Performance of joint maximum-likelihood decoding for block coded signal streams in overloaded MIMO-OFDM system

This paper presents a joint decoding scheme for block coded signals in an overloaded multiple-input multiple-output (MIMO)-OFDM system. In a normal MIMO-OFDM system, symbol detection is carried out over the signals received by multiple antenna elements and is separated from decoding. However, owing to form factor limitation, a mobile terminal may have a limited number of receive antenna elements. Instead of splitting detection and decoding, in this paper, a joint maximum likelihood (ML) decoding in an overloaded MIMO-OFDM system is investigated. Based on ideal interleaving, independence among coded symbols spread over subcarriers is assumed. Thus, the outage capacity improves even though the ergodic capacity remains the same with a single receive antenna. As an example of the proposed system, bit error rate performance of Hamming coded and spatially multiplexed signals with joint ML decoding on a Rayleigh fading channel is investigated. The error rate is evaluated through analysis and computer simulation.