Unreliable Wireless Links Research Articles

Achieving Efficient Reliable Flooding in Low-Duty-Cycle Wireless Sensor Networks

Reliable flooding in wireless sensor networks (WSNs) is desirable for a broad range of applications and network operations. However, relatively little work has been done for reliable flooding in low-duty-cycle WSNs with unreliable wireless links. It is a challenging problem to efficiently ensure 100% flooding coverage considering the combined effects of low-duty-cycle operation and unreliable wireless transmission. In this paper, we propose a novel dynamic switching-based reliable flooding (DSRF) framework, which is designed as an enhancement layer to provide efficient and reliable delivery for a variety of existing flooding tree structures in low-duty-cycle WSNs. The key novelty of DSRF lies in the dynamic switching decision making when encountering a transmission failure, where a flooding tree structure is dynamically adjusted based on the packet reception results for energy saving and delay reduction. DSRF distinguishes itself from the existing works in that it explores both poor links and good links on demand. In addition, we define the optimal wakeup schedule-ranking problem in order to maximize the switching gain in DSRF. We prove the NP-completeness of this problem and present a heuristic algorithm with a low computational complexity. Through comprehensive performance comparisons, including the simulation of large-scale scenarios and small-scale experiments on a WSN testbed, we demonstrate that compared with the flooding protocol without DSRF enhancement, the DSRF effectively reduces the flooding delay and the total number of packet transmission by $12\%{\sim }25\%$ and $10\%{\sim }15\%$ , respectively. Remarkably, the achieved performance is close to the theoretical lower bound.

Resource allocation for real-time traffic in unreliable wireless cellular networks

Providing reliable transmission for real-time traffic in wireless cellular networks is a great challenge due to the unreliable wireless links. This paper concentrates on the resource allocation problem aiming to improve the real-time throughput. First, the resource allocation problem is formulated as a Markov Decision Process and thus the optimal resource allocation policy could be obtained by adopting the value iteration algorithm. Considering the high time complexity of the optimal algorithm, we further propose an approximate algorithm which decomposes the resource allocation problem into two subproblems, namely link scheduling problem and packet scheduling problem. By this method, the unreliable wireless links are only constrained in the link scheduling problem, and we can focus on the real-time requirement of traffic in packet scheduling problem. For the link scheduling problem, we propose the maxRel algorithm to maximize the long-term network reliability, and we theoretically prove that the maxRel algorithm is optimal in scenarios with dynamic link reliabilities. The Least Laxity First algorithm is adopted for the packet scheduling problem. Extensive simulation results show that the proposed approximate resource allocation algorithm makes remarkable improvement in terms of time complexity, packet loss rate and delay.

Multi-constraint multi-objective QoS aware routing heuristics for query driven sensor networks using fuzzy soft sets

In this paper, a fuzzy based distributed power aware routing scheme considering both energy and bandwidth constraints, especially for query driven applications in the asynchronous duty-cycled wireless sensor networks are devised. The proposed multi-constraint, multi-objective routing optimization approach under strict resource constraints guarantees reliability and fast data delivery along with efficient power management in spite of unreliable wireless links and limited power supply. In query driven applications, the request from the sink to the individual sensor node will be a broadcast message, whereas the individual sensor nodes replies back to sink as unicast messages. In the proposed work, the fuzzy approach and “A Star” algorithm are utilized for satisfying energy and bandwidth constraints to route the broadcast messages of the sink while querying all the sensor nodes in the network. Every node will be provided with a guidance list, which is used to decide the next best neighbor node with good route quality for forwarding the received multi-hop broadcast messages. The route quality of the every node is estimated with fuzzy rules based on the network parameters such as maximum remaining energy, minimum traffic load and better link quality to increase the network lifetime. The provision of overhearing the broadcast messages and acknowledgements within the transmission range minimizes the effort to search for the active time of nodes while routing the broadcast messages with asynchronous scheduling. Further, in the proposed work only the time slot of its nearest neighbor relay node (to which packets are to be forwarded) is learnt to reduce the number of message transmissions in the network. For the unicast message replies, the fuzzy membership function is modified and devised based on the routing metrics such as higher residual energy, minimum traffic loads and minimum hop count under energy and bandwidth constraints. Also, the multi-hop heuristic routing algorithm called Nearest Neighbor Tree is effectively used to reduce the number of neighbors in the guidance list that are elected for forwarding. This helps to increase the individual sensor node’s lifetime, thereby maximizes the network lifetime and guarantees increased network throughput. The simulation results show that the proposed technique reduces repeated transmissions, decreases the number of transmissions, shortens the active time of the sensor nodes and increases the network lifetime for query driven sensor network applications invariant to total the number of sensor nodes and sinks in the network. The proposed algorithm is tested in a small test bed of sensor network with ten nodes that monitors the room temperature.

