I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll llllll llll llll llll
`
`US00703 l274B2
`
`(12) United States Patent
`Sherman
`
`(I O) Patent No.:
`(45) Date of Patent:
`
`US 7,031,274 B2
`Apr. 18, 2006
`
`(54) METHOD FOR ENABLING
`INTEROPERABILITY BETWEEN DATA
`TRANSMISSION SYSTEMS CONFORMlNG
`TO rEEE 802.11 ANO IUPERLAN
`STANDARDS
`
`(75)
`
`Inventor: Matthew J. Sherman, Succasunna, NJ
`(US)
`
`(73) Assignee: AT&T Corp., New York, NY (US)
`
`( *) Notice:
`
`Subject to any discla imer, the tem1 of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 739 days.
`
`(21) Appl. No.: 10/045,980
`
`(22) Filed:
`
`Jan. 1, 2002
`
`(65)
`
`Prior Publication Data
`
`US 2003/0161279 Al
`
`Aug. 28, 2003
`
`Related U.S. Application Data
`
`(60)
`
`Provisional application No. 60/261 ,935, filed on Jan.
`16, 2001.
`
`(51)
`
`Int. Cl.
`H04J 3100
`
`(2006.0 1)
`
`(52) U.S. Cl. ...................... 370/321 ; 370/337; 370/341 ;
`370/347; 370/442; 370/458; 370/462; 455/450
`
`(58) Field of Classification Search ................ 370/310,
`370/321, 337, 338, 341, 347, 43 1, 442,443,
`370/456, 458, 461 , 462, 433; 455/422.1 ,
`455/450, 451. 452.1, 452.2
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`8/ 1999 Schroeder et al.
`5,933. lll A
`9/ 1999 Chang et al ................ 455/423
`5.956.638 A •
`3/200 1 Hulyalkar el al. ....... 370/3 10. l
`6. 198,728 B l •
`2002/0114303 Al*
`8/2002 Crosbie et al. . ............ 370/338
`6/2004 Carter et al ................. 370/338
`2004/0109429 Al•
`7/2004 Taxerma.n et al. . ......... 370/466
`2004/014 1522 A L*
`
`FOREIGN P.A:rENT DOCUMENTS
`l lll 843 A2
`6/2001
`
`EP
`
`OTHER PUBLJCATIONS
`U.S. Appl. No. 60/223,993, filed Aug. 2000, Texennan. *
`U.S. Appl. No. 60/230,4 12, filed Sep. 2000, Texerman. *
`Lin et al, " Enhanced Channel Access Meehan.ism for QoS(cid:173)
`driven homePNA (HPNA 2.1)" U.S. Appl. No. 60/269,354,
`filed Feb. 2001.
`
`(Continued)
`
`Primary Examiner- Steven Nguyen
`Assis/an/ Examiner- Roberta Shand
`(74) Attorney, Agent, or Firm- Michael Haynes PLC
`
`(57)
`
`ABSTRACT
`
`Mechanisms, in a transmission channel shared by 802.11
`systems and HIPERLAN/2 systems are provided to prevent
`802. l l term inals from trausmitting during ti me periods
`allocated to HIPERLAN, so that a single channel can be
`shared between the two standards. In a particular embodi(cid:173)
`ment, a "super frame" format is used where HIPERLAN
`translllissious are offered the h ighest level of protection
`possible within 802. I I, which is needed wiU1in the 802.ll
`Contention Free Period (CFP).
`
`15 Claims, 2 Drawing Sheets
`
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`

`US 7,031,274 B2
`Page 2
`
`OTE-IER PUBLICATIONS
`
`Lin et al., " Enhanced Channel Access Mechanisms for an
`HPNA Network", U.S. Appl. No. 10/042,142, filed Jan. JJ ,
`2002.
`Lin et al., "Enhanced Channel Access Mechanisms for an
`HPNA Network". U.S. Appl. No. 10/042, 143, filed Jan. JJ ,
`2002.
