Sequence Design For Direct Sequence Spread Spectrum Communication System

Spread spectrum communication system has many advantages such as good security, low probability of being intercepted and captured, strong anti-jamming ability and multiple-access communication ability and so on. Owing to the above advantages, spread spectrum communication system has been widely used in modern military communications, satellite communications, mobile communications and command-control communications. Direct sequence spread spectrum (DS-SS) system is the most widely used and its technology is the most mature in spread spectrum communication system. The preference of the spread spectrum sequences decide the inter symbol interference (ISI) and multi-access interference (MAI) in DS-SS system to a large extent. Therefore, the investigation of sequences' properties and their constructions are the core technologies in DS-SS system. In this thesis, we study the sequences design for DS-SS system. The main contributions of this work are as follows:1. For odd n, the cross-correlations between GMW sequences and WG sequences (decimated WG sequences with one particular exponent) and that of WG sequences are investigated in detail. Moreover, the maximum magnitude of the cross- correlation between GMW sequences and WG sequences are given. Furthermore, the cross-correlation of WG sequences can be 3-valued or 5-valued under a certain condition.2. A new family of binary sequences with low correlation property is constructed for odd n and even n, respectively. The new sequence sets are proved to have not only large linear span but large family size as well.3. A new family of p-ary sequences with low correlation property is presented. It is proved that the proposed sequence set has not only large linear span but also large family size.4. Two new methods of constructing zero correlation zone (ZCZ) sequence set with large family size from an known one are presented. Compared with the original ZCZ sequence set, the proposed sequence sets have longer period, larger family size, and wider zero correlation zone. In addition, we present two new methods for constructing ZCZ sequence set from an arbitrary perfect sequence and unitary matrices.5. A novel construction method of ternary two dimensional array sets having a rectangular zero correlation zone is presented. The new class of array sets have rectangular zero correlation zones for both periodic and aperiodic correlation functions. The member size of the proposed two dimensional array sets is close to the methmatical bound, and its performance parameter is almost optimal.6. A construction of ternary two dimensional array sets having a cross-shaped zero correlation zone is presented. The new class of array sets has a cross-shaped zero correlation zone for both periodic and aperiodic correlation functions.