United States Patent
`US 6,560,443 B1
`(10) Patent No.:
`(12)
`
`(45) Date of Patent: May6, 2003
`Vaisanen etal.
`
`US006560443B1
`
`(54) ANTENNA SHARING SWITCHING
`CIRCUITRY FOR MULTI-TRANSCEIVER
`MOBILE TERMINAL AND METHOD
`THEREFOR
`
`2002/0012381 A1 *
`2002/0025778 Al *
`
`1/2002 Mattisson etal.
`2/2002 Lee
`
`FOREIGN PATENT DOCUMENTS
`
`3/1992
`0 475 681 A2
`EP
`
`EP 0575 203 Al=12/1993
`(75)
`Inventors: Ari Vaisanen, Ruutana (FI; Pekko
`EP
`0623967
`11/1994
`Orava, Tampere (FI)
`EP
`0 641 090 A2
`1/1995
`EP
`0866588
`9/1998
`
`(73) Assignee: Nokia Corporation, Espoo (FI)
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/321,824
`
`(22)
`
`Filed:
`
`May 28, 1999
`
`TInt, C07 eee ecceeseeeeeeereeesersereensensenses HO04B 1/38
`(SL)
`(52) U.S. Ch. once 455/73; 455/82; 455/552
`(58) Field of Search oo... eee 455/552, 553,
`455/101, 103, 73, 129, 277.1, 289, 550,
`78, 133, 82, 182; 375/220, 219
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`8/1988 Maile 0... ee 455/82
`4,761,822 A *
`1/1994 Kuisma
`5,276,920 A
`4/1995 Mud Rienketal.
`5,410,738 A
`5/1995 Erkocevic
`5,420,599 A
`............ 343/702
`5,463,406 A * 10/1995 Vannatta et al.
`5,507,035 A *
`4/1996 Bantz et al... 375/299
`5,550,554 A
`8/1996 Erkocevic
`5,715,525 A *
`2/1998 Tarusawaetal. ........... 455/101
`5,768,691 A
`6/1998 Materoetal.
`5,794,159 A
`8/1998. Portin
`5,822,693 A * 10/1998 Harrison ........... ee 455/432
`we. 370/342
`5,982,807 A * 11/1999 Snell
`.........
`
`
`5,987,033 A * 11/1999 Boeretal. ....
`.. 370/313
`
`6,005,524 A * 12/1999 Hayes et al... 343/702
`wee 455/277.1
`6,055,422 A *
`4/2000 Saitoh ..........
`6,138,010 A * 10/2000 Rabe et al. 0... 455/426
`6,326,926 B1 * 12/2001 Shoobridge et al.
`........ 343/702
`2001/0012282 Al *
`8/2001 Yegoshin
`
`OTHER PUBLICATIONS
`
`NECPublication No. P12398EJ2V1DS00 (Second Edition),
`“L-Band SPDT Switch”, Jan. 1998.
`
`* cited by examiner
`
`Primary Examiner—Charles N. Appiah
`(74) Attorney, Agent, or Firm—Antonelli, Terry, Stout &
`Kraus, LLP
`
`(57)
`
`ABSTRACT
`
`Antenna switching circuitry in a multi-transceiver mobile
`terminal 10, which features a first switching unit (SW1)
`which controllably couples a first transceiver port (P,) to
`either a first antenna port (P4,) or a second antenna port
`(P42); and a second switching unit (SW2) which controlla-
`bly couples the second antenna port (P,.,) to either the first
`transceiverport (P,), through the first switching unit (SW1),
`or to an input/outputport (P,,,) of a second transceiver (12).
`According to this scheme,
`the second antenna port
`is
`coupled to the input/output port of the second transceiver
`(12) in a mode in which the second transceiver (12) is
`operational, the first transceiver port (P,) being decoupled
`from the second antenna port at this time, wherein thefirst
`transceiver port is coupled to the first antenna port and the
`input/output port of the second transceiver (12) is decoupled
`from the second antenna port, whenthefirst transceiveris in
`a transmit mode, and wherein the first transceiver port is
`coupledto either of the first and second antenna ports, when
`the first transceiver (11) is in a receiving mode and the
`input/output port of the second transceiver (12) is decoupled
`from the second antenna port.
`
`42 Claims, 4 Drawing Sheets
`
`SAMSUNG 1018
`
`
`
` 1
`
`CONTROL
`CIRCUIT
`
`SAMSUNG 1018
`
`1
`
`

