USOO7532572B2
`
`(12) United States Patent
`Chen et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,532,572 B2
`May 12, 2009
`
`(54) PACKET COMMUNICATIONS SYSTEM,
`BASE STATION AND MOBILE STATION
`
`(75) Inventors: Lan Chen, Yokohama (JP): Daisuke
`Kitazawa, Kawasaki (JP); Hidetoshi
`Kayama, Yokohama (JP): Narumi
`Umeda, Yokohama (JP)
`
`(73) Assignee: NTT DoCoMo, Inc., Tokyo (JP)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 806 days.
`(21) Appl. No.: 10/845,351
`(22) Filed:
`May 14, 2004
`(65)
`Prior Publication Data
`US 2005/OO25056A1
`Feb. 3, 2005
`Foreign Application Priority Data
`(30)
`May 16, 2003
`(JP)
`.......................... P 2003-139588
`
`(51) Int. Cl.
`(2006.01)
`H04B 7/24
`(2006.01)
`H04.3/14
`(52) U.S. Cl. ....................... 370/230; 370/329; 370/341:
`37O/349
`(58) Field of Classification Search ......... ... None
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`6,414,943 B1* 7/2002 Hwang et al. ............... 370,310
`
`1/2005 Lee et al. .................... 455,453
`6,842,619 B2
`6,850,509 B2 * 2/2005 Lee et al. ..........
`... 370,336
`6,865,169 B1* 3/2005 Quayle et al. .....
`... 370,335
`7,003,302 B2 * 2/2006 Yoshida et al. .............. 455,450
`2003/0081664 A1* 5/2003 Lu et al. ..................... 375.222
`2003/O120802 A1* 6/2003 Kohno ........................ 709/237
`2003/0.1334.57 A1* 7/2003 Ono et al. ................ 370,395.4
`2003/0231598 A1* 12/2003 Venkataraman et al. ..... 370,252
`
`JP
`JP
`
`FOREIGN PATENT DOCUMENTS
`2000-232402
`8, 2000
`2002-171573
`6, 2002
`
`* cited by examiner
`Primary Examiner Chi H. Pham
`Assistant Examiner Soon D. Hyun
`(74) Attorney, Agent, or Firm Oblon, Spivak, McClelland,
`Maier & Neustadt, P.C.
`(57)
`ABSTRACT
`
`In a packet communications method of performing packet
`communications between a mobile station and a base station,
`the base station manages an amount of packets stored in a
`9.
`oI p
`transmission buffer of the mobile station. The mobile station
`notifies a changed result of an amount ofpackets stored in the
`transmission buffer of the mobile station, when the amount of
`packets stored in the transmission buffer of the mobile station
`changes. The base station changes a managed amount in
`accordance with the changed result notified from the mobile
`Stat1On.
`
`13 Claims, 10 Drawing Sheets
`
`VIRTUAL BUFFER
`CORRESPONDING TO
`MOBILE STATION 30
`13
`
`PACKET #4
`PACKET E3
`PACKET #2
`PACKET #1
`
`Eso
`CORRESPO
`MOBILE ston 30
`
`PACKET #2
`PACKET F1
`
`VIRTUAL BUFFER
`MANAGENG UNIT
`
`
`
`
`
`RESOURCE
`ALLOCATING UNIT
`
`TRANSMING
`UNIT
`
`RESERVATION
`RECOGNIZING UNIT
`
`RECEIVING
`UNIT
`
`BASE STATION 10
`
`Ericsson Exhibit 1006
`Page 1
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`

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`U.S. Patent
`
`May 12, 2009
`
`Sheet 1 of 10
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`US 7,532,572 B2
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`01 NOIIVIS 3SWQ
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`Ericsson Exhibit 1006
`Page 2
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`U.S. Patent
`
`May 12, 2009
`
`Sheet 2 of 10
`
`US 7,532,572 B2
`
`FIG.2
`
`TRANSMISSION
`BUFFER
`
`JUDGENG
`UNIT
`
`RESERVING
`UNIT
`
`TRANSMTTING
`UNIT
`
`RESERVATION RESPONSE
`RECOGNIZING UNIT
`
`RECEIVING
`UNIT
`
`
`
`MOBILESTATION 30
`FG,3
`
`DOES
`NEFAs
`
`GENERATE PLUS
`RESERVATION
`
`GENERATE MNLS
`RESERVATION
`
`TRANSMISSION
`
`Ericsson Exhibit 1006
`Page 3
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`

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`U.S. Patent
`
`May 12, 2009
`
`Sheet 3 of 10
`
`US 7,532,572 B2
`
`FG4
`
`START
`
`---, IS
`
`RESERVATION RECEIVED
`
`
`
`
`
`DELETE PACKET IN
`VIRTUAL BUFFER
`
`
`
`
`
`
`
`PLUS RESERVATION?
