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RPL over Internet of Things: Challenges, Solutions, and Recommendations
... The MRHOF considers the Expected Transmission Count (ETX), a strategic routing metric for DODAG construction. A single metric based OF in RPL may fail in energy-efficient DODAG construction under acoustic channel communication [10]. ...
In the course of time, the Internet of Things (IoT) has attracted significant research interest. However, IoT devices have limited resources available in terms of battery power, processing capacity, memory, bandwidth, etc. In an attempt to provide connectivity and Internet Protocol version 6 (IPv6) support to IoT devices, the IPv6 routing protocol for Low-Power and Lossy Networks (RPL) was officially launched as the standard routing protocol for IoT in 2012. Despite being reputed and used in diverse applications, several recent studies have revealed RPL's drawbacks and limitations. The main objective of this work is to help the IoT research community understand all aspects of RPL. The paper also provides a detailed description of the operation of the RPL protocol. What is more, this work includes novel and thorough examples, thereby gaining practical knowledge of the pros and cons of this protocol. In addition, this paper reviews and summarizes relevant RPL-based protocols and conducts comprehensive comparisons among them from the perspectives of reliability, robustness, energy efficiency, and flexibility. Technically speaking, after studying and reviewing the majority of the proposed RPL solutions, we are ultimately capable, in this work, of highlighting all the challenges faced by IoT researchers while enhancing RPL and providing what is expected to be dealt with professionally. The present work also gives more details about RPL simulation platforms and RPL applications. Not only to this extent, but rather the historical bibliometric analysis of RPL, which shows the trends in the area of research to be focused on, has been professionally analyzed based on RPL challenges over the years 2010 and 2021. To this end, the conclusions and recommendations of this study are presented along with the effective directions for future RPL, and their applicability. As a result, the authors believe that this work will be a valuable reference for all RPL researchers and designers.
The indispensable part of IoT is the Low-power and Lossy Network (LLN), which is required to connect plenty of resource-constrained (e.g., power and memory) wireless devices. Interestingly, the IPv6 Routing Protocol for LLNs (i.e., RPL), which is the standard routing protocol for IoT, relies primarily on constructing a destination-oriented directed acyclic graph governed by a variety of routing metrics that help in choosing the Objective Function (OF), which is liable for selecting the best preferred parent of each node which in turn gets involved in the route establishment towards the destination. In fact, establishing an OF based on a single metric, as the majority of research considers, has flaws or drawbacks, as it only benefits a few IoT applications. To put it another way, the network lifetime is improved for a few IoT apps but degraded for the majority. In this article, we address not only the limitation of using a single metric, but also the limitations of those works employed a composite metric by putting forward a cross-layer design and accordingly developing a fuzzy logic system that brings together four input metrics, namely, hop count, energy consumption, latency, and received signal strength indicator as a new OF, abbreviated as FL-HELR-OF. The simulation findings, acquired by the Cooja simulator, prove the effectiveness of our new OF, which particularly outperforms other existing studies concerning the packet delivery ratio, control message overhead, latency, energy consumption, and average hop count.
RPL (IPv6 routing protocol for low power and lossy networks) proposed by the IETF (Internet Engineering Task Force) ROLL (routing over low-power and lossy networks) working group is a de facto standard routing protocol for IoT environments. Since the standardization was proposed, RPL has been extensively improved for diverse application scenarios and environments. Congestion control is one of the most important reasons why RPL has been improved. In an LLN (low power and lossy network), congestion may even lead to network lifetime reduction. In resource-constrained networks where end-to-end congestion control is not feasible, RPL should play a more crucial role in congestion control. In this survey, we review the RPL schemes proposed for congestion control and load-balancing and discuss future research directions.
With the widespread use of IoT applications and the increasing trend in the number of connected smart devices, the concept of routing has become very challenging. In this regard, the IPv6 Routing Protocol for Low-power and Lossy Networks (PRL) was standardized to be adopted in IoT networks. Nevertheless, while mobile IoT domains have gained significant popularity in recent years, since RPL was fundamentally designed for stationary IoT applications, it could not well adjust with the dynamic fluctuations in mobile applications. While there have been a number of studies on tuning RPL for mobile IoT applications, but still there is a high demand for more efforts to reach a standard version of this protocol for such applications. Accordingly, in this survey, we try to conduct a precise and comprehensive experimental study on the impact of various mobility models on the performance of a mobility-aware RPL to help this process. In this regard, a complete and scrutinized survey of the mobility models has been presented to be able to fairly justify and compare the outcome results. A significant set of evaluations has been conducted via precise IoT simulation tools to monitor and compare the performance of the network and its IoT devices in mobile RPL-based IoT applications under the presence of different mobility models from different perspectives including power consumption, reliability, latency, and control packet overhead. This will pave the way for researchers in both academia and industry to be able to compare the impact of various mobility models on the functionality of RPL, and consequently to design and implement application-specific and even a standard version of this protocol, which is capable of being employed in mobile IoT applications.
