Key to implementing multimedia services based on Softswitch

Due to the importance of multimedia services, the softswitch system initially considered support for multimedia business applications from several main aspects.

First, in terms of the network structure, the processing and calling of multimedia applications are separated, and the unique information processing functions of multimedia services are implemented in media servers and smart terminal devices, general call control and service provision are completed in softswitch devices and application servers. Secondly, from the Protocol perspective, the H.323 protocol is developed for multimedia communication, and the SIP protocol is constantly improving its support for multimedia capabilities. As the cornerstone of the softswitch system, the H.248 media gateway protocol has defined a multimedia extension package. Currently, the ing between H.324 and H.320 protocols to H.248 protocols is being improved. Finally, from the perspective of business capabilities, the open business generation and provision environment makes the development of multimedia applications faster. Currently, the Parlay-based API interface specifies the function set of multimedia applications in detail and organically integrates with applications such as voice and data.

The softswitch system that supports multimedia services does not support the Integrated MCU mode adopted by H.320 and H.323 conferencing systems. It makes full use of the open features and advantages of the group exchange bearer network. The following two new layered models can be used to better meet the profitability needs of operators. The first mode is the separation scheme of MCU, that is, MCU is mainly composed of MC Multi-Point Controller) and MP multi-point processor). MC focuses on the control function and MP focuses on the media processing function. The separation center is MCU split into two parts, and the control part and the media processing part are separated. These two parts originally use internal interfaces, which are actually private interfaces. After the separation, the two parts are implemented using the standard protocol H.248. The second mode is the integration solution, that is, due to the separation of MCU, the MP device can be used as the media resource of the Media Server and will continue to be used in the next generation network system under the control of the softswitch device. MC devices and optional GK devices are completely replaced by Softswitch devices and application servers. Compared with the integration scheme, the softswitch device can completely control the media server. Therefore, this solution provides flexible business development capabilities and makes full use of the open business interfaces provided by Softswitch to facilitate operators to carry out comprehensive video and multimedia services.

In the softswitch system structure that supports video multimedia services, MP is mainly responsible for audio, video, and data mixing, switching, and synchronization of multimedia meetings. In addition, it also provides the Conversion Function of Speech Encoding. MC provides conference telephone and video conference control functions to centrally manage meetings. It can coordinate the multi-point processor with various terminals for voice, video, data codec, and priority settings. The adaptation gateway is responsible for receiving and processing signaling and audio, video, and other media streams from non-data user terminals. It can process one or more media streams, after processing, it is sent to the corresponding MP or user terminal. The signaling messages sent by the user terminal are mapped to the corresponding messages and forwarded to the softswitch device by the gateway. The Media Server provides special media resource functions, such as voice notifications and digital receivers. It also supports personalized Dynamic Language Programming and dynamic resource loading and modification. The softswitch system structure that supports video multimedia services can be divided into four layers: Access, transmission, control, and service.

The access layer provides a wide range of network and terminal device access, including H.320 terminals, H.324 terminals, and other types of terminals used on the existing network) smart terminal devices, such as SIP terminals, H.323 terminals, MGCP terminals, H.248 terminals, and soft terminals, as well as media servers. For H.320 and H.324 terminals, the gateway can map the control protocol of the Media Gateway and convert the information format to the information format that can be transmitted on the group network.

The transport layer is a packet exchange network composed of IP routers or ATM switches. It provides a unified transmission platform with high reliability and QoS Assurance for the softswitch system.

The control layer is mainly composed of softswitch, which implements call control and connection management, controls network resources, transfers corresponding business processing information, and provides open business interfaces to the business layer.

The business layer mainly refers to the devices that provide various services and services to users. It uses an open and integrated business access platform to provide various value-added services, multimedia services, and third-party services for the Next Generation Network. At the same time, it also has the corresponding business generation and maintenance environment.

In terms of the voice service development of a fixed network, the softswitch network is very mature. However, in the video multimedia field, the softswitch network is in its infancy. To meet the requirements of the Next Generation Network, it must expand its application field. If it is used in the multimedia field, image and other factors are involved, it is much more demanding in terms of terminals, services, resources, and other aspects than pure voice services. In this case, Softswitch must have multiple-point conference control, information exchange control, and other control functions. It supports protocol interfaces with multimedia terminals, multi-point controllers, and multimedia gateways to implement various video and multimedia services.

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