U.S. patent number 9,271,293 [Application Number 13/784,333] was granted by the patent office on 2016-02-23 for bidirectional iterative beam forming.
This patent grant is currently assigned to INTEL CORPORATION. The grantee listed for this patent is Intel Corporation. Invention is credited to Assaf Kasher, Quinghua Li, Huaning Niu, Ilan Sutskover.
United States Patent |
9,271,293 |
Sutskover , et al. |
February 23, 2016 |
Bidirectional iterative beam forming
Abstract
Bidirectional iterative beam forming techniques are described.
An apparatus may include a wireless device having an antenna
control module operative to initiate beam formation operations
using an iterative training scheme to form a pair of communications
channels for a wireless network, the antenna control module to
communicate training signals and feedback information with a peer
device via the transceiver and phased antenna array using partially
or fully formed high rate channels, and iteratively determine
antenna-array weight vectors for a directional transmit beam
pattern for the phased antenna array using feedback information
from the peer device. Other embodiments are described and
claimed.
Inventors: |
Sutskover; Ilan (Hadera,
IL), Kasher; Assaf (Haifa, IL), Li;
Quinghua (Sunnyvale, CA), Niu; Huaning (Milpitas,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Intel Corporation |
Santa Clara |
CA |
US |
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Assignee: |
INTEL CORPORATION (Santa Clara,
CA)
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Family
ID: |
43661373 |
Appl.
No.: |
13/784,333 |
Filed: |
March 4, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130182666 A1 |
Jul 18, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12262904 |
Oct 31, 2018 |
8626080 |
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12939417 |
Nov 4, 2010 |
8412096 |
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12262904 |
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61035480 |
Mar 11, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B
7/0682 (20130101); H01Q 3/26 (20130101); H04B
7/0617 (20130101); H04B 7/0632 (20130101); H04W
72/046 (20130101) |
Current International
Class: |
H04B
1/00 (20060101); H04W 72/04 (20090101); H04B
15/00 (20060101); H01Q 3/26 (20060101); H04B
7/06 (20060101); H04B 7/00 (20060101) |
Field of
Search: |
;455/25,69,524,525,561,562.1 ;370/329 |
Foreign Patent Documents
Other References
Extended European Search Report received for European Patent
Application No. 09718665.4. mailed Apr. 4, 2014, 8 pages. cited by
applicant.
|
Primary Examiner: Ayotunde; Ayodeji
Attorney, Agent or Firm: Kacvinsky Daisak Bluni PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of, claims benefit of, and
priority to, U.S. patent application Ser. No. 12/262,904, filed
Oct. 31, 2008, entitled "BIDIRECTIONAL ITERATIVE BEAM FORMING", and
U.S. patent application Ser. No. 12/939,417, filed Nov. 4, 2010,
entitled "BIDIRECTIONAL ITERATIVE BEAM FORMING", both of which are
incorporated herein by reference in their entirety.
Claims
The invention claimed is:
1. An apparatus, comprising: a phased antenna array; a transceiver
communicatively coupled to the phased antenna array; and an antenna
control module communicatively coupled to the transceiver and the
phased antenna array, the antenna control module to initiate beam
formation operations using an iterative training scheme to form a
pair of communications channels for a wireless network wherein the
pair of communication channels includes a high rate physical (HRP)
channel and a low rate physical (LRP) channel, receive and send
training signals over the HRP channel, and receive and send
feedback information over the HRP channel.
2. The apparatus of claim 1, comprising: a display; a processor;
and a memory coupled with the processor.
3. The apparatus of claim 1, the formation of the HRP channel
comprising: sending training signals to a peer device over the HRP
channel; receiving feedback information from the peer device over
the LRP channel; and determining antenna-array weight vectors (AWV)
for a directional transmit beam pattern for a phase antenna array
based on the feedback information.
4. The apparatus of claim 1, the antenna control module to send
transmitting timing acquisition sequences over the HRP channel.
5. The apparatus of claim 1, the antenna control module to send
transmitting delay selection sequences over the HRP channel.
6. The apparatus of claim 1, the antenna control module to send
transmitter training signals to a peer device over the HRP channel,
the transmitter training signals for use in forming a directional
transmit beam pattern for the phased antenna array.
7. The apparatus of claim 1, the antenna control module to receive
receiver training signals from a peer device over the HRP to form a
directional receive beam pattern for the phased antenna array.
8. The apparatus of claim 1, the antenna control module to receive
transmitter training signals from a peer device over the HRP to
form a directional transmit beam pattern for a phased antenna array
of the peer device.
9. The apparatus of claim 1, the antenna control module to receive
feedback information from a peer device over the LRP channel using
a directional receive beam pattern for the phased antenna
array.
10. The apparatus of claim 1, the antenna control module to send
feedback information to a peer device over the LRP channel using a
directional transmit beam pattern for the phased antenna array, the
feedback information for use in determining antenna-array weight
vectors (AWV) for a directional transmit beam pattern for a phased
antenna array of the peer device.
11. The apparatus claim 1, the antenna control module to continue
beam forming operations using multiple iterations until a
determined signal-to-noise ratio for data communications is reached
or a determined number of iterations is reached.
12. A method comprising: initiating beam formation operations using
an iterative training scheme to establish a pair of communications
channels between a first device and a second device for a wireless
network wherein the pair of communication channels includes a high
rate physical (HRP) channel and a low rate physical (LRP) channel;
receiving, by the first device, training signals from the second
device over the HRP channel; and sending, by the first device,
feedback information to the second device over the HRP channel.
13. The method of claim 12, the establishment of the HRP channel
comprising: sending, by the first device, training signals to the
second device over the HRP channel; receiving, by the first device,
feedback information from the second device over the LRP channel;
and determining antenna-array weight vectors (AWV) for a
directional transmit beam pattern for a phase antenna array based
on the feedback information.
14. The method of claim 12, the establishment of the HRP channel
comprising transmitting timing acquisition sequences.
15. The method of claim 12, the establishment of the HRP channel
comprising transmitting delay selection sequences.
16. The method of claim 12, comprising sending transmitter training
signals from the first device to the second device over the HRP
channel to form a directional transmit beam pattern for a phased
antenna array of the first device.
17. The method of claim 12, comprising receiving receiver training
signals by the first device from the second device over the HRP
channel to form a directional receive beam pattern for a phased
antenna array of the first device.
18. The method of claim 12, comprising receiving transmitter
training signals by the first device from the second device over
the HRP channel to form a directional transmit beam pattern for a
phased antenna array of the second device.
19. The method of claim 12, comprising: receiving feedback
information by the first device from the second device over the LRP
channel using a directional receive beam pattern for a phased
antenna array of the first device; and determining antenna-array
weight vectors (AWV) for a directional transmit beam pattern for a
phased antenna array of the first device using the feedback
information from the second device.
20. The method of claim 12, comprising sending feedback information
from the first device to the second device over the LRP channel
using a directional transmit beam pattern for a phased antenna
array of the first device, the feedback information for use in
determining antenna-array weight vectors (AWV) for a directional
transmit beam pattern for a phased antenna array of the second
device using the feedback information from the first device.
21. The method of claim 12, comprising communicating training
signals and feedback information, and determining antenna-array
vector weights (AWV) for a directional transmit beam pattern for a
phased antenna array of the first device, using multiple iterations
until a determined signal-to-noise ratio for data communications is
reached or until a determined number of iterations is reached.
22. An article comprising a non-transitory computer-readable
storage medium containing a plurality of instructions that when
executed enable a processor to: initiate beam formation operations
using an iterative training scheme to establish a pair of
communications channels for a wireless network wherein the pair of
communication channels includes a high rate physical (HRP) channel
and a low rate physical (LRP) channel; receive training signals
from a peer device over the HRP channel; and send feedback
information to the peer device over the HRP channel.
23. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to: send training signals to the peer device over the
HRP channel; receive feedback information from the peer device over
the LRP channel; and determine antenna-array weight vectors (AWV)
for a directional transmit beam pattern for a phase antenna array
based on the feedback information.
24. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to transmit timing acquisition sequences to establish
the HRP channel.
25. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to transmit delay selection sequences to establish
the HRP channel.
26. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to send transmitter training signals to the peer
device over the HRP channel to form a directional transmit beam
pattern for a phased antenna array.
27. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to receive receiver training signals from the peer
device over the HRP channel to form a directional receive beam
pattern for a phased antenna array.
28. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to receive transmitter training signals from the peer
device over the HRP channel to form a directional transmit beam
pattern for a phased antenna array of the peer device.
29. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to: receive feedback information from the peer device
over the LRP channel using a directional receive beam pattern for a
phased antenna array; and determine antenna-array weight vectors
(AWV) for a directional transmit beam pattern for the phased
antenna array using the feedback information from the peer
device.
30. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to send feedback information to the peer device over
the LRP channel using a directional transmit beam pattern for a
phased antenna array, the feedback information for use in
determining antenna-array weight vectors (AWV) for a directional
transmit beam pattern for a phased antenna array of the peer device
using the feedback information.
31. The article of claim 22, the non-transitory computer-readable
storage medium comprising instructions that when executed enable
the processor to communicate training signals and feedback
information, and determining antenna-array vector weights (AWV) for
the directional transmit beam pattern for a phased antenna array
using multiple iterations until a determined signal-to-noise ratio
for data communications is reached or until a determined number of
iterations is reached.
