New non-linear families of code-sequences with correlation properties better than linear families

摘要

The performance of direct-sequence code-division multiple-access systems depends on the correlation properties of the used code-sequences. In this paper, the peak and average correlation properties of binary families derived from 'Z4-linear' families of quadriphase sequences are compared to the results for well-known 'linear' families. It is shown that these families have remarkably better periodic peak correlation parameters than 'linear' families but an improvement of the average mean-square correlation properties has not been found. For increasing length, the average interference parameter tends to the expected value of the interference parameter for random sequences. Therefore, in this paper, a construction method based on linear optimization is described which results in families with low average interference parameters.