基于实测的WLAN系统导频位置优化设计

Pilot Position Optimization Design of WLAN System Based on Experiment

针对IEEE 802.11ac"利用前导序列符号+梳状导频"的帧结构,推导出基于最大似然估计的校正方案性能评估公式。基于该公式分析了导频位置选择、信道衰落及子载波间相关性对校正性能的影响。提出了一种信令交换方式,可以实现收发端优化导频位置同步,并根据信道响应的幅度信息,设计了一种低复杂度的导频位置优化的方案,能够在保证性能不损失的情况下,节省导频开销。仿真与实测的结果显示,对于理想瑞利信道数据,校正性能在信道幅度信息未知和已知的情况下分别提升1.85 d B和7.15 d B;对于实测信道数据,则分别提升1.67 d B和2.68 d B。

Considering the frame structure of IEEE 802.11ac with ＂leading preamble plus comb-like pilot＂, the performance evaluation formula of the correction scheme based on maximum likelihood estimation was derived, according to which the effect of pilot location, channel fading and subcarrier correlation was studied. Furthermore, a signalling exchange method was proposed, which ensured pilot position synchronization on both end, and a low complexity algorithm of pilot optimization according to the frequency channel amplitude information. In this way, the pilot overhead can be reduced without loss of correction performance. The experiment and simulation result shows that for ideal Rayleigh channel data, correction performance improves by 1.85 dB and 7.15 dB for unknown channel amplitude information in frequency domain and known cases respectively. For field experiment channel data, correction performance improves by 1.67 dB and 2.68 dB respectively.