On supporting temporal quality of service in WDMA-based star-coupled optical networks
In this paper, we devise a preallocation-based single-hop wavelength division multiple access (WDMA) scheme to support temporal quality of service (QoS) 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. Depending on the tunability characteristics (tunable or fixed tuned) of the transmitters/receivers, we classify the network architecture as tunable transmitter/fixed tuned receiver (TT-FR), fixed tuned transmitter/tunable receiver (FT-TR), and tunable transmitter/tunable receiver (TT-TR). We first characterize each real-time message stream nl, with two parameters, the relative message deadline D-i and the 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 (or FT-TR) system in which the message streams from a source station are assumed to be all destined for the same destination station. Under this assumption, no source/destination conflicts may occur. We propose a preallocation-based slot assignment scheme to preallocate slots to a set of isochronous message streams, (M-i, = (C-i, D-i) \ 1 less than or equal to i less than or equal to n) in such a way 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 temporal requirement, subject to the source/destination conflict constraints. We rigorously prove the invariance properties, and the correctness, of the binary splitting scheme.
temporal quality of service star-coupled optical networks slot assignment wdm/tdma