Uplink channel estimation for OFDMA system

This paper proposes uplink channel estimation schemes for OFDMA system. If frequency responses of assigned subcarriers between corresponding users and base station (BS) are put together into one frequency selective fading channel, time domain expression of the channel, in other words, overall channel impulse response has a significant property, namely, only about the same number of elements as the length of CP have nonzero values. Based on the analysis, we propose a least square channel estimation scheme and a simple remedy for conventional channel estimation scheme. Computer simulation results show that the proposed schemes can significantly improve BER performance.