On dynamically establishing and terminating isochronous message streams in WDM star-based lightwave networks

摘要

Complement to our prior work in [21], we address in this paper the problem of dynamically establishing/terminating real-time message streams in response to call setup/clear requests in single-hop star-coupled WDM optical networks. We consider a network architecture in which N stations are connected to a star coupler with W data channels (W ≤N) and one control channel. Each of the W data channels is slotted and shared by the N stations by means of time division multiplexing. The control channel is used for stations to coordinate the call establishment and termination operations. We propose a distributed, dynamic slot allocation scheme to allocate/de-allocate time slots on the W data channels to message streams, with the objective of meeting message deadlines. To facilitate slot assignment, the proposed scheme first decomposes each message stream into a set of message sub-streams, and groups the time slots on each wavelength channel into sub-channels. In response to a call setup request, the proposed scheme then allocates one or more empty sub-channels available over the W data channels to a message stream to fulfill its temporal requirement, subject to the source/destination constraints and that the temporal guarantees to existing message streams should not be violated. On the other hand, in response to a call clear request, the proposed scheme releases the slots allocated to the terminated message stream, and merges, if appropriate, empty sub-channels to facilitate future message stream establishment. We formally prove the properties, and the correctness of, the proposed dynamic slot allocation scheme.