JP2007006230A - Base station apparatus, communication terminal apparatus, control station apparatus, and queue management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform smoothly taking over queue at the time of handover, and to perform seamless handover without any data loss by performing the same queue management as the base station of a handover source before the handover in a base station of a handover destination. <P>SOLUTION: A retransmission control unit 105 indicates deletion of packet data to be specified by ACK information indicating reception success relating to a storing unit 107. The retransmission control unit 105 also gives TSN for handover destination base station to packet data stored in the storing unit 107. The storing unit 107 having the queue characterized in firstly outputting the packet data which is firstly stored therein is designed to store temporarily the packet data, and to delete the packet data indicated by the retransmission control unit 105. The storing unit 107 is designed to store the packet data which are added with the TSN for the handover destination base station at the retransmission control unit 105. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a base station apparatus, a communication terminal apparatus, a control station apparatus, and a queue management method, and particularly to a base station apparatus, a communication terminal apparatus, a control station apparatus, and a queue management method used for downlink high-speed packet transmission at the time of handover.

  In 3GPP, HSDPA (High Speed Downlink Packet Access), which realizes a maximum downlink rate (maximum throughput) of 2 Mbps or more based on the W-CDMA system, has been studied, and is moving to the commercialization stage (for example, non- Patent Document 1). In HSDPA, for example, adaptive modulation / demodulation and error correction coding (AMC) technology based on downlink quality such as SINR, hybrid automatic repeat request (HARQ) technology, and packet scheduling technology that assigns a line to each user at high speed are applied. Achieve high throughput.

  FIG. 9 is a diagram showing a configuration of a communication system assumed by HSDPA. In applying HSDPA, the base station 10 temporarily stores packet data of each mobile station (not shown) transferred from the control station 11 in a queue buffer. Then, the base station 10 transmits packet data to which a transmission opportunity is assigned by packet scheduling at a transmission rate determined by adaptive modulation based on downlink quality and error correction coding technology. Here, the transmission rate is set using the transport block length, the number of physical channels, and the modulation scheme as parameters.

  FIG. 10 is a diagram illustrating a configuration of a MAC-hs unit of a base station that performs queue control, HARQ control, and the like (for example, Non-Patent Document 2). Packet data transmitted from the control station to the base station is distributed to a queue (Priority Queue) 21 by a scheduling / priority control unit (Scheduling / Priority handling) 20 according to the priority class of the data. The HARQ control unit (HARQ entity) 22 determines whether the next transmission is an initial transmission or a retransmission from the ACK / NACK information during uplink signaling using the N-channel stop and wait method. The scheduling / priority control unit 20 assigns a queue ID (Queue ID) and a transmission sequence number (TSN) to the new packet data. Specifically, the queue ID and the transmission sequence number are given to the header part in the MAC-hs PDU (Protocol Data Unit). The MAC-hs PDU corresponds to a transport block in the physical layer, that is, one retransmission unit. A TFRC (Transport Format and Resource Combination) selection unit (TFRC selection) 23 determines a radio resource used for transmitting packet data, and generates a TFRI (Transport Format and Resource Indicator). If the packet data in the queue transmitted to the mobile station on the downlink is successfully communicated, an ACK signal is returned on the uplink control channel, and the packet data is deleted from the queue 21. On the other hand, when the packet data in the queue 21 transmitted to the mobile station on the downlink fails to communicate, a NACK signal is returned on the uplink control channel, and retransmission processing is performed under the control of the HARQ control unit 22. Applied. In this way, queue management is performed based on ACK / NACK information of the uplink control channel.

  Note that the queue structure is provided for each priority class in 3GPP, but what has been reported as a research for beyond 3G includes those provided for each user and those provided for each user and each priority class. It has been reported.

  Next, handover of the shared channel (HS-DSCH) for HSDPA will be described. FIG. 11 is a diagram illustrating a cell configuration at the time of HS-DSCH handover. The mobile station 30 changes from the cell # 1 which is an area covered by the base station 31 to the cell # 2 which is an area covered by the base station 32. This shows a situation where a handover is to be made.

At this time, when the mobile station 30 performs the HS-DSCH handover, it is desirable that a seamless handover regarding the packet data transmission can be performed if it is possible to smoothly transfer the contents of the queue related to the mobile station 30 from the base station 31 to the base station 32.
3GPP TR25.848V4.0.0 3GPP TS25.321V6.2.0

  However, in the conventional apparatus, there is a problem that the queue contents related to the mobile station 30 cannot be smoothly transferred from the base station 31 to the base station 32 when the mobile station 30 performs HS-DSCH handover. The reason is that when the handover source base station 31 transfers the queue contents to the handover destination base station 32 via the control station, there is a problem that the delay is large. In addition, since there is no wireless interface or wired interface between the base stations, there is a problem that the queue contents cannot be directly transferred between the base stations.

  Therefore, in the conventional apparatus, at the time of HS-DSCH handover, only the packet data that has been successfully ACKed in the mobile station 30 is transferred to the upper layer. Packet data remaining in the queue is discarded. Then, the handover destination base station 32 has a problem that the discarded packet data is not restored and transmitted by a method other than the retransmission process by the higher layer.

  Here, for example, in an interactive class service that requires highly reliable data transmission, an RLC sublayer operation that operates in the Acknowledge Mode is applied. The RLC exists in the control station and the mobile station, and retransmission control is performed regardless of the HS-DSCH handover operation. Therefore, retransmission is performed when packet data is lost. Then, the retransmission causes congestion in the TCP layer, which is an upper layer, and there is a problem that the bit rate is greatly reduced along with an increase in delay.

  The present invention has been made in view of this point, and by performing queue management equivalent to that of the handover source base station before the handover at the handover destination base station, it is possible to smoothly take over the queue at the time of handover. An object of the present invention is to provide a base station apparatus, a communication terminal apparatus, a control station apparatus, and a queue management method that can perform seamless handover without data loss.

  The base station apparatus of the present invention is a storage means for storing the same packet data as the other station that is the handover source received from the higher station apparatus, and a communication terminal apparatus for the packet data transmitted from the other station before the handover. When receiving the retransmission information, which is information indicating successful reception or reception failure, and the retransmission information indicating successful reception by the receiving means among the packet data stored in the storage means Retransmission control means for discarding the successfully received packet data stored in the storage means, and the storage means without being discarded by the retransmission control means after the communication terminal apparatus has handed over from the other station to the own station. And transmitting means for transmitting the remaining packet data to the communication terminal device.

