Measurements of the propagation channels in realworld
environments form the basis of all realistic system performance
evaluations, as foundation of statistical channel models
or to verify ray tracing. This is also true for the analysis of
cell-free massive multi-input multi-output (CF-mMIMO) systems.
However, such experimental data are difficult to obtain, due to the
complexity and expense of deploying tens or hundreds of channel
sounder nodes across the wide area a CF-mMIMO system is
expected to cover, especially when different configurations and
number of antennas are to be explored. In this paper, we
provide a novel method to obtain channel data for CF-mMIMO
systems using a channel sounder based on a drone, also known
as a small unmanned aerial vehicle (UAV). Such a method is
efficient, flexible, simple, and low-cost, capturing channel data
from thousands of different access point (AP) locations within
minutes. In addition, we provide sample 3.5 GHz measurement
results analyzing deployment strategies for APs and make the
data open source, so they may be used for various other studies.
To our knowledge, our data are the first large-scale, real-world
CF-mMIMO channel data.
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Uplink Energy Efficiency of Cell-Free Massive MIMO With Transmit Power Control in Measured Propagation Channels
Abstract—Cell-free massive MIMO (CF-mMIMO) is expected
to provide reliable wireless services for a large number of
user equipments (UEs) using access points (APs) distributed
across a wide area. When the UEs are battery-powered, uplink
energy efficiency (EE) becomes an important performance metric
for CF-mMIMO systems. Therefore, if the “target” spectral
efficiency (SE) is met, it is important to optimize the uplink EE
when setting the transmit powers of the UEs. Also, such transmit
power control (TPC) method must be tested on channel data from
real-world measurements to prove its effectiveness. In this paper,
we compare three different TPC algorithms using zero-forcing
reception by applying them to 3.5 GHz channel measurement
data featuring 30,000 possible AP locations and 8 UE locations
in a 200m×200m area. We show that the max-min EE algorithm
is highly effective in improving the uplink EE at a target SE,
especially if the number of single-antenna APs is large, circuit
power consumption is low, and the maximum allowed transmit
power of the UEs is high.
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- NSF-PAR ID:
- 10342473
- Date Published:
- Journal Name:
- 021 IEEE Workshop on Signal Processing Systems (SiPS)
- Page Range / eLocation ID:
- 164 to 169
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/SiPS52927.2021.00037
