Under the active promotion of “broadband China” and “speed up and down payment”, the broadband network is playing an increasingly prominent role as the basic platform for economic and social development. The Internet video application is rapidly gaining popularity, and the high-bandwidth business of 4K/8K HD, family cloud and video is also growing. In order to cope with the fierce market competition, operators have generally provided hundreds of megabytes (such as100M, 200M, 500M), and opened gigabit business in some developed regions as direction.
At present,1G-EPON and GPON have been widely deployed in China. Policies to promote,competitive drive, demand, prompting broadband access network began to MB,gigabit, to meet user demand, access technology need to be based on the rate of10G PON technology of a new generation of platform upgrade, 10G rate ofPON technology mainly includes 10G EPON, XG PON, XGS – PON.
The10G-EPON technology is maturing
The 10G-EPON standard is IEEE802.3av (later incorporated into IEEE802.3), including 10G/10Gsymmetric and 10G/1G asymmetric two modes. At present, 10g-epon technology and equipment have been very mature, and China Telecom successfully realized the chip level and system level of 10g-epon in 2011. The 10g-epon device has been deployed in the FTTB scenario scale and started deployment of FTTH scenarios. Due to the difference in the cost difference between symmetric and asymmetric PON, in order to reduce the type of plate card, the OLT side only deployed symmetrical 10g-epon port in principle. Since the 10g-epon port of OLT can be compatible with three types of ONU, including 10G/10G symmetric, 10G/1Gasymmetric 10g-epon ONU and 1G/1G EPON ONU, the ONU can be flexibly deployed according to user requirements.
Recently,China Telecom has focused on narrowing the range of 10G/1G EPON uplink. According to the IEEE802.3 standard, the uplink wavelength range of 10G/1G EPONis 1260nm ~ 1360nm. The purpose of this regulation is to be consistent with the uplink wavelength range of 1g-epon, but the biggest problem is to take up the precious resources of the O band 100nm. China Telecom has proposed narrowing the range to 1260nm ~ 1280nm (as shown in figure 1), which is consistent withthe uplink wavelength range of 10G/10G EPON. In 10G / 1G EPON ONU has not scale FTTH deployment of uplink wavelength, the wavelength of O band can be more resources for the future of PON technology, is of great significance to maintain the sustainable development of PON network.
XG-PON technology development and coexistence scheme
The XG-PON standards the ITU-T G. 987 series, which is the asymmetric mode of the descending10Gbit/s and the upward 2.5Gbit/s. At present,XG-PON technology and equipment have been mature. In particular, China Telecom has successfully implemented XG-PON laboratory communication in 2016 after nearly two years of testing, and has been verified in field trials.Recently, XG-PON will be deployed in FTTH scenarios.
The deployment of XG-PON should focus on the coexistence of GPONand XG-PON. Due to the difference between GPON and XG-PON and the range of uplink wavelengths, both of them coexist in a different way. There are two main types of coexistence schemes: the first is to use WDM1r (as shown in figure 2), which is described in the ITU-T standard; The second is to co-exist with GPON/XG-PON dual mode PON (optical module), which is an innovative scheme proposed by China Telecom (shown in figure 3). The proposal of China Telecom’s innovative solution is mainly to solve the problem of the insertion loss of about 1.5db in WDMr1, which leads to the problem of tight budget or shortage of link budget, and it is also easier to implement the project. Overall, these two kinds of schemes on whether ODN introduction of insertion loss, upgrade the construction difficulty, difficulty of equipment development, whether can use existing resources have different features (seethe coexistence of two kinds of scheme comparison shown in table 1), there will be application scenario. At present, the two co-existing methods, especially the GPON/XG-PON dual-mode PON, have been verified by laboratory and field tests.