Mobile telemedicine sensor networks with low-energy data query and network lifetime considerations

In this paper, we use an integrated architecture that takes advantage of the low cost mobile sensor networks and 3G cellular networks to accommodate multimedia medical calls with differentiated Quality-of-Service (QoS) requirements. We propose a low-energy, distributed, and concentric-zone-based data query mechanism that takes advantages of hierarchical ad hoc routing algorithms to enable a medical specialist to collect physiological data from mobile and/or remote patients. The medical specialist uses cellular network to report patients' data to the medical center. Moreover, we propose a transmission scheme among different zones with balance-based energy efficiency, which can extend network lifetime. We evaluate the validity of our proposals through simulations and analyze their performance. Our results clearly indicate the energy efficiency of the proposed sensor network query algorithms and the efficiency of our multiclass medical call admission control scheme in terms of meeting the multimedia telemedicine QoS requirements.     

The integration of ad hoc sensor and cellular networks for multi-class data transmission

This paper targets mobile telemedicine applications that can be supported using third generation (3G) cellular networks, to provide highly flexible medical services. On the other hand, large-scale Ad hoc Sensor Networks (ASN), when deployed among mobile patients who may carry different kinds of micro-sensors to measure ECG, blood pressure, basal temperature or other physiological data, can provide a dynamic data query architecture to allow the medical specialists to monitor patients at any place. So far very little research has been conducted to explore the possibility of integrating ASN with mobile telemedicine. In this paper: 1. we suggest an integrated architecture that takes advantage of the low cost mobile sensor networks and 3G cellular networks to support multimedia medical calls with differentiated Quality-of-Service (QoS) requirements. 2. We propose a low-energy, distributed, concentric-zone-based data query mechanism that has the advantages of both proactive and reactive ad hoc routing algorithms to collect medical results from large-scale mobile patients for medical specialists who use cellular network to report patient data to the medical center. 3. In order to minimize the ambulance wireless call-dropping rate, we adopt accurate resource reservation call admission control (CAC) scheme to allocate the necessary bandwidth in the destination cell. 4. In order to meet the QoS requirements of patients’ wireless calls, we use dynamic guard channel CAC scheme to keep their handoff-call dropping rate below a certain threshold. We evaluate the validity of our schemes through simulations and analyze their performance. Our results clearly indicate the efficiency of the proposed CAC and sensor network query algorithms to meet the multimedia telemedicine QoS requirements.     

Call admission control for QoS provisioning in 4G wireless networks: issues and approaches

This article presents a survey on the issues and the approaches related to designing call admission control schemes for fourth-generation wireless systems. We review the state of the art of CAC algorithms used in the traditional wireless networks. The major challenges in designing the CAC schemes for 4G wireless networks are identified. These challenges are mainly due to heterogeneous wireless access environments, provisioning of quality of service to multiple types of applications with different requirements, provisioning for adaptive bandwidth allocation, consideration of both call-level and packet-level performance measures, and consideration of QoS at both the air interface and the wired Internet. To this end, architecture of a two-tier CAC scheme for a differentiated services cellular wireless network is presented. The proposed CAC architecture is based on the call-level and packet-level QoS considerations at both the wireless and wired parts of the network. A performance analysis model for an example CAC scheme based on this architecture is outlined, and typical numerical results are presented.     

Network coding and competitive approach for gradient based routing in wireless sensor networks

Energy efficiency is a key design criterion for routing protocols in wireless sensor networks since sensor nodes are strongly constrained in terms of energy supply. Gradient-Based Routing (GBR) is a well known energy efficient routing protocol that is used in WSNs. However, there exist shortcomings in the GBR scheme such as: (1) sinks make use of flooding to broadcast interest messages which leads to a lot of duplication packets which are transmitted. This leads to the waste of a lot of energy in the network and (2) nodes deliver messages in a point to point manner. As a result, the potential of data retransmissions in the network is high due to the unstable network environment in WSNs. In this study, network coding and a competitive approach are proposed to solve the above two problems. Firstly, an energy efficient broadcast algorithm using network coding for GBR (GBR-NC) is proposed. This algorithm aims to reduce network traffic, and furthermore, reduce the energy consumption and prolong the lifetime of the network. Secondly, two competing algorithms (GBR-C and auto-adaptable GBR-C) are proposed for GBR. The basic idea of the proposed competing algorithms is to reduce the retransmission attempts and save the energy by considering two forward candidates. Simulation results show that the proposed schemes give better results when compared to the traditional GBR in terms of energy efficiency.     