`YES
`
`S2O2
`
`STORE ARRIVAL TIME h-S204
`
`ADD PACKET TO
`VIRTUAL BUFFER
`
`S205
`
`Ericsson Exhibit 1006
`Page 4
`
`

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`U.S. Patent
`
`May12, 2009
`
`Sheet 4 of 10
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`US 7,532,572 B2
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`Ericsson Exhibit 1006
`Page 5
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`Ericsson Exhibit 1006
`Page 5
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`

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`U.S. Patent
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`May 12, 2009
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`Sheet 5 of 10
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`US 7,532,572 B2
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`FIG.6
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`DOES
`NEW PACKET OCCUR 2
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`GENERATE PLUS
`RESERVATION
`
`IS PACKET DISCARDED
`
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`GENERATE MINUS
`RESERVATION
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`TRANSMISSION
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`DOES PACKE
`TO BE RE-TRANSMITTED
`OCCUR 2
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`S303
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`START
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`le.
`
`IS RESERVATION RECEIVED2
`YES
`S401
`
`PLUS RESERVATION?
`YES
`
`STORE ARRIVAL TIME
`
`
`
`
`
`S402
`S404
`
`ADD PACKET TO
`VIRTUAL BUFFER
`
`
`
`S405
`
`SRADIO RESOURCE
`ALLOCATED
`
`
`
`YES
`
`S406
`
`DELETE PACKET IN
`VIRTUAL BUFFER
`
`Ericsson Exhibit 1006
`Page 6
`
`

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`U.S. Patent
`
`May12, 2009
`
`Sheet 6 of 10
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`Ericsson Exhibit 1006
`Page 7
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`Ericsson Exhibit 1006
`Page 7
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`U.S. Patent
`
`May12, 2009
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`Sheet 7 of 10
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`Ericsson Exhibit 1006
`Page 8
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`Ericsson Exhibit 1006
`Page 8
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`

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`U.S. Patent
`
`May 12, 2009
`
`Sheet 8 of 10
`
`US 7,532,572 B2
`
`FG, 10
`
`-3. NEW PACKET
`
`
`
`OCCUR 2
`Y
`GENERATE PLUS
`RESERVATION
`
`TRANSMISSION
`
`FIG, 11
`
`
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`RESERVATION
`RECEIVED
`
`IS THERE ANY PACKET
`HAVING BEEN QUEUED MORE THAN
`THE MAXIMUM ACCEPTABLE
`QUEUE TIME?
`
`IS THERE
`ANY D PACKET WHICH IS
`RECEIVEDSUCCESSFULLY
`
`STORE ARRIVAL TIME
`
`ADD PACKET TO
`VIRTUAL BUFFER
`
`DELETE PACKE IN
`VIRTUAL BUFFER
`
`Ericsson Exhibit 1006
`Page 9
`
`

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`U.S. Patent
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`May12, 2009
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`Sheet 9 of 10
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`Page 10
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`Ericsson Exhibit 1006
`Page 10
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`U.S. Patent
`
`May 12, 2009
`
`Sheet 10 of 10
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`US 7,532,572 B2
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`Ericsson Exhibit 1006
`Page 11
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`

`

`1.
`PACKET COMMUNICATIONS SYSTEM,
`BASE STATION AND MOBILE STATION
`
`US 7,532,572 B2
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application is based upon and claims the benefit of
`priority from the prior Japanese Patent Application No.
`P2003-139588, filed on May 16, 2003; the entire contents of
`which are incorporated herein by reference.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`15
`
`25
`
`1. Field of the Invention
`The present invention relates to a packet communications
`method of performing packet communications between a
`mobile station and a base station. The present invention
`relates to a base station and a mobile station which can imple
`ment the packet communications method.
