Research On The Constructions Of Frequency Hopping Sequence Sets With Low-hit Zone

Different to the design of normal frequency hopping sequence, the design of low hit zone frequency hopping sequence required low value of hamming correlation function within correlation zone. The meaning of low hit zone frequency hopping sequence sets is that even though the relative time delay existed between the trans-missions of frequency hopping sequences, as long as the relative time delay is within a certain zone, the number of hit between different sequences is still keep in a very low level, so it can reduce the mutual interference. Low hit zone frequency hopping sequence can be used to design TH/FH CDMA system, which has potential appli-cation in UWB TH-CDMA system, multi-user radar, sonar system and so on. In recent years, many domestic and overseas researchers have devoted to design the frequency hopping sequences with good performance and a large number of optimal or almost optimal frequency hopping sequence sets were obtained. However, the results about the low hit zone frequency hopping sequence sets are limited. In this thesis, we will take a in-depth study on the construction of low hit zone frequency hopping sequence sets. Our achievements are as follows:1. A general method of construction of optimal frequency hopping sequence sets with no hit zone is presented, which is a generalization of several known con-structions. The parameters of frequency hopping sequence sets obtain by this method reach the theoretical bound. In the proposed construction, the length, the number of the sequences and the length of the no-hit zone can be changed flexibly. Furthermore, the available concrete construction methods are abound-ing.2. Based on the matrix permutation, a general method of construction of frequency hopping sequence sets with no-hit zone is presented. Using the proposed method, frequency hopping sequence sets with flexible maximum hamming correlation value can be obtained, so sequence sets with lower hamming correlation value and longer no-hit zone can be obtained by setting hamming correlation value.3. Two general methods of construction of frequency hopping sequence sets with low-hit zone and flexible maximum hamming correlation value within a certain low-hit zone is presented. Using the proposed methods, frequency hopping se- quence sets with lower hamming correlation within longer low-hit zone can be obtained. In addition, the optimal correlation properties of the two construc-tions is analyzed.