Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 1 of 22 PageID #: 62
`Case 2:20-cv-00322-JRG Document 1—3 Filed 10/01/20 Page 1 of 22 PageID #: 62
`
`EXHIBIT C
`
`EXHIBIT C
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 2 of 22 PageID #: 63
`caSGZIZO'CV'OOQ’ZZ'JRG D°°“me“t 1"IIIIIITITIIIIITIIIIfllll'fli’llllIllllfillII‘IITITIIIIZIIIITITITIIITIlliillllx”
`
`USOO6813261B1
`
`(12) Unlted States Patent
`(10) Patent N0.:
`US 6,813,261 B1
`
`Esmailzadeh et al.
`(45) Date of Patent:
`Nov. 2, 2004
`
`(54) METHOD OF MOBILE COMMUNICATION
`AND APPARATUS THEREFOR
`
`6,111,869 A *
`6,269,088 B1 *
`
`...... 370/342
`8/2000 Esmailzadeh et al.
`7/2001 Masui et al.
`................ 370/335
`
`(75)
`
`Inventors: Riaz Esmailzadeh, Yokohama (JP);
`Takashl Ya“0>_T0k0r9zaYYa (JP);
`Nobukazu D01 H h
`(JP)
`’
`ac iou]1
`.
`.
`:Ht h Ltd.Tk
`JP
`)
`1 ac 1’
`’
`0 y0(
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`.
`73 As
`Signee
`)
`(
`( * ) Notice:
`
`(21) APP1~ N0~3 09/512,820
`(22)
`Filed:
`Feb. 25, 2000
`
`Related US. Application Data
`
`(63) Continuation of application No. 08/907,088, filed on Aug. 6,
`1997, HOW Pat- N0~ 671117869
`Foreign Application Priority Data
`
`(30)
`
`Aug. 7, 1996
`(JP)
`............................................. 8—208035
`(51)
`Int. Cl.7 ................................................ H04B 7/216
`(52) US. Cl. ....................... 370/342; 370/335
`
`58
`F'
`ld f S
`h
`370/320 335
`"""""""""""""""""
`(
`)
`1e
`0
`earc
`’
`’
`370/208, 209, 420, 441, 342, 348, 329,
`913, 375/130, 140, 145, 149, 455/550,
`561, 575, 567, 95
`
`(56)
`
`References Cited
`
`us. PATENT DOCUMENTS
`
`5,151,919 A
`5,404,355 A
`5,430,760 A
`5,537,414 A *
`
`9/1992 Dent
`4/1995 Raith
`7/1995 Dent
`7/1996 Takiyasu et al.
`
`OTHER PUBLICATIONS
`Tobagi et al, Packet Switching in Radio Channels: Part
`~
`~
`~
`~
`III—Polling and (Dynamic) Split—Channel Reservation Mul-
`tiple Access, IEEE, pp. 832—845, Aug. 1976.*
`R. Esmalizadeh et al, Spread Spectrum Slot Reservation
`Multiple Access, IEEE (19%) pp. 1715—1719:
`*
`'t d b
`.
`C1 6
`y exammer
`Primary Examiner—Frank Duong
`(74) Attorney, Agent, or Firm—Mattingly, Stanger &
`Mad“ PC
`(57)
`
`ABSTRACT
`
`In order to accomplish efficient communication of data
`between a base station and a plurality of mobile terminals,
`particular orthogonal codes are transmitted from the mobile
`stations to the base station as alert signals indicating the
`presence of data to be transmitted. The base station checks
`whether particular orthogonal codes are contained in the
`:lert signals,land1when thelpartifular 9rth0gonal codes age
`etecte
`in t e a ert s1gna 5’ 1n ormat1on representing .t e
`detected orthogonal codes and the schedules for transmitting
`the data from the mobile terminals to the base station are
`transmitted from the base station to the mobile terminals as
`
`an alert response to the alert signals. When the information
`representing the orthogonal codes used for the alert signals
`are contained in the alert response transmitted from the base
`station to the mobile terminals,
`the data waiting to be
`transmitted is transmitted from the mobile terminals to the
`
`base station according the data transmission schedules in the
`alert response.