Description
BACKGROUND
Wireless communication systems communicate information over a
shared wireless communication medium such as one or more portions
of the radio-frequency (RF) spectrum. Recent innovations in
Millimeter-Wave (mmWave) communications operating at the 60
Gigahertz (GHz) frequency band promises several Gigabits-per-second
(Gbps) throughput within short ranges of approximately 10 meters.
Because of the large signal attenuation and limited transmission
power, many 60 GHz devices will rely on antenna arrays with high
directivity gain to achieve the 10 meter coverage. These devices
use techniques to steer a "beam" from a transmitter antenna array
around obstacles to find the best path to a receiver antenna array,
thereby directing much of the antenna gain towards the receiver
antenna array. Techniques to discover and direct energy between
antenna arrays of peer devices is typically referred to as "beam
forming" or "beam steering" or "beam searching." Beam forming
generally attempts to steer an antenna beam at a transmitter while
at the same time focusing a receiver antenna in the direction of
incoming power from the transmitter. Conventional beam forming
protocols, however, typically take a significant amount of training
time before a final high-speed communication channel is established
between peer devices. Consequently, techniques designed to reduce
overhead associated with training time are desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates one embodiment of a communications system.
FIG. 2 illustrates one embodiment of a wireless network.
FIG. 3 illustrates one embodiment of a phased antenna array.
FIG. 4 illustrates one embodiment of a state diagram.
FIG. 5 illustrates one embodiment of an iterative training
scheme.
FIG. 6A illustrates one embodiment of a first message flow.
FIG. 6B illustrates one embodiment of a second message flow.
FIG. 7 illustrates one embodiment of a graph for beam forming
gain.
FIG. 8 illustrates one embodiment of a third message flow.
FIG. 9 illustrates one embodiment of a phased antenna array.
FIG. 10 illustrates one embodiment of a logic flow.
FIG. 11 illustrates one embodiment of an article of
manufacture.
DETAILED DESCRIPTION
Various embodiments may be generally directed to bidirectional
iterative beam forming techniques for wireless communication
systems. Some embodiments may be particularly directed to an
enhanced bidirectional beam forming protocol designed to
concurrently generate bidirectional communication channels between
two or more wireless devices over a wireless network, such as a 60
Ghz mmWave wireless video area network (WVAN) or wireless personal
area network (WPAN), for example. Such networks are sometimes
referred to as "piconets" due to their limited transmission ranges
and participating devices. The enhanced bidirectional beam forming
protocol generates additional antenna gain for directional antenna
transmissions, thereby allowing training and feedback information
to be communicated at a higher data rate, resulting in reduced
training time and overhead in setting up bidirectional
communication channels between two wireless devices.
Since the path loss at 60 GHz band is relatively high and the
efficiency of power amplifiers at 60 GHz is relatively low (e.g.,
CMOS power amplifiers), directional transmission is needed to
achieve the desired coverage area (e.g., approximately 10 meters).
Namely, the antenna array gain from both transmit and receive beam
forming is needed to acquire the signal-to-noise ratio (SNR) for
reliable data communications. A beam forming protocol is typically
used to find the optimal phase values which maximize receiver SNR,
received power or other criterion.
Currently, there are several different types of beam forming
protocols for implementing directional transmission techniques. A
first directional transmission technique is referred to as a sector
scan. It forms several directional beams using predefined weights.
Calibration is required, however, in order to form the requisite
beams. Another technique is based on singular value decomposition
(SVD), which typically does not require calibration. SVD allows
transmission over selected singular values by using the singular
vectors for antenna patterns. In particular, the singular vector
associated with the largest Eigen value typically works well. It is
worthy to note, however, that in order to select the singular
values and singular vectors, a device typically has to have an
estimation of the entire MIMO channel, e.g., the channel from every
antenna element at the transmitter to every antenna element at the
receiver end. While the SVD technique provides improved
performance, it needs feedback information due to lack of channel
reciprocity. This potentially introduces channel delay into the SVD
directional transmission technique.
A piconet typically implements two general types of communications
transmissions, each having different transmission envelopes or
characteristics. For example, a first type of transmission may be a
directional transmission and a second type of transmission may be
an omni-directional transmission. The different types of
transmissions may occur at different transmission rates. For
example, directional transmissions may be performed using a higher
rate channel, and the second type of transmission may be performed
using a lower rate channel. In a WirelessHD network, for example,
the directional transmissions may be performed using a high rate
physical (HRP) channel, and the second type of transmission may be
performed using a low rate physical (LRP) channel. The HRP channel
may achieve a higher rate than the LRP channel, in part, through
the utilization of larger amounts of bandwidth.
Since the location of a pair of devices is unknown during
initialization, conventional techniques typically utilize a
combination of LRP channels and HRP channels for beam forming
operations. For example, one conventional technique utilizes a beam
forming protocol for phased array antennas that is based on an
iterative training scheme. In one embodiment, for example, the
iterative trainings scheme may comprise a power iteration scheme.
This beam forming protocol designed for one way high rate data
transmissions over a HRP channel, where the reverse link suffers
from low rate data transmissions over a LRP channel. Feedback
information for the iterative search process is transmitted over
the LRP channel, which dramatically slows down beam forming
operations. This may be acceptable for applications where high rate
data transmissions are needed in only one direction, such as for
video traffic from a media source to a media sink. For applications
where high rate data communications are needed in both directions,
such as for computing centric applications, however, this
introduces unwarranted delay in beam forming operations.
To solve these and other problems, various embodiments implement an
enhanced bidirectional beam forming protocol to perform
bidirectional beam forming operations to reduce training overhead
and link latency during beam forming operations. Some embodiments
delay feedback information until two-way transmit (or receive) beam
forming weights are trained, and then send the feedback over a beam
formed link with a higher rate (e.g., HRP channel). This may reduce
or eliminate the need to use a LRP channel for beam forming
operations. Additionally or alternatively, some embodiments
interleave transmit and receive beam forming operations to allow
use of partially trained links to communicate feedback information
at a higher data rate. This reduces the need to use an LRP channel
during beam forming operations.
In one embodiment, for example, a wireless device may include a
phased antenna array communicatively coupled to a transceiver. The
wireless device may further include an antenna control module
communicatively coupled to the transceiver and the phased antenna
array. The antenna control module may be arranged to perform beam
formation operations using an iterative training scheme to form a
pair of communications channels between the wireless device and a
peer device. For example, the antenna control module may be
arranged to communicate training signals and feedback information
with the peer device via the transceiver and phased antenna array.
The information is communicated using almost exclusively high rate
channels, or through partial use of low rate channels to bootstrap
setup of the high rate channels. This reduces training time for the
devices. The antenna control module iteratively determines
antenna-array weight vectors (AWVs) for a directional transmit beam
pattern for the phased antenna array using feedback information
from the peer device. Once trained the wireless devices may be used
for high-speed bidirectional data communications.
Additionally or alternatively, the antenna control module of a
wireless device may initiate bidirectional beam formation
operations using an iterative training scheme to form a pair of
communications channels for a wireless network. The antenna control
module may be arranged to interleave transmit and receive beam
forming operations for a first wireless device and a second
wireless device to allow feedback information received by the first
wireless device from the second wireless device to be communicated
over a higher data rate channel (e.g., HRP channel).
The wireless devices as described herein may coordinate operations
between each other. The coordination may involve the
uni-directional or bi-directional exchange of information. In some
embodiment, the information can be implemented as signals. For
example, training information may comprise training signals or
sequences. Further embodiments, however, may alternatively employ
data messages. The terms "training information" and "feedback
information" are meant to include both signals and data messages,
depending on a given implementation. The embodiments are not
limited in this context.
Embodiments of the enhanced bidirectional beam forming protocol
provide several advantages over conventional beam forming
techniques. For example, the enhanced bidirectional beam forming
protocol trains both directions of the communications link,
allowing for a more structured process prior to a bidirectional
operation that is more symmetric, such as in a PC environment. This
provides superior performance relative to conventional beam forming
protocols that allows the receiver of the high rate transmission to
answer (e.g., ACKs etc.) in a low rate dedicated physical layer
(PHY) that may not require training of the reverse link. In another
example, the enhanced bidirectional beam forming protocol exploits
resources more efficiently. The feedback provided during each
iteration is based on partially trained antenna arrays. In yet
another example, an external listening device can identify
transmissions from both ends of the link. This situation is
beneficial when an independent station wishes to assess the amount
of interference it is going to suffer from the regarded link. If
only one side of the link does the transmission, however, then the
station has knowledge about interference only about the forward
link and not about the reverse link. These are only a few examples
of the advantages provided by the enhanced bidirectional beam
forming protocol, and it may be appreciated that many other
advantages exist as well.
FIG. 1 illustrates a block diagram of one embodiment of a
communications system 100. In various embodiments, the
communications system 100 may comprise multiple nodes. A node
generally may comprise any physical or logical entity for
communicating information in the communications system 100 and may
be implemented as hardware, software, or any combination thereof,
as desired for a given set of design parameters or performance
constraints. Although FIG. 1 may show a limited number of nodes by
way of example, it can be appreciated that more or less nodes may
be employed for a given implementation.