`2. Description of the Related Art
`Conventionally, an “HSDPA (High Speed Downlink
`Packet Access' method which is a downlink high-speed
`packet communications method is formally specified in a
`3GPP (3' Generation Partnership Project).
`To be more specific, an “RR (Round Robin) scheme, a
`“Max C/I (Maximum Carrier/Interference) scheme and the
`like are proposed as a scheduling scheme in the downlink
`high-speed packet communications method.
`In the conventional downlink high-speed packet commu
`nications method, a transmission buffer (a queue) corre
`30
`sponding to each mobile station is provided in a base station,
`so that the base station can perform efficient scheduling pro
`cessing in consideration of an arrival time of downlink pack
`ets, a size of the transmission buffer (a length of the queue)
`and the like.
`On the other hand, in the conventional uplink high-speed
`packet communications method, a transmission buffer of
`each mobile station is provided in the mobile station.
`Therefore, a scheme in which each mobile station periodi
`cally reports an amount of packets stored in the transmission
`buffer to the base station so that the base station can perform
`the scheduling processing are proposed.
`However, there is a problem in that each mobile station
`requires a lot of “notification bits’ to report the amount of
`packets stored in the transmission buffer, so that system effi
`45
`ciency is reduced due to a control load, in the conventional
`uplink high-speed packet communications method.
`There is a problem in that a dynamic change of an amount
`of packets stored in the transmission buffer, which is caused
`by an occurrence of packets to be transmitted, an occurrence
`of packet discard and the like, can not be reflected to the base
`station in real time, so that efficient scheduling processing can
`not be performed, wasted radio resources are allocated and
`the quality of service is degraded, in the conventional uplink
`high-speed packet communications method.
`
`35
`
`40
`
`50
`
`55
`
`BRIEF SUMMARY OF THE INVENTION
`
`In viewing of the foregoing, it is an object of the present
`invention to perform the efficient scheduling processing and
`to allocate radio resources efficiently in the uplink high-speed
`packet communications method.
`A first aspect of the present invention is Summarized as a
`packet communications method of performing packet com
`munications between a mobile station and a base station.
`65
`In the packet communications method, the base station
`manages an amount of packets stored in a transmission buffer
`
`60
`
`2
`of the mobile station. The mobile station notifies a changed
`result of an amount of packets stored in the transmission
`buffer of the mobile station, when the amount of packets
`stored in the transmission buffer of the mobile station
`changes. The base station changes a managed amount in
`accordance with the changed result notified from the mobile
`station.
`A second aspect of the present invention is Summarized as
`a base station which performs packet communications with a
`mobile station. The base station includes a manager config
`ured to manage an amount of packets stored in a transmission
`buffer of the mobile station. The manager is configured to
`change a managed amount in accordance with a changed
`result of an amount of packets stored in the transmission
`buffer of the mobile station. The changed result is notified
`from the mobile station.
`A third aspect of the present invention is Summarized as a
`mobile station which performs packet communications with a
`base station. The mobile station includes a transmission
`buffer configured to store packets to be transmitted to the base
`station and a notifier configured to notify a change result of an
`amount ofpackets stored in the transmission buffer to the base
`station when the amount of packets stored in the transmission
`buffer changes.
`
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWINGS
`
`FIG. 1 is functional block diagram of a base station accord
`ing to a first embodiment of the present invention;
`FIG. 2 is functional block diagram of a mobile station
`according to the first embodiment;
`FIG. 3 is a flowchart showing an operation of the mobile
`station according to the first embodiment;
`FIG. 4 is a flowchart showing an operation of the base
`station according to the first embodiment;
`FIG. 5 is a sequence diagram showing a packet communi
`cations method according to the first embodiment;
`FIG. 6 is a flowchart showing an operation of the mobile
`station according to a second embodiment of the present
`invention;
`FIG. 7 is a flowchart showing an operation of the base
`station according to the second embodiment;
`FIG. 8 is a sequence diagram showing a packet communi
`cations method according to the second embodiment;
`FIG.9 is functional block diagram of a base station accord
`ing to a third embodiment of the present invention;
`FIG. 10 is a flowchart showing an operation of the mobile
`station according to the third embodiment;
`FIG. 11 is a flowchart showing an operation of the base
`station according to the third embodiment;
`FIG. 12 is a sequence diagram showing a packet commu
`nications method according to the third embodiment; and
`FIG. 13 is functional block diagram of a base station
`according to a first embodiment of the present invention.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`<A Configuration of a First Embodiment of the Present
`Invention>
`Referring to FIGS. 1 and 2, configurations of a base station
`and a mobile station which implement a packet communica
`tions method according to a first embodiment of the present
`invention will be described.
