Bit-Level List Generation for Iterative MIMO Receivers

The list demapper has been widely employed for coded multiple-input multiple-output (coded-MIMO) receivers, where only a list of signal vectors is examined in the calculation of likelihood ratio. In the literature, the search of list is operated in the symbol level in accordance with a search metric defined as a function of signal (symbol) vector. Since a signal vector is mapped from a group of (coded) bits, the search may be operated in the bit level if the search metric is made from the aspect of bit. In this paper, beginning with the study of a posteriori probability of bit, a bit-level list generation is proposed for iterative coded-MIMO receivers. With the information coming out of decoder, promising bit tuples can be searched in a low-complexity way, and then mapped to signal vectors for the calculation of likelihood ratio. By the complexity analysis and performance simulation, the proposed bit-level list generation is shown to have a good performance-complexity tradeoff over other existing methods.