U.S. patent application number 17/214609 was filed with the patent office on 2021-07-15 for enhanced sounding for secure mode wireless communications.
The applicant listed for this patent is Xiaogang Chen, Assaf Gurevitz, Feng Jiang, Qinghua Li, Jonathan Segev, Gadi Shor. Invention is credited to Xiaogang Chen, Assaf Gurevitz, Feng Jiang, Qinghua Li, Jonathan Segev, Gadi Shor.
Application Number | 20210218527 17/214609 |
Document ID | / |
Family ID | 1000005520973 |
Filed Date | 2021-07-15 |
United States Patent
Application |
20210218527 |
Kind Code |
A1 |
Li; Qinghua ; et
al. |
July 15, 2021 |
ENHANCED SOUNDING FOR SECURE MODE WIRELESS COMMUNICATIONS
Abstract
This disclosure describes systems, methods, and devices related
to enhanced sounding for secure mode wireless communications. A
device may generate a channel sounding symbol comprising a first
subcarrier and a second subcarrier, wherein a first amplitude of
the first subcarrier is different than a second amplitude of the
second subcarrier. The device may generate a channel sounding
signal comprising the channel sounding symbol. The device may send
the channel sounding signal to a second device.
Inventors: |
Li; Qinghua; (San Ramon,
CA) ; Chen; Xiaogang; (Portland, OR) ;
Gurevitz; Assaf; (Ramat Hasharon, IL) ; Jiang;
Feng; (Santa Clara, CA) ; Segev; Jonathan;
(Tel Mond, IL) ; Shor; Gadi; (Tel Aviv,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Li; Qinghua
Chen; Xiaogang
Gurevitz; Assaf
Jiang; Feng
Segev; Jonathan
Shor; Gadi |
San Ramon
Portland
Ramat Hasharon
Santa Clara
Tel Mond
Tel Aviv |
CA
OR
CA |
US
US
IL
US
IL
IL |
|
|
Family ID: |
1000005520973 |
Appl. No.: |
17/214609 |
Filed: |
March 26, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63001237 |
Mar 27, 2020 |
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63006216 |
Apr 7, 2020 |
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63012534 |
Apr 20, 2020 |
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63021836 |
May 8, 2020 |
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63023558 |
May 12, 2020 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0012 20130101;
H04L 5/0048 20130101; H04L 5/001 20130101; H04L 27/2626
20130101 |
International
Class: |
H04L 5/00 20060101
H04L005/00; H04L 27/26 20060101 H04L027/26 |
Claims
1. A device, the device comprising processing circuitry coupled to
storage, the processing circuitry configured to: generate a channel
sounding symbol comprising a first subcarrier and a second
subcarrier, wherein a first amplitude of the first subcarrier is
different than a second amplitude of the second subcarrier;
generate a channel sounding signal comprising the channel sounding
symbol; and send the channel sounding signal to a second
device.
2. The device of claim 1, wherein the channel sounding signal is a
null data packet (NDP).
3. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a 16
quadrature amplitude modulation (QAM) constellation.
4. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a 64
QAM constellation.
5. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
256 QAM constellation.
6. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
1024 QAM constellation.
7. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
phase-shift keying (PSK) modulation.
8. The device of claim 1, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using
quadrature phase-shift keying (QPSK) modulation.
9. The device of claim 1, wherein the processing circuitry is
further configured to: generate a second channel sounding symbol
comprising a third subcarrier and a fourth subcarrier, wherein a
third amplitude of the third subcarrier is different than a fourth
amplitude of the fourth subcarrier, wherein the channel sounding
symbol further comprises the second channel sounding symbol.
10. The device of claim 1, wherein the processing circuitry is
further configured to: generate a secure high efficiency long
training field (HEz-LTF) comprising the channel sounding symbol,
wherein the channel sounding symbol further comprises the
HEz-LTF.
11. The device of claim 1, further comprising a transceiver
configured to transmit and receive wireless signals.
12. The device of claim 11, further comprising an antenna coupled
to the transceiver to send the channel sounding signal.
13. A non-transitory computer-readable medium storing
computer-executable instructions which when executed by one or more
processors result in performing operations comprising: generating,
by a first device, a channel sounding symbol comprising a first
subcarrier and a second subcarrier, wherein a first amplitude of
the first subcarrier is different than a second amplitude of the
second subcarrier; generating, by the first device, a channel
sounding signal comprising the channel sounding symbol; and
sending, by the first device, the channel sounding signal to a
second device.
14. The non-transitory computer-readable medium of claim 13,
wherein the channel sounding signal is a null data packet
(NDP).
15. The non-transitory computer-readable medium of claim 13,
wherein generating the channel sounding symbol comprises generating
the channel sounding symbol using a 16 quadrature amplitude
modulation (QAM) constellation.
16. The non-transitory computer-readable medium of claim 13,
wherein generating the channel sounding symbol comprises generating
the channel sounding symbol using a 64 QAM or greater
constellation.
17. The non-transitory computer-readable medium of claim 13,
wherein generating the channel sounding symbol comprises generating
the channel sounding symbol using phase-shift keying (PSK)
modulation.
18. The non-transitory computer-readable medium of claim 13,
wherein generating the channel sounding symbol comprises generating
the channel sounding symbol using quadrature phase-shift keying
(QPSK) modulation.
19. A method comprising: generating, by processing circuitry of a
first device, a channel sounding symbol comprising a first
subcarrier and a second subcarrier, wherein a first amplitude of
the first subcarrier is different than a second amplitude of the
second subcarrier; generating, by the processing circuitry, a
channel sounding signal comprising the channel sounding symbol; and
sending, by the processing circuitry, the channel sounding signal
to a second device.
20. The method of claim 19, wherein generating the channel sounding
symbol comprises generating the channel sounding symbol using a 64
QAM or greater constellation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to and claims priority to U.S.
Provisional Patent Application No. 63/001,237, filed Mar. 27, 2020,
to U.S. Provisional Patent Application No. 63/006,216, filed Apr.
7, 2020, to U.S. Provisional Patent Application No. 63/012,534,
filed Apr. 20, 2020, to U.S. Provisional Patent Application No.
63/021,836, filed May 8, 2020, and to U.S. Provisional Patent
Application No. 63/023,558, filed May 12, 2020, all disclosures
which are hereby incorporated herein by reference in their
entirety.
TECHNICAL FIELD
[0002] This disclosure generally relates to systems and methods for
wireless communications and, more particularly, to enhanced
sounding for secure mode wireless communications.
BACKGROUND
[0003] Wireless devices are becoming widely prevalent and are
increasingly requesting access to wireless channels. The Institute
of Electrical and Electronics Engineers (IEEE) is developing one or
more standards that utilize Orthogonal Frequency-Division Multiple
Access (OFDMA) in channel allocation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a network diagram illustrating an example network
environment, in accordance with one or more example embodiments of
the present disclosure.
[0005] FIG. 2A depicts a schematic diagram for a trigger-based
channel sounding process, in accordance with one or more example
embodiments of the present disclosure.
[0006] FIG. 2B depicts a schematic diagram for a non-trigger-based
channel sounding process, in accordance with one or more example
embodiments of the present disclosure.
[0007] FIG. 3A depicts an illustrative system for a channel
sounding process, in accordance with one or more example
embodiments of the present disclosure.
[0008] FIG. 3B depicts an illustrative system for a channel
sounding process when an attacker exists, in accordance with one or
more example embodiments of the present disclosure.
[0009] FIG. 4A depicts a signal constellation using phase shift
keying, in accordance with one or more example embodiments of the
present disclosure.
[0010] FIG. 4B depicts a signal constellation using quadrature
amplitude modulation, in accordance with one or more example
embodiments of the present disclosure.
[0011] FIG. 5A depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0012] FIG. 5B depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0013] FIG. 5C depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0014] FIG. 5D depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0015] FIG. 5E depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0016] FIG. 5F depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0017] FIG. 5G depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0018] FIG. 6A depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0019] FIG. 6B depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0020] FIG. 6C depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0021] FIG. 6D depicts an example transformation matrix for
enhanced channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0022] FIG. 6E depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0023] FIG. 6F depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0024] FIG. 6G depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0025] FIG. 6H depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0026] FIG. 6I depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0027] FIG. 6J depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0028] FIG. 7 illustrates a flow diagram of illustrative process
for enhanced channel sounding, in accordance with one or more
example embodiments of the present disclosure.
[0029] FIG. 8 illustrates a functional diagram of an exemplary
communication station that may be suitable for use as a user
device, in accordance with one or more example embodiments of the
present disclosure.
[0030] FIG. 9 illustrates a block diagram of an example machine
upon which any of one or more techniques (e.g., methods) may be
performed, in accordance with one or more example embodiments of
the present disclosure.
[0031] FIG. 10 is a block diagram of a radio architecture in
accordance with some examples.
[0032] FIG. 11 illustrates an example front-end module circuitry
for use in the radio architecture of FIG. 10, in accordance with
one or more example embodiments of the present disclosure.
[0033] FIG. 12 illustrates an example radio IC circuitry for use in
the radio architecture of FIG. 10, in accordance with one or more
example embodiments of the present disclosure.
[0034] FIG. 13 illustrates an example baseband processing circuitry
for use in the radio architecture of FIG. 10, in accordance with
one or more example embodiments of the present disclosure.
DETAILED DESCRIPTION
[0035] The following description and the drawings sufficiently
illustrate specific embodiments to enable those skilled in the art
to practice them. Other embodiments may incorporate structural,
logical, electrical, process, algorithm, and other changes.
Portions and features of some embodiments may be included in, or
substituted for, those of other embodiments. Embodiments set forth
in the claims encompass all available equivalents of those
claims.
[0036] In wireless communications defined by the IEEE 802.11
technical standards, the very high throughput (VHT) null data
packet (NDP) Sounding-based 802.11az protocol is referred to as
VHTz, and the high efficiency (HE) null data packet (NDP)
Sounding-based 802.11az protocol is referred to as HEz. In wireless
communications defined by the IEEE 802.11 technical standards, the
very high throughput (VHT) null data packet (NDP) Sounding-based
802.11az protocol is referred to as VHTz, the and high efficiency
(HE) null data packet (NDP) Sounding-based 802.11az protocol is
referred to as HEz. VHTz is based on the 802.11ac NDP and is a
single user sequence, whereas HEz is based on 802.11ax NDP and
802.11az NDP and it supports multiuser operations.
[0037] In IEEE 802.11 communications, channel sounding refers to a
process that allows devices to evaluate radiofrequency (RF)
channels used for wireless communications. The IEEE 802.11
technical standards define processes for devices to exchange
packets, such as NDPs, and use the NDPs to determine channel
characteristics, determine relative device positions, and identify
attempted attacks.
[0038] The 802.11az secure mode considers secure communications to
address new attack models. For example, an attacker listens to the
beginning portion of the sounding symbol used in channel sounding
and detects which sounding signal is being sent. The attacker then
sends the remainder of the sounding signal with a time shift such
that the attacker's "fake" sounding signal arrives at an intended
receiver with a fake channel arrival that is detected at the
intended receiver. In this manner, an attacker may mimic a
transmission from a non-attacker (e.g., "real" device) by sending a
similar transmission to a receiving device, and timing the
reception of the fake transmission to arrive just before the real
transmission is to occur. The fake transmission from the attacker
may result in the receiving device determining that the sender of
the "real" transmission (the non-attacker) is closer to the
receiving device than it actually is, thereby subjecting the
receiving device to security vulnerabilities (e.g., unlocking for
the attacker, etc.). To counter such attack attempts, enhanced
feedback information may be provided from a sounding receiver to a
sounding transmitter to allow for devices to detect attempted
attacks.
[0039] One known solution to detect attacks is for a device to
perform a consistency check on the channels estimated based on
multiple channel soundings within the channel coherence time. A
receiver device can check the power fluctuation in the residual
interference and noise after cancelling out superimposed sounding
signals from a received signal. If there is a significant power
fluctuation, an alert may be triggered so that the ranging security
gets protected.
[0040] Because the attacker may detect which sounding signal is
sent with a small fraction of the sounding signal, some existing
solutions may not detect the attack accurately. Some channel
bandwidth may be wasted due to high false alarm rates (e.g., false
positive attack detections).
[0041] Example embodiments of the present disclosure relate to
systems, methods, and devices for Enhanced Sounding for 802.11az
Secure Mode.
[0042] In one embodiment, an enhanced sounding for secure mode
system may facilitate multiple attack mitigation enhancements. The
first enhancement extends the current constant modulus
constellation (i.e., 8PSK or QPSK) to higher order quadrature
amplitude modulations (QAMs). One solution is to add a magnitude
variation to a sounding signal so that the attacker cannot easily
detect the sounding signal. The second solution extends the
time-domain pulses to time-varying waveforms so that the
information bits of the sounding signal are mixed together in both
the frequency and the time domain. As a result, the attacker cannot
break the search space in either the time or the frequency domain,
and the attacker has to do a joint search in a space prohibitively
large. The present disclosure provides multiple options to make the
sounding signal carry more and more information so that the
attacker cannot detect the sounding signal with a high success
rate. The options may increase the signal mixing or entropy in both
the frequency and time domains so that the attacker cannot use a
frequency-time transformation to reduce the search space.
[0043] In one embodiment, an attack mitigation solution represents
an extension of the 802.11az channel sounding signal. In 802.11az,
each subcarrier of an NDP sounding symbol may have the same
magnitude (e.g., amplitude). The solution to mitigate attempted
attacks may allow magnitude changes across the subcarriers of an
NDP sounding symbol. For example, 16-, 64-, 256-, 1024-, or higher
order QAMs may be used. As a result, not only the number of phases
increases from the 8PSK or QPSK, but also the magnitude carries
additional bits (e.g., 8PSK carries three bits per symbol while
16PSK carries four bits per symbol). Therefore, the entropy of a
sounding signal (e.g., an NDP with one or more sounding symbols)
increases. The selection of the constellation point on each active
subcarrier of an NDP sounding symbol may be determined by the
output bits of a cypher as defined in 802.11az. Even though the
attacker only observes the beginning part of the sounding signal,
the attacker may still perform frequency-domain detection by
converting the time-domain signal to the frequency domain (e.g., by
a windowed Fast Fourier Transform). Because the windowed Fast
Fourier Transform (FFT) introduces inter-subcarrier interference,
the attacker needs some computation power to detect the QAM symbols
on the subcarriers. Other attack mitigation solutions are described
herein.
