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Wireless sensor networks (WSNs) and Internet of Things (IoT) are essential for numerous applications. WSN nodes often operate on limited battery capacity, so energy efficiency is a significant problem for clustering and routing. In addition to these limitations, one of the primary issues of WSNs is achieving reliability and security of transmitted data in vulnerable environments to prevent malicious node attacks. This work aims to develop a secure and energy-efficient routing protocol for fault data prediction to enhance WSNs network lifespan and data reliability. The proposed technique has three major phases: cluster construction, optimal route selection, and intrusion detection. The adaptive shark smell optimization (ASSO) technique was initially used with three input parameters for CH selection. These parameters are the residual energy, the distance to the BS, and the node density. After clustering, salp swarm optimization (SSO) is used to select the optimum path for data transmission between clusters, resulting in an energy-efficient WSN. Finally, to ensure the security of cluster-based WSNs, an effective intrusion detection system based on a modified Elman recurrent neural network (MERNN) is implemented to detect the presence of intrusions in the network. The experimental results show that it outperforms the competing methods in various performance metrics. The performance results of quality of service (QoS) parameters are expressed as dispersion value (0.8072), packet delivery rate (98%), average delay (160 ms), network lifetime (3200 rounds), and the accuracy of this method is 99.2%. Compared to the SVM, ELM, HMM, and MK-ELM protocols, the proposed protocol increases network lifetime by 77%, 60%, 45.4%, and 14.2%, respectively. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) in tourism refers to the use of interconnected devices and systems to enhance the travel experience for tourists. IoT applications in the tourism industry include using and promoting new wireless communication mediums, which will have a significant impact on this business. Wireless network sensors (WSNs) significantly influence the future of communication because they offer a new channel for communication among linked tourist machinery and equipment. The effective routing method of sensor nodes can be helpful for the application of wireless sensors and IoT in eco-cultural tourism. The routing approach of sensor nodes is crucial to the entire network's performance. Routing protocols select several intermediary nodes between the source nodes and the destination nodes to build an effective data transmission path by enhancing WSN's performance in eco-cultural tourism. This study use the Dynamic Host Configuration Protocol (DHCP) and the conventional Minimum Maximum Battery Cost Routing (MMBCR) protocol to lower the network's energy consumption and packet loss rate. According to the experimental findings, the DHCP protocol's network latency was 0.01 s, and the MMBCR protocol's network delay was 0.05 s, when there were 30 nodes in the network. Similarly, the MMBCR protocol's network latency was 0.17 s, and the DHCP protocol's network delay was 0.07 s when there were 150 nodes. The DHCP protocol's network delay increased but did not change abruptly, but the delay of the MMBCR protocol increased constantly and quicker based on the experimental outcomes. It demonstrates how the DHCP protocol is more flexible to data rate increases and more suited to enhancing the speed of sensor nodes as a new medium for communication. [ABSTRACT FROM AUTHOR]

The Internet of Things in 5G and next-generation data communication networks have relied heavily on Wireless Sensor Networks (WSNs). Data aggregation, Energy consumption, bandwidth utilization, and dynamic traffic routing play a significant role and impose challenges in achieving QoS in a sensor network. Therefore, it is crucial to concentrate on these factors in order to increase the network's lifetime and quality of service. The research's goal is to analyse IoT WSNs in terms of their architecture, framework, security, data aggregation, and routing techniques. In IoT WSNs, the data aggregation technique reduces the energy consumption of the network's nodes. This improves the network's energy and other QoS parameter's efficiency. The network layer hybrid data aggregation and routing protocol proposed in this study is new and efficient. In this work, a novel method for data aggregation based on anchor-based routing and matrix filling theory is proposed. It is suggested to use improved Anchor-based Routing protocol for Event Reporting (ARER), an anchor-based routing technique that includes dynamic clustering and constrained flooding. In order to achieve QoS in IoT WSN, the proposed hybrid network layer protocol has outperformed. The proposed protocol has performed better in terms of QoS metrics like throughput, end-to-end delay, routing overhead, packet delivery ratio, and energy consumption. [ABSTRACT FROM AUTHOR]

With the dense deployment of basic service set (BSS) in the next generation Wireless Local Access Network (WLAN). The overlapping coverage of multiple BSSs leads to intensified contention conflicts, low efficiency of buffer state reports (BSR) collection and a sharp decline in system throughput. To solve this problem, this paper proposes an access point (AP) cooperation based multi-BSS multi-user full duplex multiple access protocol (CMMFD). Firstly, access control (AC) divides the STAs in the cooperative network area into overlapping STA and non-overlapping STA. A bi-level channel resource allocation algorithm is designed. The first level is channel resource allocation in the collection stage of BSR and inter-node interference information (BI), and the second level is channel resource allocation in full duplex data transmission. Secondly, a protocol framework for parallel BI information collection of cooperative APs is designed. AC schedules cooperative APs to send trigger frame at the same time, and triggers STAs in each BSS to report BI information on the assigned channel resource with p -probability access mode. Finally, AP forwards the collected BI information to AC, and AC assigns the STAs in the multi-BSS to perform multi-user full-duplex transmission on the resource unit (RU). Theoretical analysis gives the closed form expressions of the mean number of STAs successfully collected by AC in the cooperation area and saturated network throughput. Simulation results show that compared with MU-FuPlex and EnFD-OMAX protocol, CMMFD protocol improves the network throughput by 29.6% and 31.2% respectively. [ABSTRACT FROM AUTHOR]

In Wireless Sensor Network (WSN), the consumption of energy is high due to the data transmission in the sensing region. The Optimized Distributed Voronoi-based Collaboration (ODVOC) optimizes data delivery and it suffers from huge energy consumption. To overcome this drawback, a data aggregation scheme is introduced to expand the lifetime of the network and to minimize the energy utilization. Data aggregation is a significant approach that preserves the unwanted usage of energy during data transmission. In this paper, the Optimized Distributed Voronoi-based Cooperation scheme with Energy-aware Dual-path Geographic Routing (DAOHS-ODVOC-EDGR) is proposed which incorporates the polydisperse aggregation scheme and it aggregates the indispensable data in the intermediary nodes. The effective data aggregation is achieved by the estimation of the waiting time of the data at every intermediary node and cost function that is used for electing the next-hop node. In the proposed protocol, the buffer value of every node is divided to retain diversified kinds of flow for effective and fair delivery of data. The rate of transmission at the source and intermediary node is altered during the congestion. The proposed DAOHS- ODVOC-EDGR protocol is tested via simulation scheme. The result of the simulation exposes that DAOHS-ODVOC-EDGR outperforms the TESDA and DVOC protocol in terms of network lifetime, energy efficiency, and hop count delay. [ABSTRACT FROM AUTHOR]

