基于动态帧聚合机制的WLAN传输优化

发布时间：2018-03-19 19:13

本文选题：无线网络　切入点：传输优化　出处：《国防科学技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着无线网络的广泛应用,网络效率和性能成为关注的重点。802.11n提出帧聚合技术,可以有效的提高无线网络的传输带宽。论文针对动态帧聚合进行研究,具有重要的理论和应用价值。论文首先介绍了MAC层帧聚合研究现状,分析了固定帧长帧聚合的性能。然后针对一定规模的无线网络系统,可以估计系统最大吞吐量情况下的最佳帧长。提出基于误比特率的的自适应帧聚合机制(Adaptive Frame Aggregative Based on BER,AFABB),根据信道误比特率动态调整聚合帧长,以获得最佳的传输带宽。最后,对NS2仿真软件的802.11 MAC进行扩展和改进,对提出的算法进行仿真验证。具体工作如下:(1)利用Markov链模型,基于固定帧长,分别对A-MSDU、A-MPDU和两级帧聚合进行理论分析。综合衡量网络利用率和时延,A-MPDU可以获得较好的信道利用率和传输时延。由于信道误比特率是动态变化的,当采取固定帧长,MAC层利用率不能够得到最佳。(2)根据理论模型,估计一定信道误比特率条件下,使得信道利用率最大的最佳数据单元长度。以此为基础,提出自适应帧聚合的算法,根据信道误比特率,自适应选择最佳的帧长进行聚合,提升MAC层利用率。(3)原有NS2仿真软件的802.11MAC层每次只获取一份数据包,不能支持帧聚合。论文在NS2仿真软件的基础上,对802.11MAC采取增加缓存的方法,改变获取数据包数量,进行帧聚合支持。构建仿真场景,对AFABB算法进行仿真验证。结果表明,与固定帧长策略相比,AFABB算法对于不同的误码率条件能够获得更高的MAC层利用率。
[Abstract]:With the wide application of wireless networks, network efficiency and performance become the focus of attention. 802.11n proposed frame aggregation technology, which can effectively improve the transmission bandwidth of wireless networks. This paper first introduces the research status of MAC layer frame aggregation, and analyzes the performance of fixed frame length frame aggregation. The optimal frame length can be estimated in the case of maximum throughput of the system. Adaptive Frame Aggregative Based on error rate based frame aggregation mechanism is proposed to dynamically adjust the aggregated frame length according to the channel bit error rate in order to obtain the best transmission bandwidth. Finally, an adaptive frame aggregation mechanism based on bit error rate (BER) is proposed. The 802.11 MAC of NS2 simulation software is extended and improved, and the proposed algorithm is simulated and verified. The detailed work is as follows: using Markov chain model, based on fixed frame length, The theoretical analysis of A-MSDUU A-MPDU and two-stage frame aggregation is carried out respectively. A better channel utilization and transmission delay can be obtained by synthetically measuring network utilization and delay. When using fixed frame length MAC layer utilization can not get the best. 2) based on the theoretical model, the optimal length of data unit which makes the maximum channel utilization rate can be estimated under the condition of certain channel bit error rate. An adaptive frame aggregation algorithm is proposed, which adaptively selects the best frame length to aggregate according to the channel bit error rate (BER), and improves the utilization ratio of the MAC layer. (3) the 802.11 MAC layer of the original NS2 simulation software only acquires one packet at a time. On the basis of NS2 simulation software, this paper adopts the method of increasing buffer for 802.11 MAC, changes the number of packets and supports frame aggregation. The simulation scene is constructed and the AFABB algorithm is simulated and verified. Compared with the fixed frame length strategy, the proposed algorithm can achieve higher MAC layer utilization under different BER conditions.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925.93

【共引文献】