(19) United States
`(12) Patent Application Publication
`Ishida
`
`(10) Pub. No.: US 2001/0014588 Al
`Aug. 16, 2001
`(43) Pub. Date:
`
`I IIIII IIIIIIII II llllll lllll lllll lllll lllll lllll lllll lllll 1111111111111111111
`US 20010014588Al
`
`(54) RADIO BASE STATION AND MOBILE
`STATION
`
`(30)
`
`Foreign Application Priority Data
`
`Feb. 14, 2000
`
`(JP) ......................................... 2000-35971
`
`(76)
`
`Inventor: Akira Ishida, Hirakata-city (JP)
`
`Publication Classification
`
`Correspondence Address:
`ARENT FOX KINTNER PLOTKIN & KAHN,
`PLLC
`Suite 600
`1050 Connecticut Avenue, N.W.
`Washington, DC 20036-5339 (US)
`
`Int. CI.7 ....................................................... H04B 1/00
`(51)
`(52) U.S. Cl. ............................ 455/69; 455/561; 455/442;
`455/272
`
`ABSTRACT
`(57)
`A radio base station, upon receipt of a traffic channel
`assignment request from a mobile station, creates a piece of
`traffic channel assignment information, attaches a diversity
`reception stop instruction to the information, and transmits
`the information with the diversity reception stop instruction
`to the mobile station as a response to the traffic channel
`assignment request.
`
`(21)
`
`Appl. No.:
`
`09/781,585
`
`(22)
`
`Filed:
`
`Feb. 13,2001
`
`11
`
`RADIO
`COMMUNICATION UNIT
`=-~==111
`
`4
`
`21
`
`10
`
`20
`
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`COMMUNICATION UNIT
`
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`
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`
`41
`
`RADIO
`~ - -1 COMMUNICATION UNIT
`
`50
`
`60
`
`70
`
`MODEM
`
`BASEBAND
`UNIT
`
`SIGNAL PROCESSING
`UNIT
`
`80
`
`CONTROL UNIT
`
`Intel, Exhibit 1005
`
`

`

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`
`Intel, Exhibit 1005
`
`

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`Intel, Exhibit 1005
`
`

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`
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`
`Intel, Exhibit 1005
`
`

`

`Patent Application Publication Aug. 16, 2001 Sheet 4 of 8
`
`US 2001/0014588 Al
`
`FIG. 4
`
`Leh ASSIGNMENT PROCESS
`
`STEP70
`CCH RECEPTION
`
`STEP75
`TRANSMIT Leh
`ASSIGNMENT
`REJECTION
`
`STEP76
`
`STEP77
`
`CREATE Leh
`ASSIGNMENT
`
`ATTACH DIVERSITY
`RECEPTION STOP
`INSTRUCTION
`
`TRANSMIT Leh
`ASSIGNMENT
`
`END
`
`Intel, Exhibit 1005
`
`

`

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`TION
`
`D = O;DIVERSITY RECEPTION AVAILABLE
`-D = 1 ;DIVERSITY RECEPTION STOP INSTRUC
`
`ABSOLUTE SLOT NO.
`
`CARRIER NO.
`
`RELATIVE SLOT NO.
`
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`
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`
`RESERVED I EXTENDEDLCHPROTOCOL TYPE
`MESSAGE TYPE
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`
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`
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`4
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`
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`
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`
`BIT
`
`OCTET
`
`LINK CHANNEL ASSIGNMENT MESSAGE
`
`FIG.5
`
`Intel, Exhibit 1005
`
`

`

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`
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`
`115
`
`114
`
`113
`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
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`
`FIG. 6
`
`Intel, Exhibit 1005
`
`

`

`Patent Application Publication Aug. 16, 2001 Sheet 7 of 8
`
`US 2001/0014588 Al
`
`FIG. 7
`
`Leh ESTABLISHMENT
`PROCESS
`
`TRANSMIT Leh ESTABLISHMENT
`REQUEST
`
`STEP101
`
`RECEIVE Leh ASSIGNMENT
`
`STEP102
`
`Yes
`STOP DIVERSITY
`RECEPTION
`
`STEP104
`
`CHANGE FREQUENCY AND SLOT STEP105
`
`TCH ACTIVATION PROCESS STEP106
`
`END
`
`Intel, Exhibit 1005
`
`