Upgraded network technology presents an advanced technological platform for telecare medicine information systems (TMIS) for patients. However, TMIS generally suffers various attacks since the information being shared through the insecure channel. Recently, many authentication techniques have been proposed relying on the chaotic map. However, many of these designs are not secure against the known attacks. In spite of the fact that some of the constructions attain low computation overhead, they cannot establish an anonymous communication and many of them fail to ensure forward secrecy. In this work, our aim is to present authentication and key agreement protocol for TMIS utilizing a chaotic map to achieve both security and efficiency. The underlying security assumptions are chaotic theory assumptions. This scheme supports forward secrecy and a secure session is established with just two messages of exchange. Moreover, we present a comparative analysis of related authentication techniques. [ABSTRACT FROM AUTHOR]

The wireless sensor networks (WSN) research is emerging fast in the areas of agriculture, industry, smart grid communication, smart monitoring, and smart metering. The Zigbee is a wireless network protocol under IEEE 802.15.4 standard, that provides low cost, low power, and lesser delay in data communication over a PAN network. Several sensor nodes are deployed in WSN geospatial domain to communicate with each other. The sensor nodes are the embedded devices used to perform specific applications by sending information in the network through the coordinator node. The coordinator gathers the data, stores into memory, processes it, and route it to the destination node. The Zigbee protocol supports peer-to-peer, star, mesh and cluster tree topology. In the research paper, the hardware chip design for mesh, star, and cluster Zigbee topology is proposed in which 64 nodes are communicating with each other. The chip simulation is performed on Xilinx ISE 14.7 software for 64-bit internode communication and pre-synthesized on Virtex-5 FPGA. The comparative performance of the chip is analyzed with the help of the FPGA device and timing parameters. [ABSTRACT FROM AUTHOR]

Multi-channel ad hoc networks are promising technology to alleviate the spectrum scarcity in dense networks. The main challenge for channel access in distributed multi-channel ad hoc networks is channel synchronization and competition with neither common control channel nor dedicated control transceiver. In this paper, a Tight Synchronized MAC protocol with distributed synchronization and competition process without any dedicated control channel is proposed. The protocol uses a simple handshaking mechanism to create a channel table for each node, which contains its neighbors and channels' status. By this, any node knows the priority of its channels and also the priority of neighbors' channels. By assigning priorities, a sender node starts synchronization. If sender and receiver nodes have a common channel, the proposed method finds it directly or indirectly using the common neighbor mechanism. The other feature of the proposed scheme is using a fair preemptive data transmission phase, which reduces the number of switchings along data transmission. The fair preemptive mechanism is achieved by an analytical solution to estimate the number of competing nodes and thus, estimates the number of assigned data slots. Simulation results show the performance improvements in terms of synchronization delay and packet delivery ratio over HMMAC and MSRMMAC protocols. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) plays a prominent role in health-care of patients, which assist the physicians and patients through the assistance in effective decision-making and additionally, in the medical field, IoT plays a significant role in real-time monitoring of the patients. Even though the data provided by the IoT devices ensure the effective decision-making, the data is susceptible to the network attacks. Thus, the paper proposes an authentication protocol for enabling the secure data transmission in IoT based on three functions, such as encryption function, hashing function, and adaptive XOR function. The proposed authentication protocol is named as, Adaptive XOR, hashing and Encryption Key Exchange (AXHE) protocol, which is the combination of the functions, such as encryption function, hashing function, and adaptive XOR function. The protocol ensures the security in the communication through two successive phases, such as registration and authentication of the user, where the user name, password, public keys, private keys, and security factor are employed. The authentication is progressed as seven levels and whenever the security factor matches, the user is authenticated and the communication continues. The analysis of the proposed AXHE is performed using 50 and 100 nodes in the presence of DOS and black hole attacks, which acquires the detection rate, throughput, and detection delay of 0.3859, 0.32, and 6.535 s, respectively. [ABSTRACT FROM AUTHOR]

In recent years, vehicle networks require high bandwidth due to the increasing complexity of electronic control devices for vehicles due to the demand for advanced driving aids, infotainment and V2X communication. Therefore, Ethernet protocol was introduced and vehicle gateway system was newly introduced in vehicle system. The vehicle gateway system provides an interface for continuously connecting and exchanging vehicle data in different communication environments between the Controller Area Network (CAN) protocol and the Ethernet network protocol. There are two types of data exchange in the vehicle gateway. These are direct routing and indirect routing. Vehicle gateways are connected to external networks, which can lead to security vulnerabilities. So it needs security function to ensure message integrity. Recently, vehicle manufacturers have introduced gateway systems with security features that operate to verify the integrity of messages using cipher-based message authentication codes (CMAC). But applying security functions to a gateway system introduces delays in performing security functions. Therefore, in this paper, to design stable and efficient the vehicle gateway system with security function, we have tested and evaluated the latency time that can occur according to the routing methods which are direct routing and indirect routing. [ABSTRACT FROM AUTHOR]

Domain knowledge: Today, Wireless Sensor Network (WSN) is widely used for general purposes. With the propagation of the Internet of Things (IoT), security issues arise wherever the healthcare devices are used exclusively for data transfer protocols. These network protocols are easily susceptible to attack. Although it is problematic to save sensing information from the body sensors, the loss of signal messages will often occur in an IoT environment. Thus security is a supreme requirement in health care applications, especially in the case of patient privacy. Methodology: In this paper, an IoT health care communication system is designed to implement the integration using CoAP based Secure-aware Mobility Management Protocol (CoSMP) in Wireless Body Area Network (WBAN) based IoT environment. The proposed protocol is extremely effective to secure the sensing information of the device node wherever they are moving and additionally, it is accustomed to offer secure data transmission between the node and web client. Our protocol establishes a pairwise key between the networks according to an exact algorithm, namely Advanced Encryption Standard Cipher Feedback Message Authentication Code (AES-CFMAC) algorithm, and handover operation could be authenticated by Elliptic Curve Digital Signature Algorithm (ECDSA). Numerical analysis and performance result imposes the proposed scheme is simulated in terms of network delay and handover delay. Result: Experimental results depict that the proposed protocol has been compared with the previous protocol in terms of security and mobility management. Hence, the numerical result would be evaluated based on the measures of Total Transmission Delay (TTD) on the variation of wireless link delay, sensor node delay, link failure probability delay, hop count between the gateway and WMMS in the network delay with the low delay of 303.55, 1.6, 700 and 80 in ms respectively and also performance measures of Handover Delay (HD) achieves 1212.5, 1.212, 49.46 and 1453.8 in ms respectively. The percentage in terms of using performance measures of TTD and HD is compared between proposed and existing schemes resulted in (COMP = 0.3632%, COMP-G = 0.2712 % and COSMP = 0.2532%) and (COMP = 0.3188%, COMP-G = 0.2421 % and COSMP = 0.2133%) respectively. [ABSTRACT FROM AUTHOR]

