合作式自動重傳請求使用投機式束波成形

Abstract

針對於合作式通訊上在解碼傳送與放大傳送的兩個協定上使用合作式自動重傳投機式束波成形來探討錯誤率與有效的傳送資料量，藉由錯誤率的分析可知，在解碼傳送的協定上，使用兩個最佳的接力端幫助傳輸可到達的錯誤率與使用所有解碼成功的接力端來幫助傳輸是幾乎一樣的。然而，針對於放大傳送的協定而言，假設全部可用的接力端為M個，使用一個最佳的接力端與全部使用所有的接力端的錯誤率有M!倍的差距。因此，我們探討使用i個最佳的接力端來傳輸的效能與使用所有接力端的效能，此外，我們利用錯誤率分析的結果，來分析合作式重傳機制在時間上與空間上的自由度，最後可知，對於解碼傳送協定，使用type-IV 的機制可以得到最好的傳送資料量，而針對放大傳送協定，是要使用更多的接力端才可以增加傳送資料量。

The outage probability and effective throughput of cooperative automatic request for retransmission (ARQ) are investigated for opportunistic cooperative beamforming using i relays (OC-BF-i) for decode-and-forward (DF) and amplify-and-forward (AF) protocols. According to the outage analysis, the outage performance of the proposed opportunistic cooperation schemes of using the two relay nodes is almost indistinguishable from that of using all decoding relays. However, the cooperative scheme with total relays number M for AF protocol has M! SNR offset gap between opportunistic relaying and using all relays transmission. Thus, we also discuss the outage performance for AF OC-BF-i. Motivated by outage result, cooperative ARQ schemes are developed for opportunistic cooperative beamforming for these two protocols to exploit the spatial and temporal cooperative diversities simultaneously. Analysis shows that the effective way to improve throughput is using type-IV ARQ scheme for DF OC-BF scheme. For AF OC-BF, the throughput can be more effectively improved by using more best relays.