U.S. patent application number 16/146931 was filed with the patent office on 2019-02-07 for secure sounding arrangement.
The applicant listed for this patent is INTEL IP CORPORATION. Invention is credited to DANNY ALEXANDER, ASSAF GUREVITZ, FENG JIANG, QINGHUA LI, JONATHAN SEGEV, ROBERT STACEY, SHLOMI VITURI.
Application Number | 20190045361 16/146931 |
Document ID | / |
Family ID | 65230143 |
Filed Date | 2019-02-07 |
View All Diagrams
United States Patent
Application |
20190045361 |
Kind Code |
A1 |
GUREVITZ; ASSAF ; et
al. |
February 7, 2019 |
SECURE SOUNDING ARRANGEMENT
Abstract
Methods and apparatuses for arranging sounding symbol are
provided. An example apparatus comprises memory; and processing
circuitry coupled to the memory. The processing circuitry is
configured to encode a sounding signal. The sounding signal
comprises a plurality of sounding symbols, and the repetition of
sounding symbols to be transmitted in sequence is avoided.
Inventors: |
GUREVITZ; ASSAF; (RAMAT
HASHARON, IL) ; STACEY; ROBERT; (PORTLAND, OR)
; SEGEV; JONATHAN; (TEL MOND, IL) ; LI;
QINGHUA; (SAN RAMON, CA) ; ALEXANDER; DANNY;
(NEVE EFRAIM MONOSON, IL) ; VITURI; SHLOMI; (TEL
AVIV, IL) ; JIANG; FENG; (SANTA CLARA, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTEL IP CORPORATION |
Santa Clara |
CA |
US |
|
|
Family ID: |
65230143 |
Appl. No.: |
16/146931 |
Filed: |
September 28, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62578763 |
Oct 30, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0048 20130101;
H04W 12/12 20130101; H04W 84/12 20130101; H04L 25/0226 20130101;
H04L 5/0007 20130101; H04W 12/08 20130101; H04L 27/2605 20130101;
H04L 27/2613 20130101; G01S 5/14 20130101; H04W 64/00 20130101;
G01S 11/02 20130101; H04L 25/03866 20130101; H04L 5/005
20130101 |
International
Class: |
H04W 12/08 20060101
H04W012/08; H04L 27/26 20060101 H04L027/26; H04L 5/00 20060101
H04L005/00; H04W 64/00 20060101 H04W064/00 |
Claims
1. An apparatus, comprising: a memory; and a processing circuitry
coupled to the memory, the processing circuity is configured to:
encode a sounding signal, wherein the sounding signal comprises a
plurality of sounding symbols, the repetition of sounding symbols
to be transmitted in sequence is avoided.
2. The apparatus according to claim 1, wherein intra symbol
repetition is avoided by applying zero-prefix for each sounding
symbol, and wherein inter symbol repetition is avoided by applying
masking sequence different from each other for each sounding
symbol.
3. The apparatus according to claim 1, wherein the apparatus
comprises two or more antennas, each of the antennas is to transmit
encoded sounding symbols based on the plurality of sounding
symbols, wherein for each antenna, the encoded sounding symbols in
different time slots are different, wherein for each time slot, the
encoded sounding symbols on the two or more antennas are repeated,
with different global phases determined by a general phase
matrix.
4. The apparatus according to claim 1, wherein the sounding signal
is encoded for two or more users and to be transmitted to the two
or more users, wherein the sounding symbols for different users are
transmitted over different time slots and/or over different
frequencies.
5. The apparatus according to claim 4, wherein all sounding symbols
for a first user are followed by any sounding symbol for a second
user.
6. The apparatus according to claim 4, wherein the sounding symbols
for different users are to be transmitted in an interleaved
approach, wherein transmitting of the sounding symbols for
different users comprising: transmitting a first number of sounding
symbols for a first user; transmitting a second number of sounding
symbols for a second user; transmitting a third number of sounding
symbols for the first user; and transmitting a fourth number of
sounding symbols for the second user.
7. The apparatus according to claim 1, wherein the processing
circuity is further configured to: record the Time of Departure
(ToD) information of the sounding signal; obtain the Time of
Arrival (ToA) information of the sounding signal from a receiving
device; calculate the distance between the apparatus and the
receiving device based on at least the ToD information and the ToA
information; and encode an unlocking signal if the calculated
distance is less than a predetermined threshold, to unlock a locked
device.
8. The apparatus according to claim 1, wherein the sounding signal
is to be transmitted after transmitting Null Data Packet
Announcement (NDPA), which is used to indicate the structure of the
sounding signal to be transmitted.
9. The apparatus according to claim 1, wherein the apparatus is any
one of access point (AP), station, and cellular base station.
10. The apparatus according to claim 4, wherein the apparatus is
configured as an AP or cellular base station, and wherein the
processing circuity is configured to: encode the sounding signal in
response to an uplink sounding signal received from a station.
11. A method performed by a wireless enabled apparatus, comprising:
encoding a sounding signal, wherein the sounding signal comprises a
plurality of sounding symbols, the repetition of sounding symbols
to be transmitted in sequence is avoided.
12. The method according to claim 11, wherein the apparatus
comprises two or more antennas, the method further comprising each
of the antennas is to transmit encoded sounding symbols based on
the plurality of sounding symbols, wherein for each antenna, the
encoded sounding symbols in different time slots are different,
wherein for each time slot, the encoded sounding symbols on the two
or more antennas are repeated, with different global phases
determined by a general phase matrix.
13. The method according to claim 11, further comprising encoding
the sounding signal for two or more users and transmitting the
encoded sounding signal to the two or more users, wherein the
sounding symbols for different users are transmitted over different
time slots and/or over different frequencies.
14. The method according to claim 13, wherein all sounding symbols
for a first user are followed by any sounding symbol for a second
user.
15. The method according to claim 13, wherein the sounding symbols
for different users are to be transmitted in an interleaved
approach, wherein transmitting of the sounding symbols for
different users comprising: transmitting a first number of sounding
symbol for a first user; transmitting a second number of sounding
symbol for a second user; transmitting a third number of sounding
symbol for the first user; and transmitting a fourth number of
sounding symbol for the second user.
16. A non-transitory computer-readable medium storing
computer-executable instructions which when executed by one or more
processors of an apparatus result in performing operations
comprising: encoding a sounding signal, wherein the sounding signal
comprises a plurality of sounding symbols, the repetition of
sounding symbols to be transmitted in sequence is avoided.
17. The non-transitory computer-readable medium of claim 10,
wherein the apparatus comprises two or more antennas, the method
further comprising each of the antennas is to transmit encoded
sounding symbols based on the plurality of sounding symbols,
wherein for each antenna, the encoded sounding symbols in different
time slots are different, wherein for each time slot, the encoded
sounding symbols on the two or more antennas are repeated, with
different global phases determined by a general phase matrix.
18. The non-transitory computer-readable medium of claim 10,
further comprising encoding the sounding signal for two or more
users and transmitting the encoded sounding signal to the two or
more users, wherein the sounding symbols for different users are
transmitted over different time slots and/or over different
frequencies.
19. The non-transitory computer-readable medium of claim 10,
wherein all sounding symbols for a first user are followed by any
sounding symbol for a second user.
20. The non-transitory computer-readable medium of claim 10,
wherein the sounding symbols for different users are to be
transmitted in an interleaved approach, wherein transmitting of the
sounding symbols for different users comprising: transmitting a
first number of sounding symbol for a first user; transmitting a
second number of sounding symbol for a second user; transmitting a
third number of sounding symbol for the first user; and
transmitting a fourth number of sounding symbol for the second
user.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/578,763 filed on Oct. 30, 2017, entitled "NULL
DATA PACKET (NDP) STRUCTURE FOR SECURE SOUNDING", the contents of
which are herein incorporated by reference in their entirety.
BACKGROUND
[0002] Null data packet (NDP) has been adopted as a sounding
signal. However, the details about the sounding signal are missing.
