(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2002/0061031A1
`Sugar et al.
`(43) Pub. Date:
`May 23, 2002
`
`US 2002006 1031A1
`
`(54) SYSTEMS AND METHODS FOR
`INTERFERENCE MITIGATION AMONG
`MULTIPLE WLAN PROTOCOLS
`(76) Inventors: Gary L. Sugar, Rockville, MD (US);
`William R. Seed, N. Potomac, MD
`(US); Yohannes Tesfai, Falls Church,
`VA (US)
`Correspondence Address:
`SONNENSCHEN NATH & ROSENTHAL
`1301 KSTREET NW, SUITE 600
`EAST TOWER
`WASHINGTON, DC 20005 (US)
`
`(21) Appl. No.:
`
`09/970,846
`
`(22) Filed:
`
`Oct. 5, 2001
`
`
`
`Related U.S. Application Data
`(63) Non-provisional of provisional application No.
`60/238,761, filed on Oct. 6, 2000.
`
`Publication Classification
`(51) Int. Cl. .................................................... H04J 3/16
`(52) U.S. Cl. ............................................ 370/466; 370/445
`
`(57)
`
`ABSTRACT
`
`Interference mitigation or collision avoidance Systems and
`procedures to allow different wireless local area network
`(WLAN) communication protocols to co-exist in the same
`frequency band, Such as an unlicensed frequency band used
`for Short-range wireleSS communications. The procedures
`ensure Substantial throughput of information carried by
`signals of each WLAN protocol while preventing collisions
`between Signals of different protocols.
`
`DELL
`EXHIBIT 1004 - PAGE 1
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`

`

`Patent Application Publication May 23, 2002 Sheet 1 of 22
`
`US 2002/0061031A1
`
`
`
`CN O
`Y- c O CN
`s O
`N. O.
`
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`EXHIBIT 1004 - PAGE 2
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`

`Patent Application Publication
`
`May 23, 2002. Sheet 2 of 22
`
`US 2002/0061031A1
`
`ZZ!
`
`
`
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`EXHIBIT 1004 - PAGE 3
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`

`

`Patent Application Publication May 23, 2002 Sheet 3 of 22
`FIG. 3
`
`US 2002/0061031A1
`
`NetWork
`Connection
`
`R B
`B
`
`N A ZANA
`
`FIG. 4
`SA
`SB
`
`Frequency
`F.G. 5A
`PAGA
`H-I-H
`I
`-
`
`-
`Time
`FIG. 5B
`
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`

`

`Patent Application Publication May 23, 2002 Sheet 4 of 22
`
`US 2002/0061031A1
`
`FIG. 7
`
`
`
`Frequency
`
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`EXHIBIT 1004 - PAGE 5
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`

`

`Patent Application Publication May 23, 2002 Sheet 5 of 22
`
`US 2002/0061031A1
`
`F.G. 10
`
`
`
`Frequency
`
`Frequency
`
`Frequency
`
`DELL
`EXHIBIT 1004 - PAGE 6
`
`

`

`Patent Application Publication May 23, 2002 Sheet 6 of 22
`
`US 2002/0061031A1
`
`OZ 0 || 0 0]. – OZ
`
`
`
`(ZHIN) KOuenbeu-8
`
`O O
`
`(qp) JeMO
`
`CC
`
`
`
`(ZHW) KOuenbeu-09Z09Z
`
`
`
`
`
`
`
`DELL
`EXHIBIT 1004 - PAGE 7
`
`

`

`Patent Application Publication May 23, 2002 Sheet 7 of 22
`
`US 2002/0061031A1
`
`28O
`
`
`
`Bluetooth
`Modulator
`
`F.G. 12A
`
`285
`
`
`
`287
`
`Power Amplifier
`
`To Antenna TX
`
`
`
`
`
`295
`
`
`
`
`
`802.11
`Detector
`
`1 MHZ Notch
`wfSelectable
`Center Frequency
`
`DOWnconverter
`
`297
`
`(Tx signal coupled
`into Rx path)
`w
`
`From Antenna RX
`
`290
`
`FIG. 12B
`
`an 0
`k-
`
`0
`SG
`9 -20
`st
`
`FIG. 12C
`layy
`S-20
`i. - if -40
`
`20 -10 0 10 20
`Frequency (MHz)
`
`-2O -10 O 1 O 20
`Frequency (MHz)
`
`FIG. 13
`
`309
`
`3O7
`
`
`
`Live downlink
`data
`
`802.11 Activity
`
`300
`Bluetooth activity :
`SCO Sot
`(either uplink or
`downlink)
`
`DELL
`EXHIBIT 1004 - PAGE 8
`
`

