Virtual MIMO-based cooperative communication for energy-constrained wireless sensor networks

An energy-efficient virtual multiple-input multiple-output (MIMO)-based communication architecture is proposed for distributed and cooperative wireless sensor networks. Assuming a space-time block coding (STBC) based MIMO system, the energy and delay efficiencies of the proposed scheme are derived using semi-analytic techniques. The dependence of these efficiency values on physical channel propagation parameters, fading coherence time and the amount of required training is also investigated. The results show that with judicious choice of design parameters the virtual MIMO technique can be made to provide significant energy and delay efficiencies, even after allowing for additional training overheads.     

一种实用的DF协作无线传感器网络跨层设计

针对前向译码（DF）协作无线传感器网络的特点和要求,探讨基于分集合并和差错控制两种技术的实用跨层设计方案。首先,研究支持DF中继协议的协作传感器网络在目的节点采用等增益合并（EGC）的检测方案。通过和传统的最大比合并（MRC）方案以及最近提出的协作MRC方案综合比较,说明等增益合并是一个具有良好性能的实用方案。然后,把物理层的EGC和数据链路层的自动请求重传（ARQ）结合起来,再进行系统分析。最后,基于EGC和截断ARQ提出一种实用跨层设计方案。     

Network lifetime maximization with cross-layer design in wireless sensor networks

This paper investigates a cross-layer design approach for minimizing energy consumption and maximizing network lifetime (NL) of a multiple-source and single-sink (MSSS) WSN with energy constraints. The optimization problem for MSSS WSN can be formulated as a mixed integer convex optimization problem with the adoption of time division multiple access (TDMA) in medium access control (MAC) layer, and it becomes a convex problem by relaxing the integer constraint on time slots. Impacts of data rate, link access and routing are jointly taken into account in the optimization problem formulation. Both linear and planar network topologies are considered for NL maximization (NLM). With linear MSSS and planar single-source and single-sink (SSSS) topologies, we successfully use Karush-Kuhn-Tucker (KKT) optimality conditions to derive analytical expressions of the optimal NL when all nodes are exhausted simultaneously. The problem for planar MSSS topology is more complicated, and a decomposition and combination (D&C) approach is proposed to compute suboptimal solutions. An analytical expression of the suboptimal NL is derived for a small scale planar network. To deal with larger scale planar network, an iterative algorithm is proposed for the D&C approach. Numerical results show that the upper-bounds of the network lifetime obtained by our proposed optimization models are tight. Important insights into the NL and benefits of cross-layer design for WSN NLM are obtained.     

QoSMOS: cross-layer QoS architecture for wireless multimedia sensor networks

Wireless multimedia sensor networks (WMSNs), having inherent features and limited resources, require new quality of service (QoS) protocols for real-time and multimedia applications. In this paper, we present a cross-layer QoS architecture (QoSMOS), that unifies network and link layers into a single communication module for QoS provisioning. Based on QoSMOS architecture, we developed an example reference cross-layer protocol, named cross-layer communication protocol (XLCP), enabling scalable service differentiation in WMSNs. Comprehensive analysis of simulation results indicate that the proposed architecture successfully differentiates service classes in terms of soft delay, reliability and throughput domains. A comparative analysis of XLCP and its counterparts is also given to show the superiority of the cross-layer protocol.     

An integrated cross-layer study of wireless CDMA sensor networks

In this paper, we characterize analytically the multiaccess interference in wireless code-division multiple-access sensor networks with uniformly random distributed nodes and study the tradeoff between interference and connectivity. To provide a guideline for improving system behavior, three competitive deterministic topologies are evaluated along with the random topology in terms of link-level and network-level (routing) performance. The impact of signature code length and receiver design on the network performance for different topologies is also studied.     

Prolonging the lifetime of wireless sensor networks by cross-layer interaction

This article presents a cross-layered approach for networking in wireless sensor networks. WSNs differ greatly from traditional ad hoc wireless networks and therefore require the use of new types of network protocols that are energy-efficient to ensure a node lifetime of several years on a single battery and can operate without assistance of central managers in a dynamic network topology. We show that a tightly integrated set of networking protocols is a good solution to reach the target of highly energy-efficient WSNs. Our approach combines medium access organization with routing.     

