ZiMAC：基于NC-OFDM的WiFi与ZigBee共存的MAC协议

发布时间：2018-03-27 06:26

  本文选题：MAC　切入点：WiFi　出处：《天津大学》2014年硕士论文

【摘要】：随着WiFi与ZigBee技术的不断发展以及他们在日常生活中发挥着越来越重要的作用,如高速网络接入和火灾监控等,这两种异构网络得到了越来越广泛的部署。由于WiFi和ZigBee共享2.4GHz ISM(Industrial Sciencific Medical)频段且常同时出现在同一环境中,当网络节点密度较大时两者的信道频谱将发生重叠,引起共信道干扰。相比CSMA机制,子载波置零技术可以通过分离WiFi与ZigBee的信号频谱更好地实现两者共存,且信号的并行传输使得频谱资源得到充分利用。本文针对非连续子载波正交频分复用(Non-Continuous Orthogonal Frequency Division Multiplexing,NC-OFDM)物理层在WiFi与ZigBee共存场景的应用,为WiFi设计一个与之相适应的媒体接入控制(Medium Access Control,MAC)协议:ZiMAC。ZiMAC关键技术主要有三部分,一是根据WiFi与ZigBee信道特点而重新设计的载波侦听功能,它包括新的信道状态定义以及判定物理层应该采用的发送模式;二是根据应用场景需要而改进的分布式信道接入机制;三是为保证ZigBee节点在Duty-Cycle工作方式下能够及时接入信道并进行数据传输而设置的计数器机制,它也将左右WiFi物理层发送模式的选择。本文在GNU Radio/USRP软件无线电平台上实现了ZiMAC协议,并验证其各部分功能的正确性,同时对ZiMAC的性能进行测试并分析影响其性能的因素。实验结果表明,ZiMAC在保证ZigBee与NC-OFDM并行传输能获得较好性能的同时,减少了由于子载波置零而导致的WiFi吞吐率下降:当ZigBee的数据发送密度较小时,ZiMAC在1/2带宽以及3/4带宽下的相对吞吐率比单纯采用子载波置零模式发送最大可分别提高约50个和28个百分点。
[Abstract]:With the development of WiFi and ZigBee technology, they play more and more important role in daily life, such as high-speed network access and fire monitoring. Because WiFi and ZigBee share the 2.4GHz ISM(Industrial Sciencific frequency band and often appear in the same environment simultaneously, the channel spectrum of the two networks will overlap when the network node density is high. Compared with the CSMA mechanism, the sub-carrier zeroing technique can realize the coexistence of WiFi and ZigBee better by separating the signal spectrum of the WiFi and the ZigBee. The parallel transmission of signals makes full use of spectrum resources. This paper aims at the application of non-continuous Orthogonal Frequency Division multiplexing NC-OFDM physical layer in the scene of coexistence of WiFi and ZigBee. There are three key technologies in designing a medium Access Control (MAC) protocol for WiFi: Zim AC.ZiMAC. One is the carrier interception function redesigned according to the characteristics of WiFi and ZigBee channels. It includes the new channel state definition and the transmission mode to be used in the physical layer, and the improved distributed channel access mechanism according to the needs of the application scenario. The third is the counter mechanism set up to ensure that the ZigBee node can access the channel and transmit data in time under the Duty-Cycle operation mode, which will also influence the choice of the transmission mode of the WiFi physical layer. In this paper, the ZiMAC protocol is implemented on the GNU Radio/USRP software radio platform. At the same time, the performance of ZiMAC is tested and the factors affecting its performance are analyzed. Reduced WiFi throughput due to subcarrier zeroing: when ZigBee data transmission density is small, the relative throughput of ZigBee at 1 / 2 bandwidth and 3 / 4 bandwidth is higher than that of single subcarrier zero mode transmission. It was about 50 percent higher and 28 percent higher.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN92

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1 安静怡;基于无线传感器网络的室内燃气监测系统[D];北京邮电大学;2011年

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