`

`U.S. Patent
`
`May 6, 2003
`
`Sheet 1 of 4
`
`US 6,560,443 B1
`
`
`VV
`
`ANT 2
`
`HIG. 2
`
`‘IT controt
`!
`Po CIRCUIT
`
`“23
`
`2
`
`

`

`U.S. Patent
`
`May 6, 2003
`
`Sheet 2 of 4
`
`US 6,560,443 B1
`
`MG. SA 31
`
`32 a SWBVC1
`
`34
`
`33
`
`“
`
`SWBVC2
`
`SWCVC1
`SWCVC2
`
`SWAVCI
`
`TR
`ANTSEL
`
`BTSEL
`
`TR
`
`TRX ———_______—__— Swavc2
`
`FIG. 3B
`
`
`
`FIG. 3C
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`|oo|0)|PORTSISOLATED_|1,2AND3
`
`|0|1}PORT1-PORT3,PORT2ISOLATED_|
`
`
`|1|0|PORT1-PORT2,ISOLATED_|PORTS
`
`
`
`
`
`
`3
`
`

`

`May6, 2003
`
`Sheet 3 of 4
`
`US 6,560,443 B1
`
`
`
`
`
`YMSHOLIMSVNNALNVOLDONIGAAS
`
`U.S. Patent
`
`
`
`
`
`OvOMSHOLIMSVNNALNVOLONIGASS
`
`VO
`
`ov
`
`7SV
`
`
`
`ANV1dGNNOWDSVONILOVCISIHSOTIVLSN
`
`4
`
`

`

`U.S. Patent
`
`May6, 2003
`
`Sheet 4 of 4
`
`US 6,560,443 B1
`
` LASSOIAdSS
`
`
`NoLLWisg}|NOILLVLSNOILVLS
`YAAYSSL$SOIAdSAS
`NISVANOILVLS
`
`INIOd|j393SS3O00VsssooV|”Sasa
`INIOd
`
`CSQNSLX4
`
`5OW
`
`
`
`WALSASNOILNGIELSIC
`
`NOILVLS
`
`5
`
`

