Wavelength division multiplexing-based video-on-demand systems

Serving video-on-demand (VOD) traffic via isochronous transmission service is highly desired because of the characteristics of VOD traffic. This paper proposes a mechanism to transfer VOD traffic over wavelength division mult iplexing (WDM) networks by employing isochronous transmission service. Base d on the proposed mechanism, the problem of scheduling isochronous and asyn chronous traffic for single-star WDM networks with multiple receivers and t ransmitters is investigated. The lower bounds on the total switching durati on and the number of switching modes for the isochronous and asynchronous t raffic scheduling problem are derived. An optimal scheduling algorithm is p resented for the cases where only asynchronous traffic exists; and a heuris tic algorithm is also proposed for the cases where both the isochronous and asynchronous traffic coexist in the WDM networks. Simulation results indic ate that the average switching duration and the average number of switching modes obtained by the proposed algorithm are close to the lower bounds, wh ich implies that the proposed scheduling algorithm is effective.