`

`Patent Application Publication May 23, 2002 Sheet 8 of 22
`
`US 2002/0061031A1
`
`
`
`(?oIS ?uusuel)
`
`
`
`Bois lax?)
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`‘?OIS OOS ?JO?eq \ex\oed puen6 ? ? ‘ZOg ?uusueu L
`
`
`
`
`
`
`
`?OIS OOS ??uusuel L
`
`DELL
`EXHIBIT 1004 - PAGE 9
`
`

`

`Patent Application Publication May 23, 2002 Sheet 9 of 22
`
`US 2002/0061031A1
`
`FIG. 15
`32O
`
`Guard Packet
`
`BT SCO Packet
`
`
`
`
`
`322
`
`322
`
`CTS(1) CTS(2) .
`
`.
`
`.
`
`322
`
`PHY Preamble
`
`Control
`
`
`
`324
`
`326
`
`328
`
`330
`
`332
`
`FIG 16
`340
`
`
`
`Guard Packet
`
`
`
`BT SCO Packet
`
`
`
`342
`
`342
`
`SP(1)
`
`SP(2) . . .
`
`342
`
`344
`
`
`
`Frame
`PHY Preamble '''', DURID
`
`348
`
`350
`
`352
`
`354
`
`356
`
`DELL
`EXHIBIT 1004 - PAGE 10
`
`

`

`Patent Application Publication May 23, 2002 Sheet 10 of 22 US 2002/0061031A1
`
`FIG. 17A
`
`ACL downlink data to
`transmit at Slot N
`
`400
`
`
`
`405
`
`802.11 busy
`indicator active?
`
`N
`
`TX5-slot packet at
`slot N
`
`Find greatestn in {1, 3, 5) s.t. BT
`frequency is outside of 802.11 band
`for slots N (TX Slot) and N+n (RX
`ACK slot). Use n = 0 if no such pair
`of slots exists.
`
`410
`
`N
`
`Tx n-slot packet at
`slot N
`
`Find smallestn in {1, 3,5} s.t. BT
`frequency inside 802.11 band for
`slot N and Outside for slot N +n. Use
`n = 0 if no such pair of slots exists.
`
`415
`
`422
`
`Postpone Tx, wait at
`least 2 slots before re
`running above sequence
`
`
`
`
`
`
`
`DELL
`EXHIBIT 1004 - PAGE 11
`
`

`

`Patent Application Publication May 23, 2002 Sheet 11 of 22
`
`US 2002/0061031A1
`
`FIG. 17B
`
`
`
`
`
`420
`
`425
`
`802.11 idle > 1 DIFS
`
`Y
`
`Tx n-slot packet at
`Xn-SIOtpacket a
`
`427
`
`N
`
`802.11 RX
`during BT TX?
`
`429
`
`N
`
`Tx n-slot packet at
`slot N
`
`Has BT terminal successfully
`reCeived at least T of last 10
`BT packets in 802.11 band when
`802.11 uplink active?
`
`433
`-
`Y Tx n-slot packet at
`slot N
`
`
`
`
`
`430
`
`
`
`
`
`
`
`Postpone TX, wait at
`least 2 slots before re
`running above sequence
`
`435
`
`DELL
`EXHIBIT 1004 - PAGE 12
`
`

`

`Patent Application Publication May 23, 2002 Sheet 12 of 22 US 2002/0061031A1
`
`CO
`
`l sfy
`
`
`
`i.
`
`DELL
`EXHIBIT 1004 - PAGE 13
`
`

`

`Patent Application Publication May 23, 2002 Sheet 13 of 22 US 2002/0061031A1
`FIG. 19A
`
`ACL uplink data to
`receive at slot N
`
`802.11 busy
`indicator active?
`Y
`lots N-1
`SIOISN-
`and N Outside 802.11
`band?
`N
`Slots N-
`and N inside and slot
`N Outside 802.11
`band?
`
`
`
`802.11 idle
`for > 1 DFS before
`Slot N-12
`
`500
`
`510
`
`520
`
`
`
`530
`
`
`
`
`
`N
`
`Y
`
`
`
`
`
`
`
`
`
`
`
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at Slot N
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at slot N
`
`505
`
`515
`
`N
`
`Postpone Rx, wait at
`least 2 slots before re-
`running above sequence
`
`-525
`
`
`
`Y
`
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at slot N
`
`535
`
`DELL
`EXHIBIT 1004 - PAGE 14
`
`

