Technical Program

Paper Detail

Paper:	SPCOM-P4.7
Session:	OFDM Channel Estimation
Time:	Tuesday, May 16, 16:30 - 18:30
Presentation:	Poster
Topic:	Signal Processing for Communication: Multi-carrier, OFDM, and DMT communication
Title:	Adaptive Channel Shortening Equalization for Coherent OFDM Doubly Selective Channels
Authors:	John Kleider, General Dynamics, United States; Xiaoli Ma, Auburn University, United States
Abstract:	In this work we propose a new adaptive channel shortening tech-nique for doubly selective (time-varying multi-path) Orthogonal Frequency Division Multiplexing (OFDM) channels. OFDM is considered to be a very bandwidth efficient wireless transmission technique (due to its tightly packed orthogonal sub-carrier struc-ture) for multi-path channels. Transmissions in multi-path chan-nels exhibiting long delay spread channels, however, require an excessively long cyclic prefix (CP) to prevent inter-symbol inter-ference (ISI) with OFDM, and thus undesirably reduce the band-width and power efficiency of the information transmission. Channel shortening equalization (CSE) is used to shorten the chan-nel delay spread to a certain length (less than the CP length) so that ISI is minimized. Our technique adapts to channel variation and provides a significant bit error rate (BER) improvement in performance over non-adaptive techniques. We show that the adaptive technique improves the demodulated BER by greater than a factor of 10, with diversity order 1, in a mobile long delay spread (frequency-selective) channel, while the non-adaptive method exhibits a BER floor at 0.1.