Modified hybrid slot-size/rate DBA algorithm for improving quality of services of high priority data packets of PON system

Abstract

Nowadays, real time data transmission, i.e., high priority (HP), over internet is very popular. That is why, Ethernet passive optical networks (EPONs), with the properties of low cost, high speed and high efficiency with quality of service (QoS) have become promising candidates for the next generation broadband access network. To avoid data collision and provide effective bandwidth utilization a medium access control protocol is mandatory to share the resources in the upstream transmission medium. This paper presents a new dynamic bandwidth allocation algorithm (DBA) which is the modified version of the hybrid slot-size/rate (HSSR) DBA scheme. In the HSSR scheme, total transmission window of a time cycle is divided into two parts, where 1st part is steadily divided among the optical network units (ONUs) of the network and used for the HP data traffic. This bandwidth distribution is fixed and does not depend on the traffic size in the queue of the ONUs. In contrast, in the proposed scheme, the 1st part of the transmission window is dynamically distributed to all the ONUs according to the bandwidth demand of the HP traffic of each ONU. The 2nd part of the transmission window is dynamically allocated for the BE traffic of one or multiple ONUs in both the existing HSSR and proposed schemes. The performance of the proposed scheme has been compared to the existing HSSR scheme in terms of end-to-end packet delay and bandwidth utilization. Our proposed scheme provides better bandwidth utilization and lower end-to-end packet delay for the HP data traffic in the network.