`
`Ericsson Exhibit 1006
`Page 12
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`

`

`US 7,532,572 B2
`
`10
`
`15
`
`3
`FIG. 1 shows functional blocks of the base station 10
`according to the first embodiment, and FIG. 2 shows func
`tional blocks of the mobile station 30 according to the first
`embodiment.
`As shown in FIG. 1, the base station 10 includes a receiving
`unit 11, a reservation recognizing unit 12, a virtual buffer
`managing unit 13, a resource allocating unit 14 and a trans
`mitting unit 15.
`The receiving unit 11 is configured to receive uplink pack
`ets via a common packet channel (CPCH), and to receive “a
`change result of the number of packets (a change result of an
`amount of packets)”, “communication quality information of
`packets” and the like via a uplink dedicated control channel
`(DCCH).
`The change result of the number of packets includes a “plus
`reservation' and a “minus reservation'. The plus reservation
`shows the number of packets which increase in a transmission
`buffer 35 of the mobile station 30 (an increment amount of
`packets stored in the transmission buffer 35 of the mobile
`station 30). The minus reservation shows the number of pack
`ets which decrease in a transmission buffer 35 of the mobile
`station 30 (a decrement amount of packets stored in the trans
`mission buffer 35 of the mobile station 30).
`For example, the plus reservation including information of
`“+2 shows that the number of packets stored in the transmis
`sion buffer 35 increases by two.
`The minus reservation including information of "-2
`shows that the number of packets stored in the transmission
`buffer 35 decreases by two.
`The reservation recognizing unit 12 is configured to rec
`ognize the plus reservation or the minus reservation which are
`included the change result of the number of packets notified
`from the mobile station 30. The reservation recognizing unit
`12 is configured to notify the recognized result to the virtual
`buffer managing unit 13.
`The reservation recognizing unit 12 can be configured to
`notify an arrival time of the change result of the number of
`packets to the virtual buffer managing unit 13, when the
`change result of the number of packets includes the plus
`40
`reservation.
`The virtual buffer managing unit 13 is configured to man
`age the number of packets (an amount of packets) stored in
`the transmission buffer 35 of each mobile station 30 to 30.
`The virtual buffer managing unit 13 is configured to change
`45
`the number of packets stored in the transmission buffer 35 of
`each mobile station 30 to 30, in accordance with a change
`result (the plus reservation or the minus reservation) of the
`number of packets stored in the transmission buffer 35 of each
`mobile station 30 to 30. The change result is notified from
`each mobile station 30 to 30.
`To be more specific, the virtual buffer managing unit 13 is
`configured to manage virtual buffer 13 to 13 corresponding
`to each mobile station 30 to 30.
`The virtual buffer managing unit 13 is configured to store
`the same number of packets as packets stored in the transmis
`sion buffer 35 of each mobile station 30 to 30, in each virtual
`buffer 13 to 13.
`The virtual buffer managing unit 13 is configured to change
`(increase or decrease) packets stored in each virtual buffer
`13 to 13, corresponding to each mobile station 30 to 30, in
`accordance with the change result of the numbers of packets
`stored in the transmission buffer35 of each mobile station 30
`to 30.
`In an example of FIG.1, the virtual buffer managing unit 13
`stores four packets (packets #1 to #4) in the virtual buffer 13
`corresponding to the mobile station 30. And the virtual
`
`50
`
`4
`buffer managing unit 13 stores two packets (packets #1 and
`#2) in the virtual buffer 13, corresponding to the mobile
`station 30,
`The virtual buffer managing unit 13 adds two packets to the
`virtual buffer 13, corresponding to the mobile station 30,
`when receiving a notification showing that the reservation
`recognizing unit 12 has recognized a plus reservation includ
`ing information "+2.
`On the other hand, the virtual buffer managing unit 13
`deletes one packet from the virtual buffer 13 corresponding
`to the mobile station 30, when receiving a notification show
`ing that the reservation recognizing unit 12 has recognized a
`minus reservation including information'-2'.
