USOO892.92.59B2
`
`(12) United States Patent
`Banerjee et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,929,259 B2
`Jan. 6, 2015
`
`(54) QUALITY OF SERVICE FOR WLAN AND
`BLUETOOTH COMBINATIONS
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(75) Inventors: Kaberi Banerjee, San Jose, CA (US);
`7/2008 Haartsen
`7.406,296 B2
`Gunnar Nitsche, Radebeul (DE)
`7,414,986 B2 * 8/2008 Kandala et al. ............... 370,310
`s
`7,508,781 B2 * 3/2009 Liu et al. ....................... 370,311
`7,899,396 B2
`3/2011 Meylan et al.
`(73) Assignee: NXP, B.V., Eindhoven (NL)
`2005/0271010 A1 12/2005 Capretta
`al. .......... 233
`(*) Notice:
`Subject to any disclaimer, the term of this S.E. A. : '83. St.
`eugels et al. ...
`past lSESlisted under 35
`2006/0274704 A1* 12/2006 Desai et al. ....
`370,338
`2006, O292986 A1* 12/2006 Bitran et al. ...
`.S.C. 154(b) by
`ayS.
`... 455,412
`2007/OOO2782 A1
`1/2007 Kinecktet al.
`2007/0066222 A1
`3/2007 Tao et al. ..................... 455,412
`2007/0177542 A1
`8, 2007 Hirsch
`2008/0101320 A1* 5/2008 Krahn et al. .................. 370,342
`2008. O144597 A1* 6, 2008 Chen ...... . . . . . .
`. . . . . . . . . . . . . . 370,345
`2010.0039973 A1
`2/2010 Cavalcanti et al.
`
`(21) Appl. No.: 13/453,706
`
`(22) Filed:
`
`Apr. 23, 2012
`
`(65)
`
`Prior Publication Data
`
`US 2012/O2O7143A1
`
`Aug. 16, 2012
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`WO
`
`1729 463 A1 12/2006
`2005/067212 A1
`7/2005
`OTHER PUBLICATIONS
`
`IEEE 802.15.2 part 15.2—Coexistence of Wireless Personal Area
`Networks With Other Wireless Devices . . . . 43 pgs. (2003).
`
`Related U.S. Application Data
`(62) Division of application No. 12/520,293, filed as
`application No. PCT/IB2007/055268 on Dec. 21,
`2007, now Pat No. 8.184,582
`s
`•
`L vs. 8 Y-s u Y- I sa- - 1-8
`(60) Provisional application No. 60/876,782, filed on Dec.
`(Continued)
`21, 2006.
`Primary Examiner — Jeffrey M. Rutkowski
`(51) Int. Cl.
`(57)
`ABSTRACT
`H04B 7/005
`HO47 (6/14
`A hybrid device includes both an IEEE-802.11e type WLAN
`HO4W 74/08
`client station (QAP) and a BLUETOOTH piconet unit inter
`(52) U.S. Cl
`connected such that the BLUETOOTH transmissions are
`AV e. we
`CPC .............. H04 W 16/14 (2013.01); Histo scheduled to occur according to a transmission opportunity
`(TXOP) that was granted by a quality of service (QoS) access
`point (QAP) in a basic service set (BSS). Requests for BLUE
`TOOTH traffic are handled by the associated QSTA which
`generates an add traffic service (ADDTS) to the QAP.
`
`(2006.01)
`(2009.01)
`(2009.01)
`
`USPC - - - - - - - - - - - r 370/278: 370/338; 455/450
`(58) Field of Classification Search
`USPC ......... 370/277 278, 328-330, 338, 345, 350:
`455/450 452.2
`See application file for complete search history.
`
`10 Claims, 4 Drawing Sheets
`
`120
`
`116
`
`118
`
`is
`BT *g, *g,
`NS) . A 584.”
`110^^
`WIRELESS
`106. MEDIUM
`
`IEEE-802.15.1
`BLUETOOTH
`2:402-2,480 GHz
`
`-
`
`z
`..TXOP
`5.725-5.850 GHz
`GEA
`AADDTS-129
`A DELTS.
