2G Mobile Wireless Services - WAP and iMode

WAP is an open-application layer protocol for mobile applications targeting cell phones and wireless terminals. It was developed by the WAP Forum, which has been consolidated into the Open Mobile Alliance (OMA). The current release is WAP 2.0. WAP is intended to be the World Wide Web for cell phones. It is independent of the underlying cellular networks in use. To a cell phone or PDA user, WAP is perceived as a small browser application that can be used to browse some specific websites, quite similar to the web browsing experience on a desktop computer but with significant constraints due to the form factor of the mobile terminal. A WAP system employs a proxy-based architecture to overcome the inherent limitations of mobile devices with respect to low link bandwidth and high latency. Below is a list of features that separate WAP from other application protocols:

• Wireless markup language (WML), WML script, and supporting WAP application environment: Together, they are referred to as WAE. WML is an HTML-like markup language specifically devised for mobile terminals that have limited bandwidth, fairly small screen size, limited battery time, and constrained input methods. WSL is a scaled-down scripting language supported by the WAP application environment. In addition, WAP 2.0 supports XHTML language, which allows developers to write applications for both desktop computers and mobile terminals.

• WAP protocol stack: WAP Version 1.0 includes wireless session protocol (WSP), wireless transaction protocol (WTP), wireless transport layer security (WTLS), and wireless datagram protocol (WDP). Version 2.0 incorporates standard Internet protocols into its protocol stack, such as TCP, transport layer security (TLS), and Hyper Text Transport Protocol (HTTP). Both TCP and HTTP are optimized for wireless environments.

• WAP services, such as push and traditional request/response, user agent profile, wireless telephony application, external functionality interface, persistent storage interface, data synchronization, and multimedia messaging service.

WAP 1.0 has proved to be a technological hype; it has been intensively promoted by wireless operators and content providers but has received little, if any, positive feedback from users. Because of that, WAP has sometimes been referred to as “ wait and pay. ” Interestingly, it is not only the protocol but also the applications utilizing WAP that, as a whole, push users away because of application performance, input methods, and the GUI interface, among other reasons. Moving toward standard IP protocols rather than specialized wireless protocols, WAP 2.0 addresses most of the problems of the protocol stack and the application environment, thereby giving the technology a brighter future.

iMode is a successful wireless application service provided by NTT DoCoMo. It is very similar to WAP in that it defi nes an architecture of web access on mobile terminals, primarily cell phones. Like WAP 2.0, iMode adopts standard Internet protocols as transport for applications, but iMode does not use any gateways. Instead, it utilizes overlay packet network on top of a cellular network for direct communication. The fundamental difference between WAP and iMode is that iMode requires mobile terminals to be designed to adapt to the services and applications of iMode, while WAP focuses on adapting itself to fi t into general mobile terminals. Furthermore, NTT DoCoMo’s effective WAP initiative has managed to attract many satisfied providers who can offer a wide array of services and applications to users.

Source of Information :  Elsevier Wireless Networking Complete 2010


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