Analysis of the most popular multimedia informatio

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Analysis of multimedia information service interworking technology

multimedia information service is the Chinese name of MMS (Multimedia Messaging Service). Multimedia information takes WAP Wireless Application Protocol as the carrier to transmit information in various multimedia formats including text, image, sound, etc. through the GPRS network of mobile operators, so as to realize the real-time end-to-end, terminal to terminal interconnection or interconnection to terminal multimedia information transmission. In March2001, Swedish Ericsson sent the world's first multimedia message in Cannes, France. Since then, MMS has been sought after by many terminal manufacturers, equipment manufacturers and mobile operators

1. MMS system structure

mms system mainly includes MMSC (Multimedia Messaging Service Center), WAP (Wireless Application Protocol) and VAS (value added services) systems. MMSC is the core of multimedia message network

mmsc consists of MMS server, MMS relay, information storage and database. MMSC provides storage and operation support, allowing end-to-end and end-to-e-mail instant multimedia information transmission, while supporting flexible addressing capabilities. MMSC needs to run many interfaces connecting other networks (such as the Internet), and provide open and standard API interfaces to support the application and development of value-added services. MMSC can make a smooth transition during the evolution of mobile communication network from the second generation to the third generation

wap off: since MMS uses WAP as the transmission protocol, it needs to be connected to MMSC through WAP off

DNS (DomainNameSystem)/enum (telephonenumber mapping): the MMSC to which the sender belongs obtains the domain name of the MMSC to which the receiver belongs by querying DNS/enum

billing system: MMSC can be used as the billing information collection point to transfer the billing information to the billing system

the value-added service system includes multimedia terminal, multimedia e-mail, information transmission and multimedia voice

II. Interconnection between MMS operators

in order to successfully carry out MMS services, MMS interconnection between different operators is very important. From a technical point of view, MMSCs of different operators can be interconnected through the existing stable and reliable IP network between operators (between domestic operators) or through public IP network and dedicated line (frame relay, ATM)

1. Direct connection scheme

mms operators can realize interconnection through the direct connection scheme in three ways: by establishing a tunnel on the public IP, such as using IPSec technology; Direct connection through dedicated lines, such as FR and ATM; By building VPN on the dedicated line

x (gprsroamingexchange) scheme

first of all, the lead screw replacement precision is slightly worse. Let's introduce the Grx network. Grx network is used to connect different GPRS backbone networks that can improve the quality in the detection process (reduce human interference) and reduce the working intensity of experimenters, so as to realize the interconnection between GPRS networks. Different from direct connection, Grx network is an IP network professionally operated and managed by a third-party company, which is responsible for the interconnection between GPRS networks of different operators. As Grx network is the core node of GPRS network interconnection, GPRS operators can realize interconnection with many GPRS operators at the network level by interconnecting with one or a few Grx operators

MMS service international interworking is realized by using Grx network. Operators providing MMS service can avoid establishing a large number of direct connections with all interworking partners, and only a small number of connections with Grx operators can meet the interworking requirements. Therefore, one of the keys for MMS service operators to realize interworking is to select appropriate Grx operators as partners and adopt appropriate interconnection schemes according to business needs

at present, there are nearly 20 Grx network operators in the world, which connect most of the global GPRS networks. In february2002, Finnish operator sonera and Estonian operator EMT realized the world's first mm (multimedia message) International interworking through sonera's Grx network. In June2002, sonera, a Finnish operator, and CSL, a Hong Kong operator, realized the first mm international interworking between Asia and Europe through the Grx network of sonera and Aicent

(Note: sonera is both a GPRS operator and a Grx operator; Aicent is a Grx operator)

III. MMS interworking business process

mms interworking basic business process is shown in Figure 1

Figure 1 basic process of sending multimedia SMS from network a user to network B user

user a sends mm message to user B. Mm messages are transmitted to MMSC of network a through SGSN (Serving GPRS support node) and GGSN (gateway GPRS support node)

MMSC of network a analyzes that the called user is the user of network B through MSISDN of user B (receiver), and requires network B to verify user B

the HLR of network B replies to the MMSC of network a and provides the IMSI number corresponding to the MSISDN of user B

