Thursday, April 15
4:30 - 6:00 PM
Room 1001 EECS
Abstract-
Performance in TDMA digital cellular systems is often limited by
interference, specifically by one or two dominant
interfering users.
In order to improve system performance (capacity) or call
quality,
this interference must either be avoided or mitigated for
both uplink
and downlink reception. In this talk, we give a description
of the
techniques used to handle interference for the IS-136
system. For
uplink reception, traditional diversity reception is
combined with
equalization to perform interference cancellation through
space-time
processing. This technique is further combined with fixed
beamforming
to provide significant gains in fast fading and dispersive
environments. For the downlink, fixed beamforming is used
to
statistically improve carrier to interference levels at the
handset by
only transmitting energy towards the desired mobile user.
Further
improvements can be obtained by cancelling interference at
the
handset. Under the restriction that there is only one
antenna
available for reception, joint detection is considered for
cancelling
the remaining, dominant interferers.