分簇无线传感器网络动态时隙分配MAC协议

为降低大规模无线传感器网络的平均能耗,提出了一种基于动态分配的调度型无线传感器网络MAC协议（SDC-MAC）。该协议簇间使用FDMA方式分配无线信道,簇内通过TDMA方式给各个节点分配可变长的时隙。随着簇结构的变化,簇头通过时隙分配通知,对簇内节点的时隙分配进行动态调整,簇成员节点则根据控制信息进行休眠和唤醒。仿真结果显示,该算法有效地降低了网络的平均能耗,当网络流量高时还可降低平均数据包时延。     

一种基于预约的无线传感器网络MAC协议

无线传感器网络要求的能量高效,低延时,使得MAC协议的设计充满挑战。近来已经提出了很多基于簇的MAC协议,为减少冲突在簇内部采用TDMA方式来协调簇内各个节点的传输。提出了一种在采用簇结构的基础上,使用预约方式来发送数据的R-MAC（Reservation-MAC）协议。当争用节点少的时候,采用随机争用方式来预约数据的发送;在争用节点多的时候,采用时隙争用方式来预约数据的发送。分析表明,R-MAC能够有效地降低能耗和减少延迟。     

无线传感器网络中一种动态节能的MAC协议

媒体访问控制(MAC)协议是无线传感器网络的关键协议之一,它对无线传感网络的运行和性能具有重要的影响.针对基于簇的TDMA机制存在问题,文中提出了一个动态节能的DE-MAC协议,该协议能够根据簇成员节点数目和通信负载动态地分配成员节点的时隙,减少节点的空闲侦听时间.仿真结果表明,DE-MAC协议能够有效地提高信道的利用率和网络能量有效性.     

基于树状拓扑的无线传感器网络MAC协议研究

针对无线传感器网络中树状拓扑的竞争型MAC协议存在一定能耗瑕疵的问题,根据ACK包回馈失败概率与传感器节点问平均通信延迟等因素,给出了适用于树状拓扑并采用时钟门限机制的新型MAC协议,该协议能实现单向信息采集树中父节点的能效控制。理论分析与仿真结果均表明,该机制能减少通信过程中不必要的能量浪费,提高无线传感器网络的能量效率。     

一种基于分簇的无线传感器网络MAC协议

本文提出了一种基于分簇结构的无线传感器网络MAC协议.在基于层次式路由协议的分簇网络结构中,通过综合基于竞争和基于时分复用协议的优缺点,将时间划分为交替的随机访问和调度访问两个阶段,在随机访问阶段簇内节点采用CSMA/CA实现无线信道共享.在调度访问阶段,节点根据簇首分配的时隙实现数据无冲突通信.在簇与簇之间采用FDMA避免信道干扰实现网络的扩展.分析和仿真结果表明本协议在能量效率、时间同步和网络扩展上都有所改进.     

基于改进LEACH的多簇头分簇路由算法

为了降低无线传感器网络(WSN)的能耗,延长网络的生存周期,提出一种多簇头双工作模式的分簇路由算法.算法对低功耗自适应集簇分层(LEACH)协议作了以下改进:采用多簇头双工作模式来分担单簇头的负荷,以解决单簇头因能耗较大而过早消亡的问题;选举簇头时充分考虑节点位置和节点剩余能量,并应用粒子群优化(PSO)算法优化簇头的选举,以均衡网络内各节点的能耗;建立簇与簇之间的数据传输路由,以减少簇间通信的能耗.仿真结果表明,算法有效降低了网络的能耗,延长了网络的生存周期.     

无线传感器网络环境下基于事件 驱动应用的节能TDMA协议

媒质接入控制是无线传感器网络设计的关键问题之一.由于媒质接入控制协议直接控制着节点无线通信模块的活动,而无线通信模块是传感器节点能量消耗的主要来源,因此MAC协议节能效率的好坏将严重影响网络的性能.基于TDMA的MAC协议具有固有的节能特性,即通过合理的TDMA调度避免传输碰撞以及减少节点空闲监听的时间.本文提出了ED-TDMA协议,一种面向事件驱动的传感器网络应用的TDMA协议.该协议根据当前源节点的数目动态地改变TDMA帧的长度,提高了信道利用率;同时采用位图方式的TDMA调度,极大地减少了TDMA调度的开销,节约了能量.此外,通过引入簇内覆盖的思想,使得簇内的活动节点数目为一常数,同时减少了工作节点的数目,从而延长网络的生命周期,并在一定程度上提高了系统的可伸缩性.实验结果显示,ED-TDMA协议更适用于网络负载较低、节点密度高的无线传感器网络.     

基于网格的无线传感器网络非均匀分簇算法

在无线传感器网络中,首先要考虑的是如何解决能耗问题.针对无线传感器网络现有算法存在的节点能耗不均匀及节点部署密集造成的数据冗余和能量浪费,提出了一种节能路由算法UECG.通过设定虚拟网格以及非均匀分簇来实现网络能量的均衡消耗.仿真结果表明,与LEACH协议及其改进协议EEUC相比,UECG算法能够有效减少冗余数据,平衡簇群间的能量消耗,达到延长网络寿命的目的.     

