【作者】 王悦；

【导师】 孙献璞；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2007， 硕士

【摘要】 移动AdHoc网络是一种工作在无固定设施环境下,由一组带有无线收发装置的移动终端节点组成的多跳的临时性的自治系统。功率控制机制是在保证一定通信质量的前提下,通过调节信号发射功率,使发送功率尽可能小的一种方法。在AdHoc网络中,采用功率控制机制不但能够降低网络能耗,还可以降低对邻近节点的干扰,提高信道的空间复用度,最终提高整个网络的容量。本文对Ad Hoc网络中已有的PCMA协议进行了研究,并结合双忙音多址接入协议DBTMA以及双窗口动态退避机制DWDB提出了一种改进的PCMA协议——S-PCMA协议。协议的基本思想是使用发端发起的忙音信号作为封闭节点的请求接入机制,缓解了节点间成功通信的概率随着距离和网络负载的增加而单调减小的问题。结合DWDB机制,有效地解决了通信网络中的不公平问题以及节点封闭问题。通过分析和仿真,证明了S-PCMA协议可以对公平性信道接入和吞吐量进行折衷,因此它比传统的双忙音协议和功率控制协议都要灵活。更多还原

【Abstract】 A mobile Ad Hoc network (MANET) is a collection of wireless mobile nodesdynamically forming a temporary multiple-hop network without the use of any centralcontroller or existing net-infrastructure.Under the premise of ensuring a certain quality of communication, the idea ofpower controlled schemes is to adjust the transmission power optimally and reduce it asmuch as possible. Introducing power controlled schemes in Ad Hoc network, can notonly debasing the network energy wastage, but also reducing the interference withnearby nodes. Channels can be aggressively reused, which can enhance the capability ofentire network.In this paper, former PCMA protocol is deeply researched. An improved PCMAprotocol (S-PCMA) which combines DBTMA protocol with DWDB protocol isproposed. The essential idea of S-PCMA protocol is using the sender-initiated powercontrolled busy tone as a mechanism for blocked nodes to announce the access request.A problem that the probability of successful communications between different nodes ismonotonically decreasing with respect to the increased distance and traffic load isabated. Integrating with DWDB scheme, S-PCMA protocol can effectively solve theunfair channel access problem and nodes blocked problem in communication networks.Through analysis and simulation, we demonstrate that the S-PCMA protocol is ableto balance the tradeoff between fair channel access and throughput, and is thereforemore flexible than both the traditional dual busy tone and power controlled MACprotocols.更多还原