Wireless sensor network comprises several small nodes distributed randomly in an area under observation. These nodes sense the assigned physical phenomenon occurring around it and reports back to the base station. WSN is increasingly applied in defense, industrial, health care applications etc. Some applications envisage movement of the nodes. This results in frequent alteration of network topology leading to dynamic network partitioning. Hence, the routing of data from source to sink faces more routing disruptions. Maintaining application specific quality of service (QoS) in terms of Packet delivery ratio in such Mobile wireless sensor network (MWSN) environment is a daunting task. This cannot be achieved by focusing on a solution in only a single layer of sensor network protocol stack. Instead, by incorporating different techniques in each layered OSI protocol stack, a single coherent framework is proposed in this paper. This paper proposes prediction based coding in application layer, opportunistic routing in network layer, Laplacian scaling based on round trip time measurement in session layer. The proposed cross layer solution ensures application specific QoS guaranteed fault tolerance in MWSN. [ABSTRACT FROM AUTHOR]

The utilization of wireless sensor networks (WSNs) is proliferating in our daily life. It depends on the environmental monitoring such as weather tracking, battled field, etc. However, the main challenge of WSNs is energy management. Generally, traditional nodes of the sensor network were powered by non-rechargeable batteries with limited energy capacity. The alternative solution has been discovered to resolve the limitation of the sensor battery called energy harvesting (EH). EH offers effective and an alternative solution to recharge the battery of the sensor node. It assists with the environment, and EH technique can be possible different kinds such as solar, wind, thermal and mechanical. In this paper, we propose a novel energy harvesting clustering protocol (NEHCP). The NEHCP is based on the hierarchical clustering routing algorithm, and this protocol uses solar EH. The collection of information from the sensor nodes is sent to the base station through the cluster head. The NEHCP algorithm is categorized into three sections, such as the initial phase, set-up phase and data transmission phase. Moreover, the unique feature of EH-WSNs is giving more efficient result in term of network lifetime. The simulation part of this method shows a strong ability to balance energy consumption and increases the network efficiency for the EH-WSNs. [ABSTRACT FROM AUTHOR]

Efficient energy consumption is a major problem in Wireless Sensor Network. The sink can be static or dynamic. In case of static sink, the node that is placed near the sink is utilized more than other nodes in the network due to frequent packet forwarding. This causes the node near the sink to die very soon, also further communication between the sink and other nodes in the network is disconnected. When dynamic or mobile sinks are used, the energy consumption is distributed among other nodes in the network, which increases the lifetime of the network. In this paper to know the latest position of the sink, we introduce Dynamic Hexagonal Grid Routing Protocol (DHGRP). In the first phase, the protocol divides the network by several hexagonal virtual grids to share the current position of the sink among the nodes. In the second phase, the dynamic path is selected, in case congestion occurs during data transmission or if the mobile sink is moved to a new location. The performance is evaluated by comparing with the existing ring routing protocol, Query-Driven Virtual Grid-based Data Dissemination, and Grid-Cycle Routing Protocol. The results show that the proposed DHGRP protocol has better performance in terms of energy consumption, delay, network lifetime, throughput and Packet Delivery Ratio. [ABSTRACT FROM AUTHOR]

Networks consisting of wireless sensors are extensively used in many applications. Decentralized Erasure Codes (DEC) were introduced to store the sensed data in the wireless sensor network itself before transmitting the sensed data from wireless nodes to gateway or query nodes. Data at the failed nodes can be reconstructed by accessing other nodes in the network in DEC setup. In a traditional DEC setup, it is required to access k nodes out of n nodes to reconstruct the data at the failed node. Also, the reconstruction at failed node is subjected to intruder attacks raising security concerns. To reduce the number of nodes required to reconstruct the data at failed nodes and to ensure communication security, in this paper, decentralized erasure codes were constructed from optimal locally recoverable codes and Blom's key pre-distribution protocol, which exploits the generator matrix nature of constructed code, was implemented. From the simulations, we can infer that the proposed scheme performs better than other existing methods that use Reed–Solomon codes in terms of network load and error count per sent packet. Furthermore, it is shown that the proposed scheme ensures secure and efficient communication between nodes to overcome intruder interference. [ABSTRACT FROM AUTHOR]

As the VoIP steganographic methods provide a low capacity covert channel for data transmission, an efficient and real-time data transmission protocol over this channel is required which provides reliability with minimum bandwidth usage. This paper proposes a micro-protocol for data embedding over covert storage channels or covert hybrid channels developed by steganographic methods where real-time transport protocol (RTP) is their underlying protocol. This micro-protocol applies an improved Go-Back-N mechanism which exploits some RTP header fields and error correction codes to retain maximum covert channel capacity while providing reliability. The bandwidth usage and the performance of the proposed micro-protocol are analyzed. The analyses indicate that the performance depends on the network conditions, the underlying steganographic method, the error correction code and the adjustable parameters of the micro-protocol. Therefore, a genetic algorithm is devised to obtain the optimal values of the adjustable micro-protocol parameters. The impact of network conditions, the underlying steganographic method and the error correction code on the performance are assessed through simulations. The performance of this micro-protocol is compared to an existing method named ReLACK where this micro-protocol outperforms its counterpart. [ABSTRACT FROM AUTHOR]

Besides sensing, computation, and communication of sensed data, the nodes near the base station have an additional responsibility to forward the data from far away nodes, leading to higher energy consumption around the base station. A solution to this bottleneck is to provide additional energy to such nodes, forming heterogeneous networks. Further stochastic cluster head selection leads to asymmetric energy dissipation among the nodes. This paper presents a fuzzy inspired energy-efficient protocol for a heterogeneous wireless sensor network with three types of nodes to compute feasibility of nodes to be assigned as cluster heads based on the residual energy of the node, its proximity to the base station, concentration and centrality. Most feasible nodes are assigned as cluster heads, followed by clustering and data transmission. The paper also mathematically derives optimal heterogeneity parameters to identify the number of nodes of a particular type along with the amount of energy to a particular node type. Further, the tradeoff between network timeline and percentage area covered too has been analyzed. The current work has been compared with recent protocols and the simulation outcomes show that FIEPE fairly justifies the network timeline requirement along with maximum percentage area coverage. [ABSTRACT FROM AUTHOR]

