Research On Dynamic Resource Allocation Based Network Coding In Optical Multicast Networks

With the development to broadband networks, emerging muticast services occupy a larger proportion of whole data traffic. The increasing requirement for the high quality of multicast services proposed the huge challenge to the traditional eletronic IP multicast.The All-optical multicast technology overcomes the limitations on transmission rate caused by optical-electric-optical convention, so it becomes a key technology supporting wide bandwidth and high speed multicasting communication. And the transmission efficiency, capacity and robustness of optical multicast network can be further improved by introducing network coding technology into all-optical multicast, so network coding technology is also considered as an effective solution for the high-bandwidth multicasting.Meanwhile, facing to personalized and diverse demand of multicast service, the networks are expected to have ability to transmit rate-variable services efficiently and flexibly. Therefore, it is suggested to further research on flexible and efficient resource allocation scheme based on network coding for multi-granularity multicast services.In order to achieve high-speed and high-efficiency multicast traffic transmission, this dissertation mainly focuses on the research on network coding mechanism and resource allocation scheme based on network coding technology and orthogonal frequency division multiplexing (OFDM) technology. The design of hardware structure is realized in physical layer, and relevant strategy on routing and spectrum allocation is planned in control layer. And proposed scheme is applied for the passive optical network to solve communication problem. The contributions of this doctoral dissertation can be summarized as follows:(1) The research on network node architecture for all-optical multicast supporting multi-granularity multicast traffic transmission. A novel all-optical OFDM network coding architecture is proposed to meet the large capacity and multi-granularity multicast traffic demand for the elastic optical network. A new spectrum allocation scheme based on OFDM technology is proposed, which can be adjusted flexibly according to rate-variable multicasting traffic. The proposed network coding node architecture is designed by all-optical devices for multi-granularity multicast traffic. It does not only support higher speed transmission, but also improves the network resource utilization efficiency, combining the advantages of all-optical processing, network coding and OFDM. The relevant simulations are implemented, and the bit error rate (BER) performance with transmitting multi-granularity multicast traffic is analyzed and compared. The simulation results verify that diverse bitrates multicast traffic demand can be transmitted successfully, and the proposed architecture is feasible. The performance depending on different spectrum allocation scheme is analyzed. In addition, considering that the practical all-optical network coding is restricted by the optical signal synchronization, the process of stretching pulse is adopted in our proposed scheme for reducing the difficulty of pulse bitwise alignment and the tolerance of misalignment enable to be improved for all-optical XOR encoding operation.(2) The research on elastic multicast resource allocation mechanism based on network coding. On the basis of all-optical OFDM network coding architecture, a multi-path transmission scheme based on network coding for routing and spectrum allocation is proposed for controller layer. It can not only allocate spectrum resources effectively and flexibly for various-rate multicast traffic, but also balance the network load, improve network service throughput and reduce transmission blocking rate. In this paper, RSA problem is formulated as an integer linear programming, and present a decomposition method that breaks RMLSA into its two subproblems, namely routing allocation based network coding and allocation based on most subcarriers first, which are solved sequentially. Simulation experiments are carried out to analysis transmission performance with proposed RSA scheme. The simulation results show that the proposed RSA mechanism can allocate spectrum resources efficiently and flexibly for multi-granularity multicast traffic. Compared with RSA schemes based on shortest path tree and minimum spanning tree, the proposed RSA scheme is more efficient for spectrum resource utilization and load balancing, and spectrum resource is saved more than20%.(3) The research on all-optical network coding multicast mechanism applying to passive optical network (PON). An all-optical OFDM network coding scheme is proposed for peer to peer communication in all-optical virtual private network (VPN). The proposed scheme supports full-duplex communication mode for VPN communication between inter-ONUs, and mproves the transport security. The feasibility of all-optical OFDM network coding multicast scheme for VPN in PON system is verified. The proposed scheme satisfies the demand of higher-rate VPN traffic transmission, and various-rate traffic can be transmitted by adjusted the number of subcarriers and the rate of subcarrier. More flexible multi-granularity multicast traffic transmission and spectrum allocation are supported by proposed scheme.