U.S. patent application number 11/143559 was filed with the patent office on 2012-02-09 for method and system for achieving enhanced quality and higher throughput for collocated ieee 802.11b/g and bluetooth devices in coexistent operation.
Invention is credited to Prasanna Desai, Brima Ibrahim.
Application Number | 20120034870 11/143559 |
Document ID | / |
Family ID | 35395660 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120034870 |
Kind Code |
A9 |
Desai; Prasanna ; et
al. |
February 9, 2012 |
Method and system for achieving enhanced quality and higher
throughput for collocated IEEE 802.11B/G and bluetooth devices in
coexistent operation
Abstract
A method and system for achieving enhanced quality and higher
throughput for collocated IEEE 802.11b/g and Bluetooth (BT) devices
in coexistent operation are provided. A priority signal may be
generated by a BT radio in a coexistence station to disable WLAN
transmissions in a WLAN radio when a BT HV3 frame is available for
transmission. When the priority signal is asserted, an
exponentially growing retransmission backoff mechanism in the WLAN
radio may be disabled. Moreover, when the BT radio and the WLAN
radio are enabled for coexistence operation, a WLAN fragmentation
threshold in the WLAN radio may be modified based on a WLAN
modulation rate and the BT HV3 frame duration.
Inventors: |
Desai; Prasanna;
(Olivenhain, CA) ; Ibrahim; Brima; (Aliso Viejo,
CA) |
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20060030266 A1 |
February 9, 2006 |
|
|
Family ID: |
35395660 |
Appl. No.: |
11/143559 |
Filed: |
June 2, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10387249 |
Mar 12, 2003 |
|
|
|
11143559 |
Jun 2, 2005 |
|
|
|
60600394 |
Aug 9, 2004 |
|
|
|
60400226 |
Aug 1, 2002 |
|
|
|
Current U.S.
Class: |
455/41.2 ;
455/74 |
Current CPC
Class: |
H04W 16/14 20130101;
H04W 74/0875 20130101; H04W 84/12 20130101; H04W 72/1215 20130101;
H04W 88/06 20130101; H04W 84/18 20130101 |
Class at
Publication: |
455/041.2 ;
455/074 |
International
Class: |
H04B 7/00 20060101
H04B007/00 |
Claims
1. A method for providing wireless communication, the method
comprising: in a station that handles at least a Bluetooth (BT)
communication protocol and a Wireless Local Area Network (WLAN)
communication protocol: asserting a BT priority signal for
transmitting HV3 data; disabling WLAN transmission capabilities
based on said asserted BT priority signal; and transmitting said
HV3 data when said WLAN transmission capabilities are disabled.
2. The method according to claim 1, further comprising deasserting
said BT priority signal when said transmitting of said HV3 data is
complete.
3. The method according to claim 2, further comprising enabling
said WLAN transmission capabilities when said BT priority signal is
deasserted.
4. The method according to claim 1, further comprising generating
said BT priority signal at least a predetermined guard time before
transmitting said HV3 data.
5. The method according to claim 1, further comprising turning OFF
a power amplifier when disabling said WLAN transmission
capabilities.
6. The method according to claim 1, further comprising disabling an
exponentially growing retransmission backoff in said WLAN
communication protocol when said BT priority signal is
asserted.
7. A method for providing wireless communication, the method
comprising: enabling a Bluetooth (BT) communication protocol and a
Wireless Local Area Network (WLAN) communication protocol in a
station; and modifying a WLAN fragmentation threshold utilized by
said WLAN communication protocol based on a WLAN modulation rate
and an HV3 frame duration utilized by said BT communication
protocol.
8. The method according to claim 7, further comprising generating a
coexistence signal to enable said BT communication protocol and
said WLAN communication protocol.
9. The method according to claim 7, further comprising modifying
said WLAN modulation rate.
10. A system for providing wireless communication, the system
comprising: a station that comprises a Bluetooth (BT) radio that
handles a Bluetooth (BT) communication protocol and a Wireless
Local Area Network (WLAN) radio that handles a WLAN communication
protocol; said BT radio asserts a BT priority signal for
transmitting HV3 data; said WLAN radio disables WLAN transmission
capabilities based on said asserted BT priority signal; and said BT
radio transmits said HV3 data when said WLAN transmission
capabilities are disabled.
11. The system according to claim 10, wherein said BT radio
deasserts said BT priority signal when said transmitting of said
HV3 data is complete.
12. The system according to claim 11, wherein said WLAN radio
enables said WLAN transmission capabilities when said BT priority
signal is deasserted.
13. The system according to claim 10, wherein said BT radio
generates said BT priority signal at least a predetermined guard
time before transmitting said HV3 data.
14. The system according to claim 10, wherein said WLAN radio turns
OFF a power amplifier when disabling said WLAN transmission
capabilities.
15. The system according to claim 10, wherein said WLAN radio
disables an exponentially growing retransmission backoff in said
WLAN communication protocol when said BT priority signal is
asserted.
16. A system for providing wireless communication, the system
comprising: a station that comprises a Bluetooth (BT) radio that
handles a Bluetooth (BT) communication protocol and a Wireless
Local Area Network (WLAN) radio that handles a WLAN communication
protocol; and at least one processor that modifies a WLAN
fragmentation threshold utilized by said WLAN radio based on a WLAN
modulation rate and an HV3 frame duration utilized by said BT
radio.
17. The system according to claim 16, wherein said at least one
processor generates a coexistence signal to enable said BT radio
and said WLAN radio.
18. The system according to claim 16, wherein said station modifies
said WLAN modulation rate.
19. A machine-readable storage having stored thereon, a computer
program having at least one code section for providing wireless
communication, the at least one code section being executable by a
machine for causing the machine to perform steps comprising: in a
station that handles at least a Bluetooth (BT) communication
protocol and a Wireless Local Area Network (WLAN) communication
protocol: asserting a BT priority signal for transmitting HV3 data;
disabling WLAN transmission capabilities based on said asserted BT
priority signal; and transmitting said HV3 data when said WLAN
transmission capabilities are disabled.
20. The machine-readable storage according to claim 19, further
comprising code for deasserting said BT priority signal when said
transmitting of said HV3 data is complete.