[0044] In 802.11az, channel sounding may send NDPs having one or
more symbols (e.g., the number of symbols based on the number of
spatial streams used in transmission or based on the number of long
training fields--LTFs--used). The NDP symbols may be preceded in
the NDP by other fields of the NDP, such as an HE-SIG-A field and
an HE-STF field. The magnitude of an NDP symbol included in the
NDP, as currently defined by 802.11az, may not vary from one
subcarrier to another subcarrier. However, to make it more
difficult to execute an attack using sounding signals, the
magnitude may be allowed to vary across the different subcarriers
of an NDP symbol.
[0045] The current HE-LTF defined by the 802.11 standards consists
of a fixed or predefined sequence of BPSK symbols across the active
subcarriers, which are not random. The secure mode of 802.11az
replaces the fixed BPSK symbol sequence with a random 64QAM symbol
sequence. The 802.11az long training field is referred to as
HEz-LTF to be different from the conventional HE-LTF used in
non-secure mode.
[0046] The proposed sounding signals enhance the security of
802.11az. The high complexity of detecting the sounding signal may
deter attacks and protect device and transmission security.
[0047] The above descriptions are for purposes of illustration and
are not meant to be limiting. Numerous other examples,
configurations, processes, algorithms, etc., may exist, some of
which are described in greater detail below. Example embodiments
will now be described with reference to the accompanying
figures.
[0048] FIG. 1 is a network diagram illustrating an example network
environment 100, according to some example embodiments of the
present disclosure. Wireless network 100 may include one or more
user devices 120 and one or more access points(s) (AP) 102, which
may communicate in accordance with IEEE 802.11 communication
standards. The user device(s) 120 may be mobile devices that are
non-stationary (e.g., not having fixed locations) or may be
stationary devices.
[0049] In some embodiments, the user devices 120 and the AP 102 may
include one or more computer systems similar to that of the
functional diagram of FIG. 8 and/or the example machine/system of
FIG. 9.
[0050] One or more illustrative user device(s) 120 and/or AP(s) 102
may be operable by one or more user(s) 110. It should be noted that
any addressable unit may be a station (STA). An STA may take on
multiple distinct characteristics, each of which shape its
function. For example, a single addressable unit might
simultaneously be a portable STA, a quality-of-service (QoS) STA, a
dependent STA, and a hidden STA. The one or more illustrative user
device(s) 120 and the AP(s) 102 may be STAs. The one or more
illustrative user device(s) 120 and/or AP(s) 102 may operate as a
personal basic service set (PBSS) control point/access point
(PCP/AP). The user device(s) 120 (e.g., 124, 126, or 128) and/or
AP(s) 102 may include any suitable processor-driven device
including, but not limited to, a mobile device or a non-mobile,
e.g., a static device. For example, user device(s) 120 and/or AP(s)
102 may include, a user equipment (UE), a station (STA), an access
point (AP), a software enabled AP (SoftAP), a personal computer
(PC), a wearable wireless device (e.g., bracelet, watch, glasses,
ring, etc.), a desktop computer, a mobile computer, a laptop
computer, an ultrabook.TM. computer, a notebook computer, a tablet
computer, a server computer, a handheld computer, a handheld
device, an internet of things (IoT) device, a sensor device, a PDA
device, a handheld PDA device, an on-board device, an off-board
device, a hybrid device (e.g., combining cellular phone
functionalities with PDA device functionalities), a consumer
device, a vehicular device, a non-vehicular device, a mobile or
portable device, a non-mobile or non-portable device, a mobile
phone, a cellular telephone, a PCS device, a PDA device which
incorporates a wireless communication device, a mobile or portable
GPS device, a DVB device, a relatively small computing device, a
non-desktop computer, a "carry small live large" (CSLL) device, an
ultra mobile device (UMD), an ultra mobile PC (UMPC), a mobile
internet device (MID), an "origami" device or computing device, a
device that supports dynamically composable computing (DCC), a
context-aware device, a video device, an audio device, an A/V
device, a set-top-box (STB), a blu-ray disc (BD) player, a BD
recorder, a digital video disc (DVD) player, a high definition (HD)
DVD player, a DVD recorder, a HD DVD recorder, a personal video
recorder (PVR), a broadcast HD receiver, a video source, an audio
source, a video sink, an audio sink, a stereo tuner, a broadcast
radio receiver, a flat panel display, a personal media player
(PMP), a digital video camera (DVC), a digital audio player, a
speaker, an audio receiver, an audio amplifier, a gaming device, a
data source, a data sink, a digital still camera (DSC), a media
player, a smartphone, a television, a music player, or the like.
Other devices, including smart devices such as lamps, climate
control, car components, household components, appliances, etc. may
also be included in this list.
[0051] As used herein, the term "Internet of Things (IoT) device"
is used to refer to any object (e.g., an appliance, a sensor, etc.)
that has an addressable interface (e.g., an Internet protocol (IP)
address, a Bluetooth identifier (ID), a near-field communication
(NFC) ID, etc.) and can transmit information to one or more other
devices over a wired or wireless connection. An IoT device may have
a passive communication interface, such as a quick response (QR)
code, a radio-frequency identification (RFID) tag, an NFC tag, or
the like, or an active communication interface, such as a modem, a
transceiver, a transmitter-receiver, or the like. An IoT device can
have a particular set of attributes (e.g., a device state or
status, such as whether the IoT device is on or off, open or
closed, idle or active, available for task execution or busy, and
so on, a cooling or heating function, an environmental monitoring
or recording function, a light-emitting function, a sound-emitting
function, etc.) that can be embedded in and/or controlled/monitored
by a central processing unit (CPU), microprocessor, ASIC, or the
like, and configured for connection to an IoT network such as a
local ad-hoc network or the Internet. For example, IoT devices may
include, but are not limited to, refrigerators, toasters, ovens,
microwaves, freezers, dishwashers, dishes, hand tools, clothes
washers, clothes dryers, furnaces, air conditioners, thermostats,
televisions, light fixtures, vacuum cleaners, sprinklers,
electricity meters, gas meters, etc., so long as the devices are
equipped with an addressable communications interface for
communicating with the IoT network. IoT devices may also include
cell phones, desktop computers, laptop computers, tablet computers,
personal digital assistants (PDAs), etc. Accordingly, the IoT
network may be comprised of a combination of "legacy"
Internet-accessible devices (e.g., laptop or desktop computers,
cell phones, etc.) in addition to devices that do not typically
have Internet-connectivity (e.g., dishwashers, etc.).
[0052] The user device(s) 120 and/or AP(s) 102 may also include
mesh stations in, for example, a mesh network, in accordance with
one or more IEEE 802.11 standards and/or 3GPP standards.
[0053] Any of the user device(s) 120 (e.g., user devices 124, 126,
128), and AP(s) 102 may be configured to communicate with each
other via one or more communications networks 130 and/or 135
wirelessly or wired. The user device(s) 120 may also communicate
peer-to-peer or directly with each other with or without the AP(s)
102. Any of the communications networks 130 and/or 135 may include,
but not limited to, any one of a combination of different types of
suitable communications networks such as, for example, broadcasting
networks, cable networks, public networks (e.g., the Internet),
private networks, wireless networks, cellular networks, or any
other suitable private and/or public networks. Further, any of the
communications networks 130 and/or 135 may have any suitable
communication range associated therewith and may include, for
example, global networks (e.g., the Internet), metropolitan area
networks (MANs), wide area networks (WANs), local area networks
(LANs), or personal area networks (PANs). In addition, any of the
communications networks 130 and/or 135 may include any type of
medium over which network traffic may be carried including, but not
limited to, coaxial cable, twisted-pair wire, optical fiber, a
hybrid fiber coaxial (HFC) medium, microwave terrestrial
transceivers, radio frequency communication mediums, white space
communication mediums, ultra-high frequency communication mediums,
satellite communication mediums, or any combination thereof.
[0054] Any of the user device(s) 120 (e.g., user devices 124, 126,
128) and AP(s) 102 may include one or more communications antennas.
The one or more communications antennas may be any suitable type of
antennas corresponding to the communications protocols used by the
user device(s) 120 (e.g., user devices 124, 126 and 128), and AP(s)
102. Some non-limiting examples of suitable communications antennas
include Wi-Fi antennas, Institute of Electrical and Electronics
Engineers (IEEE) 802.11 family of standards compatible antennas,
directional antennas, non-directional antennas, dipole antennas,
folded dipole antennas, patch antennas, multiple-input
multiple-output (MIMO) antennas, omnidirectional antennas,
quasi-omnidirectional antennas, or the like. The one or more
communications antennas may be communicatively coupled to a radio
component to transmit and/or receive signals, such as
communications signals to and/or from the user devices 120 and/or
AP(s) 102.
[0055] Any of the user device(s) 120 (e.g., user devices 124, 126,
128), and AP(s) 102 may be configured to perform directional
transmission and/or directional reception in conjunction with
wirelessly communicating in a wireless network. Any of the user
device(s) 120 (e.g., user devices 124, 126, 128), and AP(s) 102 may
be configured to perform such directional transmission and/or
reception using a set of multiple antenna arrays (e.g., DMG antenna
arrays or the like). Each of the multiple antenna arrays may be
used for transmission and/or reception in a particular respective
direction or range of directions. Any of the user device(s) 120
(e.g., user devices 124, 126, 128), and AP(s) 102 may be configured
to perform any given directional transmission towards one or more
defined transmit sectors. Any of the user device(s) 120 (e.g., user
devices 124, 126, 128), and AP(s) 102 may be configured to perform
any given directional reception from one or more defined receive
sectors.
[0056] MIMO beamforming in a wireless network may be accomplished
using RF beamforming and/or digital beamforming. In some
embodiments, in performing a given MIMO transmission, user devices
120 and/or AP(s) 102 may be configured to use all or a subset of
its one or more communications antennas to perform MIMO
beamforming.
[0057] Any of the user devices 120 (e.g., user devices 124, 126,
128), and AP(s) 102 may include any suitable radio and/or
transceiver for transmitting and/or receiving radio frequency (RF)
signals in the bandwidth and/or channels corresponding to the
communications protocols utilized by any of the user device(s) 120
and AP(s) 102 to communicate with each other. The radio components
may include hardware and/or software to modulate and/or demodulate
communications signals according to pre-established transmission
protocols. The radio components may further have hardware and/or
software instructions to communicate via one or more Wi-Fi and/or
Wi-Fi direct protocols, as standardized by the Institute of
Electrical and Electronics Engineers (IEEE) 802.11 standards. In
certain example embodiments, the radio component, in cooperation
with the communications antennas, may be configured to communicate
via 2.4 GHz channels (e.g. 802.11b, 802.11g, 802.11n, 802.11ax), 5
GHz channels (e.g. 802.11n, 802.11ac, 802.11ax), or 60 GHZ channels
(e.g. 802.11ad, 802.11ay, 802.11az). 800 MHz channels (e.g.
802.11ah). The communications antennas may operate at 28 GHz and 40
GHz. It should be understood that this list of communication
channels in accordance with certain 802.11 standards is only a
partial list and that other 802.11 standards may be used (e.g.,
Next Generation Wi-Fi, or other standards). In some embodiments,
non-Wi-Fi protocols may be used for communications between devices,
such as Bluetooth, dedicated short-range communication (DSRC),
Ultra-High Frequency (UHF) (e.g. IEEE 802.11af, IEEE 802.22), white
band frequency (e.g., white spaces), or other packetized radio
communications. The radio component may include any known receiver
and baseband suitable for communicating via the communications
protocols. The radio component may further include a low noise
amplifier (LNA), additional signal amplifiers, an analog-to-digital
(A/D) converter, one or more buffers, and digital baseband.
[0058] In one embodiment, and with reference to FIG. 1, the AP 102
and/or the user devices 120 may exchange sounding frames 142 (e.g.,
NDPs, NDPAs, trigger frames, etc.) and measurement reports 144
(e.g., LMRs) as shown in FIGS. 2A and 2B. The sounding frames 142
and LMRs 144 may be used in channel sounding operations as
explained further herein.
[0059] It is understood that the above descriptions are for
purposes of illustration and are not meant to be limiting.
[0060] FIG. 2A depicts a schematic diagram for a trigger-based
channel sounding process 200, in accordance with one or more
example embodiments of the present disclosure. In IEEE 802.11
communications, channel sounding refers to a process that allows
devices to evaluate radiofrequency (RF) channels used for wireless
communications. The IEEE 802.11 technical standards define
processes for devices to exchange packets, such as NDPs, and use
the NDPs to determine channel characteristics, determine relative
device positions, and identify attempted attacks.
[0061] Referring to FIG. 2A, an AP 202 may perform trigger-based
channel sounding with an STA 204 and an STA 206, in accordance with
the IEEE 802.11 standards. The AP 202 may send a trigger frame (TF)
208 (e.g., a frame that indicates to addressed devices are to send
responses to the AP 202). In response to receiving the TF 208, the
STA 204 may send an uplink (UL) NDP 210, and the STA 206 may send a
UL NDP 212 as part of the channel sounding process (e.g., an NDP
may lack a payload). Once the AP 202 has received the UL NDPs 210
and 212, the AP 202 may announce that it also will sound the
channel by sending an NDP-announcement (NDPA) 214 frame announcing
that a downlink NDP 216 is to be transmitted, and then transmitting
the DL NDP 216. Based on the DL NDP 216, the STAs 204 and 206 both
may determine CSI and other channel information, and may generate
and send LMRs to the AP 202 (e.g., the STA 204 may generate and
send LMR 218, and the STA 206 may generate and send LMR 220). For
example, the LMRs 218 and 220 may include the respective ToA of the
DL NDP 216 at the STA 204 and the STA 206, along with the ToDs and
the PS of the UL NDP 210 and 212. The AP 202 may generate and send
LMR 222 to the STAs 204 and 206, the LMR 222 including the ToAs of
the UL NDPs 210 and 212, and the ToD and PS of the DL NDP 216 (or a
previously sent DL NDP).
[0062] FIG. 2B depicts a schematic diagram for a non-trigger-based
channel sounding process 250, in accordance with one or more
example embodiments of the present disclosure. FIG. 2B refers to a
sounding process similar to that in FIG. 2A, but without requiring
a trigger frame.
