Multi-Carrier Distributed WDM Ring Network Based on Reconfigurable Optical Drop-Add-Drop Multiplexers and Carrier Wavelength Reuse

Abstract

This paper presents and experimentally demonstrates a multi-carrier distributed wavelength-divisionmultiplexing (WDM) ring network based on reconfigurable optical "drop-add-drop" multiplexers for regional and metro network applications. In the "drop-add-drop" network, optical carriers generated by a centralized multi-carrier light source (MCLS) are "dropped" at the source nodes and used for uplink transmission. Data are "added" to the network by external modulation of one or more carriers. Data are then "dropped" at the destination nodes. The reconfigurable optical add/drop multiplexer (ROADM) at each access node is not only used to "add" and "drop" data, but also to "drop" carriers, which eliminates the many distributed laser-diodes used in the conventional network. In this work, we successfully demonstrate, for the first time, a "drop-add-drop" network experiment offering 10 Gbit/s WDM transmission. Moreover, to dramatically improve the utilization efficiency of the carrier wavelengths distributed by the MCLS in the "drop-add-drop" network, we introduce the carrier wavelength reuse technique which sets the carrier extraction circuits in each access node. This technique enables us to reuse the carrier wavelengths that were already utilized for data transmission between prior source and destination nodes. To evaluate the effect of carrier wavelength reuse, we compare the blocking probabilities of the "drop-add-drop" networks with and without carrier wavelength reuse. The results show that wavelength reuse dramatically reduced the blocking probability. In addition, we numerically analyze the advantages of the "drop-add-drop" network over the conventional ROADM network in terms of network cost and power consumption.

A routing and wavelength assignment scheme in multi-carrier-distributed optical mesh networks with wavelength reuse

“…Furthermore, it was reported that the WRMD network is superior to the conventional network in terms of network cost and power consumption on ring topologies in [2]. An example of the WRMD network with mesh topology, as shown in Fig.…”

“…For cost-effectiveness analysis [2], the cost of the single LD, C LD , is defined to equal c cost units. The costs of the WSS, all-optical carrier extraction (ACE), and MLCS are defined as C WSS , C ACE , and C MCLS , respectively.…”

“…This, unfortunately, will raise energy consumption and implementation cost. Moreover, the complexity of optical carrier management increases with the number of wavelengths [2]. In other words, it will be difficult to adequately control the wavelengths of the huge number of LDs, since each wavelength of each LD has to be adjusted individually to satisfy the extremely narrow channel space.…”

A routing and wavelength assignment scheme supporting multiple light-source nodes in multi-carrier-distributed optical mesh networks with wavelength reuse

“…As mentioned above, if the number of wavelengths is increased to increase data transmission capacity, we need to add and control more distributed LDs in the conventional WDM network. This increases the cost, power consumption, and control complexity of the network [2]. Our cost analysis presented in Appendix A, which is an extension of the cost analysis in [2], observes that the WRMD network has lower cost than the conventional WDM network if some condition is satisfied.…”

“…Moreover, these filter characteristics require a narrower channel bandwidth and tighter channel spacing. Cascading the filter components in a network narrows the filter bandwidth characteristics after each access node transit, resulting in considerable degradation of the transmission performance [2,3]. In other words, the transmission performance will be drastically degraded if the optical carrier generated by a local light source is slightly detuned because of the tuning error of the light source.…”