Digital subcarrier cross-connects (DSXCs)

Digital subcarrier cross-connect (DSXC) is a circuit switching node which offers bandwidth flexibility, improved transmission performance, and electric power efficiency in transport networks. In contrast to the time division multiplexing-based optical transport network (OTN) architectures, DSXC makes use of frequency division multiplexing to perform cross-connection operation of individual subcarrier channels, which can be established to provide end-to-end dedicated circuits with flexible data rates between edge node pairs. By leveraging digital subcarrier multiplexing (DSCM), spectral guard-bands between adjacent channels are not necessary in DSXC, thus yielding good bandwidth efficiency when multiplexing subcarrier channels onto the same wavelength. In addition, digital signal processing (DSP) algorithms can be implemented to perform compensation of fiber transmission impairments in the electronic domain, thus ensuring good signal integrity. As discussed in this paper, the power consumption needed by DSXC to perform subcarrier channel cross-connection operations is estimated to be approximately one third of that required by today´s OTN digital cross-connects. As illustrated in a companion paper [1] multiple DSXCs can be arranged together to build digital subcarrier optical networks (DSONs), which is a promising energy efficient alternative to currently available transport network solutions, e.g., OTN/SONET/SDH/MPLS-TP. This paper introduces the concept, the basic building blocks and the key functionalities of DSXC.