Comprehensive Analysis of narrowband Passive Optical Networks in Access Network Technology

The access network technology is still quite common, So I studied the narrow band passive optical network in the access network technology. Here I will share it with you and hope it will be useful to you. ATM-PON has the following technical features:

◆ ATM-PON network topology is star, two-way transmission is generally used dual-fiber Air Division Multiplexing SDM), also based on Single Fiber Wavelength Division Multiplexing WDM. Point-to-multiple-point propagation uses the downstream time-division multiplexing (TDM) and upstream time-division multiplexing (TDMA) modes.

◆ The typical line rate of existing products is 622 Mb/s downstream and 155 Mb/s upstream. You can also use other bandwidth configurations, such as 622 Mb/s symmetric upper and lower lines and 155 Mb/s transmission rates. In the future, with the increase of the device level, the line rate can be further increased.

◆ In the case of FTTC and FTTZ, active devices still need to be located on the roadside or in the junction box. In the case of FTTH/B configuration, all active devices are removed from outdoor devices. Passive Optical Networks are simpler than Active Optical Networks and copper networks, and more reliable and easy to maintain. In particular, if FTTH is widely used and the active device and power backup system are transferred from the outside to the room, the environment requirements for devices and equipment can be greatly reduced, and the maintenance period can be extended.

◆ Because ONU/ONT is scattered at different points, the multi-access network technology is required for uplink access, FSAN full-service access network organization) and ITU International Telecommunication Union) TDMA is required to support uplink signal access, and TDM is used for downlink. Since each ONU/ONT is different from the OLT distance, in order to prevent signal collision, the uplink signal must adopt a special mechanism-ranging to "alignment ". Ranging is the most complicated part of ATM-PON technology.

◆ High degree of standardization, FSAN and ITU have released the technical specifications of ATM-PON, belong to different suppliers of OLT equipment and ONU has been interconnected.

◆ Because no source optical splitter will lead to optical power loss, so the transmission distance of the ATM-PON is generally not more than 20 kilometers, limited coverage.

In terms of economy, the current cost per line of the ATM-PON system is relatively high, the main reason is the limited market. FSAN believes that as user demand increases, product scale increases, and new technologies are adopted, the device and installation costs on each line will be significantly reduced.

Narrowband Passive Optical Network (narrowband PON)

The network topology of narrowband PON is the same as that of ATM-PON. It has the following main differences with ATM-PON:

ATM-PON is a broadband access network technology, can provide users with access rate greater than 2 Mb/s; narrowband PON is a narrow band access network technology, only supports narrow band business, the maximum access rate is 2 Mb/s.

◆ The line rate of narrowband PON is much lower than that of ATM-PON. The line speed is generally between 20 Mb/s and 50 MB/S.

◆ Narrow band PON transmission adopts circuit mode, while ATM-PON adopts group mode ATM Cell ).

◆ The network-side interface of narrowband PON is generally V5 interface, and the user-side interface is the existing narrowband business interface; The ATM-PON network-side interface is generally ATM interface, the user-side interface includes various wide narrowband business interface.

◆ Narrowband PON is less standardized than ATM-PON. Narrowband PON is the first to have products, there are standards; ATM-PON is the product and standards almost at the same time.

In addition to the above differences, other features of narrowband PON and ATM-PON are the same. The price of narrowband PON devices has rapidly declined in recent years and is close to the price of IDLC integrated digital loop carrier, which is widely used in narrowband access.

Applicability

Different Optical Fiber access network technologies have different application scenarios. The active optical access network technology is applicable to access by enterprises and institutions with high bandwidth requirements and high communication confidentiality. It can also be used in the feeder and wiring sections of the access network technology, and mixed with other access network technologies based on wireless or copper transmission.