无线局域网MAC优化技术研究
发布时间：2018-12-08 18:18
【摘要】：随着无线局域网的发展,其部署密度越来越密集,由于无线资源的有限,导致网络信道竞争冲突增加,同时,人们对无线网络的服务要求也越来越高,一些语音、视频等实时性较强的多媒体业务必将越来越多。如何提高MAC协议的传输性能、减少冲突的发生、提高网络公平性,如何使WLAN能够提供及时、有效、稳定的服务质量保障,区分不同业务提供不同服务,这些问题都成为退避算法研究的重要内容。针对以上问题,论文从提高节点之间的公平性,提高网络吞吐量,以及提供区分服务为出发点,研究了无线局域网传输优化问题。论文的主要贡献有以下几点:(1)针对BEB二进制退避算法存在的不公平问题,提出一种提高节点的接入公平性、减少非必要退避时间的融合性退避算法FAEIED。该算法是以EIED算法为基础,加入一个门限值CWth,来判断当前信道竞争激烈程度,然后根据判断调整竞争窗口大小。同时,在网络负载较轻时,引入FCR算法的快速接入机制,降低每个竞争周期中产生的空闲信道时间,以提高节点接入效率,减少系统浪费的退避时间,进一步提高传输性能。(2)提出了一种平衡MAC协议中节点初始竞争窗口的方法。该初始竞争窗口处理方法通过对不同优先级别节点的初始竞争窗口进行区分设置,使高优先业务能够以较高的概率接入信道,平衡不同优先等级业务的初始竞争窗口大小,使不同优先等级业务以不同概率接入信道来达到区分服务的目的。(3)针对DCF机制中无法根据优先级别提供区分服务的问题,提出一种基于区分服务的退避算法DSMAC。通过增加一个优先等级标识位P来区分不同优先等级,采取修改低优先级别业务的MAC层初始竞争窗值,并根据优先等级设定重传次数,区分不同优先级别业务退避策略来实现业务的区分服务。(4)基于ns2对提出的MAC协议改进进行了设计实现,并构建仿真场景进行仿真比较,结果表明FAEIED算法使节点之间的公平性有了明显提升,由于加入了快速接入机制,吞吐量也有一定的提高。DSMAC算法能够使高优先业务节点占有更多的带宽,降低了其平均时延和丢包率。
[Abstract]:With the development of wireless local area network (WLAN), its deployment density becomes more and more dense. Due to the limitation of wireless resources, the network channel competition conflicts increase. At the same time, the requirement of wireless network service is more and more high, some voice, Video and other real-time multimedia services will be more and more. How to improve the transmission performance of MAC protocol, reduce the occurrence of conflicts, improve network fairness, how to enable WLAN to provide timely, effective, stable quality of service guarantee, distinguish different services to provide different services. These problems have become an important content in the study of Backoff algorithm. Aiming at the above problems, this paper studies the transmission optimization of WLAN from the point of view of improving the fairness between nodes, improving network throughput, and providing differentiated services. The main contributions of this paper are as follows: (1) aiming at the unfair problem of BEB binary Backoff algorithm, a fusion Backoff algorithm (FAEIED.) is proposed to improve the access fairness of nodes and reduce the unnecessary Backoff time. The algorithm is based on the EIED algorithm, adding a threshold CWth, to judge the intensity of the current channel competition, and then adjusting the size of the competition window according to the judgment. At the same time, when the network load is lighter, the fast access mechanism of FCR algorithm is introduced to reduce the idle channel time generated in each competition cycle, so as to improve the node access efficiency and reduce the time wasted by the system. Further improve the transmission performance. (2) A method to balance the initial contention window of nodes in MAC protocol is proposed. The initial competition window processing method distinguishes and sets the initial competition window of different priority level nodes so that the high priority service can access the channel with high probability and balance the initial competition window size of different priority level services. Different priority services can be accessed by different probabilistic access channels to achieve the purpose of differentiated service. (3) aiming at the problem that differentiated service can not be provided according to priority level in DCF mechanism, a Backoff algorithm based on differentiated Service (DSMAC.) is proposed. By adding a priority level identifier P to distinguish different priority levels, we modify the initial competition window value of the MAC layer for low-priority services, and set the number of retransmissions according to the priority level. (4) based on ns2, the proposed MAC protocol improvement is designed and implemented, and simulation scenarios are constructed to carry out simulation comparison. The results show that the fairness between nodes of the FAEIED algorithm has been improved obviously, and the throughput has been improved due to the addition of fast access mechanism. The DSMAC algorithm can make the high-priority traffic nodes have more bandwidth. The average delay and packet loss rate are reduced.
【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
，
本文编号：2368793
[Abstract]:With the development of wireless local area network (WLAN), its deployment density becomes more and more dense. Due to the limitation of wireless resources, the network channel competition conflicts increase. At the same time, the requirement of wireless network service is more and more high, some voice, Video and other real-time multimedia services will be more and more. How to improve the transmission performance of MAC protocol, reduce the occurrence of conflicts, improve network fairness, how to enable WLAN to provide timely, effective, stable quality of service guarantee, distinguish different services to provide different services. These problems have become an important content in the study of Backoff algorithm. Aiming at the above problems, this paper studies the transmission optimization of WLAN from the point of view of improving the fairness between nodes, improving network throughput, and providing differentiated services. The main contributions of this paper are as follows: (1) aiming at the unfair problem of BEB binary Backoff algorithm, a fusion Backoff algorithm (FAEIED.) is proposed to improve the access fairness of nodes and reduce the unnecessary Backoff time. The algorithm is based on the EIED algorithm, adding a threshold CWth, to judge the intensity of the current channel competition, and then adjusting the size of the competition window according to the judgment. At the same time, when the network load is lighter, the fast access mechanism of FCR algorithm is introduced to reduce the idle channel time generated in each competition cycle, so as to improve the node access efficiency and reduce the time wasted by the system. Further improve the transmission performance. (2) A method to balance the initial contention window of nodes in MAC protocol is proposed. The initial competition window processing method distinguishes and sets the initial competition window of different priority level nodes so that the high priority service can access the channel with high probability and balance the initial competition window size of different priority level services. Different priority services can be accessed by different probabilistic access channels to achieve the purpose of differentiated service. (3) aiming at the problem that differentiated service can not be provided according to priority level in DCF mechanism, a Backoff algorithm based on differentiated Service (DSMAC.) is proposed. By adding a priority level identifier P to distinguish different priority levels, we modify the initial competition window value of the MAC layer for low-priority services, and set the number of retransmissions according to the priority level. (4) based on ns2, the proposed MAC protocol improvement is designed and implemented, and simulation scenarios are constructed to carry out simulation comparison. The results show that the fairness between nodes of the FAEIED algorithm has been improved obviously, and the throughput has been improved due to the addition of fast access mechanism. The DSMAC algorithm can make the high-priority traffic nodes have more bandwidth. The average delay and packet loss rate are reduced.
【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
，
本文编号：2368793
本文链接：https://www.wllwen.com/kejilunwen/wltx/2368793.html