Especially for multiuser (MU) downlink sounding, no solution was
discussed.
[0003] A P-matrix structure defined in IEEE 802.11n/ac/ax or
802.11mc specification fails to be reused for secure MU downlink
sounding. In the case of such P-matrix structure is used, if one of
the users is an attacker, other users are vulnerable to security
attacks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is an illustration of the transmission of
communications in a wireless local area network (WLAN) using Wi-Fi
protocols between an example access point (AP) and example stations
(STAs) in accordance with some examples.
[0005] FIG. 2 illustrates an example sounding procedure for ranging
the distance between one example STA and the example AP in
accordance with some examples.
[0006] FIG. 3 illustrates an example sounding procedure for ranging
the distance between more than one (for example K) example STAs and
the example AP in accordance with some examples.
[0007] FIG. 4 illustrates a scenario of interfering attack.
[0008] FIG. 5 illustrates a scenario of cyclic prefix (CP) replay
attack.
[0009] FIG. 6 illustrates a scenario of P-matrix code replay
attack.
[0010] FIG. 7 illustrates an example NDP structure in accordance
with some examples.
[0011] FIG. 8 illustrates another example NDP structure for
combating the CP replay attack in accordance with some
examples.
[0012] FIG. 9 illustrates yet another example NDP structure for
combating the P-matrix code replay attack in accordance with some
examples.
[0013] FIG. 10 illustrates an example structure of a multi-antenna
sounding signal for a user in accordance with some examples.
[0014] FIG. 11 illustrates an example structure of a sounding
signal for multiple users in accordance with some examples.
[0015] FIG. 12 illustrates another example structure of a sounding
signal for multiple users in accordance with some examples.
[0016] FIG. 13 illustrates yet another example structure of a
sounding signal for multiple users in accordance with some
examples.
[0017] FIG. 14 is a block diagram of radio architecture in
accordance with some examples.
[0018] FIG. 15 illustrates an example front-end module circuitry
for use in the radio architecture of FIG. 14 in accordance with
some examples.
[0019] FIG. 16 illustrates an example radio IC circuitry for use in
the radio architecture of FIG. 14 in accordance with some
examples.
[0020] FIG. 17 illustrates an example baseband processing circuitry
for use in the radio architecture of FIG. 14 in accordance with
some examples.
[0021] FIG. 18 is a block diagram of an example processor platform
capable of transmitting the sounding signals shown in FIGS. 11-13,
to implement the example sounding procedure(s) of FIGS. 2 and/or 3
in accordance with some examples.
[0022] FIG. 19 illustrates an example flowchart of a method for
sounding in accordance with some examples.
[0023] The figures are not to scale. Wherever possible, the same
reference numbers will be used throughout the drawing(s) and
accompanying written description to refer to the same or like
parts.
DETAILED DESCRIPTION OF EMBODIMENTS
[0024] The present disclosure will now be described with reference
to the attached drawing figures, wherein like reference numerals
are used to refer to like elements throughout, and wherein the
illustrated structures and devices are not necessarily drawn to
scale. As utilized herein, terms "component," "system,"
"interface," and the like are intended to refer to a
computer-related entity, hardware, software (e.g., in execution),
and/or firmware. For example, a component can be a processor (e.g.,
a microprocessor, a controller, or other processing device), a
process running on a processor, a controller, an object, an
executable, a program, a storage device, a computer, a tablet PC
and/or a user equipment (e.g., mobile phone, etc.) with a
processing device. By way of illustration, an application running
on a server and the server can also be a component. One or more
components can reside within a process, and a component can be
localized on one computer and/or distributed between two or more
computers. A set of elements or a set of other components can be
described herein, in which the term "a set of" can be interpreted
as "one or more".
[0025] Further, these components can execute from various computer
readable storage media having various data structures stored
thereon such as with a module, for example. The components can
communicate via local and/or remote processes such as in accordance
with a signal having one or more data packets (e.g., data from one
component interacting with another component in a local system,
distributed system, and/or across a network, such as, the Internet,
a local area network, a wide area network, or similar network with
other systems via the signal).
[0026] As another example, a component can be an apparatus with
specific functionality provided by mechanical parts operated by
electric or electronic circuitry, in which the electric or
electronic circuitry can be operated by a software application or a
firmware application executed by one or more processors. The one or
more processors can be internal or external to the apparatus and
can execute at least a part of the software or firmware
application. As yet another example, a component can be an
apparatus that provides specific functionality through electronic
components without mechanical parts; the electronic components can
include one or more processors therein to execute software and/or
firmware that confer(s), at least in part, the functionality of the
electronic components.
[0027] Use of the word "exemplary" is intended to present concepts
in a concrete fashion. As used in this application, the term "or"
is intended to mean an inclusive "or" rather than an exclusive
"or". That is, unless specified otherwise, or clear from context,
"X employs A or B" is intended to mean any of the natural inclusive
permutations. That is, if X employs A; X employs B; or X employs
both A and B, then "X employs A or B" is satisfied under any of the
foregoing instances. In addition, the articles "a" and "an" as used
in this application and the appended claims should generally be
construed to mean "one or more" unless specified otherwise or clear
from context to be directed to a singular form. Furthermore, to the
extent that the terms "including", "includes", "having", "has",
"with", or variants thereof are used in either the detailed
description and the claims, such terms are intended to be inclusive
in a manner similar to the term "comprising." Additionally, in
situations wherein one or more numbered items are discussed (e.g.,
a "first X", a "second X", etc.), in general the one or more
numbered items may be distinct or they may be the same, although in
some situations the context may indicate that they are distinct or
that they are the same.
[0028] As used herein, the term "circuitry" may refer to, be part
of, or include an Application Specific Integrated Circuit (ASIC),
an electronic circuit, a processor (shared, dedicated, or group),
and/or memory (shared, dedicated, or group) that execute one or
more software or firmware programs, a combinational logic circuit,
and/or other suitable hardware components that provide the
described functionality. In some embodiments, the circuitry may be
implemented in, or functions associated with the circuitry may be
implemented by, one or more software or firmware modules. In some
embodiments, circuitry may include logic, at least partially
operable in hardware.
[0029] Embodiments described herein may be implemented into a
system using any suitably configured hardware and/or software. FIG.
1 is an illustration of the transmission of communications in a
WLAN using Wi-Fi protocols between an example AP 100 and example
STAs 102 in accordance with some examples. The example AP 100
includes an example radio architecture 105A. The example STAs 102
each includes an example radio architecture 105B. Although FIG. 1
shows two STAs 102, the number of the example STAs 102 is not
limited, that is there can be more or less example STAs 102. FIG. 1
further includes an example network 106 and an example locked
device 101.
[0030] The example AP 100 of FIG. 1 is a device that allows the
example STAs 102 to wirelessly access the example network 106. The
example AP 100 may be a router, a modem-router, and/or any other
device that provides a wireless connection to a network. A router
provides a wireless communication link to a STA. The router may
access the network through a wire connection via a modem. A
modem-router combines the functionalities of the modem and the
router. The example AP 100 may include the example radio
architecture 105A. The example radio architecture 105A may
wirelessly transmit and receive data based on instructions from a
processor. The example radio architecture 105A is further described
below in conjunction with FIG. 14.
[0031] The example STAs 102 of FIG. 1 are Wi-Fi enabled computing
devices. The example STAs 102 may be, for example, a computing
device, a portable device, a mobile device, a mobile telephone, a
smart phone, a tablet, a gaming system, a digital camera, a digital
video recorder, a television, a set top box, an e-book reader,
and/or any other Wi-Fi enabled device. The example STAs 102 may
include the example radio architecture 105B and/or other processors
(e.g., the example application processor 1410 of FIG. 14). The
example radio architecture 105B is further described below in
conjunction with FIG. 14.