Upstream congestion control in wireless sensor networks through cross-layer optimization

Congestion in wireless sensor networks not only causes packet loss, but also leads to excessive energy consumption. Therefore congestion in WSNs needs to be controlled in order to prolong system lifetime. In addition, this is also necessary to improve fairness and provide better quality of service (QoS), which is required by multimedia applications in wireless multimedia sensor networks. In this paper, we propose a novel upstream congestion control protocol for WSNs, called priority-based congestion control protocol (PCCP). Unlike existing work, PCCP innovatively measures congestion degree as the ratio of packet inter-arrival time along over packet service time. PCCP still introduced node priority index to reflect the importance of each sensor node. Based on the introduced congestion degree and node priority index, PCCP utilizes a cross-layer optimization and imposes a hop-by-hop approach to control congestion. We have demonstrated that PCCP achieves efficient congestion control and flexible weighted fairness for both single-path and multi-path routing, as a result this leads to higher energy efficiency and better QoS in terms of both packet loss rate and delay.     

Multi-hop wireless backhaul networks: a cross-layer design paradigm

Multihop wireless backhual networks are emerging as a cost-effective solution to provide ubiquitous and broadband access to meet the rapidly increasing demands of multimedia applications. In this paper, we consider the joint optimal design of routing, medium access control (MAC) scheduling and physical layer resource allocation for such networks, where beamforming antenna arrays are equipped at the physical layer. The notion of transmission set (TS) is introduced to separate the physical layer operations from those at the upper layers; and a column generation approach is employed to efficiently identify the TSs. We then apply the dual decomposition method to decouple the routing and scheduling subproblems, which are performed at different layers and are coordinated by a pricing mechanism to achieve the optimal overall system objective. To efficiently support multimedia traffic, an admission control criterion is considered for the system objective. The performance of the proposed scheme is verified by simulation results, and the impact of the physical layer capabilities on the network performance is evaluated. We also discuss the implementation issues of the cross-layer scheme based on the IEEE 802.16 mesh mode.     

UWB radio module design for wireless sensor networks

In this paper, we describe an impulse-based ultra wideband (UWB) radio system for wireless sensor network (WSN) applications. Different architectures have been studied for base station and sensor nodes. The base station node uses coherent UWB architecture because of the high performance and good sensitivity requirements. However, to meet complexity, power and cost constraints, the sensor module uses a novel non-coherent architecture that can autonomously detect the UWB signals. The radio modules include a transceiver block, a baseband processing unit and a power management block. The transceiver block includes a Gaussian pulse generator, a multiplier, an integrator and timing circuits. For long range applications, a wideband low noise amplifier (LNA) is included in the transceiver of the sensor module, whereas in short range applications it is simply eliminated to further reduce the power consumption. In order to verify the proposed system concept, circuit level implementation is studied using 1.5 V 0.18 μm CMOS technology. Finally, the UWB radio modules have been designed for implementation in liquid-crystal-polymer (LCP) based System-on-Package (SoP) technology for low power, low cost and small size integration. A small low cost, double-slotted, Knight’s helm antenna is embedded in the LCP substrate, which shows stable characterization and a return loss better than ?10 dB over the UWB band.     

一种新型无线传感网数据链接层的设计

介绍了无线传感网络的数据链接层构造体系,并详细地描绘了它的要求条件和功能特点,讨论了不同的子系统间的相互关系。设计的这种数据链接层消耗的能量极低,且结构简单、性能优越,系统不需要全球同步。     

无线传感器网络节点应用的硬件设计

针对无线传感器网络技术引入到矿下安全监测中,首先分析了无线传感器网络的结构、特点及研究重点,提出了无线传感器网络节点的整体设计方案.介绍了传感器的选择和处理器、通信器件的选择,并将硬件分为数据采集单元、数据处理单元和数据传输单元进行详细的说明.     