Energy consumption is a major challenge in IoT devices, which was aimed to be improved by employing energy-efficient Objective Functions (OF) in the structure of RPL routing protocol. Meanwhile, the majority of the existing OFs mainly perform the parent selection based on the gathered information from the routing layer. Nevertheless, based on our investigations, there exists a series of transmission operations in the MAC layer, which significantly affects the energy consumption in IoT devices. Therefore, in this paper we propose ELITE, an energy-efficient cross-layer OF, which introduces a novel routing metric, called Strobe per Packet Ratio (SPR). SPR indicates the number of transmitted strobes per packet due to Radio Duty Cycling (RDC) policies in the MAC layer. This newly defined metric, which has been designed to be coupled with asynchronous MAC protocols, could be differentiated node by node and based on the existing relative phase shift between the communicating nodes. In this regard, ELITE tries to select a path, which imposes less number of strobe transmissions to its nodes. According to the evaluation results, while ELITE could reduce the average amount of required strobes per packet by up to 25%, it can significantly improve the average amount of consumed energy in an IoT node by up to 39% compared to its counterpart OFs.
Sustainable cities are widely adopting the standards of the Internet of Things (IoT) in almost every domain e.g. Smart Grids (SG) to provide services to a sustainable community. It enables two-way communication to manage the energy resources, where routing protocol has a significant role in communication. The diversification of IoT networks arises many challenges for the Routing Protocol for Low Power and Lossy Networks (RPL). The dynamic and lossy environment is one of the key challenges in various IoT networks, specifically SG. RPL does not able to adjust its link metric efficiently against the dynamic and lossy environment, which have a great impact on the performance metrics. To address this issue, we have introduced cognition in RPL by integrating learning automata with the Objective Function (LA-OF). Learning Automata (LA) is applied to Expected Transmission Count (ETX) to tune it according to the environment. LA learns through interacting with the environment and yields the best ETX values, afterwards the environment is monitored to trace down the instability in the environment. The proposed LA-OF is compared with standardized techniques MRHOF and OF0. The simulation results show a significant improvement with overall 7.04% in PRR, 17.52% in energy consumption, and 18.72% in overhead.
Routing Protocol for Low power lossy network (RPL) is emerged to evade the energy issues in the Internet of Things (IoT) network. Although, RPL noticeably satisfies the requirement of the IoT network, still there exist certain open issues to resolve. This paper addresses the problem of routing overhead, packet losses and load imbalance in RPL based IoT network. These downsides are solved using the proposed Dual Context‐based Routing and Load Balancing in RPL based Network (DCRL‐RPL). Primarily, we implement the grid construction where the network area is split into a different level of the unequal grid. The ranking based Grid Selection process is executed to select the optimal grid head node in each grid. The grid head node in the network schedules its member node using the Reputation based Scheduling method. The elected grid head classifies the data received from its member using Adam Deep Neural Network (ADNN) to provide better routing performance. Here, the sensitive and non‐sensitive data are considered as context for objective function selection. At last, the efficacy of the DCRL‐RPL is analyzed using the Network Simulator 3.26 (NS3) tool. From comprehensive validation results, we show that DCRL‐RPL acquires better results.
Recently, IoT has been massively applied in different areas of human life. Meanwhile, in many of the IoT applications, e.g., the remote patient health-care monitoring systems, the reliability of communications, and the consumed energy in IoT devices, which are mostly battery-operated, are very challenging. Since IoT devices are typically operated in lossy environments, providing a reliable transmission for the packets imposes a noticeable amount of energy consumption. In addition, the run-time movement of the IoT devices in mobile networks further intensifies these issues. Therefore, the applied policies in the IPv6 RPL as the standard routing mechanism in IoT networks, play an important role in providing a reliable and energy-efficient packet delivery. Nevertheless, RPL is significantly suffering from low reliability in mobile applications due to the existence of outdated parents in the limited neighbor table of the moving objects. Hence, in this study, we propose REFER; a mobility-aware version of RPL, which provides reliable and energy-efficient communication between IoT devices with utilizing a new neighbor placement policy based on a leasing time of the parents along with considering various node/link metrics for its path selections in mobile situations. Based on our evaluations, which have been conducted in different network configurations and under different mobility models, while REFER has enhanced the amount of energy consumption in the nodes, it is able to improve the reliability of the communications by at least 2.2x compared with its counterpart.
