Adaptive LDPC codes for MIMO transceiver with adaptive spectral efficiency

Abstract

By using a multi-rate low density parity check (LDPC) code, we propose an LDPC coded multiple-input multiple-output (MIMO) transceiver with adaptive spectral efficiency which allows data transmission in wireless networks at rates near the channel capacity with arbitrarily low probability of error. Equipped with multiple transmit and multiple receiver antennae, the proposed LDPC coded MIMO transceiver can maximize either coding gain with space-time diversity technique or channel capacity with space-time multiplexing technique. Since the proposed multi-rate LDPC code is constructed based on a single master parity check matrix using a row-removing approach, a single universal encoder (decoder) suffices to handle all rates. Thus, the proposed approach makes the proposed scheme feasible in a subscriber station, such as a cellular phone, to maximize the total channel capacity with a guaranteed quality-of-service. The simulation results indicate that an LDPC coded MIMO transceiver with a spectral efficiency of 1, 2, 3, 4, and 5 bits/symbol/Hz can achieve extremely reliable transmission in a Rayleigh fading channel at the signal-to-noise ratio (SNR) per bit of −2.5, 0.25, 2, 4.75, and 6.5 dB, respectively, when two transmit and two receiver antennae are used for space-time diversity.