33.3 WIRELESS INTERNET APPLICATIONS

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Because of the limited capabilities of mobile devices, applications such as browsing can be limited. Hence, developing applications/content for mobile devices is a challenging task. The various applications include e-mail, mobile commerce, entertainment, business services, news and weather information, and so on.

As the wireless networks support higher data rates and as the capabilities of the mobile devices increase, the applications can support high-resolution graphics, and audio and video streaming applications as well. As a result, users can carry out audio and video conferencing while on the move. Because audio and video communication requires real-time streaming, the mobile devices should be running a powerful mobile/real-time operating system with capability to do signal processing for encoding and decoding of audio and video signals.

Applications such as e-learning, telemedicine, and location-based services will provide users with an enhanced quality of life largely because of the anywhere, anytime communication capability.

The applications that are supported for wireless Internet access must be highly focused. E-mail, mobile commerce, entertainment services, and tourism information are the most widely used applications.

33.3.1 Pull Model and Push Model

Normally, when we access the Internet, we use the pull model. From the desktop, we make a request in the form of a URL, and we obtain the response from the server in the form of content in text format, which is interpreted by the browser running on the desktop. The pull model can be used by mobile devices to access information from the Internet servers.

Another model, the push model, also can be used effectively in a mobile environment. In this model, the server will send the content to the mobile device without the user explicitly making a request by giving a URL. For example, if a user is interested in obtaining the details of a baseball game, he can register with a Web site by giving his mobile number and how often he would like to receive the information (such as hourly). Then the server will automatically send the scores every hour. To ensure that the pushed content does not intrude into the work of the user, the following procedure is followed:

The user registers with a Web server, giving the details of the mobile number and the frequency with which he would like to receive the information.
The server sends a small message called a service indication. This message is an alert to inform the user that the scores of the game are being sent and asking the user if he would like to view the information now. The service indication also contains the URL from which the content is to be obtained.
The user can select yes or no. If the response is yes, the URL in the service indication is invoked, and the content is presented to the user. If the user response is no, then the service indication can be stored in the cache memory of the mobile device, and the user can retrieve it later to see the content.

In the pull model, we give a request to a server by specifying a URL, and the server downloads the content onto the desktop. This is called the pull model because we pull the information by specifically giving a URL.

This procedure is followed to avoid intrusion. It would be annoying if a message is received when the user is composing an e-mail for instance.

The push model is useful for such applications as obtaining stock quotes periodically, for obtaining sports information periodically, and for pushing advertisements of the user's choice.

In push model, the user need not make a request repeatedly to obtain the information. The server can automatically send the information periodically to the user.

Note

In the push model, to avoid intrusion, the server first sends a small message called service indication, which is an alert to the user that the requested information is to follow. The user can either view the information immediately or postpone it to a later time.

33.3.2 Location-Based Services

Location-based services are now catching up very fast. These services provide location-dependent information to the users when they are on the move. For instance, when a person enters a new city, he can obtain local information such as the availability of nearby hospitals, hotels, and restaurants. This is achieved by sending the location information (longitude and latitude) of the mobile device to the server. A GPS receiver can be integrated into the mobile device, and the mobile device automatically sends the location information to the server along with the request for, say, a hotel in the vicinity. The server will use the location information to find the hotels in that locality and send the hotel information to the mobile device.

In location-based services, the location of the mobile device is sent to the Web server. The Web server sends the information specific to the area in which the user is located, such as nearby hotels, tourist spots, and such.

To exploit the potential of location-based services and at the same time to ensure interoperability between mobile positioning systems developed by different organizations, the Location Interoperability Forum (LIF) was founded by Ericsson, Motorola, and Nokia in September 2000.

Location-based services will be of immense use in public safety and emergency services. New, exciting personalized services also can be developed using this technology: a user can locate friends when visiting a place, or he can be alerted on his mobile phone when a friend (or an enemy!) is in the user's vicinity. These services will be made available on both 2G and 3G networks.

Note

To provide location-based services, the mobile device has to be fitted with a GPS receiver. The GPS receiver obtains the longitude and latitude of the mobile device, and the information is sent over the wireless network to the Web server.

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