c12) United States Patent - Rice Scholarship Home

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US009820336B2
c12)
United States Patent
(IO)
Flores Miranda et al.
(45)
(58)
(54)
DUAL CHANNEL WI-FI FOR CONGESTED
WLANS WITH ASYMMETRIC TRAFFIC
LOADS
(71)
Applicant: William Marsh Rice University,
Houston, TX (US)
(72)
Inventors: Adriana B. Flores Miranda, Houston,
TX (US); Edward W. Knightly,
Houston, TX (US)
(73)
( *)
Appl. No.: 14/509,723
(22)
Filed:
(65)
Prior Publication Data
Apr. 9, 2015
Related U.S. Application Data
(60)
Provisional application No. 61/888,285, filed on Oct.
8, 2013.
(51)
Int. Cl.
H04W 88/08
(2009.01)
(2009.01)
H04W 74108
U.S. Cl.
CPC ....... H04W 88/08 (2013.01); H04W 7410866
(2013.01)
(52)
U.S. PATENT DOCUMENTS
2010/0281338 Al* 11/2010 Liu ....................... H04L 1/0022
375/340
1/2011 Keller ................... H04L 5/0042
2011/0019725 Al*
375/222
Primary Examiner - Jeffrey R Swearingen
(74) Attorney, Agent, or Firm - Osha Liang LLP
(57)
Oct. 8, 2014
US 2015/0100619 Al
References Cited
* cited by examiner
Subject to any disclaimer, the term ofthis
patent is extended or adjusted under 35
U.S.C. 154(b) by 223 days.
(21)
Field of Classification Search
None
See application file for complete search history.
(56)
Assignee: William Marsh Rice University,
Houston, TX (US)
Notice:
Patent No.:
US 9,820,336 B2
Date of Patent:
Nov. 14, 2017
ABSTRACT
A method of wireless local area network communication
between a client and an access point includes sending, by the
client, a client-originated message to the access point over a
bidirectional upload channel; receiving, by the client, a
client-acknowledgement message from the access point over
the bidirectional upload channel; receiving, by the client, an
access point-originated message from the access point over
a bidirectional download channel that was generated in
response to the client-originated message; and sending, by
the client, an access point-acknowledgement message to the
access point over the bidirectional download channel. The
bidirectional download channel is separate from the bidirectional upload channel.
2 Claims, 10 Drawing Sheets
430
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443
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i-=
441
442
440
U.S. Patent
Nov. 14, 2017
Sheet 1 of 10
US 9,820,336 B2
100
~
Access Point
110
130 - - - - - - - - -
1'
,-----------------------------,
I
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Client A
I
120A
I '-----~
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•
•
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FIG. 1
Client B
120B
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U.S. Patent
Nov. 14, 2017
US 9,820,336 B2
Sheet 2 of 10
110
~
Control Software
210
Network Stack (L3, L4)
220
Controller
230
231
232
.................................. .. ......................... !
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260
265
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FIG. 2
U.S. Patent
Nov. 14, 2017
Sheet 3 of 10
US 9,820,336 B2
Client Applications
300
315
~
Operating System
310
~................................~ ~ ..................................
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FIG. 3
U.S. Patent
US 9,820,336 B2
Sheet 4 of 10
Nov. 14, 2017
430
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442
441
465
460
450
_..,._ Frequency
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#1 at 2.412 GHz
#2 at 2.417 GHz
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#4 at 2.417 GHz
#5 at 2.432 GHz
#6 at 2.437 GHz
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#7 at 2.442 GHz
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#11 at 2.462 GHz
#12 at 2.467 GHz
#13 at 2.472 GHz
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U.S. Patent
Nov. 14, 2017
Sheet 6 of 10
US 9,820,336 B2
Access
Point
Client
120
110
STEP 1000 Data Request (ULC)
-
STEP 1010 Ack (ULC)
-
STEP 1020 Reauested Data (DLC}
....
.,
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STEP 1030 Ack (DLC)
....
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FIG. 5A
Access
Point
Client
120
-
110
STEP 2000 Data Request (DLC)
"'
STEP 2010 Ack (DLC)
STEP 2020 Requested Data (ULC)
-
STEP 2030 Ack (ULC)
"'
FIG. 5B
.-,
.,
U.S. Patent
Nov. 14, 2017
Sheet 7 of 10
Access
Point
110
US 9,820,336 B2
Clients
(120)
I
Determine
Load Ratio
STEP 3000
STEP 3010 Channel Update (DLC)
...
Update
Channel
Bandwidth
STEP 3020
FIG. 5C
U.S. Patent
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Nov. 14, 2017
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US 9,820,336 B2
Sheet 8 of 10
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Load Asymmetry (DL/UL)
FIG. 6
7
U.S. Patent
Nov. 14, 2017
US 9,820,336 B2
Sheet 9 of 10
:::;· L4 .. · ·" · · · · · · · ...... · , ,, .. .. ...... •· .. · ................. ,, , ·" .. · ................... ..
