1111111111111111 IIIIII IIIII 11111 1111111111 111111111111111 IIIII IIIII IIIII IIIIII IIII 11111111
`US 20060172769Al
`
`c19) United States
`c12) Patent Application Publication
`Oh
`
`c10) Pub. No.: US 2006/0172769 Al
`Aug. 3, 2006
`(43) Pub. Date:
`
`(54) RADIO COMMUNICATION SYSTEM
`
`(52) U.S. Cl. ......................... 455/557; 455/41.2; 455/558
`
`(76)
`
`Inventor: Waho Oh, Chiba (JP)
`
`Correspondence Address:
`BIRCH STEWART KOLASCH & BIRCH
`PO BOX 747
`FALLS CHURCH, VA 22040-0747 (US)
`
`(21) Appl. No.:
`
`10/540,930
`
`(22) PCT Filed:
`
`Apr. 12, 2004
`
`(86) PCT No.:
`
`PCT/JP04/05210
`
`(30)
`
`Foreign Application Priority Data
`
`Apr. 11, 2003
`
`(JP) ...................................... 2003-107879
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`H04B 1138
`
`(2006.01)
`
`(57)
`
`ABSTRACT
`
`The system includes: a first mobile communication terminal
`(100) (e.g., portable information terminal) having one or
`more first wireless LAN interfaces (30,31) of wireless LAN
`client function; and a second mobile communication termi(cid:173)
`nal (200) (e.g., cellular phone) having a second wireless
`LAN interface (18, 19) having a wireless LAN access point
`or wireless LAN client function. When the user is in a
`wireless LAN hotspot area (32), the user makes wireless
`LAN access using the first mobile communication terminal
`(100). When the user is located at the boundary of the
`wireless LAN hotspot area (32), wireless access is kept
`automatically by way of the second mobile communication
`terminal (200). In this way, it is possible to enjoy the merits
`of both the mobile communication system and the wireless
`LAN system.
`
`400
`
`33
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 1 of 6
`
`US 2006/0172769 Al
`
`F/6. 1
`
`400
`
`F/6. 2
`
`33
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 2 of 6
`F/6. 3
`73
`
`70
`
`71
`
`72
`
`US 2006/0172769 Al
`
`Wireless LAN
`switching
`means
`
`Communication Connection
`request
`status
`detecting
`transmitting
`means
`means
`Processor unit
`
`••
`
`11
`
`I
`
`I
`
`I
`
`I
`
`I
`
`I
`
`100
`77
`76
`30
`1----174 ---- _( ------( --- (
`r-------!:._ .. 1e-b,-.
`:Wireless:'.)/:
`:,---- ------~
`, , ,
`,
`•· Card
`LAN
`~ I
`:
`:: Interface:
`i-· :
`t
`d
`,
`: a ap er ,
`, ·-----------
`I
`-----------1
`I
`'----- -------- -----------------•
`
`78
`
`79
`
`Display/
`input unit
`Notebook PC
`
`Memory
`unit
`
`Wireless LAN
`interface .__..___,
`
`80
`
`31
`
`81
`
`F/6. 4
`
`13
`
`Display/input unit
`
`10
`
`I 11
`
`12
`
`W-CDMA
`Radio
`modem
`unit
`unit
`W-CDMA interface
`
`22
`
`Connection
`request
`receiving
`means
`Base station 23
`connecting
`means
`Application
`processor unit
`15
`FLASH
`SRAM
`1------carl ____ v 16
`---, Interface ~--
`~---------------•
`Wireless LAN
`interface
`18
`
`200
`
`14
`
`21
`19
`,.r--wrr~.-s-~
`: LAN adapter:-·
`·---------------
`17
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 3 of 6
`
`US 2006/0172769 Al
`
`200
`
`10 F/6. 5 17
`
`11
`
`12
`
`Antenna 1
`W-CDMA
`radio unit
`
`W-CDMA
`modem unit
`W-CDMA
`interface
`
`25
`
`Antenna 2
`
`Wireless
`LAN
`interface
`
`18
`
`14 22
`
`Interface controller
`
`23
`
`Base station
`Connection request
`connecting means
`receiving means
`Application processor unit
`
`13
`
`Display/input unit
`
`F/6. 6
`
`20
`
`30 1 41-------
`
`43
`
`44
`
`

`

`O'I
`0
`0
`N
`~
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`~
`.... 0 =
`""O = O" -....
