基於多入單出天線及正交分頻多工傳輸之單細胞分時雙工蜂巢式系統之研究

Abstract

本篇論文主要分為兩個部分。第一部分，我們研究基於多入單出天線及正交分頻多工傳輸(OFDM)的單細胞(single cell)分時雙工(TDD)蜂巢式系統，並與單載波傳輸(single carrier)做比較，我們使用的通道模型是Veh-A通道，其操作的頻段為2GHz。在我們的系統中，基於頻域(MRC/MRT)及時域(RAKE/Pre-RAKE)訊號處理，上行和下行架構同時被提出來並經由模擬檢驗，在上行傳送端我們使用廣義正交碼(generalized orthogonal code)作為領航訊號與資料合併傳輸，接收端則使用匹配濾波器(matched filter)來估計通道，以及最大比值合併(MRC)與犁耙式接收機(RAKE)和平行式干擾消除(PIC)來偵測資料，在下行傳送端我們使用上行估計的通道來做最大比值傳輸(MRT)與預先犁耙式(Pre-RAKE)編碼，接收端將接收訊號轉至頻域即可直接偵測資料。在模擬當中，所使用的模擬參數是根據第三代合作項目第八版本(3GPP, Release 8)，模擬結果顯示，正交分頻多工傳輸之位元錯誤率(BER)會比單載波傳輸好。 第二部分，基於一個資源區塊(resource block)傳輸，我們提出了一種通道估計的方法，傳送端在頻域將上行的資料與隨機領航訊號合併傳輸，接收端則使用相關器(correlator)來估計通道，以及最大比值合併和平行式干擾消除來偵測資料。模擬結果顯示，在八根接收天線及兩位使用者同時傳輸的情形下，正交分頻多工傳輸之位元錯誤率可以達到〖10〗^(-2)。

In this thesis, it is mainly organized for two parts. In part I, a single cell TDD cellular system based on MISO antennas and OFDM transmission is studied and we compare its performance with single carrier. We use Veh-A channel model and operate at 2GHz. In our system, both uplink and downlink transmission schemes are examined by computer simulation based on signal processing in frequency domain (MRC/MRT) and time domain (RAKE/Pre-RAKE). In uplink direction, we use generalized orthogonal code as pilot sequence combined with data at transmitter. At receiver, we use matched filter to estimate channel, maximum ratio combining, RAKE receiver, and parallel interference cancelation to detect data. In downlink direction, we use the estimated channel from the uplink receiver to do maximum ratio transmission and Pre-RAKE precoding at transmitter. At receiver, we can directly transform the received signal to frequency domain to detect data. In our simulation, we use the system parameters according to Release 8 of 3rd generation partnership project. It can be observed that the bit error rate performance of OFDM is better than single carrier from our simulation result. In part II, we propose a method to estimate channel state information based on one resource block transmission. In this scheme, we use random pilot sequence combined with data in frequency domain at transmitter. At base station receiver, we use correlator to estimate channel, maximum ratio combining and parallel interference cancelation to detect data. It is observed that the bit error rate performance of OFDM could achieve 〖10〗^(-2) under the condition of eight receive antennas and two users.