The Research On Dynamic Resources Allocation In OFDM-PON System

Orthogonal Frequency Division Multiplexing Access(OFDMA) has attracted great interest for research in the next generation of Passive Optical Networks(PON) due to features such as fine granularity, low cost, elastic resources allocation, whose research and development will give rise to further innovation and transformation of optical communication industrial chain. However, while different technologies share a common fiber platform for a point-to-multipoint PON technology, they often feature inherent physical layer(PHY) differences, which could pose technical and practical difficulties in dynamic, efficient and fair inter-technology resources scheduling.First of all, the typical equipment, network topology and media access control technologies of PON system are studied in this paper; and then the principal of OFDM technology and its key techniques(e.g. synchronization, channel estimation, subcarrier modulation and channel coding, etc.) are theoretically analyzed in detail; At last but not least, the objective to build an open access environment and deploy different PHY technologies over a common infrastructure is presented after elaborating on three different media access control protocols of OFDM-PON based on TDMA, FDMA and Hybrid TDMA/FDMA.A novel software-defined Meta-MAC-based solution of media access control protocol in OFDM-PON system is proposed in the premise of not modifying the original MAC sublayer protocol, which is able to provide the possibility of dynamic resources management and optimization, as well as overcome the PHY divide by the messaging interaction between Meta-MAC controller and Virtual PON(VPON). Then, a three-stage(VPON admission, bandwidth assignment and spectrum allocation) dynamic resources allocation scheme based on the design principals of Meta-MAC in OFDM-PON system is described in order to achieve dynamic management and optimization of subcarrier resources, satisfy the bandwidth requirements of various technologies or services, and enhance the user experience.Finally, the real-time simulation model of the proposed software-defined Meta-MAC-based dynamic resources allocation algorithm in OFDM-PON system is established by the OPNET Modeler software, in which the greedy algorithm is introduced to solve the VPON admission problem. The performance results of two different spectrum allocation scenarios, Compact Allocation(CA) and Scattered Allocation(SA), under the Meta-MAC-based OFDM-PON dynamic resources allocation algorithm are analyzed and compared through several parameters including subcarrier re-allocating threshold, subcarrier utilization, services satisfaction, and number of cycles until VPON admission, confirming the availability and feasibility of the solution.