多輸入多輸出廣播通訊在傳送端沒有通道狀態的資訊 下之分集與多工增益權衡分析

Abstract

在這篇論文中，我們考慮在傳送端不知道通道狀態資訊下有兩個接收端的多天線輸入多天線輸出廣播通道，我們已經知道在假設一個輔助隨機變數U當作一個分時的變數下，它的自由度範圍是可以達到的。然而，我們覺得在假設其它U的情況下是有可能達到相同的自由度範圍以及更好的中斷機率效能。所以我們考慮了功率分流。在這篇論中是第一次證出在功率分流的情況下，自由度範圍的邊界跟分時的是一樣的。此外，對於在傳送端沒有通道狀態資訊下的多天線輸入多天線輸出的廣播通道，任何編碼方法的錯誤率效能是可以藉由相應的分集與多工增益權衡效能被嚴格測得，然後我們再去分析在傳送端沒有通道狀態資訊下多天線輸入多天線輸出廣播通道的分時之分集與多工增益權衡效能。對於功率分流，我們考慮兩種解碼器，即個別最大似然解碼器和串行干擾消除的解碼器。最後我們發現在很多情況下，功率分流條件下的串行干擾消除解碼之分集與多工增益權衡效能是優於分時的。

In this thesis, we consider a two-users MIMO broadcast channel (BC) without channel state information at transmitter (CSIT) whose exact DoF region is known to be achieved by setting an auxiliary random variable U as a time-sharing variable. Yet, it is possible that other setting of U could achieve the same DoF region with better outage performance. We consider the case of power-split scheme. It is first shown in this thesis that the outer bound of DoF region with power split is same as the DoF region with time-sharing. Moreover, as the error performance of any coding schemes for the MIMO BC without CSIT can be rigorously measured by the corresponding DMT performance, we then analyze the DMT performance achieved by the time-sharing scheme for the MIMO BC without CSIT. For the power split scheme, two decoding methods are considered, namely, the individual ML decoder and the successive interference cancellation (SIC) decoder. We find that in many cases the DMT resulting from SIC decoder for power split scheme is much better than from the time-sharing scheme.