Scheduling of real-time messages in optical broadcast-and-select networks

In this paper, we consider broadcast-and-select networks based on optical passive stars. In these single-hop networks, communicating pairs can exchange messages directly, without the need to store information at intermediate nodes for later forwarding. Messages are transmitted in a packetized way, and each message has an associated deadline. In order to guarantee the message reception timeliness, we ask that all the messages are received within their corresponding deadline. We show that this scheduling problem is strong NP-complete, even in a very restricted case. Then, we turn our attention to fast approximating heuristics. We present four of them, assess their average performance by means of computer simulation, and give their worst-case performance bounds. Such bounds can be effectively used to test the success of the schedule before generating it.