Uplink Channel Estimation for Multi-user OFDM-based Systems

In this paper we propose a simple, yet flexible and efficient, channel estimator for the uplink in broadband Orthogonal Frequency Division Multiplexing (OFDM) systems. The processing is performed in the time-domain, by extracting the channel’s impulse response (CIR) for each user from a joint training signal. In this OFDM system, the pilot sequence we advocate, where all users share the same pilot sub-carriers, consists of one OFDM-symbol endowed with time-shifted properties per user, which isolates each user’s CIR and is robust against multi-user interference. The feasibility of our approach is substantiated by system simulation results obtained using BRAN-A broadband mobile wireless channel model.