What Does PON Technology Mean? Passive Optical Network Solves The Last Mile Of Broadband

At present, the mainstream solution to solve the problem of the last mile of broadband access is PON technology. It uses optical fiber as a transmission medium and uses passive optical distribution network to achieve point-to-multipoint connections. It reduces operation and maintenance costs while providing high-bandwidth services. The original traditional copper cable access method is slowly being replaced by it.

What does PON technology mean?

PON is the abbreviation of PON, which is called passive optical network in Chinese. It is composed of three parts, one part is optical line terminal OLT, one part is optical network unit ONU, and the other part is passive optical distribution network ODN. The optical line terminal OLT is installed in the operator's central office, and the optical network unit ONU is placed in the user's home or corridor. The passive optical distribution network ODN is composed of optical fiber and passive splitter. It does not require any power supply equipment.

The core feature of this technology is passive. Traditional network intermediate nodes require a large number of switches and routers, and each device must be powered and maintained. The optical splitter used by PON is like an optical lens, which purely splits the optical signal into multiple channels. No electronic components are involved, so it does not generate heat and does not require power supply, which greatly reduces equipment failure rates and operation and maintenance costs.

How does the PON network work?

PON uses wavelength division multiplexing technology to achieve two-way communication. In the downstream direction, the OLT sends data by broadcasting. All ONUs can receive the same signal. However, each ONU only extracts its own data frame. In the upstream direction, time division multiple access technology is used. The OLT assigns different sending time windows to each ONU to ensure that data arrives in an orderly manner without conflict.

The actual workflow is that the OLT continuously broadcasts downlink data and at the same time dynamically allocates uplink time slots to each ONU. The ONU is usually in an energy-saving sleep state, wakes up within the allocated time period, and sends cached data. Such a mechanism allows multiple users to efficiently share the same fiber resource, ensuring bandwidth utilization and preventing data collisions!

What are the advantages of PON technology?

The most intuitive advantage of PON is its large bandwidth. A single optical fiber can easily support Gigabit or even 10 Gigabit transmission rates, which can fully meet high bandwidth needs such as 4K video, cloud storage, and online games. The optical fiber transmission distance is long, and its coverage radius can reach 20 kilometers, making it suitable for large-scale deployment in urban and rural areas.

The passive characteristics bring extremely high reliability and extremely low operation and maintenance costs. The optical splitter in the middle does not require power supply, is not afraid of regional power outages, and also reduces the risk of lightning damage. Operators only need to maintain the OLT and ONU equipment at both ends, and the ODN network in the middle has almost zero maintenance, significantly reducing labor costs.

What are the disadvantages of PON technology?

The coverage range of PON is limited by the optical power budget. The theoretical distance is 20 kilometers. However, in actual deployment, optical splitters will cause insertion loss. The greater the number of splitters, the greater the loss. The coverage distance will be shortened accordingly. Users in remote areas may not be directly covered and need to add relay equipment.

Troubleshooting is relatively complicated, which is also a problem in practice, because the ODN network is all passive components, and there is no way to remotely monitor the status like active equipment. When a certain optical fiber is interrupted, maintenance personnel can only take the OTDR equipment to the site to troubleshoot the fault point by section, which takes a long time to locate, which affects the user experience.

What is the difference between PON and GPON?

This technology family is called PON, which consists of multiple standards, such as APON, BPON, and the two-part Gigabit passive transmission category, namely GPON and EPON. GPON is a gigabit passive optical network, defined by the ITU-T organization. It supports two types, one is the related rate of downlink 2.5Gbps, and the other is the corresponding rate of uplink 1. It has high encapsulation efficiency and can well withstand traditional TDM services in terms of transmission.

EPON is a PON technology based on Ethernet. It follows the .3 standard, and its uplink and downlink are symmetrical. GPON has more advantages than EPON in terms of bandwidth utilization and service adaptation, but its equipment cost is slightly higher. Most of the newly built networks currently use GPON technology, and 10G PON is being popularized on a large scale.

What are the application scenarios of PON technology?

As the most widely used application scenario of PON, FTTH optical fiber to the home is operated by operators with the help of PON network, pulling optical fiber directly into every household, and also providing integrated services such as broadband Internet access, IPTV television and VoIP telephone. Newly built residential communities are directly pre-embedded with PON networks, while old communities are gradually upgraded step by step with the help of optical renovation projects.

Enterprise dedicated lines and mobile backhaul are also key application areas. For enterprises, PON can be used to build internal office networks to achieve high-speed interconnection among various departments. In the 5G era, base station fronthaul and backhaul networks extensively use PON technology, relying on existing optical fiber resources to resolve transmission bandwidth bottlenecks to support the development of mobile communications services.

I would like to ask, which PON technology does the broadband used in your home use? Can its speed test reach the bandwidth specified when signing the contract? We sincerely invite you to share your online experience in the comment area. If you think the article has practical value, please like it and forward it to friends in need.