A high performance long-reach passive optical network with a novel excess bandwidth distribution scheme

• We propose new cycle-control slot structures and a distributed MAC over LR-PON.
• The control slot is routed through an (N + 1) × (N + 1) SC to resolve the long propagation problem.
• The decentralized MAC shows a three-order-of-magnitude improvement in delay performance.
• The previous Q-DBA (queue-weight-based-DBA) distributes most excess bandwidth to the malicious ONU.
• The proposed P-DBA (profit-weight-based-DBA) guarantees very low delay performance even when under attack.

Long-reach passive optical networks (LR-PONs) have been considered to be promising solutions for future access networks. In this paper, we propose a distributed medium access control (MAC) scheme over an advantageous LR-PON network architecture that reroutes the control information from and back to all ONUs through an (N + 1) × (N + 1) star coupler (SC) deployed near the ONUs, thereby overwhelming the extremely long propagation delay problem in LR-PONs. In the network, the control slot is designed to contain all bandwidth requirements of all ONUs and is in-band time-division-multiplexed with a number of data slots within a cycle. In the proposed MAC scheme, a novel profit-weight-based dynamic bandwidth allocation (P-DBA) scheme is presented. The algorithm is designed to efficiently and fairly distribute the amount of excess bandwidth based on a profit value derived from the excess bandwidth usage of each ONU, which resolves the problems of previously reported DBA schemes that are either unfair or inefficient. The simulation results show that the proposed decentralized algorithms exhibit a nearly three-order-of-magnitude improvement in delay performance compared to the centralized algorithms over LR-PONs. Moreover, the newly proposed P-DBA scheme guarantees low delay performance and fairness even when under attack by the malevolent ONU irrespective of traffic loads and burstiness.