AbstractÐFuture sub-THz cellular deployments may be utilized
to complement the coverage of the global positioning
system (GPS) and provide centimeter-level accuracy. In this work,
we use measurement data at 142 GHz to test a map-based
position location algorithm in an outdoor urban microcell (UMi)
environment. We utilize an extended Kalman filter (EKF) to track
the position of the user equipment (UE) along a rectangular track,
with the transmitter-receiver separation distances varying from
24.3 m to 52.8 m. The position and velocity of the UE are tracked
by the EKF, with measurements of the angle of arrival and time
of flight information obtained along an outdoor track, to provide
a mean accuracy of 24.8 cm at 142 GHz, over 34 UE locations,
using a single base station in line-of-sight and non-line-of-sight.
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Millimeter Wave Position Location using Multipath Differentiation for 3GPP using Field Measurements
3GPP air interface standards support meter-level
position location of a user in a cellular network. With wider
bandwidths and narrow antenna beamwidths available at
mmWave frequencies, cellular networks now have the potential
to provide sub-meter position location for each user. In this
work, we provide an overview of 3GPP position location
techniques that are designed for line-of-sight propagation. We
discuss additional measurements required in the 3GPP standard
that enable multipath-based non-line-of-sight position location.
Further, we validate the concepts in this paper by using field
data to test a map-based position location algorithm in an indoor
office environment which has dimensions of 35 m by 65.5 m. We
demonstrate how the fusion of angle of arrival and time of flight
information in concert with a 3-D map of the office provides a
mean accuracy of 5.72 cm at 28 GHz and 6.29 cm at 140 GHz,
over 23 receiver distances ranging from 4.2 m to 32.3 m, using a
single base station in line-of-sight and non-line-of-sight. We also
conduct a theoretical analysis of the typical error experienced
in the map-based position location algorithm and show that the
complexity of the map-based algorithm is low enough to allow
real-time implementation.
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- NSF-PAR ID:
- 10205765
- Date Published:
- Journal Name:
- 2020 IEEE Global Communciations conference
- Volume:
- 2020
- Page Range / eLocation ID:
- 1-7
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Accurate precise positioning at millimeter wave frequencies is possible due to the large available bandwidth that permits precise on-the-fly time of flight measurements using conventional air interface standards. In addition, narrow antenna beamwidths may be used to determine the angles of arrival and departure of the multipath components between the base station and mobile users. By combining accurate temporal and angular information of multipath components with a 3- D map of the environment (that may be built by each user or downloaded a-priori), robust localization is possible, even in non-line-of-sight environments. In this work, we develop an accurate 3-D ray tracer for an indoor office environment and demonstrate how the fusion of angle of departure and time of flight information in concert with a 3-D map of a typical large office environment provides a mean accuracy of 12.6 cm in line-of-sight and 16.3 cm in non-line-of-sight, over 100 receiver distances ranging from 1.5 m to 24.5 m using a single base station. We show how increasing the number of base stations improves the average non-line-of-sight position location accuracy to 5.5 cm at 21 locations with a maximum propagation distance of 24.5 m. Index Terms—localization; positioning; position location; navigation; mmWave; 5G; ray tracing; site-specific propagation; map-basedmore » « less
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Abstract—This letter provides a comparison of indoor radio propagation measurements and corresponding channel statistics at 28, 73, and 140 GHz, based on extensive measurements from 2014-2020 in an indoor office environment. Side-by-side comparisons of propagation characteristics (e.g., large-scale path loss and multipath time dispersion) across a wide range of frequencies from the low millimeter wave band of 28 GHz to the sub-THz band of 140 GHz illustrate the key similarities and differences in indoor wireless channels. The measurements and models show remarkably similar path loss exponents over frequencies in both line-of-sight (LOS) and non-LOS (NLOS) scenarios, when using a one meter free space reference distance, while the multipath time dispersion becomes smaller at higher frequencies. The 3GPP indoor channel model overestimates the large-scale path loss and has unrealistic large numbers of clusters and multipath components per cluster compared to the measured channel statistics in this letter. Index Terms—mmWave, THz, channel models, multipath time dispersion, 5G, 6G, large-scale path loss, 3GPP InH.more » « less
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Abstract: The vast amount of spectrum available for millimeter wave (mmWave) wireless communication systems will support accurate real-time positioning concurrent with communication signaling. This paper demonstrates that accurate estimates of the position of an unknown node can be determined using estimates of time of arrival (ToA), angle of arrival (AoA), as well as data fusion or machine learning. Real-world data at 28 GHz and 73 GHz is used to show that AoA-based localization techniques will need to be augmented with other positioning techniques. The fusion of AoA-based positioning with received power measurements for RXs in an office which has dimensions of 35 m by 65.5 m is shown to provide location accuracies ranging from 16 cm to 3.25 m, indicating promise for accurate positioning capabilities in future networks. Received signal strength intensity (RSSI) based positioning techniques that exploit the ordering of the received power can be used to determine rough estimates of user position. Prediction of received signal characteristics is done using 2-D ray tracing.more » « less
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Context. The 1°.3 (G1.3) and 1°.6 (G1.6) cloud complexes in the central molecular zone (CMZ) of our Galaxy have been proposed to possibly reside at the intersection region of the X1 and X2 orbits for several reasons. This includes the detection of co-spatial low- and high-velocity clouds, high velocity dispersion, high fractional molecular abundances of shock-tracing molecules, and kinetic temperatures that are higher than for usual CMZ clouds. Aims. By investigating the morphology and deriving physical properties as well as chemical composition, we want to find the origin of the turbulent gas and, in particular, whether evidence of an interaction between clouds can be identified. Methods. We mapped both cloud complexes in molecular lines in the frequency range from 85 to 117 GHz with the IRAM 30 m telescope. The APEX 12m telescope was used to observe higher frequency transitions between 210 and 475 GHz from selected molecules that are emitted from higher energy levels. We performed non-local thermodynamic equilibrium (non-LTE) modelling of the emission of an ensemble of CH 3 CN lines to derive kinetic temperatures and H 2 volume densities. These were used as starting points for non-LTE modelling of other molecules, for which column densities and abundances were determined and compared with values found for other sources in the CMZ. Results. The kinematic structure of G1.3 reveals an ‘emission bridge’ at intermediate velocities (~150 km s −1 ) connecting low-velocity (~100 km s −1 ) and high-velocity (~180 km s −1 ) gas and an overall fluffy shell-like structure. These may represent observational evidence of cloud-cloud interactions. Low- and high-velocity gas components in G1.6 do not show this type of evidence of an interaction, suggesting that they are spatially separated. We selected three positions in each cloud complex for further analysis. Each position reveals several gas components at various peak velocities and of various line widths. We derived kinetic temperatures of 60–100 K and H 2 volume densities of 10 4 –10 5 cm −3 in both complexes. Molecular abundances relative to H 2 suggest a similar chemistry of the two clouds, which is moreover similar to that of other GC clouds and, especially, agrees well with that of G+0.693 and G−0.11. Conclusions. We conclude that G1.3 may indeed exhibit signs of cloud-cloud interactions. In particular, we propose an interaction of gas that is accreted from the near-side dust lane to the CMZ, with gas pre-existing at this location. Low- and high-velocity components in G1.6 are rather coincidentally observed along the same line of sight. They may be associated with either overshot decelerated gas from the far-side dust line or actual CMZ gas and high-velocity gas moving on a dust lane. These scenarios would be in agreement with numerical simulations.more » « less
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