21. The machine-readable storage according to claim 20, further
comprising code for enabling said WLAN transmission capabilities
when said BT priority signal is deasserted.
22. The machine-readable storage according to claim 19, further
comprising code for generating said BT priority signal at least a
predetermined guard time before transmitting said HV3 data.
23. The machine-readable storage according to claim 19, further
comprising turning OFF a power amplifier when disabling said WLAN
transmission capabilities.
24. The machine-readable storage according to claim 19, further
comprising code for disabling an exponentially growing
retransmission backoff in said WLAN communication protocol when
said BT priority signal is asserted.
25. A machine-readable storage having stored thereon, a computer
program having at least one code section for providing wireless
communication, the at least one code section being executable by a
machine for causing the machine to perform steps comprising:
enabling a Bluetooth (BT) communication protocol and a Wireless
Local Area Network (WLAN) communication protocol in a station; and
modifying a WLAN fragmentation threshold utilized by said WLAN
communication protocol based on a WLAN modulation rate and an HV3
frame duration utilized by said BT communication protocol.
26. The machine-readable storage according to claim 25, further
comprising code for generating a coexistence signal to enable said
BT communication protocol and said WLAN communication protocol.
27. The machine-readable storage according to claim 25, further
comprising code for modifying said WLAN modulation rate.
Description
BACKGROUND OF THE INVENTION
[0001] The use of Wireless Personal Area Networks (WPANs) has been
gaining popularity in a great number of applications because of the
flexibility and convenience in connectivity they provide. WPAN
systems, such as those based on Bluetooth (BT) technology, replace
cumbersome cabling and/or wiring used to connect peripheral devices
and/or mobile terminals by providing short distance wireless links
that allow connectivity within a 10-meter range. In contrast to
WPAN systems, Wireless Local Area Networks (WLANs) provide
connectivity to devices that are located within a slightly larger
geographical area, such as the area covered by a building or a
campus, for example. WLAN systems are based on IEEE 802.11 standard
specifications, typically operate within a 100-meter range, and are
generally utilized to supplement the communication capacity
provided by traditional wired Local Area Networks (LANs) installed
in the same geographic area as the WLAN system.
[0002] In some instances, WLAN systems may be operated in
conjunction with WPAN systems to provide users with an enhanced
overall functionality. For example, Bluetooth technology may be
utilized to connect a laptop computer or a handheld wireless
terminal to a peripheral device, such as a keyboard, mouse,
headphone, and/or printer, while the laptop computer or the
handheld wireless terminal is also connected to a campus-wide WLAN
network through an access point (AP) located within the
building.
[0003] Both Bluetooth and WLAN radio devices, such as those used
in, for example, handheld wireless terminals, generally operate in
the 2.4 GHz (2.4000-2.4835 GHz) Industrial, Scientific, and Medical
(ISM) unlicensed band. Other radio devices, such as those used in
cordless phones, may also operate in the ISM unlicensed band. While
the ISM band provides a suitable low-cost solution for many of
short-range wireless applications, it may also have some drawbacks
when multiple users operate simultaneously. For example, because of
the limited bandwidth, spectrum sharing may be necessary to
accommodate multiple users. Multiple active users may also result
in significant interference between operating devices. Moreover, in
some instances, microwave ovens may also operate in this frequency
spectrum and may produce significant interference or blocking
signals that may affect Bluetooth and/or WLAN transmissions.
[0004] When operating a Bluetooth radio and a WLAN radio in, for
example, a wireless device, at least two different types of
interference effects may occur. First, when an interfering signal
is present in a transmission medium along with the
signal-of-interest, a low signal-to-noise-plus-interference ratio
(SINR) may result. In this instance, for example, a Bluetooth
signal may interfere with a WLAN signal or a WLAN signal may
interfere with a Bluetooth signal. The second effect may occur when
the Bluetooth and WLAN radio devices are collocated, that is, when
they are located in close proximity to each other so that there is
a small radio frequency (RF) path loss between their corresponding
radio front-end receivers. In this instance, the isolation between
the Bluetooth radio front-end and the WLAN radio front-end may be
as low as 10 dB, for example. As a result, one radio may
desensitize the front-end of the other radio upon transmission.
Moreover, since Bluetooth employs transmit power control, the
collocated Bluetooth radio may step up its power level when the
signal-to-noise ratio (SNR) on the Bluetooth link is low,
effectively compromising the front-end isolation between radio
devices even further. Low noise amplifiers (LNAs) in the radio
front-ends may not be preceded by a channel selection filter and
may be easily saturated by the signals in the ISM band, such as
those from collocated transmissions. The saturation may result in a
reduction in sensitivity or desensitization of the receiver portion
of a radio front-end, which may reduce the radio front-end's
ability to detect and demodulate the desired signal.
[0005] Packet communication in WLAN systems requires
acknowledgement from the receiver in order for the communication to
proceed. When the isolation between collocated radio devices is
low, collisions between WLAN communication and Bluetooth
communication, due to greater levels of mutual interference than if
the isolation were high, may result in a slowdown of the WLAN
communication, as the access point does not acknowledge packets.
This condition may continue to spiral downwards until the access
point drops the WLAN station. If, in order to avoid this condition,
WLAN communication in collocated radio devices is given priority
over all Bluetooth communication, then isochronous Bluetooth packet
traffic, which does not have retransmission capabilities, may be
starved of communication bandwidth. Moreover, this approach may
also starve other Bluetooth packet traffic of any communication
access. Collocated WLAN/Bluetooth radio devices should therefore be
operated so as to maintain WLAN communication rates high while also
providing access to Bluetooth communication when necessary.
[0006] Different techniques have been developed to address the low
isolation problem that occurs between collocated Bluetooth and WLAN
radio devices in coexistent operation. These techniques may take
advantage of either frequency and/or time orthogonality mechanisms
to reduce interference between collocated radio devices. Moreover,
these techniques may result from so-called collaborative or
non-collaborative mechanisms in Bluetooth and WLAN radio devices,
where collaboration refers to any direct communication between the
protocols. For example, Bluetooth technology utilizes Adaptive
Frequency Hopping (AFH) as a frequency division multiplexing (FDM)
technique that minimizes channel interference. In AFH, the physical
channel is characterized by a pseudo-random hopping, at a rate of
1600 hops-per-second, between 79 1 MHz channels in the Bluetooth
piconet. AFH provides a non-collaborative mechanism that may be
utilized by a Bluetooth device to avoid frequencies occupied by a
spread spectrum system such as a WLAN system. In some instances,
the Bluetooth radio may be adapted to modify its hopping pattern
based on, for example, frequencies in the ISM spectrum that are not
being occupied by other users.