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0
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20
40
so
80
Total Number of Clients
FIG. 7
100
U.S. Patent
Nov. 14, 2017
US 9,820,336 B2
Sheet 10 of 10
2 APs: Dual Wi-Fi Throughput Gains over 802.1 i {Load Asymmetry: 1)
700 .... ···-············· ... , ' ........... ,,,............... .
,~~~~~~~~~~~~~~l~ll Aggregate Traffic (2 APs)
Uplink Traffic (2 APs)
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FIG. 8
100
US 9,820,336 B2
1
2
DUAL CHANNEL WI-FI FOR CONGESTED
WLANS WITH ASYMMETRIC TRAFFIC
LOADS
layer and a download physical layer, a download transceiver,
and a download antenna, wherein the download chain. The
download chain may send an access point-originated message over a bidirectional download channel and receive a
client-acknowledgement message on the bidirectional
download channel. The access point may include an upload
chain that may include an upload media access control layer
and an upload physical layer, an upload transceiver, and an
upload antenna. The upload chain may receive a clientoriginated over a bidirectional upload channel and send an
access point-acknowledgement message on the bidirectional
upload channel. The access point may include a controller
that forwards the download data to the download chain and
forwards the upload acknowledgement to the upload chain.
Other aspects of the disclosure will be apparent from the
following description and the appended claims.
CROSS-REFERENCE TO RELATED
APPLICATIONS
This application claims priority under 35 U.S.C. §119(e)
to U.S. Provisional Patent Application Ser. No. 61/888,285
filed on Oct. 8, 2013. U.S. Provisional Patent Application
Ser. No. 61/888,285 is hereby incorporated by reference in
to the instant application.
STATEMENT REGARDING FEDERALLY
SPONSORED RESEARCH OR DEVELOPMENT
The invention was made with government support under
Grant Number CNS-1126478 awarded by the National Science Foundation. The invention was made with government
support under Grant Number CNS-1012831 awarded by the
National Science Foundation. The government has certain
rights in the invention.
5
IO
15
BRIEF DESCRIPTION OF DRAWINGS
20
BACKGROUND
25
Wireless local area networks (WLANs) are methods of
communicating between nodes in a network within a limited
area via a wireless link. Network nodes may include clients
such as mobile telephone devices or laptop computers and
access points such as routers or gateways. In some cases,
access points provide access to an additional network such
as the internet or a private network to the clients.
The wireless link allows clients to communicate with the
additional network, via the access point, without being
physically connected to the access point via a communication cable. However, a wireless link is an inherently limited
communication medium. All nodes communicating via the
wireless link may interfere with one another.
SUMMARY
In one aspect, a method of wireless local area network
communication between a client and an access point may
include sending, by the client, a client-originated message to
the access point over a bidirectional upload channel; receiving, by the client, an client-acknowledgement message from
the access point over the bidirectional upload channel;
receiving, by the client, an access point-originated message
from the access point over a bidirectional download channel
that was generated in response to the client-originated
message; and sending, by the client, an access point-acknowledgement message to the access point over the bidirectional download channel.
In one aspect, a method of wireless local area network
communication between a client and an access point may
include receiving, by the access point, a client-originated
message over a bidirectional upload channel; sending, by the
access point, an access point-acknowledgement message to
the client over the bidirectional upload channel; sending, by
the access point, an access point-originated message to the
client over a bidirectional download channel that was generated in response to the client-originated message; and
receiving, by the access point, a client-acknowledgement
message from the client over the bidirectional download
channel.
In one aspect, an access point may include a download
chain that may include a download media access control
30
35
40
45
50
55
60
65
Certain embodiments of the disclosure will hereafter be
described with reference to the accompanying drawings. It
should be understood, however, that the accompanying
drawings illustrate the various implementations described
herein and are not meant to limit the scope of various
technologies described herein. The drawings show and
describe various embodiments of the current disclosure.
FIG. 1 shows a wireless network in accordance with one
or more embodiments of the invention.
FIG. 2 shows an access point in accordance with one or
more embodiments of the invention
FIG. 3 shows a client in accordance with one or more
embodiments of the invention.
FIG. 4A shows a spectrum allocation diagram in accordance with one or more embodiments of the invention.
FIG. 4B shows a diagram of the channels defined by the
IEEE 802.11 communication protocol for the 2.4 GHz band.
FIGS. SA-SC show flow diagrams in accordance with one
or more embodiments of the invention.
FIG. 6 shows a measured throughput ratio to load ratio of
a wireless network in accordance with one or more embodiments of the invention.
FIG. 7 shows a measured throughput ratio to load ratio of
a wireless network in accordance with one or more embodiments of the invention.
FIG. 8 shows a gain of a wireless network over an existing
wireless network in accordance with one or more embodiments of the invention.
DETAILED DESCRIPTION
Specific embodiments will now be described with reference to the accompanying figures. In the following description, numerous details are set forth as examples. It will be
understood by those skilled in the art that one or more
embodiments of the present invention may be practiced
without these specific details and that numerous variations
or modifications may be possible without departing from the
scope. Certain details known to those of ordinary skill in the
art are omitted to avoid obscuring the description.
