Effects of partial correlation on the multipleaccess capability of directsequence spread spectrum
Abstract
Nearly all previous analytical results on the performance of direct sequence, spread spectrum multiple access (DS/SSMA) communications are restricted to systems which employ a full period of the signature sequence in each data pulse. For certain applications, however, it is required to employ long signature sequences with multiple data bits per period of the signature sequence. In a DS/SSMA system with multiple data bits per period, the performance depends on the partial correlation properties of the signature sequences (rather than aperiodic correlation properties as in the case of one bit per period). In this paper, the performance of a DS/SSMA system for which the period p is greater than the number N of chips per data pulse is analyzed. The multipleaccess capability of two classes of DS/SSMA systems with N chips per bit, when the performance measure is the meansquared crosscorrelation, is compared. It is found that the multipleaccess capability is less for the class in which p and N are relatively prime than for the class with p = N (i.e., one bit/period). This is primarily because of improvements that result from the optimization of the phases of the signature sequences in the case p = N.
 Publication:

NTC '81; National Telecommunications Conference, Volume 2
 Pub Date:
 1981
 Bibcode:
 1981ntc.....2....4P
 Keywords:

 Cross Correlation;
 Multiple Access;
 Spread Spectrum Transmission;
 Electromagnetic Interference;
 Performance;
 Spectral Signatures;
 Communications and Radar