Implementation and field experiments of a 16QAM mobile data system based on PSAM channel sounding and TCM encoding techniques

This paper reports experimental results of a pilot symbol aided 16QAM system for land mobile communications at 1.9 GHz. To combat the multipath fading phenomena in Rayleigh fading channels, the pilot symbol assisted modulation (PSAM) channel sounding technique, trellis coded modulation (TCM), and space diversity are employed. The TCM coder, with 8 states, has the length of the shortest error event path of 2 and the product of the branch distances along that path of d_pmin²=0.8. We have also designed a two branch MRC space diversity receiver in which each branch has a channel estimation capability. As a result of field experimental measurements, we have obtained the BER=6×10^-4 at E_b/N_o=20 dB in a 16QAM system with diversity and TCM