FTTx-based VoIP challenges: improving the user's voice service experience (1)

In recent years, with the continuous development of internet broadband users, FTTx continues to grow, and FTTx-based VoIP users are also growing, IMS integration faces challenges.

Opportunities and Challenges of VoIP

A large number of new Internet-based businesses and new applications are emerging. These changes undoubtedly put forward higher requirements for communication networks. Access networks have entered the "Broadband Age ". The rapid development of optical transmission technology has led to the rapid development of backbone network technology. Similarly, in the access network, FTTx has low costs and high-capacity transmission capabilities in intensive business areas and residential areas, it has been used by major carriers as the most important broadband access technology. As a traditional fixed-line service, due to the appearance and popularization of FTTx, it is evolving from traditional TDM technology to VoIP.

FTTx is mainly used to access network optical fiber. Its core technology is PON (Passive Optical Network), which is mainly composed of OLT (local equipment of regional telecom data centers) and ODN (optical fiber network) it is composed of an ONU/ONT (user terminal device) and has a network structure. FTTx is divided into FTTB (optical fiber to the building) based on the location difference of The ONU/ONT endpoint ), FTTN (fiber-to-node), FTTO (fiber-to-Office), and FTTH (fiber-to-household). The PON architecture mainly refers to optical signals going down from the OLT, the optical signal is transmitted to the ONU/ONT of each user's terminal device in Ethernet format through a passive device Splitter (Optical Splitter, this not only greatly reduces the cost of maintaining network equipment rooms and equipment, but also saves a lot of construction costs such as optical cable resources.

How to deploy the FTTx voice service: Taking the China Telecom Group as an example to deploy the FTTx voice service: the China Telecom Group recommends that you use the following principles to deploy the voice service based on your needs:

1. FTTB/N/H cells in the new zone should no longer use copper cables to provide traditional voice services, but use VoIP to provide voice services;

2. For FTTB/N cells, the MDU built-in voice processing module (built-in) and independent IAD should be used to provide voice services for users;

3. High-end home customers who implement FTTH should provide voice services to users through SFU built-in IAD or home gateway built-in IAD;

4. For the transformation of the FTTB + LAN community, we recommend that you retain the voice service provision method of the existing PSTN network.

It can be seen that VoIP has become the mainstream technology for voice services in the new community. In addition, as the bandwidth demand for each user increases, the FTTB + LAN model may also be transformed. As the ONU Location keeps moving closer to the end user, copper may eventually be replaced by optical fiber cables, traditional voice phones will also be cut into FTTx networks and become IP calls. In the long run, this is conducive to the recovery and reuse of operators' previous investment in assets. In terms of voice services, the FTTx System is designed mainly for the Next Generation Network NGN. Therefore, we recommend that you directly connect the voice service upstream to the softswitch platform.

The FTTx voice service is connected to the NGN network and is implemented through VoIP. The following services from the OLT equipment use the same Ethernet-based bearer, and the protocol is unified and simple, it is easy to work with various protocols of the NGN network and can be seamlessly connected to the softswitch network.

VoIP calls are directly initiated from the ONU/ONT device of the user end. This complies with the principle of flattening the NGN network. The signaling protocol adopted supports SIP, MGCP, and H.248, the VoIP service traffic is converged at the OLT and uplinked to the softswitch voice platform through the FE/GE interface. The voice service must be configured with the highest priority.

In the way of connecting a single uplink interface to the SS dedicated data network, because the entire network uses the data network for data transmission, therefore, the main debugging work is the integration of the SIP/MGCP/H.248 protocol between the ONU/ONT terminal and the SS. After the Protocol connection is completed, the ONU/ONT terminal can be properly registered to the SS.

In SS access, ONU/ONTIP can be allocated in two ways:

First, use the private network address of the SS. ONU/ONT is directly connected to the logic/physical private network of the softswitch SS. The protocol processing is convenient, similar to the current access method of China Telecom for AG/TG/SG. This method has a certain impact on the security of the NGN network, and is generally used for devices trusted by operators.

Second, use a broadband gateway device. After using a broadband gateway device, you can use a private IP address within the LAN of the Gateway. You only need to use a public IP address for the gateway device, when a user calls the SS through a local IP address, the gateway device converts the IP address to an Internet egress address and exchanges it with the SS. The data in the SS direction is also converted to the corresponding ONU/ONT. Using this method will increase the processing requirements for the broadband gateway device BAC, but it also has the advantage of good confidentiality and low address occupation. It is generally applied to devices such as the operator's untrusted client IAD and soft terminal.