Impact of node architecture in the power consumption and footprint requirements of optical transport networks

We evaluate and compare the power consumption and the number of required slots (footprint) of fixed and flexible transport nodes. The node architecture is assumed to comprise a grooming structure, and a reconfigurable optical add/drop multiplexer (ROADM). Fixed grooming is achieved using cascades of muxponders. Alternatively, flexible grooming is achieved with electrical switches. Fixed frequency and fixed direction ROADM, and colorless and directionless ROADM are considered. For all the architectures, we present an accurate dimensioning model that allows computation of the required modules. Results show that to optimize the total power consumption and footprint of the network, the architecture of each node has to be selected according to the amount and pattern of the add/drop and regenerated traffic and the number of pairs of fibers convergent to the node. An optimization method based on simple rules for node type selection is proposed.