(19) p)
`
`(12)
`
`Europiiisches Patentamt
`
`European Patent Office
`
`Office européen des brevets
`
`(11)
`
`EP1 206 051 A1
`
`EUROPEAN PATENT APPLICATION
`published in accordance with Art. 158(3) EPC
`
`(43) Date of publication:
`15.05.2002 Bulletin 2002/20
`
`(21) Application number: 019457472
`
`(22) Dale of filing: 02.07.2001
`
`(84) Designated Contracting States:
`AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU
`MC NL PT SE TR
`
`Designated Extension States:
`AL LT LV MK RO SI
`
`(30) Priority: 03.07.2000 JP 2000201233
`
`(71) Applicant: MATSUSHITA ELECTRIC INDUSTRIAL
`00., LTD.
`Kadoma—shi, Osaka 571 -8501 (JP)
`
`
`
`(51) Int (31.7: H04B 7110, H04B 7/26
`
`(86) International application number:
`PCTIJPO1I05696
`
`(87) International publication number:
`WO 02/03571 (10.01.2002 Gazette 2002102)
`
`(72) Inventors:
`0 AIZAWA, Junichi
`Yokohama-shi, Kanagawa 240-0033 (J P)
`0 AOYAMA, Takahisa
`Yokosuka-shi, Kanagawa 239-0841 (JP)
`0 HOSHINO, Masayuki
`Yokosuka-shi, Kanagawa 239-0841 (JP)
`
`(74) Representative: Grtinecker, Kinkeldey,
`Stockmair & Schwanhfiusser Anwaltssozietfit
`Maximilianstrasse 58
`
`80538 Mflnchen (DE)
`
`(54)
`
`WIRELESS COMMUNICATION DEVICE, AND WIRELESS COMMUNICATION METHOD
`
`An array directivity switching determining sec-
`(57)
`tion 114 stores reception quality information outputted
`from a separating section 113, determines whether to
`change a directivity or beam width oftransmission array
`antenna based on reception quality information, and
`outputs an information to indicate either to change the
`directivity or beam width of transmission array antenna
`to an array directivity switching controlling section 115
`in accordance with the determination result. When an
`
`information to change the directivity or beam width of
`transmission array antenna is output from the array di-
`rectivity switching determining section 114, the array di-
`rectivity switching controlling section 115 calculates the
`weight to be transmitted at each antenna based on ar-
`rival directivity information outputted from a reception
`array directivity controlling section 110, outputs the
`weight to the reception array directivity controlling sec-
`tion 110, and outputs an information to change the di-
`rectivity or beam width of transmission array antenna.
`
`
`THANSMISSION
`TRANSMISSION
`FRAME
`‘
`
`DATA
`GENEHAHNG
`
`MODULMING
`SECTION
`
` 103
`
`
`
`I 7
`TRANSMISSION FRAME
`ENERATING SECTION
`
`3“
`TRANSMISSION
`DATA
`
`
`
`TRANSMISSION
`ARRAY
`
`
`
`ARRAY
`DIREO'T‘IVITY
`SWITCHING
`DIRECTIVI‘I’Y
`
`
`CONTROLLING
`CONTROLLING
`SECTION
`SECTION
`
`
`
`
`RECEPTION
`ARRAY
`
`
`DIREC’I'NITY
`
`CONTROLLING
`
`SEO'HON
`
`RADIO RECEPTION
`SECTION
`REDEVED
`DATA
`
`
`SEPARATIHO
`SECTION
`
`DEMDDULATIN G
`SECTION
`
`
`FIG.1
`
`
`Printed by Jews, 750m PARIS (FR)
`
`EP1206051A1
`
`

`

`1
`
`EP 1 206 051 A1
`
`2
`
`Description
`
`Technical Field
`
`[0001] The present invention relates to a radio com-
`munication apparatus and a radio communication meth-
`od, specifically to an array antenna control of a radio
`communication apparatus.
`
`Background Art
`
`In radio communications, there is a case in
`[0002]
`which transmitted data might not be received correctly
`due to influence of a channel etc. In this case, when a
`transmitting side transmits data to a receiving side, the
`receiving side performs error detection on the received
`data, and transmits a retransmission request to the
`transmitting side when there is an error detected. Then,
`when receiving the retransmission request from the re-
`ceiving side, the transmitting side transmits data using
`the same directivity or beam width oftransmission array
`antenna used when data has been first transmitted.
