OFweek Optical Communication Network News: Fiber optic access is moving from 100 megabit to gigabit, and recently Shenzhen Telecom has taken the lead in planning to build a gigabit city benchmark city, achieving 100% fiber coverage within 5 years, building 2 million 100 megabit subscribers and 900,000 gigabit subscribers, and developing 1.5 million 4K TV subscribers. Gigabit all-optical network will undoubtedly have to use next-generation PON technology. There are many types of PON technology, including 10GEPON, 10GGPON, symmetric and asymmetric, as well as 40GPON, 100GPON, WDMPON, etc., what are the characteristics of each of them, the following will be a detailed introduction.

EPON how to upgrade to 10GEPON

EPON technology than GPON was launched first, but its downstream bandwidth is lower than GPON, and in support of traditional services than GPON weak, so EPON is mainly in Japan, South Korea and China and other fiber deployment of the earlier market has a large-scale application.

EPON and GPON mainly provide 100 Gigabit services, and to upgrade to Gigabit network, 10GEPON or 10GGPON needs to be deployed. 10GEPON has a wider uplink spectrum, which covers the spectrum of EPON, so the 10GEPON local end can be compatible with EPON terminals in the existing network.

10GEPON currently has two standards, one is asymmetric type that is downstream 10G, upstream 1G, and a symmetric type of upstream and downstream are 10G. asymmetric type has a higher price/performance ratio, but the rate ratio of downstream and upstream is large. The symmetric 10GEPON solves the problem of low uplink rate, but the cost is higher, and when the symmetric 10GEPON coexists with EPON, the downlink rate will be pulled down by too many low-speed EPON terminals. Because time division multiplexing is used in the uplink, if a large number of data windows are occupied by low-speed EPON, the window left for 10GEPON terminals will be limited, and the actual rate will drop significantly.

So is there a better 10GEPON solution that can increase the uplink rate without bringing too much cost increase?

Uplink 2. 5G rate 10GEPON technology

The difference in uplink rates between 10GEPON and 10GGPON results in different user bandwidths and experiences across different networks, creating obstacles to unified service planning. In response, Huawei developed a 10GEPON solution with an uplink 2 .5G rate, so that the asymmetric 10GEPON and 10GGPON rates are identical, facilitating operators' service planning, shielding the differences between devices, and facilitating the unified issuance and management of services.

Specifically, Huawei's symmetric 10GEPON service board at the local end can support multiple remote configurations, i.e., either symmetric or asymmetric terminals, while supporting uplink 2.5G rate specifications. The asymmetric 10GEPONT hardware at the remote end supports both traditional 1G rate uplink and 2.5G rate uplink, and only needs to enable the software license to work with the bureau to obtain the uplink 2.5G rate.

Uplink 2.5G 10GEPON undoubtedly solves the problem of asymmetric 10GEPON uplink rate is low, and through the software License allows operators to reduce the initial investment in equipment, according to the needs of the business growth to buy License, no need to replace the hardware can be realized upstream speed, this pay-as-you-go business model is more in line with the gradual growth of the operator's business needs. This pay-as-you-go business model is more in line with the gradual growth of the operator's business. It also encourages new technological innovations, giving rise to more new features and new services.

How to Upgrade GPON to 10GGPON

GPON and 10GGPON wavelengths do not overlap, they need to coexist in the same ODN network through the WDM1r combiner, although an additional passive optical device, but the 10GPON wavelengths do not overlap the benefits of uplink rate will not be like 10GEPON, the uplink rate is affected by the low-speed EPON terminals, 10GGPON can be accessed at full rate.

For the evolution of GPON to 10GGPON, Huawei's PONCombo solution offers three different approaches. One is an external combiner solution, which can be configured in a cabinet or on a wiring rack, and connects to GPON interfaces, 10GPON interfaces, and ODN interfaces through optical connectors, respectively. The second is through the PONCombo board, a single board to provide GPON and 10GPON interfaces, integrated in the 2-in-1 connector combiner, only one optical interface to the outside world, so that in the evolution of the original optical interface only needs to be inserted into the connector of the PONCombo board on the connector will be fine, the advantage of this program is that according to the distance of the replacement of the optical module, with a certain degree of flexibility. The third is the PONCombo optical module, that is, the optical module integrated within the GPON, 10GPON and WDM1r combiner, the benefits of this program is easy to evolve, the disadvantage is the high cost and lack of optical module replacement flexibility.