`Lin et al., " Enhanced Channel Access Mechanisms for an
`HPNA Network", U.S. Appl. No. 10/042,165. filed Jan. 11,
`2002.
`Lin et al., " Enhanced Channel Access Mechanisms for an
`HPNA Network", U.S. Appl. No. 10/042,179. filed Jan. 11 ,
`2002.
`
`Lin et al., " Enhanced ChallJ1el Access Mechru1isms for an
`HPNA Network", U.S. Appl. No. 10/042,166, filed Jan. 11 ,
`2002.
`Ghassemzadeh et al., "A Method for Whitening Spread
`Spectnuu Codes", U.S. Appl. No. 09/875,767, filed Jun. 6,
`2001.
`Britz et al., "Metropolitan Networks Based on Fiber and
`Free Space Access Distribution Method". U.S. Appl. No.
`09/98 J ,240, filed Oct. 18, 200 l.
`Britz et al., "Metropolitan Networks Based on Fiber and
`Free Space Access Distribution System", U.S. Appl. No.
`09/978,581 , filed Oct. 18. 2001.
`
`" cited by examiner
`
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`

`U.S. Patent
`
`Apr. 18, 2006
`
`Sheet 1 of 2
`
`US 7,031,274 B2
`
`Fig.I
`
`Fig.2
`
`201
`
`203
`
`.___~__.TO/FROM
`DATA SOURCE
`
`STATION/ ACCES PORT
`
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`

`U.S. Patent
`
`Apr. 18, 2006
`
`Sheet 2 of 2
`
`US 7,031,274 B2
`
`Fig.3
`
`PRIOR ART
`
`n x 2 ms
`
`m x 2 ms
`
`I ... 2 ms ·I
`Super frame of length 2 k x 2 ms
`
`BEACON
`
`Fig.4
`n x 2 ms
`m x 2 ms
`e il/lfi!l:I!!B.i!lll!!!)l! x llM@f Hf.#M: · · • llM!if.~: e :)::};taozt:1!:luttn;;rrt
`I ... 2 ms ·I
`Spoofing Frame
`BEACON
`
`. ............................ .
`
`..............................
`
`Super frame of length 2 k x 2 ms
`
`Fig.5
`
`Cf P max Length
`
`--TBTI
`
`802.11 a NAV Reset
`
`i0
`
`PCF
`
`2 ms
`
`I x 2 ms
`
`m x 2 ms
`
`n x 2 ms
`
`Super frame of length 2 k x 2 ms
`B = Beacon
`......... HIPERLAN/2 formats
`E = er _End
`::c',WN, 802.11 r ormats
`X = Blocking or Spoofing
`802.11 Management F romes
`Optional 802.11 Management r romes
`r rome Sequence
`Potential frames from Prior DCF
`
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`US 7,031,274 B2
`
`1
`METBOD FOR ENABUNG
`[NTEROPERABILITY BETWEEN DATA
`TRANSMISSION SYSTEMS CONFORMING
`TO IEEE 802.11 AND HIPERLAN
`STANDARDS
`
`This application claims priority of provisional application
`No. 60/261.935 filed Jan. 16. 2001.
`
`2
`This method of facilitating interoperability of HIPER(cid:173)
`LAN and 802.lla has some drawbacks. For one, this
`approach presumes that the 802.11 terminals can be pre(cid:173)
`vented from transmitting during the HIPERLAN operating
`5 phase. Currently, no mechanism exists within tbe 802.1 1
`standard to allow this. Also, the problem is best addressed by
`a solution compatible with existing generations of terminals.
`
`SUMMARY OF THE INY ENTJON
`
`FJ ELD OF TH E INVENT10N
`
`10
`
`This invention relates to data transmission systems and to
`their controlling operating standards. It is also concerned
`with wireless local area networks (WLAN) and with allow(cid:173)
`ing operability between two standards and in particular to
`interoperability between 802.lla standards and HIPERLAN
`standards.