`
`[0003] Moreover, after the first data is correctly re-
`ceived, the transmitting side transmits next data using
`the same directivity or beam width oftransmission array
`antenna used when first data has been transmitted.
`
`[0004] However, since a channel situation changes
`every moment, it is not guaranteed that a method trans-
`mitting data is always the optimum one, and the opti—
`mum directivity or beam width of transmission array an—
`tenna differs depending on the channel situation, result-
`ing in poor transmission efficiency in the radio commu-
`nications that does not perform transmission using the
`optimum directivity or beam width of transmission array
`antenna in accordance with the channel situation.
`
`Disclosure Of Invention
`
`It is an object of the present invention to pro-
`[0005]
`vide a radio communication apparatus and a radio com-
`munication method that can reduce the number of re-
`
`transmissions to improve transmission efficiency.
`[0006] This object can be achieved by measuring a
`channel situation at the time when a receiving side per-
`forms reception and detects an error, than deciding a
`directivity or beam width of transmission array antenna
`used when a transmitting side transmits/retransmits da-
`ta based on the measured channel situation, transmit-
`ting side performs transmission with an appropriate di-
`rectivity or beam width of transmission array antenna
`when carrying out transmission/retransmission.
`
`Brief Description of Drawings
`
`[0007]
`
`FIG. 1 is a block diagram showing the configuration
`ofthe radio communication apparatus according to
`
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`Embodiment 1 of the present invention; and
`FIG. 2 is a block diagram showing the configuration
`of the radio communication apparatus according to
`Embodiment 2 of the present invention.
`
`Best Mode for Carrying Out the Invention
`
`[0008] Thefollowing is an explanation of the embod-
`iments of the present invention with reference to the
`drawings accompanying herewith.
`
`(Embodiment 1)
`
`the operations
`[0009] This embodiment explains
`when using quality information of received signal meas-
`ured according to the channel situation.
`[0010]
`FIG. 1 is a block diagram showing the config-
`uration of the radio communication apparatus according
`to Embodiment 1 of the present invention. In FIG. 1, a
`radio communication apparatus 100 and a radio com-
`munication apparatus 150 perform radio communica-
`tion with each other.
`
`[0011] A buffer 101 stores transmission data and out-
`puts transmission data to a transmission frame gener-
`ating section 102 according to an information outputted
`from an array directivity switching determining section
`114 to be described later.
`
`[0012] The transmission frame generating section
`102 generates atransmission frame composed oftra ns—
`mission data outputted from the buffer 101 , and outputs
`the generated frame to a modulating section 103.
`[0013] The modulating section 103 modulates the
`transmission frame, and outputs the modulated frame
`to a radio transmission section 104.
`
`[0014] The radio transmission section 104 performs
`radio processing to the transmission signal outputted
`from the modulating section 103, and outputs the radio
`processed transmission signal to a transmission array
`directivity controlling section 105.
`[0015] The transmission array directivity controlling
`section 105 assigns weight to the transmission signal
`outputted from the radio transmission section 104 ac-
`cording to an information outputted from an array direc-
`tivity switching controlling section 115, and outputs the
`resultant weighted signal to antenna 107, antenna 108,
`and antenna 109 via a duplexer 106. Moreover, the
`transmission array directivity controlling section 105
`does not assign new weight to transmission signal as
`long as no changes of the directivity or beam width of
`transmission array antenna is performed.
`[0016] The duplexer 106 transmits the transmission
`signal outputted from the transmission array directivity
`controlling section 105 using antenna 107, antenna 108
`and antenna 109. on the other hand, the duplexer106
`outputs the radio signal that has been received by an-
`tenna107, antenna 108 and antenna 109 to a reception
`array directivity controlling section 110 as a received sig—
`nal.
`
`

`

`3
`
`EP 1 206 051 A1
`
`4
`
`Each of the antenna 107, antenna 108, and an-
`[0017]
`tenna 109 transmits the transmission signal outputted
`from the duplexer 106, and outputs the received radio
`signal to the duplexer 106.
