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Survey on Blockchain-based IoT
Payment and Marketplaces
AMILA SAPUTHANTHRI1, (Member, IEEE), CHAMITHA DE ALWIS2, (Senior Member, IEEE)
and MADHUSANKA LIYANAGE.3, (Senior Member, IEEE)
1he Department of Electrical and Electronic Engineering, University of Sri Jayewardenepura. (amila.saputhanthri@dialog.lk)
2The Department of Electrical and Electronic Engineering, University of Sri Jayewardenepura. e-mail: (chamitha@sjp.ac.lk)
3The Center for Wireless Communications, University of Oulu, Finland and the School of Computer Science, University College Dublin, Ireland.
(madhusanka.liyanage@oulu.fi, madhusanka@ucd.ie)
This research was supported by the Academy of Finland under 6Genesis Flagship (Grant No. 318927) project and by the Science
Foundation Ireland under Connect Center (13 RC/2077_P2) project.
ABSTRACT The ever-growing smart applications will expand the Internet of Things (IoT) ecosystem
to connect over 75 billion devices by 2025. IoT ecosystems comprise sensors that act as data suppliers
and applications where monetary transactions are required to compensate the data producers. This signifies
the importance of IoT payments and marketplaces to facilitate micro-transactions of billions of connected
devices in the IoT ecosystem, which is heterogeneous, decentralized, and diverse. However, realizing such
an ecosystem raises multiple challenges such as overcoming poor inter-operability, resource constraints,
and security and privacy vulnerabilities of IoT devices and platforms. Blockchain is a Distributed Ledger
Technology (DLT) that can be identified as a potential solution to overcome the challenges in realizing
IoT payments and marketplaces. This is due to the characteristics of blockchain such as decentralization,
traceability, immutability, and non-repudiation. This paper presents a comprehensive survey on blockchain-
based IoT payments and marketplaces. This paper provides a brief introduction to the concepts of IoT
payments and IoT marketplaces. Then the technical challenges involved in realizing IoT payment and
marketplaces are discussed by highlighting the blockchain-based solutions. Furthermore, blockchain-based
smart applications which use IoT marketplace and IoT payment concepts are presented marking the role of
blockchain in each of the application. Subsequently, the paper discussed the integration challenges while
also highlighting possible solutions. It is envisaged that this paper would shed light on the development of
blockchain-based solutions to realize IoT payments and marketplaces.
INDEX TERMS Internet of Things, IoT payment, IoT marketplace, Blockchain, Smart Contracts,
Decentralization
I. INTRODUCTION
The number of devices connected to the Internet of Things
(IoT) is expected to grow beyond 75 billion by 2025, record-
ing an increase of more than 50 billion devices within the
next five years [1]. Internet-connected devices communicat-
ing with each other were initially referred to as Machine to
Machine (M2M) communication-based device networks [2].
These M2M networks have evolved towards IoT connecting
heterogeneous devices that can communicate with each other
using various protocols over the internet to exchange a wide
range of information [3]–[6]. IoT is further enhanced together
with the dawn of the Internet of Everything (IoE), which fa-
cilitates the interactions among people, devices, and data [7]–
[9].
IoT systems connect various smart objects mounted with
sensors actuators and software systems. They sense and
collect information from the physical environment and then
take necessary actions on them. A typical IoT system consists
of three main layers. They are a perception layer with various
IoT devices, sensors, and actuators to sense data, a commu-
nication layer with various wired and wireless modules to
transmit the sensor data, and an industrial application layer
with various smart industry verticals. The general IoT archi-
tecture of the latest IoT systems consists of an application
layer, cloud computing layer, network layer, fog layer, and
object layer is shown in Figure 1. The cloud computing
and the fog layers are the major additions to the initial IoT
architecture [10].
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TABLE 1. Summary of Important Acronyms
Acronym Definition
5G Fifth Generation
AI Artificial Intelligence
AV Autonomous Vehicles
BDA Big Data Analytics
BP Block Producers
BTU Bitcoin Unlimited
DAG Directed Acyclic Graphs
DLT Distributed Ledger Technique
DPoS Delegated Proof-of-Stake
DS Double Spending
DSO Distribution System Operator
EHR Electronic Health Records
ESS Energy Storage System
HPBC High-Performance Blockchain Consensus
ICT Information and Communication Technologies
IoE Internet of Every-things
IoT Internet of Things
IoV Internet of Vehicles
ISO International Organization for Standardization
ITU International Telecommunication Union
LN Lightning Network
M2M Machine-to-Machine
M2P Machine-2-Peer
ML Machine Learning
mMTC massiveMachine-Type-Communication
P2P Peer to Peer
PKI Public Key Infrastructure
PoS Proof-of-Stake
PoW Proof of Work
SCC Storage Compression Consensus
uRLLC ultra-reliable-Low-Latency-Communication
Application
layer
Cloud
Computing
Network
layer
Fog
layer
Smart object
layer
Sensors
Actuators
Mobile
apps
Data analytics
tools
sensor data
upload
Communication
medium
Network
Cloud
resources
data
upload
reply
app
data
reply reply
FIGURE 1. IoT architecture.
The world is experiencing the 4th industrial revolution
together with the advancements in IoT and Information and
Communication Technologies (ICT) [11], [12]. Moreover,
recent developments in 5G mobile communication also fa-
cilitates the development of IoT through ultra-reliable-Low-
Latency-Communication (uRLLC) and massive Machine-
Type-Communication (mMTC) [6], [13]–[16]. Therefore,
IoT enabled smart industries are expected to exhibit an ex-
ponential growth [17], [18].
The conventional computer-aided industries are getting
converted into smart industries that makes data driven deci-
sion making based on IoT and Big Data Analytics (BDA)
concepts [19]. IoT application areas such as agriculture,
utilities, healthcare and transportation are expected to be
converted into smart IoT applications [20]. Sensor networks
have automated and improved the efficiency of agricultural
practices [21]. Smart city concept will be supported by the
utility meters which will be deployed worldwide as smart IoT
systems. Smart healthcare systems will utilize latest techno-
logical advancements to perform critical remote surgeries as
well. Connected cars is the next revolution in transportation
sector.
IoT systems connect various smart objects mounted with
sensors actuators and software systems. A typical IoT system
consists of three main layers including, a perception layer
with various IoT devices including sensors and actuators to
sense data, a communication layer with various wired and
wireless modules to transmit the sensor data, and an indus-
trial application layer with various smart industry verticals.
The general IoT architecture which is suitable for describing
the latest IoT systems consists of an application layer, cloud
computing layer, network layer, fog layer, and object layer is
shown in Figure 1. The cloud computing and the fog layers
are the major additions to the initial IoT architecture [10].
IoT has the following features [22]:
•Heterogeneity of IoT data - IoT systems consist of
heterogeneous IoT devices, communication protocols,
and IoT data types [23].
•Decentralization of IoT systems - IoT systems should
be capable to exchange, make use of information and
collaborate with each other
•Diversity of IoT ecosystems - Sensors, actuators, and
software systems used in one IoT system to the other
varies a lot.
These characteristics of IoT has resulted in bellow chal-
lenges [22]:
•Heterogeneity of IoT system – The variation of the
devices, communication protocols, etc. have created
complex networks and paved the way to many other
challenges [23].
•Poor interoperability – Due to the decentralized and
heterogeneous nature of the IoT systems, it is chal-
lenging to exchange information among different IoT
systems [24].
•Resource limitations of IoT devices – IoT devices con-
sist of limited computing, storage, and power resources.
Therefore, the companies are forced to have large-scale
cloud infrastructure projects [25].
•Privacy and security vulnerabilities – Exchanging IoT
data with cloud-based IoT platforms, authentication of
vastly decentralized IoT devices using limited resources
in IoT devices have created privacy and security con-
cerns [26].
The IoT devices constantly request data from other devices
as a service. This ecosystem requires monetary transactions
to be performed by sensors and devices in exchange for
data services. These transactions and exchanges occur mainly
over an internet-based network. Conventional payment mod-
els rely on a trusted third-party such as a bank, during
transactions. However, considering the number of transac-
tions that can occur with billions of IoT devices and the
prevailing trust issues, centralized payment systems will not
be able to handle the smart industry predictions. Also, in
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the IoT ecosystem, devices need to communicate regularly
over the internet to exchange information. Malicious attacks
from internal or external sources are common during the
process. Therefore, at the first gateway to the network, an
authentication mechanism that can secure the identity of the
IoT devices in the network is essential [27].
The data growth rate in the IoT domain has increased
with new devices, sensors, and emerging technologies. The
enormous amount of data generated by these IoT applications
has enforced companies to deploy large-scale cloud storage
solutions. The emerging smart industries need to predict and
adapt their solutions based on the insights received from
sensor data. Therefore, a trustworthy neutral data-sharing
platform is required for the data producers and consumers
to trade [28]. These data streams generated by the IoT de-
vices have a resell value to third-party buyers as well. The
unavailability of a clearly defined framework for the business
side of the IoT ecosystem is negatively impacting its growth.
Therefore, a clear business model framework needs to be
defined for the IoT data trading.
Blockchain is a widely used DLT that is decentralized in
nature and continuously grows along with the executed trans-
actions. When a transaction is executed, a new block creation
request is initiated. Then, all the nodes in the blockchain
network initiate the process of block validation, A validated
block will be added to the end of the blockchain by inverse
reference pointing to the parent block. This block validation
process prevents any alterations to the existing blocks in
the blockchain as the malicious party needs to change the
relevant block of each node in the network. The key charac-
teristics of blockchain such as decentralization, immutability,
trustworthiness, and non-repudiation have made it an ideal
candidate for applications that require secure but anonymous
and immutable transactions [22]. Due to these characteris-
tics, blockchains have the potential to mitigate the existing
issues and revolutionize IoT payments and IoT marketplace
concept.
•IoT payments - Due to the distributed nature of
blockchain technologies, P2P transactions without
third-party involvement can be performed. Therefore,
the bottleneck of having a central authority due to
its cost and performance issues can be mitigated by
validating the transactions by a decentralized mecha-
nism. Individual nodes in the blockchain keeps all the
committed transaction details and its immutable. The
cryptographic mechanisms in blockchain guarantee the
integrity and enable secure payments. Also it helps with
other issues caused by third parties in IoT financial
transactions, namely the lack of anonymity for the users
and additional security risks.
•IoT marketplace - Global IoT data market value will
reach over USD 1 trillion by 2026 [29]. There are
several IoT data marketplaces that have already been
deployed for selling and buying IoT data. But, the
unique characteristics of IoT data have created technical
challenges for the success of those platforms. A neutral
platform that can be trusted by both the data suppliers
and the consumers is essential for the success of IoT
market. Blockchain can be used as the base technology
to create such a digital trading platform. Further, it can
allow IoT device owners to monetize any transaction or
exchange data among the devices as a reward instead of
a monetary transaction.
The use of third parties for IoT-related financial transac-
tions creates issues such as lack of anonymity and security
concerns. When the growing hacking attempts on internet-
based platforms are considered, users don’t prefer to share
their credit card information or storing their transactions
history in IoT marketplaces. When a third party is involved,
it leads to an increased transaction fee, also. This is a major
concern considering the small-scale micro-transactions that
occur in IoT systems. We can use blockchain-based platforms
to develop anonymous solutions and remove third parties in-
volved in centralized systems. On the other hand, transaction
fees can be an issue in blockchain technology as well. But,
the research community is attempting various mechanisms to
resolve this issue using the latest DLTs.
The data generated by IoT are tradeable assets that can
be even sold to third-party buyers as well. The traditional
marketplaces are generally used to share static data. But,
the IoT ecosystem requires near-real-time data streams to
utilize its actual potential. It requires efficient ways to avoid
the initial data consumers from reselling the data without
the consent of the data supplier as well. Therefore, mutual
trust will be a key component in the IoT marketplace and
dynamic trade agreements are required among the parties.
The IoT marketplaces do not always consist of trusted parties
and smart contracts can be used as a trusted intermediary to
create reliable transactions. Datum [35] is a smart contract-
based blockchain that provides an option to securely store
structured data in decentralized storage. But, this doesn’t
address the real-time data requirement of IoT applications.
Any IoT data producer should be able to trade the generated
data in an IoT marketplace [36].
Blockchain is an ideal candidate to address many of the
unique challenges observed in the IoT domain [37]. But,
there are obstacles that blockchains in IoT implementation
should overcome to be the paradigm shift in the IoT domain.
The need to pay a transaction fee to reward miners for
their time and efforts is a major obstacle. The market-based
transaction fees concept used in typical cryptocurrencies is
quite expensive and not suitable for IoT transactions. The
transaction time of blockchains is another problematic issue.
