寬頻分碼多重擷取系統之全數位MMSE多使用者接收機:演算法及其FPGA實現

Abstract

部分平行干擾消除(partial PIC)是一個簡單但有效率的多使用者偵測 (multi-user detection) 的方法，對部分平行干擾消除來說，部分消除因子(PCF)是一個重要的影響因素，通常都是利用嘗試錯誤的方式找到最佳的PCF值。在本篇論文中，我們提出一個適用於寬頻分碼多重擷取(W-CDMA)系統的兩級最小均方差(MMSE)多使用者接收機，利用MMSE的運算法則可以導出最佳的PCF值。在模擬的結果中顯示出，使用所推導出的PCF值可以改善偵測的效能，另外配合使用碼追蹤迴路(code tracking loop)可以讓多使用者接收機更完整。最後，以FPGA的設計流程實現所提出來的低複雜度接收機。

The partial parallel interference cancellation (PIC) is known to be a simple yet effective multi-user detection scheme. However, the partial cancellationfactors (PCF), being critical to the partial PIC, are usually obtained by trial and error. In this thesis, a two-stage minimum mean square (MMSE) partial PIC for the W-CDMA system is proposed. Using the scheme, the optimal PCFs can be theoretically derived. It is shown that the detection can be greatly enhanced using the derived PCFs. The code tracking loop can be incorporated into the partial PIC structure and this results in a complete mutli-user receiver. Finally, a low complexity receiver architecture is proposed and implemented using a FPGA design flow.