用於多用戶偵測接收的最小均方差平行式部分雜訊消除器

Abstract

對於分碼多工系統而言，平行干擾消除偵測器是一個簡單且有效的多用戶偵測接收器。藉由部分式平行干擾消除器我們可以更有效的改善傳統平行干擾消除偵測器的效能。對於某一個特定的用戶而言，部分式平行干擾消除器只消除部分由其他用戶所重製的干擾信號。消除的量是由部分消除因素所決定。在之前，這個值大都是藉由電腦尋找出來的，很少有相關的理論結果。 在這篇論文中，我們介紹了一個最小均方差的部分式平行干擾消除器。並且依據這個準則，導出了一個完整的數學式子用來計算最佳的部分消除因素。模擬結果證實這個值與之前的論文是相符合的，而且它不易受雜訊大小和干擾功率大小的影響，部分式雜訊消除偵測器確實比完全式雜訊消除偵測器的效能更好。

The parallel inteference cancellation (PIC) detector is an effective yet simple multiuser detector for code-division multiple access (CDMA) systems. The performance of the standard PIC can be further improved by the so called the partial PIC. For the received signal for a particular user, the partial PIC only partially cancels the interference regenerated from other users. The amount of cancellation is controlled by a partial cancellation factor. Previously, this factor is obtained by trial and error. No theoretic results were reported. In this thesis, we introduce a minimum mean square error (MMSE) criterion for the partial PIC. Based on this criterion, the closed-form solution is derived for the optimal cancellation factor. Simulations show that the optimal cancellation factor is very close to the one used in previous work. Also, the optimal factor is not sensitive to the noise level and the interferencing signal power.