The design space of wireless sensor networks

In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics. As a consequence, it is becoming increasingly difficult to discuss typical requirements regarding hardware issues and software support. This is particularly problematic in a multidisciplinary research area such as wireless sensor networks, where close collaboration between users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. In this article we discuss the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions. We justify our view by demonstrating that specific existing applications occupy different points in the design space.     

A design for secure and survivable wireless sensor networks

In this article, we present a study of the design of secure and survivable wireless sensor networks (WSN) that has yet to be addressed in the literature. Our goal is to develop a framework that provides the security and survivability features that are crucial to applications in a WSN, because WSNs are vulnerable to physical and network-based security attacks, accidents, and failures. To achieve such a goal, we first examine the security and survivability requirements. We then propose a security and survivability architecture in a WSN with heterogeneous sensor nodes. To understand the interactions between survivability and security, we also design and analyze a key management scheme. The results of the experiment show that a good design can improve both security and survivability of a WSN; however, in some situations, there is a trade off between security and survivability.     

Integrated low-power communication system design for wireless sensor networks

Wireless sensor network systems are now being applied by an international community for critical applications in commerce, healthcare, and security. These systems have unique characteristics and face many implementation challenges. Among all, the requirement of long operating life for a wireless sensor node under limited energy supply imposes the most severe design constraints. This calls for innovative design methodologies to address this rigorous requirement. This article first provides an overview of wireless technologies for sensor networks. It then describes communication system, circuit design, and system packaging considerations. The selection of radio architectures and circuit techniques is discussed with an emphasis on the low-power implementation and operating characteristics that match requirements of sensor network application. Finally, the design, implementation, and performance of the most challenging component, a complete low-power CMOS receiver system, is presented to demonstrate these design principles.     

Enhanced performance based on cross-layer design from physical to transport layers for multihop wireless networks

This paper puts forward a novel cognitive cross-layer design algorithms for multihop wireless networks optimization across physical,mediam access control(MAC),network and transport layers.As is well known,the conventional layered-protocol architecture can not provide optimal performance for wireless networks,and cross-layer design is becoming increasingly important for improving the performance of wireless networks.In this study,we formulate a specific network utility maximization(NUM)problem that we believe is appropriate for multihop wireless networks.By using the dual algorithm,the NUM problem has been optimal decomposed and solved with a novel distributed cross-layer design algorithm from physical to transport layers.Our solution enjoys the benefits of cross-layer optimization while maintaining the simplicity and modularity of the traditional layered architecture.The proposed cross-layer design can guarantee the end-to-end goals of data flows while fully utilizing network resources.Computer simulations have evaluated an enhanced performance of the proposed algorithm at both average source rate and network throughput.Meanwhile,the proposed algorithm has low implementation complexity for practical reality.     

仿真研究无线多跳网络跨层协议设计的优劣

为了改善无线多跳网络的性能，很多研究表明跨层协议设计比OSI模型更适合无线网络。本文分析了无线多跳网络的特征及对各协议层的影响，给出了跨层协议设计对网络性能的改善以及它可能带来的问题，并针对速率自适应MAC协议和网络层路由协议之间的相互影响给出了仿真实例，结果证明跨层协议设计要充分考虑不同协议之间的相互影响，合理规划、谨慎实施，否则网络的性能不升反降。     

无线通信中跨层设计的研究

为了适应下一代通信系统的需求,需要对无线网络资源进行科学的整体管理,提出了跨层设计这种新的系统优化方法。文中通过对各类跨层设计的分析、对跨层优化步骤的阐述和对跨层优化实现方法的描述,打破传统分层设计中层的界限,对物理层、数据链路层和应用层等参数进行联合优化,获得各种通信性能指标之间的平衡,使总体通信性能最优。分析和仿真结果表明,在一般信道信噪比的情况下,跨层设计对视频通信质量有明显的改善,峰值信噪比提高了0.6～1.0 dB。