`

`US 6,560,443 B1
`
`1
`ANTENNA SHARING SWITCHING
`CIRCUITRY FOR MULTI-TRANSCEIVER
`MOBILE TERMINAL AND METHOD
`THEREFOR
`
`FIELD OF THE INVENTION
`
`to the field of
`This invention relates, generally,
`telecommunications/mobile terminals, such as mobile
`phones and the like and, more particularly, it relates to an
`antennae sharing scheme for diversity antennae in a dual-
`radio hand-held terminal such asIP (Internet Protocol) based
`WLAN (Wireless Local Area Network)/BT (Bluetooth)
`hand-held terminal.
`
`BACKGROUND OF THE INVENTION
`
`Recently, a new technology has been developing which
`can expand the use of mobile phones in related hand-held
`mobile terminals using the same 2.4 GHz ISM (Industrial,
`Scientific and Medical) band as that employed by wireless
`LAN (WLAN) communication which conforms to the IEEE
`802.11 standard such as for DSSS (Direct Sequence Spread
`Spectrum) radio communication, the contents of which are
`incorporated herein by reference. This new technology is
`referred to as Bluetooth (BT) which is a low-powered radio
`technology, having a range of approximately 10 cm to 10 m,
`but can be extended for greater distances through simply
`increasing the transmit powerlevel. The frequency band of
`this new technology calls for an ISM radio band at 2.4 GHz,
`whichis a license-free spectrum band,practically, available
`worldwide and which conforms to the wireless LAN
`(WLAN)radio ISM band conforming to IEEE 802.11 stan-
`dard for DSSS radio communication. Employmentof this
`low power/lower range ISM band to mobile phone technol-
`ogy would mean that cable hook-ups would no longer be
`required between laptop computers and cellular (or cell)
`phones to send E-mail, as one example. Further, business
`people would be able to surf the internet on their laptop,
`while their mobile phone is in their jacket pocket. That is,
`the mobile phone, as one example of a mobile terminal, will
`no longer haveto be limited to a basic service set (BSS) link,
`which typically consists of a numberof stations executing
`the same MAC (Medium Access Control) protocol in com-
`peting for access to the same shared medium. (The basic
`service set may be isolated or it may be connected to a
`backbone distribution system through an access point, the
`access point functioning as a bridge. The MACprotocol may
`be fully distributed or controlled by a central coordinated
`function housed in the access point. The basic service set
`generally corresponds to what is referred to as a cell in the
`literature. An extended service set (ESS) consists of two or
`more basic service sets interconnected by a distribution
`system. Such distribution system is, typically, a wired back-
`bone LAN. The extended service set appears as a single
`logical LAN to the logical link control (LLC) level. FIG. 5
`of the drawings typifies a wireless LAN model conforming
`to the IEEE 802.11 standard.)
`In a WLAN link-up, a single access transceiver can
`support a small group of co-located users within a range of
`less than one hundred to several hundred feet, typically. On
`the other hand, Bluetooth technology will enable users to
`connect
`their mobile computers, digital cellular phones,
`hand-held devices, network access points and other mobile
`devices by wireless short-range radio links, unimpeded by
`line-of-site restrictions using substantially less power. Blue-
`tooth (BT) technology will increase the ease of wireless
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`communication by the ordinary citizen, as well as the scope
`of wireless connectivity. Also, since BT is limited to short
`range communication,
`typically, under 10 meters,
`for
`example, 2-3 meters, it uses a considerably lower power