Load balancing clustering and routing for IoT-enabled wireless sensor networks

Internet of things (IoT) devices are equipped with a number of interconnected sensor nodes that relies on ubiquitous connectivity between sensor devices to optimize information automation processes. Because of the extensive deployments in adverse areas and unsupervised nature of wireless sensor networks (WSNs), energy efficiency is a significant aim in these networks. Network survival time can be extended by optimizing its energy consumption. It has been a complex struggle for researchers to develop energy-efficient routing protocols in the field of WSNs. Energy consumption, path reliability and Quality of Service (QoS) in WSNs became important factors to be focused on enforcing an efficient routing strategy. A hybrid optimization technique presented in this paper is a combination of fuzzy c-means and Grey Wolf optimization (GWO) techniques for clustering. The proposed scheme was evaluated on different parameters such as total energy consumed, packet delivery ratio, packet drop rate, throughput, delay, remaining energy and total network lifetime. According to the results of the simulation, the proposed scheme improves energy efficiency and throughput by about 30% and packet delivery ratio and latency by about 10%, compared with existing protocols such as Chemical Reaction Approach based Cluster Formation (CHRA), Hybrid Optimal Based Cluster Formation (HOBCF), GWO-based clustering (GWO-C) and Cat Swarm Optimization based Energy-Efficient Reliable sectoring Scheme with prediction algorithms (P_CSO_EERSS). The study concludes that the protocol suitable for creating IoT monitoring system network lifetime is an important criteria.     

An energy‐efficient asynchronous wake‐up scheme for underwater acoustic sensor networks

In addition to the requirements of the terrestrial sensor network where performance metrics such as throughput and packet delivery delay are often emphasized, energy efficiency becomes an even more significant and challenging issue in underwater acoustic sensor networks, especially when long‐term deployment is required. In this paper, we tackle the problem of energy conservation in underwater acoustic sensor networks for long‐term marine monitoring applications. We propose an asynchronous wake‐up scheme based on combinatorial designs to minimize the working duty cycle of sensor nodes. We prove that network connectivity can be properly maintained using such a design even with a reduced duty cycle. We study the utilization ratio of the sink node and the scalability of the network using multiple sink nodes. Simulation results show that the proposed asynchronous wake‐up scheme can effectively reduce the energy consumption for idle listening and can outperform other cyclic difference set‐based wake‐up schemes. More significantly, high performance is achieved without sacrificing network connectivity. Copyright © 2015 John Wiley & Sons, Ltd.     

Time Synchronization Algorithms in Low-Cost Wireless Sensor Network Systems

Time synchronization is an essential building block of sensor network systems. In this paper, we present a comprehensive study of least squares algorithms for time synchronization in sensor networks, with a focus on continuous monitoring and data collection applications. We propose a set of algorithms to address a number of issues in practical implementation on typical low-cost sensor network platforms, including a scaled signal model to achieve numerical stability in an ill-conditioned problem, sequential estimators for the scaled signal model to reduce computational complexity, a fast initialization scheme to improve energy efficiency, and outlier detection algorithms to improve robustness in long-term autonomous operations. The proposed algorithms are implemented and a measurement-based simulation method is employed to study the performance.     

Single-path routing for life time maximization in multi-hop wireless networks

Energy-aware routing is important in multi-hop wireless networks that are powered by battery, e.g., wireless sensor networks. To maximize the network survivability, the energy efficiency of paths must be taken into account for route selection. Simple heuristics such as choosing paths with minimal energy consumption are ineffective, because the energy of the nodes on such paths may deplete quickly. The issue is particularly serious for the networks with regular traffic pattern as in monitoring sensor applications. Existing solutions to this issue typically adopt the multi-path routing approach, in which multiple paths are set up between source and destination and one (or all) of the paths is (are) used at a certain moment. However, this approach involves high overhead for establishment and management of multiple paths. In this paper, we present a static single-path routing scheme which uses one energy-efficient path for each communicating peer throughout the network lifetime, eliminating the overhead of multi-path routing. It is theoretically proved that our routing scheme achieves a constant factor approximate of the optimal solution. We compare the performance of the proposed scheme with that of multi-path routing via simulations. Despite the use of single static path, the proposed scheme outperforms existing multi-path routing schemes and produces performance close to the optimal multi-path solution, particularly in heavily loaded networks and multiple-gateway networks.     

