瑞利衰落信道下SRARQAMS传输性能建模分析.docx

硕十学位论文
摘 要
为了提高无线通信系统的数据传输速率和传输质量,现在都广泛地采用物理层自适应调制编码(AMC)与链路层自动请求重传(ARQ)技术相结合的跨层设计,这种传输系统能够在保证传输质量的前提下大大提高系统频谱利用率。本文
在瑞利(Rayleigh)衰落信道模型下,对基于选择自动请求重传()技术的自适应调制系统的传输性能进行了分析研究,完成的主要工作和创新概括如下: 首先,针对Rayleigh衰落信道,对结合选择自动请求重传(SR—ARQ)技术的自适
应调制系统()的系统模型和传输原理进行了分析,并构造了一个有限状态Markov链来描述Rayleigh衰落信道和自适应调制系统,求得了各调制模式的状态转移概率。其次,将影响系统性能的因素参数化,利用等效时延的思想, 建立发送端带有休假的M/G/1排队模型,考虑了经有限次传输未成功分组的服务时延对系统时延性能的影响,求得了该系统的主要时延性能指标分组平均等待时延和分组平均服务时延的解析式。通过数值模拟分析了各系统参数对时延性能的
影响,进而得到了提高系统传输速率的方法。 Rayleigh衰落信道下能获得更好的系统时延性能。最后,,将分组传输的信道状态和缓存中等待传输的分组数结合考虑建立新的扩展的Markov模
型,求得了系统各状态的稳态分布和分组丢失率的解析式;考虑到实际通信系统中缓存区容量是有限的,,利用嵌入Markov链的思想,。通过仿真对系统的分组丢失率的解析式进行验证,并分析了各系统参数对系统分组丢失率的影响,得到提高系统传输能力的有效方法。
关键字:;有限状态Markov模型;排队模型;平均服务时延;嵌入
Markov链;分组丢失率
—AMS传输性能建模分析
Ab stract
The cross—layer design bining of adaptive modulation and coding with truncated ARQ is now extensively adopted to enhance data rate and quality of transmission in munication systems,which increases spectral efficiency a lot under the premise of ensuring the quality of this paper,a adaptive modulation bined with SR-ARQ is analyzed over Rayleigh fading channels, the main works and innovations of this dissertation are generalized as follows:Firstly, the transmission scheme and the system model of SR·-ARQ—-AMS over Rayleigh fading channels is finite-state Markov chain modeled for describing Rayleigh fading channels and adaptive modulation ,parameterize the factors affecting the system performance and establish a queuing model with vacations by using the equivalent service delay system’S main
performance measures,such as system’S average waiting delay time and average service delay time are gained,which take into account the delay of lost packet transmitting limited affluence of various system parameters on system delay is analyzed by numerical simul