A WDM ring MAN architecture with traffic distribution and collisions avoidance for bandwidth utilization enhancement

In this paper we study a wavelength division multiplexing multi-ring metropolitan area network architecture with a separate control wavelength and a finite number of access nodes. Each access node is equipped with a fixed tuned transmitter and a fixed tuned receiver for control information exchange. Also, each access node has a tunable transmitter to exploit all data wavelengths while it uses a set of parallel tunable receivers providing suitable tuning time and range to cover all data wavelengths. Our study focuses on the critical problem that many access ring protocols introduce, of limited fiber bandwidth utilization especially at high offered loads. Thus, an efficient slotted access algorithm is applied to avoid data channel collisions and destination conflicts. Also, a multiple transmission buffer architecture is introduced at each node with an effective buffer selection for transmission scheme that combines the priority criteria of receiver collisions avoidance with data packet delay optimization. In this way, significant performance improvement is managed reducing the dropping probability and the total delay experienced, while maximizing throughput. Thus, our network strategy not only manages high scalability and maintenance, but also it achieves maximum bandwidth utilization. A discrete event simulation model is developed to evaluate performance measures.