`

`Patent Application Publication Aug. 16, 2001 Sheet 8 of 8
`
`US 2001/0014588 Al
`
`SLOT4,8
`PS3
`
`- - -
`
`SLOT2,6
`PSl
`PS4
`-
`
`-
`
`SLOT3,7
`PS2
`-
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`
`FROMSTEP74
`
`Yes
`
`ATTACH STOP INSTRUCTION TO
`TCH FOR FIRST MOBILE STATION
`
`STEP94
`ATTACH STOP INSTRUCTION TO
`Leh ASSIGNMENT FOR NEW
`MOBILE STATION
`
`TO STEP77
`
`FIG. 8
`
`FIG. 9
`
`Intel, Exhibit 1005
`
`

`

`US 2001/0014588 Al
`
`Aug. 16, 2001
`
`1
`
`RADIO BASE STATION AND MOBILE STATION
`
`BACKGROUND OF THE INVENTION
`
`[0001]
`
`(1) Field of the Invention
`
`[0002] The present invention relates to a radio base station
`that communicates with a plurality of mobile stations with a
`space division multiplex, and relates to a mobile station.
`
`[0003]
`
`(2) Description of Related Art
`
`[0004] Recently, digital communication apparatuses trans(cid:173)
`fer information by modulating a carrier with a digital
`information signal (baseband signal) to efficiently transfer
`data.
`
`[0005]
`In digital communications, a multiple channel sys(cid:173)
`tem is adopted to assign a plurality of users to the same
`frequency to efficiently use frequencies. This is achieved by
`improvements in the data transfer speed or development of
`the time division multiplex. In addition to the above tech(cid:173)
`niques, a technique called space division multiplex is cur(cid:173)
`rently receiving attention. The space division multiplex
`enables a plurality of channels to be assigned to the same
`frequency at the same time using the adaptive array method.
`
`[0006]
`In the adaptive array method, a radio wave is
`transmitted or received to/from a remote end in a certain
`direction by adaptively forming a directional pattern (also
`referred to as an array antenna pattern) using a plurality of
`antennas. The adaptive array method is described in detail in
`"Transactions on Adaptive Signal Processing in Space
`Domain and Applied Techniques" (The Transactions of the
`Institute of Electronics and Communication, Vol.175-B-II,
`No.11, November), and will not be detailed here.
`
`[0007]
`In the space division multiplex, an adaptive-array
`radio base station communicates with a plurality of mobile
`stations simultaneously by forming a different directional
`pattern for each mobile station on each carrier of the same
`frequency simultaneously. The space division multiplex is
`also called Path Division Multiple Access (PDMA). The
`PDMA is described in detail in "PDMA Mobile Communi(cid:173)
`cation System" (Technical Report of Institute of Electronics,
`Information and Communication Engineers, RCS93-
`84(1994-01), pp37-44), and will not be detailed here.
`
`[0008] When the space division multiplex is applied to a
`mobile communication system such as a portable telephone
`or a PHS (Personal Handyphone System) telephone, the
`radio base station needs to form an array antenna pattern for
`either of transmission and reception. This is because it is
`physically difficult for a mobile station to have an array
`antenna and because the mobile station's position and direc(cid:173)
`tion greatly changes due to its portability.
`
`[0009] Meanwhile, many of recent portable telephones or
`PHS telephones have an embedded antenna in addition to a
`whip antenna to perform a diversity reception. It should be
`noted here that the diversity reception is divided into (1) the
`antenna selection diversity in which one out of a plurality of
`antennas that provides a reception signal with the highest
`reception level is selected and the signal is received through
`the selected antenna, and (2) the maximal-ratio combiner
`diversity in which received signals are weighted in propor(cid:173)
