FTTH Technology Comparison: AON vs PON Networks, What's the Difference?

Fiber-to-the-home (FTTH) is a network system where fiber optic cables are installed directly from a central hub into individual residences, such as houses and apartments. Significant progress has been made in deploying FTTH, which allows subscribers to access broadband Internet via fiber optics instead of copper. Two main approaches to deploying a high-speed FTTH network are active optical networks (AON) and passive optical networks (PON). So, what is the difference between AON and PON, and how do you make an informed choice?

 

What is Active Optical Networks (AON)?

 

AON (Active Optical Network) uses a point-to-point architecture, where each subscriber has a dedicated fiber optic line that terminates in an optical concentrator. AON networks rely on power-driven switching equipment, such as routers or aggregation switches, to manage and distribute signals and ensure that they are accurately delivered to individual subscribers. Through the switching capabilities of the switching equipment, input and output signals can be directed precisely to their destination. By relying on Ethernet technology, AON networks have the advantage of interoperability between different providers. Users can select the right data rate hardware for their needs and expand the network as demand increases without reconfiguring it. However, AON networks require at least one aggregation switch per user.

 

In active optical networks, amplifiers, transponders, and modulators are crucial devices that are key in facilitating more complex communication schemes.

 

Amplifiers

 

Amplifiers enhance the strength of optical signals in fiber optic cable transmission. Amplifiers are generally classified into two types: analog amplifiers and digital amplifiers. The key distinction is that the former is a more cost-effective solution, employed in various settings, including large buildings like data centers and hospitals. The other type of digital amplifier utilizes laser emitters rather than LED emitters and can provide advanced features for some specific applications.

 

Transponders

 

A transponder is an optical link signal converter that converts a signal from one format to another. For example, if you want to use a phone line to transmit a TV signal, you must first use a transponder to convert that model to a phone signal. This signal conversion makes seamless connectivity possible, letting you plug a phone line directly into a wall jack.

 

Modulators

 

A modulator differs from a transponder in that it changes the wavelength of the optical signal rather than formatting the signal. This feature comes in handy, for example, when you need to use blue fiber optics to transmit a red laser beam, in which case modulators convert the red laser beam into a blue laser beam to ensure that the optical signal is compatible with the optical medium.

What Is PON Network?

 

Unlike the previously mentioned AON network architecture, passive optical networks utilize a point-to-multipoint network architecture, where optical signals are separated and collected through the use of passive optical splitters. Fiber optic splitters are used to connect multiple subscribers in a PON network with a single fiber optic to provide them with different services without the need for separate fiber optic deployments in hubs and end-users. The switching equipment in a PON network is passive and does not need to be electrically powered, with fiber optic strands being shared in parts of the network and powered equipment used only at the source and receiving ends of the signals.

 

 

In a PON network, the following important products and devices collectively form the critical nodes of the PON architecture, providing efficient optical communications and making it a versatile and effective architecture for delivering broadband access services.

 

Read This Article to Learn More: Passive Optical Network Guide

 

OLT

 

The OLT (Optical Line Terminal) is responsible for sending and receiving optical signals to and from the subscriber side and is the central device of the PON, which can also manage the entire PON network and is usually located in the service provider's central office and data center. Some OLT devices can also provide network visualization WebUI for real-time network management; administrators can view the network's essential data, alarms, and reports at any time through the WEB view, whether on-site or remote control.

 

ONU or ONT 

 

The ONT(Optical Network Unit) or ONU (Optical Network Terminal) is installed at the customer's end, such as a residential or commercial location, and is responsible for receiving optical signals from the OLT and then converting them into electrical signals for use by the terminal equipment.ONT can be used as a home gateway to provide high-quality telephony, high-definition television, and Internet services, among other services. When used in conjunction with OLTs, ONT/ONUs can be used as fiber-to-the-home(FTTH) and multi-service traffic to provide efficient GPON solutions.

