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A turbo compressor for mobile surfers

February 20, 2003

Despite faster Internet connections, many users still resentfully associate the three letters www with "world wide wait". This is also due to the fact that files are constantly increasing in size. When using wireless terminals with low-resolution displays, such as palmtops or PDAs, it is not in fact necessary to transfer all elements of a Web page, designed for display on large, high-resolution monitors. Although mobile service providers offer solutions to this problem, access is then limited to preselected sites, in the same way as the WAP service.

A data compression system developed by the Fraunhofer Institute for Microelectronic Circuits and Systems IMS provides access to all Web sites with a two to three-fold decrease in download times. This software reduces the resolution of graphical elements and compresses them, without the user noticing.

"For technical reasons, however, this doesn't work with all file formats," admits Alexander Coers, who developed the compressor. "Although, for example, it reduces JPEG images to the resolution of the display, the commonly used but mostly smaller GIFs remain unchanged." The software also compresses the most widely used text formats: HTML and its relative XML are compressed in the same way, as are ASCII and plain text (txt). On the other hand, pages in PDF (portable data format) are transferred in their original format.

The data flow is as follows: When a user wishes to view a particular Web page on a wireless terminal (the client), the browser requests it via the proxy client installed in the terminal. The proxy client communicates with the proxy server, a computer connected to the Internet that "recognizes" its clients' needs. The proxy server downloads the Web page from the Internet and the integrated compressor reduces the size of the files it contains. Finally, it sends the Web page to the wireless client, whose proxy decompresses the data. The browser then presents the Web page on the display.

This process works with all terminals that support the widely used Java programming language. There are also few restrictions in the choice of browser: The compressor software is compatible with every browser program capable of communicating with the Internet via a proxy server.

Fraunhofer-Gesellschaft