U.S. patent application number 15/052337 was filed with the patent office on 2016-06-16 for phase rotation for preambles within multiple user, multiple access, and/or mimo wireless communications.
This patent application is currently assigned to BROADCOM CORPORATION. The applicant listed for this patent is BROADCOM CORPORATION. Invention is credited to Vinko Erceg, Min Chuin Hoo, Jun Zheng.
Application Number | 20160173305 15/052337 |
Document ID | / |
Family ID | 45697248 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160173305 |
Kind Code |
A1 |
Zheng; Jun ; et al. |
June 16, 2016 |
Phase rotation for preambles within multiple user, multiple access,
and/or MIMO wireless communications
Abstract
Phase rotation for preambles within multiple user, multiple
access, and/or MIMO wireless communications. An appropriately
designed phase rotation vector and/or appropriately designed cyclic
shift delays (CSDs) are applied to respective sub-band components
of the preamble. With appropriately designed CSDs, certain fields
within the preamble are not modified. For example, a legacy short
training field (L-STF) of the preamble is not changed when using
appropriately designed CSDs. The respective CSDs may be implemented
as integer multiples of a common CSD (e.g., 0.times.CSD,
1.times.CSD, 2.times.CSD, etc. such that one of the values of such
a CSD vector may be zero [0], another may be the common CSD itself,
etc.). Also, by employing an appropriately designed phase rotation
vector and integer multiples of a CSD to a preamble, the respective
peak to average power ratio (PAPR) between different respective
fields within the preamble may be minimized.
Inventors: |
Zheng; Jun; (San Diego,
CA) ; Hoo; Min Chuin; (Mountain View, CA) ;
Erceg; Vinko; (Cardiff by the Sea, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BROADCOM CORPORATION |
Irvine |
CA |
US |
|
|
Assignee: |
BROADCOM CORPORATION
IRVINE
CA
|
Family ID: |
45697248 |
Appl. No.: |
15/052337 |
Filed: |
February 24, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14585305 |
Dec 30, 2014 |
9276790 |
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15052337 |
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13217830 |
Aug 25, 2011 |
8934572 |
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14585305 |
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61378769 |
Aug 31, 2010 |
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Current U.S.
Class: |
375/325 |
Current CPC
Class: |
H04L 5/0026 20130101;
H04L 5/0048 20130101; H04L 25/03866 20130101; H04L 27/227 20130101;
H04L 27/2621 20130101; H04L 27/20 20130101; H04L 27/2613 20130101;
H04B 7/084 20130101 |
International
Class: |
H04L 27/227 20060101
H04L027/227; H04B 7/08 20060101 H04B007/08 |
Claims
1. A wireless communication device comprising: a processor
configured to: receive, from another wireless communication device,
a first sub-band component of a signal via a first sub-band of a
communication channel, wherein the signal includes a plurality of
sub-components including the first sub-band component and a second
one or more sub-band components, wherein the second one or more
sub-band components have undergone rotation based on a phase
rotation vector, and wherein the first sub-band component and the
second one or more sub-band components of the signal have undergone
cyclic shift delay (CSD); receive a second sub-band component of
the signal via a second sub-band of the communication channel; and
process the first sub-band component and the second one or more
sub-band components of the signal based on the CSD and the phase
rotation vector to recover data transmitted from the another
wireless communication device.
2. The wireless communication device of claim 1, wherein the
processor is further configured to: receive a third sub-band
component of the signal via a third sub-band of the communication
channel; receive a fourth sub-band component of the signal via a
fourth sub-band of the communication channel; and process the first
sub-band component, the second sub-band component, the third
sub-band component, and the fourth sub-band component based on the
CSD and the phase rotation vector to recover the data transmitted
from the another wireless communication device.
3. The wireless communication device of claim 2, wherein the phase
rotation vector is [1, -1, -1, -1].
4. The wireless communication device of claim 2, wherein: the first
sub-band of the communication channel is a first 20 MHz sub-band of
an 80 MHz communication channel; the second sub-band of the
communication channel is a second 20 MHz sub-band of the 80 MHz
communication channel; the third sub-band of the communication
channel is a third 20 MHz sub-band of the 80 MHz communication
channel; and the fourth sub-band of the communication channel is a
fourth 20 MHz sub-band of the 80 MHz communication channel.
5. The wireless communication device of claim 1, wherein: the first
sub-band of the communication channel is a first 20 MHz sub-band of
the communication channel; and the second sub-band of the
communication channel is a second 20 MHz sub-band of the
communication channel.
6. The wireless communication device of claim 1 further comprising:
a communication interface, coupled to the processor, that is
configured to support communications within at least one of a
satellite communication system, a wireless communication system, a
wired communication system, a fiber-optic communication system, or
a mobile communication system; and the processor configured to
receive the signal from the another wireless communication device
via the communication interface.
7. The wireless communication device of claim 1 further comprising:
a wireless station (STA), wherein the another wireless
communication device includes an access point (AP).
8. The wireless communication device of claim 1 further comprising:
an access point (AP), wherein the another wireless communication
device includes a wireless station (STA).
9. A wireless communication device comprising: a processor
configured to: receive, from another wireless communication device,
a first sub-band component of a signal via a first sub-band of a
communication channel, wherein the signal includes a plurality of
sub-components including the first sub-band component and a second
one or more sub-band components, wherein the second one or more
sub-band components have undergone rotation based on a phase
rotation vector that is [1, -1, -1, -1], and wherein the first
sub-band component and the second one or more sub-band components
of the signal have undergone cyclic shift delay (CSD); receive a
second sub-band component of the signal via a second sub-band of
the communication channel; receive a third sub-band component of
the signal via a third sub-band of the communication channel;
receive a fourth sub-band component of the signal via a fourth
sub-band of the communication channel; and process the first
sub-band component, the second sub-band component, the third
sub-band component, and the fourth sub-band component of the signal
based on the CSD and the phase rotation vector to recover data
transmitted from the another wireless communication device.
10. The wireless communication device of claim 9, wherein: the
first sub-band of the communication channel is a first 20 MHz
sub-band of an 80 MHz communication channel; the second sub-band of
the communication channel is a second 20 MHz sub-band of the 80 MHz
communication channel; the third sub-band of the communication
channel is a third 20 MHz sub-band of the 80 MHz communication
channel; and the fourth sub-band of the communication channel is a
fourth 20 MHz sub-band of the 80 MHz communication channel.
11. The wireless communication device of claim 9 further
comprising: a communication interface, coupled to the processor,
that is configured to support communications within at least one of
a satellite communication system, a wireless communication system,
a wired communication system, a fiber-optic communication system,
or a mobile communication system; and the processor configured to
receive the signal from the another wireless communication device
via the communication interface.
12. The wireless communication device of claim 9 further
comprising: a wireless station (STA), wherein the another wireless
communication device includes an access point (AP).
13. The wireless communication device of claim 9 further
comprising: an access point (AP), wherein the another wireless
communication device includes a wireless station (STA).
14. A method for execution by a wireless communication device, the
method comprising: receiving, via a communication interface of the
wireless communication device and from another wireless
communication device, a first sub-band component of a signal via a
first sub-band of a communication channel, wherein the signal
includes a plurality of sub-components including the first sub-band
component and a second one or more sub-band components, wherein the
second one or more sub-band components have undergone rotation
based on a phase rotation vector, and wherein the first sub-band
component and the second one or more sub-band components of the
signal have undergone cyclic shift delay (CSD); receiving, via the
communication interface of the wireless communication device and
from the another wireless communication device, a second sub-band
component of the signal via a second sub-band of the communication
channel; and processing the first sub-band component and the second
one or more sub-band components of the signal based on the CSD and
the phase rotation vector to recover data transmitted from the
another wireless communication device.
15. The method of claim 14 further comprising: receiving, via the
communication interface of the wireless communication device and
from the another wireless communication device, a third sub-band
component of the signal via a third sub-band of the communication
channel; receiving, via the communication interface of the wireless
communication device and from the another wireless communication
device, a fourth sub-band component of the signal via a fourth
sub-band of the communication channel; and processing the first
sub-band component, the second sub-band component, the third
sub-band component, and the fourth sub-band component based on the
CSD and the phase rotation vector to recover the data transmitted
from the another wireless communication device.
16. The method of claim 15, wherein the phase rotation vector is
[1, -1, -1, -1].
17. The method of claim 15, wherein: the first sub-band of the
communication channel is a first 20 MHz sub-band of an 80 MHz
communication channel; the second sub-band of the communication
channel is a second 20 MHz sub-band of the 80 MHz communication
channel; the third sub-band of the communication channel is a third
20 MHz sub-band of the 80 MHz communication channel; and the fourth
sub-band of the communication channel is a fourth 20 MHz sub-band
of the 80 MHz communication channel.
18. The method of claim 14, wherein: the first sub-band of the
communication channel is a first 20 MHz sub-band of the
communication channel; and the second sub-band of the communication
channel is a second 20 MHz sub-band of the communication
channel.
19. The method of claim 14 further comprising: operating the
communication interface of the wireless communication device to
support communications within at least one of a satellite
communication system, a wireless communication system, a wired
communication system, a fiber-optic communication system, or a
mobile communication system.
20. The method of claim 14, wherein the wireless communication
device includes a wireless station (STA), and the another wireless
communication device includes an access point (AP).
Description
CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS
Continuation Priority Claim, 35 U.S.C. .sctn.120
[0001] The present U.S. Utility patent application claims priority
pursuant to 35 U.S.C. .sctn.120 as a continuation of U.S. Utility
application Ser. No. 14/585,305, entitled "Phase rotation for
preambles within multiple user, multiple access, and/or MIMO
wireless communications," filed Dec. 30, 2014, pending, and
scheduled subsequently to be issued as U.S. Pat. No. 9,276,790 on
Mar. 1, 2016 (as indicated in an ISSUE NOTIFICATION mailed from the
USPTO on Feb. 10, 2016), which is a continuation of U.S. Utility
application Ser. No. 13/217,830, entitled "Phase rotation for
preambles within multiple user, multiple access, and/or MIMO
wireless communications", filed Aug. 25, 2011, now U.S. Pat. No.
8,934,572 issued on Jan. 13, 2015, which claims priority pursuant
to 35 U.S.C. .sctn.119(e) to U.S. Provisional Application No.
61/378,769, entitled "Phase rotation for preambles within multiple
user, multiple access, and/or MIMO wireless communications", filed
Aug. 31, 2010, all of which are hereby incorporated herein by
reference in their entirety and made part of the present U.S.
Utility patent application for all purposes.
INCORPORATION BY REFERENCE
[0002] The following IEEE standards are hereby incorporated herein
by reference in their entirety and are made part of the present
U.S. Utility patent application for all purposes: [0003] 1. IEEE
Std 802.11.TM.--2007, "IEEE Standard for Information
technology--Telecommunications and information exchange between
systems--Local and metropolitan area networks--Specific
requirements; Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications," IEEE Computer Society, IEEE
Std 802.11.TM.--2007, (Revision of IEEE Std 802.11-1999), 1233
pages. [0004] 2. IEEE Std 802.11n.TM. --2009, "IEEE Standard for
Information technology--Telecommunications and information exchange
between systems--Local and metropolitan area networks--Specific
requirements; Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications; Amendment 5: Enhancements for
Higher Throughput," IEEE Computer Society, IEEE Std
802.11n.TM.--2009, (Amendment to IEEE Std 802.11.TM.--2007 as
amended by IEEE Std 802.11k.TM.--2008, IEEE Std 802.11r.TM.--2008,
IEEE Std 802.11y.TM.--2008, and IEEE Std 802.11r.TM.--2009), 536
pages. [0005] 3. IEEE P802.11 ac.TM./D1.1, August 2011, "Draft
STANDARD for Information Technology--Telecommunications and
information exchange between systems--Local and metropolitan area
networks--Specific requirements, Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) specifications,
Amendment 5: Enhancements for Very High Throughput for Operation in
Bands below 6 GHz," Prepared by the 802.11 Working Group of the 802
Committee, 297 total pages (pp. i-xxiii, 1-274).