`s
`
`
`
`132
`
`123
`
`BTTSPEC
`PARAMETERS
`
`103
`
`OCE
`AC
`
`CONTROL
`UNIT
`
`LINK MGMT
`SOFTWARE
`
`SUPPORTING
`APPLICATION
`SOFTWARE
`
`Uniloc Ex. 2001
`Microsoft v. Uniloc
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`US 8,929,259 B2
`Page 2
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`(56)
`
`References Cited
`
`OTHER PUBLICATIONS
`
`Godfrey, T., et al., GlobespanVirata “Making QoS a Reality over
`WLAN Connections,' retrieved from the Internet at www.eetimes.
`com/General/PrintView/4009268, 53 pages. (Dec. 2003).
`
`Singh, H., et al.; “Enhanced Power Saving in Next Generation Wire
`less LANs”, IEEE Veh. Techn. Conf. 2006, 5 pgs. (2006).
`
`International Search Report for European Patent Application PCT/
`IB2007/055268 (Dec. 21, 2007).
`
`* cited by examiner
`
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`U.S. Patent
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`Jan. 6, 2015
`
`Sheet 1 of 4
`
`US 8,929,259 B2
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`120
`
`116
`
`118
`
`PCONET
`
`BT
`
`39
`
`ESS
`
`9.4|st
`A IEEE 802. WAN
`y BIN
`2.400-2,4835 GHZ
`a
`<--TXOP /
`IEEE-802.15.1
`5.725-5.850 GHz
`GRANTED
`BLUETOOT
`-
`A. ADDTSN-129
`2:402-248O GHz
`\
`110 r- A DELIS->
`'s A.
`N
`c
`124
`/ v
`N
`
`Y
`\
`
`106 WRELESS
`- MEDIUM
`
`
`
`3
`12
`
`BTTSPEC
`PARAMETERS
`
`CONTROL
`UNIT
`
`LINK MGMT
`SOFTWARE
`
`SUPPORTING
`APPLICATION
`SOFTWARE
`
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`U.S. Patent
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`Jan. 6, 2015
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`Sheet 2 of 4
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`US 8,929,259 B2
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`2O2
`R
`
`802.11e PERIODC SUPERFRAME
`208
`
`210
`
`CFP (HCFPOLLSQSTAS
`BEACON
`OOSCF-POLL
`
`CONTENTIONPERIOD, EDCF AND POLLING THRUHCF
`QOS CF-POLL
`222
`
`HCFRAMES
`
`OSTA FRAMES
`206
`
`214
`RTS/CTS/DAIA/AC
`K(POLLED BYHC)
`
`220
`RTS/CTS/DAIA/AC
`K(AFTERDIFS)
`
`224
`RTS/CTS/DATA/AC
`K(POLLED BYHC)
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`
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`U.S. Patent
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`Jan. 6, 2015
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`Sheet 3 of 4
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`US 8,929,259 B2
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`g
`
`3O8
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`31 O
`
`312
`
`TARGET BEACON
`TRANSMISSION
`TIME (TBTT)
`314
`
`TARGET BEACON
`TRANSMISSION
`TIME (TBTT)
`
`
`
`302
`
`1
`
`SYNC EVENT
`TBTT, BT OFFSET
`
`FG. 3
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`U.S. Patent
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`Jan. 6, 2015
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`Sheet 4 of 4
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`US 8,929,259 B2
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`Ž?730NENDES ANSA
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`US 8,929,259 B2
`
`1.
`QUALITY OF SERVICE FOR WLAN AND
`BLUETOOTH COMBINATIONS
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a divisional of copending U.S. patent
`application Ser. No. 12/520,392, filedon Jun. 25, 2009, which
`is a 371 of international patent application PCT/IB2007/
`055268, filed on Dec. 21, 2007, which claims the benefit of
`U.S. provisional patent application No. 60/876.782, filed on
`Dec. 21, 2006.
`
`FIELD OF THE INVENTION
`
`This invention relates to wireless communications sys
`tems, and more particularly to co-located BLUETOOTH and
`WLAN devices that must share communication resource
`aCCCSS,
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`BACKGROUND
`
`2
`lision of needs to access the medium results in a larger num
`ber of retrials and corresponding inefficiencies.
