Research On Key Technologies Of Boolean-Based Network Coding In Optical Multicast Networks

With the development of broadband networks and the continuous appearance of new muticast services, the high quality multicast services required by users are increasing. The traditional electronic IP multicast will hard to meet the future multicast requirements for the low processing speed and capability. Optical networks have characteristics of bandwith and high speed. The advantages of network coding are efficient and reliable. Introducing network coding into optical multicast networks and combining the advantages of them is a novel way for meeting the ever-increasing multicast bandwith requirement and the hight quality multicast services. However, before introducing network coding into optical networks and display their advantages, some academic and technological problems need to be solved firstly.Motivated by the communication network services requirements, the core mechanisms and key technologies of optical network coding and its applications in optical multicast networks were investigated in the paper.(1) Motivated by the requirement of realizing network coding based optical multicast, a heuristic algorithm which can be accomplished in polynomial time was presented to eatablish a network coding based two channels multicast tree in the paper. The restriction principle can ensure that the multicast tree contians minimun coding nodes. Multicast tree is the foundation of realizing network coding based multicast. (2) The linear network coding can not be implemented in optical networks without optical-electronic-optical (OEO) conversions for lacking optical random access memory and the XOR network coding is too restrictive. To introduce network coding into optical networks, a novel two-channel optical network coding scheme based on logic shift and logic XOR calculations was presented in the paper. The proposed network coding scheme can be implemented in optical multicast networks without OEO conversion and more universal than XOR network coding.(3) On the basis of the network coding based two-channel multicast tree and the optical network coding scheme, the network coding based all-optical multicast was studied in the paper. The feasibility of optical multicast was verified via optical hardware experiment, and the optical multicast performances of network coding based optical multicast and the traditional optical multicst were compared and analyzed through software simulation. This result proved that the algorithm which is employed to establish network coding based multicast tree can influence the performance indirectly.(4) The wavelength converter is too expensive to resolve wavelength conflict in WDM networks. To resolve the wavelength conflict in low cost, network coding technology was introduce into wavelength channel of WDM multicast networks in the paper. Moreover, the additional and expensive optical hardware are employed to improve the transmission security by changing phase, frequent or polarization of signals in optical networks. On the basis of the proposed network coding scheme, the network coding based encryption method which is achieved by encrypt the coding vectors was proposed and the security of the method was proved in the paper.