Design And Quality Of Several Spreading Sequence Sets

It is well-known that sequences with good periodic auto-correlation and cross-correlation functions find their applications in the field of spread spectrum communications, CDMA systems, channel estimations, synchronizations, system identifications, radar and sonar system, etc. There are many different kinds of sequences and it is clear that different applications may require different sequences with specific properties. The thesis mainly analyses some specific 2-phases spreading sequences and periodic complete complementary codes, and discusses a class of unified constructing methods for zero (low) correlation zone sequences based on ideal autocorrelation sequence and orthogonal matrix in QS-CDMA.In this thesis, the construction of complete complementary codes is emphasized. We analyse and simplify the construction of the N-phase orthogonal sequences proposed by Suehiro, give a way to generate the independent sequences without repetition. In addition, we proposed a new method to get N-phase complete complementary sets S by combining cyclically shifting multiphase orthogonal sequences and orthogonal matrix.Later, the concept of zero correlation zone (low correlation zone) is presented and the construction of sequences with such properties is proposed, too. In this thesis, we propose a class of unified constructing methods for zero (low) correlation zone sequences based on ideal autocorrelation sequence and orthogonal matrix, and their correlation properties are presented and proved. The methods suitable for QS-CDMA system, possess of both simplicity and universality. This idea, in fact, open a new direction in spreading sequence design.