`level than that of WLAN. Namely, for a mobile phone, a
`WLAN DSSSradio operating in the 2.4 GHz ISM band
`having 30-50 meter range, for example, would typically
`require about 100 mW power level, whereas a BT ISM
`FHSS (Frequency Hopping Spread Spectrum) radio or,
`simply, a BT ISM spread spectrum radio would require
`about 1 mW powerlevel. This technology enables portable
`electronic devices to connect and communicate wirelessly
`via short range, ad hoc networks.
`In order to function on a worldwide basis, Bluetooth
`requires a radio frequency that is license-free and open to
`any radio. The 2.4 GHz ISM bandsatisfies these
`requirements, the 2.4 GHz bandactually being 2.4-2.483
`GHz radio band. When a Bluetooth radio is applied to a
`mobile phone, the user can leave the mobile phone clipped
`to his belt or in a pocket and walk around for the entire
`dial-up-connection. Also, because there are no line-of-site
`requirements for Bluetooth devices,
`it
`is well suited for
`wireless connectivity, such as between a mobile phone and
`a notebook computer. For example, with Bluetooth, a person
`could synchronize their phone with a PC without taking the
`phoneout of their pocket or briefcase. Users would be able
`to automatically receive E-mail on their notebook or laptop
`computers by the digital cellular phones in their pockets or
`synchronize their primary PC with their hand-held computer
`without taking it out of their briefcase. The omni-directional
`capability of Bluetooth allows synchronization to start when
`the phone is brought into range of the PC. It allows for a
`gross data rate of 1 Mbit/S, with second generation plans to
`be increased to a ratio of 2 Mbit/second. It uses packets
`switching protocol based on a frequency hopping scheme
`(analogous to IEEE 802.11 standard). Also, because of its
`omnidirectionality, authentication and encryption is also
`included, for security reasons, as part of the base band
`protocol thereof. That is, authentication relies on utilizing a
`secret key (i.e., password or PIN), thereby assuring security.
`In view of the attributes of this low power ISM radio band
`and its relevance to mobile terminals, such as hand-held
`mobile (cellular) phones and the like, the present inventors
`have considered how to facilitate both the 2.4 GHz ISM
`
`band WLAN DSSSradio and the low power/short range 2.4
`GHz ISM BTradio to effect a practical and cost-effective
`dual mode mobile terminal, namely, an IP based dual mode
`WLAN/BT hand-held terminal. Filter, antennae and RF
`switch components of a WLAN IEEE 802.11 DSSS radio
`and BT dual mode terminal can be shared in a number of
`
`ways, the inventors determined. In its simplest form, such
`components are not shared, that 1s, both radios are imple-
`mented as separate and independent units. However,this is
`obviously not the optimal solution, both in termsof cost, as
`well as practicality. On the other hand, combining a low
`powershort range 2.4 GHz ISM radio band device like a BT
`radio and a substantially higher power level WLAN device,
`like the 802.11 DSSS radio, into a small sized hand-held
`terminal, has several drawbacks, namely,
`interference,
`resulting from sharing of antennae, filters and other com-
`ponents. In fact, sharing a diversity antennae scheme, filters
`and antennae switches between two 2.4 GHzradios in a dual
`
`mode terminal has not been implementedearlier, as far as
`known. Therefore, such problems had not existed in such a
`form, earlier. Dual band mobile phones have somewhat
`similar problems, but, however, as the two radios in the dual
`band mobile phone employ different frequency bands, dif-
`ferent approaches are used.
`6
`
`6
`
`