BACKGROUND OF THE INVENTION
[0006] 1. Technical Field of the Invention
[0007] The invention relates generally to communication systems;
and, more particularly, it relates to phase rotation for preambles
within multiple user, multiple access, and/or MIMO wireless
communications.
[0008] 2. Description of Related Art
[0009] Communication systems are known to support wireless and wire
lined communications between wireless and/or wire lined
communication devices. Such communication systems range from
national and/or international cellular telephone systems to the
Internet to point-to-point in-home wireless networks. Each type of
communication system is constructed, and hence operates, in
accordance with one or more communication standards. For instance,
wireless communication systems may operate in accordance with one
or more standards including, but not limited to, IEEE 802.11x,
Bluetooth, advanced mobile phone services (AMPS), digital AMPS,
global system for mobile communications (GSM), code division
multiple access (CDMA), local multi-point distribution systems
(LIVIDS), multi-channel-multi-point distribution systems (MMDS),
and/or variations thereof.
[0010] Depending on the type of wireless communication system, a
wireless communication device, such as a cellular telephone,
two-way radio, personal digital assistant (PDA), personal computer
(PC), laptop computer, home entertainment equipment, et cetera
communicates directly or indirectly with other wireless
communication devices. For direct communications (also known as
point-to-point communications), the participating wireless
communication devices tune their receivers and transmitters to the
same channel or channels (e.g., one of the plurality of radio
frequency (RF) carriers of the wireless communication system) and
communicate over that channel(s). For indirect wireless
communications, each wireless communication device communicates
directly with an associated base station (e.g., for cellular
services) and/or an associated access point (e.g., for an in-home
or in-building wireless network) via an assigned channel. To
complete a communication connection between the wireless
communication devices, the associated base stations and/or
associated access points communicate with each other directly, via
a system controller, via the public switch telephone network, via
the Internet, and/or via some other wide area network.
[0011] For each wireless communication device to participate in
wireless communications, it includes a built-in radio transceiver
(i.e., receiver and transmitter) or is coupled to an associated
radio transceiver (e.g., a station for in-home and/or in-building
wireless communication networks, RF modem, etc.). As is known, the
receiver is coupled to the antenna and includes a low noise
amplifier, one or more intermediate frequency stages, a filtering
stage, and a data recovery stage. The low noise amplifier receives
inbound RF signals via the antenna and amplifies them. The one or
more intermediate frequency stages mix the amplified RF signals
with one or more local oscillations to convert the amplified RF
signal into baseband signals or intermediate frequency (IF)
signals. The filtering stage filters the baseband signals or the IF
signals to attenuate unwanted out of band signals to produce
filtered signals. The data recovery stage recovers raw data from
the filtered signals in accordance with the particular wireless
communication standard.
[0012] As is also known, the transmitter includes a data modulation
stage, one or more intermediate frequency stages, and a power
amplifier. The data modulation stage converts raw data into
baseband signals in accordance with a particular wireless
communication standard. The one or more intermediate frequency
stages mix the baseband signals with one or more local oscillations
to produce RF signals. The power amplifier amplifies the RF signals
prior to transmission via an antenna.
[0013] Typically, the transmitter will include one antenna for
transmitting the RF signals, which are received by a single
antenna, or multiple antennae (alternatively, antennas), of a
receiver. When the receiver includes two or more antennae, the
receiver will select one of them to receive the incoming RF
signals. In this instance, the wireless communication between the
transmitter and receiver is a single-output-single-input (SISO)
communication, even if the receiver includes multiple antennae that
are used as diversity antennae (i.e., selecting one of them to
receive the incoming RF signals). For SISO wireless communications,
a transceiver includes one transmitter and one receiver. Currently,
most wireless local area networks (WLAN) that are IEEE 802.11,
802.11a, 802.11b, or 802.11g employ SISO wireless
communications.
[0014] Other types of wireless communications include
single-input-multiple-output (SIMO), multiple-input-single-output
(MISO), and multiple-input-multiple-output (MIMO). In a SIMO
wireless communication, a single transmitter processes data into
radio frequency signals that are transmitted to a receiver. The
receiver includes two or more antennae and two or more receiver
paths. Each of the antennae receives the RF signals and provides
them to a corresponding receiver path (e.g., LNA, down conversion
module, filters, and ADCs). Each of the receiver paths processes
the received RF signals to produce digital signals, which are
combined and then processed to recapture the transmitted data.
[0015] For a multiple-input-single-output (MISO) wireless
communication, the transmitter includes two or more transmission
paths (e.g., digital to analog converter, filters, up-conversion
module, and a power amplifier) that each converts a corresponding
portion of baseband signals into RF signals, which are transmitted
via corresponding antennae to a receiver. The receiver includes a
single receiver path that receives the multiple RF signals from the
transmitter. In this instance, the receiver uses beam forming to
combine the multiple RF signals into one signal for processing.
[0016] For a multiple-input-multiple-output (MIMO) wireless
communication, the transmitter and receiver each include multiple
paths. In such a communication, the transmitter parallel processes
data using a spatial and time encoding function to produce two or
more streams of data. The transmitter includes multiple
transmission paths to convert each stream of data into multiple RF
signals. The receiver receives the multiple RF signals via multiple
receiver paths that recapture the streams of data utilizing a
spatial and time decoding function. The recaptured streams of data
are combined and subsequently processed to recover the original
data.
[0017] With the various types of wireless communications (e.g.,
SISO, MISO, SIMO, and MIMO), it would be desirable to use one or
more types of wireless communications to enhance data throughput
within a WLAN. For example, high data rates can be achieved with
MIMO communications in comparison to SISO communications. However,
most WLAN include legacy wireless communication devices (i.e.,
devices that are compliant with an older version of a wireless
communication standard). As such, a transmitter capable of MIMO
wireless communications should also be backward compatible with
legacy devices to function in a majority of existing WLANs.
[0018] Therefore, a need exists for a WLAN device that is capable
of high data throughput and is backward compatible with legacy
devices.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] FIG. 1 is a diagram illustrating an embodiment of a wireless
communication system.
[0020] FIG. 2 is a diagram illustrating an embodiment of a wireless
communication device.
[0021] FIG. 3 is a diagram illustrating an embodiment of a radio
frequency (RF) transmitter.
[0022] FIG. 4 is a diagram illustrating an embodiment of an RF
receiver.
[0023] FIG. 5 is a diagram illustrating an embodiment of a method
for baseband processing of data.
[0024] FIG. 6 is a diagram illustrating an embodiment of a method
that further defines Step 120 of FIG. 5.
[0025] FIGS. 7-9 are diagrams illustrating various embodiments for
encoding the scrambled data.
[0026] FIGS. 10A and 10B are diagrams illustrating embodiments of a
radio transmitter.
[0027] FIGS. 11A and 11B are diagrams illustrating embodiments of a
radio receiver.
[0028] FIG. 12 is a diagram illustrating an embodiment of an access
point (AP) and multiple wireless local area network (WLAN) devices
operating according to one or more various aspects and/or
embodiments of the invention.
[0029] FIG. 13 is a diagram illustrating an embodiment of a
wireless communication device, and clusters, as may be employed for
supporting communications with at least one additional wireless
communication device.
[0030] FIG. 14 is a diagram illustrating an embodiment of phase
rotation on a preamble as may be performed within one or more
wireless communication devices.
[0031] FIG. 15 is a diagram illustrating an embodiment of a
comparison of peak to average power ratio (PAPR) across various
fields of a packet using various phase rotation vectors on frames
of various bandwidths.
[0032] FIG. 16 is a diagram illustrating an embodiment of a
complementary cumulative density (or distribution) function (CCDF)
of instantaneous power (P.sub.inst) for the L-SIG field.
[0033] FIG. 17 is a diagram illustrating an alternative embodiment
of phase rotation on a preamble as may be performed within one or
more wireless communication devices.
[0034] FIG. 18 is a diagram illustrating another embodiment of
phase rotation on a preamble as may be performed within one or more
wireless communication devices.
[0035] FIG. 19 is a diagram illustrating another embodiment of a
comparison of PAPR across various fields of a packet using various
phase rotation vectors on frames of various bandwidths.
[0036] FIG. 20 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field.
[0037] FIG. 21 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field, and particularly, using
4.times. oversampling.
[0038] FIG. 22 is a diagram illustrating another embodiment of a
comparison of PAPR across various fields of a packet using various
phase rotation vectors on frames of various bandwidths.
[0039] FIG. 23 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field, and particularly, using
4.times. oversampling.
[0040] FIG. 24 is a diagram illustrating an embodiment of Gaussian
fit of a time-domain (t-dom) signal.
[0041] FIG. 25 is a diagram illustrating an embodiment of a method
for operating one or more wireless communication devices.
DETAILED DESCRIPTION OF THE INVENTION
[0042] FIG. 1 is a diagram illustrating an embodiment of a wireless
communication system 10 that includes a plurality of base stations
and/or access points 12-16, a plurality of wireless communication
devices 18-32 and a network hardware component 34. The wireless
communication devices 18-32 may be laptop host computers 18 and 26,
personal digital assistant hosts 20 and 30, personal computer hosts
24 and 32 and/or cellular telephone hosts 22 and 28. The details of
an embodiment of such wireless communication devices are described
in greater detail with reference to FIG. 2.
[0043] The base stations (BSs) or access points (APs) 12-16 are
operably coupled to the network hardware 34 via local area network
connections 36, 38 and 40. The network hardware 34, which may be a
router, switch, bridge, modem, system controller, etc. provides a
wide area network connection 42 for the communication system 10.
Each of the base stations or access points 12-16 has an associated
antenna or antenna array to communicate with the wireless
communication devices in its area. Typically, the wireless
communication devices register with a particular base station or
access point 12-14 to receive services from the communication
system 10. For direct connections (i.e., point-to-point
communications), wireless communication devices communicate
directly via an allocated channel.
[0044] Typically, base stations are used for cellular telephone
systems (e.g., advanced mobile phone services (AMPS), digital AMPS,
global system for mobile communications (GSM), code division
multiple access (CDMA), local multi-point distribution systems
(LMDS), multi-channel-multi-point distribution systems (MMDS),
Enhanced Data rates for GSM Evolution (EDGE), General Packet Radio
Service (GPRS), high-speed downlink packet access (HSDPA),
high-speed uplink packet access (HSDPA and/or variations thereof)
and like-type systems, while access points are used for in-home or
in-building wireless networks (e.g., IEEE 802.11, Bluetooth,
ZigBee, any other type of radio frequency based network protocol
and/or variations thereof). Regardless of the particular type of
communication system, each wireless communication device includes a
built-in radio and/or is coupled to a radio. Such wireless
communication devices may operate in accordance with the various
aspects of the invention as presented herein to enhance
performance, reduce costs, reduce size, and/or enhance broadband
applications.
[0045] FIG. 2 is a diagram illustrating an embodiment of a wireless
communication device that includes the host device 18-32 and an
associated radio 60. For cellular telephone hosts, the radio 60 is
a built-in component. For personal digital assistants hosts, laptop
hosts, and/or personal computer hosts, the radio 60 may be built-in
or an externally coupled component. For access points or base
stations, the components are typically housed in a single
structure.
[0046] As illustrated, the host device 18-32 includes a processing
module 50, memory 52, radio interface 54, input interface 58 and
output interface 56. The processing module 50 and memory 52 execute
the corresponding instructions that are typically done by the host
device. For example, for a cellular telephone host device, the
processing module 50 performs the corresponding communication
functions in accordance with a particular cellular telephone
standard.
[0047] The radio interface 54 allows data to be received from and
sent to the radio 60. For data received from the radio 60 (e.g.,
inbound data), the radio interface 54 provides the data to the
processing module 50 for further processing and/or routing to the
output interface 56. The output interface 56 provides connectivity
to an output display device such as a display, monitor, speakers,
et cetera such that the received data may be displayed. The radio
interface 54 also provides data from the processing module 50 to
the radio 60. The processing module 50 may receive the outbound
data from an input device such as a keyboard, keypad, microphone,
et cetera via the input interface 58 or generate the data itself.
For data received via the input interface 58, the processing module
50 may perform a corresponding host function on the data and/or
route it to the radio 60 via the radio interface 54.
