Reducing frequency reuse distance in cellular communications using trellis coded modulation

Co-channel interference is of great concern when planning modern cellular communication systems. The commonly used seven-cell frequency reuse pattern is based on the fact that the carrier to interference ratio (C/I) should be higher than 18dB, which is based on subjective tests (W.C.Y. Lee, 1995). A scheme based on trellis coded modulation (TCM) is proposed which enables the system to perform satisfactorily even at reduced levels of C/I. The proposed scheme gives the flexibility to use four or three cell repeat patterns, thus substantially increasing the spectral efficiency of the system. The scheme proposes the use of different TCMs in the different co-channel cells. Simulation results have shown that for a four-cell repeat pattern, the proposed scheme resulted in a bit error rate of 10^-5 or better, with an outage probability of 0.86%.