U.S. patent application number 17/353728 was filed with the patent office on 2021-10-07 for phased array mobile channel sounding system.
The applicant listed for this patent is AT&T Intellectual Property I, L.P.. Invention is credited to Aditya Chopra, Saeed Ghassemzadeh, Arunabha Ghosh, Andrew Thornburg.
Application Number | 20210313688 17/353728 |
Document ID | / |
Family ID | 1000005666400 |
Filed Date | 2021-10-07 |
United States Patent
Application |
20210313688 |
Kind Code |
A1 |
Ghassemzadeh; Saeed ; et
al. |
October 7, 2021 |
PHASED ARRAY MOBILE CHANNEL SOUNDING SYSTEM
Abstract
A wireless channel sounding system may include a wireless
channel sounding transmitter having at least two radio frequency
front ends coupled to at least two phased array antennas to
generate at least two radio frequency channel sounding waveforms
from at least two baseband signals, the at least two phased array
antennas each controllable to provide a respective transmit beam
that is steerable in azimuth and elevation, and that comprises one
of the at least two radio frequency channel sounding waveforms,
where faces of the at least two phased array antennas are arranged
to provide a transmit beam coverage over 360 degrees in azimuth,
and a first processing system including at least one processor, in
communication with the at least two radio frequency front ends, to
provide the at least two baseband signals and steer the respective
transmit beams via instructions to the at least two radio frequency
front ends.
Inventors: |
Ghassemzadeh; Saeed;
(Austin, TX) ; Chopra; Aditya; (Austin, TX)
; Ghosh; Arunabha; (Austin, TX) ; Thornburg;
Andrew; (Austin, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AT&T Intellectual Property I, L.P. |
Atlanta |
GA |
US |
|
|
Family ID: |
1000005666400 |
Appl. No.: |
17/353728 |
Filed: |
June 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16527218 |
Jul 31, 2019 |
11043742 |
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17353728 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 21/065 20130101;
H01Q 3/2617 20130101; H01Q 3/34 20130101; H04B 7/0634 20130101;
H04B 7/0617 20130101; H04L 5/0048 20130101 |
International
Class: |
H01Q 3/34 20060101
H01Q003/34; H04L 5/00 20060101 H04L005/00; H01Q 21/06 20060101
H01Q021/06; H04B 7/06 20060101 H04B007/06; H01Q 3/26 20060101
H01Q003/26 |
Claims
1. A wireless channel sounding system comprising: a wireless
channel sounding transmitter comprising: at least one radio
frequency front end coupled to at least two phased array antennas
to generate at least two radio frequency channel sounding waveforms
from at least two baseband signals; the at least two phased array
antennas, wherein each of the at least two phased array antennas is
controllable to provide a respective transmit beam that is
steerable in at least one of: azimuth or elevation, and that
comprises one of the at least two radio frequency channel sounding
waveforms, wherein faces of the at least two phased array antennas
are arranged to provide a transmit beam coverage over 240 degrees
in azimuth; and a first processing system including at least one
processor, in communication with the at least one radio frequency
front end to: provide the at least two baseband signals; and steer
the respective transmit beams via instructions to the at least one
radio frequency front end.
2. The wireless channel sounding system of claim 1, further
comprising: a wireless channel sounding receiver comprising: at
least one phased array antenna controllable to provide a respective
receive beam that is steerable in at least one of: azimuth or
elevation; at least one radio frequency front end coupled to the at
least one phased array antenna to: receive at least one radio
frequency channel sounding waveform of the at least two radio
frequency channel sounding waveforms from the wireless channel
sounding transmitter via the respective receive beam; and generate
at least one baseband signal from the at least one radio frequency
channel sounding waveform; and a second processing system including
at least one processor in communication with the at least one radio
frequency front end of the wireless channel sounding receiver to:
steer the respective receive beam via instructions to the at least
one radio frequency front end of the wireless channel sounding
receiver; receive the at least one baseband signal from the at
least one radio frequency front end of the wireless channel
sounding receiver; and record the at least one baseband signal.
3. The wireless channel sounding system of claim 2, wherein the
second processing system is further to: record location information
of the wireless channel sounding receiver, spatial orientation
information of the respective receive beam, and timing information
for the receiving of the at least one baseband signal.
4. The wireless channel sounding system of claim 3, wherein the
second processing system is further to: transmit the at least one
baseband signal, the location information of the wireless channel
sounding receiver, the spatial orientation information of the
respective receive beam, and the timing information to the first
processing system.
5. The wireless channel sounding system of claim 4, wherein the
first processing system is further to: determine a plurality of
measurements of at least one wireless channel parameter based upon
the at least one baseband signal, the location information of the
wireless channel sounding receiver, the spatial orientation
information of the respective receive beam, and the timing
information.
6. The wireless channel sounding system of claim 5, wherein the
first processing system is further to: record spatial orientation
information of the respective transmit beams, wherein the plurality
of measurements of the at least one wireless channel parameter is
further based upon the spatial orientation information of the
respective transmit beams.
7. The wireless channel sounding system of claim 6, wherein the
wireless channel sounding transmitter further comprises: a
gyroscope; and a compass, wherein the first processing system is
further to determine the spatial orientation information of the
respective transmit beams via the gyroscope and the compass.
8. The wireless channel sounding system of claim 2, wherein the
second processing system is further to: determine a plurality of
measurements of at least one wireless channel parameter based upon
the at least one baseband signal.
9. The wireless channel sounding system of claim 8, wherein the
second processing system is further to: record the plurality of
measurements of the at least one wireless channel parameter.
10. The wireless channel sounding system of claim 8, wherein the
second processing system is further to: transmit the plurality of
measurements of the at least one wireless channel parameter to the
first processing system.
11. The wireless channel sounding system of claim 1, wherein the at
least two radio frequency channel sounding waveforms that are
transmitted via the respective transmit beams are orthogonal
signals that are transmitted at a same time.
12. The wireless channel sounding system of claim 1, wherein the at
least two phased array antennas comprise a pair of half-cylindrical
antennas, wherein each of the half-cylindrical antennas provides
the transmit beam coverage over at least a 120 degree azimuthal
sector.
13. The wireless channel sounding system of claim 1, wherein the at
least two phased array antennas comprise at least three phased
array antennas, wherein each of the at least three phased array
antennas provides a transmit beam coverage over at least a 80
degree azimuthal sector.
14. The wireless channel sounding system of claim 1, wherein the at
least three phased array antennas comprise at least four phased
array antennas, wherein each of the at least four phased array
antennas provides the transmit beam coverage over at least a 60
degree azimuthal sector.
15. The wireless channel sounding system of claim 1, wherein each
of the at least one radio frequency front end includes a plurality
of variable phase shifters associated with respective antenna
elements of an associated one of the at least two phased array
antennas.
16. The wireless channel sounding system of claim 15, wherein the
instructions to the at least one radio frequency front end to steer
the respective transmit beams are for controlling the plurality of
variable phase shifters to control directions of the respective
transmit beams.
17. The wireless channel sounding system of claim 1, wherein each
of the respective transmit beams comprises a directional beam with
a half-power beamwidth of less than 30 degrees, wherein the
steering the transmit beams further comprises controlling the
half-power beamwidth of the each of the transmit beams via the
instructions.
18. The wireless channel sounding system of claim 1, wherein each
of the at least one radio frequency front end includes a
baseband-to-radio frequency upconverter.
19. A method comprising: providing, by a first processing system of
a wireless channel sounding transmitter of a channel sounding
system including at least one processor, at least two baseband
signals to at least one radio frequency front end of the wireless
channel sounding transmitter; and steering, by the first processing
system, respective transmit beams via instructions to the at least
one radio frequency front end, wherein the at least one radio
frequency front end is to generate at least two radio frequency
channel sounding waveforms from the at least two baseband signals,
wherein the at least one radio frequency front end is coupled to at
least two phased array antennas of the wireless channel sounding
transmitter, wherein each of the at least two phased array antennas
is controllable to provide a respective transmit beam that is
steerable in at least one of: azimuth or elevation, and that
comprises one of the at least two radio frequency channel sounding
waveforms, and wherein faces of the at least two phased array
antennas are arranged to provide a transmit beam coverage over 240
degrees in azimuth.
20. A non-transitory computer-readable medium storing instructions
which, when executed by at least a first processing system of a
wireless channel sounding transmitter of a channel sounding system
including at least one processor, cause the at least the first
processing system to perform operations, the operations comprising:
providing at least two baseband signals to at least one radio
frequency front end of the wireless channel sounding transmitter;
and steering respective transmit beams via instructions to the at
least one radio frequency front end, wherein the at least one radio
frequency front end is to generate at least two radio frequency
channel sounding waveforms from the at least two baseband signals,
wherein the at least one radio frequency front end is coupled to at
least two phased array antennas of the wireless channel sounding
transmitter, wherein each of the at least two phased array antennas
is controllable to provide a respective transmit beam that is
steerable in at least one of: azimuth or elevation, and that
comprises one of the at least two radio frequency channel sounding
waveforms, and wherein faces of the at least two phased array
antennas are arranged to provide a transmit beam coverage over 240
degrees in azimuth.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/527,218, filed on Jul. 31, 2019, now U.S.
Pat. No. 11,043,742, which is herein incorporated by reference in
its entirety.
[0002] The present disclosure relates generally to wireless
communication networks, and more particularly to wireless channel
sounding systems, non-transitory computer readable media, and
methods for measuring wireless channel parameters using a phased
array channel sounding transmitter.
BACKGROUND
[0003] Wireless channel sounding may comprise measuring wireless
channel related parameters such as complex impulse response, path
loss, received signal strength (RSS), excess delay, or
root-mean-square (RMS) delay spread, Doppler spread, fade rate,
angle of arrival (AoA) and/or angle of departure (AoD), and the
like, as experienced by a user equipment or base station. In one
implementation, channel sounding may utilize directional antennas.
For instance, to measure AoA using a directional antenna, the
antenna may be turned in incremental steps to measure the RSS. The
AoA is recorded where the RSS is at a maximum. While this solution
is inexpensive, it is a relatively slow measurement technique.
SUMMARY
[0004] In one example, the present disclosure discloses a wireless
channel sounding system, non-transitory computer readable medium,
and method for measuring wireless channel parameters using a phased
array channel sounding transmitter. For example, a wireless channel
sounding system may include a wireless channel sounding transmitter
having at least two radio frequency front ends coupled to at least
two phased array antennas to generate at least two radio frequency
channel sounding waveforms from at least two baseband signals. The
wireless channel sounding transmitter may further include the at
least two phased array antennas, each of the at least two phased
array antennas controllable to provide a respective transmit beam
that is steerable in azimuth and elevation, and that comprises one
of the at least two radio frequency channel sounding waveforms,
where faces of the at least two phased array antennas are arranged
to provide a transmit beam coverage over 360 degrees in azimuth.
