On supporting temporal quality of service in WDMA-based star-coupled optical networks

Abstract

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 !V 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 M/sub i/, with two parameters, the relative message deadline D/sub i/ and the maximum (total) message size C/sub i/ that can arrive within any time interval of length D/sub 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/sub i/=(C/sub i/, D/sub i/)|1/spl les/i/spl les/n) in such a way that, in any time window of size D/sub i/ slots, at least C/sub i/ slots on a wavelength channel are allocated to M/sub 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 fulfil its temporal requirement, subject to the source/destination conflict constraints. We rigorously prove the invariance properties, and the correctness, of the binary splitting scheme.