`
`BACKGROUND OF THE TNVENTJON
`
`Mechanisms, in a transmission channel shared by 802.l J
`systems and HJPERLAN/2 systems are provided in accord
`with the invention to prevent 802.11 terminals from trans(cid:173)
`mitting during time periods allocated to HIPERLAN, so that
`15 a single channel can be shared between the two standards. In
`a particular embodiment, a "super-frame" format is used
`where HIPERLAN transmissions are offered the highest
`level of protection possible within 802.11, which is provided
`within the 802.J I Contention Free Period (CFP).
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`FIG. 1 is a schematic of WLAN systems where interop(cid:173)
`er<1bili1y is desirable;
`FIG. 2 is a block schematic of a wireless station or access
`point used in the WLANS;
`FIG. 3 is a graph of transmission states in the channels of
`a WLAN in one previously proposed solution concerning
`interoperability;
`FIG. 4 is a graph of a proposed superframe structure of a
`contention arrangement for permitting
`iuteroperability
`between 802.lla WLANS and HIPERLAN WLANS;
`FIG. 5 is graph of an alternative proposed superframe
`strucn1re of a contention arrangement for permitting interop(cid:173)
`erability between 802.Jla WLANS and HIPERLAN
`WLANS.
`
`DETAILED DESCRIPTION
`
`20
`
`35
`
`Wireless data transmission is a rapidly growing field. One
`increasingly popular form of such transmission is wireless
`local areas networks (WLANs). A number of standards
`currently exist for WLANs. However, they tend to be
`fragmented and largely incompatible. There is a desire for a 25
`worldwide standard that would allow a single device to
`ftmction virtually anywhere in the world providing high(cid:173)
`speed corn1ectivity.
`WLANs require specific protocols to transmit infonna(cid:173)
`tion, as do wired LANs. With numerous stations along a 30
`network, LAN stations must take care to prevent collisions
`if more than one station wishes to transmit information in the
`LAN. The s.ituation is more critical iu the wireless environ(cid:173)
`ment (i.e .. WLANs) since wireless stations and wireless
`access points behave differently from wired stations.
`Recently, bands have opened up between 5 and 6 GHz,
`wbicb may penuit a worldwide standard. Wireless standards
`are being developed to utilize those bands. One such stan(cid:173)
`dard is HIPERLAN/2 (High Performance Radio Local Area
`Network Type 2), which is of European origin. Another such 40
`standard is IEEE 802.lla, which originates primarily in the
`US. Japan is developing standards similar to both those in
`the US and Europe. Both tl1e US and European standards
`profess similar levels of performance, and use very similar
`waveforms to communicate. However, the two standards are 45
`currently incompatible-Particularly at the Media Access
`Control (MAC) layer. As such, a large push bas developed
`to create a single hybrid standard, or provide some means for
`the two standards to easily interoperate.
`Many situations occur where 802. l la WLANs must sub- 50
`stantially coexist with HIPERLAN WLANs. Since they
`operate at overlapping frequencies, contention collisions are
`frequent and must be resolved if the two systems are to
`operate without interference in close proximity to each
`other.
`Methods for interoperation of HIPERLAN and 802.lla
`systems are heiug contemplated in which systems conform(cid:173)
`ing to both standards might share one common channel
`without interference. A super-frame structure has been pro(cid:173)
`posed to support interoperation between the standards. The 60
`proposed struct1tre contemplates a super frame witl1 an
`802.Jl phase and a HIPERLAN/2 phase (See super-frame
`structure shown in FIG. 3). The super frame has a length of
`2kx2 ms, where k is an integer. Duration of the 802.11
`beacon plus the 802.lla phase is set at nx2 ms. The 65
`HIPERLAN/2 phase comprises mx2 ms. The smn of m and
`n would he 2k.