Secure data communication is the need of hour today specifically when the wireless communication channel is insecure. We are proposing a protocol which can be customized in variety of situations. We want to use steganography as a complementary tool for cryptography. The protocol utilizes the nature of communication protocol and it is even useful for places where data hiding and cryptography is illegal or can't be performed because of various reasons. We are giving a name to these kinds of networks as disturbed networks. The proposed peer to peer protocol is very useful for insecure channels and disturbed networks and we provide complete analysis to validate its utility. The method is a convenient stop and wait protocol which provides unbeatable security and suitable for mobile phones as well. At the same time, for intruder's perspective, there is no encryption involved which is a very important aspect. [ABSTRACT FROM AUTHOR]

A major issue in VANETs is the high mobility of the nodes. Broadcasting helps in improving the performance of the VANETs in terms of secure routing. However, broadcasting is a major overhead in VANETs. Broadcasting is still a widely used technique in wireless ad hoc networks and is mainly used to transmit network control information and application oriented data. The Optimized Link State Routing Protocol (OLSR) uses a multipoint relay scheme (MPR) to flood the network with control messages involving topology and other technical data. The method generally adopted is flooding which sometimes may lead to congestion in the network. The OLSR technique also has the capability of reducing retransmissions that are redundant and obsolete. We have proposed a MPR selection technique for a robust broadcast in VANETs. Our proposed method tries to cover all the 2-hop MPR nodes 'm' times. It also considers the weaker 2-hop MPR nodes set and compensates by providing an alternate solution to counteract the same. In fact, the proposed method determines the strength of the 2-hop MPR set before the start of the transmission and also tries to control the flooding of the transmission control messages. The proposed method is capable of recovering faster when there are broken communication links using the concept of friend MPR nodes. This is made possible with the help of the control packets which carry information regarding the RMPR and the Friend MPR nodes. The RMPR nodes are analyzed using a network simulator (NS2) and mathematical modeling. The values were obtained from the graph readings that were supplied to the simulator. The performance analysis has been tabulated in the results and discussion section. We have studied the performance of the proposed RMPR–OLSR protocol with the existing MMPR–OLSR and the OLSR protocols. The protocols were assessed by studying the network performance when the number of nodes was increased. It was assessed based on the nature of the traffic within the network. The delay for the proposed RMPR–OSLR was lesser than the other two methods (even with an increase in the number of nodes). Similarly, the packet drop for RMPR–OLSR was lesser than MMPR–OLSR and OLSR. The throughput of the RMPR–OLSR was found to increase by than the other existing protocols. The channel utilization was found to be more improved than the other protocols. In fact, the packet delivery ratio (PDR) of the proposed protocol was more than the other two protocols. Thus, the proposed protocol is capable of improving the overall throughput of the network and also helps in maximizing the PDR with respect to the MPR selection technique employed by OLSR. [ABSTRACT FROM AUTHOR]

As one of the most important convergence layer (CL) protocol for delay/disruption-tolerant networking (DTN), Licklider transmission protocol (LTP) is designed for deep space communications, but it has rarely been considered for near earth applications. In this paper, LTP is proposed instead of TCP as CL with Bundle protocol (BP) for future application in GEO-relayed space networks (GRSN). Analytical models are built to estimate the file delivery time of LTP in GRSN. Experiments are also conducted on our computer based testbed in emulation of the basic scenarios during data transmission from LEO satellite to a ground station in GRSN. The results show that in transmission efficiency BP with LTPCL outperforms other protocols, such as BP with TCPCL, direct terrestrial TCP (TCP Cubic) and TCP variants (TCP Hybla) for space segments in most scenarios. It could be envisioned that DTN with LTPCL for space segment is currently the best choice for future GEO-relayed space internetworking. Moreover, performance of two different networking schemes,i.e. the on-board DTN routers and the bent-pipe relays are compared. It is observed that bent-pipe relays outperform the on-board DTN routers scheme when the channel condition is good, while the on-board DTN routers scheme performs better with high data loss ratio. [ABSTRACT FROM AUTHOR]

Wireless sensor network is an emerging technology capable of having low-cost and low-power and battery-powered sensor node. At this point the protocol concentric clustered power-efficient gathering in sensor information systems and clustered general self organized tree based energy-balance routing protocol energy efficient protocol are used to increase the energy and to extend network lifetime. For these achievement of clustering techniques, optimization technique particle swarm optimization is used for data transmission through base station. If the base station is inaccessible region from the cluster-head, energy consumption will be augmented and it can shrink the lifetime of wireless sensor network. To conquer these, multi-hop gateway node is implemented with both protocol to achieve maximum lifetime and energy efficiency of wireless sensor network. To improve the quality-of-service (QoS) placing more number of gateways is required. So we propose a new algorithm nearer optimal algorithm which recursively computes least possible adequate dominating sets, at the time constantly preserving QoS requirements across iterations. In this paper comparison is done in terms of throughput, packets delivery ratio and number of nodes alive. [ABSTRACT FROM AUTHOR]

The energy consumption during the cluster head selection phase in a hierarchal and dynamic cluster based wireless sensor network had been considered insignificant in the previous research works. However, we have shown in our previous works that around 25% network energy is exhausted only in repeated cluster formation process of the network. We have proposed a round rotation (RR) protocol, which can be used in any dynamic cluster based network that can substantially conserve the overhead energy (the energy consumed in the random cluster head setup phase) of the network. It was shown that 20% of the total network energy consumed in data transmission can be conserved by minimizing the transmission of unnecessary control messages in the cluster setup phase. This paper also compares the overhead energy consumed in our proposed RR mechanism with three different mechanisms, (1) generic dynamic cluster based protocols, (2) centrally controlled dynamic cluster based protocols and (3) (re-clustering avoidance RCA) protocols. Results show that network lifetime can be improved by 25% using our proposed RR technique. The optimal value of cluster heads has also been calculated considering the network energy consumed in the different protocols. [ABSTRACT FROM AUTHOR]

The issue of antenna correlation in multi-pair massive antenna relay network is studied. Under the spatial correlation properties of the channel, an analytical approximation for both upper and lower bounds using popular maximum ratio combining/maximum ratio transmission relaying scheme is developed. This gives an insight of the system achievable rate by exploiting channel reciprocity in the time-division duplex protocol. To this aim five special antenna correlation cases are discussed and the corresponding overall spectral efficiency is analyzed. The performance of the scheme is compared against the other precoding and receiver combining schemes, i.e., zero forcing and minimum-mean-squared-error processing under the antenna correlation model. The analytical results backed up by simulations clearly quantify the impacts of antenna correlation under various cases on user spectral efficiency. [ABSTRACT FROM AUTHOR]