In various embodiments, the communications system 100 may comprise,
or form part of a wired communications system, a wireless
communications system, or a combination of both. For example, the
communications system 100 may include one or more nodes arranged to
communicate information over one or more types of wired
communication links. Examples of a wired communication link, may
include, without limitation, a wire, cable, bus, printed circuit
board (PCB), Ethernet connection, peer-to-peer (P2P) connection,
backplane, switch fabric, semiconductor material, twisted-pair
wire, co-axial cable, fiber optic connection, and so forth. The
communications system 100 also may include one or more nodes
arranged to communicate information over one or more types of
wireless communication links. Examples of a wireless communication
link may include, without limitation, a radio channel, infrared
channel, radio-frequency (RF) channel, Wireless Fidelity (WiFi)
channel, a portion of the RF spectrum, and/or one or more licensed
or license-free frequency bands.
The communications system 100 may communicate information in
accordance with one or more standards as promulgated by a standards
organization. In one embodiment, for example, various devices
comprising part of the communications system 100 may be arranged to
operate in accordance with one or more of the WirelessHD.TM.
specifications, standards or variants, such as the WirelessHD
Specification, Revision 1.0d7, Dec. 1, 2007, and its progeny as
promulgated by WirelessHD, LLC (collectively referred to as the
"WirelessHD Specification"). The WirelessHD Specification defines a
next generation wireless digital network interface for consumer
electronic products. Specifically, the WirelessHD Specification
enables wireless connectivity for streaming high-definition content
between various wireless devices, such as a source device and
high-definition displays. The WirelessHD Specification defines a
wireless protocol that enables the creation of a WVAN. In a current
instantiation of the WirelessHD Specification, the MAC and PHY are
defined to support the wireless delivery of uncompressed high
definition audio and video at formats up to 1080 p at 60 Hertz (Hz)
with 24 bit color at a range that is typically at least 10 meters.
In addition, the delivery of compressed audio/visual (AV) streams
and data is also supported at a similar range. An adaptation
sub-layer enables network and service set up by supporting
authentication, advanced device and connection control.
Although some embodiments may be described with reference to the
WirelessHD Specification by way of example, it may be appreciated
that the techniques described herein may also be implemented for
other wireless standards as promulgated by other standards
organizations as well, such as the International Telecommunications
Union (ITU), the International Organization for Standardization
(ISO), the International Electrotechnical Commission (IEC), the
Institute of Electrical and Electronics Engineers (information
IEEE), the Internet Engineering Task Force (IETF), and so forth. In
various embodiments, for example, the communications system 100 may
communicate information according to one or more IEEE 802.11
standards for wireless local area networks (WLANs) such as the
information IEEE 802.11 standard (1999 Edition, Information
Technology Telecommunications and Information Exchange Between
Systems--Local and Metropolitan Area Networks--Specific
Requirements, Part 11: WLAN Medium Access Control (MAC) and
Physical (PHY) Layer Specifications), its progeny and supplements
thereto (e.g., 802.11a, b, g/h, j, n, VHT SG, and variants); IEEE
802.15.3 and variants; IEEE 802.16 standards for WMAN including the
IEEE 802.16 standard such as 802.16-2004, 802.16.2-2004,
802.16e-2005, 802.16f, and variants; next generation WirelessHD
(NGmS) progeny and variants; European Computer Manufacturers
Association (ECMA) TG20 progeny and variants; and other wireless
networking standards. The embodiments are not limited in this
context.
The communications system 100 may communicate, manage, or process
information in accordance with one or more protocols. A protocol
may comprise a set of predefined rules or instructions for managing
communication among nodes. In various embodiments, for example, the
communications system 100 may employ one or more protocols such as
a beam forming protocol, medium access control (MAC) protocol,
Physical Layer Convergence Protocol (PLCP), Simple Network
Management Protocol (SNMP), Asynchronous Transfer Mode (ATM)
protocol, Frame Relay protocol, Systems Network Architecture (SNA)
protocol, Transport Control Protocol (TCP), Internet Protocol (IP),
TCP/IP, X.25, Hypertext Transfer Protocol (HTTP), User Datagram
Protocol (UDP), and so forth.
The communications system 100 also may be arranged to operate in
accordance with standards and/or protocols for media processing.
Examples of media processing standards include, without limitation,
the High Definition Television (HDTV) standards as defined by the
ITU Radiocommunication Sector (ITU-R), such as the Recommendation
BT.709-5, Parameter Values for the HDTV Standards For Production
and International Programme Exchange, published April 2002, the
Digital Video Broadcasting Terrestrial (DVB-T) broadcasting
standard, the ITU/IEC H.263 standard, Video Coding for Low Bitrate
Communication, ITU-T Recommendation H.263v3, published November
2000 and/or the ITU/IEC H.264 standard, Video Coding for Very Low
Bit Rate Communication, ITU-T Recommendation H.264, published May
2003, Motion Picture Experts Group (MPEG) standards (e.g., MPEG-1,
MPEG-2, MPEG-4), and/or High performance radio Local Area Network
(HiperLAN) standards. Examples of media processing protocols
include, without limitation, Session Description Protocol (SDP),
Real Time Streaming Protocol (RTSP), Real-time Transport Protocol
(RTP), Synchronized Multimedia Integration Language (SMIL)
protocol, and/or Internet Streaming Media Alliance (ISMA) protocol.
The embodiments are not limited in this context.
As shown in FIG. 1, the communications system 100 may comprise a
transmitter node 102 coupled to a plurality of receiver nodes
104-1-n, where n may represent any positive integer value. In
various embodiments, the transmitter node 102 and the plurality of
receiver nodes 104-1-n may be implemented as various types of
wireless devices. Examples of wireless devices may include, without
limitation, an IEEE 802.15.3 piconet controller (PNC), a
controller, an IEEE 802.11 Private Basic Service Set (PBSS) Control
Point (PCP), a coordinator, a station, a subscriber station, a base
station, a wireless access point (AP), a wireless client device, a
wireless station (STA), a laptop computer, ultra-laptop computer,
portable computer, personal computer (PC), notebook PC, handheld
computer, personal digital assistant (PDA), cellular telephone,
combination cellular telephone/PDA, smartphone, pager, messaging
device, media player, digital music player, set-top box (STB),
appliance, workstation, user terminal, mobile unit, consumer
electronics, television, digital television, high-definition
television, television receiver, high-definition television
receiver, and so forth. In such embodiments, the transmitter node
102 and the receiver nodes 104-1-n may comprise one more wireless
interfaces and/or components for wireless communication such as one
or more transmitters, receivers, transceivers, chipsets,
amplifiers, filters, control logic, network interface cards (NICs),
antennas, antenna arrays, and so forth. Examples of an antenna may
include, without limitation, an internal antenna, an
omni-directional antenna, a monopole antenna, a dipole antenna, an
end fed antenna, a circularly polarized antenna, a micro-strip
antenna, a diversity antenna, a dual antenna, an antenna array, and
so forth. In one embodiment, certain devices may include antenna
arrays of multiple antennas to implement various adaptive antenna
techniques and spatial diversity techniques. Some embodiments for
an enhanced bidirectional beam forming protocol are discussed in
the context of using phased antenna arrays. The enhanced
bidirectional beam forming protocol may be used with any type of
antenna having a need for feedback information, and the embodiments
are not limited in this respect. For example, while some aspects of
an enhanced bidirectional beam forming protocol are designed to
enable a phased antenna array at both ends of the link, a
switched-sector antenna (e.g., an antenna with predefined few
directions that can switch from one direction to another) may still
use this protocol.
For purposes of illustration and not limitation, examples for an
enhanced bidirectional beam forming protocol may be given with
reference to WirelessHD networks, protocols and devices. It may be
appreciated, however, that an enhanced bidirectional beam forming
protocol may be implemented with other types of networks, protocols
and devices. For example, an enhanced bidirectional beam forming
protocol may be implemented for a NGmS network, protocol or
devices, and still fall within the intended scope of the
embodiments. The embodiments are not limited in this context.
In various embodiments, the transmitter node 102 and the receiver
nodes 104-1-n may comprise or form part of a wireless network 106.
In one embodiment, for example, the wireless network 106 may
comprise a WVAN as defined by the WirelessHD Specification. In the
context of a WVAN, both nodes 102, 104 may be implemented as
WirelessHD compliant devices. In a WVAN, the transmitter node 102
may be communicatively coupled to one or more receiver nodes
104-1-n. In accordance with the WirelessHD Specification and
nomenclature, one or both of the nodes 102, 104 may be implemented
as a coordinator or a station. A coordinator is normally, but not
always, a device that is a sink for media information (e.g., audio
or video data). The coordinator typically includes a display, and
in some cases a media storage device such as a personal video
recorder (PVR), media server, or STB. A station may comprise a
device that either has media information that it can source or
sink, potentially at the same time.
