This paper studies the off-line wavelength assignment problem in tree optical networks that use multiple fibers in each link. In the multifiber scenario, the wavelength assignment is potentially more flexible because the same wavelength can be carried simultaneously on parallel links. However, in tree networks, our results unfortunately show that multiple fibers do not fundamentally improve problem complexity nor do they decrease the worst-case bound based on the request load. For multifiber directed or undirected binary trees, we show that the wavelength assignment problem (WAP) is NP-complete. In contract, there is a polynomial algorithm for undirected single-fiber binary trees. If path lengths are restricted to at most three, WAP in dual-fiber undirected tree networks is still NP-complete whereas if path lengths are restricted to four, WAP is any multifiber directed or undirected tree network is NP-complete. Finally, we show a tight upper bound of 3L_max/(2k) wavelengths per fiber for any k-fiber undirected tree where L is the connection load.

Date Published: 5 October 2000
PDF: 8 pages
Proc. SPIE 4213, Terabit Optical Networking: Architecture, Control, and Management Issues, (5 October 2000); doi: 10.1117/12.402532

Published in SPIE Proceedings Vol. 4213:
Terabit Optical Networking: Architecture, Control, and Management Issues
John M. Senior; Sudhir Dixit; Chunming Qiao, Editor(s)