  The communication terminal apparatus of the present invention includes a flag indicating that the packet data is stored in both the handover source base station apparatus and the handover destination base station apparatus, and is transmitted from the handover source base station apparatus Receiving means for receiving packet data, and the handover source base station apparatus and the handover destination base station which are information for identifying packet data with respect to the packet data including the flag received by the receiving means Identification information assigning means for assigning common identification information to the apparatus, error detection means for detecting an error in the received packet data, information on the detection result of the error detected by the error detection means, and the identification information giving means Transmitting the identification information assigned in step 1 to the handover destination base station apparatus before handover A configuration that includes a stage, the.

  The control station apparatus according to the present invention determines whether or not the communication terminal apparatus is to be handed over from the handover source base station apparatus to the handover destination base station apparatus based on information of a reception quality measurement result in the communication terminal apparatus. A flag indicating packet data to be transmitted to the handover source base station apparatus and the handover destination base station apparatus when a handover is determined by the determination means and the handover determination means. And a transmission means for transmitting the packet data to which the flag has been assigned by the flag assignment means to the handover source base station apparatus and the handover destination base station apparatus.

  In the queue management method of the present invention, the handover source base station apparatus and the handover destination base station apparatus receive and store the same packet data from the host station apparatus before the handover, and the handover source base station apparatus A step in which the handover base station apparatus and the handover source base station apparatus receive retransmission information that is information indicating successful reception or reception failure of the packet data transmitted from the communication terminal apparatus; A step of discarding the successfully received packet data stored in the handover source base station apparatus and the handover destination base station apparatus when the retransmission information is received.

  According to the present invention, by performing queue management equivalent to that of the handover source base station before the handover at the handover destination base station, the handover of the queue at the time of handover can be performed smoothly and seamless without data loss. Handover can be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of base station apparatus 100 according to Embodiment 1 of the present invention.

  The antenna 101 outputs the received signal to the RF receiving unit 102 and transmits packet data input from the RF transmitting unit 111 or a pilot signal input from the RF transmitting unit 113.

  The RF reception unit 102 down-converts the reception signal input from the antenna 101 from a radio frequency to a baseband frequency and outputs the down-converted signal to the demodulation unit 103.

  Demodulation section 103 demodulates the received signal input from RF receiving section 102 and outputs the demodulated signal to error correction decoding section 104.

  The error correction decoding unit 104 performs error correction decoding on the received signal input from the demodulation unit 103, and extracts and extracts ACK / NACK information (retransmission information) that is information indicating successful reception or reception failure in the communication terminal apparatus. ACK / NACK information is output to retransmission control section 105 and transmission priority control section 106. Further, error correction decoding section 104 performs error correction decoding on the received signal input from demodulation section 103, and extracts and extracts a handover destination base station TSN (identification information) that is information for identifying packet data. The handover destination base station TSN is output to the transmission priority control unit 106. Then, error correction decoding section 104 outputs the received signal after extracting the ACK / NACK information and the handover destination base station TSN as received data, and transmits it to the control station. At this time, the reception data transmitted to the control station includes reception quality information that is information indicating the reception quality of the communication terminal apparatus. Here, the handover destination base station TSN is an identifier for identifying packet data provided by the communication terminal apparatus, and is an identifier common to the handover source base station apparatus and the handover destination base station apparatus. is there. Details of the handover destination base station TSN will be described later.

  Based on the ACK / NACK information input from error correction decoding section 104, retransmission control section 105 instructs storage section 107 to delete the packet data specified by the ACK information indicating successful reception. In addition, retransmission control section 105 outputs NACK information indicating reception failure to transmission priority control section 106.

  The transmission priority control unit 106 receives packet data as transmission data from the control station and outputs the packet data to the storage unit 107. Also, the transmission priority control unit 106 assigns transmission opportunities to both the initial transmission packet data and the retransmission packet data stored in the storage unit 107 based on the retransmission information input from the retransmission control unit 105. Then, the transmission priority control unit 106 outputs the allocated transmission opportunity information to the storage unit 107 and the TFRI selection unit 108 as scheduling information. The transmission priority control unit 106 operates differently depending on whether the base station apparatus 100 is a handover source base station apparatus or a handover destination base station apparatus. Specifically, when the base station device 100 is a handover source base station device, the transmission priority control unit 106 assigns a transmission opportunity to new packet data when ACK information is received. When NACK information is received, a transmission opportunity is assigned to packet data to be retransmitted. On the other hand, when the base station device 100 is a handover destination base station device, the transmission priority control unit 106 does not perform transmission processing until the handover of the communication terminal device is completed. In addition, when the base station device 100 is a handover source base station device, the transmission priority control unit 106 sequentially sets its own station for packet data stored in the storage unit 107 in the order of storage. A unique TSN is assigned. On the other hand, when the base station device 100 is a handover destination base station device, the transmission priority control unit 106 receives the NACK information and the handover destination base station TSN, and stores the NACK stored in the storage unit 107. The handover destination base station TSN input from the error correction decoding unit 104 is added to the packet data specified by the information. At this time, the transmission priority control unit 106 recognizes that the NACK information and the handover destination base station TSN received in the same transmission time interval (TTI) are for the same packet data.

  The storage unit 107 is a queue having a feature that the packet data input first is output first. The storage unit 107 temporarily stores the packet data input from the transmission priority control unit 106 and also transmits the packet priority control unit 106. The stored packet data is output to error correction encoding section 109 based on the scheduling information input from. Further, the storage unit 107 deletes the packet data instructed from the retransmission control unit 105 among the stored packet data. In addition, when the base station device 100 is a handover source base station device, the storage unit 107 stores the packet data to which the transmission priority control unit 106 has added the TSN. Further, when the base station apparatus 100 is a handover destination base station apparatus, the storage section 107 stores packet data to which the handover destination base station TSN is assigned by the transmission priority control section 106. In addition, when the base station device 100 is a handover destination base station device, the storage unit 107 does not allocate a transmission opportunity by the transmission priority control unit 106, and thus only discards and stores packet data.