The wireless channel sounding transmitter may also include a first
processing system including at least one processor, in
communication with the at least two radio frequency front ends, to
provide the at least two baseband signals and steer the respective
transmit beams via instructions to the at least two radio frequency
front ends.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The teachings of the present disclosure can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0006] FIG. 1 illustrates an example system, in accordance with the
present disclosure;
[0007] FIG. 2 illustrates an example translation of spatial
orientation information of a local coordinate system with respect
to a channel sounding transmitter into spatial orientation
information in a global coordinate system, in accordance with the
present disclosure;
[0008] FIG. 3 illustrates a portion of an example channel sounding
transmitter, in accordance with the present disclosure;
[0009] FIG. 4 illustrates a flowchart of an example method for
measuring wireless channel parameters using a phased array channel
sounding transmitter; and
[0010] FIG. 5 illustrates an example of a computing device, or
computing system, specifically programmed to perform the steps,
functions, blocks, and/or operations described herein.
[0011] To facilitate understanding, similar reference numerals have
been used, where possible, to designate elements that are common to
the figures.
DETAILED DESCRIPTION
[0012] The present disclosure broadly discloses methods,
computer-readable media, and devices for measuring wireless channel
parameters using a phased array channel sounding transmitter.
Developing 3GPP Fifth Generation (5G) standards include the use of
millimeter wave frequencies (30 GHz to 300 GHz) as carrier
frequencies. The propagation loss of air at such frequencies is
relatively high. One technique to overcome this loss is the use of
beamformed wireless communication. In beamformed communications,
wireless signals are transmitted in a narrow beam. The
concentration of energy in a narrow beam helps overcome the
propagation loss of the wireless medium. Similarly, 5G receivers
may also sense wireless signals in a narrow region of space,
allowing the capture of a large amount of signal energy and
correspondingly low amounts of noise and interference energy. This
is relevant to channel sounding, as 5G channel models should
provide metrics with respect to a spatial grid around the
transmitter or the receiver.
[0013] For deployment and configuration of wireless network
infrastructure, it is beneficial to obtain a wireless channel's
propagation within the frequency bands of interest to the standard.
The act of making such wireless channel propagation measurements is
known as channel sounding. Channel sounding typically operates by
transmitting a known wireless signal in the frequency band of
interest by a channel sounding transmitter, and subsequently
receiving this signal at a different location by a channel sounding
receiver. Knowing both the transmitted and the received signal, the
state of the channel at the time of transmission can be extracted,
resulting in what may be referred to as a "channel snapshot."
Multiple of such channel snapshots can be acquired by varying the
hardware location, orientation, speed, time of transmission, and
even the environment around the channel sounder transmitter and the
channel sounding receiver. The resulting dataset of channel
snapshots may be subsequently analyzed to extract channel models to
be used for standards development, as well as network
infrastructure deployment, configuration, and optimization.
[0014] Based on multiple antennas at both transmitters and
receivers, a M.times.N (M transmit antennas and N receive antennas)
multiple input multiple output (MIMO) channel sounding system is
able to measure directional channel propagation at both ends of the
wireless link (e.g., at the transmit and receive antennas) and
improve resolution of the spatial multiple path parameters. In one
example, a channel sounding system may transmit a known signal
(broadly a "channel sounding signal" or "channel sounding
waveform") via a first transmit beam direction of a channel
sounding transmitter, and measure the channel parameters via all N
receive antennas at the channel sounding receiver. The channel
sounding transmitter may then switch to a second transmit beam
direction and the process repeats until all M.times.N combinations
have been performed. By way of example and without any limitation,
a Zadoff-Chu (ZC) sequence in the time domain may be used for
channel sounding. In another example, in the case of frequency
domain processing, the channel sounding signal may be inserted
before an inverse Fast Fourier Transform (iFFT) stage in the
transmitter. In one example, the channel sounding signal may be in
accordance with a modulation coding scheme e.g., a binary phase
shift keying (BPSK) modulation coding scheme, a quadrature phase
shift keying (QPSK) modulation coding scheme, a frequency
modulation (FM) scheme, an amplitude modulation (AM) scheme, a
frequency shift keying (FSK) scheme, a modulation coding scheme
based upon a precoding matrix indicator, or a modulation coding
scheme based upon precoder cycling. Higher level encoding schemes
such as 16-QAM, 64-QAM, and the like may also be used in other
examples.
[0015] In one example, the present disclosure may comprise mobile
channel sounding transmitters (and receivers) that include multiple
phased array antennas, e.g., where radio frequency (RF) components,
such as power amplifiers, variable phase shifters, and transceivers
are integrated with the antennas elements of each phased array. In
particular, examples of the present disclosure may provide a
channel sounding system that may operate in one or more frequency
bands for 5G communications, and which may determine measurements
of wireless channel parameters (e.g., one or more "key performance
indicators" (KPIs)), such as a complex impulse response, a path
loss, a received signal strength (RSS), e.g., a reference signal
received power (RSRP), a carrier-to-interference (CIR) ratio (or
signal-to-noise ratio (SNR)), an excess delay, a root-mean-square
(RMS) delay spread, an angular spread, a Doppler spread, a fade
rate, an angle of arrival (AoA), and the like, along with spatial
orientation information, such as azimuth and elevation angles, and
locations associated with the measurements. Although examples of
the present disclosure are applicable to a wide range of frequency
bands, in one example, the present disclosure may relate to channel
sounding in centimeter and millimeter wave ranges. For instance,
for all of the examples herein, the considered wireless cellular
communications standard may be the Third Generation Project (3GPP)
New Radio (NR) and/or 5G radio access technology.
[0016] The channel sounding transmitter may comprise a device that
is equipped to operate according to the specification of the
considered wireless cellular communications standard (e.g., 5G
millimeter wave multiple-in multiple-out (MIMO)). In one example,
the channel sounding transmitter may include at least two phased
array antennas arranged to provide a transmit beam coverage across
360 degrees in azimuth, and may be configured with the ability to
simultaneously beam sweep multiple transmit beams for the
respective phased array antennas to transmit multiple channel
sounding waveforms from the mobile channel sounding transmitter
(which, in one example, may comprise orthogonal waveforms/signals
that are transmitted simultaneously via the respective transmit
beams). In other words, the at least two phased array antennas
provide transmit beams that are steerable so that for each
azimuthal direction, at least one transmit beam is steerable to
include the azimuthal direction within the half-power beam width
angular coverage of the at least one transmit beam.
[0017] Similarly, the channel sounding receiver may comprise a
device that is equipped to operate according to the specification
of the considered wireless cellular communications standard (e.g.,
5G millimeter wave multiple-in multiple-out (MIMO)). In one
example, the channel sounding receiver may include at least one
phased array antenna, e.g., up to three phased array antennas. To
illustrate, the channel sounding receiver may include at least
three phased array antennas arranged to provide a receive beam
coverage across 360 degrees in azimuth, and may be configured with
the ability to simultaneously beam sweep multiple receive beams for
the respective phased array antennas to receive channel sounding
waveforms from the mobile channel sounding transmitter. In other
words, the at least three phased array antennas provide receive
beams that are steerable so that for each azimuthal direction, at
least one receive beam is steerable to include the azimuthal
direction within the half-power beam width angular coverage of the
at least one receive beam.
[0018] Antenna array geometry defines the placement of the antenna
elements on the phased array antenna. For example, a uniform
rectangular array (URA) geometry has antenna elements placed in a
rectangular pattern with equal spacing between neighboring
elements. Planar geometries such as the URA typically have a
spatial region within which they can transmit or receive via a
narrow beam (e.g., a half power beam width (HPBW) of less than 30
degrees angular spread, less than 15 degrees angular spread, less
than 10 degrees angular spread, and so forth). In order to cover
the entire 360 degree field of view in the azimuth plane around a
channel sounding transmitter or a channel sounding receiver,
multiple planar phased array antennas may be arranged side-by-side.
For instance, for either or both of a channel sounding transmitter
and a channel sounding receiver, three planar phased array antennas
may be arranged in a generally triangular layout. In another
example, four planar phased array antennas may be arranged in a
generally square or rectangular layout with each phased array
antenna covering at least 90 degrees in azimuth. In such case, if
the azimuth spatial coverage of each phased array antenna is
greater than or equal to 90 degrees, the four phased array antennas
can combine to cover all 360 degrees. Similarly, a configuration of
three phased array antennas may cover the entire azimuth field of
view as long as each phased array antenna has greater than or equal
to 120 degrees of coverage. In another example, for either or both
of the channel sounding transmitter and the channel sounding
receiver, the present disclosure may utilize a cylindrical phased
array antenna, with antenna elements placed either uniformly or
non-uniformly on the face of the array. A complete cylinder with
antenna elements on the surface can provide 360 degrees of
azimuthal coverage. In another example, two half-cylinder phased
array antennas can also provide similar coverage.
[0019] It should be noted that in various examples, the phased
array antennas may have different fields-of-view in an elevation
plane. For example, the phased array antennas may have a field of
view in elevation of 120 degrees, 90 degrees, 60 degrees, etc. The
elevation field of view may be symmetric around the horizon (or a
horizontal plane with respect to a device chassis) or may be
offset, e.g., to provide greater coverage above or below a
horizontal plane. For instance, the top edges of the phased array
antennas may be angled towards each other, while the bottom edges
of the phased array antennas may be angled away from each other. In
another example, multiple phased array antennas may be arranged to
provide 180 degrees of elevation coverage.
[0020] Appropriate control circuitry may also be paired with the
phased array antennas. For example, in the channel sounding
transmitter, if there are N phased array antennas, there may be N
independent transmit beams that can be utilized simultaneously. In
one example, the channel sounding transmitter may include N radio
frequency (RF) front ends (including, for example: variable phase
shifters, power amplifiers, diplexers or switches, upconverters,
and the like) and N digital baseband units (which may include
transceivers) to upconvert the channel sounding waveforms that are
to be transmitted via the respective N phased array antennas
(where, in one example, the transmissions may be simultaneous). The
baseband units may include digital-to-analog converters (DACs) to
convert digital representations of channel sounding waveforms
(which may be provided by a processing system of the channel
sounding transmitter) to analog baseband representations of the
channel sounding waveforms, which may then be upconverted via the
RF front ends. A channel sounding transmitter with the ability to
transmit N beams at the same time can sweep through the 360 degree
field of view quickly by dividing the total azimuth field of view
into N smaller coverage zones for each of the transmit beams of the
N phased array antennas.
