Maximum periodic correlation of pseudo-random sequences in CDMA

Abstract

The article presents the comparison of the Welch, modified Welch, Sarwate and Sidelnikov lower bounds on the correlation of CDMA codes. It is shown that the modified Welch bound is the best general bound known, while for codes whose symbols are roots of unity, the Sidelnikov bound is tighter. It appears likely that these bounds are nonoptimal for larger number of codes in a code set, and that there is still place for further improvements.