[0032] The example network 106 of FIG. 1 is a system of
interconnected systems exchanging data. The example network 106 may
be implemented using any type of public or private network such as,
but not limited to, the Internet, a telephone network, a local area
network (LAN), a cable network, and/or a wireless network. To
enable communication via the network 106, the example Wi-Fi AP 100
includes a communication interface that enables a connection to an
Ethernet, a digital subscriber line (DSL), a telephone line, a
coaxial cable, or any wireless connection, etc.
[0033] The example locked device 101 of FIG. 1 is a network enabled
device, which can be locked and unlocked by the example STA(s) 102.
The example locked device 101 includes a communication interface,
such as an example radio architecture 105C, that enables a
connection to an Ethernet, a digital subscriber line (DSL), a
telephone line, a coaxial cable, or any wireless connection,
etc.
[0034] In an example scenario, the example locked device 101 may be
implemented as a locked door. The example STA(s) 102 aims to unlock
the locked door. The distance between the example STA(s) 102 and
the locked door and/or the distance between the example STA(s) 102
and the example AP 100 is an important reference value for the
unlocking. For example, the door will be open automatically, if the
distance between the example STA 102 and the locked door is less
than 5 meters, and/or if the distance between the example STA 102
and the example AP 100 is less than 7 meters. In order to range
(i.e., measure) the distance between the example STA 102 and the
example AP 100 (or the example locked device 101), a sounding
procedure is used.
[0035] FIG. 2 illustrates an example sounding procedure for ranging
the distance between one example STA 102 and the example AP 100 in
accordance with some examples. In the example procedure, the
example STA 102 firstly sends a Null Data Packet Announcement
(NDPA) message, which may announce to the example AP 100 about the
coming Null Data Packet (NDP) and indicate to the example AP 100
about how to respond to the NDP. Then, the example STA 102 sends an
uplink (UL) sounding to the example AP 100. Then, upon receiving
the UL sounding, the example AP 100 may send a downlink (DL)
sounding as a response.
[0036] FIG. 3 illustrates an example sounding procedure for ranging
the distance between more than one (for example K) example STAs 102
and the example AP 100 in accordance with some examples. In the
polling phase, the example AP 100 polls the example STAs 102 and
finds the first STA, the second STA, . . . , the K.sup.th STA.
Then, the example AP 100 may send trigger signal to each of the
example STAs 102 in sequence, to trigger the UL sounding from each
of the example STAs 102. In response, each of the example STAs 102
sends an UL sounding to the example AP 100. After the example AP
100 solicits UL soundings from the all example STAs 102, the
example AP 100 sends an NDPA, which may indicate the structure of
the coming DL sounding. Furthermore, the sounding symbol
allocations for the STAs may be indicated in the NDPA so that the
STAs know where to find their sounding symbols. The sounding
symbols with the zero prefix or padding are placed right next to
each other instead of Short Interframe Space (SIFS) apart for high
efficiency.
[0037] Although FIGS. 2-3 show the example sounding procedures
between one or more example STAs 102 and the example AP 100, the
sounding procedure also can be performed between any two or more
entities. For example, in ranging mode, the example locked device
101 may act as an AP (or STA) as shown in FIGS. 2-3, and the
example STAs 102 may act as a STA (or AP) as shown in FIGS. 2-3.
For example, the door or the monitor may act as an AP as shown in
FIGS. 2-3, which sends out Wi-Fi beacons and wants the user device
to get associated with. The unlocking operation is based on the
distance between the ranging devices e.g. AP and STA as shown in
FIGS. 2-3 (or two STAs in mesh mode). Furthermore, in positioning
mode, the AP(s) as shown in FIGS. 2-3 may reside in a plurality of
network nodes, and the user device (STA) may measure the distance
between itself and the plurality of network nodes, in order to
position the AP(s). The AP(s) as shown in FIGS. 2-3 know the
position of the user device after the measurements. The unlocking
operation is based on the position.
[0038] In the above example sounding procedure illustrated in FIGS.
2-3, the STA(s) may record the time of departure (ToD) t1 of the UL
sounding and the time of arrival (ToA) t4 of the DL sounding; while
the AP may record the ToA t2 of the UL sounding and the ToD t3 of
the DL sounding. The STA(s) and the AP may use any technical
measure well known in this art such as time stamp to perform the
recording.
[0039] The recorded time t1-t4 may be collected by any one or more
of the AP and the STA(s) as shown in FIGS. 2-3, to calculate the
distance between the AP and the STA(s). Besides, for safety
purpose, one STA should not collect the data related to other
STA(s). For example, if the AP calculates the distance, the STA(s)
will send the recorded t1 and t4 to the AP. Besides, if the STA(s)
calculates the distance, the AP will send the recorded respective
t2 and t3 to the respective STA. After obtaining the time t1-t4,
any one or more of the AP and the STA(s) as shown in FIGS. 2-3 may
calculate the round trip time (RTT) as RTT=t4-t1-(t3-t2), and
calculate the distance as c*RTT/2, wherein c is the speed of
light.
[0040] If the calculated distance is less than a predetermined
distance, or the calculated RTT is less than a predetermined time,
any one or more of the AP and the STA(s) as shown in FIGS. 2-3 may
generate an unlocking instruction, and unlock the example locked
device 101 (e.g., locked door or locked screen) accordingly. In one
scenario, the door will be open automatically, if the calculated
distance between any of the example STA(s) 102 and the example
locked device 101 is less than 5 meters, or the calculated RTT is
less than 33 nanoseconds.
[0041] The above ranging procedure, for example, the sounding
procedure may be affected by a potential attacker. The attacker may
broadcast an interference or replayed signal, which is superposed
on the sounding single on the receiver's antenna, or send it to the
aimed receiver. Then, at the receiver, the ToA, such as t2 or t4,
of the sounding signal may be disturbed. For example, the
superposed signal may arrive earlier than the sounding signal,
which makes the recorded t2 and/t4 less than the actual ToA. As a
result, the calculated distance or RTT may become smaller than the
actual one. In one scenario, the calculated distance is 4 m while
the intended person is 24 m away from the door, that is, the door
may be open incorrectly, which give chance to the attacker.
[0042] FIGS. 4-6 show three example attack modes. FIG. 4
illustrates a scenario of interfering attack. In this scenario, a
desired transmitter 401, such as the AP as shown in FIGS. 2-3, may
send a DL sounding signal to a desired receiver 402, such as the
STA(s) as shown in FIGS. 2-3. An attacker 401' doesn't know what
the DL sounding signal looks like and just sends an arbitrary
signal such as a spike to interfere the DL sounding.
[0043] The effect of the attack is that multiple fake multipaths
(spikes with hollow triangle as indicated) present at the channel
estimate of the desired receiver 402. From the perspective of the
desired receiver 402, a fake multipath would be considered as the
first channel arrival from the desired transmitter 401, which is
earlier than that of the actual multipaths (spikes with solid
triangle as indicated). This may make the detected ToA at the
desired receiver 402 earlier than the actual one, and thus
jeopardize the security of ranging applications (e.g. door
unlocking and screen unlocking).
[0044] FIG. 5 illustrates a scenario of CP replay attack. In this
scenario, an attacker 501' takes advantage of the partial
repetitive structure of OFDM symbol, where the ending portion is
the repetition of the beginning portion (CP). The attacker 501'
records the beginning portion (CP) of the received sounding symbol,
which is an OFDM symbol in legacy modes transmitted by a desired
transmitter 501, and replays the recorded portion at the end of the
sounding symbol with a timing advancement. As a result, the timing
advancement creates a fake channel arrival earlier than the actual
one. This may make the detected ToA at the desired receiver earlier
than the actual one, and thus jeopardize the security of ranging
applications (e.g. door unlocking and screen unlocking).
[0045] FIG. 6 illustrates a scenario of P-matrix code replay
attack. In this scenario, an attacker also takes advantages of the
repetition in the P-matrix coded transmission. The sounding symbol
for each antenna is sent multiple times with different global
phases specified by the P-matrix code (e.g.