`.... 0 =
`t "e -....
`
`> ....
`
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`rJJ
`c
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`
`transmitting means
`L.._ ________________________________ ___. Connection request
`
`S64
`
`S63
`
`connection request
`
`Transmit a
`
`signal
`
`-S62
`
`~ S61
`
`communication
`
`status
`
`Detect
`
`73
`
`switching means
`Wire I ess LAN
`
`No
`
`wireless LAN access point
`Switch to the alternative
`
`LAN interface 18
`Switch to wireless
`
`S66
`
`S68
`
`71
`
`s i gna I strength r--t-S60
`Detect received
`
`(RSS I)
`
`72
`
`detecting means
`Communication status
`
`F/6. 7
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 5 of 6
`
`US 2006/0172769 Al
`
`FIG. 8
`
`Start
`
`Connection request
`receiving means
`
`Receive a connection
`request signal
`
`S50
`
`22
`
`No
`
`Yes
`
`S55
`
`Ordinary e-ma i I
`process
`
`Establish W-CDMA
`connection
`
`S53
`
`23
`
`Activate the wireless S54
`LAN interface
`Base station
`connecting means
`
`End
`
`

`

`Patent Application Publication Aug. 3, 2006 Sheet 6 of 6
`
`US 2006/0172769 Al
`
`F/6. g
`
`91 -
`
`92
`
`9 3~
`
`5-9
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`9
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`
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`' 97
`
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`-1D:WLAN
`~PW: 12345678
`_.,,..
`
`-
`
`

`

`US 2006/0172769 Al
`
`Aug. 3, 2006
`
`1
`
`RADIO COMMUNICATION SYSTEM
`
`TECHNICAL FIELD
`
`[0001] The present invention relates a wireless connnuni(cid:173)
`cation system including: a first mobile connnunication ter(cid:173)
`minal ( e.g., portable information terminal) having one or
`more wireless LAN interfaces providing wireless LAN
`client function; and a second mobile connnunication termi(cid:173)
`nal ( e.g., cellular phone) having a wireless LAN interface
`providing the function of a wireless LAN access point or
`wireless LAN client function.
`
`BACKGROUND ART
`
`[0002] There have been wide area coverage data connnu(cid:173)
`nication services of some hundreds kilo bps, using a mobile
`communication system such as W-CDMA (Wideband Code
`Division Multiple Access), GSM (Global System for Mobile
`Connnunications), GPRS (General Packet Radio Service),
`cdma2000 or the like.
`
`[0003] There also have been high-speed local area cover(cid:173)
`age data connnunication services of some tens Mbps, using
`wireless LAN systems composing of multiple hotspots areas
`provided by wireless LAN access points (APs ).
`
`[0004]
`In using a wireless LAN system, in most cases,
`portable information terminals such as notebook PCs and
`PDAs (Personal Digital Assistant) having a wireless LAN
`adapter provided with wireless LAN client function, e.g.,
`card type wireless LAN adapters, including PCMCIA (Per(cid:173)
`sonal Computer Memory Card International Association)
`card, CF (Compact Flash) card, SD (Secure Digital) card
`and the like, or portable information terminals with a built-in
`wireless LAN function are used. In a wireless LAN hotspot
`area, a portable information terminal with a wireless LAN
`interface is used to access the internet or perform e-mail
`transmission and reception.
