As service providers globally continue to rapidly build future-proof, 100% fiber optic networks, XGS-PON technology has become the de facto standard for meeting the multi-gigabit bandwidth needs of residential and business customers. While broadband internet service at speeds of 10 gigabits per second (Gbps) may seem excessive for ordinary subscribers today, over the next years, XGS-PON will facilitate an increase in bandwidth consumption driven by more demanding content and services, such as 4K and 8K video, videoconferencing, augmented reality & virtual reality, and gaming.
XGS-PON, which stands for 10 Gigabit Symmetrical Passive Optical Network, is an updated standard for passive optical network (PON) fiber-based transmission technology, that supports high-speed 10 gigabit per second (Gbps) symmetrical – meaning downstream and upstream – data transfers.
Dgtl Infra provides an in-depth overview of XGS-PON technology, including its speeds, architecture, wavelengths, compatibility with GPON, and deployment costs. Additionally, we compare XGS-PON to other key passive optical network (PON) standards, such as GPON, XG-PON, NG-PON2, EPON, and 10G EPON. Looking forward, Dgtl Infra reviews future fiber technology upgrades for XGS-PON, like 25G PON, 50G PON, and 100G PON. Finally, we highlight examples of fiber providers who are deploying and trialing XGS-PON technology in the United States, Canada, and Europe – including a case study of Virgin Media O2.
What is XGS-PON?
XGS-PON, which stands for 10 Gigabit Symmetrical Passive Optical Network, is an updated standard for passive optical network (PON) fiber-based transmission technology, that supports high-speed 10 gigabit per second (Gbps) symmetrical data transfers. This means that XGS-PON technology is capable of delivering last-mile broadband network access at speeds of up to 10 Gbps downstream and 10 Gbps upstream.
XGS stands for ten (X), Gigabit (G), and Symmetrical (S).
Presently, the Gigabit Passive Optical Network (GPON) standard is the primary fiber-based transmission technology in-place that is delivering last-mile broadband network access. However, GPON is only capable of supplying this network access at speeds of up to 2.4 Gbps downstream and 1.2 Gbps upstream. Therefore, a fiber network that utilizes XGS-PON technology can deliver over 4x downstream and 8x upstream bandwidth to customers, as compared to GPON technology.
XGS-PON enables internet service providers (ISPs) to offer superior high-speed internet, video, and voice services to consumers and businesses. In turn, these customers benefit from XGS-PON’s significant step-up in bandwidth by experiencing better performance when gaming (particularly cloud-based), using multiple streaming devices simultaneously, and consuming higher resolution content (e.g., 4K and 8K video).
Additionally, mobile backhaul is another market segment which XGS-PON can address, particularly as it relates to 5G transport.
Architecture of XGS-PON
In terms of architecture, XGS-PON operates over a point-to-multipoint optical access infrastructure, composed exclusively of passive optical components. Indeed, active electronics in the network only reside at hubs and at the customer’s home or business. Below is an illustration of a typical XGS-PON system architecture:
According to the International Telecommunication Union (ITU), XGS-PON must support a minimum fiber transmission distance of 20 kilometers, equivalent to 12.4 miles, between an optical line terminal (OLT) and optical network unit (ONU) – which is commonly referred to as an optical network terminal (ONT). While XGS-PON can support a maximum fiber transmission distance of 40 kilometers, equivalent to 24.9 miles, between an OLT and ONU / ONT.
Importantly, XGS-PON technology can serve up to 256 customers on a single fiber. In contrast, GPON is capable of supporting only 64 customers and typically these networks do not serve more than 32 customers.
XGS-PON delivers symmetrical 10 Gbps services over a single wavelength. Specifically, XGS-PON operates at a downstream wavelength of 1577 nm and an upstream wavelength of 1270 nm.
Also, XGS-PON systems are backward compatible, meaning they are capable of operating at the same wavelengths as an existing XG-PON system or operating at GPON wavelengths.
Compatibility of XGS-PON and GPON
XGS-PON is designed as an overlay onto existing GPON networks through the addition of optical wavelengths. In an overlay network, a GPON fiber provider can continue to operate GPON for certain customers (e.g., homes), while seamlessly operating XGS-PON for other customers with larger bandwidth requirements (e.g., businesses).