The recent development of the vehicular ad hoc networks (VANETs) has motivated an increasing interest in vehicular services and applications, such as active safety service and the infotainment service. Effective data Dissemination has become more and more important in vehicular services sharing. In this paper, the connectivity characteristics of VANETs are theoretically analyzed and implemented to show the partial connections in vehicle to vehicle communication. Hence, we propose the connectivity-aware data dissemination (CADD) in partially connected VANETs will improve the data transmission capacity. In the CADD protocol, a new metric of the node forwarding capability estimation is introduced. The metric is designed by the combination the throughput function and the active connection time estimation. And then, the high efficiency data dissemination protocol is designed by the new metric. Simulation results show that the CADD protocol outperforms existing solutions in terms of the packet delivery ratio, the transmission delay, and the protocol overhead under the condition of the intermittent network connectivity. [ABSTRACT FROM AUTHOR]

In MANETs, the mobile nodes usually relay other nodes' packets for the proper operation of the network. However, selfish nodes usually don't cooperate in relaying other nodes' packets but use the regular nodes to relay their packets. The increase in the number of selfish nodes affects the network performance badly. Existing protocols try to minimize the impact of selfish nodes with high computation overhead and/or communication overhead. In this paper, triple referee incentive mechanism is proposed that employs three referees to monitor the behavior of any intermediate node. In case of any selfish behavior, the packets will be bypassed through the referee nodes so that the data communication is uninterrupted in the network. In addition, the selfish nodes are motivated through incentives with less packet overhead. Hash operations are used in the data packets and acknowledgement packets instead of the public key cryptography operations so that the average packet overhead is less than that of the public key cryptography based incentive protocols. Hash values are used to attain payment non repudiation and restrain free riding attacks. [ABSTRACT FROM AUTHOR]

Recent research in mobile ad-hoc networks (MANETs) mostly deals to minimize the broadcast expenses of route discovery by controlling the query-broadcast. In this regard, a variety of broadcast-repealing schemes have been proposed, and employed to improve effectiveness and efficiency in various aspects of route-discovery considering time and energy. These schemes mainly focus on reducing unnecessary propagation of route-query by repealing the query-broadcast. Time-to-live based broadcast is the most common controlled-flooding scheme widely used in routing protocols. Recently some other broadcast-repealing schemes are proposed which work based on chasing-policy. The critical and analytical assessment to evaluate these schemes such aspects is of great importance. In this paper, we investigate their query-diffusion process, and their merits and demerits. [ABSTRACT FROM AUTHOR]

Abstract—Various wireless networks scenarios involve dissemination of large amounts of control information. This limits the channel resources available for transmission of the user data. This problem is especially crucial in dense networks, sensor networks, and high-mobility networks (e.g., networks of vehicles and drones). Several methods for dissemination of control information are known. This study is focused on the promising method called differential update. The idea behind it is that control messages sent by stations should contain only the information modified since the transmission of the previous message. An analytical model of this method has been developed. It allows one to estimate the average amount of transmitted control information and the reliability and promptness of its delivery to neighboring stations. An algorithm for adaptive tuning of parameters of the differential update method has been developed on the basis of this model. Simulation results obtained with NS-3 simulator demonstrate that the proposed algorithm minimizes the amount of sent control information while satisfying the set of requirements on reliability and promptness of its delivery. [ABSTRACT FROM AUTHOR]

Internet of vehicles (IoV) is a branch of the internet of things (IoT) which is used for communication among vehicles. As vehicular nodes are considered always in motion, hence it causes the frequent changes in the topology. These changes cause major issues in IoV like scalability, dynamic topology changes, and shortest path for routing. Clustering is among one of the solutions for such type of issues. In this paper, the stability of IoV topology in a dynamic environment is focused. The proposed metaheuristic dragonfly-based clustering algorithm CAVDO is used for cluster-based packet route optimization to make stable topology, and mobility aware dynamic transmission range algorithm (MA-DTR) is used with CAVDO for transmission range adaptation on the basis of traffic density. The proposed CAVDO with MA-DTR is compared with the progressive baseline techniques ant colony optimization (ACO) and comprehensive learning particle swarm optimization (CLPSO). Numerous experiments were performed keeping in view the transmission dynamics for stable topology. CAVDO performed better in many cases providing minimum number of clusters according to current channel condition. Considerable important parameters involved in clustering process are: number of un-clustered nodes as a re-clustering criterion, clustering time, re-clustering delay, dynamic transmission range, direction, and speed. According to these parameters, results indicate that CAVDO outperformed ACO-based clustering and CLPSO in various network settings. Additionally, to improve the network availability and to incorporate the functionalities of next-generation network infrastructure, 5G-enabled architecture is also utilized. [ABSTRACT FROM AUTHOR]

As overall network traffic pursue to expand, a lot of low-power medium access control protocols have been proposed to deal with burst traffic in wireless sensor network. Although most of them provide low throughput but do not well optimize the energy consumption. In this paper, we propose a new hybrid carrier sense multiple access with collision avoidance (CSMA/CA) and time division multiple access (TDMA) protocol that arranges nodes into two categories of priority according to their traffic rate and data transmission delay. Nodes that have continuous data should send its data during the contention free period, those one will be classified as low priority and its data will be scheduling using TDMA. Others nodes who have a random data should transmit it immediately during the contention access period (CAP) using a fuzzy logic algorithm, based on their queue length and implemented in the CSMA/CA algorithm. Therefore, the proposed scheme dynamically changes the CAP length to ensure that nodes can complete its transaction during the same super-frame. Simulation results are done using the network simulator tools (NS-2) and have improved good efficiency regarding the IEEE 802.15.4 standard. The mechanism has improved the energy consumption, minimised the packet loss probability, increased the throughput variation in the network and also minimised the average end to end delay. [ABSTRACT FROM AUTHOR]

In the medium access control layer (MAC) of WSN, the scheduling mechanism of nodes based on the periodical listen/sleep is an effective way of saving node energy consumption. In the case of data transmission which is not affected reduces the nodes’ proportions, we improve the protocols based on asynchronous MAC. This paper discusses a protocol which is a low duty cycle energy-efficient MAC protocol for WSN and can be adaptively updated based on the prediction nodes’ wake-up time. We call it AP-MAC protocol. In AP-MAC protocol, the nodes will not wake up or send data in the same period, and they will wake up in random time according to the algorithm that has been set. In this case, the network can avoid the problem of collision, cross-talk, etc. caused by all the nodes’ wake-up in the same time, and save more energy. To ensure the reliable transmission of network data, the node which sends data will predict the wake-up time of receiving nodes and ensure the receiving nodes wake up timely and establish a connection with sending note. At the same time, we join several adaptive update mechanisms in the network according to the dynamic changes of it. The experimental results show that the improved protocol not only can save the network energy consumption by effectively reducing the overall duty cycle of the network nodes and improving the reliable transmission of data but also can improve the adaptability of the network. [ABSTRACT FROM AUTHOR]