IoT payment systems require many microtransactions to be
completed within seconds. But, public blockchains such as
Bitcoin, Ethereum and Ripple require each block be vali-
dated by the global blockchain [32]. Bitcoin Lightning Net-
work (BLN), virtualized DLTs (vDLTs) and alternative DLT
technologies such as Directed Acyclic Graphs (DAGs) are
some examples for research attempts to improve blockchain
technology to make it suitable for IoT applications. Even
though blockchain needs further optimizations to make it
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TABLE 2. Summary of important surveys on IoT payments and Marketplaces
Ref.
Technical Challenges of IoT Market Places
Technical Challenges of IoT Payment
Blockchain-based IoT Market Places
Blockchain-based IoT Payment
Blockchain-based IoT Application
Blockchain Implementation Challenges
Future Directions
Remarks
[30] M L M L H L M A survey on the IoT marketplace for smart IoT solutions, relevant application domains and the
technologies used.
[31] M M L L H L M A review on the use of blockchain for IoT.
[22] M M L L H H L A survey on blockchain for IoT and introduces a proposal for a BCoT architecture to converge
blockchain and IoT.
[32] L M L H L M L A survey on IoT payment systems highlighting the blockchain-based solutions and its limitations.
[33] L L L L M L M A survey of IoT security challenges and blockchain solutions to address them.
[34] L L L L L H M A detailed analysis of security concerns of blockchain and existing solutions to address the issues.
This H H H H H H H This survey .
LLow Coverage MMedium Coverage HHigh Coverage
an ideal IoT payment and marketplace platform, the already
available research results indicate that blockchain based IoT
payment and marketplace concepts can revolutionize the IoT
ecosystem.
A. MOTIVATION
As per the summary of surveys given in Table 2, already
available surveys discussing IoT payments and IoT market-
places based on blockchain is very limited. Perera et al [30]
has done a survey of the IoT solutions in the emerging mar-
ketplace by discussing and summarising the functionalities
provided by each solution.
Enser et. al. [32] examine the compatibility of blockchains
for IoT payment transactions by highlighting the character-
istics that have made blockchain an ideal solution for P2P
transactions between IoT data producers and consumers.
Further, this research paper discusses the integration chal-
lenges of blockchain to achieve fast and cheap IoT-related
transactions as well. Ozyilmaz et al [28] analyze the positive
impact of establishing a decentralized and trustless platform
for IoT data sharing. The writers have developed a proof-
of-concept data marketplace using Ethereum and Swarm.
Shaimaa Bajoudah et al [38] proposed a decentralized mar-
ketplace to trade brokered IoT data. Also, Wiem Badreddine
et al [39] introduce an IoT data marketplace with three dif-
ferent models using MQTT as the publish/subscribe method,
Ethereum as the DLT, and Solidity as the smart contract.
B. OUR CONTRIBUTION
Even though, the existing research and survey papers sum-
marize the possible usage of blockchain for IoT, an extensive
survey has not been done to research specifically on possible
avenues for blockchain to resolve IoT payment challenges
and cater market place requirements with the expected IoT
boost that will be initiated by smart industries.
This paper aims to
•Introduce the blockchain-based platforms - The con-
cepts related to blockchain and smart contracts are sum-
marized. Further, the blockchain-based platforms are
introduced.
•Thoroughly analyze the usage of blockchain for IoT
applications - The blockchain-based IoT solutions are
discussed.
•Examine the IoT payment related issues and the
requirement for an IoT market place - The concept
of IoT payments and blockchain-based IoT payment
solutions are discussed in detail.
•Discuss the suitability of blockchain based IoT pay-
ment system and IoT market place - The concept
of IoT market places and blockchain-based IoT market
place solutions are discussed in detail.
•Discuss technical challenges of IoT - The technical
challenges of IoT solutions are introduced and the role
of blockchain in solving those challenges are analyzed.
•Discuss the integration challenges of blockchain -
The unique challenges of blockchain integration are
discussed.
C. OUTLINE
The remainder of the paper is organized as follows. Section
II first presents an overview on blockchain and smart con-
tracts. Section III summarizes the payment and market place
requirements for IoT. How the payment and market place
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challenges can be addressed by blockchain is discussed in
Section IV. Available IoT payment systems and IoT market
place options based on blockchain are discussed in Section V
and VI respectively. Section VIII introduces the integration
challenges of blockchain. Lessons learned and open research
issues are discussed in Section IX. Finally, the paper is
concluded in Section X.
II. BLOCKCHAIN AND SMART CONTRACT
In this section, we first discuss the summary of blockchain
technology, then summarize the key blockchain characteris-
tics. Further, we introduce the IoT application areas and how
blockchain is introduced for those IoT applications.
A. BLOCKCHAIN SUMMARY
Blockchain is a DLT that keeps a record of transactions in a
transparent, auditable, and immutable manner. Block, chain
and network are the three core parts of a blockchain. It stores
transactions in a chain of blocks while using cryptographic
mechanisms [47]. Except for the first block, each block in a
blockchain point to its immediately previous block (parent
block) using the inverse reference of the parent block (hash
value of the parent block) [48]. The first block of a blockchain
which is known as the genesis block doesn’t have a parent
block. A block structure consists of the following informa-
tion:
•Block size - the size of the block in bytes
•Block header - contains block version, a reference to
a previous block hash, merkle tree root, mining-related
parameters, and nonce
•Transaction counter
•Transactions
A blockchain grows with the executed transactions and all
the nodes in the network validate the newly generated blocks.
Then, it will be appended at the end of the blockchain [22].
Key characteristics of blockchain include:
•Decentralization - The decentralization feature of
blockchain distributes the authority among all nodes in
the network. This ensures the redundancy of the system
when compared with the centralized system approach
which requires a trusted third party to operate. High
availability of services, improved trust and reduced fail-
ure risk are the benifits provided by decentralization.
•Immutability - The transactions stored in the ledger
are permanent and distributed among the nodes. There-
fore, they are unalterable. This immutable nature of
blockchain ensures the integrity of the data stored in the
ledger [49].
•Enhanced security - Due to the decentralized nature
of blockchain, any fraudulent party who wants to alter
the blocks needs to alter the data stored in all nodes in
the network. Encryption mechanisms are used to further
enhance security and the cryptographic hash is used in
the blockchains as well [50].
•Consensus - Conses algorithms are considered as one
of the core concepts of blockchain which has made
the network being trustless [51]. This is a decision-
making process performed by the blockchain nodes in
the network to validate the transactions. Even though the
nodes in a blockchain don’t trust each other, they trust
the transactions validated by the consensus algorithm.
B. SMART CONTRACT
Smart contracts are programs stored in a blockchain that
are executed when a predefined condition is satisfied [52].
They execute the terms of a contractual agreement using
computerized transaction protocols [53]. The first implemen-
tation of a smart contract on the blockchain is Bitcoin. Later,
Etherium developed a wide variety of smart contracts on a
blockchain [54]. The contractual terms in smart contracts are
enforced automatically when given conditions are satisfied.
These enforced contractual terms are converted to executable
computer programs while preserving the logical statement
flows. Once, a smart contract is executed and stored in a
blockchain, it is immutable and cannot be modified [22].
Smart contract solutions are used in various IoT applications
such as healthcare, manufacturing, and finance [47].
C. IMPORTANT BLOCKCHAIN PLATFORMS
A comparison of important blockchain platforms is given in
Table 3. Blockchain platforms can be categorized into four
different types. They are
•Public blockchain - permissionless and anyone with
internet access is allowed to become a node in the
network which can validate the transactions based on
the consensus algorithm used. Eg. Bitcoin and Ethereum
•Private blockchain - permission blockchain and net-
work access are restricted only to authorized users. Eg.
Multichain and Hyperledger Fabric
•Consortium blockchain - this is known as a federated
blockchain where multiple organizations can govern the
blockchain network. So, this is different from the private
blockchain. Eg. R3
•Hybrid blockchain - a hybrid of both centralized and
decentralized features where some processes are kept
public and others private based on the transaction which
can be shared in the public network. Eg. Ripple
1) Bitcoin
Bitcoin is a widely used, virtual currency developed based
on the concept of cryptocurrency [55]. The validated bitcoin
transactions using PoW consensus is updated in a public
ledger. Firstly, the transactions generated in a given period
will be sorted and stored in a block. Then, the newly gen-
erated block will be added to the blockchain using inverse
referencing method after it is validated by the other nodes
in the public blockchain [56]. Bitcoin operates over a P2P
network and it is vulnerable to decentralized network attacks
such as the double spending attacks [57].
2) Ethereum
Ethereum is an open-source blockchain solution based on
the concept of smart contracts [32]. Ethereum uses a pro-
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TABLE 3. Blockchain and smart contract platforms and also more features
Platform Platform
type
Transaction
fee
Transaction
count
Consensus Related work
Etherium Public 4 USD
(Varies)
20 TPS PoW IoT Data Marketplace on Blockchain [28].
Hyperledger
Fabric
Private Free 2000 TPS Orders and
endorsers
Norwegian Seafood Traceability Network, My Sensor, VideoCoin Net-
work [40], Carbon market [41].
Quorum Private Free 100 TPS BFT Financial services [42]
EOS Public Free 1,000 - 4,000
TPS
DPoS Gaming solutions [43]
Cardano Public 0.05 USD
(Varies)
257 TPS Ouroborous Smart agriculture solution [44]
Ardor Public 1 ARDR 12 TPS PoS Loyalty reward solution - Triffic solution rewards people with tokens
for visiting local neighborhoods [45]
Ark Public 0.1 ARK 18 - 19 TPS DPoS Financial tools - Payvo is a financial tool for crypto-based activities [45]
IOTA Private Free 250 TPS Tangle Smart City Solutions [46]
gramming language - solidity, decentralized storage service
- swarm and the cryptocurrency - ether [28]. It used PoW as
the consensus algorithm and later changed to PoS due to the
transaction throughput related concerns of PoW [58]
3) Hyperledger Fabric
Bitcoin and Ethereum are famous due to the usage of bit-
coin and ether as cryptocurrencies. But, Hypeledger is also
gaining popularity, and the software development sector has
started using it due to the promising results shown over
other competing blockchain platforms [59]. It is an open-
source community effort to develop a set of frameworks
for industry-level blockchain deployments [60]. Hyperledger
fabric is an enterprise-grade DLT platform that is developed
to support industry use-cases that require a permissioned
network with high scalability and security [61]
4) IOTA
IOTA uses tangle which is a DAG-based DLT technology
[62]. IOTA platform is developed to address the IoE require-
ments by enabling a decentralized IoT data marketplace [28].
IOTA tangle is not a typical blockchain with blocks, chains,
and miners. Instead, it uses directed graphs technology to
cross-check one another and entangle the steam of trans-
actions together [32]. IOTA platform promises to provide
essential characteristics required by IoT.
5) Other platforms
•EOS - EOS is an open-source platform for blockchain-
based applications which can be deployed as a public
or private network [63]. It uses Delegated Proof-of-
Stake (DPoS) consensus algorithm to validate block
producers and EOS token as the cryptocurrency [64].
Smart contracts and decentralized autonomous applica-
tions (dApps) are also used as core technologies.
•Cardano - Cardano is a DLT system that supports
smart contracts and dApps. Cardano uses Proof-of-
Stake (PoS) algorithm known as Ouroboros [64]. This
is the first blockchain platform that was founded based
on peer-reviewed research [65].
Smart Health
Content Trading
Smart Manufacturing
Smart Energy
IoV
Smart Cities
Blockchain
ecosystem
Immutability
Decentalization
Trustless
but auditable
Non-repudiation
Verification based
on consensus
Pseudonomitiy
Transparency
Enhanced-
security
Anonymity
Cryptographically
secured digital
ledger
Smart Agriculture
Required features
PU/ PR/ HY/ CO
IM, ES, TR, AN, NR
TW, AU
Required features
Features enabled by blockchain for IoT
IM - Immutability
ES - Enhanced security
TR - Transparency
AN - Anonymity
NR - Non-repudiation
TW - Trustworthiness
AU - Auditability
Blokchain types
PU - Public
PR - Private
CO - Consortium
HY - Hybrid
Required Features
PU/HY
IM, ES, TR, AN, NR
TW, AU
PR/ HY/ CO
IM, ES, TR, AN, NR
TW, AU
PR/ HY/ CO
IM, ES, TR, AN, NR
TW, AU
Required Features Required Features
Required Features
PU/HY
IM, ES, TR, AN, NR
TW, AU
Required features
PU/ PR/ HY/ CO
IM, ES, TR, AN, NR
TW, AU
PU /HY/ CO
IM, ES, TR, AN, NR
TW, AU
FIGURE 2. Blockchain-based solutions for IoT
D. BLOCKCHAIN FOR IOT
IoT systems mainly consist of three major components:
sensors, computation engine, and actuators. The actual im-
plementation of sensors, computation mechanism, and ac-
tuators vary based on the IoT application [66]. The IoT
implementations are suffering from technical challenges to
achieve their true potential. Blockchain characteristics show
a promising future to address the IoT challenges and take
IoT applications to the next level. Hence, the convergence of
blockchain and IoT has the potential to be the next paradigm
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in IoT application domain [22]. The Figure 2 summarises the
features that will be enabled by blochain for IoT applications.
