Cooperative Communications in Resource-Constrained Wireless Networks

Wireless industrial sensor networks are wireless sensor networks which have been adapted to industrial applications. Most techniques for wireless sensor networks can be applied to wireless industrial sensor networks. However, for industrial applications of wireless industrial sensor networks, new requirements such as real-time, reliable delivery need to be considered. In this paper, we propose EARQ, which is a novel routing protocol for wireless industrial sensor networks. It provides real-time, reliable delivery of a packet, while considering energy awareness. In EARQ, a node estimates the energy cost, delay and reliability of a path to the sink node, based only on information from neighboring nodes. Then, it calculates the probability of selecting a path, using the estimates. When packet forwarding is required, it randomly selects the next node. A path with lower energy cost is likely to be selected, because the probability is inversely proportional to the energy cost to the sink node. To achieve real-time delivery, only paths that may deliver a packet in time are selected. To achieve reliability, it may send a redundant packet via an alternate path, but only if it is a source of a packet. Experimental results show that EARQ is suitable for industrial applications, due to its capability for energy efficient, real-time, reliable communications.

Virtual multi-input multi-output (MIMO) or vMIMO is becoming an attractive technology to achieve spatial diversity in wireless networks without using additional antennas, and to reduce power consumption by cooperation among multiple nodes. As data gathering is one of the most important operations in many sensor network applications, this paper studies energy-efficient data gathering in wireless sensor networks using vMIMO. We define the joint vMIMO and data gathering (vMDG) problem, which is NP-hard. We also propose a distributed method called D-vMDG as an approximation algorithm. This algorithm first constructs a tree-like topology by taking the unique features of vMIMO into account. Then, an energy-efficient routing protocol based on dynamic programming is proposed for each node on the constructed topology. Our theoretical analysis shows that D-vMDG can achieve an approximation ratio of O(1). Our simulations show that D-vMDG decreases the energy consumption by 81 and 36 percent compared to the well-known MDT [26] and MIMO-LEACH [19] algorithms respectively.

Monitoring and automatic control of building environment is a crucial application of Wireless Sensor Network (WSN) in which maximizing network lifetime is a key challenge. Previous research into the performance of a network in a building environment has been concerned with radio propagation within a single floor. We investigate the link quality distribution to obtain full coverage of signal strength in a four-storey building environment, experimentally. Our results indicate that the transitional region is of particular concern in wireless sensor network since it accommodates high variance unreliable links. The transitional region in a multi-storey building is mainly due to the presence of reinforced concrete slabs at each storey and the fac┬©ade which obstructs the radio signal and introduces an additional absorption term to the path loss.

Ultra-wideband (UWB) radio communication sys- tems operate using extremely short duration base-band pulses. This paper compares the performance of three competing multi- ple access modulation schemes that have been proposed for appli- cation to UWB based wireless sensor networks. These multiple access schemes are ultra-wideband Time-Hopping (TH-UWB), Direct Sequence Spread Spectrum (DSSS-UWB) and Orthogonal Frequency Division Multiplexing (OFDM-UWB). Each system was investigated under four operating conditions of different bandwidths and bit rates for three different transmission ranges. The attributes measured to compare the performance of the multiple access schemes under consideration were packet link error rate, throughput and energy efficiency. TH-UWB outper- forms DSSS-UWB and OFDM-UWB for high bandwidth condi- tions. Whereas, DSSS-UWB performs better in low bandwidth conditions compared to the other two systems. Decreasing the transmission range significantly degrades the overall performance of the systems. I. INTRODUCTION Wireless sensor networks are special networks composing of a large number of inexpensive, low-power communication sensing devices (sensor nodes), which are densely deployed throughout a physical space and have the capability of col- laborating with each other to monitor a wide variety of ambient conditions. Realisation of sensor network applications requires wireless ad hoc networking techniques (1), therefore the sensor nodes are deployed in an ad hoc fashion and are required to organize themselves to form a multi-hop wireless communication network. Efficient and reliable communication between multiple sen- sor network entities is a big challenge. The increased collision probability resulting from multiple sensor nodes transmitting data simultaneously over the same transmission medium is a common problem facing communication in wireless networks. This problem can be overcome by using reliable multiple access techniques. An ideal wireless sensor communication network would require a multiple access scheme that allows the accommodation of multiple users and provides effective communication. It must also offer some measure of security and should have low probability of intercept. It should also be resistant to jamming and must be energy efficient. Ultra-wideband (UWB) radio is an emerging technology that operates using extremely short duration base-band pulses and has a number of advantages that makes it an attractive choice for sensor networks. In particular, UWB systems have low power and low complexity. They have a noise like signal and are therefore resistant to severe multipath and jamming. They also provide greater bandwidth and are more cost ef- fective for providing increased throughput without increasing power. The three approaches to multiple access in UWB are:

