A Comprehensive Overview of APON,BPON,EPON,GPON

PON stands for passive optical network, which means that the ODN (optical distribution network) between the OLT (optical line terminal) and the ONU (optical network unit) does not have any active equipment, and only uses optical fibers and passive components.PON mainly uses a point-to-multipoint network structure, which is the main technology to realize FTTB / FTTH.

PON technology contains a lot of content, and iteratively updated constantly. The development of xPON technology ranges from APON, BPON, to later GPON and EPON. All of them were developed with different transmission modes and standards in different periods.

What is APON?In the late 1990s, ITU (International Telecommunication Union) first proposed APON for packet communication using asynchronous transmission mode (ATM). APON uses the centralized and statistical multiplexing of ATM, combined with the sharing effect of passive splitters on optical fiber and optical line terminals, making the cost 20-40% lower than traditional PDH / SDH access systems based on circuit switching.

What is BPON?With the rapid development of Ethernet technology, APON is basically no longer used. At this time, the concept of broadband passive optical network (BPON) was proposed. BPON is an enhanced version of APON. It was originally called APON, but it was later distinguished from APON as BPON. BPON is based on the ATM protocol, with upstream and downstream speeds of 155 and 622 Mbps, respectively, while adding dynamic bandwidth allocation and protection functions. It can provide services such as Ethernet access, video transmission and high-speed leased lines.

What is EPON?Due to the high cost of BPON deployment, it was later replaced by EPON, with higher cost performance and faster speed. EPON is an Ethernet passive optical network. EPON is based on the PON technology of Ethernet, which combines the advantages of PON technology and Ethernet technology. It adopts point-to-multipoint structure and passive optical fiber transmission, and can provide various services on top of Ethernet. Due to the cost-effective deployment of EPON, it is the most effective communication method to realize the "three networks in one" and "last mile".

What is GPON?GPON is Gigabit-capable Passive Optical Network. The standards adopted by EPON and GPON are different. It can be said that GPON is more advanced and can transmit more bandwidth. Although GPON has advantages over EPON at high rates and multiple services, GPON's technology is more complex and its cost is higher than EPON. Therefore, at present, EPON and GPON are technologies with more PON broadband access applications. Which technology to choose depends more on the cost of optical fiber access and business requirements. GPON will be more suitable for customers with high bandwidth, multi-service, QoS and security requirements and ATM technology as the backbone. The future development is higher bandwidth. For example, EPON / GPON technology has developed 10 G EPON / 10 G GPON, and the bandwidth will be further improved.

As the demand for network providers' capacity continues to increase, the versatility of access networks must also be expanded to meet this growing demand. PON is the most widely used technology in FTTH. The advantage of PON technology is that it can reduce the occupation of backbone optical fiber resources and save investment; the network structure is flexible and the expansion ability is well; the failure rate of passive optical devices is low, and it is not easy to be interfered by the external environment; the business supportability is strong.