Internet of Everything (IoE) - From Molecules to the Universe

Abstract

As the Internet of Things (IoT) technologies continue to advance, they are becoming increasingly specialized and compartmentalized into non-interacting application domains, which we call IoXs with X referring to the particular application areas, e.g., Internet of Energy (IoEn), Internet of Vehicles (IoV). This trend has also led to the emergence of unconventional IoXs, such as the Internet of Nano Things (IoNT), further increasing the heterogeneity of the future IoT landscape, in terms of not only the underlying technologies but also the spatiotemporal scale and medium of applications, as well as the material nature of things and the type and semantics of data produced and exchanged. This paper explores the potential synergies and opportunities that may arise from such diversity through the interactions between heterogeneous IoXs, enabling unprecedented applications beyond the current confines of IoT. Inspired by the ubiquitous connectivity and seamless interoperability of the universe, which is a vast network of heterogeneous entities interconnected through various forms of interactions (e.g., chemical, electromagnetic, acoustic, and gravitational), we propose the Internet of Everything (IoE) framework. The IoE framework aims to facilitate cooperation of both existing and future IoXs on a diverse scale ranging from molecules to the universe. We discuss potential IoE applications that can be enabled by such synergies and identify the unique challenges for bringing this holistic IoE picture into reality. To address some of these challenges, we propose a layered network architecture for IoE, which includes an IoE middleware that provides a semantic interface among IoXs based on the introduced concept of 'IoX-as-a-Service'. Lastly, we recommend future research directions for enabling the IoE applications.

Full text

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Internet of Everything (IoE) - From Molecules
to the Universe
Ozgur B. Akan, Fellow, IEEE, Ergin Dinc, Member, IEEE, Murat Kuscu, Member, IEEE,
Oktay Cetinkaya, Senior Member, IEEE, Bilgesu A. Bilgin, Member, IEEE
Abstract—As the Internet of Things (IoT) technologies continue
to advance, they are becoming increasingly specialized and com-
partmentalized into non-interacting application domains, which
we call IoXs with X referring to the particular application areas,
e.g., Internet of Energy (IoEn), Internet of Vehicles (IoV). This
trend has also led to the emergence of unconventional IoXs, such
as the Internet of Nano Things (IoNT), further increasing the
heterogeneity of the future IoT landscape, in terms of not only
the underlying technologies but also the spatiotemporal scale and
medium of applications, as well as the material nature of things
and the type and semantics of data produced and exchanged.
This paper explores the potential synergies and opportunities that
may arise from such diversity through the interactions between
heterogeneous IoXs, enabling unprecedented applications beyond
the current confines of IoT. Inspired by the ubiquitous connectiv-
ity and seamless interoperability of the universe, which is a vast
network of heterogeneous entities interconnected through various
forms of interactions (e.g., chemical, electromagnetic, acoustic,
and gravitational), we propose the Internet of Everything (IoE)
framework. The IoE framework aims to facilitate cooperation of
both existing and future IoXs on a diverse scale ranging from
molecules to the universe. We discuss potential IoE applications
that can be enabled by such synergies and identify the unique
challenges for bringing this holistic IoE picture into reality.
To address some of these challenges, we propose a layered
network architecture for IoE, which includes an IoE middleware
that provides a semantic interface among IoXs based on the
introduced concept of ‘IoX-as-a-Service’. Lastly, we recommend
future research directions for enabling the IoE applications.
Index Terms—Internet of Everything.
I. INTRODUCTION
Universe is a vast heterogeneous network of ‘every-
thing’, ranging from molecules to the planets. Some of the
most complex phenomena, e.g., evolution and conscious-
ness, are believed to be rooted in complex interaction net-
works that create more information than the interacting
parts. This ubiquitous connectivity of the universe and the
‘more than the sum’ characteristics of the underlying hetero-
geneous networks are the two main traits inspiring the Internet
O. B. Akan, E. Dinc, and B. A. Bilgin are with the Internet of Ev-
erything (IoE) Group, Department of Engineering, University of Cam-
bridge, Cambridge CB3 0FA, UK (e-mail: {oba21, bab46}@cam.ac.uk,
ed502@cantab.ac.uk).
M. Kuscu and O. Cetinkaya are with the Center for neXt-generation Commu-
nications (CXC), Department of Electrical and Electronics Engineering, Koc¸
University, Istanbul 34450, Turkey (e-mail: {mkuscu, ocetinkaya}@ku.edu.tr).