`

`Patent Application Publication May 23, 2002 Sheet 14 of 22
`
`US 2002/0061031A1
`
`999
`
`979XH || || 'Z08
`
`079
`
`
`
`
`
`
`
`099
`
`099
`
`DELL
`EXHIBIT 1004 - PAGE 15
`
`

`

`Patent Application Publication May 23, 2002 Sheet 15 of 22 US 2002/0061031A1
`FIG. 20
`
`20 ms
`
`
`
`elescucco are are
`
`FIG. 22
`
`20 mS
`
`HomeRF
`
`
`
`
`
`arbTb1
`
`DELL
`EXHIBIT 1004 - PAGE 16
`
`

`

`Patent Application Publication May 23, 2002 Sheet 16 of 22
`
`US 2002/0061031A1
`
`Z89
`
`989
`
`
`
`919
`
`(ZHNZ) XTO
`
`
`
`DELL
`EXHIBIT 1004 - PAGE 17
`
`

`

`Patent Application Publication May 23, 2002 Sheet 17 of 22 US 2002/0061031A1
`
`FIG. 23
`
`
`
`Configure HRF N
`superframe
`normally
`
`
`
`
`
`600
`
`HRF frequency in 802.11
`band for this dwell?
`
`Y
`
`610
`
`
`
`To mitigate HRF/802.11 data collisions, configure HRF
`superframe as follows:
`Beacon: Protect using 802.11 guard packet
`CFP1: Configure normally, protect with 802.11 guard packet
`Service Slot: Configure normally
`CSMAVCA Field:
`if shared CSmaMode = 1
`configure normally
`else alternate CSMAJCA ownership between HRF & 802.11
`CFP2: Configure normally, protect with 802.11 guard packet
`
`Set arb Tblin) = 0, n=0,...,31
`
`620
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`To mitigate HRFIBT data collisions, configure HRF superframe
`and HRFIBT arbitration table (arbTbl) as follows:
`For each BT slot in HRF band during this dwell
`if BT slot overlaps with CFP1:
`if BT Slot is a SCO slot
`alternate = 1
`if alternate at 1
`disable BT transmission (arbiblin) = 1)
`else
`disable HRF transmission during BT slot
`else
`disable BT transmission (arbiblin) = 1)
`if BT slot overlaps with CFP2:
`if BT Slot is a SCO slot
`disable HRF transmission during BT slot
`else
`disable BT transmission (arbTbi n) = 1)
`if BT slot overlaps with CSMAJCA field:
`if BT Slot is a SCO slot:
`protect BT SCO packet w/ HomeRF guard packet
`
`DELL
`EXHIBIT 1004 - PAGE 18
`
`

`

`Patent Application Publication
`
`US 2002/0061031A1
`
`90]
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`DELL
`EXHIBIT 1004 - PAGE 19
`
`

`

`Patent Application Publication May 23, 2002 Sheet 19 of 22 US 2002/0061031A1
`
`FIG. 24B
`
`Find smallestn in {1, 3, 5) s.t. (1) BT frequency inside either active
`band for slot N and Outside of both active bands for slot N+n; (2)
`arbTblk) = 0 for k = N,...,N+n. Use n = 0 if no such pair of slots exists
`(find smallest packet which does not interfere wiHRF voice data, which
`has a TXfrequency inside either active band, and a corresponding ACK
`frequency Outside of both active bands)
`
`
`
`
`
`
`
`
`
`Postpone TX, wait at
`least 2 slots before re
`running above Sequence
`
`735
`
`740
`
`750
`
`
`
`745
`
`
`
`
`
`CSMA idle > 1 DIFS
`for active bands in Which
`slot N resides 2
`
`
`
`Tx n-slot packet
`at Slot N
`
`DELL
`EXHIBIT 1004 - PAGE 20
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`

`

`US 2002/0061031A1
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`91/
`
`Patent Application Publication
`
`091991
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`May 23, 2002 Sheet 20 of 22
`
`0119]
`
`DELL
`EXHIBIT 1004 - PAGE 21
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`