[0007] Even when frequency division multiplexing techniques are
applied, significant interference may still occur because a strong
signal in a separate channel may still act as a blocking signal and
may desense the radio front-end receiver, that is, increase the
receiver's noise floor to the point that the received signal may
not be clearly detected. For example, a collocated WLAN radio
front-end transmitter generating a 15 dBm signal acts as a strong
interferer or blocker to a collocated Bluetooth radio device
receiver when the isolation between radio devices is only 10 dB.
Similarly, when a Bluetooth radio device is transmitting and a WLAN
radio device is receiving, particularly when the Bluetooth radio
front-end transmitter is operating as a 20 dBm Class 1 type, the
WLAN radio device receiver may be desensed by the Bluetooth
transmission as the isolation between radios is reduced. Due to
high-volume, low-cost nature of WLAN and BT radio chips, the more
expensive Surface Acoustic Wave (SAW) filtering devices that may
filter out blocking signals from nearby channels are not generally
utilized and collocated WLAN/Bluetooth radio device interference
remains a concern in WPAN applications.
[0008] Other techniques may be based on collaborative coexistence
mechanisms, such as those described in the IEEE 802.15.2-2002
Recommended Practice for Information Technology--Part 15.2:
Coexistence of Wireless Personal Area Networks with Other Wireless
Devices Operating in the Unlicensed Frequency Bands. For example,
these techniques may comprise Medium Access Control (MAC) layer
mechanisms or Physical (PHY) layer mechanisms. The MAC layer
techniques may comprise, for example, the Alternating Wireless
Medium Access (AWMA) technique or the Packet Traffic Arbitration
(PTA) technique. Both the AWMA and the PTA techniques provide a
time division multiplexing (TDM) approach to the collocated radio
device isolation problem. For example, the AWMA technique
partitions a WLAN communication interval into two segments: one for
the WLAN system and one for the WPAN system. Each wireless system
is then restricted to transmissions in their allocated time
segments. On the other hand, the PTA technique provides for each
communication attempt by either a collocated WLAN radio device or a
Bluetooth radio device to be submitted for arbitration and
approval. The PTA may then deny a communication request that would
result in collision or interference. The PHY layer technique may
comprise, for example, a programmable notch filter in the WLAN
radio device receiver to filter out narrow-band WPAN or Bluetooth
interfering signals. These techniques may result in some
transmission inefficiencies or in the need of additional hardware
features in order to achieve better coexistent operation.
[0009] Other collaborative coexistence mechanisms may be based on
proprietary technologies. For example, in some instances, firmware
in the collocated WLAN radio device may be utilized to poll a
status signal in the collocated Bluetooth radio device to determine
whether Bluetooth communication is to occur. However, polling the
Bluetooth radio device may have to be performed on a fairly
constant basis and may detract the WLAN radio device from its own
WLAN communication operations. If a polling window is utilized
instead, where the polling window may be as long as several hundred
microseconds, the WLAN radio device may not perform its WLAN
protocol operations during that time with the expectation that the
Bluetooth radio device may indicate that Bluetooth communication is
to occur. In other instances, the collocated WLAN and Bluetooth
radio devices may utilize an interrupt-driven arbitration approach.
In this regard, considerable processing time may be necessary for
performing the interrupt operation and to determine the appropriate
communication schedule based on the priority and type of WLAN and
Bluetooth packets.
[0010] Further limitations and disadvantages of conventional and
traditional approaches will become apparent to one of skill in the
art, through comparison of such systems with some aspects of the
present invention as set forth in the remainder of the present
application with reference to the drawings.
BRIEF SUMMARY OF THE INVENTION
[0011] A method and/or system for achieving enhanced quality and
higher throughput for collocated IEEE 802.11b/g and Bluetooth
devices in coexistent operation, substantially as shown in and/or
described in connection with at least one of the drawings, as set
forth more completely in the claims.
[0012] These and other advantages, aspects and novel features of
the present invention, as well as details of an illustrated
embodiment thereof, will be more fully understood from the
following description and drawings.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0013] FIG. 1A is a block diagram of an exemplary WLAN
infrastructure network comprising basic service sets (BSSs)
integrated using a common distribution system (DS), in connection
with an embodiment of the invention.
[0014] FIG. 1B is a block diagram of an exemplary WLAN
infrastructure network comprising a basic service set (BSS) with
stations that support WLAN/Bluetooth coexistence, in accordance
with an embodiment of the invention.
[0015] FIG. 1C is a block diagram that illustrates an exemplary
usage model for a coexistence terminal with collocated WLAN and
Bluetooth radio devices, in accordance with an embodiment of the
invention.
[0016] FIG. 2A is a block diagram of an exemplary WLAN/Bluetooth
collaborative radio architecture with the WLAN device configuring
the antenna system and the BT device having a single TX/RX port, in
accordance with an embodiment of the invention.
[0017] FIG. 2B is a block diagram of an exemplary WLAN/Bluetooth
collaborative radio architecture with the WLAN device configuring
the antenna system and the BT device having separate TX and RX
ports, in accordance with an embodiment of the invention.
[0018] FIG. 2C is a block diagram of an exemplary WLAN/Bluetooth
collaborative architecture with both radio devices configuring the
antenna system and the Bluetooth radio device having a single TX/RX
port, in accordance with an embodiment of the invention.
[0019] FIG. 2D is a block diagram of an exemplary WLAN/Bluetooth
collaborative architecture with both radio devices configuring the
antenna system and the Bluetooth radio device having separate TX
and RX ports, in accordance with an embodiment of the
invention.
[0020] FIG. 3 is a timing diagram that illustrates an exemplary
communication of BT HV3 frames and WLAN transmissions based on the
TX_BT signal, in accordance with an embodiment of the
invention.