O. B. Akan is also with the Center for neXt-generation Communications
(CXC), Department of Electrical and Electronics Engineering, Koc¸ University,
Istanbul 34450, Turkey (e-mail: akan@ku.edu.tr).
This work was supported in part by the ERC project MINERVA (ERC-2013-
CoG #616922), AXA Research Fund (AXA Chair for Internet of Everything
at Koc¸ University), The Scientific and Technological Research Council of
Turkey (TUBITAK) under Grant #120E301, and EU Horizon 2020 MSCA-IF
under Grant #101028935.
of Everything (IoE) framework that we introduce in this paper,
representing a big step beyond the confines of the Internet of
Things (IoT) applications.
IoT has long been under the scope of both academia and
industry, with several sophisticated applications, e.g., smart
meters in energy grids, industrial and agricultural wireless
sensor networks (WSNs), that found their way into the market.
One of the limitations of IoT is the lack of interaction between
its branches, i.e., Internet of Xs (IoXs), each targeting only a
specific application domain (X). For example, the Internet of
Vehicles (IoV) aims to establish networks of smart vehicles
to optimize traffic flow at a lower environmental/operational
cost [1]. However, it has no direct liaison with other domains,
such as industrial plants (Internet of Industrial Things - IIoT)
or agricultural fields (Internet of Agricultural Things - IoAT),
which could benefit from the networking capabilities of IoV
to attain a better efficiency vs. cost index. This apparent dis-
connection between IoXs leads to a short-sighted perspective
missing out on many opportunities and synergies that lay in the
interaction of heterogeneous technologies, which can generate
higher value than that of the sum of individual IoXs.
IoE takes a holistic approach and aims to link existing IoXs
based on novel interaction pathways defined among them.
Such interactions may enable, for example, a blockchain-
based energy market where consumers trade energy directly
with each other and with the grid (instead of retailers) via
energy tokens, which is a by-product of the Internet of Money
(IoM) and Internet of Energy (IoEn) merger [2], [3]. IoV can
be integrated with these two for peer-to-peer (P2P) vehicle
charging (using the same tokens), lowering waiting times and
pressure on scarce resources through efficient energy cooper-
ation between peers. Yet, this ambitious goal requires optimal
matching of donor and recipient vehicles by real-time tracking
of their locations and battery levels, which can be achieved by
the Internet of Space (IoSP) seamlessly communicating with
the IoM, IoEn, and IoV within the IoE framework.
The proposed IoE framework goes beyond merely con-
necting existing IoXs. Taking inspiration from the ubiquitous
connectivity and heterogeneous networking characteristics of
the universe, IoE also facilitates the integration of new and
unconventional IoXs into its framework. One of these IoXs is
the Internet of Nano Things (IoNT), a collaborative network of
smart nanomachines and biological agents, which is poised to
increase the resolution of cyber-physical interfaces and bring
connectivity into uncharted territories, e.g., inside human body
[4]. Another example is the Internet of People and Senses
(IoPS), which defines a set of applications enabled by the
conceptual transfer of information between human brains, in-

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INTERNET
Internet of Space (IoSp)
Internet of Agricultural Things (IoAT)
Internet of Vehicles (IoV) Internet of Money (IoM)
Industrial IoT (IIoT)
Internet of Nano Things (IoNT)
Car batteries
Aero and battery token, P2P vehicle charging
Bio-cyber
interfaces
Health monitoring of plants and cattle
Tactile internet
& skill transfer
INTERNET OF
EVERYTHING
Digital commerce
Secure
update Brain
token
Farmland
connectivity
Internet of Plants and Animals
High-
performance
grids
Industrialized
farming
Reliable
operation
Energy
token
Blockchain-
based energy
market
Telepathic
driving
Internet of Energy (IoEn)
Internet of People and Senses (IoPS)
Pipeline
monitoring
Energy-efficient
and sustainable
farming
Figure 1. The envisioned IoE landscape with example interaction pathways enabled between different IoXs.
cluding the nonverbal communication of senses, e.g., olfaction,
and memories [5]. Integrated with the existing IoXs within
the IoE framework, these unconventional IoXs may potentially
facilitate seamless cyber-physical interfaces with the universe,
granting humans an unprecedented level of control over nature.