[ 1 1 1 - 1 ] ##EQU00001##
in this scenario). Even though one can send different sounding
symbols for different antennas, the attack can still be made as
illustrated in FIG. 6.
[0046] For example, according to the global phase specified by the
P-matrix code, AP antenna 1 transmits a first and second sounding
symbol A and another A, and AP antenna 2 transmits a first and
second sounding symbols B and -B. At the first place, an attacker
did not know what the sounding signals look like. Then, the
attacker records the first received sounding symbol R1, which is a
superimposition of the first sounding symbols for above described
two antennas (i.e. A+B), and then it can replay the overlapped
signal and a timing advancement to deceive the desired receivers
(not shown in FIG. 6). This may make the detected ToA at the
desired receiver earlier than the actual one, and thus jeopardize
the security of ranging applications (e.g. door unlocking and
screen unlocking).
[0047] What is worse, the attacker keeps recording the second
received sounding symbol R2 (i.e. A-B) and obtains two overlapped
signals in sequence. By decoding these two received overlapped
sounding symbols with linear equation in two unknowns, the attacker
can easily derive what the two original sounding symbols exactly
are, i.e. A=(R1+R2)/2, and B=(R1-R2)/2. In this example, the
channel responses are the unity for the simplicity of
illustration.
[0048] In a more ordinary case, there are more than two kinds of
sounding symbols transmitted from two or more antennas. However,
the attacker might still be able to decode the original sounding
symbols (i.e. solve linear equation in multiple unknowns). Say
there are four symbols x0, x1, x2, and x3 which are unknown to the
attacker, and the P-matrix is
[ 1 - 1 1 1 1 1 - 1 1 1 1 1 - 1 - 1 1 1 1 ] . ##EQU00002##
After recording these four symbols overlapped with each other in
four time slots, the attacker can obtain four superimpositions (say
W, X, Y, and Z). Hence, four original sounding symbols would be
decoded as x0=(W+X+Y-Z)/4, x1=(-W+X+Y+Z)/4, x2=(W-X+Y+Z)/4, and
x3=(W+X-Y+Z)/4.
[0049] Note that, in the above example attack modes, the distance
estimation uses the whole sounding signal instead of the first
samples arrived. For example, the sounding signal is a sinusoid
wave with one period. In a matched filter implementation, the
receiver matches the locally generated sinusoid wave with the
received sinusoid wave. If a matched waveform is detected, the
signal arrival is declared. Therefore, the attacker can record the
CP and replay it when the receiver still receives signal, even
though the beginning part of the signal was already received.
[0050] FIG. 7 illustrates an example NDP structure in accordance
with some examples. To prevent the above three attacks (illustrated
in FIGS. 4-6), the legacy sounding signal is modified, e.g.
802.11ax NDP, for 802.11az (or 802.11mc) secure mode. The sounding
signal structure in this embodiment is illustrated in FIG. 7. The
legacy portion can be the same as 802.11ax's
"L-STF+L-LTF+L-SIG+RL-SIG+HE-SIG-A" or 802.11ac's NDP beginning
portions before VHT-STF. The legacy portion is for backward
compatibility. The 802.11az portion can start by a short training
field (STF) for setting the receiver's automatic gain control
(AGC). The 802.11az STF can reuse 802.11ax's HE-STF (high
efficiency long training field) or 802.11ac's VHT-STF (very high
throughput short training field). After the STF, there are multiple
sounding symbols as illustrated in FIG. 7.
[0051] FIG. 8 illustrates another example NDP structure for
combating the CP replay attack in accordance with some examples.
For combating the CP replay attack, there is no CP in each sounding
symbol as illustrated in FIG. 8. Namely, there is no sub-symbol
level repetition in the sounding symbol. Furthermore, for each
sounding symbol, zero prefix of padding is used to combat the
inter-symbol interference.
[0052] FIG. 9 illustrates yet another example NDP structure for
combating the P-matrix code replay attack in accordance with some
examples. For combating P-matrix code replay, any repetition at the
symbol level is removed. Namely, the sounding symbols are all
different. One example for generating the sounding symbols is
illustrated in FIG. 9. In frequency domain, a common sounding
sequence e.g. the legacy HE-LTF sequence may be XOR with a masking
sequence bit by bit. When the common sounding sequence is the
sequence with all one or zero bits, the masking step can be skipped
and the generated sequence is just the same or opposite of the
masking sequence. It should be noticed that the masking sequence
has 39 bits in total, in which 30 bits are used for controlling the
shape of each sounding symbol and remain 9 bits are used for random
shifting. That is to say, with the masking sequence, billions of
(i.e. 2.sup.30) different sounding symbols could be generated,
which makes the attacker impossible to interpret one by one from so
many combinations. After the bit-by-bit XOR masking, the bits are
mapped to modulation constellations and the mapped constellation
symbols are loaded to the subcarriers of the sounding symbol. After
the loading, the frequency domain signal is converted to the time
domain. Instead of CP, zero-prefix or padding is added. Finally,
the global phase of the sounding symbol is applied according to the
corresponding entry of the P-matrix code.
[0053] FIG. 10 illustrates an example structure of a multi-antenna
sounding signal for a user in accordance with some examples. FIG.
11 illustrates an example structure of a sounding signal for
multiple users in accordance with some examples. FIG. 12
illustrates another example structure of a sounding signal for
multiple users in accordance with some examples. FIG. 13
illustrates yet another example structure of a sounding signal for
multiple users in accordance with some examples.
[0054] For combating the P-matrix replay attack, the sounding
signals for different users may be separated in time domain (or
frequency domain) not in P-matrix code domain, as illustrated in
FIGS. 11-13. For the same user, the sounding symbols for different
antennas can be multiplexed by P-matrix codes with different
masking sequences across sounding symbols, as illustrated in FIG.
10.
[0055] For combating the interfering attack, each antenna may sound
the channel multiple times within the channel coherence time, as
illustrated in FIGS. 11-13. It should be noticed that the sounding
signal should be different over time for preventing replay attacks.
The receiver of the soundings checks the consistency of the channel
estimates for identifying attacks. If there are no attacks, the
channel estimates should remain the same. If there is an attack,
the channel estimates are likely to be different because the
attacker could not vary the interfering signal following the
desired transmitter's varying signal for generating fake multipaths
consistently over time. It should be noticed that the varying
sounding signal is unknown to the attacker.
[0056] As shown in FIG. 10, each antenna sends a sounding symbol
set, which includes a series of the sounding symbols. For each
antenna, the sounding symbols are different, i.e., no repetition
structure. For example, 1.sup.st sounding symbol of 1.sup.st
antenna and N.sup.th sounding symbol of 1.sup.st antenna are
different. At each symbol time slot, the sounding symbols for all
the antennas of the same user can be the same except that their
global phases may be different. For example, 1.sup.st sounding
symbol of 1.sup.st antenna for 1.sup.st user and 1.sup.st sounding
symbol of N.sup.th antenna for 1.sup.st user can be the same except
a global phase difference. For example, the masking sequence in
FIG. 9 can be the same for all symbols in the same symbol time slot
for the same user.
[0057] In one scenario, the following P-matrix can be applied for
sounding with 4 antennas:
[ 1 - 1 1 1 1 1 - 1 1 1 1 1 - 1 - 1 1 1 1 ] . ##EQU00003##
For the first antenna, for example, symbol x0, -x1, x2, x3 can be
sent; for the second antenna, for example, symbol x0, x1, -x2, x3
can be sent; for the third antenna, for example, symbol x0, x1, x2,
-x3 can be sent; for the fourth antenna, for example, symbol -x0,
x1, x2, x3 can be sent.