`tion to each reception level and combined, and the combined
`signal is received.
`
`[0010] However, there is a problem that when a space(cid:173)
`division-multiplex base station uses the space division mul(cid:173)
`tiplex to communicate with a plurality of mobile stations
`performing the diversity reception, the communication qual(cid:173)
`ity deteriorates. The reason for this is thought that a posi(cid:173)
`tional difference between the whip antenna and the embed(cid:173)
`ded antenna greatly affects reception of the array antenna
`pattern. More specifically, since many mobile stations use a
`whip antenna for transmission, the radio base station often
`points the array antenna pattern at a spatial position of the
`whip antenna. In this case, if the embedded antenna is
`located at such a position as is interfered with an array
`antenna pattern for another mobile station, the embedded
`antenna may be selected by mistake since the diversity
`reception selects an antenna based on only the reception
`signal level. This leads to deterioration of the communica(cid:173)
`tion quality ( e.g., increase in the bit error rate).
`
`SUMMARY OF THE INVENTION
`[0011]
`It is therefore an object of the present invention to
`provide a radio base station that prohibit deterioration of
`communication quality due to a diversity reception at a
`mobile station, and to provide a mobile station for this
`purpose.
`
`[0012] The above object is fulfilled by a radio base station
`for performing a radio communication with a plurality of
`mobile stations with a space division multiplex method, the
`radio base station being characterized by: transmitting an
`instruction to stop performing a diversity reception to a
`mobile station which the radio base station is to communi(cid:173)
`cate with by the space division multiplex method.
`
`[0013] With the above construction, the radio base station
`transmits the diversity reception stop instruction to each
`mobile station which the radio base station is to communi(cid:173)
`cate with by the space division multiplex method. Upon
`receipt of the diversity reception stop instruction, each
`mobile station stops the diversity reception and performs a
`reception using one antenna. This prohibits deterioration of
`communication quality due to the diversity reception at the
`mobile station.
`
`[0014] Also, the mobile station does not receive the diver(cid:173)
`sity reception stop instruction from ordinary radio base
`stations that do not perform the space division multiplex. As
`a result, the mobile station improves the communication
`quality for both ordinary and present-invention radio base
`stations. That is to say, the mobile station improves the
`communication quality by the diversity reception in the case
`of ordinary radio base stations, and by the one-antenna
`reception with an array antenna pattern in the case of the
`radio base station of the present invention.
`
`[0015] The above radio base station may comprise: a
`creation means for creating a piece of traffic channel assign(cid:173)
`ment information after receiving a traffic channel assign(cid:173)
`ment request from a mobile station; an attachment means for
`attaching the diversity reception stop instruction to the piece
`of traffic channel assignment information; and a transmis(cid:173)
`sion means for transmitting the piece of traffic channel
`assignment information with the diversity reception stop
`instruction, to the mobile station as a response to the traffic
`channel assignment request.
`
`[0016] With the above construction, the diversity recep(cid:173)
`tion stop instruction is transmitted together with the traffic
`
`Intel, Exhibit 1005
`
`