In general, embodiments of the invention relate to a
wireless channel architecture that includes a mechanism to
allocate spectrum resources for wireless transmissions. One
or more embodiments of the invention allocate spectrum
resources based on the direction of the data transmissions,
which allows the configuration of spectrum resources to
match performance to the system's traffic asymmetry.
US 9,820,336 B2
3
4
FIG. lA shows a wireless channel architecture (100) in
accordance with one or more embodiments of the invention.
The wireless channel architecture (100) includes an access
point (AP) (110) and a number of clients (120A, 120B)
connected by a wireless link (130). The AP (110) may be
connected to an additional network (not shown) via a wired
or wireless link. In one or more embodiments of the invention, the additional network is the Internet or a private
network.
In one embodiment of the invention, the client (120A,
120B) may correspond to any communication device that
includes functionality to implement embodiments of the
invention (see e.g., FIGS. 3, SA-5B). Examples of communication devices may include, but are not limited to, a phone,
smart phone, a laptop, a wireless access point, a wireless
router, a gaming console, a set top box, a television, a tablet
computer, and a desktop computer.
When the AP (110) is connected to the additional network,
the clients (120) communicate with the additional network
through the AP (110) via the wireless link (130). The
wireless link (130) is discussed below. In one or more
embodiments of the invention, the AP (110) acts as a link
controller that regulates communications through the wireless link (130). For example, the AP (110) may send update
messages to the clients (120) that instruct the clients (120)
to use a specific protocol, method of data encoding, channel
assignment, message format, etc.
The wireless link (130) includes two logical channels: a
bidirectional upload channel and a bidirectional download
channel. Messages between the AP (110) and clients (120)
are sent via the bidirectional upload channel or bidirectional
download channel, based on the message type and message
sender. Messages are classified as either originated messages
or acknowledgement messages. Originated messages are
new messages and acknowledgement messages are
acknowledgements of received originated messages. Each
originated message sent over the wireless link (130) is
acknowledged. Originated messages from the AP (110) are
sent over the bidirectional download channel and originated
messages from the clients (120A, 120B) are sent over the
bidirectional upload channel. When a message is received by
the AP (110) on the bidirectional upload channel, the AP
(110) sends an acknowledgement message over the bidirectional upload channel acknowledging receipt of the received
message. When a message is received by one of the clients
(120) on the bidirectional download channel, the client
sends an acknowledgement message over the bidirectional
download channel acknowledging receipt of the received
message.
The bidirectional upload channel and bidirectional download channel are asynchronous. Messages, either originated
or acknowledgement, may be sent over each channel at any
time. Each channel may only be utilized by an individual
entity (e.g., a client or the access point) at a time. In one
embodiment of the invention, each client (120) or the access
point (110) that wishes to send an originated message (not an
acknowledgement message) over the channel contends for
the channel as defined by the IEEE 802.11 communication
protocol. In one or more embodiments of the invention,
contention for each channel is reduced by separating the
types of messages sent over each channel. For example, in
one or more embodiments of the invention, in a system of
one access point and a number of clients, the contention for
the download channel is eliminated because only the access
point may send originated messages on the download channel.
FIG. 2 shows a diagram of an AP (110) in accordance with
one or more embodiments of the invention. The AP (110)
includes the necessary hardware, software and/or firmware
to support two bidirectional communication channels. The
AP (110) may include control software (210), such as an
operating system, which governs the overall operation of the
AP (110).
The AP (110) may also include a network stack (220) that
manages network connections and communication flow in
order to support the Internet Protocol (IP) (or other layer 3
protocols) and the transmission control protocol (TCP) (or
other layer 4 protocols).
Further, the AP (110) includes a download chain (231) and
an upload chain (232). In one embodiment of the invention,
the download chain (231) includes hardware, firmware,
and/or software, components to support the bidirectional
download channel, and the upload chain (232) includes
similar components to support the bidirectional upload channel. The download chain (231) includes a download media
access control (MAC) layer and a download physical layer
(240), a download transceiver (250), and a download
antenna (260). The upload chain (232) includes an upload
MAC layer and a download physical layer (245), an upload
transceiver (255), and an upload antenna (265). The hardware and software components allow data to be sent over the
channels. The DL MAC layer and DL Phys Layer (240)
provide layer 2 and layer 1 functionality for the bidirectional
download channel. Further, the UL MAC layer and UL Phys
Layer (245) provide layer 2 and layer 1 functionality for the
bidirectional upload channel.
The AP (110) further includes a controller (230) that
controls communications over the wireless link (130). The
controller (230) manages communications over the bidirectional upload channel and bidirectional download channel.
More specifically, the controller (230) determines whether a
given message or acknowledgement is to be sent via the
bidirectional download channel or the bidirectional upload
channel (see FIGS. SA-5, below).
The controller (230) may also manage the operation of the
download transceiver (250) and upload transceiver (255).
For example, the controller may set the band of operation of
each transceiver according to the download bandwidth (441)
and the upload bandwidth (442).
In one embodiment of the invention, the controller may be
implemented in hardware, software, or a combination of
hardware and software. Further, the controller may be conceptually part of the layer 2 processing that is performed by
the AP. In on embodiment of the invention, the network
stack (220) is not aware of the modified layer 2 processing
that is occurring in the AP. Said another way, embodiments
of the invention are implemented such that the network stack
(220) is not aware that messages and acknowledgements are
processed as shown in FIGS. SA and 5B.
