Optimized synergy between 10 Gb/s and 40 Gb/s channels on a partially transparent network

As optical networks are moving towards transparency to save expensive optoelectronic conversions, 40 Gb/s transmission technology appears on the field to meet the increasing capacity requirements. An advantage of transparent network is its independence of the bit rate and modulation format. Hence the transition from 10 to 40 Gb/s in a transparent network can be imagined as a gradual replacement of transponders working at 10 Gb/s with transponders at 40 Gb/s and the co-existence of both bit rates. In this paper we propose a routing method optimizing the exploitation of unused capacity in 40 Gb/s channels and also reducing the number of optoelectronic devices; we name this criterion ‘10/40 Gb/s synergy’. We show that routing 10 Gb/s demands at different bit rates is more performing than a routing at a fixed bit rate; we also show that the synergy minimize the number of required 40 Gb/s transponder as a function of traffic characteristics.