Implementation of a Multicode BLQS-CDMA Modem-Codec, in single PC board, using DSP and FPGAs

摘要

The paper summarizes the study results and the development of an hardware/firmware to implement a spread spectrum modem. This modem is part of a communication system based on an innovative access technique called Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA). The peculiarity of this approach is the utilization of Direct Sequence Spread Spectrum (SS) signals. Several SS signals, suitably synchronized can be transmitted in the same band, with negligible impairments to the signal to noise ratio of each individual signal. The main advantages of this access technique over previous conventional approaches are primarily: better utilization of the channel capacity, reduction of power requirements for transmission units, reduction of interferences to other systems. After the description of the relevant system aspects the paper deals with some aspects of the modem implementation.