This article introduces the extended versions of selected papers from the refereed proceedings of the 16th International Conference on Runtime Verification (RV 2016) held in Madrid, Spain, in September 2016. Runtime verification encompasses all aspects of monitoring and analysis of hardware, software, and system executions in general. Runtime verification techniques are lightweight dynamic techniques to assess and enforce correctness, reliability, and robustness during system execution. These techniques are significantly more powerful and versatile than conventional testing, and more practical than exhaustive formal verification (at the price of incomplete coverage). [ABSTRACT FROM AUTHOR]

Effective techniques for extending lifetime in multi-hop wireless sensor networks include duty cycling and, more recently introduced, cooperative transmission (CT) range extension. However, a scalable MAC protocol has not been presented that combines both. An On-demand Scheduling Cooperative MAC protocol (OSC-MAC) is proposed to address the energy hole problem in multi-hop wireless sensor networks (WSNs). By combining an on-demand strategy and sensor cooperation intended to extend range, OSC-MAC tackles the spatio-temporal challenges for performing CT in multi-hop WSNs: cooperating nodes are neither on the same duty cycle nor are they necessarily in the same collision domain. We use orthogonal and pipelined duty-cycle scheduling, in part to reduce traffic contention, and devise a reservation-based wake-up scheme to bring cooperating nodes into temporary synchrony to support CT range extension. The efficacy of OSC-MAC is demonstrated using extensive NS-2 simulations for different network scenarios without and with mobility. Compared with existing MAC protocols, simulation results show that while we explicitly account for the overhead of CT and practical failures of control packets in dense traffic, OSC-MAC still gives 80-200 % lifetime improvement. [ABSTRACT FROM AUTHOR]

An opportunistic network is a wireless ad hoc network that has frequently intermittent connectivity due to nodes’ mobility. These spare, unpredictable networks aim to solve the prolonged delay paths by a store-carry-forward scheme. It is difficult to determine the appropriate nodes to forward the messages since there are few opportunistic contacts. The nodes might decide based on the obtained data of the network as a guide to reach a destination. The aforementioned technique is not helpful in case the rate of change in the network topology is higher than the rate of data gathering due to usage restrictions and uncertain available information/knowledge of the future contacts. In this paper, to cope with the challenges imposed by the un-deterministic environment, a risk assessment strategy is considered to evaluate the short and long-term impact of each decision to find the optimal node/paths. This routing scheme can take advantage of the unanticipated connection to make the routing more flexible in short time and with less buffer usage. Our proposed risk assessment algorithms that are based on MALP are mixed with the knowledge about buffer management and network capacity. The prioritized messages to be disseminated as well as better decision to take a risk are the main contributions of this paper. Moreover, the self-adaptive threshold, distributed PID controller, is considered to tackle different threshold levels for each node individually. Numerical results prove that the proposed method drastically increases the delivery ratio and also minimizes the risk of exceeding resource consumption and packet loss. [ABSTRACT FROM AUTHOR]

To support communications of a large number of deployed devices while guaranteeing limited signaling load, low energy consumption and high reliability, future cellular systems require efficient random access protocols. However, how to address the collision resolution at the receiver is still the main bottleneck of these protocols. The network-assisted diversity multiple access (NDMA) protocol solves the issue and attains the highest potential throughput at the cost of keeping devices active to acquire feedback and repeating transmissions until successful decoding. In contrast, another potential approach is the feedback-free NDMA (FF-NDMA) protocol, in which devices do repeat packets in a pre-defined number of consecutive time slots without waiting for feedback associated with repetitions. Here, we investigate the FF-NDMA protocol from a cellular network perspective in order to elucidate under what circumstances this scheme is more energy efficient than NDMA. We characterize analytically the FF-NDMA protocol along with the multipacket reception model and a finite Markov chain. Analytic expressions for throughput, delay, capture probability, energy, and energy efficiency are derived. Then, clues for system design are established according to the different trade-offs studied. Simulation results show that FF-NDMA is more energy efficient than classical NDMA and HARQ-NDMA at low signal-to-noise ratio (SNR) and at medium SNR when the load increases. [ABSTRACT FROM AUTHOR]

Mobile ad hoc networks (MANETs) are mobile networks, which are automatically outspread on a geographically limited region, without requiring any preexisting infrastructure. Mostly, nodes are both self-governed and self-organized without requiring a central monitoring. Because of their distributed characteristic, MANETs are vulnerable to a particular routing misbehavior, called wormhole attack. In wormhole attack, one attacker node tunnels packet from its position to the other attacker nodes. Such wormhole attack results in a fake route with fewer hop count. If source node selects this fictitious route, attacker nodes have the options of delivering the packets or dropping them. For this reason, this paper proposes an improvement over AODV routing protocol to design a wormhole-immune routing protocol. The proposed protocol called defending against wormhole attack (DAWA) employs fuzzy logic system and artificial immune system to defend against wormhole attacks. DAWA is evaluated through extensive simulations in the NS-2 environment. The results show that DAWA outperforms other existing solutions in terms of false negative ratio, false positive ratio, detection ratio, packet delivery ratio, packets loss ratio and packets drop ratio. [ABSTRACT FROM AUTHOR]

Three factors have been often shown to significantly affect the reliability of real-time transmission in wireless local area networks-transmission rate, power, and packet size. We analyze these factors and determine the optimal combination of factors subject to time constraints that yields the most reliable transmission of real-time data. We propose a cross-layer framework to jointly design the routing and MAC protocol combined with our optimization approach. The approach under a non-real-time routing protocol that produces a path metric is compared with a real-time routing protocol. Additionally, the real-time routing protocol enhances a guaranteed rate with our approach. Our experiments reveal that real-time performance in terms of miss ratio and throughput is significantly increased in lossy link and heavy traffic environments. Miss ratio and average throughput are improved by up to 30% over a state-of-the art routing protocol and 35% over a MAC protocol, respectively. [ABSTRACT FROM AUTHOR]