[0063] Referring to FIG. 2B, an AP 252 may perform trigger-based
channel sounding with an STA 254 and an STA 256, in accordance with
the IEEE 802.11 standards. The AP 252 may send an NDPA 258 to
announce the sending of a DL NDP 260, and may send the DL NDP 260.
The STAs 254 and 256 may receive the DL NDP 260 and respond by
sending UL NDPs (e.g., the STA 254 may send UL NDP 262, and the STA
256 may send UL NDP 264). After exchanging UL and DL NDPs, the AP
252 and the STAs 254 and 256 may generate and send respective LMRs.
The STA 254 may send LMR 266, the STA 256 may send LMR 268, and the
AP 252 may send LMR 270. The LMRs may include ToAs of frames
received, ToDs of frames sent, and PS of frames sent by the
respective device sending the LMR.
[0064] FIG. 3A depicts an illustrative system 300 for a channel
sounding process, in accordance with one or more example
embodiments of the present disclosure.
[0065] Referring to FIG. 3A, the system 300 may include multiple
devices (e.g., STA 1, STA 2) performing channel sounding. For
example, the STA 2 may send a first sounding signal 302 and a
second sounding signal 304 (e.g., NDPs as shown in FIGS. 2A and
2B). The second sounding signal 304 may reflect off of object 306
(e.g., an object or person), resulting in a different ToA than the
ToA of the first sounding signal 302 at STA 1. As shown in FIG. 3A,
the first arrival at STA 1 may be the ToA of the first sounding
signal 302, and the second arrival at STA 1 may be the ToA of the
second sounding signal 304. As shown, the magnitude of the first
sounding signal 302 may be greater than the magnitude of the second
sounding signal 304 (e.g., because the second sounding signal 304
reflected off of the object 306, which may be further away from STA
1 than is STA 2).
[0066] While not shown, the process may be bidirectional, in which
case STA 1 may send sounding signals to STA 2 similar to the first
sounding signal 302 and the second sounding signal 304, using the
same paths, but in the opposite direction. The channel responses at
both STAs should be the same, allowing for the STAs to determine
whether any ToA is fake and likely generated by an attacker as
shown in FIG. 3B.
[0067] FIG. 3B depicts an illustrative system 350 for a channel
sounding process when an attacker exists, in accordance with one or
more example embodiments of the present disclosure.
[0068] Referring to FIG. 3B, the system 350 may include multiple
devices (e.g., STA 1, STA 2) performing channel sounding. An
attacker device 352 with an oscillator 354 may attempt to replicate
sounding signals sent by STA 2, which may have an oscillator 356.
For example, the STA 2 may send a first sounding signal 358 and a
second sounding signal 360 (e.g., NDPs as shown in FIGS. 2A and
2B). The second sounding signal 360 may reflect off of object 361
(e.g., an object or person), resulting in a different ToA than the
ToA of the first sounding signal 358 at STA 1. The attacker device
352 may receive a third sounding signal 362 from STA 2 and may
replicate the third sounding signal 362 by sending a fourth
sounding signal 364 and a fifth sounding signal 366, intended to
arrive at STA 1 before the first sounding signal 358 and the second
sounding signal 360.
[0069] Still referring to FIG. 3B, the estimated channel response
in the forward direction (e.g., from STA 2 to STA 1) may include a
fake first arrival (e.g., the ToA of the fourth sounding signal
364), a fake second arrival (e.g., the ToA of the fifth sounding
signal 366), a true first arrival (e.g., the ToA of the first
sounding signal 358), and a true second arrival (e.g., the ToA of
the second sounding signal 360. The fifth sounding signal 366 may
arrive at STA 1 later than the fourth sounding signal 364 (e.g.,
because it may reflect off of an object 363), but before the second
sounding signal 360 to perpetrate an attack. Similarly, the fourth
sounding signal 364 may arrive at STA 1 before the first sounding
signal 358 to perpetrate an attack.
[0070] It is difficult for the attacker device 352 to generate the
same fake multipaths in bidirectional soundings as the sounding
signals sent by STA 1 and STA 2 such that the phases, delays, and
amplitudes relative to the true multipaths are the same in both
directions. To generate the same fake multipaths in both
directions, the attacker device 352 needs the perfect calibration
of the transmit and receive chains, the perfect synchronization to
the intended transmitter clock (e.g., via the oscillator 354), the
fine resolution detection of the multipaths in the received signal,
and the knowledge of the randomized sounding signal. Among the
difficulties, the synchronization needs to occur at the phase level
not frequency level. The fine resolution multipath detection is
also very challenging. Small multipaths need to be detected in the
presence of the interferences from the strong multipaths.
Furthermore, the attacker device 352 usually needs some time to
analyze the beginning part of the received signal (e.g., the third
sounding signal 362) so that the attacker device 352 can detect
which sounding signal is being sent, and then sends the remaining
part of the sounding signal with a time shift (e.g., the fourth
sounding signal 364 and the fifth sounding signal 366). Therefore,
the attacker's sounding signal for generating the fake first
arrival is usually incomplete. Provided the difficulties, there are
mismatches in channel responses estimated from the two directions
as shown in FIG. 3B.
[0071] The mismatched responses (e.g., in the forward and reversed
directions) in FIG. 3B may be used by the STAs to detect the attack
and trigger an alert. In the measure report of current 11az secure
mode, only {time of arrival (ToA), time of departure (ToD)} or
{ToD, phase shift (PS)} are sent. There is no amplitude and phase
information about the individual multipaths or the overall picture
of the multipaths.
[0072] FIG. 4A depicts a signal constellation 400 using phase shift
keying, in accordance with one or more example embodiments of the
present disclosure.
[0073] Referring to FIG. 4A the constellation 400 shown is an 8PSK
(phase shift keying) constellation in which each phase (e.g.,
angle) has the same amplitude A.
[0074] FIG. 4B depicts a signal constellation 450 using quadrature
amplitude modulation, in accordance with one or more example
embodiments of the present disclosure.
[0075] Referring to FIG. 4B the constellation 450 shown is an 64QAM
(quadrature amplitude modulation) constellation in which the
different phases have different amplitudes (e.g., distances from
the 0,0 origin of the axes).
[0076] While FIG. 4A and FIG. 4B represent different
constellations, other modulation and phase shift keying techniques
may correspond to different constellations.
[0077] FIG. 5A depicts an example technique 500 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0078] Referring to FIG. 5A, the technique 500 represents an
extension of the 802.11az sounding signal. In 802.11az, the symbol
on each subcarrier may have the same magnitude (e.g., amplitude).
The magnitude changes may be allowed across the subcarriers. For
example, 16-, 64-, 256-, 1024-, or higher order QAMs may be used
(e.g., FIG. 4B) for modulation of the sounding signal. As a result,
not only the number of phases increases from the 8PSK or QPSK, but
also the magnitude carries additional bits. Therefore, the entropy
of the sounding signal increases. The selection of the
constellation point on each active subcarrier may be determined by
the output bits of a cypher like the current 802.11az.
[0079] In one or more embodiments, even though an attacker may only
observe the beginning part of the sounding signal, the attacker may
perform frequency-domain detection by converting the time-domain
signal to frequency domain (e.g., by a windowed FFT). Because the
windowed FFT introduces inter-subcarrier interference, the attacker
needs some computation power to detect the QAM symbols on the
subcarriers. However, the inter-subcarrier interference reduces as
the window size increases. The attacker may be able to detect most
of the QAM symbols after observing 80-90% of sounding signal, for
example, and may generate an attack signal in the remaining 10-20%
sounding time.
[0080] A signal's peak to average power ratio (PAPR) is relevant in
channel sounding. In particular, a large PAPR may not be optimal
for channel sounding, as a time-domain signal peak may be clipped,
resulting in noise, bit error, and interference, thereby causing a
distorted channel estimation. Data packets, such as sounding NDPs,
may use 64QAM, which may experience a high PAPR. In this manner, by
using higher order QAMs to vary amplitude, the sounding signal may
be more difficult for an attacker to identify and copy, but with
some risk of signal peak clipping and distorted channel estimation.
Current channel sounding packets do not vary the signal amplitude
with higher order QAMs in part because of the distortion risk.
[0081] In one or more embodiments, a long training field (LTF) of a
sounding signal (e.g., the UL NDP 210 of FIG. 2A, the UL NDP 212 of
FIG. 2A, the DL NDP 216 of FIG. 2A, DL NDP 260 of FIG. 2B, the UL
NDP 262 of FIG. 2B, the UL NDP 264 of FIG. 2B) may be generated to
include a sequence for secure mode communications. There may be 122
non-zero entries in the 20-MHz secure 2.times.LTF sequence. The
mapping of pseudo random octets may be to the non-zero entries of
the 20-MHz secure 2.times.LTF sequence, and then the 64-QAM values
for each non-zero entry of the secure LTF sequence may be
constructed. There may be up to 64.sup.122 secure LTF sequences
available to be selected in an NDP for 20-MHz secure 2.times.LTF,
as there are up to eight repetitions and up to eight secure LTF
sequences within a repetition. For notational convenience each
entry of the LTF sequence may be indicated with the integer k,
which is an integer between zero and sixty three. A table may
provide the pseudo random octet index for each nonzero subcarrier
index in the secure LTF sequence. All entries in the secure LTF
sequence other than the non-zero entries shall be set to zero. The
six least significant bits (B0,B1,B2,B3,B4,B5) of an octet, taking
values from zero to sixty three, are used in the construction of
the 64-QAM value for a 20-MHz secure sounding NPD, a 40-MHz secure
sounding NDP, an 80-MHz secure sounding NDP, and a 160-MHz secure
sounding NDP.
[0082] The current HE-LTF defined by the 802.11 standards consists
of a fixed or predefined sequence of BPSK symbols across the active
subcarriers, which are not random. The secure mode of 802.11az
replaces the fixed BPSK symbol sequence with a random 64QAM symbol
sequence. The 802.11az long training field is referred to as
HEz-LTF to be different from the conventional HE-LTF used in
non-secure mode.
[0083] FIG. 5B depicts an example technique 520 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0084] Referring to FIG. 5B, to address a possible attack signal,
time domain pulses 522 independent in time may be used as
illustrated. Because the polarity or phase and/or magnitude of each
pulse may be independent of the others, the attacker may not obtain
any information about the current part of the sounding signal by
analyzing a previous part of the sounding signal.
[0085] However, there may be limited choices for the time limited
pulses 522. For example, one option is the pulse being generated by
setting all the active subcarriers to be the same value (e.g., 1).
The shape of this pulse may be close to a rectangle. The
corresponding sounding signal (i.e., a sequence of pulses) may
experience very little inter-pulse interference in the time domain.
The attacker can detect the polarity or phase or magnitude of the
pulse by analyzing the beginning part of pulse and generate an
attack signal attacking the remaining part. For a 20 MHz sounding
signal, the rectangular pulse width is about 50 ns. The attacker
can generate a fake arrival ahead of the actual ones by 20 ns (i.e.
7 meters) if the receiver device does not have an attack detection
mechanism. For time limited pulses other than the rectangle, the
attacker can use a Viterbi algorithm to detect the polarity or
phase or magnitude of the pulse by observing the beginning part of
the pulse.
[0086] FIG. 5C depicts an example technique 530 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0087] Referring to FIG. 5C, to address an attack on a time limited
pulse, strong inter-signal interference may need to be introduced
as illustrated in FIG. 5C. Instead of a time limited pulse, a
reference signal may have the duration the same as the sounding
signal. The reference signal may be generated from the QAM symbols
in the frequency domain the same way as the legacy OFDM symbol. The
QAM symbols may be determined by the output bits of a cypher like
the current 802.11az. The sounding signal consists of the reference
signal and its (cyclically) shifted copies that may have different
polarities or phases or/and magnitudes as illustrated in FIG. 5C.
Namely, the time limited pulse in FIG. 5B may be replaced by the
reference signal in FIG. 5C. The polarity or phase or magnitude of
the shifted signals may be determined by the output bits of a
cypher.
[0088] To make the system even more secure, instead of using
shifted copies of the same reference signal, different reference
signals may be used in FIG. 5C. Namely, the sounding signal
consists of the superimposition of different reference signals.
Each reference signal may be generated from a different set of QAM
symbols in frequency domain. A different (cyclic) shift may be
applied to each reference signal.
[0089] In general, the solution in FIG. 5C makes the sounding
signal look like Gaussian signal in both time and frequency
domains, which maximizes the entropy of each sample in time and
frequency so that the attacker has a hard time to detect the
sounding signal.
[0090] FIG. 5D depicts an example technique for enhanced channel
sounding, in accordance with one or more example embodiments of the
present disclosure.
[0091] Referring to FIG. 5D, this option is the simplest extension
of the existing solution in 802.11az secure mode. One possibility
is using a fully random QPSK sequence to replace the 8PSK Golay
sequence in 802.11az secure mode. Since the constellation points
are denser in 8PSK than QPSK, the fully random 8PSK sequence is
more secure than fully random QPSK sequence. It increases the
entropy of the sounding signal and thus makes the attacker harder
to detect the transmitting sounding signal. To enhance the
security, 8PSK or 16PSK or higher order PSK constellation may be
used for the secure mode. The PSK constellation has the same
magnitude that sounds each active subcarrier with the same power.
This makes the consistency check across the repeated soundings more
stable than using a constellation with multiple magnitudes like
16QAM.
[0092] There are two ways to enhance the existing 802.11az secure
mode. First, fully random 8PSK or 16PSK or higher order PSK
sequences may be used to replace the existing 8PSK Golay sequences.
For the fully random PSK sequence, the PSK symbols of the sequence
are independently specified by the encryption bits, which are
generated by a cypher using some exchanged parameters or are
received from the other ranging party. Second, instead of replacing
the Golay sequence by a fully random sequence, the Golay structure
of 11az may be reused, but increase the constellation from 8PSK to
a higher order PSK (e.g., 16PSK or 32PSK). The second method
maintains the Golay structure so that the peak to average power
ratio (PAPR) of the sounding signal in time domain is smaller than
those of the fully random sequences. The smaller PAPR enables a
higher transmission power and a longer working range for
802.11az.
