Variable-bandwidth optical paths: comparison between optical code-labelled path and OCDM path

In a conventional wavelength-routed network, the bandwidth of one wavelength is considered as the minimum granularity for a given connection request. Therefore, no multiple connection requests can be accepted by using a single wavelength simultaneously. This may cause inefficiency in the bandwidth utilization in some cases. In this paper, the focus is on the variable-bandwidth approach called an optical code (OC)-based path to improve this bandwidth utilization. The concept of OC-enabling paths is investigated, which shows its potential in resolving the above granularity problem inherent to the wavelength-routed network. First, two optical paths, called the OC-labeled and OC division multiplexing (OCDM) paths, are proposed. The former is based upon label switching and statistical multiplexing, while the latter is based upon OCDM. Next, OC-label and OCDM optical cross connects are described to support OC-labeled and OCDM paths, respectively. In this paper, a coherent time-spread OC is adopted. A two-state flow-fluid traffic model is addressed and regarded as the general analysis model. Finally, the performances between these proposed paths are qualified and compared, and numerical results show that the OC-labeled path outperforms the OCDM path under short burst duration time, whereas the OCDM path, provides higher flexibility than the OC-labeled path, owing to its independence of burst duration time.