無線局域網(wǎng)MAC優(yōu)化技術(shù)研究
發(fā)布時間：2018-12-08 18:18
【摘要】：隨著無線局域網(wǎng)的發(fā)展,其部署密度越來越密集,由于無線資源的有限,導(dǎo)致網(wǎng)絡(luò)信道競爭沖突增加,同時,人們對無線網(wǎng)絡(luò)的服務(wù)要求也越來越高,一些語音、視頻等實時性較強(qiáng)的多媒體業(yè)務(wù)必將越來越多。如何提高M(jìn)AC協(xié)議的傳輸性能、減少沖突的發(fā)生、提高網(wǎng)絡(luò)公平性,如何使WLAN能夠提供及時、有效、穩(wěn)定的服務(wù)質(zhì)量保障,區(qū)分不同業(yè)務(wù)提供不同服務(wù),這些問題都成為退避算法研究的重要內(nèi)容。針對以上問題,論文從提高節(jié)點之間的公平性,提高網(wǎng)絡(luò)吞吐量,以及提供區(qū)分服務(wù)為出發(fā)點,研究了無線局域網(wǎng)傳輸優(yōu)化問題。論文的主要貢獻(xiàn)有以下幾點:(1)針對BEB二進(jìn)制退避算法存在的不公平問題,提出一種提高節(jié)點的接入公平性、減少非必要退避時間的融合性退避算法FAEIED。該算法是以EIED算法為基礎(chǔ),加入一個門限值CWth,來判斷當(dāng)前信道競爭激烈程度,然后根據(jù)判斷調(diào)整競爭窗口大小。同時,在網(wǎng)絡(luò)負(fù)載較輕時,引入FCR算法的快速接入機(jī)制,降低每個競爭周期中產(chǎn)生的空閑信道時間,以提高節(jié)點接入效率,減少系統(tǒng)浪費(fèi)的退避時間,進(jìn)一步提高傳輸性能。(2)提出了一種平衡MAC協(xié)議中節(jié)點初始競爭窗口的方法。該初始競爭窗口處理方法通過對不同優(yōu)先級別節(jié)點的初始競爭窗口進(jìn)行區(qū)分設(shè)置,使高優(yōu)先業(yè)務(wù)能夠以較高的概率接入信道,平衡不同優(yōu)先等級業(yè)務(wù)的初始競爭窗口大小,使不同優(yōu)先等級業(yè)務(wù)以不同概率接入信道來達(dá)到區(qū)分服務(wù)的目的。(3)針對DCF機(jī)制中無法根據(jù)優(yōu)先級別提供區(qū)分服務(wù)的問題,提出一種基于區(qū)分服務(wù)的退避算法DSMAC。通過增加一個優(yōu)先等級標(biāo)識位P來區(qū)分不同優(yōu)先等級,采取修改低優(yōu)先級別業(yè)務(wù)的MAC層初始競爭窗值,并根據(jù)優(yōu)先等級設(shè)定重傳次數(shù),區(qū)分不同優(yōu)先級別業(yè)務(wù)退避策略來實現(xiàn)業(yè)務(wù)的區(qū)分服務(wù)。(4)基于ns2對提出的MAC協(xié)議改進(jìn)進(jìn)行了設(shè)計實現(xiàn),并構(gòu)建仿真場景進(jìn)行仿真比較,結(jié)果表明FAEIED算法使節(jié)點之間的公平性有了明顯提升,由于加入了快速接入機(jī)制,吞吐量也有一定的提高。DSMAC算法能夠使高優(yōu)先業(yè)務(wù)節(jié)點占有更多的帶寬,降低了其平均時延和丟包率。
[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.
【學(xué)位授予單位】：國防科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN925.93
，
本文編號：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.
【學(xué)位授予單位】：國防科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN925.93
，
本文編號：2368793
本文鏈接：http://sikaile.net/kejilunwen/wltx/2368793.html
最近更新
教材專著