`
`[0005] On the other hand, in using a mobile connnunica(cid:173)
`tion system, mobile terminals capable of accessing the
`mobile connnunication system, e.g., W-CDMA cellular
`phone, PHS data connnunication card, etc., are used to make
`wireless access for voice connnunications and data connnu(cid:173)
`nications.
`
`[0006] Since, however, the mobile connnunication system
`and the wireless LAN system are available in only an
`independent manner, under the existing circumstances the
`user should make use of different wireless connnunication
`systems by handling different wireless connnunication ter(cid:173)
`minals.
`
`[0007] As the prior art relating to linkage of a cellular
`phone with a portable information terminal, connections
`between a cellular phone and a portable information termi(cid:173)
`nal using cables, infrared, or Bluetooth technology are
`known (see Japanese Patent Application Laid-open Hei
`10-56673, Japanese Patent Application Laid-open Hei
`10-285203, and Japanese Patent Application Laid-open
`2001-103568, for example).
`
`[0008] Now, comparing the service of the mobile connnu(cid:173)
`nication system of W-CDMA or the like with that of a
`wireless LAN system, both have some merits and demerits.
`Specifically, the mobile connnunication system has the
`merits of providing wide service area and also supporting
`
`high-speed travel but has the demerits of a high basic rate
`and being charged based on traffic usage, causing disadvan(cid:173)
`tage in downloading bulky data such as motion pictures,
`music, etc.
`
`[0009] On the other hand, a wireless LAN system has the
`advantage of realizing high speed data connnunication and
`the capability of using the service at a low cost or at a fixed
`price because the system architecture is simple. However, it
`also has the disadvantage of using a high frequency band
`with the necessity of a great amount of frequency resource
`(bandwidth) in order to realize high-speed data connnuni(cid:173)
`cation and the disadvantage of a limited or local service area
`(e.g., about some hundreds meters in a hotspot).
`
`[0010] With the development of enlargement of the cov(cid:173)
`erage areas of mobile connnunication services based on
`W-CDMA technology and others and enlargement of wire(cid:173)
`less LAN hotspot areas as well as the spread of inexpensive
`mobile terminals, many users have come to own both the
`W-CDMA cellular phone and the portable information ter(cid:173)
`minal having a wireless LAN interface in order to enjoy the
`merits of both of the wireless connnunication systems.
`Under these circumstances, there has been a demand for
`development of a device which can make the switch (han(cid:173)
`dover) between the different mobile connnunication systems
`by making use of wireless LAN interfaces provided for
`mobile terminals, in order to put both the wireless connnu(cid:173)
`nication systems to sufficient use.
`
`[0011]
`In sum, achievement of a high-speed, inexpensive
`wireless LAN service using a portable information terminal
`having a wireless LAN interface for a limited, wireless LAN
`access point area, installed at home, in an office, public area
`or the like, is wanted while provision of a wireless access
`environment that enables continuous internet access and
`e-mail transmission and reception using a W-CDMA cellular
`phone is desired when the user is out of the wireless LAN
`service area.
`
`[0012] The present invention has been devised in view of
`the above circumstances, it is therefore an object of the
`present invention to provide a wireless connnunication
`system which can enjoy the merits of both of the mobile
`connnunication system and the wireless LAN system.
