多用戶多輸入多輸出廣播通道中減少通道資訊回饋之技術

Feedback Load Reduction in Multiuser MIMO Broadcast Channel

蔡玉倫(Yu-Lun Tsai)

指導教授 ： 蘇炫榮

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00856

摘要

在多用戶多輸入多輸出的下載通道系統下，如果傳送端可以知道所有使用者的通道資訊，則可以達到系統最大傳輸資料量。而當系統使用分頻雙工技術時，需要藉由每位使用者回饋來讓傳送端知道使用者群的通道資訊，如此一來會造成上傳頻寬的負擔，系統中使用者越多，所佔的頻寬會越大。在這篇論文中我們迫零波束技術使用在多用戶多輸入多輸出的下載通道系統中時，去降低使用者回饋給傳送端資訊量；在這樣的系統下，使用者所回饋的資訊可分成通道的方向資訊和通道的品質指標。我們提出一個多閾值的回饋方法，這方法中最關鍵的是利用估測訊號干擾雜訊比的秩序統計量去建立多個閾值，這些閾值不但做為量化時的代表位階，也同時用來減少回饋的資訊量。從最後模擬的結果可以知道，我們所提出的多閾值方法不但可以減少很多回饋資訊量，也可以有比傳統回饋的方法(全部使用者都要回饋）好的加總傳送資訊量。

關鍵字

多用戶多輸入多輸出(MU-MIMO) ； 下載通道 ； 迫零波束技術(ZFBF) ； 回饋通道資訊量之減少 ； 有序統計 ； 部分正交之使用者選擇(SUS)

並列摘要

We consider the downlink of a multiuser multiple antennas channel. It is
known that when full channel state information is available at the transmitter
(full CSIT), the sum capacity can be achieved. Thus, for the system which
employs frequency division duplex (FDD), this requires each user to feed back
their channel state information (CSI) to the base station (BS), which incur a
large aggregate feedback bandwidth, especially when the number of users is
large. We consider zero-forcing beamforming (ZFBF) with semi-orthigonal
user selection(SUS) in which CSI is split to channel direction information
(CDI) and channel quality indicator (CQI). We propose a novel scheme to
reduce feedback load by using the threshold-based feedback strategy. The
key feature of the proposed approach is the use of order statistic concept to
construct multiple thresholds on CQI not only to reduce feedback load but
also to be the representative levels instead of using the quantizer. We show
that by employing the proposed scheme the feedback load can be signi‾-
cantly reduced, and the sum-rate performance is better than the traditional
feedback schemes.

並列關鍵字

multiuser multiple-input multiple-output (MU-MIMO) ； down- link channel ； zero-forcing beamforming (ZFBF) ； feedback load reduction ； order statistic ； semi-orthogonal user selection (SUS)

參考文獻

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[4] N. Jindal, MIMO broadcast channels with ‾nite-rate feedback," IEEE