Introduction - If you have any usage issues, please Google them yourself
The voice channel in mobile communication systems have high priority and are
almost always available. By using the voice channel also for data transmissions it
is possible to get the same availability as for voice calls. But due to speech codecs
in the voice channel, regular modems can not be used and special techniques are
needed to transmit data.
This thesis presents methods to transmit data over the voice channel in a GSM,
UMTS or TETRA network. The focus has been on robust data transmission rather
than high data bit rates. Approaches are introduced which improve the reliability
for transmissions even for systems with low rate speech codecs and channels with
some distortion.
The results of the thesis are suggestions of symbol patterns and ways to create
and adapt symbols for specific application and channel conditions to achieve the
desired goal for the application