`

`Patent Application Publication May 23, 2002 Sheet 21 of 22 US 2002/0061031A1
`FIG. 25A
`
`ACL uplink data to
`receive at slot N
`
`actw802 = 1 if 802.11 busy indicator active
`actvHRF = 1 if HRFCSMA busy indicator active
`
`800
`
`
`
`
`
`arbTblk = 0,
`
`Y
`
`810
`
`
`
`actw802 =
`aCtWHRF = 0
`
`
`
`820
`
`slots N-1
`and NOutside both active
`bands?
`
`805
`
`N
`
`Postpone Rx, Waitat
`least 2 slots before re
`running above sequence
`
`815
`
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at slot N
`
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at Slot N
`
`
`
`
`
`830
`
`
`
`
`
`
`
`
`
`slot N-1 inside
`either active band and
`slot NOutside both
`active bands 2
`
`N
`
`Postpone RX, wait at
`least 2 slots before re
`running above Sequence
`
`DELL
`EXHIBIT 1004 - PAGE 22
`
`

`

`Patent Application Publication May 23, 2002 Sheet 22 of 22 US 2002/0061031A1
`
`FIG. 25B
`
`
`
`840
`
`CSMA ide>
`DIFS before slot N-1 for
`active bands in which slot N-1
`resides 2
`
`845
`
`Send POLL to BT
`terminal at slot N-1
`to receive uplink data
`at slot N
`
`
`
`
`
`
`
`
`
`850
`
`ls 802.11
`the only active band in
`Which slot N-1 resides, and is there
`no 802.11 to Rx during slot N-1
`transmission ?
`
`
`
`
`
`
`
`
`
`860
`
`is 802.11 the
`Only active band in which slot N
`1 resides, is there 802.11 data to RX, and has
`BT terminal received > Tof last 10 BT packets
`in 802.11 band When 802.11
`uplink active?
`
`
`
`870
`
`N
`Postpone Rx, Waitat
`least 2 slots before re
`running above sequence
`
`
`
`Y
`
`Send POLL to BT
`terminal at Slot N-1
`to receive uplink data
`at slot N
`
`855
`
`
`
`Y
`
`Send POL to BT
`terminal at slot N-1
`to receive uplink data
`at slot N
`
`865
`
`DELL
`EXHIBIT 1004 - PAGE 23
`
`