`

`US 6,560,443 B1
`
`3
`The present invention specifically addresses the issue of
`antennae sharing between two 2.4 GHz radios in a dual
`mode terminal such as would be effected in connection with
`an IP based dual mode WLAN/BThand-held terminal. The
`present inventors are not aware of any earlier attempts at
`effecting antennae sharing in such a dual mode terminal. On
`the other hand, the inventors are aware of several earlier
`attempts at diversity antennae sharing, but, however, only
`with regard to a standard WLAN operation. One such known
`earlier scheme was disclosed by Lucent Technologies in EP
`0 623 967 Al, dated Nov. 9, 1994, which describes dual
`antennae diversity system for wireless LAN consisting of
`two L-shaped PIFA antennae. In that disclosure, a single
`pole dual terminal switch (SPDT) is employed to effect
`switching between the two antenna members in a receive
`mode and for switching to only one of the two antenna
`members for operation of the apparatus in a transmit mode.
`However, that earlier disclosure did not address the issue of
`antenna sharing of diversity antennae in a dual mode scheme
`which calls for a common radio band such as two 2.4 GHz
`radios, one being a WLAN radio conforming to the IEEE
`802.11 standard, referred to above, the contents of which are
`incorporated herein by reference, and the other being a
`relatively low power/low range radio, for example, a BT
`ISM FHSSradio.
`
`Aslightly different antennae switch andfilter arrangement
`of a WLAN radio, with no detailed antennae description,
`was disclosed by Harris Corporation in EP 0 866 588 A2,
`dated Sep. 23, 1998. This published application also does
`not disclose anything about an antennae sharing scheme of
`diversity antennae in a dual mode hand-held terminalas that
`to which the present
`invention addresses. However,
`the
`Harris disclosure does give an example of one wireless
`transceiver which may be readily used for WLAN applica-
`tions in the 2.4 GHz ISM bandaccording to the IEEE 802.11
`standard for DSSS radio communication. Use of two diver-
`
`in WLAN PCcards
`sity antennae, for example, PIFAs,
`(previously known as PCMCIA card)
`is very popular
`because of multi-path propagation problems, while prior
`hand-held terminals operating on lower frequencies do not
`use diversity antennae.
`
`4
`spectrum radio operating on a substantially same ISM radio
`band as that of the WLAN radio. In this connection, this
`second lower power and shorter range radio can be one
`conforming to Bluetooth (BT) radio communication.
`It
`is an additional object
`to implement an antennae
`switching scheme for antennae sharing of diversity antennae
`in the dual mode mobile terminal scheme which is both
`
`economical and practical and which can be implemented
`without having to add an additional antenna for the second
`transceiver.
`
`10
`
`It is still a further object of this invention to achieve an
`antennae sharing scheme in connection with a dual mode
`hand-held mobile terminal or hand-held terminal per se
`which can be implemented in a standard mobile terminal
`such as a mobile (cellular) phone and the like, a PDA
`(personal digital assistant), as well as other wireless com-
`munication links that can operate on an ISM radio band such
`as the 2.4 GHz DSSS WLAN conforming to the [EEE
`802.11 standard, as one example (although not
`limited
`thereto).
`It is also an object of the present invention to overcome
`any inherent problem directed to antennae sharing, antennae
`switching and pertaining to the filter chains associated with
`a WLAN/BTdual mode hand-held terminal, as one example,
`although not limited thereto. It is a still further to achieve an
`antennae sharing scheme which provides high performance
`in connection with the dual antennae receive mode of the
`
`diversity operation.
`It is also an object of the present invention to minimize the
`number of RF switches and at the same time minimizing
`switch losses for purposes of optimizing performance during
`operation of either one of the transceivers (radios) in the
`mobile terminal.
`
`SUMMARYOF THE INVENTION
`
`The foregoing and other problems are overcome and the
`objects of the invention are realized through effecting anten-
`nae switching circuitry and antennae sharing methodthere-
`for for a multi-transceiver mobile terminal in accordance
`with the examples illustrated in the related embodiments of
`this invention.
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`OBJECTS OF THE INVENTION
`
`45
`
`50
`
`55
`
`It is a further object of invention to achieve a substantially
`interference-free antenna sharing scheme in the multi-
`transceiver mobile terminal where one of the transceivers is
`
`a WLANradio and the other operates on substantially the
`same ISM radio band.
`
`60
`
`In this connection the invention calls for a switching
`scheme for diversity antennae in a multi-transceiver mobile
`It is an object of this invention to realize an antennae
`terminal where one such transceiver may be a WLAN
`switching scheme for sharing diversity antennae efficiently
`conforming to the IEEE 802.11 standard for DSSS radio
`and as economically as possible.
`communication and the other may bearelatively lower
`It is also an object of this invention to effect a substan-
`power/lower range radio operating on the same ISM radio
`tially interference-free switching circuitry for sharing a pair
`band as the WLAN such as conforming to Bluetooth radio,
`of diversity antennae in a multi-transceiver mobile terminal
`although not
`limited thereto.
`In accordance with this
`such as a hand-held mobile terminal including, for example,
`scheme, the dual transceivers are not required to operate at
`mobile or cellular phones, although not limited thereto, in
`the same time. The dropping of an antennae connection and
`which both transceivers operate, substantially, on the same
`the setting up of a new antenna connection from scratch, of
`ISM radio band but having different power/range require-
`course, takes time and requires electrical power. Therefore,
`ments.
`one featured aspect of the invention permits the first
`transceiver, for example,
`the WLAN radio,
`to act as a
`receiver only, including, for example, to monitor when the
`AP (access point) directed thereto becomes available for
`communication while the second transceiveris providing a
`needed connection,1.e., is operational. The present invention
`is achievable through using only the standard diversity
`antennae of the WLAN network of the mobile terminal.
`
`It is a still further object of this invention to achieve a
`substantially interference-free antennae sharing scheme in
`connection with a hand-held mobile terminal having diver-
`sity antennae for a dual mode mobile terminal having a
`WLAN radio operating on substantially a 2.4 GHz ISM band
`conforming to IEEE standard for DSSS radio communica-
`tion and a relatively low power and short range spread
`
`65
`
`According to a further aspect of the present invention,
`both the first and second transceivers, such as the WLAN
`and BT radios, are able to receive RF signals at the same
`time such as when the hand-held terminal is powered-up or
`in a situation where neither of the radios are connected,
`
`7
`
`7
`
`