Although some embodiments may be described with the wireless
network 106 implemented as a WVAN network for purposes of
illustration, and not limitation, it can be appreciated that the
embodiments are not limited in this context. For example, the
wireless network 106 may comprise or be implemented as various
types of wireless networks and associated protocols suitable for a
WPAN, a Wireless Local Area Network (WLAN), a Wireless Metropolitan
Area Network, a Wireless Wide Area Network (WWAN), a Broadband
Wireless Access (BWA) network, a radio network, a television
network, a satellite network such as a direct broadcast satellite
(DBS) network, and/or any other wireless communications network
configured to operate in accordance with the described
embodiments.
As shown in the embodiment of FIG. 1, the transmitter node 102 may
be coupled to receiver nodes 104-1-n by wireless communication
links 108-n. A particular wireless communication link (e.g.,
wireless communication link 108-1) may be arranged to establish one
or more common or dedicated connections between the transmitter
node 102 and a particular receiver node (e.g., receiver node
104-1). In various embodiments, a particular wireless communication
link (e.g., wireless communication link 108-1) may include multiple
virtual channels, with each of the virtual channels comprising a
point-to-point logical connection from the transmitter node 102 to
a particular receiver node (e.g., receiver node 104-1). In various
implementations, multiple virtual channels may share a physical
link, with each virtual channel comprising dedicated resources or
bandwidth of the physical link.
In various embodiments, the nodes 102, 104 may communicate using a
physical layer component (PHY), such as a high-rate PHY (HRP). In
one embodiment, for example, the HRP supports multi-Gb/s throughput
at a distance of approximately 10 meters through adaptive antenna
technology. Because of this, the antenna pattern used for the HRP
is highly directional. The HRP is optimized for the delivery of
uncompressed high-definition video, although other data can be
communicated using the HRP. To support multiple video resolutions,
the HRP has more than one data rate defined. The HRP carries
isochronous data such as audio and video, asynchronous data, MAC
commands, antenna beam forming information, and higher layer
control data for A/V devices. It may be appreciated that the use of
HRP and LRP are for WirelessHD devices, and other types of PHYs may
be used for other types of devices. With respect to the NGmS
protocol, for example, the high rate PHY may be referred to as the
OFDM PHY or the SC PHY depending on the modulation type, while the
low rate PHY is called a CONTROL PHY or a MCS of the SC PHY. In the
latter case, the low rate transmissions will be based on wide
bandwidth with significant processing gain that renders the
transmission more robust. Other types of high rate and low rate
PHYs may be used for different types of devices, and the
embodiments are not limited in this context.
In various embodiments, the nodes 102, 104 may also communicate
using a low-rate PHY (LRP). The LRP is a multi-Mb/s bidirectional
link that also provides a relatively short range (e.g., 10 meters).
One or more data rates are defined for the LRP, with the lower data
rates having near omni-directional coverage while the highest data
rates are directional, although this is not necessarily binding.
For example, some arrangements may use higher data rates of LRP in
almost-omni directional transmissions. Because the LRP has near
omni-directional modes, it can be used for both unicast and
broadcast connections. Furthermore, because all stations support
the LRP, it can be used for station-to-station links for WirelessHD
devices, although this may not be possible for NGmS devices. The
LRP supports multiple data rates, including directional modes, and
is used to carry low-rate isochronous data such as audio, low-rate
asynchronous data, MAC commands including the beacon,
acknowledgements for HRP packets, antenna beam forming information,
capabilities information, and higher layer control data for A/V
devices.
In some cases (not all) the HRP and LRP may operate in overlapping
frequency bands and so they are coordinated by the MAC. The media
access scheme may include a time division multiple access (TDMA)
format, a frequency division multiple access (FDMA) format, a
TDMA/FDMA format, a code division multiple access (CDMA), a
wide-band CDMA (WCDMA) format, an orthogonal frequency division
multiple access (OFDMA) format, and so forth. The embodiments are
not limited in this context.
The WVAN typically supports two types of devices. In one
embodiment, for example, a WVAN may support a coordinator and a
station. The coordinator controls the timing in the piconet, keeps
track of the members of the WVAN, is able to transmit and receive
using the LRP, may be able to transmit data using the HRP, and may
be able to receive data using the HRP. A station is able to
transmit and receive using the LRP, may initiate stream
connections, may be able to transmit data using the HRP, and may be
able to receive data using the HRP. A station may be capable of
acting as a coordinator in the WVAN. Such a station is referred to
as being coordinator capable.
In addition to the two MAC personalities of coordinator and
station, each device in a WirelessHD WVAN will have one of four
different PHY capabilities as shown in Table 1 as follows:
TABLE-US-00001 TABLE 1 PHY Description HR0 A device that is not
able to either receive or transmit using the HRP HRRX A device that
is able to receive in the HRP, but is not able to transmit using
the HRP HRTX A device that is able to transmit in the HRP, but is
not able to receive using the HRP HRTR A device that is able to
both transmit and receive using the HRP
All compliant WirelessHD devices are able to transmit and receive
using the LRP. Both the HRP and LRP may provide multiple data
rates, as specified in the WirelessHD Specification.
In various embodiments, the transmitter node 102 and the receiver
nodes 104-1-n may be arranged to communicate various types of media
information in multiple communication frames. The various types of
media information may include image information, audio information,
video information, AV information, and/or other data provided from
the media source 108. In various embodiments, the information may
be associated with one or more images, image files, image groups,
pictures, digital photographs, music file, sound files, voice
information, videos, video clips, video files, video sequences,
video feeds, video streams, movies, broadcast programming,
television signals, web pages, user interfaces, graphics, textual
information (e.g., encryption keys, serial numbers, e-mail
messages, text messages, instant messages, contact lists, telephone
numbers, task lists, calendar entries, hyperlinks), numerical
information, alphanumeric information, character symbols, and so
forth. The information also may include command information,
control information, routing information, processing information,
system file information, system library information, software
(e.g., operating system software, file system software, application
software, game software), firmware, an application programming
interface (API), a program, an applet, a subroutine, an instruction
set, an instruction, computing code, logic, words, values, symbols,
and so forth.
The transmitter node 102 may be arranged to receive media content
from a media source node 110 to be unicast and/or multicast to one
or more of the receiver nodes 104-1-n. In various embodiments, the
transmitter node 102 may be arranged to receive media content from
the source node 110. The media source node 110 generally may
comprise any media source capable of delivering static or dynamic
media content to the transmitter node 102. In one embodiment, for
example, the media source node 110 may comprise a multimedia server
arranged to provide broadcast or streaming media content to the
transmitter node 102. In some implementations, the media source
node 110 may form part of a media distribution system (DS) or
broadcast system such as an over-the-air (OTA) broadcast system, a
radio broadcast system, a television broadcast system, a satellite
broadcast system, and so forth. In some implementations, the media
source node 110 may be arranged to deliver media content
pre-recorded and stored in various formats for use by a device such
as a Digital Versatile Disk (DVD) device, a Video Home System (VHS)
device, a digital VHS device, a digital camera, video camera, a
portable media player, a gaming device, and so forth.
As shown in the embodiment of FIG. 1, for example, the transmitter
node 102 may be coupled to the media source node 110 through a
communication medium 112. The communication medium 112 generally
may comprise any medium capable of carrying information signals
such as a wired communication link, wireless communication link, or
a combination of both, as desired for a given implementation. In
various embodiments, the communication medium 112 may comprise a
wired communication link implemented as a wired Ethernet and/or P2P
connection, for example. In such embodiments, information may be
communicated over the communication medium 112 in accordance with
the information IEEE 802.3, and the transmitter node 102 may
receive media content from the media source node 110 substantially
loss-free.
Although some embodiments may be described with the communication
medium 112 implemented as a wired Ethernet and/or P2P connection
for purposes of illustration, and not limitation, it can be
appreciated that the embodiments are not limited in this context.
For example, the communication medium 112 between the transmitter
node 102 and the source node 110 may comprise various types of
wired and/or wireless communication media and, in some cases, may
traverse one or more networks between such devices.
The transmitter node 102 may be arranged to buffer media content
and to parse or fragment the media content into communication
frames for unicast or multicast transmission to the receiver nodes
104-1-n. In some implementations, the transmitter node 102 may be
arranged to parse or fragment the received media content as it is
read into a buffer. In some embodiments, the media content provided
to the transmitter node 102 may be delivered as one or more media
frames. Each media frame may comprise a discrete data set having a
fixed or varying length, and may be represented in terms of bits or
bytes such as 16 kilobytes (kB), for example. It can be appreciated
that the described embodiments are applicable to various types of
communication content or formats, such as frames, packets,
fragments, cells, units, and so forth.
In various embodiments, the transmitter node 102 may be arranged to
create a sequence of media frames to be broadcast over one or more
of the wireless communication links 108-1-n. Each media frame may
comprise a discrete data set having fixed or varying lengths, and
may be represented in terms of bits or bytes. While multicasting,
each media frame may contain a destination address comprising a
group address corresponding to multiple intended recipients, such
as receiver nodes 104-1-n. In some embodiments, the destination
address may refer to all receiver nodes 104-1-n within the wireless
network 106.
FIG. 2 illustrates a block diagram of one embodiment of a wireless
network 200. For ease of illustration, and not limitation, the
wireless network 200 depicts a limited number of nodes by way of
example. It can be appreciated that more nodes may be employed for
a given implementation.