`
`............ 370/347
`
`36 Claims, 10 Drawing Sheets
`
`CELL
`
`120
`ORTHOGONAL
`CODES
`
`
`
`
`
`ORTHOGONAL
`CODES
`
`SC
`
`RSCHEDULES
`
`
` 121
`HEDULES E.
`
`
`
`
`
`
`122
`
`BASE STATION [100
`
`ORTHO[)G%NAL
`CO E
`
`
`
`132
`SCHEDULES
`
` TO A SWITCHTNG
`
`STATTON
`
`MOBTLE
`
`COMMUNTCATTON
`
`
`SWITCHING
`STATTON
`
`
`
`
`
`
`
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 3 of 22 PageID #: 64
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 3 of 22 PageID #: 64
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 1 0f 10
`
`US 6,813,261 B1
`
`CODES
`
`CODES
`
`
` ORTHOGOONAL
`
`ORTHOGOZNAL
`4%SCHEDULES
`
`
`_ASESTATION
`122
`
`
`_RTHOGONAL_ODE—
`
`
` TO A SWITCHING
`
`STATION —132
`_CHEDULES
`
` MOBILE
`
`
`COMMUNICATION
`'
`SWITCHING
`STATION
`
`130
`
`SCHEDULES
`
`
`
`FIG. 1
`
`

`

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`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 4 Of 22 PageID #: 65
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 2 0f 10
`
`US 6,813,261 B1
`
`BASE STATION
`
`205
`
`TRANSMISSION
`
`211
`
`PILOT CHANNEL
`MODULATOR
`
`ACK/NACK OR
`I ALERT RESPONSE
`CHANNEL MODULATOR
`
`SLOT
`TIMING
`
`RECEPTION DATA
`
`ALERT
`RECEIVED
`
`201
`
`202
`
`MEMORY
`
`203
`
`DISPLAY
`UNIT
`
`204
`
`INPUT/
`OUTPUT
`UNIT
`
`MOBILE
`COMMUNICATION
`SWITCHING
`STATION
`INTERFACE
`UNIT
`
`
`
`PN CODE GENERATOR
`
`TO A MOBILE
`
`COMMUNICATION
`SWITCHING STATION
`
`FIG. 2
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 5 of 22 PageID #: 66
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 5 of 22 PageID #: 66
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 3 0f 10
`
`US 6,813,261 B1
`
`250 RECEPTION
`SIGNAL
`
`ALERT CHANNEL-
`MATCHED FILTER
`
`214
`
`PN CODE
`
`DSP CONTROL
`SIGNAL
`
`ALERT CHANNEL ACCUMULATOR
`
`321
`ACCUMULATORS
`
`311
`
`9:4
`
`9:0 ACCUMULATORS
`
`ACCUMULATORS
`
`03
`
`ACCUMULATORS 9:4
`
`ORTHOGONAL
`
`CODE GENERATOR
`
`ALERT SIGNAL
`
`FIG. 3
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 6 of 22 PageID #: 67
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 6 of 22 PageID #: 67
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 4 0f 10
`
`US 6,813,261 B1
`
`401
`
`CPU
`
`402
`
`MOBILE TERMINAL
`
`405
`TRANSMISSION
`411
`DSP
`DATA
`DATA PACKET
`TRANSMISSION
`MODULATOR
`
`C-ODE
`
`SELECTION
`SIGNAL
`
`403
`
`TIMING
`
`SLOT
`SYNCHRONIZING
`DATA
`
`DISPLAY
`UNIT
`
`404
`
`INPUT/
`
`03mm
`
`
`
`RECEEGXION
`
`ACK/NACK OR ALERT
`
`RESPONSE CHANNEL
`DEMODULATOR
`
`PN CODE GENERATOR
`
`FIG. 4
`
`412
`
`ALERT CHANNEL MODULATOR
`
`
`500
`
`SLOT TIMING
`
`I ORTHOGONAL CODE
`GENERATOR .
