Performance of wavelength-convertible multihop optical ShuffleNets employing convolutional coding under hot-potato routing SuFong Chien Faculty of Engineering and Technology, Multimedia University, Jln Ayer Keroh Lama Bukit Beruang 75450, Melaka, Malaysia sfchien@mmu.edu.my Kenzo Takahashi and Satya Prasad Majumder Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor, Malaysia kt@mmu.edu.my, S.P.Majumder@mmu.edu.my Received 27 November 2001; revised manuscript received 4 February 2002 Performance analysis is carried out for a multihop optical ShuffleNet with full wavelength conversion to evaluate the effect of wavelength converters on the bit-error-rate (BER) and packet-error-rate (PER) performance. Computed results show that there is a significant decrease in BER with an increase in the number of wavelength converters n w for the same transmitter power. Further, an increase of n w is needed at increased network load g; for example, to achieve the maximum throughput, n w ≈ 10 and n w ≈ 20 are needed corresponding to g = 0.5 and g = 1.0. It is found that when convolutional coding is applied, the required number of wavelength converters is greatly reduced at the full load g = 1.0. © 2002 Optical Society of America OCIS codes: 060.0060, 060.4510. 1. Introduction The performance of wavelength-routed optical networks with packet switching is much affected by the packet contentions at the intermediate nodes. Wavelength conversion has been employed to reduce the blocking probability as well as the deflection probability. However, the effectiveness of the reductions depends on the network topology itself. Barry and Humblet 1 have shown that meshed topologies can achieve the largest gain by use of wavelength conversion. In packet-switching networks, packets with the same wavelength that have the desired similar output link will be converted to another wavelength to solve the contention problem. A recent study has reported that both Manhattan Street networks and ShuffleNets achieve the maximum throughput by use of at least four wavelengths with an impressive hop delay. 2 However, the required number of wavelengths will increase dramatically when the load increases. This former study has also failed to consider the physical limitations of the network system that can restrict the network-throughput performance. To view the consequence of the physical limitation, the per-hop loss-compensation system is used to evaluate the packet-error-rate and bit-error-rate (PER/BER) performance in the wavelength-conversion case. 3 In this transmission system, the power levels in the network are always kept equal, and the amplifiers are set to compensate exactly for the per-hop loss. The computed results show that in the presence of noises such as amplified spontaneous emission (ASE) and cross talk, network throughput is enhanced, but the BER/PER performance is poor. Hence we propose two methods to solve the problem mentioned above, i.e., either by increasing the number of wavelengths (n w ) or by employing forward error correction (FEC) coding in the network. However, JON 60 February 2002 / Vol. 1, No. 2 / JOURNAL OF OPTICAL NETWORKING 93