GPON, The Standard For Fiber Connections

GPON is a telecommunications access technology that uses fiber-optic cabling to reach the user. This fiber optic technology provides faster data transmission and reception through a single fiber, with a point-to-multipoint architecture, which allows home optical fiber (FTTH), or a building (FTTB). It also provides access to Triple Play (Video, Voice, and Data). It emerged with the need to strengthen copper and HFC networks, which were deemed obsolete at some point. Now, copper and fiber optic provide adequate solutions to each need.

Thinking about deploying GPON? Watch our webinar “Multi-Vendor GPON Activation in Action” on-demand.

While a few years ago it was a success to have 10 Mbps of an ADSL/DOCSIS connection, these speeds have been left far behind today. Except for some villages where optical fiber has not yet been deployed, it is rare to find FTTH connections of less than 100 Mbps, even almost the average speed today is 300 Mbps. Achieving these speeds is possible thanks to a number of modern technologies, and most importantly, GPON.

FTTH, Fiber-to-the-Home connections, is a direct connection between the plant and our home using a fiber optic cable. This connection is made from the OLT that is located in the central of the company to the ONT, which is the device that we place in our house.

 GPON emerged to end the problems of the PON standard, seeking to support all types of services (voice, Internet, TV, etc.) at symmetric speeds of 622 Mbit/s or 1.25 Gbit/s and asymmetric downstream 2.5 Gbit/s and upstream 1.25 Gbit/s, at a distance of up to 20 km for a maximum of 64 users per fiber link.

Fiber-optic communication offers several well-known advantages over electrical and RF transmission. Optical cables have very high bandwidth. The absence of electrical power over the line means there’s no spark hazard. Electromagnetic methods can’t tap the signal, so it’s more secure. Likewise, EM interference isn’t a problem. Maintenance is low, and the thin cables can be packed densely.

Several options are available for getting fiber optics close to the end-user. They include active optical networks (AON) as well as passive optical networks (PON). Within PON, the main options are BPON (broadband passive optical network), GPON (gigabit passive optical network), and EPON (Ethernet passive optical network). GPON offers the fastest speeds of any current PON option.

 

GPON

How GPON Works

The GPON technology is based on the ITU-T G.984 standard. It’s considered the successor to BPON, which is built on G.983. A single network consists of an optical line terminal (OLT) belonging to the service provider, a splitter, and up to 64 optical network units (ONU). The ONU may or may not be on the end user’s premises, but it serves a single customer. It converts the optical signal to electrical or RF signals which the end user’s equipment can connect to.

An ONU is sometimes called an ONT (optical network terminal). An ONT is usually on the customer premises and an ONU somewhere outside, but there’s otherwise no real difference. 

The information is sent over the short-wavelength infrared band, using wavelength division multiplexing (WDM). Downstream data goes over a 1490 nm signal, with a maximum speed of 2.488 gigabits per second. The upstream data uses the 1310 nm wavelength and can carry up to 1.244 Gb/second.

The next generation of GPON, called 10G GPON or XG-PON, offers symmetric 10 Gb/second upload and download speeds.

GPON customers are typically homes or small businesses. The technology delivers data, voice, and IP video. It may be packaged with an RF overlay at 1550 nm so that it can provide standard cable video as well.

GPON

GPON Advantages

Among its main advantages are:

Higher bandwidth.

Longer distance: The optical fiber allows cable distances of up to 20Km.

Quality of service: GPON guarantees the necessary bandwidth for each service and user.

Security: The information in the optical fiber travels encrypted, which guarantees the security in communications.

Operation: GPON has an integrated management model that simplifies the administration of the equipment.

Scalability: Companies can evolve to XG-PON and continue using the same fiber infrastructure.

In addition, this technology allows all IP services to be integrated through a single cable: VoIP, IPTV, Data / Internet, WIFI, video conferencing, video surveillance, access control, home automation … etc. which means, not only significant cost savings, but also a simplification in the management of all the elements that are part of the network.