Problem statement: The Wireless Body Area Sensor Networks (WBASNs) is a wireless network used for communication among sensor nodes operating on or inside the human body in order to monitor vital body parameters and movements. This study surveys the state-of-the-art on Wireless Body Area Networks, discussing the major components of research in this area including physiological sensing and preprocessing, WBASNs communication techniques and data fusion for gathering data from sensors. In addition, data analysis and feedback will be presented including feature extraction, detection and classification of human related phenomena. Approach: Comparative studies of the technologies and techniques used in such systems will be provided in this study, using qualitative comparisons and use case analysis to give insight on potential uses for different techniques. Results and Conclusion: Wireless Sensor Networks (WSNs) technologies are considered as one of the key of the research areas in computer science and healthcare application industries. Sensor supply chain and communication technologies used within the system and power consumption therein, depend largely on the use case and the characteristics of the application. Authors conclude that Life-saving applications and thorough studies and tests should be conducted before WBANs can be widely applied to humans, particularly to address the challenges related to robust techniques for detection and classification to increase the accuracy and hence the confidence of applying such techniques without physician intervention.

Wireless network of wearable biomedical sensors by human body shows great potential to enhance the biometrics performance significantly. Meanwhile, it poses prominent characteristics and challenges to physicians and engineers for its particular medical application as compared to other application of wireless sensor networks (WSN). Mobility pattern plays an important role in designing the wireless body sensor networks (WBSN) and will also affect the accuracy of modeling WBSN in health care application. Much of the mobility scenarios generated in current work of wireless body sensor networks has used fairly simple models to generate the mobile topological graph, which bear little resemblance to the actual mobility patterns. This paper is the first attempt to investigate the mobility model in WBSN based on the existing mobility models in wireless data networks and ad hoc networks. We first briefly review the existing mobility models in related research areas such as wireless ad hoc network and cellular networks. Further on, we propose a dedicated and more realistic mobility model named BAMM (Body Area Mobility Model) for wireless body sensor networks by concentrating on the unique characteristics of WBSN and finally study the effects of mobility on the performance of WBSN by simulation experiments.

Co-operative communication has been shown to significantly improve energy efficiency in wireless sensor networks. The outdated channel state information (CSI) problem will result in severe performance degradation of co-operative communication systems including energy efficiency. In this study, the authors analyse the impact of outdated CSI on energy efficiency of amplify-and-forward co-operative hybrid automatic repeat reQuest system. The authors derive the expression of the average energy consumption per bit of data transmission under outdated CSI. Numerical results show the deteriorating effects of outdated CSI on the performance of energy efficiency and transmission reliability in co-operative communication system. It is also shown that energy efficiency can be improved by error correcting codes mechanism when end-to-end signal-to-noise ratio at the destination node is within a certain range.