  Based on the scheduling information input from the transmission priority control unit 106, the TFRI selection unit 108 determines the transport format and resources used for the next transmission, and selects the TFRI, the coding rate, and the modulation multi-level number. Then, the TFRI selection unit 108 outputs the selected TFRI and coding rate information to the error correction coding unit 109 and outputs the selected modulation multilevel information to the modulation unit 110.

  The error correction encoding unit 109 adds the TFRI input from the TFRI selection unit 108 to the packet data input from the storage unit 107, and based on the coding rate information input from the TFRI selection unit 108, the TFRI. Is encoded at a predetermined encoding rate. Then, error correction encoding section 109 outputs the packet data to which the encoded TFRI is added to modulation section 110. The TFRI may be transmitted in advance on a physical channel different from the packet data.

  Based on the modulation multi-level information input from the TFRI selection unit 108, the modulation unit 110 converts the packet data added with the TFRI added from the error correction encoding unit 109 into a predetermined modulation multi-level modulation method. And then output to the RF transmitter 111.

  The RF transmission unit 111 up-converts the packet data added with the TFRI input from the modulation unit 110 from the baseband frequency to the radio frequency and outputs it to the antenna 101.

  Modulation section 112 modulates the pilot signal and outputs it to RF transmission section 113.

  The RF transmission unit 113 up-converts the pilot signal input from the modulation unit 112 from the baseband frequency to the radio frequency and outputs it to the antenna 101.

  Next, the configuration of communication terminal apparatus 200 according to Embodiment 1 of the present invention will be described using FIG. FIG. 2 is a block diagram showing a configuration of communication terminal apparatus 200. The ACK / NACK signal generation unit 205, the rearrangement unit 206, the decomposition processing unit 207, the duplicate transmission flag extraction unit 208, the TSN extraction unit 209, and the handover destination base station TSN generation unit 210 constitute a MAC-hs unit 216.

  The antenna 201 outputs the received signal to the RF receiving unit 202 and transmits the signal input from the RF transmitting unit 215.

  The RF reception unit 202 down-converts the reception signal input from the antenna 201 from a radio frequency to a baseband frequency and outputs the result to the demodulation unit 203.

  The demodulation unit 203 demodulates the reception signal input from the RF reception unit 202 and outputs the demodulated signal to the error correction decoding unit 204 and the reception quality measurement unit 211.

  Error correction decoding section 204 performs error correction decoding on the received signal input from demodulation section 203 and outputs the received signal to ACK / NACK signal generation section 205, duplicate transmission flag extraction section 208 and TSN extraction section 209.

  An ACK / NACK signal generation unit 205 serving as an error detection unit detects an error of the received packet data from the CRC result of the transport block of the packet data after error correction decoding (MAC-hs PDU) input from the error correction decoding unit 204. ACK / NACK information corresponding to the determination result is generated. Then, the ACK / NACK signal generation unit 205 outputs the generated ACK / NACK information to the rearrangement unit 206 and the error correction coding unit 213. Further, the ACK / NACK signal generation unit 205 outputs the packet data after determination of the presence / absence of an error to the rearrangement unit 206.

  The rearrangement unit 206 rearranges the packet data, which is input from the ACK / NACK signal generation unit 205, out of order due to retransmission or the like in the order of TSN based on the value of the TSN included in the MAC-hs PDU. The data is output to the decomposition processing unit 207.

  The disassembly processing unit 207 deletes the MAC-hs header and padding bits from the packet data input from the rearrangement unit 206, extracts the MAC-d PDU, and outputs the MAC-d PDU to the MAC-d unit (not shown).

  Duplicate transmission flag extraction section 208 extracts a duplicate transmission flag from the packet data after error correction decoding inputted from error correction decoding section 204 and outputs the extracted duplicate transmission flag to TSN generation section 210 for handover destination base station. .

  TSN extraction section 209 extracts TSN from the packet data after error correction decoding input from error correction decoding section 204, and outputs the extracted TSN to TSN generation section 210 for handover destination base station.

  The handover destination base station TSN generation unit 210 serving as identification information providing means, based on the duplicate transmission flag input from the duplicate transmission flag extraction unit 208 and the TSN input from the TSN extraction unit 209, Information). Then, handover destination base station TSN generation section 210 outputs the generated handover destination base station TSN to error correction encoding section 213. The handover destination base station TSN generation unit 210 makes an error in the handover destination base station TSN at the timing at which the NACK signal in the same packet data and the handover destination base station TSN are transmitted at the same transmission time interval (TTI). The data is output to the correction encoding unit 213.

  Reception quality measurement section 211 measures reception quality for each base station apparatus 100 using a pilot signal included in the reception signal input from demodulation section 203. Reception quality measuring section 211 then outputs the measurement result to reception quality information generating section 212.

  Reception quality information generation section 212 generates reception quality information based on the measurement result input from reception quality measurement section 211 and outputs the reception quality information to error correction encoding section 213. For example, the reception quality information generation unit 212 stores CQI selection information common to the base station apparatus 100 that associates SIR and CQI (Channel Quality Indicator) for the purpose of determining the MCS level of adaptive modulation. The CQI is selected by referring to the CQI selection information using the SIR measurement result. Alternatively, the reception quality itself used by the control station apparatus to determine handover may be reported to the control station apparatus. Then, reception quality information generation section 212 outputs the selected CQI or reception quality itself as reception quality information to error correction encoding section 213.

  Error correction coding section 213 performs error detection on packet data including ACK / NACK information input from ACK / NACK signal generation section 205, handover destination base station TSN input from handover destination base station TSN generation section, and transmission data. Corrected encoded and output to the modulation unit 214. In addition, when the reception quality information is input from the reception quality information generation unit 212, the error correction encoding unit 213 performs error correction encoding on the input reception quality information and outputs it to the modulation unit 214.

  Modulator 214 modulates the packet data or reception quality information input from error correction encoder 213 and outputs the result to RF transmitter 215.

  The RF transmission unit 215 up-converts the packet data or reception quality information input from the modulation unit 214 from the baseband frequency to the radio frequency and outputs the up-converted data to the antenna 201.

