Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
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 jwcn.eurasipjournals.eom 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 .
