【作者】 张海涛；

【导师】 张晓敏；

【作者基本信息】 山东大学 ， 通信与信息系统， 2011， 硕士

【摘要】 近几年,随着无线通信技术的飞速进步,IEEE 802.11无线局域网迅猛发展,无线局域网以其组网方便,移动性和可扩展性好,传输速率较高等优点被广泛应用于社会各个领域。与此同时,无线局域网在各种不同环境下的性能也成为人们关注的焦点。IEEE 802.11无线局域网采用共享的无线信道进行传输,无线传输信道的不可靠性决定了无线局域网的性能会受到冲突、干扰等各种因素的影响,因此对于无线局域网性能的研究具有重要的意义。目前,对于IEEE802.11无线局域网性能的研究普遍使用二维马尔可夫链模型。为提高分析模型的精确性,本文考虑网络传输过程中的实际环境因素影响,在已有分析模型的基础上,给出了分析非理想信道非饱和状态下IEEE 802.11 DCF’性能的改进的二维马尔科夫链模型,用该模型对IEEE 802.11 DCF访问机制进行分析,求出饱和吞吐量表达式,并对非饱和系统中吞吐量与到达率的关系进行分析,其次考虑重传次数和退避阶数对网络性能的影响,在原有模型的基础上对其进行分析,计算出不同的重传次数与退避阶数的饱和吞吐量,最后用NS仿真分别验证了其准确性。更多还原

【Abstract】 In the recent years, with the rapid progress of wireless communication technology, the Wireless Local Networks (WLANs) have achieved a tremendous amount of growth. Wireless Local Area Network technology is widely used in all areas of society and becomes more and more popular because of its convenience, mobility and extendibility. At the same time, people have focused more attention on the performance of the Wireless Local Networks under any different environments.Because of the data transmission of IEEE 802.11 WLANs using a wireless channel, its unreliability decides that the performance of WLANs will be affect by a variety of collisions and interfere. So the research of performance has become more and more important.The most of research of WLANs base on Bianchi’s Bidimensional Markov Model at present. In order to improve the accuracy of analysis, this paper, considering impacts of practical setting in the process of transmission, proposes a improved bidimensional Markov chains model for estimating the performance of IEEE802.11 DCF for a non-ideal channel in non-saturated conditions and then, using the improved model, analyzes the performances of IEEE802.11 DCF Wireless LANs, deriving the expressions of the saturation throughput. Then using the model above, the relationship of non-saturated throughput and arrival rate is analyzed. Secondly, considering the impacts of backoff and retry depends on the original model and get the saturated throughput about the different backoff and retry. In the end, the results from the model are verified by Simulation.更多还原