This article discusses several ways to connect the WAP gateway server and the mobile network, and the corresponding protocol stack, and it has been further applied to some preliminary discussion. 1. Introduction The current WAP has become a hot topic in the field of information technology (IT), and there are more articles and discusses in this regard, involving all aspects of WAP, such as the protocol stack itself, WAP various applications, etc. Indeed, WAP realized the dream of 'Internet surfing', and is one of the best modes of wireless communication and Internet combination. The WAP application is also quite rich, and its greatest feature is the flexibility of the system structure and the openness of the protocol. WAP Gateway Server is the key part of the mobile network, which directly determines its application model directly with the connection mode of the mobile network. can. This article will talk about the preliminary view of further strengthening the function of WAP gateway server.
2. Classic WAP Application Structure Model Basic Structure Based on WAP Forum (WAP Forum) Basic Structure is BEARER Wireless Data News Agreement (WDP) Transmission Layer Security Protocol (WTLS) Transaction Layer Agreement (WTP ) Conference Layer Protocol (WSP) Wireless Application Environment (WAE), in the latest WAP1.2 version, Many new application patterns, such as 'push' (push, to actively send the Internet content to a mobile user Agreement), etc. The WAP protocol stack is applied to the structural model as shown in Figure 1. The WAP gateway server as a core component mainly completes two functions: implementation of protocol conversion between WAP protocol stack (WSP / WTP / WTLS / WDP) and Internet Protocol (HTTP / TLS / TCP / IP); Decoding, the WAP data is compressed and encoded to reduce network traffic, maximizing wireless resources. WAP implements mobile phone Internet, is coordinated by mobile terminals, mobile networks (composed of base stations and switches), WAP Gateway Server and Network Content Supplier (ICP), Network Service Providers (ISP). This typical mobile Internet access process can be briefly described as follows: (1) Mobile request; (2) Mobile network (GSM, CDMA or other mobile network) Turn on local ISP; (3) Local ISP connection WAP gateway server; (4) The WAP Gateway server issues a request to the target content server; (5) The target content server passes the information to the WAP gateway server; (6) The WAP gateway server sends the process to the local ISP; (7) Local ISP back mobile back Network; (8) The mobile phone receives Internet information; it can be seen that the network entity involved in this process is more complicated. At the same time, the WAP gateway server is only used as a gateway, which is relatively insufficient. Therefore, it may be possible to use the openness of the WAP protocol to change this single connection form to achieve the purpose of making the powerful storage and processing capabilities that use the WAP gateway server to make it a true 'server'. 3. Several forms of WAP Server and Mobile Network (MN) Connections and Changes of Protocol Stacks 3.1 Connection Form WAP As a gateway server (Gateway connection Mn and Internet), the connection to the mobile network is to determine its structure and function. The main factor, the so-called 'WAP Gateway Server Solution'. For mobile networks that use packet exchange, such as GPRS and third-generation networks, WAP gateway servers can use IP directly connected to it, this will not be discussed here. However, for non-IP networks, such as GSM circuit exchange data (CSD) networks, etc., it is possible to use no change in connection. These variations are described below with the current application of more common CSDs and short message (SMS) bearers as an example, and the advantages and disadvantages of the pros and cons, and the performance of the WAP gateway server.