[0021] FIG. 4 is a timing diagram that illustrates exemplary
assertion instances of the TX_BT signal, in accordance with an
embodiment of the invention.
[0022] FIG. 5A is a flow diagram that illustrates exemplary steps
for priority communication of BT HV3 traffic when utilizing a
predetermined guard time, in accordance with an embodiment of the
invention.
[0023] FIG. 5B is a flow diagram that illustrates exemplary steps
for priority communication of BT HV3 traffic when the TX_BT signal
is utilized to turn OFF a WLAN radio power amplifier, in accordance
with an embodiment of the invention.
[0024] FIG. 5C is a flow diagram that illustrates exemplary steps
for modifying a WLAN fragmentation threshold based on a WLAN
modulation rate, in accordance with an embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Certain embodiments of the invention may be found in a
method and system for achieving enhanced quality and higher
throughput for collocated IEEE 802.11b/g and Bluetooth (BT) devices
in coexistent operation. A priority signal may be generated by a BT
radio in a coexistence station to disable WLAN transmissions in a
WLAN radio when a BT HV3 frame is available for transmission. When
the priority signal is asserted, an exponentially growing
retransmission backoff mechanism in the WLAN radio may be disabled.
Moreover, when the BT radio and the WLAN radio are enabled for
coexistence operation, a WLAN fragmentation threshold in the WLAN
radio may be modified based on a WLAN modulation rate and the BT
HV3 frame duration. This approach may provide an improvement in the
performance of collocated WLAN and BT radio devices in coexistent
operation.
[0026] FIG. 1A is a block diagram of an exemplary WLAN
infrastructure network comprising basic service sets (BSSs)
integrated using a common distribution system (DS), in connection
with an embodiment of the invention. Referring to FIG. 1A, the
exemplary WLAN infrastructure network 100 shown may comprise a
first BSS 102a, a second BSS 102b, a DS 104, a wired network 106, a
portal 108, a first access point (AP) 112a, a second AP 102b, and a
plurality of WLAN stations (STAs). The BSSs 102a and 102b may
represent a fundamental building block of the IEEE 802.11 (WLAN)
architecture and may be defined as a group of stations (STAs) that
are under the direct control of a single coordination function. The
geographical area covered by a BSS is known as the basic service
area (BSA). The DS 104 may be utilized to integrate the BSSs 102a
and 102b and may comprise suitable hardware, logic, circuitry,
and/or code that may be adapted to operate as a backbone network
that is responsible for Medium Access Control (MAC) level transport
in the WLAN infrastructure network 100. The DS 104, as specified by
the IEEE 802.11 standard, is implementation independent. For
example, the DS 104 may be implemented utilizing IEEE 802.3
Ethernet Local Area Network (LAN), IEEE 802.4 token bus LAN, IEEE
802.5 token ring LAN, Fiber Distributed Data Interface (FDDI)
Metropolitan Area Network (MAN), or another IEEE 802.11 wireless
medium. The DS 104 may be implemented utilizing the same physical
medium as either the first BSS 102a or the second BSS 102b.
However, the DS 104 is logically different from the BSSs and may be
utilized only to transfer packets between the BSSs and/or to
transfer packets between the BSSs and the wired network 106.
[0027] The wired network 106 may comprise suitable hardware, logic,
circuitry, and/or code that may be adapted to provide wired
networking operations. The wired network 106 may be accessed from
the WLAN infrastructure network 100 via the portal 108. The portal
108 may comprise suitable hardware, logic, circuitry, and/or code
and may be adapted to integrate the WLAN infrastructure network 100
with non-IEEE 802.11 networks. Moreover, the portal 108 may also be
adapted to perform the functional operations of a bridge, such as
range extension and/or translation between different frame formats,
in order to integrate the WLAN infrastructure network 100 with IEEE
802.11-based networks.
[0028] The APs 112a and 112b may comprise suitable hardware, logic,
circuitry, and/or code that may be adapted to support range
extension of the WLAN infrastructure network 100 by providing the
integration points necessary for network connectivity between the
BSSs. The STA 110a and the STA 110b correspond to WLAN-enabled
terminals that comprise suitable hardware, logic, circuitry, and/or
code that may be adapted to provide connectivity to the WLAN
infrastructure network 100 via the APs. The STA 110a shown is a
laptop computer and may correspond to a mobile station or terminal
within the BSS and the STA 110b shown is a desktop computer and may
correspond to a fixed or stationary terminal within the BSS. Each
BSS may comprise a plurality of mobile or fixed stations and may
not be limited to the exemplary implementation shown in FIG.
1A.
[0029] FIG. 1B is a block diagram of an exemplary WLAN
infrastructure network comprising a basic service set (BSS) with
stations that support WLAN/Bluetooth coexistence, in accordance
with an embodiment of the invention. Referring to FIG. 1B, the
exemplary WLAN infrastructure network 120 shown differs from the
WLAN infrastructure network 100 in FIG. 1A in that at least one BSS
comprises at least one station or terminal that supports Bluetooth
technology. In this regard, the second BSS 102b comprises
additional mobile terminals or stations such as a Personal Digital
Assistant (PDA) 110c and a mobile phone 110d while the laptop
computer 110a is now shown to be Bluetooth-enabled. The peripheral
devices 114 shown may be part of the Wireless Personal Area Network
(WPAN) supported by the Bluetooth-enabled laptop computer. For
example, the laptop computer 110a may communicate via Bluetooth
technology with a keyboard, a mouse, a printer, a mobile phone, a
PDA, and/or a set of headphones or speakers, where these devices
and the laptop computer 110a may form an ad-hoc Bluetooth piconet.
Generally, a Bluetooth piconet may comprise a master device or
terminal and up to seven slave devices or terminals. In this
exemplary implementation, the laptop computer 110a may correspond
to the master Bluetooth terminal and the peripheral devices 114 may
correspond to the slave Bluetooth terminals.
[0030] The Bluetooth-enabled laptop computer 110a in FIG. 1B may
comprise a WLAN radio device and a Bluetooth radio device that
allows it to communicate with the WLAN infrastructure network 100
via the AP 112b and with the Bluetooth piconet respectively.