[0048] Radio 60 includes a host interface 62, a baseband processing
module 64, memory 66, a plurality of radio frequency (RF)
transmitters 68-72, a transmit/receive (T/R) module 74, a plurality
of antennae 82-86, a plurality of RF receivers 76-80, and a local
oscillation module 100. The baseband processing module 64, in
combination with operational instructions stored in memory 66,
execute digital receiver functions and digital transmitter
functions, respectively. The digital receiver functions, as will be
described in greater detail with reference to FIG. 11B, include,
but are not limited to, digital intermediate frequency to baseband
conversion, demodulation, constellation demapping, decoding,
de-interleaving, fast Fourier transform, cyclic prefix removal,
space and time decoding, and/or descrambling. The digital
transmitter functions, as will be described in greater detail with
reference to later Figures, include, but are not limited to,
scrambling, encoding, interleaving, constellation mapping,
modulation, inverse fast Fourier transform, cyclic prefix addition,
space and time encoding, and/or digital baseband to IF conversion.
The baseband processing modules 64 may be implemented using one or
more processing devices. Such a processing device may be a
microprocessor, micro-controller, digital signal processor,
microcomputer, central processing unit, field programmable gate
array, programmable logic device, state machine, logic circuitry,
analog circuitry, digital circuitry, and/or any device that
manipulates signals (analog and/or digital) based on operational
instructions. The memory 66 may be a single memory device or a
plurality of memory devices. Such a memory device may be a
read-only memory, random access memory, volatile memory,
non-volatile memory, static memory, dynamic memory, flash memory,
and/or any device that stores digital information. Note that when
the processing module 64 implements one or more of its functions
via a state machine, analog circuitry, digital circuitry, and/or
logic circuitry, the memory storing the corresponding operational
instructions is embedded with the circuitry comprising the state
machine, analog circuitry, digital circuitry, and/or logic
circuitry.
[0049] In operation, the radio 60 receives outbound data 88 from
the host device via the host interface 62. The baseband processing
module 64 receives the outbound data 88 and, based on a mode
selection signal 102, produces one or more outbound symbol streams
90. The mode selection signal 102 will indicate a particular mode
as are illustrated in the mode selection tables, which appear at
the end of the detailed discussion. For example, the mode selection
signal 102, with reference to table 1 may indicate a frequency band
of 2.4 GHz or 5 GHz, a channel bandwidth of 20 or 22 MHz (e.g.,
channels of 20 or 22 MHz width) and a maximum bit rate of 54
megabits-per-second. In other embodiments, the channel bandwidth
may extend up to 1.28 GHz or wider with supported maximum bit rates
extending to 1 gigabit-per-second or greater. In this general
category, the mode selection signal will further indicate a
particular rate ranging from 1 megabit-per-second to 54
megabits-per-second. In addition, the mode selection signal will
indicate a particular type of modulation, which includes, but is
not limited to, Barker Code Modulation, BPSK, QPSK, CCK, 16 QAM
and/or 64 QAM. As is further illustrated in table 1, a code rate is
supplied as well as number of coded bits per subcarrier (NBPSC),
coded bits per OFDM symbol (NCBPS), data bits per OFDM symbol
(NDBPS).
[0050] The mode selection signal may also indicate a particular
channelization for the corresponding mode which for the information
in table 1 is illustrated in table 2. As shown, table 2 includes a
channel number and corresponding center frequency. The mode select
signal may further indicate a power spectral density mask value
which for table 1 is illustrated in table 3. The mode select signal
may alternatively indicate rates within table 4 that has a 5 GHz
frequency band, 20 MHz channel bandwidth and a maximum bit rate of
54 megabits-per-second. If this is the particular mode select, the
channelization is illustrated in table 5. As a further alternative,
the mode select signal 102 may indicate a 2.4 GHz frequency band,
20 MHz channels and a maximum bit rate of 192 megabits-per-second
as illustrated in table 6. In table 6, a number of antennae may be
utilized to achieve the higher bit rates. In this instance, the
mode select would further indicate the number of antennae to be
utilized. Table 7 illustrates the channelization for the set-up of
table 6. Table 8 illustrates yet another mode option where the
frequency band is 2.4 GHz, the channel bandwidth is 20 MHz and the
maximum bit rate is 192 megabits-per-second. The corresponding
table 8 includes various bit rates ranging from 12
megabits-per-second to 216 megabits-per-second utilizing 2-4
antennae and a spatial time encoding rate as indicated. Table 9
illustrates the channelization for table 8. The mode select signal
102 may further indicate a particular operating mode as illustrated
in table 10, which corresponds to a 5 GHz frequency band having 40
MHz frequency band having 40 MHz channels and a maximum bit rate of
486 megabits-per-second. As shown in table 10, the bit rate may
range from 13.5 megabits-per-second to 486 megabits-per-second
utilizing 1-4 antennae and a corresponding spatial time code rate.
Table 10 further illustrates a particular modulation scheme code
rate and NBPSC values. Table 11 provides the power spectral density
mask for table 10 and table 12 provides the channelization for
table 10.
[0051] It is of course noted that other types of channels, having
different bandwidths, may be employed in other embodiments without
departing from the scope and spirit of the invention. For example,
various other channels such as those having 80 MHz, 120 MHz, and/or
160 MHz of bandwidth may alternatively be employed such as in
accordance with IEEE Task Group ac (TGac VHTL6).
[0052] The baseband processing module 64, based on the mode
selection signal 102 produces the one or more outbound symbol
streams 90, as will be further described with reference to FIGS.
5-9 from the output data 88. For example, if the mode selection
signal 102 indicates that a single transmit antenna is being
utilized for the particular mode that has been selected, the
baseband processing module 64 will produce a single outbound symbol
stream 90. Alternatively, if the mode select signal indicates 2, 3
or 4 antennae, the baseband processing module 64 will produce 2, 3
or 4 outbound symbol streams 90 corresponding to the number of
antennae from the output data 88.
[0053] Depending on the number of outbound streams 90 produced by
the baseband module 64, a corresponding number of the RF
transmitters 68-72 will be enabled to convert the outbound symbol
streams 90 into outbound RF signals 92. The implementation of the
RF transmitters 68-72 will be further described with reference to
FIG. 3. The transmit/receive module 74 receives the outbound RF
signals 92 and provides each outbound RF signal to a corresponding
antenna 82-86.
[0054] When the radio 60 is in the receive mode, the
transmit/receive module 74 receives one or more inbound RF signals
via the antennae 82-86. The T/R module 74 provides the inbound RF
signals 94 to one or more RF receivers 76-80. The RF receiver
76-80, which will be described in greater detail with reference to
FIG. 4, converts the inbound RF signals 94 into a corresponding
number of inbound symbol streams 96. The number of inbound symbol
streams 96 will correspond to the particular mode in which the data
was received (recall that the mode may be any one of the modes
illustrated in tables 1-12). The baseband processing module 64
receives the inbound symbol streams 90 and converts them into
inbound data 98, which is provided to the host device 18-32 via the
host interface 62.
[0055] In one embodiment of radio 60 it includes a transmitter and
a receiver. The transmitter may include a MAC module, a PLCP
module, and a PMD module. The Medium Access Control (MAC) module,
which may be implemented with the processing module 64, is operably
coupled to convert a MAC Service Data Unit (MSDU) into a MAC
Protocol Data Unit (MPDU) in accordance with a WLAN protocol. The
Physical Layer Convergence Procedure (PLCP) Module, which may be
implemented in the processing module 64, is operably coupled to
convert the MPDU into a PLCP Protocol Data Unit (PPDU) in
accordance with the WLAN protocol. The Physical Medium Dependent
(PMD) module is operably coupled to convert the PPDU into a
plurality of radio frequency (RF) signals in accordance with one of
a plurality of operating modes of the WLAN protocol, wherein the
plurality of operating modes includes multiple input and multiple
output combinations.
[0056] An embodiment of the Physical Medium Dependent (PMD) module,
which will be described in greater detail with reference to FIGS.
10A and 10B, includes an error protection module, a demultiplexing
module, and a plurality of direction conversion modules. The error
protection module, which may be implemented in the processing
module 64, is operably coupled to restructure a PPDU (PLCP
(Physical Layer Convergence Procedure) Protocol Data Unit) to
reduce transmission errors producing error protected data. The
demultiplexing module is operably coupled to divide the error
protected data into a plurality of error protected data streams The
plurality of direct conversion modules is operably coupled to
convert the plurality of error protected data streams into a
plurality of radio frequency (RF) signals.
[0057] As one of average skill in the art will appreciate, the
wireless communication device of FIG. 2 may be implemented using
one or more integrated circuits. For example, the host device may
be implemented on one integrated circuit, the baseband processing
module 64 and memory 66 may be implemented on a second integrated
circuit, and the remaining components of the radio 60, less the
antennae 82-86, may be implemented on a third integrated circuit.
As an alternate example, the radio 60 may be implemented on a
single integrated circuit. As yet another example, the processing
module 50 of the host device and the baseband processing module 64
may be a common processing device implemented on a single
integrated circuit. Further, the memory 52 and memory 66 may be
implemented on a single integrated circuit and/or on the same
integrated circuit as the common processing modules of processing
module 50 and the baseband processing module 64.
[0058] FIG. 3 is a diagram illustrating an embodiment of a radio
frequency (RF) transmitter 68-72, or RF front-end, of the WLAN
transmitter. The RF transmitter 68-72 includes a digital filter and
up-sampling module 75, a digital-to-analog conversion module 77, an
analog filter 79, and up-conversion module 81, a power amplifier 83
and a RF filter 85. The digital filter and up-sampling module 75
receives one of the outbound symbol streams 90 and digitally
filters it and then up-samples the rate of the symbol streams to a
desired rate to produce the filtered symbol streams 87. The
digital-to-analog conversion module 77 converts the filtered
symbols 87 into analog signals 89. The analog signals may include
an in-phase component and a quadrature component.
[0059] The analog filter 79 filters the analog signals 89 to
produce filtered analog signals 91. The up-conversion module 81,
which may include a pair of mixers and a filter, mixes the filtered
analog signals 91 with a local oscillation 93, which is produced by
local oscillation module 100, to produce high frequency signals 95.
The frequency of the high frequency signals 95 corresponds to the
frequency of the outbound RF signals 92.
[0060] The power amplifier 83 amplifies the high frequency signals
95 to produce amplified high frequency signals 97. The RF filter
85, which may be a high frequency band-pass filter, filters the
amplified high frequency signals 97 to produce the desired output
RF signals 92.
[0061] As one of average skill in the art will appreciate, each of
the radio frequency transmitters 68-72 will include a similar
architecture as illustrated in FIG. 3 and further include a
shut-down mechanism such that when the particular radio frequency
transmitter is not required, it is disabled in such a manner that
it does not produce interfering signals and/or noise.
[0062] FIG. 4 is a diagram illustrating an embodiment of an RF
receiver. This may depict any one of the RF receivers 76-80. In
this embodiment, each of the RF receivers 76-80 includes an RF
filter 101, a low noise amplifier (LNA) 103, a programmable gain
amplifier (PGA) 105, a down-conversion module 107, an analog filter
109, an analog-to-digital conversion module 111 and a digital
filter and down-sampling module 113. The RF filter 101, which may
be a high frequency band-pass filter, receives the inbound RF
signals 94 and filters them to produce filtered inbound RF signals.
The low noise amplifier 103 amplifies the filtered inbound RF
signals 94 based on a gain setting and provides the amplified
signals to the programmable gain amplifier 105. The programmable
gain amplifier further amplifies the inbound RF signals 94 before
providing them to the down-conversion module 107.
[0063] The down-conversion module 107 includes a pair of mixers, a
summation module, and a filter to mix the inbound RF signals with a
local oscillation (LO) that is provided by the local oscillation
module to produce analog baseband signals. The analog filter 109
filters the analog baseband signals and provides them to the
analog-to-digital conversion module 111 which converts them into a
digital signal. The digital filter and down-sampling module 113
filters the digital signals and then adjusts the sampling rate to
produce the digital samples (corresponding to the inbound symbol
streams 96).