`
`DISCLOSURE OF INVENTION
`
`[0013] The wireless connnunication system according to
`the present invention includes: a wireless LAN access point
`connected to a public wireless access network; a first mobile
`connnunication terminal connectable to the wireless LAN
`access point and having a first wireless LAN interface; and
`a second mobile connnunication terminal connectable to the
`public wireless access network, connectable to the first
`mobile connnunication terminal by way of the first wireless
`LAN interface and having a second wireless LAN interface,
`and is characterized in that the first mobile connnunication
`terminal includes: a connnunication status detecting means
`that detects the strength of the received signal from the
`wireless LAN access point and/or the status of connnuni(cid:173)
`cation with the wireless LAN access point; a connection
`request transmitting means for transmitting a connection
`request signal to the second mobile connnunication terminal
`by way of the wireless LAN access point and the public
`wireless access network when the connnunication status
`detecting means recognizes the necessity of connection to
`
`

`

`US 2006/0172769 Al
`
`Aug. 3, 2006
`
`2
`
`the second mobile communication terminal by way of the
`first wireless LAN interface and the second wireless LAN
`interface; and a wireless LAN connection switching means
`for establishing connection to the second wireless LAN
`interface of the second mobile communication terminal
`when the communication status detecting means determines
`that communication with the second mobile communication
`terminal by way of the second wireless LAN interface will
`be permitted, and the second mobile communication termi(cid:173)
`nal includes: a connection request receiving means for
`receiving the connection request signal; and a base station
`connecting means which establishes connection to the public
`wireless access network and validates the second wireless
`LAN interface upon reception of the connection request
`signal, so as to enable its connection with the first mobile
`communication terminal by way of the first wireless LAN
`interface and the second wireless LAN interface.
`
`[0014] With this configuration, in the case where the first
`mobile communication terminal resides in the mobile com(cid:173)
`munication system service area and is also located in a
`wireless LAN hotspot area, if it is determined by the
`communication status detecting means that the first mobile
`communication terminal has been in communication with
`the wireless LAN access point and needs to be connected to
`the second mobile communication terminal by way of the
`first wireless LAN interface and the second wireless LAN
`interface, the connection request transmitting means trans(cid:173)
`mits a connection request signal to the second mobile
`communication terminal via the wireless LAN access point.
`
`[0015] The wireless LAN switching means of the first
`mobile communication terminal determines the signal
`strength of each of the wireless LAN signals detected by the
`communication status detecting means, and establishes con(cid:173)
`nection to the wireless LAN access point offering the
`maximum signal strength. The second mobile communica(cid:173)
`tion terminal receives a connection request signal from the
`first mobile communication terminal, by the connection
`request receiving means. When the signal is recognized as
`the connection request signal from the first mobile commu(cid:173)
`nication terminal, the second terminal establishes wireless
`connection to the base station and makes the second wireless
`LAN interface active so as to enable connection from the
`first wireless LAN interface.
`
`[0016] Further, the first mobile communication terminal
`causes the wireless LAN switching means to switch its
`connection with the wireless LAN hotspot into connection to
`the second mobile communication terminal by way of the
`first wireless LAN interface and the second wireless LAN
`interface, so as to continuously keep the user's wireless
`access via the base station.
`
`[0017]
`In the above wireless communication system, the
`second wireless LAN interface of the second mobile com(cid:173)
`munication terminal has a wireless LAN access point or
`wireless LAN client function, and when the communication
`status detecting means determines that the first mobile
`communication terminal can be connected by means of the
`wireless LAN access point or wireless LAN client function
`of the second mobile communication terminal, the wireless
`LAN connection switching means establishes connection to
`the wireless LAN access point or wireless LAN client
`function of the second mobile communication terminal, in
`infrastructure mode or in ad hoc mode.
`
`[0018] With the above arrangement, the second mobile
`communication terminal can be connected to multiple first
`mobile communication terminals in one-to-one manner in ad
`hoc mode and can also be connected to multiple first mobile
`communication terminals simultaneously in infrastructure
`mode.
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`[0019] FIG. 1 is a schematic diagram showing a wireless
`communication system configuration according to the
`embodiment of the present invention.
`
`[0020] FIG. 2 is a schematic diagram showing a wireless
`communication system configuration according to the
`embodiment of the present invention.
`
`[0021] FIG. 3 is a block diagram showing a configuration
`of a first mobile communication terminal according to the
`embodiment of the present invention.
`
`[0022] FIG. 4 is a block diagram showing a configuration
`of a second mobile communication terminal according to the
`embodiment of the present invention.
