## Abstract

Light-trees can efficiently guarantee point-to-multipoint 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 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.

©2011 Optical Society of America

Full Article | PDF Article**OSA Recommended Articles**

Fen Zhou, Miklós Molnár, Bernard Cousin, and Chunming Qiao

J. Opt. Commun. Netw. **3**(4) 323-334 (2011)

Weisheng Xie, Jason P. Jue, Xi Wang, Qiong Zhang, Qingya She, Paparao Palacharla, and Motoyoshi Sekiya

J. Opt. Commun. Netw. **6**(3) 291-302 (2014)

Arush Gadkar, Tim Entel, Jeremy M. Plante, and Vinod M. Vokkarane

J. Opt. Commun. Netw. **6**(3) 340-354 (2014)