(1) The WAP gateway server and the Mn may have three connection situations on the circuit exchange data bearer entity, as shown in FIG. The first form is a classic method, and the CSD passes through a series of intermediate conversion (sequentially after IWF, PSTN, MODEM), and finally by ISP provides IP connections to the WAP gateway server; the second way is directly provided by mobile network switches Connect to ISP, by ISP provides IP connections to the WAP gateway server, and ISP acts as a role of protocol conversion between CSD and IP. The third way is to provide digital relays directly by mobile network switches, connect to the WAP gateway server. The first way can make full use of the current infrastructure, ie the quantity user line can achieve connection with the WAP gateway server, the direct advantage is that the WAP service provider will increase, which can fully introduce competition and improve services. In the second way, ISP recommends requires relatively expensive trunk, and also assumes the tasks of the protocol conversion between CSD and IP, which may affect the enthusiasm of ISP participation in WAP services. The third way is the most concise, reliable, but need to be used by the WAP gateway server to assume the protocol conversion work of CSD to IP, in which the WAP gateway server also plays the role of ISP. From the perspective of making full use of WAP gateway server, the third program will be a better solution. (2) On the short message service carrying entity on the short message service (SMS) load entity, there are two connection situations in the WAP gateway server and MN, as shown in Figure 3. The first solution is a classic program. The second solution is moving the function of the wireless data gateway to the WAP gateway server in the case of retaining the short message center, which is to make the WAP gateway server bears as many functions as possible. At present, the short message service supported by mobile network has limited traffic (maximum of 140bytes content), and there is not much sense to carry the Internet. Further consideration is to apply the WAP gateway server as a short message service center, which has a greater practical value. From the perspective of telecommunications equipment manufacturers, two carrier entities (actually promoted to all carrying entities) tend to choose a more powerful solution for the WAP gateway server. As a result, the WAP gateway is borne by a computer that is large and has a strong processing capacity. If only the role of the gateway is complete, there is a 'large material small use'. Therefore, in order to make full use of existing capabilities, a part of the function is moved to the WAP gateway server, which is completely feasible. And for operators, such networking methods are simple to connect, relatively low cost, reliable operation, convenient maintenance. In theory, the openness of the WAP protocol can guarantee the flexibility of these various connections.
3.2 The protocol stack design The above-mentioned change in connection has brought the corresponding changes in the protocol stack. As an open technology, the WAP protocol is designed to support these changes. The following is still the case of the protocol stack as an example in the case of GSM and CDMA bearer entities. 3.2.1 The WAP protocol stack on the CSD bearer entity is shown in Figure 4-6. The first solution is a typical protocol stack structure without any changes. In the second solution, the subnet from the ISP to the WAP gateway server can be any transmission network, such as LAN, WAN, etc. based on Ethernet, etc., which saves PSTN connection and related protocol conversion, in ISP and mobile networks. Establish PPP directly. The third solution must establish a direct connection similar to dialing between mobile networks and WAP gateway servers, which can be done by the PPP protocol.
3.2.2 The WAP protocol stack on the SMS bearer entity is shown in Figure 7-8. In the first schede, Wireless Data Gateway will be encapsulated in the IP Tunnel, transferred to the WAP gateway server, and the WAP gateway server removes SMS from the tunnel, and the down process is also, this It is also a typical solution. In the second scenario, the tunnel transfer is omitted, but must be converted from a short message implementation interface (SME-IF for GSM, MC I / F for CDMA) to complete the conversion of the short message to the WDP protocol, the wireless data gateway integrates WAP gateway servers. The change in the open WAP protocol structure is not only feasible, but also relatively simple, the efficiency improvement is worthy of attention. 4. The deep application of the WAP Gateway server is currently induced by the WAP gateway server that can only implement the basic application defined by the protocol, that is, transmitting the Internet content, only to the role of the gateway. In fact, the applications defined by the WAP protocol are far less than these. The business that WAP can provide should be more inconvenient. In addition to the use of changes in the use of changes to the mobile network to give the WAP gateway server more powerful feature, the WAP gateway server can also provide users with a variety of value-added services and the so-called 'personalized service'.
Email is a typical value-added business, and it is also more popular in WAP business. Provides users such as address directory management, personal information services (such as geographic positioning, etc.) reflect the feature of the WAP gateway server to truly implement 'personalized service'. Due to the restriction of mobile terminal memory and processing power, implement these functions, the WAP gateway server can handle and store this information and content, and can be delivered at any time when the user needs. With the WAP transport layer security protocol, it is important encryption and who works in the field of mobile e-commerce. It is also placed in the WAP gateway server to complete, save the heavy processing tasks for mobile networks and terminals. The WAP protocol stack also retains a part of the definition of future WAP applications and services, which can be done in the WAP gateway server under appropriate conditions. Without the short message bearer entity to transmit Internet content, there is no practical value, but the function of using the WAP gateway server to complete the short message center is a good idea, and telecom operators should welcome this program. It can be expected that the WAP gateway server may also be paid more use in the future to become a comprehensive gateway server. 5. The opening of the Connection WAP protocol allows the WAP gateway server and mobile network to have a variety of ways, thus launching the basis for improving the traffic of the WAP gateway server, but also ensures the flexibility and diversity of design, development, installation, operation. . At the same time, the WAP gateway server can be given a variety of functions of the WAP gateway server, and its application mode changes with the development of technology and market.