PON Transceiver

 

PON transceivers can be used on OLT and ONU equipment to transmit and receive optical signals between them. By expanding PON optical modules, network operators can easily expand network capacity.

 

PLC Splitters

 

PLC splitter can combine optical signals into a single output or distribute an incoming optical signal to multiple independent outputs. In other words, the splitter in a PON can be used in both directions, functionally, to distribute fiber optic signals downstream from the central office for broadcasting to all subscribers or to send signals from subscribers upstream for fiber optic signal merging to communicate with the central office.

 

What Are The Differences Between AON and PON Network, and How Do You Choose It?

 

As different fiber optic backbone types in FTTH systems, both PON and AON allow subscribers or businesses to access the network. The following section will introduce the differences between PON and AON to help you make the right choice.

 

Signal Distribution

 

The main difference between AON and PON networks is how the optical signals are distributed to each subscriber in an FTTH system. In an AON system, each subscriber has a dedicated fiber optic chain and enjoys independent bandwidth that is not shared. In a PON system, users share part of the fiber chain. Because of this difference, active optical networks are more efficient than passive optical networks, and AON networks can also support more users.

 

Cost

 

Power supply equipment and maintenance costs account for most of the network operating expenses. AON is a powered network, while PON uses passive devices. Therefore, PON has an advantage in maintenance and power supply costs, and its cost is less than that of AON.

 

Coverage Distance and Applications

 

AON can cover distances up to 90 km, whereas PON can generally only be deployed with a 20 km fiber network. Thus, PON users must be closer to the transmitter signal in the ground location.

PON is the only applicable solution if there are other aspects to consider, such as the need to deploy RF and video services, taking into account special reasons and business-related aspects. If the services in the network are all based on the Internet Protocol, then either PON or AON is applicable. PON is more suitable when long transmission distances are involved, and there are difficulties in providing power or cooling to the on-site infrastructure. If it is a business user or the network needs to be deployed to multiple dwelling units, then an AON network is more appropriate.

 

Network Expansion

 

When network expansion is required, AON networks need to install optical interface boards on tributary nodes to enhance the directionality of light. PON networks, on the other hand, only need to replace the optical splitter, and the optical directionality can be improved by using optical splitters with more branches. Therefore, in terms of network expansion, PON is more convenient than AON, and the expansion cost is also lower.

 

Network Security Mechanism

 

Regarding network security mechanisms, PON has a more stable network security mechanism, which provides all-around protection to the network through single node protection and full network protection. Single-node protection ensures that equipment failures of nodes in the network will not affect other nodes, and the network can also withstand simultaneous failures of multiple nodes. Full-network protection uses the exact dual-optical-plane protection mechanism, providing 1+1 channel protection and 1+1 circuit protection, and automatically switching optical planes, thus effectively guaranteeing network security.

 

AON vs PON Networks: Which is Better for FTTH?

 

Both AON and PON are effective solutions when choosing FTTH. The difference lies in the two kinds' different usage scenarios and unique advantages for different applications. When choosing a network solution, you need to evaluate various factors, such as geographic location, application requirements, and cost.

 

Although AON is more costly, it provides more efficient network connectivity and is great for high-bandwidth and low-latency network applications such as those in the healthcare, entertainment, and education industries. These industries have a higher demand for Internet access and are essential for meeting customer needs and ensuring an excellent user experience.

 

With its point-to-multipoint and shared bandwidth characteristics, PON can provide broad Internet access to urban and densely populated areas based on the advantages of distributing and broadcasting data to a wide range of users through a single passive optical splitter, reducing the need for and cost of fiber optic resources.

 

Conclusion

When you have to choose between AON and PON, evaluate your specific needs. They both have their own advantages or disadvantages and when choosing an FTTH solution, you need to consider the changes that come with the uniqueness of the deployment.QSFPTEK can provide you with a free consulting service for network solutions, and our engineers can customize a high-quality PON network solution for you. If you have any questions about PON or AON, please feel free to contact us.