`
`WLANs are essentially a wireless replication of a wired
`LAN and in many ways operated in substantially the same
`manner. There are important differences that must be accom(cid:173)
`modated. A wireless node is unable to listen while it is
`transmitting and wireless media are more likely to contain
`noise and interference than are wired media. Additionally
`some tenninals remain hidden to other 1em1inals even
`though both may access a particular network. Hidden ter(cid:173)
`minals coupled with an inability of a transmitting terminal to
`listen may result in collisions as more than one terminal may
`transmit in tl1e same lime interval.
`Standards have evolved to avoid such collisions in
`WLANs. 802.11 is one standard in use in North America and
`has probable use in Europe and other areas in the world.
`55 HIPERLAN is a similar standard for WLANs used in parts
`of Europe and potentially in North America. l'l is not
`unexpected that in some areas there may exist a net.xi to
`interoperate 802.11 and HIPERLAN/2 systems. Both stan-
`dards operate in a frequency range that is overlapping hence
`m1less steps are taken to prevent collisions tbey wi ll likely
`occur.
`A typical WLAN arrangement is shown in the FIG. 1
`wherein several WLANs 101, 103 and 105 which may
`overlap are shown in close proximity to one another. Each
`WLAN includes a plurality of stations 111, 113 and 115
`througl1 wl1ich messages may be sent to and received from
`that particular WLAN 101 , 103 and 105. Eacb WLAN
`
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`

`US 7,031,274 B2
`
`3
`includes couneclion to au access port (AP) 112, 114 and 116,
`which permits communication between WLANs.
`WLANs are accessed through stations that operate as the
`access ports (AP) 112, ll4 and 116. AP's provide commu(cid:173)
`nications with services and stations outside the immediate 5
`set of wireless stations with which it conummicates. The
`service "behind" the AP is termed the Distribution Service
`(DS) in 802.1 l. Stations in systems using either or both
`802.1 l and l-llPERLAN/2 protocols should accommodate
`both. Due to the wireless nature of the WLAN, ordinary 10
`stations need not support both systems although such abili(cid:173)
`ties would be desirable since it is most likely that common
`frequencies will be shared. It is clearly desirable that theAPs
`support both standards (i.e., with a hybrid AP (HAP)).
`AJ1 illustrative example of a station/access port 201 is 15
`shown in the FIG. 2 and includes a wireless antenna 203, a
`radio signal processing component 205, and a data process(cid:173)
`ing component 207. The data processing component
`receives data entered from a computer unit and transmits
`received data from the radio unit to a computer unit of the 20
`WLAN. The STA/AP may take many varied forms known to
`those skilled in the art and hence need not be disclosed in
`detail.
`Some prior solutions to the problem of collisions between
`competing systems sharing a coulluOn frequency band have
`relied on a spoofing technique to spoof tenuinals into
`thinking that the media was busy during a time period
`identified by a duration field defined by the 802.11 standard.
`802. 1 l STAs have a mechanism called the Network Allo(cid:173)
`cation Vector (NAY) that can be set to prevent the STA from
`transmitting. However, the NAY is set only under very
`specific conditions that do uot exist at the time the HIPER(cid:173)
`LAN/2 frames need to seize the medilu11. Many existing
`STA ca1u1ot be modified to set the NAY based on the
`detection of HIPERLAN/2 transmissions. A network allo(cid:173)
`cation vector (NAY) normally is set to indicate that a media
`is busy even if no signal is detected. Hence setting of the
`NAY may be used to inhibit m1wanted transmissions in cases
`where they might interfere with other transmissions that are
`undetectable to the potentially interfering station. Possible
`spoofing frames/frame sequences that could be usefol
`include a CTS transmitted by an AP, a data frame transmitted
`by au AP, an RTS trans111i11ed by ru1 AP fo llowed by a CTS
`from a station, the prior RTS/CTS combination followed by
`an additional CTS frame from the AP, or the prior RTS/CTS
`combination followed by a data frame. Other frame
`sequences can also be used with this regard.