MMSC of network a establishes a prefix of "mms." by analyzing MCC and MNC of IMSI The domain name address of which is sent to the DNS server connected to MMSC

the DNS server of network a retrieves the IP address of the DNS server of network B. If it is not retrieved, the DNS server of network a will address the root DNS server to obtain the IP address of the DNS server of network B

the DNS server of network B sends the IP address of this MMSC back to the DNS server of network a

the DNS server of network a transfers the IP address of the MMSC of network B to the MMSC connected to it

MMSC of network a sends mm to MMSC of network B through BG, VPN or Grx of this network and BG of network B

through the wap push function, the MMSC of network B sends a notification about the receipt of a new message to user B (depending on the specific implementation, SMSC is applied to the WAP Push Service)

after receiving the notification containing the subject, size and message URL, user B receives the MM message from the terminal to the MMSC according to the above message

Figure 1 is a simplified figure. For example, normally BG should include firewall and SMTP functions, and WAP customs (including push proxy customs) can also be separated from MMSC

IV. relevant technical characteristics and issues needing attention of MMS interworking

it is very important and key to understand the technical characteristics of MMS interworking. MMS service network interconnection between operators mainly requires the implementation of MM4 interface between MMSCs, which adopts simple mail Transfer Protocol SMTP (3gpp23.140) based on IP. In addition, GSMA (globalsystemfor Mobile Communication Association) has developed ir 52 standard, which is used to define the MM4 interface between MMSCs, through which multimedia messages can be transferred from one MMSC to another on the IP network. So far, many MMS operators have followed this standard to realize interconnection

on the network side, it is not necessary to build any kind of independent exchange network that only serves MMS interworking. Before using MMS between public Internet transmission operators, QoS, security, interconnection network control, reliability and support for new network features have been applied in Grx network. This is because, in fact, Grx can be regarded as a network controlled by operators, unlike the public Internet, which is open to everyone

using the Internet as an MM4 interface can cost less than Grx, but it is also not free. Using the public Internet as the Internet will also cause some problems and costs, such as message security rules (for example, it is impossible for all operators to use VPN that can operate together), address filtering rules, and garbage message control. MMSC is never directly connected to the IP interworking backbone, but all MMS messages must pass through BG gateway, firewall or SMTP, accounting for 10.8%; Equipment with a stroke of more than 1000mm shall be closed

it should be noted that if one side of the MM4 interface uses the public Internet (VPN or no VPN), while the other side uses the Grx network, MMS interworking will have some problems. Such a connection is difficult to implement. For example, the DNS query to obtain the called MMSC address is one of the factors affected, because Grx and the Internet have their own DNS systems. Therefore, operators must negotiate the MMS interworking technology. For example, operators need to modify the interworking network interfaces of the internal IP network structure of operators, such as firewalls and proxy gates. Due to cost and capacity, even if operators can deploy various networks according to demand, we also recommend using a unified network to transmit messages on the interworking MM4 interface to reduce relevant options. If MMS interworking is very successful, MMS traffic is likely to greatly increase the use of Grx. Grx will not only be a simple IP backbone

in terms of business application, we should also make a comprehensive examination of the use of the product in the fields of auto parts, electronics and communications, household appliances and furniture, railways, military aviation, medical treatment, etc. When there are many interworking partners, Grx scheme has advantages over direct connection scheme. The workload of using Grx to carry MMS services is smaller than that of directly contacting all MMSCs. The operator should evaluate the physical connection of the MM4 interface and select the most appropriate one. Considering some commercial and business factors, leased line or IP-VPN network is more effective for some operators with relatively concentrated destinations (for example, MMS receiving users are mainly concentrated in a few operators). Because the transmission of IP messages is separated from the upper layer addressing, and at the same time, the interface will have several physical connections

v. conclusion

we mainly discussed the network scheme for MMS operators to implement interconnection and the business process of MMS interworking. The implementation of MMS interworking service will bring new business enjoyment to users and make mm interworking between different operators possible. Now more and more operators have started commercial MMS interworking, especially in terms of international interworking, which will be one of the key businesses of mobile operators. For mobile operators, their business prospects will have irreplaceable attraction. (end)

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