With the rapid development of the broadband market, mainstream operators at home and abroad have already provided broadband access services based on PON bearers. The EPON standard initiated by IEEE and the GPON standard initiated by ITU have become the two mainstreams of PON technology.
However, with the recent development of online on-demand, online education, IPTV and interactive games, especially 4K video, virtual reality and other services, the demand for bandwidth continues to grow, and the original 100M/200M access bandwidth has been The broadband industry is entering the Gigabit era without meeting the business needs of users. The original GPON/EPON access can not meet the user’s business needs. The 10G PON technology has gradually become the mainstream technology of the PON network. The major operators at home and abroad are facing the pressure and challenge of upgrading the 10G PON network.
PON technology began in 1995. After 14 years of development of various PON technologies, the IEEE released the IEEE 802.3av 10G EPON standard in 2009, maximizing the content of EPON IEEE 802.3ah, which is the rapid development of the future network foundation.
The 10G EPONs are classified into two types according to the rate: the asymmetric mode (the downlink rate is 10 Gbit/s, the uplink rate is 1 Gbit/s) and the symmetric mode (the downlink rate is 10 Gbit/s, and the uplink rate is 10 Gbit/s). The biggest feature of 10G EPON is that it expands the upstream and downstream bandwidth of EPON. At the same time, it supports a maximum split ratio of 1:256. It also has a great improvement in transmission distance. At a split ratio of 1:256, the transmission distance can be It reaches 20km, and at a split ratio of 1:128, the transmission can reach 30km.
Since 2008, the ITU has gradually standardized the next generation of GPON technology, defining XG-PON1 and XG-PON2. XG-PON1 is asymmetric (downlink rate is 10Gbit/s, uplink rate is 2.5Gbit/s), and XG-PON2 is symmetric (up/down rate is 10Gbit/s).
The main features of 10G GPON are: compatibility, 10G GPON ODN system can effectively use the existing fiber, splitter and live connector in the original GPON network; super broadband capability, the broadband capability provided by 10G GPON is GPON 4 times and 10 times of EPON, so it can meet the user’s future demand for large bandwidth; good interoperability, 10G GPON follows the GPON management control protocol, can provide very complete 10G GPON interoperability; greater split ratio And farther away, 10G GPON can achieve a transmission distance of 20km at a split ratio of 1:512. 10G GPON is suitable for both densely populated cities and remote areas in order to improve the coverage of access networks.
The working principle of the 10G PON is the same as that of the PON. That is, the downlink OLT sends the data to each ONU by means of broadcast, and the uplink uses Time Division Multiplexing (TDMA) to transmit data to the OLT.
As shown in Figure 1, on the OLT, the downlink service is encapsulated into a GEM frame and the ID of each ONU is transmitted on the optical fiber. After reaching the optical splitter, it is divided into branches to reach each ONU. The ONU determines which one by comparing the ID number. The data belongs to itself, and the ID is discarded if it does not match.
As shown in Figure 2, the uplink is divided into different time slots. Each ONU can only send data to the OLT according to a specified time slot. The time slots are uniformly allocated by the OLT, so that the uplink data of each ONU does not reach the optical splitter. Conflicts arise in order to compete for time slots.
10G PON Network technology is an important way for broadband access network service bearer. With the development and popularization of large-flow and high-bandwidth services such as 4K video and virtual reality, 10G PON has become the trend of the GPON/EPON.