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Bandwidth assignment is a key issue in optical access networks, so an efficient mechanism is required for dynamic distribution of limited resources in the uplink channel among competing subscriber optical network units (ONUs). This paper presents a novel optimized dynamic bandwidth allocation (ODBA) algorithm for hybrid WDM/TDM passive optical networks. ODBA algorithm operates using information frame length of the subscriber's ONUs and their information arrival rate; both of these factors finalize the assigned transmission capacity to the users. The system performance under differing offered traffic loads is evaluated in terms of network throughput, average delay and channel utilization. Further, the proposed ODBA scheme is validated by performing a comparative analysis with well-known algorithms. [ABSTRACT FROM AUTHOR]

This paper presents a novel configuration for the optical access systems with dynamic bandwidth allocation (DBA) and the scheduling technique. A new DBA mechanism is proposed which is an improved version of Lightweight Optimal Wavelength Scheduling (LOWS). This algorithm has a provision of multiple priority classes with tunable upstream wavelength. In the presented Modified LOWS (MLOWS) algorithm, the scheduling cycle is segmented equally into two categories, i.e., highest priority and lowest priority information traffic. The surplus transmission capacity from the subscribers having lower bandwidth requirements is assigned to a heavily loaded subscriber optical network unit (ONUs). MLOWS computes the minimum length of the scheduling cycle and allocates that many time slots per cycle to every ONU sequentially. As the demand discrepancy is reduced the requirement for elastic storage buffers is made minimal. The performance of the system architecture and DBA scheme is extensively investigated in terms of quality of service (QOS) parameters. The simulation results show improved network performance in comparison with similar schemes. [ABSTRACT FROM AUTHOR]

With the emergence of differentiated service applications, optical access networks have developed as the most promising reliable technology for broadband access systems. One of the most critical characteristics of the access system is dynamic bandwidth allocation (DBA) which facilitates sharing of a common upstream channel for diverse categories of bursty data. It is expected that an ideal DBA mechanism shall reserve transmission resources for higher prioritized real-time applications along with a fair allocation of best effort (BE) services. This requires a provision of prioritized service class transmission on multiple uplink wavelengths in a cost-effective manner. This paper proposes a novel improved hybrid slot size/rate (IHSSR) DBA scheme that allows data traffic with three diverse priority classes to be communicated on multiple upstream wavelengths. The transmission cycle is segmented equally into two segments, in which the first section is reserved exclusively for the highest priority-expedite forwarding data traffic. On the other hand, the remaining part of the time cycle is further distributed between two services namely assured forwarding and best effort (BE) traffic. Furthermore, the proposed IHSSR algorithm computes the minimum scheduled channel length to achieve higher channel utilization. The proposed DBA mechanism is comprehensively evaluated in terms of quality of service metrics like average frame delay, throughput, average jitter, and channel utilization on varying traffic load. The simulation results indicate an improved performance from 4 to more than 20% in comparison with similar existing schemes. The range of congestion-free traffic load is also prolonged in the proposed algorithm. Thus it can be visualized that the proposed mechanism outperforms other schemes and met its objective. [ABSTRACT FROM AUTHOR]

Hybrid wavelength division multiplexed (WDM)/Time division multiplexed (TDM) virtual passive optical networks (VPONs) are considered to provide cost efficient solutions for ever increasing bandwidth requirements of next generation optical access networks. With the development in technology effective bandwidth assignment has emerged as a major concern area. In this paper a novel heavy load optimized dynamic bandwidth allocation algorithm (HLO-DBA) is proposed for the hybrid WDM/TDM VPONs. Multi point control protocol of Ethernet passive optical network (EPON) is implemented for WDM/TDM VPONs subscribers. The excess bandwidth of lightly loaded subscribers is distributed among heavily loaded users through an efficient mechanism. The proposed technique effectively utilize the idle period between the last transmitted REPORT messages from previous transmission cycle (t-1) to the first GRANT message in the current cycle (t). Optical network units (ONUs) connecting the subscribers are scheduled in such a way so as to reduce the wastage of bandwidth. Performance evaluation of HLO-DBA in terms of quality of service (QOS) metrics like throughput and average delay is done to validate the optimization of the proposed mechanism. [ABSTRACT FROM AUTHOR]

Hybrid WDM/TDM optical access network has evolved as a cost-effective solution to the higher requirements of bandwidth in the access network. Bandwidth allocation and scheduling mechanism have become critical issues in the optical access networks. In this paper, a novel upstream bandwidth optimization hybrid scheduling algorithm has been proposed in which optical network units can employ tunable wavelength for upstream transmission with a single optical source. Resources allocations have been done utilizing multi point control protocol and for wavelength scheduling the shortest length of channels have been computed. Investigation of the proposed algorithm for providing improved channel utilization has been performed and a comparative analysis has been done for validation. [ABSTRACT FROM AUTHOR]