`Some background in WLAN IEEE-802.11 developments
`would be helpful in understanding the present invention. Tim
`Godfrey, Globespan Virata, in a COMMSDESIGN article
`dated Dec. 19, 2003, explains that a hybrid coordination
`function (HCF) in the IEEE-802.11e Standard replaces the
`IEEE-802.11-legacy distributed coordination function
`(DCF) and point coordination function (PCF) in a quality of
`service (QoS) station (QSTA). See, Commdesign web site.
`The HCF includes two access mechanisms, an enhanced dis
`tributed channel access (EDCA), and an HCF controlled
`channel access (HCCA). The HCF defines a uniform set of
`frame exchange sequences that are usable at any time, and
`allocates rights to transmit with transmit opportunities (TX
`OPs) granted to QSTA’s through the channel access mecha
`nisms. Each TXOP grants a particular QSTA the right to use
`the medium at a defined point in time, and for a defined
`maximum duration. The allowed duration of TXOP's are
`communicated globally in the EDCA station beacon.
`The HCF introduced new acknowledgement (ACK) rules.
`Before, every unicast data frame required an immediate
`response with an ACK control frame. Now, HCF allows either
`no-acknowledgement, or block-acknowledgement, and
`which to use is specified in a QoS data frame control field. The
`no-acknowledgement is useful in applications with very low
`jitter tolerance, e.g., streaming multimedia, where retry
`delays would make the data unusable. Block-acknowledge
`ments can increase efficiency by aggregating the ACKs for
`multiple received frames into a single response.
`In EDCA, the contention window and backoff times are
`adjusted to favor higher priority classes gaining medium
`access. Eight user priority levels are available, and each pri
`ority is mapped to an "Access Category', which corresponds
`to one of four transmit queues. Each queue provides frames to
`an independent channel access function, each of which imple
`ments the EDCA contention algorithm. When frames are
`available in multiple transmit queues, contention for the
`medium occurs both internally and externally, based on the
`same coordination function. The internal scheduling
`resembles the external scheduling. Internal collisions are
`resolved by allowing frames with the higher priority to trans
`mit, while the lower priority frames are subjected to a queue
`specific backoff as if a collision had occurred.
`The minimum idle delay before contention, the minimum
`and maximum contention windows, and other parameters
`defining EDCA operation are stored locally by the QSTA.
`Such parameters can be different for each access category
`(queue), and can be individually updated for each access
`category by a QoS access point (QAP) through the EDCA
`parameter sets. The parameters are sent from the QAP as part
`of the beacon, and in probe and re-association response
`frames. The stations in the network can then be adjusted to
`changing conditions, and the QAP can manage the overall
`QoS.
`Under EDCA, stations and access points use the same
`access mechanism and contend on an equal basis at a given
`priority. A station that wins an EDCA contention is granted a
`transmit opportunity (TXOP), the right to use the medium for
`a period of time. The duration of each TXOP is specified per
`access category, and is included in the TXOP limit field of the
`access category (AC) parameter record in the EDCA param
`eterset. A QSTA can use a TXOP to transmit multiple frames
`within an access category.
`If a frame exchange sequence has been completed, and
`there is still time remaining in the TXOP, the QSTA can
`extend the frame exchange sequence by transmitting another
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`
`Hand held devices are now becoming a hub for personal
`communication and individual mobile computing needs. It is
`a centre for the convergence of multiple media types and
`multiple networking standards that are best Suited to transport
`a specific types of data.
`BLUETOOTH (IEEE-802.15.1 Industry Standard) and
`wireless local area network (WLAN) networking (IEEE
`802.11a/b/g Industry Standards) have been used extensively
`in hand-held personal communication devices. A Packet Traf
`fic Arbitration (PTA) algorithm for time division multiple
`access (TDMA) has been used quiet successfully to allow two
`networks, such as WLAN and BLUETOOTH, to be collo
`cated with sufficient throughput on both to support useful
`communication.
`But the throughput requirements of Such networks has
`been expanding in step with market needs. The throughput
`increases on each of the networks, means increased wireless
`medium traffic reservation periods, e.g., IEEE-802.11n for
`WLAN, and Extended Data Rate (EDR) extensions for
`BLUETOOTH.