1) Smart manufacturing
The conventional manufacturing industry is getting upgraded
to smart manufacturing. During a product life cycle, a large
amount of data is produced, and BDA-based IoT applica-
tions are heavily used [67]. Raw material, Manufacturing
equipment, warehouses, and almost everything thing in-
volved in a product life cycle needs to exchange IoT data.
Therefore, blockchain-based solutions are suitable for smart
manufacturing-related IoT applications and IoT marketplace
requirements [68].
2) Smart agriculture
Smart agriculture applications use technologies such as BDA,
cloud computing, IoT sensors to monitor and automate farm-
ing operations. Agricultural requirements need IoT applica-
tions to install sensors in the land, irrigation systems, weather
stations, logistic facilities, and even in seller locations. This
is a complex IoT eco-system that can vastly benefit from
blockchain IoT applications and IoT marketplace [44], [69],
[70].
3) Smart energy
Smart energy applications are observed in various societal
domains such as domestic needs, commercial applications,
and other industry requirements. A smart grid is a key smart
energy requirement where an electricity network is deployed
to detect and react based on energy usage and observed issues
to heal them. These applications need to coordinate with mul-
tiple parties in the eco-system such as consumers, consumer
equipment, power generation, and distribution equipment,
administrative and payment systems. Therefore, blockchain-
based IoT solutions have the opportunity to resolve the
challenges in smart energy applications while creating an IoT
marketplace [71]–[75].
4) Smart health
Healthcare-related applications should be dealt cautiously as
it involves human life. The healthcare sector includes hos-
pitals, health staff, patients, health equipment, logistics, etc.
Therefore, IoT applications need to integrate all these sectors
to provide solutions such as patient monitoring, health record
maintenance, system automation, and disease predictions.
Blockchain-based smart health applications can address strict
security concerns related to the healthcare sector and deploy
an IoT marketplace solution to allow health data sharing
requirements as well [76]–[79].
5) IoVs
IoV needs to integrate vehicle networks with other vehicle
networks, roadside networks, infrastructure networks, and
pedestrian networks to function. Therefore, IoV applica-
tions need to exchange sensor data and obtain feedback for
users, manufacturers, etc. where an IoT marketplace would
also require. Blockchain-based IoV applications have shown
promising results to resolve the current IoV challenges and
to provide a truly decentralized solution [80].
6) Other IoT Application
The other IoT application domains include transportation,
supply chain and retail sector. The concept of IoE has enabled
things, processes, data and people to create various IoT
domains together. These IoT domains require IoT payments
to handle micro-transactions and IoT marketplaces to enable
data sharing applications.
IoT applications are expected to be the next paradigm,
but the IoT application predictions have not yet been met
due to the technical challenges observed during practical
implementations. Blockchain-based solutions provide a trust-
worthy neutral platform for IoT applications to overcome
the technical challenges prevailing currently. Blockchain it-
self needs improvements to handle IoT transaction expecta-
tions. But, the current research shows promising results with
blockchain-based IoT solutions mainly in the IoT payment
and marketplace application domains.
III. IOT MARKETPLACE
IoT systems use sensors that are capable of sensing the
relevant conditions, platforms that can process the collected
data, and devices that can function as actuators based on
processed data. These IoT eco-systems use cloud computing
concepts such as Software as a Service (SaaS), Platform
as a Service (PaaS), Infrastructure as a Service (IaaS), and
emerging concepts such as Sensing as a Service. The IoT
platforms require sensor data to function. Therefore, the data
consumers are waiting to obtain the sensor data over the
internet and they are willing to pay for the obtained sensor
data as well.
Data Suppliers Data consumers
Blockchain based IoT
marketplace
API layer
Blockchain
platform
Cloud
storage Application
users
Smart
contract
Distributed
ledger
Consensus Cryptography
Crypto-currency
Sensors
Gateways
Local
storage
Fog layer
API layer
Distributed
storage
Company X -
Eg: smart
health
Company Y -
Eg: IoV
Data
Anaytics
Application
GUI
Developers
IoT
applications 3rd
parties
Standardization
consumer data
standards
IoT
devices
Data
Storage
Supplier to consumer data flow
Regulators
sensor data
supplier data
regulations
FIGURE 3. IoT data marketplace architecture
The concept of the IoT marketplace has become an essen-
tial component in modern-day smart application ecosystems.
The IoT marketplace value by 2030 is predicted to be over
USD 3 trillion [81]. Further, more than one million organiza-
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tions are expected to use IoT marketplaces to monetize their
data. This will generate more than 12 exabytes of IoT data
sets for the transactions performed daily [81]. BDEX [82]
is a Data as a Service (DaaS) platform established in 2014
to provide actionable data for companies. DAWEX [83] is
another global data exchange platform established in 2017 to
monetize the generated data.
An IoT data marketplace mainly consists of three com-
ponents. They are data suppliers, data consumers and the
platform to handle the data marketplace.
•Data suppliers - They are the data owners. IoT devices
such as smart home appliances, smart watches, weather
stations and health monitoring devices are a few exam-
ples for the commonly used IoT data suppliers which
generate data.
•Data consumers - They are the parties who are willing
to purchase and use the data generated by the data
suppliers. Research institutions,smart applications such
as IoV and marketing agencies are a few examples for
IoT data consumers.
•Data platform - It is required to handle the enormous
amount of data generated by IoT sensor applications
and share the data among the data consumers. Both
the data consumers and suppliers need to register in
this platform. Then based on the requirement of the
data consumer, the platform should handle any relevant
transaction fee and distribute data as per pre-defined
policies that can be agreed by both the parties.
Figure 3 shows an IoT data marketplace architecture that
can be used to share the generate IoT data among the required
consumers. The registered IoT sensors generate IoT data and
act as the data suppliers. The type of IoT data generated and
the relevant compensation details must be updated during the
registration process. The consumers need to compensate the
suppliers and obtain the generated data.
A. KEY CHALLENGES IN CURRENT IOT
MARKETPLACES
Data consumers and data suppliers seamlessly trade in an
IoT marketplace. This allows companies to make use of both
publicly available data and privately-owned data for their
use cases. But IoT when creating an IoT marketplace, below
mentioned challenges can be observed.
•Lack of cooperation among IoT platforms - It is
challenging to exchange data between different IoT sys-
tems, due to the inherent nature of being decentralized
and heterogeneous. Hence, the interoperability of IoT
platforms is challenging to be achieved while results in
data silos.
•Requirement of a trusted third party - Currently, the
normal practice is to compensate the IoT data suppliers
using a trusted third party such as a bank. When the
micro-transactions that occur in the IoT ecosystem are
considered, transaction fees and the centralized mecha-
nism are not efficient approaches.
•IoT devices specific technical challenges - Limited re-
source availability is a common feature in IoT systems.
Hence, the typical authentication and authorization ap-
proaches cannot be implemented and the systems are
vulnerable to security threats.
B. ROLE OF BLOCKCHAIN FOR IOT MARKETPLACES
The contributing parties have multi-dimensional benefits
from a decentralized IoT data marketplace.
1) Technical benefits
•No need to maintain backend IoT platforms - The IoT
data marketplace will act as the backend to integrate the
sensors and the IoT applications.
•Availability of a vast pool of IoT data - IoT applications
have insights from a pool of sensors. So, individual data
silos with limited insights aren’t getting created.
•Optimized software for IoT sensors and applications -
The IoT data marketplace is responsible for integrating
the consumers and the suppliers. Therefore, the relevant
software code or other application configurations that
should run in sensors and IoT applications can be stan-
dardized.
•Actionable insight reselling capability - The data con-
sumers can obtain raw data and further improve them
into actionable insights and sell them to other interested
third parties. Since we have a common IoT data mar-
ketplace, it is possible to compensate the original data
suppliers.
2) Economical benefits
•IoT data monetization for data suppliers - New set of
business models involving sensor data generators, data
consumers will create more diversified IoT application
use cases.
•Reselling IoT data with added value - The data obtained
by data consumers can be resold after converting them
into actionable data insights.
•IoT data economy - Even though it is predicted that
IoT applications will revolutionize the world, only data
silos are getting created. An IoT data marketplace will
allow the true potential of IoT data monetization to be
achieved.
The functional block diagram of a blockchain-based IoT
marketplace varies based on the technologies used and a
general block diagram is given in Figure 4. Let’s analyze
the already deployed similar solutions based on previous
research.
Kazım Rıfat Özyılmaz et al [28] introduced a decentralized
and trustless data marketplace platform for non-real-time and
non-critical IoT applications to store and access IoT data.
They highlight the fact that on-chain or off-chain data storage
mechanism, monetization method and suitable tools and ca-
pabilities to create an IoT platform are the key considerations,
when creation an IoT marketplace. The blockchain used
is Ethereum and the decentralized storage used is Swarm.
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Buyer Seller
Distributed File Storage
Smart contract for
payments
Smart contract for
reviews
Smart contract for IoT
data
Blockchain
solutions
Store
IoT data
Obtain
IoT data
Share
IoT data
Request
IoT data
Pay for
IoT data
Receive
payments
Off chain IoT data sharing
requirements
Review
IoT data
Buyer
FIGURE 4. Functional block diagram of blockchain-based IoT data
marketplace
Smart contract is used for transparent data collection sharing
to implement the decentralized IoT data marketplace. It is
important for the data consumers to know the geolocations.
Hence, GeoHex is used to facilitate easy querying of geolo-
cations. A validation and feedback mechanism is used to rank
the quality of IoT data, based on consumer feedback. Ether is
used as the monetizing method. A off-chain scaling solution
called payment channels (Raiden for Ethereum) is used to
support instant transactions.
Gowri Sankar Ramachandran et al [84] propose a de-
centralized marketplace for smart cities. Sellers with data
products and buyers interested in their data are fundamental
components in the data marketplace. They have used smart
contracts to register sellers and post data products for the buy-
ers to search and find them. In this implementation, Ethereum
blockchain is used along with an off-chain distributed file
storage system named InterPlanetary File System (IPFS).
Meta-data organization is proposed to follow any standard
JSON format. Streaming Data Payment Protocol (SDPP) is
used to enable real-time micropayments. The rating process
of buyers and sellers in the marketplace is implemented using
a smart contract as well.
Pooja Gupta et al [85] proposed a three-tiered architecture
consists of participants of the marketplace, facilitators to
supervise service areas, and regulators to ensure that the facil-
itators are adhering to the privacy regulations. IoT devices are
resource-constrained, so facilitators ease the burden on those
devices by acting as fog nodes. They used BigChainDB, a
decentralized database system to maintain IoT system data.
A blockchain named Martchain is built using Ethereum and
smart contracts are executed to automate the trading. A
watermarking technique is used to identify reselling of data
and compensate the data suppliers. The regulators form a
consortium blockchain named policy-chain to validate the
compliance of facilitators by executing a policy contract, a
smart contract.
Wiem Badreddine et al [39] developed a blockchain-based
IoT data monetization framework. They use Message Queu-
ing Telemetry Transport (MQTT) protocol and Ethereum
smart contract to build three different real-time IoT data shar-
ing solutions. The overall system architecture consists of a
smart contract, publishers who provide IoT data, subscribers
who consume IoT data, and an untrusted MQTT broker to
connect the publishers and subscribers. They propose three
solutions; Trace-MAX provides maximum traceability by
asking the participants to write detailed information in the
distributed ledger. Trace-MIN is the minimum traceability
solution that required only the brokers to record minimal
information allowing only a basic trace. Trace-BF uses bloom
filters to manage data hashes with fewer verification opera-
tions on the blockchain.
IV. IOT PAYMENTS
In an IoT ecosystem, based on the application the devices use
various technologies to generate, communicate and analyze
data. The interaction among people. devices and data are
called the Internet of Everything (IoE) [32] nowadays. IoE
needs the ecosystem to perform monetary transactions in
exchange for services over the internet. The introduction of
5G technology is expected to further grow the potential use-
cases of IoE.
IoT payment requirements are generated by various IoT
verticals. Some of the example scenarios would be a smart
car authorizing fuel payments as it approaches the fuel
station, a smart health device sharing the prescription with
a smart pharmacy, and proceeding with the drug purchase,
and a smart agricultural applications ordering and paying
for fertilizer and water supplies. M2M transaction value is
expected to reach USD 27.62 billion by 2023 [86].
•Smart cities - The concept of cashless cities can con-
nect any object to smart city network and eliminate
the inefficiencies of payment mechanisms that can be
observed in current systems. A research done by Visa
in 100 cities shows that smart payment mechanisms can
provide USD 470 billion in direct net benefits per year
[87].
•Smart homes - Modern day houses contain devices
with embedded financial functionalities. Automated
utility payments and automated supply ordering are a
few examples where IoT has enabled pay-per-use busi-
ness models and service offerings.
