9/20/2016, optical fiber access is moving from 100 megabytes to gigabytes. Recently, Shenzhen Telecom has taken the lead in planning to build a gigabyte City benchmark city. Within five years, it will achieve 100% optical fiber coverage, build 2 million 100 megabytes users and 900,000 gigabytes users, and develop 1.5 million 4K TV users. Gigabit all-optical network will undoubtedly use the next generation PON technology. There are many kinds of PON technologies, including 10G EPON, 10G GPON, symmetrical and asymmetrical, and 40G PON, 100G PON, WDM PON, etc. What are their respective characteristics, which will be described in detail below.

How to upgrade EPON to 10G EPON

EPON technology was first introduced than GPON, but its downlink bandwidth is lower than GPON, and it is weaker than GPON in supporting traditional services. Therefore, EPON has large-scale applications mainly in Japan, Korea and China, where optical fibers are deployed earlier.

EPON and GPON mainly provide 100 Mbp service. To upgrade to Gigabit network, 10G EPON or 10G GPON need to be deployed. The upstream spectrum of 10G EPON is wider and covers the spectrum of EPON. Therefore, 10G EPON can be compatible with EPON terminals in the current network.

There are two kinds of standards for 10G EPON, one is asymmetric, that is, downlink 10G, upward 1G, and the other is symmetric, both up and downlink 10G. The asymmetric type has a higher cost performance ratio, but the downlink and upstream speed ratio is larger. Although symmetrical 10G EPON solves the problem of low upstream speed, it has high cost. When symmetrical 10G EPON coexists with EPON, the downstream speed will be reduced by too many low-speed EPON terminals. Because time division multiplexing is used in the upstream, if a large number of data windows are occupied by low-speed EPON, the windows left to 10G EPON terminals will be limited, and the actual rate will be greatly reduced.

So is there a better 10G EPON scheme that can increase the upstream speed without too much cost increase?

Uplink 2.5G Rate 10G EPON Technology

The difference between 10G EPON and 10G GPON in upload rate leads to different user bandwidth and experience in different networks of operators, which brings obstacles to the unification of operators’business planning. For this reason, Huawei has developed a 10G EPON solution with 2.5G upstream speed. This asymmetric 10G EPON has the same speed as 10G GPON, which facilitates the business planning of operators, shields the differences between devices and facilitates the unified distribution and management of business.

Specifically, Huawei Bureau Symmetrical 10G EPON Business Board can support a variety of remote configurations, that is, symmetrical or asymmetrical terminals, while supporting the upstream 2.5G rate specifications. The remote asymmetric 10G EPON ONT hardware supports both the traditional 1G rate and the 2.5G rate upstream. Only the software License can cooperate with the local authorities to obtain the 2.5G rate upstream.

The 10G EPON of 2.5G upstream undoubtedly solves the problem of low upstream speed of asymmetric 10G EPON. Software license can reduce the initial equipment investment of operators, purchase licensee according to the needs of business growth, and achieve upstream speed-up without replacing hardware. This business model of pay-on-demand is more in line with the business of operators. The need for step-by-step growth. New technology innovation can also be encouraged to generate more new functions and new businesses.

How to upgrade GPON to 10G GPON

GPON and 10G GPON wavelength do not overlap. When they coexist on the same ODN network, they need to use WDM1r combiner. Although there is an additional passive optical device, the advantage of 10G PON wavelength does not overlap is that unlike 10G EPON, the upstream rate is not affected by the low-speed EPON terminal, and 10G GPON can obtain the full rate.