[0021] In one example, the N signals transmitted by the N phased
array antennas can be from a single baseband unit via a switch (or
bank of switches). The switch(es) may be used to direct channel
sounding waveforms to one beam at any given time. In such an
example, the transmitter device may sweep the beams through their
respective fields of view in a sequential manner, resulting in a
slower sweep of the 360 degree field of view. By placing additional
switches and baseband transmitter units, the number of baseband
units can be set anywhere between 1 to N, in order to achieve a
desired balance of cost, device size, performance speed, etc. In
another example, each phased array antenna may be provided with its
own dedicated RF front end.
[0022] Similarly, in the channel sounding receiver, if there are N
phased array antennas, there may be N independent receive beams
that can be utilized simultaneously. In one example, the channel
sounding receiver may include N radio frequency (RF) front ends
(including, for example: variable phase shifters, power amplifiers,
diplexers or switches, downconverters, and the like) and N digital
baseband units (which may include transceivers) to sense the
signals received via the respective N phased array antennas
simultaneously. A receiver device with the ability to capture N
beams at the same time can sweep through the 360 degree field of
view quickly by dividing the total azimuth field of view into N
smaller coverage zones for each of the receive beams of the N
phased array antennas.
[0023] In one example, the N signals coming out of the N phased
array antennas can be fed into a single baseband receiver via a
switch (or bank of switches). The switch(es) may be used to select
one beam at any given time. In such an example, the receiver device
may sweep the beams through their respective fields of view in a
sequential manner, resulting in a slower sweep of the 360 degree
field of view. By placing additional switches and baseband
receivers, the number of baseband receivers can be set anywhere
between 1 to N, in order to achieve a desired balance of cost,
device size, performance speed, etc. In another example, each
phased array antenna may be provided with its own dedicated RF
front end.
[0024] In one example, wireless channel parameter measurements may
be determined in one or more digital baseband units of the channel
sounding receiver. For instance, the digital baseband units may
receive analog baseband signals from respective RF front ends and
sample the analog baseband signals (e.g., an analog-to-digital
conversion) to provide digital baseband signals. Each of the
digital baseband units (or "baseband receivers") may be implemented
as a programmable logic device (PLD), such as a field programmable
gate array (FPGA) or the like, processing units, such as a central
processing unit (CPU) a multi-core processor, or the like in
conjunction with a memory, and/or a combination of CPU-based
processing unit(s) and PLD(s).
[0025] In one example, the digital baseband units may perform
various calculations to determine various measures of wireless
channel parameters, such as a complex impulse response, a path
loss, an RSS, a CIR, an excess delay, an RMS delay spread, an
angular spread, a Doppler spread, a fade rate, an AoA, and so
forth. Alternatively, or in addition, the digital baseband units
may forward the digital baseband signals to a processor (or
processors), such as a central processing unit (CPU) of the channel
sounding receiver, to further determine various measurements of
wireless channel parameters.
[0026] In one example, the channel sounding receiver does not
calculate various measures of wireless channel parameters, or KPIs,
in real-time, but rather may store digital baseband signals as the
channel sounding receiver performs fast switching to sweep one or
more receive beams through various angles of arrival (AoA) and
obtain multiple digital baseband signals for the various receive
beam direction(s), e.g., within a coherence time of the wireless
channel. The channel sounding receiver may then, at a later time,
calculate the various measures of wireless channel parameters from
the stored digital baseband signals that are derived from the
received channel sounding waveforms (e.g., via the digital baseband
units and/or via a processing system including one or more other
processors). Notably, the time to perform calculations to determine
various measures of wireless channel parameters may be significant.
For instance, for a given channel sounding location, the channel
sounding receiver may fail to receive a full set of channel
sounding waveforms in accordance with various settings of interest
(e.g., a range of angles, a range of frequencies, a range of
waveforms/signal types, etc.) within the coherence time if the
channel sounding receiver was to also calculate the measure of
wireless channel parameters as the channel sounding
waveforms/signals are being received. Thus, by collecting the
digital baseband signals and postponing the actual calculations of
the measures of wireless channel parameters, the channel sounding
system may better ensure that the requisite signals are received
within the coherence time. In addition, this provides for more
accurate measure(s) of the wireless channel parameter(s) as the
received signals may be made closer in time than would otherwise be
achieved.
[0027] In another example, the channel sounding receiver may store
digital baseband signals and may then provide the digital baseband
signals to the channel sounding transmitter at a later time (e.g.,
after receiving various channel sounding waveforms at one or more
locations). In such an example, the channel sounding transmitter
may perform similar calculations of the measures of wireless
channel parameters. In still another example, the channel sounding
receiver may provide the digital baseband signals to another device
and/or processing system (e.g., a network-based server) which may
then calculate measures of wireless channel parameters.
[0028] In accordance with the present disclosure, a channel
sounding receiver may tag a wireless channel parameter measurement
with directional/spatial orientation information, i.e., in addition
to a location. In one example, the channel sounding receiver may
calculate a direction, or spatial orientation of a receive beam
with respect to a local coordinate system, e.g., a three
dimensional space with dimensions/axis aligned to a length, a
width, and a depth of the receiver device, for example. In one
example, a channel sounding receiver may include at least three
phased array antennas that may be arranged to provide at least
three receive beams and to steer each of the at least three receive
beams through receive beam directions/spatial orientations within a
given azimuth and elevation range. In addition, in one example, the
channel sounding receiver may be configured to associate each
receive beam (or receive beam direction/orientation) with a
vector/direction/spatial orientation in a local coordinate system
that is fixed, e.g., with respect to the positions of the at least
three phased array antennas. For instance, the channel sounding
receiver may be configured with a mapping of receive beams to
spatial orientations/directions in the local coordinate system.
[0029] It should be noted that other local coordinate systems may
have a different alignment with respect to the channel sounding
receiver (e.g., offset 30 degrees from the major dimensions/axis of
the channel sounding receiver). In any case, a local orientation of
a receive beam in a local coordinate system may be translated into
a global orientation, e.g., in the global coordinate system. In one
example, the translations may be based upon the difference between
the local orientation and the global orientation, which can be
estimated using a gyroscope and compass of the channel sounding
receiver. The determination of a direction/orientation of a receive
beam and the translation to a spatial orientation in a global
coordinate system are described in greater detail below in
connection with the example of FIG. 2.
[0030] In another example, the channel sounding receiver may
associate the angle of arrival (AoA) with a wireless channel
parameter measurement (and a location), (e.g., where the wireless
channel parameter measurement relates to a received power). In one
example, the channel sounding receiver does not tag a wireless
channel parameter measurement (e.g., received signal strength) with
spatial orientation information, but rather tags spatial
orientation information of a measurement with the location. For
instance, at a given location, the primary direction from which the
signal energy arrives is recorded, but not the actual received
signal strength. In one example, the channel sounding receiver may
tag a digital baseband signal with a time stamp, location
information, and/or directional/spatial orientation information
(e.g., in an example where the channel sounding receiver does not
calculate one or more measures of wireless channel parameters, and
where the calculation(s) is/are instead performed at the channel
sounding transmitter or elsewhere).
[0031] In one example, locations, or geographic positions may be
determined at the channel sounding receiver via a Global
Positioning System (GPS) unit, or may be derived using other
location estimation methods, such as cell identifier (cell ID)
based methods, observed time difference of arrival (OTDA)
techniques, or barycentric triangulation. In this regard, it should
be noted that any references herein to a channel sounding receiver
may comprise a mobile channel sounding receiver, i.e., a device
that is portable and which can be moved from location to location.
For instance, a mobile channel sounding receiver may be moved with
relative ease, such as one that may be carried by a person or
wheeled on a small cart that may be pushed or pulled by a person.
In addition, the orientation of the channel sounding receiver may
be determined from a gyroscope and compass, allowing the channel
sounding receiver device to determine a receive beam
direction/spatial orientation, and to therefore measure wireless
channel parameters with high spatial accuracy.
[0032] In addition, the mobile channel sounding transmitter may
determine its own location in the same or a similar manner as the
channel sounding receiver (and may be similarly equipped with a GPS
and/or other requisite hardware) and may calculate a direction (and
in one example, a distance) between the mobile channel sounding
transmitter and the channel sounding receiver. The mobile channel
sounding transmitter may then transmit channel sounding waveforms
via one or more transmit beams using one or more phased arrays,
e.g., accounting for the direction of the channel sounding
receiver. For example, each transmit beam may comprise a relatively
focused beam, e.g., with a HPBW of 15 degrees or less, or with a
broader beam e.g., up to 60 to 90 degrees of HPBW centred on the
direction of the channel sounding receiver, up to 120 degrees,
etc.
[0033] It should also be noted that the mobile channel sounding
transmitter may comprise a device that is portable and which can be
moved from location to location. For instance, a mobile channel
sounding transmitter may be moved with relative ease, such as one
that may be carried by a person or wheeled on a small cart that may
be pushed or pulled by a person. In addition, the use of a mobile
channel sounding transmitter may enable faster channel sounding as
compared to channel sounding via a base station (e.g., an NR base
station) that is used as a channel sounding transmitter. For
instance, an NR base station may serve various subscribers'
endpoint devices/user equipment and may therefore not be able to
dedicate sufficient resources to channel sounding (e.g., the base
station may not be able to transmit channel sounding waveforms such
that the channel sounding receiver can receive these waveforms
within the coherence time of the wireless channel).
[0034] In one example, the channel sounding receiver may store one
or more wireless channel parameter measurements (and/or digital
baseband signals) in a record, along with the spatial orientation
information and a location associated with the wireless channel
parameter measurements (and/or digital baseband signals), e.g., in
a local memory. In one example, the channel sounding receiver may
be deployed to obtain wireless channel parameter measurements
(and/or digital baseband signals) at various locations within an
environment and may collect and store all of the measurements
(and/or digital baseband signals). The measurements (and/or digital
baseband signals) may then be retrieved at a later time and
transferred to another device or system for storage and/or
analysis. For instance, associated data from the mobile channel
sounding transmitter regarding the transmit beam(s), the channel
sounding waveforms, the location(s) of the mobile channel sounding
transmitter, etc. may be stored and/or uploaded to the same device
or system and correlated with the measurements (and/or digital
baseband signals) of the channel sounding receiver.