[0093] FIG. 5E depicts an example technique 550 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0094] Referring to FIG. 5E, the transformation from the encryption
bits to the sounding signal should be unknown to the attacker so
that it is hard for the attacker to detect the encryption bits by
observing part of the sounding signal. The modulation like OFDM and
direct sequence spread spectrum (DSSS), and the QAM mapping like
Grey mapping, may be transformations known to the attacker. It may
be beneficial to have a transformation unknown to the attacker as
illustrated in FIG. 5E.
[0095] FIG. 5F depicts an example technique 560 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0096] Referring to FIG. 5F, to reuse the existing components in a
transceiver, it may be beneficial to add a transformation before
the inverse fast Fourier transform (IFFT) in FIG. 5F, which is
unknown to the attacker, as illustrated in FIG. 5G.
[0097] FIG. 5G depicts an example technique 570 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0098] In FIG. 5G, the transformation M is unknown to the attacker
and may be changed for each sounding or each measurement. It is
desirable that each element of the output vector of the
transformation M should be determined jointly by all the encryption
bits at the input vector. As a result, the attacker has to detect
the encryption bits jointly instead of a divide-and-conquer
fashion. The transformation M may be linear or non-linear. If it is
non-linear, the operations of permutation and replacement may be
applied. The input of M may be of N symbols each with a small
alphabet e.g. QPSK or 16QAM and the output of M may be of L symbols
each with a large alphabet whose size is desired to be an
exponential (or quadratic or cubic function of N). For simplicity,
N may be equal to L. Similarly, for simplicity, M may be linear as:
x=s, (1) where s is the input symbol vector; and x is the output
symbol vector. For even power distribution, M may be a unitary
matrix, whose columns (or rows) are orthogonal with each other. In
addition, the norms of the columns (or rows) of M may be the same.
For example, a discrete Fourier transform (DFT_matrix is a unitary
matrix. For another example, a rotation matrix is a unitary matrix.
In fact, a unitary matrix can be viewed as a rotation matrix. The
unitary matrix can be parametrized in various ways such as the
Givens angles in 802.11n/ac/ax and the Householder vectors in the
802.16e/m technical standard.
[0099] FIG. 6A depicts an example technique 600 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0100] Referring to FIG. 6A, because the attacker may learn the
transformation M after listening to the soundings, the
transformation M needs to vary with soundings. For example, it may
be beneficial to have a large set of M matrixes such that the
attacker may not know which of them is used for a specific
sounding. As illustrated in FIG. 6A, the parameters of the
transformation M may be determined by some of the encryption bits.
The output of M are controlled by two parts, the input symbols and
the parameters of M as illustrated in FIG. 6A. If the dimension of
M is large enough e.g. greater than 100 or if the set of M is large
enough, the input symbols may be fixed e.g. [1, 0, . . . 0] or [1,
. . . 1] i.e. carrying no information for simplicity because the
parameters of M already carry enough entropy for security
protection. If a fixed input vector [1, 0, . . . 0] is used, the
output vector is essentially the first column of M. Namely, the
other columns of M are not used for the security protection. For
the example of 802.11az sounding with 20 MHz bandwidth, there are
128 subcarriers. The matrix M can be 128 by 128. It can be
parameterized by 16,256 Givens angles, whose ranges are (0,2.pi.]
and [0, .pi./2], respectively. Similar to the compressed feedback
of 802.11n/ac/ax, the encryption bits can specify the Givens
angles. If a higher security level is required, some encryption
bits may be used to specify the various input symbols for the input
vector s in Equation (1) above. For example, BPSK or QPSK symbols
may be specified by the encryption bits.
[0101] A simplified way to generate a large set of M matrixes is
permutation. The rows and/or the columns of a specific M matrix can
be permuted to generate different M matrixes. The encryption bits
specify the permutation of the M matrix. This technique is
equivalent to permuting the elements of the input vector s before
applying the transformation and then permuting the elements of the
output vector x. Since the elements of the M matrix just move to
other positions instead of changing to other values, the security
protection level is not as high as the methods that change the
values of the elements.
[0102] The matrix M in FIGS. 5G and 6A is of N by P, where N is the
number of subcarriers (or active subcarriers) and P is the number
of QAM symbols to be mixed together. Note that, P is not
necessarily to be equal to N for reducing the complexity. For large
bandwidths, the size of M is large e.g. 1024 and the matrix
multiplications are of high complexities. For a low complexity,
special matrixes with structures may be used as the matrix M e.g.
binary matrix, FFT (or IFFT) matrix, and Hadamard matrix such that
the complexity of the matrix multiplication is low. For example,
the binary matrix with 1s and -1s only involve sign and addition
operations. For another example, QPSK matrix with {1, -1, j, -j }
or {.+-.1.+-.j} also only involve sign and addition operations. For
a third example, the complexity of the FFT (or IFFT) matrix
multiplication is O(N log N), which is lower than O(N.sup.2). In
addition, the existing hardward for FFT (or IFFT) can be reused.
Since the special matrix may be known to the attacker, some
operations unknown to the attacker may need to be added after the
matrix multiplication for further protecting the security. Two
options are listed next.
[0103] FIG. 6B depicts an example technique 620 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0104] Referring to FIG. 6B, the technique 620 is a special case
for the technique 600 of FIG. 6A. After the matrix multiplication
with M, the elements in the output vector x in Equation (1) above
are permuted. For low complexity, the permutation may be constant
and thus may be known to the attacker. For high security, the
permutation varies so that it is unknown to the attacker. The total
number of permutation combinations is N!, where N is the number of
subcarriers (or active subcarriers). The complexity is prohibitive
for the attacker to search for the permutation being used in a
sending signal. For a simple implementation of the permutation,
block interleavers may be used. A block interleaver may read in
data symbols sequentially and fill out the rows of the interleaver
row by row. When the data is read out, the data are read out column
by column such that the symbol order is different from the one when
the symbols are read in. The rows or columns do not need to be
fully filled.
[0105] In the existing 802.11 system, interleavers are widely used.
A parser may be added before the interleavers. The parser
distributes input bits to different interleavers and then each
interleaver permutes the bits distributed to the interleaver. The
interleaved bits at the output of the interleavers are finally
concatenated as the interleaved bits of the overall interleaving
process. This idea can be reused here.
[0106] In FIG. 6B, some examples of interleaver are illustrated. In
the top portion FIG. 6B, two block interleavers are used. The
number of block interleavers is limited when a single block
interleaver is used for the whole permutation. For example, for
N=128, there are only less than 128 block interleavers such that
the attacker may be able to use brute force search to find the
interleaver being used. To increase the number of permutations,
multiple block interleavers may be used. In the top portion FIG.
6B, two interleavers are serially concatenated. The total number of
permutations is then multiplied e.g. close to N.times.N. For high
security, more than two block interleavers can be used. In the
bottom portion FIG. 6B, an example using a parser and interleavers
is illustrated. The elements of input vector x are first
interleaved and parsed. The parsed elements are distributed to
multiple interleavers, respectively. The elements distributed to
each interleaver are interleaved and the interleaved elements from
the interleavers are concatenated for the next step. For
simplicity, the first interleaver with parameters (L1, K1) may be
not used, i.e. no interleaving before parsing, where L1 and K1 are
the numbers for rows and columns of the block interleaver,
respectively. The number of permutations is multiplied by choosing
different block interleaver parameters i.e. L.sub.is and
K.sub.is.
[0107] The permutation operation can be included in the matrix
multiplication of Equation (1) above by permuting the rows of
M.
[0108] FIG. 6C depicts an example technique 630 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0109] Referring to FIG. 6C, instead of permutation, masking can be
used to protect the security. It may be desired to prevent the
attacker from seeing the individual encryption symbols in both time
and frequency domains. For example, 802.15.4z UWB ranging sends
individual time domain pulses sequentially, where the pulses are
not interfered with each other. The attacker can predict the ending
part of the pulse by detecting the beginning parting of the pulse
without the interference from the other pulses. For another
example, OFDM modulation sends individual frequency domain QAM
symbols, where the QAM symbols do not interfere with each other.
The individual signals in the two examples have low entropies such
that the attacker can detect them reliably. It may be desirable
that the attacker always observes mixed signals with high entropies
in both the time and frequency domain.
[0110] In FIG. 6C, encryption bits generate two sets of the
symbols. One is the QAM symbols to be mixed by the matrix M. The
other is the sequence of masking symbols, which are multiplied with
the mixed symbols in vector x of (1), respectively. For simplicity,
the masking symbols may be of BPSK or QPSK e.g. {+1, -1} or {1, -1,
j, -j}, or {1+j, 1-j, -1+j, -1-j} such that the masking operation
only involves sign (and addition) operation. The encryption bits in
FIG. 6C can be generated by a cypher like in the 802.11az standard.
In one embodiment, the M matrix is the FFT matrix.
[0111] The options aforementioned can be jointly used together. For
the ease of implementation, the number of the rows of matrix M may
be a power of 2 (e.g., 128 and 1024). Some subcarriers may be
reserved for DC, edges, and/or pilots. Therefore, if the number of
the permuted or masked symbols (e.g., 128) is greater than that of
the subcarriers available for carrying the secure sounding signal
(e.g., 118), some permuted or masked symbols may not be used (i.e.,
not mapped to the subcarriers).
[0112] FIG. 6D depicts an example transformation matrix 640 for
enhanced channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0113] The mixing of the encryption bits or symbols in FIGS. 5G and
6A preferably may be unknown to the attacker. In FIGS. 6B and 6C,
permutation and scrambling are used such that the transformation M
in FIG. 5G is unknown to the attacker and the transformation M
remains a rotation matrix i.e. a unitary matrix. For the ease of
implementation, the encryption symbols may be mixed by a filter.
The filter can be linear or nonlinear. For linear filters, finite
impulse response (FIR) or infinite impulse response (IIR) can be
used. Although the linear filters can be implemented in the form of
the transformation matrix M as illustrated in FIG. 6D, the
conventional delay taps are of a low complexity. Namely, the
encryption symbols carrying the encryption bits are passed through
a linear filter with registers to get mixed signals at the output
of the filter. For FIR filters, the larger the number of taps the
securer of the system. For IIR filters, the number of taps may not
need to be large, but the precision requirement may need to be
high. Otherwise, the cumulative errors at the end of the output can
be large. Both linear filters may need initialization and
termination. The registers may be initialized by all zeros. Or, the
input symbols to the filters may be treated in a circular or wrap
around fashion. For example, the beginning and the end of the input
symbols are connected with each other such that the input symbols
form a loop. The symbols at the end can be used for the
initialization of the beginning ones. For simplicity, the filter
taps may be chosen from a finite (or structured) alphabet for a low
complexity. For example, the alphabet may be {+1,-1} or {1+j, -1+j,
1-j, -1-j}, which may not incur real multiplications in the filter
operation.
[0114] In one or more embodiments, the transformation matrix 640
(M) for linear filters may have a Toeplitz structure.
[0115] When the attacker observes the beginning portion of the
sounding signal and converted the observed signal into frequency
domain. The windowed FFT introduces inter-carrier interferences. It
is similar to applying a FIR filter, which is the spectrum of the
windowing function, to signals on each subcarrier. If the window
size is a quarter of the sounding signal, the number of significant
taps of the FIR filter is about 11, which is not a large number for
the attacker to break the system. Additional filter taps may be
introduced, which expands the taps due to the windowing, by the
sounding transmitter. This makes it difficult for the attacker to
break the system.
[0116] FIG. 6E depicts an example technique 650 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0117] The encryption bits or symbol mixing in FIGS. 5G, 6A, 6C,
and 6D may cause unequal sounding powers across frequency as
illustrated in FIG. 6E. For a specific sounding, some subcarriers
may not have enough sounding signal power. This may reduce the
accuracy of channel estimation or time of arrival (ToA) estimation.
In addition, different soundings for the same channels may have
different sounding power profiles across frequency. This may affect
the consistency check used by attack detection.
[0118] To mitigate the problem, the magnitude range of the sounding
signal on the subcarriers may be limited. For example, a minimum
limit can be set. If the sounding signal on a subcarrier is below
the limit, the signal is boosted to the minimum limit. Similarly, a
maximum limit can be set. If the sounding signal on a subcarrier is
above the limit, the signal is caped to the maximum limit. Since
the limits may be known to the attacker, it is desirable that the
magnitude outside the range limits is mapped to a value inside the
range limits not always at the limits. For example, mod operation
may be used as Equation (2):
a.sub.out=a.sub.MIN+mod(a.sub.in-a.sub.MIN, a.sub.MAX-a.sub.MIN),
(2)
where a.sub.in and a.sub.out are input and output magnitudes,
respectively; a.sub.MAX and a.sub.MIN are the upper and lower
limits of the magnitudes, respectively.
[0119] In another mitigation option, the encryption bits or symbols
mixing in FIGS. 5G, 6A, 6C, and 6D may cause unequal sounding
powers across frequency as illustrated in FIG. 6E. For a specific
sounding, some subcarriers may not have enough sounding signal
power. This may reduce the accuracy of channel estimation or time
of arrival (ToA) estimation. In addition, different soundings for
the same channels may have different sounding power profiles across
frequency. This may affect the consistency check used by attack
detection.
[0120] For constant sounding power across frequency, high order PSK
signal (e.g. 16PSK and higher PSK) may be used. For low order PSK
signals (e.g. 8PSK), the attacker may observe the beginning part
(e.g. 1/4 of the sounding signal) and use Viterbi equalizer in the
frequency domain to detect the transmitting signals on each
subcarrier so that the attacker can regenerate the sounding signal
with a time shift. For security, randomized phase rotations may be
applied to the PSK symbols on the subcarriers, respectively. The
randomized phase rotation is unknown to the attacker but known to
the intended receiver. The rotated phases may be determined part of
the encryption bits.
[0121] To further increase the sounding signal entropy, the phase
of each subcarrier may be jointly determined by all or a large
portion of the encryption bits. For example, the ideas in the
previous options can be reused. The symbol vector in Equation (1)
and the QAM symbols in FIGS. 5G-6C can be replaced by angle vector
or angles. The angles are determined by the encryption bits. For
example, the two encryption bits selects one angle out of {0
degree, 90 degrees, 180 degrees, 270 degree}. The angles picked
from a finite alphabet are then transformed by mixing and/or
scrambling. For the ease of implementation, Hadamard matrix, FFT
matrix, IFFT matrix, or linear filters may be used for the mixing.