`In the system shown in FIG. 3, there is no provision to set
`a NAY to properly cover HIPERLAN/2 transmissions. The
`solution, shown in FIG. 3, discloses a prior super-frame
`proposal. Tue problem is that there is nothing in the proposal
`that would force 802. Ila STA to cease transmissions during
`the HIPERLAN phase oflhe Superframe. The 802.1 la STA
`would view the HIPERLAN phase as a part of the 802.11
`Contention Period (CP), and would normally be free to
`transmit during the CP.
`A modified solution such as shown iu the FIG. 4 allows
`a HAP to transmit a spoofing frame with a duration field set
`to protect transmissions from HIPERLAN/2 stations. The
`modified system requires no changes to any legacy (old 60
`existing type) STA.
`In accord with principles of the invention, a Super-frame
`stnicture, shown in FIG . 5 depicting signals of both stan(cid:173)
`dards, in a channel, is disclosed herein that allows 802.lla
`stations (STA and AP) to share a single channel with 65
`l-llPERLAN/2 stations. l-llPERLAN/2 transmission occurs
`within the [l)PERLAN/2 phase that is bu1ied within the
`
`4
`Contention Free Period (CFP) of 802.1 1. Tue CFP occurs
`with a regular period, aud all 802.11 terminals set their
`NAV's during the CFP. To realize such a super frame the
`following sequence of frames/phases can be used as shown
`iu the graph of FIG. 5.
`CFP _Beacon, 802. I I Broadcast, 802. I I CFP, HIPER(cid:173)
`LAN/2 phase, CF _End, 802.1 l CP
`Here, CFP _Beacon is a Beacon starting a CFP. Not all
`Beacons need start a CFP. However, the CFP must recur
`every integral number of Beacons. The inference is ilJat the
`Beacon period must be a sub multiple of the super frame size
`(which is still 2k time 2 msec). For the method of FIG. 5,
`three phases exist. A phase here means a collection of frames
`primarily controlled by a conuuon coordination or access
`functiou. 'foe first phase would consist of the CFP _Beacon,
`802.11 Broadcast, and 802.11 CFP. Tue sum time occupied
`by this phase is an integral number times 2 msec, and that
`number is specified as 1 for this illustrative example. Also
`note that the tem1 "Broadcast" here is used in a generic
`nature meaning Broadcast and Multicast frames. 111e HIP(cid:173)
`ERLAN/2 phase would remain at n times 2 msec, and the
`CF 13 End, 802.11 CP would have to be m times 2 msec. The
`sum l+m+n must be 2k. Note that from an 802. 11 perspec(cid:173)
`tive, all transmissions from the CFP _Beacon to the CF _End
`25 (including those from BlPERLAN stations) would be con(cid:173)
`sidered as the 802.11 CFP. While the AP would restrict all
`CFP data transmissions to occurring in the first "Phase" of
`the superfouue, the 802. 11 stations operating in this strnc(cid:173)
`ture would be unaware of the "Phases" and would only see
`30 one large CFP, with part of it full of undetectable transmis(cid:173)
`sions (the HIPERLAN/2 transmissions).
`FIG. 5 is meant to be illustrative of the advantages of
`nesting the E-JIPERLAN/2 phase witl1in the CFP, rather than
`the CP. 11 represents the most limiting iuterprelation of the
`35 existing 802.11-1999 standard, and most restrictive CFP
`scheduling ndes. Depending on the flexibility available
`within the 802.11 system, other orderings of the phases
`under the CFP may be possible, and would be within the
`spirit of this invention. Such orderings would have various
`40 advantages and disadvantages.
`The key issue is support for 802.11 Power Saving (PS)
`stations. These statious spend as much of their time as
`possible in the "dose" stale, where they cannot receive or
`transmit frames, but consume little power. They awake
`45 every so many Beacon Intervals (the time between Beacons)
`to see if there is are any pending frames for them. The
`Beacon frame contains a Delivery Traffic Indication Mes(cid:173)
`sage (DT1M) element when any associated 802.1 J stations
`are in PS mode. The 802.11 stations indicate to the AP how
`50 often they wake up (their listen interval). The AP buffers
`traffic for each station for at least their listen interval before
`discarding it. Stations indicate what PS mode they currently
`are in with every frame they transmit.
