无线传感器网络MAC层协议的分析比较

无线传感器网络是一种由大量廉价微型传感器节点组成,并通过无线通信方式形成的多跳自组织网络,可用于对其部署区域的某些物理量进行智能监测。由于传感器节点数目较大,MAC协议是保证无线传感器网络高效通信的关键网络协议之一。另一方面,因为传感器节点受到电源能量有限、通信能力有限、计算和存储能力有限等现实条件的限制,传感器网络中的MAC协议又具有一些独特之处。对无线传感器网络MAC协议的研究现状进行较全面的考察,分析比较其中的几种典型MAC协议,并提出了该领域的发展趋势和未来工作的一些思路。     

A Traffic-Aware Energy Efficient Scheme for WSN Employing an Adaptable Wakeup Period

Recently, Wireless Sensor Networks (WSN) have come to require an energy efficiency and a guaranteed delivery delay time, on the contrary to traditional Medium Access Control (MAC) protocols that have mostly aimed for a high throughput. In order to satisfy these new significant requirements, many of the newer WSN MAC protocols employ duty cycled mechanism, in order to improve energy efficient techniques in the MAC layer. This duty cycled mechanism is oriented to the toggling of the transceiver’s conditions composed of the wakeup and sleep states. However, regrettably, the channel conditions of a wireless network can be changed anytime according to the traffic congestion. If a high congestion is present, an insufficient wakeup period can cause the successful communication ratio to worsen. This can be a weakness in previous duty cycled mechanisms due to their lack of consideration for the network conditions. Therefore, we have devised and designed an efficient new scheme, the adaptable wakeup period, which can resolve this issue. We present analyses and the simulated results of our work, together with a comparison between the synchronous and asynchronous MAC protocols, using two types of analysis models that we suggest.     

Towards a classification of energy aware MAC protocols for wireless sensor networks

Power management is an important issue in wireless sensor networks (WSNs) because wireless sensor nodes are usually battery powered, and an efficient use of the available battery power becomes an important concern specially for those applications where the system is expected to operate for long durations. This necessity for energy efficient operation of a WSN has prompted the development of new protocols in all layers of the communication stack. Provided that, the radio transceiver is the most power consuming component of a typical sensor node, large gains can be achieved at the link layer where the medium access control (MAC) protocol controls the usage of the radio transceiver unit. MAC protocols for sensor networks differ greatly from typical wireless networks access protocols in many issues. MAC protocols for sensor networks must have built‐in power conservation, mobility management, and failure recovery strategies. Furthermore, sensor MAC protocols should make performance trade‐off between latency and throughput for a reduction in energy consumption to maximize the lifetime of the network. This is in general achieved through duty cycling the radio transceiver. Many MAC protocols with different objectives were proposed for wireless sensor networks in the literature. Most of these protocols take into account the energy efficiency as a main objective. There is much more innovative work should be done at the MAC layer to address the hard unsolved problems. In this paper, we first outline and discuss the specific requirements and design trade‐offs of a typical wireless sensor MAC protocol by describing the properties of WSN that affect the design of MAC layer protocols. Then, a typical collection of wireless sensor MAC protocols presented in the literature are surveyed, classified, and described emphasizing their advantages and disadvantages whenever possible. Finally, we present research directions and identify open issues for future medium access research. Copyright © 2009 John Wiley & Sons, Ltd.     

流量自适应媒体访问控制协议的研究与设计

针对媒体访问控制(MAC)协议在无线传感器网络中的作用与要求,分析了典型的MAC协议,提出流量自适应改进方案,并用NS2对其进行了性能测试.仿真结果表明,在网络节点分布较为密集,突发数据流量变化较大的网络环境中,流量自适应MAC协议的能量效率、吞吐率和网络延迟都有较大的改善.     

