TAILIEUCHUNG - Báo cáo hóa học: " Research Article Multiple CFOs in OFDM-SDMA Uplink: Interference Analysis and Compensation"

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 Multiple CFOs in OFDM-SDMA Uplink: Interference Analysis and Compensation | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 909075 14 pages doi 2009 909075 Research Article Multiple CFOs in OFDM-SDMA Uplink Interference Analysis and Compensation Malte Schellmann and Volker Jungnickel Fraunhofer Institute for Telecommunications Heinrich-Hertz-Institut Einsteinufer 37 10587 Berlin Germany Correspondence should be addressed to Malte Schellmann schellmann@ Received 1 July 2008 Revised 14 November 2008 Accepted 11 March 2009 Recommended by Erdal Panayirci In OFDM-based space division multiple access SDMA systems multiple users are served by a multiantenna base station simultaneously on the same frequency resources. In the uplink each user s signal may be distorted by an independent carrier frequency offset CFO which impairs the orthogonality of the subcarrier signals and if not properly compensated results in performance degradations. We analyze the influence of multiusers CFOs on the signal transmission in the OFDM-SDMA uplink and derive suitable bounds for the achievable signal-to-interference conditions. By modifying the signal model suitably we develop a simple scheme for partial compensation of the CFO distortions. It allows to maintain the subcarrier-wise channel equalization and thus is well suited to be applied for a real-time system implementation. However as CFOs impair the cyclic structure of the OFDM symbols our scheme is not able to compensate for the entire distortion. The remaining interference is treated as additional noise which limits the supported size of the CFOs. Copyright 2009 M. Schellmann and V. Jungnickel. 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 promising solution to lead wireless communication systems toward high spectral efficiencies is the .

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