`
`
`
`
`
`CODE SELECTION
`SIGNAL
`
`FIG. 5
`
`
`
`ALERT SIGNAL
`
`
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 7 of 22 PageID #: 68
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 7 of 22 PageID #: 68
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 5 0f 10
`
`US 6,813,261 B1
`
`C 610
`
`C 611
`
`1
`
`601
`
`602
`
`604
`
`603
`
`
`
`FIG. 6
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 8 of 22 PageID #: 69
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 8 of 22 PageID #: 69
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 6 0f 10
`
`US 6,813,261 B1
`
` MOBILE TERMINAL
`ALERT CHANNEL MODULATOR 500
`
`
`
`ORTHOGONAL CODE GENERATOR
`601
`[———L|
`
`PN CODE GENERATOR
`PN CODE FOR THE
`
`ALERT CHANNEL
`
`
`MOBILE TERMINAL
`ALERT CHANNEL MODULATOR 500
`
`ORTHOGONAL CODE GENERATOR
`
`I
`
`I:602
`
`PN CODE GENERATOR
`
`PN CODE FOR THE
`ALERT CHANNEL
`
`‘
`
`
`ALERT CHANNEL MODULATOR 500
`
`MOBILE TERMINAL
`
`
`
`
`
`ORTHOGONAL CODE GENERATOR
`I
`I
`I
`l 603'
`
`
`
`416
`PN CODE GENERATOR
`
`PN CODE FOR THE
`
`ALERT CHANNEL
`
`
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 9 of 22 PageID #: 70
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 9 of 22 PageID #: 70
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 7 0f 10
`
`US 6,813,261 B1
`
`ALERT
`
`BASESIKHON
`
`SIGNAL
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 10 of 22 PageID #: 71
`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 10 of 22 PageID #: 71
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 8 0f 10
`
`US 6,813,261 B1
`
`FIG. 9
`
`BASE STATION
`
`CODE
`NUMBER
`
`NUMBER
`ADDRESS OF
`BASE STATION
`
`ACK/NACK
`OR ALERT
`RESPONSE
`CHANNEL
`MODULATOR
`
`PN Code Generator
`PN CODE FOR
`ACK/NACK OR
`ALERT RESPONSE
`CHANNEL
`
`BASE STATION
`
`SOURCE,
`ADDRESS OF
`BASE STATION
`
`ADDRESS OF
`TRANSMITTING
`SOURCE,
`ADDRESS OF
`BASE STATION
`ADDRESS OF
`TRANSMITTING
`SOURCE,
`ADDRESS OF
`BASE STATION
`
`ADDRESS OF
`TRANSMITTING
`SOURCE,
`ADDRESS OF
`
`\
`
`1 1 0
`
`DATA PACKETS
`
`m
`m
`E—‘ék
`
`111
`
`112
`
`
`
`
`
`DATA PACKETS
`
`
`
`DATA PACKETS
`
`FIG. 10
`
`\ TIME SLOTS
`
`
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 11 of 22 PageID #: 72
`Case 2:20-cv-00322-JRG Document 1—3 Filed 10/01/20 Page 11 of 22 PageID #: 72
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 9 0f 10
`
`US 6,813,261 B1
`
`
`
` 1101
`
`DATA PACKETS GENERATED
`
`TRANSMIT ALERT SIGNALS FROM
`THE HEAD OF THE TIME SLOTS
`
`1102
`
`
`
`
`WAIT FOR N SLOTS
`(N IS A RANDOM NUMBER)
`
`
`1103
`
`
`ARE THE ALERT
`
`
`NO RESPONSE
`
`SIGNALS SUCCESSFULLY
`RECEIVED?
`
`
`RESPONSE IS RECEIVED
`
`
`
`
`
`
`1105
`
`
`TIME SLOTS ACCORDING TO A ,
`
`RESPONSE FROM THE BASE STATION.
`
`TRANSMIT DATA PACKETS TO
`
`
`
`1106 ARE THE
`
`PACKETS SUCCESSFULLY
`
`RECEIVED?
