无线Ad hoc网络定向MAC协议研究

发布时间：2018-11-19 19:01

【摘要】：由于Ad hoc网络的组网灵活性强、支持移动性、易于迅速展开、系统整体抗毁能力强和系统成本低等特点,被广泛应用于车辆联网、应急救援和军用战术网络等网络场景中。然而,随着各种各样上层业务涌现,Ad hoc网络的容量以及传输质量亟需提升,全向Ad hoc网络已经无法得到满足。因此引入定向天线,利用定向天线在天线增益、传输范围和抗干扰能力的优势,可以极大改善移动Ad hoc网络的性能。然而,定向天线为Ad hoc网络带来好处的同时,也引入了诸如耳聋‖和天线增益不对称导致的隐藏终端等问题。因此,如何设计高效定向MAC协议,使得定向天线的性能和优势得以发挥的同时又有效地减轻上述问题,是本文研究的重点。首先,论文在NS-3上设计了波束宽度和数量可调的波束切换定向天线模型,实现了经典的定向MAC协议——DVCS协议,包括对原有WLAN模型进行扩展,提供天线波束的切换、锁定和解锁功能,建立到达方向角缓存和定向网络分配向量表。结果验证,定向天线的使用提高了Ad hoc网络的吞吐量、降低了节点间的干扰,提升了分组递交率、缩短了分组平均时延。其次,由于多向时序RTS协议分类中的CRCM协议无需事先知道节点位置信息,且通过依次发送定向RTS和定向CTS包减轻“耳聋”问题和因天线增益不同而导致的隐藏终端问题,论文对CRCM协议进行适用性分析,仿真结果表明,CRCM协议有效减轻定向MAC面临的问题,与DVCS协议及全向MAC协议相比较提高了网络吞吐量,对移动场景的适应能力更好。最后,针对大量连续稳定的业务模型,CRCM协议存在发送控制分组时间长而导致的通信效率低的问题,论文提出了一种改进的CRCM协议,通过合理减少循环RTS和CTS握手次数,并改进随机退避算法,提升协议的传输效率。结果表明所提协议减少了控制开销,提升了传输效率,提高了吞吐量,降低了分组时延。
[Abstract]:Ad hoc network is widely used in network scenarios such as vehicle networking, emergency rescue and military tactical networks because of its strong flexibility, mobility, ease of rapid deployment, strong overall anti-destruction ability and low system cost. However, with the emergence of various upper layer services, the capacity and transmission quality of, Ad hoc networks need to be improved, omnidirectional Ad hoc networks can not be satisfied. Therefore, the performance of mobile Ad hoc networks can be greatly improved by introducing directional antennas and utilizing the advantages of directional antennas in antenna gain, transmission range and anti-jamming ability. However, while directional antennas bring benefits to Ad hoc networks, problems such as deafness and hidden terminals caused by antenna gain asymmetry are also introduced. Therefore, how to design an efficient directional MAC protocol to give full play to the performance and advantages of directional antennas while effectively reducing the above problems is the focus of this paper. Firstly, the paper designs a beam-switching directional antenna model with adjustable beamwidth and number on NS-3, and implements the classical directional MAC protocol-DVCS protocol, including extending the original WLAN model to provide antenna beam switching. Lock and unlock functions, build DOA cache and directional network assignment scale. The results show that the use of directional antenna can improve the throughput of Ad hoc network, reduce the interference between nodes, improve the packet delivery rate and shorten the average packet delay. Secondly, the CRCM protocol in the classification of multidirectional sequential RTS protocols does not need to know the node location information in advance, and the "deafness" problem and the hidden terminal problem caused by different antenna gain are alleviated by sending the directed RTS and directed CTS packets in turn. The applicability of CRCM protocol is analyzed in this paper. The simulation results show that the CRCM protocol can effectively alleviate the problems faced by directed MAC. Compared with DVCS protocol and omnidirectional MAC protocol, the network throughput is improved and the adaptability to mobile scenes is better. Finally, aiming at a large number of continuous and stable traffic models, the CRCM protocol has the problem of low communication efficiency due to the long time of sending and controlling packets. In this paper, an improved CRCM protocol is proposed, which can reasonably reduce the number of circular RTS and CTS handshake. And improve the random Backoff algorithm to improve the transmission efficiency of the protocol. The results show that the proposed protocol reduces the control overhead, improves the transmission efficiency, improves the throughput and reduces the packet delay.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

【参考文献】