`The virtual buffer managing unit 13 can be configured to
`delete packets stored in the virtual buffer 13, in predeter
`mined order.
`When adding a packet to the virtual buffer 13, to 13, the
`virtual buffer managing unit 13 can be configured to associate
`the added packet with an additional time of the packet.
`Because the packet is added to the virtual buffer 13 to 13,
`in a short time after the change result of the number of packets
`arrives at the base station 10, the virtual buffer managing unit
`13 can be configured to regard an arrival time of the change
`result as the additional time of the packet.
`The virtual buffers 13 to 13, can have the same sizes, and
`the virtual buffers 13 to 13, can have different sizes in accor
`dance with the number of packets stored in the transmission
`buffer 35.
`The resource allocating unit 14 is configured to allocate a
`radio resource which is used in uplink packet communica
`tions with the mobile station, by referring to the virtual buffer
`corresponding to the mobile station 30.
`For example, the resource allocating unit 14 can allocate
`the radio resources (for example, radio channels, codes and
`transmission timings) to packets stored in the virtual buffer
`managed by the virtual buffer managing unit 13, in ascending
`order of a packet number starting from a packet #1.
`The transmitting unit 15 is configured to notify the radio
`resources allocated by the resource allocating unit 14 to the
`mobile station via a downlink dedicated control channel
`(DCCH).
`As shown in FIG. 2, the mobile station 30 includes a
`receiving unit 31, a reservation response recognizing unit 32.
`a judging unit 33, a reserving unit 34, a transmission buffer 35
`and a transmitting unit 36.
`The receiving unit 31 is configured to receive a notification
`of the radio resources allocated by the resource allocation unit
`14 from the base station 10 via the downlink DCCH.
`The reservation response recognizing unit 32 is configured
`to instruct the transmitting unit 36 to transmit uplink packets
`using the radio resources (for example, a radio channel, a
`code and a transmitting timing) notified by the resource allo
`cation unit 14.
`The judging unit 33 is configured to judge whether a pre
`determined situation occurs or not.
`For example, the judging unit 33 can judge whether a
`packet has been generated to be transmitted to the base station
`10 or not. The judging unit 33 can judge whether a packet has
`been discarded in the transmission buffer 35 or not.
`The judging unit 33 can judge whether a packet has been
`transmitted to the base station successfully or not. To be more
`specific, the judging unit 33 can judge whether or not to
`receive an ACK signal related to the transmitted packet.
`The judging unit 33 can judge whether a packet has been
`generated to be re-transmitted to the base station 10 or not. In
`other words, the judging unit 33 can judge whether transmis
`sion of the packet to the base station 10 fails or not. To be more
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`specific, the judging unit 33 can judge whether or not to
`receive a NACK signal related to the transmitted packet.
`The reserving unit 34 is configured to generate the change
`result including the plus reservation or the minus reservation,
`in accordance with a judgment result from the judging unit
`33.
`When packets to be transmitted to the base station 10 are
`generated, the reserving unit 34 is configured to generate a
`plus reservation including the number of generated packets,
`as an increment number (amount) of packets stored in the
`transmission buffer.
`When packets stored in the transmission buffer 35 are
`discarded, the reserving unit 34 is configured to generate a
`minus reservation including the number of discarded packets,
`as a decrement number (amount) of packets stored in the
`transmission buffer.
`The transmission buffer 35 is configured to store packets to
`be transmitted to the base station 10. The transmission buffer
`35 can be configured to store the generated packets, by using
`a method of inserting the generated packets into the queue in
`accordance with a predetermined scheduling scheme.
`The transmission buffer 35 can be configured to discard
`packets which have elapsed for a predetermined period since
`the packets were stored in the virtual buffer, packets which
`have been re-transmitted a predetermined number of times,
`packets which a user has cancelled to transmit and the like.
`The transmitting unit 36 is configured to transmit packets
`stored in the transmission buffer 35 to the base station 10 via
`the uplink CPCH. The transmitting unit 36 is configured to
`transmit the packets by using the radio resource instructed by
`the reservation response recognizing unit 32.
`The transmitting unit 36 is configured to transmit the
`change result including the plus reservation or the minus
`reservation generated by the reserving unit 34 to the base
`station 10 via the uplink DCCH.