RPL (IPv6 routing protocol for low power and lossy networks) is a standard routing protocol in the Internet of Things (IoT) networks. It is used by nodes which are characterized by limited resources (like energy, memory, processing power, and bandwidth). In the standard RPL routing protocol, the energy consumption balancing during selecting the preferred parents it is not considered that it leads to depleting the battery power of some loaded nodes faster than the other nodes. Besides, the original RPL routing protocol has increased control packets that lead to high energy consumption inside the nodes and decrease the network lifetime. Therefore, to overcome these problems, this article proposed Energy-efficient load-balanced RPL (EL-RPL) routing protocol for IoTs networks. In this protocol, a parent selection algorithm is proposed. It selects the parent in parent list to be the next hop node in the direction of destination node in networks based on an objective function that combine between the highest remaining energy and the total number of received packets by the parent. This can balance the load on the all parents in the parents' list. Besides, the proposed protocol improves the DODAG construction by preventing the DIO packets transmission to the nodes with the lower ranks. This will lead to save energy and hence enhance the networks’ lifetime. Many experiments were performed using the OMNeT++ network simulator to evaluate the efficiency of EL-RPL routing protocol. In comparison with some existing protocol, the results ensure that the proposed EL-RPL protocol can efficiently save energy, decrease the control packets, and improve the lifetime of the IoTs networks.
The RPL routing protocol for low power and lossy networks uses the objective function (OF) to build a Destination Oriented Directed Acyclic Graph (DODAG) based on a set of metrics and constraints. The OF has as the main function to select and specify the best parent or the optimal path to reach the destination. However, proposing an adequate objective function in Low Power and Lossy Networks (LLNs) presents a substantial challenge. In this paper, we propose a survey on existing objective functions in LLNs based on a set of metrics. These metrics can define a node or/and link characteristics. We highlight the advantages and the shortcoming of each studied solution. Furthermore, we propose a classification of the used metrics and the criteria of choice. Then, we present a comparative study of the existing OFs in terms of the required performances of the RPL protocol and we provide a deep statistical analysis of all reviewed papers. Finally, we conclude our contribution by highlighting the different issues and challenges that can be exploited for future works. We believe that this survey will help LLNs researchers’ community to easily understand the objective function concept and contributes to improving RPL in this context for further relevant research works.
The emergence of the Internet of Things (IoT) and its applications has taken the attention of several researchers. In an effort to provide interoperability and IPv6 support for the IoT devices, the Internet Engineering Task Force (IETF) proposed the 6LoWPAN stack. However, the particularities and hardware limitations of networks associated with IoT devices lead to several challenges, mainly for routing protocols. On its stack proposal, IETF standardizes the RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) as the routing protocol for Low-power and Lossy Networks (LLNs). RPL is a tree-based proactive routing protocol that creates acyclic graphs among the nodes to allow data exchange. Although widely considered and used by current applications, different recent studies have shown its limitations and drawbacks. Among these, it is possible to highlight the weak support of mobility and P2P traffic, restrictions for multicast transmissions, and lousy adaption for dynamic throughput. Motivated by the presented issues, several new solutions have emerged during recent years. The approaches range from the consideration of different routing metrics to an entirely new solution inspired by other routing protocols. In this context, this work aims to present an extensive survey study about routing solutions for IoT/LLN, not limited to RPL enhancements. In the course of the paper, the routing requirements of LLNs, the initial protocols, and the most recent approaches are presented. The IoT routing enhancements are divided according to its main objectives and then studied individually to point out its most important strengths and weaknesses. Furthermore, as the main contribution, this study presents a comprehensive discussion about the considered approaches, identifying the still remaining open issues and suggesting future directions to be recognized by new proposals.
Wireless Sensor Networks have become a key enabler for Industrial Internet of Things (IoT) applications; however, to adapt to the derived robust communication requirements, deterministic and scheduled medium access should be used, along with other features, such as channel hopping and frequency diversity. Implementing these mechanisms requires a correct synchronization of all devices in the network, a stage in deployment that can lead to non-operational networks. The present article presents an analysis of such situations and possible solutions, including the common current approaches and recommendations, and proposes a new beacon advertising method based on a specific Trickle Timer for the Medium Access Control (MAC) Time-Slotted Channel Hopping (TSCH) layer, decoupling from the timers in the network and routing layers. With this solution, improvements in connection success, time to join, and energy consumption can be obtained for the widely extended IEEE802.15.4e standard.