[0064] FIG. 5 is a diagram illustrating an embodiment of a method
for baseband processing of data. This diagram shows a method for
converting outbound data 88 into one or more outbound symbol
streams 90 by the baseband processing module 64. The process begins
at Step 110 where the baseband processing module receives the
outbound data 88 and a mode selection signal 102. The mode
selection signal may indicate any one of the various modes of
operation as indicated in tables 1-12. The process then proceeds to
Step 112 where the baseband processing module scrambles the data in
accordance with a pseudo random sequence to produce scrambled data.
Note that the pseudo random sequence may be generated from a
feedback shift register with the generator polynomial of
S(x)=x.sup.7+x.sup.4+1.
[0065] The process then proceeds to Step 114 where the baseband
processing module selects one of a plurality of encoding modes
based on the mode selection signal. The process then proceeds to
Step 116 where the baseband processing module encodes the scrambled
data in accordance with a selected encoding mode to produce encoded
data. The encoding may be done utilizing any one or more a variety
of coding schemes (e.g., convolutional coding, Reed-Solomon (RS)
coding, turbo coding, turbo trellis coded modulation (TTCM) coding,
LDPC (Low Density Parity Check) coding, etc.).
[0066] The process then proceeds to Step 118 where the baseband
processing module determines a number of transmit streams based on
the mode select signal. For example, the mode select signal will
select a particular mode which indicates that 1, 2, 3, 4 or more
antennae may be utilized for the transmission. Accordingly, the
number of transmit streams will correspond to the number of
antennae indicated by the mode select signal. The process then
proceeds to Step 120 where the baseband processing module converts
the encoded data into streams of symbols in accordance with the
number of transmit streams in the mode select signal. This step
will be described in greater detail with reference to FIG. 6.
[0067] FIG. 6 is a diagram illustrating an embodiment of a method
that further defines Step 120 of FIG. 5. This diagram shows a
method performed by the baseband processing module to convert the
encoded data into streams of symbols in accordance with the number
of transmit streams and the mode select signal. Such processing
begins at Step 122 where the baseband processing module interleaves
the encoded data over multiple symbols and subcarriers of a channel
to produce interleaved data. In general, the interleaving process
is designed to spread the encoded data over multiple symbols and
transmit streams. This allows improved detection and error
correction capability at the receiver. In one embodiment, the
interleaving process will follow the IEEE 802.11(a) or (g) standard
for backward compatible modes. For higher performance modes (e.g.,
IEEE 802.11(n), the interleaving will also be done over multiple
transmit paths or streams.
[0068] The process then proceeds to Step 124 where the baseband
processing module demultiplexes the interleaved data into a number
of parallel streams of interleaved data. The number of parallel
streams corresponds to the number of transmit streams, which in
turn corresponds to the number of antennae indicated by the
particular mode being utilized. The process then continues to Steps
126 and 128, where for each of the parallel streams of interleaved
data, the baseband processing module maps the interleaved data into
a quadrature amplitude modulated (QAM) symbol to produce frequency
domain symbols at Step 126. At Step 128, the baseband processing
module converts the frequency domain symbols into time domain
symbols, which may be done utilizing an inverse fast Fourier
transform. The conversion of the frequency domain symbols into the
time domain symbols may further include adding a cyclic prefix to
allow removal of intersymbol interference at the receiver. Note
that the length of the inverse fast Fourier transform and cyclic
prefix are defined in the mode tables of tables 1-12. In general, a
64-point inverse fast Fourier transform is employed for 20 MHz
channels and 128-point inverse fast Fourier transform is employed
for 40 MHz channels.
[0069] The process then proceeds to Step 130 where the baseband
processing module space and time encodes the time domain symbols
for each of the parallel streams of interleaved data to produce the
streams of symbols. In one embodiment, the space and time encoding
may be done by space and time encoding the time domain symbols of
the parallel streams of interleaved data into a corresponding
number of streams of symbols utilizing an encoding matrix.
Alternatively, the space and time encoding may be done by space and
time encoding the time domain symbols of M-parallel streams of
interleaved data into P-streams of symbols utilizing the encoding
matrix, where P=2M In one embodiment the encoding matrix may
comprise a form of:
[ C 1 C 2 C 3 C 4 C 2 M - 1 C 2 M - C 2 * C 1 * - C 4 * C 3 * - C 2
M * C 2 M - 1 ] ##EQU00001##
The number of rows of the encoding matrix corresponds to M and the
number of columns of the encoding matrix corresponds to P. The
particular symbol values of the constants within the encoding
matrix may be real or imaginary numbers.
[0070] FIGS. 7-9 are diagrams illustrating various embodiments for
encoding the scrambled data.
[0071] FIG. 7 is a diagram of one method that may be utilized by
the baseband processing module to encode the scrambled data at Step
116 of FIG. 5. In this method, the encoding of FIG. 7 may include
an optional Step 144 where the baseband processing module may
optionally perform encoding with an outer Reed-Solomon (RS) code to
produce RS encoded data. It is noted that Step 144 may be conducted
in parallel with Step 140 described below.
[0072] Also, the process continues at Step 140 where the baseband
processing module performs a convolutional encoding with a 64 state
code and generator polynomials of G.sub.0=133.sub.8 and
G.sub.1=171.sub.8 on the scrambled data (that may or may not have
undergone RS encoding) to produce convolutional encoded data. The
process then proceeds to Step 142 where the baseband processing
module punctures the convolutional encoded data at one of a
plurality of rates in accordance with the mode selection signal to
produce the encoded data. Note that the puncture rates may include
1/2, 2/3 and/or 3/4, or any rate as specified in tables 1-12. Note
that, for a particular, mode, the rate may be selected for backward
compatibility with IEEE 802.11(a), IEEE 802.11(g), or IEEE
802.11(n) rate requirements.
[0073] FIG. 8 is a diagram of another encoding method that may be
utilized by the baseband processing module to encode the scrambled
data at Step 116 of FIG. 5. In this embodiment, the encoding of
FIG. 8 may include an optional Step 148 where the baseband
processing module may optionally perform encoding with an outer RS
code to produce RS encoded data. It is noted that Step 148 may be
conducted in parallel with Step 146 described below.
[0074] The method then continues at Step 146 where the baseband
processing module encodes the scrambled data (that may or may not
have undergone RS encoding) in accordance with a complimentary code
keying (CCK) code to produce the encoded data. This may be done in
accordance with IEEE 802.11(b) specifications, IEEE 802.11(g),
and/or IEEE 802.11(n) specifications.
[0075] FIG. 9 is a diagram of yet another method for encoding the
scrambled data at Step 116, which may be performed by the baseband
processing module. In this embodiment, the encoding of FIG. 9 may
include an optional Step 154 where the baseband processing module
may optionally perform encoding with an outer RS code to produce RS
encoded data.
[0076] Then, in some embodiments, the process continues at Step 150
where the baseband processing module performs LDPC (Low Density
Parity Check) coding on the scrambled data (that may or may not
have undergone RS encoding) to produce LDPC coded bits.
Alternatively, the Step 150 may operate by performing convolutional
encoding with a 256 state code and generator polynomials of
G.sub.0=561.sub.8 and G.sub.1=753.sub.8 on the scrambled data the
scrambled data (that may or may not have undergone RS encoding) to
produce convolutional encoded data. The process then proceeds to
Step 152 where the baseband processing module punctures the
convolutional encoded data at one of the plurality of rates in
accordance with a mode selection signal to produce encoded data.
Note that the puncture rate is indicated in the tables 1-12 for the
corresponding mode.
[0077] The encoding of FIG. 9 may further include the optional Step
154 where the baseband processing module combines the convolutional
encoding with an outer Reed Solomon code to produce the
convolutional encoded data.
[0078] FIGS. 10A and 10B are diagrams illustrating embodiments of a
radio transmitter. This may involve the PMD module of a WLAN
transmitter. In FIG. 10A, the baseband processing is shown to
include a scrambler 172, channel encoder 174, interleaver 176,
demultiplexer 170, a plurality of symbol mappers 180-184, a
plurality of inverse fast Fourier transform (IFFT)/cyclic prefix
addition modules 186-190 and a space/time encoder 192. The baseband
portion of the transmitter may further include a mode manager
module 175 that receives the mode selection signal 173 and produces
settings 179 for the radio transmitter portion and produces the
rate selection 171 for the baseband portion. In this embodiment,
the scrambler 172, the channel encoder 174, and the interleaver 176
comprise an error protection module. The symbol mappers 180-184,
the plurality of IFFT/cyclic prefix modules 186-190, the space time
encoder 192 comprise a portion of the digital baseband processing
module.
[0079] In operations, the scrambler 172 adds (e.g., in a Galois
Finite Field (GF2)) a pseudo random sequence to the outbound data
bits 88 to make the data appear random. A pseudo random sequence
may be generated from a feedback shift register with the generator
polynomial of S(x)=x.sup.7+x.sup.4+1 to produce scrambled data. The
channel encoder 174 receives the scrambled data and generates a new
sequence of bits with redundancy. This will enable improved
detection at the receiver. The channel encoder 174 may operate in
one of a plurality of modes. For example, for backward
compatibility with IEEE 802.11(a) and IEEE 802.11(g), the channel
encoder has the form of a rate 1/2 convolutional encoder with 64
states and a generator polynomials of G.sub.0=133.sub.8 and
G.sub.1=171.sub.8. The output of the convolutional encoder may be
punctured to rates of 1/2, 2/3, and 3/4 according to the specified
rate tables (e.g., tables 1-12). For backward compatibility with
IEEE 802.11(b) and the CCK modes of IEEE 802.11(g), the channel
encoder has the form of a CCK code as defined in IEEE 802.11(b).
For higher data rates (such as those illustrated in tables 6, 8 and
10), the channel encoder may use the same convolution encoding as
described above or it may use a more powerful code, including a
convolutional code with more states, any one or more of the various
types of error correction codes (ECCs) mentioned above (e.g., RS,
LDPC, turbo, TTCM, etc.) a parallel concatenated (turbo) code
and/or a low density parity check (LDPC) block code. Further, any
one of these codes may be combined with an outer Reed Solomon code.
Based on a balancing of performance, backward compatibility and low
latency, one or more of these codes may be optimal. Note that the
concatenated turbo encoding and low density parity check will be
described in greater detail with reference to subsequent
Figures.
[0080] The interleaver 176 receives the encoded data and spreads it
over multiple symbols and transmit streams. This allows improved
detection and error correction capabilities at the receiver. In one
embodiment, the interleaver 176 will follow the IEEE 802.11(a) or
(g) standard in the backward compatible modes. For higher
performance modes (e.g., such as those illustrated in tables 6, 8
and 10), the interleaver will interleave data over multiple
transmit streams. The demultiplexer 170 converts the serial
interleave stream from interleaver 176 into M-parallel streams for
transmission.
[0081] Each symbol mapper 180-184 receives a corresponding one of
the M-parallel paths of data from the demultiplexer. Each symbol
mapper 180-182 lock maps bit streams to quadrature amplitude
modulated QAM symbols (e.g., BPSK, QPSK, 16 QAM, 64 QAM, 256 QAM,
et cetera) according to the rate tables (e.g., tables 1-12). For
IEEE 802.11(a) backward compatibility, double Gray coding may be
used.
[0082] The map symbols produced by each of the symbol mappers
180-184 are provided to the IFFT/cyclic prefix addition modules
186-190, which performs frequency domain to time domain conversions
and adds a prefix, which allows removal of inter-symbol
interference at the receiver. Note that the length of the IFFT and
cyclic prefix are defined in the mode tables of tables 1-12. In
general, a 64-point IFFT will be used for 20 MHz channels and
128-point IFFT will be used for 40 MHz channels.
[0083] The space/time encoder 192 receives the M-parallel paths of
time domain symbols and converts them into P-output symbols. In one
embodiment, the number of M-input paths will equal the number of
P-output paths. In another embodiment, the number of output paths P
will equal 2M paths. For each of the paths, the space/time encoder
multiples the input symbols with an encoding matrix that has the
form of
[ C 1 C 2 C 3 C 4 C 2 M - 1 C 2 M - C 2 * C 1 * - C 4 * C 3 * - C 2
M * C 2 M - 1 ] . ##EQU00002##
[0084] The rows of the encoding matrix correspond to the number of
input paths and the columns correspond to the number of output
paths.
