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Publication
Joint Beamforming, Terminal Scheduling, and Adaptive Modulation with Imperfect CSIT in Rayleigh Fading Correlated Channels with Co-channel Interference
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Advisor(s)
Abstract(s)
—This paper presents a resource allocation algorithm
for multi-user wireless networks affected by co-channel interference.
The analysis considers a network with one base station
(BS) that uses a multiple antenna transmitter (beamformer) to
schedule (in a time-division manner) transmissions towards a
set of J one-antenna terminals in the presence of K persistent
interferers. The transmitter is assumed to employ MaximumRatio
Combining (MRC) beamforming with spatially-correlated
branches and channel envelopes modelled as Rayleigh-distributed
processes. The BS has access to an imperfect (outdated) copy
of the instantaneous Channel State Information (CSI) of each
terminal. Based on this CSI at the transmitter side (CSIT), the BS
proceeds to select (at each time interval or time-slot) the terminal
with the highest channel strength for purposes of transmission.
This imperfect CSIT is also used to calculate the coefficients of the
beamformer that will be used to transmit information towards the
scheduled terminal, as well as for selecting the most appropriate
modulation format (threshold-based decision). In addition, the
transmission towards each scheduled terminal is assumed to
experience persistent co-channel interference that will degrade
the quality of the information reception process. The main merits
of this work are the following: 1) joint analysis of MRC-based
beamforming, terminal scheduling based on maximum channel
strength, and modulation assignment, and 2) joint modelling
of the effects of spatial correlation, co-channel interference
and imperfect CSIT. Results suggest that scheduling helps in
rejecting co-channel interference and the degrading effects of
imperfect CSIT. Spatial correlation could some times lead to
better performance than the uncorrelated case, particularly in the
low SNR (Signal-to-Noise Ratio) regime. Conversely, uncorrelated
branches always outperform the correlated case in the high SNR
regime. The use of higher numbers of antennas also improve
performance of the system. However, spatial correlation tends
to accumulate over the antenna array thus leading to a more
noticeable performance degradation and more allocation errors
due to the outdated CSIT assumption.
Description
The Second International Conference on Advances in Signal, Image and Video Processing - from Sensing to Applications (SIGNAL 2017). 21 to 25, May, 2017, 5Gsignalwave. Barcelona, Spain.
Keywords
Beamforming Scheduling Resource allocation Imperfect CSIT Maximum Ratio Combining (MRC)