Our objective in this paper is to explore the potential
synergies and opportunities that can be enabled by the in-
teractions of heterogeneous IoXs within the IoE framework,
some of which are illustrated in Fig. 1. To this end, we first
discuss the state-of-the-art in key IoXs, including those that
are well-established, such as IIoT, IoAT, IoM, IoV, and IoEn,
as well as those that are still in early stages of development,
such as IoNT and IoPS, and identify novel opportunities
for cross-domain synergies. We illustrate these opportunities
through practical IoE applications that span a wide range of
scales, from molecules to the universe, and incorporate both
inanimate human-made and autonomous natural objects. We
identify unique challenges that arise beyond those encountered
in IoT, due to significantly increased diversity regarding the
spatiotemporal scale and medium of applications, material
nature of things, as well as syntax and semantics of gener-
ated and communicated data. We propose a layered network
architecture for IoE that may help overcome some of the
identified challenges, such as interoperability, scalability, and
integration of autonomous things. As part of this architecture,
we also discuss the key properties of an IoE middleware that
can be developed with a service-oriented approach based on
the introduced IoX-as-a-Service concept.
Cross-domain interactions in IoT have been addressed in
literature from various perspectives. For example, strategies to
enable an interoperable IoT ecosystem that allows integrating
vertical IoT platforms and creating cross-domain applications
were discussed in [6] as part of the H2020 symbIoTe project.
Similarly, cross-domain solutions were developed for semantic
interoperability of heterogeneous IoT platforms in the inter-
IoT project [7]. However, existing approaches in literature have
not considered the integration of unconventional or upcoming
IoXs with significantly diverse characteristics into such cross-
domain frameworks, thereby overlooking the opportunities that
an all-embracing integrative approach, such as IoE, can offer.
This paper introduces the innovative IoE framework that
transcends the limitations of existing IoT approaches. Our key
contributions include presenting a diverse range of novel IoE
applications that unveil the transformative potential of our
proposed framework, identifying unique challenges arising
from the interactions between heterogeneous IoXs, proposing
a layered network architecture for IoE that incorporates novel
design elements to address the challenges of interoperability,
scalability, and integration of autonomous things, including
a service-oriented IoE middleware based on IoX-as-a-Service
concept. The perspectives and introductory proposals given
here aim to inspire academia and industry to explore and in-
novate beyond the current boundaries of IoT towards enabling
previously unattainable levels of connectivity and control.
II. IN TE RN ET O F XS(IOXS)
This section explores some of the existing and upcoming
IoXs with applications spanning diverse scales ranging from
molecular scale to the scale of planets. We examine the latest
developments in these pillars, the diverse technologies they
employ, and the benefits they offer both now and in the future.

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INTERNET
Health-care
provider
Interconnected
Body-Area
Nanosensor
Networks
Alzheimer & Epilepsy
Monitoring and Brain
Stimulation Nanonetworks
Heart
Monitoring
Networks
(a) (b)
(c)
(d)
(e)
SiO2
Functionalized Si
graphene
Information
molecules
Insulated gold
contacts
Electrical stimuli
responsive hydrogel
Reservoir
walls
Nanoporous
graphene
Nano-processor
Piezoelectric zinc oxide
energy harvesting unit
Graphene plasmonic
THz nano-transceiver
Nano-memory
Graphene
nanosensor
Nanoactuator
Graphene
Plasmonic Waves
Incoming
THz-EM Wave
Graphene Nanoribbon
Dielectric
Metal
Cancer
Monitoring/Drug
Delivery Networks
Bio-cyber
interface
Figure 2. (a) Conceptual drawing of a continuous health monitoring application of IoNT. (b) MC among engineered bacteria within IoNT. (c) Graphene-based
nanoscale MC transmitter & receiver architectures. (d) EH nanomachine architecture for IoNT. (e) Graphene plasmonic nanoscale THz transceiver architecture.
A. Internet of Nano Things (IoNT)
Nanotechnology has enabled the manipulation of individual
atoms to develop new nanomaterials with exceptional char-
acteristics and the design of nanoscale machines interfacing
with the physical universe at the molecular level. The idea
of IoNT, as illustrated in Fig. 2, lies in interconnecting
nanomachines of different functionalities to overcome their
resource limitations and increase their operational capabilities,
besides integrating these nanonetworks with the conventional
electromagnetic (EM) wireless networks through nano-macro
and bio-cyber interfaces to enable unprecedented applications,
such as intrabody continuous health monitoring [4].