TCP adaptation with network coding and opportunistic data forwarding in multi-hop wireless networks

Opportunistic data forwarding significantly increases the throughput in multi-hop wireless mesh networks by utilizing the broadcast nature of wireless transmissions and the fluctuation of link qualities. Network coding strengthens the robustness of data transmissions over unreliable wireless links. However, opportunistic data forwarding and network coding are rarely incorporated with TCP because the frequent occurrences of out-of-order packets in opportunistic data forwarding and long decoding delay in network coding overthrow TCP’s congestion control. In this paper, we propose a solution dubbed TCPFender, which supports opportunistic data forwarding and network coding in TCP. Our solution adds an adaptation layer to mask the packet loss caused by wireless link errors and provides early positive feedbacks to trigger a larger congestion window for TCP. This adaptation layer functions over the network layer and reduces the delay of ACKs for each coded packet. The simulation results show that TCPFender significantly outperforms TCP/IP in terms of the network throughput in different topologies of wireless networks.

Co-DDTMA: Cooperative Distributed TDMA for Vehicular Networks

In recent years, Vehicular Ad Hoc Networks (VANET) has experienced a rapid development due to the advancement of wireless communication technologies, and now emerges as a promising way to provide road safety, traffic efficiency and infotainment applications. However, it is a challenge to design a reliable and efficient Medium Access Control (MAC) protocol for VANET due to its frequent topology changes and unreliable wireless links. Cooperative communication, on the other hand, can enhance the reliability of wireless links by exploiting the broadcast nature of the wireless communication. A cooperative scheme for MAC is proposed for VANET in this paper, referred to as Cooperative Distributed TDMA (Co-DTDMA). In the Co-DTDMA, neighboring nodes utilize its idle slots for cooperatively retransmitting a packet which has failed to reach the destination. Since the cooperative retransmission is conducted in node's own idle slot, the proposed scheme does not interrupt the normal transmission. Both theoretical analysis and simulation results demonstrate that the proposed scheme greatly increases the probability of successful packet transmission and decreases the packet transmission delay.

Delay-Aware Program Codes Dissemination Scheme in Internet of Everything

Due to recent advancements in big data, connection technologies, and smart devices, our environment is transforming into an “Internet of Everything” (IoE) environment. These smart devices can obtain new or special functions by reprogramming: upgrade their soft systems through receiving new version of program codes. However, bulk codes dissemination suffers from large delay, energy consumption, and number of retransmissions because of the unreliability of wireless links. In this paper, a delay-aware program dissemination (DAPD) scheme is proposed to disseminate program codes with fast, reliable, and energy-efficient style. We observe that although total energy is limited in wireless sensor network, there exists residual energy in nodes deployed far from the base station. Therefore, DAPD scheme improves the performance of bulk codes dissemination through the following two aspects. (1) Due to the fact that a high transmitting power can significantly improve the quality of wireless links, transmitting power of sensors with more residual energy is enhanced to improve link quality. (2) Due to the fact that performance of correlated dissemination tends to degrade in a highly dynamic environment, link correlation is autonomously updated in DAPD during codes dissemination to maintain improvements brought by correlated dissemination. Theoretical analysis and experimental results show that, compared with previous work, DAPD scheme improves the dissemination performance in terms of completion time, transmission cost, and the efficiency of energy utilization.

