Introducing wavelength granularity to reduce the complexity of optical cross connects

In future transport networks, optical cross connects (OXC's) could optically route wavelength-division-multiplexed (WDM) signals. In order to switch a large amount of channels, OXC's should have much more complex structures, in terms of both optical components and internal controls. To cope with this, we propose to introduce optical granularity: if WDM signals with the same source-destination pair were assigned a group of adjacent wavelengths, they could be optically routed by OXC's as a single channel. This modifies usual routing and wavelength assignment, but reduces the number of optical components in OXC's and also makes it easier to configure and modify connections. Advantages are similar to those that might come from increasing electrical granularity (i.e., using fewer signals with a higher bit rate), if this option were not limited by transmission impairments.