Error control coding improves reliability and efficiency of wireless communication systems. This research delves into the latest advancements in error control coding schemes for wireless communication systems, with a specific focus on their application within the domain of Low Power Wide Area Networks (LPWANs) such as Narrowband Internet of Things (NB-IoT) systems, LoRa energy-efficient hardware design, random access control systems, and wireless sensor networks. In the context of LPWANs, particularly NB-IoT systems, we investigate the adaptive coding and modulation (ACM) in NB-IoT systems, which adapts coding rates and modulation techniques to changing channel circumstances. Comprehensive analysis of the literature review shows that the proposed approaches are more energy efficient and less error-prone than fixed coding and modulation schemes. Using Cell Design Methodology (CDM), Single Error Correction (SEC) codes are optimized for energy efficiency. Power and energy efficiency have improved in standard CMOS and CDM logic systems. This impacts IoT devices, memory storage, and security systems. Next, Forward Error Correction (FEC) is examined for ALOHA-based random-access control systems wherein packet loss rate and spectral efficiency metrics are mathematically calculated. FEC is beneficial, especially when time and frequency synchronization diverge. Monte Carlo simulations studied in the literature shows that FEC improves satellite communication systems. This review establishes benefits of FEC, notably in satellite communications systems. In addition, Wireless Sensor Networks (WSNs) error control techniques and network reliability and performance are examined along with Convolutional, Turbo, Low density parity check codes(LDPC), and Polar error correction coding (ECC) methods. We learn about their benefits, drawbacks, and implementation challenges by assessing their efficacy, efficiency, and applicability in wireless sensor networks (WSN) applications. This study further highlights advancements of energy-efficient error control coding when, integrated into network designs alongwith the trade-offs between efficacy and intricacy to help improve wireless communication networks. Finally, this study summarizes current error control coding approaches for wireless communication systems. We provide insights into improving reliability, energy conservation, and efficacy by examining ACM, CDM, FEC, and error correction coding (ECC) across varied domains including LPWAN and IoT technologies with earnest hope to facilitate researchers, engineers, and professionals working in the field of error control coding in wireless communication.

This paper presents the `Generalized Poor Man's SIMO System' (gPMSS) which combines two approaches, cooperative communication and diversity combination, to reduce packet losses over links in wireless sensor networks. The proposed gPMSS is distinct from previous cooperative communication architectures in wireless sensor networks which rely on a relay channel, and also distinct from implementations in 802.11 networks that require a wired infrastructure or hardware changes for cooperation. gPMSS foregoes the need for any changes to mote hardware and it works within the current IEEE 802.15.4 standard. We describe the gPMSS protocol that governs the cooperation between receivers. Three variants are evaluated including selection diversity, equal gain and maximal ratio combining. First, we demonstrate gPMSS on bit error traces in a fully reproducible manner. This is followed by an implementation of gPMSS in C# on the .NET Micro Framework edition of the recently released Imote2 mote platform. We demonstrate by means of experiments an increase in the packet reception rate from 22---30% to 73---76%, a relative increase of 150---245%. We also analyzed the power consumed by the transmitter per delivered packet and observe a reduction of up to 68%. We also take into account the retry limit of the IEEE 802.15.4 protocol and demonstrate that gPMSS is able to provide 99% packet delivery at the protocol's default retry parameters against 65---75% without it.

A Wireless sensor network (WSN) comprises several sensor nodes such as magnetic, thermal, and infrared, and the radar is set up in a particular geographical area. The primary aim of sensor network is to transmit reliable, secure data from one node to another node, node to base station and vice versa and from base station to all nodes in a network and to conserve the energy of sensor nodes. On the other hand, there are several restrictions such as large energy consumption, limited storage/memory and processing ability, higher latency, and insufficient resources. The related security issues in wireless sensor network are authenticity, confidentiality, robustness, integrity, and data freshness. The sensor nodes are susceptible to several attacks such as DOS, Sybil, flood, black hole, selective forwarding which results in the leakage of sensitive and valuable information. It is therefore necessary to provide security against these critical attacks in the network. Wireless sensor network were earlier used for military applications with the objective of monitoring friendly and opposing forces, battlefield surveillance, detection of attacks, but today Wireless Networking have a huge number of applications-environmental, healthcare, home, industrial, commercial and are still counting. This paper is an extensive review of the security requirements, attacks that are to be avoided and resolved for achieving a secure network connection. This paper also emphasizes various limitations and defense strategies to prevent threats and attacks. The issues of applications of wireless sensor network for smooth and reliable transmissions are also discussed. The sensor networks are popular for mission-critical-tasks and security is immensely required for such hostile environment employed networks.

A series of challenges exist in the process of sensor network research which can not be solved by one sensor node. Cooperative communication, based on the idea of spatial diversity, which makes different users or nodes in wireless network share their antennas or other network resources, is a promising technique toward improving performance of wireless sensor network significantly. This article adopts cooperation between nodes and opportunistic collaboration transmission strategy is proposed. Energy efficient power allocation algorithm in wireless sensor network is put forward to optimize performance of opportunistic cooperative transmission. Through the simulation, regardless of statistical feature of channel state of opportunistic node, opportunistic cooperation can effectively improve the performance of the system. Using energy efficient power allocation algorithm can effectively reduce energy consumption of the network and improve the network performance

