An interference immunity decoding method for multicarrier trellis-coded SFH/16QAM

Multicarrier trellis-coded modulation is known to be effective in land mobile delay-sensitive speech communications, since it can achieve frequency diversity by multicarrier and trellis coding without interleaving. Recently, multicarrier trellis-coded 8PSK using frequency hopping (FH) has been proposed to reduce the fading correlation of the received signal and increase the error correction capability of multicarrier trellis-coded systems. In cellular communication systems, frequency reuse is employed to achieve good spectral efficiency, although it depends on the level of the cochannel interference (CCI). Interference immunity decoding methods with interleaving based on randomizing the CCI levels and adjusting the minimum Euclidean distance according to the weighted value by using the estimated CCI level per symbol have been proposed. However, the use of interleaving may cause time delays. In this paper, we propose an interference immunity decoding method for multicarrier trellis-coded slow-FH/16QAM without using interleaving. In our proposed scheme, we estimate the CCI using space symbols inserted in several slots and modify the branch metric according to the weighted value by using the estimated CCI level per symbol. Multiple carriers using frequency hopping are employed to prevent excess time delay by randomizing the interference level without interleaving. The BER performance of the proposed decoding method is investigated by computer simulation. It is shown that the proposed decoding method is effective in suppressing the effects of CCI in fading channels.