As shown, the wireless network 200 may comprise a wireless device
202 coupled to a wireless device 204. In various embodiments, the
wireless communications system 200 may comprise or be implemented
by one or more elements of the communications system 100 of FIG. 1,
such as wireless network 100, transmitter node 102, and receiver
nodes 104-1-n. The embodiments are not limited in this context.
In one embodiment, for example, the wireless device 202 and the
wireless device 204 may be implemented as WirelessHD compliant
devices, and the wireless network 200 may be implemented as a WVAN
network. In such an embodiment, the wireless network 200 may
communicate information in accordance with the WirelessHD
Specification and associated techniques, and the wireless device
202 may comprise a WirelessHD compliant device communicatively
coupled to the wireless device 204 comprising another WirelessHD
compliant device. In various implementations, the wireless network
200 may support a unicast and/or multicast communication
environment for distributing media content by unicasting and/or
multicasting from the wireless device 202 to the wireless device
204. Typically, the wireless devices 202, 204 will utilize unicast
or multicast techniques based upon the type of channel being used.
For example, the wireless devices 202, 204 will utilize unicast
techniques when using a HRP channel, and multicast techniques when
using a LRP channel. The embodiments are not limited in this
context.
In one embodiment, for example, the wireless devices 202, 204 each
may include the capability to establish one or more wireless
communications channels 206 using respective transceivers 205, 205a
coupled to respective antenna control modules 208, 208a coupled to
respective phased antenna arrays 210, 210a. In various embodiments,
the communications channel 206 may be implemented at the MAC layer
of the communication protocol stack within a transceiver and/or
wireless communication chipset of a wireless device.
FIG. 3 illustrates one embodiment of wireless system 300 suitable
for performing analog beam forming. The wireless system 300 may be
implemented for the nodes 102, 104-1-n as described with reference
to FIG. 1, and/or the wireless nodes 202, 204 as described with
reference to FIG. 2.
In the illustrated embodiment shown in FIG. 3, the wireless system
300 may comprise a more detailed diagram for a pair of phased
antenna arrays 210, 210a implemented for respective wireless
devices 202, 204. The phased antenna arrays 210, 210a may be
communicatively coupled to the respective antenna control modules
208, 208a. The phased antenna array 210 may comprise a transmitter
antenna array 310 and a receiver antenna array 320. The phased
antenna array 210a may comprise a transmitter antenna array 330 and
a receiver antenna array 340. Although the antenna arrays 310, 320
and the antenna arrays 330, 340 may be illustrated a separate
antenna arrays, it may be appreciated that each may be implemented
using a single antenna array using different transmit and receive
coefficients, vectors or other suitable antenna parameters.
The transmitter antenna arrays 310, 330 may comprise respective
power amplifiers 312-1-a and power amplifiers 332-1-f each coupled
to respective phase shifters 314-1-b and phase shifters 334-1-g.
The phase shifters 314-1-b and phase shifters 334-1-g may each be
coupled to respective antennas 316-1-c and antennas 336-1-h. The
receiver antenna arrays 320, 240 may comprise respective antennas
326-1-d and antennas 346-1-i each coupled to respective phase
shifters 324-1-e and phase shifters 344-1-j. The phase shifters
324-1-e and phase shifters 344-1-j may each be coupled to
respective low noise amplifiers (LNA) 322-1-r and LNA 342-1-s,
which are in turn each coupled to respective combiners 346, 348. It
may be appreciated that the transmitter and receiver chains can
share phase shifters and/or amplifiers as desired for a given
implementation. The embodiments are not limited in this
context.
The wireless devices 202, 204 may use the respective phased antenna
arrays 210, 210a to communicate control information and media
information over a wireless shared media 350. The transmitter
antenna array 310 and the receiver antenna array 340 of the
respective wireless devices 202, 204 may communicate information
using an HRP channel 352-1 and/or a LRP channel 354-1. The
transmitter antenna array 330 and the receiver antenna array 320 of
the respective wireless devices 204, 202 may communicate
information using an HRP channel 352-2 and/or a LRP channel 354-2.
In one embodiment, the HRP channels 352-1, 352-2 may be implemented
as directional channels operating at higher rate data communication
speeds, and the LRP channels 354-1, 354-2 may be implemented as
omni-directional channels operating at lower rate data
communications speeds.
The antenna control modules 208, 208a may use the respective
transceivers 205, 205a and respective phased antenna arrays 210,
210a to perform beam forming operations. The beam forming
operations may include explicit feedback beam forming, which
supports all types of WirelessHD compliant devices, such as HR0,
HRRX, HRTX and HRTR. There is no requirement that the transmitter
and the receiver for a station are the same and no calibration is
required. The beam forming operations may also include implicit
feedback beam forming, which is typically used when both the source
and destination are HRTR capable.
In order to provide data rates on the order of Gbps at
approximately 10 meters for 60 GHz mmWave operations, the phased
antenna arrays 210, 210a are implemented as high gain antenna
networks in the 60 GHz frequency band. The phased antenna arrays
210, 210a can create beams that can be steered around obstacles to
find a best path between the wireless devices 202, 204. The antenna
control modules 208, 208a may cooperate to implement an enhanced
bidirectional beam forming protocol suitable for beam search and
beam tracking operations. Beam search is a technique of estimating
transmitter and receiver antenna-array weight vectors (AWVs) that
result in a desired beam with an acceptable level of gain or SNR
over the HRP channels 352-1, 352-2. Beam tracking is a technique of
tracking transmitter and receivers AWVs that correspond to an
existing beam over time due to small perturbations of the HRP
channels 352-1, 352-2. While beam search is typically a stand-alone
technique using a dedicated time interval, beam tracking takes
place during data transfer and is appended to existing HRP packets
and corresponding ACK packets.
FIG. 4 illustrates one embodiment of a state diagram 400. The state
diagram 400 illustrates state transitions for adaptive beam forming
using the phased antenna arrays 210, 210a. In the illustrated
embodiment shown in FIG. 4, the wireless device 202 may be in an
idle state 402, and detect a peer device (e.g., wireless device
204) within communication range of the wireless device 202. The
wireless device 202 may exit the idle state 402, and enter a beam
formation state 404. The wireless device 202 may initiate beam
formation operations using an iterative training scheme to form a
pair of communications channels HRP 352-1, 352-2 between the
wireless devices 202, 204. For example, the antenna control module
208 for the wireless device 202 may be arranged to communicate
training signals and feedback information with the wireless device
204 via the transceiver 205 and phased antenna array 210. The
information is communicated using exclusively the HRP channels
352-1, 352-2, while reducing or eliminating the need to use the LRP
channels 354-1, 354-2. This reduces training time for the devices.
The antenna control module 208 iteratively determines AWVs for a
directional transmit beam pattern for the phased antenna array 210
using feedback information from the wireless device 204. Once
trained the wireless devices 202, 204 may exit the beam formation
state 404, and enter a data transfer state 406 to use the HRP
channels 352-1, 352-2 for bidirectional high rate data
communications.
FIG. 5 illustrates one embodiment of iterative training scheme for
a wireless system 500. Since the path loss in the 60 GHz frequency
band is very high and the efficiency of CMOS power amplifiers at 60
GHz is low, directional transmission is needed to achieve the
desired 10 meter coverage. The array gain from transmit and receive
beam forming operations is needed to acquire the desired SNR for
reliable data communications. Currently, there are several
different beam forming protocols to acquire directional
transmissions. The first beam forming protocol uses the sectored
antenna approach, which switches among several preformed beams. The
second beam forming protocol uses phased antenna arrays where
transmit and receive beams are formed by changing the phases of the
input and output signals of each antenna element, as described with
reference to FIG. 3.
The second beam forming protocol uses an iterative training
approach. An iterative training process utilizes training sequences
and feedback in successive iterations in order to train
transmitters or receivers. The iterative training approach provides
the advantage of distributing transmit power to multiple power
amplifiers, and the beam can be adaptively steered. It is worthy to
note that this discussion is limited to only a single data stream
for purposes of clarity, although some embodiments may be
implemented for multiple data streams as well. A brief overview of
iterative training is provided below to better illustrate and
describe the operations and benefits of the enhanced bidirectional
beam forming protocol.
In one embodiment, the desired beam forming weights at the receiver
(Rx) 504 and transmitter (Tx) 502, denoted by vectors u and v,
maximize the gain of the beamformed channel as shown in Equation
(1) as follows:
.times..times..times..times..times..times. ##EQU00001## where H is
the effective channel matrix between transmitter 502 and receiver
504; u.sup.HH{circumflex over (v)} is the beam formed scalar
channel for beam forming weights u and {circumflex over (v)}; and u
and v are the normalized beam forming vectors at the receiver 504
and transmitter 502 respectively. The effective channel matrix
incorporates the effects of the transmit/receive weighting matrixes
and the wireless channel, and it is the product of the transmit
weighting matrix B.sub.t, wireless channel H.sub.w, the receive
weighting matrix B.sub.r e.g., H=B.sub.rH.sub.wB.sub.t. The weight
entries on the i-th row of B.sub.r form the i-th effective receive
antenna and similarly the weight entries on the i-th column of
B.sub.t form the i-th effective transmit antenna. The entry on the
i-th row and j-th column of H is the channel response between the
i-th effective receive antenna and the j-th effective transmit
antenna. If H is known, then u and v can be computed using the
singular value decomposition (SVD) of H. However, H is usually
unknown at both transmitter 502 and receiver 504 for 60 GHz
systems. Consequently, iterative training is used as an efficient
scheme to obtain u and v, and which does not require costly
training to learn about the whole H.
