tailieunhanh - báo cáo hóa học: " Orthogonal beamforming using Gram-Schmidt orthogonalization for multi-user MIMO downlink system"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Orthogonal beamforming using Gram-Schmidt orthogonalization for multi-user MIMO downlink system | Matsumura and Ohtsuki EURASIP Journal on Wireless Communications and Networking 2011 2011 41 EURASIP Journal op . http content 2011 1 41 WirelessCommunications and Networking a SpringerOpen Journal RESEARCH Open Access Orthogonal beamforming using Gram-Schmidt orthogonalization for multi-user MIMO downlink system Kunitaka Matsumura and Tomoaki Ohtsuki Abstract Simultaneous transmission to multiple users using orthogonal beamforming known as space-division multipleaccess SDMA is capable of achieving very high throughput in multiple-input multiple-output MIMO broadcast channel. In this paper we propose a new orthogonal beamforming algorithm to achieve high capacity performance in MIMO broadcast channel. In the proposed method the base station generates a unitary beamforming vector set using Gram-Schmidt orthogonalization. We extend the algorithm of opportunistic SDMA with limited feedback LF-OSDMA to guarantee that the system never loses multiplexing gain for fair comparison with the proposed method by informing unallocated beams. We show that the proposed method can achieve a significantly higher sum capacity than LF-OSDMA and the extended LF-OSDMA without a large increase in the amount of feedback bits and latency. Keywords Multi-user MIMO Gram-Schmidt orthogonalization Space-division multiple-access SDMA 1 Introduction In multiple-input multiple-output MIMO broadcast downlink systems simultaneous transmission to multiple users known as space-division multiple-access SDMA is capable of achieving very high capacity. In general the capacity of SDMA can be considerably improved in comparison with time-division multipleaccess 1 because of multiuser diversity gain which refers to the selection of users with good channels for transmission 2 3 . The optimal SDMA performance can be achieved by dirty paper coding DPC 4 however implementation of DPC is infeasible since it requires complete channel state information CSI and high computational .

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