Driven by the special requirements of the Low-power and Lossy Networks (LLNs), the IPv6 Routing Protocol for LLNs (RPL) was standardized by the IETF some six years ago to tackle the routing issue in such networks. Since its introduction, however, numerous studies have pointed out that, in its current form, RPL suffers from issues that limit its efficiency and domain of applicability. Thus, several solutions have been proposed in the literature in an attempt to overcome these identified limitations. In this survey, we aim mainly to provide a comprehensive review of these research proposals assessing whether such proposals have succeeded in overcoming the standard reported limitations related to its core operations. Although some of RPL’s weaknesses have been addressed successfully, the study found that the proposed solutions remain deficient in overcoming several others. Hence, the study investigates where such proposals still fall short, the challenges and pitfalls to avoid, thus would help researchers formulate a clear foundation for the development of further successful extensions in future allowing the protocol to be applied more widely.
Internet of Things technology has given rise to Smart Cities, Smart Health, Smart Transport Logistics, Smart Production and Supply chain management, Smart Home and the list is long. Smart city deployments are gaining momentum around the world. Security and Reliability of IoT infrastructure in smart cities remain important challenges. In this regard, ROLL-WG has standardised RPL for urban environment (RFC 5548). RPL is designed to address the needs of constrained IoT environment. RPL uses Objective Functions (ETX & Hop Count) to optimise parent selection as well as route selection. Newer Objective Functions for IoT applications are suggested by researchers to manage network and security. In this paper, we propose Multi DODAG's in RPL for improved performance and reliable smart city applications.We have tested the proposed model in Contiki OS with Cooja simulator. Proposed model provides improved efficiency in convergence time, Packet Delivery Ratio, Control Traffic Overhead, Power consumption. For reliability, node participation is evaluated. Hence, Multi DODAG's in RPLcan better optimize constrained resources and provide reliability to the network.
The IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) protocol stack is a key part of the Internet of Things (IoT) where the 6LoWPAN motes will account for the majority of the IoT `things'. In 6LoWPAN networks, heavy network traffic causes congestion which significantly affects the overall performance and the quality of service metrics. In this paper, a new analytical model of congestion for 6LoWPAN networks is proposed using Markov chain and queuing theory. The derived model calculates the buffer loss probability and the channel loss probability as well as the number of received packets at the final destination in the presence of congestion. Also, we calculate the actual wireless channel capacity of IEEE 802.15.4 with and without collisions based on Contiki OS implementation. The validation of the proposed model is performed with different scenarios through simulation by using Contiki OS and Cooja simulator. Simulation results show that the analytical modelling of congestion has an accurate agreement with simulation.
RPL is the IPv6 routing protocol for low-power and lossy networks (LLNs), standardized by IETF in 2012 as RFC6550. Specifically, RPL is designed to be a simple and inter-operable networking protocol for resource-constrained devices in industrial, home, and urban environments, intended to support the vision of the Internet of Things (IoT) with thousands of devices interconnected through multihop mesh networks. More than four-years have passed since the standardization of RPL, and we believe that it is time to examine and understand its current state. In this article, we review the history of research efforts in RPL; what aspects have been (and have not been) investigated and evaluated, how they have been studied, what was (and was not) implemented, and what remains for future investigation. We reviewed 97+ RPL-related academic research papers published by major academic publishers and present a topic-oriented survey for these research efforts. Our survey shows that only 40.2% of the papers evaluate RPL through experiments using implementations on real embedded devices, ContikiOS and TinyOS are the two most popular implementations (92.3%), and TelosB was the most frequently used hardware platform (69%) on testbeds that have average and median size of 49.4 and 30.5 nodes, respectively. Furthermore, unfortunately, despite it being approximately four years since its initial standardization, we are yet to see wide adoption of RPL as part of real-world systems and applications. We present our observations on the reasons behind this and suggest directions on which RPL should evolve.
RPL, the IPv6 Routing Protocol for low-power and lossy networks, is considered the de facto routing protocol for the Internet of Things (IoT). Since its standardization, RPL has contributed to the advancement of communications in the world of tiny, embedded networking devices by providing, along with other standards, a baseline architecture for IoT. Several years later, we analyze the extent to which RPL has lived up to the expectations defined by the IETF requirements, and tie our analysis to current trends, identifying the challenges RPL must face to remain on the forefront of IoT technology.
