Sequence Pair Correlation Theory In The Application Of OCDMA System Research

Optical code division multiple access (OCDMA) system, with the advantages of highconfidentiality, strong anti-interference ability, is a kind of communication mode has goodprospects for development. Whether address code word has good correlation properties andlarge size capacity will directly affect the performance of the system. But the existingoptical address codes of the relevant characteristics and the capacity is always there is ashift in the yard contradiction. Therefore, to find a good correlation property also has alarge capacity address code become a research hotpot. To address this problem, this paperintends to use the idea of quasi-synchronous CDMA system referenced to OCDMA system,namely the use of zero correlation zone (Zero correlation zone, ZCZ) concept allows thesystem to maintain synchronization of one or several code words around, combined withsequence pair’s theory, greatly increasing the capacity of the system address code. Forenhanced correlation issues, drawing on the idea of complementary sequence, applied tosequence pairs, on the basis of relevance to ensure increased capacity codeword.Firstly, this paper deeply studies the basic concepts of sequence pairs and theautocorrelation function transformation properties, and draws the thoughts of sequencepairs to study ZCZ sequence pairs’s basic concepts and transformation properties of thecorrelation function. Finally on the base of the combination of the two concepts, studyperiodic and aperiodic ZCZ complementary sequence pair of basic concepts andtransformation properties. Research work on the whole article has played a guiding role inthe theory.In-depth study of the relevant theory, research three kinds of ZCZ complementarysequence pair construction method, namely the left-sub construction method, element-crossover based construction method and interleaving method based construction method.Among them, the left-sub construction method is based on the cycle complementarysequence pairs segmented left with certain conditions, get a new sequence pairs with zerocorrelation zone properties. Element-crossover based construction is based on ZCZcomplementary sequence pairs carried element-crossover to get greater length of ZCZcomplementary sequence pairs. Interleaving methods based construction method, learnfrom interleaving method which is more mature in the sequence study, apply to theconstruction method of sequence pairs, and constructed ZCZ complementary sequencepairs with zero correlation zone based on cycle complementary sequence pairs. Finally, study the construction of ZCZ sequence pairs used the interleaving methodwhich has described in detail. And construct OCDMA system model containing N users,carry out the theoretical research of using ZCZ sequence pair as address codes for datatransmission, the result proves that using ZCZ sequence pair as the address code forOCDMA system can effectively inhibit the multi-user interference (Multi-user interferenceMUI), and eliminates the beat noise in transmission.