`The PTA algorithm relies heavily on there being enough
`quite time in both networks to deliver whole frames without
`errors. However, the frequency and duration of quiet periods
`is reduced in advanced IEEE-802.11n networks. So, it
`becomes necessary for each network to recognize the
`medium reservation requirements of the other collocated net
`work.
`Typically, the PTA algorithm uses hardware signaling
`50
`methods to reserve the medium, either for WLAN or BLUE
`TOOTH traffic. Such reservation scheme presupposes that
`the WLAN Station will have a sufficient number and duration
`of quiet periods to allow asynchronous and isochronous
`BLUETOOTH traffic.
`However, new standards like the IEEE-802.11n allow
`aggregated frame transfers of MAC service and protocol data
`units. Such can result in a serious depletion of the number of
`available WLAN quiet periods. The WLAN medium access
`windows can be as long as a few milliseconds, especially with
`hand-held devices that operate at under 100 Mbps/second
`transfer rates.
`BLUETOOTH isochronous transfers need quiet periods
`that are at least 2.5 milliseconds long. It is getting increas
`ingly more difficult in newer devices to accommodate the
`error-free transfer of IEEE-802.11n frames while still sup
`porting BLUETOOTH traffic. The errors caused by the col
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`frame in the same access category. The QSTA must ensure
`that the transmitted frame and any necessary acknowledge
`ment can fit into the time remaining in the TXOP.
`the IEEE-802.11-type contention-based medium access is
`Susceptible to severe performance degradation when over
`loaded. In overload conditions, the contention windows
`become large, and more and more time is spent in backoff
`delays rather than sending data. Admission control in the
`IEEE-802.11e networks regulates the amount of data con
`tending for the medium.
`IEEE-802.11e is an enhancement of the IEEE-802.11a and
`IEEE-802.11b wireless LAN (WLAN) specifications. It
`offers quality of service (QoS) features, including the priori
`tization of data, voice, and video transmissions. The IEEE
`802.11a, IEEE-802.11b, and IEEE-802.11e standards are ele
`ments of the IEEE-802.11 family of specifications for
`wireless local area networks.
`IEEE-802.11e enhances the IEEE-802.11 Media Access
`Control layer (MAC layer) with a coordinated time division
`multiple access (TDMA) construct, and adds error-correcting
`mechanisms for delay-sensitive applications such as Voice
`and video. The IEEE-802.11e specification enables seamless
`interoperability and is especially well suited for use in net
`works that include multimedia capability. It supports high
`speed Internet access with full-motion video, high-fidelity
`audio, and Voice over IP (VoIP).
`IEEE-802.11e networks operate in two ranges, 2.400
`2.4835 GHz (the same as IEEE-802.11b networks), or 5.725
`GHz to 5.850 GHz (the same as IEEE-802.11a networks).
`There arc certain advantages to the higher frequency range,
`including faster data transfer speed, more channels, and
`reduced susceptibility to interference.
`The four basic parts of a BLUETOOTH system are a radio
`frequency (RF) unit, a baseband or link control unit, link
`management Software, and the Supporting application soft
`Wa.
`The BLUETOOTH radio is a short-distance, low-power
`radio operating in the unlicensed spectrum of 2.4-gigahertz
`(GHz). The radio uses a nominal antenna power of 0-dBm
`(1-mW) and has a range of 10 meters. Optionally, a range of
`40
`100 meters may be achieved by using an antenna power of
`20-dBm (100-mW). Data is transmitted at a maximum rate of
`one megabit per second. However, communication protocol
`overhead limits the practical data rate to about 721-Kbps.
`BLUETOOTH uses spectrum spreading, the transmission
`hops among seventy-nine different frequencies between
`2.402-GHz and 2.480-GHz at nominal rate of 1600-hops/s.
`Spectrum spreading minimizes interference from other
`devices in the 2.4-GHz band, such other wireless networks. If
`a transmission encounters interference, it waits 625-micro
`seconds for the next frequency hop and retransmits on a new
`frequency. Frequency hopping also provides data security
`because two packets of data are never sent consecutively over
`the same frequency, and the changing frequencies are pseudo
`random.