`
`[0023] FIG. 5 is a block diagram showing another con(cid:173)
`figuration of a second mobile communication terminal
`according to the embodiment of the present invention.
`
`[0024] FIG. 6 is a schematic view showing a case where
`the wireless communication system according to
`the
`embodiment of the present invention is used in infrastructure
`mode.
`
`[0025] FIG. 7 is a flowchart showing operation in the first
`mobile communication terminal according to the embodi(cid:173)
`ment of the present invention.
`
`[0026] FIG. 8 is a flowchart showing operation in the
`second mobile communication terminal according to the
`embodiment of the present invention.
`
`[0027] FIG. 9 is a diagram showing a configuration of a
`connection request signal used in the wireless communica(cid:173)
`tion system according to the embodiment of the present
`invention.
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`
`[0028] The embodiment of the wireless communication
`system according to the present invention will be described
`next with reference to the drawings.
`
`[0029] FIGS. 1 and 2 are schematic diagrams showing a
`configuration of the wireless communication system in
`accordance with the embodiment of the present invention.
`FIG. 3 is a block diagram showing a configuration of a first
`mobile communication terminal; FIG. 4 is block diagram
`showing a configuration of a second mobile communication
`terminal; and FIG. 5 is a block diagram showing another
`configuration of a second mobile communication terminal.
`
`[0030] A first mobile communication terminal 100 is a
`portable information terminal having a first wireless LAN
`interface. Specific examples include notebook PCs, hand(cid:173)
`held PCs, PDAs and the like.
`
`[0031] A second mobile communication terminal 200 is a
`cellular phone having a second wireless LAN interface. As
`a specific example, use can be made of a W-CDMA cellular
`
`

`

`US 2006/0172769 Al
`
`Aug. 3, 2006
`
`3
`
`phone using the W-CDMA (wideband code division mul(cid:173)
`tiple access) mobile communication system or wide-area
`wireless communication system, which can provide a ser(cid:173)
`vice for wide area coverage at the maximum data transfer
`rate of 384 kbps outdoors, and supports high-speed travel
`such as in a car, bullet train, etc., and is charged based on the
`time or amount of data communication.
`[0032] Here, the second mobile communication terminal
`200 is not limited only to the cellular phones that support the
`W-CDMA mobile communication system but, cellular
`phones that support another digital mobile communication
`system such as, for example, GPRS (General Packet Radio
`Service), cdma2000, HSDPA (High Speed Downlink Packet
`Access) or the like, can be used.
`[0033] The first wireless LAN interface provided for first
`mobile communication terminal 100 and the second wireless
`LAN interface for second mobile communication terminal
`200 may employ wireless LAN interfaces for wireless local
`area network systems that, based on the IEEE (IEEE: the
`Institute of Electrical and Electronics Engineers, Inc.,)
`802.llb, IEEE802.lla and IEEE802.llg standards, can
`provide a service for local area coverage at the maximum
`data transfer rate of 54 Mbps, and deal with low-speed
`movement, i.e., standing still or walking around, and is
`charged at a low price or at a fixed sum. Here, the local area
`coverage means that the service area is limited discretely or
`to a spot.
`[0034]
`It should be noted that the first wireless LAN
`interface and second wireless LAN interface are not limited
`to the wireless LAN interfaces based on the IEEE802.llb,
`IEEE802.lla and IEEE802.llg standards, but use can also
`be made of wireless LAN interfaces supporting other high(cid:173)
`speed wireless systems such as, for example, UWB(Ultra
`Wide Band), the next-generation wireless LAN systems
`exceeding 200 Mbps, and IEEE802.llh, IEEE802.lli,
`IEEE802.llj, etc.
`[0035] First mobile communication terminal 100 is mainly
`composed of a processor unit 70, a display/input unit 79, a
`memory unit 80 and a first wireless LAN interface 31, each
`component being connected to a bus 78, as shown in FIG.
