A study on channel estimation methods for MC-CDMA systems

In this paper, we propose a novel channel estimation method for time-domain spreading multi-carrier code division multi-carrier code division multiple access (MC-CDMA) systems. In time-domain spreading MC-CDMA systems, code-multiplexed pilot symbols are transmitted consecutively in both time and frequency domains. In our proposed method, weighted pilot symbols in both domains are coherently added to improve signal-to-noise ratio (SNR) of pilot symbols in channel estimation. However, the channel estimation quality degrades when the weights of pilot symbols are not selected appropriately according to the changes of propagation environments. We propose a method which the optimum weighting factors for pilot symbols are adaptively selected according to the changes of propagation environments, by measuring maximum Doppler frequency for the time domain and delay spread for the frequency domain at MS (mobile station). We evaluate our proposed method by computer simulation, and clarify improvement of channel estimation accuracy.