Design of seamlessly and limitlessly expandable OXC and verification tests on its versatile applicability

Abstract

We propose an extremely cost-effective optical-cross-connect (OXC) architecture that allows hitless port-count expansion with virtually no limit to meet incremental traffic growth at minimum cost. This is enabled by a new interconnection scheme of optical splitters and wavelength-selective switches (WSSs) in the express-switch part and that of transponder banks in the add/drop parts. The benefit is offset by slight constraint on routing flexibility, which is minimized with a newly developed interconnection algorithm. Extensive computer simulations are carried out to verify that the proposed OXC retains satisfactory routing capability without notable penalty even though smaller-degree WSSs ( 1 × 9 ) are utilized: it is compared with present fixed-port-count OXCs using larger-degree WSSs ( 1 × 20 ), which have no hitless extension capability. The proposed OXC with the proposed algorithm can drastically reduce OXC hardware cost. We analyze node-design parameters in terms of the routing performances of the OXC and search for the appropriate values. The effects of traffic churn ratio during network expansion and the geographic traffic distribution are investigated. The results verify the effectiveness and robustness of the OXC architecture and the expansion scheme; the number of WSSs needed and the necessary component WSS port count can be greatly reduced while the resultant link fiber increment is marginal (1%–5%), compared with the ideal OXC without any routing restriction.

Metropolitan Optical Networks: A Survey on New Architectures and Future Trends

“…Transponders: Transponders are signal converters from the optical domain to the electronic domain, or vice versa. At each entrance door, there is a traffic receiving device (Rx) and at each exit door there is a traffic transmitting device (Tx) [60]. In the literature, these devices are transponders [61] and transceivers [62].…”

“…When couplers, splitters and blockers are used instead of filters, some side effects can be detected. Among them is the reduction in wavelength availability, the lower range of signals due to excessive noise and bit error rate (BER), and the accumulation of out-of-band noise generated by optical transmitters, and possible interference in adjacent channels [1], [4], [5], [7], [60].…”

“…ROADM is also called by optical cross-connects (OXCs). Since OXC is a more generic way to refer to an optical switching device, both forms, ROADMs / OXC are often used interchangeably in the literature [11], [60].…”

“…In addition, there is usually amplification at a node, to help mitigate the loss of division. Several viable ROADM and WSS architectures for metropolitan optical networks are presented in [35], [60] and [74]. Some of these architectures alter the layout of the devices on the left and right side of the figure, as is the case with the Route-and-Couple (RnC) architecture, which can be understood as the reverse of the BnS architecture, with WSSs in the left side position and S positioned on the right.…”

“…As the new OXC proposed in [60] is almost immune to traffic conditions at any point in the network, it is necessary to test the impact of the deployment of this equipment on different network architectures. It is also necessary to investigate other low-cost equipment to perform infrastructure combined updates in the metro varied segments.…”