Modulation and coding rate selection to improve successive cancellation reception in OFDM and spread OFDM MIMO systems

This paper presents a method to determine a different modulation and coding rate (MCR) to be applied by the transmitter to each MIMO data stream in frequency -selective communications to improve the performance of a successive cancellation receiver. In addition, the MCR selection method assumes a predetermined successive cancellation decoding order thus simplifying the receiver. Comparisons are made to BLAST with the same MCR level on each stream (with both equal power on each stream and different power on each stream). The "MCR selection BLAST" is tested for both OFDM and spread OFDM in a simulated 18.75 MHz channel. Simulation results for a spread OFDM system show up to a 4 dB improvement in frequency-selective channels over V-BLAST with equal power and the same MCR level on each stream. The results also show that in spread OFDM MCR selection with equal power is a viable alternative to allocating different power on each stream, but in OFDM the MCR selection with equal power performed worse than allocating a different power on each stream.