適用於多重輸出入正交分頻多工調變之空頻碼設計

Abstract

本論文主要探討在頻率選擇性衰減通道 (frequency-selective fading channel) 環境下，針對多重輸出入正交分頻多工調變 (MIMO-OFDM) 系統設計空頻碼 (space-frequency codes)。藉由使用中央極限定理，亦即當隨機變數個數達到特定數量時，機率密度函數將趨近高斯分布之特性，計算空頻碼之成對錯誤機率並提供對應之碼字設計準則，亦即秩 (rank) 準則和距離 (distance) 準則；吾人可依通道變化速度快慢之差異，將通道狀況區分為快速衰減通道 (rapid fading channel) 和類靜止通道 (quasi-static channel) 兩種，各自通道所對應之設計準則也將被討論。在詳細分析下，可知利用中央極限定理分析空頻碼所得之碼字設計法則和空時碼之設計法則相似。在系統模擬部分，將比較在討論之通道環境裡，不同設計方式所得之籬柵碼位元錯誤率的比較情形。

A space-frequency coded multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system on frequency-selective fading channel is considered. By exploiting the central limit theory that the random variables can approach Gaussian distribution, which is used when the number of random variables is large enough, we will analyze the pairwise error probability of space-frequency codes and provide the corresponding design criteria, which mean rank criterion and distance criterion. According to the channel variation speed, rapid fading channel and quasi-static fading channel are distinguished, the individual design criteria are also presented. From the code design of these case, it is deduced that the code construction of space-frequency codes is similar to the code construction of space-time codes by applying the central limit theory. The simulation results are presented to compare the various trellis code designed from various criteria in the channel environments.