`

`US 2002/0061031A1
`
`May 23, 2002
`
`SYSTEMS AND METHODS FOR INTERFERENCE
`MITIGATION AMONG MULTIPLE WLAN
`PROTOCOLS
`0001. This application claims priority to U.S. Provisional
`Application No. 60/238,761 filed Oct. 6, 2000, the entirety
`of which is incorporated herein by reference.
`
`BACKGROUND OF THE INVENTION
`0002 The present invention is directed to systems and
`methods for preventing the collisions or interference
`between Signals from different wireleSS local area network
`(WLAN) and wireless personal area network (WPAN) com
`munication protocols that coexist in the Same frequency
`band. The term WLAN is used to refer to a class of wireless
`communication technology that operates at a distance up to
`100 meters, and AWPAN is commonly used to refer to a
`class of wireleSS communication technology that operates up
`to a distance of 10 meters. For simplicity, when used herein,
`the term WLAN is meant to encompass WLAN as well as
`WPAN technologies, and any other shorter-range wireless
`communication technology, particularly, but not limited to,
`those that do not require a license for operation by the
`Federal Communications Commission in the United States
`and other similar unlicensed bands outside of the U.S.
`0003. The existence and popularity of new WLAN com
`munication protocols results in Several protocols sharing the
`Same frequency spectrum. This causes an interference prob
`lem affecting throughput and reliability in wireleSS net
`works.
`
`IEEE 802.11b.
`
`Bluetooth TM
`
`HomeRF
`
`Market Focus
`
`Devices Likely to
`Use this Tech.
`
`Technology
`
`Peak Data Rate
`Range
`Transmit Power
`
`Enterprise
`WLAN,
`school, home
`Laptop,
`desktop PCs
`
`2.4 GHz ISM,
`DSSS
`11 Mbps
`50 m
`20 dbm
`
`Wireless cable
`
`Home WLAN
`
`Palmtops, cell-
`phones, MP3
`players
`2.4 GHz ISM,
`FH
`721 kbps
`10 m
`Odbrm
`
`Home desktop
`PCs, printers,
`cordless phones
`2.4 GHz ISM,
`FH
`1.6 Mbps
`50 m
`20 dbm
`
`In the U.S. alone, for example, three popular
`0004.
`WLAN technologies exist which share the 2.4 GHz unli
`censed ISM band (see table above). As it turns out, each
`technology has merits relative to the other and, as a result,
`has Secured itself as a preferred technology in at least one
`important market Segment. Bluetooth", for example, has
`proven to be the leading WLAN technology for low-cost
`mobile computing devices Such as palm-top computers,
`cell-phones, and MP3 audio players. On the other hand,
`because of its support for 10 Mbps data rates, IEEE 802.11b
`appears to be preferred for laptop computers in the enter
`prise and home environments.
`0005. The lack of a dominant WLAN technology means
`that different device types may use multiple WLAN tech
`nologies at the same time in the same place. For example, in
`the residence, IEEE 802.11b and/or HomeRF may be used
`for wireleSS computer networking, and Bluetooth may be
`preferred for games, MP3 playerS and palmtop computers.
`
`In the enterprise environment, 802.11b may be used for
`wireless computer networking (laptops and/or desktop com
`puters), and Bluetooth may be used for palmtop computers
`and cell-phones.
`0006 Unfortunately, although each of these technologies
`was designed to work reliably with Some interference in the
`ISM band, they were not designed to coexist with each other.
`The resulting interference between the WLAN technologies
`degrades System throughput and compromises the overall
`reliability of each of the wireless networks. This is a
`well-known and well-documented problem.
`SUMMARY OF THE INVENTION
`0007. The systems and methods of the present invention
`provide interference mitigation algorithms which allow for
`the operation of multiple wireleSS communication protocols
`in a common frequency band, particularly an unlicensed
`frequency band allocated for Short-range wireleSS commu
`nication. The Systems and methods according to the present
`invention have utility in WLANs where there is possible
`overlap in frequency and time of Signals transmitted in a
`common frequency band. In Some cases, there is a signal of
`one communication protocol that is of a fixed frequency
`nature (at least one or more fixed frequencies) in the
`frequency band concurrent with a signal of another com
`munication protocol that hops to different, but predictable,
`frequencies. It is also possible that there are signals of a
`frequency hopping nature of the same type of communica
`tion protocol present in the frequency band, for example,
`two Bluetooth networks operating in the same frequency
`band. In general, the System and methods of the present
`invention are useful in WLANs that have one or more
`frequency hopping communication protocols coexisting
`with one or more fixed frequency communication protocols
`in a frequency band, and WLANs that have two or more
`frequency hopping Signals of the same or different type
`coexisting in a frequency band. Collisions of Signals in the
`frequency band that would otherwise naturally occur among
`the devices are minimized or avoided while optimizing
`throughput of information.
`0008. Other objects and advantages of the present inven
`tion will become more readily apparent when reference is
`made to the following description in conjunction with the
`accompanying drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`0009 FIG. 1 is a block diagram of a multi-protocol
`communication environment according to the present inven
`tion.
`0010 FIG. 2 is a block diagram showing an internal
`architecture Suitable for a multi-protocol wireleSS commu
`nication device (MPD) according to the present invention.
`0011 FIG. 3 is a diagram depicting communication
`between an MPD and terminal nodes in a WLAN using two
`different types of WLAN communication protocols or tech
`nologies, referred to as A and B.
`0012 FIG. 4 is a frequency spectrum diagram for a
`multi-mode WLAN in which two different WLAN commu
`nication protocols operate in the same frequency band.
`0013 FIGS. 5A and 5B are timing diagrams showing
`basic time-division duplex formats for each WLAN com
`munication protocol.
`
`DELL
`EXHIBIT 1004 - PAGE 24
`
`