Those skilled in the art will appreciate that while FIG. 3
shows a client that includes only a single transceiver and a
single antenna, embodiments of the invention may be implemented with client that include a two-antenna design that is
equivalent to the two-antenna design that is shown in FIG.
2 or the AP.
FIG. 3 shows a diagram of a client (120A, 120B) in
accordance with one or more embodiments of the invention.
The client (120A, 120B) includes the necessary hardware,
software and/or firmware to support two bidirectional communication channels. The client (120) may also include one
or more client applications (300), such as an Internet
browser, and an operating system (310) that governs the
overall operation of the client (120).
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25
30
35
40
45
50
55
60
65
US 9,820,336 B2
5
6
The client (120A, 120B) also includes a network stack
(320) that manages network connections and communication flow in order to support the Internet Protocol (IP) (or
other layer 3 protocols) and the transmission control protocol (TCP) (or other layer 4 protocols).
The client includes a messaging chain (315). The messaging chain (315) includes hardware, software, and/or
firmware components to support the bidirectional download
channel and the bidirectional upload channel. The messaging chain (315) includes a MAC layer and a physical layer
(330), a transceiver (350), and an antenna (360). The MAC
layer and Phys Layer (330) provide layer 2 and layer 1
functionality for the bidirectional channel, which may operate, at any given time, as either an upload channel or a
download channel.
The messaging chain (315) may also include a controller
(340) that adjusts the operational band of the transceiver
(350). The controller (340) sets the operational band depending on the type of message being sent. If the message is an
originated message, the message is sent over the bidirectional upload channel and the operational band is set to the
upload bandwidth (442). If the message is an acknowledgement message, the message is sent over the bidirectional
download channel and the operational band is set to the
download bandwidth (441). Further, the controller may be
conceptually part of the layer 2 processing that is performed
by the client.
As discussed above, embodiments of the invention allocate different channels for upload traffic (i.e., data (excluding acknowledgements) sent from a client to an AP) and
download traffic (i.e., data (excluding acknowledgements)
sent from an AP to a client). The following section describes
how different channels may be allocated within the wireless
link.
FIG. 4A shows a physical channel allocation diagram of
the wireless link (130) in accordance with one or more
embodiments. The physical channel allocation diagram
shows the spectral implementation of the two logical channels. The wireless link (130) includes a total communication
bandwidth (440) that is the total bandwidth utilized by the
wireless link (130). In one or more embodiments, the total
communication bandwidth (440) may be a single channel
defined by the IEEE 802.11 communication protocol. In
such cases, bandwidth may be allocated to each individual
channel (441,442) by associating a specific frequency range
(i.e., a sub-channel) within a single channel to each of the
download channel and the upload channel, where the frequency ranges are non-contiguous. In one or more embodiments of the invention, a guard band (443) provides isolation
between the bidirectional download channel and bidirectional upload channel.
Alternatively, referring to FIG. 4B, the download channel
bandwidth and the upload channel bandwidth may be determined by allocating one or more discrete channels to each of
the bidirectional upload channel or the bidirectional download channel. For example, FIG. 4B shows a diagram of the
channels defined by the IEEE 802.11 communication protocol. Each channel includes a 22 MHz bandwidth that
potentially overlaps neighboring channels. There are a total
of 14 channels and the center frequency of each of the first
13 channels is separated by 5 MHz from neighboring
channels. In one or more embodiments, the total communication bandwidth (140) may be multiple channels defined by
the IEEE 802.11 communication protocol. In one or more
embodiments of the invention, the total bandwidth may be
a continuous bandwidth, such as channels 1-4 as defined by
the IEEE 802.11 communication protocol, or a number of
discontinuous bands, such as channels 1, 8 and 13 as defined
by the IEEE 802.11 communication protocol. Further, each
of the upload channel and the download channel may be
associated with one or more of the aforementioned channel
(e.g., the upload channel is associated with channel #1 at
2.412 GHz and channel #6 at 2.437 GHz, while the download channel is associated with channel #11 sat 2.462 GHz
and channel #14 at 2.484 GHz). In one or more embodiments of the invention, the total communication bandwidth
(140) may be multiple discrete channels at a number of
frequencies such as the whitespaces between existing television broadcasting frequencies or any other communication
bands known to one of ordinary skill in the art, e.g., 5 GHz,
60 GHz, etc.
Returning to FIG. 4A, AP-originated messages (450) are
sent over the bidirectional download channel utilizing the
download channel bandwidth (441). AP-acknowledgement
messages (460) sent by clients (120A, 120B) in response to
AP-originated messages (450) are sent over the bidirectional
download utilizing the download channel bandwidth (441).
Client-originated messages (455) are sent over the bidirectional upload utilizing the upload channel bandwidth (442).
Client-acknowledgement messages (465) sent by the access
point (110) in response to client-originated messages (455)
are sent over the bidirectional upload utilizing the upload
channel bandwidth (442).
