Multiple Orthogonal Sequence Subsets with Low In-Phase Cross-Correlation from the Shifted M-Sequence

Abstract

Orthogonal sequence set has good in-phase cross-correlation (IPCC) property and then receives wide application in code division multiple access communications. However, it is well known that the number of orthogonal sequences is not larger than sequence length. In order to obtain more sequences, the IPCC property will have to be decreased. In this paper, a method to increase the number of orthogonal sequences is proposed on the basis of the shifted m-sequence. By considering a given orthogonal sequence set as an original orthogonal sequence subset, multiple orthogonal sequence subsets with the same sequence length and subset size can be constructed. The combination set of these constructed orthogonal sequence subsets and original orthogonal sequence subset will possess much more sequences since the number of sequences will be increased from N to the square of N. In addition, the constructed multiple orthogonal sequence subsets satisfy that intra-subset IPCC is equal to zero and the normalized inter-subset IPCC is not larger than 0.5.