`

`US 2002/0061031A1
`
`May 23, 2002
`
`FIG. 6 is a diagram showing concurrent transmis
`0.014
`sion of information from an MPD (downlink) on each of two
`WLAN communication protocols to two separate terminals
`in the same frequency band.
`0.015
`FIG. 7 is a diagram showing concurrent reception
`of information at the MPD (uplink) from two separate
`terminals on each of two WLAN communication protocols
`in the same frequency band.
`0016 FIG. 8 is a diagram showing transmission from the
`MPD to a terminal (downlink) on one communication
`protocol concurrent with reception at the MPD from another
`terminal (uplink) on another communication protocol in the
`Same frequency band.
`0017 FIG. 9 is a flow diagram showing a notch filtering
`technique to Support Simultaneous downlink of information
`on each of two different communication protocols in the
`Same frequency band.
`0.018
`FIG. 10 is a flow diagram showing a notch filtering
`technique to Support Simultaneous downlink of information
`on one communication protocol and uplink on another
`communication protocol in the same frequency band.
`0.019
`FIG. 11A is a block diagram showing a configu
`ration in an MPD Suitable for simultaneous downlink of
`information using the frequency hopping communication
`protocol, such as Bluetooth TM and fixed frequency commu
`nication protocol, such as IEEE 802.11 in the same fre
`quency band.
`0020 FIGS. 11B, 11C and 11D are spectrum diagrams of
`various signal points in the block diagram of FIG. 11A.
`0021
`FIG. 12A is a block diagram showing a configu
`ration in an MPD Suitable for simultaneous downlink of
`information using a frequency hopping communication pro
`tocol and uplink of information using the fixed frequency
`communication protocol in the same frequency band.
`0022 FIGS. 12B and 12C are spectrum diagrams of
`various signal points in the block diagram of FIG. 12A.
`0023 FIG. 13 is a timing diagram showing the use of a
`guard packet to manage communication of Synchronous type
`data using a frequency hopping protocol in the same fre
`quency band as a fixed frequency communication protocol.
`0024 FIGS. 14A and 14B are flow diagrams showing a
`procedure for using the guard packet shown in FIG. 13 for
`downlink and uplink, respectively, of Synchronous type data.
`0.025
`FIG. 15 is timing diagram for an alternative guard
`packet for wireleSS communication devices that function as
`acceSS points.
`0.026
`FIG. 16 is a timing diagram for a guard packet for
`wireleSS communication devices that function as terminals
`or Stations.
`0027 FIGS. 17A and 17B depict a flow diagram for a
`procedure for downlink communication of non-Synchronous
`type data using a frequency hopping communication proto
`col in the same frequency band as a fixed frequency com
`munication protocol.
`0028 FIG. 18 is a spectrum diagram that shows an
`optional additional procedure for downlink communication
`of asynchronous type data using a frequency hopping com
`
`munication protocol in the same frequency band as a fixed
`frequency communication protocol.
`0029 FIGS. 19A and 19B depict a flow diagram for a
`procedure for uplink communication of asynchronous type
`data using a frequency hopping communication protocol in
`the same frequency band as a fixed frequency communica
`tion protocol.
`0030 FIG. 20 is a timing diagram for a time frame of
`information transmitted in accordance with Still another type
`of frequency hopping wireleSS communication protocol,
`Such as HomeRFTM.
`0031
`FIG. 21A is a block diagram of a clock circuit
`arrangement designed to frequency lock and phase align the
`clock Signals of two frequency hopping communication
`protocols.
`0032 FIG. 211B is a timing diagram showing a desired
`phase alignment between the clock Signals of two frequency
`hopping protocols.
`0033 FIG. 22 is a diagram showing how an arbitration
`table is built to manage communication in the Same fre
`quency band where two frequency hopping communication
`protocols are active according to the present invention.
`0034 FIG. 23 is a flow diagram for a procedure to
`manage communication in the same frequency band where
`two frequency hopping communication protocols and one
`fixed frequency communication protocol are active and
`synchronous type data is communicated using the two
`frequency hopping communication protocols.
`0035 FIGS. 24A, 24B and 24C depict a flow diagram for
`a procedure to manage communication in the same fre
`quency band where two frequency hopping communication
`protocols and one fixed frequency communication protocol
`are active and asynchronous type data is downlink commu
`nicated.
`0036 FIGS. 25A and 25B depict a flow diagram for a
`procedure to manage communication in the same frequency
`band where two frequency hopping communication proto
`cols and one fixed frequency communication protocol are
`active and asynchronous type data is uplink communicated.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`0037) 1. General Description of Interference Mitigation
`Procedures
`0038. The present invention enables an improvement in
`the operation of two or more dissimilar wireleSS local area
`network (WLAN) communication protocols or technologies
`that operate in the same frequency band. For purposes of
`understanding the present invention, Several terms will be
`introduced and explained. The term “node” will be used
`throughout. A node refers to a wireleSS communication
`device that is a point on a network, such as a WLAN. A
`“hub” node is a node that distributes information to (as well
`as receives information from) other nodes and may also be
`connected to another network, Such as a wired network. A
`“terminal' node is a node that communicates with a hub
`node or other non-hub nodes, and is not connected to another
`network.
`
`DELL
`EXHIBIT 1004 - PAGE 25
`
`