`The link controller handles all the BLUETOOTH baseband
`functions, e.g., encoding Voice and data packets, error correc
`tion, slot delimitation, frequency hopping, radio interface,
`data encryption, and link authentication. It also executes the
`link management Software.
`The IEEE-802.11e Standard defines a hybrid coordination
`function (HCF) used in the quality of service (QoS) enhance
`basic service set (QBSS). The HCF has two modes of opera
`tion, enhanced distributed channel access (EDCA) and HCF
`controlled channel access (HCCA). EDCA can support pri
`oritized traffic. EDCA is a contention-based channel access
`function, and HCCA is based on a polling mechanism, con
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`trolled by a hybrid coordinator (HC). The HC is co-located
`with the QoS enhanced access point (QAP). Both access
`functions enhance or extend functionality of the original
`IEEE-802.11 DCF and PCF access methods.
`Two other elements introduced by the IEEE IEEE-802.11e
`MAC are the access category (AC) and transmission oppor
`tunity (TXOP) in the HCF. The TXOP reserves an interval of
`time when a particular QoS enhanced client station (QSTA)
`has the right to make frame exchanges over the wireless
`medium. The TXOP can be obtained using the contention
`based channel access, e.g., an enhanced distributed access
`channel (EDCA) TXOP. The EDCA-TXOP is announced in
`the beacon frame transmitted by the QoS enhanced access
`point (QAP). The QSTA’s each contend for MCATXOP. The
`TXOP can also be granted by HCF controlled channel access
`(HCCA), it is a HCCA (polled) TXOP. The HCCA channel
`access method TXOP is included in the QoS poll frame trans
`mitted to a QSTA by the QAP when it polls the QSTA to start
`frame transmission. Once a QSTA gets the medium access
`right, it is allowed to transmit multiple frames during its
`exclusive time slot.
`Each station using the EDCA has four ACs, each with one
`transmit queue with an independent mechanism to contend
`for medium access. The four ACs have different priorities,
`and are intended for different kinds of traffic, e.g., back
`ground (AC BK), best effort (ACBE), video (ACVI), and
`voice (AC VO). The TXOP defines the starting time and
`maximum duration that a station may transmit frames.
`In the IEEE IEEE-802.11e Standard, when a QSTA has a
`traffic stream (TS) such as an audio-video (AV) stream to
`transmit, it sends an add TS (ADDTS) request to QAP to ask
`for transmission permission for the TS before starting trans
`mission. Such ADDTS request includes a traffic specification
`(TSPEC) which specifies the characteristics and QoS expec
`tations of the TS, e.g., TSID, data rate, data unit size, desired
`PHY rate, medium access method (EDCA or HCCA), etc.
`When the QAP receives the ADDTS request, it will evaluate
`the request in view of the TSPEC element, available band
`width, channel condition, network loading, etc. If the band
`width is available, the QAP will accept the request. The QAP
`transmits its decision with an ADDTS response to the
`requesting QSTA. If the request is accepted the QSTA shall
`start transmitting the TS. Otherwise, the QSTA shall not
`transmit the TS.
`Each AC has its own transmit queue and its own set of AC
`parameters. The differentiation in priority between AC is
`realized by setting different values for the AC parameters. The
`most important of which are, Arbitrary inter-frame space
`number (AIFSN). The minimum time interval between the
`wireless medium becoming idle and the start of transmission
`of a frame; Contention Window (CW). A random number is
`drawn from this interval, or window, for the backoff mecha
`nism; and, TXOP Limit, The maximum duration for which a
`QSTA can transmit after obtaining a TXOP. When data
`arrives at the MAC-UNITDATA service access point (SAP),
`the IEEE-802.11e MAC first classifies the data with the
`appropriate AC, and then pushes the newly arrived MSDU
`into the appropriate AC transmit queue. MSDUs from differ
`ent ACs contend for EDCA-TXOP internally within the
`QSTA. The internal contention algorithm calculates the back
`off, independently for each AC, based on AIFSN, contention
`window, and a random number. The backoff procedure is
`similar to that in DCF, and the AC with the smallest backoff
`wins the internal contention. The winning AC would then
`contend externally for the wireless medium. The external
`contention algorithm has not changed significantly compared
`to DCF, except that in DCF the deferral and backoff were
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`constant for a particular PHY. IEEE-802.11e has changed the
`deferral and backoff to be variable, and the values are set
`according to the appropriate AC. With proper tuning of AC
`parameters, traffic performance from different ACs can be
`optimized and prioritization of traffic can be achieved. This
`requires a central coordinator (QAP) to maintain a common
`set of AC parameters to guarantee fairness of access for all
`QSTA within the QBSS. Also in order to address the asym
`metry between uplink (QSTA to QAP) and the much heavier
`10
`downlink (QAP to QSTA) traffic, a separate set of EDCA
`parameters is defined for the QAP only, which takes this
`asymmetry into account.
