Impairment-aware dynamic RWA algorithm in multi-granularity WDM optical networks Yongmin Qi * (1), Yi Zhu (2), Tianshu Wang (1), Xuefang Zhou (1), Sheng Qian (1) and Qiliang Li (1) 1: College of Communication Engineering, Hangzhou Dianzi University, Hangzhou, P. R. China, 310018 2: Dept. of Computer Science, the University of Texas at Dallas, Richardson, TX 75080, USA ABSTRACT In practical multi-granularity WDM optical networks, optical signals will be degraded due to impairments mainly introduced by a number of multi-granularity optical cross-connects (MG-OXC) and fiber links. Even worse, transmission impairments will make the bit-error rate to be unacceptable. We investigate the impact of transmission impairments on optical signal quality in multi-granularity WDM optical networks. A novel dynamic impairment-aware RWA algorithm is proposed based on the presented transmission impairments model. We also evaluate the proposed algorithm in the serial cascaded MG-OXCs network and the interconnecting MG-OXCs network by simulations. Keywords: Multi-granularity, routing and wavelength and waveband assignment (RWA), transmission impairment 1. INTRODUCTION Multi-granularity switching and routing have been proposed and studied as a cost-effective solution to manage hundreds of wavelengths in the backbone network using wavelength division multiplexing (WDM) technology [1-3]. Compared with traditional optical cross-connects (OXCs), multi-granularity optical cross-connects (MG-OXCs) may handle three switching granularities including fiber, waveband and wavelength. Coarse switching and routing granularities efficiently reduce the ports of the switch, and hence the total complexity and the cost of the WDM optical network are lower. In practical optical networks, the quality of optical signal is degraded by transmission impairments induced by non-ideal transmission. After transmitting along the lightpaths, some optical signals may not be detected by the receivers at the destination MG-OXC node due to poor powers, or the received bit-error-rate (BER) is too high to be accepted. Therefore, intelligent RWA algorithms, which consider the effects of impairments in three-stage MG-OXCs WDM optical networks, need to be developed. * ymqi@hdu.edu.cn (Yongmin Qi ); Phone +8657186919123 Network Architectures, Management, and Applications VI, edited by Weisheng Hu, Shao-Kai Liu, Ken-ichi Sato, Lena Wosinska, Proc. of SPIE Vol. 7137, 71373D © 2008 SPIE · CCC code: 0277-786X/08/$18 · doi: 10.1117/12.804196 Proc. of SPIE Vol. 7137 71373D-1 2008 SPIE Digital Library -- Subscriber Archive Copy