DCT-based channel estimation techniques for LTE uplink

We investigate channel estimation for long term evolution (LTE) uplink over frequency-selective fading multiple-input multiple-output (MIMO) channels. As the conventional DFT-based channel estimation algorithm used for obtaining the channel impulse response (CIR) in wide band may not be applicable in narrow band of LTE uplink, which results an irreducible error floor, we propose an novel channel estimation based on discrete cosine transform (DCT), assuming only two users transmit simultaneously in the same frequency band (or SDMA). By exploiting the properties of reference signals of each user, type I DCT can separate channel response of each user in DCT-domain completely. Then, optimal channel estimation in the linear minimal mean square error (MMSE) sense in DCT-domain is derived. Finally, the performance of the proposed channel estimation is verified via simulation.