Design And Performance Research On MAC Layer In OFDM-PON

In recent years, the bandwidth demands of access network growth rapidly. And existing passive optical network (PON) which based on time division multiplexing access (TDMA) technique can not meet these demands. In order to meet the demands of high bandwidth and multi-service access, a novel PON namely orthogonal frequency division multiplexing (OFDM)-PON is proposed and discussed.Firstly, this thesis introduces the advantages, elaborates the composition and operation principle, and expounds some key techniques of MAC layer in OFDM-PON. After analyzing the advantages and disadvantages of existing algorithms, a novel dynamic bandwidth allocation (DBA) algorithm namely fixed cyclic polling cycle (FCPP) DBA algorithm is proposed, which supports multi-service and guarantees QoS. The improved algorithm uses two-level scheduling mechanisms: intra-priotity and inter-priotity. In intra-priotity allocation, bandwidth pre-request mechanism is uesd to reduce delay of expedited forward (EF) service, proportional allocation mechanism is used to balance priority and fairness between assured foeward (AF) service and best effort (BE) service. In the inter-priotity allocation, and smallest bandwidth request allocated first principle is used to guarantee bandwidth allocation fairness among ONUs in the same priority. A simulation is conducted to study the performance of PCPP-DBA algorithm in OFDM-PON. The results show that, compared with the traditional DBA algorithms, FCPP not only meets QoS requirements excellently but also adapted OFDM-PON better with higher bandwidth efficiency and lower algorithm complexity. This paper is divided into five chapters.In the first chapter, this paper has investigated and analyzed the current OFDM-PON researching background and situation, domestic and international research development. Chapter 2 generenlly introduces OFDM-PON. In the following chapter 3, introduces existing DBA algorithms and discuss its Advantages and disadvantages. In chapter 4, we proposed a novel DBA algorithm namely FCPP and research its performance. Finally in Chapter 5, the whole paper is summarized.