To upgrade from GPON to XGS-PON, a fiber provider needs to perform the following at its central office:
- Upgrade the backbone connections of all existing optical line terminals (OLTs) to 10 Gbps connections
- Replace all existing GPON-only line cards in the OLT chassis to combo cards supporting both GPON and XGS-PON standards, allowing both services to be deployed on the same optical distribution network (ODN)
- Replace all existing GPON-only optics to optics supporting both GPON and XGS-PON
Subsequently, the fiber provider or internet service provider (ISP) can offer faster speeds, following an upgrade to the customer’s optical network terminal (ONT) – a device which delivers internet, video, and voice services to the customer.
XGS-PON and GPON Diagram
Deployment Costs of XGS-PON
Presently, the cost differential between fiber deployments using GPON and XGS-PON transmission technology is relatively immaterial. According to Adtran, XGS-PON electronics cost 20% to 30% more than GPON electronics, which translates to only 2% to 3% more capital per home for an entire fiber-to-the-home (FTTH) network build-out.
As a result, nearly all greenfield fiber networks are choosing to be built using XGS-PON, given its superior bandwidth capabilities for both downstream and upstream transmission. Indeed, by deploying XGS-PON today, instead of GPON, fiber providers can avoid a future upgrade cycle.
Regarding operating expenses, XGS-PON is a passive optical network (PON) technology, meaning that the fiber network does not need to be constantly powered by electricity, which reduces energy costs. As an example, a splitter, which is the device that splits a circuit is completely passive in XGS-PON.
XGS-PON vs GPON, XG-PON, NG-PON2, EPON, and 10G EPON
Several passive optical network (PON) standards exist for delivering gigabit and multi-gigabit capable broadband services, including the following access technologies:
- GPON: Gigabit Passive Optical Network
- XGS-PON: 10 Gigabit Symmetrical Passive Optical Network
- NG-PON2: Next-Generation Passive Optical Network 2
- EPON: Ethernet Passive Optical Network; runs on the Ethernet protocol
- 10G EPON: 10 Gigabit Ethernet Passive Optical Network
Of these standards, XGS-PON, NG-PON2, and 10G EPON are considered next-generation passive optical networks. Growth and uptake of these new access technologies is expected to be rapid. According to Omdia, the next-generation PON equipment market is forecasted to increase at a 39% compound annual growth rate (CAGR) to $12 billion of revenue by 2027.
Differences Between GPON, XG-PON, and XGS-PON
The transition between passive optical network (PON) fiber-based transmission technologies has been dynamic, with GPON, XG-PON, and XGS-PON often compared. While GPON is the primary fiber-based transmission technology currently in-place and XGS-PON is expected to replace it, XG-PON was a short-lived evolutionary stop-gap.
As shown above, the main difference between XG-PON and XGS-PON is that XG-PON delivers asymmetrical bandwidth of up to 10 Gbps downstream and 2.5 Gbps upstream, while XGS-PON is capable of providing symmetrical bandwidth of up to 10 Gbps downstream and 10 Gbps upstream.
Symmetrical download and upload speeds are critical for enabling high-quality, real-time communications, such as through videoconferencing, telehealth, distance learning, and collaboration tools. Additionally, symmetrical bandwidth facilitates the upload and sharing of large files to the cloud.
XGS-PON vs NG-PON2
XGS-PON and NG-PON2 are both next-generation passive optical network (PON) technologies, however, they primarily differ in terms of their commercial adoption and technical capabilities.
Presently, growth in PON technology is being driven largely by XGS-PON deployments from fiber providers in North America, Europe, Middle East, and Africa (EMEA), and the Caribbean and Latin America (CALA). In contrast, the commercial adoption of NG-PON2 has been limited to-date, with Verizon being one of the only notable exceptions pursuing NG-PON2 deployments.
Verizon is building-out fiber across its footprint using NG-PON2 technology for: i) Fios, Verizon’s brand for its 100% fiber optic broadband service and ii) mobile backhaul, from its cell towers and small cell sites.
At Verizon’s recent Investor Day, the company touted the benefits of NG-PON2, including support for symmetrical speeds of up to 10 Gbps, efficiency, multi-purpose, and reliability.
To this end, Verizon is able to deliver multi-gigabit symmetrical service that can support residential, small- and medium-sized businesses, large enterprises, and wireless customers on one fiber network. Therefore, instead of operating four physical networks, Verizon is operating one by leveraging NG-PON2 technology, which – in theory – leads to both capital expenditure and operational expense savings.
Importantly, in the future, NG-PON2 can have its bandwidth extended further, given that it is capable of reaching symmetrical speeds of up to 40 Gbps.