Research in this field has been focusing on physical layer
design, where terahertz (THz)-band EM and molecular com-
munications (MC) [8] are the most promising approaches to
enable reliable information transfer at the nanoscale. MC,
being already realized by living cells, provides a more bio-
compatible ground for developing artificial nanonetworks;
thus, it has attracted the most attention. IoNT research pri-
oritizes developing channel models, nano-transceiver archi-
tectures, modulation/detection techniques, and communication
protocols for MC [9]. However, there is still an immense
discrepancy between the complexity of the developed methods
and the resource limitations of nanomachines, requiring further
interdisciplinary research efforts.
B. Internet of People and Senses (IoPS)
Sharing human cognitive functionalities and senses through
the Internet, i.e., IoPS, can create many groundbreaking appli-
cations. The interconnection of human brains, i.e., Brainets, for
an advanced network-scale consciousness leading to higher-
level intelligence and for new forms of direct conceptual com-
munication and collaboration among people, is the ultimate
goal of the IoPS vision [5]. The still-evolving IoPS adopts
many other technologies gaining maturity. For example, the
Tactile Internet, i.e., real-time sharing of touch and actuation,
enabling the transfer of skills and labour, has already found
applications in remote healthcare, education, and gaming. Re-
search towards digital communication of smell and taste is also
gaining momentum, promising new forms of social networking
based on non-verbal communication modalities [10].
Applications of IoPS can be diversified towards human
augmentation, such as mind control over electronic devices,
internet access by thought, and enhanced sensory capabilities
in a wider EM and acoustic spectrum. However, such ap-
plications necessitate overcoming fundamental challenges in
instrumentation and brain research.
C. Industrial Internet of Things (IIoT)
The fourth industrial revolution, namely Industry 4.0, strives
for the combination of Internet and future-oriented technolo-
gies with already electrified and automated industrial machin-
ery (Fig. 3). It aims to optimize industrial processes, increase
productivity, reduce costs, and improve product quality. IIoT
requires a combination of hardware, software, and commu-
nication technologies, including sensors, cloud computing,
data analytics, and AI. The main benefits of IIoT include
real-time monitoring, predictive maintenance, and automation,
which can help companies make more informed decisions and
improve their operations. The forthcoming Industry 5.0 Era
[11] is expected to better fit into this purpose as well as the IoE
framework by interconnecting several IoXs. The widespread
adoption of IIoT technologies will bring significant benefits to
industries, businesses, and society as a whole.
D. Internet of Vehicles (IoV)
The integration of vehicles in the IoT domain and their
interaction with other vehicles, pedestrians, (network) infras-
tructure, and road-side units, also termed vehicle-to-everything
(V2X) communications, has converted the old Vehicular Ad
Hoc Networks (VANETs) into the IoV concept [1]. The ulti-
mate goal of IoV is to establish a network of “smart” vehicles
that exchange information for coordinating their automated
behaviour to minimize risks and maximize traffic flow at lower
emission, cost, and energy consumption.
The multidisciplinary nature of IoV comprises a variety of
technologies and standards, including wireless communication
protocols, such as 5G and Wi-Fi, WSNs, big data analytics,

4
and AI, to offer novel safety, mobility, and infotainment ser-
vices. Intelligent traffic management, predictive maintenance,
and connected/autonomous vehicles can only be achieved by
the seamless interoperation of these technologies. Since cities
become more interconnected as days pass, they offer the
ideal conditions for IoV proliferation while helping connected
vehicles gradually transform into autonomous entities.
E. Internet of Money (IoM)
Cryptocurrencies have emerged to tackle the inefficiencies
of the conventional banking system, e.g., long account opening
and transaction processing times. They utilize blockchain tech-
nology [2], which is based on a distributed ledger system with
no central ledger, i.e., a bank approving transactions. Here, the
cryptocurrency miners serve as the distributed ledger to gener-
ate cryptocurrencies, offering improved reliability, flexibility,
and security. Cryptocurrency wallets can be obtained instantly
anywhere by anyone, and transactions can be made online in
minutes without any border or cost. Hence, cryptocurrencies
are regarded as the money of the Internet, i.e., IoM, and their
value is stored by the connectivity of distributed ledger. Thanks
to enabling faster, securer, and more transparent transactions
between peers, IoM presents huge potential for a variety
of industries and sectors, e.g., e-commerce, automotive, and
energy, with many innovative applications.