`

`US 2002/0061031A1
`
`May 23, 2002
`
`0039. A multi-protocol wireless communication device
`(MPD) is a device which acts as a node (hub or terminal) on
`two or more wireless local or personal area networks,
`simultaneously. An example of an MPD is device that
`operates Simultaneously as a hub with respect to communi
`cation protocols A and B in communicating with terminal
`nodes. Some terminal nodes that communicate with this
`MPD may use only protocol A and others may use only
`protocol B, while still others may use protocol A and/or B.
`Generally, the devices that operate using communication
`protocol A form one wireleSS communication network, and
`the devices that operate using communication protocol B
`form another wireleSS communication network. Another
`example of an MPD is a laptop computer augmented with
`the appropriate hardware and/or Software to act as a terminal
`node with respect protocol A and Simultaneously as a hub
`node with respect to protocol B. Still another example of an
`MPD is a device that simultaneously operates as a terminal
`node for protocol A and a terminal node for protocol B. The
`interference avoidance algorithms described herein are use
`ful in the MPD. Finally, it should be understood that the
`interference avoidance algorithms of the present invention
`may also be useful to manage communication of two or
`more networks operating with the same communication
`protocol in the same frequency band, particularly where a
`characteristic of the protocol (frequency hopping) necessi
`tates collision avoidance procedures to optimize throughput
`on each network.
`0040. The terms “downlink” and “uplink” are used in the
`foregoing description. Transmission from the hub node to a
`terminal node is referred to as a "downlink' and communi
`cation from a terminal node to a hub node is referred to as
`an “uplink.” Transmission directly between terminal nodes
`is called peer-to-peer communication.
`0041. A terminal node may have a particular name or
`identifier for different communication protocols. For
`example, a BT terminal node is called a slave and a 802.11
`terminal node is called a station (STA). A BT hub node is
`called a master. An 802.11 hub node is called an access point
`
`FIG. 1 shows an example of a system 10 according
`0.042
`to the invention in which an MPD 12 communicates with
`terminal nodes 14, 16, 18, 20 and 22. Terminal nodes 14 and
`22 are wireleSS communication devices that, for example,
`operate using a first communication protocol, Such as
`802.11. Terminal nodes 16 and 20 are wireless communi
`cation devices that, for example, operate using a Second
`communication protocol, Such as Bluetooth. Terminal node
`18 is a wireleSS communication device that, for example,
`operates using a third communication protocol, Such as
`HomeRF. The MPD12 is shown to be connected to a wired
`network 30, which in turn may be connected to a router 32
`and to the Internet 34.
`0.043
`FIG. 2 shows an example of an internal architec
`ture for an MPD device useful according to the invention.
`0044) The MPD 12 comprises a receive channel section
`100, a transmit channel section 150, MAC layer protocol
`processors 180, 182 and 184, a network access arbitration
`controller 190, a voice processor 192 and a system controller
`194. The receive channel section 100 comprises an RF-to-IF
`downconverter 102 which is coupled to a receive antenna, a
`digitizer 104 coupled to the downconverter 102, a plurality
`
`of IF-to-baseband downconverters 110, 112 and 114 each
`asSociated with a particular communication protocol, and a
`plurality of protocol detectors 120, 122, 124 each associated
`with a particular communication protocol.
`0045. In the transmit channel section 150, there is an
`IF-to-RF upconverter 152, a digital-to-analog converter 154,
`an adder 156, a plurality of baseband-to-IF upconverters
`160, 162 and 164 each associated with a particular commu
`nication protocol and a plurality of modulators each 170,
`172 and 174 each associated with a particular communica
`tion protocol. Thus, for each communication protocol, there
`is a detector in the receive channel section 100 that performs
`the decoding of the baseband digital Signal according to the
`rules of that communication protocol, and in the transmit
`channel section 150, there is a modulator that performs the
`encoding of the baseband digital Signal according to the
`rules of that communication protocol.
`0046) For each protocol, the MPD 12 has a MAC block
`180, 182 and 184. A network access arbitration controller
`(NAAC) 190 is coupled to the MAC blocks 180, 182 and
`184. A voice processor 192 is coupled to the NAAC 190 to
`process digital voice data. (A video processor or any other
`Special application processor may also be included in the
`MPD12 as would appreciated by those in the art.) A system
`controller 194 is coupled to the voice processor 194. The
`system controller 194 provides high level control function
`ality. For example, the system controller 194 can measure
`activity on one or more communication protocols in the
`network by monitoring Signal energy in a frequency band of
`a particular or several communication protocols. Moreover,
`the System controller 194 can generate signals that represent
`a measure of a level of a signal. Many of the elements shown
`in FIG. 2, including the MAC blocks 180-184, voice pro
`cessor 192, NAAC 190 and system controller 194 are
`Software processes that are executed by one or more digital
`processing chips, either of an application Specific variety or
`a general processing variety. The interference mitigation/
`collision avoidance procedures described herein are
`executed by the NAAC 190. However, it should be under
`stood that other elements shown in FIG. 2 may share
`responsibility or perform the processes described herein.
`Moreover, the logic to perform the interference avoidance
`algorithms described herein can alternatively be embodied
`by one or more controllers configured or programmed (with
`Software instructions or firmware), Such as one or more
`general purpose processors or application specific integrated
`circuits (ASICs). Alternatively, the logic to perform the
`interference avoidance algorithms described herein can be
`embodied as a Software product Stored on a processor
`readable memory containing instructions that, when
`executed by a processor, cause the processor to perform the
`Steps of the various algorithms described herein.
`0047 The precise location or component that performs
`the processes is not material to the invention. In Some cases,
`Such as the notch filtering procedures, the interference
`mitigation procedures involve tapping Signals at the output
`of one or more other elements in the receive section 100 or
`transmit Section 150. Depending on design considerations,
`Some components or functions may be implemented with
`analog signal designs, Such as the upconverters and down
`converters. On the other hand, digital Signal filtering tech
`niques may be desirable, but not required, Such as in the case
`of notch filtering procedures described hereinafter.
`
`DELL
`EXHIBIT 1004 - PAGE 26
`
`