[0058] For example, the AP(s) as shown in FIGS. 2-3 send DL
sounding via its 2 antennas for 1.sup.st user (or 1.sup.st STA) and
2.sup.nd user (or 2.sup.nd STA) by using 8 symbol time slots. Each
sounding symbol set consists of 2 symbol time slots with sounding
signals for the 2 AP antennas and for one user. Then, 4 sounding
symbol sets can be formed and 2 for each user (or each STA). The DL
sounding for each user may be sent sequentially as illustrated in
FIG. 11. Namely, 2 sounding symbol sets for 1.sup.st user are sent
followed by the 2 sets for 2.sup.nd user.
[0059] For providing more processing time for the latter users,
e.g., 2.sup.nd user (or 2.sup.nd STA), the sounding symbol set or
even sounding symbol may be interleaved as shown in FIG. 12. All
users receive their sounding symbol sets before any repeated
sounding symbol sets. Namely, the transmitter of AP finishes one
round of soundings for all users first and then repeats the
soundings for another round.
[0060] Furthermore, as shown in FIG. 13, the sounding signal for
multiple users may be arranged at frequency domain (subcarriers of
OFDM), rather than time domain. For example, the whole bandwidth of
the AP(s) as shown in FIGS. 2-3 is divided for each user (STA). For
example, the whole bandwidth of the AP is 80 MHz, and there are 4
STAs, then each STA may take 20 MHz. That is, the DL sounding for
each user occupies one fourth of whole number of the
subcarriers.
[0061] Note that, the above examples also can be applicable to the
cellular network. That is, the AP(s) as shown in FIGS. 2-3 may
implemented as evolved NodeB (eNB) or other types of base station
according to 3G, 4G, 5G or beyond.
[0062] For example, for positioning mode, three eNBs can be used to
determine the relative position of the STA(s) such as the example
STA(s) 102 to the eNBs by using the above sounding procedure. That
is, the STA(s) can be positioned by three base stations. Then,
according to the relative position of the STA(s), the distance
between the STA(s) and the example locked device 101 can be
calculated.
[0063] Note that, there can be more or less eNBs to determine the
relative position of the STA(s). For example, the eNB can determine
the distance and the arrival angle of the STA(s) by using the above
sounding procedure.
[0064] Then, the distance between the STA(s) and the example locked
device 101 can be calculated. Besides, other positioning
technologies by using sounding are also applicable.
[0065] FIG. 14 is a block diagram of radio architecture 105A, 105B,
105C in accordance with some examples. The radio architecture 105A,
105B, 105C may be implemented in any one of the example AP 100, the
example STAs 102, and the example locked device 101 of FIG. 1.
Radio architecture 105A, 105B, 105C may include radio front-end
module (FEM) circuitry 1404a-b, radio IC circuitry 1406a-b and
baseband processing circuitry 1408a-b. Radio architecture 105A,
105B, 105C 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.
[0066] FEM circuitry 1404a-b may include a WLAN or Wi-Fi FEM
circuitry 1404a and a Bluetooth (BT) FEM circuitry 1404b. The WLAN
FEM circuitry 1404a may include a receive signal path comprising
circuitry configured to operate on WLAN RF signals received from
one or more antennas 1401, to amplify the received signals and to
provide the amplified versions of the received signals to the WLAN
radio IC circuitry 1406a for further processing. The BT FEM
circuitry 1404b may include a receive signal path which may include
circuitry configured to operate on BT RF signals received from one
or more antennas 1401, to amplify the received signals and to
provide the amplified versions of the received signals to the BT
radio IC circuitry 1406b for further processing. FEM circuitry
1404a may also include a transmit signal path which may include
circuitry configured to amplify WLAN signals provided by the radio
IC circuitry 1406a for wireless transmission by one or more of the
antennas 1401. In addition, FEM circuitry 1404b may also include a
transmit signal path which may include circuitry configured to
amplify BT signals provided by the radio IC circuitry 1406b for
wireless transmission by the one or more antennas. In the
embodiment of FIG. 14, although FEM 1404a and FEM 1404b 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.
[0067] Radio IC circuitry 1406a-b as shown may include WLAN radio
IC circuitry 1406a and BT radio IC circuitry 1406b. The WLAN radio
IC circuitry 1406a may include a receive signal path which may
include circuitry to down-convert WLAN RF signals received from the
FEM circuitry 1404a and provide baseband signals to WLAN baseband
processing circuitry 1408a. BT radio IC circuitry 1406b may in turn
include a receive signal path which may include circuitry to
down-convert BT RF signals received from the FEM circuitry 1404b
and provide baseband signals to BT baseband processing circuitry
1408b. WLAN radio IC circuitry 1406a may also include a transmit
signal path which may include circuitry to up-convert WLAN baseband
signals provided by the WLAN baseband processing circuitry 1408a
and provide WLAN RF output signals to the FEM circuitry 1404a for
subsequent wireless transmission by the one or more antennas 1401.
BT radio IC circuitry 1406b may also include a transmit signal path
which may include circuitry to up-convert BT baseband signals
provided by the BT baseband processing circuitry 1408b and provide
BT RF output signals to the FEM circuitry 1404b for subsequent
wireless transmission by the one or more antennas 1401. In the
embodiment of FIG. 14, although radio IC circuitries 1406a and
1406b 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.
[0068] Baseband processing circuitry 1408a-b may include a WLAN
baseband processing circuitry 1408a and a BT baseband processing
circuitry 1408b. The WLAN baseband processing circuitry 1408a 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 1408a. Each of the
WLAN baseband circuitry 1408a and the BT baseband circuitry 1408b
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 1406a-b, and to also
generate corresponding WLAN or BT baseband signals for the transmit
signal path of the radio IC circuitry 1406a-b. Each of the baseband
processing circuitries 1408a and 1408b may further include physical
layer (PHY) and medium access control layer (MAC) circuitry, and
may further interface with the link aggregator for generation and
processing of the baseband signals and for controlling operations
of the radio IC circuitry 1406a-b.
[0069] Referring still to FIG. 14, according to the shown
embodiment, WLAN-BT coexistence circuitry 1413 may include logic
providing an interface between the WLAN baseband circuitry 1408a
and the BT baseband circuitry 1408b to enable use cases requiring
WLAN and BT coexistence. In addition, a switch 1403 may be provided
between the WLAN FEM circuitry 1404a and the BT FEM circuitry 1404b
to allow switching between the WLAN and BT radios according to
application needs. In addition, although the antennas 1401 are
depicted as being respectively connected to the WLAN FEM circuitry
1404a and the BT FEM circuitry 1404b, 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 1404a or 1404b.
[0070] In some embodiments, the front-end module circuitry 1404a-b,
the radio IC circuitry 1406a-b, and baseband processing circuitry
1408a-b may be provided on a single radio card, such as wireless
radio card 1402. In some other embodiments, the one or more
antennas 1401, the FEM circuitry 1404a-b and the radio IC circuitry
1406a-b may be provided on a single radio card. In some other
embodiments, the radio IC circuitry 1406a-b and the baseband
processing circuitry 1408a-b may be provided on a single chip or
integrated circuit (IC), such as IC 1412.
[0071] In some embodiments, the wireless radio card 1402 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, 105C 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.
[0072] In some of these multicarrier embodiments, radio
architecture 105A, 105B, 105C 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, 105C 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, 802.11ay 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, 105C may also be suitable to
transmit and/or receive communications in accordance with other
techniques and standards.
[0073] In some embodiments, the radio architecture 105A, 105B, 105C
may be configured for high-efficiency Wi-Fi (HEW) communications in
accordance with the IEEE 802.1ax standard. In these embodiments,
the radio architecture 105A, 105B, 105C may be configured to
communicate in accordance with an OFDMA technique, although the
scope of the embodiments is not limited in this respect.
[0074] In some other embodiments, the radio architecture 105A,
105B, 105C 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.
[0075] In some embodiments, the BT baseband circuitry 1408b 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.
[0076] In some embodiments, the radio architecture 105A, 105B, 105C
may include other radio cards, such as a cellular radio card
configured for cellular (e.g., 3GPP such as LTE, LTE-Advanced or 5G
communications).