`[0018] The reception array directivity controlling sec-
`tion 110 estimates direction of arrival of a received wave
`
`based on phase differences and power differences be-
`tween signals received by the antenna 107, antenna
`108, and antenna 109, and outputs information which
`indicates the direction of arrival (hereinafter referred to
`as "arrival directivity information") to the array directivity
`switching controlling section 115. Moreover, the recep-
`tion array directivity controlling section 110 outputs the
`received signal outputted from the duplexer 106 to a ra—
`dio reception section 111.
`[0019] The radio reception section 111 performs radio
`processing to the received signal outputted from the du-
`plexer 152, and outputs the radio processed received
`signal to a demodulating section 112.
`[0020] The demodulating section 112 demodulates
`the received signal outputted from the radio reception
`section 111, and outputs the demodulated signal to a
`separating section 113.
`[0021] The separating section 113 separates the re-
`ceived signal outputted from the demodulating section
`112 into received data, information that indicates quality
`of the received signal (hereinafter referred to as "recep-
`tion quality information) and a signal that indicates re-
`questing transmission of next data (hereinafter referred
`to as "ACK signal") or a signal that indicates requesting
`retransmission
`of
`data
`(hereinafter
`referred
`to
`as "NACK signal), and outputs received data to outside,
`and outputs ACK/NACK signal and reception quality in-
`formation to the array directivity switching determining
`section 114.
`
`[0022] When array directivity switching determining
`section 114 stores the reception quality information out—
`putted from the separating section 113 and when a
`NACK signal is received, the array directivity switching
`determining section 114 determines whetherto change
`the directivity or beam width of transmission array an-
`tenna based on reception quality information. Then,
`based on the determination result, the array directivity
`switching determining section 114 outputs information
`whetherto change the directivity or beam width of trans-
`mission array antenna to the array directivity switching
`controlling section 115, and outputs information to re-
`transmit data to the buffer 101.
`
`[0023] On the other hand, when an ACK signal is re-
`ceived, the array directivity switching determining sec-
`tion114 determines whetherto change the directivity or
`beam width oftransmission array antenna based on re-
`ception quality information. Then, based on the deter-
`mination result, the array directivity switching determin—
`ing section 114 outputs information whether to change
`the directivity or beam width of transmission array an—
`tenna to the array directivity switching controlling sec—
`tion 115, and the array directivity switching determining
`
`section 114 outputs information to transmit next data to
`the buffer 101.
`
`[0024] When array directivity switching determining
`section 114 outputs information to changethe directivity
`or beam width of transmission array antenna, the array
`directivity switching controlling section 115 calculates
`the weight to be transmitted at each antenna based on
`the arrival directivity information outputted from the re-
`ception array directivity controlling section 110, and out—
`puts the weight to the transmission array directivity con—
`trolling section 105, and the array directivity switching
`controlling section 115 outputs information to change
`the directivity or beam width of transmission array an-
`tenna.
`
`Furthermore, when no change in the directivity
`[0025]
`or beam width of transmission array antenna is to be
`executed, the array directivity switching controlling sec-
`tion 115 outputs information not to changethe directivity
`oftransmission or beam to the transmission array direc-
`tivity controlling section 105.
`[0026] Antenna 151 receives radio signals transmit-
`ted from the antenna 107, antenna 108 and antenna
`109, and outputs them to a duplexer 152.
`In addition,
`antenna 151 transmits a transmission signal outputted
`from the duplexer 152 as a radio signal.
`[0027] The duplexer 152 outputs the received signal
`outp utted from antenna 151 to a radio reception section
`153, and outputs a transmission signal outputted from
`a radio transmission section 159 to the antenna 151.
`
`[0028] The radio reception section 153 performs radio
`processing to a received signal outputted from the du-
`plexer 152, and outputs the radio processed received
`signal to both demodulating section 154 and reception
`quality measuring section 155.
`[0029] The demodulating section 154 demodulates a
`received signal outputted from the radio reception sec-
`tion 153, and outputs the obtained reception frame to
`an error detecting section 156.