Because of the size of the laptop computer 110a, locating the WLAN
and BT radio devices in the same terminal may result in signal
interference between WLAN and BT communications. When the PDA 110c
and/or the mobile phone 110d are Bluetooth-enabled, the small form
factor of these coexistence terminals may result in a small radio
frequency (RF) path loss between WLAN and BT radio devices and
likely interference between WLAN and BT communications.
[0031] FIG. 1C is a block diagram that illustrates an exemplary
usage model for a coexistence terminal with collocated WLAN and
Bluetooth radio devices, in accordance with an embodiment of the
invention. Referring to FIG. 1C, the mobile phone 110d may comprise
a WLAN radio device to communicate with the AP 112c. The RF path
loss between the AP 112c and the mobile phone 110d may be, for
example, 65 dB for 10 meters. The IEEE 802.15.2 draft, for example,
provides a formula for calculating the RF path loss. The mobile
phone 110d may also be Bluetooth-enabled and may comprise a
Bluetooth radio device to communicate with, for example, a
Bluetooth headset 122 and/or a home gateway 124 with Bluetooth
cordless telephony capability. Because of the small form factor of
the mobile phone 110d, the WLAN and Bluetooth radio devices may be
in such close proximity to each other within the same coexistence
terminal that the isolation between them is sufficiently low to
allow desensitization of one radio device by the other.
[0032] The Bluetooth-enabled mobile phone 110d may comprise two
transmission power levels. For example, the mobile phone 110d may
operate as a Class 1 power level terminal with a maximum
transmission power of 20 dBm to communicate with the home gateway
124. In another example, the mobile phone 110d may operate as a
Class 2 power level terminal with a maximum transmission power of 4
dBm to communicate with the Bluetooth headset 122. The Bluetooth
headset 122 may comprise suitable hardware, logic, circuitry,
and/or code that may be adapted to receive and/or transmit audio
information. For example, the Bluetooth handset 122 may be adapted
to receive and/or transmit Continuous Variable Slope Delta (CVSD)
modulated voice from the mobile phone 110d or receive A2DP, such as
MP3, from the mobile phone 110d. The home gateway 124 may comprise
suitable hardware, logic, circuitry, and/or code that may be
adapted to receive and/or transmit data and/or audio information.
For example, the home gateway 124 may receive and/or transmit 64
kb/s CVSD modulated voice.
[0033] In operation, the mobile phone 110d may receive voice or
audio content from the WLAN infrastructure network via the AP 112c
and may communicate the voice or audio contents to the Bluetooth
headset 122 or the voice contents to the home gateway 124.
Similarly, the Bluetooth headset 122 the home gateway 124 may
communicate voice contents to the Bluetooth-enabled mobile phone
110d which in turn may communicate the voice contents to other
users through the WLAN infrastructure network.
[0034] FIG. 2A is a block diagram of an exemplary WLAN/Bluetooth
collaborative radio architecture with the WLAN device configuring
the antenna system and the Bluetooth device having a single TX/RX
port, in accordance with an embodiment of the invention. Referring
to FIG. 2A, the WLAN/Bluetooth collaborative radio architecture 200
may comprise a WLAN/Bluetooth coexistence antenna system 202, a
WLAN radio device 204, and a Bluetooth radio device 206. The
WLAN/Bluetooth coexistence antenna system 202 may comprise suitable
hardware, logic, and/or circuitry that may be adapted to provide
WLAN and Bluetooth communication between external devices and a
coexistence terminal. The WLAN/Bluetooth coexistence antenna system
202 may comprise at least one antenna for the transmission and
reception of WLAN and BT packet traffic. In this regard, the
antenna or antennas utilized in the WLAN/Bluetooth coexistence
antenna system 202 may be designed to meet the form factor
requirements of the coexistence terminal.
[0035] The WLAN radio device 204 may comprise suitable logic,
circuitry, and/or code that may be adapted to process WLAN protocol
packets for communication. The WLAN radio device 204 may comprise
an antenna controller 208 that may comprise suitable logic,
circuitry, and/or code that may be adapted to generate at least one
control signal 210 to configure the operation of the WLAN/Bluetooth
coexistence antenna system 202. In this regard, the control signal
210 may be utilized to configure the WLAN/Bluetooth coexistence
antenna system 202 for WLAN or Bluetooth communication. As shown,
the WLAN radio device 204 may comprise separate ports for
transmission (TX) and reception (RX) of WLAN packet traffic.
However, a single TX/RX port may also be utilized for WLAN
communication.
[0036] The WLAN radio device 204 may be adapted to generate a WLAN
transmission (TX_WLAN) signal and to assert the TX_WLAN signal
during WLAN communication. The WLAN radio device 204 may also be
adapted to receive a Bluetooth priority (TX_BT) signal from the
Bluetooth radio device 206. When the Bluetooth radio device 206
asserts the TX_BT signal, the transmission of WLAN traffic from the
WLAN radio device 204 may be disabled. No polling or
interrupt-driven mechanism need be utilized. In this regard,
disabling the transmission path in the WLAN radio device 204 may be
performed by, for example, utilizing a general purpose input/output
(GPIO) pin. This approach may be similar to disabling a WLAN device
in airplanes so that passengers may be sure the radios in their
portable devices are turned off and cannot interfere with the
airplane's systems. When the Bluetooth radio device 206 deasserts
the TX_BT signal, the transmission of WLAN traffic from the WLAN
radio device 204 may be enabled. Firmware operating in the WLAN
radio device 204 may track the traffic status when WLAN
transmission is disabled and may utilize the traffic status to
resume communications once WLAN transmission is enabled.
[0037] The Bluetooth radio device 206 may comprise suitable logic,
circuitry, and/or code that may be adapted to process Bluetooth
protocol packets for communication. As shown, the Bluetooth radio
device 206 may comprise a single port for transmission and
reception (TX/RX) of Bluetooth packet traffic. The Bluetooth radio
device 206 may be adapted to generate the TX_BT signal and to
assert the signal when Bluetooth frames are available for
communication. The TX_BT signal may be transferred to the WLAN
radio device via a GPIO pin in the Bluetooth radio device 206. The
Bluetooth radio device 206 may also be adapted to deassert the
TX_BT signal when communication of the Bluetooth frames has been
completed.