For the evolution of GPON to 10G GPON, Huawei PON Combo solution provides three different ways. One is an external synthesizer solution, which can be configured in the cabinet or on the wiring rack. It connects GPON interface, 10G PON interface and ODN interface through optical connector respectively. The second one is through PON Combo board. The single board provides GPON and 10G PON interface. It integrates a combiner on 2-in-1 connector and has only one optical interface to the outside. In this way, only the original optical interface needs to be inserted into the connector of PON Combo board. The advantage of this scheme is that the optical module can be replaced according to the distance. There is some flexibility. The third is PON Combo optical module, which integrates GPON, 10G PON and WDM1r combiner. The advantage of this scheme is easy evolution, but the disadvantage is high cost and lack of flexibility of optical module replacement.

40G PON and symmetrical 10G PON

As the next generation technology of 10G PON, 40G PON was once very hot. Some operators in developed countries wanted to skip 10G PON and enter 40G PON directly. One of the advantages of this technology is that it has four different wavelengths, which is very helpful in providing dedicated lines. Traditional PON technology uses broadcasting mode downstream. Although there is no data security problem theoretically through encryption technology, some foreign governments and bank customers still have concerns. And 40G PON can be separated on the physical layer by independent wavelength, which solves the security problem. In addition, the remote module processing of wireless base station also needs independent wavelength to transmit.

However, in order to maintain the unity of terminals, 40G PON terminals need to adapt to different wavelengths. This technology still has great challenges. The yield of optical modules has not yet reached the standard. It is difficult to achieve, especially the cost of terminals. Therefore, many operators decide to start with symmetrical 10G PON. Symmetrical 10G PON can be compatible with asymmetrical and symmetrical 10G PON terminals at the far end. Therefore, terminals can be configured according to different needs of residential applications or enterprise dedicated lines to reduce costs.

100G PON and WDM PON

Huawei released the industry’s first 100G PON prototype on FTTH Council in February 2016. At present, 100G PON is realized by single-wave 25G and four-wavelength superposition. The multiplexing of the current GPON wavelength means that when 100G PON is deployed, GPON technology needs to exit the historical stage and release the wavelength resources to provide higher technology. Rate.

Another technology is WDM PON, Huawei has been investing in innovation, from the initial 16-wave 1G to 32-wave 2.5G, to March 2016, the first 32-wave 10G prototype was released at the OFC exhibition in the United States. WDM PON is suitable for the application of enterprise dedicated line or wireless remote base station forward transmission. Because WDM PON needs to configure AWG filter, it is not completely compatible with traditional ODN, so the current application is very limited.

Next Generation PON Terminal

The development of various PON technologies also needs the cooperation of terminals. At present, the terminals of various PONs and 10G PONs are mature. On the one hand, the terminal is increasing in speed, including supporting Gigabit interface, dual-band Wi-Fi, supporting routing, etc. On the other hand, the terminal has gradually become the control center and connection center of smart home. The terminal is also developing towards intelligent direction, providing an open software platform to support third-party software integration and download. Integrating Bluetooth, Zigbee/Z-wave and other interfaces can support 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 in use or not, and automatically enter the energy saving mode if not in use. In addition, in the future, Wi-Fi can automatically detect whether the device is in use or not, and then start Wi-Fi when the device is required. Although it will sacrifice part of the response speed, it can save energy and protect the environment.

concluding remark

The development of optical fiber technology is very rapid. It is a rare industry where the technological development is ahead of the business demand. The 10G PON products being deployed on a large scale were launched several years ago, and now the prototype of 100G PON has been demonstrated. However, different technical standards also bring operators confusion about network choice and complexity of operation and maintenance management. Unified standards are the future direction of development. A good business model can promote technological innovation, such as 10G EPON with 2.5G upstream, energy-saving terminals, etc. More technological innovation should be encouraged only through software modification, so as to reduce the number of upgrades of equipment by operators, so as to increase the benefits of the industrial chain.

The scale deployment of the next generation PON technology represented by 10G PON has begun, and benchmarking pilot projects such as Gigabit City and Gigabit Community are being launched. Gigaband gigaband all-optical network era is approaching. Gigaband UWB network provides a powerful guarantee for the development of new services such as 4K/8K video, VR virtual reality and high-quality experience.