AN IMPLEMENTATION OF A CMA ADAPTIVE ARRAY FOR HIGH-SPEED GMSK TRANSMISSION IN MOBILE COMMUNICATIONS

The hardware implementation of an adaptive array as a technique for compensating multipath fading in mobile communications is described. The number of the antenna elements is four. The target communication system is modulated by 256 kbps Gaussian-filtered minimum shift keying and has a time-division multiplexing architecture with 24 time slots. Based on the digital beam forming concept, all of the signals and the array weights are digital-signal processed. The constant modulus algorithm (CMA) is employed for weight optimizing. In an additive white Gaussian noise channel, this system has 5.6 dB gain in an energy-per-bit-to-noise-density ratio (E(b)/N0), at a bit error rate (BER) of 1.0 x 10(-3), compared with a single-antenna system. The result of the basic field test shows that the gain at a BER of 1.0 x 10(-3) reaches 22.3 dB in a nonselective, slow Rayleigh fading channel given a 5 Hz maximum Doppler shift. These results certify our successful implementation.