From ITU News
Millions of homes and businesses access global networks through the cost-efficient Passive Optical Network (PON) technologies standardized by ITU. The next generation, known as “Higher Speed PON”, will provide for speeds of 50 Gbit/s per wavelength, up from the 10 Gbit/s of its predecessors.
ITU News spoke with Frank Effenberger, Fellow at Futurewei Technologies and Rapporteur for ITU’s working group on optical systems for fibre access networks (Q2/15), to learn more evolution of the PON market and the motivations for ITU standards’ jump from 10G to 50G.
“The first widely deployed system, G-PON [Gigabit PON], is found almost everywhere now and is used by well over 600 million subscribers worldwide,” highlights Effenberger.
But demand for higher capacity is growing fast with the rise of bandwidth-intensive services such as communication via HD video, cloud gaming and Virtual Reality. Optical access solutions will also provide essential support to IMT-2020/5G wireless communications and innovation towards smart cities and smart factories.
“What we are seeing is a gradual evolution from G-PON to XG-PON [10G PON] and XGS-PON [10G symmetric PON], which is now being deployed at scale in many countries,” says Effenberger.
“Given the large size and cost of the fixed access network, upgrades generally come once per decade.”
The development of Higher Speed PON began in 2018 and targets completion before the close of 2021.
Released in 2019, the first ITU standard of the new G.9804 series, ITU G.9804.1, served as a guide for the development of Higher Speed PON systems by defining the requirements of envisioned applications.
Currently under approval, ITU G.9804.2 specifies the common transmission convergence layer for single-channel and multi-channel 50 Gbit/s systems, and ITU G.9804.3 defines the optical requirements and specifications of the 50 Gbit/s single-channel physical media dependent layer.
Higher Speed PON looks to the future, anticipating market demand to begin in 2024.
“The PON industry has been researching such an evolution step in PON capacity for at least five years,” highlights Effenberger. “Several generations of prototype have already been developed and their results published. We know what technology is necessary.”
Higher Speed PON includes both single-channel 50 Gbit/s systems to succeed XG(S)-PON and multi-channel 50 Gbit/s systems to succeed NG-PON2 (40G PON, at 10Gbit/s per wavelength).
It will be the first standardized PON system to employ digital signal processing (DSP). Effenberger explains: “This may be surprising to hear that DSP has not been used in PON before, but this is a natural consequence of the nature of fibre-optic transmission. For systems operating at 10 Gbit/s and lower, DSP is simply not needed.”
In tandem with the economies of scale introduced by large-scale deployment, DSP will help Higher Speed PON to uphold PON’s reputation as a cost-efficient optical access solution.
“DSP provides so much advantage that 25G-bandwidth optics can be used to produce a 50G system,” highlights Effenberger. “This improves the cost profile of the system because DSP shifts the difficulty from the optical domain, where it’s hard to cost reduce, to the digital domain where cost reduction is inevitable due to Moore’s Law.”
Although Higher Speed PON offers a five-fold capacity increase over its predecessors, it has been designed to work with the same fibre plant as G-PON, XG(S)-PON and NG-PON2.
“A successful technology requires a coincidence of both technical feasibility and strong global market demand,” notes Effenberger. “We strongly believe that 50G PON will provide the right capacity, at the right price, and at the right time.”
The international standards developed by ITU-T Study Group 15 define networks, technologies and infrastructures for transport, access and home.