`The traffic specification (TSPEC) is the traffic stream man
`agement device provides the management link between
`higher layer QoS protocols such as IntSery or DiffSery with
`the IEEE-802.11e channel access functions. TSPEC
`describes data rate, packet size, delay, and service interval.
`TSPEC negotiation between peer MAC layers provides the
`mechanism for controlling admission, establishment, adjust
`ment and removal of traffic streams. Traffic stream admission
`control is especially important since there is limited band
`width available in the wireless medium. Bandwidth access
`must be controlled to avoid traffic congestion, which can lead
`to breaking established QoS and drastic degradation of over
`all throughput. The IEEE-802.11e standard specifies the use
`of Traffic Specification (TSPEC) for such a purpose for both
`EDCA and HCCA.
`QoS management frames, primitives, and procedures are
`defined for TSPEC negotiation, which is always initiated by
`the station management entity (SME) of a QSTA, and
`accepted or rejected by the HC. Requested TSPEC is com
`municated to the MAC via the MAC layer management entity
`(MLME) SAP. This allows higher layer SW, protocols, and
`application, such as RSVP, to allocate resources within the
`MAC layer.
`Admission control is negotiated by the use of a TSPEC. A
`station specifies its traffic flow requirements (data rate, delay
`bounds, packet size, and others) and requests the QAP to
`40
`create a TSPEC by sending the ADDTS (add TSPEC) man
`agement action frame. The QAP calculates the existing load
`based on the current set of issued TSPECs. Based on the
`current conditions, the QAP may accept or deny the new
`TSPEC request. If the TSPEC is denied, the high priority
`access category inside the QSTA is not permitted to use the
`high priority access parameters, but it must use lower priority
`parameters instead. Admission control is not intended to be
`used for the “best effort' and “background traffic classes.
`50
`What is needed is a system that allows WLAN client sta
`tions (STAs) to recognize and declare the needs of BLUE
`TOOTH traffic as one of the supported traffic streams to the
`Access Point of the WLAN network, and thus reserve
`medium time for BLUETOOTH traffic.
`
`6
`An advantage of the present invention is the co-interfer
`ence that would otherwise be associated with a hybrid device
`combining WLAN and BLUETOOTH devices is reduced or
`totally eliminated.
`Another advantage of the present invention is a method is
`provided for making error-free BLUETOOTH data transfers
`in the presence of WLAN devices.
`A still further advantage of the present invention is a wire
`less device is provided for efficient use of its radio medium.
`An advantage of the present invention is a method is pro
`vided that allows a WLAN STA to reserve medium time for a
`collocated BLUETOOTH traffic stream. The WLAN STA
`asks an Access Point of the WLAN network to accommodate
`the BLUETOOTH traffic as if it were a supported traffic
`Stream.
`The above summary of the present invention is not
`intended to represent each disclosed embodiment, or every
`aspect, of the present invention. Other aspects and example
`embodiments are provided in the figures and the detailed
`description that follows.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention may be more completely understood in con
`sideration of the following detailed description of various
`embodiments of the invention in connection with the accom
`panying drawings, in which:
`FIG. 1 is a functional block diagram of a hybrid WLAN and
`BLUETOOTH wireless device embodiment of the present
`invention;
`FIG. 2 is a diagram showing how BLUETOOTH wireless
`media accesses are scheduled into the IEEE-802.11e super
`frames using transmit opportunity (TXOP) grants from the
`access point,
`FIG. 3 is a timing diagram showing how a target beacon
`transmission time and offset communicated in a management
`frame can be used to synchronize otherwise independent
`BLUETOOTH and WLAN activity; and
`FIG. 4 is a timing diagram showing how a BLUETOOTH
`master/slave can be allowed to be active while a collocated
`local WLAN QSTA is being silent in its cooperation with a
`scheduled PSMP sequence that involves other QSTA’s.
