Efficient Impairment-Constrained 3R Regenerator Placement for Light-Trees in Optical Networks

Yi Zhu, Xiaofeng Gao, Weili Wu, Jason P. Jue
2011 Journal of Optical Communications and Networking  
Light-trees can efficiently guarantee point-tomultipoint connection in optical networks for many widely used multicast applications, such as Internet protocol television (IPTV). The establishment of a light-tree requires the placement of 3R regenerators along the tree due to the wavelength continuity constraint and physical impairments. Thus, the problem is to establish a light-tree and to assign wavelengths such that the number of regenerators is minimized. We call this problem the efficient
more » ... lem the efficient 3R regenerator placement (ERP) problem. If we fix the routing of the multicast tree, then how to place a minimum number of regenerators and assign wavelengths to links becomes a subproblem of ERP, which is named the wavelength assignment and regenerator placement (WARP) problem. We find that ERP is NP-hard, and then provide an approximation algorithm named SPT-ReWa, which has a subroutine named ReWa which can solve WARP optimally. We prove that ReWa can find an optimal solution for WARP, and we analyze the approximation ratio of SPT-ReWa for ERP. Finally, we illustrate several simulation scenarios to show the efficiency of SPT-ReWa.
doi:10.1364/jocn.3.000359 fatcat:hb2q7l5f2rayfee2lcwc3zzsci