時間反轉空間分割多工系統的性能分析

Performance Analysis of Time-Reversal Space Division Multiple Access System

本文提出了一個下鍊時間反轉空間分割多工系統，時間反轉的架構將複雜的信號處理由行動用戶端移至基地台，我們提出了兩個前置濾波器架構：第一個前置濾波器的脈衝響應為基地台與用戶端之通道脈衝響應時間反轉，其優點為在取樣點空間與時間能量的集中；第二個前置濾波器滿足零強迫的條件，因此多用戶干擾可完全移除。此外，我們比較了直序分碼多工系統，理論與模擬結果證實了本文提出的架構具有低複雜度、高傳輸速率、具有彈性與實用性等優點。

In this paper, we propose a time-reversal (TR) downlink space division multiple access communication system. The TR scheme shifts the signal processing needs from the receiver at the radio terminal (RT) to the transmitter at the base station or fixed access point (AP), where power and computational resources are plentiful. We developed two prefiltering schemes: the impulse response of the first prefilter is a time-reversed conjugation of the channel impulse response between the AP and relevant RT. The benefit is spatial and temporal focusing, which collects energy at the sampling instant. The second prefilter meets the zero-forcing criterion such that multiuser interference is completely eliminated at the sampling instants of the relevant RT receiver. Furthermore, we compare the proposed scheme to a downlink direct sequence code division multiple access (DS/CDMA) system that is widely applied in 3G networks. Analytical and simulation results confirm that the superior features of the proposed scheme over the DS/CDMA system lie in the lower complexity, higher throughput, greater flexibility, and practicality.