[0077] In some IEEE 802.11 embodiments, the radio architecture
105A, 105B, 105C 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.
[0078] FIG. 15 illustrates an example front-end module circuitry
1404a for use in the radio architecture of FIG. 14 in accordance
with some examples. Although the example of FIG. 15 is described in
conjunction with the WLAN FEM circuitry 1404a, the example of FIG.
15 may be described in conjunction with the example BT FEM
circuitry 1404b (FIG. 14), although other circuitry configurations
may also be suitable.
[0079] In some embodiments, the FEM circuitry 1404a may include a
TX/RX switch 1502 to switch between transmit mode and receive mode
operation. The FEM circuitry 1404a may include a receive signal
path and a transmit signal path. The receive signal path of the FEM
circuitry 1404a may include a low-noise amplifier (LNA) 1506 to
amplify received RF signals 1503 and provide the amplified received
RF signals 1507 as an output (e.g., to the radio IC circuitry
1406a-b (FIG. 14)). The transmit signal path of the circuitry 1404a
may include a power amplifier (PA) to amplify input RF signals 1509
(e.g., provided by the radio IC circuitry 1406a-b), and one or more
filters 1512, such as band-pass filters (BPFs), low-pass filters
(LPFs) or other types of filters, to generate RF signals 1515 for
subsequent transmission (e.g., by one or more of the antennas 1401
(FIG. 14)) via an example duplexer 1514.
[0080] In some dual-mode embodiments for Wi-Fi communication, the
FEM circuitry 1404a 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 1404a may
include a receive signal path duplexer 1504 to separate the signals
from each spectrum as well as provide a separate LNA 1506 for each
spectrum as shown. In these embodiments, the transmit signal path
of the FEM circuitry 1404a may also include a power amplifier 1510
and a filter 1512, such as a BPF, an LPF or another type of filter
for each frequency spectrum and a transmit signal path duplexer
1504 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 1401 (FIG. 14). In some embodiments, BT
communications may utilize the 2.4 GHz signal paths and may utilize
the same FEM circuitry 1404a as the one used for WLAN
communications.
[0081] FIG. 16 illustrates an example radio IC circuitry 1406a for
use in the radio architecture of FIG. 14 in accordance with some
examples. The radio IC circuitry 1406a is one example of circuitry
that may be suitable for use as the WLAN or BT radio IC circuitry
1406a/1406b (FIG. 14), although other circuitry configurations may
also be suitable. Alternatively, the example of FIG. 16 may be
described in conjunction with the example BT radio IC circuitry
1406b.
[0082] In some embodiments, the radio IC circuitry 1406a may
include a receive signal path and a transmit signal path. The
receive signal path of the radio IC circuitry 1406a may include at
least mixer circuitry 1602, such as, for example, down-conversion
mixer circuitry, amplifier circuitry 1606 and filter circuitry
1608. The transmit signal path of the radio IC circuitry 1406a may
include at least filter circuitry 1612 and mixer circuitry 1614,
such as, for example, up-conversion mixer circuitry. Radio IC
circuitry 1406a may also include synthesizer circuitry 1604 for
synthesizing a frequency 1605 for use by the mixer circuitry 1602
and the mixer circuitry 1614. The mixer circuitry 1602 and/or 1614
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. 16 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 1614 may each
include one or more mixers, and filter circuitries 1608 and/or 1612
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.
[0083] In some embodiments, mixer circuitry 1602 may be configured
to down-convert RF signals 1507 received from the FEM circuitry
1404a-b (FIG. 14) based on the synthesized frequency 1605 provided
by synthesizer circuitry 1604. The amplifier circuitry 1606 may be
configured to amplify the down-converted signals and the filter
circuitry 1608 may include an LPF configured to remove unwanted
signals from the down-converted signals to generate output baseband
signals 1607. Output baseband signals 1607 may be provided to the
baseband processing circuitry 1408a-b (FIG. 14) for further
processing. In some embodiments, the output baseband signals 1607
may be zero-frequency baseband signals, although this is not a
requirement. In some embodiments, mixer circuitry 1602 may comprise
passive mixers, although the scope of the embodiments is not
limited in this respect.
[0084] In some embodiments, the mixer circuitry 1614 may be
configured to up-convert input baseband signals 1611 based on the
synthesized frequency 1605 provided by the synthesizer circuitry
1604 to generate RF output signals 1509 for the FEM circuitry
1404a-b. The baseband signals 1611 may be provided by the baseband
processing circuitry 1408a-b and may be filtered by filter
circuitry 1612. The filter circuitry 1612 may include an LPF or a
BPF, although the scope of the embodiments is not limited in this
respect.
[0085] In some embodiments, the mixer circuitry 1602 and the mixer
circuitry 1614 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 1604. In some
embodiments, the mixer circuitry 1602 and the mixer circuitry 1614
may each include two or more mixers each configured for image
rejection (e.g., Hartley image rejection). In some embodiments, the
mixer circuitry 1602 and the mixer circuitry 1614 may be arranged
for direct down-conversion and/or direct up-conversion,
respectively. In some embodiments, the mixer circuitry 1602 and the
mixer circuitry 1614 may be configured for super-heterodyne
operation, although this is not a requirement.
[0086] Mixer circuitry 1602 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 1507 from FIG. 16 may be down-converted to provide I and Q
baseband output signals to be sent to the baseband processor.
[0087] 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 1605 of synthesizer 1604 (FIG. 16). 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.
[0088] 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.
[0089] The RF input signal 1507 (FIG. 15) 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 1606 (FIG. 16)
or to filter circuitry 1608 (FIG. 16).
[0090] In some embodiments, the output baseband signals 1607 and
the input baseband signals 1611 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
1607 and the input baseband signals 1611 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.
[0091] 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.
[0092] In some embodiments, the synthesizer circuitry 1604 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 1604 may be a delta-sigma
synthesizer, a frequency multiplier, or a synthesizer comprising a
phase-locked loop with a frequency divider.
[0093] According to some embodiments, the synthesizer circuitry
1604 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 1604 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
1408a-b (FIG. 14) depending on the desired output frequency 1605.
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 1410.
[0094] In some embodiments, synthesizer circuitry 1604 may be
configured to generate a carrier frequency as the output frequency
1605, while in other embodiments, the output frequency 1605 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 1605 may be a LO frequency (fLO).
[0095] FIG. 17 illustrates an example baseband processing circuitry
1408a for use in the radio architecture of FIG. 14 in accordance
with some examples. The baseband processing circuitry 1408a is one
example of circuitry that may be suitable for use as the baseband
processing circuitry 1408a (FIG. 14), although other circuitry
configurations may also be suitable. Alternatively, the example of
FIG. 17 may be used to implement the example BT baseband processing
circuitry 1408b of FIG. 14.
[0096] The baseband processing circuitry 1408a may include a
receive baseband processor (RX BBP) 1702 for processing receive
baseband signals 1607 provided by the radio IC circuitry 1406a-b
(FIG. 14) and a transmit baseband processor (TX BBP) 1704 for
generating transmit baseband signals 1611 for the radio IC
circuitry 1406a-b. The baseband processing circuitry 1408a may also
include control logic 1706 for coordinating the operations of the
baseband processing circuitry 1408a.
[0097] In some embodiments (e.g., when analog baseband signals are
exchanged between the baseband processing circuitry 1408a-b and the
radio IC circuitry 1406a-b), the baseband processing circuitry
1408a may include ADC 1710 to convert analog baseband signals 1607
received from the radio IC circuitry 1406a-b to digital baseband
signals for processing by the RX BBP 1702. In these embodiments,
the baseband processing circuitry 1408a may also include DAC 1712
to convert digital baseband signals from the TX BBP 1704 to analog
baseband signals 1611.
[0098] In some embodiments that communicate OFDM signals or OFDMA
signals, such as through baseband processor 1408a, the transmit
baseband processor 1704 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 1702
may be configured to process received OFDM signals or OFDMA signals
by performing an FFT. In some embodiments, the receive baseband
processor 1702 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.