`

`US 2002/0061031A1
`
`May 23, 2002
`
`0048. With reference to the configuration shown in FIG.
`3 in which an MPD communicates with node A (NA) and
`node B (N). NA and N use WLAN technologies (wireless
`communication protocols) A and B, respectively. NA is
`located a distance of RA from the MPD; N is located a
`distance of R from the MPD. The MPD is shown in the
`FIG.3 to be connected to a wired network. In this example,
`the MPD is acting as a hub node with respect to protocol A
`and a hub node with respect to protocol B in the same
`frequency band.
`0049. Without loss of generality, the spectrum of wireless
`communication protocol A is assumed to occupy a greater
`bandwidth than that used by WireleSS communication pro
`tocol B, as shown in FIG. 4. The transmit power of protocol
`Signal A and protocol Signal B may also be different.
`Protocol Signals A and/or B may be frequency-hopped
`throughout their allocated frequency band, and occasionally
`overlap in frequency.
`0050 Protocols A and B are further assumed to use a
`Time-Division Duplex (TDD) format, which typically
`results in a half-duplex mode of operation for each between
`the MPD and its nodes. As shown in FIGS. 5A and 5B, the
`nominal packet duration for communication protocol A is
`PA. The minimum time between transmissions is GA. Simi
`larly, the nominal packet duration for WLAN technology B
`is PB, and the minimum time between transmissions is G.
`0051
`Interference occurs when two or more communi
`cation protocol Signals overlap in time and frequency. The
`term collision is often used to describe the case where two
`or more Signals attempt to occupy a common medium at the
`same time. As shown in FIGS. 6, 7 and 8 there are 3 general
`types of interference problems. (1) Downlink A-Downlink B
`(FIG. 6) occurs when the MPD wishes to transmit to NA and
`NE at the same time and protocol Signals A and B at least
`partially overlap in spectrum. (2) Uplink A-Uplink B (FIG.
`7) occurs when the MPD wishes to receive signals from NA
`and N, where protocol Signals A and B at least partially
`overlap in spectrum. (3) Downlink A-Uplink B (FIG. 8)
`occurs when the MPD wishes to transmit a signal to NA
`while receiving a signal from N, where both transmit and
`receive Signals at least partially overlap in Spectrum. A
`fourth case, Downlink B-Uplink A, is similar to (3).
`
`1.1 Downlink A-Downlink B
`0.052 When the spectrum of transmitted protocol signals
`A and B are non-overlapping, the MPD can deliver downlink
`protocol signals A and B to NA and N, respectively, with no
`interference. When the Spectrum of protocol Signal A over
`laps with that of B, conventional transmission techniques in
`which protocol signals A and B are transmitted without
`regard for the other will result in interference to both
`systems. With reference to FIG. 9, one method of commu
`nications that maximizes aggregate downlink throughput is
`to apply a notch filter 200 to the wider bandwidth protocol
`Signal Ato first remove the Spectral energy of protocol Signal