【作者】 徐珊珊；

【导师】 赵远东；

【作者基本信息】 南京信息工程大学 ， 系统分析与集成， 2007， 硕士

【摘要】 本论文主要研究Ad hoc网络中的能量效率问题。Ad hoc网络是一种无固定结构的分布式多跳网络，由于节点的移动性，网络中的节点一般依靠电池供电，而电池的存储能量有限，这使得能量问题成为Ad hoc网络中的突出问题。论文对Ad hoc网络各层存在的能量问题进行了阐述，给出了Ad hoc网络模型，定义了网络均衡度，以及根据实际测量结果得到的能量消耗模型。论文提出了链路层和路由层的解决方案，分别是PEMAC链路协议、TBER路由度量算法。大量的研究文献表明，节点处于休眠状态的时候其能量消耗非常小，基于节点休眠模式的PEMAC协议正是利用了节点的这一特性，使节点可以在休眠、空闲和传输状态中切换。采用PEMAC协议，节点处于空闲状态一段时间后如果没有数据发送或者节点收到目的地址为其它节点的RTS／CTS消息后将进入休眠状态，从而节省了能量。论文对PEMAC协议进行了建模分析，给出了该协议的离散Markov链模型，并通过该模型求得在一定参数条件下的节点最佳休眠时间的公式。分析和仿真结果表明，采用该协议可以有效地延长网络生存时间，提高网络的吞吐量。TBER路由度量与目前所提出的各种基于能量的路由度量不同，该度量从流量的角度出发，综合考虑了节点当前能量以及节点链路层的拥塞情况，是一种兼顾整体(整个网络)与局部(单个节点)的能量路由度量方案。该路由度量方法可以使网络中节点的能量被更加均匀、合理地利用，同时也均衡了网络的流量，提高了网络的吞吐量和能量效率，延长了网络的生存时间。本论文指出网络各层次间协议相适配，可以进一步提高网络的性能，如延长网络生存时间、提高网络吞吐量等。论文对链路层与路由层的能量问题进行了综合分析，分析和仿真表明，在链路层采用PEMACA协议的同时在路由层采用TBER路由度量可以进一步提高Ad hoc网络生存时间和网络吞吐量，提高网络的能量效率。更多还原

【Abstract】 Ad hoc networks are multi-hop wireless networks without fixed infrastructure.Because node’s strong dependency on batteries, the Ad hoc networks areenergy-constrained. How to improve energy efficiency is an important design issuedue to the limited battery life.This paper presents a summary of recent work on energy efficiency among alllayers of Ad hoc networks, defines a model of Ad hoc network using random graphtheorem, and gives an energy consumption model by realistic test. Our researchesfocus on energy efficiency of the MAC layer and the network layer.In the MAC layer, we develop a new energy efficiency MAC protocol calledPEMAC. This protocol reduces the energy consumption of node. Using PEMAC, anode with packet to transmit sends an RTS message, and the destination node returnsa CTS. The node should switch into the sleep state when:(1) if there is no packet totransmit after an idle period, or (2) it receives an RTS/CTS message destined to othernode. A Markov chain model for PEMAC is presented to obtain the optimal sleepingtime of the node. Simulation results show that, compared with traditional IEEE802.11 Ad hoc networks, PEMAC outperforms in terms of network lifetime andnetwork throughput.TBER is a new energy-efficiency metric for determining routes in Ad hocnetworks. With TBER, the node’s residual energy (remaining battery capacity) andMAC load are taken into account. As a result, an established route avoids usingnodes with minimum energy or heavy load. A comparison of MPTR routing andTBER routing metric is conducted. The analysis and simulation results show thatTBER routing metric can prolong the network lifetime and increase networkthroughput when there are enough routes to be selected. Results also show that theimprovement is limited due to overhearing.We also combined the PEMAC with TBER and get the conclusion thatincorporation of energy efficiency methods appropriately can further improvenetwork lifetime and throughput.更多还原