[0085] FIG. 10B illustrates the radio portion of the transmitter
that includes a plurality of digital filter/up-sampling modules
194-198, digital-to-analog conversion modules 200-204, analog
filters 206-216, I/Q modulators 218-222, RF amplifiers 224-228, RF
filters 230-234 and antennae 236-240. The P-outputs from the
space/time encoder 192 are received by respective digital
filtering/up-sampling modules 194-198. In one embodiment, the
digital filters/up sampling modules 194-198 are part of the digital
baseband processing module and the remaining components comprise
the plurality of RF front-ends. In such an embodiment, the digital
baseband processing module and the RF front end comprise a direct
conversion module.
[0086] In operation, the number of radio paths that are active
correspond to the number of P-outputs. For example, if only one
P-output path is generated, only one of the radio transmitter paths
will be active. As one of average skill in the art will appreciate,
the number of output paths may range from one to any desired
number.
[0087] The digital filtering/up-sampling modules 194-198 filter the
corresponding symbols and adjust the sampling rates to correspond
with the desired sampling rates of the digital-to-analog conversion
modules 200-204. The digital-to-analog conversion modules 200-204
convert the digital filtered and up-sampled signals into
corresponding in-phase and quadrature analog signals. The analog
filters 206-214 filter the corresponding in-phase and/or quadrature
components of the analog signals, and provide the filtered signals
to the corresponding I/Q modulators 218-222. The I/Q modulators
218-222 based on a local oscillation, which is produced by a local
oscillator 100, up-converts the I/Q signals into radio frequency
signals.
[0088] The RF amplifiers 224-228 amplify the RF signals which are
then subsequently filtered via RF filters 230-234 before being
transmitted via antennae 236-240.
[0089] FIGS. 11A and 11B are diagrams illustrating embodiments of a
radio receiver (as shown by reference numeral 250). These diagrams
illustrate a schematic block diagram of another embodiment of a
receiver. FIG. 11A illustrates the analog portion of the receiver
which includes a plurality of receiver paths. Each receiver path
includes an antenna, RF filters 252-256, low noise amplifiers
258-262, I/Q demodulators 264-268, analog filters 270-280,
analog-to-digital converters 282-286 and digital filters and
down-sampling modules 288-290.
[0090] In operation, the antennae receive inbound RF signals, which
are band-pass filtered via the RF filters 252-256. The
corresponding low noise amplifiers 258-262 amplify the filtered
signals and provide them to the corresponding I/Q demodulators
264-268. The I/Q demodulators 264-268, based on a local
oscillation, which is produced by local oscillator 100,
down-converts the RF signals into baseband in-phase and quadrature
analog signals.
[0091] The corresponding analog filters 270-280 filter the in-phase
and quadrature analog components, respectively. The
analog-to-digital converters 282-286 convert the in-phase and
quadrature analog signals into a digital signal. The digital
filtering and down-sampling modules 288-290 filter the digital
signals and adjust the sampling rate to correspond to the rate of
the baseband processing, which will be described in FIG. 11B.
[0092] FIG. 11B illustrates the baseband processing of a receiver.
The baseband processing includes a space/time decoder 294, a
plurality of fast Fourier transform (FFT)/cyclic prefix removal
modules 296-300, a plurality of symbol demapping modules 302-306, a
multiplexer 308, a deinterleaver 310, a channel decoder 312, and a
descramble module 314. The baseband processing module may further
include a mode managing module 175, which produces rate selections
171 and settings 179 based on mode selections 173. The space/time
decoding module 294, which performs the inverse function of
space/time encoder 192, receives P-inputs from the receiver paths
and produce M-output paths. The M-output paths are processed via
the FFT/cyclic prefix removal modules 296-300 which perform the
inverse function of the IFFT/cyclic prefix addition modules 186-190
to produce frequency domain symbols.
[0093] The symbol demapping modules 302-306 convert the frequency
domain symbols into data utilizing an inverse process of the symbol
mappers 180-184. The multiplexer 308 combines the demapped symbol
streams into a single path.
[0094] The deinterleaver 310 deinterleaves the single path
utilizing an inverse function of the function performed by
interleaver 176. The deinterleaved data is then provided to the
channel decoder 312 which performs the inverse function of channel
encoder 174. The descrambler 314 receives the decoded data and
performs the inverse function of scrambler 172 to produce the
inbound data 98.
[0095] FIG. 12 is a diagram illustrating an embodiment of an access
point (AP) and multiple wireless local area network (WLAN) devices
operating according to one or more various aspects and/or
embodiments of the invention. The AP point 1200 may compatible with
any number of communication protocols and/or standards, e.g., IEEE
802.11(a), IEEE 802.11(b), IEEE 802.11(g), IEEE 802.11(n), as well
as in accordance with various aspects of invention. According to
certain aspects of the present invention, the AP supports backwards
compatibility with prior versions of the IEEE 802.11x standards as
well. According to other aspects of the present invention, the AP
1200 supports communications with the WLAN devices 1202, 1204, and
1206 with channel bandwidths, MIMO dimensions, and at data
throughput rates unsupported by the prior IEEE 802.11x operating
standards. For example, the access point 1200 and WLAN devices
1202, 1204, and 1206 may support channel bandwidths from those of
prior version devices and from 40 MHz to 1.28 GHz and above. The
access point 1200 and WLAN devices 1202, 1204, and 1206 support
MIMO dimensions to 4.times.4 and greater. With these
characteristics, the access point 1200 and WLAN devices 1202, 1204,
and 1206 may support data throughput rates to 1 GHz and above.
[0096] The AP 1200 supports simultaneous communications with more
than one of the WLAN devices 1202, 1204, and 1206. Simultaneous
communications may be serviced via OFDM tone allocations (e.g.,
certain number of OFDM tones in a given cluster), MIMO dimension
multiplexing, or via other techniques. With some simultaneous
communications, the AP 1200 may allocate one or more of the
multiple antennae thereof respectively to support communication
with each WLAN device 1202, 1204, and 1206, for example.
[0097] Further, the AP 1200 and WLAN devices 1202, 1204, and 1206
are backwards compatible with the IEEE 802.11 (a), (b), (g), and
(n) operating standards. In supporting such backwards
compatibility, these devices support signal formats and structures
that are consistent with these prior operating standards.
[0098] Generally, communications as described herein may be
targeted for reception by a single receiver or for multiple
individual receivers (e.g. via multi-user multiple input multiple
output (MU-MIMO), and/or OFDMA transmissions, which are different
than single transmissions with a multi-receiver address). For
example, a single OFDMA transmission uses different tones or sets
of tones (e.g., clusters or channels) to send distinct sets of
information, each set of set of information transmitted to one or
more receivers simultaneously in the time domain. Again, an OFDMA
transmission sent to one user is equivalent to an OFDM
transmission. A single MU-MIMO transmission may include
spatially-diverse signals over a common set of tones, each
containing distinct information and each transmitted to one or more
distinct receivers. Some single transmissions may be a combination
of OFDMA and MU-MIMO. MIMO transceivers illustrated may include
SISO, SIMO, and MISO transceivers. The clusters employed for such
communications may be continuous (e.g., adjacent to one another) or
discontinuous (e.g., separated by a guard interval of band gap).
Transmissions on different OFDMA clusters may be simultaneous or
non-simultaneous. Such wireless communication devices as described
herein may be capable of supporting communications via a single
cluster or any combination thereof. Legacy users and new version
users (e.g., TGac MU-MIMO, OFDMA, MU-MIMO/OFDMA, etc.) may share
bandwidth at a given time or they can be scheduled at different
times for certain embodiments.
[0099] FIG. 13 is a diagram illustrating an embodiment of a
wireless communication device, and clusters, as may be employed for
supporting communications with at least one additional wireless
communication device. Generally speaking, a cluster may be viewed
as a depiction of the mapping of tones, such as for an OFDM symbol,
within or among one or more channels (e.g., sub-divided portions of
the spectrum) that may be situated in one or more bands (e.g.,
portions of the spectrum separated by relatively larger amounts).
As an example, various channels of 20 MHz may be situated within or
centered around a 5 GHz band. The channels within any such band may
be continuous (e.g., adjacent to one another) or discontinuous
(e.g., separated by some guard interval or band gap). Oftentimes,
one or more channels may be situated within a given band, and
different bands need not necessarily have a same number of channels
therein. Again, a cluster may generally be understood as any
combination one or more channels among one or more bands.
[0100] The wireless communication device of this diagram may be of
any of the various types and/or equivalents described herein (e.g.,
AP, WLAN device, or other wireless communication device including,
though not limited to, any of those depicted in FIG. 1, etc.). The
wireless communication device includes multiple antennae from which
one or more signals may be transmitted to one or more receiving
wireless communication devices and/or received from one or more
other wireless communication devices.
[0101] Such clusters may be used for transmissions of signals via
various one or more selected antennae. For example, different
clusters are shown as being used to transmit signals respectively
using different one or more antennae.
[0102] Also, it is noted that, with respect to certain embodiments,
general nomenclature may be employed wherein a transmitting
wireless communication device (e.g., such as being an Access point
(AP), or a wireless station (STA) operating as an `AP` with respect
to other STAs) initiates communications, and/or operates as a
network controller type of wireless communication device, with
respect to a number of other, receiving wireless communication
devices (e.g., such as being STAs), and the receiving wireless
communication devices (e.g., such as being STAs) responding to and
cooperating with the transmitting wireless communication device in
supporting such communications. Of course, while this general
nomenclature of transmitting wireless communication device(s) and
receiving wireless communication device(s) may be employed to
differentiate the operations as performed by such different
wireless communication devices within a communication system, all
such wireless communication devices within such a communication
system may of course support bi-directional communications to and
from other wireless communication devices within the communication
system. In other words, the various types of transmitting wireless
communication device(s) and receiving wireless communication
device(s) may all support bi-directional communications to and from
other wireless communication devices within the communication
system. Generally speaking, such capability, functionality,
operations, etc. as described herein may be applied to any wireless
communication device.
[0103] Within certain wireless communication systems, wireless
communication devices of various capabilities operate concurrently.
For examples, legacy wireless communication devices (e.g., IEEE
802.11a, TGa and/or IEEE 802.11n, TGn compliant, or generally
having a first capability) may operate in a common environment with
newer wireless communication devices (e.g., IEEE 802.11ac, TGac
compliant, or generally having a second capability). In such
instances where various capability type wireless communication
devices operate in a common vicinity or region, the legacy wireless
communication devices (e.g., TGa and/or TGn compliant, first
capability) should notified appropriately when communications
corresponding to the newer wireless communication devices (e.g.,
TGac compliant, second capability) may be occurring or will occur.
For examples, the legacy wireless communication devices (e.g., TGa
and/or TGn compliant, first capability) may be notified regarding
what types of communications will be contained within a remaining
portion of a frame; such indication may be provided via a preamble
of the frame. From one perspective, the preamble can indicate to
the legacy wireless communication devices (e.g., TGa and/or TGn
compliant, first capability) that they should stay off of the air
(i.e., not access the communication medium) for some period of time
in which communications when communications corresponding to the
newer wireless communication devices (e.g., TGac compliant) may be
occurring or will occur. Such newer types of communications may be
orthogonal frequency division multiple access (OFDMA), multi-user
multiple input multiple output (MU-MIMO), combination
OFDMA/MU-MIMO, etc.
[0104] A phase rotation vector, as may be applied to such a
preamble, provides for backward compatibility with the legacy
wireless communication devices (e.g., TGa and/or TGn compliant,
first capability) while allowing communications to be performed
using newer protocols and recommended practices such as may be
performed by newer wireless communication devices (e.g., TGac
compliant, second capability). The bandwidth employed for
legacy/first capability wireless communication devices can be
narrower than newer/second capability wireless communication
devices. For example, legacy/first capability wireless
communication devices may operate using 20 MHz or 40 MHz (e.g.,
composed of two 20 MHz sub-bands) bandwidth, while newer/second
capability wireless communication devices may operate using 80 MHz
bandwidth (e.g., composed of four 20 MHz sub-bands or two 40 MHz
sub-bands).
[0105] A phase rotation vector may be applied to the preamble to
effectuate backward compatibility to accommodate the legacy/first
capability wireless communication devices while also allowing
function of the newer/second capability wireless communication
devices.