In one embodiment of the invention, the upload channel
bandwidth (442) and download channel bandwidth (441) are
set by the AP (110). The AP (110) may continuous monitors
the wireless link load ratio which is the download load, e.g.
the average quantity of data being sent from the AP (110) to
the clients (120A, 120B), to the upload load, e.g. the
quantity of data being sent from the clients (120A, 120B) to
the AP (110). Further, the AP (110) may continuously
compare the wireless link load ratio to the ratio of the
download channel bandwidth (442) to the upload channel
bandwidth (441). If the values of these ratios are different,
the AP (110) may update the download channel bandwidth
(442) and the upload channel bandwidth (441) to match (or
more closely approximate) the wireless link load ratio.
FIG. SA shows a method according to one or more
embodiments of the invention. The method depicted in FIG.
SA may be used to transfer data from an additional network
to a client (120) over a wireless link in accordance with one
or more embodiments of the invention. One or more steps
shown in FIG. SA may be omitted, repeated, and/or performed in a different order among different embodiments of
the invention. Each step of FIG. SA is designated as (ULC)
if the signal is send over the bidirectional upload channel or
(DLC) if sent over the bidirectional download channel.
At STEP 1000, a client sends a client-originated message
to an access point. The client-originated message may, for
example, request data contained on the additional network.
For example, the client may request a web page, audio file,
or video file located on a remote server connected to the
Internet. The client-originated message is sent via the bidirectional upload channel utilizing the upload bandwidth. In
one embodiment of the invention, sending a client-originated message includes: (i) receiving the client-originated
message (in the form of one or more IP packets) by the MAC
layer (330), (ii) determining (e.g., by the controller (340))
that the received message is a client-originated message, (iii)
setting, by the controller (340), the operational band on the
transceiver (350) to the upload channel, (iv) encapsulating
the received IP packets by the MAC layer (330) to generate
one or more MAC frames, (v) sending the MAC frames to
the Physical layer (330), where the physical layer (330)
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subsequently provides the MAC frames(s) to the transceiver
in order for the transceiver (350) to transmit the MAC
frames to the AP via the wireless link (130).
At STEP 1010, the AP sends, in response to receiving the
client-originated message, a client-acknowledgement message. The client-acknowledgement message includes an
acknowledgement that the client-originated message was
received. The client-acknowledgement message is sent via
the bidirectional upload channel utilizing the upload bandwidth. The AP subsequently communicates with the additional network to acquire the requested data. In one embodiment of the invention, the AP receives the client-originated
message, e.g., in the form of one or more MAC frames, on
the transceiver (255) that is part of the upload chain (232).
Further, the AP sends the client-acknowledgement to the
client via the upload chain (232) and the wireless link (130).
In one embodiment of the invention, the client-acknowledgment is generated by the UL MAC layer (245). Further, after
the client receives the client-acknowledgment, the controller
(340) may switch the operational band of the transceiver to
the download channel.
At STEP 1020, the AP sends an AP-originated message to
the client. The AP-originated message includes the
requested data or information related to the requested data.
The AP-originated message is sent via the bidirectional
download channel utilizing the download bandwidth. In one
embodiment of the invention, sending a client-originated
message includes: (i) receiving the client-originated message (in the form of one or more IP packets) by the controller
(230), (ii) determining (e.g., by the controller (230)) that the
received message is an AP-originated message, (iii) forwarding the IP packets, by the controller (230), to the
download chain (231), (iv) encapsulating the received IP
packets by the MAC layer (240) to generate one or more
MAC frames, (v) sending the MAC frames to the Physical
layer (240), where the physical layer (240) subsequently
provides the MAC frames(s) to the transceiver in order for
the transceiver (250) to transmit the MAC frames to the
client via the wireless link.
At STEP 1030, the client sends, in response to receiving
the AP-originated message, an AP-acknowledgement message. The AP-acknowledgement message includes an
acknowledgement that the AP-originated message was
received. The AP-acknowledgement message is sent via the
bidirectional download channel utilizing the download
bandwidth. In one embodiment of the invention, the client
receives the AP-originated message, e.g., in the form of one
or more MAC frames, on the transceiver (350). Further, the
client sends the AP-acknowledgement to the AP via the
download channel and the wireless link (130). In one
embodiment of the invention, the AP-acknowledgment is
generated by the MAC layer (330).
FIG. 5B shows a signaling diagram of a method according
to one or more embodiments of the invention. The method
depicted in FIG. 5B may be used to transfer data from a
client (120) to an additional network over a wireless link in
accordance with one or more embodiments of the invention.
One or more steps shown in FIG. 5B may be omitted,
repeated, and/or performed in a different order among different embodiments of the invention. Each step of FIG. 5B
is designated as (ULC) if the signal is send over the
bidirectional upload channel or (DLC) if sent over the
bidirectional download channel.
At STEP 2000, the AP sends an AP-originated message to
a client. The AP-originated message includes a request for
data on the client. For example, an additional network may
request a photo that is located on the client. The AP-
originated message is sent to the client using the download
chain (231) utilizing the download bandwidth.
At STEP 2010, the client sends, in response to the
AP-originated message, an AP-acknowledgement message.
