Performance of transmitter pre-processing assisted multi-cell IDMA system over correlated frequency-selective channel

In this letter, we evaluate the performance of coded-interleave division multiple access (IDMA) system using multi-user transmitter pre-processing (MUTP) technique for downlink communication. The MUTP, which is mainly considered to mitigate the effects of co-channel interference, is realized by singular value decomposition (SVD), which exploits the signals space of channel state information (CSI) of all the active users acquired via feedback channels. Particularly, the CSIs are estimated using Least Square Error (LSE) algorithm at each of the MSs and are vector quantized using Lloyd´s algorithm, and the bits representing the quantized magnitudes and phases are feedback to the base station (BS) through the dedicated low rate noisy channel. The quantized bits are recovered at the BS to formulate the pre-processing matrix. We also compare the performance of MUTP with minimum mean square error (MMSE) detector for the coded IDMA system. Our simulation results reveals that our considered MUTP scheme alleviates the effects of CCI with less complex signal detection at the MSs when compared to MMSE detector. Further, SVD based MUTP assisted coded IDMA system outperforms the MMSE detector in terms of achievable bit error rate (BER) with low signal to noise ratio (SNR) requirement by mitigating the effects of CCI and multi-user interference.