[0099] Referring back to FIG. 14, in some embodiments, the antennas
1401 (FIG. 14) 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 1401 may each include a set of phased-array
antennas, although embodiments are not so limited.
[0100] Although the radio architecture 105A, 105B, 105C 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.
[0101] FIG. 18 is a block diagram of an example processor platform
1800 capable of transmitting the sounding signals shown in FIGS.
11-13, to implement the example sounding procedure(s) of FIGS. 2
and/or 3 in accordance with some examples. The processor platform
1800 can be, for example, a server, a personal computer, a mobile
device (e.g., a cell phone, a smart phone, a tablet such as an
iPad.TM.), a personal digital assistant (PDA), an Internet
appliance, or any other type of computing device.
[0102] The processor platform 1800 of the illustrated example
includes a processor 1812. The processor 1812 of the illustrated
example is hardware. For example, the processor 1812 can be
implemented by one or more integrated circuits, logic circuits,
microprocessors, GPUs, DSPs, or controllers from any desired family
or manufacturer. The hardware processor may be a semiconductor
based (e.g., silicon based) device.
[0103] The processor 1812 of the illustrated example includes a
local memory 1813 (e.g., a cache). The processor 1812 of the
illustrated example is in communication with a main memory
including a volatile memory 1814 and a non-volatile memory 1816 via
a bus 1818. The volatile memory 1814 may be implemented by
Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random
Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)
and/or any other type of random access memory device. The
non-volatile memory 1816 may be implemented by flash memory and/or
any other desired type of memory device. Access to the main memory
1814, 1816 is controlled by a clock controller.
[0104] In some embodiments, the processor 1812 is configured to:
encode a sounding signal, wherein the sounding signal comprises a
plurality of sounding symbols, and wherein the repetition of
sounding symbols to be transmitted in sequence is avoided, as shown
in FIGS. 8-13. In some embodiments, the processor 1812 is
configured to perform any actions of the desired transmitter or
desired receiver as shown in FIGS. 1-13, such as the STAs and AP as
shown in FIGS. 2-3.
[0105] The processor platform 1800 of the illustrated example also
includes an interface circuit 1820. The interface circuit 1820 may
be implemented by any type of interface standard, such as an
Ethernet interface, a universal serial bus (USB), and/or a PCI
express interface.
[0106] In the illustrated example, one or more input devices 1822
are connected to the interface circuit 1820. The input device(s)
1822 permit(s) a user to enter data and commands into the processor
1812. The input device(s) can be implemented by, for example, a
sensor, a microphone, a camera (still or video), a keyboard, a
button, a mouse, a touchscreen, a track-pad, a trackball, isopoint
and/or a voice recognition system.
[0107] One or more output devices 1824 are also connected to the
interface circuit 1820 of the illustrated example. The output
devices 1824 can be implemented, for example, by display devices
(e.g., a light emitting diode (LED), an organic light emitting
diode (OLED), a liquid crystal display, a cathode ray tube display
(CRT), a touchscreen, a tactile output device, and/or speakers).
The interface circuit 1820 of the illustrated example, thus,
typically includes a graphics driver card, a graphics driver chip
or a graphics driver processor.
[0108] The interface circuit 1820 of the illustrated example also
includes a communication device such as a transmitter, a receiver,
a transceiver, a modem and/or network interface card to facilitate
exchange of data with external machines (e.g., computing devices of
any kind) via a network 1826 (e.g., an Ethernet connection, a
digital subscriber line (DSL), a telephone line, coaxial cable, a
cellular telephone system, etc.).
[0109] The processor platform 1800 of the illustrated example also
includes one or more mass storage devices 1828 for storing software
and/or data.
[0110] Examples of such mass storage devices 1828 include floppy
disk drives, hard drive disks, compact disk drives, Blu-ray disk
drives, RAID systems, and digital versatile disk (DVD) drives.
[0111] The coded instructions 1832 may be stored in the mass
storage device 1828, in the volatile memory 1814, in the
non-volatile memory 1816, and/or on a removable tangible computer
readable storage medium such as a CD or DVD.
[0112] FIG. 19 illustrates an example flowchart of a method 1900
for sounding, in accordance with some examples. In one embodiment,
the flow chart in FIG. 19 can be implemented in the processor
platform 1800 in FIG. 18.
[0113] The method 1900 may begin with step S1901, in which the
processor platform 1800, e.g., the processor 1812 may encode a
sounding signal, and then the processor platform 1800, e.g., the
interface circuit 1820 may transmit the encoded sounding signal.
The encoded sounding signal may comprise a plurality of sounding
symbols, in which the repetition of sounding symbols to be
transmitted in sequence is avoided.
[0114] Furthermore, as shown in FIG. 8, the intra symbol repetition
is avoided by applying zero-prefix for each sounding symbol, and as
shown in FIG. 9, the inter symbol repetition is avoided by applying
masking sequence different from each other for each sounding
symbol.
[0115] Furthermore, as shown in FIG. 10, the processor platform
1800 may comprise two or more antennas. For each antenna, the
encoded sounding symbols in different time slots are different. For
each time slot, the encoded sounding symbols on the two or more
antennas are repeated, with different global phases determined by a
general phase matrix, such as P-matrix. These sounding symbols
consists a sounding symbol set for a single user.
[0116] Furthermore, as shown in FIGS. 2 and 3, the sounding signal
may be transmitted after transmitting NDPA, which is used to
indicate the structure of the sounding signal to be
transmitted.
[0117] The processor platform 1800 may be configured as any one of
Wi-Fi AP, station, or cellular base station, such as the example AP
100, the example STA(s) 102, the example locked device 103, or an
example eNodeB. The encoded sounding signal may be configured as UL
sounding or DL sounding.
[0118] In particular, for DL sounding, the processor platform 1800
may transmit the DL sounding signal for multiple users. The DL
sounding symbols for different users are transmitted over different
time slots and/or over different frequencies, as shown in FIGS.
11-13.
[0119] In an example case in which sounding symbols for different
users are transmitted over different frequencies, the sounding
symbols for each user can be transmitted on respective subcarriers.
The sounding symbols for multiple users can be transmitted on the
same time slots, as shown in FIG. 13.
[0120] In an example case in which sounding symbols for different
users are transmitted over different time slots, all sounding
symbols for a first user may be followed by any sounding symbol for
a second user, as shown in FIG. 11.
[0121] In another example case in which sounding symbols for
different users are transmitted over different time slots, the
sounding symbols for different users may be transmitted in an
interleaved approach. That is, the processor platform 1800 may
transmit a first number of sounding symbol for a first user; then
transmit a second number of sounding symbol for a second user; then
transmit a third number of sounding symbol for the first user; and
then transmit a fourth number of sounding symbol for the second
user, as shown in FIG. 12.
[0122] Furthermore, for DL sounding, the processor platform 1800
may be configured to encode the sounding signal in response to an
uplink sounding signal received from the STA(s), as shown in FIG.
3.
[0123] Then, the method 1900 may proceed to step S1902, after
transmitting and receiving the UL and DL sounding, the processor
platform 1800 may collect the ToA and ToD of the UL and DL sounding
signal.
[0124] Then, the method 1900 may proceed to step S1903, the
processor platform 1800 may calculate the distance between the two
devices such AP and STA(s) as shown in FIGS. 2-3, based on the
collected the ToA and ToD of the UL and DL sounding signal, by
using the calculation described in combination to FIGS. 2 and
3.
[0125] Then, the method 1900 may proceed to step S1904, the
calculated distance is compared with a predetermined threshold. In
one scenario, the predetermined threshold may be 5 m for unlocking
a door. If the calculated distance is greater than the
predetermined threshold, the processor platform 1800 may perform
the next sounding, since the distance is not near enough.
