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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: Research Article Delay Optimization in Cooperative Relaying with Cyclic Delay Diversity | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 736818 9 pages doi 10.1155 2008 736818 Research Article Delay Optimization in Cooperative Relaying with Cyclic Delay Diversity Slimane Ben Slimane Bo Zhou and Xuesong Li Radio Communication Systems Department of Communication Systems The Royal Institute of Technology KTH Electrum 418 164 40KISTA Sweden Correspondence should be addressed to Slimane Ben Slimane slimane@radio.kth.se Received 1 November 2007 Accepted 5 March 2008 Recommended by J. Wang Cooperative relaying has recently been recognized as an alternative to MIMO in a typical multicellular environment. Inserting random delays at the nonregenerative fixed relays further improve the system performance. However random delays result in limited performance gain from multipath diversity. In this paper two promising delay optimization schemes are introduced for a multicellular OFDM system with cooperative relaying with stationary multiple users and fixed relays. Both of the schemes basically aim to take the most advantages of the potential frequency selectivity by inserting predetermined delays at the relays in order to further improve the system performance coverage and throughput . Evaluation results for different multipath fading environments show that the system performance with delay optimization increases tremendously compared with the case of random delay. Copyright 2008 Slimane Ben Slimane et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION A practical method called cooperative communications has been proposed recently in order to approach the theoretical limits of MIMO technology 1 . Mobile units or relays cooperate by sharing their antennas so as to create a virtual MIMO system 2 thus enabling to exploit diversity and .
