Breadth first algorithms for APP detectors over MIMO channels

Abstract

Abstract-For iterative decoding of multiple antenna systems concatenated with an outer error correcting code, it is important to use an a posteriori probability detector for the MIMO detection to achieve near capacity performance. To avoid full APP detection, we propose a reduced complexity detector based on breadth first algorithms. Although these algorithms are suboptimal, we show that they can provide a good list of candidates for the APP calculation. Furthermore, by exploiting the a priori information delivered from the outer decoder, it is possible to decrease the MIMO detector complexity at each iteration. Using simulation results, we will compare the performance of the proposed detectors with the list sphere detector.

An Iterative MIMO-HSDPA Receiver Based On a K-Best-MAP Algorithm

“…Since the computational complexity of (2) is exponentially in N T , we use a K-best-MAP demodulator (similar to [5], [6] …”

“…Since optimum MIMO demodulation has exponential complexity, various efficient approximations have been proposed. Among those, promising algorithms are based on sphere decoding [3]- [6] and systematic tree search [7], [8].…”

“…In Section II, we thus propose an iterative MIMO-HSDPA receiver that uses a K-best-MAP algorithm (cf. [5], [6]) for demodulation. We exploit the horizontal encoding structure by using the cyclic redundancy check (CRC) bits within each layer to further decrease the computational complexity of the K-best-MAP demodulator.…”

Performance and complexity analysis of suboptimal MIMO detectors

“…We use the breadth first M algorithm in order to obtain the list of candidates as proposed in [7]. The main idea is that the survivors with small weight can be omitted with a negligible probability of discarding the most likelihood paths.…”

“…In this paper, we propose to compare two families of suboptimal APP MIMO detectors: the soft-output minimum mean square error (MMSE) detector with a priori information [5], [6] and the list type breadth first M and T M algorithms [7]. This paper is organized as follows.…”