40GPON and symmetric 10GPON

As the next generation of 10GPON technology, 40GPON was once very hot, some operators in developed countries had wanted to skip 10GPON directly into the 40GPON, one of the benefits is the use of OTN/" target="_blank">Wave Division technology, with four different wavelengths, which is very helpful in the provision of private lines. Traditional PON technology downstream using broadcasting, although theoretically there is no data security issues through encryption technology, but some foreign government and banking customers still have concerns. And 40GPON can be separated on the physical layer through independent wavelengths, which solves the security problem. In addition the remote module processing of the wireless base station also needs to have an independent wavelength to transmit.

However, in order to maintain terminal unity, 40GPON terminals need to adapt to different wavelengths, this technology is still a big challenge, the optical module yield has not yet reached the standard, the realization of a certain degree of difficulty, in particular, it is difficult to bring down the cost of the terminal. Therefore, many operators have decided to first symmetric 10GPON, symmetric 10GPON can be compatible with the remote end of the symmetric 10GPON terminal asymmetric and symmetric 10GPON terminals, so that the terminal can be configured according to the different residential applications or enterprise leased line on-demand to reduce costs.

100GPON and WDMPON

Huawei released the industry's first 100GPON prototype at the OLT/" target="_blank">FTTHCouncil in February 2016.Currently, 100GPON is implemented using a single-wave 25G, four-wavelength stack, multiplexing the current GPON wavelengths, which means that when 100GPON starts to be deployed, GPON technology needs to be When the deployment of 100GPON begins, GPON technology needs to be withdrawn from the stage of history, and the wavelength resources will be released for the new technology to provide a higher rate.

Another technology is WDMPON, and Huawei has been investing in innovation, from the initial 16-wave 1G to 32-wave 2.5G to the first 32-wave 10G prototype released at the OFC show in the U.S. in March 2016.WDMPON is suited for enterprise leased line or wireless remote base station forward transmission applications. Since WDMPON requires the configuration of AWG filters, it is not fully compatible with traditional ODNs, so the applications are still very limited.

Next-generation PON terminal

Various PON technology development also requires the cooperation of the terminal, the current variety of PON and 10GPON terminal has matured. On the one hand, the terminals are constantly upgrading in terms of rate, including support for Gigabit interface, support for dual-band Wi-Fi, support for routing, etc. On the other hand, the terminals are also gradually becoming the control center and connection center of the smart home, and the terminals are developing in the direction of intelligence, providing open software platforms to support the third party's software integration and downloads, and integrating interfaces such as Bluetooth, Zigbee/Z-wave, etc., so that they can support the smart home business.

In addition, the terminal is also gradually improving on energy saving and environmental protection, for example, the terminal can automatically detect the Ethernet interface on the user side to find out whether the user is using it or not, and if it is not used, it can automatically enter the energy saving mode. In addition, in the future on Wi-Fi, it can also automatically detect whether there is a device in use, and then start Wi-Fi when it detects that the device has a request, although it will sacrifice part of the response speed, but it can be energy-saving and environmentally friendly.

Conclusion

The development of fiber optic technology is very rapid, is one of the few technical development in front of the business needs of the industry, is being deployed on a large scale 10GPON products have been launched a few years ago, and now the prototype of the 100GPON has also been demonstrated. However, different technical standards also bring operators confusion in network selection and complexity in operation and maintenance management, and unified standards are the future direction of development. A good business model can promote technological innovation, such as uplink 2.5G 10GEPON, automatic energy-saving terminals, etc. More technological innovations only through software modifications should be encouraged to reduce the number of times the operators upgrade their equipment, so that the industry chain can gain more revenue.

The scale deployment of next-generation PON technology represented by 10GPON has already kicked off, and benchmarking pilots such as gigabit cities and gigabit communities are underway. Gigabit ultra-broadband network provides a strong guarantee for the development of new services such as 4K/8K video, VR virtual reality and other high-quality experience, and the era of Gigaband Gigabit all-optical network is approaching.