`

`US 6,560,443 B1
`
`6
`is disclosed in NEC publication document No.
`P12398EJ2V1DS00 (second edition), dated January 1998,
`the contents of which are incorporated herein by reference.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above set forth and other featured aspects of the
`invention are made more apparent in the ensuing detailed
`description of the invention when read in conjunction with
`the related examples described and illustrated in the accom-
`panying drawings, wherein:
`FIG. 1 is a schematic diagram illustrating the principle of
`the antenna sharing switching arrangementaccording to one
`embodiment of the present invention;
`FIG. 2 is a diagram illustrating the antenna sharing
`switching arrangement according to another representative
`embodiment of the present invention;
`FIG. 3A illustrates an example of a logic circuit diagram
`relating to the control circuit according to FIG. 2;
`FIG. 3B isillustrative of an example of signal descriptions
`associated with the antenna switch control logic arrange-
`ment in FIG. 3A;
`FIG. 3C is illustrative of an example of the antennae
`switch truth table as it relates to the embodimentin FIG. 2
`of the drawings;
`FIG. 4 illustrates an antenna system consisting of two
`high efficiency PIFA-type rectangular antennae, which are
`useable in the antenna sharing scheme of the present
`invention, according to one example; and
`FIG. 5 represents a WLAN standard developed by the
`IEEE 802.11 committee.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`5
`although a connection may be needed. The versatility of the
`mobile phoneeffects integration (i.e., connectivity) between
`mobile computers, digital phones, network access points
`within a short range scheme.
`Although there are some minor drawbacksresulting from
`losses when switching from the second antenna, which is a
`diversity antenna shared between WLAN and Bluetooth, for
`example, the benefits arising as a result of using the low
`powered/low range Bluetooth radio, clearly, outweigh any
`such drawbacks. In this connection, the present invention
`features a schemein which one of the two WLAN diversity
`antennae is switched for Bluetooth radio use when the
`Bluetooth radio needs to be functional.
`In general,
`the
`second transceiver, for example,
`the Bluetooth radio,
`is
`connected to the antenna port assigned thereto when the
`mobile terminal is physically outside the coverage area of
`the WLAN radio. Since the WLAN radio would typically be
`the preferred choice of communication linkage, in a mobile
`terminal where one of the transceivers is a WLAN and the
`other is a BT radio, the WLAN coverage can be monitored
`during the time the second transceiver, for example,
`the
`Bluetooth radio, is in use. During this time, the first trans-
`ceiver is coupled at its receiver port to the first antenna
`monitoring an access point (AP), the access point becoming
`available through that one of the diversity antennae whichis
`not being used by the Bluetooth radio.
`Also in accordance with the present invention, it becomes
`possible for the first transceiver, for example, the WLAN
`radio, to receive or monitor its frequency band without being
`destructively interfered with by the transmitted signal from
`the BT module, since the BT module requires, typically, one
`milliwatt or less power level. However, use of the WLAN
`transmitter while the BT radio is operational is prohibited as
`damages to the BT radio might occur.
`With regard to the question of diversity isolation during
`simultaneous operation of the two antennae, this isolation
`could be improved with a metallic structure connected as a
`shield and located between the antennae. That is, according
`to one featured aspect of the invention, the mobile terminal
`includes a pair of diversity antennae which are separated
`with a metallic structure, for example, a metallic plate
`attached to a ground plane and providing improvedisolation
`to effect rf shielding. According to one disclosed
`embodiment, although not
`limited thereto,
`the invention
`calls for each of the antennae to be a planar inverted F
`antenna (PIFA). The PIFAs can be rectangular(inclusive of
`both square and oblong shaped rectangles) or even
`L-shaped, although not limited thereto. In this connection,
`the present invention has been schemed to enable optimal
`sharing of antennae and filter chains associated with the
`transceivers between that of the transmit and receive modes
`of two like ISM band radios such as the 2.4 GHz WLAN
`
`40
`
`45
`
`50
`
`FIG. 1 illustrates the principle of the present invention in
`accordancewith a first embodimentof the present invention
`in which 10 represents as mobile terminal such as a mobile
`(cellular) phone having a dual antenna, dual transceiver
`arrangement which can be,
`for example, an IP-based
`WLAN/Bluetooth hand-held terminal. The basic idea is to
`switch one of the two WLAN diversity antennae ANT1 and
`ANT2 for BT (Bluetooth) use, when BT needs to be func-
`tional.
`In general, BT connection is effected when the
`hand-held terminal is located outside the available coverage
`of WLAN. As the WLAN radio communication is the
`preferred method, WLAN coverage of an AP (accesspoint)
`can be constantly monitored, while the BT radio (BT
`module) 12 is in use. Simultaneous operation is limited to
`the receive (rx) mode of the WLAN radio (WLAN module)
`11 when the BT radio (BT module) 12 is operational, either
`in the receive (rx) or the transmit (tx) mode, in order to
`protect the BT transceiver from permanent damage.
`radio according to IEEE 802.11 standard for DSSS radio
`Specifically, the antennae switching circuitry 13 in the
`communication, and the 2.4 GHz BT spread spectrum radio,
`55
`
`for dual mode mobile terminal implementation. The RF multi-transceiver mobile terminal 10 hasafirst switching
`switches employed are illustrated, for example, as single
`unit SW1 which controllably couples the first transceiver
`pole double throw (SPDT) switches which are of well
`port P, to eithera first antenna port P,, or a second antenna
`known variety which can be implemented in connection
`port P,5, and has a second switching unit, namely, SPDT
`with a single RF chip or each can be associated with a
`switch SW2, which couples the second antenna port P,., to
`separate semiconductor chip. In this connection,it is noted
`either the first transceiver port P,, through thefirst switching
`that both EP 0 623 967 Al and EP 0 866 588 A2 disclose
`unit SW1, or to an input/output port P,4 of a second
`transceiver 12 whichis,in this example, a BT radio having,
`substantially, a same ISM radio band as that of the WLAN
`module 11, such as, for example, a 2.4 GHz ISM band
`WLAN radio according to IEEE 802.11 standard for DSSS
`radio.
`In accordance with this embodiment,
`the SPDT
`switches SW1 and SW2are controlled by the control circuit
`8
`
`SPDTs; however, those SPDTs are employed for switching
`between the receive and transmit modes of a WLAN radio
`(single transceiver). An example of an SPDT switch usable
`in the present invention is the NEC hPG/52TA L-band SPDT
`(Single Pole Double Throw) GaAs FET switch which was
`developed for cellular or cordless telephone application and
`
`60
`
`65
`
`8
`
`

