Novel pseudorandom phase generation in transform domain communication systems

Transform domain communication system (TDCS) and wavelet domain communication system (WDCS) have been reported to have interference avoiding capability under adverse environmental conditions. These systems achieve low probability of intercept (LPI) and orthogonality simultaneously by using the pseudorandom (PR) sequences for generating the phase vector of the basic function. Conventionally, the PR phase vectors in TDCS and WDCS were generated by a maximal length binary PR sequence (m-sequence), which allows only a relatively small number of users in the systems. This paper reports a method to increase the user capacity of TDCS and WDCS by applying Gold sequence to generate the PR phase vector of the basic function. The increased user capacity of the systems based on Gold sequence is tabulated. Simulation results also demonstrate that by using Gold sequences for the PR phase generation, both TDCS and WDCS can provide a comparable interference avoiding capability with a larger user capacity, compared to those of the systems based on m-sequences in multiple access environments.