`3.
`[0036] The first wireless LNA interface 31 used here is a
`built-in PC wireless LAN interface, and performs signal
`transmission and reception using an antenna 81. Processor
`unit 70 is provided with driver software for first wireless
`LAN interface 31 and application software. The driver
`software of first wireless LAN interface 31 or application
`software constitutes a communication status detecting
`means 72 for detecting the received signal strength(s) and
`communication status of a wireless LAN hotspot area 3 2 ( or
`multiple hotspot areas) of a wireless LAN access point(s)
`300, a connection request transmitting means 73 for sending
`a signal for requesting connection to the second mobile
`communication terminal 200 and a wireless LAN switching
`means 71 for making a switch (handover) from one wireless
`LAN spot to another.
`[0037] Here, first wireless LAN interface 31 may also be
`constituted of a card interface 74, e.g., PCMCIA card, CF
`card, SD card, etc., and a card-type wireless LAN adapter 76
`(indicated at 30 in FIGS. 1 and 2), instead of a built-in PC
`first wireless LAN interface. In this case, wireless LAN
`adapter 76 performs signal transmission and reception via an
`antenna 77.
`
`[0038] Second mobile communication terminal 200 is
`composed of, as shown in FIG. 4, a W-CDMA antenna unit
`10, a W-CDMA radio unit 11, a W-CDMA modem unit 12,
`an application processor unit 14, a display/input unit 13, a
`memory unit 15 and a second wireless LAN interface 18.
`The second wireless LAN interface 18 performs signal
`transmission and reception via a wireless LAN interface
`antenna 17.
`
`[0039] Further, the driver software or application software
`in application processor unit 14 constitutes a connection
`request receiving means 22 for receiving a connection
`request signal sent from connection request transmitting
`means 73 of the first mobile communication terminal and a
`base station connecting means 23 for establishing wireless
`connection with a base station in accordance with the
`connection request verified by connection request receiving
`means 22.
`
`[0040] Second wireless LAN interface 18 may be also be
`composed of a card interface 16 and a card-type wireless
`LAN adapter 19, instead of the built-in second wireless LAN
`interface 18 that is directly connected to bus 20.
`
`[0041] For card interface unit 16 and card type wireless
`LAN adapter 19, a card interface such as SD card, PC card,
`PCMCIA card, CF card, etc., and a wireless LAN adapter
`supporting corresponding card interface, may be used. Fur(cid:173)
`ther, as the built-in second wireless LAN interface 18 a
`wireless LAN interface providing wireless LAN access
`point function or client function may also be employed.
`
`[0042] Second mobile communication terminal 200 may
`also be constituted of a dual-mode mobile communication
`terminal having W-CDMA/wireless LAN interfaces, as
`shown in FIG. 5. That is, the dual mode mobile communi(cid:173)
`cation terminal (second mobile communication terminal
`200) having W-CDMA/wireless LAN interfaces, shown in
`FIG. 5 is adapted to be a mobile communication terminal
`that establishes connection to each wireless system by way
`of the corresponding wireless interface, and makes a switch
`(handover) of communication between the wireless systems,
`based on the status.
`
`In the second mobile communication terminal 200
`[0043]
`shown in FIG. 5, an interface controller 25 is a controller
`that performs mode switching, that is, performs on-off
`control of a W-CDMA interface 24 and second wireless
`LAN interface 18. Here, W-CDMAinterface 24 is composed
`ofa W-CDMAantenna unit 10, W-CDMAradio unit 11 and
`a W-CDMA modem unit 12.
`
`[0044] Application processor unit 14 performs transmis(cid:173)
`sion/reception data processes for each mode and switches
`transmission/reception data between W-CDMA and wireless
`LAN interfaces, to realize the function of a dual mode
`mobile communication terminal.
