A development of GMSK/TDMA system with CMA adaptive array for land mobile communications

The authors describe a hardware implementation of a GMSK/TDMA (Gaussian minimum-shift keying/time-division multiple-access) communication system and show the bit error rate (BER) performance of the system. This system employs a modulation data rate of 256 kb/s and accommodates 24 users/carrier. In order to reduce the effect of multipath fading, an adaptive array which has four antenna elements is implemented using a digital beamforming concept. All signal processing is carried out by digital signal processors. In an AWGN (additive white Gaussian noise) channel, this system has a 6-dB gain in input power at a BER of 1.0*10/sup -3/ compared with the ordinary system with only one antenna. A field test shows that the gain at a BER of 1.0*10/sup -3/ becomes 20 dB in a flat fading channel.<
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