Best Use Cases for GPON

GPON technology can be very cost-effective, provided it meets certain conditions. The OLT is relatively expensive, so the number of ONUs connected to it should be at or not much below either 32 or 64. Going above 32 ONUs requires adding a second port to the OLT, so there’s a cost jump at that point. Of course, the more users there are on an OLT, the more likely it is that service will degrade under peak use.

A PON offers low maintenance costs and has a high MTBF since passive components don’t fail as often. Its advantage is especially strong where minimizing maintenance work is essential.

The GPON design includes ATM encapsulation. This makes it convenient to deploy in networks that use an ATM backbone.

A GPON can replace existing copper-wire cabling and deliver higher data speeds with greater reliability. The question is when the improvement justifies the work of replacing it. High-density areas require less fiber and make it easier to optimize the allocation of ONUs to OLTs. With a large office building, it may make sense to put an OLT on the premises. Compact OLTs are available which don’t have to be deployed in a central office.

GPON vs. Other Optical Technologies

While GPON is growing in popularity, it isn’t the only option for bringing optical communication lines to the end-user. Different technologies have their place, and a service provider needs to consider their relative costs and benefits.

AON vs. PON

Active optical networks have their own advantages. They use electrically powered switching rather than passive splitters. An AON has a greater range, as much as 70 km from the central switch to an Ethernet device. Users can be more widely dispersed. The costs are more nearly proportional to the number of users, so there’s less need to optimize end-user groupings.

GPON includes QoS features to keep latency down, but an active network allocates bandwidth more effectively and provides better latency when the user load is high. It’s easier to locate faults in a busy network since the switches can report points of failure.

An AON has higher power consumption, and active components are more prone to failure than passive ones. Costs and maintenance requirements will be higher. AONs don’t support RF overlays.

BPON, EPON, and GPON

The PON competition today is basically between EPON and GPON. BPON networks are still around and will be for a long time, but they’re a previous generation of technology. BPON is slower than GPON and offers no advantages to compensate. It’s merely a matter of how long it will take to replace all existing installations.

EPON is sometimes called GEPON (gigabit EPON), which is confusing since people will tend to pronounce it like GPON.

EPON and GPON are both available in 10G versions, but the architectures are noticeably different.

GPON uses two different types of encapsulation. It uses GPON Encapsulation Mode, or GEM, to provide a frame-oriented service. Also, it uses ATM encapsulation for when working in an ATM network rather than Ethernet. EPON doesn’t add any encapsulation but treats everything as Ethernet data. It’s a subject of ongoing debate whether GPON is more flexible this way or just adds complexity.

Choosing between GPON and EPON is difficult. GPON has ATM compatibility, better data speeds, and better QoS features. EPON is more economical and treats Ethernet natively.

The Future of FTTH Connections and the GPON Standard

The GPON standard today is perfect for ensuring the proper functioning of new FTTH connections, and can still give much more of itself; it is far from saturated.

At the moment, GPON continues to be adopted in more and more countries and regions where little by little the optical fiber continues to replace copper, although there is still a long way until the disappearance of copper connections, especially in towns and small municipalities where there is almost no investment.

GPON will continue to be the standard for present and future short-term fiber connections, a standard that will continue to behave smoothly when 1 Gbps connections become the standard connections of all households, connections that some companies already offer and that they are not so far from becoming the standard if we take into account that connections between 300 Mbps and 600 Mbps are, today, the standard speeds.

GPON or EPON: Which is The Right Choice?

Getting fiber to the customer allows higher data speeds and opens new business opportunities. The questions are when to upgrade and which technology to use. The first choice is between active and passive networking. Within passive optical networking, GPON and EPON are the leading choices. Each approach has its advantages. Careful research and planning are needed to decide which will provide the most significant benefits.

When upgrading your service network, you need the highest level of expertise on your side. New options are always opening up, and yesterday’s state of the art is today’s outdated technology. Contact us to learn how we can help you to stay up to date.

Thinking about deploying GPON? Watch our webinar “Multi-Vendor GPON Activation in Action” on-demand.

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