GPRS Videophone

Student: Benjamin Charles Appleton

Supervisor: Dr. Vaughan Clarkson

Category: Electrical Engineering Thesis Project

Mobile videoconferencing is a commercial gold mine, widely recognised as the next big step in mobile communications. The introduction of widely available mobile videoconferencing will bring a host of applications including advanced telecommuting, remote job interviews, telemarketing, improved distance learning, telemedicine, and the obvious advantage to interpersonal communications. Many big players in the communication and computing industry are planning to launch products in this market over the next 10 years. However, one serious obstacle must first be overcome: the difficulty of sending a high bandwidth video signal through a low bandwidth mobile phone system. It is one of the major problems driving two large fields of research: high-bandwidth wireless communication systems such as 3G networks, and new low-bandwidth videoconferencing standards such as H.324/M and T.120. It is inevitable that within the next decade these efforts will converge to produce high-quality mobile videoconferencing accessible by the general public.

Today?s video compression technology lags well behind the new techniques being published by leading research groups. As the field of video compression matures, video compression techniques are emerging which are strong enough to allow video conferencing over existing mobile phones. Analysis-synthesis speech compression and wavelet video compression allow videoconferencing at data rates so low as to be previously unthinkable. Therefore it makes sense to bring together the strongest compression techniques currently available to make a mobile videophone that operates at the currently available data rates.

The system demonstrates good performance at 25kbps (GPRS) with satisfactory performance at 12kbps (GSM). A variable bit rate speech codec based on LPC-10e has been developed requiring only 600bps, significantly increasing the bandwidth available for video. The proprietary video compression scheme developed is scalable to ensure that the quality will improve with future bandwidth increases. A prototype has been implemented on a laptop computer with a GPRS phone, demonstrating the system?s potential.

Poster Presentation (PDF)

Thesis Document (PDF)

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