`
`
`
`FIG. 11
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 12 of 22 PageID #: 73
`Case 2:20-cv-00322-JRG Document 1—3 Filed 10/01/20 Page 12 of 22 PageID #: 73
`
`US. Patent
`
`Nov. 2, 2004
`
`Sheet 10 0f 10
`
`US 6,813,261 B1
`
`START
`
`ALERT SIGNALS RECEIVED
`
`1201
`
`DETERMINE TIME SLOTS CAPABLE
`OF RECEIVING DATA PACKETS
`FROM THE MOBILE TERMINALS
`
`1202
`
`SENDS THE RESULTS
`OF SCHEDULES TO THE
`MOBILE TERMINALS
`
`1203
`
`SEND NACK AND
`RE-SCHEDULE
`
`
`
`1204
`
`
`ARE
`
`SEND NACK AND
`PACKETS
`
`RECEIVED? RE-SCHEDULE
`
`
`1207
`
`
`
`
`ARE
`
`PACKETS SUCCESSFULLY
`RECEIVED?
`
`
`YES
`
`SEND ACK
`
`1208
`
`END
`
`FIG. 12
`
`

`

`Case 2:20-cv-00322-JRG Document 1-3 Filed 10/01/20 Page 13 of 22 PageID #: 74
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`
`US 6,813,261 B1
`
`1
`METHOD OF MOBILE COMMUNICATION
`AND APPARATUS THEREFOR
`
`This application is a continuation of Ser. No. 08/907,088
`filed Aug. 6, 1997 now US. Pat. No. 6,111,869.
`
`FIELD OF THE INVENTION
`
`invention relates to a method of mobile
`The present
`communication for transmitting and receiving data between
`a base station and a plurality of mobile terminals after
`having determined schedules for transmitting data, and to an
`apparatus therefor. Particularly, the invention relates to a
`method of mobile communication wherein, in transmitting a
`plurality of data packets from mobile terminals to the base
`station, the base station is informed that the data packets to
`be transmitted are present
`in the mobile terminals, and
`wherein the schedules for transmitting and receiving the data
`packets are determined and then the data packets are trans-
`mitted and received.
`
`BACKGROUND OF THE INVENTION
`
`In the prior art, a reservation-type mobile communication
`system has been proposed to transmit and receive data by
`radio communication between a base station and a plurality
`of mobile terminals after having reserved data channels for
`transmission and reception.
`
`SUMMARY OF THE INVENTION
`
`The present inventors have developed a system for over-
`coming the problems associated with the conventional sys-
`tem as discussed below. The above-mentioned conventional
`
`mobile communication system of the reservation type has
`been provided with a plurality of channels such as a pres-
`ervation channel for transmitting and receiving a reservation
`packet, a response channel for transmitting and receiving a
`response packet for the reservation packet, and data channels
`for transmitting and receiving data, and wherein mobile
`terminals which wish to transmit the data use the reservation
`
`channel to transmit the reservation packet to the base station
`in order to let the base station know the presence of data that
`are to be transmitted.
`
`The base station that has received the reservation packet
`from the mobile terminal assigns a data channel and a time
`slot which is a transmission timing that will be used by the
`mobile terminal, and transmits the assigned data channel and
`the time slot to the mobile terminal by using the response
`channel.
`
`The mobile terminal that has received a response from the
`base station transmits data to the base station by using the
`assigned data channel and the time slot. The mobile terminal
`of the conventional transmission system of the reservation
`type transmits the data by using the data channel and the
`time slot assigned by the base station, and avoids the
`collision of data on the data channel even when the data are
`
`transmitted from a plurality of mobile terminals.
`In the above-mentioned conventional mobile communi-
`
`cation system of the reservation type, however, a plurality of
`reservation packets collide in the base station when the
`reservation packets are transmitted from a plurality of
`mobile terminals to the base station, and the contents of the
`reservation packets cannot be correctly read out in the base
`station. Therefore, the mobile terminals must transmit res-
`ervation packets again. In order to transmit the reservation
`package again as described above, waiting times are set in
`a random fashion so that the reservation packages will not
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`collide again. When the reservation packets collide,
`transmission efficiency of data greatly decreases.