Toward <inline-formula> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula>-Connectivity of the Random Graph Induced by a Pairwise Key Predistribution Scheme With Unreliable Links

We study the secure and reliable connectivity of wireless sensor networks. Security is assumed to be ensured by the random pairwise key predistribution scheme of Chan, Perrig, and Song, and unreliable wireless links are represented by independent on/off channels. Modeling the network by an intersection of a random $K$-out graph and an Erd\H{o}s-R\'enyi graph, we present scaling conditions (on the number of nodes, the scheme parameter $K$, and the probability of a wireless channel being on) such that the resulting graph contains no nodes with degree less than $k$ with high probability, when the number of nodes gets large. Results are given in the form of zero-one laws and are shown to improve the previous results by Ya\u{g}an and Makowski on the absence of isolated nodes (i.e., absence of nodes with degree zero). Via simulations, the established zero-one laws are shown to hold also for the property of $k$-connectivity; i.e., the property that graph remains connected despite the deletion of any $k-1$ nodes or edges.

Distributed robust control for nonlinear systems using wireless neural control

This paper is concerned with the synthesis of a class of nonlinear system over the wireless neural control network (WNCN) which refers to a group of neuron nodes interacting with each other by radio connection. The nonlinear system is modeled by a standard neural network model (SNNM) which is the interconnection of a linear dynamic system and bounded static nonlinear operators. The WNCN treats itself as a fully distributed nonlinear dynamic controller. The unreliable wireless communication links within WNCN are modeled by fading channels. By constructing appropriate discretetime Lyapunov function, the global asymptotic stability of the closed-loop system is discussed in particular for the cases with stochastic perturbations induced by packet losses. The connection weights among the neuron nodes that guarantee stability of the system can be obtained by solving a convex optimization problem with some linear matrix inequality (LMI) constraints. A numerical example is given to illustrate the correctness and effectiveness of the theoretical results.

Special issue on energy‐efficient wireless communication networks with QoS

Special issue on energy‐efficient wireless communication networks with QoS

Broadcasting Delay-Constrained Traffic Over Unreliable Wireless Links With Network Coding

There is increasing demand for using wireless networks for applications that generate packets with strict per-packet delay constraints. In addition to delay constraints, such applications also have various traffic patterns and require guarantees on throughputs of packets that are delivered within their delay constraints. Furthermore, a mechanism for serving delay-constrained traffic needs to specifically consider the unreliable nature of wireless links, which may differ from link to link. Also, as it is usually infeasible to gather feedback information from all clients after each transmission, broadcasting delay-constrained traffic requires addressing the challenge of the lack of feedback information. We study a model that jointly considers the application requirements on traffic patterns, delay constraints, and throughput requirements, as well as wireless limitations, including the unreliable wireless links and the lack of feedback information. Based on this model, we develop a general framework for designing feasibility-optimal broadcasting policies that applies to systems with various network coding mechanisms. We demonstrate the usage of this framework by designing policies for three different kinds of systems: one that does not use network coding, one that employs XOR coding, and the last that allows the usage of linear coding.

QoS Sensitive VANET Control Scheme based on Feedback Game Model

As a special type of mobile ad-hoc network, Vehicular Ad-hoc Network (VANET) is considered as an attractive topic by many researchers. In VANETs, vehicles act as routers and clients, which are connected with each other through unreliable wireless links. Due to the dynamic nature of vehicles, developing communication protocols for VANETs is a challenging task. In this paper, we tackle the problem of real-world VANET operations and propose a new dual-level communication scheme through the combination of power and rate control algorithms. Based on the game theoretic approach, the proposed scheme effectively formulates the interactive situation among several vehicles. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse VANET environments.

English

Providing reliable and efficient communication under fading channels is one of the major technical challenges in wireless sensor networks (WSNs), especially in industrial WSNs (IWSNs) with dynamic and harsh environments. Reliable Reactive Routing Enhancement (R3E) to increase the resilience to link dynamics for WSNs/IWSNs. R3E is designed to enhance existing reactive routing protocols to provide reliable and energy-efficient packet delivery against the unreliable wireless links by utilizing the local path diversity. A biased back off scheme has been introduced, during the route-discovery phase to find a robust guide path, which can provide more cooperative forwarding opportunities. Along this guide path, data packets are greedily progressed toward the destination through nodes’ cooperation without utilizing the location information. R3E remarkably improves the packet delivery ratio, while maintaining high energy efficiency and low delivery latency.

Primary path reservation using enhanced slot assignment in TDMA for session admission.