[0035] In another example, the measurements (and/or digital
baseband signals) from the channel sounding receiver may be
transferred to the mobile channel sounding transmitter for storage
and/or analysis. This can be done after obtaining a series of
measurements (and/or digital baseband signals), e.g., via a cable
connection when the mobile channel sounding transmitter and
receiver are together in a same location, or may be transmitted
wirelessly by the channel sounding receiver to the mobile channel
sounding transmitter via a wireless side link.
[0036] In one example, the channel sounding transmitter may store
various information in connection with channel sounding waveforms
that are transmitted, such as a timestamp, spatial orientation
information (e.g., a transmit beam direction, or angle of departure
(AoD)), and a location. This information may then be correlated
with corresponding information of the channel sounding receiver.
For instance, a received signal strength (RSS) for a particular
angle of arrival at a location may be correlated with a location,
angle of departure, and transmit strength of the channel sounding
transmitter to provide a more comprehensive wireless channel
snapshot. The channel sounding transmitter may determine its
location as described above. In addition, the channel sounding
transmitter may translate a transmit beam direction/AoD in a local
coordinate system into a transmit beam direction/AoD in a global
coordinate system in the same or a similar manner as described
above in connection with the channel sounding receiver. For
example, translations may be based upon the difference between the
local orientation and the global orientation, which can be
estimated using a gyroscope and compass of the channel sounding
transmitter. These and other aspects of the present disclosure are
discussed in greater detail below in connection with the examples
of FIGS. 1-5.
[0037] To better understand the present disclosure, FIG. 1
illustrates an example network, or system 100 in which examples of
the present disclosure for measuring wireless channel parameters
using a phased array channel sounding transmitter. In one example,
the system 100 includes a telecommunication service provider
network 170. The telecommunication service provider network 170 may
comprise a cellular network 101 (e.g., a 4G/Long Term Evolution
(LTE) network, a 4G/5G hybrid network, or the like), a service
network 140, and a core network, e.g., an IP Multimedia Subsystem
(IMS) core network 115. The system 100 may further include other
networks 180 connected to the telecommunication service provider
network 170. FIG. 1 also illustrates various mobile endpoint
devices, e.g., user equipment (UE) 116 and 117. The UE 116 and 117
may each comprise a cellular telephone, a smartphone, a tablet
computing device, a laptop computer, a pair of computing glasses, a
wireless enabled wristwatch, or any other cellular-capable mobile
telephony and computing devices (broadly, "a mobile endpoint
device").
[0038] In one example, the cellular network 101 comprises an access
network 103 and a core network, Evolved Packet Core (EPC) network
105. In one example, the access network 103 comprises a cloud RAN.
For instance, a cloud RAN is part of the 3.sup.rd Generation
Partnership Project (3GPP) 5G specifications for mobile networks.
As part of the migration of cellular networks towards 5G, a cloud
RAN may be coupled to an EPC network until new cellular core
networks are deployed in accordance with 5G specifications. In one
example, access network 103 may include cell sites 111 and 112 and
a baseband unit (BBU) pool 114. In a cloud RAN, radio frequency
(RF) components, referred to as remote radio heads (RRHs), may be
deployed remotely from baseband units, e.g., atop cell site masts,
buildings, and so forth. In one example, the BBU pool 114 may be
located at distances as far as 20-80 kilometers or more away from
the antennas/remote radio heads of cell sites 111 and 112 that are
serviced by the BBU pool 114. It should also be noted in accordance
with efforts to migrate to 5G networks, cell sites may be deployed
with new antenna and radio infrastructures such as multiple input
multiple output (MIMO) antennas, and millimeter wave antennas. In
this regard, a cell, e.g., the footprint or coverage area of a cell
site, may in some instances be smaller than the coverage provided
by NodeBs or eNodeBs of 3G-4G RAN infrastructure. For example, the
coverage of a cell site utilizing one or more millimeter wave
antennas may be 1000 feet or less.
[0039] Although cloud RAN infrastructure may include distributed
RRHs and centralized baseband units, a heterogeneous network may
include cell sites where RRH and BBU components remain co-located
at the cell site. For instance, cell site 113 may include RRH and
BBU components. Thus, cell site 113 may comprise a self-contained
"base station." With regard to cell sites 111 and 112, the "base
stations" may comprise RRHs at cell sites 111 and 112 coupled with
respective baseband units of BBU pool 114. In accordance with the
present disclosure, any one or more of cell sites 111-113 may be
deployed with antenna and radio infrastructures, including multiple
input multiple output (MIMO) and millimeter wave antennas. In one
example, any one or more of cell sites 111-113 may comprise one or
more directional antennas (e.g., capable of providing a half-power
azimuthal beamwidth of 60 degrees or less, 30 degrees or less, 15
degrees or less, etc.). In one example, any one or more of cell
sites 111-113 may comprise a 5G "new radio" (NR) base station.
[0040] In one example, the channel sounding receiver 120 and the
channel sounding transmitter 125 (e.g., a mobile channel sounding
transmitter) may be used to determine a plurality of measurements
of at least one wireless channel parameter (broadly, "channel
sounding"). In one example, channel sounding receiver 120 may
comprise a user equipment, e.g., a mobile endpoint device
comprising a cellular telephone, a smartphone, a tablet computing
device, a laptop computer, or any other cellular-capable mobile
telephony and computing. In one example, channel sounding receiver
120 may comprise a dedicated channel sounding device. Similarly,
the channel sounding transmitter 125 may comprise a dedicated
channel sounding device.
[0041] In one example, the channel sounding transmitter 125 may
comprise two or more phased array antennas (e.g., a quantity of M
phased arrays), M RF front ends, and 1-M digital baseband units. In
one example, the channel sounding transmitter 125 may transmit
channel sounding signals (also referred to as "channel sounding
waveforms") via multiple transmit beams for reception by the
channel sounding receiver 120. In general, the channel sounding
waveforms may have a variety of characteristics, such as those
described above, that may be specified by the channel sounding
transmitter 125 (and/or by an operator thereof). In one example,
the channel sounding transmitter 125 may record location
information, spatial orientation information (and timing
information) of the respective transmit beams.
[0042] In one example, the channel sounding receiver 120 may be
used to receive channel sounding waveforms that are transmitted in
an environment from the channel sounding transmitter 125, where the
channel sounding waveforms, as received, may be used to calculate
or determine the measures of various wireless channel parameters
such as: a complex impulse response, a path loss, an RSS, a CIR, an
excess delay, an RMS delay spread, an angular spread, a Doppler
spread, a fade rate, an AoA, and so forth. For illustrative
purposes, the "wireless channel(s)" for which the channel sounding
receiver 120 is obtaining channel sounding waveforms may be
indicated by reference numeral 190 in FIG. 1.
[0043] In one example, the channel sounding receiver 120 includes
one or more phased array antennas that may be activated and
deactivated according to a schedule or otherwise synchronized to
the transmission of channel sounding waveforms. In one example,
each phased array antenna may be paired with an RF front end to
receive radio frequency (RF) signals from the respective phased
array antenna and convert the signals into baseband signals. A
digital sampling unit (e.g., an analog-to-digital converter (ADC)
of a baseband processing unit) may convert the baseband signals
into digital representations of the channel sounding waveforms that
are received via the respective phased array antennas. For
instance, the digital sampling unit(s) may oversample the analog
baseband signals at a sampling interval under the control of timing
signals from a clock circuit to create the digital representations
of the channel sounding waveforms. In one example, each phased
array may cover 90-180 degrees in azimuth, 90-180 degrees in
elevation, etc., and the phased arrays may collectively cover 360
degrees in azimuth and 120-180 degrees in elevation (or greater,
e.g., to account for angles below horizon).
[0044] In one example, the baseband processing units may output the
digital representations of the channel sounding waveforms to a
processor unit that is configured to perform various operations for
determining measures of wireless channel parameters, as described
herein. For instance, the channel sounding receiver 120 may
calculate, based upon the digital representations of the channel
sounding waveforms, a phase difference between channel sounding
waveforms received via respective antennas. The processor unit may
further determine an angle of arrival (AoA) based upon the antenna
positions and the phase difference.
[0045] In one example, the channel sounding receiver 120 may
receive a reference copy or copies of the channel sounding
waveforms(s) and/or a set of parameters characterizing the channel
sounding waveforms, from the channel sounding transmitter 125.
Accordingly, the channel sounding receiver 120 may determine a
carrier-to-interference ratio (CIR) by comparing a sequence
received via one of the phased array antennas with a reference
copy. Similarly, the channel sounding receiver 120 may calculate a
complex impulse response, a path loss, an RSS, a CIR, an excess
delay, an RMS delay spread, an angular spread, a Doppler spread, a
fade rate, an AoA, or the like, from the digital representations of
the channel sounding waveforms.
[0046] In one example, the channel sounding receiver 120 does not
calculate various measures of wireless channel parameters, or KPIs,
in real-time, but rather may store digital baseband signals as the
channel sounding receiver 120 performs fast switching to sweep one
or more receive beams through various angles of arrival (AoA) and
obtain multiple digital baseband signals for the various receive
beam direction(s), e.g., within a coherence time of the "wireless
channel(s)" 190. The channel sounding receiver may then, at a later
time, calculate the various measures of wireless channel parameters
from the stored digital baseband signals that are derived from the
received channel sounding waveforms (e.g., via the digital baseband
units and/or via a processing system including one or more other
processors).
[0047] Alternatively, or in addition, the channel sounding receiver
120 may store digital baseband signals and may then provide the
digital baseband signals to the channel sounding transmitter 125 at
a later time (e.g., after receiving various channel sounding
waveforms at one or more locations). In such an example, the
channel sounding transmitter 125 may perform similar calculations
of the measures of wireless channel parameters. In still another
example, the channel sounding receiver 120 may provide the digital
baseband signals to another device and/or processing system (e.g.,
a network-based server, such as application server (AS) 145) which
may then calculate measures of wireless channel parameters.
[0048] In one example, the channel sounding transmitter 125 and the
channel sounding receiver 120 may establish a wireless side link
for exchanging timing information as well as for conveying
information regarding the channel sounding waveforms (e.g., a
reference copy or copies, and/or modulation parameters, beam
information, etc.). To illustrate, a wireless side link may include
a communication session via cellular network infrastructure, e.g.,
including at least wireless links 192 and 193. Alternatively, the
wireless side link may comprise a wireless communication session
via a non-cellular wireless networking protocol, such as IEEE
802.11/Wi-Fi, or the like, or via a wireless communication session
in accordance with a set of non-restricted frequency resources
(e.g., using ISM band frequencies). In such examples, the
non-cellular wireless communication session may include an access
point (AP) coordinator (not shown) and/or a peer-to-peer session
(represented by wireless link 191 in FIG. 1). In addition, in such
examples, the non-cellular wireless link(s) may comprise
out-of-band wireless links (which use different frequencies from
the channel sounding waveforms and the "wireless channel(s)" 190.