`

`US 2001/0014588 Al
`
`Aug. 16, 2001
`
`2
`
`channel assignment. This allows the mobile station to stop
`the diversity reception at the same time it starts a commu(cid:173)
`nication through a traffic channel.
`
`[0017] The above radio base station may also comprise: a
`determination means for determining, after receiving a traf(cid:173)
`fic channel assignment request from a mobile station,
`whether to allow the mobile station to space-division-mul(cid:173)
`tiplex with another mobile station which has communicated
`with the radio base station; a creation means for creating a
`piece of traffic channel assignment information when the
`determination means determines to allow the mobile station
`to space-division-multiplex with the other mobile station; an
`attachment means for attaching the diversity reception stop
`instruction to the piece of traffic channel assignment infor(cid:173)
`mation; and a transmission means for transmitting the piece
`of traffic channel assignment information with the diversity
`reception stop instruction, to the mobile station as a response
`to the traffic channel assignment request, and transmitting
`the diversity reception stop instruction to the other mobile
`station through a traffic channel.
`
`[0018] With the above construction, the mobile station
`stops the diversity reception at the same time it starts the
`space division multiplex.
`
`[0019] The above object is also fulfilled by a mobile
`station for performing a diversity reception, the mobile
`station having a plurality of antennas and comprising: a
`judgement means for judging whether a diversity reception
`stop instruction has been received from a radio base station;
`and a stop means for stopping the diversity reception when
`the judgement means judges that a diversity reception stop
`instruction has been received.
`
`[0020] With the above construction, upon receipt of the
`diversity reception stop instruction, the mobile station stops
`the diversity reception and performs a reception using one
`antenna. This prohibits deterioration of communication
`quality due to the diversity reception at the mobile station.
`
`[0021] Also, the mobile station does not receive the diver(cid:173)
`sity reception stop instruction from ordinary radio base
`stations that do not perform the space division multiplex. As
`a result, the mobile station improves the communication
`quality for both ordinary and present-invention radio base
`stations. That is to say, the mobile station improves the
`communication quality by the diversity reception in the case
`of ordinary radio base stations, and by the one-antenna
`reception with an array antenna pattern in the case of the
`radio base station of the present invention.
`
`[0022] The above mobile station may further comprise: a
`reception means for receiving a piece of traffic channel
`assignment information from the radio base station as a
`response to a traffic channel assignment request sent to the
`radio base station, wherein the judgement means judges
`whether the diversity reception stop instruction has been
`attached to the received piece of traffic channel assignment
`information.
`
`[0023] With the above construction, the diversity recep(cid:173)
`tion stop instruction is transmitted together with the traffic
`channel assignment. This allows the mobile station to stop
`the diversity reception at the same time it starts a commu(cid:173)
`nication through a traffic channel.
`
`[0024]
`In the above mobile station, the judgement means
`may further judge whether data received by the reception
`means through a traffic channel includes the diversity recep(cid:173)
`tion stop instruction.
`
`[0025] With the above construction, the diversity recep(cid:173)
`tion stop instruction is transmitted through a traffic channel.
`This allows the radio base station to transmit the stop
`instruction with a more flexible timing, enabling to stop the
`diversity reception as circumstances demand.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0026] These and other objects, advantages and features of
`the invention will become apparent from the following
`description thereof taken in conjunction with the accompa(cid:173)
`nying drawings which illustrate a specific embodiment of
`the invention. In the drawings:
`
`[0027] FIG. 1 is a block diagram showing the construction
`of the radio base station in the embodiment;
`
`[0028] FIG. 2 is a block diagram showing the construction
`of the signal processing unit 50;
`
`[0029] FIG. 3 is a block diagram showing the construction
`of the user processing unit 51a;
`
`[0030] FIG. 4 is a flowchart showing the link channel
`assignment process of the radio base station;;
`
`[0031] FIG. 5 shows an example of a link channel assign(cid:173)
`ment message;
`
`[0032] FIG. 6 is a block diagram showing the construction
`of the mobile station in the present embodiment;
`
`[0033] FIG. 7 is a flowchart showing a link channel
`establishment process in the mobile station;
`
`[0034] FIG. 8 shows the slot assignment table managed
`by the radio base station; and
`
`[0035] FIG. 9 is a flowchart showing the procedure of the
`stop instruction transmission by the radio base station.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`[0036]
`In the present embodiment, the radio base station
`performs a radio communication with one or more mobile
`stations by forming an array antenna pattern using a plurality
`of antennas. In the present embodiment, it is assumed that
`the radio base station is a PHS (Personal Handyphone
`System) base station which performs a radio communication
`with a PHS telephone according to a TDMA/TDD (Time
`Division Multiple Access/Time Division Duplex) method
`conforming to a PHS standard. The radio base station
`performs the space division multiplex, as well as the time
`division multiplex. In performing the space division multi(cid:173)
`plex, the radio base station instructs a mobile station which
`the radio base station is to newly communicate with by the
`space division multiplex, to stop the diversity reception.
`
`[0037] Construction of Radio Base Station
`
`[0038] FIG. 1 is a block diagram showing the construction
`of the radio base station in the present embodiment. As
`shown in FIG. 1, the radio base station includes a baseband
`unit 70, a modem unit 60, a signal processing unit 50, radio
`
`Intel, Exhibit 1005
`
`