`The transmitting unit 36 is configured to transmit the num
`ber of packets stored in the transmission buffer 35 at a pre
`determined interval, so as to synchronize between the trans
`mission buffer 35 and the virtual buffer in the virtual buffer
`managing unit 13 of the base station 10.
`In the embodiment, the judging unit 33, the reserving unit
`34 and the transmitting unit 36 constitute a notifier configured
`to notify a change result of an amount (number) of packets
`stored in the transmission buffer 35 to the base station 10,
`each time the amount (number) of packets stored in the trans
`mission buffer changes.
`<An Operation of the First Embodiment>
`First, referring to FIG.3, an operation of the mobile station
`30 according to the first embodiment will be described.
`As shown in FIG.3, in step S101, the judging unit 33 of the
`mobile station 30 judges whether packets to be transmitted to
`the base station 10 are generated or not, by monitoring an
`input operation of a user and the like. When the answer is
`YES, the operation moves to step S104. On the other hand,
`when the answer is NO, the operation moves to step S102.
`In step S102, the judging unit 33 judges whether packets
`which have elapsed for a predetermined period since the
`packets were stored in the virtual buffer, packets which have
`been re-transmitted a predetermined number of times, pack
`ets which a user has cancelled to transmit and the like are
`discarded or not, by monitoring the transmission buffer 35.
`When the answer is YES, the operation moves to step S105.
`On the other hand, when the answer is NO, the operation
`moves to step S103.
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`In step S103, the judging unit 33 judges whether packets
`are transmitted to the base station 10 successfully or not, by
`monitoring the transmitting unit 36.
`To be more specific, the judging unit 33 judges that packets
`are transmitted to the base station 10 successfully, when the
`transmitting unit 26 receives an ACK signal from the base
`station 10. When the answer is YES, the operation moves to
`step S105. On the other hand, when the answer is NO, the
`operation returns to step S101.
`In step S104, the reserving unit 34 of the mobile station 30
`generates a plus reservation including the number of packets
`generated to be transmitted to the base station 10, as an
`increment number of packets stored in the transmission buffer
`35.
`In step S105, the reserving unit 34 of the mobile station 30
`generates a minus reservation including the number of dis
`carded packets or the number of packets which have been
`transmitted to the base station 10 successfully, as a decrement
`number of packets stored in the transmission buffer 35.
`In step S106, the transmitting unit 36 of the mobile station
`30 transmits the plus reservation or the minus reservation
`generated by the reserving unit 34 to the base station 10 via
`the uplink DCCH.
`The mobile station 30 is configured to perform steps S101
`to S106 repeatedly. The mobile station 30 can be configured
`to perform steps S101 to S103 in parallel.
`Second, referring to FIG.4, an operation of the base station
`10 according to the first embodiment will be described.
`In step S201, the receiving unit 11 of the base station 10
`determines whether or not to receive the change result of the
`number of packets from the mobile station 30, by monitoring
`the uplink DCCH.
`When the receiving unit 11 determines to receive the
`change result, in step S201, the reservation recognizing unit
`12 of the base station 10 recognizes a plus reservation or a
`minus reservation which are included the change result
`received by the receiving unit 11.
`When a minus reservation is determined to be included in
`the change result, in step S203, the virtual buffer managing
`unit 13 of the base station 10 deletes packets corresponding to
`a decrement number of packets included in the minus reser
`vation, from the virtual buffer corresponding to the mobile
`station which has transmitted the minus reservation.
`On the other hand, when a plus reservation is determined to
`be included in the change result, the virtual buffer managing
`unit 13 stores a reception time (an arrival time) of the plus
`reservation in step S204, and add packets corresponding to an
`increment number of packets included in the plus reservation
`in the transmission buffer 35, so as to associate the added
`packet with the reception time, in step S205.
`Third, referring to FIG. 5, an example of the packet com
`munications method according to the first embodiment will
`be described.
`In step S1001, the judging unit 33 detects that two packets
`to be transmitted to the base station 10 are generated, and the
`reserving unit 34 generates a plus reservation (+2) including
`information showing that the number of packets stored in the
`transmission buffer 35 increases by two.
`In step S1002, the transmitting unit 36 transmits the plus
`reservation (+2) to the base station 10 via the uplink DCCH.