无线传感器网络S-MAC协议分析

S-MAc协议是weiYe等人在IEEE802．儿协议的基础上,针对WSNs网络能量有效性而提出的一种专用于WSNs网络的节能协议。S-MAC协议主要使用三种新技术来减少能耗：节点周期性的休眠,邻节点形成虚拟簇在休眠制度上自同步,以及利用消息传递机制来发送长包,减少竞争反应时间。本文将对无线传感网络（WSNs）的节点能耗问题进行讨论,并对无线传感器网络MAc层节能协议进行分析。     

一种高效节能的无线传感器网络 MAC 协议

针对无线传感器网络 MAC 协议的作用与要求,给出一种基于 CDMA 的 MAC 协议改进方案.根据网络负载变化采用周期性的侦听/睡眠机制,使大多数节点处于睡眠状态,节省能耗;同时结合 CDMA 技术给节点分配网内唯一的具有正交性的高速伪随机码(PN)来调制数据信号,使之在时域和频域重叠,实现数据的大规模实时传送.仿真结果表明,协议在保证系统低延时和高吞吐量的同时,能明显减少能量消耗.     

Energy efficient TDMA-based MAC protocol associated with GAF for wireless sensor networks

The design of media access control (MAC) protocol for wireless sensor networks (WSNs) with the idea of cross layer attracts more and more attention. People can improve the MAC protocol by obtaining certain information regarding the network layer and physical layer. This article synthesizes and optimizes certain cross-layer protocols which have existed. On the basis of the routing, topology information in the network layer, and transmission power information in the physical layer, the time slot assignment algorithm has been improved in the MAC layer. By using geographical adaptive fidelity algorithm (GAF) to divide the grids, controlling of transmission power and scheduling the work/sleep duty cycle for sensor nodes, a new MAC protocol has been proposed to decrease energy consumption and enlarge the lifetime of WSNs. Simulation results show that the MAC protocol functions well.     

FPS‐MAC: Fuzzy priority scheduling‐based MAC protocol for intelligent monitoring systems

Recent advances in microelectronics have encouraged the implementation of a wireless sensor network (WSN) in intelligent monitoring systems (IMSs). The IMS for time‐critical applications requires timely and reliable data delivery without sacrificing the energy efficiency of the network. This paper proposes FPS‐MAC, a fuzzy priority scheduling‐based medium access control protocol, designed for event critical traffic in hierarchical WSN. The FPS‐MAC allows time‐critical event traffic to opportunistically steal the data slots allocated for periodic data traffic in event‐based situations. Additionally, a fuzzy logic‐based slot scheduling mechanism is introduced to provide guaranteed and timely medium access to emergency traffic load and ensures the quality‐of‐service (QoS) requirements of IMSs. Both analytical and simulation results for data throughput, energy consumption, and transmission delay of FPS‐MAC, TLHA, E‐BMA, and BMA‐RR have been analyzed to demonstrate the superiority of the proposed FPS‐MAC protocol.     

Mobility Impact on Cluster Based MAC Layer Protocols in Wireless Sensor Networks

Wireless sensor networks (WSNs) enable a wide variety of applications resulting in still increasing requirements for the protocols supporting the operations. The medium access control (MAC) layer protocols are essential for improving the performance of an application and its quality of service because MAC protocols influence channel capacity utilization, network delay, energy consumption, and scalability. The contribution of this paper is two novel cluster-based time division multiple access (TDMA) scheduling MACs for WSNs and an analysis of the mobility impact on both. The proposed MAC layer protocols support real time applications where the cluster-based scheduling improves the scalability and also improves the performance in varying network conditions. The paper presents the design, implementation and performance evaluation of the proposed cluster based TDMA scheduling algorithms green conflict free (GCF) and multicolor-GCF (M-GCF) for high complexity and high requirement applications of WSNs under both low and high mobility conditions. The comparative evaluation shows that the M-GCF algorithm has better slot sharing and less conflicts with reduced communication energy consumption, delay, and good throughput under static and low mobility conditions while the GCF algorithm has better performance in high mobility scenarios. The paper also defines the mobility threshold that decides the use of the GCF- and M-GCF algorithms according to the mobility requirement of application.     