Beam forming is needed before the transmission of the data packet.
In current protocols and for a P2P scheduled training, and for
systems without RF transceiver chain calibration, the beam forming
weights of the phased antenna arrays are gradually refined during
the beam refinement phase that consumes a significant overhead of
about 400 microseconds (.mu.s), for example. It is desirable to
reduce the training overhead as much as possible for high network
throughput. In the state of the art, iterative training is the
scheme employed for the beam refinement because of its superior
performance. It is iterative and each iteration has two steps,
e.g., the training of maximum ratio combining (MRC) weights and the
training of the maximum ratio transmission (MRT) weights, as shown
in FIG. 5 and Equation (2) as follows. Step 1: u(i)=norm(Hv(i))
Step 2: v(i+1)=norm(H.sup.Hu(i)) (2) where
.function. ##EQU00002## normalizes the magnitude of the beam
forming vector. For clarity and simplicity, the noise term is not
evaluated. At the i-th iteration, the transmitter 502 has the
transmit beam forming vector v(i), which comes from the feedback
from the receiver 504.
In the first step in Equation (2), the transmitter 502 sends
training symbols to the receiver 504 using v(i), and the receiver
504 estimates the receive beam forming weights that maximize the
received signal strength for the transmit vector v(i) as follows.
The receiver measures the response on each effective receive
antenna respectively, and the measured responses form the vector
Hv(i). The receive beam forming vector maximizing the received
signal (e.g., the MRC vector), is shown in Equation (3) as follows:
u(i)=norm(Hv(i)) (3)
In the second step in Equation (2), the transmitter 502 sends
training symbols through each effective transmit antenna
respectively and the receiver 504 estimates the transmit beam
forming weights that maximize the received signal strength for the
receive vector u(i) as follows. The receiver uses u(i) as the
receive vector and measures the beam formed channel response for
each effective transmit antenna in H respectively. The measured
channel responses form the vector u.sup.H(i)H. The transmit beam
forming vector maximizing the received signal (e.g., the MRT
vector), is shown in Equation (4) as follows:
v.sup.H(i+1)=norm(u.sup.H(i)H) or v(i+1)=norm(H.sup.Hu(i)) (4) The
value for v(i+1) is fed back to the transmitter 502 for the
(i+1)-th iteration. The values for u(i) and v(i) gradually
converges to the ideal u and v as each iteration completes.
Iterative training is currently used by certain conventional beam
forming protocols, such as those currently implemented by the
WirelessHD Specification. The conventional beam forming protocol
utilized by the WirelessHD Specification, however, introduces a
significant amount of training overhead and link latency. It is
also designed for training a link in one direction at a time, which
may be suitable to digital television sets that are designed to
operate mainly as receivers and less as transmitters. A PC
environment is different, however, and focus is placed on both
transmitting and receiving operations. The enhanced bidirectional
beam forming protocol reduces link latency for training
bidirectional links, and is described in further detail with
reference to FIG. 6.
FIG. 6A illustrates one embodiment of a message flow 600. The
message flow 600 illustrates a message flow for an enhanced
bidirectional beam forming protocol that reduces latency introduced
by an iterative training scheme by using only HRP channels 352-1,
352-2, while reducing or eliminating the need to use the LRP
channels 354-1, 354-2. For purposes of illustration and not
limitation, the wireless device 202 may represent a piconet
controller (PNC) or coordinator, and the wireless device 204 may
represent a wireless station (STA). In one embodiment, the message
flow 600 may be applicable for WirelessHD devices, although the
embodiments are not limited in this respect.
In the illustrated embodiments shown in FIG. 6A, the wireless
device 202 exits the idle state 402 and enters the beam forming
state 404. The wireless device 202 may optionally transmit timing
acquisition and optimal delay selection sequences to the wireless
device 204. The antenna control module 208 of the wireless device
202 cooperates with the antenna control module 208a of the wireless
device 204 to implement an iterative training scheme using an
enhanced bidirectional beam forming protocol. The iterative
training scheme may use any number of iterations 602-1-m as desired
for a given implementation.
During a first iterative training 602-1, the antenna control module
208 uses the transceiver 205 and the phased antenna array 510 of
the wireless device 202 to send training signals, such as training
signals 613, from the wireless device 202 to the wireless device
204 over a downlink (DL) HRP channel 352-1. In a typical scenario,
multiple training signals are transmitted, while the wireless
device 202 changes its antenna weights at proper times (e.g., at
the beginning of every training signal). For example, the antenna
control module 208 sends receiver (Rx) training signals 613 from
the wireless device 202 to the wireless device 204 over the DL HRP
channel 352-1 to allow the wireless device 204 to deduce the MRC
weights and form a directional receive beam pattern for a phased
antenna array 210a of the wireless device 204. The antenna control
module 208 sends transmitter (Tx) training signals 614 from the
wireless device 202 to the wireless device 204 over the DL HRP
channel 352-1 to allow the device 204 to measure characteristics of
its received signal. These characteristics are later fed back from
device 204 to device 202 using message 617 to allow wireless device
202 to deduce its MRT weights so that a directional transmit beam
pattern for the phased antenna array 210 of the wireless device 202
can be formed.
In a conventional beam forming protocol, the antenna control module
208 may wait to receive feedback information from the wireless
device 204 over the LRP channel 354-1. In the enhanced
bidirectional beam forming protocols, however, the feedback
information from the wireless device 204 is delayed until a
directional receive beam pattern for the phased antenna array 210
of the wireless device 202 as been formed or partially formed,
thereby allowing the wireless device 202 to receive the feedback
information from the wireless device 204 over an uplink (UL) HRP
channel 352-2. The UL HRP channel 352-2 operates at a much higher
data rate than the LRP channel 354-1, and therefore using the UL
HRP channel 352-2 for the feedback information reduces training
overhead and latency.
Referring again to the message flow 600, the antenna control module
208a uses the transceiver 205a and the phased antenna array 210a of
the wireless device 204 to send training signals or sequences to
the wireless device 202 over the UL HRP channel 352-2. For example,
the antenna control module 208a sends training signals 615 to the
wireless device 202 over the UL HRP channel 352-2 to deduce the MRC
weights and form a directional receive beam pattern for the phased
antenna array 210 of the wireless device 202. The antenna control
module 208a also sends training signals 616 to the wireless device
202 over the UL HRP channel 352-2 to allow the wireless device 202
to measure characteristics of its received signal. These
characteristics are later fed back from device 202 to device 204
using message 618 to allow wireless device 204 to deduce its MRT
weights so that a directional transmit beam pattern for the phased
antenna array 210a of the wireless device 204 can be formed.
Once the phased antenna array 210 of the wireless device 202 has a
fully or partially formed directional receive beam pattern using
the weights (e.g., MRC weights) obtained at arrow 615, the wireless
device 204 may send feedback information to the wireless device 202
over the UL HRP channel 352-2, which is received using the
directional receive beam pattern for the phased antenna array 210
of the wireless device 202, as indicated by the arrow 617. The
phased antenna array 210a may use the same transmit beam forming
vector as used when previously sending the UL PNC Rx vector
training (PNC MRC weights) (arrow 615). This provides the wireless
device 202 with receive gain that may not have been available prior
to stage 615 or earlier.
The antenna control module 208 may determine AWVs for the
directional transmit beam pattern for the phased antenna array 210
of the wireless device 202 using the feedback information from the
wireless device 204. The first iteration 602-1 may then be
completed by having the wireless device 202 send feedback
information to the wireless device 204 over the DL HRP channel
352-1 using a directional transmit beam pattern obtained from
recently received feedback information (arrow 617) for the phased
antenna array 210 of the wireless device 202. The phased antenna
array 210a of the wireless device 204 may use the directional
receive beam pattern formed when receiving the DL STA Rx vector
training (STA MRC weights) at arrow 613 to receive the feedback
information. The antenna control module 208a may then use the
feedback information in determining AWVs for the directional
transmit beam pattern for the phased antenna array 210a of the
wireless device 204 using the feedback information from the
wireless device 202.
The wireless devices 202, 204 may continue with the next iterative
trainings 602-2-m performing similar beam forming or beam
refinement operations as used with the first iterative training
602-1. For example, for iterative training 602-2 the operations
indicated by arrows 619 through 624 are similar to those operations
performed as indicated by arrows 613 through 618. Each iterative
training 602-1-m provides successively more accurate AWVs for the
HRP channels 352-1, 352-2. This process continues until a
terminating condition is reached, such as reaching a determined SNR
for data communications, reaching a determined number of iterations
(e.g., three iterations), or until both ends of the link request
termination of the training process. At this point, the HRP
channels 352-1, 352-2 may be used for bidirectional high rate data
communications.
It is worthy to note that the feedback information provided at
arrow 617 may optionally be moved back and provided during stage
616. This may add synchronization overhead, however, because of the
transmit/receive switching.