Optimal rate allocation and QoS-sensitive admission control in wireless integrated networks

The problem of Call Admission Control and rate allocation in loosely coupled wireless integrated networks is investigated. The related Radio Resource Management schemes were introduced to improve network performance in wireless integrated networks. However, these schemes did not reflect the independence and competitiveness of loosely coupled wireless integrated networks. Furthermore, given that users have different requirements for price and Quality of Service (QoS), they are able to select a network according to their preference. We consider a scenario with two competitive wireless networks, namely Universal Mobile Telecommunications System cellular networks and Wireless Local Area Networks. Users generate two types of traffic with different QoS requirements: real-time and non-real-time. We propose a scheme that exploits a mathematical model for the control of call admission and adopt a noncooperative game theory-based approach to address the rate allocation problem. The purpose is to maximize the revenue of the network providers while guaranteeing a level of QoS according to user needs. Simulation results show that the proposed scheme provides better network performance with respect to packet loss rate, packet delay time, and call-blocking probability than other schemes when the data rates are allocated to each call at the point that maximizes the revenue of network providers. We further demonstrate that a Nash equilibrium always exists for the considered games.     

Dynamic key management in sensor networks

Numerous key management schemes have been proposed for sensor networks. The objective of key management is to dynamically establish and maintain secure channels among communicating nodes. Desired features of key management in sensor networks include energy awareness, localized impact of attacks, and scaling to a large number of nodes. A primary challenge is managing the trade-off between providing acceptable levels of security and conserving scarce resources, in particular energy, needed for network operations. Many schemes, referred to as static schemes, have adopted the principle of key predistribution with the underlying assumption of a relatively static short-lived network (node replenishments are rare, and keys outlive the network). An emerging class of schemes, dynamic key management schemes, assumes long-lived networks with more frequent addition of new nodes, thus requiring network rekeying for sustained security and survivability. In this article we present a classification of key management schemes in sensor networks delineating their similarities and differences. We also describe a novel dynamic key management scheme, localized combinatorial keying (LOCK), and compare its security and performance with a representative static key management scheme. Finally, we outline future research directions.     

An Authenticated Identity-Based Key Establishment and Encryption Scheme for Wireless Sensor Networks

1Introduction Wirelesscommunicationhasbeenahotissuesince1990.includingAdhocandwirelesssensornetworks,etc.Especially,WirelessSensorNetwork(WSN).Whichhasreceivedconsiderableattentionduringlast decade[1-2].Ithasbeendevelopedforawidevarietyof applications,inc…     

Design and analysis of asynchronous wakeup for wireless sensor networks

In wireless sensor networks, scheduling the sleep duration of each node is one of the key elements for controlling critical performance metrics such as energy consumption and latency. Since the wakeup interval is a primary parameter for determining the sleeping schedule, how to tune the wakeup interval is crucial for the overall network performance. In this paper, we present an effective framework for tuning asynchronous wakeup intervals of IEEE 802.15.4 sensor networks from the energy consumption viewpoint. First, we derive an energy consumption model of each node as an explicit function of the wakeup interval, and empirically validate the derived model. Second, based on the proposed model, we formulate the problem of tuning the wakeup interval with the following two objectives: to minimize total energy consumption and to maximize network lifetime. We show that these two problems can be optimally solved by an iterative algorithm with global information by virtue of the convexity of the problem structure. Finally, as practical solutions, we further propose heuristic optimization algorithms that only exploit local information. In order to develop heuristic algorithms, we propose two broadcasting schemes, which are entitled as maximum wakeup interval broadcasting and efficient local maximum broadcasting. These broadcasting algorithms enable nodes in the network to have heterogeneous wakeup intervals.     

