Delay diversity for direct sequence spread spectrum system to reduce transmitting power in Rayleigh flat-fading channel

This paper presents a novel technique to save the transmitting power of spread-spectrum communication systems based on the application of delay diversity. The core idea of this delay-diversity system is to delay two spreading sequences that carry the same information of a bit with respect to each other in order to statistically separate the influence of fading on the same bit in time domain. The theoretical bit error rate (BER) expression of the proposed system is derived and verified by simulations. According to the numerical results, it is found that this technique save significant amount of transmitting power, and it may be used to extend the life-time of energy-constrained devices such as sensor nodes in wireless sensor networks.