Design And Analysis Of Topology-Transparent MAC Scheduling Codes And Optical Orthogonal Codes

Multiple access protocols and schemes play a very important role in the multi-user communication networks, such as mobile ad hoc network (MANET), optical code division multiple access (OCDMA) network. The basic requirement of the multiple access techniques is to avoid or reduce the mutual interference between the signals as far as possible when a variety of users share common channel resource efficiently. Thus it is required to design a collection of multiple access coding signals satisfying certain characteristics. Moreover, some new application systems are required to support not only more users but also multi-class services and thus spawned some new multiple access coding problems. In this thesis, some important results are obtained by investigating the design and performance analysis of topology-transparent media access control (MAC) scheduling codes for MANET and optical orthogonal codes (OOCs) for OCDMA networks, respectively.Firstly, by using polynomials over Galois field and set partition, a construction of topology-transparent MAC scheduling code for MANET supporting multi-class services is proposed. The code length is minimized under the condition that one successful transmission slot is guaranteed for each user in lowest priority class. In MANET based on the proposed codes, the smaller the code length is, the smaller the data transmission delay will be. The proposed code has much flexibility in choosing the transmission slots and its construction is simple. The study shows that the wireless network employing the proposed MAC scheduling code can support users with multi-class services and provide guaranteed quality of services (QoS). Moreover, the proposed MAC scheduling codes outperform the MAC scheduling code based on variable-weight OOCs under certain conditions.Secondly, a multi-channel topology-transparent MAC scheduling code is proposed for MANET supporting multi-classes of users via polynomials over Galois field. The code length is derived and compared with the single-channel topology-transparent MAC scheduling code. It is shown that when the number of channel is H, the code length of the proposed MAC scheduling code is approximately H times smaller than the code length of single-channel MAC scheduling code. Thus the proposed code can reduce the code length by using multi-channels resources. Moreover, the numerical results show that under the same network parameters, the proposed MAC scheduling codes have better performance than the extended TDMA fixed assignment scheme in terms of code length, minimum guaranteed throughput, and so on.Next, variable-weight OOCs for OCDMA systems supporting multiple QoS are investigated. Four classes of optimal cyclic packing are presented explicitly based on a kind of combinatorial design. A recursive construction for optimal cyclic packing is proposed based on semi-cyclic group divisible designs (SCGDDs). By computer search, some constructions of optimal cyclic packing with small parameters are given. Based on the above results, two classes of optimal variable-weight OOCs with Hamming weights3and4are obtained. The application of the variable-weight OOCs for the design of topology-transparent MAC scheduling code is also presented.Then, four classes of optimal cyclic packing with block size{4,5,6} are constructed based on quadratic residues in number theory. By using the equivalence between optimal optical orthogonal code and optimal cyclic packing, four classes of optimal variable-weight OOCs with weight{4,5,6} are obtained and more new optimal variable-weight OOCs are obtained via recursive constructions. These improve the existing results on optimal variable-weight OOCs with at least three distinct Hamming weights and minimum Hamming weight4.Finally, a novel construction for space/wavelength/time optical code is presented by using orthogonal array (OA) and r-simple matrix (SM), which is named as OA-SM Construction. The proposed codes are with single-pulse-per-plane property and thus called three-dimensional single-pulse-per-plane code (3-D SPPC). In the literature, previously presented constructions of3-D SPPCs have maximum Hamming cross-correlation equal to one. The new constructions can produce optical orthogonal codes with maximal Hamming cross-correlation larger than or equal to one. By comparing with an upper bound of three-dimensional optical orthogonal codes, it is shown that some of the proposed3-D SPPCs are asymptotically optimal. The bit error rate (BER) performance of the proposed codes is analysed and compared with3-D SPPCs and MWOOCs in the literature. Moreover, the proposed3-D SPPCs can support more potential users in some cases, while achieving comparable performance.