`While the invention is amenable to various modifications
`and alternative forms, specifics thereof have been shown by
`way of example in the drawings and will be described in
`detail. It should be understood, however, that the intention is
`not to limit the invention to the particular embodiments
`described. On the contrary, the intention is to cover all modi
`fications, equivalents, and alternatives falling within the spirit
`and Scope of the invention as defined by the appended claims.
`
`DETAILED DESCRIPTION
`
`In FIG. 1, a single wireless hand-held device embodiment
`of the present invention, referred to herein by the general
`reference numeral 100, comprises a wireless local area net
`work (WLAN) client station (QSTA) 102 with a media access
`control (MAC) 103 that is collocated with a BLUETOOTH
`(BT) device 104. Both independent wireless networks must
`share a wireless medium 106.
`The WLAN QSTA 102 conforms to the IEEE-802.11e
`industry standard and therefore operates in the 2.400-2.4835
`and 5.725-5.850 GHz radio spectrum over a radio link 108.
`The BT device 104 conforms to the IEEE-802.15.1 industry
`standard and therefore operates in the 2.400-2.480 GHz radio
`spectrum over a radio link 110. Their collocation with each
`other and overlapping frequencies of operation predisposes
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`SUMMARY OF THE INVENTION
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`In an example embodiment, a hybrid wireless device
`includes both a IEEE-802.11e type WLAN client station
`(QAP) and a BLUETOOTH piconet unit interconnected such
`that the BLUETOOTH transmissions are scheduled to occur
`according to a transmission opportunity (TXOP) that was
`granted by a quality of service (QoS) access point (QAP) in a
`basic service set (BSS). Requests for BLUETOOTH traffic
`are handled by the associated QSTA which generates an add
`traffic service (ADDTS) to the QAP.
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`them to mutual interference when they try to simultaneously
`access the wireless medium 106. If they do collide, backoff
`procedures are used to get a clear channel, and Such backoff
`periods waste time that could be used exchanging data.
`Potential co-interference between a WLAN basic service
`set (BSS) 112 and a BLUETOOTH piconet 114 is more
`organized because it is controlled and limited. Admission
`controls inherent in the IEEE-802.11e industry standard are
`used to effectively reserve time slots in which the BSS 112
`network will be quiet so the BT piconet 114 can confidently
`access the wireless medium 106 and make error-free
`dataframe transfers. In FIG. 1, BSS 112 includes a QoS
`access point (QAP) 116 and a hybrid controller (HC) 118, and
`BT piconet 114 includes a master/slave 120.
`When BT device 104 needs to send some traffic to the
`piconet 114, it issues a request-to-send (RTS) 122 to the
`QSTA 102. A set of BLUETOOTH traffic specification
`parameters (BT-TSPEC) 123 is stored in the QSTA 102.
`An add traffic stream (ADDTS) 124 is transmitted over
`WLAN radio link 108 to the QAP 116. If the priority and
`access can be accommodated, a transmit opportunity (TXOP)
`126 is returned to the QSTA 102. A clear-to-send (CTS) 128
`is sent to the BT device 104 and it can thereafter transmit BT
`signals in the reserved times. The BSS 112 will be quiescent
`to allow the BT traffic.
`A conventional IEEE-802.11e delete traffic stream
`(DELTS) 129 request frame is communicated to the QAP116
`to teardown the BLUETOOTH access. The next BLUE
`TOOTH traffic is then established with another ADDTS 124
`and corresponding TXOP 126.