Low-power and lossy networks (LLNs) comprised of thousands of embedded networking devices can be used in a variety of applications, such as smart grid automated metering infrastructures (AMIs) and wireless sensor networks. Connecting these LLNs to the Internet has even greater potential, leading to the emerging concept of the Internet of Things (IoT). With the goal of integrating LLNs into IoT, the IETF has recently standardized RPL and 6LoWPAN to allow the use of IPv6 on LLNs. Although there already exist several studies on the the performance of RPL and embedded IPv6 stack in LLN, performance measurement and characterization of TCP over RPL in multihop LLNs is yet to be studied. In this article, we present a comprehensive experimental study on the performance of TCP over RPL in an embedded IPv6-based LLN running over a 30-node multihop IEEE 802.15.4 testbed network. Our results and findings are aimed at investigating how embedded TCP interoperates with common Linux TCP and underlying RPL (and vice versa), which furthers our understanding of the performance trade-offs when choosing TCP over RPL in IPv6-based LLNs.
Low-Power and Lossy Networks (LLNs) are a class of network in which
both the routers and their interconnect are constrained. LLN routers
typically operate with constraints on processing power, memory, and
energy (battery power). Their interconnects are characterized by
high loss rates, low data rates, and instability. LLNs are comprised
of anything from a few dozen to thousands of routers. Supported
traffic flows include point-to-point (between devices inside the
LLN), point-to-multipoint (from a central control point to a subset
of devices inside the LLN), and multipoint-to-point (from devices
inside the LLN towards a central control point). This document
specifies the IPv6 Routing Protocol for Low-Power and Lossy Networks
(RPL), which provides a mechanism whereby multipoint-to-point traffic
from devices inside the LLN towards a central control point as well
as point-to-multipoint traffic from the central control point to the
devices inside the LLN are supp
The Internet Engineering Task Force (IETF) has developed new protocol named as IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) for use in lossy environments to connect resource limited wireless nodes. RPL organize network as acyclic oriented graphs named DODAG and by doing this it provide transfer of messages from nodes to DODAG root through most reliable and fastest route. In this paper authors introduce main characteristics and review RPL protocol to be applied in wireless sensor networks.
Stochastic automata operating in an unknown random environment have been proposed earlier as models of learning. These automata update their action probabilities in accordance with the inputs received from the environment and can improve their own performance during operation. In this context they are referred to as learning automata. A survey of the available results in the area of learning automata has been attempted in this paper. Attention has been focused on the norms of behavior of learning automata, issues in the design of updating schemes, convergence of the action probabilities, and interaction of several automata. Utilization of learning automata in parameter optimization and hypothesis testing is discussed, and potential areas of application are suggested.
IEEE 802.15.4-2006 represents a widely used standard for multihop Wireless Sensor Networks. However, the standard exploits a tree structure in the MAC layer, which may lead to network partitions even after a single link or node failure, i.e. the well known single point of failure problem. Besides, the single path approach avoids the routing protocol to select by itself a next hop based on its own criteria. Moreover, transmissions must be appropriately scheduled in the IEEE 802.15.4 cluster-tree to avoid colli- sions. In this paper, we propose to modify the cluster-tree structure into a Cluster-Directed Acyclic Graph (DAG) to improve the robustness and the topology redundancy at the MAC layer. We also present a simple greedy scheduling algorithm integrated with the IEEE 802.15.4 MAC mechanisms. Simulations show that the proposed mechanisms optimize the MAC layer for multihop topologies. In particular, the routing proto- col (e.g. RPL) is able to exploit efficiently the cluster-DAG and to reduce the number of packet losses and the end-to-end delay. Last but not least, the cluster-DAG structure leads globally to energy savings by reducing the number of retransmissions at the MAC layer.
