Spread-spectrum for ISM band radio

A general method based on the concept of spherically symmetric signals, is presented for the evaluation of the average probability of error of uncoded asynchronous direct-sequence/slow-frequency-hopped spread-spectrum (DS/SFH-SS) signals, over a multipath Rician fading channel (which models indoor radio propagation in factories). The authors analyse both BFSK modulation with noncoherent demodulation and diversity by square law combining (SLC), and BPSK modulation with coherent demodulation and diversity by maximal ratio combining of the specular component (MRCSC). Power-control, and simple interleaved channel coding are employed for improving the bit error rate (BER) performance. It is found that the DS scheme is always superior