波束通道下多用戶多輸入多輸出系統之干擾抑制合併接收機

多輸入多輸出技術之發展過程已從單用戶(SU-MIMO) 系統擴展至多用戶(MU-MIMO)系統，但是在多用戶多輸入多輸出系統中，接收機的複雜度隨著天線數及用戶數量的增加而提升，由其當用戶數量提升。因此對於MU-MIMO接收機來說，低複雜度之接收機為一重要議題，而同通道間之干擾(co-channel in addition interference)也為設計接收機上一大問題，其包括同基地台傳至其他用戶之干擾，以及來自不同基地台之訊號干擾。而本文中採用干擾抑制合併接收機(interference rejection combinig, IRC)，其特點為可以對同通道干擾之訊號進行壓抑，設計上之困難點為需要知道服務用戶通道資訊及接收訊號之共變異數矩陣，本文中會介紹如何去應對其困難點。本文將通道由原本的空間域(spatial domain)轉換到波束域(beam domain)，波束域除本身存在著功率集中之特性，而此特性對於降低接收機之複雜度有很大幫助，在波束通道下，由於其特性，可以透過用戶分群及波束選擇亦可以有效降低接收機複雜度。因此本文之模擬皆為在波束通道下進行模擬。結合上述之內容，本文之目標為在波束通道下，在用戶分群及波束選擇之後，採用IRC接收機進行訊號偵測，並採用共變異數矩陣估測法與選擇性通道估測法，在系統性能不下降太多之情況下，降低接收機之複雜度。

關鍵字

干擾抑制合併接收機；共變異數矩陣估測法；選擇性通道估測法

並列摘要

Multi-user multiple-input and multiple-output (MU-MIMO) technology has been used popularly in wireless communication systems because of it’s superior benefit. However, the complexity of the receiver increases exponentially with the number of users Therefore, low complexity receiver for MU-MIMO systems is an important research topic. Another important issue is the co-channel interference which includs the inter-cell interference and intra-cell interference. In this thesis, we propose to adopt the interference rejection combining (IRC) receiver, because the IRC receiver is simple and can effectively suppress the inter-cell interference.. In order to reduce the complexity of receiver, we propose some simplified IRC receivers over beamspace. Due to the sparse property of beam channel, user grouping and beam selection method can be used to decrease the complexity of receiver. Combining with user grouping and beam selection, we try to decrease the receiver complexity using selective channel estimation and covariance estimation without trading too much systems performance.

並列關鍵字

interference rejection combining ； selective channel estimation ； covariance estimation

參考文獻

[1] U. Madhow, “Blind Adaptive Interference Suppression for the Near-Far Resistant Acquisition and Demodulation of Direct-Sequence CDMA Signals” IEEE Transactions on Signal Processing, Pages: 124 – 136, 1997, Vol. 45.

[2] L. Rugini; P. Banelli; S. Cacopardi, “A Full-Rank Regularization Technique for MMSE Detection in Multiuser CDMA Systems” IEEE Communications Letters, Pages: 34 – 36, 2005, Vol. 9.

[3] M. L. Honig, U. Madhow, and S. Verdu, “Blind adaptive multiuser detection,” IEEE

Trans. Inform. Theory, vol. 41, pp. 944–960, July 1995.

[4] Yusuke Ohwatari; Nobuhiko Miki; Takahiro Asai; Tetsushi Abe; Hidekazu Taoka, “Performance of Advanced Receiver Employing Interference Rejection Combining to Suppress Inter-Cell Interference in LTE-Advanced Downlink”Vehicular Technology Conference (VTC Fall), 2011 IEEE, pp. 1–7.

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波束通道下多用戶多輸入多輸出系統之干擾抑制合併接收機

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