After the transformation, some output angles may be removed for
accommodating the DC and edge subcarriers and the remaining are
used as the phases for the active subcarriers in the sounding.
[0122] As compared with the other options whose signal magnitude
can vary across subcarriers, the security level of this option is
reduced due to the entropy reduction in magnitude.
[0123] FIG. 6F depicts an example technique 660 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0124] In one mitigation option, high order QAM is used for the
ease of implementation. However, since the attacker knows the
constellation, the attacker can observe the beginning part of the
sounding signal and detect the QAM symbols e.g. using Viterbi
equalizer and sphere decoder in frequency domain. To make the
detection difficult for the attacker, the constellation of each
subcarrier can be changed. For example, it can be rotated by an
angle, which may be unknown to the attacker. An example is shown in
FIG. 6F. Since the original QAM constellation is symmetric about
real axis, imaginary axis, and the origin, the rotation angles can
be chosen from (0 degree, 90 degrees] or [0 degree, 90 degrees).
For example, {0, .pi./4}, {0, .pi./8, .pi./4, 3.pi./8}, or n.pi./N
for n =0, 1, . . . , .left brkt-top.N/2.right brkt-bot.-1. For each
active subcarrier, some of the encryption bits select the
constellation point from the constellation and some encryption bits
select the rotation. Since the attacker only know the constellation
but doesn't know the rotation angle, the attacker has to search the
constellations for all the angles. For the example in FIG. 6F, the
eight constellation points from the two constellations are the
increased search space. This increases the search space and reduces
the success rate of the attack.
[0125] FIG. 6G depicts an example technique 670 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0126] Referring to FIG. 6G, it is desirable that the previous
portion of a sounding signal does not provide information about the
remaining portion of the sounding signal so that the attacker
cannot learn from the previous portion to predict the remaining
portion. From this perspective, time domain pulses with a limited
pulse duration are an option. However, if the pulse duration is
long and the pulse shape is known to the attacker, the attacker can
send the ending portion of the pulse with a time advancement by
detecting the beginning of the pulse. Therefore, it may be
beneficial to either to reduce the pulse duration or to make the
pulse shape unknown to the attacker. Increasing the sounding signal
bandwidth can reduce the pulse duration. However, for a given 20
MHz bandwidth whose pulse duration is longer than 50 ns, the pulse
shape may need to be unknown to the attacker.
[0127] For generating different pulses unknown to the attacker, a
delta function or reference pulse is passed through a filter as
illustrated in FIG. 6G. In FIG. 6G, the reference pulse on the top
portion may be a delta function or a Nyquist pulse or a time domain
signal whose spectrum is a constant across the active subcarriers.
A shaping filter is illustrated in the middle portion of FIG. 6G.
The shaping filter is for changing the shape and the effective
width of the reference pulse. A new pulse is generated by filtering
the reference pulse using the shaping filter. The new pulse is
illustrated in the bottom portion of FIG. 6G.
[0128] Still referring to FIG. 6G, the effective width of the
shaped pulse may be wider than the reference pulse's width. The
wider width is desirable for generating inter-symbol interference
among the shaped pulses sent sequentially. Namely, the wider width
causes overlaps among the sounding pulse sequence such that the
attacker cannot detect the polarity or phase or amplitude of the
overlapped pulses easily. In another word, the security of the
sounding signal is protected by the inter-pulse interference. From
another viewpoint, the shaping filter introduces artificial
multipaths at the sounding transmitter, which are unknown to the
attacker. For high level of security, more than ten taps may be
desired. Furthermore, the effective width of shaped pulse is
desired to cause inter-pulse interference among more than ten
shaped pulses such that the complexity for undoing the inter-pulse
interference is prohibitive for the attacker, who may not know the
shaping filter taps. The taps of the shaping filter may be
determined by encryption bits. In addition, the taps may be chosen
from QAM constellation e.g. 16-, 64-, and 256-QAM for the ease of
implementation.
[0129] FIG. 6H depicts an example technique 680 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0130] An example of generating the sounding signal is illustrated
in FIG. 6H. From the left to the right, part of the encryption bits
determine a set of QAM symbols e.g. QPSK or 16QAM or 64QAM symbols,
which may be multiplied with the reference pulses, respectively.
After FFT or DFT, some part of the output signals may be punctured
or removed to make room for DC and edge subcarriers. After the
puncturing, the remaining signals are loaded onto the active
subcarriers in frequency domain before going into time domain. The
IFFT or IDFT converts the loaded signals to time domain. If there
is no puncturing for the DC and edge subcarriers, the time domain
signals may consist of Nyquist pulses e.g. sinc pulses, where the
reference pulse is a Nyquist pulse. The puncturing introduces some
inter-pulse interference such that the reference pulse is not a
true Nyquist pulse. Before transmission, the reference pulses are
shaped for adding strong inter-pulse interferences and getting a
pulse shape unknown to the attacker. The pulse shaping can be
implemented as an FIR filter. In addition, circular convolution may
be used in the pulse shaping. For example, for 20 MHz sounding,
there are 128 QAM symbols before FFT, 122 active subcarriers before
IFFT, 128 samples for the reference pulses before pulse shaping,
and still 128 time samples after the pulse shaping with circular
convolution.
[0131] FIG. 6I depicts an example technique 690 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0132] The idea of introducing multipaths in FIG. 6H may be applied
to any sounding signal (e.g. the 8PSK-Golay in the 802.11az
technical standard) and the other options in the disclosure. For
example, the sounding transmitter may first generate the sounding
signal using OFDM and QAM modulations and then pass the sounding
signal to a multipath filter to add inter-symbol interference as
illustrated in FIG. 6I. The multipath filter may be the same the
shaping filter as in FIG. 6H. The multipath filter may be an FIR
filter and the filtering operation may be circular convolution.
Since the attacker may not know the filter taps of the multipath
filter, the detection complexity of the QAM symbol is increased
exponentially with the number of taps in the multipath filter. The
multipath taps are determined by part of the encryption bits and
the encryption bits are known to the intended receiver. The
intended receiver can undo the effect of introduced multipaths and
estimate the time of arrival of the sounded channel.
[0133] The example in FIG. 6I adds inter-symbol interference in the
time domain.
[0134] FIG. 6J depicts an example technique 695 for enhanced
channel sounding, in accordance with one or more example
embodiments of the present disclosure.
[0135] The interference introduced by the sounding transmitter can
be added in frequency domain as illustrated in FIG. 6J, which is a
special case of the schemes in FIGS. 5G, 6A, 6C, and 6D. The
inter-carrier interference (ICI) filter can be an FIR filter, whose
filter taps may be unknown to the attacker. Circular convolution
may be used by the ICI filter.
[0136] It is understood that the above descriptions are for
purposes of illustration and are not meant to be limiting.
[0137] FIG. 7 illustrates a flow diagram of illustrative process
700 for enhanced channel sounding, in accordance with one or more
example embodiments of the present disclosure.
[0138] At block 702, a device (e.g., the user device(s) 120 and/or
the AP 102 of FIG. 1, the AP 202 of FIG. 2A, the STA 204 or 206 of
FIG. 2A, the AP 252 of FIG. 2B, the STA 254 or 256 of FIG. 2B) may
generate one or more symbols for channel sounding (e.g., channel
sounding symbols). The channel sounding symbols may be included in
one or more HEz-LTF fields of a sounding frame (e.g., the NPDs of
FIGS. 2A and 2B), for which the number of symbols may depend on the
number of space-time streams used in transmission and/or based on a
number of users associated with the transmission. The symbols may
be generated using any of the enhanced techniques shown in FIGS.
5A-6J. For example, any symbol may include multiple frequency
subcarriers, and the amplitude of the subcarriers of a symbol may
vary (e.g., as shown in FIG. 5A). In this manner, the number of
constellation points of the symbols may be greater than the number
of constellation points used in some existing channel sounding
symbols (e.g., those generated using 8PSK or other techniques where
the amplitude of the subcarriers remains the same across all
subcarriers of a HE-LTF sounding symbol). The subcarrier values of
the sounding symbols may be random values (e.g., using 64QAM).
[0139] At block 704, the device may generate an 802.11az secure
mode sounding signal (e.g., sounding/ranging NDP) that includes the
one or more sounding symbols. The sounding signal may be
trigger-based (e.g., in response to a received trigger frame as
shown in FIG. 2A) or non-trigger-based (e.g., as shown in FIG. 2B).
The sounding symbols may be proceeded in the sounding signal by
other fields, such as an HE-SIG-A field and an HE-STF field.
[0140] At block 706, the device may send the 802.11az secure mode
sounding signal. The 802.11az secure mode sounding signal may be
sent as part of a channel sounding process according to FIG. 2A or
FIG. 2B, for example.
[0141] It is understood that the above descriptions are for
purposes of illustration and are not meant to be limiting.
[0142] FIG. 8 shows a functional diagram of an exemplary
communication station 800, in accordance with one or more example
embodiments of the present disclosure. In one embodiment, FIG. 8
illustrates a functional block diagram of a communication station
that may be suitable for use as an AP 102 (FIG. 1) or a user device
120 (FIG. 1) in accordance with some embodiments. The communication
station 800 may also be suitable for use as a handheld device, a
mobile device, a cellular telephone, a smartphone, a tablet, a
netbook, a wireless terminal, a laptop computer, a wearable
computer device, a femtocell, a high data rate (HDR) subscriber
station, an access point, an access terminal, or other personal
communication system (PCS) device.
[0143] The communication station 800 may include communications
circuitry 802 and a transceiver 810 for transmitting and receiving
signals to and from other communication stations using one or more
antennas 801. The communications circuitry 802 may include
circuitry that can operate the physical layer (PHY) communications
and/or medium access control (MAC) communications for controlling
access to the wireless medium, and/or any other communications
layers for transmitting and receiving signals. The communication
station 800 may also include processing circuitry 806 and memory
808 arranged to perform the operations described herein. In some
embodiments, the communications circuitry 802 and the processing
circuitry 806 may be configured to perform operations detailed in
the above figures, diagrams, and flows.
[0144] In accordance with some embodiments, the communications
circuitry 802 may be arranged to contend for a wireless medium and
configure frames or packets for communicating over the wireless
medium. The communications circuitry 802 may be arranged to
transmit and receive signals. The communications circuitry 802 may
also include circuitry for modulation/demodulation,
upconversion/downconversion, filtering, amplification, etc. In some
embodiments, the processing circuitry 806 of the communication
station 800 may include one or more processors. In other
embodiments, two or more antennas 801 may be coupled to the
communications circuitry 802 arranged for sending and receiving
signals. The memory 808 may store information for configuring the
processing circuitry 806 to perform operations for configuring and
transmitting message frames and performing the various operations
described herein. The memory 808 may include any type of memory,
including non-transitory memory, for storing information in a form
readable by a machine (e.g., a computer). For example, the memory
808 may include a computer-readable storage device, read-only
memory (ROM), random-access memory (RAM), magnetic disk storage
media, optical storage media, flash-memory devices and other
storage devices and media.
[0145] In some embodiments, the communication station 800 may be
part of a portable wireless communication device, such as a
personal digital assistant (PDA), a laptop or portable computer
with wireless communication capability, a web tablet, a wireless
telephone, a smartphone, a wireless headset, a pager, an instant
messaging device, a digital camera, an access point, a television,
a medical device (e.g., a heart rate monitor, a blood pressure
monitor, etc.), a wearable computer device, or another device that
may receive and/or transmit information wirelessly.
[0146] In some embodiments, the communication station 800 may
include one or more antennas 801. The antennas 801 may include one
or more directional or omnidirectional antennas, including, for
example, dipole antennas, monopole antennas, patch antennas, loop
antennas, microstrip antennas, or other types of antennas suitable
for transmission of RF signals. In some embodiments, instead of two
or more antennas, a single antenna with multiple apertures may be
used. In these embodiments, each aperture may be considered a
separate antenna. In some multiple-input multiple-output (MIMO)
embodiments, the antennas may be effectively separated for spatial
diversity and the different channel characteristics that may result
between each of the antennas and the antennas of a transmitting
station.
[0147] In some embodiments, the communication station 800 may
include one or more of a keyboard, a display, a non-volatile memory
port, multiple antennas, a graphics processor, an application
processor, speakers, and other mobile device elements. The display
may be an LCD screen including a touch screen.
[0148] Although the communication station 800 is illustrated as
having several separate functional elements, two or more of the
functional elements may be combined and may be implemented by
combinations of software-configured elements, such as processing
elements including digital signal processors (DSPs), and/or other
hardware elements. For example, some elements may include one or
more microprocessors, DSPs, field-programmable gate arrays (FPGAs),
application specific integrated circuits (ASICs), radio-frequency
integrated circuits (RFICs) and combinations of various hardware
and logic circuitry for performing at least the functions described
herein. In some embodiments, the functional elements of the
communication station 800 may refer to one or more processes
operating on one or more processing elements.
[0149] Certain embodiments may be implemented in one or a
combination of hardware, firmware, and software. Other embodiments
may also be implemented as instructions stored on a
computer-readable storage device, which may be read and executed by
at least one processor to perform the operations described herein.
A computer-readable storage device may include any non-transitory
memory mechanism for storing information in a form readable by a
machine (e.g., a computer). For example, a computer-readable
storage device may include read-only memory (ROM), random-access
memory (RAM), magnetic disk storage media, optical storage media,
flash-memory devices, and other storage devices and media. In some
embodiments, the communication station 800 may include one or more
processors and may be configured with instructions stored on a
computer-readable storage device.
[0150] FIG. 9 illustrates a block diagram of an example of a
machine 900 or system upon which any one or more of the techniques
(e.g., methodologies) discussed herein may be performed. In other
embodiments, the machine 900 may operate as a standalone device or
may be connected (e.g., networked) to other machines. In a
networked deployment, the machine 900 may operate in the capacity
of a server machine, a client machine, or both in server-client
network environments. In an example, the machine 900 may act as a
peer machine in peer-to-peer (P2P) (or other distributed) network
environments. The machine 900 may be a personal computer (PC), a
tablet PC, a set-top box (STB), a personal digital assistant (PDA),
a mobile telephone, a wearable computer device, a web appliance, a
network router, a switch or bridge, or any machine capable of
executing instructions (sequential or otherwise) that specify
actions to be taken by that machine, such as a base station.