[0038] In some instances, either the WLAN radio device 204 or the
Bluetooth radio device 206 may be disabled and the wireless
terminal may not operate in a coexistence mode. When the WLAN radio
device 204 is disabled, the WLAN/Bluetooth coexistence antenna
system 202 may utilize a default configuration to support Bluetooth
communication. When the Bluetooth radio device 206 is disabled, the
antenna controller 208 may configure the WLAN/Bluetooth coexistence
antenna system 202 to support WLAN communication.
[0039] FIG. 2B is a block diagram of an exemplary WLAN/Bluetooth
collaborative radio architecture with the WLAN device configuring
the antenna system and the Bluetooth device having separate TX and
RX ports, in accordance with an embodiment of the invention.
Referring to FIG. 2B, the WLAN/Bluetooth collaborative radio
architecture 220 may comprise the WLAN/Bluetooth coexistence
antenna system 202, the WLAN radio device 204, and the Bluetooth
radio device 206. In this regard, the Bluetooth radio device 206 in
FIG. 2B comprises separate transmission (TX) and reception (RX)
ports for Bluetooth communication. The antenna controller 208 and
the control signal 210 may be adapted to configure the
WLAN/Bluetooth coexistence antenna system 202 to accommodate for
the separate TX and RX ports in the Bluetooth radio device 206.
[0040] In some instances, either the WLAN radio device 204 or the
Bluetooth radio device 206 may be disabled and the wireless
terminal may not operate in a coexistence mode. When the WLAN radio
device 204 is disabled, the WLAN/Bluetooth coexistence antenna
system 202 may utilize a default configuration to support Bluetooth
communication. When the Bluetooth radio device 206 is disabled, the
antenna controller 208 may configure the WLAN/Bluetooth coexistence
antenna system 202 to support WLAN communication.
[0041] FIG. 2C is a block diagram of an exemplary WLAN/Bluetooth
collaborative architecture with both radio devices configuring the
antenna system and the Bluetooth radio device having a single TX/RX
port, in accordance with an embodiment of the invention. Referring
to FIG. 2C, the WLAN/Bluetooth collaborative radio architecture 230
may comprise the WLAN/Bluetooth coexistence antenna system 202, the
WLAN radio device 204, and the Bluetooth radio device 206. The
Bluetooth radio device 206 may be adapted to generate a
configuration signal 212 to indicate different priority conditions
that may be associated with different types of Bluetooth packets.
The configuration signal 212 may be transferred to the
WLAN/Bluetooth coexistence antenna system 202 via a GPIO pin in the
Bluetooth radio device 206. In this regard, the configuration
signal 212 may be at least 1-bit wide in order to provide higher
granularity or priority selection during coexistence operation. The
TX_BT and/or the configuration signal 212 may be utilized with
and/or instead of the control signal 210 to configure the
WLAN/Bluetooth coexistence antenna system 202.
[0042] In some instances, either the WLAN radio device 204 or the
Bluetooth radio device 206 may be disabled and the wireless
terminal may not operate in a coexistence mode. When the WLAN radio
device 204 is disabled, the Bluetooth radio 206 may configure the
WLAN/Bluetooth coexistence antenna system 202 via the configuration
signal 212 to support Bluetooth communication. When the Bluetooth
radio device 206 is disabled, the antenna controller 208 may
configure the WLAN/Bluetooth coexistence antenna system 202 to
support WLAN communication.
[0043] FIG. 2D is a block diagram of an exemplary WLAN/Bluetooth
collaborative architecture with both radio devices configuring the
antenna system and the Bluetooth radio device having separate TX
and RX ports, in accordance with an embodiment of the invention.
Referring to FIG. 2D, the WLAN/Bluetooth collaborative radio
architecture 240 may comprise the WLAN/Bluetooth coexistence
antenna system 202, the WLAN radio device 204, and the Bluetooth
radio device 206. The Bluetooth radio device 206 may comprise
separate transmission (TX) and reception (RX) ports for Bluetooth
communication. In this regard, the configuration signal 212 may be
utilized to configure the WLAN/Bluetooth coexistence antenna system
202 to support separate TX and RX ports for Bluetooth
communication. The TX_BT and the configuration signal 212 may be
utilized with or instead of the control signal 210 to configure the
WLAN/Bluetooth coexistence antenna system 202 and to accommodate
for the separate TX and RX ports in the Bluetooth radio device
206.
[0044] In some instances, either the WLAN radio device 204 or the
Bluetooth radio device 206 may be disabled and the wireless
terminal may not operate in a coexistence mode. When the WLAN radio
device 204 is disabled, the Bluetooth radio 206 may configure the
WLAN/Bluetooth coexistence antenna system 202 via the configuration
signal 212 to support Bluetooth communication. When the Bluetooth
radio device 206 is disabled, the antenna controller 208 may
configure the WLAN/Bluetooth coexistence antenna system 202 to
support WLAN communication.
[0045] FIG. 3 is a timing diagram that illustrates an exemplary
communication of BT HV3 frames and WLAN transmissions based on the
TX_BT signal, in accordance with an embodiment of the invention.
Referring to FIG. 3, the Bluetooth radio device 206 may be adapted
to communicate Bluetooth packets supported by the synchronous
connection-oriented (SCO) logical transport. In this regard, the
Bluetooth radio device 206 may be adapted to communicate Bluetooth
(BT) HV3 packets. A BT HV3 packet may be generally used for 64 kb/s
speech transmission but need not be so limited. The BT HV3 packet
may comprise 30 information bytes with a payload length of 240 bits
and no payload header present. The bytes are not protected by
forward error correction (FEC) and no cyclic redundancy check (CRC)
is present. Because retransmission of BT HV3 packets is not
supported, when a BT HV3 packet is not received, the quality of the
overall transmission is reduced since the information contained in
the lost BT HV3 packet will not be retransmitted. As a result, BT
HV3 packets may require a higher priority of transmission to avoid
interference with WLAN transmission.