•Smart transport - The latest connected cars have in-
built payment functionalities for everything from gas
to parking and infotainment. Similar functionalities are
introduced to the whole eco system of smart transporta-
tion. As an example, Honda and Visa together have
introduced infotainment system that allows users to pay
gas, parking, food, etc [87].
•Smart retail - IoT payments have created a subdivi-
sion of commercial activities where unattended retail
is becoming more common. Amazon’s new cashless,
cashier-less stores which allow customers to collect
items off shelves and automatically get charged upon
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TABLE 4. Blockchain solutions for IoT payments and marketplaces
Challenge of ex-
isting system
Description of the challenge Solution via blockchain Possible limitations in blockchain sys-
tem
Requirement of a
trusted 3rd party •Rely on a trusted third party to per-
form financial transactions.
•Usually, a bank acts as the trusted
third party.
•Decentralized and immutable in
nature.
•The dependency with a trusted
third party can be avoided and the
transactions will still be reliable.
•The scalability concerns in terms
of transactions and storage.
•IoT payments require a scalable
blockchain platform to handle its
continuous growth.
Lack of
anonymity
for the users
•The users need to share their pay-
ment information and
•Allow the transaction history to be
maintained in IoT applications.
•Considering the recent scandals,
users always prefer to perform trans-
actions anonymously.
•The keys used in blockchain and
the personal identifiable informa-
tion of the users can be sepa-
rated and avoid linking them via
pseudo-anonymity.
•A completely anonymous solu-
tion can lead to criminal activities.
•The right balance of anonymity
need to be carefully analyzed
based on the application with the
regulatory authorities.
Requirement of
micro-payments •IoT transactions are micro-
transactions by default
•The behavior of IoT applications
require to perform multiple sub-
transactions during a transaction.
•The conventional payment mecha-
nisms use trusted third parties
•Centralized payment systems are not
designed to handle micro-payments
•Transaction fee is increased.
•Since, blockchain is a distributed
ledger, a trusted third party is not
required.
•The transactions fees that need to
be paid to the trusted third parties
during micro-transactions can be
avoided.
•Blockchain transaction validation
via miners involves transaction
costs.
•It is a major concern in
blockchain platforms as the
IoT transaction values are very
small.
Issue of fiat cur-
rency •The use of fiat currency is common
in both developed and developing
countries.
•The cost of producing, printing, and
securing fiat currency, the ineffi-
ciency of payments and unsuitability
to digital economic needs are major
disadvantages.
•It can use crypto-currency based
payments and avoid the usage of
fiat currency completely.
•The regulatory bodies have not
yet approved cryptocurrencies.
•Usage of non-regulated and non-
standardized cryptocurrencies is a
challenge.
Static agreements
on payment rates •The traditional IoT businesses mod-
els primarily allow only static agree-
ments with IoT data suppliers.
•Due to dynamic micro-transactions
it requires dynamic payment rates.
•The decentralized blockchain
platforms enable P2P
transactions.
•The IoT data suppliers and the
consumers can perform dynamic
transactions.
•It is flexible to allow P2P data
sharing without performing a fi-
nancial transaction as well.
•Blockchain transaction fee is a
major blocking point to estab-
lish dynamic payment rate agree-
ments.
exiting. According to new estimates, this has generated
more than 50 % more revenue on average than typical
convenience stores [88].
•Smart grids - The power production, transmission and
distribution is monitored, controlled and smart concepts
such as smart metering and peer to peer energy trading
are introduced with smart grid concept [89].
•Smart agriculture - This domain mainly deals with
buyer-seller relationship in many areas including pur-
chasing seeds, sharing climate data, selling crops, agri-
culture field monitoring, etc. Therefore, IoT related
micro-payments which can vastly benefit by introducing
a distributed payment mechanism based on blockchain
is an integral part of the eco-system [69]
•Smart healthcare -Smart healthcare systems deals with
sensitive patient information and deals with various pay-
ments requirements with patients, hospitals, healthcare
staff, pharmaceutical industries etc. [90]
•Supply Chains - Supply chains related transactions are
subjected to issues such as money laundering, sanction
violations, bribery, etc. Therefore, blockchain-based
IoT payment solutions can improve the efficiency and
reduce frauds [91].
A. KEY CHALLENGES IN CURRENT IOT PAYMENTS
SYSTEMS
Conventional IoT applications deploy their own IoT ecosys-
tem with sensors and actuators with network connectivity and
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IoT platform to run the relevant control algorithms to run the
application. This has created IoT network silos for individual
applications. As a result, the capital cost of IoT application
deployments is high and the widespread use of IoT solutions
is hindered.
•Requirement of a trusted 3rd party - Traditional IoT
business models rely on a trusted third party to perform
financial transactions. An intermediary such as a bank
is used during the process and the actual advantages of
P2P transactions are not allowed to be obtained because
of this.
•Lack of anonymity for the users - IoT application
users are reluctant to share their payment information
and allow the transaction history to be maintained in IoT
applications.
•Requirement of micro-payments - IoT deals with
micro-transactions and in order to perform a single IoT
transaction, multiple sub-transactions might need to be
performed. The conventional payment mechanisms are
not designed to handle such micro-payments and using a
trusted third party has increased transaction fees as well.
•Issue of fiat currency - Even in today’s world, the
paper-based currency is used for 85% of all global trans-
actions. This is common in developed economies as
well. The usage of fiat currency in the United Kingdom,
United States, and Germany are recorded as 48%, 55%,
and 67% respectively [92]. The usage of physical fiat
currencies is a major blocking point for the advance-
ment of the IoT sector. The cost of producing, printing,
and securing fiat currency, the inefficiency of payments,
unsuitability to digital economic needs are some of the
major concerns of physical fiat currencies.
•Static agreements on payment rates - IoT required to
perform dynamic micro-transactions [93]. Due to tradi-
tional business models that are prevailing in the industry,
IoT platforms have to enter into static agreements with
IoT data suppliers. But, the data requirements of IoT
platforms are dynamic in nature. So, the latest IoT
trends urge for solutions that has the capability to handle
dynamic payment terms.
B. ROLE OF BLOCKCHAIN FOR IOT PAYMENTS
The key characteristics of blockchain include decentraliza-
tion, immutability, and enhanced security. These characteris-
tics make the blockchain technology ideal for IoT payments.
Since the blockchains are distributed, direct P2P transactions
can be performed without the need of a trusted third party.
The IoT payments can be made unalterable due to the im-
mutability provided by the consensus mechanism and smart
contracts used by blockchains. Therefore, the IoT transaction
history can not be modified or reversed.
Worldwide people have adopted electronic payments. The
consumer identity theft attempts are common and current
payment system ecosystems such as payment cards are vul-
nerable to such instances. The process of tokenization con-
verts the sensitive data into non-sensitive tokens. Therefore,
sensitive data can be secured as the original data gets replaced
with an unrelated value. Blockchain-based distributed pay-
ment systems can protect the users from identity thefts as
payment tokens can easily used in the blockchain payment
ecosystem [94].
The conventional fiat currency faces issues in currency
issuance, payment methods, and currency storage require-
ments. Therefore, digital currency usage is ivolving and the
acceptance of bitcoin by El-Salvador in June 2021 as legal
tender, is an example for the possibility of world moving
towards cryptocurrencies. Xuan Han et al [95] have analyzed
some of the major cryptocurrencies and proposed an scheme
to use digital currency during their research work.
The eco-system of blochkchain-based IoT payments is
given in Figure 5. The blockchain-based decentralized IoT
payment schemes will provide various benefits to IoT pay-
ment domain.
•No dependency with third-party payment platforms -
The traditional business models rely on a trusted third
party to proceed with payment transactions. The most
widely used mechanism is to use a third-party such
as a bank to proceed with transactions. Blockchain-
based IoT payment options have enabled actual P2P
transactions without any dependency on a third party.
•Anonymous transactions - When a third party such as
a bank is involved in the transaction process, the users
have to provide sensitive information such as credit card
information to proceed with payments. If IoT data from
multiple platforms is required, the users have to ex-
pose their sensitive payment information multiple times.
Considering the security risks involved in the current
digital era, this is not preferred by IoT data consumers.
So, using blockchain, a certain amount of anonymity
can be maintained.
•Less transaction fee - In traditional E-business models,
the transaction fee is a major issue as micro-transactions
are a unique characteristic of IoT. Blockchain-based
solutions are improved and necessary research is be-
ing done to minimize the transaction fee. Also, IOTA-
tangle-based payment approaches have introduced, pay-
ment options without any transaction fee.
V. TECHNICAL CHALLENGES OF IOT PAYMENT AND
MARKETPLACES
The traditional IoT business models used for IoT payments
and market places rely on central authority. This has created
technical challenges such as IoT data security and privacy
issues, creation of data silos without any collaboration, re-
quirement of a central payment systems, lack of anonymity
and fradulent transaction attempts. Table 4 shows how the
existing IoT payment and marketplace challenges are ad-
dressed by blockchain solutions and Table 5 highlights how
IoT challenges are addressed by blockchain in real world
implementations.
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Tokenization
Distributed
ledger
Digital
currency
IoT
Payments
Smart
health
payments
cashless city
efficient payments
within city
Smart
agriculture
payments
Smart
energy
payments
Smart
home
payments
Smart
manufacturing
payments
Smart
transport
payments
Smart
city
payments
Embedded financial
functionalities
Automated utility payments
Automated supply ordering
Payment for
parking and
infotainment
etc.
Inbuilt payment
systems
Payments for
hospitals etc.
Automated health
data record
payments
Cashless
payments
Cashier-less
stores etc.
Smart
metering peer to
Peer to peer
energy trading
Payments for
raw materials
FIGURE 5. Blockchain-based IoT payment
A. IOT DATA SECURITY
1) Technical challenge of IoT data security
Most of the IoT devices are controlled remotely over the
internet to achieve the desired functionality. These devices
use standard communication protocols to share information
among the devices in the IoT ecosystem via communication
networks. The IoE concept highlights the smart connected
things concept where each device is having some sensor
module to collect data and a communication module to
connect to the IoT application network. These IoT devices
include home appliances, health monitoring devices, weather
stations, tracking devices, and much other equipment based
on the IoT application domain. The data acquired from the
end devices need to be shared in real-time with the IoT
application platforms. Considering the critical nature of the
IoT ecosystem, enabling IoT data security is a critical factor
for the development of all IoT fields.
The IoT deployment architectures need to be secure from
privacy, integrity, and confidentiality-related security attacks.
IoT ecosystem consists of inter-connected networks which
inherit the security issues of computer networks. The het-
erogeneous devices are having power, memory and other re-
source constraints that make it further challenging to address
the security issues through complex mechanisms [33].
2) Role of blockchain in solving IoT data security issue
Blockchain solutions are introduced for tracking and moni-
toring products, goods, and assets to increase trust and se-
curity. They maintain the integrity of the distributed transac-
tions. Therefore, IoT devices can be registered with a defined
set of attributes in a distributed ledger such as blockchain and
resolve the existing security and trust issues of IoT platforms.
The Blockchain IoT (BIoT) concept in [27] explains
how sensor data-related transactions can be included in a
blockchain. This provides essential security features such as
publishing sensor data in distributed ledgers, the immutabil-
ity of the records, authentication, and non-repudiation of
data. They are identified as solutions with protection from
data tampering and usage of compromised IoT devices, se-
cure communication, user authentication, and trustworthi-
ness [96].
Even though blockchain-based solutions can establish IoT
security, they are also vulnerable to security issues. If the
randomness of private keys is limited, then they can easily be
compromised by the attackers. Further, transaction privacy
and other security threats such as double spending attacks
need to be carefully analyzed when introducing a blockchain
solution [34].
3) Summary
Even though blockchain systems offer a robust approach
for IoT security, they are also vulnerable. Based on the
security threat, the research community has suggested dif-
ferent frameworks. But, a single framework that is resilient
against many combined attacks and feasible to implement is
a research challenge. The fate of blockchain-based security in
the era of quantum computing is yet to be properly analyzed.
B. IOT DATA PRIVACY
1) Technical challenge of IoT data privacy
The IoT data produced within the IoT ecosystem need to be
transmitted, processed, and stored securely without compro-
mising privacy. It is common for IoT data to contain sensitive
information including personal data. User data should not be
disclosed without obtaining consent from the data owners.
IoT ecosystems are complex, decentralized, and consist of
heterogeneous system elements. Therefore, it is challenging
to preserve the privacy of IoT data.
The privacy concerns related to IoT data negatively affect
the adoption of it as users are reluctant to use a system that
is not capable of respecting the privacy requirements of the
users. The traditional authorization protocols such as Role
Based Access Management (RBAC), OAuth 2.0, and OpenID
are too complex to run in most of the resource constraints IoT
environments. User privacy is considered a major concern by
the regulators as well. Therefore, it is essential to guarantee
the privacy of IoT data [33].
