Wavelength-aggregation Scheme with Delay-based Frame Distribution Technique for Incrementally Upgrading TWDM-PON toward 5G Beyond

This paper describes a novel wavelength aggregation scheme that we propose. The scheme aims to incrementally upgrade time and wavelength division multiplexing passive optical networks (TWDM-PONs), with the aim of enabling future networks to function effectively. Mobile base stations are split into central units/distributed units (CU/DUs) and remote units (RUs). The optical link between the CU/DUs and the RUs is known as mobile fronthaul (MFH). Future networks that rise above fifth generation networks will need to deploy a huge number of RUs. Thus, quite a few optical fibers will be needed. Accordingly, TWDM-PONs enable MFH to be constructed cost effectively. However, mobile systems tend to upgrade their data rate incrementally up to the standardized maximum data rate in response to user traffic demand. Thus, both upgraded and non-upgraded CU/DUs co-exist in a mobile system at the same time. Therefore, TWDM-PONs have to upgrade their maximum data rates to enable the CU/DUs to be upgraded without stopping any transmission from other CU/DUs that were not upgraded in the PON branch. For this purpose, we propose a wavelength-aggregation scheme with a delay-based frame distribution technique that satisfies the MFH latency requirement. Unlike other schemes, this scheme can upgrade TWDM-PON data rates without stopping any other traffic. Numerical simulations demonstrated that the scheme can provide seamless upgrading that satisfies the MFH latency requirement with a minimized number of wavelengths, one that is less than the upper limit defined in the TWDM-PON specification.