What is Next Choice Beyond 10G PON?

The worldwide fiber deployment has entered into an acceleration phase since the mid 2000’s. Fiber connectivity provides ubiquitous high-speed connectivity to connect everyone and everything from anywhere. GPON, as the first generation of PON technology commercialized on a large-scale worldwide, paved the way for fiber technologies since 2009.  Deployment of new PON technology approximately every 8 years allowed a continuous success for fiber operators. The evolution of PON technologies upgrades the fiber network by providing enhanced bandwidth and cost-effective solutions to fulfill the emerging applications requirement. From 2016, operators have begun to launch 10G PON around the world, especially in Asia. This new PON technology allows service providers to offer shared internet speeds up to 10Gbps and deliver gigabit services to end users to meet the demand of 5G and a wide range of application such as 4K videos and OTT services. This enables operators to differentiate their services and compete with OTT players, and to generate new revenues streams by proposing new services consuming more bandwidth.

The challenges ahead: increasing bandwidth requirement

With arrival of the 5G era, the new generation of mobile network introduces demanding requirements that challenge existing fiber networks for larger bandwidth, more capacity with lower latency. In the most obvious scenario, emergence of 5G mm Wave drives large data throughputs, which can extend to as much 20 times the required capacity of 4G LTE.  Another scenario is high-density small cells for 5G fix wireless access, which require larger bandwidth for the backhaul transport. The current 10G PON can hardly meet the increasing bandwidth requirements or premium service level agreement needs.

The second challenge comes from digital transformation.  When they embrace a digital strategy, all businesses increasingly depend on their connectivity to the cloud and high performance application such as AI and big data. In addition, each industry has its specific requirements for the network transmission performance for different scenarios. For many critical applications, businesses use bandwidth on a dynamic basis as their requirements change. The limitation of GPON or 10G PON makes it difficult to meet all scenarios requirements. An enhanced PON technology is needed to ensure the network can meet all the different applications requirements for low delay, larger bandwidth, security, and reliability.

Finally, the explosion of data generated by millions of IoT devices each day puts the current 10G PON system under pressure. According to Idate estimates, the world IoT market is expected to reach 1.7 billion objects by 2025, increased almost fourfold between 2020 and 2021.  Increased bandwidth demand is driving passive optical network upgrades to support higher speeds of data transmission with enhance security and reliability.

What are the options available to telcos?

What is the next generation of PON technology to meet the challenge for ever-increasing high transmission capacities demand?

There is a considerable debate on the follow-up path of 10G PON: 25G PON or 50G PON.  IEEE and ITU-T are actively involved on research to promote the evolution of PON technologies on two different directions. The IEEE first approved their 25G/50G EPON standard in 2020. In parallel, the ITU-T began to study higher speed PON technologies around 2016 and initiated their 50G PON solution and standard in 2018. Widely supported by major Tier-1 operators and equipment vendors, the ITU-T standard is scheduled to finish in 2021. The large-scale commercial deployment of the new PON technologies is expected to start around 2024.

Despite some points of debate still to be solved, 50G PON technology seems to be the most future proof choice after the 10G PON generation.

Sufficient bandwidth growth:  From GPON to 10G PON to 50G PON, the bandwidth increases by at least 4 times per generation. It is an open question as to whether an intermediate upgrade step to 25G PON (between 10G PON and 50G PON) can make sense beyond niche applications. According to many leading network operators, it is only worthwhile making the huge investments and efforts of system upgrade for a four times capacity increase.

Appropriate deployment timeframe:  The access network upgrade tempo is generally every 7 or 8 years.  GPON has been deployed widely in large-scale since 2009. After 7 years, 10G PON has been deployed in 2016.  Based on this previous deployment pace, the next generation of PON technology would launch in around 2024. Obviously, the commercial timeframe of 25G PON is close to 50G PON availability. Frequently upgrading fiber network in a short time interval cannot be supported economically or operationally. 50G PON technology is expected to be technically achievable in the upcoming years. Before the release of 50G PON, it seems that 10G PON will continue to be deployed in large-scale and should be sufficient to meet the market demand in the next few years.

Comparable deployment cost to 25G PON: 25G PON is an incremental improvement of existing PON approaches, but the necessary 25G optical components must be developed. 50G PON will be the first PON system to use digital signal processing.  This design approach uses the power of microelectronics to enable 50G using similar optical components as 25G PON. Hence, 25G PON does not seem to have significant cost advantages.  Furthermore, because of its adoption by major telcos worldwide, the volumes of 50G PON is expected to be much larger than that of 25G PON. Of course, since this is speculation about the future, there is still a debate around the relative cost of 50G PON and 25G PON.

Coexistence with existing fiber infrastructure:  50G PON can effectively reuse the existing 10G PON ODN resources and in doing so greatly reduce deployment costs. Depending on the selected wavelength plan option, 50G PON can also support GPON coexistence.

Conclusion:
50G PON is a future proof choice and will be the mainstream choice to migrate from 10G PON to 50G PON.  A preference for 50G PON has been expressed by several world-class telcos as well as equipment vendors. The cost-effective development 50G PON can be accelerated by massive deployment volumes. For emerging markets for FTTH, 10G PON is the best choice for now, and they still have enough time for the next upgrade.