We have witnessed the Fixed Internet emerging with virtually every computer being connected today; we are currently witnessing the emergence of the Mobile Internet with the exponential explosion of smart phones, tablets and net-books. However, both will be dwarfed by the anticipated emergence of the Internet of Things (IoT), in which everyday objects are able to connect to the Internet, tweet or be queried. Whilst the impact onto economies and societies around the world is undisputed, the technologies facilitating such a ubiquitous connectivity have struggled so far and only recently commenced to take shape. To this end, this paper introduces in a timely manner and for the first time the wireless communications stack the industry believes to meet the important criteria of power-efficiency, reliability and Internet connectivity. Industrial applications have been the early adopters of this stack, which has become the de-facto standard, thereby bootstrapping early IoT developments with already thousands of wireless nodes deployed. Corroborated throughout this paper and by emerging industry alliances, we believe that a standardized approach, using latest developments in the IEEE 802.15.4 and IETF working groups, is the only way forward. We introduce and relate key embodiments of the power-efficient IEEE 802.15.4-2006 PHY layer, the power-saving and reliable IEEE 802.15.4e MAC layer, the IETF 6LoWPAN adaptation layer enabling universal Internet connectivity, the IETF ROLL routing protocol enabling availability, and finally the IETF CoAP enabling seamless transport and support of Internet applications. The protocol stack proposed in the present work converges towards the standardized notations of the ISO/OSI and TCP/IP stacks. What thus seemed impossible some years back, i.e., building a clearly defined, standards-compliant and Internet-compliant stack given the extreme restrictions of IoT networks, is commencing to become reality.
The assumption of TCP-based protocols that packet error (lost or damaged) is due to network congestion is not true for wireless networks. For wireless networks, it is important to reduce the number of retransmissions to improve the effectiveness of TCP-based protocols. In this paper, we consider improvement at the data link layer for systems that use stop-and-wait ARQ as in IEEE 802.11 standard. We show that increasing the buffer size will not solve the actual problem and moreover it is likely to degrade the quality of delivery (QoD). We firstly study a wireless router system model with a sequential convolutional decoder for error detection and correction in order to investigate QoD of flow and error control. To overcome the problems along with high packet error rate, we propose a wireless router system with parallel sequential decoders. We simulate our systems and provide performance in terms of average buffer occupancy, blocking probability, probability of decoding failure, system throughput, and channel throughput. We have studied these performance metrics for different channel conditions, packet arrival rates, decoding time-out limits, system capacities, and the number of sequential decoders. Our results show that parallel sequential decoders have great impact on the system performance and increase QoD significantly.
Internet of Things technology has given rise to Smart Cities, Smart Health, Smart Transport Logistics, Smart Production and Supply chain management, Smart Home and the list is long. Smart city deployments are gaining momentum around the world. Security and Reliability of IoT infrastructure in smart cities remain important challenges. In this regard, ROLL-WG has standardised RPL for urban environment (RFC 5548). RPL is designed to address the needs of constrained IoT environment. RPL uses Objective Functions (ETX & Hop Count) to optimise parent selection as well as route selection. Newer Objective Functions for IoT applications are suggested by researchers to manage network and security. In this paper, we propose Multi DODAG’s in RPL for improved performance and reliable smart city applications.We have tested the proposed model in Contiki OS with Cooja simulator. Proposed model provides improved efficiency in convergence time, Packet Delivery Ratio, Control Traffic Overhead, Power consumption. For reliability, node participation is evaluated. Hence, Multi DODAG’s in RPLcan better optimize constrained resources and provide reliability to the network.
The routing protocol RPL for low power and lossy networks (LLNs) suffers from reduced reliability, increase in control overhead, longer latency and higher energy utilization on experiencing high node density, link or node failures in the network. This paper aims to elaborately study the behaviour of RPL’s expected transmissions count (ETX) based path selection for lengthier routes and the impact of node density and link or node failures on them. Our study finds that the path selection along long routes suffers due to the lack of decisive information on the neighbourhood links. As an alternate, a laplacian energy based path selection is proposed to enrich RPL by bringing in additional neighbourhood connection information into the path selection process to provide stable paths. Laplacian energy drop, a two-walk neighbourhood connectivity measure that is incorporated in L-RPL helps a node to pick the most resilient path. By simulation and testbed experiment results, it is shown that the proposed L-RPL improves path selection and reduces control overhead (29.05% and 39.68% reduction in (Destination Advertisement Object) control data when 9% of nodes fail and during normal conditions respectively), latency and also improves energy utilization.
Internet of Mobile Things (IoMT) is a new paradigm of the Internet of Things (IoT) where devices are inherently mobile. While mobility enables innovative applications and allows new services, it remains a challenging issue as it causes disconnection of nodes and intermittent connectivity, which negatively impacts the network operation and performance. In addition, energy saving presents a real challenge for networks with limited resources. In this context, a new energy e�cient and mobility aware routing protocol called EMA-RPL is proposed based on the well-known Routing Protocol for Low power and Lossy Networks (the RPL standard).