Overall, one of the key disadvantages to NG-PON2, which has hindered its commercial adoption, is cost. According to Dell’Oro Group, NG-PON2 costs 3.5x to 4x more than XGS-PON on a per-port basis.
NG-PON2 is the first multi-wavelength network access standard, which utilizes time wavelength division multiplexing (TWDM) to support 4 wavelengths (today) to 8 wavelengths (future) of 10 Gbps each over a single fiber. Based on NG-PON2 initially supporting 4 wavelengths of 10 Gbps each on the same fiber, this equates to total symmetrical bandwidth of 40 Gbps.
Additionally, NG-PON2 enables new technical capabilities like wavelength mobility for seamlessly migrating services and channel bonding, which can increase the bandwidth delivered for a single service. Finally, multiple wavelengths over a single passive optical network (PON) can provide enhanced resiliency and low-latency.
XGS-PON vs 10G EPON
XGS-PON and 10G EPON are both standards for next-generation passive optical networks which support symmetrical and asymmetrical line-rate operations. Importantly, XGS-PON is the next-generation standard of the International Telecommunication Union (ITU), while 10G EPON is the next-generation standard of the Institute of Electrical and Electronics Engineers (IEEE).
In terms of symmetrical bandwidth, XGS-PON and 10G EPON are both capable of providing of up to 10 Gbps downstream and 10 Gbps upstream. Geographically, XGS-PON is the predominant next-generation standard in North America and Europe, while 10G EPON is more commonplace in Asia.
Future Fiber Technology – 25G PON, 50G PON, and 100G PON
Commercial solutions are being developed and trials are being undertaken for future passive optical network (PON) fiber-based transmission technologies, including 25G PON, 50G PON, and 100G PON.
XGS-PON has been designed for easy upgrades, without changing the underlying optical distribution network (ODN), to reach future PON fiber-based transmission technologies that can deliver more bandwidth. Specifically, the XGS-PON standard allows for hardware to be further upgraded to technology that supports 25G PON (25 Gbps), 50G PON (50 Gbps), and 100G PON (100 Gbps).
As shown below, optical line terminal (OLT) and optical network terminal (ONT) forecasts indicate that, at present, XGS-PON is the dominant next-generation PON technology, followed – at a significant distance – by 10G EPON and NG-PON2. By 2027, future PON fiber-based transmission technologies including 25G PON, 50G PON, and 25G/25G EPON are expected to gain some market share, with XGS-PON still remaining the principal standard.
XGS-PON Deployment Examples
XGS-PON is being deployed by carriers and internet service providers (ISPs) with millions of fiber passings in the United States, Canada, and Europe, among other regions in the world. For example, some of the largest companies deploying and trialing XGS-PON technology in their access networks include:
- United States: AT&T, Frontier Communications, Quantum Fiber (Lumen), Kinetic (Windstream)
- Canada: Rogers Communications, Bell (BCE), Telus
- Europe: Openreach (BT Group), Virgin Media O2, CityFibre, Proximus, KPN
To better understand how XGS-PON is being deployed, below is further detail on how Virgin Media O2, a 50%/50% joint venture between Liberty Global and Telefónica, is implementing the technology in the UK.
Virgin Media O2 – XGS-PON Deployment
In the UK, Virgin Media O2 intends to upgrade its entire hybrid fiber-coaxial (HFC) network to fiber-to-the-home (FTTH) by year-end 2028. To do this, Virgin Media O2 is utilizing XGS-PON fiber-based transmission technology.
Including Virgin Media O2’s existing fiber footprint and joint ventures, the company will extend its total FTTH footprint to up to 23 million premises, which represents approximately 80% of the UK fixed network market. Therefore, by 2028, all Virgin Media O2 customers will be able to subscribe to 10 Gbps service.
Utilizing its in-house build, network, and corporate services, Virgin Media O2 anticipates rolling-out XGS-PON fiber-based transmission technology across its fixed network at a cost of only £100 per home.
To this end, Virgin Media O2 touts its 100% underground, ducted network as making it very cost-effective to pull fiber through to the last cabinet – meaning the company will only build fiber “drops” and incur customer premises equipment (CPE) costs for subscribers who want to upgrade to fiber services.
In comparison, Virgin Media O2 states that it would cost £75 to £80 per premise for the company to upgrade to a full DOCSIS 4.0 hybrid fiber-coaxial (HFC) network in the UK.