`

`US 2001/0014588 Al
`
`Aug. 16, 2001
`
`3
`
`communication units 11, 21, 31, and 41, antennas 10, 20, 30,
`and 40, and a control unit 80.
`
`[0039] The baseband unit 70 performs a TDMA/TDD
`process for each signal to be transmitted by the space
`division multiplex. In the TDMNTDD process, a plurality
`of signals (baseband signals representing audio data or other
`data) to be transferred between the modem unit 60 and a
`plurality of lines connected via a public switched telephone
`network are multiplexed or separated into/from TDMN
`TDD frames. It should be noted here that a TDMA/TDD
`frame has a period of 5 mS and is divided into eight equal
`time slots, namely four transmission time slots and four
`reception time slots. More specifically, the baseband unit 70
`multiplexes signals from the plurality of lines into each
`TDMNTDD frame for the time division multiplex, multi(cid:173)
`plexes the signals from the plurality of lines into each
`transmission time slot for the space division multiplex, and
`outputs four signals at the maximum to the modem unit 60
`for each transmission time slot for space division multiplex.
`The baseband unit 70 inputs four signals at the maximum by
`the space division multiplex from the modem unit 60 for
`each reception time slot, and demultiplexes each received
`TDMNTDD frame into signals and outputs the signals to
`the plurality of lines.
`
`[0040] The modem unit 60 modulates signals input from
`the baseband unit 70, and demodulates signals input from
`the signal processing unit 50. The it/4-shift QPSK is used as
`a modulation/demodulation method.
`
`[0041] The signal processing unit 50 calculates parameters
`for array transmission/reception using the antennas 10 to 40
`as one array antenna. It should be noted here that the array
`transmission/reception is a transmission/reception which is
`performed by forming an array antenna pattern. The param(cid:173)
`eters here are weighting factors used for adjusting amplitude
`and phase of each signal to be transmitted or received
`from/to the radio communication unit 11, 21, 31, or 41,
`during the space division multiplex. That is to say, an array
`antenna pattern for one mobile station is formed by assign(cid:173)
`ing weights to transmission/reception signals of the radio
`communication unit 11, 21, 31, or 41 when a plurality of
`signals are transmitted or received at the same time through
`a plurality of antennas. More specifically, the signal pro(cid:173)
`cessing unit 50 calculates parameters according to each
`signal received by the radio communication units 11, 21, 31,
`and 41, assigns the calculated parameters as a weight to each
`reception signal. This forms a directional pattern at a recep(cid:173)
`tion. The signal processing unit 50 also assigns the calcu(cid:173)
`lated parameters as a weight to each signal transmitted by
`the radio communication units 11, 21, 31, and 41. This forms
`a directional pattern at a transmission.
`
`[0042] The radio communication units 11, 21, 31, and 41,
`during array transmissions, convert signals weighted by the
`signal processing unit 50 into RF (Radio Frequency) signals
`and transmit the RF signals through the antennas 10 to 40,
`and during array reception, convert signals received through
`the antennas 10 to 40 into baseband signals and output the
`baseband signals to the signal processing unit 50. During an
`omni transmission/reception, only the radio communication
`unit 11 operates as described above, and the other radio
`communication units 21, 31, and 41 stop operating. It should