`In step S1003, the reservation recognizing unit 12 notifies
`the plus reservation and the arrival time of the plus reservation
`to the virtual buffer managing unit 13.
`In step S1004, the virtual buffer managing unit 13 adds two
`packets to the virtual buffer corresponding to the mobile
`station 30, in accordance with the notification from the res
`ervation recognizing unit 12.
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`The virtual buffer managing unit 13 can associate the
`added packets with the arrival time of the plus reservation as
`the addition time of the packets.
`In step S1005, the resource allocating unit 14 allocates
`radio resources (for example, a radio channel, a code and a
`transmission timing), by referring to the virtual buffer corre
`sponding to the mobile station30. In an example of FIG. 5, the
`resource allocating unit 14 allocates radio resources for three
`packets.
`In step S1006, the transmitting unit 15 notifies the radio
`resources allocated by the resource allocating unit 14 to the
`mobile Station 30 via the downlink DCCH.
`In step S1007, the transmitting unit 36 transmits three
`packets to the base station 10 via the uplink CPCH, by using
`the radio resources instructed by the reservation response
`recognizing unit 32.
`Then, the judging unit 33 detects that three packets have
`been transmitted to the base station 10 successfully and the
`number of packets stored in the transmission buffer 35
`decreases by three. The reserving unit 34 generates a minus
`reservation (-3) including information showing that the num
`ber of packets stored in the transmission buffer 35 decreases
`by three.
`In step S1008, the transmitting unit 36 transmits the minus
`reservation (-3) to the base station 10 via the uplink DCCH.
`In step S1009, the reservation recognizing unit 12 notifies
`reception of the minus reservation (-3) to the virtual buffer
`managing unit 13.
`Then, the virtual buffer managing unit 13 deletes three
`packets from the virtual buffer corresponding to the mobile
`station 30, in accordance with the notification from the res
`ervation recognizing unit 12.
`In step S1010, the transmission buffer 35 discards two
`packets which have elapsed for a predetermined period since
`the packets were stored in the virtual buffer.
`Then, the judging unit 33 detects that the number of pack
`ets stored in the transmission buffer 35 decreases by two. The
`reserving unit 34 generates a minus reservation (-2) includ
`ing information showing that the number of packets stored in
`the transmission buffer 35 decreases by two.
`In step S1011, the transmitting unit 36 transmits the minus
`reservation (-2) to the base station 10 via the uplink DCCH.
`In step S1012, the reservation recognizing unit 12 notifies
`reception of the minus reservation (-2) to the virtual buffer
`managing unit 13.
`Then, the virtual buffer managing unit 13 deletes two pack
`ets from the virtual buffer corresponding to the mobile station
`30, in accordance with the notification from the reservation
`recognizing unit 12.
`<Functions and Effects of the First Embodiment>
`According to the packet communications method of the
`first embodiment, the mobile station 30 is configured to notify
`the change result of the number of packets (the plus reserva
`tion or the minus reservation) to the base station 10, each time
`the number of the packets stored in the transmission buffer 35
`changes, so that the base station 10 can grasp a dynamic
`change in the transmission buffer 35 of the mobile station 30
`in real time.
`According to the packet communications method of the
`first embodiment, the mobile station 30 is configured to notify
`the change result of the number of packets having a small
`amount of data to the base station 10, so as to prevent an
`amount of traffic between the mobile station 30 and the base
`station 10 from increasing.
`According to the packet communications method of the
`first embodiment, the base station 10 only increases or
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`decreases the number of packets stored in the virtual buffer
`corresponding to the mobile station 30 in accordance with the
`change result of the number of packets, so as to prevent
`system efficiency due to a control load from being reduced.
`According to the packet communications method of the
`first embodiment, the virtual buffer managing unit 13
`increases or decreases the number of packets stored in the
`virtual buffer corresponding to the mobile station 30 in accor
`dance with the change result of the number of packets notified
`from the mobile station 30, so as to follow a change in the
`transmission buffer 35 of the mobile station 30 in real time
`with a light control load.
`According to the packet communications method of the
`first embodiment, the resource allocating unit 14 allocate
`radio resources which are used in the uplink packet commu
`nications with the mobile station 30 by referring to the virtual
`buffer corresponding