Multi-rate QR-MDD for High Data Rate Transmission in Nomadic Local Wireless Access

In this paper, we propose a new MIMO algorithm for giga-bps data transmission. To reduce computational complexity and the decoding latency, a 3-stage receiver algorithm, namely multi-rate QR-MDD is proposed. The MIMO receiver consists of multi-dimensional detection, partial interference cancellation and the weighted zero-forcing equalization, where transmit antennas are divided into two group. The first group is transmitted using lower modulation level and lower code rate and the MDD (multi-dimensional detection) algorithms is used for demodulation and decoding, while the second group is transmitted using higher modulation order and higher code rate and the WZF algorithms is used. Once the first group is decoded, they are cancelled out from received signal for demodulation and decoding of the second group. The complexity and the error rate performance are investigated and compared with MLD (Maximum Likelihood Detection) and ZF (zero forcing). The error performance is slightly worse performance than that of MLD. And computational complexity viewpoint of the required number of real multiplications is approximately 2 times the complexity level of ZF.