[0046] Referring back to FIG. 3, there is shown an exemplary timing
representation of BT HV 3 communication from a coexistence
terminal. The transmission of a pair of BT HV3 packets between a
station or terminal and a peripheral device is referred to as a BT
HV3 frame. A packet 302 may be transmitted from the station to the
peripheral device in time slot f(k) and a packet 304 may be
transmitted from the peripheral device to the station in time slot
f(k+1). A time slot in Bluetooth communication is 625 .mu.s in
duration and each time slot may correspond to a different frequency
in an adaptive frequency hopping (AFH) hopping sequence. A BT HV3
frame is 1.25 ms in duration. Transmission of BT HV3 packets from
the coexistence terminal may occur every sixth time slot or every
third BT HV3 frame. For example, a first packet may be transmitted
from the station during time slot f(k) and a next packet may be
transmitted from the station during time slot f(k+6). Similarly, a
first packet may be received by the station during time slot f(k+1)
and a next packet may be received by the station during time slot
f(k+7). As a result, no Bluetooth transmission may occur over a
period of two BT HV3 frames providing a WLAN transmission window of
2.5 ms.
[0047] As shown, the TX_BT signal 306 may be asserted during time
slots f(k) and f(k+1) and during time slots f(k+6) and f(k+7) to
provide priority transmission to the BT HV3 packets over WLAN
transmission. Asserting the TX_BT signal 306 may disable WLAN
transmissions in the WLAN radio device 204, for example. The WLAN
transmission window 308 illustrates a period of time between
assertions of the TX_BT signal 306 when the WLAN radio device 204
may transmit WLAN packets. In this example, the WLAN radio device
204 may transmit WLAN packets during time slots f(k+2) through
f(k+5) and during time slots f(k+8) through f(k+11).
[0048] FIG. 4 is a timing diagram that illustrates exemplary
assertion instances of the TX_BT signal, in accordance with an
embodiment of the invention. Referring to FIG. 4, there is shown a
BT HV3 frame 402, a first TX_BT signal 404, and a second TX_BT
signal 406. The first TX_BT signal 404 may be asserted prior to the
start of the BT HV3 frame 402 in order to provide firmware and/or
hardware in the WLAN radio device 204 with time to complete or
terminate a current WLAN packet transmission. The first TX_BT
signal 404 may be asserted within a guard time. This guard time may
range from just prior to the start of the BT HV3 frame 402 to 200
.mu.s to 250 .mu.s prior to the start of the BT HV3 frame 402. In
this regard, firmware and/or hardware in the WLAN radio device 204
may generate and/or store information regarding the completion or
termination of the current WLAN packet transmission. The WLAN radio
device 204 may utilize the information generated and/or stored to
resume WLAN packet communications after the first BT_TX signal 404
is deasserted.
[0049] In another embodiment of the assertion operation, the second
TX_BT signal 406 may be asserted immediately prior to the start of
the BT HV3 frame 402 in order to terminate a current WLAN packet
transmission by the WLAN radio device 204. This approach may be
utilized when, for example, the second TX_BT signal 406 may be
asserted on a pin that turns OFF a power amplifier utilized for
supporting WLAN packet transmissions in the WLAN radio device 204.
In this regard, firmware and/or hardware in the WLAN radio device
204 may generate and/or store information regarding the termination
of the current WLAN packet transmission. The WLAN radio device 204
may utilize the information generated and/or stored to resume WLAN
packet communications after the second BT_TX signal 406 is
deasserted.
[0050] FIG. 5A is a flow diagram that illustrates exemplary steps
for priority communication of BT HV3 traffic when utilizing a
predetermined guard time, in accordance with an embodiment of the
invention. Referring to FIG. 5A, after start step 502, in step 504,
a WLAN radio device, substantially as shown in FIGS. 2A-2D, may be
transmitting WLAN packets to an access point. When reception of a
transmitted WLAN packet is not acknowledged, the packet may be
retransmitted but the retransmission attempt may be backed off by
an exponentially growing time. When failure to receive a
transmitted WLAN packet results from, for example, interference
produced by the collocated Bluetooth radio device, exponentially
backing off the next transmission attempt may result in a reduced
transmission rate that may result in more interference from the
Bluetooth radio device. The Bluetooth radio device may be
substantially as shown in FIGS. 2A-2D. Moreover, because of the
periodicity of the BT HV3 frame, new transmission attempts may
occur at a time when the TX_BT signal is asserted, further delaying
the retransmission. These effects may result in a spiraling
condition where the retransmission of an unacknowledged WLAN packet
may be delayed sufficiently that the access point may consider the
station outside its range of operation. In this regard, for
coexistence operation of collocated WLAN and Bluetooth radio
devices, the exponentially growing retransmission backoff in the
WLAN radio device may be disabled.
[0051] In step 506, the WLAN radio device may determine whether the
Bluetooth radio device has asserted the TX_BT signal. When the
TX_BT signal has not been asserted, the WLAN radio device may
continue transmitting WLAN packets as in step 504. When the TX_BT
signal has been asserted, the WLAN radio device may proceed to step
508. In step 508, the WLAN radio device may complete transmission
of a current WLAN packet within the guard time provided by the
TX_BT signal before BT HV3 frame transmission is to occur. When the
current WLAN packet may not be transmitted within the guard time
provided by the TX_BT signal, then the WLAN radio device may
terminate transmission of the current WLAN packet and may
retransmit the current WLAN packet at the next available WLAN
transmission window. In step 510, the WLAN radio device may store
information regarding WLAN packet transmission status. For example,
the WLAN radio device may store information regarding whether the
current WLAN packet was completely transmitted or was terminated
and a future transmission attempt is necessary.
[0052] In step 512, the WLAN radio device may determine whether the
Bluetooth radio device has deasserted the TX_BT signal. When the
TX_BT signal has not been deasserted, the Bluetooth radio device
may still be transmitting BT HV3 traffic and the WLAN transmission
may remain disabled. When the TX_BT signal has been deasserted, the
WLAN radio device may proceed to step 514 and resume WLAN packet
transmission. In step 514, the WLAN radio device may resume
transmission of a terminated current WLAN packet or may transmit a
next WLAN packet if the current WLAN packet was transmission was
completed previously within the guard time provided by the TX_BT
signal. After step 514, the flow diagram 500 may proceed to end
step 516.