TCP has been extensively credited for the stability of the Internet. However, as the product of bandwidth and latency increases, TCP becomes inefficient and prone to instability. The explicit control protocol (XCP) is a promising congestion control protocol that outperforms TCP in terms of efficiency, fairness, convergence speed, persistent queue length and packet loss rate. However, XCP is not globally stable in the presence of heterogeneous delays. When the ratio of maximum to average transmission latency is sufficiently large, XCP will become instability. In this paper, according to the robust control theory, with the help of a recently developed Lyapunov-Krasovskii functional, an improved version of XCP, named R-XCP, is proposed to solve the weakness of XCP under heterogeneous delays, which adjusts parameter $$\alpha $$ from an initial value of 0.4 to a reasonable value for improving system robustness. And then, the synthesis problem is reduced to a convex optimization scheme expressed in terms of linear matrix inequalities. Extensive simulations have shown that R-XCP significantly decreases the volatilities of the aggregate traffic rate and control time interval, and indeed achieves this stability goal. Compared with previous work, R-XCP has a better balance between robustness and responsiveness, and the computational complexity declines significantly at the same time. Besides, R-XCP makes the system less sensitive to flows, which contribute little traffic but maliciously report their transmission delays. [ABSTRACT FROM AUTHOR]

To improve the efficiency of carrier sense multiple access (CSMA)-based medium access control (MAC) protocol, CSMA with collision resolution (CSMA/CR) has been proposed. In the CSMA/CR protocol, a transmitting station can detect a collision by employing additional carrier sensing after the start of data transmission and resolve the next collision that might occur by broadcasting a jam signal during a collision detection (CD) period. By extending this original CSMA/CR protocol that uses a single CD phase, in this paper we propose a multi-phased CSMA/CR (MP-CSMA/CR) protocol that employs multiple CD phases. In the proposed MP-CSMA/CR protocol, colliding stations are filtered in each CD phase, and only surviving stations compete again in the next CD phase. Therefore, the collision resolution probability becomes higher as the CD phases proceed. Utilizing the multiple CD phases, we analyze the throughput numerically and find optimal operating parameters-such as the number of CD phases and the number of CD slots per phase-that maximize the throughput. Based on this result, we also propose a dynamic MP-CSMA/CR protocol in which the number of CD phases is dynamically changed to suit network conditions. Analysis and simulation results show that the proposed MP-CSMA/CR protocol significantly outperforms CSMA/CR with a single CD phase. The dynamic MP-CSMA/CR protocol achieves a slightly better throughput than MP-CSMA/CR, which uses a fixed optimal number of CD phases. [ABSTRACT FROM AUTHOR]

This paper proposes to increase the efficiency energy of nodes which rapidly drops during the transmission of the LEACH (Low Energy Adaptive Clustering Hierarchy), using the method of the dual-hop layered in the sensor field. By introducing dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission was introduce. By introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was introduces. In the proposed DL-LEACH, the energy consumption of cluster head for remote transmission reduces and increases the energy efficiency of sensor node by reducing the transmission distance and simplifying the transmission routine for short-range transmission. As compared the general LEACH, it was adapted to a wider sensor field. [ABSTRACT FROM AUTHOR]

One of important issues in wireless sensor networks is how to effectively use the limited node energy to prolong the lifetime of the networks. Clustering is a promising approach in wireless sensor networks, which can increase the network lifetime and scalability. However, in existing clustering algorithms, too heavy burden of cluster heads may lead to rapid death of the sensor nodes. The location of function nodes and the number of the neighbor nodes are also not carefully considered during clustering. In this paper, a multi-factor and distributed clustering routing protocol MFDCRP based on communication nodes is proposed by combining cluster-based routing protocol and multi-hop transmission. Communication nodes are introduced to relay the multi-hop transmission and elect cluster heads in order to ease the overload of cluster heads. The protocol optimizes the election of cluster nodes by combining various factors such as the residual energy of nodes, the distance between cluster heads and the base station, and the number of the neighbor nodes. The local optimal path construction algorithm for multi-hop transmission is also improved. Simulation results show that MFDCRP can effectively save the energy of sensor nodes, balance the network energy distribution, and greatly prolong the network lifetime, compared with the existing protocols. [ABSTRACT FROM AUTHOR]

Transmission of system-critical control information plays a key role in efficient management of limited wireless network resources and successful reception of payload data information. This paper uses an orthogonal frequency division multiplexing (OFDM) architecture to investigate the detection performance of a time-domain approach used to detect deterministic control signalling information. It considers a type of control information chosen from a finite set of information, which is known at both transmitting and receiving wireless terminals. Unlike the maximum likelihood (ML) estimation method, which is often used, the time-domain detection technique requires no channel estimation and no pilots as it uses a form of time-domain correlation as the means of detection. Results show that when compared with the ML method, the time-domain approach improves detection performance even in the presence of synchronisation error caused by carrier frequency offset. [ABSTRACT FROM AUTHOR]

Many applications of wireless sensor networks (WSNs) require events be detected around moving targets and delivered to a user, whose location may also change over time. Consequently, it is not desirable to have a single sensor node serving as the sink node for centralized event processing. Furthermore, an event usually occurs across different locations and lasts for a period of time that are unknown in advance. Hence it cannot be detected by a static set of sensor nodes. In this paper, we propose a general framework for such dynamic in-network event detection in WSNs. This framework enables a flexible number of sensor nodes to dynamically collaborate in detecting and delivering any specified event. So far there has been no such work reported in the literature. We have designed a protocol for the sensor nodes to autonomously determine whether they should participate in and which tasks they should perform to collaboratively process an event. We have implemented a prototype of the proposed framework using MicaZ motes and evaluated it through both simulations and experiments. The results demonstrate that our framework is effective and efficient in terms of energy cost and event processing delay. [ABSTRACT FROM AUTHOR]

This paper focuses on the event based investigations over different data dissemination routing protocols for highly dense wireless sensor networks. Initially for the wireless sensor network domain, we analyzed data dissemination flooding and gossiping routing protocols. We etude and exemplify our proposed model for data dissemination based evaluation with Delphi random generator distribution strategy. We calculated performance metrics as sense count, transmit count, receive count and receive redundant count. At the end, simulations analysis has been carried out to prove the validity of our designed scenario. [ABSTRACT FROM AUTHOR]

Among synchronization protocols applied in wireless sensor network, reference broadcast synchronization (RBS) is one prominent protocol achieving very high accuracy of synchronization given that the broadcasting medium is available. However, that the protocol lacks packet loss tolerance brings about degraded performance in severe conditions of wireless channel. Also, the instantaneous synchronization used in this protocol results in time discontinuity, which might cause serious faults in the distributed system. In this study, we propose a packet loss tolerance and continuous synchronization mechanism for RBS. Then we verified the result through simulations. [ABSTRACT FROM AUTHOR]

