tailieunhanh - Báo cáo hóa học: "Research Article Securing OFDM over Wireless Time-Varying Channels Using Subcarrier Overloading with Joint Signal Constellations"

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 Securing OFDM over Wireless Time-Varying Channels Using Subcarrier Overloading with Joint Signal Constellations | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 437824 18 pages doi 2009 437824 Research Article Securing OFDM over Wireless Time-Varying Channels Using Subcarrier Overloading with Joint Signal Constellations Gill R. Tsouri1 and Dov Wulich EURASIP Member 2 1 Department of Electrical Engineering Rochester Institute of Technology Rochester NY 14623 USA 2 Department of Electrical and Computer Engineering Ben-Gurion University of the Negev Beer-sheva 84105 Israel Correspondence should be addressed to Gill R. Tsouri grteee@ Received 29 November 2008 Revised 29 May 2009 Accepted 30 July 2009 Recommended by Merouane Debbah A method of overloading subcarriers by multiple transmitters to secure OFDM in wireless time-varying channels is proposed and analyzed. The method is based on reverse piloting superposition modulation and joint decoding. It makes use of channel randomness reciprocity and fast decorrelation in space to secure OFDM with low overheads on encryption decryption and key distribution. These properties make it a good alternative to traditional software-based information security algorithms in systems where the costs associated with such algorithms are an implementation obstacle. A necessary and sufficient condition for achieving information theoretic security in accordance with channel and system parameters is derived. Security by complexity is assessed for cases where the condition for information theoretic security is not satisfied. In addition practical means for implementing the method are derived including generating robust joint constellations decoding data with low complexity and mitigating the effects of imperfections due to mobility power control errors and synchronization errors. Copyright 2009 G. R. Tsouri and D. Wulich. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in