`be noted here that the omni transmission/reception is a
`
`transmission/reception performed with a omnidirectional
`pattern using one antenna, without forming an array antenna
`pattern.
`
`[0043] The control unit 80 controls the entire radio base
`station by controlling the signal processing unit 50, modem
`unit 60, and baseband unit 70. Upon receipt of a traffic
`channel (TCH) assignment request (also referred to as a link
`channel establishment request, hereinafter "link channel" is
`referred to as "Leh") from a mobile station via the radio
`communication units 11, 21, 31, 41, signal processing unit
`50, modem unit 60, and baseband unit 70, the control unit 80
`selects an unassigned traffic channel and transmits to the
`mobile station an Leh assignment message that indicates that
`the selected traffic channel is assigned. The control unit 80
`transmits a diversity reception stop instruction to the mobile
`station together with the Leh assignment message via the
`radio communication units 11, 21, 31, 41, signal processing
`unit 50, and modem unit 60.
`
`[0044] The Leh establishment request
`issued for
`is
`requesting a link and an assignment of a traffic channel and
`is transmitted from a mobile station to the radio base station
`through a control channel ( also referred to as CCH) to
`change to a traffic channel during a position registration, a
`call-out, a call-in, a hand-over, or a channel change. An Leh
`establishment re-request, which is similar to the Leh estab(cid:173)
`lishment request, is also used. The Leh establishment re(cid:173)
`request is transmitted from a mobile station to the radio base
`station due to, for example, occurrence of a time-out after
`the Leh establishment request. An Leh assignment includes
`a frequency number and a slot number and is transmitted
`from the radio base station to a mobile station, wherein the
`frequency number and the slot number are used to specify a
`traffic channel to be assigned.
`
`[0045] The control unit 80 instructs the signal processing
`unit 50 to perform the omni transmission/reception for the
`control channels and to perform the array transmission/
`reception for the traffic channels.
`
`[0046] Construction of Signal Processing Unit 50
`
`[0047] FIG. 2 is a block diagram showing the construction
`of the signal processing unit 50. The signal processing unit
`50 includes user processing units 51a to 51d, adders 551 to
`554, and transmission/reception switches 561 to 564. When
`receiving an instruction to perform the array transmission/
`reception from the control unit 80, the signal processing unit
`50 calculates weighting factors and assigns the calculated
`weighting factors; and when receiving an instruction to
`perform the omni transmission/reception, the signal process(cid:173)
`ing unit 50 allows only the user processing unit 51a to
`operate, prohibiting the user processing units 51b and 51c
`from operating.
`
`[0048] The user processing units 51a to 51d correspond to
`four user signals to be transmitted by the space division
`multiplex for each time slot. Each user processing unit
`calculates the earlier-described weighting factors for a
`reception time slot, and extracts a user signal by using the
`weighting factors to combine reception signals input from
`the radio communication units 11 to 41 through switches
`561 to 564. Each user processing unit assigns the weighting
`factors to the user signal for a transmission time slot, and
`outputs the weighted user signal to each radio communica(cid:173)
`tion unit.
`
`Intel, Exhibit 1005
`
`