`

`US 6,560,443 B1
`
`7
`14 in a manner in which the second antennae port P,. is
`coupled to the input/output port of the second transceiver 12
`in a modein which the secondtransceiver 12 is operational,
`at which time, also,
`the first
`transceiver port P,,
`is
`decoupled from the second antennaport P,,. Also, the first
`transceiver port P, is coupled to the first antenna port P,,
`and the input/output port of the second transceiver 12 is
`decoupled from the second antennae port P,,, whenthe first
`transceiverport is in the transmit mode, and, further,the first
`transceiverport P, is coupled to eitherofthe first and second
`antennae ports, when the first transceiver is in a receiving
`modeand the input/outputport P,,, of the second transceiver
`12 is decoupled from the second antenna port P,5. Also,
`according to this scheme, when the secondtransceiver 12 is
`operational, the second antennae port P,, is coupled to the
`input/output port of the second transceiver 12 and thefirst
`transceiver 11 is decoupled from the second antennaport P,,
`and is coupledto thefirst antenna port P,, as a receiveronly.
`Simultaneous operation, however,is limited to, for example,
`WLAN rx with BT on rx or tx only. The second transceiver,
`for example,
`the BT module, cannot operate if the first
`transceiver, for example, the WLAN module, is transmitting.
`This new scheme, according to the example illustrated in
`FIG. 1, provides for the implementation of an additional
`transceiver, such as the BT module 12, with the already
`existing first receiver, for example, a WLAN radio,
`in a
`standard size mobile terminal, without adding an additional
`antenna for the newly added BT module. Since an antennae
`diversity scheme would be preferable in connection with a
`2.4 GHz ISM band WLAN device like IEEE 802.11 stan-
`
`dard for DSSSradio communication to overcome multi-path
`propagation, using one of the two separate diversity anten-
`nae for occasional BT use saves the cost and space of adding
`yet another antennae to a standard size hand-held mobile
`terminal unit.
`FIG. 2 is illustrative of another embodiment which shows
`an antennae sharing switching arrangement for a multi-
`transceiver mobile terminal such as, although not limited
`thereto, an IP based dual mode WLAN/BT hand-held ter-
`minal. In accordance with this example illustration of the
`present invention, 21 represents the first transceiver, for
`example, 2.4 GHz ISM band WLAN module or device
`according to the IEEE 802.11 standard for DSSS radio
`communication and 22 represents the added second trans-
`ceiver which is illustrated in this example, although not
`limited thereto, to a BT module.
`In the embodiment of FIG. 2, in the WLAN transmit
`mode, or the first mode,
`the third SPDT switch SwC is
`switched to the position 2 where it connects a second
`antenna port P,, to the second switch SwB. In this mode,
`also, the first switching unit SwA is switched from position
`3 to position 2 thereof to thereby form a connection to the
`output port P, of the WLAN module. Under this WLAN
`transmit mode, only antenna ANT1 is used as the WLAN
`transmit antenna. The second switching unit SwB is
`switched to the position where it connects the WLAN
`receive chain at the input port P, to the unconnected port 3
`of switch SwA so as to prevent the WLAN transmit signal
`which is coupled from the first antenna ANT1 to the second
`antenna ANT2 from leaking into the WLAN receive chain.
`Filter FL2 in the WLAN transmit chain can be optimally
`chosen therefor for best performance since it does not have
`to be shared with the WLAN receive chain under this