`Furthermore,
`in the above-mentioned conventional
`mobile communication system of the reservation type, data
`for making a reservation are transmitted and received in
`addition to the data that are to be transmitted. Therefore, a
`ratio of the data that are desired to be transmitted decreases
`in the whole data that are transmitted and received between
`the base station and the mobile terminals. When the con-
`
`the
`
`secutive data are to be transmitted being divided into a
`plurality of data packages in the above-mentioned conven-
`tional mobile communication system of the reservation type,
`in particular, a reservation packet is transmitted for the
`transmission of each data packet, and the packets occupy a
`large ratio in the whole data transmitted and received
`between the base station and the mobile terminal.
`
`A mobile communication system of the reservation type
`applying a code division multiple access (CDMA) has been
`disclosed in an article to R. Esmailzadeh, N. Doi, H. Masui,
`Y. Ohgoshi and T. Yano, entitled “Spread Spectrum Slot
`Reservation Multiple Access”, IEEE VTC, April 1996, Vol.
`3, pp. 1715—1719. The outline of this system involves
`forming a plurality of reservation channels, response chan-
`nels and data channels by using pseudo noise (PN) as a
`plurality of different dispersion codes, requesting the trans-
`mission of data through the plurality of reservation channels,
`and transmitting and receiving data by using a data channel
`designated by the response channel. According to the con-
`ventional mobile communication system of the reservation
`type using the above-mentioned CDMA, the contents of the
`reservation packets can be correctly read out by the base
`station even when a plurality of mobile terminals are trans-
`mitting reservation packets to the base station. Aplurality of
`reservation packets received by the base station are partially
`overlap each other on the time aXis, provided the timings
`deviate by more than a chip which is a minimum unit for
`constituting a PN signal among the reservation packets.
`However,
`in the conventional mobile communication
`system of the reservation type using the above-mentioned
`CDMA, when the deviation of timing is not larger than a
`chip among the reservation packets that are partly overlap-
`ping one another, the contents of the reservation packets are
`not correctly read by the base station. Therefore, the mobile
`terminals must transmit the reservation packets again. Also,
`the data for making a reservation are transmitted and
`received in addition to the data that are to be transmitted.
`Therefore,
`the ratio of the data that are desired to be
`transmitted becomes low with respect to the entire amount
`of data transmitted and received between the base station
`and the mobile terminals.
`
`The present inventors have studied the above-mentioned
`prior art and have found the following problems. First, in the
`above-mentioned conventional mobile communication sys-
`tem of the reservation type, it is not possible to read the
`contents of the reservation packets when the reservation
`packets simultaneously arrive at the base station from a
`plurality of mobile terminals. When the plurality of reser-
`vation packets collide, it becomes necessary to transmit the
`reservation packets again.
`Second, reservation packets are transmitted for determin-
`ing schedules for transmitting data. For this purpose,
`therefore, an output is necessary for transmitting the reser-
`vation packets in addition to an output for transmitting the
`data, and the communication capacity of data decreases by
`an amount corresponding to the electric power of transmit-
`ting the reservation packets.
`
`

`

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`
`US 6,813,261 B1
`
`3
`An object of the present invention is to provide technol-
`ogy capable of efficiently transmitting and receiving data
`between the base station and a plurality of mobile terminals.
`Another object of the present
`invention is to provide
`technology capable of detecting the individual alert signals
`even when a plurality of alert signals are transmitted from a
`plurality of mobile terminals to the base station.
`Yet another object of the present invention is to provide
`technology capable of maintaining, at a low level, the value
`of the alert signals transmitted from the mobile terminals.
`The following are representative examples of methods
`and apparatuses which realize the above-mentioned and
`other objects of the present invention.
`(1) A method of mobile communication includes deter-
`mining schedules for transmitting and receiving data, and
`transmitting and receiving data between a base station and a
`plurality of mobile terminals according to the schedules.
