Scheduled multi gate polling (SMGP) algorithm for delay reduction of long reach PON based access network

In open access optical network with point to multipoint structure needs active components to cover large number of users in a wide area. Requirement of more active components increase the network cost significantly. To cover large range congregation of point to multipoint networks is one of the solutions that reduce the network deployment cost. This idea offers the long-reach passive optical network (LR-PON) concept with 100 Km spanning open access network (OAN) with less active components. The LR-PON produces large propagation delay that may appreciably increase the overall transmission delay. To solve this delay problem in the LR-PON, multi-thread polling (MTP) scheme is one of the remarkable solutions. However, in the conventional MTP schemes over-granting is a serious limitation to make the system more effective. In this paper, we propose a new DBA algorithm for the LR-PON system, named scheduled multi Gate polling (SMGP) algorithm. This SMGP algorithm provides new Gate messages scheduling with proper grant sizing of each ONU that provide fairness of services and delay diminishing principles. Performance of the proposed algorithm is compared with that of the existing MTP and single thread polling (STP) algorithms in terms of end-to-end packet delay for different distance spanning and offered loads, cycle time variation and throughput. In simulation results we found that the SMGP algorithm provides lower packet delay for the case of longer distances and higher offered loads with better throughput than both the MTP and STP algorithms.