`
`operation mode.
`According to a second mode, namely, the BT mode, the
`third switching unit SwC is switched to a position 3 where
`it connects the BT module to the second antenna port P,».
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`60
`
`65
`
`8
`In this BT mode, the second switching unit SwB switchesto
`the position 3 where the WLAN receive chain, including
`filter FL1 is connected to the first switching unit SwA in
`order to minimize leakage of the BT transmit signal into the
`receiver port of the WLAN module. In this BT mode, the
`WLAN coverage can be monitored by switching SwAto a
`position 3 where it connects the first antenna port to the
`WLAN receiver chain via second switching unit SwB.
`In accordance with a third mode, namely,
`the WLAN
`receive mode, the third switching unit SwC is switched to a
`position where the second antenna port P,, is coupled to
`switch SwB. Also, first switching unit SwA is switched to a
`position where it connects the first antenna port P,, to
`switch SwB. Through turning of the second switching unit
`SwBantenna, diversity selection can be made between the
`first and second antennae ports. Filter FL1 in the WLAN
`receive chain can be optimally chosen for best performance
`as it does not have to be shared with the WLAN transmit
`chain.
`
`The operation of the example in FIG. 2, of another
`embodiment according to the present
`invention, can be
`clearly understood in connection with the signal description
`and the switch truth table schemes shown in FIGS. 3B and
`
`3C of the drawings, respectively, in conjunction with the
`antennae switch logic operation effected by the logic cir-
`cuitry shown in FIG. 3A of the drawingsasit relates to the
`control circuit 23 in FIG. 2 thereof. In this connection, when
`the logic values of VC1 and VC2 asthey relate to each of
`the three switching units, are at logic 0, all three ports of the
`SPDTswitchesare isolated. This is similarly the case when
`the logic values of VC1 and VC2 are both at 1. On the other
`hand, when VC1 of each switch is at logic 0 and VC 2 of
`each switch is at logic 1, a connection is effected between the
`second antennaport and the BT module, and a connectionis
`effected between the receiver port of the WLAN module and
`the first antenna port. Whenthe logic levels of VC1 and VC2
`are reversed, the WLAN module is in the transmit mode.
`Using the antennae schemes shown in FIG. 4 of the
`drawings, as an example, 40 represents the metallic shield
`that acts as a ground plane, 41 and 42 are square/rectangular
`shaped PIFA antennae to be used, although not
`limited
`thereto, in the examples in FIGS. 1 and 2, 43 and 44are the
`connecting terminals of the respective PIFA antenna to the
`switching units SwA and SwC, respectively, 45 and 46
`represent the ground terminal connections of the antennae
`and 47, provided optionally, is a metallic plate attached to
`ground plane 40 and providing improvedisolation to effect
`shielding between PIFAs 41 and 42. Although the antennae
`illustrated in FIG. 4 are square-shaped rectangles,
`this
`should not be considered as being limited thereto. Other
`shapes including other rectangular shapes (e.g., elongated)
`and even L-shaped planar antennae are applicable to the
`present invention, either in connection with the embodi-
`ments in FIGS. 1 and 2 or in connection with other example
`embodiments relating to the present invention. With regard
`to FIG. 2, moreover, in the BT mode, the square shaped PIFA
`antenna ANT2 is connected to the BT module and the
`square-shaped PIFA antenna ANTI is connected to the
`WLAN receiver to enable the monitor