With the advent of new internet services and the broader application of Passive Optical Network (PON) in the industry, PON, as the core technology of the 5th Generation Fixed Networks (F5G), needs to evolve and upgrade continuously to meet the needs of the future network. The latency of PON networks is a key network performance indicator that urgently needs improvement. This article conducts in-depth research on the low latency technologies in the PON networks.

This article first summarizes the challenges faced by current PON networks in terms of low latency. It identifies two main reasons for high latency: the inherent uplink delay introduced by the Optical Network Unit (ONU) bandwidth allocation mechanism and the random uplink delay introduced by the ONU registration/ranging mechanism. To address these issues, this article proposes two ultra-low latency solutions based on single frame multi burst technology and an independent registration channel, followed by experimental verification and analysis.

Analysis shows that the single-frame multi-burst approach optimally balances latency and bandwidth utilization in a quarter scheduling cycle, albeit at the expense of some bandwidth. This method is ideal for latency-sensitive, bandwidth-tolerant services. The independent registration channel solution, by dedicating an extra wavelength for ONU registration/ranging, eliminates the extra delay and jitter from silent periods in standard service channels.

The ultra-low latency solution for PON discussed in this article can effectively reduce network latency, and help promote the large-scale commercialization of emerging applications such as Virtual Reality (VR) and accelerate the growth of industrial internet.