In examples where the wireless side link comprises an out-of-band
wireless link, the channel sounding receiver 120 and the channel
sounding transmitter 125 may use a different set of antennas, RF
front ends, and/or baseband units than those which are used for
channel sounding/channel property measurements in accordance with
the present disclosure.
[0049] In still another example, wireless link 190 may represent an
in-band wireless link, which may share the same frequency resources
as the channel sounding waveforms and/or the "wireless channel(s)"
190, but which may utilize different time resources (different time
blocks). For instance, the channel sounding waveforms may be for
millimeter wave frequencies (30 GHz to 300 GHz) as carrier
frequencies, where the wireless side link utilizes the same set of
frequencies or frequency bands. In all of these examples, the
wireless side link may be used to transmit a synchronization signal
by the channel sounding transmitter 125, in addition to other
information regarding one or more channel sounding waveforms, such
as reference copies or parameters thereof, beam information, timing
information, etc. The wireless side link may also be used by the
channel sounding receiver 120 to notify the channel sounding
transmitter 125 that the channel sounding receiver 120 is in
position and ready to measure, to confirm that a clock circuit of
the channel sounding receiver 120 is matched to the synchronization
signal, to confirm successful measurements to the channel sounding
transmitter 125 or to indicate one or more failed measurements, to
report the measurements to the channel sounding transmitter 125,
and so forth.
[0050] In one example, the channel sounding receiver 120 may store
one or more wireless channel parameter measurements (and/or digital
baseband signals) in a record, along with the spatial orientation
information and a location associated with the wireless channel
parameter measurements (and/or digital baseband signals), e.g., in
a local memory. In one example, the channel sounding receiver 120
may be deployed to obtain wireless channel parameter measurements
(and/or digital baseband signals) at various locations within an
environment and may collect and store all of the measurements
(and/or digital baseband signals). The measurements (and/or digital
baseband signals) may then be retrieved at a later time and
transferred to another device or system for storage and/or
analysis. For instance, associated data from the mobile channel
sounding transmitter regarding the transmit beam(s), the channel
sounding waveforms, the location(s) of the mobile channel sounding
transmitter, etc. may be stored and/or transferred to the channel
sounding transmitter 125 for storage and/or analysis. This can be
done after obtaining a series of measurements (and/or digital
baseband signals), e.g., via a cable connection when the channel
sounding transmitter 125 and channel sounding receiver 120 are
together in a same location, or may be transmitted wirelessly by
the channel sounding receiver 120 to the channel sounding
transmitter 125 via a wireless side link.
[0051] In one example, the channel sounding transmitter 125 may
store various information in connection with channel sounding
waveforms that are transmitted, such as a timestamp, spatial
orientation information (e.g., a transmit beam direction, or angle
of departure (AoD)), and a location. This information may then be
correlated with corresponding information of the channel sounding
receiver 120. For instance, a received signal strength (RSS) for a
particular angle of arrival at a location may be correlated with a
location, AoD, and transmit strength of the channel sounding
transmitter 125 to provide a more comprehensive snapshot of the
wireless channel(s) 190.
[0052] In one example, the channel sounding receiver 120 and
channel sounding transmitter 125 may each comprise all or a portion
of a computing device or system, such as computing system 500,
and/or processing system 502 as described in connection with FIG. 5
below, and may be configured to provide one or more functions for
measuring wireless channel parameters using a phased array channel
sounding transmitter, and for performing various other operations
in accordance with the present disclosure. For instance, a channel
sounding system comprising channel sounding transmitter 125 (and/or
channel sounding transmitter 125 in conjunction with channel
sounding receiver 120) may be configured to perform functions such
as those described below in connection with the example method 400
of FIG. 4.
[0053] In addition, it should be noted that as used herein, the
terms "configure," and "reconfigure" may refer to programming or
loading a processing system with
computer-readable/computer-executable instructions, code, and/or
programs, e.g., in a distributed or non-distributed memory, which
when executed by a processor, or processors, of the processing
system within a same device or within distributed devices, may
cause the processing system to perform various functions. Such
terms may also encompass providing variables, data values, tables,
objects, or other data structures or the like which may cause a
processing system executing computer-readable instructions, code,
and/or programs to function differently depending upon the values
of the variables or other data structures that are provided. As
referred to herein a "processing system" may comprise a computing
device including one or more processors, or cores (e.g., as
illustrated in FIG. 5 and discussed below, and which may include
central processing units (CPUs), graphics processing units (GPUs),
programmable logic devices (PLDs), and so forth) or multiple
computing devices collectively configured to perform various steps,
functions, and/or operations in accordance with the present
disclosure.
[0054] In one example, the EPC network 105 provides various
functions that support wireless services in the LTE environment. In
one example, EPC network 105 is an Internet Protocol (IP) packet
core network that supports both real-time and non-real-time service
delivery across a LTE network, e.g., as specified by the 3GPP
standards. In one example, cell sites 111 and 112 in the access
network 103 are in communication with the EPC network 105 via
baseband units in BBU pool 114. In operation, UE 116 may access
wireless services via the cell site 111 and UE 117 may access
wireless services via the cell site 112 located in the access
network 103. It should be noted that any number of cell sites can
be deployed in access network. In one illustrative example, the
access network 103 may comprise one or more cell sites.
[0055] In EPC network 105, network devices such as Mobility
Management Entity (MME) 107 and Serving Gateway (SGW) 108 support
various functions as part of the cellular network 101. For example,
MME 107 is the control node for the LTE access network. In one
embodiment, MME 107 is responsible for UE (User Equipment) tracking
and paging (e.g., such as retransmissions), bearer activation and
deactivation process, selection of the SGW, and authentication of a
user. In one embodiment, SGW 108 routes and forwards user data
packets, while also acting as the mobility anchor for the user
plane during inter-cell handovers and as the anchor for mobility
between 5G, LTE and other wireless technologies, such as 2G and 3G
wireless networks.
[0056] In addition, EPC network 105 may comprise a Home Subscriber
Server (HSS) 109 that contains subscription-related information
(e.g., subscriber profiles), performs authentication and
authorization of a wireless service user, and provides information
about the subscriber's location. The EPC network 105 may also
comprise a packet data network (PDN) gateway 110 which serves as a
gateway that provides access between the EPC network 105 and
various data networks, e.g., service network 140, IMS core network
115, other network(s) 180, and the like. The packet data network
gateway 110 is also referred to as a PDN gateway, a PDN GW or a
PGW. In addition, the EPC network 105 may include a Diameter
routing agent (DRA) 106, which may be engaged in the proper routing
of messages between other elements within EPC network 105, and with
other components of the system 100, such as a call session control
function (CSCF) (not shown) in IMS core network 115. For clarity,
the connections between DRA 106 and other components of EPC network
105 are omitted from the illustration of FIG. 1.
[0057] In one example, service network 140 may comprise one or more
devices, such as application server (AS) 145 for providing services
to subscribers, customers, and or users. For example,
telecommunication service provider network 170 may provide a cloud
storage service, web server hosting, and other services. As such,
service network 140 may represent aspects of telecommunication
service provider network 170 where infrastructure for supporting
such services may be deployed. In one example, AS 145 may comprise
all or a portion of a computing device or system, such as computing
system 500, and/or processing system 502 as described in connection
with FIG. 5 below, specifically configured to provide one or more
service functions in accordance with the present disclosure, such
as a network-based secure data storage for wireless channel
parameter measurement records. For instance, channel sounding
receiver 120 and/or channel sounding transmitter 125 may forward
measurements of wireless channel parameters to AS 145 for storage.
Either or both of channel sounding receiver 120 and channel
sounding transmitter 125 may also forward additional data to AS 145
for storage, such as reference copies of the channel sounding
waveform(s) and/or parameters thereof, transmit beam information,
time stamp information, location information of the channel
sounding receiver 120 and channel sounding transmitter 125, and so
forth. Although a single application server, AS 145, is illustrated
in service network 140, it should be understood that service
network 140 may include any number of components to support one or
more services that may be provided to one or more subscribers,
customers, or users by the telecommunication service provider
network 170.
[0058] In one example, other networks 180 may represent one or more
enterprise networks, a circuit switched network (e.g., a public
switched telephone network (PSTN)), a cable network, a digital
subscriber line (DSL) network, a metropolitan area network (MAN),
an Internet service provider (ISP) network, and the like. In one
example, the other networks 180 may include different types of
networks. In another example, the other networks 180 may be the
same type of network. In one example, the other networks 180 may
represent the Internet in general.
[0059] In accordance with the present disclosure, any one or more
of the components of EPC network 105 may comprise network function
virtualization infrastructure (NFVI), e.g., SDN host devices (i.e.,
physical devices) configured to operate as various virtual network
functions (VNFs), such as a virtual MME (vMME), a virtual HHS
(vHSS), a virtual serving gateway (vSGW), a virtual packet data
network gateway (vPGW), and so forth. For instance, MME 107 may
comprise a vMME, SGW 108 may comprise a vSGW, and so forth. In this
regard, the EPC network 105 may be expanded (or contracted) to
include more or less components than the state of EPC network 105
that is illustrated in FIG. 1. In this regard, the EPC network 105
may also include a self-optimizing network (SON)/software defined
network (SDN) controller 102.
[0060] In one example, SON/SDN controller 102 may function as a
self-optimizing network (SON) orchestrator that is responsible for
activating and deactivating, allocating and deallocating, and
otherwise managing a variety of network components. In one example,
SON/SDN controller 102 may further comprise a SDN controller that
is responsible for instantiating, configuring, managing, and
releasing VNFs. For example, in a SDN architecture, a SDN
controller may instantiate VNFs on shared hardware, e.g., NFVI/host
devices/SDN nodes, which may be physically located in various
places.
[0061] The foregoing description of the system 100 is provided as
an illustrative example only. In other words, the example of system
100 is merely illustrative of one network configuration that is
suitable for implementing embodiments of the present disclosure. As
such, other logical and/or physical arrangements for the system 100
may be implemented in accordance with the present disclosure. For
example, channel sounding may utilize multiple channel sounding
receivers to receive channel sounding signals/waveforms from
channel sounding transmitter 125. Similarly, multiple mobile
channel sounding transmitters may be utilized for channel sounding
in conjunction with channel sounding receiver 120 and/or multiple
channel sounding receivers.