The AP-acknowledgement message includes an acknowledgement that the AP-originated message was received. The
AP-acknowledgement message is sent via the bidirectional
download channel utilizing the download bandwidth.
At STEP 2020, the client sends a client-originated message. The client-originated message includes the requested
data or information about the requested data. The clientoriginated message is sent via the bidirectional upload
channel utilizing the upload bandwidth.
At STEP 2030, the AP sends, in response to the clientoriginated message, a client-acknowledgement message.
The client-acknowledgement message includes an acknowledgement that the client-originated message was received.
The client-acknowledgement message is sent using the
upload chain utilizing the upload bandwidth. The AP then
sends the requested data to the additional network.
In some cases, a traffic load ratio may change and the AP
may need to reallocate the total communication bandwidth
(130). FIG. SC illustrates a method of reallocating bandwidth (130) to the download bandwidth and the upload
bandwidth in accordance with one or more embodiments of
the invention. One or more steps shown in FIG. SC may be
omitted, repeated, and/or performed in a different order
among different embodiments of the invention. Each step of
FIG. SC is designated as (ULC) if the signal is send over the
bidirectional upload channel or (DLC) if sent over the
bidirectional download channel.
At STEP 3000, the access point determines that the
wireless link load ratio has changed. For example, a number
of clients may begin to request many video files contained
on the additional network. Such requests may increase the
amount of data that needs to be sent from the AP to the
clients over the wireless link. In one or more embodiments
of the invention, the access point determines a new download bandwidth and a new upload bandwidth in response to
determining that the wireless link load ratio has changed. In
one or more embodiments of the invention, the access point
determines a ratio of a new download bandwidth to a new
upload bandwidth in response to determining that the wireless link load ratio has changed.
At STEP 3010, the AP sends a channel update message to
all of the clients. In one or more embodiments of the
invention, the channel update message including a new
download bandwidth and a new upload bandwidth. More
specifically, the channel update message includes the new
channels that will be used for the download and upload
channels. Said another way, the channel update message will
specify one or more channel(s) (see FIG. 4B) or frequency
ranges that are to be used for each of the upload channel and
the download channel. The channel update message is sent
via the bidirectional download channel utilizing the download bandwidth. In one or more embodiments of the invention, the channel update message is sent through a broadcast
system according to the existing IEEE 802 .11 beacon system
used for access point presence identification and other
purposes.
In one or more embodiments of the invention, the channel
update message includes the ratio of a new download
bandwidth to a new upload bandwidth. More specifically,
the channel update message includes a new ratio of the total
available communication bandwidth to be assigned to the
bidirectional upload channel and to the bidirectional download channel, e.g., the ration may be 60:40, which represents
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that 60% of the total available communication bandwidth is
to be allocated to the bidirectional download channel and
40% of the total available communication bandwidth is to be
allocated to the bidirectional download channel.
In one or more embodiments of the invention, the access
point sets the download bandwidth of the access point to the
ratio of the total communication bandwidth and the upload
bandwidth of the access point to a remaining ratio of the
total communication bandwidth after sending the channel
update message. In one or more embodiments of the invention, the remaining ratio is calculated by the access point
based on the determined ratio. In one or more embodiments
of the invention, the access point set the download bandwidth of the access point to the new download bandwidth
and the upload bandwidth of the access point to the new
upload bandwidth after sending the channel update message.
AT STEP 3020, the client sets the download bandwidth
and the upload bandwidth based on the received channel
update message. In one or more embodiments of the invention, the client set the download bandwidth to the new
download bandwidth and the upload bandwidth to the new
upload bandwidth based on the information received in the
channel update message. At this point the clients and the AP
begin communicating using the new upload channel and
download channel.
FIG. 6 shows a comparison of the throughput ratio to the
load ratio of the disclosed wireless communication method
to existing communication methods due to load asymmetry.
The throughput ratio to the load ratio is the ratio of the
performance ratio of the download to upload ratio divided
by the ratio of the download traffic load to the upload traffic
load. If the ratio of the throughput ratio to the load ratio is
not 1, it indicates that the ratio of available download
bandwidth to download traffic load or upload bandwidth to
upload traffic load is mismatched and results in reduced
system performance.
The throughput ratio to the load ratio has been measured
for three different communication schemes under various
levels of download to upload traffic load asymmetry. As seen
from the plots, the Dual Wi-Fi method (which corresponds
to an implementation of one or more embodiments of the
invention) is able to match the download bandwidth to the
download traffic load and upload bandwidth to upload traffic
load independent of load asymmetry. Existing communication methods, such as IEEE 802.11 and WiFi-NC, are unable
to provide matched download bandwidth to the download
traffic load and upload bandwidth to upload traffic load
independent of load asymmetry. By matching these ratios,
the disclosed method of wireless network communication
provides improved wireless link efficiency.
FIG. 7 shows a comparison of the throughput ratio to the
load ratio of the disclosed wireless communication method
to existing communication methods due to client increase.
As the number of clients communicating with any access
point increases, channel contention increases.