Otherwise, the processor platform 1800 may encode an unlocking
signal, to unlock a locked device, such as the example locked
device 101.
[0126] The above steps are only examples, and the processor
platform 1800 can perform any actions described in connection to
FIGS. 1-13, to perform a secure sounding procedure.
[0127] Examples herein can include subject matter such as a method,
means for performing acts or blocks of the method, at least one
machine-readable medium including executable instructions that,
when performed by a machine (e.g., a processor with memory, an
application-specific integrated circuit (ASIC), a field
programmable gate array (FPGA), or the like) cause the machine to
perform acts of the method or of an apparatus or system for
concurrent communication using multiple communication technologies
according to embodiments and examples described.
[0128] Example 1 is an apparatus, comprising: a memory; and a
processing circuitry coupled to the memory, the processing circuity
is configured to: encode a sounding signal, wherein the sounding
signal comprises a plurality of sounding symbols, the repetition of
sounding symbols to be transmitted in sequence is avoided.
[0129] Example 2 comprises the subject matter of any variation of
example 1, wherein intra symbol repetition is avoided by applying
zero-prefix for each sounding symbol, and wherein inter symbol
repetition is avoided by applying masking sequence different from
each other for each sounding symbol.
[0130] Example 3 comprises the subject matter of any variation of
example 1 or example 2, wherein the apparatus comprises two or more
antennas, each of the antennas is to transmit encoded sounding
symbols based on the plurality of sounding symbols, wherein for
each antenna, the encoded sounding symbols in different time slots
are different, wherein for each time slot, the encoded sounding
symbols on the two or more antennas are repeated, with different
global phases determined by a general phase matrix.
[0131] Example 4 comprises the subject matter of any variation of
any of examples 1-3, wherein the sounding signal is encoded for two
or more users and to be transmitted to the two or more users,
wherein the sounding symbols for different users are transmitted
over different time slots and/or over different frequencies.
[0132] Example 5 comprises the subject matter of any variation of
example 4, wherein all sounding symbols for a first user are
followed by any sounding symbol for a second user.
[0133] Example 6 comprises the subject matter of any variation of
example 4, wherein the sounding symbols for different users are to
be transmitted in an interleaved approach, wherein transmitting of
the sounding symbols for different users comprising: transmitting a
first number of sounding symbols for a first user; transmitting a
second number of sounding symbols for a second user; transmitting a
third number of sounding symbols for the first user; and
transmitting a fourth number of sounding symbols for the second
user.
[0134] Example 7 comprises the subject matter of any variation of
any of examples 1-6, wherein the processing circuity is further
configured to: record the Time of Departure (ToD) information of
the sounding signal; obtain the Time of Arrival (ToA) information
of the sounding signal from a receiving device; calculate the
distance between the apparatus and the receiving device based on at
least the ToD information and the ToA information; and encode an
unlocking signal if the calculated distance is less than a
predetermined threshold, to unlock a locked device.
[0135] Example 8 comprises the subject matter of any variation of
any of examples 1-7, wherein the sounding signal is to be
transmitted after transmitting Null Data Packet Announcement
(NDPA), which is used to indicate the structure of the sounding
signal to be transmitted.
[0136] Example 9 comprises the subject matter of any variation of
any of examples 1-3 and 7-8, wherein the apparatus is any one of
access point (AP), station, and cellular base station.
[0137] Example 10 comprises the subject matter of any variation of
any of examples 4-6, wherein the apparatus is configured as an AP
or cellular base station, and wherein the processing circuity is
configured to: encode the sounding signal in response to an uplink
sounding signal received from a station.
[0138] Example 11 is a method performed by a wireless enabled
apparatus, comprising: encoding a sounding signal, wherein the
sounding signal comprises a plurality of sounding symbols, the
repetition of sounding symbols to be transmitted in sequence is
avoided.
[0139] Example 12 comprises the subject matter of any variation of
example 11, wherein the step of encoding further comprising:
applying zero-prefix for each sounding symbol to avoid intra symbol
repetition; applying masking sequence different from each other for
each sounding symbol to avoid inter symbol repetition.
[0140] Example 13 comprises the subject matter of any variation of
example 11 or 12, wherein the apparatus comprises two or more
antennas, the method further comprising each of the antennas is to
transmit encoded sounding symbols based on the plurality of
sounding symbols, wherein for each antenna, the encoded sounding
symbols in different time slots are different, wherein for each
time slot, the encoded sounding symbols on the two or more antennas
are repeated, with different global phases determined by a general
phase matrix.
[0141] Example 14 comprises the subject matter of any variation of
any of examples 11-13, further comprising encoding the sounding
signal for two or more users and transmitting the encoded sounding
signal to the two or more users, wherein the sounding symbols for
different users are transmitted over different time slots and/or
over different frequencies.
[0142] Example 15 comprises the subject matter of any variation of
example 14, wherein all sounding symbols for a first user are
followed by any sounding symbol for a second user.
[0143] Example 16 comprises the subject matter of any variation of
example 14, wherein the sounding symbols for different users are to
be transmitted in an interleaved approach, wherein transmitting of
the sounding symbols for different users comprising: transmitting a
first number of sounding symbol for a first user; transmitting a
second number of sounding symbol for a second user; transmitting a
third number of sounding symbol for the first user; and
transmitting a fourth number of sounding symbol for the second
user.
[0144] Example 17 comprises the subject matter of any variation of
any of examples 11-16, the method further comprising: recording the
Time of Departure (ToD) information of the sounding signal;
obtaining the Time of Arrival (ToA) information of the sounding
signal from a receiving device; calculating the distance between
the apparatus and the receiving device based on at least the ToD
information and the ToA information; and encoding an unlocking
signal if the calculated distance is less than a predetermined
threshold, to unlock a locked device.
[0145] Example 18 comprises the subject matter of any variation of
any of examples 11-17, wherein the sounding signal is to be
transmitted after transmitting Null Data Packet Announcement
(NDPA), which is used to indicate the structure of the sounding
signal to be transmitted.
[0146] Example 19 comprises the subject matter of any variation of
any of examples 11-13 and 17-18, wherein the apparatus is any one
of access point (AP), station, and cellular base station.
[0147] Example 20 comprises the subject matter of any variation of
any of examples 14-16, wherein the apparatus is configured as an AP
or cellular base station, and wherein the step of encoding a
sounding signal further comprising: encoding the sounding signal in
response to an uplink sounding signal received from a station.
[0148] Example 21 is a non-transitory computer readable medium,
having stored thereon instructions, which when executed cause a
computing device to perform the method according to any one of
examples 11-20.
[0149] The above description of illustrated embodiments of the
subject disclosure, including what is described in the Abstract, is
not intended to be exhaustive or to limit the disclosed embodiments
to the precise forms disclosed. While specific embodiments and
examples are described herein for illustrative purposes, various
modifications are possible that are considered within the scope of
such embodiments and examples, as those skilled in the relevant art
can recognize.
[0150] In this regard, while the disclosed subject matter has been
described in connection with various embodiments and corresponding
Figures, where applicable, it is to be understood that other
similar embodiments can be used or modifications and additions can
be made to the described embodiments for performing the same,
similar, alternative, or substitute function of the disclosed
subject matter without deviating therefrom. Therefore, the
disclosed subject matter should not be limited to any single
embodiment described herein, but rather should be construed in
breadth and scope in accordance with the appended claims below.
[0151] In particular regard to the various functions performed by
the above described components or structures (assemblies, devices,
circuits, systems, etc.), the terms (including a reference to a
"means") used to describe such components are intended to
correspond, unless otherwise indicated, to any component or
structure which performs the specified function of the described
component (e.g., that is functionally equivalent), even though not
structurally equivalent to the disclosed structure which performs
the function in the herein illustrated exemplary implementations.
In addition, while a particular feature may have been disclosed
with respect to only one of several implementations, such feature
may be combined with one or more other features of the other
implementations as may be desired and advantageous for any given or
particular application.
* * * * *