`[0030] The reception quality measuring section 155
`measures quality of the received signal outputted from
`the radio reception section 153, and outputs reception
`quality information which indicatesthe measured recep-
`tion quality to a transmission frame generating section
`157.
`
`[0031] The error detecting section 156 determines
`whetherthere is an error in a reception frame outputted
`from the demodulating section 154, and when there is
`an error detected in the received data, error detecting
`section 156 outputs a NACK signal which requests re-
`transmission ot the erroneous data to the transmission
`
`frame generating section 157. Moreover, when there is
`no error detected in the received frame, the error detect-
`ing section 156 outputs an ACK signal which requests
`transmission of next datato thetransmission frame gen—
`erating section 157, and the error detecting section 156
`outputs errorless data.
`[0032] The transmission frame generating section
`157 generates atransmission frame composed oftra ns-
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`5
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`EP 1 206 051 A1
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`6
`
`mission data, reception quality information, and ACK/
`NACK signal, and outputs generated frame to a modu-
`lating section 158.
`[0033] The modulating section 158 modulates the
`transmission frame, and outputs the modulated frame
`to a radio transmission section 159 as a transmission
`
`signal.
`[0034] The radio transmission section 159 performs
`radio processing to the transmission signal outputted
`from the modulating section 158, and outputs the radio
`processed transmission signal to the duplexer 152.
`[0035] The following is an operational explanation of
`the radio communication apparatus ofthis embodiment.
`[0036] Transmission data is stored in the buffer 101
`and outputto the transmission frame generating section
`102 from the buffer 1 01 accordingto an information from
`the array directivity switching determining section 114,
`and the output data is formed as a transmission frame
`at the transmission frame generating section 102, and
`the resultant frame is output to the modulating section
`103.
`
`[0037] The transmission frame is modulated by the
`modulating section 103, the modulated frame is output
`to the radio transmission section 104 wherein it is sub-
`
`jected to radio processing operation, and is output as a
`radio signal to the transmission array directivity control-
`ling section 105, then output to antenna 107, antenna
`108, and antenna 109 via the duplexer 106.
`[0038] A radio signal transmitted from the radio com—
`munication apparatus 100 is received by antenna 151
`and is output to the radio reception section 153 as a re-
`ceived signal via duplexer 152.
`is subjected to radio
`[0039] The received signal
`processing operation in the radio reception section 153,
`the radio processed signal is output to both the demod-
`ulating section 154 and reception quality measuring
`section 155, then demodulated by the demodulating
`section 154, and output as a reception frametothe error
`detecting section 156.
`[0040] The reception quality of the received signal is
`measured by the reception quality measuring section
`155, and reception quality information indicating the
`measured reception quality is output to thetransmission
`frame generating section 157.
`[0041] The error detecting section 156 determines
`whether there is an error in the received frame. When
`
`an error is detected, NACK signal of erroneous data is
`output to the transmission frame generating section
`157, and when there is no error detected, ACK signal of
`errorless data is output to the transmission frame gen-
`erating section 157, and the received data is output to
`the next stage (not shown in the figure).
`[0042] The transmission frame generating section
`157 generates a transmission frame composed of re—
`ception quality information, ACK/NACK signal and
`transmission data.
`
`is subjected to radio
`mission section 159 wherein it
`processing operation, and the radio processed trans-
`mission signal is output as a radio transmission signal
`to antenna 151 via the duplexer152.
`[0044] The radio signal transmitted from the radio
`communication apparatus 150 is passed through anten-
`na 107, antenna 108, antenna 109, duplexer 106, and
`reception array directivity controlling section 110, then
`output to the radio reception section 111 as a received
`signal wherein it is subjected to radio processing and is
`output to the demodulating section 112 whereby the ra-
`dio processed signal is demodulated then the demodu-
`lated signal is output to the separating section 113. The
`reception array directivity controlling section 110 esti—
`mates direction of arrival of a received wave based on
`
`phase differences and power differences between sig-
`nals received by antenna 107, antenna 108, and anten-
`na 109, and the arrival directivity information is output
`to the array directivity switching controlling section 115.