An Application Oriented Power Saving MAC Protocol for Wireless Sensor Networks

Energy efficiency has been an important concern in wireless sensor networks where Medium Access Control (MAC) protocol plays an important role. However, current MAC protocols designed for energy saving have seldom considered multiple applications coexisting in WSN with variation of traffic load dynamics. In this paper, we propose an adaptive control algorithm at MAC layer to promote energy efficiency. We focus on the tradeoff relation between collisions and control overhead as a reflection of traffic load and propose to balance the tradeoff under the constraints of QoS options. We integrate the algorithm into S-MAC and verify it through NS-2 platform. The simulation results demonstrate that our algorithm achieves observable improvement in energy performance while meeting QoS requirement for different coexisting applications in comparison with S-MAC.     

OCR-MAC：一种新的基于CSMA的无线传感器网络MAC协议

传感器网络被认为是21世纪最重要的技术之一,它将对人类未来的生活产生深远影响,其中MAC协议是WSN通信协议中最为突出也是最为重要的关键协议之一。无线传感器网络具有节点的电源能量和硬件资源受限的特点,因此设计高能效的MAC协议是MAC协议研究中具有挑战性的研究课题。基于以上目的,本文采用了CSMA机制和分簇路由协议的优点,改进了传统的MAC协议提出了OCR-MAC协议,并利用MATLAB进行了仿真,仿真结果表明,改进后的OCR-MAC协议在节能和网络数据传输方面性能更加优越。     

移动代理WSN网络中信道Sift MAC协议

介绍了一种采用移动代理的无线传感器(WSN)网络,该网络系统由移动代理节点负责复杂数据处理、接入处理、数据转发传输、路由维护等工作,与一般WSN网络相比具有节能优势。该网络系统MAC层采用S-ALOHA协议,不仅网络吞吐量低而且能耗大,依据网络结构特点提出了采用基于信噪比(SNR)的信道Sift协议。仿真验证该协议大大提高了网络吞吐量和降低了网络系统能耗。     

GSHMAC: Green and Secure Hybrid Medium Access Control for Wireless Sensor Network

The cost efficiency of wireless platforms and their easy deployment enable the applicability of it in widespread application domains. Wireless sensor networks (WSNs) are not excluded from it. Their application domains vary from industrial monitoring to military applications. A WSN is a resource-constrained network and energy of the WSN node is a valuable resource. Like every other network, WSNs are also vulnerable to security attacks. A security attack can results in networks consuming more resources, leading to earlier depletion of node energy. A significant part of the resource consumption in a WSN is controlled by the medium access control (MAC) mechanism. This paper focuses on WSN MAC mechanisms and countermeasures for attacks targeting the MAC layer in a WSN. Denial of sleep attacks are the most relevant for WSN MAC as these types of attacks have shattered effects, which bring down the sensor lifetime from years to days. This paper proposes a secure hybrid MAC mechanism, Green and Secure Hybrid Medium Access Control (GSHMAC) to overcome the devastating effect of WSN MAC attacks. The proposed mechanism provides features such as collision threshold-based MAC mode control and countermeasures on WSN MAC using internal MAC mechanisms. GSHMAC shows improved energy-efficiency, delay, and throughput in the presence of attacks, as compared with state-of-art secure MAC mechanisms.     

A Massive Transmission Scheme in Contention-Based MAC for Wireless Multimedia Sensor Networks

For transmitting the data which is composed of sensed information in sensors, wireless sensor networks have been developed and researched for the improvement of energy efficiency, hence, many MAC protocols in WSN employ the duty cycle mechanism. Since the progressed development of the low power transceiver and processor let the high energy efficiency come true, the delivery of the multimedia data which occurs in the area of sensor work should be needed to provide supplemental information. In this paper, we design a new scheme for massive transmission of large multimedia data where the duty cycle is used in contention based MAC protocol, for WMSN. The proposed scheme can be applied into the previous duty cycle mechanism because it provides two operations between normal operation and massive transmission operation. Measuring the status of the buffer in a sender and the condition of current radio channel can be criteria for the decision of the above two operations. This paper shows the results of the experiment by performing the simulation. The target protocol of the experiment is X-MAC which is contention-based MAC protocol for WSN. Two approaches, both X-MAC which operates only duty cycle mechanism and X-MAC(MTS) which operates combined massive transmission scheme, are used for the comparative.     