F. Internet of Energy (IoEn)
The centralized nature of the existing electricity grid results
in wasted energy due to supply&demand imbalances. It is also
inflexible when it comes to incorporating renewable energy
sources. The Smart Grid concept was developed to create a
decentralized and flexible grid using smart meters, actuators,
and WSNs [3]. This concept automates the grid by monitoring
supply&demand in real-time, resulting in higher efficiency.
The broader concept of IoEn includes other forms of energy,
such as gas and water, and aims to create a seamless network
for energy generation, storage, distribution, and consumption.
IoEn also covers powering WSNs, where battery life is a
concern, as non-deterministic battery depletion means unreli-
able sensors and high maintenance costs. EH and WPT can
help by making sensors energy-autonomous, but harvestable
sources like solar are often dependent on external factors,
imposing another challenge. One way to alleviate this is
to use multiple EH mechanisms to increase reliability and
self-sufficiency [12]. Additionally, energy-efficient sensing,
computation, and communication techniques are essential for
uninterrupted operations in the IoEn.
G. Internet of Space (IoSp)
Communication satellites (CSs) are a crucial component
of the IoE framework. Besides the high-throughput satellites
(HTSs) meeting the growing data traffic demand, small CSs
are increasingly being deployed into low Earth orbit (LEO) and
formed into massive constellations, such as those by SpaceX
and OneWeb. LEO constellations provide truly global and
ubiquitous connectivity, which provides coverage to oceans
and sparsely populated areas where otherwise uncovered [8].
Therefore, IoSp will be the backbone of IoXs in the areas
where today’s communication infrastructure has not reached.
Advancements in space expeditions by private companies
like SpaceX and Blue Origin have made populating space with
human artifacts cheaper and faster. However, the idea of using
CSs to support human colonization of Mars is still speculative.
Deploying CSs around its orbit could enable the establishment
of the Internet on Mars and joining it with the Internet on
Earth, forming a greater Internet called IoSp; yet the technical
challenges of this endeavor are significant. Nevertheless, IoSp
adoption has the potential to enable new business models, sci-
entific discoveries, and exploration missions while improving
satellite navigation and global connectivity.
H. Internet of Agricultural Things (IoAT)
In the last decade, smart agriculture technologies, such as
farmland WSNs, have become popular due to increasing food
demand, food security, and health concerns. IoAT refers to
information and communication technology (ICT) applications
in agriculture, including smart farming, food logistics, process-
ing, and awareness, aiming to integrate every aspect of agri-
culture to improve efficiency, productivity, and sustainability.
Existing IoAT applications include precision agriculture
with high-accuracy weather forecasts and livestock health
monitoring enabled by wearable sensors, energy-neutral
drones [13], water-efficient irrigation systems, real-time track-
ing of products for food awareness and supply chain planning
[14]. Developing predictive analytics tools to analyze the volu-
minous data generated by the heterogeneous IoAT components
is a major topic. Looking forward, ongoing advancements in
IoAT technologies, combined with emerging fields, such as
blockchain and AI, are expected to drive further innovation
and transformation across the entire agriculture value chain.
III. INT ER NE T OF EVERYTHING
This section provides an overview of the applications
emerging from unique IoX interactions. It also discusses the
challenges that arise from these synergies, proposes an IoX-as-
a-Service approach within the IoE architecture, and highlights
potential future directions for achieving a fully-fledged IoE.
A. Applications
IoE aims to enable the development of novel applications
by creating synergy among distinct IoXs through the facilita-
tion of their functional interactions. These have found many
examples in practice, including the ones already established or
currently gaining maturity, besides the ones requiring further
investigation/advancement in their respective fields. Below, we
enumerate some of these applications:
•Pipeline monitoring in industrial plants and oil&gas distribu-
tion systems with (nano)sensors detecting leaks, blockages,
or impurities to satisfy regulations (IoNT, IIoT, & IoEn),
•Bio-cyber interfaces that translate biochemical signals from
intrabody nanonetworks into electrical terms, and vice versa,
for seamless biotic-abiotic interactions enabling the devel-
opment of new medical devices that work with the body’s

5
Mechanization
·Mechanical production
·Water and steam power
·1st mechanical loom
Electrification
·Mass production
·Diversion of labour
·1st assembly line
Automation
·Automated production
·Computers
·Electronics
·IT systems
·1st PLC
Digitalization
·Cyber physical systems
·(Industrial) IoT
·Robotics and AI
·Big Data
·Cloud Computing
·Cyber-physical cognitive systems
·Mass customization
·Human-robot co-working
·Exoskeletons
·6G and beyond
·Industrial blockchain
·Mixed reality
- 1784 - - 1870 - - 1969 - - 2011 -
Industry 2.0 Industry 3.0 Industry 4.0 Industry 5.0
Industry 1.0
Personalization
- Near Future -
Figure 3. History of the industrial revolution, revealing how the adaptation of the Internet marked the new epoch (Industry 4.0) almost a half-century earlier.