`[0045] The received signal is separated into received
`data, reception quality information and ACKINACK sig-
`nal by the separating section 113, the received data is
`output to the next stage (notshown in thefigure), where-
`as reception quality information and ACK/NACK signal
`are output to the array directivity switching determining
`section 114.
`
`[0046] According to reception quality information,
`which is stored in the array directivity switching deter-
`mining section 114,
`the determination whether to
`change the directivity or beam width of transmission ar—
`ray antenna is performed. Then, based on the determi-
`nation result, information whether to change the direc-
`tivity or beam width oftransmission array antenna is out-
`put to the array directivity switching controlling section
`115.
`
`[0047] Moreover, when NACK signal is input to the ar-
`ray directivity switching determining section 114, an in—
`formation indicating a retransmission request is output
`to the buffer 101 from the array directivity switching de-
`termining section 114.
`[0048]
`Furthermore, when ACK signal is input to the
`array directivity switching determining section 114, an
`information indicating a request for transmission of the
`next data is output to the buffer 101 from the array di-
`rectivity switching determining section 114.
`[0049] When a change in the directivity or beam width
`of transmission array antenna is performed, the array
`directivity switching controlling section 115 calculates
`the weight to be transmitted at each antenna based on
`the arrival directivity information outputted from the re-
`ception array directivity controlling section 110, and out-
`puts the weight to transmission array directivity control-
`ling section 105. Then, information to changethe direc-
`tivity or beam width oftransmission array antenna is out—
`put to the transmission array directivity controlling sec-
`tion 105.
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`[0043] The transmission frame is modulated by the
`modulating section 158, then output to the radio trans-
`
`[0050] On the other hand, when no change in the di—
`rectivity or beam width of transmission array antenna is
`
`

`

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`EP 1 206 051 A1
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`8
`
`performed, the array directivity switching controlling
`section 115 outputs an informationto indicate no change
`in the directivity or beam width of transmission array an-
`tenna to the transmission array directivity controlling
`section 105.
`
`Furthermore, when information indicates a re-
`[0051]
`transmission request is input to the buffer 1 01 ,thetrans-
`mission data to be retransmitted is output to the trans-
`mission trame generating section 102 from the buffer
`101 and the output is generated as atransmission frame
`by the transmission frame generating section 102, and
`the generated frame is output to the modulating section
`103. Then, the modulating section 103 modulates the
`resultant and outputs a modulated frame to the radio
`transmission section 104 wherein the modulated frame
`
`is subjected to radio processing operation. The radio
`processed frame is output as a radio signal with a phase
`or a power value that are controlled by the transmission
`array directivity controlling section 105 to the duplexer
`106, antenna 107, antenna 108 and antenna 109 and
`then transmitted to the radio reception section 153 and
`received as a received signal by the antenna 151 and
`duplexer 152.
`[0052] On the other hand, when an information re-
`quest to transmit next data is input to the buffer 101 , the
`successfully transmitted data is deleted from the buffer
`101 and the next transmission data is input to the buffer
`101, generated as a transmission frame by the trans-
`mission frame generating section 102, and then output
`to the modulating section 103 wherein the modulating
`section 103 modulates the resultant, and outputs it to
`the radio transmission section 104. The output is sub-
`jected to radio processing by the radio transmission sec-
`tion 104. The radio processed frame is output as a radio
`signal with a phase or a power value controlled by the
`transmission array directivity controlling section 105 to
`the duplexer106, antenna 107, antenna 108 and anten—
`na 109 and then transmitted to the radio reception sec-
`tion 153 and received by the antenna 151 and duplexer
`152 as a received signal.
`[0053] Therefore, according to the radio communica-
`tion apparatus of this embodiment, since the directivity
`or beam width of transmission array antenna can be
`changed based on quality information of the received
`signal and transmission can be performed with an opti-
`mal directivity according to the channel situation, mak-
`ing it possible to reduce the number of retransmissions.
`[0054] Additionally, when the quality of the stored re-
`ception quality information is low, the array directivity
`switching determining section 114 can inform the array
`directivity switching controlling section 115 to change
`the array directivity of transmission antenna to be ori-
`ented toward the main wave and the other waves.