Further, while only a single machine is illustrated, the term
"machine" shall also be taken to include any collection of machines
that individually or jointly execute a set (or multiple sets) of
instructions to perform any one or more of the methodologies
discussed herein, such as cloud computing, software as a service
(SaaS), or other computer cluster configurations.
[0151] Examples, as described herein, may include or may operate on
logic or a number of components, modules, or mechanisms. Modules
are tangible entities (e.g., hardware) capable of performing
specified operations when operating. A module includes hardware. In
an example, the hardware may be specifically configured to carry
out a specific operation (e.g., hardwired). In another example, the
hardware may include configurable execution units (e.g.,
transistors, circuits, etc.) and a computer readable medium
containing instructions where the instructions configure the
execution units to carry out a specific operation when in
operation. The configuring may occur under the direction of the
executions units or a loading mechanism. Accordingly, the execution
units are communicatively coupled to the computer-readable medium
when the device is operating. In this example, the execution units
may be a member of more than one module. For example, under
operation, the execution units may be configured by a first set of
instructions to implement a first module at one point in time and
reconfigured by a second set of instructions to implement a second
module at a second point in time.
[0152] The machine (e.g., computer system) 900 may include a
hardware processor 902 (e.g., a central processing unit (CPU), a
graphics processing unit (GPU), a hardware processor core, or any
combination thereof), a main memory 904 and a static memory 906,
some or all of which may communicate with each other via an
interlink (e.g., bus) 908. The machine 900 may further include a
power management device 932, a graphics display device 910, an
alphanumeric input device 912 (e.g., a keyboard), and a user
interface (UI) navigation device 914 (e.g., a mouse). In an
example, the graphics display device 910, alphanumeric input device
912, and UI navigation device 914 may be a touch screen display.
The machine 900 may additionally include a storage device (i.e.,
drive unit) 916, a signal generation device 918 (e.g., a speaker),
an enhanced sounding for secure mode device 919, a network
interface device/transceiver 920 coupled to antenna(s) 930, and one
or more sensors 928, such as a global positioning system (GPS)
sensor, a compass, an accelerometer, or other sensor. The machine
900 may include an output controller 934, such as a serial (e.g.,
universal serial bus (USB), parallel, or other wired or wireless
(e.g., infrared (IR), near field communication (NFC), etc.)
connection to communicate with or control one or more peripheral
devices (e.g., a printer, a card reader, etc.)). The operations in
accordance with one or more example embodiments of the present
disclosure may be carried out by a baseband processor. The baseband
processor may be configured to generate corresponding baseband
signals. The baseband processor may further include physical layer
(PHY) and medium access control layer (MAC) circuitry, and may
further interface with the hardware processor 902 for generation
and processing of the baseband signals and for controlling
operations of the main memory 904, the storage device 916, and/or
the enhanced sounding for secure mode device 919. The baseband
processor may be provided on a single radio card, a single chip, or
an integrated circuit (IC).
[0153] The storage device 916 may include a machine readable medium
922 on which is stored one or more sets of data structures or
instructions 924 (e.g., software) embodying or utilized by any one
or more of the techniques or functions described herein. The
instructions 924 may also reside, completely or at least partially,
within the main memory 904, within the static memory 906, or within
the hardware processor 902 during execution thereof by the machine
900. In an example, one or any combination of the hardware
processor 902, the main memory 904, the static memory 906, or the
storage device 916 may constitute machine-readable media.
[0154] The enhanced sounding for secure mode device 919 may carry
out or perform any of the operations and processes (e.g., process
700) described and shown above.
[0155] It is understood that the above are only a subset of what
the enhanced sounding for secure mode device 919 may be configured
to perform and that other functions included throughout this
disclosure may also be performed by the enhanced sounding for
secure mode device 919.
[0156] While the machine-readable medium 922 is illustrated as a
single medium, the term "machine-readable medium" may include a
single medium or multiple media (e.g., a centralized or distributed
database, and/or associated caches and servers) configured to store
the one or more instructions 924.
[0157] Various embodiments may be implemented fully or partially in
software and/or firmware. This software and/or firmware may take
the form of instructions contained in or on a non-transitory
computer-readable storage medium. Those instructions may then be
read and executed by one or more processors to enable performance
of the operations described herein. The instructions may be in any
suitable form, such as but not limited to source code, compiled
code, interpreted code, executable code, static code, dynamic code,
and the like. Such a computer-readable medium may include any
tangible non-transitory medium for storing information in a form
readable by one or more computers, such as but not limited to read
only memory (ROM); random access memory (RAM); magnetic disk
storage media; optical storage media; a flash memory, etc.
[0158] The term "machine-readable medium" may include any medium
that is capable of storing, encoding, or carrying instructions for
execution by the machine 900 and that cause the machine 900 to
perform any one or more of the techniques of the present
disclosure, or that is capable of storing, encoding, or carrying
data structures used by or associated with such instructions.
Non-limiting machine-readable medium examples may include
solid-state memories and optical and magnetic media. In an example,
a massed machine-readable medium includes a machine-readable medium
with a plurality of particles having resting mass. Specific
examples of massed machine-readable media may include non-volatile
memory, such as semiconductor memory devices (e.g., electrically
programmable read-only memory (EPROM), or electrically erasable
programmable read-only memory (EEPROM)) and flash memory devices;
magnetic disks, such as internal hard disks and removable disks;
magneto-optical disks; and CD-ROM and DVD-ROM disks.
[0159] The instructions 924 may further be transmitted or received
over a communications network 926 using a transmission medium via
the network interface device/transceiver 920 utilizing any one of a
number of transfer protocols (e.g., frame relay, internet protocol
(IP), transmission control protocol (TCP), user datagram protocol
(UDP), hypertext transfer protocol (HTTP), etc.). Example
communications networks may include a local area network (LAN), a
wide area network (WAN), a packet data network (e.g., the
Internet), mobile telephone networks (e.g., cellular networks),
plain old telephone (POTS) networks, wireless data networks (e.g.,
Institute of Electrical and Electronics Engineers (IEEE) 802.11
family of standards known as Wi-Fi.RTM., IEEE 802.16 family of
standards known as WiMax.RTM.), IEEE 802.15.4 family of standards,
and peer-to-peer (P2P) networks, among others. In an example, the
network interface device/transceiver 920 may include one or more
physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or
more antennas to connect to the communications network 926. In an
example, the network interface device/transceiver 920 may include a
plurality of antennas to wirelessly communicate using at least one
of single-input multiple-output (SIMO), multiple-input
multiple-output (MIMO), or multiple-input single-output (MISO)
techniques. The term "transmission medium" shall be taken to
include any intangible medium that is capable of storing, encoding,
or carrying instructions for execution by the machine 900 and
includes digital or analog communications signals or other
intangible media to facilitate communication of such software.
[0160] The operations and processes described and shown above may
be carried out or performed in any suitable order as desired in
various implementations. Additionally, in certain implementations,
at least a portion of the operations may be carried out in
parallel. Furthermore, in certain implementations, less than or
more than the operations described may be performed.
[0161] FIG. 10 is a block diagram of a radio architecture 105A,
105B in accordance with some embodiments that may be implemented in
any one of the example AP 102 and/or the example STA 120 of FIG. 1.
Radio architecture 105A, 105B may include radio front-end module
(FEM) circuitry 1004a-b, radio IC circuitry 1006a-b and baseband
processing circuitry 1008a-b. Radio architecture 105A, 105B as
shown includes both Wireless Local Area Network (WLAN)
functionality and Bluetooth (BT) functionality although embodiments
are not so limited. In this disclosure, "WLAN" and "Wi-Fi" are used
interchangeably.
[0162] FEM circuitry 1004a-b may include a WLAN or Wi-Fi FEM
circuitry 1004a and a Bluetooth (BT) FEM circuitry 1004b. The WLAN
FEM circuitry 1004a may include a receive signal path comprising
circuitry configured to operate on WLAN RF signals received from
one or more antennas 1001, to amplify the received signals and to
provide the amplified versions of the received signals to the WLAN
radio IC circuitry 1006a for further processing. The BT FEM
circuitry 1004b may include a receive signal path which may include
circuitry configured to operate on BT RF signals received from one
or more antennas 1001, to amplify the received signals and to
provide the amplified versions of the received signals to the BT
radio IC circuitry 1006b for further processing. FEM circuitry
1004a may also include a transmit signal path which may include
circuitry configured to amplify WLAN signals provided by the radio
IC circuitry 1006a for wireless transmission by one or more of the
antennas 1001. In addition, FEM circuitry 1004b may also include a
transmit signal path which may include circuitry configured to
amplify BT signals provided by the radio IC circuitry 1006b for
wireless transmission by the one or more antennas. In the
embodiment of FIG. 10, although FEM 1004a and FEM 1004b are shown
as being distinct from one another, embodiments are not so limited,
and include within their scope the use of an FEM (not shown) that
includes a transmit path and/or a receive path for both WLAN and BT
signals, or the use of one or more FEM circuitries where at least
some of the FEM circuitries share transmit and/or receive signal
paths for both WLAN and BT signals.
[0163] Radio IC circuitry 1006a-b as shown may include WLAN radio
IC circuitry 1006a and BT radio IC circuitry 1006b. The WLAN radio
IC circuitry 1006a may include a receive signal path which may
include circuitry to down-convert WLAN RF signals received from the
FEM circuitry 1004a and provide baseband signals to WLAN baseband
processing circuitry 1008a. BT radio IC circuitry 1006b may in turn
include a receive signal path which may include circuitry to
down-convert BT RF signals received from the FEM circuitry 1004b
and provide baseband signals to BT baseband processing circuitry
1008b. WLAN radio IC circuitry 1006a may also include a transmit
signal path which may include circuitry to up-convert WLAN baseband
signals provided by the WLAN baseband processing circuitry 1008a
and provide WLAN RF output signals to the FEM circuitry 1004a for
subsequent wireless transmission by the one or more antennas 1001.
BT radio IC circuitry 1006b may also include a transmit signal path
which may include circuitry to up-convert BT baseband signals
provided by the BT baseband processing circuitry 1008b and provide
BT RF output signals to the FEM circuitry 1004b for subsequent
wireless transmission by the one or more antennas 1001. In the
embodiment of FIG. 10, although radio IC circuitries 1006a and
1006b are shown as being distinct from one another, embodiments are
not so limited, and include within their scope the use of a radio
IC circuitry (not shown) that includes a transmit signal path
and/or a receive signal path for both WLAN and BT signals, or the
use of one or more radio IC circuitries where at least some of the
radio IC circuitries share transmit and/or receive signal paths for
both WLAN and BT signals.
[0164] Baseband processing circuity 1008a-b may include a WLAN
baseband processing circuitry 1008a and a BT baseband processing
circuitry 1008b. The WLAN baseband processing circuitry 1008a may
include a memory, such as, for example, a set of RAM arrays in a
Fast Fourier Transform or Inverse Fast Fourier Transform block (not
shown) of the WLAN baseband processing circuitry 1008a. Each of the
WLAN baseband circuitry 1008a and the BT baseband circuitry 1008b
may further include one or more processors and control logic to
process the signals received from the corresponding WLAN or BT
receive signal path of the radio IC circuitry 1006a-b, and to also
generate corresponding WLAN or BT baseband signals for the transmit
signal path of the radio IC circuitry 1006a-b. Each of the baseband
processing circuitries 1008a and 1008b may further include physical
layer (PHY) and medium access control layer (MAC) circuitry, and
may further interface with a device for generation and processing
of the baseband signals and for controlling operations of the radio
IC circuitry 1006a-b.
[0165] Referring still to FIG. 10, according to the shown
embodiment, WLAN-BT coexistence circuitry 1013 may include logic
providing an interface between the WLAN baseband circuitry 1008a
and the BT baseband circuitry 1008b to enable use cases requiring
WLAN and BT coexistence. In addition, a switch 1003 may be provided
between the WLAN FEM circuitry 1004a and the BT FEM circuitry 1004b
to allow switching between the WLAN and BT radios according to
application needs. In addition, although the antennas 1001 are
depicted as being respectively connected to the WLAN FEM circuitry
1004a and the BT FEM circuitry 1004b, embodiments include within
their scope the sharing of one or more antennas as between the WLAN
and BT FEMs, or the provision of more than one antenna connected to
each of FEM 1004a or 1004b.
[0166] In some embodiments, the front-end module circuitry 1004a-b,
the radio IC circuitry 1006a-b, and baseband processing circuitry
1008a-b may be provided on a single radio card, such as wireless
radio card 1002. In some other embodiments, the one or more
antennas 1001, the FEM circuitry 1004a-b and the radio IC circuitry
1006a-b may be provided on a single radio card. In some other
embodiments, the radio IC circuitry 1006a-b and the baseband
processing circuitry 1008a-b may be provided on a single chip or
integrated circuit (IC), such as IC 1012.
[0167] In some embodiments, the wireless radio card 1002 may
include a WLAN radio card and may be configured for Wi-Fi
communications, although the scope of the embodiments is not
limited in this respect. In some of these embodiments, the radio
architecture 105A, 105B may be configured to receive and transmit
orthogonal frequency division multiplexed (OFDM) or orthogonal
frequency division multiple access (OFDMA) communication signals
over a multicarrier communication channel. The OFDM or OFDMA
signals may comprise a plurality of orthogonal subcarriers.
[0168] In some of these multicarrier embodiments, radio
architecture 105A, 105B may be part of a Wi-Fi communication
station (STA) such as a wireless access point (AP), a base station
or a mobile device including a Wi-Fi device. In some of these
embodiments, radio architecture 105A, 105B may be configured to
transmit and receive signals in accordance with specific
communication standards and/or protocols, such as any of the
Institute of Electrical and Electronics Engineers (IEEE) standards
including, 802.11n-2009, IEEE 802.11-2012, IEEE 802.11-2016,
802.11n-2009, 802.11ac, 802.11ah, 802.11ad, 802.11 ay and/or
802.11ax standards and/or proposed specifications for WLANs,
although the scope of embodiments is not limited in this respect.
Radio architecture 105A, 105B may also be suitable to transmit
and/or receive communications in accordance with other techniques
and standards.
[0169] In some embodiments, the radio architecture 105A, 105B may
be configured for high-efficiency Wi-Fi (HEW) communications in
accordance with the IEEE 802.11ax standard. In these embodiments,
the radio architecture 105A, 105B may be configured to communicate
in accordance with an OFDMA technique, although the scope of the
embodiments is not limited in this respect.