  Next, the configuration of control station apparatus 300 that is a higher station apparatus of base station apparatus 100 will be described using FIG. FIG. 3 is a block diagram illustrating a configuration of the control station apparatus 300.

  The wired data reception unit 301 receives the reception data transmitted from each base station device 100 and the reception quality information of the communication terminal device 200, outputs the reception data to the MAC-d unit 302, and decides handover of the reception quality information. The data is output to the unit 303.

  The MAC-d unit 302 performs MAC-d processing on the received data input from the wired data receiving unit 301 and outputs the processed data to an RLC unit (not shown). Further, the MAC-d unit 302 performs MAC-d processing on the transmission data input from the RLC unit and outputs the data to the wired data transmission unit 306.

  The handover determining unit 303 determines whether or not the communication terminal apparatus 200 is to be handed over based on the reception quality information input from the wired data receiving unit 301. When the handover determining unit 303 determines to perform handover, the handover determining unit 303 outputs handover determination information that is information instructing handover to the wired data transmission destination base station determining unit 304 and the duplicate transmission flag adding unit 305. .

  When the handover determination information is input from the handover determination unit 303, the wired data transmission destination base station determination unit 304 sends the communication data to each communication terminal device 200 with respect to the wired data transmission unit 306 based on the input handover determination information. The base station apparatus 100 that is a destination to which data is transmitted is notified. Specifically, the wired data transmission destination base station determination unit 304 is currently communicating with the wired data transmission unit 306 before the handover determination information is input, that is, the handover source base station device. 100 is instructed to send data. Also, the wired data transmission destination base station determination unit 304, with respect to the wired data transmission unit 306 and the handover source base station apparatus 100 currently in communication and the handover from the input of the handover determination information to the completion of the handover. The base station apparatus 100 is instructed to transmit data. Further, the wired data transmission destination base station determination unit 304 instructs the wired data transmission unit 306 to transmit data to the handover destination base station apparatus 100 after the handover is completed.

  When handover determination information is input from the handover determination unit 303, the duplicate transmission flag assignment unit 305 is configured to assign a duplicate transmission flag for each data transmission unit based on the input handover determination information. Is output to the wired data transmission unit 306. Specifically, the duplicate transmission flag assigning unit 305 outputs, for example, “0” of information indicating non-duplication as the duplicate transmission flag before the handover information is input, and after the handover determination information is input, the handover is performed. For example, “1”, which is information indicating duplication, is output as an duplication flag. Then, the duplicate transmission flag assigning unit 305 outputs, for example, “0” of information indicating non-duplication as a duplicate transmission flag after the handover is completed.

  The wired data sending unit 306 gives the duplicate transmission flag inputted from the duplicate transmission flag giving unit 305 to the transmission data inputted from the MAC-d unit 302, and is instructed by the wired data sending destination base station determining unit 304. To the base station apparatus 100. The duplicate transmission flag assigning unit 305 and the wired data sending unit 306 constitute a flag assigning unit.

  Next, operations of base station apparatus 100, communication terminal apparatus 200, and control station apparatus 300 will be described using FIG. FIG. 4 is a sequence diagram showing operations of base station apparatus 100, communication terminal apparatus 200, and control station apparatus 300. In FIG. 4, base station apparatus 100-1 is a handover source base station apparatus, and base station apparatus 100-2 is a handover destination base station apparatus. Further, the base station apparatus 100-1 and the base station apparatus 100-2 have the same configuration as that in FIG.

  First, in the control station device 300, since the communication terminal device 200 is before handover, the duplicate transmission flag assigning unit 305 outputs a duplicate transmission flag “0” indicating non-duplication, and the wired data sending unit 306 The duplicate transmission flag “0” is assigned. In addition, the wired data transmission destination base station determination unit 304 instructs the base station device 100-1 as a destination of transmission data. Then, the control station apparatus 300 transmits the packet data with the duplicate transmission flag “0” to the base station apparatus 100-1, and the base station apparatus 100-1 transmits the packet data with the duplicate transmission flag “0”. Receive (step ST401).

  Next, the base station apparatus 100-1 transmits the packet data assigned with the duplicate transmission flag “0” to the communication terminal apparatus 200, and the communication terminal apparatus 200 sends the packet data assigned with the duplicate transmission flag “0”. Receive (step ST402).

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data in error correction decoding section 204, and ACK / NACK signal generation section 205 determines whether reception has succeeded or has failed. As a result of the determination, if reception fails, the ACK / NACK signal generation unit 205 generates NACK information, the communication terminal apparatus 200 transmits the NACK information to the base station apparatus 100-1, and the base station apparatus 100-1 NACK information is received (step ST403). At this time, since the duplicate transmission flag extracted by the duplicate transmission flag extraction unit 208 is “0”, the handover destination base station TSN generation unit 210 does not generate the handover destination base station device TSN. The NACK information includes information that can identify packet data that has failed to be received.

  Next, base station apparatus 100-1 performs scheduling for retransmitting packet data of NACK information in transmission priority control section 106. Then, base station apparatus 100-1 transmits the packet data stored in storage section 107 as retransmission data, and communication terminal apparatus 200 receives the packet data as retransmission data (step ST404). At this time, the same duplicate transmission flag “0” as that at the first transmission is assigned to the packet data as the retransmission data. Thereafter, the processes of step ST403 and step ST404 are repeated until no NACK information is generated.

  Also, at a predetermined timing, base station apparatus 100-2 transmits a pilot channel pilot signal, and communication terminal apparatus 200 receives the pilot signal (step ST405). Similarly, base station apparatus 100-1 transmits a pilot channel pilot signal at a predetermined timing, and communication terminal apparatus 200 receives the pilot signal (step ST406).

  Next, communication terminal apparatus 200 generates reception quality information at reception quality information generation section 212 after measuring reception quality at reception quality measurement section 211, and a base station apparatus that is communicating the generated reception quality information 100-1 and the base station apparatus 100-1 receives the reception quality information (step ST407).

  Next, base station apparatus 100-1 transmits reception quality information to control station apparatus 300, and control station apparatus 300 receives the reception quality information (step ST408).

  Next, in control station apparatus 300, handover determining section 303 determines that communication terminal apparatus 200 is to be handed over from base station apparatus 100-1 to base station apparatus 100-2 based on the reception quality information.