`
`In such a case where the quality of the stored
`[0055]
`reception quality information is low, transmission can be
`performed in a direction where transmission antenna
`can be oriented toward paths other than the main wave
`path, sothatthe receiving side can obtain diversity effect
`
`and the number of retransmissions can be reduced.
`
`[0056] Moreover, when the quality ofthe stored recep-
`tion quality information is
`low,
`the array directivity
`switching determining section 114 can output an infor-
`mation to widen the beam width of the directivity oftra ns-
`mission antenna used for transmission a signal to the
`array directivity controlling section 115.
`[0057] Accordingly, since the quality of stored recep-
`tion quality information is low and the beam width of the
`directivity of transmission antenna can be widened so
`as to perform transmission, it is possible to reduce the
`number of retransmissions and to lessen delay at the
`receiving side. Furthermore, even in a case where the
`channel situation is extremely poor, successful trans—
`mission can be achieved.
`
`For example, when the quality of the stored re-
`[0058]
`ception quality information is high, the array directivity
`switching determining section 114 can output an infor-
`mation to narrow the beam width of the directivity of
`transmission antenna used for transmission a signal to
`the array directivity controlling section 115.
`[0059] Therefore, since the quality of the stored re-
`ception quality information is high and the beam width
`of the directivity of transmission antenna can be nar-
`rowed so as to perform transmission, then it is possible
`to prevent interference to other users.
`[0060] As another example,
`the array directivity
`switching determining section 114 can measure the lev-
`el of stored reception quality information, making it pos—
`sible to output an information to change the beam width
`corresponding to the level stepwise to the array direc-
`tivity controlling section 115.
`[0061] Therefore, since directivity or beam width of
`transmission array antenna can be changed gradually
`based on reception quality information, it is possible to
`perform transmission with an optimum directivity ac-
`cording to the channel situation and to reduce the
`number of retransmissions.
`
`the array directivity
`further example,
`Still
`[0062]
`switching determining section 114 can provide limita-
`tions to the directivity or beam width of transmission ar-
`ray antenna.
`[0063] Resulting in a limited range ofthetransmission
`signal and hence making it possible to prevent interfer-
`ence to other users.
`
`(Embodiment 2)
`
`FIG. 2 is a block diagram showing the config-
`[0064]
`uration of the radio communication apparatus according
`to Embodiment 2 of the present invention. Parts in FIG.
`2 identical to those in FIG. 1 are assigned the same ref-
`erence numerals as in FIG.
`1 and their detailed expla-
`nations are omitted.
`
`In FIG. 2, a radio communication apparatus
`[0065]
`200 and a radio communication apparatus 250 perform
`radio communication with each other.
`
`[0066] The buffer 101 stores transmission data, and
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`outputs transmission data to the transmission frame
`generating section 102 according to an ACK/NACK sig-
`nal outputted from the separating section 113.
`[0067] The transmission array directivity controlling
`section 105 assigns weight to atransmission signalfrom
`the radio transmission section 104 according to an in-
`formation outputted from an array directivity switching
`controlling section 201, and outputs the resultant signal
`to the antenna 107, antenna 108, and antenna 109 via
`the duplexer 106. Moreover, when the directivity or
`beam width of
`transmission array antenna is not
`changed, the transmission array directivity controlling
`section 105 does not change the weight ofthe transmis-
`sion signal.
`[0068] The reception array directivity controlling sec-
`tion 110 estimates direction of arrival of a received wave
`
`based on phase differences and power differences be-
`tween signals received by the antenna 107, antenna
`108, and antenna 109, and outputs arrival directivity in-
`formation to the array directivity switching controlling
`section 201. Moreover, the reception array directivity
`controlling section 110 outputs a received signal output-
`ted from the duplexer 106 to the radio reception section
`111.
`
`[0069] The separating section 113 separates a re-
`ceived signal output from the demodulating section 112
`into a received data, a directivity switching signal to be
`described later and an ASK/NACK signal, specifically,
`outputs the received data to the next stage, outputs the
`ACKINACK signal to the buffer 101, and outputs the di—
`rectivity switching signal to the array directivity switching
`controlling section 201.