基于WSN的能量高效MAC协议研究

介质访问控制(medium access control,MAC)协议能效性直接影响着无线传感器网络的寿命.在阐述能量消耗分布及造成无效功耗原因的基础上,分析了MAC协议的性能评价指标和分类方法;重点围绕能量高效,比较研究了当前一些重要的MAC协议,结果表明不存在满足所有要求的协议,仅仅是在各性能间优化折中;最后展望了无线传感器网络MAC协议进一步的研究趋势.     

SPEECH‐MAC: Special purpose energy‐efficient contention‐based hybrid MAC protocol for WSN and Zigbee network

Energy‐efficient Zigbee‐based wireless sensor network (WSN) occupies a major role in emergency‐based applications. The foremost drawback of such applications is maintaining the battery power because frequent changing is not possible in those conditions. In the earlier days, several researches created new model MAC protocols in terms of increase the lifetime of the WSN. But still, there is a research gap particularly in emergency applications. In order to improve the lifetime of such applications, we introduced a novel hybrid MAC protocol, namely, special purpose energy‐efficient contention‐based hybrid MAC (SPEECH‐MAC) protocol. This protocol includes dual hop concept considerably to save the energy. Both the single hop network and the dual hop networks are developed, and the results are analyzed. Prioritization mechanism for SPEECH‐MAC protocol is introduced to analyze the emergency conditions in detail. In summary, according to the simulation, the calculated parameters are total residual energy, end‐to‐end delay, packet drop, packet delivery ratio, and network throughput.     

低占空比无线传感器网络中MAC协议研究进展

无线传感器网络(WSN)是一种多跳自组织网络,它由大量具有有限能力的节点组成,在工业、农业、交通、国防等领域具有广泛应用.为了减少节点的能量消耗,延长网络的生命周期,近年来逐渐出现了基于低占空比技术(Low-Duty-Cycle)的WSN,简称LDC-WSN.在LDC-WSN中,节点在一个工作周期内大部分时间处于睡眠状态,只有极少时间内处于工作状态.MAC协议是实现LDC-WSN中节点睡眠调度的关键,对LDC-WSN保持正常工作并获得理想的工作性能具有非常重要的意义.针对LDC-WSN中MAC协议的研究仍处于起步阶段,是目前研究的热点.对当前研究进行综述,详细介绍和分析LDC-WSN中最具代表性和较新的MAC协议.通过对比和总结当前工作的优缺点,明确了目前存在的问题和难点,为未来更深入的研究指明了方向.     

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.     

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.     

Supporting bursty traffic in wireless sensor networks through a distributed advertisement-based TDMA protocol (ATMA)

Nodes in wireless sensor networks (WSNs) are battery powered and oftentimes deployed in remote and hostile locations. Energy conservation is, therefore, one of the primary goals of MAC protocols designed for these networks. Contention-based protocols employ static or variable duty cycles to minimize energy dissipated in idle listening. TDMA-based protocols, on the other hand, use reservation and scheduling to minimize energy loss. Further energy savings may be obtained by taking the nature of the network traffic into consideration. Several WSN applications such as surveillance applications and habitat monitoring applications generate bursty traffic. In this paper, we combine the advantages of contention-based and TDMA-based protocols to form Advertisement-based Time-division Multiple Access (ATMA), a distributed TDMA-based MAC protocol for WSNs, that utilizes the bursty nature of the traffic to prevent energy waste through advertisements and reservations for data slots. We provide detailed comparisons of the ATMA protocol with contention-based protocols (S-MAC, T-MAC and ADV-MAC), a TDMA-based protocol (TRAMA) and hybrid protocols (Z-MAC and IEEE 802.15.4) through extensive simulations and qualitative analysis. The simulation results show that with bursty traffic, ATMA outperforms these existing protocols in terms of energy consumption with reductions of up to 80%, while providing the best packet delivery ratio (close to 100%) and latency among all the investigated protocols for several simulation scenarios studied.     