  Next, control station apparatus 300 transmits a radio link establishment request to base station apparatus 100-2, and base station apparatus 100-2 receives the radio link establishment request (step ST409).

  Next, control station apparatus 300 transmits a physical channel setting request with base station apparatus 100-2 to communication terminal apparatus 200 via base station apparatus 100-1 (step ST410).

  Next, in the control station apparatus 300, the wired data transmission destination base station determination unit 304 transmits transmission data to the base station apparatus 100-1 and the base station apparatus 100-2 to the wired data transmission unit 306. At the same time, the duplicate transmission flag assigning unit 305 outputs the duplicate transmission flag “1”. Then, control station apparatus 300 assigns duplicate transmission flag “1” to the packet data and transmits packet data to which duplicate transmission flag “1” is assigned to base station apparatus 100-1 at wired data transmission section 306. The base station apparatus 100-1 receives the packet data to which the duplicate transmission flag “1” is assigned (step ST411). Further, the control station apparatus 300 transmits the packet data with the duplicate transmission flag “1” to the base station apparatus 100-2, and the base station apparatus 100-2 transmits the packet data with the duplicate transmission flag “1”. Receive (step ST412).

  Next, the base station apparatus 100-1 transmits the packet data with the duplicate transmission flag “1” to the communication terminal apparatus 200, and the communication terminal apparatus 200 transmits the packet data with the duplicate transmission flag “1”. Receive (step ST413).

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data in error correction decoding section 204, and ACK / NACK signal generation section 205 determines whether reception has succeeded or has failed. As a result of the determination, if the reception fails, the ACK / NACK signal generation unit 205 generates NACK information. Further, since the duplicate transmission flag extracted by the duplicate transmission flag extraction unit 208 is “1”, the TSN extraction unit 209 extracts the handover destination base station TSN generation unit 210 as the handover destination base station TSN. Set TSN to “0”. Communication terminal apparatus 200 transmits NACK information and handover destination base station TSN “0” to base station apparatus 100-2, and base station apparatus 100-2 transmits NACK information and handover destination base station TSN “0”. "Is received (step ST414). Further, communication terminal apparatus 200 transmits NACK information and handover destination base station TSN “0” to base station apparatus 100-1, and base station apparatus 100-1 transmits NACK information and handover destination base station TSN “0”. Is received (step ST415).

  Next, since the base station apparatus 100-1 has received the NACK information, the base station apparatus 100-1 is related to the NACK information stored in the storage unit 107 by instructing the retransmission control unit 105 to perform retransmission. The same packet data as the packet data is transmitted as retransmission data, and communication terminal apparatus 200 receives the packet data as retransmission data (step ST416). At this time, the duplicate transmission flag “1” is added to the packet data as in the first transmission. Further, since the base station apparatus 100-2 receives the NACK information and the handover destination base station TSN “0”, the packet data of the handover destination base station TSN “0” is stored in the storage unit 107. .

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data in error correction decoding section 204, and ACK / NACK signal generation section 205 determines whether reception has succeeded or has failed. As a result of the determination, if the reception is successful, the ACK / NACK signal generation unit 205 generates ACK information. Then, the handover destination base station TSN generation unit 210 generates the handover destination base station TSN because the duplicate transmission flag extracted by the duplicate transmission flag extraction unit 208 is “1”. At this time, the handover destination base station TSN generating unit 210 sets the handover destination base station TSN to “0” because the retransmission data is received this time.

  Next, communication terminal apparatus 200 transmits ACK information and handover destination base station TSN “0” to base station apparatus 100-2, and base station apparatus 100-2 transmits ACK information and handover destination base station TSN “0”. 0 "is received (step ST417). Further, communication terminal apparatus 200 transmits ACK information and handover destination base station TSN “0” to base station apparatus 100-1, and base station apparatus 100-1 transmits ACK information and handover destination base station TSN “0”. Is received (step ST418). Since the base station apparatus 100-2 receives the ACK information, the retransmission control unit 105 instructs the retransmission control unit 105 to discard the packet data of the TSN “0” for the handover destination base station stored in the storage unit 107. The packet data of the TSN “0” for the Hanodoba destination base station is discarded from the storage unit 107.

  Next, in the control station device 300, the wired data transmission destination base station determination unit 304 instructs the wired data transmission unit 306 to transmit data to the base station device 100-1 and the base station device 100-2. In addition, the duplicate transmission flag assigning unit 305 outputs the duplicate transmission flag “1”. Then, the control station apparatus 300 assigns the duplicate transmission flag “1” to the packet data to be transmitted next in the wired data transmission unit 306, and the packet data to which the duplicate transmission flag “1” is assigned is transmitted to the base station apparatus 100. -1 and the base station apparatus 100-1 receives the packet data to which the duplicate transmission flag “1” is assigned (step ST419). Further, the control station apparatus 300 transmits the packet data with the duplicate transmission flag “1” to the base station apparatus 100-2, and the base station apparatus 100-2 transmits the packet data with the duplicate transmission flag “1”. Receive (step ST420).

  Next, the base station apparatus 100-1 transmits the packet data with the duplicate transmission flag “1” to the communication terminal apparatus 200, and the communication terminal apparatus 200 transmits the packet data with the duplicate transmission flag “1”. Receive (step ST421).

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data in error correction decoding section 204, and ACK / NACK signal generation section 205 determines whether reception has succeeded or has failed. As a result of the determination, if the reception fails, the ACK / NACK signal generation unit 205 generates NACK information. Further, since the duplicate transmission flag extracted by the duplicate transmission flag extraction unit 208 is “1”, the TSN extraction unit 209 extracts the handover destination base station TSN generation unit 210 as the handover destination base station TSN. Set TSN to “1”. Communication terminal apparatus 200 transmits NACK information and handover destination base station TSN “1” to base station apparatus 100-2, and base station apparatus 100-2 transmits NACK information and handover destination base station TSN “0”. Is received (step ST422). Further, communication terminal apparatus 200 transmits NACK information and handover destination base station TSN “1” to base station apparatus 100-1, and base station apparatus 100-1 transmits NACK information and handover destination base station TSN “1”. "Is received (step ST423).