`
`[0045] Further, the function of second mobile communi(cid:173)
`cation terminal 200 is realized by processing, converting and
`transferring data between W-CDMAinterface 24 and second
`wireless LAN interface 18. Similarly, the driver software or
`application software in application processor unit 14 may be
`provided with the function of connection request receiving
`means 22 for receiving a connection request signal sent from
`a first mobile communication terminal by connection request
`transmitting means 73, and the function of base station
`connecting means 23 for establishing a wireless connection
`
`

`

`US 2006/0172769 Al
`
`Aug. 3, 2006
`
`4
`
`to a base station in accordance with the connection request
`verified by connection request receiving means 22.
`
`[0046] Referring to FIG. 3, the flow of signals in the first
`wireless LAN interface 31 in the first mo bile communication
`terminal will be described.
`
`[0047] The signal transmitted from wireless LAN access
`point 300 is received by antenna 81, and sent to processor
`unit 70 via first wireless LAN interface 31. The signal is data
`processed and converted by the wireless LAN interface
`driver software and application software provided for pro(cid:173)
`cessor unit 70 and is displayed on display/input unit 79.
`
`[0048] Data to be transmitted, such as a user's request,
`e-mail etc., is data processed and converted by the wireless
`LAN interface driver software and application software
`provided for processor unit 70 and is transmitted to wireless
`LAN access point 300 byway of first wireless LAN interface
`31 and antenna 81.
`
`[0049] Referring to FIGS. 4 and 5, the flow of signals
`with regard to W-CDMA interface 24 in the second mobile
`communication terminal will be described.
`
`[0050] The downstream signal from base station 400 (see
`FIG. 1) is converted into I and Q-phase, orthogonal base
`band signals, through W-CDMA antenna unit 10 and
`W-CDMA radio unit 11, and the signals are input to
`W-CDMA modem unit 12. W-CDMA modem unit 12 per(cid:173)
`forms W-CDMA signal demodulation, communication pro(cid:173)
`tocol processing and other processes.
`
`[0051] The demodulated information data is transferred
`through bus 20 to application processor unit 14 where it is
`processed. The information data generated by application
`processor unit 14 is input to W-CDMA modem unit 12,
`where it is converted into I and Q-phase orthogonal base(cid:173)
`band signals, which in turn are input to W-CDMA radio unit
`11.
`
`[0052] W-CDMA radio unit 11 converts the input I and
`Q-phase orthogonal baseband signals into a high-frequency
`radio signal of a predetermined channel, and transmits it as
`a upstream signal to base station 400 (see FIG. 1) via
`W-CDMA antenna unit 10.
`
`[0053] Application processor unit 14 processes various
`kinds of data such as voice, image, e-mail, internet access
`data and other data, so that the application software can
`provide various W-CDMAmobile communication functions
`to the user.
`
`[0054] Referring to FIGS. 4 and 5, signal flow with
`regard to second wireless LAN interface 18 in the second
`mobile communication terminal will be described.
`
`[0055] The W-CDMA received signal, which has been
`processed and converted by application processor unit 14, is
`supplied to second wireless LAN interface 18, and is trans(cid:173)
`mitted to first mobile communication terminal 100 through
`wireless LAN interface antenna 17. On the other hand, the
`signal from first mobile communication terminal 100 is
`received by second wireless LAN interface 18 and is pro(cid:173)
`cessed and converted by application processor unit 14 and
`supplied to W-CDMA interface 24.
`
`[0056] Referring to FIGS. 1 and 2, the wireless commu(cid:173)
`nication system according to the embodiment of the present
`invention will be described in further detail.
`
`[0057] The wireless communication system according to
`the embodiment of the present invention includes: as shown
`in FIGS. 1 and 2, the first wireless system composed of one
`or multiple wireless LAN access points 300, installed at
`home, at an office, at a public area or any other site, a local,
`wireless LAN service area (wireless LAN hotspot area 32)
`provided by one or multiple hotspots and a first mobile
`communication terminal 100; and the second wireless sys(cid:173)
`tem composed of a wide area coverage, mobile communi(cid:173)
`cation service area 33 based on W-CDMA system, consti(cid:173)
`tuted by multiple base stations 400 and a second wireless
`communication terminal 200.