Unlike the RPL which is basically designed for static devices, EMA-RPL enables better sustaining of connectivity of mobile nodes and conserving energy. The proposed protocol integrates an enhanced mobility detection method through a continuous control of the distance between the mobile node and its attachment, a novel point of attachment prediction based on the new location of the mobile node, and an e�cient replacement strategy preserving the mobile node energy. EMA-RPL overcomes and mitigates problems caused by the mobility of nodes. Simulations using Cooja/Contiki show that EMA-RPL outperforms both the RPL and its mobility aware variant (MRPL) in terms of handover delay, data loss rate, signaling cost and energy consumption.
Devices connected to the internet are increasing day a day, the era of Internet of Things (IoT) is coming. However, handling big data generated by the IoT networks will present considerable challenge for the decision makers. Wireless sensor networks (WSNs) is one of the big data source in IoT. In such networks, a wide range of areas are monitored by thousands of sensors where gathered data are sent to the sink node. Unfortunately, WSNs impose many challenges compared to other types of networks. Data management is a mainly challenging task for WSNs due to the huge amounts of data collected in such networks. To the best of our knowledge, this paper represents the first formal overview about big data management in WSNs. We highlight and categorize, based on some performance measures, different algorithms designed for data collection, aggregation, correlation, compression and prediction in such networks. Furthermore, we give a review about most important WSN applications. Finally, open research issues of WSNs are also suggested and put forward in this paper.
Wireless sensor networks (WSNs) are widely applied in various industrial applications. In this paper, we present an efficient data gathering scheme that guarantees the Quality of Service and optimizes the following network performance metrics as well as the end-to-end reliability in WSNs: 1) minimum total energy consumption; 2) minimum unit data transmitting energy consumption; and 3) maximum utilization efficiency defined as network lifetime per unit deployment. We first transform the performance optimization problem into a problem to optimize the following parameters: 1) deployed nodal number ; 2) nodal placement ; and 3) nodal transmission structure . Then, we prove that the optimization problem is solvable mathematically. For our observation, the sensor nodes close to the sink trend failed early since they consumed more energy with heavier relay traffic destined for the sink, which seriously affects the network performance. The key point of this optimization is adopting lower reliability requirements and shorter transmission distance for nodes near the sink. Consequently, this reduces the energy consumption of the nodes in the hotspot area. Meanwhile, it adopts higher reliability requirements and farther transmission distance for nodes far from the sink to make full use of the node residual energy, so as to optimize the network performance without harming network reliability. Numerical simulation results demonstrate that our optimal approach improves the network lifetime by 18%–48% and network utility by 17%, and guarantees desire reliability level.
IEEE 802.22 wireless regional area network (WRAN) is a cognitive radio-based network. WRANs are intended to be deployed by
different service providers and designed to opportunistically utilize the unused TV bands. WRANs have to self-coexist with
other overlapped WRANs in a distributed manner. Therefore, every service provider tries to acquire a band free of interference
from others to satisfy a required quality of service. This self-coexistence problem is one of the major challenges in WRAN. In this paper, we propose a Markov-based distributed approach for mitigating this
problem. We model the problem as an absorbing discrete-time Markov chain. In this model, if two or more overlapped WRANs select
the same band, then each one should either stay or switch to another band according to a certain switching probability. This
process continues until each one of the WRANs finds an interference-free band. In this case, the Markov chain reaches the
absorbing state. This model is employed to find the optimal switching probability, which in turn minimizes the time required
to reach the absorbing state. The switching probability is numerically found as a function of the number of overlapped WRANs
and available bands. Extensive simulation has been conducted to validate our numerical results.
The wide deployment of lower-cost wireless devices will significantly improve the productivity and safety of industrial plants while increasing the efficiency of plant workers by extending the information set available about the plant operations. The aim of this document is to analyze the functional requirements for a routing protocol used in industrial Low-power and Lossy Networks (LLNs) of field devices.
The convolutional coding is a very popular channel coding technique for the major reason of mitigating the probability of having many retransmissions because of difficult (noisy) communication channels. Sequential decoding is a type of convolutional codes that becomes of interest in wireless communication since it affords a decoding time that can be adaptive to channel state. In this study, the authors propose an improved queuing model, using discrete-time semi-Markov chain, which represents a modified packet retransmission policy over previously proposed queuing model. The authors queuing model mainly describes the behaviour of the buffer, which belongs to intermediate hops, when sequential decoding is implemented and concerns also about packets being transmitted over erroneous channels. The authors aim after conducting queuing analysis to find a real mathematical form for the average buffer occupancy as a network performance metric. Although the improved queuing model when incorporating the new policy for retransmission is very complicated, we are finally able to derive an expression for that performance metric considering practical assumptions. They further illustrate how the modified queuing model has a better impact on the end-to-end delay of messages, being transmitted without any extra buffering requirements needed, than the other relevant proposed queuing model. They conduct a simulation study using computer programming with the same assumptions used for queuing analysis to validate their analytical explanations and results. Furthermore, they validate the correctness of their closed-form expression through comparing its results with those obtained from expression related to a queuing model which discarded employing any retransmission policy.