  Next, since base station apparatus 100-1 has received NACK information, retransmission control section 105 instructs retransmission. Further, since the base station apparatus 100-2 receives the NACK information, the base station apparatus 100-2 keeps the same packet data as the retransmitted packet data in the storage unit 107. In step ST419, the packet data is transmitted from the control station apparatus 300 after the processing of step ST412 to step ST418 is completed. However, the present invention is not limited to this, and the packet data in step ST419 is immediately after step ST411. 100-1 may be sent.

  Next, when the communication terminal apparatus 200 is handed over from the base station apparatus 100-1 to the base station apparatus 100-2 while repeating the processing of step ST421 to step ST423, the control station apparatus 300 A link release request is transmitted to base station apparatus 100-1, and base station apparatus 100-1 receives the radio link release request (step ST424).

  Next, control station apparatus 300 transmits a radio link establishment request to base station apparatus 100-2, and base station apparatus 100-2 receives the radio link establishment request (step ST425).

  Next, control station apparatus 300 transmits a physical channel setting request to communication terminal apparatus 200 via base station apparatus 100-1, and communication terminal apparatus 200 receives the physical channel setting request (step ST426). . Thereby, base station apparatus 100-1 stops transmission of packet data, base station apparatus 100-2 starts transmission of packet data, and communication terminal apparatus 200 transmits a packet after establishing synchronization with base station apparatus 100-2. Start receiving data. Thereby, the handover of the communication terminal apparatus 200 from the base station apparatus 100-1 to the base station apparatus 100-2 is completed.

  Next, communication terminal apparatus 200 transmits a physical channel setting notification to control station apparatus 300 via base station apparatus 100-2 to notify that the physical channel has been set (step ST427). .

  FIG. 5A is a diagram illustrating a queue structure in the storage unit 107 of the base station apparatus 100-1 when the processing up to step ST427 is completed, and FIG. 5B is the processing up to step ST427 completed. It is a figure which shows the relationship between the packet data stored in the storage part 107 of the base station apparatus 100-2 in the case of having performed, a duplication transmission flag, normal TSN, and TSN for handover destination base stations.

  5A, the storage unit 107 of the base station apparatus 100-1 includes queues # 501 to # 503 of communication terminal apparatuses that do not perform handover and queue # 504 of communication terminal apparatuses that perform handover. The queue # 504 includes a packet data arriving before the handover decision, that is, a part # 505 storing packet data not transmitted to the base station device 100-2 and a packet data arriving after the handover decision, ie, the base station device. It is composed of a part # 506 in which packet data transmitted to 100-2 is stored.

  In FIG. 5B, packet data # 510 and # 511 are packet data to which the duplicate transmission flag “0” is assigned, and packet data # 512 to # 516 have the duplicate transmission flag “1”. Packet data that has been assigned. Packet data # 510 and packet data # 511 in FIG. 5B are stored in a portion # 505 in which packet data not transmitted to the base station apparatus 100-2 in FIG. 5A is stored. The packet data # 512 to # 516 in FIG. 5B are stored in the portion # 506 in which the packet data transmitted to the base station apparatus 100-2 in FIG. Also, normal TSNs “29” to “35” are set in the packet data # 510 to # 516 transmitted from the base station apparatus 100-1. In addition, the handover destination base station TSN generated by the handover destination base station TSN generation unit 210 of the communication terminal apparatus 200 is given the duplicate transmission flag “0” for the packet data # 510 and # 511. So not generated. On the other hand, since the duplicate transmission flag “1” is assigned to the packet data # 512 to # 516, the handover destination base station TSNs “0” to “35” are used instead of the normal TSNs “31” to “35”. 4 "are sequentially generated. Thereby, the handover destination base station apparatus 102-2 can store the same packet data in the same order as the handover source base station apparatus 102-1 before the handover.

  FIG. 6 is a diagram illustrating a queue management operation of the storage unit 107 of the handover destination base station apparatus 100-2.

  When it is determined that the handover is to be performed, first, the storage unit 107 sequentially outputs the packet data to which the handover destination base station TSN numbered sequentially from the handover destination base station TSN “0” is assigned. (FIG. 6A). Next, when receiving ACK information for the handover destination base station TSN “0”, the base station device 100-2 includes the handover destination base station TSN among the packet data stored in the storage unit 107. The packet data to which “0” is assigned is discarded, and after discarding, the packet data is packed in the head direction (downward in FIG. 6) (FIG. 6B). Next, when receiving NACK information for the TSN “1” for the handover destination base station, the base station device 100-2 discards the packet data to which the TSN “1” for the handover destination base station is attached. Instead, it is stored as it is in the storage unit 107 (FIG. 6C). Next, when the base station apparatus 100-2 receives the ACK information for the handover destination base station TSN “2”, the handover destination base station TSN among the packet data stored in the storage unit 107 is received. The packet data to which “2” is assigned is discarded, and after discarding, the packet data is packed in the head direction (FIG. 6D). Thereby, the packet data stored in the storage unit 107 is in a state in which the packet data to which the handover destination base station TSNs “1”, “3”, and “4” are assigned are sequentially stored from the top.

  When the packet data stored in the storage unit 107 of the base station apparatus 100-2 is in the state of FIG. 6D, the handover of the communication terminal apparatus 200 from the base station apparatus 100-1 to the base station apparatus 100-2 Is completed, the base station apparatus 100-2 transmits the packet data to which the handover destination base station TSN “1” is assigned to the communication terminal apparatus 200 as retransmission data, and the communication terminal apparatus 200 Packet data to which the base station TSN “1” is assigned is received (step ST428).

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data at error correction decoding section 204, determines whether reception is successful or reception failure at ACK / NACK signal generation section 205, and responds to the determination result. ACK information or NACK information is transmitted to base station apparatus 100-2 (step ST429). And the process of step ST428 and step ST429 is repeated until reception success is detected.

  Next, in the control station device 300, the wired data transmission destination base station determination unit 304 notifies the wired data transmission unit 306 of the base station device 100-2 as a transmission data destination, and a duplicate transmission flag assignment unit. 305 outputs a duplicate transmission flag “0”. Then, the control station apparatus 300 assigns the duplicate transmission flag “0” to the packet data to be transmitted next in the wired data transmission unit 306, and the packet data to which the duplicate transmission flag “0” is assigned is transmitted to the base station apparatus 100. The base station apparatus 100-2 receives the packet data to which the duplicate transmission flag “0” is added (step ST430).

