Assessment of an optical burst switched core node with a restricted number of simultaneous active users using the burst error loss rate

摘要

The technical superiority of spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems over traditional wavelength division multiplexing (WDM) systems in optical burst switched (OBS) networks is mainly attributed to the former's better medium access control (MAC) layer performance. Nevertheless, in order to conduct an accurate comparison, a thorough study of the physical layer performance should be involved, especially because in many cases the physical layer noise would affect the maximum achievable number of simultaneously active users. Hence, in this work, we develop a novel assessment approach that combines both MAC and physical layer capabilities by introducing a new burst error loss rate parameter. In particular, the approach targets cases with limitations on the number of simultaneous active users. Next, as an example of a noisy physical layer, the effect of phase-induced intensity noise on the number of active users in OBS/SAC-OCDMA systems is analyzed. Our analysis shows that this effect introduces a burst error rate (BurstER) in the multiple-access interference cancellation operation (not investigated before). This BurstER is an increasing function of the number of active users and hence would suppress the system MAC layer performance. Finally, assuming an ideal WDM physical layer, we employ the developed approach to present an illustrative performance comparison between OBS/SAC-OCDMA and OBS/WDM systems. The results show that OBS/SAC-OCDMA performance outperforms that of OBS/WDM when the number of tolerated bits in error per burst exceeds a certain value.