`[0070] When an information to change the directivity
`or beam width of transmission array antenna is output
`according to an information indicative of a change in the
`directivity switching signal which is output from the sep-
`arating section 113, the array directivity switching con—
`trolling section 201 calculates the weight to be transmit-
`ted at each antenna based on the arrival directivity in-
`formation outputted from the reception array directivity
`controlling section 110. Then, weight is output to the
`transmission array directivity controlling section 105,
`and output the information to change the directivity or
`beam width of transmission array antenna.
`[0071] Moreover, when the directivity or beam width
`of transmission array antenna is not changed, the array
`directivity switching controlling section 201 outputs in-
`formation indicates no change of the directivity or beam
`width of transmission array antenna to the transmission
`array directivity controlling section 105.
`[0072] The reception quality measuring section 155
`measures quality of the received signal outputted from
`the radio reception section 153, and outputs the meas-
`ured reception quality information to an array directivity
`switching determining section 251.
`[0073] The error detecting section 156 determines
`whether there is an error in data of a reception frame
`output from the demodulating section 154, and outputs
`
`a NACK signal which requests retransmission of erro-
`neous data to the array directivity switching determining
`section 251 when there is an error detected in the re-
`
`ceived data. Further, when there is no error in the re-
`ceived data, an ACK signal which requests transmission
`of next data is output to the array directivity switching
`determining section 251, so that only errorless data is
`output.
`[0074] The transmission frame generating section
`157 generates atransmission frame composed oftra ns—
`mission data, a directivity switching signal to be de-
`scribed later and ACK/NACK signal, and outputs the
`generated frame to a modulating section 158.
`[0075] Array directivity switching determining section
`251 stores the reception quality information outputfrom
`the reception quality measuring section 155 and when
`NACK signal is received from the error detecting section
`156, the array directivity determining section 251 deter-
`mines whether to change the directivity or beam width
`of transmission array antenna based on the stored re-
`ception quality information. Then, information whether
`to change the directivity or beam width of transmission
`array antenna (hereinafter referred to as "directivity
`switching signal“), and NACK signal are both output to
`the transmission frame generating section 157.
`[0076] Moreover, when receiving the ACK signal from
`error detecting section 156, the array directivity switch-
`ing determining section 251 determines whether to
`change the directivity or beam width of transmission ar—
`ray antenna based on the stored reception quality infor—
`mation, and outputs, based on the determination result,
`the directivity switching signal and ACK signal to the
`transmission frame generating section 157.
`[0077] Next, an operational explanation of the radio
`communication apparatus of this embodiment is given
`below.
`
`[0078] The directivity switching signal is generated
`based on reception quality information by the array di-
`rectivity switching determining section 251, and is com-
`posed together with the ACK/NACK signal and trans-
`mission data to generate transmission frame by the
`transmission frame generating section 157. The trans-
`mission frame is modulated by the modulating section
`158 and then output to the radio transmission section
`159 wherein it is subjected to radio processing opera-
`tion, and then transmitted as a radio signal by antenna
`151 via the duplexer 152.
`[0079] A radio signal transmitted from the radio com-
`munication apparatus 250 is received by antenna 107,
`antenna 108, antenna 109, passed through duplexer
`106 and reception array directivity controlling section
`110 and output as a received signal to the radio recep-
`tion section 111. The output to the radio reception sec-
`tion 111 is subjected to radio processing operation, out—
`put to the demodulating section 112 to be demodulated
`bythe demodulating section 112, and then output to the
`separating section 113. Moreover, the reception array
`directivity controlling section 110 estimates direction of
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`arrival of a received wave based on phase differences
`and power differences between signals received by the
`antenna 107, antenna 108, and antenna 109, and out-
`puts arrival directivity information to the array directivity
`switching controlling section 201.
`[0080]
`In separating section 113, the received signal
`is separated into received data, directivity switching sig-
`nal, and ACK/NACK signal, received data is output to
`next stage, ASK/NACK signal is output tothe buffer 1 01,
`and the directivity switching signal is output to the array
`directivity switching controlling section 201.
`[0081] When the ACK signal is input to buffer 101,
`successfully transmitted data is deleted from the buffer
`101 and next transmission data is input to buffer 101.
`[0082] Moreover, when the NCAK signal is input to
`buffer 101 , transmission data to be retransmitted is ou