  Next, the base station apparatus 100-2 transmits the packet data to which the duplicate transmission flag “0” is assigned to the communication terminal apparatus 200, and the communication terminal apparatus 200 receives the packet data to which the duplicate transmission flag “0” is assigned. Receive (step ST431).

  Next, communication terminal apparatus 200 performs error correction decoding on the received packet data in error correction decoding section 204, and ACK / NACK signal generation section 205 determines whether reception has succeeded or has failed. As a result of the determination, if reception fails, ACK / NACK signal generation unit 205 generates NACK information, communication terminal apparatus 200 transmits NACK information to base station apparatus 100-2, and base station apparatus 100-2 transmits NACK information. Is received (step ST432). At this time, since the duplicate transmission flag extracted by the duplicate transmission flag extraction unit 208 is “0”, the handover destination base station TSN generation unit 210 does not generate the handover destination base station device TSN.

  Next, in the base station apparatus 100-2, the transmission priority control unit 106 performs scheduling for retransmitting packet data of NACK information. Then, base station apparatus 100-2 transmits the packet data stored in storage section 107 as retransmission data, and communication terminal apparatus 200 receives the packet data as retransmission data (step ST433). At this time, the same duplicate transmission flag “0” as that at the first transmission is assigned to the packet data as the retransmission data. Thereafter, the processes in steps ST431 to ST433 are repeated until no NACK information is generated.

  Thus, according to the first embodiment, the communication terminal apparatus gives the TSN for the handover destination base station and notifies the handover destination base station apparatus. Therefore, in the handover destination base station apparatus, before the handover, Queue management synchronized with the handover source base station apparatus can be performed. Further, according to the first embodiment, queue management synchronized between the handover source base station apparatus and the handover destination base station apparatus is performed before the handover, so that the queue can be taken over smoothly during the handover. Seamless handover without data loss can be performed.

(Embodiment 2)
FIG. 7 is a block diagram showing a configuration of communication terminal apparatus 700 according to Embodiment 2 of the present invention.

  As shown in FIG. 7, communication terminal apparatus 700 according to Embodiment 2 adds queue ID extraction section 701 to communication terminal apparatus 200 according to Embodiment 1 shown in FIG. In FIG. 7, parts having the same configuration as in FIG. Further, the configuration of the control station apparatus is the same as that in FIG. 1, and the configuration of the base station apparatus is the same as that in FIG.

  Error correction decoding section 204 performs error correction decoding on the received signal input from demodulation section 203 and outputs the received signal to ACK / NACK signal generation section 205, duplicate transmission flag extraction section 208, TSN extraction section 209 and queue ID extraction section 701.

  The queue ID extraction unit 701 extracts the queue ID (identifier) included in the packet data after error correction decoding input from the error correction decoding unit 204 and outputs the queue ID (identifier) to the error correction encoding unit 213. The queue ID is assigned to the packet data stored in the storage unit 107 by the transmission priority control unit 106 of the base station apparatus.

  The error correction coding unit 213 receives the ACK / NACK information input from the ACK / NACK signal generation unit 205, the duplicate transmission flag input from the duplicate transmission flag extraction unit 208, and the handover destination input from the TSN generation unit 210 for handover destination base station The packet data including the base station TSN, the queue ID input from the queue ID extraction unit 701 and the transmission data is subjected to error correction coding and output to the modulation unit 214. In addition, when the reception quality information is input from the reception quality information generation unit 212, the error correction encoding unit 213 performs error correction encoding on the input reception quality information and outputs it to the modulation unit 214.

  Next, the queue structure in the storage unit 107 of the base station apparatus will be described with reference to FIGS. 8 (a) to 8 (c). FIG. 8A is a diagram showing a queue structure. FIGS. 8B and 8C are diagrams showing packet data, a duplicate transmission flag, a normal TSN, a queue ID, and a handover in a handover destination base station apparatus. It is a figure which shows the relationship with the destination base station TSN.

  8A, the storage unit 107 of the base station apparatus 100-1 includes queues # 801 and # 802 of communication terminal apparatuses that do not perform handover and queues # 803 and # 804 of communication terminal apparatuses that perform handover. For each communication terminal device, two queues are managed for each QoS (Quality of Service), and queue # 803 and queue # 804 are queues for different QoS of the same user. Further, the queue ID “0” is assigned to the packet data stored in the queue # 803, and the queue ID “1” is assigned to the packet data stored in the queue # 804. The queue # 803 includes a part # 805 in which packet data arriving before the handover decision, that is, packet data not transmitted to the base station device 100-2 is stored, and a packet data arriving after the handover decision, that is, the base station device. It is composed of a part # 806 in which packet data transmitted to 100-2 is stored. The queue # 804 includes a packet data arriving before the handover decision, that is, a portion # 807 storing packet data not transmitted to the base station apparatus 100-2 and a packet data arriving after the handover decision, that is, the base data It consists of a portion # 808 in which packet data transmitted to the station device 100-2 is stored.

  In FIG. 8B, packet data # 810 and # 811 are packet data to which the duplicate transmission flag “0” is assigned, and packet data # 812 to # 816 are assigned to the duplicate transmission flag “1”. Packet data. The packet data # 810 and packet data # 811 in FIG. 8B are stored in the part # 805 in which packet data not transmitted to the base station apparatus 100-2 in FIG. 8A is stored. The packet data # 812 to # 816 in FIG. 8 (b) are stored in the part # 806 in which the packet data transmitted to the base station apparatus 100-2 in FIG. 8 (a) is stored. Also, normal TSNs “29” to “35” are set in the packet data # 810 to # 816 transmitted from the base station apparatus 100-1. In addition, the handover destination base station TSN generated by the handover destination base station TSN generation unit 210 of the communication terminal apparatus 200 is assigned the duplicate transmission flag “0” for the packet data # 810 and # 811. So not generated. On the other hand, since the duplicate transmission flag “1” is assigned to the packet data # 812 to # 816, the handover destination base station TSN “0” to “35” is used instead of the normal TSN “31” to “35”. 4 "are sequentially generated. Further, the queue ID “0” is assigned to the packet data # 810 to # 816.

