Abstract
In mobile communication systems with multisensor
antennas at base stations, downlink channel estimation plays a
key role because accurate channel estimates are needed for
transmit beamforming. One efficient approach to this problem is
channel probing with feedback. In
this method, the base station array transmits probing (training)
signals. The channel is then estimated from feedback reports
provided by the users.
This paper studies the performance of the channel probing method
with feedback using a multisensor base station antenna array and
single-sensor users. The least squares (LS), linear minimum mean
square error (LMMSE), and a new scaled LS (SLS) approaches to the
channel estimation are studied. Optimal choice of probing signals
is investigated for each of these techniques and their channel
estimation performances are analyzed. In the case of multiple LS
channel estimates, the best linear unbiased estimation (BLUE)
scheme for their linear combining is developed and studied.