[0106] For example, when considering the impact of certain phase
rotation vectors as applied by or for legacy/first capability
wireless communication devices (e.g., TGn compliant), there may be
some potential risks of the legacy/first capability wireless
communication devices (e.g., TGn compliant) not being able to
perform carrier acquisition of the frames associated with the newer
wireless communication devices (e.g., TGac compliant, second
capability) if the phase rotation vector applied to the preambles
is not designed properly. In some instances, a best legacy phase
rotation vector may be employed by co-existed or co-located legacy
wireless communication devices (e.g., TGn compliant, first
capability).
[0107] A detailed peak to average power ratio (PAPR) analysis for a
VHT frame may be performed. Generally speaking, a tradeoff is made
between achieving a high degree of backward compatibility to
accommodate the legacy/first capability wireless communication
devices while also achieving a relatively low (e.g., acceptable)
PAPR across the various fields of a frame. For example, ideally,
there will not be a great deal of variation between the PAPR
associated with the various fields of the frame when using an
appropriately designed phase rotation vector.
[0108] Such a detailed PAPR analysis for a VHT frame provides for a
decomposed PAPR comparison of different legacy preamble fields
(e.g., a legacy short training field (L-STF), a legacy long
training field (L-LTF), a legacy signal field (L-SIG), at least one
very high throughput signal field (VHT-SIGA)) of VHT frames with
different bandwidth options (20 MHz, 40 MHz, 80 MHz). Based on such
detailed PAPR analysis, it is demonstrated that L-SIG &
VHT-SIGA (as well as Non-HT Dup-Payload) are the dominant PAPRs
across the VHT frame.
[0109] A novel means of effectuating PAPR reduction using an
appropriately designed phase rotation vector is presented herein.
Various options of such PAPR reduction techniques/proposals are
compared and contrasted, and a novel, preferred embodiment of phase
rotation vector design is presented herein that helps effectuate a
great deal of PAPR reduction method without causing carrier
detection problems for legacy wireless communication devices (e.g.,
IEEE 802.11n, TGn compliant, first capability).
[0110] FIG. 14 is a diagram illustrating an embodiment of phase
rotation on a preamble as may be performed within one or more
wireless communication devices. This diagram shows some of the
possible deleterious effects that may be incurred by the
application of a phase rotation vector on such legacy wireless
communication devices (e.g., IEEE 802.11n, TGn compliant, first
capability). For example, such legacy wireless communication
devices (e.g., IEEE 802.11n, TGn compliant, first capability)
should be able to detect a 80 MHz legacy preamble and stay off of
the air (i.e., not access the communication medium) for the entire
packet duration so that the newer wireless communication devices
(e.g., IEEE 802.11ac, TGac compliant, second capability) may
operate without interference with those legacy wireless
communication devices. As may be seen with respect to a 80 MHz
frame (e.g., as employed by a newer wireless communication devices
such as being IEEE 802.11ac, TGac compliant, second capability),
the frame may be viewed as being composed of four separate 20 MHz
sub-band components. Respective elements of a phase rotation vector
may be applied to the respective sub-band components (e.g., 20 MHz
each) of a preamble, shown as .theta.1, .theta.2, .theta.3, and
.theta.4.
[0111] A certain level of backward compatibility should be
maintained to avoid degrading the carrier detection/acquisition
capability of the legacy wireless communication devices (e.g., IEEE
802.11n, TGn compliant, first capability) that may operate using
bandwidths of 20 MHz and 40 MHz.
[0112] As can be seen in the diagram, three possible options may be
encountered when operating using a legacy wireless communication
devices (e.g., IEEE 802.11n, TGn compliant, first capability) using
a bandwidth of 40 MHz, a 40 MHz sub-band may occupy a lower portion
of the 80 MHz band, a 40 MHz sub-band may occupy an upper portion
of the 80 MHz band, or a 40 MHz band associated with those wireless
communication devices operating using a overlapped basic services
set (OBSS) may overlap the second and third 20 MHz sub-bands of the
80 MHz band.
[0113] Mathematically, the most backward compatible 80 MHz phase
rotation vector is simply [1, j, -1, -j] (i.e., [0, 90 deg, 180
deg, 270 deg]). However, such a phase rotation vector may actually
lead to an undesirably high PAPR (e.g., shown with respect to FIG.
15 and FIG. 16).
[0114] A large PAPR variation among the various fields of a field
can be problematic for a variety of reasons including operating
within a non-linear region of a power amplifier (PA) or RF
amplifier (e.g., as shown within various embodiments herein)
implemented within a wireless communication device. A relatively
large back-off (e.g., reduction in power) may be required to ensure
operation within a linear region of such components within a
wireless communication device.
[0115] Considering the backward compatibility design considerations
with respect to legacy wireless communication devices (e.g., IEEE
802.11n, TGn compliant, first capability), certain considerations
may be of significant concern including the processing such as
performed by a receiving wireless communication device (RX) as
related to legacy preamble decoding such as: carrier detection
(CD), timing acquisition, channel estimation, carrier frequency
offset (CFO) correction, L-SIG decode, etc.
[0116] To effectuate backward compatibility, an appropriately
designed phase rotation vector should be transparent to all
functions except for carrier detection (CD). For example, except
"carrier detection", all other processing operations should be
transparent to the choice of per-20 MHz sub-band phase rotations
(e.g., to the respective 20 MHz sub-band components within a
preamble). For carrier detection (CD), the impact of phase rotation
depends on the particular processing means being employed. For
example, if an auto-correlation based processing means is employed,
then carrier detection should also be transparent to arbitrary
phase rotations. Alternatively, if a matched filter based detection
processing means is employed, then depending on its location inside
80 MHz spectrum and the per-20 MHz sub-band phase rotation factors
(e.g., applied to the respective 20 MHz sub-band components within
a preamble), 40 MHz legacy/IEEE 802.11n devices might "see" a
totally different legacy STF field than IEEE 802.11n frames. Such
legacy wireless communication devices (e.g., IEEE 802.11n, TGn
compliant, first capability), employing such a matched filter based
detection processing means, typically will not be able to perform
appropriate receiver processing and deal with such a situation.
[0117] FIG. 15 is a diagram illustrating an embodiment of a
comparison of peak to average power ratio (PAPR) across various
fields of a packet using various phase rotation vectors on frames
of various bandwidths. As can be seen, various respective fields of
a packet are affected differently and can have different respective
PAPRs associated therewith. The fields L-SIG and VHT-SIGA (as well
as Non-HT Dup Payload) are the dominant PAPRs across the VHT frame
when using a phase rotation vector of [1, j] as associated with
legacy wireless communication devices (e.g., IEEE 802.11n, TGn
compliant, first capability) using a bandwidth of 40 MHz, when
using a phase rotation vector of [1, -1, -1, -1] as associated with
newer wireless communication devices (e.g., IEEE 802.11ac, TGac
compliant, second capability) using a bandwidth of 80 MHz, and when
using a phase rotation vector of [1, j, -1, -j] as associated with
newer wireless communication devices (e.g., IEEE 802.11ac, TGac
compliant, second capability) using a bandwidth of 80 MHz.
[0118] As can be seen, the L-SIG PAPR is much higher than any other
fields in 40 MHz and 80 MHz mode. It is also noted that all of
these results are assuming a 4.times. over-sample. It is further
noted that the PAPR numbers shown in the table for L-SIG, VHT-SIGA,
VHT-SIGB and VHT-DATA fields are the 99.9-percentile PAPR. To be
specific, 99.9% of the instantaneous time-domain OFDM signal power
is less than this number when the average OFDM signal is normalized
to be 1.
[0119] One manner to deal with this relatively large PAPR for this
highest affected field is to employ a relatively large back-off;
however, it may not be desirable to employ such a large back-off to
deal only with a singularly problematic affected field.
[0120] FIG. 16 is a diagram illustrating an embodiment of a
complementary cumulative density (or distribution) function (CCDF)
of instantaneous power (P.sub.inst) for the L-SIG field. As can be
seen in this diagram, the phase rotation vector of [1, j, -1, j]
provides a relatively poor performance and could necessitate using
a relatively large back-off. Such a relatively large back-off can
severely limit the transmit power by which signals may be
transmitted from a transmitting wireless communication device. That
is to say, the transmit power must be reduced significantly (e.g.,
using a relatively large back-off) to transmit signals without
distortion.
[0121] An appropriately designed PAPR technique is presented
herein, as it generally is undesirable to apply a big PA/RF
amplifier back-off only to satisfy one poorly performing field
(e.g., L-SIG/VHT-SIGA). A better system design provides for more
balanced PAPRs across the various fields of the packet. Such a
better system design at least allows the payload field to be the
dominant PAPR source.
[0122] Certain embodiment may require additional PA back-off simply
to mitigate the effects of a larger than necessary L-SIG/VHT-SIGA
PAPR. For example, in one embodiment, about 2.0 dB additional PA
back-off is needed for 40 MHz L-SIG when compared to the payload
field, and about 4.3 dB additional PA back-off is needed for 80 MHz
L-SIG (e.g., if using [1, j, -1, -j] as phase rotation
factors).
[0123] A good PAPR reduction technique also benefits non-HT DUP
frames. Such non-HT DUP frames may be created using the same rule
as legacy preamble (e.g., as defined in Section 20.3.11.11 of IEEE
Std 802.11n.TM.--2009 as incorporated by reference above). For such
DUP frames, even the payload field may suffer deleteriously from a
large PAPR.
[0124] FIG. 17 is a diagram illustrating an alternative embodiment
of phase rotation on a preamble as may be performed within one or
more wireless communication devices. This embodiment employs a
phase rotation vector of [1, j, 1, j] and also employs a cyclic
shift delay (CSD) of 25 ns to the upper 40 MHz sub-band component
of the preamble. Such a phase rotation vector of [1, j, 1, j] (25
ns) does in fact improve the PAPR. However, the risk of potential
carrier detection problem for legacy wireless communication devices
(e.g., IEEE 802.11n, TGn compliant, first capability) using a
bandwidth of 40 MHz. While this approach does provide for some
modest improvement in performance, a following embodiment provides
for a much greater improvement in performance.
[0125] FIG. 18 is a diagram illustrating another embodiment of
phase rotation on a preamble as may be performed within one or more
wireless communication devices. A novel PAPR reduction method
presented herein can be used to reduce the PAPR across the
respective fields without changing L-STF as "seen" by legacy
wireless communication devices (e.g., IEEE 802.11n, TGn compliant,
first capability) using a bandwidth of 40 MHz.
[0126] For example, since the L-STF tones are spaced by 1.25 MHz in
the frequency domain (f-dom), multiples of 800 ns CSD as applied to
the respective sub-band components of a preamble (e.g., no CSD
applied to the first sub-band component, 800 ns CSD applied to the
second sub-band component, 1600 ns CSD applied to the third
sub-band component, and 2400 ns CSD applied to the fourth sub-band
component in one embodiment). The application of such CSDs will not
change the L-STF field at all. Hence, those legacy wireless
communication devices (e.g., IEEE 802.11n, TGn compliant, first
capability) using a bandwidth of 40 MHz will "see" the exact legacy
L-STF as defined in accordance with IEEE 802.11n.
[0127] The multiples of 800 ns CSD can be implemented easily
because there are only 4 possible phase rotation factors: 1, -1, j,
-j. No additional hardware complexities are required for the
implementation. It is noted that, except for the L-STF field (which
is unaffected using these appropriately selected CSDs), other
legacy preamble fields (L-LTF, L-SIG, VHT-SIGA) are not exactly
copies of the 20 MHz corresponding fields with proper phase
rotations.
[0128] FIG. 19 is a diagram illustrating another embodiment of a
comparison of PAPR across various fields of a packet using various
phase rotation vectors on frames of various bandwidths. As may be
seen, the second row from the top and the bottom row employ a PAPR
reduction method using integer multiples of a CSD being applied to
the respective sub-band components of the preamble.
[0129] For example, the second row from the top [corresponding to a
40 MHz bandwidth] employs no CSD applied to the first sub-band
component of 20 MHz (rotated by an element of a phase rotation
vector of "1"), 800 ns CSD applied to the second sub-band component
of 20 MHz (rotated by an element of the phase rotation vector of
"j").