QoS in Wireless Multimedia Sensor Networks: A Layered and Cross-Layered Approach

The emergence of wireless multimedia sensor networks (WMSN) has given birth to several civilian as well as defense applications. Some of the interesting applications employing low cost sensor nodes to manipulate rich multimedia content include traffic monitoring, border surveillance, smart homes, environment and habitat monitoring. Unlike the traditional sensor networks which are aimed at maximizing network lifetime by decreasing energy utilization, the main objective of WMSNs is optimized delivery of multimedia content along with energy efficiency. Multimedia communications in WMSNs, has stringent delay and high bandwidth requirement as compared to scalar data transfer in WSNs. Fulfilling these constraints in resource and energy constrained WMSNs is a huge challenge. In WMSNs, each layer of the protocol stack is responsible and fully involved in providing QoS guarantees. There is a need for new schemes at each layer of the protocol stack- from advanced coding techniques that reduce encoder complexity and achieve maximum compression to dynamic routing and MAC protocols that provide service differentiation and reduce end-to-end latency. In wireless sensor networks, where all layers have dependency on each other, QoS guarantees are possible through the cross layer interaction of different layers. This paper gives an overview of the different existing layered schemes in WMSNs, followed by a discussion on the significance and efficiency gains that can be achieved from cross layer interactions in WMSNs along with the review of the existing cross layer approaches. Finally, we identify the open research issues which have not been adequately addressed so far.     

Study of an adaptive frame size predictor to enhance energy conservation in wireless sensor networks

Technological advances in low-power digital signal processors, radio frequency (RF) circuits, and micromechanical systems (MEMS) have led to the emergence of wirelessly interconnected sensor nodes. The new technological possibilities emerge when a large number of tiny intelligent wireless sensor nodes are combined. The sensor nodes are typically battery operated and, therefore, energy constrained. Hence, energy conservation is one of the foremost priorities in design of wireless sensor networks (WSNs) protocols. Limited power resources and bursty nature of the wireless channel are the biggest challenges in WSNs. Link adaptation techniques improve the link quality by adjusting medium access control (MAC) parameters such as frame size, data rate, and sleep time, thereby improving energy efficiency. In This work, our study emphasizes optimizing WSNs by building a reliable and adaptive MAC without compromising fairness and performance. Here, we present link adaptation techniques at MAC layer to enhance energy efficiency of the sensor nodes. The proposed MAC uses a variable frame size instead of a fixed frame size for transmitting data. In order to get accurate estimations, as well as reducing the computation complexity, we utilize the extended Kalman filter to predict the optimal frame size for improving energy efficiency and goodput, while minimizing the sensor memory requirement. Next, we designed and verified different network models to evaluate and analyze the proposed link adaptation schemes. The correctness of the proposed theoretical models have been verified by conducting extensive simulations. We also prototype the proposed scheme with the MAC protocol on Berkeley Motes. Both prototype and simulation results show that the proposed algorithms improve the energy efficiency by up to 15%.     

A new scheduling algorithm to provide proportional QoS in optical burst switching networks

A new scheduling algorithm, which aims to provide proportional and controllable QoS （Quality of Service） in terms of burst loss probability for OBS （Optical Burst Switching） networks, is proposed on the basis of a survey of QoS schemes in current OBS networks. With simulations, performance analysis and comparisons are carried out in detail. The results show that, in the proposed scheme, burst loss probabilities are proportional to the given factors and the control of QoS performance can be achieved with better performance. This scheme will be beneficial to the OBS network management and the tariffpolicy making.     

Performance enhancement of combining QoS provisioning and location management in wireless cellular networks

Quality-of-service (QoS) provisioning and location management (LM) in cellular networks are solved separately in previous work. For realistic network environments, we have proposed a framework of combining QoS provisioning and LM by using all available user mobility information. In this paper, we present performance evaluation to show that this framework can yield more efficient solutions for both. We propose a novel path-based LM scheme in this combined framework and evaluate the performance gain of the new scheme over the original path-based LM scheme by simulations. Further, we propose a new connection admission control (CAC) scheme derived from this combined framework for QoS provisioning and present results showing performance enhancements over CAC schemes proposed previously.     

