Abstract

With the arrival of 5G era, Internet traffic is growing explosively. Meanwhile, the asymmetry of traffic in upstream and downstream directions is becoming more severe. Most current network architectures are designed based on the assumption of bi-directionally symmetric traffic demands. Network capacity in the direction that carries less traffic is largely wasted. To tackle this issue, we propose a new optical network architecture that can efficiently handle bi-directionally asymmetric traffic demands. Specifically, we design a novel asymmetric colorless, directionless, and contentionless (CDC) reconfigurable add/drop multiplexer (ROADM), which can adaptively configure numbers of ingress and egress $1 \times N$ wavelength selective switches (WSSs) in each direction asymmetrically according to actual traffic demands, thereby avoiding wastage of $1 \times N$ WSSs in the direction carrying less traffic. Also, we decouple each transponder into a pair of split transmitter (Tx) and receiver (Rx), and asymmetrically configure their numbers according to actual bi-directional traffic demands, significantly reducing the add/drop cost in a ROADM. To evaluate the benefit of the proposed asymmetric network architecture, we exploit the routing and spectrum assignment problem in an optical network. A novel analytical model to evaluate lightpath blocking performance with asymmetric numbers of opposite fibers on each link of an optical network is developed. Also, efficient heuristic algorithms to target asymmetric traffic are proposed. Simulation results show that the proposed asymmetric optical network architecture can achieve significantly better lightpath blocking performance than its counterpart symmetric architecture when their total system costs are close. Furthermore, the analytical model can accurately predict the blocking performance of an optical network based on the asymmetric architecture.

Colorless, partially directionless, and contentionless architecture for high-degree ROADMs

Yongcheng Li, Jieming Lin, Liangjia Zong, Sanjay K. Bose, Biswanath Mukherjee, and Gangxiang Shen
J. Opt. Commun. Netw. 14(6) 481-492 (2022)

Low-Cost CDC ROADM Architecture Based on Stacked Wavelength Selective Switches

Haining Yang, Brian Robertson, Peter Wilkinson, and Daping Chu
J. Opt. Commun. Netw. 9(5) 375-384 (2017)

Impact of ROADM Colorless, Directionless, and Contentionless (CDC) Features on Optical Network Performance [Invited]

Yongcheng Li, Li Gao, Gangxiang Shen, and Limei Peng
J. Opt. Commun. Netw. 4(11) B58-B67 (2012)

Add/Drop Contention-Aware RWA With Directionless ROADMs: The Offline Lightpath Restoration Case

Pablo Pavon-Marino and Maria-Victoria Bueno-Delgado
J. Opt. Commun. Netw. 4(9) 671-680 (2012)

Demonstration of Quasi-Contentionless Flexible ROADM Based on a Multiport WXC

Liangjia Zong, Han Zhao, Yunfei Yan, and Zhiyong Feng
J. Opt. Commun. Netw. 8(7) A141-A151 (2016)