Optimum self-reference spatial diversity processing for FDSS and FH communication systems

In 1996, a new spread spectrum communication system, called Frequency Diversity Spread Spectrum (FDSS), was proposed as a system to mitigate the problems of the common spread spectrum techniques. In this paper, two blind self-reference optimum beamforming methods tailored for the FDSS signalling scheme using the trivial repetition code are derived based on the inherent cross-correlation properties present among all the frequency bands. The method is also applicable to fast Frequency Hopping (FH) systems. The proposed methods use the information of the all the frequency bins jointly to yield optimum beamforming in the sense of maximum Signal to Interference-plus-Noise Ratio (SINR). One method computes all the beamvectors jointly performing a single generalized eigenvector computation. The other calculates each beamvector independently aiming at a parallel implementation. The two methods are analytically studied and tested via Monte-Carlo simulations. They are compared to other existing methods in terms of bit error rate, outperforming them and showing a performance close to the optimum value.