own systems and providing doctors with real-time updates
on patient health (IoNT & IoPS),
•Validating blockchain transactions and thus mining cryp-
tocurrencies or brain tokens using bodily functions, such as
body heat/fluids and brain activities, i.e., replacing the high-
powered computing equipment of traditional cryptocurrency
mining, thereby offering a more sustainable and efficient
solution (IoPS & IoM),
•Realizing telepathic driving via brain-to-vehicle technology,
thus redefining car autonomy with mind-controlled steering,
powertrain, and brake systems (IoPS & IoV),
•Precision agriculture by the seamless cooperation of weather
data, farming tools, and irrigation systems (IIoT & IoAT),
•Minimizing downtimes, balancing supply&demand, and re-
alizing predictive maintenance in power grids (IIoT & IoEn),
•Avoiding disruptions, keeping a better inventory, and main-
taining quality in supply chains through data-driven insights,
i.e., ever-efficient process management (IIoT & IoM),
•P2P charge trading between electric cars (IoV, IoM & IoEn),
•Dynamic traffic congestion control, transport capacity max-
imisation, and smart parking in cities (IoV & IoSp),
•Safe and reliable vehicle-assistance systems via networked
miniature sensors spread into vehicles to track proximity
and environmental conditions in real-time (IoV & IoNT),
•Phenotype creation (by determining growth/health status)
and cattle tracking through dynamic multimedia aerial mon-
itoring of plants (IoAT & IoV),
•Blockchain-based energy markets enabling consumers to
trade energy directly from the grid (IoM & IoEn),
•Skill transfer between humans using brain tokens for remote
healthcare, education, and arts services (IoPS & IoM),
•Blockchain-based precision tracking of manufactured prod-
ucts in the supply chain (IIoT & IoM),
•Real-time tracking of vehicle locations/battery states and
nearby charging stations’ capacity/status for optimal vehicle-
station matching, thereby minimizing waiting times and
pressure on scarce resources (IoV, IoSp, IoEn),
•Satellite-driven secure software updates for autonomous &
connected cars (IoV & IoSp),
•Reliable operation of the crypto market without cyber-
attacks and/or government censorship (IoSp & IoM),
•Securer and faster farmland connectivity (IoAT & IoSp),
•Creating a digital twin of the human body for precision and
predictive medicine (IoPS & IoNT),
•Distributed emergency service and automated search and
rescue with energy-neutral drones (IoV, IoEn, & IoSp).
The above-given list is by no means exhaustive, but it
displays the kind of range that is available or on the horizon.
However, the challenges posed by these interactions, as well
as those that are inherent to IoT, must be addressed in order
for IoE to reach its envisioned potential.
B. Challenges
The ambitious and holistic objective of integrating diverse
IoXs presents a range of challenges. While some of these
challenges are unique to the IoE framework, others are simply
magnified versions of the difficulties that we already encounter
when devising IoT applications.
1) Interoperability: IoT platforms are characterized by their
heterogeneity in terms of device and communication technolo-
gies. Most IoT applications require utilizing various devices
that are produced by different companies, which may be in-
compatible with each other due to relying on different sensing
and communication standards and protocols. This complexity
of this so-called interoperability problem is amplified in IoE
due to the broader diversity of interconnected things, ranging
from natural or biosynthetic cells, to living plants, satellites,
and conventional gas sensors. These things vary significantly
in terms of materials, size, functions, operating mechanisms,
and sensing, computing, and communication capabilities.
Moreover, IoE applications integrating several IoXs of differ-
ent scales can now span a wider range of environments, further
compounding the interoperability challenge, particularly in
terms of communication technologies. For example, in a
scenario where IoAT and IoNT are interacting, the application
environment may extend from the intrabody of an animal (for
continuous health monitoring) to a farmland or a factory (for
collection, delivery, and processing of agricultural products),
each of which poses different communication requirements.
