QoS Based Algorithms for Efficient Bandwidth Utilization in NG-Epon

Abstract

Bandwidth demand of access subscribers is increasing rapidly, so upgradation of access networks is essentially required. An effective network solution for access is desired that can deliver higher data rates for differentiated services. More than one and half decade of extensive work is done on Passive Optical Networks (PON). Ethernet PON, a different PON variant that can provide diversified and modern services and applications. Next-Generation EPON is an upgradation of EPON for accomplishing higher traffic rates, larger covered area and more flexible wave length channels. Next-Generation EPON is a technology which can handle enormous bandwidth and effective distribution requirements for prospective Internet based services. Standardization procedures for NG-EPON are in progress. Transmission of traffic from subscribers Optical Network Unit (ONU) towards central office Optical Line Terminal (OLT) in NG-EPON is carried out through four wavelengths each op erating at a data rate of 25Gbps. Dynamic wavelength and bandwidth allocation (DWBA) algorithms are needed for efficient arbitration of the bandwidth resources between the subscribers. In this research, we have proposed different DWBA al gorithms for NG-EPON; DWBA-I, DWBA-II and BASAC-DWBA. DWBA-I is a Quality-of-Service based algorithm that has been designed to manage the differ ent types of data traffic in NG-EPON. DWBA-I is based on the achievable sys tem requirements of NG-EPON. DWBA-II is an algorithm designed to meet the system requirement specifications of NG-EPON and handle traffic requirements of subscribers in a cost effective manner. DWBA-II is based on the achievable operational requirements of NG-EPON. DWBA-I and DWBA-II algorithms are comparatively analyzed and evaluated with existing DWBA algorithms. Perfor mance of DWBA-I and DWBA-II has been evaluated through the implementation of simulation models. DWBA-I and DWBA-II performs better than the different existing DWBA algorithms in terms of packet delay, completion time and packet drop ratio. NG-EPON is considered to be the only future prospective access technology that could help to achieve 100Gbps data rates. Wavelength bonding is a phenomenon Abbreviations xiv that can help ONUs to enhance their transmission capabilities. Using wavelength bonding an ONU could transmit on multiple wavelength channels in parallel. ONUs can achieve data transmission rates of 25Gbps to 100Gbps. In upstream direction, ONUs share different available channels in time-sharing manner to effec tively utilize the resources in NG-EPON. DWBA algorithm is required for efficient utilization of wavelengths and bandwidth resources in upstream direction. DWBA plays a vital role to help ONUs for transmission on multiple channels simultane ously. To achieve data rates of 50, 75 or 100 Gbps an ONU would be allocated 2/3/4 wavelength channels respectively. When an ONU transmit on multiple chan nels, a frame-rearrangement problem would occur at OLT. OLT has to bear an extra overhead of frame-rearrangement because the received frames at the OLT are not in their original sequence. DWBA could help to minimize frame rearrangement overhead. Balance Assured Single Allocation Channel (BASAC) DWBA is a pro posed algorithm that could alleviate frame rearrangement problem and provides efficient wavelength and bandwidth utilization in NG-EPON. BASAC-DWBA re duces frame-rearrangement problem, ensures the fairness in allocation and also provides efficient resource utilization. We comparatively analyzed and evaluated BASAC-DWBA with existing SCAP-DWBA. The simulation results show that our proposed DWBA alleviates frame-rearrangement problem as compared to ex isting DWBA algorithm and proves to be more efficient based on average packet delay and average completion time.