  FIG. 8C is a diagram showing a relationship among packet data, a duplicate transmission flag, a normal TSN, a queue ID, and a handover destination base station TSN in queue # 804. In FIG. 8C, packet data # 820 and # 821 are packet data to which the duplicate transmission flag “0” is assigned, and packet data # 822 to # 826 are assigned to the duplicate transmission flag “1”. Packet data. Further, the packet data # 821 and the packet data # 822 in FIG. 8C are stored in the part # 807 in which packet data not transmitted to the base station apparatus 100-2 in FIG. 8A is stored. The packet data # 822 to # 826 in FIG. 8C is stored in the part # 808 where the packet data transmitted to the base station apparatus 100-2 in FIG. 8A is stored. Yes.

  Also, normal TSNs “12” to “18” are set in the packet data # 820 to # 826 transmitted from the base station apparatus 100-1. Further, the handover destination base station TSN generated by the handover destination base station TSN generation unit 210 of the communication terminal apparatus 200 is given the duplicate transmission flag “0” for the packet data # 820 and # 821. So not generated. On the other hand, since the duplicate transmission flag “1” is assigned to the packet data # 822 to # 826, the TSN “0” to “TSN for the handover destination base station is replaced with the normal TSN“ 14 ”to“ 18 ”. 4 "are sequentially generated. Further, the queue ID “1” is assigned to the packet data # 820 to # 826. Thus, when receiving packet data # 810- # 816, communication terminal apparatus 700 transfers queue ID “0” extracted by queue ID extraction section 701 to the handover destination base station apparatus, and packet When data # 821 to # 826 are received, the queue ID “1” extracted by the queue ID extraction unit 701 is transferred to the handover destination base station apparatus. The operations of the base station apparatus, communication terminal apparatus, and control station apparatus are the same as those shown in FIG. 4 except that the communication terminal apparatus transfers the queue ID transmitted from the handover source base station apparatus to the handover destination base station apparatus. Since the operation is the same, the description thereof is omitted.

  Thus, according to the second embodiment, in addition to the effects of the first embodiment, the ACK information or the NACK information, the handover destination base station TSN, and the queue ID are transmitted from the communication terminal apparatus to the handover destination base station. Since transmission is performed to the device, even when queue management is performed for each QoS, the handover destination base station device can perform queue management equivalent to that of the handover source base station device before the handover.

  The base station apparatus, communication terminal apparatus, control station apparatus, and queue management method according to the present invention are suitable for retransmitting packet data in which an error has occurred.

The block diagram which shows the structure of the base station apparatus which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the communication terminal device which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the control station apparatus which concerns on Embodiment 1 of this invention. Sequence diagram showing operations of base station apparatus, communication terminal apparatus, and control station apparatus according to Embodiment 1 of the present invention The figure which shows the queue structure which concerns on Embodiment 1 of this invention. The figure which shows the queue structure which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the communication terminal device which concerns on Embodiment 2 of this invention. The figure which shows the queue structure which concerns on Embodiment 2 of this invention. Diagram showing configuration of communication system The figure which shows the structure of the MAC-hs part of the conventional base station apparatus. Diagram showing cell configuration

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Base station apparatus 102 RF receiving part 103 Demodulation part 104 Error correction decoding part 105 Retransmission control part 106 Transmission priority control part 107 Storage part 108 TFRI selection part 109 Error correction encoding part 110, 112 Modulation part 111, 113 RF transmission part

Claims (6)

Storage means for storing the same packet data as the other station that is the handover source received from the higher-level station device;
Receiving means for receiving retransmission information which is information indicating successful reception or reception failure in the communication terminal device of the packet data transmitted from the other station before handover;
Retransmission control for discarding successfully received packet data stored in the storage means when receiving the retransmission information indicating successful reception in the receiving means among the packet data stored in the storage means Means,
Transmitting means for transmitting packet data remaining in the storage means without being discarded by the retransmission control means after the communication terminal apparatus has handed over from the other station to the own station;
A base station apparatus comprising: When the identification information, which is information for identifying packet data, is received together with the retransmission information indicating reception failure, the identification information is added to the packet data that has failed to be stored in the storage means of the local station. Comprising transmission priority control means;
The storage means stores the same packet data in the same order as the other stations before handover by storing the packet data given the identification information by the transmission priority control means. The base station apparatus according to claim 1. Receiving means for receiving packet data transmitted from the handover source base station apparatus, including a flag indicating that the packet data is stored in both the handover source base station apparatus and the handover destination base station apparatus; ,
Allocation information common to the handover source base station apparatus and the handover destination base station apparatus, which is information for identifying the packet data, is allocated to the packet data including the flag received by the reception unit. Identification information providing means;
An error detection means for detecting an error in the received packet data;
Transmission means for transmitting the information on the detection result of the error detected by the error detection means and the identification information assigned by the identification information giving means to the base station apparatus of the handover destination before handover;
A communication terminal apparatus comprising:   The transfer means for transferring, to the handover destination base station apparatus, an identifier different for each QoS assigned to the packet data received from the handover source base station apparatus by the receiving means. 3. The communication terminal device according to 3. Handover determining means for determining whether or not the communication terminal apparatus is handed over from a handover source base station apparatus to a handover destination base station apparatus based on information of a measurement result of reception quality in the communication terminal apparatus;
Flag giving means for giving packet data a flag indicating that it is packet data to be transmitted to the handover source base station apparatus and the handover destination base station apparatus when handover is decided by the handover decision means When,
Transmitting means for transmitting the packet data to which the flag is assigned by the flag grant means to the handover source base station apparatus and the handover destination base station apparatus;
A control station apparatus comprising: The handover source base station apparatus and the handover destination base station apparatus receive and store the same packet data from the host station apparatus before the handover;
The handover destination base station apparatus and the handover source base station apparatus receive retransmission information that is information indicating successful reception or reception failure in the communication terminal apparatus of the packet data transmitted from the handover source base station apparatus. Steps,
When receiving the retransmission information indicating successful reception, discarding the successfully received packet data stored in the handover source base station apparatus and the handover destination base station apparatus;
A queue management method comprising:

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