Interference parameters of concatenated spreading sequences for asynchronous CDMA

Concatenation of sequences is a simple way to construct longer sequences from shorter ones. In this article, the average interference parameter of concatenated sequences (also known as Kronecker sequences) is derived as a function of the interference parameters of the inner and the outer sequences. Bounds on the average interference parameter are given. Although the peak correlation parameters of families of concatenated spreading sequences are rather poor compared to those of 'linear' families of sequences of the same length (e.g. Gold-sequences), it is shown that the interference parameters are not worse. Moreover, the structure of concatenated sequences can be used to reduce receiver complexity and to speed up code acquisition in the high SNR-region. Additionally, families of concatenated sequences can be constructed with a greater flexibility in the choice of the parameters (size of the family, length of the sequences) than 'linear' families.