[0062] In one example, the system 100 may be expanded to include
additional networks, such as network operations center (NOC)
networks, additional access networks, and so forth. The system 100
may also be expanded to include additional network elements such as
border elements, routers, switches, policy servers, security
devices, gateways, a content distribution network (CDN) and the
like, without altering the scope of the present disclosure. In
addition, system 100 may be altered to omit various elements,
substitute elements for devices that perform the same or similar
functions, combine elements that are illustrated as separate
devices, and/or implement network elements as functions that are
spread across several devices that operate collectively as the
respective network elements. For instance, in one example, SON/SDN
controller 102 may be spilt into separate components to operate as
a SON orchestrator and a SDN controller, respectively. Similarly,
although the SON/SDN controller 102 is illustrated as a component
of EPC network 105, in another example SON/SDN controller 102,
and/or other network components may be deployed in an IMS core
network 115 instead of being deployed within the EPC network 105,
or in other portions of system 100 that are not shown, while
providing essentially the same functionality.
[0063] In addition, although aspects of the present disclosure have
been discussed above in the context of a long term evolution
(LTE)-based core network (e.g., EPC network 105), examples of the
present disclosure are not so limited. For example, as illustrated
in FIG. 1, the cellular network 101 may represent a "non-stand
alone" (NSA) mode architecture where 5G radio access network
components, such as a "new radio" (NR), "gNodeB" (or "gNB"), and so
forth are supported by a 4G/LTE core network (e.g., a Evolved
Packet Core (EPC) network 105). However, in another example, system
100 may instead comprise a 5G "standalone" (SA) mode point-to-point
or service-based architecture where components and functions of EPC
network 105 are replaced by a 5G core network, which may include an
access and mobility management function (AMF), a user plane
function (UPF), a session management function (SMF), a policy
control function (PCF), a unified data management function (UDM),
an authentication server function (AUSF), an application function
(AF), a network repository function (NRF), and so on. For instance,
in such a network, application server (AS) 145 of FIG. 1 may
represent an application function (AF) for adjusting aspects of a
cellular network in response to measurements of wireless channel
parameters by a receiver device, and for performing various other
operations in accordance with the present disclosure. In addition,
any one or more of cell sites 111-113 may comprise 2G, 3G, 4G
and/or LTE radios, e.g., in addition to 5G new radio (NR)
functionality. For instance, in non-standalone (NSA) mode
architecture, LTE radio equipment may continue to be used for cell
signaling and management communications, while user data may rely
upon a 5G new radio (NR), including millimeter wave communications,
for example. Thus, these and other modifications are all
contemplated within the scope of the present disclosure.
[0064] FIG. 2 illustrates an example translation of spatial
orientation information of a local coordinate system with respect
to phased array antennas into a global coordinate system. In
particular, FIG. 2 illustrates an environment 200 containing a
channel sounding transmitter 201 with at least three phased array
antennas 205-207. It should be noted that the example of FIG. 2 is
provided for illustrative purposes in connection with just one
illustrative architecture comprising a plurality of phased array
antennas. Thus, the following discussion is equally applicable to
other arrangements of phased array antennas, such as four phased
array antennas in a rectangular or square layout, two
half-cylindrical phased array antennas, and so forth.
[0065] As illustrated in FIG. 2, the orientation of phased array
antennas 205-207 is shown with respect to local coordinate system
290 containing axis (x, y, z). A global coordinate system 295
having a different orientation and containing axis (u, v, w) is
also illustrated in FIG. 2. The channel sounding transmitter 201
may be configured to transmit multi-path and/or spatial diversity
signals, e.g., via transmit beam directions 210-219 of phased array
antenna 205. Each of the transmit beam directions 210-219 may have
different azimuth and elevation bearings from the other transmit
beam directions of transmit beam directions 210-219. In one
example, the transmit beam directions 210-219 may be identified by
transmit beam indexes/indices or logical beam identifiers (beam
IDs).
[0066] In one example, the channel sounding transmitter 201 can
transmit a wireless signal (e.g., a channel sounding waveform) on a
transmit beam that is oriented in one of the transmit beam
directions 210-219 via selection/control of voltage(s) and/or
phase(s) in the transmit circuitry associated with one or more
given antenna elements of the phased array antenna 205, or via a
logical index associated with a respective transmit beam direction
210-219. The channel sounding transmitter 201 may also translate or
map each of the transmit beam directions 210-219 to a set of angles
(or angles and magnitudes), n-tuples of coordinates defining a unit
vector (or defining a magnitude and direction/orientation), or any
other definitive units of local coordinate system 290, thereby
giving the transmit beam directions 210-219, identified with a
logical "beam ID," a physical spatial direction/orientation with
respect to the local coordinate system 290. For instance, the
channel sounding transmitter 201 may be configured by a
manufacturer or operator with such a mapping by utilizing
combinations of voltage and/or phase settings, and observing and
recording actual transmit beam directions. A similar procedure may
be applied to transmit beams (and transmit beam directions)
associated with phased array antennas 206 and 207.
[0067] In one example, the local coordinate system 290 may be
mapped or translated to the global coordinate system 295. For
instance, global coordinate system 295 may have two dimensions
corresponding to a planar estimation of the surface of the Earth
(e.g., the "u" axis and "v" axis in FIG. 2), with the third
dimension (e.g., the "w" axis) being normal to the plane. In
addition, the planar estimation of the surface of the Earth can
also be aligned such that one dimension is north-south (e.g., the
"v" axis) and another dimension is east-west (e.g., the "u" axis).
Accordingly, the orientations of the (x, y, z) axis of local
coordinate system 290 relative to the (u, v, w) axis of global
coordinate system 295 may be determined from a gyroscope and
compass of the channel sounding transmitter 201. The transmit beam
directions 210-219 may be similarly translated into
directions/orientations in the global coordinate system 295 via the
same mapping.
[0068] In one example, a location of the channel sounding
transmitter 201 in local coordinate system 290 may be translated
into a location in global coordinate system 295. For instance,
channel sounding transmitter 201 may estimate its position relative
to several base stations/cell sites using observed time difference
of arrival (OTDA). Once channel sounding transmitter 201 determines
its location relative to these base stations/cell sites, the
channel sounding transmitter 201 may then determine an absolute
location (e.g., a latitude and a longitude) from the location
relative to fixed known locations of the base stations/cell sites.
However, in another example, the channel sounding transmitter 201
may include a GPS receiver such that channel sounding transmitter
201 may determine an absolute location (e.g., in global coordinate
system 295) which may comprise a standard latitude and
longitude.
[0069] In one example, the channel sounding transmitter 201 may
store various information in connection with channel sounding
waveforms that are transmitted, such as a timestamp, spatial
orientation information (e.g., a transmit beam direction, or angle
of departure (AoD)), and a location. This information may then be
correlated with corresponding information from a channel sounding
receiver. For instance, a received signal strength (RSS) for a
particular angle of arrival at a location may be correlated with a
location of the channel sounding transmitter 201, an angle of
departure and transmit strength of the channel sounding signal, and
so forth to provide a more comprehensive snapshot of the wireless
channel(s) being measured.
[0070] It should be noted that in a channel sounding system of the
present disclosure, a channel sounding receiver may have similar
components and a similar configuration as the channel sounding
transmitter 201, and may similarly translate receive beam
directions in a local coordinate system into receive beam
directions in the same global coordinate system as the channel
sounding transmitter 201. In examples where locations are
determined using OTDA from cell sites, the channel sounding
receiver may also translate a location in a local coordinate system
into a location in the same global coordinate system as the channel
sounding transmitter 201.
[0071] To illustrate, for a given location in the local coordinate
system 290 corresponding to a location in the global coordinate
system 295, the channel sounding receiver may collect a set of
measurements of one or more wireless channel parameters (and/or a
set of digital baseband signals). For example, for each spatial
direction/receive beam direction, the channel sounding receiver may
set the phase and/or the voltage driving each antenna element of a
phased array antenna according to a look up table where each entry
corresponds to a receive beam index, receive a waveform (a channel
sounding waveform) via the receive beam pointed in a corresponding
one of the receive beam directions, and generate and store a
digital baseband signal derived from the received waveform. In one
example, the channel sounding receiver may later calculate or
determine the measures of various wireless channel parameters based
upon the stored digital baseband signals. Thus, for the given
location the channel sounding receiver will sample the space
according to the receive beam directions in the look-up table.
Furthermore, each wireless channel parameter measurement and/or
digital baseband signal may be associated with a position and
orientation of the channel sounding receiver.
[0072] FIG. 3 illustrates a portion of an example channel sounding
transmitter 300, in accordance with the present disclosure. As
illustrated in FIG. 3, channel sounding transmitter 300 includes a
phased array antenna 350 having a plurality of antenna elements
355. The phased array antenna 350 may be coupled to a radio
frequency (RF) front end 340. RF front end 340 may comprise a
circuit between the phased array antenna 350 and a digital baseband
unit 330 (e.g., a 5G radio transceiver). In the example of FIG. 3,
the RF front end 340 includes a plurality of filters 343, a
plurality of variable phase shifters 342, and a plurality of
variable gain amplifiers 341. RF front end 340 may further include
a RF-to-baseband upconverter 344 that is controlled by local
oscillator (LO) 345 and which may up-convert baseband frequency
range signals to RF signals.
[0073] The processor unit 310 may generate digital representations
of channel sounding waveforms and provide these digital
representations to digital baseband unit 330. The digital-to-analog
converter (DAC) 346 may obtain the digital representations of
channel sounding waveforms and output baseband frequency range
representations of the channel sounding waveforms. The baseband
frequency range representations may then be up-converted to the
channel sounding waveforms (e.g., RF signals) by the baseband-to-RF
upconverter 344.
[0074] In one example, processor unit 310 may adjust the gain(s) of
variable gain amplifiers 341 and/or the phase delays of variable
phase shifters 342 via control lines 390 to provide a transmit beam
having specified characteristics (e.g., beam direction, beam width,
transmit signal strength/gain, etc.). In one example, the pass band
of filters 343 may also be controlled via control lines 390. The
control of these elements of RF front end 340 may be based upon the
various criteria, including the bit sequences of the channel
sounding waveform(s) and/or other characterization parameters of
the channel sounding waveform(s). In one example, the processor
unit 310 may also configure digital baseband unit 330 and/or DAC
346 to function in a particular manner, e.g., based upon the
characterization parameters of the channel sounding waveform(s) to
be transmitted.