In IEEE 802.15.4/ZigBee Wireless Sensor Networks (WSNs) a specific node (called the PAN coordinator or sink) controls the whole network. When the network operates in a multi-hop fashion, the position of the PAN coordinator has a significant impact on the performance: it strongly affects network energy consumption for both topology formation and data routing. The development of efficient self-managing, self-configuring and self-regulating protocols for the election of the node that coordinates and manages the IEEE 802.15.4/ZigBee WSN is still an open research issue. In this paper we present a cross-layer approach to address the problem of PAN coordinator election on topologies formed in accordance with the IEEE 802.15.4. Our solution combines the network formation procedure defined at the MAC layer by the IEEE 802.15.4 standard with a topology reconfiguration algorithm operating at the network layer. We propose a standard-compliant procedure (named PAN coordinator ELection – PANEL) to self-configure a IEEE 802.15.4/ZigBee WSN by electing, in a distributed way, a suitable PAN coordinator. A protocol implementing this solution in IEEE 802.15.4 is also provided. Performance results show that our cross-layer approach minimizes the average number of hops between the nodes of the network and the PAN coordinator allowing to reduce the data transfer delay and determining significant energy savings compared with the performance of the IEEE 802.15.4 standard.
IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) is a routing protocol specifically designed for Low power and Lossy Networks (LLN) compliant with the 6LoWPAN protocol. It currently shows up as an RFC proposed by the IETF ROLL working group. However, RPL has gained a lot of maturity and is attracting increasing interest in the research community. The absence of surveys about RPL motivates us to write this paper, with the objective to provide a quick introduction to RPL. In addition, we present the most relevant research efforts made around RPL routing protocol that pertain to its performance evaluation, implementation, experimentation, deployment and improvement. We also present an experimental performance evaluation of RPL for different network settings to understand the impact of the protocol attributes on the network behavior, namely in terms of convergence time, energy, packet loss and packet delay. Finally, we point out open research challenges on the RPL design. We believe that this survey will pave the way for interested researchers to understand its behavior and contributes for further relevant research works.
The demand for maximum network lifetime in many mission-critical applications of wireless sensor networks motivates the great significance to deploy as few sensors as possible to achieve the expected network performance. In this paper, we first characterize the energy consumption of wireless sensor networks with adjustable transmission ranges through theoretical analysis. Based on this result, we propose a deployment strategy with T as the required minimum network lifetime. We come up with three interventions: (A) in order to achieve an evenly balanced energy consumption among all nodes, the node density in different areas of the network should be a continuous varying function of the distance from the sink; (B) if there are insufficient nodes to achieve a balanced energy consumption over the whole network, our proposed node deployment strategy can be used to achieve the required lifetime threshold T with minimum number of nodes; and (C) when there are sufficient nodes to ensure the network connectivity and coverage with the node density of τ, we design an algorithm to identify the optimal transmission radius r and the corresponding achievable maximum network lifetime. Our conclusions are verified by extensive simulation results.
Sequential decoders are convolutional channel decoders that are characterized by having variable decoding complexity in changing channel conditions. They are widely used in wireless packet-switching networks and mobile communications. The major difference of multimedia networks from traditional networks is the deadline to display or (play) the arriving packets. Especially, this is more obvious in real- time video streaming applications. Real-time video streaming applications prefer User Datagram Protocol (UDP) for video packet transfers. The operation of sequential decoding in this paper is applied on wireless multimedia networks. Buffers are usually required by the sequential decoder to store packets if there is an empty space. Geometric/Pareto/1/N queue model is used to describe the behavior of the sequential decoders with finite buffers. In this paper, we present an analytical study on the finite buffer behaviors of the sequential decoding system and provide closed form expression for the blocking probability due to limited buffer capacity, system throughput, and average buffer occupancy. We present also a simulation study to show the average buffer occupancy. KEYWORDS—Sequential decoder, average buffer occupancy, queuing analysis, blocking probability, system throughput.
MARPL: A crosslayer approach for Internet of things based
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OF-ECF: A New Optimization of the Objective
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The Trickle Algorithm
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Routing requirements for urban low-power and lossy networks
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REFER: A Reliable and Energy-Efficient RPL for Mobile IoT Applications
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