A Distributed MAC Protocol Using Virtual Control Channels for CRSNs

A cognitive radio sensor network (CRSN) is a promising fusion network that combines conventional wireless sensor network (WSN) with cognitive radio (CR) functionalities. With abilities to sense for available channels and to adapt to the radio environment, a CRSN is able to be more opportunistic in accessing spectrums than a WSN, but it also has problems due to hardware constraints and energy limitations. In many studies on distributed CR MAC protocols, establishing dedicated control channels (DCCs) has been considered as an important problem because it is essentially used for coordination and negotiation of spectrum assignments. However, directly applying DCCs into CRSNs is impractical, due to its high-cost complexity in hardware and deployment. To solve it, in this paper we propose a distributed MAC protocol using virtual control channels for CRSNs, in which CR sensor nodes called secondary users are grouped into clusters, and commonly shared available channels are utilized as virtual DCCs. In addition, a channel selection scheme is developed, based on an approximated partially observable Markov decision process. Our numerical simulation results indicate that the proposed MAC protocol can not only improve the throughput rate but also reduce the energy consumption under no DCCs.     

Performance of Transport Protocols for Multimedia Communications in Wireless Sensor Networks

Many wireless sensor network (WSN) applications require efficient multimedia communication capabilities. However, the existing communication protocols in the literature mainly aim to achieve energy efficiency and reliability objectives and do not address multimedia communication challenges in WSN. In this paper, comprehensive performance evaluation of the existing transport protocols is performed for multimedia communication in WSN. Performance metrics such as packet delivery rate, end-to-end packet delay, bandwidth and energy efficiency, frame peak signal-to-noise ratio (PSNR), delay-bounded frame PSNR, frame delivery probability, frame end-to-end delay and jitter are investigated. The results clearly show that the existing transport protocols are far from satisfying the requirements of multimedia communication in WSN and hence there is a need for new effective multimedia delivery protocols for WSN.     

MAC Protocols for Energy Harvesting Wireless Sensor Networks: Survey

Energy harvesting (EH) technology in the field of wireless sensor networks (WSNs) is gaining increasing popularity through removing the burden of having to replace/recharge depleted energy sources by energy harvester devices. EH provides an alternative source of energy from the surrounding environment; therefore, by exploiting the EH process, WSNs can achieve a perpetual lifetime. In view of this, emphasis is being placed on the design of new medium access control (MAC) protocols that aim to maximize the lifetime of WSNs by using the maximum possible amount of harvested energy instead of saving any residual energy, given that the rate of energy harvested is greater than that which is consumed. Various MAC protocols with the objective of exploiting ambient energy have been proposed for energy‐harvesting WSNs (EH‐WSNs). In this paper, first, the fundamental properties of EH‐WSN architecture are outlined. Then, several MAC protocols proposed for EH‐WSNs are presented, describing their operating principles and underlying features. To give an insight into future research directions, open research issues (key ideas) with respect to design trade‐offs are discussed at the end of this paper.     

Adaptive MAC Protocol for Solar Energy Harvesting Based Wireless Sensor Networks in Agriculture

The wireless sensor network is one of the promising technologies in the agriculture field. Its actual usage in real agriculture fields is limited by its dependence on the small batteries which cannot make the network survive for long. Various protocols are being designed at the network and MAC layer to increase the lifetime of the nodes, but up to a certain extent only. Hence the energy harvesting to power up the WSN nodes is a promising technology to fulfill this ever energy demand, but the protocols need to be redesigned for this scenario. Solar energy harvesting based MAC protocol which is adaptive to the changing weather conditions is designed in this paper for the smart agriculture applications. It is based on the multilayer and receiver-initiated process to improve network quality. It has shown the remarkable performance over the other energy harvesting based protocols in terms of ENO ratio, energy consumption and collision rate.

     

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.