`

`US 2001/0014588 Al
`
`Aug. 16, 2001
`
`4
`
`[0049] The user processing unit 51a does not assign
`weights in the case of the omni transmission, and outputs a
`signal from the modem unit 60 to the radio communication
`unit 11, as it is, via the adder 551 and switch 561.
`
`[0050] The adder 551 combines weighted components of
`each user transmission signal output to the radio communi(cid:173)
`cation unit 11. The adders 552 to 553 operate in the same
`way as the adder 551, but differ from the adder 551 in that
`they correspond to the radio communication units 21 to 41,
`respectively.
`
`[0051] Construction of User Processing Unit
`
`[0052] The user processing units 51a to 51d have the same
`construction. In the following description, the user process(cid:173)
`ing unit 51a is used as an example.
`
`[0053] FIG. 3 is a block diagram showing the construction
`of the user processing unit 51a. The user processing unit 51a
`includes a weight calculation unit 53, an adder 54, a refer(cid:173)
`ence signal generation unit 55, a switch 56, multipliers 521
`to 524, and multipliers 581 to 584.
`
`[0054] The weight calculation unit 53 calculates weight(cid:173)
`ing factors so that a sum of differences between (a) each
`reception signal SlR to S4R received respectively from the
`radio communication units 11 to 41 and (b) the reference
`signal generated by the reference signal generation unit 55
`becomes a minimum. It should be noted here that the
`reference signal is symbol data in a period of a known fixed
`bit pattern (fixed symbols) included in a control signal for a
`control channel or in a communication signal for a traffic
`channel. More specifically, fields R (Ramp bits), SS (Start
`Symbol), PR (Preamble), and UW (Unique Word) are
`known fixed bit patterns. These fields can be used as
`reference signals. Also, the control signal includes a call-out
`identification code and a call-in identification code which
`are known. These identification codes are defined in the PHS
`standard, and will not be detailed here.
`
`[0055] The weight calculation unit 53 outputs the calcu(cid:173)
`lated weighting factors for a reception time slot to the
`multipliers 521 to 524 during the symbol period during
`which the weighting factors are calculated, or in one of the
`succeeding symbol periods.
`
`[0056] The weight calculation unit 53 outputs the calcu(cid:173)
`lated weighting factors to the multipliers 581 to 584 using a
`succeeding transmission time slot that corresponds to the
`reception time slot for which the weighting factors are
`calculated.
`
`[0057] The reference signal generation signal 55 outputs
`symbol data to be a reference signal in synchronization with
`the symbol timing through a reception time slot for a control
`channel; and outputs symbol data to be a reference signal to
`the weight calculation unit 53 in synchronization with the
`symbol timing through a reception time slot for a traffic
`channel.
`
`[0058] The multipliers 521 to 524 assign the weighting
`factors output from the weight calculation unit 53 to the
`reception signals Xl to X4 output from the radio commu(cid:173)
`nication units 11 to 41, for reception time slots.
`
`[0059] The adder 54 combines the signals weighted by the
`multipliers 521 to 524 into one signal. The composite signal
`represents a reception symbol for user "a" extracted from the
`
`four space-division-multiplexed reception signals received
`from users "a" to "d", wherein four is the maximum number
`and the number may be less.
`
`[0060] The multipliers 581 to 584 assign the weighting
`factors output from the weight calculation unit 53 to a
`transmission symbol for user "a" for each of the radio
`communication units 11 to 41.
`
`[0061] Leh Assignment
`
`[0062] FIG. 4 is a flowchart showing the Leh assignment
`process performed when the radio base station receives a
`control signal from a mobile station. After the process shown
`in FIG. 4 is completed, a communication through the
`assigned traffic channel (TCH) starts.
`
`[0063] The control unit 80 receives the control signal from
`the mobile station through the radio communication unit 11,
`signal processing unit 50, and modem 60 with reception time
`slots for a control channel (step 70). This reception may be
`the omni or array reception.
`
`[0064] When the received control signal is an Leh estab(cid:173)
`lishment request or an Leh establishment re-request (steps
`71 and 78), the control unit 80 attempts to nominate a
`candidate for a mobile station to use a time-division-multi(cid:173)
`plexed channel or a space-division-multiplexed traffic chan(cid:173)
`nel not assigned for a TDMNTDD frame (step 72).
`[0065] When failing to nominate a candidate, the control
`unit 80 instructs the signal processing unit 50 to transmit an
`Leh assignment rejection message (step 75).
`
`[0066] When succeeding in nominating a candidate, the
`control unit 80 creates an Leh assignment message which
`shows a carrier number (frequency number) of the selected
`traffic channel and a slot position (step 74), adds a diversity
`reception stop instruction to the created Leh assignment
`message (step 76), and then transmits the Leh assignment
`message (step 77).
`
`[0067] Diversity Reception Stop Instruction
`
`[0068] FIG. 5 shows an example of an Leh assignment
`message. As shown in FIG. 5, the Leh assignment message
`is composed of five octets, where the octet "5" includes only
`two bits. These octets conform to the PHS standard and will
`not be described in detail, except for the bit "6" of the octet
`"3" (hereinafter referred to as a D flag). When being "1", the
`D flag indicates a diversity reception stop instruction against
`the mobile station; and when being "O", the D flag indicates
`that a diversity reception is possible, namely, that either a
`diversity reception or a reception using one antenna is
`possible.
`
`[0069] As described above, the radio base station of the
`present embodiment transmits a diversity reception stop
`instruction to a mobile station when it starts a radio com(cid:173)
`munication with the mobile station using a traffic channel.
`With this construction, the radio base station can allow a
`plurality of mobile stations to stop the diversity reception
`and perform a reception using one antenna while performing
`radio communications with the plurality of mobile stations
`with the space division multiplex.
`
`[0070] Construction of Mobile Station
`
`[0071] FIG. 6 is a block diagram showing the construction
`of the mobile station in the present embodiment. The mobile
`
`Intel, Exhibit 1005
`
`

`

`US 2001/0014588 Al
`
`Aug. 16, 2001
`
`5
`
`station includes antennas 110a and 110b, a transmission/
`reception switch unit 111, a radio