`Particular orthogonal codes are transmitted from mobile
`stations to the base station as alert signals indicating the
`presence of data to be transmitted. The base station checks
`whether particular orthogonal codes are contained in the
`alert signals transmitted from the mobile terminals to the
`base station. When the particular orthogonal codes are
`detected in the alert signals transmitted from the mobile
`stations to the base station, data representing the detected
`orthogonal codes and the schedules for transmitting the data
`from the mobile terminals to the base station are transmitted
`from the base station to the mobile terminals as an alert
`
`response in response to the alert signals. When the data
`representing the orthogonal codes used for the alert signals
`transmitted from the mobile terminals to the base station are
`
`contained in the alert response transmitted from the base
`station to the mobile terminals, the data transmission sched-
`ules in the alert response are read out at the mobile terminals
`and the data are transmitted from the mobile terminals to the
`
`base station according the schedules that are read out.
`When the data are to be transmitted and received between
`
`the base station and the mobile terminals according to the
`above-mentioned mobile communication method, mobile
`terminals which intend to transmit data select and generate
`particular orthogonal codes out of a plurality of orthogonal
`codes, and transmit these generated orthogonal codes to the
`base station as alert signals indicating the presence of data
`that are to be transmitted. Here,
`the orthogonal codes
`transmitted as alert signals from the mobile terminals to the
`base station are such codes that the inner products of the
`same codes assume particular values but the inner products
`of different codes assume a value of zero.
`
`The base station that has received the alert signals gen-
`erates orthogonal codes and checks whether these generated
`orthogonal codes are contained in the alert signals transmit-
`ted from the mobile terminals to the base station. When the
`
`orthogonal codes generated by the base station are detected
`in the alert signals transmitted from the mobile terminals to
`the base station, the base station that has received the alert
`signals determines schedules for transmitting the data from
`the mobile terminals to the base station. Then the base
`
`station transmits, to the mobile terminals, the data repre-
`senting the detected orthogonal codes and the determined
`schedules for transmitting data from the mobile terminals to
`the base station as an alert response to the alert signals.
`Upon receiving the alert response, the mobile terminals
`compare the orthogonal codes transmitted from the mobile
`terminals to the base station with orthogonal codes repre-
`sented by the data stored in the alert response, and check if
`the data representing the orthogonal codes used in the alert
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`signals transmitted from the mobile terminals to the base
`station are contained in the alert response transmitted from
`the base station to the mobile terminals. When the data
`
`representing the orthogonal codes used by a mobile terminal
`as its alert signal are contained in the alert response from the
`base station, the data transmission schedules in the alert
`response are read out by the mobile terminal, and the data
`are transmitted from the mobile terminal to the base station
`
`according to the schedules that are read out.
`According to the mobile communication method as
`described above, the data are transmitted and received after
`the schedules are determined by alert signals of orthogonal
`codes. Therefore, an efficient communication of data can be
`accomplished between the base station and the plurality of
`mobile terminals.
`
`(2) In the mobile communication method described in (1)
`above, the alert signals transmitted from the mobile termi-
`nals to the base station are multiplied by each of a plurality
`of orthogonal codes generated in the base station in order to
`check whether particular orthogonal codes are contained in
`the alert signals. The base station generates a plurality of
`orthogonal codes upon receiving alert signals from the
`mobile terminals, multiplies the alert signals transmitted
`from the mobile terminals to the base station by each of a
`plurality of orthogonal codes generated by the base station,
`and detects orthogonal codes in the alert signals that are
`received based upon the results of multiplication.
`When a plurality of mobile terminals simultaneously
`transmit alert signals to the base station, a plurality of
`orthogonal codes are contained in the alert signals received
`by the base station. Here, however, the inner products of the
`same orthogonal codes assume particular values and the
`inner products of different orthogonal codes assume a value
`of zero. Therefore, the alert signals containing a plurality of
`orthogonal codes are multiplied by each of a plurality of
`orthogonal codes generated by the base station, and the
`results of multiplication are checked for each of the orthogo-
`nal codes. Even when the plurality of orthogonal codes are
`contained in the alert signals, therefore,
`it is possible to
`check if particular orthogonal codes are contained.