[0053] FIG. 5B is a flow diagram that illustrates exemplary steps
for priority communication of BT HV3 traffic when the TX_BT signal
is utilized to turn OFF a WLAN radio power amplifier, in accordance
with an embodiment of the invention. Referring to FIG. 5B, after
start step 522, in step 524, a WLAN radio device, substantially as
shown in FIGS. 2A-2D, may be transmitting WLAN packets to an access
point. The exponentially growing retransmission backoff in the WLAN
radio device may be disabled. In step 526, the WLAN radio device
may determine whether a collocated Bluetooth radio device,
substantially as shown in FIGS. 2A-2D, has asserted the TX_BT
signal. When the TX_BT signal has not been asserted, the WLAN radio
device may continue transmitting WLAN packets as in step 524. When
the TX_BT signal has been asserted, the WLAN radio device may
proceed to step 528. In step 528, the asserted TX_BT signal may
turn OFF a power amplifier in the transmission portion of the WLAN
radio device immediately terminating the transmission of a current
WLAN packet. In step 530, the WLAN radio device may store
information regarding, for example, scheduling a next transmission
attempt for the current WLAN packet during a next available WLAN
transmission window.
[0054] In step 532, the WLAN radio device may determine whether the
Bluetooth radio device has deasserted the TX_BT signal. When the
TX_BT signal has not been deasserted, the Bluetooth radio device
may still be transmitting BT HV3 traffic and the WLAN transmission
may remain disabled. When the TX_BT signal has been deasserted, the
WLAN radio device may proceed to step 534 and resume WLAN packet
transmission. In step 34, the WLAN radio device may resume
transmission of the terminated current WLAN packet. After step 534,
the flow diagram 520 may proceed to end step 536.
[0055] Regarding disabling the exponentially growing retransmission
backoff, when asserting the TX_BT signal during a station to access
point transmission and the WLAN packet transmission is interrupted
by turning OFF the WLAN radio amplifier, the WLAN radio device's
firmware may be adapted to detect the TX_BT signal in order to
update a state machine, for example, not to expect an
acknowledgement (ACK) from the access point. Otherwise, the WLAN
radio device may not have information indicating that an ACK was
not to be received in this instance and, in accordance with the
IEEE 802.11b/g specification, the WLAN radio device may
exponentially delay each retransmission attempt.
[0056] FIG. 5C is a flow diagram that illustrates exemplary steps
for modifying a WLAN fragmentation threshold based on a WLAN
modulation rate, in accordance with an embodiment of the invention.
Referring to FIG. 5C, after start step 542, in step 544, the WLAN
radio device may determine a packet fragmentation threshold to
enable transmission during the WLAN transmission window. A packet
for transmission control protocol (TCP) may be approximately 1500
bytes, for example. As shown in FIG. 3, the WLAN transmission
window is approximately 2.5 ms in duration. When the fragmentation
threshold for WLAN transmission is high, for example, higher than
1500 bytes, then all bytes in the TCP packet payload may be used in
the WLAN packet payload. Packets with a higher number of bytes
result in more efficient transmission. When the fragmentation
threshold for WLAN transmission is low, for example, 256 bytes or
lower, then several WLAN packets may be necessary to transmit the
TCP payload. While fewer bytes in a WLAN packet is less efficient,
when collisions occur, it may be more efficient to retransmit
shorter WLAN packets.
[0057] In order to guarantee that the WLAN packet is transmitted
within the 2.5 ms window, a WLAN radio device, substantially as
shown in FIGS. 2A-2D, may select the fragmentation threshold based
on the modulation rate of the WLAN link. For example, when the
fragmentation threshold is 256 bytes, a 2 Mbps modulation rate will
produce a WLAN packet of approximately 1 ms, which is well within
the WLAN transmission window between BT HV3 packet traffic. On the
other hand, when the fragmentation threshold is 1500 bytes, a 2
Mbps modulation rate will produce a WLAN packet of approximately 6
ms, which will not be completely transmitted within the WLAN
transmission window.
[0058] After step 544, a WLAN radio device may determine whether
the modulation rate in the WLAN link has changed. When the
modulation rate has not changed, the current fragmentation
threshold still provides for WLAN packet transmission within the
WLAN transmission window. When the modulation rate in the WLAN link
has changed, the WLAN radio device may proceed to step 548. In step
548, the WLAN radio device may modify the fragmentation threshold,
if necessary, to guarantee that a WLAN packet may be completely
transmitted within the WLAN transmission window. After step 548,
the flow diagram 540 may proceed to end step 550.
[0059] The invention provides a simple collaborative approach
between collocated WLAN and Bluetooth radio devices in a coexistent
terminal that achieves enhanced quality and higher throughput for
IEEE 802.11b/g and Bluetooth communication. This approach may be
applicable to a mobile station that handles at least a first
communication protocol and a second communication protocol, where
the first communication protocol may assert a priority signal to
disable the capabilities of the second communication protocol. The
capabilities of the second communication protocol may include, for
example, transmitting and receiving information. In this regard,
data for the first communication protocol may be transmitted when
the second communication protocol capabilities are disabled.
Disabling the capabilities of the second communication protocol may
be include, for example, turning OFF a transceiver or a power
amplifier.
[0060] Accordingly, the present invention may be realized in
hardware, software, or a combination of hardware and software. The
present invention may be realized in a centralized fashion in at
least one computer system, or in a distributed fashion where
different elements are spread across several interconnected
computer systems. Any kind of computer system or other apparatus
adapted for carrying out the methods described herein is suited. A
typical combination of hardware and software may be a
general-purpose computer system with a computer program that, when
being loaded and executed, controls the computer system such that
it carries out the methods described herein.
[0061] The present invention may also be embedded in a computer
program product, which comprises all the features enabling the
implementation of the methods described herein, and which when
loaded in a computer system is able to carry out these methods.
Computer program in the present context means any expression, in
any language, code or notation, of a set of instructions intended
to cause a system having an information processing capability to
perform a particular function either directly or after either or
both of the following: a) conversion to another language, code or
notation; b) reproduction in a different material form.
[0062] While the present invention has been described with
reference to certain embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the scope of the present
invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the present
invention without departing from its scope. Therefore, it is
intended that the present invention not be limited to the
particular embodiment disclosed, but that the present invention
will include all embodiments falling within the scope of the
appended claims.
* * * * *