On supporting time-constrained communications in WDMA-based star-coupled optical networks

We devise a preallocation based single hop wavelength division multiple access (WDMA) scheme to support time constrained communication in star coupled optical networks. We consider a star coupled broadcast and select network architecture in which N stations are connected to a star coupler with W different wavelength channels. Each of the W wavelength channels is slotted and shared by the N stations by means of time division multiplexing. Networks with different transceiver configurations, i.e., TT-FR, FT-TR, and TT-TR systems, are investigated. We characterize each real time message stream M, with two parameters, relative message deadline D_i and maximum (total) message size C_i that can arrive within any time interval of length D_i . We then discuss a restricted case in a TT-FR system in which the message streams from a source station are assumed to be all going to the same destination station. Under this assumption, no source/destination conflicts may occur. We propose a preallocation based slot assignment scheme to allocate slots to a set of isochronous message streams, {M_i=(C_i, D_i))|1⩽i⩽n}, so that in any time window of size D_i slots, at least C_i slots on a wavelength channel are allocated to M_i for all i. With the solution derived in the restricted case as a basis, we then consider slot assignment in a (general) TT-TR system, and propose a binary splitting scheme to assign each message stream sufficient and well spaced slots to fulfill its timing requirement, subject to source/destination conflict constraints. We rigorously prove the invariant properties and the correctness of the binary splitting scheme