`According to the mobile communication method as
`described above, the results of multiplication of the same
`orthogonal codes assume particular values and the results of
`multiplication of different orthogonal codes assume a value
`of zero. This makes it possible to detect the individual alert
`signals even when the plurality of alert signals are trans-
`mitted from a plurality of mobile terminals to the base
`station.
`
`(3) In the mobile communication method described in (2)
`above,
`the results of multiplication of the alert signals
`transmitted from the mobile terminals to the base station and
`
`the orthogonal codes generated in the base station, are
`accumulated for each of a plurality of bit periods constitut-
`ing the orthogonal codes in order to check whether particular
`orthogonal codes are contained in the alert signals. Upon
`receiving alert signals from the mobile terminals, the base
`station multiplies the alert signals transmitted from the
`mobile terminals to the base station by orthogonal codes
`generated by the base station, and accumulates the results of
`the multiplication for each of a plurality of bit periods
`constituting the orthogonal codes. When the inner products
`of the orthogonal codes in the alert signals that are received
`and the orthogonal codes generated by the base station are
`accumulated for each of a plurality of bit periods, the noise
`component in each bit period is canceled and the S/N ratio
`of the alert signals is improved. Therefore,
`it becomes
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`5
`possible to maintain the output value of the alert signals
`transmitted from the mobile terminals at a low level. This
`saves the output of the alert channel for transmitting the alert
`signals and increases the number of data channels.
`According to the mobile communication method as
`described above, reception of the alert signals is detected by
`accumulating the orthogonal codes for a plurality of bit
`periods, making it possible to maintain the output value of
`the alert signals transmitted from the mobile terminals at a
`low level.
`
`(4) An apparatus used for mobile communication accord-
`ing to a method involving determining schedules for trans-
`mitting and receiving data, and transmitting and receiving
`data between a base station and a plurality of mobile
`terminals according to the schedules, includes an alert signal
`transmission means for transmitting particular orthogonal
`codes from mobile terminals to the base station as alert
`
`signals indicating the presence of data to be transmitted. The
`apparatus also includes an alert signal reception means for
`checking in the base station whether particular orthogonal
`codes are contained in the alert signals transmitted from the
`mobile terminals to the base station. An alert response
`transmission means is provided which, when the particular
`orthogonal codes are detected in the alert signals transmitted
`from the mobile terminals to the base station, transmits,
`from the base station to the mobile terminals, data repre-
`senting the detected orthogonal codes and the schedules for
`transmitting the data from the mobile terminals to the base
`station as an alert response to the alert signals. Finally, an
`alert response reception means is provided which, when the
`data representing the orthogonal codes used for the alert
`signals transmitted from the mobile terminals to the base
`station are contained in the alert response transmitted from
`the base station to the mobile terminals, reads out at the
`mobile terminals the data transmission schedules in the alert
`response.
`When the data are to be transmitted and received between
`
`the base station and the mobile terminals according to the
`above-mentioned mobile communication apparatus, mobile
`terminals which intend to transmit data select and generate
`particular orthogonal codes out of a plurality of orthogonal
`codes, and transmit these generated orthogonal codes to the
`base station as alert signals indicating the presence of data
`for transmitting the above generated orthogonal codes. In
`the base station which has received the alert signals, the alert
`signal reception means generates orthogonal codes and
`checks if the above generated orthogonal codes are con-
`tained in the alert signals that are transmitted from the
`mobile terminals to the base station. When the orthogonal
`codes generated by the base station are detected in the alert
`signals transmitted from the mobile terminals to the base
`station, the alert response transmission means in the base
`station that has received the alert signals determines sched-
`ules for transmitting data from the mobile terminals to the
`base station, and transmits, from the base station to the
`mobile terminals, the data representing the detected orthogo-
`nal codes and the determined schedules for transmitting data
`from the mobile terminals to the base station as an alert
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`response to the alert signals.