2) Role of blockchain in solving IoT data privacy issue
Smart contracts can be executed in blockchains to provide
IoT device authentication in the decentralized system and
they are less complex compared to the traditional authentica-
tion protocols. Blockchain solutions have their own privacy-
related concerns. One of the main issues that should be
addressed to preserve data privacy is not letting and sensitive
data be lost or erased from the system [97]. Mixing technique
and anonymous solutions are the two existing solutions for
privacy protection [98]. Both centralized mixing and de-
centralized mixing models have their own disadvantages. In
centralized mixing, the transaction time is a major concern,
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and in decentralized mixing increased complexity is a major
concern [98]. The use of cryptography-based techniques to
preserve privacy and transaction time is a common approach
to preserve the privacy.
Smart contracts can be used to define access rules, access
time periods, or other required conditions to ensure data
privacy and the user right levels can also be managed [33].
Tiffany Hyun-Jin Kim et al [99] developed a mechanism
named Self-Sovereign Privacy (SSP) to protect the privacy
and integrity of the data collected by IoT devices. This
method removed the risk of having a single point of failure
and minimized the cryptographic operations that must be
performed on IoT devices. Alem Fitwi et al [100] Alem Fitwi
et al [100] proposed a blockchain-based privacy protection
scheme for surveillance cameras to perform surveillance
activities by capturing videos without compromising user
privacy.
3) Summary
Privacy of IoT data needs to be preserved to enhance user
trust in the IoT ecosystem. Blockchain solutions provide pos-
sible solutions to address IoT data-related privacy concerns.
Even though blockchain is an ideal candidate to address
many of the IoT-related technical challenges, widespread
adoption of blockchain-based technologies is still hindered
due to the privacy concerns of blockchain itself. In pub-
lic blockchains, user information shared is disclosed to all
nodes. Further, the other types of blockchains are also facing
data privacy-related concerns where research community is
trying to provide an ideal solution.
C. LACK OF COOPERATION AMONG IOT PLATFORMS
1) Technical challenge of not having cooperation amoing IoT
platforms
It is challenging to exchange data within the IoT ecosystem
due to the decentralized nature and heterogeneity of IoT
systems and it is challenging to achieve interoperability
as well. The distributed IoT resources make it difficult to
manage and the distribution of smart objects of multiple IoT
applications at the same location makes it more complex.
Therefore, the corporation among IoT platforms is important
to reduce complexity and deployment costs [101].
Let’s consider an example: An agricultural IoT system
needs weather data for analytical purposes. The weather
stations established by the meteorology department indepen-
dently collect weather data for weather predictions. Since
the two IoT platforms are working independently without
any cooperation, the agricultural IoT system will need to
deploy a separate weather station. If there is a common IoT
marketplace, agricultural IoT platform and weather station
platform can exchange information and achieve resource
optimization. The different IoT verticals need to cooperate
with each other to prevent the issue of small silo networks
without much use is getting created.
2) Role of blockchain in providing cooperation among IoT
platforms
Blockchains can keep the transactions in an immutable
manner and the transaction records in the blockchain are
transparent and reliable. Further, data monetization can be
enabled via cryptocurrency-based transactions without the
need for fiat currency. Therefore, the blockchain-based IoT
data marketplace concept can deploy a platform for various
IoT applications to coordinate with each other.
Let’s consider an example: A smart health monitoring
device fixed on an athlete can monitor the health conditions.
Once the device owner advertises the data via an IoT market-
place, hospitals, AI-based training institutions, pharmaceuti-
cal companies, and any other third-party system can obtain
the stream of data to be used in their IoT applications. This
type of approach can allow the IoT platforms to coordinate
with IoT platforms and fast track the IoT adoption.
Hong-Ning Dai et al [22] highlighted the convergence
of blockchain and IoT and proposed an interoperable IoT
platform architecture. Eman M. Abou-Nassar et al [109] in-
troduced a decentralized and interoperable trust model based
on blockchain for healthcare-based IoT.
3) Summary
Due to the lack of cooperation among IoT platforms, small-
scale silo networks are getting created. This is a ma-
jor concern for the widespread adoption of IoT solutions.
Blockchain provides a promising solution to the IoT plat-
form interoperability issue via the blockchain-based IoT
platforms. But, the integration challenges of blockchain such
as performance and scalability issues observed with IoT
platforms that generate a high volume of data need to be
resolved with further research.
D. REQUIREMENT OF CENTRAL PAYMENT SYSTEMS
1) Technical challenge of having a central payment system
The conventional IoT business models rely on a trusted
third party to act as an intermediary to perform monetary
transactions. This is a major limiting factor to prevent the
adoption of true P2P applications. The recent boom in IoT
and the expected growth in the IoT ecosystem suggest that
IoT applications and relevant monetary transactions will
increase exponentially. In an IoT data marketplace, it is
preferred to allow data suppliers and consumers to perform
the transactions in a decentralized manner [39].
2) Role of blockchain in implementing decentralized
payment solution
Due to the distributed nature of blockchains, they allow
direct P2P transactions without the need of a trusted third
party. Blockchain technologies bring capabilities such as
data tracking, coordinating, and allowing a large number
of devices to be handled without a centralized approach.
The parties in a blockchain might not trust each other. But,
the immutability of blockchains has enabled the parties to
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TABLE 5. How blockchain solutions can address IoT challenges
Challenges Importance of blockchain fea-
tures to address them
Practical implementations Possible limitations in blockchain
system
IoT Data Security
•Allows to publish sensor
data in distributed ledgers,
the immutability of the
records, authentication, and
non-repudiation of data.
•Therefore, data tampering
will be avoided and
secure communication,
user authentication, and
trustworthiness will be
enabled.
•ArcTouch – DApps for smart,
connected items; including
voice assistants, wearables
and smart TVs [102].
•Xage - A blockchain-
protected security platform
for IoT [103]
•Vulnerable to security issues
including transaction privacy
and other types of attacks
such as double spending.
IoT Data Privacy
•Smart contracts can be exe-
cuted to provide IoT device
authentication in the decen-
tralized system
•Cryptography-based
solutions can further enhance
privacy.
•Chronicled - pharmaceutical
and food supply industries re-
lated supply chain solutions
[104].
•The stringent data privacy re-
quirements in pharmaceutical
industry are handled.
•Privacy of blockchain-based
IoT systems is a major con-
cern.
•Especially, public ledgers,
lack of awareness in data
sharing and ability to track
via personally identifiable in-
formation pose data privacy
risks.
Lack of cooperation
among IoT platforms •The decentralized,
immutable, transparent
and crypto-currency-based
IoT data marketplace.
•A platform which the IoT ap-
plications can coordinate.
•NetObjex – IoTokens pro-
vides a secure platform for
IoT devices in the same
ecosystem [105].
•Helium - A decentralized
wireless infrastructure solu-
tion to provide connectivity
for IoT devices [106]
•The complexity of
blockchain-based systems is
a major concern for resource
limited IoT applications.
Requirement of central
payment systems •Due to the distributed nature
of blockchains, they allow di-
rect P2P transactions without
the need of a trusted third
party.
•HYPR - decentralized net-
works to secure connected
ATMs, cars, locks and homes
[107].
•Grid+ - Provides consumers
access to energy saving IoT
devices.
•Transaction fee issue of
blockchain.
Lack of anonymity
•Blockchain has the capability
to provide anonymity via de-
centralized payment systems.
•NEBULA GENOMICS
-Understanding human
genome. All individual DNA
data are kept anonymously in
a blockchain [108].
•Due to the complete
anonymity, they are
vulnerable to criminal
exploitation and regulatory
resistance.
trust each other without a central authority. From the past,
there were proposals for decentralized P2P Wireless Sensor
Networks (WSN) [31]
P2P transactions without third-party intervention can be
allowed in a distributed payment system [110]. Natthanan
Chanthong et al [111] designed and built an electronic
payment system for electric vehicle (EV) charging using
blockchain and smart contract technologies to control and
manage payments and to decentralize the payment system.
Tassos Dimitriou et al [112] developed a data payment and
transfer scheme that uses bitcoin payments to reward users
for detailed electricity measurements they submit to a utility
provider (UP) and other applications such as crowdsensing.
Even though the technology is promising which has hindered
the usage of blockchain as a decentralized payment plat-
form. The technology has its own scalability issues. Payment
channel networks have been proposed to increase transaction
throughput and decrease transaction confirmation latency,
[113].
3) Summary
IoT deals with micro-transactions. Each transaction of cryp-
tocurrency requires a certain amount of computation and
attracts transaction fees. Therefore, the computation and
transmission overheads are a major concern in blockchain-
based decentralized payment systems.
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E. LACK OF ANONYMITY
1) Technical challenge of lack of anonymity
Users do not want the IoT applications to store their payment
and transaction history details. Eg: Imagine a farmer who’s
using third-party weather station data to control an irrigation
system. This farmer has to pay for the weather station data,
smart irrigation system, etc. So, the farmer’s bank informa-
tion data need to be shared with the third parties who are
handling these IoT platforms. If the use case involves more
IoT platforms, the number of times the bank information to
be shared will also increase.
2) Role of blockchain in providing anonymity
Blockchains excel in anonymity when compared to tradi-
tional centralized IoT platforms. Willian J. Gordon et al [114]
used pseudonymization which consists of removing some of
the information necessary to identify an entity. The research
conducted by Nir Kshetri et al [115] proposed a blockchain-
enabled e-voting (BEV) system to allow the eligible voters to
anonymously cast their vote using a computer or smartphone.
Chao Lin et al [116] introduced Decentralized Conditional
Anonymous Payment (DCAP). It is difficult to regulate De-
centralized Anonymous Payment (DAP) systems. Therefore,
the anonymity feature of blockchain can be exploited by
criminals for money laundering and other cybercrime.
3) Summary
Blockchain has the capability to provide anonymous so-
lutions via decentralized payment systems. But, complete
anonymity can be criminally exploited. Therefore, the decen-
tralized payment systems should be designed after carefully
considering the level of anonymity to be allowed based on
regulatory requirements to avoid criminal exploitation and
reasonable privacy protection.
F. OTHER TECHNICAL CHALLENGES
1) Technical challenge of high transaction fee
If a third-party organization is used in IoT solutions, a
separate transaction fee should be paid for their service.
Since IoT payments include many micropayments, the higher
transaction fee is a major concern for IoT payments and
market places [93]. Therefore, a payment that is both small
and metered is required for IoT systems. We can use cryp-
tocurrencies to remove the fiat currency usage requirement,
Further, the decentralized solutions, remove the need for a
third party to perform monetary transactions. Therefore, the
merchant payment fees can be reduced and users can receive
funds immediately via cryptocurrencies. The transaction fee
is an issue in blockchain technologies as well, but there is
multiple research that has been done to improve this signifi-
cantly.
2) Static agreements issue
Due to the current static agreements, there is a possibility for
the data owner to loose the ownership of data due to reselling
possibility. An example scenario would be a small house
generating sensor data and providing them to marketplace,
then the data can be resold by-passing the owner.
VI. IOT APPLICATIONS
Blockchain technology can be applied in many IoT do-
main applications. Blockchain technologies can be applied
in different IoT domains as shown in Figure 6. These IoT
applications include autonomous vehicles, smart agriculture,
smart cities, smart grid, and smart trading. The importance of
blockhain characteristics for IoT applications is highlighted
in Table 6 and a summary of related research work in IoT
application domains are mentioned in Table 7.
IoV sensors
Car manufacturers
Repair centers
Blockchain based IoT
marketplace platform
Smart
contract
Distributed
ledger
Consensus Cryptography
Crypto-currency
Insurance companies
Law enforcement authorities
Agriculture
sensors
Smart city
sensors
Smart health
sensors
Smart energy
sensors
Crop buyers
Crop sellers
Chemical manufacturers
Research institutes
Government organizations
Educational institutes
Citizens
Utility authorities
Pharmacetical companies
Hospitals
Research institutes
Medical centers
Power generators
Electricity companies
Micro-grids
Energy consumers
Supplier data
Consumer data
IoV data users
Smart agriculture data users
Smart city data users
Smart health data users
Smart energy data users
FIGURE 6. Blockchain-based IoT payment and marketplace application
domains
A. AUTONOMOUS VEHICLES
1) Introduction
IoV is considered as an emerging concept in Intelligent
Transportation Systems (ITS) which has integrated the Ve-
hicular Adhoc Network (VANETs) to IoT [117]. The overall
IoV ecosystem that consists of smart vehicles is interdepen-
dent with communication networks, and external environ-
ments including roads, traffic lights, road signs, pedestrians,
and all relevant domains relevant to transportation. IoV is a
major component in the concept of smart city as well [118].