2) Big Data: The integration of multiple IoXs naturally
increases the amount of data that are to be processed for
IoE applications. In connection with the device heterogeneity
amplified in IoE, not only the volume of data but also the
variety of data in a typical IoE application may significantly
increase. For example, data generated by biotic things in IoE
may syntactically and semantically differ substantially from
the data exchanged among abiotic devices.
3) Resource Management: The extended range and variety
of environments and things in IoE may result in increased vari-
ation in the nature and availability of device, communication,
and energy sources. Thus, IoE demands more dynamic man-
agement of these sources to ensure the QoS of its applications.

6
IoX Layer
IoE Middleware Layer
IoE Application Layer
IoAT
Application Layer
Middleware Layer
Network Layer
Perception Layer
IoV
Application Layer
Middleware Layer
Network Layer
Perception Layer
IoNT
Application Layer
Middleware Layer
Network Layer
Perception Layer
IoX-as-a-Service
Service discovery
Service call
Service integration
Semantic interface
Data processing
Resource management
INTERNET
Continuous intrabody
health monitoring Precision agriculture
Dynamic route
optimization
...
QoS, privacy, security
Figure 4. IoE architecture based on IoX-as-a-Service approach.
4) Scalability and Flexibility: With its holistic and all-
embracing nature, IoE should be scalable to seamlessly inte-
grate new IoXs with currently unknown technologies into its
framework, and should be flexible to accommodate the new
functions, services, and applications made available by still-
evolving IoXs, such as IoNT and IoPS. Rather than imposing
standards on the existing and evolving or upcoming IoXs,
which is a challenging task even in the current IoT landscape,
IoE should facilitate a fundamental-level dialog between IoXs,
insulated from the complexities of individual IoXs.
5) Integration of Autonomous Things: Diverging signifi-
cantly from IoT, IoE integrates IoXs that can comprise living
things, such as plants, animals, and natural and synthetic
biological cells, which are characterized by autonomy, the
ability to self-organize and -produce. In contrast to the fully
artificial nature of IoT, where all the things and their interac-
tions are heteronomous and can be programmed and controlled
externally, engaging biotic things with autonomous behaviors
in IoE applications may require semantically and syntactically
different approaches in establishing their interfaces with abi-
otic devices and systems. This challenge can be also relevant
for IoE applications involving AI-integrated IoXs since ad-
vances in AI are leading to increasingly autonomous behaviors
in artificial devices and systems. Nevertheless, flourishing
research in semantic information and communication theories
and tools holds promise for addressing such challenges.
C. IoE Architecture
Many challenges in IoT including interoperability, big data,
and resource management, are being targeted with middleware
solutions, which are typically a set of software that runs
on the cloud and ensure the QoS of IoT applications by
mediating and coordinating interactions among heterogeneous
devices and networks, and processing the generated data. In
the layered architecture of IoT, the middleware layer provides
isolation between the physical layer and the application layer,
allowing the application designers to develop applications
without dealing with the heterogeneity of the underlying
device and communication technologies. Various middleware
layer architectures have been proposed for IoT, including
service-oriented architecture (SOA), microservices-based and
event-based architectures [15]. However, IoE compounds the
challenges of IoT and poses a new set of challenges, that are
not likely to be addressed by the current middleware solutions
tailored for IoT. It is, therefore, necessary to introduce an
additional layer of isolation with a second middleware layer,
i.e., IoE middleware, at the application/IoX level, leaving
specific IoX-level challenges to the IoX middleware.
In light of these considerations, we propose a logical layered
architecture for IoE with a service-oriented IoE middleware
to facilitate the design of IoE applications involving diverse
IoXs interacting with each other. Our proposed architecture,
depicted in Fig. 4, comprises three distinct logical layers: the
IoX layer, the IoE middleware layer, and the IoE application
layer. In this service-oriented architecture, we consider each
IoX in the IoX layer as a service, an approach we term as
IoX-as-a-service. These IoXs are located in the bottom layer
of this architecture, each with its own distinct IoX-layered
architecture, thereby affording a degree of independence in
the design and operation of individual IoX services.