`
`[0058] Next, switching between the wireless systems will
`be described.
`
`[0059] When, as shown in FIG. 1, first mobile commu(cid:173)
`nication terminal 100 and second mobile communication
`terminal 200 reside both in wireless LAN hotspot area 32
`and in W-CDMAmobile communication service area 33, the
`user is able to establish connection to wireless LAN access
`point 300 using first mobile communication terminal 100 to
`make wireless access to the internet or for e-mail reception
`and transmission and other wireless access.
`
`[0060] First mobile communication terminal 100, using
`communication status detecting means 72 that is built in the
`wireless LAN interface driver software or application soft(cid:173)
`ware, detects the received signal strength of wireless LAN
`hotspot area 32, and also detects the communication status
`with wireless LAN access point 300, such as the average
`transmission and reception packet amounts and average
`transmission and reception data rates. Based on the detection
`of the received signal strength, first mobile communication
`terminal 100 checks whether the terminal resides at the
`boundary of wireless LAN hotspot area 32. It is also checked
`based on the detection of the communication status whether
`first mobile communication terminal 100 is busy, in com(cid:173)
`munication, or in an idle state (in which the terminal is not
`used by the user or no wireless access has been made for a
`time longer than a predetermined period of time).
`
`[0061]
`If the terminal is determined to be located at the
`boundary of wireless LAN hotspot area 32 due to user's
`movement and if there is another wireless LAN hotpot area
`around the current location, first mobile communication
`terminal 100 makes a handover between the hotspots, using
`wireless LAN switching means 71 that is built in the
`wireless LAN interface driver software or application soft(cid:173)
`ware, so as to enable the user to make continuous wireless
`access.
`
`[0062] On the other hand, if the terminal is determined to
`be located at the boundary of wireless LAN hotspot area 32
`due to user's movement and if there is no wireless LAN
`hotpot area around the current location, wireless access of
`first mobile communication terminal 100 is wanted to be
`made to continue by making the first mobile communication
`terminal 100 operate with the second mobile communication
`terminal 200 owned by the user. In this case, first mobile
`communication terminal 100, using connection request
`transmitting means 73 that is built in the wireless LAN
`interface driver software or application software, transmits a
`connection request signal that indicates continuation of the
`wireless access through second wireless LAN interface 18,
`to second wireless communication terminal 200, by way of
`wireless LAN access point 300.
`
`

`

`US 2006/0172769 Al
`
`Aug. 3, 2006
`
`5
`
`[0063] Second wireless connnunication terminal 200
`receives a connection request signal sent from first mobile
`communication terminal 100, using connection request
`receiving means 22 that is built in the wireless LAN inter(cid:173)
`face driver software or application software of application
`processor unit 14, and analyzes the received signal and
`checks and verifies it. This process is done by, for example,
`analyzing and checking the format of the connection request
`signal, and verifying the user name and password contained
`in the connection request signal.
`
`[0064] When the signal is determined to be the connection
`request signal from first mobile connnunication terminal
`100, the second terminal, using base station connecting
`means 23 that is built in the driver software or application
`software of application processor unit 14, establishes wire(cid:173)
`less connection ( calling) to base station 400 by way of
`W-CDMA interface 24. For example, connection is made to
`the predetermined internet service provider (ISP) or the
`in-house intranet, by circuit switching (CS) or packet
`switching (PS).
`
`[0065] At the same time, second wireless LAN interface
`18 is activated to provide a wireless LAN access point or
`wireless LAN client function to first mobile connnunication
`terminal 100.
`
`[0066] Having transmitted a request signal for connection
`to second mobile connnunication terminal 200 by means of
`connection request transmitting