2) Role of Blockchain-based solution
IoV has integrated smart vehicles with the internet. The
overall IoV ecosystem includes smart vehicles with sen-
sors, road network, pedestrians, other vehicles, and other
infrastructure. Therefore, in order to guarantee road safety, a
common information exchange platform is required among
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the IoV ecosystem. ITS needs this platform to be secure,
trustworthy, and immutable to achieve the intended objec-
tives [117]. IoV faces technical challenges such as effectively
using the scare spectrum, allocating channels for commu-
nication, and utilizing transportation infrastructure appropri-
ately based on the traffic conditions [119]. IoV applications
can resolve these challenges by integrating blockchain with
cryptographic techniques and edge computing. Innopolis
University in Russia implemented a M2M billing service for
electric autonomous vehicles. Their primary focus was to
introduce a solution based on IOTA’s tangle network for the
M2M monetary transactions that need to be performed by the
vehicles with charging stations for electricity consumption.
The introduced payment framework acts as a meter to ex-
change IOTAs for the consumed power based on the number
of kWh [32].
3) Summary
IoV aims to establish a novel and secure smart vehicle
ecosystem. IoV is still trying to resolve many security and
privacy vulnerabilities. The blockchain-based solutions that
are emerging in IoV are capable of resolving the technical
challenges of IoV by enabling secure data communication.
Secure IoV communications can utilize methodologies such
as the High-Performance Blockchain Consensus (HPBC)
algorithm. But, the number of transactions required to update
blockchain ledgers poses serious issues for vehicles as these
may consume the available energy.
B. SMART AGRICULTURE
1) Introduction
Smart agriculture is a revolutionary concept that has allowed
farmers to access real-time crop data very easily and respond
accordingly. Farmers can analyze data and make informed
decisions rather than relying on their gut feeling. Efficiency
in all aspects of farming is critical to get the maximum yield
and meet the increasing demand. Smart agriculture expects
to improve all food supply chain elements by eliminating the
middleman and deploying a transparent and efficient system.
The application requirements of agriculture supply chain in-
clude query efficiency, security and privacy, the authenticity
and reliability of data [120].
2) Role of blockchain-based solution
In the context of building an inter-organizational mechanism
of data sharing and value creation, blockchain technology is
believed to be the favorable candidate, compared to many
other information and communication technologies (ICT).
The need for a middleman can be eliminated by introducing
transparent and efficient blockchain-based food supply chain
solutions. This allows the buyers to track the origin of the
product, product delivery time, and even the environmental
conditions of the field as well [69]. Mohsin Ur Rahman et
al [44] proposed a distributed data sharing system for smart
agriculture which consists of four main components namely
smart agriculture, smart contract, Interplanetary File System
(IPFS), and agriculture stakeholders. Shujing Lu et al [70]
designed a blockchain-based agricultural data sharing model
and system architecture.
3) Summary
Smart agriculture applications need systems that can guar-
antee query efficiency, security, and privacy, authenticity,
and reliability of data. Blockchain-based smart agricul-
ture platforms are capable of deploying a transparent and
trusted ecosystem where farmers can have access to instant
agriculture-related data such as the seed quality, climate
environment-related data, payments, soil conditions, and
crop market status.
C. SMART CITIES
1) Introduction
Smart cities are developed as a solution to the growing
urbanization challenge to achieve sustainable development
goals. They are a combination of smaller smart networks.
These data-driven services are developed based on ICTs and
the data is acquired via mechanisms such as sensors, cameras,
human inputs, crowd-sourced data from mobile phones and
vehicles. The data sources might be wholly owned by local
authorities, a single organization, or any heterogeneous group
of individuals and organizations. The data owners must be
compensated by the data consumers in a smart city for
sharing the data with them [84].
2) Role of blockchain-based solution
A smart city consists of various parties that need to sell, find
and buy data to function their applications. The data suppliers
need to be compensated for sharing information. Therefore,
the IoT data marketplace platforms are essential in smart
cities. Blockchain’s unique characteristics make it an ideal
candidate for such an IoT marketplace.
Driss EL MAJDOUBI et al [122] developed a smart
blockchain-based solution to preserve privacy and security in
a smart city environment. Stefano Loss et al [123] demon-
strated how a blockchain-based platform can be used to
handle land registration. Junfeng Xie et al [124] reviewed
how blockchain technology is applied in various domains of
smart cities including smart citizens, smart healthcare, smart
grid, smart transportation, and supply chain management.
Saqib Hakak et al [125] did a case study on a conceptual
blockchain-based architecture that can secure a smart city.
3) Summary
A smart city is an ecosystem of various IoT applications
such as transportation, healthcare, energy, manufacturing,
education, administration, and logistics. The characteristics
of blockchain such as transparency, automation, decentraliza-
tion, and immutability are helpful in achieving the ultimate
smart city concept.
D. SMART GRID
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TABLE 6. Importance of blockchain characteristics to IoT marketplace applications
Blockchain benefits Description
Smart Energy
Smart Agriculture
Smart Government
Smart Health
Smart Cities
Smart Manufacturing
IoV
Content Trading
Decentralized payment
and marketplace
Decentralizing provides high availability of services, improved trust and
reduced failure risk in IoT applications. H H H H H H H H
Immutable transactions Once the transactions are stored in the ledger, they are permanent and
unalterable. H H H H H H H H
Enhanced-security Distributed architecture along with cryptographic mechanisms make it
difficult to alter data. H H H H H H H H
Trustworthy transactions Even though the nodes are trust-less the consensus mechanisms used
can be trusted. H H H H H H H H
Transparency of transac-
tions
The transparency added by blockchain allows the participant with
openness in transactions. H M H H H M H H
Non-repudiation Once a transaction is performed the in blockchain, its validity cannot be
questioned. H H H H H H H H
Anonymity Users are allowed to perform transactions anonymously without com-
promising privacy . H L H H H H H M
HHigh impact MMedium impact LLow impact
1) Introduction
Smart grids are the core of smart energy solutions. It allows
the power generation sources and the power consumers to
exchange information and deliver energy in an automated and
distributed network. Micro-grids are deployed within small
communities using renewable energy and Energy Storage
Systems (ESS). They act as a platform to trade locally
generated energy with each other in the community [71].
2) Role of blockchain-based solution
Siddharth Dekhane et al [72] presented a blockchain-based
power distribution ecosystem for smart cities. This system
used a wallet-based currency, called “Green Coin”, for power
transactions such as buying, selling, and lending. Mohamed
R. Hamouda et al [73] presented the development and case-
study validation of a comprehensive transactive energy mar-
ket framework with linked blockchain and power system.
S. M. Suhail Hussain et al [74] developed an ethereum-
based blockchain solution for energy trading. The research
results are shown for a case where energy transactions are
undertaken between the Distribution System Operator (DSO)
and the smart meters of individual houses. Taeyun Ha et
al [75] designed a power smart contract system based on
blockchain for renewal energy trading market that consists
of power producers and consumers (Prosumers).
3) Summary
The concept of smart energy aims to integrate green and
renewable energy technologies into the conventional power
grids efficiently. The blockchain-based typical power trading
markets consist of power producers and power consumers
who are capable of producing renewable energy. Blockchain
and smart contract technologies used in energy trading helps
to implement a distributed network with transparency and
immutability
E. SMART HEALTHCARE
1) Introduction
Rapid growth is observed in the usage of wearable bio-
sensors and smart healthcare-related use cases. The enor-
mous amount of data produced by the healthcare ecosystem
need to be shared among the parties involved. This ecosystem
will eventually improve the health condition of people by
using their own data as it provides an overall better under-
standing of a patient rather than relying only on Electronic
Health Records (EHR). In the current context, due to the
hospital or specific patient-specific IoT solutions, only health
data silos are getting created. Therefore, it is required to
enable data sharing among both private and public healthcare
sector applications to prevent the less useful data silos from
getting created. [126].
2) Role of blockchain-based solution
The main requirement of a health marketplace is to create
a data-centric decentalized ecosystem and use AI applica-
tions to further improve the solutions. Decentralized market-
places are implemented based on secure smart contracts and
DLTs. This has enabled data producers to transact with data
consumers while maintaining anonymity. Blockchain-based
platforms can create a distributed and trusted user network
for data sharing [76]. BCT has the potential to enhance data-
sharing due to its properties such as transparency, traceability,
and immutability [77].
Ahmad Alsharif et al [78] proposed a decentralized
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TABLE 7. Blockchain-based IoT payment and marketplace related research
IoT Challenges IoT Application
Ref. Description of related work.
IoT Marketplace
IoT Payments
IoT Data Security
IoT Data Privacy
Lack of cooperated IoT platforms
Need of central payment systems
Lack of anonymity
Autonomous Vehicles
Smart Agriculture
Smart Cities
Smart Grid
Smart Healthcare
Content Trading
Common
[28] A decentralized and trustless data marketplace plat-
form for nonreal-time and non-critical IoT applica-
tions to store and access IoT data.
✓ ✓ ✓ ✓ ✓
[84] A decentralized marketplace for smart cities. ✓ ✓ ✓ ✓
[85] A three-tiered architecture consists of participants
of the marketplace, facilitators to supervise service
areas, and regulators to ensure that the facilitators are
adhering to the privacy regulations.
✓ ✓ ✓ ✓ ✓
[39] A blockchain-based IoT data monetization frame-
work.
✓ ✓ ✓ ✓ ✓
[119] A blockchain-based IoV scheme to ensure secure data
sharing.
✓ ✓ ✓ ✓ ✓
[76] A blockchain-based consent model for health data
sharing.
✓ ✓ ✓ ✓
[84] A blockchain-based data market place for smart
cities.
✓✓ ✓✓✓✓ ✓
[85] A three tier IoT marketplace consisting of data sellers,
facilitators and regulators is proposed.
✓ ✓ ✓ ✓
[121] An integrated trading system named ArtChain, based
on blockchain for trading artworks
✓ ✓ ✓ ✓
[78] A decentralized health data trading platform with
access control and smart contract.
✓✓✓ ✓✓✓ ✓
[75] A power trading market-based on blockchain and n
VCG-auction-based transaction.
✓ ✓ ✓ ✓ ✓
[74] A blockchain implementation-based on Ethereum im-
plementation for energy trading.
✓ ✓ ✓
[44] A blockchain-based data sharing platform for smart
agriculture.
✓ ✓ ✓ ✓
[70] A blockchain-based agricultural IoT data sharing sys-
tem .
✓ ✓ ✓
blockchain-based medical data marketplace for the medical
record sellers to sell their data to interested buyers. Naveen
Kumar S et al [79] established a hyperledger fabric-based
blockchain network among patients and medical institutions
to share patients’ data securely and reliably. Vikas Jaiman et
al [76] developed a blockchain-based data-sharing consent
model using smart contracts to access control the health
data. Alevtina Dubovitskaya et al [77] presented a system-
atic literature review to analyze the motivations, advantages,
limitations, and future challenges faced when applying the
distributed ledger technology in oncology.
3) Summary
Smart healthcare applications consisting of various elements
such as health monitoring devices, research institutes, pa-
tients, and various other sections that need to share health-
related information with each other. Considering the sensitive
nature of health data, health data sharing should be allowed
based on individual consent. But, resource limitation is a
major bottleneck. Further, BCT uses crytographic techniques
to guarantee data privacy and security.
F. CONTENT TRADING
1) Introduction
BitTorrent technology is an option for content data sharing.
But, it infringes on the copyright, which taints its public
perception [127]. The art market performs USD 200 billion
worth annual trading, It is one of the largest unregulated
markets in the world which is responsible for one-third of
crimes committed [128].
2) Role of blockchain-based solution
The blockchain-based digital content marketplace can re-
solve the issue of digital content trading issues that are
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observed in current market environments. The decentralized
market which will be created using blockchain allows the
users to engage in content publishing, hosting, accessing,
downloading, and paying activities.
Gabin Heo et al [129] proposed a new blockchain system
named the Secret Block-based BlockChain (SBBC). This
uses both off-chain and on-chain network components, to
solve the issues observed with the blockchain system. Umair
Khan et al [130] proposed a blockchain solution based on
Ethereum to protect content and transactions. A blockchain-
based art trading system named ArtChain was introduced as
a pilot project in [121].
3) Summary
Current content trading applications need solutions for the
existing problems such as copyright violations, forgery, and
falsification in the digital content trading environments. Even
though blockchain is an ideal solution for the issues in the
content trading domain, due to the scalability concerns, it is
difficult to propagate digital content to the blockchain net-
work. Therefore, blockchain-based content trading platforms
consisting of off-chain and on-chain network components are
introduced as a solution.
VII. INTEGRATION CHALLENGES OF BLOCKCHAIN
The term blockchain is a leading buzzword in modern day
tech world. But, the actual implementations of blockchain
technologies are hindered due to various technical limitations
mentioned in Table 8 which the research community has
been trying to resolve for the last few years. The issues of
transaction fee an transaction time are major challenges. The
scalability issues of blockchain with respect to transactions
and storage are also having a negative impact towards the
blockchain adaption. Lack of standards, new security and
privacy issues, latest quantum resistance related concerns,
intermittent connection issues and other challenges such as
regulatory resistance are challenges that should overcome for
the widespread use of blockchain technologies in the real
world applications such as IoT marketplaces.
