tailieunhanh - Báo cáo hóa học: " Impact and Mitigation of Multiantenna Analog Front-End Mismatch in Transmit Maximum Ratio Combining"

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: Impact and Mitigation of Multiantenna Analog Front-End Mismatch in Transmit Maximum Ratio Combining | Hindawi Publishing Corporation EURASIP Journal on Applied Signal Processing Volume 2006 Article ID 86931 Pages 1-14 DOI ASP 2006 86931 Impact and Mitigation of Multiantenna Analog Front-End Mismatch in Transmit Maximum Ratio Combining Jian Liu 1 2 Nadia Khaled 1 3 Frederik Petre 1 Andre Bourdoux 1 and Alain Barel4 1 Interuniversity Microelectronics Center IMEC Wireless Research Kapeldreef 75 3001 Leuven Belgium 2 Department ELEC-ETRO Vrije Universiteit Brussel 1050 Brussel Belgium . Department KULeuven ESAT INSYS Kapeldreef75 3001 Leuven Belgium 4 Department of ELEC Vrije Universiteit Brussel VUB Pleinlaan 2 1050 Brussel Belgium Received 20 December 2004 Revised 23 May 2005 Accepted 27 May 2005 Transmit maximum ratio combining MRC allows to extend the range of wireless local area networks WLANs by exploiting spatial diversity and array gains. These gains however depend on the availability of the channel state information CSI . In this perspective an open-loop approach in time-division-duplex TDD systems relies on channel reciprocity between up- and downlink to acquire the CSI. Although the propagation channel can be assumed to be reciprocal the radio-frequency RF transceivers may exhibit amplitude and phase mismatches between the up- and downlink. In this contribution we present a statistical analysis to assess the impact of these mismatches on the performance of transmit-MRC. Furthermore we propose a novel mixed-signal calibration scheme to mitigate these mismatches which allows to reduce the implementation loss to as little as a few tenths of a dB. Finally we also demonstrate the feasibility of the proposed calibration scheme in a real-time wireless MIMO-OFDM prototyping platform. Copyright 2006 Hindawi Publishing Corporation. All rights reserved. 1. INTRODUCTION High-throughput HT wireless local area networks WLANs of the fourth-generation the physical PHY and medium access control MAC layer of which is currently being standardized in the IEEE .