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Voice Feature Guide 01

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Voice Technology Development

Voice Technology Development

Figure 1-1 shows the voice technology development. The public switched telephone network (PSTN), next generation network (NGN), and IP multimedia subsystem (IMS) are widely used for communication.
Figure 1-1 Voice technology development

PSTN

PSTN is a connection-oriented network based on timeslot switching. Each circuit connection occupies a timeslot of the pulse code modulation (PCM) basic group, that is, the switching circuit is performed at the rate of 64 kbit/s, which cannot be changed. Advantages and disadvantages of PSTN are as follows:
  • Advantages: Fast switching speed, accurate obtaining of call duration, short transmission delay, small jitter, supporting services with high requirements on real-time (especially telephony services)
  • Disadvantages: Supporting only 64 kbit/s, exclusively occupying allocated network resources, and low resource usage

NGN

NGN is an integrated network. NGN, a packet-based network, employs the IP technology to build the carrier network and implement the separation of call control from bearing.

For packet voice services, the NGN uses a softswitch as the control layer, IP as the bearer layer, and AG as the access layer. Voice over IP (VoIP) is an important application of packet voice services.

VoIP

To implement VoIP, analog voice signals are compressed and encapsulated into data signals and then transmitted on the IP network, as shown in Figure 1-2. The example usage of VoIP is IP call. In a narrow sense, the VoIP only refers to the voice signal transmission. In a broad sense, the VoIP also refers to data signal transmission, that is, modem over IP (MoIP) and fax over IP (FoIP).
Figure 1-2 VoIP implementation

IMS Network

With the development of telecommunication technology, users want to use voice services to facilitate work and life instead of the traditional voice communication. As a result, a stronger communication platform is required to provide integrated voice, video, and mobility features, as shown in Figure 1-3. The IMS network is developed to meet requirements.
Figure 1-3 Communication requirements
The IMS is a system that controls IP-based multimedia sessions on the NGN. The IMS network contains all core NEs that implement multimedia services, including video, audio, text, and instant messaging (IM).

IP =

IP-based transmission

IP-based session control

IP-based service implementation

Multimedia =

Supporting multimedia services including video, audio, image, and text

Subsystem =

A system using the advanced network technology and devices

The IMS network was designed by 3rd Generation Partnership Project (3GPP) in the R5 version to support IP-based multimedia services.

The IMS network features the following:
  • Same as the softswitch, call control is separated from bearing.
  • Services are separated from call control, which speeds up new service provisioning, as shown in Figure 1-4.
    Figure 1-4 Control, bearing, and service separation
  • The IP-based IMS network is an integrated core network that can be shared by the mobile and fixed networks.
  • The IMS network uses E2E SIP signaling. Services and terminals are developed toward intelligence.
    • The control plane using the SIP protocol to control signaling in a centralized manner.
    • The service plane using the SIP protocol to provide a uniformed session mechanism for all services.
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Updated: 2019-02-22

Document ID: EDOC1100067358

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