`In BT piconet 114, a baseband resource manager is respon
`sible for BT access to the radio medium 106. The baseband
`resource manager grants time on the physical channels to all
`of the entities that have negotiated an access contract. It also
`negotiates access contracts that are commitments to provide a
`user application with an expected performance. The access
`contract and scheduling function control the use of the
`BLUETOOTH radio, e.g., the normal exchange of data
`between connected devices over logical links, and logical
`transports, as well as the use of the radio medium to carry out
`inquiries, make connections, be discoverable or connectable,
`or to take readings from unused carriers during the use of
`adaptive frequency hopping mode. Sometimes, the schedul
`ing of a logical link results in changing to a different physical
`channel from the one that was previously used, e.g., due to
`involvement in a scatternet, a periodic inquiry function, or
`page scanning. When the physical channels arc not time slot
`aligned, the resource manager also accounts for the realign
`ment time between slots on the original physical channel and
`slots on the new physical channel.
`A BT link controller is responsible for the encoding and
`decoding of BLUETOOTH packets from the data payload
`and parameters related to the physical channel, logical trans
`port and logical link. The link controller carries out the link
`control protocol signaling, in conjunction with the scheduling
`function of the resource manager. A radio frequency (RF)
`block 130 is responsible for transmitting and receiving pack
`ets of information on the physical channel. A baseband con
`trol allows baseband control of the timing and frequency
`carrier of the RF block 130. The RF block 130 transforms data
`streams between the physical channel and the baseband into
`the required formats.
`The responsibility of allocating TXOP's 126 is that of the
`QAP 116. The QAP 116 determines if each requested TXOP
`126 time can be allocated to the requesting QSTA 102. Once
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`allocated, the method used by STA’s like QSTA 102 to grab
`the medium 106 and use its amount of TXOP 126 is a part of
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`the QoS facility defined in IEEE-802.11e Standard. It is not
`guaranteed that other STA’s in the BSS 112 can or will
`monitor the TXOP 126 allocation of a specific QSTA 102 in
`the BSS 112.
`Once allocated a TXOP 126 for the BT piconet 114, the
`QSTA 102 (really BT device 104) must adhere to its bound
`aries. The QAP 116 can note any violations and take correc
`tive action against the offending QSTA 102, but such action is
`not described or mandated by the standard. The QSTA 102 or
`the QAP 116 has the added responsibility of reserving the
`medium so that any other STA’s in the BSS 112 know of the
`TXOP 126 reservations. These are explicit actions defined by
`the Standard.
`Although other STA’s do not necessarily monitor the issu
`ing of TXOP's 126, they do receive notification that a certain
`duration has been reserved for a QSTA, and each observes the
`appropriate boundaries of the reservation by not transmitting
`during the relevant time period.
`The local QSTA 102 has an RF stage in its PHY layer 132
`that has to be squelched off during the time the BT device 104
`is being allowed to access radio medium 106. The QSTA 102
`RF has to be squelched off so its WLAN link 108 carriers
`don’t interfere with the BT link 110. By transmitting a sched
`ule for the BT traffic, the QSTA 102 makes sure that the QAP
`116 also does nothing towards the QSTA 102 during the BT
`TXOP 126. It will itself only allow BT traffic during this quiet
`period. The BT transmission power levels will not typically
`interfere with BSS transmissions in other parts of the BSS
`112. The BT traffic therefore does not depend on blocking
`other QSTA’s in the BSS 112. The QSTA 102 with the BT
`port only needs to block the QAP 116 from transmitting
`WLAN traffic to itself, and it must not transmit any WLAN
`traffic during the times reserved to the BT described in the
`TXOP 126. In this case, nothing else need be known to the
`other QSTA's in the BSS. A specific scheduled TXOP can be
`given by the QAP 116 to the QSTA 102, e.g., by a RTS/CTS
`reservation mechanism. The QSTA 102 can then become
`quiet to allow the BT piconet 114 to take over.
`FIG. 2 represents a data exchange format embodiment of
`the present invention useful in wireless hand-held device 100,
`and is referred to herein by the general reference numeral 200.
`Format 200 uses an IEEE-802.11e superframe 202 with HC
`frames 204 and QSTA frames 206. These are respectively
`transmitted, e.g., by QAP 116 and QSTA 102 in FIG.1. The
`superframe 202 has a first part, a contention free period (CFP)
`208, wherein a hybrid coordination function (HCF) polls the
`QSTA's. A second part, a contention period (CP) 210 pro
`vides for EDCF a