Mobile ad hoc networks (MANET) is a self-organized collection of nodes that communicates without any infrastructure. Providing quality of service (QoS) in such networks is a competitive task due to unreliable wireless link, mobility, lack of centralized coordination, and channel contention. The success of many real time applications is purely based on the QoS, which can be achieved by quality aware routing (QAR) and admission control (AC). Recently proposed QoS mechanisms do focus completely on either reservation or admission control but are not better enough. In MANET, high mobility causes frequent path break due to the fact that every time the source node must find the route. In such cases the QoS session is affected. To admit a QoS session, admission control protocols must ensure the bandwidth of the relaying path before transmission starts; reservation of such bandwidth noticeably improves the admission control performance. Many TDMA based reservation mechanisms are proposed but need some improvement over slot reservation procedures. In order to overcome this specific issue, we propose a framework—PRAC (primary path reservation admission control protocol), which achieves improved QoS by making use of backup route combined with resource reservation. A network topology has been simulated and our approach proves to be a mechanism that admits the session effectively.

Timer‐based power management for infrastructure IEEE 802.11 WLAN with unreliable wireless links

SUMMARYEfficient power management is a critical requirement for the battery‐operated portable electronic devices incorporating wireless transceivers to have a longer runtime. The existing timer‐based power management (TPM) is able to balance energy saving and quality of service requirements by tuning the values of its idle and doze timers. In this paper, the TPM applied in the infrastructure IEEE 802.11 wireless local area network with unreliable wireless links, referred to as TPM‐UWL, is presented. A novel stochastic analysis model is developed for TPM‐UWL, based on which the probabilities that a mobile station (STA) is at active, dozing, and idle states are obtained. Additionally, the number of buffered frames at the access point and the sleeping STA, the STA's average power consumption, and a frame's average delay under TPM‐UWL are derived. Further, the optimization problem that minimizes power consumption under the constraints of delay and buffer size is presented, which enables an STA to set its maximum number of retransmissions and the values of the idle and doze timers in the medium access control layer such that power consumption is minimized, while the constraints of delay and buffer size are satisfied. Copyright © 2014 John Wiley & Sons, Ltd.

Opportunistic Flooding in Low-Duty-Cycle Wireless Sensor Networks with Unreliable Links

Flooding service has been investigated extensively in wireless networks to efficiently disseminate network-wide commands, configurations, and code binaries. However, little work has been done on low-duty-cycle wireless sensor networks in which nodes stay asleep most of the time and wake up asynchronously. In this type of network, a broadcasting packet is rarely received by multiple nodes simultaneously, a unique constraining feature that makes existing solutions unsuitable. In this paper, we introduce Opportunistic Flooding, a novel design tailored for low-duty-cycle networks with unreliable wireless links and predetermined working schedules. Starting with an energy-optimal tree structure, probabilistic forwarding decisions are made at each sender based on the delay distribution of next-hop receivers. Only opportunistically early packets are forwarded via links outside the tree to reduce the flooding delay and redundancy in transmission. We further propose a forwarder selection method to alleviate the hidden terminal problem and a link-quality-based backoff method to resolve simultaneous forwarding operations. We show by extensive simulations and test-bed implementations that Opportunistic Flooding is close to the optimal performance achievable by oracle flooding designs. Compared with Improved Traditional Flooding, our design achieves significantly shorter flooding delay while consuming only 20-60% of the transmission energy.

Cooperative clustering‐based medium access control for broadcasting in vehicular ad‐hoc networks

Owing to the advancement of wireless communication technologies, the vehicular ad-hoc network (VANET) has experienced a rapid development in recent years. However, it is challenging to design a reliable and efficient medium access control (MAC) protocol for safety messages with strict quality of service demands, owing to unreliable wireless links and frequent changes of topology. On the other hand, cooperative communication can enhance the reliability of wireless links by exploiting the spatial diversity. The authors present here a cooperative clustering-based MAC (CCB-MAC) protocol for VANETs, in order to improve the transmission reliability of safety messages. In CCB-MAC, the selected helpers relay the safety message to the nodes that have failed in reception during the broadcast period. In addition, cooperation is conducted in idle slots, without interrupting the normal transmission. Both mathematical analysis and numerical results demonstrate that CCB-MAC increases the successful reception rate of safety messages significantly.