The throughput ratio to the load ratio has been measured
for three difference communication schemes under various
levels of client load. As seen from the plots, the Dual Wi-Fi
method (which corresponds to an implementation of one or
more embodiments of the invention) is able to match the
download bandwidth to the download traffic load and upload
bandwidth to upload traffic load independent of the client
load. Existing communication methods, such as IEEE
802.11 and WiFi-NC, are unable to provide matched download bandwidth to the download traffic load and upload
bandwidth to upload traffic load independent of client load.
By matching these ratios independently of client load, the
disclosed method of wireless communication provides
improved wireless link efficiency.
FIG. 8 shows a comparison of the throughput gain of an
implementation of one embodiment of the invention versus
IEEE 802.11 for increasing levels of client load on an access
point. The throughput gains are broken down into aggregate
traffic, upload traffic, and download traffic. As seen from the
plot, as the total number of clients increases, APs and clients
implementing embodiments of the invention significantly
improves download traffic and shows significant improvements in aggregate traffic, e.g. aggregate traffic improves by
more than 30% for 100 clients. Accordingly, embodiments
of the invention may significantly improve download traffic
which greatly improves the user experience of the client.
Embodiments of the invention enable the division of the
total assigned bandwidth into two physical, bidirectional
channels. The bidirectional upload channel and bidirectional
download channel operate independently and asynchronously and are physically implemented in either contiguous
or non-contiguous frequency. The spectrum resources allocated to each channel is configurable by the access point
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(110).
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Embodiments of the invention enable decoupling of the
upload and download medium access by assigning the
bidirectional upload channel and bidirectional download
channel by message origination. Through this allocation,
messages sent via the bidirectional download channel and
bidirectional upload channel never compete for the same
spectrum resources, thereby allowing for simultaneous,
asynchronous, and independent upload and download Media
Access Control (MAC) layer data-handshakes. Consequently, in one or more embodiments of the invention the
channel architecture achieves spectrum isolation between
messages sent via the bidirectional upload channel and the
bidirectional download channel.
Embodiments of the invention enable physical bidirectional communication within the bidirectional upload channel and the bidirectional download channel to support the
complete MAC-layer data-acknowledgement handshake.
Specifically, MAC data traffic in each channel includes the
data flowing in one direction as originated messages and
Acknowledgments (ACKs) as acknowledgement messages
associated with the originated messages. Thus, no generic
control messages use either the bidirectional upload channel
or the bidirectional download channel, only the acknowledgement messages for the originated messages traveling in
each channel. Thus, the bidirectional upload channel and
bidirectional download channel provide control feedback
(acknowledgement messages) that are paired with transmitted data (originated messages), allowing asynchronous and
independent upload and download MAC traffic operation in
each channel.
One potential benefit of the bidirectional upload channel
and bidirectional download channel is the capability to
perform independent and asynchronous upload and download MAC level data-ACK transmissions. Having the complete MAC data-ACK handshake in each channel allows the
system to adjust MAC and Physical Layer level mechanisms
to independently address upload and download resource
allocation. In one or more embodiments of the invention, the
bidirectional capability of each channel permits independent
performance between upload and download MAC level
traffic.
Embodiments of the invention may impact the number of
contending nodes, e.g. APs (110) and clients (120A, 120B),
for each channel. In one embodiment of the invention, the
number of contending nodes is reduced to only the number
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of APs (110) in the bidirectional download channel. For
example, in the case when a single AP (110) is contending
for the bidirectional download channel, the contention for
the channel is eliminated which allows the bidirectional
download data channel to send back-to-back data transmission achieving close to full channel utilization. In another
example, only the clients (120A, 120B) contend for the
bidirectional upload channel. Consequently, smaller number
of nodes competing for the bidirectional upload channel or
bidirectional download channel reduces coordination time,
the number of collisions and retransmissions, and thus
increases spectral efficiency.
In many WLANs scenarios, the load transmitted from the
AP (110) to the clients (120A, 120B) far outweighs traffic
demand from the clients (120) to the AP (110), thereby
yielding traffic asymmetry. One or more embodiments of the
invention allows the flexible allocation of spectrum
resources to the logical channels. Based on the premise that
download data traffic is typically greater than upload data
traffic load, embodiments of the invention may allocate the
bidirectional download channel with more bandwidth, e.g.
increasing the download bandwidth (441) and decreasing the
upload bandwidth (442). Thus, the bidirectional download
channel may independently transmit more data than the
bidirectional upload channel at any instant.
When many clients (120) associate with a single AP (110),
for example, a large number of mobile phones with a single
AP (110), the clients (120) cause a disproportional amount
of medium contention compared to the AP (110), which
produces contention asymmetry. One or more embodiments
of the invention address contention asymmetry by eliminating the uneven number of upload and download devices
competing for the bidirectional upload channel or bidirectional download channel. More specifically, because clients
(120A, 120B) only contend for the bidirectional upload
channel and APs (110) only contend for the bidirectional
download channel, medium access contention in each channel is directly weighted on the traffic load of that direction.
Embodiments of the invention provide the flexibility to
separately address upload and download resource allocation.