FIG. 6B illustrates one embodiment of a message flow 650. The
message flow 650 illustrates a message flow for an enhanced
bidirectional beam forming protocol that reduces latency introduced
by an iterative training scheme by using predominantly HRP channels
352-1, 352-2, while reducing or eliminating the need to use the LRP
channels 354-1, 354-2. For purposes of illustration and not
limitation, the wireless device 202 may represent a piconet
controller (PNC) or coordinator, and the wireless device 204 may
represent a wireless station (STA). In one embodiment, the message
flow 650 may be applicable for NGmS devices, although the
embodiments are not limited in this respect.
In the illustrated embodiments shown in FIG. 6A, the message flow
650 illustrates a message flow suitable for an enhanced
bidirectional beam forming protocol implemented for a NGmS network,
protocol or devices. The NGmS protocol, for example, may contain DL
RX training, DL feedback and DL TX training, followed by UL RX
training, UL feedback and UL TX training, where the DL feedback is
feedback sent over a downlink corresponding to UL TX training that
was previously transmitted.
The message flow 650 of FIG. 6B is similar to the message flow 600
described with reference to FIG. 6A, with a different sequencing
for the training signals and messages. As shown in the message flow
650, signals and/or messages 613 to 618 are reordered in the
following sequence: 613, 618, 614, 615, 617 and 616. It may be
appreciated that this sequencing provides the following
characteristics: (1) all arrows in the same direction may be
grouped together to form a single packet; and (2) in a group there
is RX training, feedback information and then TX training. Unlike
message flow 600, where the feedback information can correspond to
current iteration training, the message flow 650 corresponds to
previous iteration training. The embodiments are not limited in
this context.
FIG. 7 illustrates one embodiment of a graph 700 for beam forming
gain. The graph 700 provides a number of iterations on a x-axis and
a combined output (dB) on a y-axis. As a result of the enhanced
bidirectional beam forming protocol, the feedback at arrow 618 is
sent with approximately 15-25 dB beam forming gain (depending on
which iteration) due to performing both transmit and receive beam
forming. For example, approximately 15 dB gain may be achieved in
the first iteration 602-1, and 5-6 dB additional gain may be
achieved in the second iteration 602-2. After the second iteration
602-2, progressively smaller gains are realized by each successive
iteration (e.g., 602-3 through 602-9). These SNR improvements
enable much faster feedback for beam forming operations without
calibration. These results correspond to 32 or 36 antenna elements
on both sides.
FIG. 8 illustrates one embodiment of a message flow 800. The
message flow 800 illustrates an alternative message flow for an
enhanced bidirectional beam forming protocol that reduces latency
introduced by an iterative training scheme by using the HRP
channels 352-1, 352-2, while reducing or limiting the need to use
the LRP channels 354-1, 354-2. For purposes of illustration and not
limitation, the wireless device 202 may represent a piconet
controller (PNC) or coordinator, and the wireless device 204 may
represent a wireless station (STA).
Similar to the message flow 600, the message flow 800 attempts to
coordinate transmit and receive beam forming operations to allow
feedback information to be provided over the HRP channels 352-1,
352-2. The wireless device 202 exits the idle state 402 and enters
the beam forming state 404. The wireless device 202 utilizes the
message flow 800 to initiate bidirectional beam formation
operations using an iterative training scheme to form a pair of
communications channels for a WPAN or WVAN. The message flow 800
interleaves transmit and receive beam forming operations to allow
use of partially trained links to communicate feedback information
at a higher data rate. More particularly, the message flow 800
interleaves transmit and receive beam forming operations for the
wireless devices 202, 204 to allow feedback information received by
the wireless device 202 from the wireless device 204 to be
communicated over the HRP channels 352-1, 352-2. This reduces the
need to use the LRP channels 354-1, 354-2 during beam forming
operations.
In the illustrated embodiment shown in FIG. 8, the message flow 800
begins with optional timing acquisition and optimal delay selection
operations. During a first iterative training 802-1, the antenna
control module 208 sends transmitter (Tx) training signals 813 from
the wireless device 202 to the wireless device 204 over the DL HRP
channel 352-1 to allow the device 204 to measure characteristics of
its received signal. The wireless device 202 receives feedback
information 814 from the wireless device 204 over the UL LRP 354-2
to deduce its MRT weights. The antenna control module 208 of the
wireless device 202 determines AWVs for the directional transmit
beam pattern for the phased antenna array 210 of the wireless
device 202 using the feedback information 814 from the wireless
device 204.
The wireless device 202 then sends Rx training signals (STA MRC
weights) to the wireless device 204 over the DL HRP 352-1 to allow
the wireless device 204 to deduce and form a directional receive
beam pattern for the phased antenna array 210a of the wireless
device 204, as indicated by arrow 815. The wireless device 202
receives Tx training signals (STA MRT weights) from the wireless
device 204 over the UL HRP 352-2 to form a directional transmit
beam pattern for the phased antenna array 210a of the wireless
device 204, as indicated by arrow 816.
The antenna control module 208 uses the transceiver 205 and the
phased antenna array 510 of the wireless device 202 to send
training signals 815 from the wireless device 202 to the wireless
device 204 over a downlink DL HRP channel 352-1 to allow the
wireless device 204 to deduce the MRC weights and form a
directional receive beam pattern for a phased antenna array 210a of
the wireless device 204. The antenna control module 208a also sends
training signals 816 to the wireless device 202 over the UL HRP
channel 352-2 to allow the wireless device 202 to measure
characteristics of its received signal.
The wireless device 202 sends feedback information 817 to the
wireless device 204 over the DL HRP 352-1 using a directional
transmit beam pattern for the phased antenna array 210 of the
wireless device 202. The feedback information 817 is carried using
a partially trained link obtained in the recent half-iteration. As
a result, the feedback information 817 is much more robust and
efficient than using only the DL LRP channel 354-1. The wireless
device 204 uses the feedback information to determine AWVs for the
directional transmit beam pattern for the phased antenna array 210a
of the wireless device 204 using the feedback information 817 from
the wireless device 202.
To complete the first iterative training 802-1, the wireless device
202 receives training signals 818 by the wireless device 202 from
the wireless device 204 over the UL HRP 352-2 to deduce MRC weights
and form a directional receive beam pattern for the phased antenna
array 210 of the wireless device 202.
The wireless devices 202, 204 may continue with the next iterative
trainings 802-2-k performing similar beam forming or beam
refinement operations as used with the first iterative training
802-1. For example, the wireless device 202 may receive additional
feedback information from the wireless device 204 over the UL HRP
352-2 using the directional receive beam pattern for the phased
antenna array 210 of the wireless device 202 during the second
iterative training 802-2. The antenna control module 210 may
determine AWVs for the directional transmit beam pattern for the
phased antenna array 210 of the wireless device 202 using the
additional feedback information from the wireless device 204. Each
iterative training 802-1-k provides successively more accurate AWVs
for the HRP channels 352-1, 352-2. This process continues until a
terminating condition is reached, such as reaching a determined SNR
for data communications or reaching a determined number of
iterations (e.g., three iterations). At this point, the HRP
channels 352-1, 352-2 may be used for bidirectional high rate data
communications.
The enhanced bidirectional beam forming protocol utilizes partially
trained links to provide a higher data rate for the feedback
information during the feedback stages. In the WirelessHD
Specification, by way of contrast, feedback stages after the first
one are done using "directional" mode, which is a selected antenna
pattern. With non-calibrated antennas, a random antenna pattern may
yield less than 0 dBi in certain directions. The directional mode
is expected to be around 0 dBi as it is the best among few random
choices. An additional advantage of the enhanced bidirectional beam
forming protocol is that the beamformer need not transfer the
selected antenna pattern for the directional mode to the
beamformee, since the next time feedback is already going to be
over a beamformed link, which is properly trained.
FIG. 9 illustrates one embodiment of a phased array antenna 900.
The phased array antenna 900 may be representative of, for example,
the phased array antennas 210, 210a. In the illustrated embodiment
shown in FIG. 9, the phased array antenna 900 may comprise multiple
antenna elements 902-1-p.
In some embodiments, the enhanced bidirectional beam forming
protocol may train a subset of antenna elements 902-1-p from the
phased array antenna 900. The first few iterations of beam forming
operations may be of reduced time and quality. When the phased
antenna array 900 is implemented by the wireless device 202, and
has 36 antenna elements 902-1 through 902-36, then the antenna
control module 208 can couple some of the antenna elements 902-1
through 902-36 together and generate training for fewer overall
antenna elements 902-1 through 902-36. This shortens the time of
the training in the first iterative trainings and may still capture
some of the expected antenna gain. An example for such coupling is
depicted in FIG. 9, where four (4) antenna elements 902-5, 902-10,
902-12 and 902-17 marked in cross-hatchings, for example, are
always phase shifted by the same amount, such as 90 degrees, 180
degrees or 270 degrees. This results in essentially eight (8) to
nine (9) antenna elements made from the 6.times.6 phased antenna
array 900.
By way of example, referring again to the exemplary message flows
600, 800, the wireless device 202 may send Tx training signals to
the wireless device 204 over the DL HRP 352-1 to form a directional
transmit beam pattern for a subset of antenna elements 902-1-p of
the phased antenna array 210 of the wireless device 202.