[0170] In some other embodiments, the radio architecture 105A, 105B
may be configured to transmit and receive signals transmitted using
one or more other modulation techniques such as spread spectrum
modulation (e.g., direct sequence code division multiple access
(DS-CDMA) and/or frequency hopping code division multiple access
(FH-CDMA)), time-division multiplexing (TDM) modulation, and/or
frequency-division multiplexing (FDM) modulation, although the
scope of the embodiments is not limited in this respect.
[0171] In some embodiments, as further shown in FIG. 10, the BT
baseband circuitry 1008b may be compliant with a Bluetooth (BT)
connectivity standard such as Bluetooth, Bluetooth 8.0 or Bluetooth
6.0, or any other iteration of the Bluetooth Standard.
[0172] In some embodiments, the radio architecture 105A, 105B may
include other radio cards, such as a cellular radio card configured
for cellular (e.g., 5GPP such as LTE, LTE-Advanced or 7G
communications).
[0173] In some IEEE 802.11 embodiments, the radio architecture
105A, 105B may be configured for communication over various channel
bandwidths including bandwidths having center frequencies of about
900 MHz, 2.4 GHz, 5 GHz, and bandwidths of about 2 MHz, 4 MHz, 5
MHz, 5.5 MHz, 6 MHz, 8 MHz, 10 MHz, 20 MHz, 40 MHz, 80 MHz (with
contiguous bandwidths) or 80+80 MHz (160 MHz) (with non-contiguous
bandwidths). In some embodiments, a 920 MHz channel bandwidth may
be used. The scope of the embodiments is not limited with respect
to the above center frequencies however.
[0174] FIG. 11 illustrates WLAN FEM circuitry 1004a in accordance
with some embodiments. Although the example of FIG. 11 is described
in conjunction with the WLAN FEM circuitry 1004a, the example of
FIG. 11 may be described in conjunction with the example BT FEM
circuitry 1004b (FIG. 10), although other circuitry configurations
may also be suitable.
[0175] In some embodiments, the FEM circuitry 1004a may include a
TX/RX switch 1102 to switch between transmit mode and receive mode
operation. The FEM circuitry 1004a may include a receive signal
path and a transmit signal path. The receive signal path of the FEM
circuitry 1004a may include a low-noise amplifier (LNA) 1106 to
amplify received RF signals 1103 and provide the amplified received
RF signals 1107 as an output (e.g., to the radio IC circuitry
1006a-b (FIG. 10)). The transmit signal path of the circuitry 1004a
may include a power amplifier (PA) to amplify input RF signals 1109
(e.g., provided by the radio IC circuitry 1006a-b), and one or more
filters 1112, such as band-pass filters (BPFs), low-pass filters
(LPFs) or other types of filters, to generate RF signals 1115 for
subsequent transmission (e.g., by one or more of the antennas 1001
(FIG. 10)) via an example duplexer 1114.
[0176] In some dual-mode embodiments for Wi-Fi communication, the
FEM circuitry 1004a may be configured to operate in either the 2.4
GHz frequency spectrum or the 5 GHz frequency spectrum. In these
embodiments, the receive signal path of the FEM circuitry 1004a may
include a receive signal path duplexer 1104 to separate the signals
from each spectrum as well as provide a separate LNA 1106 for each
spectrum as shown. In these embodiments, the transmit signal path
of the FEM circuitry 1004a may also include a power amplifier 1110
and a filter 1112, such as a BPF, an LPF or another type of filter
for each frequency spectrum and a transmit signal path duplexer
1104 to provide the signals of one of the different spectrums onto
a single transmit path for subsequent transmission by the one or
more of the antennas 1001 (FIG. 10). In some embodiments, BT
communications may utilize the 2.4 GHz signal paths and may utilize
the same FEM circuitry 1004a as the one used for WLAN
communications.
[0177] FIG. 12 illustrates radio IC circuitry 1006a in accordance
with some embodiments. The radio IC circuitry 1006a is one example
of circuitry that may be suitable for use as the WLAN or BT radio
IC circuitry 1006a/1006b (FIG. 10), although other circuitry
configurations may also be suitable. Alternatively, the example of
FIG. 12 may be described in conjunction with the example BT radio
IC circuitry 1006b.
[0178] In some embodiments, the radio IC circuitry 1006a may
include a receive signal path and a transmit signal path. The
receive signal path of the radio IC circuitry 1006a may include at
least mixer circuitry 1202, such as, for example, down-conversion
mixer circuitry, amplifier circuitry 1206 and filter circuitry
1208. The transmit signal path of the radio IC circuitry 1006a may
include at least filter circuitry 1212 and mixer circuitry 1214,
such as, for example, up-conversion mixer circuitry. Radio IC
circuitry 1006a may also include synthesizer circuitry 1204 for
synthesizing a frequency 1205 for use by the mixer circuitry 1202
and the mixer circuitry 1214. The mixer circuitry 1202 and/or 1214
may each, according to some embodiments, be configured to provide
direct conversion functionality. The latter type of circuitry
presents a much simpler architecture as compared with standard
super-heterodyne mixer circuitries, and any flicker noise brought
about by the same may be alleviated for example through the use of
OFDM modulation. FIG. 12 illustrates only a simplified version of a
radio IC circuitry, and may include, although not shown,
embodiments where each of the depicted circuitries may include more
than one component. For instance, mixer circuitry 1214 may each
include one or more mixers, and filter circuitries 1208 and/or 1212
may each include one or more filters, such as one or more BPFs
and/or LPFs according to application needs. For example, when mixer
circuitries are of the direct-conversion type, they may each
include two or more mixers.
[0179] In some embodiments, mixer circuitry 1202 may be configured
to down-convert RF signals 1107 received from the FEM circuitry
1004a-b (FIG. 10) based on the synthesized frequency 1205 provided
by synthesizer circuitry 1204. The amplifier circuitry 1206 may be
configured to amplify the down-converted signals and the filter
circuitry 1208 may include an LPF configured to remove unwanted
signals from the down-converted signals to generate output baseband
signals 1207. Output baseband signals 1207 may be provided to the
baseband processing circuitry 1008a-b (FIG. 10) for further
processing. In some embodiments, the output baseband signals 1207
may be zero-frequency baseband signals, although this is not a
requirement. In some embodiments, mixer circuitry 1202 may comprise
passive mixers, although the scope of the embodiments is not
limited in this respect.
[0180] In some embodiments, the mixer circuitry 1214 may be
configured to up-convert input baseband signals 1211 based on the
synthesized frequency 1205 provided by the synthesizer circuitry
1204 to generate RF output signals 1109 for the FEM circuitry
1004a-b. The baseband signals 1211 may be provided by the baseband
processing circuitry 1008a-b and may be filtered by filter
circuitry 1212. The filter circuitry 1212 may include an LPF or a
BPF, although the scope of the embodiments is not limited in this
respect.
[0181] In some embodiments, the mixer circuitry 1202 and the mixer
circuitry 1214 may each include two or more mixers and may be
arranged for quadrature down-conversion and/or up-conversion
respectively with the help of synthesizer 1204. In some
embodiments, the mixer circuitry 1202 and the mixer circuitry 1214
may each include two or more mixers each configured for image
rejection (e.g., Hartley image rejection). In some embodiments, the
mixer circuitry 1202 and the mixer circuitry 1214 may be arranged
for direct down-conversion and/or direct up-conversion,
respectively. In some embodiments, the mixer circuitry 1202 and the
mixer circuitry 1214 may be configured for super-heterodyne
operation, although this is not a requirement.
[0182] Mixer circuitry 1202 may comprise, according to one
embodiment: quadrature passive mixers (e.g., for the in-phase (I)
and quadrature phase (Q) paths). In such an embodiment, RF input
signal 1107 from FIG. 12 may be down-converted to provide I and Q
baseband output signals to be sent to the baseband processor.
[0183] Quadrature passive mixers may be driven by zero and
ninety-degree time-varying LO switching signals provided by a
quadrature circuitry which may be configured to receive a LO
frequency (fLO) from a local oscillator or a synthesizer, such as
LO frequency 1205 of synthesizer 1204 (FIG. 12). In some
embodiments, the LO frequency may be the carrier frequency, while
in other embodiments, the LO frequency may be a fraction of the
carrier frequency (e.g., one-half the carrier frequency, one-third
the carrier frequency). In some embodiments, the zero and
ninety-degree time-varying switching signals may be generated by
the synthesizer, although the scope of the embodiments is not
limited in this respect.
[0184] In some embodiments, the LO signals may differ in duty cycle
(the percentage of one period in which the LO signal is high)
and/or offset (the difference between start points of the period).
In some embodiments, the LO signals may have an 85% duty cycle and
an 80% offset. In some embodiments, each branch of the mixer
circuitry (e.g., the in-phase (I) and quadrature phase (Q) path)
may operate at an 80% duty cycle, which may result in a significant
reduction is power consumption.
[0185] The RF input signal 1107 (FIG. 11) may comprise a balanced
signal, although the scope of the embodiments is not limited in
this respect. The I and Q baseband output signals may be provided
to low-noise amplifier, such as amplifier circuitry 1206 (FIG. 12)
or to filter circuitry 1208 (FIG. 12).
[0186] In some embodiments, the output baseband signals 1207 and
the input baseband signals 1211 may be analog baseband signals,
although the scope of the embodiments is not limited in this
respect. In some alternate embodiments, the output baseband signals
1207 and the input baseband signals 1211 may be digital baseband
signals. In these alternate embodiments, the radio IC circuitry may
include analog-to-digital converter (ADC) and digital-to-analog
converter (DAC) circuitry.
[0187] In some dual-mode embodiments, a separate radio IC circuitry
may be provided for processing signals for each spectrum, or for
other spectrums not mentioned here, although the scope of the
embodiments is not limited in this respect.
[0188] In some embodiments, the synthesizer circuitry 1204 may be a
fractional-N synthesizer or a fractional N/N+1 synthesizer,
although the scope of the embodiments is not limited in this
respect as other types of frequency synthesizers may be suitable.
For example, synthesizer circuitry 1204 may be a delta-sigma
synthesizer, a frequency multiplier, or a synthesizer comprising a
phase-locked loop with a frequency divider. According to some
embodiments, the synthesizer circuitry 1204 may include digital
synthesizer circuitry. An advantage of using a digital synthesizer
circuitry is that, although it may still include some analog
components, its footprint may be scaled down much more than the
footprint of an analog synthesizer circuitry. In some embodiments,
frequency input into synthesizer circuity 1204 may be provided by a
voltage controlled oscillator (VCO), although that is not a
requirement. A divider control input may further be provided by
either the baseband processing circuitry 1008a-b (FIG. 10)
depending on the desired output frequency 1205. In some
embodiments, a divider control input (e.g., N) may be determined
from a look-up table (e.g., within a Wi-Fi card) based on a channel
number and a channel center frequency as determined or indicated by
the example application processor 1010. The application processor
1010 may include, or otherwise be connected to, one of the example
secure signal converter 101 or the example received signal
converter 103 (e.g., depending on which device the example radio
architecture is implemented in).
[0189] In some embodiments, synthesizer circuitry 1204 may be
configured to generate a carrier frequency as the output frequency
1205, while in other embodiments, the output frequency 1205 may be
a fraction of the carrier frequency (e.g., one-half the carrier
frequency, one-third the carrier frequency). In some embodiments,
the output frequency 1205 may be a LO frequency (fLO).
[0190] FIG. 13 illustrates a functional block diagram of baseband
processing circuitry 1008a in accordance with some embodiments. The
baseband processing circuitry 1008a is one example of circuitry
that may be suitable for use as the baseband processing circuitry
1008a (FIG. 10), although other circuitry configurations may also
be suitable. Alternatively, the example of FIG. 12 may be used to
implement the example BT baseband processing circuitry 1008b of
FIG. 10.
[0191] The baseband processing circuitry 1008a may include a
receive baseband processor (RX BBP) 1302 for processing receive
baseband signals 1209 provided by the radio IC circuitry 1006a-b
(FIG. 10) and a transmit baseband processor (TX BBP) 1304 for
generating transmit baseband signals 1211 for the radio IC
circuitry 1006a-b. The baseband processing circuitry 1008a may also
include control logic 1306 for coordinating the operations of the
baseband processing circuitry 1008a.
[0192] In some embodiments (e.g., when analog baseband signals are
exchanged between the baseband processing circuitry 1008a-b and the
radio IC circuitry 1006a-b), the baseband processing circuitry
1008a may include ADC 1310 to convert analog baseband signals 1309
received from the radio IC circuitry 1006a-b to digital baseband
signals for processing by the RX BBP 1302. In these embodiments,
the baseband processing circuitry 1008a may also include DAC 1312
to convert digital baseband signals from the TX BBP 1304 to analog
baseband signals 1311.
[0193] In some embodiments that communicate OFDM signals or OFDMA
signals, such as through baseband processor 1008a, the transmit
baseband processor 1304 may be configured to generate OFDM or OFDMA
signals as appropriate for transmission by performing an inverse
fast Fourier transform (IFFT). The receive baseband processor 1302
may be configured to process received OFDM signals or OFDMA signals
by performing an FFT. In some embodiments, the receive baseband
processor 1302 may be configured to detect the presence of an OFDM
signal or OFDMA signal by performing an autocorrelation, to detect
a preamble, such as a short preamble, and by performing a
cross-correlation, to detect a long preamble. The preambles may be
part of a predetermined frame structure for Wi-Fi
communication.
[0194] Referring back to FIG. 10, in some embodiments, the antennas
1001 (FIG. 10) may each comprise one or more directional or
omnidirectional antennas, including, for example, dipole antennas,
monopole antennas, patch antennas, loop antennas, microstrip
antennas or other types of antennas suitable for transmission of RF
signals. In some multiple-input multiple-output (MIMO) embodiments,
the antennas may be effectively separated to take advantage of
spatial diversity and the different channel characteristics that
may result. Antennas 1001 may each include a set of phased-array
antennas, although embodiments are not so limited.
