Performance of filter-bank-based spreading codes for cellular and microcellular channels
Kenneth J. Hetling, G.J. Saulnier, Pankaj Kumar Das · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1997
Recently, a new class of spreading codes has been developed based upon the time-frequency duality of multirate filter bank structures. Unlike the maximal length sequences, these new codes are not limited to being binary valued. Instead, the elements of the sequences are determined by an optimization process which emphasizes certain desirable code properties. In this paper, spreading codes based upon multirate filter banks are developed for use in a cellular or microcellular channel in which partial synchronization is maintained between the users. This situation allows the cross-correlation between the codes to be optimized over a fraction of the total range of possible phase shifts between the codes. COdes are designed for an example set of channel conditions and bit error rate results are generated. These results show that the new codes perform better than conventional Gold codes.