Additionally or alternatively, the wireless devices 202, 204 may
exchange additional information during the enhanced bidirectional
beam forming protocol that may accelerate beam forming operations.
For example, similar to the way that the WirelessHD Specification
uses to identify the proper antenna pattern index for the
directional mode, the enhanced bidirectional beam forming protocol
can add additional information types to certain stages of beam
forming operations, such a needed modulation and coding scheme
(MCS) for the wireless devices 202, 204. An information field of
defined length (e.g., 3 bits) may be used to communicate the MCS
information. The MCS information may be communicated, for example,
with the transmitter training signals in either link direction in
order to assist in generating the feedback information during the
feedback stages. Other types of information other than MCS
information may be sent during different stages of the enhanced
bidirectional beam forming protocol, and the embodiments are not
limited in this context.
In embodiments, the feedback information may correspond to
measurements done at the receiver and is largely unaware of the
antenna patterns applied by the transmitter. An example of feedback
information may comprise a channel estimation per given delay,
among others. In some embodiments, the amount of feedback
information may be uniform. Additionally or alternatively, the
wireless devices 202, 204 may exchange increasing amounts of
feedback information during the feedback stages of the enhanced
bidirectional beam forming protocol to accelerate beam forming
operations. When the HRP channels 352-1, 352-2 are partially or
fully formed, and the feedback overhead becomes cheaper, then one
or both of the wireless devices 202, 204 can increase the amount of
feedback information provided over the HRP channels 352-1, 352-2 at
certain stages and/or iterative trainings so that the overall beam
forming training time is reduced.
Operations for various embodiments may be further described with
reference to the following figures and accompanying examples. Some
of the figures may include a logic flow. It can be appreciated that
an illustrated logic flow merely provides one example of how the
described functionality may be implemented. Further, a given logic
flow does not necessarily have to be executed in the order
presented unless otherwise indicated. In addition, a logic flow may
be implemented by a hardware element, a software element executed
by a processor, or any combination thereof. The embodiments are not
limited in this context.
FIG. 10 illustrates one embodiment of a logic flow 1000 for
selecting a channel pair to form a new wireless network between two
or more devices. In various embodiments, the logic flow 1000 may be
performed by various systems, nodes, and/or modules and may be
implemented as hardware, software, and/or any combination thereof,
as desired for a given set of design parameters or performance
constraints. For example, the logic flow 1000 may be implemented by
a logic device (e.g., transmitter node, receiver node) and/or logic
comprising instructions, data, and/or code to be executed by a
logic device. For purposes of illustration, and not limitation, the
logic flow 1000 is described with reference to FIG. 1. The
embodiments are not limited in this context.
In one embodiment, for example, the logic flow 1000 may initiate
beam formation operations using an iterative training scheme to
form a pair of communications channels for a wireless network at
block 1002. For example, the wireless device 202 may initiate beam
formation operations using an iterative training scheme to form a
pair of communications channels (352-1, 352-2) for a 60 GHz mmWave
WPAN or WVAN. The embodiments are not limited in this context.
In one embodiment, for example, the logic flow 1000 may communicate
training signals and feedback information between a first device
and a second device using only high rate channel at block 1004. For
example, may communicate training signals and feedback information
between the wireless devices 202, 204 using only HRP channels
352-1, 352-2. The embodiments are not limited in this context.
In one embodiment, for example, the logic flow 1000 may determine
antenna-array weight vectors for a directional transmit beam
pattern for a phased antenna array of the first device using
feedback information from the second device at block 1006. For
example, the antenna control module 208 of the wireless device 202
may determine AWVs for a directional transmit beam pattern for the
phased antenna array 210 of the wireless device 202 using feedback
information from the wireless device 204. The embodiments are not
limited in this context.
FIG. 11 illustrates one embodiment of an article of manufacture
1100. As shown, the article 1100 may comprise a storage medium 1102
to store logic 1104 for selecting a channel pair to form a new
wireless network between two or more devices. For example, logic
1104 may be used to implement the channel selection module 208, as
well as other aspects of the transmitter node (102, 202) and/or the
receiver nodes (104-1-n, 204). In various embodiments, the article
1100 may be implemented by various systems, nodes, and/or
modules.
The article 1100 and/or machine-readable storage medium 1102 may
include one or more types of computer-readable storage media
capable of storing data, including volatile memory or, non-volatile
memory, removable or non-removable memory, erasable or non-erasable
memory, writeable or re-writeable memory, and so forth. Examples of
a machine-readable storage medium may include, without limitation,
random-access memory (RAM), dynamic RAM (DRAM), Double-Data-Rate
DRAM (DDR-DRAM), synchronous DRAM (SDRAM), static RAM (SRAM),
read-only memory (ROM), programmable ROM (PROM), erasable
programmable ROM (EPROM), electrically erasable programmable ROM
(EEPROM), Compact Disk ROM (CD-ROM), Compact Disk Recordable
(CD-R), Compact Disk Rewriteable (CD-RW), flash memory (e.g., NOR
or NAND flash memory), content addressable memory (CAM), polymer
memory (e.g., ferroelectric polymer memory), phase-change memory
(e.g., ovonic memory), ferroelectric memory,
silicon-oxide-nitride-oxide-silicon (SONOS) memory, disk (e.g.,
floppy disk, hard drive, optical disk, magnetic disk,
magneto-optical disk), or card (e.g., magnetic card, optical card),
tape, cassette, or any other type of computer-readable storage
media suitable for storing information. Moreover, any media
involved with downloading or transferring a computer program from a
remote computer to a requesting computer carried by data signals
embodied in a carrier wave or other propagation medium through a
communication link (e.g., a modem, radio or network connection) is
considered computer-readable storage media.
The article 1100 and/or machine-readable medium 1102 may store
logic 1104 comprising instructions, data, and/or code that, if
executed by a machine, may cause the machine to perform a method
and/or operations in accordance with the described embodiments.
Such a machine may include, for example, any suitable processing
platform, computing platform, computing device, processing device,
computing system, processing system, computer, processor, or the
like, and may be implemented using any suitable combination of
hardware and/or software.
The logic 1104 may comprise, or be implemented as, software, a
software module, an application, a program, a subroutine,
instructions, an instruction set, computing code, words, values,
symbols or combination thereof. The instructions may include any
suitable type of code, such as source code, compiled code,
interpreted code, executable code, static code, dynamic code, and
the like. The instructions may be implemented according to a
predefined computer language, manner or syntax, for instructing a
processor to perform a certain function. The instructions may be
implemented using any suitable high-level, low-level,
object-oriented, visual, compiled and/or interpreted programming
language, such as C, C++, Java, BASIC, Perl, Matlab, Pascal, Visual
BASIC, assembly language, machine code, and so forth. The
embodiments are not limited in this context. When implemented the
logic 1104 is implemented as software, the software may be executed
by any suitable processor and memory unit.
It is worthy to note that although the terms "downlink" and
"uplink" channels are used when describing some embodiments, these
terms are used to differentiate between two different channels
being used between two different devices. Alternate terms may
include a "first" channel and a "second" channel, a "forward"
channel and a "reverse" channel, and any other suitable labels. Any
two channels between any two devices may be used with an enhanced
bidirectional beam forming protocol as described herein, and still
fall within the scope of the embodiments. The embodiments are not
limited in this context.
It is also worthy to note that the increased gain provided by an
enhanced bidirectional beam forming protocol may be realized at any
point during iterative training operations due to variations in the
iterative training operations for different types of protocols
(e.g., WirelessHD, NGmS, and so forth), and flexibility in
modifying a particular implementation for interleaving operations
in support of bidirectional beamforming operations. For example,
the increased gain from communicating feedback information as
described with reference FIG. 6B may be realized during the first
iteration or second iteration depending on a particular
implementation. The embodiments are not limited in this
context.
Numerous specific details have been set forth herein to provide a
thorough understanding of the embodiments. It will be understood by
those skilled in the art, however, that the embodiments may be
practiced without these specific details. In other instances,
well-known operations, components and circuits have not been
described in detail so as not to obscure the embodiments. It can be
appreciated that the specific structural and functional details
disclosed herein may be representative and do not necessarily limit
the scope of the embodiments.
Unless specifically stated otherwise, it may be appreciated that
terms such as "processing," "computing," "calculating,"
"determining," or the like, refer to the action and/or processes of
a computer or computing system, or similar electronic computing
device, that manipulates and/or transforms data represented as
physical quantities (e.g., electronic) within the computing
system's registers and/or memories into other data similarly
represented as physical quantities within the computing system's
memories, registers or other such information storage, transmission
or display devices. The embodiments are not limited in this
context.
It is also worthy to note that any reference to "one embodiment" or
"an embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment. Thus, appearances of the
phrases "in one embodiment" or "in an embodiment" in various places
throughout the specification are not necessarily all referring to
the same embodiment. Furthermore, the particular features,
structures or characteristics may be combined in any suitable
manner in one or more embodiments.
While certain features of the embodiments have been illustrated as
described herein, many modifications, substitutions, changes and
equivalents will now occur to those skilled in the art. It is
therefore to be understood that the appended claims are intended to
cover all such modifications and changes as fall within the true
spirit of the embodiments.
* * * * *