在車速影響下正交分頻多工系統中空間多工與 空間分集技術之比較

Abstract

在MIMO-OFDM系統中，分為提供高資料傳輸率的空間多工或提供傳送分集的空間分集兩種方法。本論文根據IEEE 802.16e所規定的資料格式，在各種車速下，觀察使用Alamouti’s空時碼與使用空間多工下效能的變化。並對於空時方塊碼在時變通道下，造成正交特性被破壞，提出並列式干擾消除與排序式連續干擾消除等方法，來改善相鄰天線間干擾造成的錯誤率。 在兩傳兩收系統中，我們以相同的頻譜效率(比如:空時方塊碼一個符元由2m個位元組成會等同於空間多工一個符元由m個位元組成)，在不同車速的環境下，用電腦模擬來比較空間多工(例如：最大概似法則、零強制法、最小平方平均誤差,V-BLAST)與空間分集(例如：空時方塊碼,空時方塊碼-並列式干擾消除法,空時方塊碼-排序式連續干擾消除法)錯誤率的表現。

In MIMO-OFDM systems there are two methods,which can offer high data rates through spatial multiplexing or transmit diversity using spatial diversity.In this thesis,the systems are based on the IEEE 802.16e specifications,we observe the change of the performance using Alamouti’s space-time codes(STC) and spatial multiplexing scheme in the high vehicle speed channel.And for the space-time block code,the orthogonal properties is destroyed in the time-varying channel,so we propose two algorithms,which are Parallel Interference Cancellation(PIC) and Ordered Successive Interference Cancellation(OSIC),to improve the bit-error rate from the inter-antennas interference(IAI). In the 2x2 systems,in the same spectral efficiency(e.g. the space-time block code technique with a modulation scheme transmitting 2 bits per symbol has the same spectral efficiency as the spatial multiplexing scheme with a modulation transmitting bits per symbol.),we use computer simulation to compare the bit error rate performance between the spatial multiplexing(e.g.ML,ZF,MMSE,V-BLAST) and spatial diversity(e.g.STBC, STBC-PIC, STBC-OSIC).