[0195] Although the radio architecture 105A, 105B is illustrated as
having several separate functional elements, one or more of the
functional elements may be combined and may be implemented by
combinations of software-configured elements, such as processing
elements including digital signal processors (DSPs), and/or other
hardware elements. For example, some elements may comprise one or
more microprocessors, DSPs, field-programmable gate arrays (FPGAs),
application specific integrated circuits (ASICs), radio-frequency
integrated circuits (RFICs) and combinations of various hardware
and logic circuitry for performing at least the functions described
herein. In some embodiments, the functional elements may refer to
one or more processes operating on one or more processing
elements.
[0196] The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any embodiment described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other embodiments. The terms
"computing device," "user device," "communication station,"
"station," "handheld device," "mobile device," "wireless device"
and "user equipment" (UE) as used herein refers to a wireless
communication device such as a cellular telephone, a smartphone, a
tablet, a netbook, a wireless terminal, a laptop computer, a
femtocell, a high data rate (HDR) subscriber station, an access
point, a printer, a point of sale device, an access terminal, or
other personal communication system (PCS) device. The device may be
either mobile or stationary.
[0197] As used within this document, the term "communicate" is
intended to include transmitting, or receiving, or both
transmitting and receiving. This may be particularly useful in
claims when describing the organization of data that is being
transmitted by one device and received by another, but only the
functionality of one of those devices is required to infringe the
claim. Similarly, the bidirectional exchange of data between two
devices (both devices transmit and receive during the exchange) may
be described as "communicating," when only the functionality of one
of those devices is being claimed. The term "communicating" as used
herein with respect to a wireless communication signal includes
transmitting the wireless communication signal and/or receiving the
wireless communication signal. For example, a wireless
communication unit, which is capable of communicating a wireless
communication signal, may include a wireless transmitter to
transmit the wireless communication signal to at least one other
wireless communication unit, and/or a wireless communication
receiver to receive the wireless communication signal from at least
one other wireless communication unit.
[0198] As used herein, unless otherwise specified, the use of the
ordinal adjectives "first," "second," "third," etc., to describe a
common object, merely indicates that different instances of like
objects are being referred to and are not intended to imply that
the objects so described must be in a given sequence, either
temporally, spatially, in ranking, or in any other manner.
[0199] The term "access point" (AP) as used herein may be a fixed
station. An access point may also be referred to as an access node,
a base station, an evolved node B (eNodeB), or some other similar
terminology known in the art. An access terminal may also be called
a mobile station, user equipment (UE), a wireless communication
device, or some other similar terminology known in the art.
Embodiments disclosed herein generally pertain to wireless
networks. Some embodiments may relate to wireless networks that
operate in accordance with one of the IEEE 802.11 standards.
[0200] Some embodiments may be used in conjunction with various
devices and systems, for example, a personal computer (PC), a
desktop computer, a mobile computer, a laptop computer, a notebook
computer, a tablet computer, a server computer, a handheld
computer, a handheld device, a personal digital assistant (PDA)
device, a handheld PDA device, an on-board device, an off-board
device, a hybrid device, a vehicular device, a non-vehicular
device, a mobile or portable device, a consumer device, a
non-mobile or non-portable device, a wireless communication
station, a wireless communication device, a wireless access point
(AP), a wired or wireless router, a wired or wireless modem, a
video device, an audio device, an audio-video (A/V) device, a wired
or wireless network, a wireless area network, a wireless video area
network (WVAN), a local area network (LAN), a wireless LAN (WLAN),
a personal area network (PAN), a wireless PAN (WPAN), and the
like.
[0201] Some embodiments may be used in conjunction with one way
and/or two-way radio communication systems, cellular
radio-telephone communication systems, a mobile phone, a cellular
telephone, a wireless telephone, a personal communication system
(PCS) device, a PDA device which incorporates a wireless
communication device, a mobile or portable global positioning
system (GPS) device, a device which incorporates a GPS receiver or
transceiver or chip, a device which incorporates an RFID element or
chip, a multiple input multiple output (MIMO) transceiver or
device, a single input multiple output (SIMO) transceiver or
device, a multiple input single output (MIS 0) transceiver or
device, a device having one or more internal antennas and/or
external antennas, digital video broadcast (DVB) devices or
systems, multi-standard radio devices or systems, a wired or
wireless handheld device, e.g., a smartphone, a wireless
application protocol (WAP) device, or the like.
[0202] Some embodiments may be used in conjunction with one or more
types of wireless communication signals and/or systems following
one or more wireless communication protocols, for example, radio
frequency (RF), infrared (IR), frequency-division multiplexing
(FDM), orthogonal FDM (OFDM), time-division multiplexing (TDM),
time-division multiple access (TDMA), extended TDMA (E-TDMA),
general packet radio service (GPRS), extended GPRS, code-division
multiple access (CDMA), wideband CDMA (WCDMA), CDMA 2000,
single-carrier CDMA, multi-carrier CDMA, multi-carrier modulation
(MDM), discrete multi-tone (DMT), Bluetooth.RTM., global
positioning system (GPS), Wi-Fi, Wi-Max, ZigBee, ultra-wideband
(UWB), global system for mobile communications (GSM), 2G, 2.5G, 3G,
3.5G, 4G, fifth generation (5G) mobile networks, 3GPP, long term
evolution (LTE), LTE advanced, enhanced data rates for GSM
Evolution (EDGE), or the like. Other embodiments may be used in
various other devices, systems, and/or networks.
[0203] The following examples pertain to further embodiments.
[0204] Example 1 may include a device comprising processing
circuitry coupled to storage, the processing circuitry configured
to: generate a channel sounding symbol comprising a first
subcarrier and a second subcarrier, wherein a first amplitude of
the first subcarrier is different than a second amplitude of the
second subcarrier; generate a channel sounding signal comprising
the channel sounding symbol; and send the channel sounding signal
to a second device.
[0205] Example 2 may include the device of example 1 and/or some
other example herein, wherein the channel sounding signal is a null
data packet (NDP).
[0206] Example 3 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a 16
quadrature amplitude modulation (QAM) constellation.
[0207] Example 4 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a 64
QAM constellation.
[0208] Example 5 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
256 QAM constellation.
[0209] Example 6 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
1024 QAM constellation.
[0210] Example 7 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using a
phase-shift keying (PSK) modulation.
[0211] Example 8 may include the device of example 1 and/or some
other example herein, wherein to generate the channel sounding
symbol comprises to generate the channel sounding symbol using
quadrature phase-shift keying (QPSK) modulation.
[0212] Example 9 may include the device of example 1 and/or some
other example herein, wherein the processing circuitry is further
configured to: generate a second channel sounding symbol comprising
a third subcarrier and a fourth subcarrier, wherein a third
amplitude of the third subcarrier is different than a fourth
amplitude of the fourth subcarrier, wherein the channel sounding
symbol further comprises the second channel sounding symbol.
[0213] Example 10 may include the device of example 1 and/or some
other example herein, wherein the processing circuitry is further
configured to: generate a secure high efficiency long training
field (HEz-LTF) comprising the channel sounding symbol, wherein the
channel sounding symbol further comprises the HEz-LTF.
[0214] Example 11 may include the device of example 1 and/or some
other example herein, further comprising a transceiver configured
to transmit and receive wireless signals.
[0215] Example 12 may include the device of example 1 and/or some
other example herein, further comprising an antenna coupled to the
transceiver to cause to send the channel sounding signal.
[0216] Example 13 may include a non-transitory computer-readable
medium storing computer-executable instructions which when executed
by one or more processors result in performing operations
comprising: generating, by a first device, a channel sounding
symbol comprising a first subcarrier and a second subcarrier,
wherein a first amplitude of the first subcarrier is different than
a second amplitude of the second subcarrier; generating, by the
first device, a channel sounding signal comprising the channel
sounding symbol; sending, by the first device, the channel sounding
signal to a second device.
[0217] Example 14 may include the non-transitory computer-readable
medium of example 13 and/or some other example herein, wherein the
channel sounding signal is a null data packet (NDP).
[0218] Example 15 may include the non-transitory computer-readable
medium of example 13 and/or some other example herein, wherein
generating the channel sounding symbol comprises generating the
channel sounding symbol using a 16 quadrature amplitude modulation
(QAM) constellation.
[0219] Example 16 may include the non-transitory computer-readable
medium of example 13 and/or some other example herein, wherein
generating the channel sounding symbol comprises generating the
channel sounding symbol using a 64 QAM or greater
constellation.
[0220] Example 17 may include the non-transitory computer-readable
medium of example 13 and/or some other example herein, wherein
generating the channel sounding symbol comprises generating the
channel sounding symbol using phase-shift keying (PSK)
modulation.
[0221] Example 18 may include the non-transitory computer-readable
medium of example 13 and/or some other example herein, wherein
generating the channel sounding symbol comprises generating the
channel sounding symbol using quadrature phase-shift keying (QPSK)
modulation.
[0222] Example 19 may include a method comprising: generating, by
processing circuitry of a first device, a channel sounding symbol
comprising a first subcarrier and a second subcarrier, wherein a
first amplitude of the first subcarrier is different than a second
amplitude of the second subcarrier; generating, by the processing
circuitry, a channel sounding signal comprising the channel
sounding symbol; sending, by the processing circuitry, the channel
sounding signal to a second device.
[0223] Example 20 may include the method of example 19 and/or some
other example herein, wherein generating the channel sounding
symbol comprises generating the channel sounding symbol using a 64
QAM or greater constellation.
[0224] Example 21 may include one or more non-transitory
computer-readable media comprising instructions to cause an
electronic device, upon execution of the instructions by one or
more processors of the electronic device, to perform one or more
elements of a method described in or related to any of examples
1-20, or any other method or process described herein.
[0225] Example 22 may include an apparatus comprising logic,
modules, and/or circuitry to perform one or more elements of a
method described in or related to any of examples 1-20, or any
other method or process described herein.
[0226] Example 23 may include a method, technique, or process as
described in or related to any of examples 1-20, or portions or
parts thereof.
[0227] Example 24 may include an apparatus comprising: one or more
processors and one or more computer readable media comprising
instructions that, when executed by the one or more processors,
cause the one or more processors to perform the method, techniques,
or process as described in or related to any of examples 1-20, or
portions thereof.
[0228] Example 25 may include a method of communicating in a
wireless network as shown and described herein.
[0229] Example 26 may include a system for providing wireless
communication as shown and described herein.
[0230] Example 27 may include a device for providing wireless
communication as shown and described herein.
[0231] Embodiments according to the disclosure are in particular
disclosed in the attached claims directed to a method, a storage
medium, a device and a computer program product, wherein any
feature mentioned in one claim category, e.g., method, can be
claimed in another claim category, e.g., system, as well. The
dependencies or references back in the attached claims are chosen
for formal reasons only. However, any subject matter resulting from
a deliberate reference back to any previous claims (in particular
multiple dependencies) can be claimed as well, so that any
combination of claims and the features thereof are disclosed and
can be claimed regardless of the dependencies chosen in the
attached claims. The subject-matter which can be claimed comprises
not only the combinations of features as set out in the attached
claims but also any other combination of features in the claims,
wherein each feature mentioned in the claims can be combined with
any other feature or combination of other features in the claims.
Furthermore, any of the embodiments and features described or
depicted herein can be claimed in a separate claim and/or in any
combination with any embodiment or feature described or depicted
herein or with any of the features of the attached claims.
[0232] The foregoing description of one or more implementations
provides illustration and description, but is not intended to be
exhaustive or to limit the scope of embodiments to the precise form
disclosed. Modifications and variations are possible in light of
the above teachings or may be acquired from practice of various
embodiments.
[0233] Certain aspects of the disclosure are described above with
reference to block and flow diagrams of systems, methods,
apparatuses, and/or computer program products according to various
implementations. It will be understood that one or more blocks of
the block diagrams and flow diagrams, and combinations of blocks in
the block diagrams and the flow diagrams, respectively, may be
implemented by computer-executable program instructions. Likewise,
some blocks of the block diagrams and flow diagrams may not
necessarily need to be performed in the order presented, or may not
necessarily need to be performed at all, according to some
implementations.
[0234] These computer-executable program instructions may be loaded
onto a special-purpose computer or other particular machine, a
processor, or other programmable data processing apparatus to
produce a particular machine, such that the instructions that
execute on the computer, processor, or other programmable data
processing apparatus create means for implementing one or more
functions specified in the flow diagram block or blocks. These
computer program instructions may also be stored in a
computer-readable storage media or memory that may direct a
computer or other programmable data processing apparatus to
function in a particular manner, such that the instructions stored
in the computer-readable storage media produce an article of
manufacture including instruction means that implement one or more
functions specified in the flow diagram block or blocks. As an
example, certain implementations may provide for a computer program
product, comprising a computer-readable storage medium having a
computer-readable program code or program instructions implemented
therein, said computer-readable program code adapted to be executed
to implement one or more functions specified in the flow diagram
block or blocks. The computer program instructions may also be
loaded onto a computer or other programmable data processing
apparatus to cause a series of operational elements or steps to be
performed on the computer or other programmable apparatus to
produce a computer-implemented process such that the instructions
that execute on the computer or other programmable apparatus
provide elements or steps for implementing the functions specified
in the flow diagram block or blocks.
[0235] Accordingly, blocks of the block diagrams and flow diagrams
support combinations of means for performing the specified
functions, combinations of elements or steps for performing the
specified functions and program instruction means for performing
the specified functions. It will also be understood that each block
of the block diagrams and flow diagrams, and combinations of blocks
in the block diagrams and flow diagrams, may be implemented by
special-purpose, hardware-based computer systems that perform the
specified functions, elements or steps, or combinations of
special-purpose hardware and computer instructions.
[0236] Conditional language, such as, among others, "can," "could,"
"might," or "may," unless specifically stated otherwise, or
otherwise understood within the context as used, is generally
intended to convey that certain implementations could include,
while other implementations do not include, certain features,
elements, and/or operations. Thus, such conditional language is not
generally intended to imply that features, elements, and/or
operations are in any way required for one or more implementations
or that one or more implementations necessarily include logic for
deciding, with or without user input or prompting, whether these
features, elements, and/or operations are included or are to be
performed in any particular implementation.
[0237] Many modifications and other implementations of the
disclosure set forth herein will be apparent having the benefit of
the teachings presented in the foregoing descriptions and the
associated drawings. Therefore, it is to be understood that the
disclosure is not to be limited to the specific implementations
disclosed and that modifications and other implementations are
intended to be included within the scope of the appended claims.
Although specific terms are employed herein, they are used in a
generic and descriptive sense only and not for purposes of
limitation.
* * * * *