Subject: Question

From: Kazi Rahman <[email-masked]>
Date: Wed, 8 Sep 1999 09:49:05 -0500 (CDT)

Dear Sir,

 I am currently working with  my thesis on 3-G mobile videophone. There
may be loss of synchronization in voice and video with rapid movement of
the end users. My research area is to work on the improvement of voice and
video synchronization in case of high mobility of the videophones. 

In my opinion, this phenomenon due to bit error. Because
motion-compensated temporal prediction works best for scenes with limited
amount of linear motion. Scenes with a lot of motion or with complex type
of motion therefore produce more coded data. This, in turn, will affect
the available resources of the network. We can use VBR. But in this case
the mean and peak data rates should be negotiated at the beginning of
connection establishment. VBR uses open loop encoded video that has both
short-term and long-term variations in the bit rate. If the mean and/or
peak bit rates continue to change which is common for rapid moving
objects, then the video source may violate the traffic parameters agreed
to at the start of the connection.

One conventional solution is to use buffer at the encoding end. But this
may cause extra delay in case of mobile videophone.

What do you think I should do to reduce BER at the minimum level ? A
solution I was thinking is to design a gateway that will provide necessary
compensation to the loss of synchronization of voice and video due to
mobility of the end users.

Kazi Shafiqur Rahman
Graduate Student, Dept.  of Electrical Engineering.
The University of Texas at Arlington
Arlington, TX 76010, USA
Student Member, IEEE.