7
The IoE middleware layer is responsible for the discovery,
call, and integration of the required IoX services, besides
managing their interactions in terms of data, events, and re-
sources to enable an application defined in the IoE application
layer. The layer manages interactions among IoXs through
high-level interfaces, which address the interoperability chal-
lenges primarily through the alignment and translation of
IoX-specific semantic ontologies, while the syntactic interop-
erability among physical devices within a particular IoX is
largely managed by the corresponding IoX middleware. The
IoE middleware layer also addresses non-functional require-
ments, e.g., security, privacy, scalability and flexibility, and
integration of autonomous things. To ensure efficient and fair
resource utilization, the IoE middleware engages in cross-layer
interaction with individual IoX middleware layers, enabling
dynamic modifications to their behavior for optimal resource
allocation and management.
D. Future Directions
The IoE architecture requires addressing several further
challenges, including the abstraction of IoXs as services
through the formalization of their semantics in a way that
maintains insulation between the IoE application design and
IoX-specific architectural and technological details, as well
as finding a common set of semantics to facilitate inter-IoX
interactions. These challenges are further compounded by the
fact that many of the IoXs that are envisioned as part of the
IoE are still evolving in terms of the functions they offer, and
are still at the very early stages of standardization in terms of
the underlying technologies. Additionally, the IoE landscape
is likely to be complemented by new IoXs relying on new
device and communication technologies. Therefore, the IoE
middleware layer must be flexible to accommodate such
variations in semantics, which can be achieved by building
interfaces based on fundamental-level ontologies common to
all IoXs and leaving the IoX-specific intricacies to be handled
by individual IoX middleware layers.
Other practical steps to advance the IoE include the develop-
ment of new communication techniques orthogonal to conven-
tional EM methods to extend the connectivity, the development
of universal transceivers that support multiple communication
modalities to provide physical-layer interoperability, and the
design of hybrid and adaptive EH methods that can be imple-
mented by things in various dynamic environments.
IV. CONCLUSION
This paper brings to the forefront the potential of the upcom-
ing IoE revolution by showcasing the practical applications
that can be enabled through the synergistic interactions among
various IoT application domains, referred to as IoXs. Adopting
an IoX-as-a-Service approach, we propose a logical layered ar-
chitecture for the IoE, which includes an IoE middleware layer
that manages IoX interactions and addresses the challenges
of interoperability, big data, and dynamic resource allocation.
This service-oriented IoE architecture has the potential to
integrate the evolving and upcoming IoXs, such as IoNT and
IoSp, into the holistic IoE framework, thereby complementing
the existing IoXs and fostering large-scale connectivity and
control, from molecular levels to the confines of the universe.
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Ozgur B. Akan received his PhD degree from the Georgia Institute of Tech-
nology, Atlanta, GA, USA, in 2004. He is currently the Head of the Internet
of Everything Group, Department of Engineering, University of Cambridge,
UK, and the Director of the Center for neXt-generation Communications
(CXC), Department of Electrical and Electronics Engineering, Koc¸ University,
Turkey. His research interests include wireless, nano, molecular, and neural
communications, and the Internet of Everything.
Ergin Dinc received his PhD degree in Electrical and Electronics Engineering
from Koc¸ University, Turkey, in 2016. After his PhD, he held postdoctoral
positions at KTH Royal Institute of Technology, Sweden, and University of
Cambridge, UK. At the time of this study, he was with the Internet of Every-
thing (IoE) Group, Department of Engineering, University of Cambridge. His
research interests include cyber–physical systems, molecular communications
and satellite communications.
Murat Kuscu received his PhD degrees in Engineering from the University
of Cambridge, UK, in 2020, and in Electrical and Electronics Engineering
from Koc¸ University, Turkey, in 2017. He is currently an Assistant Professor
at the Department of Electrical and Electronics Engineering, Koc¸ University.
His research interests include the Internet of Bio-Nano Things, nanomaterials,
biosensors, and microfluidics.
Oktay Cetinkaya received his PhD degree in Electrical and Electronics
Engineering from Koc¸ University, Turkey, in 2018. After his PhD, he worked
as a postdoctoral researcher at the University of Southampton, UK, and the
University of Sheffield, UK, for two years each. In April 2022, He joined the
University of Oxford as a Senior Research Associate. His research interests
include energy harvesting, drone networking, and the Internet of Things.
Bilgesu A. Bilgin received his PhD degree in Mathematics from Koc¸
University, Turkey, in 2015. After his PhD, he worked as a postdoctoral
researcher at Koc¸ University and the University of Cambridge, UK. His
research interests include molecular communication, intrabody nanonetworks,
and dynamical systems.