`When stations in the PS mode are present, the AP is
`55 required to maintain a DTIM interval. This interval indicates
`the number of Beacons that occur between Beacons wbere
`delivery of broadcast/multicast frames will be attempted.
`Beacons which a1u1ounce U1e delivery of broadcast/multicast
`frames are called DTIMs. Each Beacon contains a count
`down to the Beacon where delivery of broadcast/multicast
`messages will be attempted, as well at the interval between
`such beacons. When Broadcast frames are delivered in the
`presence of stations in the PS mode, they must be delivered
`before any directed (unicast or addressed to a single station)
`frames . In addition. for CFP _Beacon. the beacon must
`indicate in the DT!M element which PS stations the AP
`intends to poll dltriug that CFP. That enables the PS stations
`
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`

`US 7,031,274 B2
`
`6
`5
`111e HlPERLAN/2 phase is viewed by 802.1 I terminals as
`lO know when they must remain awake 10 receive broadcast/
`part of the CFP, and accorded protection accordingly. The
`multicast frames, or frames addressed to them. Otherwise
`CFP's maximum length (determined by the parameter CFP
`stations only awake once per their listen interval (and at the
`DTIM intervals if the must receive Broadcast/Multicast
`max length) is determined by a variable reg11larly broadcast
`in Beacon messages. JI is optimally set very close lo the full
`messages), and go back lO their dose state immediately if no 5
`length of the super.frame. 1o relinquish the time to the CP,
`fr'<1.mes need to be received. Note that CFP _Beacons must
`when the CF _End is sent, all terminals automatically reset
`also be DTIM Beacons, though the reverse is not true.
`their NAV's. Normal CP transmissions would then occur.
`Given that PS stations will be staying awake (wasting
`power) to receive frames announced by the Beacon, and that
`Note that additional Beacons might occur during the CP that
`broadcast/multicast messages must always be transferred 10 do not start a new CFP. The existence of these Beac-0ns may
`first, the ordering of FlG. 5 is the most obvious solution.
`make it easier to handle broadcast traffic, and 802.1 I power
`However, nothing in the standard prevents the delivery of
`saver terminals, but is not a requirement.
`HIPERLAN/2 frames before the delivery of 802.11 broad-
`Beacon jitter may result in jitter in the super.frame.
`cast frames. In addition, during the CFP, all 802.l 1 stations
`IPERLAN/2 is not very tolerant of jitter. However, by
`will remain quite until CFP max Interval regardless of 15 utilizing spoofing frames jitter before the Beacon can be
`controlled. Also by allowing the broadcast/CFP traffic to be
`whether the channel is occupied by a known signal. They
`recognize the HIPERLAN/2 phase as a part of the CFP. So
`intern1pted by the HIPERLAN/2 phase, it is possible to ease
`there is no reason why the HIPERLAN/2 phase could not be
`some of the Beacon jitter restrictions while maintaining
`first after the beacon, followed by broadcast/multicast mes-
`precise tinting for the HJPERLAN/2 phase. The system
`sages, and the "CFP" phase. This reordering acn1ally pro- 20 would schedule tbe HIPERLAN/2 phase to be some time
`after the CFP _Beacon. Since the Beacon would jitter, the
`vides the maximum scheduling flexibility, at the penalty of
`PS stations having to remain awake during the I-IIPER-
`time between it and the I-IIPERLAN/2 phase would vary.
`LAN/2 phase.