[0075] In one example, the processor unit 310 may comprise all or a
portion of a computing device or system, such as system 500, and/or
processor 502 as described in connection with FIG. 5 below. In one
example, the processor unit 310 may perform functions, such as
communicating with the a network-based server and/or a channel
sounding receiver to obtain reference copies of channel sounding
waveforms or characterization parameters of the channel sounding
waveform(s) that are to be transmitted. The characterization
parameters may include: a transmit power, a waveform/sequence
indication, timing indication (e.g., transmission duration,
periodicity, offset, and the like), frequency location (e.g.
sub-band index, grid alignment, transmission bandwidth), and so
forth.
[0076] In one example, the processing unit 310 may store various
information in connection with channel sounding waveforms that are
transmitted, such as a timestamp, spatial orientation information
(e.g., a transmit beam direction, or angle of departure (AoD)), and
a location. This information may then be correlated with
corresponding information from a channel sounding receiver. For
instance, a received signal strength (RSS) for a particular angle
of arrival at a location of a channel sounding receiver may be
correlated with a location of the channel sounding transmitter 300,
an angle of departure and transmit strength of the channel sounding
signal, and so forth to provide a more comprehensive snapshot of
the wireless channel(s) being measured.
[0077] It should also be noted that FIG. 3 illustrates one transmit
path of channel sounding transmitter 300 that includes phased array
antenna 350. However, channel sounding transmitter 300 may include
a plurality of additional phased array antennas, RF front ends, and
digital baseband units coupled to processor unit 310 that are the
same or substantially similar to the portion of channel sounding
transmitter 300 illustrated in FIG. 3. Thus, processor unit 310 may
also control aspects of other RF front ends to steer transmit beams
via respective phased array antennas, may generate digital
representations to be converted into the channel sounding
waveform(s), and so forth.
[0078] It should also be noted that the example of FIG. 3 provides
just one example of a transmit path of a channel sounding
transmitter in accordance with the present disclosure. For
instance, in another example, DAC 346 may be included in RF front
end 340, e.g., instead of in the digital baseband unit 330. In
still another example, the filters 343 may comprise diplexers which
may be configured and reconfigured for transmit and receive modes,
respectively. In one example, the antenna elements 355 may comprise
dual polarization antenna elements. However, for ease of
illustration, the portion of the channel sounding transmitter 300
depicted in FIG. 3 may be related to one of the polarizations.
Thus, these and other modifications are all contemplated within the
scope of the present disclosure.
[0079] In addition, in a channel sounding system of the present
disclosure, a channel sounding receiver may have similar components
and a similar configuration as the channel sounding transmitter
300. For example, a channel sounding receiver may include at least
one phased array antenna having a plurality of antenna elements
coupled to at least one radio frequency (RF) front end with a
plurality of filters, a plurality of variable phase shifters, and a
plurality of variable gain amplifiers, and a RF-to-baseband
downconverter that is controlled by a local oscillator (LO) and
which may down-convert received signals to a baseband frequency
range. The RF-to-baseband downconverter may feed received and
down-converted signals (e.g., analog baseband signals) to an
analog-to-digital converter (ADC) of a digital baseband unit, which
may sample the analog baseband signals to output digital baseband
signals. For instance, the ADC may oversample the analog baseband
signals at a sampling interval under the control of timing signals
from a clock circuit (e.g., including a rubidium reference clock or
the like) to create digital representations of the channel sounding
waveforms that are received (broadly, "digital baseband signals").
The channel sounding receiver may also include a processing system
to store the digital baseband signals and/or to calculate one or
more measures of various wireless channel parameters, to provide
the digital baseband signals and/or measure(s) of wireless channel
parameters to the channel sounding transmitter 300, and so forth.
In one example, certain measurements of wireless channel parameters
may be determined in a digital baseband unit of the channel
sounding receiver, e.g., as an alternative or in addition to
determining measurements of wireless channel parameters by the
processor unit. In such an example, the digital baseband unit may
forward measurements of one or more wireless channel parameters to
the processor unit of the channel sounding receiver, e.g., for
further tagging with location and/or spatial orientation
information.
[0080] FIG. 4 illustrates a flowchart of an example method 400 for
measuring wireless channel parameters using a phased array channel
sounding transmitter, in accordance with the present disclosure. In
one example, steps, functions and/or operations of the method 400
may be performed by a channel sounding system including at least a
first processing system (e.g., comprising a channel sounding
transmitter, or any one or more components thereof, such as one or
more processors, baseband units, transceivers, antennas or antenna
arrays (e.g., phased array antennas), and so forth). In one
example, the channel sounding system may also include a second
processing system (e.g., comprising channel sounding receiver, or
any one or more components thereof, such as one or more processors,
baseband units, transceivers, antennas or antenna arrays (e.g.,
phased array antennas), and so forth). In accordance with the
present disclosure, a processing system may include one or more
processors, which can include CPUs, PLDs, or a combination thereof.
For instance, a processing system may include central processing
unit, a digital baseband unit, and so forth. In one example, the
steps, functions, or operations of method 400 may be performed by a
computing device or system 500, and/or a processing system 502 as
described in connection with FIG. 5 below, or multiple instances of
the computing device or system 500. For instance, the computing
device 500 may represent at least a portion of a mobile channel
sounding transmitter in accordance with the present disclosure.
Similarly, the computing device 500 may represent at least a
portion of a mobile channel sounding receiver in accordance with
the present disclosure. For illustrative purposes, the method 400
is described in greater detail below in connection with an example
performed by at least a first processing system. The method 400
begins in step 405 and proceeds to step 410.
[0081] At step 410, a first processing system (e.g., of a channel
sounding transmitter) provides at least two baseband signals to at
least two RF front ends of the channel sounding transmitter. For
instance, the at least two baseband signals may comprise digital
baseband signals intended for conversion to at least two RF channel
sounding waveforms to be transmitted via phased array antennas of
the channel sounding transmitter. In other words, the baseband
signals may comprise digital representations of the RF channel
sounding waveforms.
[0082] At step 415, the first processing system steers respective
transmit beams via instructions to at least two radio frequency
front ends. For example, the channel sounding transmitter may
include the at least two RF front ends coupled to at least two
phased array antennas to generate at least two radio frequency
channel sounding waveforms from the at least two baseband signals.
In addition, the channel sounding transmitter may include the at
least two phased array antennas, each of which is controllable to
provide a respective transmit beam that is steerable in azimuth and
elevation, and that comprises one of the at least two RF channel
sounding waveforms. In one example, the at least two RF channel
sounding waveforms that are transmitted via the respective transmit
beams are orthogonal signals that are transmitted at a same
time.
[0083] In one example, faces of the at least two phased array
antennas are arranged to provide a transmit beam coverage over 360
degrees in azimuth. For example, the at least two phased array
antennas may comprise a pair of half-cylindrical antennas, where
each of the half-cylindrical antennas provides the receive beam
coverage over at least a 180 degree azimuthal sector. In another
example, the at least two phased array antennas may comprise at
least three phased array antennas, where each of the at least three
phased array antennas provides a transmit beam coverage over at
least a 120 degree azimuthal sector. In still another example, the
at least three phased array antennas may comprise at least four
phased array antennas, where each of the at least four phased array
antennas provides a transmit beam coverage over at least a 90
degree azimuthal sector, and so on.
[0084] In one example, each of the at least two RF front ends
includes a baseband-to-RF upconverter, which may receive a baseband
signal representing a channel sounding waveform, and which may
convert the baseband signal to a respective one of the RF channel
sounding waveforms. In one example, each of the at least two RF
front ends includes a plurality of variable phase shifters
associated with respective antenna elements of an associated one of
the at least two phased array antennas. Accordingly, the
instructions to the at least two RF front ends to steer the
respective transmit beams may be for controlling the plurality of
variable phase shifters to control the directions of the respective
transmit beams. In one example, each of the at least two RF front
ends may further include a plurality of variable gain amplifiers
(VGAs) to further steer the respective transmit beams and/or to
control the beamwidths of the respective transmit beams. In one
example, each of the transmit beams may comprise a directional beam
with a half-power beamwidth of less than 30 degrees. In one
example, the steering of the respective transmit beams at step 415
further comprises controlling the half-power beamwidth of the each
of the transmit beams via the instructions (e.g., for controlling
the phase shifters and/or VGAs).
[0085] At step 420, the first processing system may record spatial
orientation information of the respective transmit beams (e.g.,
along with any characterization parameters of the respective RF
channel sounding waveforms and/or the digital representations
thereof). In one example, the first processing system may further
record timing information of the respective transmit beams (e.g.,
of the transmission of the respective RF channel sounding waveforms
via the transmit beams). To illustrate, the channel sounding
transmitter may comprise a gyroscope and a compass. As such, the
first processing system may determine the spatial orientation
information of the respective transmit beams via the gyroscope and
the compass. In one example, the first processing system may also
translate beam directions from a local coordinate system to a
global coordinate system. In one example, the first processing
system may also record location information of the channel sounding
transmitter associated with the transmission of respective RF
channel sounding waveforms via the transmit beam(s). For instance,
the location information may be determined via OTDA techniques with
respect to a plurality of cellular base stations or the like, or
may be determined via a GPS of the channel sounding
transmitter.
[0086] At step 425, a second processing system (e.g., of a channel
sounding receiver) may steer a respective receive beam via
instructions to at least one RF front end of the wireless channel
sounding receiver. For example, the wireless channel sounding
receiver may comprise at least one phased array antenna
controllable to provide the respective receive beam that is
steerable in azimuth and elevation. The wireless channel sounding
receiver may also comprise least one RF front end coupled to the at
least one phased antenna array to receive at least one RF channel
sounding waveform from the wireless channel sounding transmitter
via the respective receive beam and generate at least one baseband
signal from the at least one RF channel sounding waveform. It
should be noted that the channel sounding receiver may include any
number of phased array antennas, RF front ends, baseband processing
units, and so forth, as described above (e.g., two half-cylindrical
phased array antennas, three planar phased array antennas, four
planar phased array antennas, etc., along with corresponding RF
front end(s) and baseband processing unit(s)).
[0087] At step 430, the second processing system may receive the at
least one baseband signal from the at least one RF front end. For
instance, the at least one RF front end may include an
RF-to-baseband downconverter. In one example, the baseband signal
may comprise a digital baseband signal. For instance, the RF front
end may further comprise an analog-to-digital converter (ADC) to
sample the analog baseband signals to provide digital baseband
signals.