The reliable data delivery is a challenging task in Wireless Sensor Networks (WSNs) due to dynamic and unpredictable changing behaviors of nodes. The traditional cryptographic and authentication based schemes can't be adopted due to their associated cost and incapability to counter nodes misbehavior attacks. Recently, trust based solutions have proved to be more effective to address nodes' misbehavior attacks. Apart from isolating misbehaving nodes, the existing trust based schemes lacks the capability to minimize link failure notifications due to transient transmission disruption which consequently give rise to frequent route breakages thereby undermining throughput and route stability. Moreover, the existing solutions give rise to high energy consumption and control overhead in pursuit of trust estimation and network-wide dissemination which not only adds to network congestion but also undermines network lifetime. In this paper, we present a Trust and Energy aware Routing Protocol (TERP) that makes use of a distributed trust model for the detection and isolation of misbehaving nodes. TERP incorporates a composite routing function that encompasses trust, residual-energy, and hop count of neighbor nodes in making routing decisions. This multi-facet routing strategy helps to balance out energy consumption among trusted nodes while routing data using shorter paths. Moreover, TERP intelligently evaluates the actual link breakage thereby avoiding unnecessary route discoveries. Simulation results demonstrate improved throughput, network lifetime and route stability of TERP when compared to existing work. [ABSTRACT FROM AUTHOR]

Achieving same notion of time remains an important task for most distributed systems. Time synchronization requires a unique combination of high accuracy ( $$\upmu $$ s level) and energy efficiency. Several application layer protocols have been developed to meet these requirements. This article proposes that the physical layer clock recovery process can provide application layer clock drift estimate, and the application layer clock can be corrected with the help of this estimate. This eliminates the need of application layer time synchronization protocol i.e. the cross-layer approach reduces the number of message exchanges required by application layer for time synchronization that leads to energy conservation. It argues that such a cross-layer approach can provide a more accurate frequency offset estimation, or can achieve greater energy savings, for a given accuracy, by reducing the message exchanges. Analysis of the proposed method provides concrete bounds on achieved improvement. Experimental evaluation showed that physical layer clock drift can be used to correct application layer clock drift as they are identical. [ABSTRACT FROM AUTHOR]

Transmission Control Protocol (TCP) performs poorly over wireless networks. Some research indicates that the TCP congestion control mechanism may cause burstiness in the traffic flow. Numerous TCP segments are delivered simultaneously, while an acknowledgement of a retransmission is successfully received. Burstiness leads to a highly contentious network, which markedly increases the probability of packet loss on wireless networks. TCP pacing is a possible solutions for TCP burstiness on multi-hop networks. In this algorithm, TCP segment transmissions are distributed over the whole Round Trip Time. Most pacing protocols attempt to insert a delay interval into the TCP transmissions. However, there is a similar pacing algorithm in IEEE802.11, known as the contention window mechanism. In this paper, we first measure and analyze the way that the contention window size affects TCP throughput in different scenarios. We propose a cross-layer TCP pacing protocol by contention control in the MAC layer, called TCP Contention Control (TCP-CC). It adjusts the lower bound of the contention window in order to optimize the overall TCP throughput in both one-hop and multi-hop topology. Finally, comparative simulations are conducted in order to verify the improvements of our protocol on both TCP Reno and TCP Vegas. [ABSTRACT FROM AUTHOR]

IP-enabled sensors can be globally addressable by any Internet-connected entity, and therefore, their protection presents different challenges than that of traditional sensors, as they are subject to any potential attacker in the Internet. For this reason, specific security protocols must be developed to address the security requirements of IP-enabled sensors. An interesting approach to achieve this aim is the Ladon security protocol, which allows resource-deprived devices to efficiently implement end-to-end authentication, authorisation and key establishment mechanisms. However, in so limited environments such as sensor networks, not only efficient protocols must be defined, but they must also be optimally parameterised. This paper constitutes a step forward in this direction. First, a state transition model of the Ladon protocol is presented to analytically describe its behaviour. Then, this model is used to select the most effective parameterisation of the protocol in terms of message retransmissions and execution of cryptographic operations. The obtained results show that the selected parameterisation allows maximising the probability of a successful secure session establishment, while keeping the overhead introduced by the protocol low. Additionally, the performance comparison carried out shows that Ladon outperforms alternative approaches to achieve the same objective in terms of message transmission and reception operations. [ABSTRACT FROM AUTHOR]

Opportunistic routing can greatly improve energy efficiency in wireless sensor networks (WSNs). An important challenge is the design of a coordination protocol to implement an effective relay selection and prioritization scheme to minimize expected cost. Many existing opportunistic routing protocols often assumed an ideal link-layer, and thus the computed forwarder list may be suboptimal. Worth noting that, the computation complexity of optimal result grows rapidly with size of candidate set when the nonideal link-layer conditions are taken into account. It is, however, not feasible for energy and processing capability constrained WSNs. To address this problem, we propose a low-cost low-complexity opportunistic routing (L2OR) protocol to achieve an energy-efficient data delivery over WSNs. Our research work begins with a thorough investigation and understanding of properties of forwarder list under nonideal link-layer conditions. On this basis, a low-complexity heuristic algorithm is designed to efficiently find a reasonable choice of forwarder list, with an objective of reducing the search space to the size of candidate set. We conduct theoretical analysis and a set of simulation experiments to evaluate the performance of our L2OR. It is shown that, when comparing to typical energy-aware opportunistic protocol, the L2OR can achieve performance improvement in terms of data transmission efficiency as well as energy consumption. [ABSTRACT FROM AUTHOR]

Although existing wakeup scheduling techniques suggest end-to-end delay guarantees for real-time applications, their fixed wakeup schedules may not meet such constraints when multiple sensors compete for the event delivery at the same time. In this paper we propose a new MAC protocol called SPEED-MAC that can provide real-time delay guarantees with much lower energy consumption for both single-source and multi-source events. The main ideas underlying the protocol are twofold. First, we introduce a novel wakeup technique called signaling wakeup, which is small only enough to detect the event occurrence. By employing the signaling wakeup we can minimize the event report latency as well as the idle listening. Second, to resolve the collisions and contentions incurred by multi-source events, the protocol employs adaptive wakeup that combines static scheduling with contention-based media access control depending on the type of traffic. The result of our analytic evaluation confirms that SPEED-MAC can provide real-time delay guarantees even for a large-scale network assuming a low event rate. We have implemented SPEED-MAC on both NS-2 and MICA2 platforms, and evaluated both the energy and the network performance of the protocol for various scenarios including multi-source, multi-sink, source-to-sink, sink-to-source, multi-cast and broadcast traffic. Our experimentation results show that SPEED-MAC can achieve an order of magnitude energy savings while providing near optimal latency compared to the existing solutions. [ABSTRACT FROM AUTHOR]