90 research outputs found
Distributed Detection over Fading MACs with Multiple Antennas at the Fusion Center
A distributed detection problem over fading Gaussian multiple-access channels
is considered. Sensors observe a phenomenon and transmit their observations to
a fusion center using the amplify and forward scheme. The fusion center has
multiple antennas with different channel models considered between the sensors
and the fusion center, and different cases of channel state information are
assumed at the sensors. The performance is evaluated in terms of the error
exponent for each of these cases, where the effect of multiple antennas at the
fusion center is studied. It is shown that for zero-mean channels between the
sensors and the fusion center when there is no channel information at the
sensors, arbitrarily large gains in the error exponent can be obtained with
sufficient increase in the number of antennas at the fusion center. In stark
contrast, when there is channel information at the sensors, the gain in error
exponent due to having multiple antennas at the fusion center is shown to be no
more than a factor of (8/pi) for Rayleigh fading channels between the sensors
and the fusion center, independent of the number of antennas at the fusion
center, or correlation among noise samples across sensors. Scaling laws for
such gains are also provided when both sensors and antennas are increased
simultaneously. Simple practical schemes and a numerical method using
semidefinite relaxation techniques are presented that utilize the limited
possible gains available. Simulations are used to establish the accuracy of the
results.Comment: 21 pages, 9 figures, submitted to the IEEE Transactions on Signal
Processin
Towards Live 3D Reconstruction from Wearable Video: An Evaluation of V-SLAM, NeRF, and Videogrammetry Techniques
Mixed reality (MR) is a key technology which promises to change the future of
warfare. An MR hybrid of physical outdoor environments and virtual military
training will enable engagements with long distance enemies, both real and
simulated. To enable this technology, a large-scale 3D model of a physical
environment must be maintained based on live sensor observations. 3D
reconstruction algorithms should utilize the low cost and pervasiveness of
video camera sensors, from both overhead and soldier-level perspectives.
Mapping speed and 3D quality can be balanced to enable live MR training in
dynamic environments. Given these requirements, we survey several 3D
reconstruction algorithms for large-scale mapping for military applications
given only live video. We measure 3D reconstruction performance from common
structure from motion, visual-SLAM, and photogrammetry techniques. This
includes the open source algorithms COLMAP, ORB-SLAM3, and NeRF using
Instant-NGP. We utilize the autonomous driving academic benchmark KITTI, which
includes both dashboard camera video and lidar produced 3D ground truth. With
the KITTI data, our primary contribution is a quantitative evaluation of 3D
reconstruction computational speed when considering live video.Comment: Accepted to 2022 Interservice/Industry Training, Simulation, and
Education Conference (I/ITSEC), 13 page
- …