A novel dynamic bandwidth allocation algorithm in optical access systems

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.