Comparison of central and distributed control in a WDMA star network

The authors address key issues involved in data link control in a wavelength-division-multiple-access (WDMA) optical star network. A comparison is made between regulating data traffic from a central controller and at the individual distributed stations. The particular transmission format considered is one in which data are carried on a baseband signal and control information is carried on a multiplexed subcarrier, thereby providing a transparent data link without requiring a second optical control channel. It is shown that central control will relax the hardware and cost requirements of each station´s receiver as well as reduce the time delay in setting up a call. The specific hardware advantages for each individual station´s optoelectronic receiver when implementing a central control algorithm include a reduction in the required bandwidth and number of optical and RF filters