Capacity Optimization in TDMA Ad-Hoc Networks

Many scheduling techniques have been developed to solve the problem of sharing the common channel to multiple stations. TDMA has been increasingly used as a scheduling technique in ad-hoc networks. The current trend for QoS capable applications led to the deployment of numerous routing schemes that use TDMA. These schemes try to solve the problem of distributing the available slots among the wireless nodes and at the same time, to find paths within the network that fulfill some QoS related limitations, such as end-to-end delay. The exact way the slots are distributed among the transmitting nodes has an impact on the end-to-end delay and other performance parameters of the network, such as capacity. Therefore, the efficiency of the scheduling algorithms is closely related to the network topologies. In this paper, we propose two new end-to-end TDMA scheduling algorithms that try to enhance the network capacity by increasing the number of concurrent connections established in the network, without causing additional end-to-end delay. We study the efficiency of the proposed algorithms, when applied on various random topologies, and compare them in terms of end-to-end delay and network capacity.     

On the performance and fairness of dynamic channel allocation in wireless mesh networks

Channel assignment in multichannel multiradio wireless mesh networks is a powerful resource management tool to exploit available multiple channels. Channels can be allocated either statically on the basis of long‐term steady state behavior of traffic or dynamically according to actual traffic demands. It is a common belief that dynamic schemes provide better performance; however, these two broad classes of channel allocation schemes have not been compared in detail. In this paper, we quantify the achievable performance gain and fairness improvement through an optimal dynamic channel allocation scheme. We develop optimal algorithms for a dynamic and three static schemes using mixed integer linear programming and compare them in the context of QoS provisioning, where network performance is measured in terms of acceptance rate of QoS sensitive traffic demands. Our extensive simulations show that static schemes should optimize channel allocation for long‐term traffic pattern and maintain max–min fairness to achieve acceptable performances. Although the dynamic and max–min fair static schemes accomplish the same fairness, the dynamic channel allocation outperforms the static scheme about 10% in most cases. In heavily overloaded regimes, especially when network resources are scarce, both have comparable performances, and the max–min fair scheme is preferred because it incurs less overhead. Copyright © 2011 John Wiley & Sons, Ltd.     

基于聚类的无线传感网络的合作MIMO传输方案

Wireless sensor network is becoming more and more popular in recent years, but energy-constrained characteristic of sensor nodes is one of the critical issues that we must consider in system design. In this paper, a cluster-based virtual V-BLAST transmission scheme is proposed to achieve energy savings for energy-constrained wireless sensor networks. In the proposed scheme, instead of using cluster member as cooperative nodes, multiple cluster heads cooperate to form virtual antenna array so that V-BLAST based virtual MIMO transmission can be implemented. Based on the communication energy consumption model, a way to optimize the parameters for the scheme is given. In addition, detailed simulation is performed to evaluate the performance of the proposed scheme for both densely and sparsely deployed sensor networks. Theoretical analysis and simulation results verify the energy efficiency of the proposed scheme.     

DEICA: A differential evolution-based improved clustering algorithm for IoT-based heterogeneous wireless sensor networks

With the evolution of technology, many modern applications like habitat monitoring, environmental monitoring, disaster prediction and management, and telehealth care have been proposed on wireless sensor networks (WSNs) with Internet of Things (IoT) integration. However, the performance of these networks is restricted because of the various constraints imposed due to the participating sensor nodes, such as nonreplaceable limited power units, constrained computation, and limited storage. Power limitation is the most severe among these restrictions. Hence, the researchers have sought schemes enabling energy-efficient network operations as the most crucial issue. A metaheuristic clustering scheme is proposed here to address this problem, which employs the differential evolution (DE) technique as a tool. The proposed scheme achieves improved network performance via the formulation of load-balanced clusters, resulting in a more scalable and adaptable network. The proposed scheme considers multiple parameters such as nodes' energy level, degree, proximity, and population for suitable network partitioning. Through various simulation results and experimentation, it establishes its efficacy over state-of-the-art schemes in respect of load-balanced cluster formation, improved network lifetime, network resource utilization, and network throughput. The proposed scheme ensures up to 57.69%, 33.16%, and 57.74% gains in network lifetime, energy utilization, and data packet delivery under varying network configurations. Besides providing the quantitative analysis, a detailed statistical analysis has also been performed that describes the acceptability of the proposed scheme under different network configurations.