[0130] Also, the bottom row [corresponding to a 80 MHz bandwidth]
employs no CSD applied to the first sub-band component of 20 MHz
(rotated by an element of a phase rotation vector of "1"), 800 ns
CSD applied to the second sub-band component of 20 MHz (rotated by
an element of the phase rotation vector of "j"), 1600 ns CSD
applied to the third sub-band component of 20 MHz (rotated by an
element of the phase rotation vector of "-1"), and 2400 ns CSD
applied to the fourth sub-band component of 20 MHz (rotated by an
element of the phase rotation vector of "-j"). It is noted that the
PAPR numbers shown in the table for L-SIG, VHT-SIGA, VHT-SIGB and
VHT-DATA fields are the 99.9-percentile PAPR. To be specific, 99.9%
of the instantaneous time-domain OFDM signal power is less than
this number when the average OFDM signal is normalized to be 1.
[0131] FIG. 20 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field. As can be seen when
comparing the FIG. 20 with FIG. 16, by using the integer multiples
of a CSD being applied to the respective sub-band components of the
preamble (e.g., shown using the two curves whose data points are
triangular shaped), a significant improvement in performance is
achieved.
[0132] FIG. 21 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field, and particularly, using
4.times. oversampling. This diagram is analogous with respect to
previous embodiments, with at least one difference being that
4.times. oversampling is performed on signals before they are
provided to a digital to analog converter (DAC) within a wireless
communication device before being transmitted there from.
[0133] FIG. 22 is a diagram illustrating another embodiment of a
comparison of PAPR across various fields of a packet using various
phase rotation vectors on frames of various bandwidths.
[0134] As may be seen, the second row from the top, the third row
from the top, and the bottom row employ a PAPR reduction method
using integer multiples of a CSD being applied to the respective
sub-band components of the preamble.
[0135] For example, the second row from the top [corresponding to a
40 MHz bandwidth] employs no CSD applied to the first sub-band
component of 20 MHz (rotated by an element of a phase rotation
vector of "1"), 400 ns CSD applied to the second sub-band component
of 20 MHz (rotated by an element of the phase rotation vector of
"j").
[0136] For example, the third row from the top [corresponding to a
40 MHz bandwidth] employs no CSD applied to the first sub-band
component of 20 MHz (rotated by an element of a phase rotation
vector of "1"), 800 ns CSD applied to the second sub-band component
of 20 MHz (rotated by an element of the phase rotation vector of
"j").
[0137] Also, the bottom row [corresponding to a 80 MHz bandwidth]
employs no CSD applied to the first sub-band component of 20 MHz
(rotated by an element of a phase rotation vector of "1"), 800 ns
CSD applied to the second sub-band component of 20 MHz (rotated by
an element of the phase rotation vector of "j"), 1600 ns CSD
applied to the third sub-band component of 20 MHz (rotated by an
element of the phase rotation vector of "-1"), and 2400 ns CSD
applied to the fourth sub-band component of 20 MHz (rotated by an
element of the phase rotation vector of "-j").
[0138] FIG. 23 is a diagram illustrating another embodiment of a
CCDF of P.sub.inst for the L-SIG field, and particularly, using
4.times. oversampling. As can be seen in this diagram, by using the
integer multiples of a CSD being applied to the respective sub-band
components of the preamble (e.g., shown using the two curves whose
data points are triangular shaped, and shown using the one curve
whose data points are diamond shaped), a significant improvement in
performance is achieved.
[0139] The mathematical analysis associated with the PAPR reduction
method is presented below.
[0140] 1. No oversampled 40 MHz PAPR with phase rotation [1, j]
x ( n ) = k = - 64 63 X ( k ) - j 2 .pi. kn 128 = k = - 64 - 1 ( X
( k ) - j 2 .pi. kn 128 + X ( k + 64 ) - j 2 .pi. ( k + 64 ) n 128
) = k = - 64 - 1 ( X ( k ) - j 2 .pi. kn 128 + j X ( k ) - j 2 .pi.
( k + 64 ) n 128 ) = ( k = - 64 - 1 X ( k ) - j 2 .pi. kn 128 ) ( 1
+ j - j .pi. n ) ##EQU00003##
[0141] As can be seen, the term, (1+j e.sup.-j.pi.n, is a constant
modulus term.
[0142] 2. 4.times. oversampled 40 MHz PAPR with phase rotation [1,
j]
x ( n ) = k = - 64 63 X ( k ) - j 2 .pi. kn 4 .times. 128 = k = -
64 - 1 ( X ( k ) - j 2 .pi. kn 4 .times. 128 + X ( k + 64 ) - j 2
.pi. ( k + 64 ) n 4 .times. 128 ) = k = - 64 - 1 ( X ( k ) - j 2
.pi. kn 4 .times. 128 + j X ( k ) - j 2 .pi. ( k + 64 ) n 4 .times.
128 ) = ( k = - 64 - 1 X ( k ) - j 2 .pi. kn 4 .times. 128 ) ( 1 +
j j .pi. n 4 ) ##EQU00004##
[0143] As can be seen, the term,
( 1 + j - j .pi. n 4 ) , ##EQU00005##
is a non-constant (i.e., not constant) modulus term.
[0144] FIG. 24 is a diagram illustrating an embodiment of Gaussian
fit of a time-domain (t-dom) signal. As can be seen with respect to
this diagram, by using the integer multiples of a CSD being applied
to the respective sub-band components of the preamble (e.g., shown
using the bottom two graphs), a significant improvement in
performance is achieved.
[0145] FIG. 25 is a diagram illustrating an embodiment of a method
for operating one or more wireless communication devices. Referring
to method 2500 of FIG. 25, the method 2500 describes operations as
may be performed within a transmitting wireless communication
device. The method 2500 begins by applying elements of a phase
rotation vector to respective sub-band components of a preamble, as
shown in a block 2510.
[0146] The method 2500 continues by applying respective integer
multiples of CSD to respective sub-band components of the preamble,
as shown in a block 2520.
[0147] For example, the operations of the block 2520 may be
effectuated by applying second CSD (e.g., 1.times.CSD.sub.x ns) to
second sub-band component of the preamble, as shown in a block
2520a. Such operations may continue by applying second CSD (e.g.,
1.times.CSD.sub.x ns) to second sub-band component of the preamble,
as shown in a block 2520b. Generally speaking, the operations may
continue by applying n.sup.th CSD (e.g., (n-1).times.CSD.sub.x ns)
to n.sup.th sub-band component of the preamble, as shown in a block
2520c.
[0148] For example, one embodiment operates by processing a
preamble [corresponding to a 80 MHz bandwidth] by employing no CSD
applied to the first sub-band component of 20 MHz (rotated by an
element of a phase rotation vector of "1"), 800 ns CSD applied to
the second sub-band component of 20 MHz (rotated by an element of
the phase rotation vector of "j"), 1600 ns CSD applied to the third
sub-band component of 20 MHz (rotated by an element of the phase
rotation vector of "-1"), and 2400 ns CSD applied to the fourth
sub-band component of 20 MHz (rotated by an element of the phase
rotation vector of "-j").
[0149] Another embodiment operates by processing a preamble
[corresponding to a 40 MHz bandwidth] by employing no CSD applied
to the first sub-band component of 20 MHz (rotated by an element of
a phase rotation vector of "1"), and 800 ns CSD applied to the
second sub-band component of 20 MHz (rotated by an element of the
phase rotation vector of "j").
[0150] Generally, the principles of applying integer multiples of a
CSD to the respective sub-band components of the preamble may be
applied to preambles of various sizes without departing from the
scope and spirit of the invention.
[0151] It is also noted that the various operations and functions
as described with respect to various methods herein may be
performed within a wireless communication device, such as using a
baseband processing module and/or a processing module implemented
therein (e.g., such as in accordance with the baseband processing
module 64 and/or the processing module 50 as described with
reference to FIG. 2) and/or other components therein.
[0152] For example, such a baseband processing module can perform
processing of various signals including applying any of a variety
of phase rotation vectors to preambles of signals and applying
respective integer multiples of cyclic shift delays (CSDs) to
respective sub-band components of the preamble, or any other
operations and functions as described herein, etc. or their
respective equivalents. In some embodiments, such a baseband
processing module and/or a processing module (which may be
implemented in the same device or separate devices) can perform
such processing to generate signals for transmission using at least
one of any number of radios and at least one of any number of
antennae of another wireless communication device in accordance
with various aspects of the invention, and/or any other operations
and functions as described herein, etc. or their respective
equivalents. In some embodiments, such processing is performed
cooperatively by a processing module in a first device, and a
baseband processing module within a second device. In other
embodiments, such processing is performed wholly by a baseband
processing module.
[0153] It is also noted that the various operations and functions
as described with respect to various methods herein may be
performed within a wireless communication device, such as using a
baseband processing module and/or a processing module implemented
therein, (e.g., such as in accordance with the baseband processing
module 64 and/or the processing module 50 as described with
reference to FIG. 2) and/or other components therein. For example,
such a baseband processing module can generate such signals and
frames as described herein as well as perform various operations
and analyses as described herein, or any other operations and
functions as described herein, etc. or their respective
equivalents.
[0154] For example, such a baseband processing module and/or a
processing module (which may be implemented in the same device or
separate devices) can perform generation of a beamforming feedback
frame, as well as generation of a signal including such a
beamforming feedback frame and transmission of that signal using at
least one of any number of radios and at least one of any number of
antennae of a wireless communication device in accordance with
various aspects of the invention, and/or any other operations and
functions as described herein, etc. or their respective
equivalents. In some embodiments, such a beamforming feedback frame
is generated cooperatively by a processing module in a first
device, and a baseband processing module within a second device. In
other embodiments, such a beamforming feedback frame is generated
wholly by a baseband processing module or a processing module.
[0155] In some embodiments, such a baseband processing module
and/or a processing module (which may be implemented in the same
device or separate devices) can perform such processing to generate
signals for transmission using at least one of any number of radios
and at least one of any number of antennae to another wireless
communication device (e.g., which also may include at least one of
any number of radios and at least one of any number of antennae) in
accordance with various aspects of the invention, and/or any other
operations and functions as described herein, etc. or their
respective equivalents. In some embodiments, such processing is
performed cooperatively by a processing module in a first device,
and a baseband processing module within a second device. In other
embodiments, such processing is performed wholly by a baseband
processing module or a processing module.
[0156] As may be used herein, the terms "substantially" and
"approximately" provides an industry-accepted tolerance for its
corresponding term and/or relativity between items. Such an
industry-accepted tolerance ranges from less than one percent to
fifty percent and corresponds to, but is not limited to, component
values, integrated circuit process variations, temperature
variations, rise and fall times, and/or thermal noise. Such
relativity between items ranges from a difference of a few percent
to magnitude differences. As may also be used herein, the term(s)
"operably coupled to", "coupled to", and/or "coupling" includes
direct coupling between items and/or indirect coupling between
items via an intervening item (e.g., an item includes, but is not
limited to, a component, an element, a circuit, and/or a module)
where, for indirect coupling, the intervening item does not modify
the information of a signal but may adjust its current level,
voltage level, and/or power level. As may further be used herein,
inferred coupling (i.e., where one element is coupled to another
element by inference) includes direct and indirect coupling between
two items in the same manner as "coupled to". As may even further
be used herein, the term "operable to" or "operably coupled to"
indicates that an item includes one or more of power connections,
input(s), output(s), etc., to perform, when activated, one or more
its corresponding functions and may further include inferred
coupling to one or more other items. As may still further be used
herein, the term "associated with", includes direct and/or indirect
coupling of separate items and/or one item being embedded within
another item. As may be used herein, the term "compares favorably",
indicates that a comparison between two or more items, signals,
etc., provides a desired relationship. For example, when the
desired relationship is that signal 1 has a greater magnitude than
signal 2, a favorable comparison may be achieved when the magnitude
of signal 1 is greater than that of signal 2 or when the magnitude
of signal 2 is less than that of signal 1.