Assessing Diagnosis Approaches for Wireless Sensor Networks: Concepts and Analysis

Diagnosis is of great importance to wireless sensor networks due to the nature of error prone sensor nodes and unreliable wireless links. The state-of-the-art diagnostic tools focus on certain types of faults, and their performances are highly correlated with the networks they work with. The network administrators feel difficult in measuring the effectiveness of their diagnosis approaches and choosing appropriate tools so as to meet the reliability demand. In this work, we introduce the D-vector to characterize the property of a diagnosis approach. The D-vector has five dimensions, namely the degree of coupling, the granularity, the overhead, the tool reliability and the network reliability, quantifying and evaluating the effectiveness of current diagnostic tools in certain applications. We employ a skyline query algorithm to find out the most effective diagnosis approaches, i.e., skyline points (SPs), from five dimensions of all potential D-vectors. The selected skyline D-vector points can further guide the design of various diagnosis approaches. In our trace-driven simulations, we design and select tailored diagnostic tools for GreenOrbs, achieving high performance with relatively low overhead.

LINKORD: link ordering-based data gathering protocol for wireless sensor networks

With respect to the multi-hop communication pattern of wireless sensor networks, all the nodes should establish multi-hop paths towards a common data gathering point to provide a data gathering service for the underlying applications. Although data gathering protocols provide a simple service, these protocols suffer from poor performance in practice due to the power constraints of low-power sensor nodes and unreliability of wireless links. Existing data gathering protocols rely on the ETX metric to find high-throughput paths through assuming there is an infinite number of transmission attempts at the link layer for delivering a single packet over every link. However, in practice the link layer provides a bounded number of transmissions per packet over individual links. Therefore, employing existing data gathering protocols in these situations may result in the construction of the paths that require more than maximum number of provided link layer transmissions for delivering a single packet over each link. In this regard, we propose a path cost function which considers the limitation on the number of provided link layer transmissions and relative position of the links along the paths according to their data transmission probability. Furthermore, we introduce a data gathering protocol which uses the proposed path cost function to construct high-throughput paths. Moreover, this protocol employs a newly designed congestion control mechanism during the data transmission process to provide energy-efficient and high-throughput data delivery. The simulation results show that, the proposed protocol improves data delivery ratio by 70 % and network goodput by 80 %, while it reduces the consumed energy for data delivery by 50 % compared to the default data gathering protocol of TinyOS.

Joint Design of Asynchronous Sleep-Wake Scheduling and Opportunistic Routing in Wireless Sensor Networks

Designing a lifetime-maximization routing in wireless sensor networks poses a great challenge mainly due to unreliable wireless links and limited power supply. Recently, two natural advantages of opportunistic routing, i.e., path diversity and the improvement of transmission reliability, are exploited to develop a lifetime-extended opportunistic routing for wireless sensor networks. Besides, asynchronous sleep-wake scheduling is an effective mechanism to reduce energy consumption by appropriately arranging sensor nodes to sleep. Hence, in this paper, we propose a joint design of asynchronous sleep-wake schedules and opportunistic routing, called ASSORT, to maximize the network lifetime. Simulation results show that ASSORT effectively achieves network lifetime extension compared with other routing schemes.

A SURVEY ON DIFFERENT CROSS-LAYER ATTACKS AND THEIR DEFENSES IN MANETS

A Mobile ad hoc network (MANET) is a self-configuring network that has no infrastructure. Each device in a MANET is free to move independently in any direction and will therefore change its links to other devices frequently. It is an emerging technology that has the potential to be applied in applications like battlefields and also in many commercial applications. With great features MANET also has some limitations like unreliability of wireless links, constantly changing topologies and more. Due to this vulnerable nature of MANET, they are exposed to various security threats that cause problems in using them. The attackers takes advantage of these vulnerabilities to launch various kinds of security attacks on MANETs. Among the security attacks, the attack of most concern is Cross-layer attack that initializes at MAC layer and launches attack on routing layer which causes serious degradation in network performance. This attack emerges from lack of interaction between MAC and routing layer. In this paper, we focus on surveying various Cross-layer attacks that were discovered till now and their defense systems. Finally we highlight what could be done in future to improve the defense systems.