A. ISSUE OF TRANSACTION FEE
1) Introduction
Micro-payments are an essential component in IoT applica-
tions as they constantly request data as a service from IoT
devices. These transactions need to be compensated with
some sort of small, metered, and anonymous payment option.
The transaction fee is a major bottleneck in blockchain-based
IoT application solutions. Some blockchain solutions require
the transaction validators to be compensated. The transaction
fees are market-based, which makes them quite expensive.
2) Possible solutions
The on-chain solution is a method to increase scalability by
modifying only elements within a blockchain. The transmis-
sion cost is lower than the conventional way in this method.
But, increasing the block size is not a scalable solution.
The off-chain solutions improve scalability by processing the
transactions outside the blockchain and solve the transaction
cost issues as they are handled outside the blockchain [131].
DAG-based approaches, aiming to provide cheap blockchain
services with low latency and high throughput, are emerging
as a solution to blockchain transaction fee issue [132].
Ansgar Fehnker et al [133] analyzes the Bitcoin Unlim-
ited (BTU) in which the transmission limit is higher and
the transmission cost is lower than the conventional way.
Yuwei Guo et al [134] provided a detailed analysis of the
Bitcoin Lightning Network (LN). The LNs use an off-chain
mechanism to reduce transaction fees. Giuseppe Antonio
Pierro et al [135] analyzed the influence factors on Etherium
transaction fee. Wenhui Yang et al [136] proposed a DAG-
based blockchain for resource-constrained VSNs.
3) Summary
In blockchain, once a transaction is created, the user must
pay the transaction fee to the minor. This transaction fee is
a major issue as light transactions such as micro-payments
are a regular occurrence in IoT. On-chain and off-chain so-
lutions are proposed as solutions to current blockchain scal-
ability and transaction fee issues. But, handling the micro-
transactions generated by various IoT systems is still an
issue. Research community is using DAG-based solutions for
various IoT applications as a latest solution.
B. SCALABILITY ISSUE: TRANSACTIONS
1) Introduction
The PoW concept introduced in initial blockchain applica-
tions has the core concept of competing for computation
power [137].In PoW, the members in the blockchain need
to solve complex problems, purely as a need for evidence,
but not as a real requirement for a solution. The resource
requirement of this process cannot be catered by IoT devices
[138]. So, the transaction time is a problematic issue for
many blockchain-based technologies.
2) Possible solutions
Unlike PoW, PoS uses coin age i.e. the contribution to the
blockchain network which doesn’t require a high computa-
tional power [139]. Abdelatif Hafid et al [140] did a compre-
hensive survey regarding the existing solutions to blockchain
scalability. Shihab Shahriar Hazari et al [141] proposed a
method using parallel mining which accelerated the process
of PoW when compared with solo mining as the maximum
of two miners will try to solve a specific block at a given
time. Also, in literature, the solutions related to blockchain
scalability can be classified into first layer solutions such as
sharding, bigger blocks and DAGs and second-layer solu-
tions such as payment channels and side chains [140].
Both PoW and PoS consensus mechanisms avoid fork-
ing and maintain a single version of blockchain ledger by
slowing down the access rate of new blocks [138]. The use
of DAGs is proposed as a solution to decrease transaction
time and improve scalability [132]. Instead of arranging the
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nodes in linear chains, they are arranged as a directed graph
in DAGs. The consensus in DAG-based solutions before
creating a new node is usually reached by confirming a given
number of previous transactions. Hence, it eliminates the
requirement of complex consensus mechanisms, ultimately
improving the scalability. Shu Yang et al [142] introduced
CoDAG which improved the linear structure of traditional
blockchain protocol using DAG. CoDAG achieved a through-
put of 394 TPS, which is higher than Bitcoin and Ethereum.
3) Summary
The blockchain scalability issue in terms of transactions is
a major issue that the research community has been trying
to resolve so it will be suitable for IoT applications. We
can classify those solutions into two categories as first layer
solutions which modify the structure of the blockchain and
second layer solutions which include more transactions in a
block to increase throughput. The main chain’s structure is
not changed in second-layer solutions. Therefore, network
security is not sacrificed when compared with first-layer
solutions. The research community is interested in combin-
ing both first and second-layer solutions to achieve higher
throughput which is essential for adopting blockchain-based
solutions for IoT applications.
C. SCALABILITY: STORAGE
1) Introduction
Storage capacity and scalability have been deeply ques-
tioned in the blockchain. The scalability of storage capacity
is another major bottleneck in the blockchain. In typical
blockchains, the chain continues to grow. Especially the full
nodes need significant storage to store the complete chain.
Nodes require more resources as they grow and this reduces
the scalability of the system and it can impact the system
performance. For example, when the Ethereum blockchain
platform is considered, it requires all the nodes in a network
to participate in the validation and if the data volume in
the application is significant, this results in considerable
processing delay [143].
2) Possible solutions
Distributed storage systems can store a large amount of data
off the chain. Therefore, it is proposed to combine blockchain
with existing distributed storage systems [124]. Block com-
pression techniques are used to reduce some redundant data
of a block that has been already stored. Blockchain prun-
ing is used to remove non-critical historical data from the
blockchain while preserving the security [144].
The Storage Compression Consensus (SCC) algorithm
used by Teasung Kim et al [145] compresses a blockchain
in each device to prevent storage capacity limitations in
lightweight IoT devices. Teasung Kim et al [146] proposed
a selective compression scheme using a checkpoint-chain
to prevent the limitation of accumulating the compression
results which needs to validate the retained blocks. MD.
Soharab Hossain Sohan et al [147] proposed a distributed
storage system IPFS is used to bypass the storing liabilities
and to increase throughput. Roman Matzutt et al [148] devel-
oped a scheme named Coin-Prune to prune old-blocks.
3) Summary
Each node in a traditional blockchain needs to process and
store the complete transactions to the genesis block. The
IoT devices have limited computing and storage resources.
Therefore, blockchains cannot be used with most IoT appli-
cations due to this limitation. Combining blockchains with
existing storage systems allows the solutions to store a large
amount of data off the chain.
D. LACK OF STANDARDS
1) Introduction
The term “blockchain” has been one of the most widely used
tech buzzwords and it is evolving rapidly when compared
with the attempts to introduce a standardization framework.
So, the emerging blockchain technologies are used without
proper standardization provided by a recognized interna-
tional organization [149]. This is causing regulatory bodies
not to accept blockchain-based technologies as they might
not interoperate with each other and it will be difficult to
integrate with traditional information systems as well [150].
2) Possible solutions
A major standardization initiative was initiated on blockchain
and distributed ledger technologies through a Technical
Committee of the International Organization for Standard-
ization, ISO/TC 307. Other organizations like IEEE1 and
the International Telecommunication Union (ITU) have also
established standardization efforts on blockchains to iden-
tify the needs and responsibilities of their members and
stakeholders as users, developers, and operators of this new
technology [150].
International Organization for Standardization (ISO) is
currently working on 15 work programmes related to the
standardization of blockchain technologies and distributed
ledger technologies [151]. International Telecommunication
Union (ITU) established Application of Distributed Ledger
Technology (FG DLT) in May 2017 to identify and analyze
DLT-based applications and services related to telecommu-
nication use cases and concluded their work in August 2019
[152]. ITU-T work programme SG20 which is responsible
for studies relating to the Internet of things (IoT) and its
applications are currently working on blockchain-based ap-
plications and frameworks [153]. Lukas König et al [149]
referred to local and international standardization organiza-
tion’s publications and provided a set of comparison criteria
for future work and a comparison of the existing standards
work.
3) Summary
Standardization improves interoperability and provides a
clear view of technical aspects for the industry. The existing
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Author et al.: Preparation of Papers for IEEE TRANSACTIONS and JOURNALS
issue of lack of standardization and clarity is a major obstacle
to the adoption of the technology. Therefore, the standard-
ization of blockchain technology is one of the major steps
towards enabling interoperability and obtaining regulatory
acceptance of the technology. But, introducing standards to
an emerging technology can limit its advancement as well.
E. NEW SECURITY AND PRIVACY ISSUES
1) Introduction
Blockchain-based IoT systems use encryption and authen-
tication strategies to ensure the security of data. Even
though these strategies protect the transaction security of
blockchains, the privacy of blockchain-based IoT systems
has always been a major concern [154]. Some of the
blockchain vulnerabilities are listed below.
•Liveness attack: The confirmation time of a target trans-
action is delayed in a liveness attack. The three phases
of liveness attack are the preparation phase, transaction
denial phase, and blockchain retarder phase [59].
•51% vulnerability: 51% attack can be performed and
the entire blockchain can be controlled when a single
miner’s hashing power is greater than 50% of the total
hashing power of the entire blockchain [155], [156].
•Double Spending (DS) attack: When the proportion of
computing power possessed by an attacker is higher
than that of the honest network, DS attacks can be
performed [157]
•Selfish mining: In selfish mining, malicious nodes don’t
immediately disclose their newly mined blocks and
deflect their behavior from the standard pattern [158].
•Smart contract vulnerabilities: If an attack based on a
smart contract is successfully executed, it will cause the
smart contract to perform in an expected manner and
result in losses to the parties involved [159].
2) Possible solutions
The Conflux is a high throughput and fast confirmation
blockchain platform which uses a novel consensus protocol
to secure against double-spending attacks and liveness at-
tacks [160]. Jehyuk Jang et al [157] analyzed profitable DS
attacks and guide how to set a block confirmation number for
a safe transaction.
Saurabh Singh et al [34] did a comprehensive survey on the
security attacks, challenges, and solutions for the distributed
IoT networks. Xiaoqi Li et al [59] did a survey on the
security of blockchain systems. Vanessa Chicarino et al [158]
presented a simple heuristic to detect the presence of selfish
mining attacks in PoW based blockchain networks. Sarwar
Sayeed et al [159] proposed an attack categorization for
smart contract vulnerabilities and highlighted the flaws in
existing vulnerability detection methodologies. Chenxing Li
et al [160] developed, high throughput and fast confirmation
blockchain platform named the Conflux.
3) Summary
Blockchain solutions also face major security concerns. For
example, transaction malleability is one of the main security
issues and it is caused by delayed information in the hash
transaction, DoS attacks are also a common phenomenon,
there are attacks that affect privacy and confidentiality of
data. A security attack on a critical IoT application can
result in major losses. Therefore, when adopting blockchains
for IoT applications, its security issues should be addressed
properly after analyzing the similar solutions discussed in
this research.
F. OTHER CHALLENGES
1) Intermittent Connection
In today’s context, many of the services rely on continuous
network connectivity. Therefore, communication infrastruc-
ture has become a crucial factor. However, 100% population
coverage of networks is not available in all areas and even in
the areas with coverage, intermittent connectivity is a com-
mon issue. Blockchain solutions require continuous network
connectivity to constantly exchange data with its peer nodes
[161].
A blockchain-based payment scheme can be built using
smart contracts, a token-based admission control, account
management, and mining rewards distribution for intermit-
tently connected regions [161]. Yining et al [161] proposed
a blockchain-based digital payment scheme that can deliver
reliable services on top of unreliable networks in remote
regions using Etherium. Yang Xiao et al [155] proposed an
analytical model which can assess the impact of network con-
nectivity on the PoW blockchain and its impact on consensus
security.
VIII. LESSONS LEARNED AND FUTURE RESEARCH
In this section, We outline the lessons learned and future
research challenges, along with available requirements to
improve blockchain-based IoT payment and marketplace so-
lutions.
A. TECHNICAL CHALLENGES
1) Lessons Learned
The traditional e-business models used in IoT related pay-
ment and marketplaces have hindered the development of
IoT applications. IoT data security and privacy are major
concerns when transmiting and storing IoT data. A central
payment system managed by a third party is required for
IoT solutions and lack of anonymity, high transaction fee,
fradulent transaction attempts and static agreements are some
of the major technical challenges observed in such solutions.
2) Open Research Problems
•How to overcome IoT data security and privacy issue?
•What’s the best solution to decentralize the IoT platform
solutions?
•How to improve anonymity in IoT solutions ?
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Author et al.: Preparation of Papers for IEEE TRANSACTIONS and JOURNALS
TABLE 8. Impact of blockchain integration challenges to IoT marketplace applications
Blockchain Integration
Challenges Description
Smart Energy
Smart Agriculture
Smart Government
Smart Health
Smart Cities
Smart Manufacturing
IoV
Content Trading
Transaction fee The market-based transaction fees required to compensate the validators
are quite expensive H H H H H H H H
Scalability issue: transac-
tions
The number of transactions that can be performed by most of the
blockchain platforms are limited. H M H H H M H H
Scalability issue: storage As the blockchain ledger grows, storage capacity requirement limits the
scalability of the system. H H H H H H H H
Lack of standards A well-defined standardized framework for blockchain is not available.
