MMS learning-network structure and working principle

Http://blog.csdn.net/long4u/archive/2005/10/23/514161.aspx

MMSNetwork structure and working principle

Implementation of MMS
The implementation of the multimedia short message service system must be flexible, and the interoperability between different types of networks and terminals is convenient for integrating and developing new businesses.
The multimedia SMS System can be implemented in two ways: WAP-based implementation and IP-based implementation.
(1) WAP-based implementation
WAP provides strong support for MMS implementation in both business specifications and underlying technologies. The protocol stack structure 3-2 that uses WAP to implement the MMS service is shown in.

Figure 3-2 MMS protocol stack structure based on WAP

In MMS applications implemented using the WAP protocol, the entire link can be divided into two parts. The first part is the link between the MMS user proxy and the WAP Gateway. It uses the WAP protocol stack structure and provides common services on various wireless media. Application-oriented services similar to MMS are provided by WSP (WAP Session Protocol. The second part is the link between the WAP Gateway and the MMS repeater. The connection between them uses the IP technology, and the high-level layer uses the difficult HTTP protocol for communication. During the communication process, the WAP Gateway is a transparent device and does not make any interpretation or modification to the data forwarded by it.
A typical MMS communication process goes through the following stages;
◆ The MMS user agent sends multimedia text messages;
◆ MMS repeater notifies the target user of the arrival of multimedia text messages;
◆ The target MMS user agent receives multimedia text messages;
◆ The target MMS user agent sends a receiving confirmation message to the MMS repeater;
◆ The MMS repeater reports the multimedia text message delivery results to the source MMS user agent.

(2) IP-based implementation
In addition to WAP-based implementation, 3GPP is developing an IP-based MMS implementation scheme. Figure 3-3 shows an IP-based MMS protocol stack structure, and uses the TCP protocol optimized for the characteristics of the wireless network as the transport layer protocol. Based on different services provided, application layer protocols such as SMTP, POP3, IMAP4, and HTTP can be used for communication between MMS user agents and MMS repeater/server.

 

Figure 3-3 IP-based MMS protocol stack structure

Similar to the WAP-based implementation, the link between the user terminal and the MMS server/repeater is also divided into two parts. The two parts use the same high-level protocol. The difference lies in the transport layer protocol. The MMS user proxy and IP gateway can use a suitable wireless link.
TCP protocol, while common TCP protocol is used for communication between the IP Gateway and the MMS repeater/server.

Personal notes:

The implementation of the WAP protocol stack is cumbersome. Starting from WAP2.0, The Protocol introduces the HTTP protocol, that is, wireless profiled HTTP and wtcp, which is easy to implement. We know that in the OSI Layer-7 protocol structure, HTTP belongs to the application layer, TCP belongs to the transport layer, and IP belongs to the network layer. In this way, we will have a better understanding of the IP-based MMS protocol stack. The encapsulation of MM will be discussed in the next article. It should be noted that after using HTTP as the carrier, it is no longer connected to mmsc using WAP Gateway, but through IP Gateway (Wireless HTTP, via GPRS wireless ).

Note that, in 3-3, the implementation is based on the IP address, and the gateway label in the figure should be problematic. This still affects understanding. I have read this image and thought that this method does not require WAP Gateway. The correct implementation principle is as follows. Even so, the previous figure provides more detailed information to help us understand.