Part I. What is AON?
AON is Active Optical Network. Active optical network refers to the network in which the signal is transmitted from the central office equipment to the user distribution unit using photoelectric conversion equipment, active optoelectronic devices, and optical fiber and other active optical fiber transmission equipment during the transmission process. Active optical devices include light sources (lasers), optical receivers, optical transceiver modules, optical amplifiers (fiber amplifiers and semiconductor optical amplifiers), etc.
Features of AON:
● Large transmission capacity: 155Mb/s or 622Mb/s access rate
● Long transmission distance: without repeater, the distance is more than 70 kilometers
● Mature technology: both PDH equipment and SDH equipment have been widely used
Part II. What is PON?
PON is the Passive Optical Network. The passive optical network is mainly composed of the optical line terminal at the central office end and the optical network unit at the user end. It is a point-to-multipoint network. Star, bus and other topological structures only need to install a simple optical splitter at the optical branch point, so it has the advantages of saving optical cable resources, sharing bandwidth resources, saving equipment room investment, fast network construction, and low comprehensive network construction cost. Therefore, with the application of optical fiber access technology FTTB, FTTC and FTTZ, PON has quickly become the most ideal access method for various FTTx and has been widely used.
Features of PON:
1. The Transmission rate is 622Mbps or 155Mbps down and 155Mbps up.
3. PON is a point-to-multipoint optical fiber transmission and access network, which has the advantages of saving optical cable resources, high equipment security, fast network construction speed, and low cost.
4. The passive optical networks that have been gradually commercialized mainly include TDM-PON (APON, EPON, GPON) and WDM-PON. Their common features are:
● Good upgradeability and low cost. Active equipment is removed from the access network, thereby avoiding electromagnetic interference and lightning effects, reducing the failure rate of lines and external equipment, and reducing the corresponding operation and maintenance costs;
● Good business transparency, high bandwidth, applicable to signals of any format and rate, can support analog radio and television services more economically, and support triple play (voice, video, data) services;
● High reliability, provides QoS guarantees of different business priorities, adapts to the development trend of IP-based broadband access market, and is suitable for large-scale applications.
Part III. AON vs PON, What’s the Difference?
1. Signal Distribution
In ADN, users have their own special optical fiber. The bandwidth that each user acquire is the same. Users in the PON network share a part of optical fiber. Therefore, those using PON may find their speed slow because all people share the same bandwidth. Moreover, if there is something wrong with the PON system, it would be difficult to find the source.
2. Equipment and Cost
The optical signals are mainly guided by active equipment, while there are no powering devices to guide signals besides two terminals. Therefore, AON needs more cost of powering equipment and maintenance than PON.
3. Coverage Distance
AON can cover a distance range of up to 90 km, while PON is usually limited by fiber cable runs of up to 20 km. As a result, users who choose PON should be closer to the original signals.
In the application, many factors should be taken into account in addition to the above reseason. For example, PON would be suitable when it involves radio frequency deployment and video services. You’d better choose AON if you have high requirements of the network or if there are many people to use.
5. Network Expansion
When branches need to be added in the network, the AON system must add optical interface boards at tributary nodes to increase the optical direction, while the PON system only needs to replace the optical splitter. The light direction can be increased by using optical splitters with more branches. So the expansion of PON is much more convenient than AON and the investment cost is lower.
6. Network Security Mechanism
PON is equipped with a more reliable network security mechanism, which includes single-node protection and whole-network protection. Single-node protection means that the equipment failure of a node in the network does not affect the work of other nodes, and has the ability to resist the simultaneous failure of multiple nodes. The whole network protection means that the same double optical plane protection mechanism can be used to provide 1+1 channel protection and 1+1 circuit protection and automatically switch the optical plane, which effectively ensure the security of the network.