`In the mobile terminals that have received the alert
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`response, the alert response reception means compares the
`orthogonal codes transmitted from the mobile terminals to
`the base station with orthogonal codes represented by the
`data stored in the alert response, and checks if the data
`representing the orthogonal codes used in the alert signals
`transmitted from the mobile terminals to the base station are
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`contained in the alert response transmitted from the base
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`6
`station to the mobile terminals. When the data representing
`the orthogonal codes used by the mobile terminals as alert
`signals are contained in the alert response from the base
`station, the data transmission schedules in the alert response
`are read out by the mobile terminals, and the data are
`transmitted from the mobile terminals to the base station
`according to the schedules that are read out.
`According to the mobile communication apparatus as
`described above, the data are transmitted and received after
`the schedules are determined by alert signals which use
`orthogonal codes. Therefore, an efficient communication of
`data can be accomplished between the base station and the
`mobile terminals.
`
`(5) In an apparatus for mobile communication described
`in (4) above, the alert signal reception means is provided
`with a multiplication means for multiplying the alert signals
`transmitted from the mobile terminals to the base station by
`each of a plurality of orthogonal codes generated in the base
`station. When the base station in the above-mentioned
`
`mobile communication apparatus receives alert signals from
`the mobile terminals, the alert signal reception means gen-
`erates a plurality of orthogonal codes, and the multiplication
`means multiplies the alert signals transmitted from the
`mobile terminals to the base station by each of a plurality of
`orthogonal codes generated by the base station, in order to
`detect orthogonal codes in the alert signals that are received
`based upon the results of multiplication. When a plurality of
`mobile terminals simultaneously transmit alert signals to the
`base station, a plurality of orthogonal codes are contained in
`the alert signals received by the base station. Here, however,
`the inner products of the same orthogonal codes assumes
`particular values and the inner products of different orthogo-
`nal codes assume a value of zero. Therefore, the alert signals
`containing a plurality of orthogonal codes are multiplied by
`each of a plurality of orthogonal codes generated by the base
`station, and the results of multiplication are checked for each
`of the orthogonal codes. Even when the plurality of orthogo-
`nal codes are contained in the alert signals, therefore, it is
`possible to check if particular orthogonal codes are con-
`tained.
`
`According to the mobile communication apparatus as
`described above, the results of multiplication of the same
`orthogonal codes assume particular values and the results of
`multiplication of different orthogonal codes assume a value
`of zero. This makes it possible to detect the individual alert
`signals even when the alert signals are transmitted from the
`mobile terminals to the base station.
`
`(6) In the mobile communication apparatus described in
`(5) above, the alert signal reception means is provided with
`an accumulation means for accumulating the results of
`multiplication of the alert signals transmitted from the
`mobile terminals to the base station and the orthogonal
`codes generated in the base station for each of a plurality of
`bit periods constituting the orthogonal codes. When the base
`station receives alert signals from the mobile terminals, the
`alert signal reception means multiplies the alert signals
`transmitted from the mobile terminals to the base station by
`orthogonal codes generated by the base station, and the
`accumulation means accumulates the results of multiplica-
`tion for each of a plurality of bit periods constituting the
`orthogonal codes. When the inner products of the orthogonal
`codes in the alert signals that are received and the orthogonal
`codes generated by the base station are accumulated for each
`of a plurality of bit periods constituting the orthogonal
`codes, the noise component in each bit period is canceled
`and the S/N ratio of the alert signals is improved. Therefore,
`it becomes possible to maintain the output value of the alert
`
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`7
`signals transmitted from the mobile terminals in the mobile
`communication apparatus at a low level. This saves the
`output of the alert channel for transmitting the alert signals
`and increases the number of data channels.
`
`According to the mobile communication apparatus as
`described above, reception of the alert signals is detected by
`accumulating the orthogonal codes for a plurality of bit
`periods, making it possible to maintain the output value of
`the alert signals transmitted from the mobile terminals at a
`low level.
`
`These and other objects, features and advantages of the
`present invention will become more apparent in view of the
`following detailed description of the preferred embodiments
`in conjunction with