`But this time could be filled with 802.J I CFP traffic. The
`Also, while polling of 802.11 stations during the CFP
`802.11 traffic would be suspended by the AP just prior lo the
`nt--eds to be in Association TD (AID) order (with broadcast/ 25 HIPERLAN/2 phase start time. and would resume after the
`multicast messages being sent first) nothing prevents HIP-
`HIPERLAN/2 phase. Alternatively, the Access Port (AP)
`ERLAN/2 messages from intervening at any point during
`could broadcast dummy traffic just prior to the CFP _Beacon
`polling cycle of the CFP. Thus, it is possible to have a
`preventing other traffic from seizing the medium. In addi-
`broadcast phase start immediately after the Beacon, be
`t'ion, wh.ile it is lllJ.likely lo be needed, a spoofing frame or
`interrupted by the HIPERLAN/2 phase. and then have the 30 frame sequence could still be transmitted prior to the HIP-
`broadcast phase pick up again after the HIPERLAN/2 phase
`ERLAN/2 phase if desired to further assure that no 802.11
`completes. Or, the CFP phase could be interrupted by the
`STA are active during the HIPERLAN/2 phase.
`mPERLAN/2 phase, and then continue afterwards followed
`Wbile this invention has been exemplified as a system for
`by the CP. To the 802.11 stations, the Broadcast phase, CFP
`handliug 802.11 aud HIPERLAN/2 transmissions, its prin-
`phase, and HIPERLAN/2 phase all appear as a single CFP 35 ciples may be applicable to other transmission systems such
`as Bluetooth, HomeRF or WiMedia. Such systems may also
`phase. Thus, any ordering of these phases will work, and are
`within the spirit of the invention. The key is that the
`be known at times a Personal Area networks (PANS) rather
`mPERLAN/2 phase should occur during the CF'P phase
`than WLANs. These applications will be obvious to those
`where it has additional protection from 802.11 stations s.ince
`skilled in the art.
`their NAV's are set for the CFP.
`40 What I claim is:
`In the graph of FIG. 5, synchronization of signaling is
`1. In a communications environment where multiple
`secured by use of the beacon frames "B" (a management
`instances of diverse access protocols share a com1mU1ica(cid:173)
`frame), which define the superframe size or more correctly
`tions media, where it is desired that transmissions from one
`the times between CFPs. 802.11 MAC access functions are
`instance not collide with
`transmissions fonn another
`controlled by coordination functions of which DCF is a 45
`instance. and each instance of an access protocol has the
`ability to restrict access to the media for all stations in that
`distributed coordination function and PCF is a centralized
`(point) coordination function. CFP Max length is the maxi(cid:173)
`instance practicing that protocol from a set of stations in that
`mum lenf,>tb of a contentiou free period within the 802.1 1
`instauce, and the stations haviug the ability to restrict access
`system whose end is marked by "E" the CF-End manage(cid:173)
`in each instance can all communicate with the other stations
`ment frame shown occurring at less than the maximum). As 50
`able to restrict access. wherein a method of permitting
`interoperability of the instances of the access protocols
`shown, the HIPERLAN/2 format transmissions (H/2 MAC(cid:173)
`frame) occur during a portion of the 802. 11 CFP. The CFP
`includes the steps of:
`assigning each instauce of each access protocol to sepa(cid:173)
`period also includes a "CFP" phase (i.e., a period of time
`rate phases occurring in aJlocated time periods;
`within the CFP where actual data is delivered using the
`communicating the aJlocated time periods for each pro(cid:173)
`CFP's contention free protocols). Following the end of the 55
`tocol instance to the stations having the ability to
`CFP at "E" an 802.l la fonuat CP (contention period) is
`activated. A management frame "X" to pem1it blocking and
`restrict tra'ffic for that protocol instance;
`spoofing is iucorporated both before HlPERLAN/2 trans(cid:173)
`for a selected protocol assembling spoofing frames from
`missions and immediately before the next subsequent CFP(cid:173)
`an RTS frame transmitted by APs associated with the
`_Beacon "8". If desired "X" may be incorporated on only 60
`selected protocol, followed by a CTS frame transmitted
`one or indeed none of these intervals. Blocking and spoofing
`by stations associated with the selected protocol; and
`are discussed in my co pending application discussed herein
`restricting access of stations in each protocol iustance lo
`only those rime periods assigned to that protocol
`above. Hence, by embedding HIPERLAN/2 transmissions
`instance.