[0157] As may also be used herein, the terms "processing module",
"module", "processing circuit", and/or "processing unit" (e.g.,
including various modules and/or circuitries such as may be
operative, implemented, and/or for encoding, for decoding, for
baseband processing, etc.) may be a single processing device or a
plurality of processing devices. Such a processing device may be a
microprocessor, micro-controller, digital signal processor,
microcomputer, central processing unit, field programmable gate
array, programmable logic device, state machine, logic circuitry,
analog circuitry, digital circuitry, and/or any device that
manipulates signals (analog and/or digital) based on hard coding of
the circuitry and/or operational instructions. The processing
module, module, processing circuit, and/or processing unit may have
an associated memory and/or an integrated memory element, which may
be a single memory device, a plurality of memory devices, and/or
embedded circuitry of the processing module, module, processing
circuit, and/or processing unit. Such a memory device may be a
read-only memory (ROM), random access memory (RAM), volatile
memory, non-volatile memory, static memory, dynamic memory, flash
memory, cache memory, and/or any device that stores digital
information. Note that if the processing module, module, processing
circuit, and/or processing unit includes more than one processing
device, the processing devices may be centrally located (e.g.,
directly coupled together via a wired and/or wireless bus
structure) or may be distributedly located (e.g., cloud computing
via indirect coupling via a local area network and/or a wide area
network). Further note that if the processing module, module,
processing circuit, and/or processing unit implements one or more
of its functions via a state machine, analog circuitry, digital
circuitry, and/or logic circuitry, the memory and/or memory element
storing the corresponding operational instructions may be embedded
within, or external to, the circuitry comprising the state machine,
analog circuitry, digital circuitry, and/or logic circuitry. Still
further note that, the memory element may store, and the processing
module, module, processing circuit, and/or processing unit
executes, hard coded and/or operational instructions corresponding
to at least some of the steps and/or functions illustrated in one
or more of the Figures. Such a memory device or memory element can
be included in an article of manufacture.
[0158] The present invention has been described above with the aid
of method steps illustrating the performance of specified functions
and relationships thereof. The boundaries and sequence of these
functional building blocks and method steps have been arbitrarily
defined herein for convenience of description. Alternate boundaries
and sequences can be defined so long as the specified functions and
relationships are appropriately performed. Any such alternate
boundaries or sequences are thus within the scope and spirit of the
claimed invention. Further, the boundaries of these functional
building blocks have been arbitrarily defined for convenience of
description. Alternate boundaries could be defined as long as the
certain significant functions are appropriately performed.
Similarly, flow diagram blocks may also have been arbitrarily
defined herein to illustrate certain significant functionality. To
the extent used, the flow diagram block boundaries and sequence
could have been defined otherwise and still perform the certain
significant functionality. Such alternate definitions of both
functional building blocks and flow diagram blocks and sequences
are thus within the scope and spirit of the claimed invention. One
of average skill in the art will also recognize that the functional
building blocks, and other illustrative blocks, modules and
components herein, can be implemented as illustrated or by discrete
components, application specific integrated circuits, processors
executing appropriate software and the like or any combination
thereof.
[0159] The present invention may have also been described, at least
in part, in terms of one or more embodiments. An embodiment of the
present invention is used herein to illustrate the present
invention, an aspect thereof, a feature thereof, a concept thereof,
and/or an example thereof. A physical embodiment of an apparatus,
an article of manufacture, a machine, and/or of a process that
embodies the present invention may include one or more of the
aspects, features, concepts, examples, etc. described with
reference to one or more of the embodiments discussed herein.
Further, from figure to figure, the embodiments may incorporate the
same or similarly named functions, steps, modules, etc. that may
use the same or different reference numbers and, as such, the
functions, steps, modules, etc. may be the same or similar
functions, steps, modules, etc. or different ones.
[0160] Unless specifically stated to the contra, signals to, from,
and/or between elements in a figure of any of the figures presented
herein may be analog or digital, continuous time or discrete time,
and single-ended or differential. For instance, if a signal path is
shown as a single-ended path, it also represents a differential
signal path. Similarly, if a signal path is shown as a differential
path, it also represents a single-ended signal path. While one or
more particular architectures are described herein, other
architectures can likewise be implemented that use one or more data
buses not expressly shown, direct connectivity between elements,
and/or indirect coupling between other elements as recognized by
one of average skill in the art.
[0161] The term "module" is used in the description of the various
embodiments of the present invention. A module includes a
functional block that is implemented via hardware to perform one or
module functions such as the processing of one or more input
signals to produce one or more output signals. The hardware that
implements the module may itself operate in conjunction software,
and/or firmware. As used herein, a module may contain one or more
sub-modules that themselves are modules.
[0162] While particular combinations of various functions and
features of the present invention have been expressly described
herein, other combinations of these features and functions are
likewise possible. The present invention is not limited by the
particular examples disclosed herein and expressly incorporates
these other combinations.
Mode Selection Tables:
TABLE-US-00001 [0163] TABLE 1 2.4 GHz, 20/22 MHz channel BW, 54
Mbps max bit rate Code Rate Modulation Rate NBPSC NCBPS NDBPS EVM
Sensitivity ACR AACR Barker 1 BPSK Barker 2 QPSK 5.5 CCK 6 BPSK 0.5
1 48 24 -5 -82 16 32 9 BPSK 0.75 1 48 36 -8 -81 15 31 11 CCK 12
QPSK 0.5 2 96 48 -10 -79 13 29 18 QPSK 0.75 2 96 72 -13 -77 11 27
24 16-QAM 0.5 4 192 96 -16 -74 8 24 36 16-QAM 0.75 4 192 144 -19
-70 4 20 48 64-QAM 0.666 6 288 192 -22 -66 0 16 54 64-QAM 0.75 6
288 216 -25 -65 -1 15
TABLE-US-00002 TABLE 2 Channelization for Table 1 Frequency Channel
(MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9
2452 10 2457 11 2462 12 2467
TABLE-US-00003 TABLE 3 Power Spectral Density (PSD) Mask for Table
1 PSD Mask 1 Frequency Offset dBr -9 MHz to 9 MHz 0 +/-11 MHz -20
+/-20 MHz -28 +/-30 MHz and greater -50
TABLE-US-00004 TABLE 4 5 GHz, 20 MHz channel BW, 54 Mbps max bit
rate Code Rate Modulation Rate NBPSC NCBPS NDBPS EVM Sensitivity
ACR AACR 6 BPSK 0.5 1 48 24 -5 -82 16 32 9 BPSK 0.75 1 48 36 -8 -81
15 31 12 QPSK 0.5 2 96 48 -10 -79 13 29 18 QPSK 0.75 2 96 72 -13
-77 11 27 24 16-QAM 0.5 4 192 96 -16 -74 8 24 36 16-QAM 0.75 4 192
144 -19 -70 4 20 48 64-QAM 0.666 6 288 192 -22 -66 0 16 54 64-QAM
0.75 6 288 216 -25 -65 -1 15
TABLE-US-00005 TABLE 5 Channelization for Table 4 Frequency
Frequency Channel (MHz) Country Channel (MHz) Country 240 4920
Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12
5060 Japan 16 5080 Japan 36 5180 USA/Europe 34 5170 Japan 40 5200
USA/Europe 38 5190 Japan 44 5220 USA/Europe 42 5210 Japan 48 5240
USA/Europe 46 5230 Japan 52 5260 USA/Europe 56 5280 USA/Europe 60
5300 USA/Europe 64 5320 USA/Europe 100 5500 USA/Europe 104 5520
USA/Europe 108 5540 USA/Europe 112 5560 USA/Europe 116 5580
USA/Europe 120 5600 USA/Europe 124 5620 USA/Europe 128 5640
USA/Europe 132 5660 USA/Europe 136 5680 USA/Europe 140 5700
USA/Europe 149 5745 USA 153 5765 USA 157 5785 USA 161 5805 USA 165
5825 USA
TABLE-US-00006 TABLE 6 2.4 GHz, 20 MHz channel BW, 192 Mbps max bit
rate ST TX Code Modu- Code Rate Antennas Rate lation Rate NBPSC
NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 24 24 2 1 QPSK 0.5 2 96 48 48 2 1
16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM
0.75 6 288 216 18 3 1 BPSK 0.5 1 48 24 36 3 1 QPSK 0.5 2 96 48 72 3
1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM
0.75 6 288 216 24 4 1 BPSK 0.5 1 48 24 48 4 1 QPSK 0.5 2 96 48 96 4
1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM
0.75 6 288 216
TABLE-US-00007 TABLE 7 Channelization for Table 6 Frequency Channel
(MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9
2452 10 2457 11 2462 12 2467
TABLE-US-00008 TABLE 8 5 GHz, 20 MHz channel BW, 192 Mbps max bit
rate ST TX Code Modu- Code Rate Antennas Rate lation Rate NBPSC
NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 24 24 2 1 QPSK 0.5 2 96 48 48 2 1
16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM
0.75 6 288 216 18 3 1 BPSK 0.5 1 48 24 36 3 1 QPSK 0.5 2 96 48 72 3
1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM
0.75 6 288 216 24 4 1 BPSK 0.5 1 48 24 48 4 1 QPSK 0.5 2 96 48 96 4
1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM
0.75 6 288 216
TABLE-US-00009 TABLE 9 channelization for Table 8 Frequency
Frequency Channel (MHz) Country Channel (MHz) Country 240 4920
Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12
5060 Japan 16 5080 Japan 36 5180 USA/Europe 34 5170 Japan 40 5200
USA/Europe 38 5190 Japan 44 5220 USA/Europe 42 5210 Japan 48 5240
USA/Europe 46 5230 Japan 52 5260 USA/Europe 56 5280 USA/Europe 60
5300 USA/Europe 64 5320 USA/Europe 100 5500 USA/Europe 104 5520
USA/Europe 108 5540 USA/Europe 112 5560 USA/Europe 116 5580
USA/Europe 120 5600 USA/Europe 124 5620 USA/Europe 128 5640
USA/Europe 132 5660 USA/Europe 136 5680 USA/Europe 140 5700
USA/Europe 149 5745 USA 153 5765 USA 157 5785 USA 161 5805 USA 165
5825 USA
TABLE-US-00010 TABLE 10 5 GHz, with 40 MHz channels and max bit
rate of 486 Mbps TX ST Code Code Rate Antennas Rate Modulation Rate
NBPSC 13.5 Mbps 1 1 BPSK 0.5 1 27 Mbps 1 1 QPSK 0.5 2 54 Mbps 1 1
16-QAM 0.5 4 108 Mbps 1 1 64-QAM 0.666 6 121.5 Mbps.sup. 1 1 64-QAM
0.75 6 27 Mbps 2 1 BPSK 0.5 1 54 Mbps 2 1 QPSK 0.5 2 108 Mbps 2 1
16-QAM 0.5 4 216 Mbps 2 1 64-QAM 0.666 6 243 Mbps 2 1 64-QAM 0.75 6
40.5 Mbps 3 1 BPSK 0.5 1 81 Mbps 3 1 QPSK 0.5 2 162 Mbps 3 1 16-QAM
0.5 4 324 Mbps 3 1 64-QAM 0.666 6 365.5 Mbps.sup. 3 1 64-QAM 0.75 6
54 Mbps 4 1 BPSK 0.5 1 108 Mbps 4 1 QPSK 0.5 2 216 Mbps 4 1 16-QAM
0.5 4 432 Mbps 4 1 64-QAM 0.666 6 486 Mbps 4 1 64-QAM 0.75 6
TABLE-US-00011 TABLE 11 Power Spectral Density (PSD) mask for Table
10 PSD Mask 2 Frequency Offset dBr -19 MHz to 19 MHz 0 +/-21 MHz
-20 +/-30 MHz -28 +/-40 MHz and greater -50
TABLE-US-00012 TABLE 12 Channelization for Table 10 Frequency
Frequency Channel (MHz) Country Channel (MHz) County 242 4930 Japan
250 4970 Japan 12 5060 Japan 38 5190 USA/Europe 36 5180 Japan 46
5230 USA/Europe 44 5520 Japan 54 5270 USA/Europe 62 5310 USA/Europe
102 5510 USA/Europe 110 5550 USA/Europe 118 5590 USA/Europe 126
5630 USA/Europe 134 5670 USA/Europe 151 5755 USA 159 5795 USA
* * * * *