A wavelength reusing/sharing access protocol for multichannel photonic dual bus networks

In a multichannel photonic dual bus network, each of the unidirectional bus contains a number of channels (wavelengths) and the bus headend periodically generates fixed length slots on each of the channels. Generally, one channel called control channel is used to carry signals and the others are data channels. Each station is equipped with one fixed-transmitter and one fixed-receiver which are permanently tuned to the dedicated control channel, and n tunable-transmitters and m tunable-receivers are tunable over the entire wavelength range. For nonoverlapping traffic in network, the maximum network throughput will be achieved by applying the wavelength reusing concept. Given a set of serving traffic, a set of new traffic requests, and c data channels (wavelengths), the wavelength/receiver assignment problem [(n,m,c)-WRAP] is to assign a transmission wavelength and a receiver for each of the request such that the network throughput is maximized and the number of assigned wavelengths is minimized. In this paper, we prove that the (n,m,c)-WRAP is NP-hard. An efficient distributed wavelength reusing/sharing access protocol (DWRAP) is proposed for the (1,m,c)-WRAP. Based on the DWRAP, three different schemes are proposed for assigning the wavelength/receiver. The throughput of the DWRAP is analyzed and the performance of the three proposed schemes on the DWRAP are evaluated and compared by simulation. Simulation results demonstrate that for a limited number of wavelengths and receivers, the proposed schemes substantially improve the network throughput and access delay under general traffic demands.