Dynamic Interleaved Slotted ALOHA: A Multiple Access Protocol for Wavelength Division Multiplexed Photonic Networks

This paper introduces a preallocation-based multiple access protocol for wavelength-division multiplexed (WDM) optically interconnected passive star-coupled networks. The objective is to combine the strengths of two other preallocation-based strategies, interleaved slotted ALOHA (I-SA) and interleaved time division multiple access with multiple buffers (I-TDMA*), while minimizing their inherent weaknesses. I-SA is a random access protocol which features good delay but poor maximum throughput. I-TDMA* is a static protocol which has excellent throughput but suffers from synchronization delay at low arrival rates. The new protocol, dynamic interleaved slotted ALOHA (DISA), is a random access protocol which combines the high capacity of I-TDMA* with the excellent latency characteristic of I-SA. This is achieved through a flow control mechanism which throttles the amount of traffic transmitted through the network based on the local load characteristics. No global information (other than packet acknowledgments) is necessary to implement this flow control mechanism; each node intelligently restricts network transmissions based only on the frequency of local packet arrivals and collisions. The protocol is described and discrete event simulation is used to compare the performance of DISA to I-SA and I-TDMA* over a range of system, load, and protocol parameters.