Thus, in the presence of an upload or download medium
access issue, systems that implement embodiments of the
invention allows for an in-channel solution that is only
applied where required. For example, in the presence of
upload hidden terminals, the channel architecture allows the
implementation of any existing in-channel hidden terminal
MAC, such as RTS-CTS that is applied only to the upload
channel. In one or more embodiments of the invention, the
system isolates upload and download factors, allowing the
system to separately address issues found in either upload or
download transmissions.
Embodiments of the invention may increase network
performance without increasing the network resources.
Instead of increasing spectrum resources, embodiments of
the invention provide a mechanism to allocate traffic within
the channel to achieve higher spectral efficiency.
Further embodiments of the invention enable the preallocation of spectrum resources and achieve isolation
between upload and download traffic. Because existing
multi-channel systems do not differentiate between upload
and download traffic, increases in data rates are limited by
upload vs. download contention within the narrow channels.
Embodiments of the invention pre-allocate the upload bandwidth (442) and download bandwidth (441) to the bidirectional download channel and bidirectional upload channel
which presents the capability to adapt spectrum resources to
the traffic load, instead of presenting limited fixed width
sub-channels.
Embodiments of the invention permit physical bidirectional communication within the bidirectional upload channel and bidirectional download channel, and thereby enable
the complete MAC-layer data-ACK handshake within each
channel. As a result, embodiments of the invention may
enable in-channel control feedback that is paired with transmitted data (originated messages) that allows asynchronous
and independent upload and download MAC traffic operation. Further, embodiments of the invention enable the
configuration of bandwidth resources of each sub-channel to
match the system's traffic asymmetry or a desired download
and upload service.
Embodiments of the invention may combat traffic asymmetry from within the channel, without requiring adjusting
the total communication bandwidth (140). Specifically,
embodiments of the invention combat the issue from the
origin by separating upload and download contention to
provide the bandwidth each requires.
Additional embodiments of the invention isolate upload
and download data traffic, as a result traffic asymmetry may
be addressed under any environment. Moreover, embodiments of the invention provide a mechanism to select the
amount of bandwidth provided to either traffic direction that
are guaranteed. In contrast to a shared band system where
this is not easily defined and guaranteed.
Embodiments of the invention may support instantaneous
adaptation of bandwidth allocation by permitting dynamic
channel bandwidth division by adjusting the download
bandwidth (441) and the upload bandwidth (442).
While the invention has been described with respect to a
limited number of embodiments, those skilled in the art,
having the benefit of this disclosure, will appreciate that
other embodiments can be devised which do not depart from
the scope as disclosed herein. Accordingly, the scope should
be limited by the attached claims.
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What is claimed is:
1. A method of operating a wireless local area network
between a client and an access point (AP) to increase
efficiency of a total communication bandwidth, the method
comprising:
determining, by the AP, a ratio of a download load to an
upload load between the AP and the client;
allocating, by the AP and based on the ratio, a first portion
of the total communication bandwidth to a wireless
bidirectional upload channel,
allocating, by the AP and based on the ratio, a second
portion of the total communication bandwidth to a
wireless bidirectional download channel,
wherein the wireless bidirectional download channel and
the wireless bidirectional upload channel are spectrally
isolated and operated asynchronously;
sending, by the AP, a channel update message comprising
the ratio to the client,
wherein the client is restricted from sending client-originated messages over the wireless bidirectional download channel to reduce contention for the wireless
bidirectional download channel;
receiving, by the AP comprising an antenna, a clientoriginated message over the wireless bidirectional
upload channel;
sending, by the AP, an AP-acknowledgement message to
the client over the wireless bidirectional upload channel;
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sending, by the AP, an AP-originated message to the client
over the wireless bidirectional download channel
wherein the AP-originated message was generated i~
response to the client-originated message; and
receiving, by the AP, a client-acknowledgment message
from the client over the wireless bidirectional download channel.
2. An access point (AP) that increases the efficiency of a
total communication bandwidth in a wireless local area
network, comprising:
a download chain comprising a download media access
control layer and a download physical layer, a download transceiver, and a download antenna, wherein the
download chain is configured to:
send an AP-originated message over a wireless bidirectional download channel,
receive a client-acknowledgement message on the
wireless bidirectional download channel
an upload chain comprising an upload m;dia access
control layer and an upload physical layer, an upload
transceiver, and an upload antenna, wherein the upload
chain is configured to:
receive a client-originated message over a wireless
bidirectional upload channel,
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send a AP-acknowledgement message on the wireless
bidirectional upload channel,
an AP controller configured to:
forward the download data to the download chain
forward the upload acknowledgement to the upload
chain,
determine a ratio of a download load to an upload load
between the AP and the client;
allocate, based on the ratio, a first portion of the total
communication bandwidth to the wireless bidirectional upload channel;
allocate, based on the ratio, a second portion of the total
communication bandwidth to the wireless bidirectional download channel,
wherein the wireless bidirectional download channel and
the wireless bidirectional upload channel are spectrally-isolated and operated as asynchronously;
generate a channel update message comprising the ratio
for transmission to the client,
wherein the client is restricted from sending client-originated messages over the wireless bidirectional download channel to reduce contention for the wireless
bidirectional download channel.
* * * * *
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