`within the contention free period of the 802.l la format both
`systems operate with out interference to/from each other and 65
`2. The method of claim 1. where:
`using 802. I J DCF in the access protocol for at least one
`coordinating access via a Hybrid Access Port (which !mows
`the timing of both systems).
`of the phases;
`
`Marvell Semiconductor, Inc. - Ex. 1004, Page 0007
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
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`US 7,031,274 B2
`
`10
`
`15
`
`7
`enabling the stations transmitting in this phase witl1 an
`ability to restrict access to 802.11 AP's; and
`restricting access in other phases by stations transmitting
`in this phase by having 802.11 APs trigger the trans(cid:173)
`mission or spoofing frames with durntion fields set to 5
`prevent access by 802.11 stations to the medium in
`other phases.
`3. The method of claim 2, including a step of:
`practicing the HIPERLAN/2 access protocol in HJPER-
`LAN/2 stations in at least one of the phases.
`4. The method or claim 2, including a step of:
`assembling the spoofing frames transmitted from an
`802.11 RTS frame transmitted by the APs, followed by
`an 802.11 CTS frame transmitted by 802.11 stations.
`5. The method of claim 2, including a step of:
`assembling the spoofing frames transmitted from an
`802.11 RTS frame transmitted by the APs, followed by
`an 802.11 CTS frames transmitted by 802.11 stations,
`followed by other CTS frames transmitted by APs.
`6. The method of claim 2, including a step of:
`where the spoofing frames transmitted consist of a single
`802.11 CTS frame transmitted by each of the APs.
`7. The method of clai1u 2, including a step of:
`ssembling the spoofing frames transmit1ed from a single
`802. 11 data frame transmined by each of Ille APs.
`8. The method of claim 2, including a step of:
`arranging start times of the phases to be on average
`periodic in natLU·e, allowing a super-frame strncture to
`be defined.
`9. The method of claim 2, including steps of:
`pred.eterlllining start and end dines of at least one of the
`phases; and
`making the start aud end times known to all stations
`needing to restrict access during that phase so that no
`commt111ications is required between stations restrict- 35
`ing access to the media for that phase.
`10. In a commt111ication environment in which access
`ports of systems are individually operative at overlapping
`
`8
`frequencies in one or two active operative WLAN systems
`each operating in a common channel each under a different
`controlling standard, wherein a method of permitting
`interoperability of the two systems includes steps of:
`establishing a superframe within which contention is
`substantially eliminated and resolved by;
`limiting each system to separate phases of allocated
`defined contention periods for differing;
`for a selected standard, assembling spading frames from
`an RTS frame transmitted by APs associated with the
`selected standard, followed by a CTS frame transmitted
`by stations associated with the selected standard; and
`selecting contention periods to acconuuodate variants of
`operating standards of the operative WLAN systems:
`and
`preventing access ports of one standard from transmitting
`during time periods alloued to access ports of anotl1er
`standard for transmission.
`11. The method of claim 10, including a step of:
`establishing transmission for one of the two WLAN
`systems during a contention period of the other WLAN.
`12. The method of claim 11, including a step of:
`separating 802.11 CFP intervals form H/2 MAC-frame
`intervals by a spoofing/blocking frame sequence.
`13. The method or claim 12, including a step of:
`adding additional beacons in au 802.1 1 interval to prevent
`jitter.
`14. The method of claim 13, iucluding a step of:
`ending a contention free period for 802.11 after comple(cid:173)
`tion of HIPERLAN/2 transmissions.
`15. The method of claim 14, including a step of:
`synchronizing super-frames by use of a synchronizing
`beacon.
`
`* * * * *
`
`20
`
`25
`
`30
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`Marvell Semiconductor, Inc. - Ex. 1004, Page 0008
`IPR2019-01350 (Marvell Semiconductor, Inc. v. Uniloc 2017 LLC)
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