An asynchronous low‐power medium access control protocol for wireless sensor networks

Duty cycling is a fundamental approach used in contention‐based medium access control (MAC) protocols for wireless sensor networks (WSNs) to reduce power consumption in sensor nodes. Existing duty cycle‐based MAC protocols use either scheduling or low‐power listening (LPL) to reduce unnecessary energy lost caused by idle listening and overhearing. This paper presents a new asynchronous duty‐cycled MAC protocol for WSN. It introduces a novel dual preamble sampling (DPS) approach to efficiently coordinate channel access among nodes. DPS combines LPL with a short‐strobed preamble approach to significantly reduce the idle‐listening issue in existing asynchronous protocols. We provide detailed analysis of the energy consumption by using well‐known energy models and compare our work with B‐MAC and X‐MAC, two most popular asynchronous duty cycle‐based MAC protocols for WSNs. We also present experimental results based on NS‐2 simulations. We show that depending on the traffic load and preamble length, the proposed MAC protocol improves energy consumption significantly without degrading network performances in terms of delivery ratio and latency. For example, for a traffic rate of 0.1 packets/s and a preamble length of 0.1 s, the average improvement in energy consumption is about 154%. Copyright © 2011 John Wiley & Sons, Ltd.     

无线传感器网络中基于有限反馈的协同MIMO策略

该文针对无线传感器网络中能量有限问题,提出了一种基于有限反馈的协同MIMO策略。该策略基于梯度算法,用1bit反馈来自动地调整簇头节点和协同簇头节点的发射功率。对无线传感器网络中基于有限反馈的Alamouti码的协同MISO系统的误码率进行了理论分析,推导了基于有限反馈Alamouti码的协同MISO策略能耗的契尔诺夫上限表达式。理论分析和仿真结果都表明,该文提出的协同MISO策略与基于标准Alamouti码的协同策略相比,无线传感器网络的总能耗更低,能效更高,且当簇头节点和协同簇头节点一直选择较好信道对应的节点来发送信息时,即最优策略,无线传感器网络的总能耗更低。     

Affinity propagation‐based interference‐free clustering for wireless sensor networks

Wireless sensor networks (WSNs), eg, industrial WSNs, require reliability and real‐time communication. Clustering technique together with schedule‐based access can provide the benefits, such as energy saving, reliability, and timeliness. However, integrating above two technologies into WSNs requires sophistical time slot allocation mechanism. To simplify the time slot allocation, the paper proposes a distributed interference‐free clustering algorithm for WSNs. The algorithm is inspired by affinity propagation (AP) clustering algorithm. By adapting and improving the original AP algorithm, the proposed clustering algorithm aims to jointly optimize energy saving and coverage issues while providing interference free between clusters. The performance analysis demonstrates that it can achieve high receiving rate (reliability), low delay (real time), and low‐energy consumption.     

ETPS-MAC: Energy Traffic Priority Scheduling-based QoS-aware MAC protocol for hierarchical WSNs

The evolution of the wireless sensor network (WSN) in recent years has reached its greatest heights and applications are increasing day by day, one such application is Smart Monitoring Systems (SMSs) which is in vision of implementation in every urban and rural areas. The implementation of WSN architecture in SMS needs an intelligent scheduling mechanism that efficiently handles the dynamic traffic load without sacrificing the energy efficiency of network. This paper presents a centralized TDMA scheduling based medium access control (MAC) protocol, called Energy Traffic Priority Scheduling MAC (ETPS-MAC) that accommodates variable traffic load while maintaining Quality-of-Service (QoS) assurance in hierarchical WSNs. The ETPS-MAC protocol employs priority scheduling algorithm which considers two factors for assigning priority, the energy factor and the traffic load factor to avoid packet buffering and maintains minimum data packet delay in case of high traffic load. Moreover, a novel rank-based clustering mechanism in FPS-QMAC protocol prolongs the network lifetime by minimizing the distance between the cluster head (CH) and the base station (BS). Both analytical and simulation models demonstrate the superiority of the ETPS-MAC protocol in terms of energy consumption, transmission delay, data throughput and message complexity when compared with the existing TDMA based MAC protocols.     

Analysis and optimization of duty-cycle in preamble-based random access networks

Duty-cycling has been proposed as an effective mechanism for reducing the energy consumption in wireless sensor networks (WSNs). Asynchronous duty-cycle protocols where the receiver wakes up periodically to check whether there is a transmission and the sender transmits preambles to check if the receiver is awake are widely used in WSNs due to the elimination of complex control mechanisms for topology discovery and synchronization. However, the intrinsic simplicity of the asynchronous mechanism has the drawback of smaller energy saving potential that requires the optimization of the duty cycle parameters. In this paper, we propose a novel method for the optimization of the duty-cycle parameters in preamble-based random access networks based on the accurate modeling of delay, reliability and energy consumption as a function of listen time, sleep time, traffic rate and medium access control (MAC) protocol parameters. The challenges for modeling are the random access MAC and the sleep policy of the receivers, which make it impossible to determine the exact time of data packet transmissions, and thus difficult to investigate the performance indicators given by the delay, reliability and energy consumption to successfully receive packets. An analysis of these indicators is developed as a function of the relevant parameters of the network and it is used in the minimization of the energy consumption subject to delay and reliability requirements. The optimization provides significant reduction of the energy consumption compared to the previously proposed protocols in the literature.