Discussion on various optical fiber access technologies in FTTH

With the increase of users ' demand for broadband access, the gradual decrease of the cost of fiber to the user, and the rapid development of optical fiber access technology, the broadband access mode of fiber to households will gradually mature. In this paper, the advantages of various optical fiber access technologies to realize the fiber to the household are disadvantages and applications, the paper puts forward that gepon and Gpon are the two most potential optical fiber access technologies in the future, and introduce the Gepon key technologies which are more mature for current standards and equipments.

Key words FTTH MSTP Point-to-Point Ethernet GEPON GPON

1. Background

First of all, with the increasing demand for broadband access, the existing broadband access, such as ADSL and LAN access, due to the existence of short transmission distance, limited access bandwidth, security is not high, QoS is not a good guarantee, and so on, has been increasingly unable to meet the needs of users. Second, the rapid development of optical access technology, from active optical access technology (PDH, SDH, MSTP, point-to-point Ethernet system) to PON passive optical access technology (APON, Bpon, GPON, EPON, GEPON). Finally, due to the cost of optical fiber itself, the equipment cost of Optical transceiver module, Olt and ONU, and the supporting cost of existing fiber to households are decreasing, the cost and line cost of optical fiber to household equipment are reduced greatly than before. Therefore, the access mode of optical fiber to the household is gradually mature, and it has become a hot spot in the communication industry at home and abroad. In the near future will become an important means of user access. However, in many optical fiber access technology, which kind of fiber access technology is more suitable for FTTH large-scale development?

2. Active Optical fiber access technology

2.1 PDH

PDH technology has been widely used in the field of optical access for its maturity, and its safety and reliability and high QoS guarantee performance, so that it is still the important optical fiber access technology for telecom operators for some time. However, the traditional PDH technology in the access to the application of inevitable limitations, mainly reflected in:

(1) Lack of unified network management;

(2) lack of networking capability;

(3) The ability to protect the business is poor;

(4) Lack of effective load-carrying means for the rapid growth of IP data service;

(5) Lack of flexibility in capacity upgrading;

(6) The interface is single, the equipment is stacked, the external cable connection is more, the fault point is increased, which brings difficulty to maintenance.

PDH Optical access technology is mainly used in point-to-point small-capacity dedicated enterprise users.

2.2 SDH

In the current enterprise customers optical access to the application of more SDH, compared with PDH, like the following obvious advantages:

(1) Unified bit rate, unified interface standards, easy interconnection between devices;

(2) The ability of network management is greatly strengthened;

(3) Has the self-healing protection function.

The main drawback of SDH is that it is designed for the transmission of TDM information. The technology lacks the functionality needed to handle information other than traditional voice information based on TDM technology, and is not suitable for transferring ATM and Ethernet services outside of TDM.

SDH Optical access technology is mainly used in point-to-point large-capacity dedicated line enterprise users, local or Exchange contact (POP) communication between.

2.3 MSTP

Based on SDH, simultaneously realizes TDM, ATM, Ethernet and so on service access, processing and transmission, provides the unified network management MSTP, has the following advantages:

(1) Provide a variety of physical interface to meet the new business fast access. It can provide multiple service flexible access while ensuring the compatibility of traditional TDM business. Typical business mainly include: IP, ATM, SDH, FR.

(2) because it is based on the existing SDH transmission network, it can be well compatible with existing technology to ensure the existing investment.

(3) MSTP uses VC virtual Cascade technology to effectively utilize the bandwidth and realize the bandwidth management of the smaller particles.

(4) MSTP uses Lcas technology to ensure that the number of virtual cascaded is dynamically adjusted without interrupting the data stream.

(5) The MSTP technology supports network, tree type, star type, multiple ring cut and so on, which can improve the scalability of networks, and facilitate the configuration of system environment flexibly and efficiently.

(6) High reliability of transmission and automatic protection of recovery function. MSTP inherits the protection characteristics of SDH, is less than 50ms automatic protection and recovery, and ensures the customer's satisfaction to the service.

The main disadvantages of MSTP are:

(1) Low bandwidth utilization;

(2) The maximum available bandwidth is limited;

(3) The main realization of two-layer function, as well as a simpler three-layer function;

(4) Flexibility to provide business capacity is insufficient.

(5) The consumption of optical fiber is more

The applications of MSTP are mainly located in the communication between the Bureau and the meeting point and the point-to-point communication between the large enterprises and the users.