莱斯信道下跨层系统的频谱效率分析

为提高无线通信网络在传输中的频谱利用率,提出一种莱斯信道下的跨层系统.该系统联合了物理层的自适应调制技术与数据链路层的自动重传技术.利用从接收端反馈回的信道状态信息和自动重传请求,发射端自适应调节调制模式,自动重传发射数据.推导了莱斯信道下,跨层系统的频谱效率和中断概率的封闭表达式,以及固定调制模式系统的频谱效率的表达式,并利用推导的表达式进行仿真.结果表明,对比仅有自适应调制的系统,跨层系统的频谱增益大约是1.5 dB;而与仅有自动重传的系统相比,其频谱增益最大达到3 dB.

Spectral efficiencies analysis of cross-layer system for Rician fading channels

A cross-layer system for Rician fading channels was developed to improve wireless communication network's spectral efficiencies.The system was scheduled combining multi-level adaptive modulation at physical layer with truncated automatic repeat request protocol at data link layer.The transmitter updated the modulation mode adaptively and retransmited data automatically by utilizing channel state information(CSI) and automatic repeat request(ARQ) which were fed back by the receiver.Close-form expressions of the cross-layer system and only-AM system for spectral efficiencies and the probability of outage over Rician fading channels were derived.Results show that comparing to only-AM system,the cross-layer system performance gains could achieve almost 1.5 dB,while comparing to only-ARQ system,the cross-layer system performance gains is up to 3 dB.