The performance of GMSK as a modulation scheme for direct sequence CDMA

The processing gain of a direct sequence spread spectrum communications system using GMSK modulation is analysed. Multiple access interference is considered, rather than broadband white noise. Monte-Carlo methods are used. It is shown that the processing gain in a GMSK based system is lower than is possible in an equivalent system using QPSK. It is further shown that this processing gain need not be lost if adjacent systems are allowed to overlap in frequency. The optimum time-bandwidth product is found to be between 0.1 and 0.2.<
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