Hence, the regulators are reluctant to accept it. H L H H H M H M
New security issues Blockchains are vulnerable to security attacks similar to other ICT
systems. H H H H H H H H
Privacy issues The privacy of the data stored in the blocks are not always protected as
the data stored in the ledger might be visible to all nodes. M L H H H H H H
Quantum resistance Quantum computing has threatened to expose hash algorithms and other
PKI systems. H H H H H H H H
Intermittent connections Continuous network connectivity is not available all the time in all
areas. H H H M H L H M
HHigh impact MMedium impact LLow impact
•How to resolve the transaction fee and scalability hur-
dles in IoT solutions?
3) Preliminary Solutions
Data security and privacy can be provided to IoT solutions
by using blockchain-based solutions with smart contract and
cryptopraphic techniques. Blockchain is a DLT by nature, so
central authority can be removed. So, the lack of anonymity
and transaction fee related issues can also be overcome by
blockchain-based solution which remove the third party from
IoT solutions.
4) Future Research Directions
Research community have proposed various DLT and DAG
based solutions to address the technical challenges that have
limited the true potential of IoT. A single blockchain-based
solution for all IoT technical challenges or introducing stan-
dardized blockchain-based solutions to resolve specific IoT
technical challenges as a guideline will help the develop-
ment of IoT domain immensely by overcoming its technical
challenges. The right balance between blockchain and other
cryptographic techniques to ensure data security and privacy
need to be identified.
B. APPLICATIONS
1) Lessons Learned
IoT systems connect various smart objects mounted with
sensors actuators and software systems which can sense and
collect information from the physical environment and then
take necessary actions on them. The IoT ecosystem needs a
way for sensors and devices to make monetary transactions in
exchange for services. Therefore, IoT payment and market-
place requirements exist in various IoT application domain
such as autonomous vehicles, smart agriculture, smart cities,
smart grid, smart healthcare and content trading. Due to the
characteristics such as decentralization, immutability, non-
repudiation, traceability and trust of the BCT, they can be
applied in all these IoT application domains.
2) Open Research Problems
•How can the blockchain technology along with modern
cryptographic techniques, and edge computing be used
in IoT applications ?
•What’s the best blockchain-based platform for IoT mar-
ketplace requirement of various IoT applications?
•How can IoT application data silos be prevented ?
3) Preliminary Solutions
Blockchain-based solutions such as HPBC are integrated into
secure IoV communications. Various decentralized data mar-
ketplaces, focusing on the product smart contract and query-
ing components are introduced in smart cities. Prosumer
energy sharing applications use decentralized BCT solutions.
Smart health applications use BCT-based data sharing ap-
proaches. Content trading is an emerging IoT application
where BCT-based solutions were introduced.
4) Future Directives
The IoT domain mainly deals with micro-transactions and
transaction fee and scalability issues of blockchain are major
bottlenecks for IoT applications to use the BCT. Therefore,
when developing an IoT marketplace solution for any IoT
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application domain, latest DLT-based plaforms such as hy-
perledger fabric or DAG-based platforms such as IOTA need
to be considered. Since, IoT applications deal with sensitive
information, ensuring privacy in blokchain-based solutions
with right balance of BCT and typical cryptographic tech-
niques is a must.
C. INTEGRATION CHALLENGES
1) Lessons Learned
Even though blockchain is highly regarded by research com-
munity for IoT applications, the actual implementations of
blockchain technologies are hindered due to various technical
limitations. The transaction fee that has to be paid to miners
is a major obstacle in blockchain-based IoT applications as
micro-transactions are a common occurence in IoT domain.
The scalability in terms of transactions and storage is an-
other major concern for adopting blcokchain-based solutions.
Emerging blockchain technologies are used without proper
standardization and this has resulted in lack of trust regard-
ing overall blockchain solutions. Privacy and latest security
threats such as liveness attack, 51% vulnerability DS attack
and smart contract vulnerabilities need to be addressed. The
quantum resistance has threatened core blockchain security
implementations which are based on cryptographic and has
function related mechanisms. Intermittent connectivity issues
observed in rural areas and regulatory concerns can also be
considered as significant blockchain integration challenges.
2) Open Research Problems
•How to reduce the transaction fee required to reward the
miners?
•How can the scalability issue of blockchain be resolved
?
•How to standardize the emerging blockchain technolo-
gies to gurantee interoperability ?
•How can blockchain survive the privacy and new secu-
rity threat ?
•Can blockchain survive quantum resistance ?
•Will the rejection of blockchain based solutions by
regulatory bodies hinder its development effort ?
3) Preliminary Solutions
The proposed on-chain solutions tries to resolve the scala-
bility issue by modifying only elements within a blockchain
while the off-chain solutions improve the scalability by
processing the transactions at outside the blockchain. The
emerging DAG-based approaches are suggested for IoT ap-
plications as a solution to blockchain transaction fee issue.
ISO and ITU has initiated standardization related directives.
Novel conses mechanisms are tested to address blockchain
security and privacy issues. The post quantum schemes are
adapted by blockchain-based solutions to face quantum re-
sistance.
4) Future Directives
The blockchain solutions are vulnerable to various security
threats and a standard framework need to be introduced for
the application developers to follow, so the vulnerabilities can
be minimized. The research community need to analyze the
quantum resistance capability of their blockchain-based solu-
tions and improve the solutions to face the inevitable future.
The lack of standardization is a main reason for regulatory
resistance and this is a major drawback for the widespread
usage of blokchain-based IoT application solutions. Hence, a
standardization approach similar to the mobile communica-
tion technology standards need to be followed for blockchain
as well.
D. EMERGING DIRECTIONS
1) Quantum Resistance
The cryptographic techniques such as Rivest, Shamir, Adle-
man (RSA), and Elliptic Curve (EC) are used to secure
blockchains by protecting stored data [162]. The latest de-
velopments in the quantum computing domain can cause
security issues that have never been considered before. For
example, Shor’s algorithm running on a powerful quantum
computer can break the public-key algorithms in polynomial-
time [163]. These public-key algorithms can be broken in
polynomial-time with Shor’s algorithm on a sufficiently pow-
erful quantum computer [163]. Therefore, the usage of both
public-key crypto systems and hash functions is threatened
by the evolution of quantum computing.
Various quantum computing-based cryptosystems includ-
ing hybrid cryptosystems merge pre-quantum and post-
quantum cryptosystems are introduced to withstand the quan-
tum attacks. For example, Code-based - to support error
correction codes, multivariant-based - to solve the complex
multivariate equations, lattice-based - rely on n-dimensional
spaces with a periodic structure, Isogency-based - to with-
stand the quantum attacks on elliptic curves [163].
Yu-Long Gao et al [164] defined post-quantum blockchain
(PQB) and proposed a secure cryptocurrency scheme
by combining the lattice-based signature scheme with
blockchain together. Tiago M. Fernández-Caramès et al
[163] reviewed some of the post-quantum schemes and an-
alyzed their application to the blockchain. A development
framework for a scalable, quantum-secured permissioned
blockchain named Logicontract (LC) was introduced by Xin
Sun et al [165].
The use of blockchain and other DLTs for numerous
applications has evolved significantly in the last few years.
The main reason for the widespread research interest in
blockchain is its characteristics that we discussed in section 2
due to public-key cryptography and hash functions. The fast
progress of quantum computing which uses methodologies
such as Grover’s and Shor’s algorithms will be an immense
threat to core concepts of blockchain such as public-key
cryptography and hash functions. Therefore, the research
community needs to closely follow the developments in
VOLUME 4, 2016 23
Author et al.: Preparation of Papers for IEEE TRANSACTIONS and JOURNALS
quantum computing and redesign blockchains to withstand
quantum attacks.
2) AI ML Integration
IoT has been a most widely used technology in the recent past
for various application domains. The IoT characteristics and
its issues such as security concerns and micro-transactions
have paved the way to utilize blockchain, AI and ML to
introduce technological improvements in the IoT application
domains [166]. Due to the rapid adoption of IoT, an exsessive
amount of IoT data is getting generated. Therefore, big data
and AI, along with blockchain is vital to accurately analyze
IoT data in real-time [167]
Devrim Unal et al [168] introduces how blockchain with
Federated Learning (FL) can create a secure big data analyt-
ics service for IoT. Zeinab Shahbazi et al [169] applied an
integrated methods of blockchain and ML to create a smart
manufacturing system. Supriya M et al [170] reviewed how
the utilization of ML, big data, and blockchain technology is
important for the health sector advancements.
IX. CONCLUSION
The adoption of IoT applications has hindered due to techni-
cal limitations inherited by IoT. These include data security
and privacy issues, lack of cooperation among IoT platforms,
the requirement of a central payment system, and lack of
anonymity. Therefore, IoT applications require a platform
with characteristics such as decentralization, immutability,
enhanced security, and anonymity to handle their micro-
transactions efficiently and cost-effectively. This paper ana-
lyzes the technical challenges faced by IoT applications and
the suitability of blockchain-based solutions to address those
challenges. Especially, the IoT payment transactions and data
sharing marketplaces can be deployed by using blockchain-
based technologies. In this research paper, we have identi-
fied the IoT application areas such as smart health, smart
agriculture, IoVs, smart manufacturing, and content trading
as some of the major IoT application domains that have
shown promising results with blockchain-based solutions.
Even though blockchain-based solutions and DAG-based
solutions show promising results, they also have integration
challenges such as the issue of the transaction fee, scalability
issues in terms of transactions and storage, security and
privacy issues, and the latest challenge: quantum resistance
that needs to be addressed before being the next revolution of
IoT to achieve its true potential.
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AMILA SAPUTHANTHRI (Member, IEEE) re-
ceived his B.Sc. degree (First Class Honours) in
Electronic and Telecommunication Engineering
and M.Sc. degree in Telecommunications from
University of Moratuwa, Moratuwa, Sri Lanka,
in 2014 and 2019 respectively, and is currently
reading for the Ph.D. degree in Electrical and
Electronic Engineering from the University of Sri
Jayewardenepura,Ratmalana, Sri Lanka. He is also
working as a Lead Engineer at Dialog Axiata PLC
currently. His research interests are telecommunication, cloud computing,
IoT and Blockchain.
MADHUSANKA LIYANAGE (S07, M16, SM20)
received his B.Sc. degree (First Class Honours)
in electronics and telecommunication engineering
from the University of Moratuwa, Sri Lanka, in
2009, the M.Eng. degree from the Asian Institute
of Technology, Thailand, in 2011, the M.Sc. de-
gree from the University of Nice Sophia Antipolis,
France, in 2011, and the Doctor of Technology
degree in communication engineering from the
University of Oulu, Finland, in 2016. From 2011
to 2012, he worked a Research Scientist at the I3S Laboratory and Inria,
Shopia Antipolis, France. He is currently an assistant professor/Ad Astra
Fellow at School of Computer Science, University College Dublin, Ireland.
He is also acting as an adjunct Processor at the Center for Wireless Commu-
nications, University of Oulu, Finland. He was also a recipient of prestigious
Marie Skłodowska-Curie Actions Individual Fellowship during 2018-2020.
During 2015-2018, he has been a Visiting Research Fellow at the CSIRO,
Australia, the Infolabs21, Lancaster University, U.K., Computer Science
and Engineering, The University of New South Wales, Australia, School of
IT, University of Sydney, Australia, LIP6, Sorbonne University, France and
Computer Science and Engineering, The University of Oxford, U.K. He is
also a senior member of IEEE. In 2020, he has received "2020 IEEE ComSoc
Outstanding Young Researcher" award by IEEE ComSoc EMEA. Dr. Liyan-
age’s research interests are 5G/6G, SDN, IoT, Blockchain, MEC, mobile and
virtual network security. More info: http://www.madhusanka.com
CHAMITHA DE ALWIS (Member, IEEE) is a
Senior Lecturer/Head of Department in the De-
partment of Electrical and Electronic Engineering,
Faculty of Engineering, University of Sri Jayewar-
denepura, Sri Lanka. He also provides consultan-
tancy services in the areas of telecommunication,
4G, 5G, IoT, and network security. He received the
B.Sc. degree (First Class Hons.) in Electronic and
Telecommunication Engineering from the Univer-
sity of Moratuwa, Sri Lanka, in 2009, and the
Ph.D. degree in Electronic Engineering from the University of Surrey,
United Kingdom, in 2014. He has published over 20 peer-reviewed articles,
contributed to various national and international projects related to ICT, and
served as a reviewer and TPC member in several international journals and
conferences. He has also worked as a Consultant to the Telecommunication
Regulatory Commission of Sri Lanka, an Advisor in IT Services in the
University of Surrey, United Kingdom, and a Radio Network Planning and
Optimization Engineer in Mobitel, Sri Lanka. His research interests include
5G, 6G, IoT, blockchain, and network security.
28 VOLUME 4, 2016