Data gathering is a fundamental operation for various applications of wireless sensor networks (WSNs), where sensor nodes sense information and forward data to a sink node via multihop wireless communications. Typically, data in a WSN is relayed over a tree topology to the sink for effective data gathering. A number of tree-based data gathering schemes have been proposed in the literature, most of which aim at maximizing network lifetime. However, the timeliness and reliability of gathered data are also of great importance to many applications in WSNs. To achieve low-latency, high-reliability data gathering in WSNs, in this paper, we construct a data gathering tree based on a reliability model, schedule data transmissions for the links on the tree and assign transmitting power to each link accordingly. Since the reliability of a link is highly related to its signal to interference plus noise ratio (SINR), the SINR of all the currently used links on the data gathering tree should be greater than a threshold to guarantee high reliability. We formulate the joint problem of tree construction, link scheduling and power assignment for data gathering into an optimization problem, with the objective of minimizing data gathering latency. We show the problem is NP-hard and divide the problem into two subproblems: Construction of a low-latency data gathering tree; Jointly link scheduling and power assignment for the data gathering tree. We then propose a polynomial heuristic algorithm for each subproblem and conduct extensive simulations to verify the effectiveness of the proposed algorithms. Our simulation results show that the proposed algorithms achieve much lower data gathering latency than existing data gathering strategies while guaranteeing high reliability.

Data gathering is a fundamental operation in various applications of wireless sensor networks (WSNs), where sensor nodes sense information and forward data to a sink node via multi-hop wireless communications. Typically, data in a WSN is relayed over a tree topology to the sink for effective data gathering. A number of tree-based data gathering schemes have been proposed in the literature, most of which aim at maximizing network lifetime. However, the timeliness and reliability of gathered data are also of great importance to many applications in WSNs. To achieve low-latency, high-reliability data gathering in WSNs, in this paper, we construct a data gathering tree based on a reliability model, schedule data transmissions for the links on the tree and assign transmitting power to each link accordingly. Since the reliability of a link is highly related to its signal to interference plus noise ratio (SINR), the SINR of all the currently used links on the data gathering tree should be greater than a threshold to guarantee high reliability. We formulate the joint problem of tree construction, link scheduling and power assignment for data gathering into an optimization problem, with the objective of minimizing data gathering latency. We show the problem is NP-hard and divide the problem into two subproblems: Constructing a low-latency data gathering tree; Jointly link scheduling and power assignment for the data gathering tree. We then propose a polynomial heuristic algorithm for each subproblem and conduct extensive simulations to verify the effectiveness of the proposed algorithms. Our simulation results show that the proposed algorithms achieve much lower data gathering latency than existing data gathering strategies while guaranteeing high reliability. Moreover, the algorithms also have a comparable energy efficiency and network lifetime to other algorithms.

Similar to many technological developments, wireless sensor networks have emerged from military needs and found its way into civil applications. Today wireless sensor networks has become a key technology for different kinds of smart environments and an intense research effort is currently underway to enable the application of wireless sensor networks for a wide range of industrial problems. Wireless networks are of a particular importance when a large number of sensor nodes have to be deployed and/or in hazardouse situations. The research field in this paper is supposed to be on this issue that a lot of these sensors are distributed randomly and just a few of them are aware of their position [e.g. by GPS]. The purpose is to determine the best way that allows all the nodes to find their position. This paper presents an effective geometric algorithm for localization. Result of implementation show that this algorithm can be a better substitution for current methods because of lower expense and simple implementation.

Data gathering is a major function of many applications in wireless sensor networks. The most important issue in designing a data gathering algorithm is how to save energy of sensor nodes while meeting the requirements of special applications or users. Wireless sensor networks are characterized by centralized data gathering, multi-hop communication and many to one traffic pattern. These three characteristics can lead to severe packet collision, network congestion and packet loss, and even result in hot-spots of energy consumption thus causing premature death of sensor nodes and entire network. In this paper, we propose a load balance data gathering algorithm that classifies sensor nodes into different layers according to their distance to sink node and furthermore, divides the sense zone into several clusters. Routing trees are established between sensor node and sink depending on the energy metric and communication cost. For saving energy consumption, the target of data aggregation scheme is adopted as well. Analysis and simulation results show that the algorithm we proposed provides more uniform energy consumption among sensor nodes and can prolong the lifetime of sensor networks.