摘要：作为最适用于无线传感器网络的近距离无线通信技术标准之一，IEEE802.15.4协议及其性能已被广泛研究。但由于其竞争接入期的CSMA/CA机制采用固定接入参数进行信道接入，因此在网络负载较大时产生严重丢包现象及过度能耗问题，且在动态网络环境中不能始终达到应用层要求。本论文针对此问题，对IEEE802.15.4信道接入参数自适应优化策略进行研究。

首先，深入分析了信道接入参数：最小退避指数、最大退避次数及重传次数对可靠度和能量效率的影响，为自适应优化策略提供参考。

其次再详细介绍了知名优化算法ADAPT(AdaptiveAccessParametersTuning)。该算法主要应用于MAC层，通过实时分析网络各项性能指标来变更MAC层信道接入参数，从而提升整体网络效能。

最后通过具体的仿真结果说明该算法无论是在静态还是动态网络仿真环境下都能根据网络传输负载变化及时调整算法参数，进而满足应用层对传输可靠性要求的同时降低能耗。

关键词无线传感网络能耗可靠度自适应优化算法

毕业设计说明书外文摘要

Title  Research  on  IEEE  802.15.4  Network  Adaptive Strategy                       

Abstract：As a favorite protocol in wireless sensor networks,IEEE 802.15.4 has been extensively studied. However, its reliability and energy efficiency would become poor when the network load is high, due to its MAC parameters are fixed. In order to address this problem, this dissertation study a adaptive parameters tuning approache for IEEE 802.15.4 networks. 

First, we evaluate the impact of the MAC parameters on the reliability and the energy efficiency of the network. The results provide a few guidelines for the design of adaptive strategies for reliable and energy-efficient operations.  Second, we analyze the well-know adapative strategy, called ADAPT. The strategy involves an energy-aware adaptation module that captures the application’s reliability requirements, and autonomously configures the MAC layer based on the network topology and the traffic conditions in order to minimize the power consumption. 

Finally, the simulation results show that the algorithm can adjust the parameters of the algorithm according to the network transmission load both in stationary and dynamic operating conditions,and so the required reliability level can be achieved at runtime. 

Keywords wireless sensor networks energy reliability adaptive optimization algorithm 

目次

1绪论1

1.1无线传感网.1

1.2IEEE802.15.4无线网络.4

1.3国内外研究现状.5

1.4论文结构与主要工作.6

2IEEE802.15.4MAC协议...8

2.1引言...8

2.2设备类型...8

2.3拓扑结构...8

2.4超帧结构..10

2.5数据传输模型..11

2.6信道接入算法..14

3IEEE802.15.4信道接入参数对性能影响仿真分析16

3.1引言..16

3.2接入参数调整对投递率的影响16

3.3接入参数调整对能量效率的影响..18

3.4本章小结..20

4ADAPT投递率优化策略仿真分析22

4.1引言..22

4.2系统模型..22

4.3设计思想..23

4.4优化策略..23

4.5仿真设置..27

4.6静态条件下的仿真分析..28

4.7动态条件下的仿真分析..32

4.8本章小结..34

结论.36

致谢.37

参考文献.38

1绪论

1.1无线传感网

1.1.1无线传感器网络结构

随着无线通信技术以及嵌入式芯片技术的进步与成熟，以这两项技术为基础的小型传感器正在不断发展[1]。其较低能耗与成本低廉的特点使小型传感器在信息采集以及无线收发和数据处理领域有着很大的应用。