[0088] At step 435, the second processing system records the at
least one baseband signal. For instance, the channel sounding
receiver may include a memory or storage unit to store the at least
one baseband signal.
[0089] At step 440, the second processing system may record
location information of the channel sounding receiver, spatial
orientation information of the respective receive beam, and timing
information for a receiving of the at least one baseband signal. To
illustrate, the channel sounding receiver may comprise a gyroscope
and a compass. As such, the second processing system may determine
the spatial orientation information of the respective receive
beam(s) via the gyroscope and the compass. In one example, the
second processing system may also translate beam directions from a
local coordinate system to a global coordinate system. In one
example, the location information may be determined via OTDA
techniques with respect to a plurality of cellular base stations or
the like, or may be determined via a GPS of the channel sounding
receiver. In one example, step 440 may be performed at the same
time as and/or in conjunction with step 435.
[0090] At step 445, the second processing system may transmit the
at least one baseband signal, the location information of the
channel sounding receiver, the spatial orientation information of
the respective receive beam, and the timing information to the
first processing system. In one example, the transmitting is at a
time that is at least after the coherence time of the channel with
respect to receiving the at least one baseband signal. In other
words the channel sounding receiver records a sequence of one or
more baseband signals from one or more received RF channel sounding
waveforms via one or more receive beams within the coherence time
of the channel. Then the plurality of baseband signals is sent at
some later time to the first processing system of the channel
sounding transmitter.
[0091] At step 450, the second processing system may determine a
plurality of measurements of at least one wireless channel
parameter based upon the at least one baseband signal. For
instance, in one example, step 450 may be performed after the at
least one baseband signal is recorded at step 435 and after the
coherence time of the channel with respect to receiving the at
least one baseband signal from the RF front end. In other words,
the channel sounding receiver records a sequence of one or more
baseband signals from one or more received RF channel sounding
waveforms via one or more receive beams within the coherence time
of the channel. Then the plurality of measurements is calculated at
some later time. In one example, the at least one wireless channel
parameter may comprise a complex impulse response, a path loss, a
received signal strength (RSS), e.g., a reference signal received
power (RSRP), a carrier-to-interference (CIR) ratio (or
signal-to-noise ratio (SNR)), an excess delay, a root-mean-square
(RMS) delay spread, an angular spread, a Doppler spread, a fade
rate, an angle of arrival (AoA), and the like.
[0092] At step 455, the second processing system may record the
plurality of measurements of at least one wireless channel
parameter. For instance, the channel sounding receiver may be
reoriented, may be moved to a different location, and so forth.
Additional recordings of baseband signals derived from RF channel
sounding waveforms received via one or more receive beams may also
be obtained, additional measurements of at least one wireless
channel parameter may be determined and stored, and so forth. The
plurality of measurements of at least one wireless channel
parameter may be stored/recorded along with associated spatial
orientation information, such as azimuth and elevation angles, and
locations associated with the measurements.
[0093] At step 460, the second processing system may transmit the
plurality of measurements of the at least one wireless channel
parameter to the first processing system (e.g., to the channel
sounding transmitter). For instance, the first processing system
may correlate the plurality of measurements of the at least one
wireless channel parameter with stored information comprising:
spatial orientation information of the respective transmit beams
(e.g., along with any characterization parameters of the respective
RF channel sounding waveforms and/or the digital representations
thereof), timing information of the respective transmit beams
(e.g., of the transmission of the respective RF channel sounding
waveforms via the transmit beams), and so forth to provide a more
comprehensive snapshot of the wireless channel(s) being
measured.
[0094] At step 465, the first processing system may determine a
plurality of measurements of at least one wireless channel
parameter based upon the at least one baseband signal, the location
information of the channel sounding receiver, the spatial
orientation information of the respective receive beam, and the
timing information (e.g., transmitted to the first processing
system by the second processing system at step 445). In one
example, the plurality of measurements of at least one wireless
channel parameter is further based upon information stored by the
first processing system, such as: spatial orientation information
of the respective transmit beams (e.g., along with any
characterization parameters of the respective RF channel sounding
waveforms and/or the digital representations thereof), timing
information of the respective transmit beams, location information
of the channel sounding transmitter, etc. Notably, the first
processing system (of the mobile channel sounding transmitter) may
aggregate measurements with respect to the channel sounding
transmitter and/or the channel sounding receiver at a plurality of
different locations and/or orientations for various purposes, such
as for combining measurements, for generating coverage maps, for
storage and uploading to another device for analysis, and so forth.
Following step 465, the method 400 proceeds to step 495 where the
method 400 ends.
[0095] It should be noted that the method 400 may be expanded to
include additional steps, or may be modified to replace steps with
different steps, to combine steps, to omit steps, to perform steps
in a different order, and so forth. For example, the method 400 is
described in connection with a single channel sounding receiver.
However, in another example, multiple channel sounding receivers
may be used to obtain baseband signals and/or measures of wireless
channel parameter simultaneously and/or in a sequence while
deployed at different locations in an environment of interest. In
another example, one or more steps of the method 400 may be
repeated, e.g., for additional locations of either or both of the
channel sounding receiver and channel sounding transmitter. In one
example, the method 400 may further include the first processing
system and second processing system (e.g., the channel sounding
transmitter and the channel sounding receiver) establishing and/or
communicating over a wireless side link to exchange information
regarding channel sounding waveform(s), such as the shape of the
waveform, e.g., return-to-zero (RZ), non-return-to-zero (NRZ), a
frequency or range of frequencies, the duration of the waveform,
the time and/or frequency resources to be used, and other
properties as described above, to establish a time synchronization
between the channel sounding transmitter and the channel sounding
receiver, and so forth. In still another example, the method 400
may further include either or both of the first processing system
and the second processing system transmitting measure(s) of
wireless channel parameter(s) and associated data (e.g., location
information, timing information, beam orientation information,
etc.) to one or more additional devices. Thus, these and other
modifications are all contemplated within the scope of the present
disclosure.
[0096] In addition, although not specifically specified, one or
more steps, functions, or operations of the method 400 may include
a storing, displaying, and/or outputting step as required for a
particular application. In other words, any data, records, fields,
and/or intermediate results discussed in the method(s) can be
stored, displayed, and/or outputted either on the device executing
the method(s) or to another device, as required for a particular
application. Furthermore, steps, blocks, functions or operations in
FIG. 4 that recite a determining operation or involve a decision do
not necessarily require that both branches of the determining
operation be practiced. In other words, one of the branches of the
determining operation can be deemed as an optional step.
Furthermore, steps, blocks, functions or operations of the above
described method(s) can be combined, separated, and/or performed in
a different order from that described above, without departing from
the example examples of the present disclosure.
[0097] FIG. 5 depicts a high-level block diagram of a computing
device or processing system specifically programmed to perform the
functions described herein. As depicted in FIG. 5, the processing
system 500 comprises one or more hardware processor elements 502
(e.g., a central processing unit (CPU), a microprocessor, or a
multi-core processor), a memory 504 (e.g., random access memory
(RAM) and/or read only memory (ROM)), a module 505 for measuring
wireless channel parameters using a phased array channel sounding
transmitter, and various input/output devices 506 (e.g., storage
devices, including but not limited to, a tape drive, a floppy
drive, a hard disk drive or a compact disk drive, a receiver, a
transmitter, a speaker, a display, a speech synthesizer, an output
port, an input port and a user input device (such as a keyboard, a
keypad, a mouse, a microphone and the like)). In accordance with
the present disclosure input/output devices 506 may also include
antenna elements, antenna arrays, remote radio heads (RRHs),
baseband units (BBUs), transceivers, power units, GPS units, and so
forth. Although only one processor element is shown, it should be
noted that the computing device may employ a plurality of processor
elements. Furthermore, although only one computing device is shown
in the figure, if the method 400 as discussed above is implemented
in a distributed or parallel manner for a particular illustrative
example, i.e., the steps of the above method 400, or the entire
method 400, is implemented across multiple or parallel computing
devices, e.g., a processing system, then the computing device of
this figure is intended to represent each of those multiple
computing devices.
[0098] Furthermore, one or more hardware processors can be utilized
in supporting a virtualized or shared computing environment. The
virtualized computing environment may support one or more virtual
machines representing computers, servers, or other computing
devices. In such virtualized virtual machines, hardware components
such as hardware processors and computer-readable storage devices
may be virtualized or logically represented. The hardware processor
502 can also be configured or programmed to cause other devices to
perform one or more operations as discussed above. In other words,
the hardware processor 502 may serve the function of a central
controller directing other devices to perform the one or more
operations as discussed above.
[0099] It should be noted that the present disclosure can be
implemented in software and/or in a combination of software and
hardware, e.g., using application specific integrated circuits
(ASIC), a programmable gate array (PGA) including a Field PGA, or a
state machine deployed on a hardware device, a computing device or
any other hardware equivalents, e.g., computer readable
instructions pertaining to the method discussed above can be used
to configure a hardware processor to perform the steps, functions
and/or operations of the above disclosed method 400. In one
example, instructions and data for the present module or process
505 for measuring wireless channel parameters using a phased array
channel sounding transmitter (e.g., a software program comprising
computer-executable instructions) can be loaded into memory 504 and
executed by hardware processor element 502 to implement the steps,
functions, or operations as discussed above in connection with the
illustrative method 400. Furthermore, when a hardware processor
executes instructions to perform "operations," this could include
the hardware processor performing the operations directly and/or
facilitating, directing, or cooperating with another hardware
device or component (e.g., a co-processor and the like) to perform
the operations.
[0100] The processor executing the computer readable or software
instructions relating to the above described method can be
perceived as a programmed processor or a specialized processor. As
such, the present module 505 for measuring wireless channel
parameters using a phased array channel sounding transmitter
(including associated data structures) of the present disclosure
can be stored on a tangible or physical (broadly non-transitory)
computer-readable storage device or medium, e.g., volatile memory,
non-volatile memory, ROM memory, RAM memory, magnetic or optical
drive, device or diskette, and the like. Furthermore, a "tangible"
computer-readable storage device or medium comprises a physical
device, a hardware device, or a device that is discernible by the
touch. More specifically, the computer-readable storage device may
comprise any physical devices that provide the ability to store
information such as data and/or instructions to be accessed by a
processor or a computing device such as a computer or an
application server.
[0101] While various examples have been described above, it should
be understood that they have been presented by way of illustration
only, and not a limitation. Thus, the breadth and scope of any
aspect of the present disclosure should not be limited by any of
the above-described examples, but should be defined only in
accordance with the following claims and their equivalents.
* * * * *