JP4718617B2 - Wireless communication system, wireless base station, and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication system, a wireless base station, and a wireless communication method using wireless communication.

3GPP (3rd
Generation Partnership Project (W-CDMA) Wideband Code Division Multiple
Access) system, HSDPA (High Speed Downlink Packet Access) system, and HSUPA (High Speed)
Uplink Packet Access) systems have been studied and specified (for example, Non-Patent Documents 1, 2, 3, and 4 below). In addition, E3G (Evolved
3G) Systems are also being studied. FIGS. 1 to 3 show configuration examples of a W-CDMA system, an HSDPA system, an HSUPA system (hereinafter, these systems are collectively referred to as “HSPA system”), and an E3G system, respectively.

  One of the features of the HSPA system is that the modulation method and the coding method are variable according to the radio wave condition. As a result, the speed of data communication can be increased.

  In addition, unlike the W-CDMA system, the HSPA system does not perform diversity handover in which handover is performed without disconnecting the connection between the base station and the terminal, and temporarily disconnects the connection with the handover source base station. Then, a hard handover (Hard Hand Over) is performed to reconnect to the handover destination base station.

  Next, a configuration example of the network side (infrastructure side) of the conventional W-CDMA system and HSPA system is shown in FIGS. 4 and 5 (for example, described in Non-Patent Documents 1 to 4 below), and the E3G system FIG. 6 shows a configuration example of FIG. 6, and FIG. 7 shows a configuration example of terminals in each system.

As shown in FIG. 4, in a W-CDMA system, a radio control station (RNC) 10 includes a PDCP (Packet Data Convergence Protocol) unit 12, an RLC (Radio Link Control) unit 13, and a MAC (Media
(Access Control) unit 14 and a radio network controller (RRC) 15. On the other hand, the radio base stations (NodeB) 20 and 30 include a signal processing (BB) unit 22. The PDCP unit 12, the RLC unit 13, and the MAC unit 14 generate individual packets and transfer them to the units 12 and the like. Generation of these packets and the like are controlled by the wireless line control unit 15.

  FIG. 5 shows the infrastructure side configuration in the HSPA system. Compared with FIG. 4, the radio base stations (NodeB) 20 and 30 include the MAC-hs / MAC-es unit 17, and a part of the functions of the radio control station 10 exists in the radio base stations 20 and 30. ing.

  Further, as shown in FIG. 6, the E3G system has a configuration in which an RLC unit 13, a MAC unit 14, and a radio channel control unit RRC unit 15 are provided on the radio base station (eNodeB) 51 and 52 side.

  As described above, the functions performed in the radio control station 10 of the host device in the W-CDMA system are gradually performed in the subordinate radio base stations 20, 30, 51, and 52 in the HSPA system and the E3G system. This speeds up communication by causing the packet creation to be performed on the side closer to the terminal 60.

  As shown in FIG. 7, the terminal 60 includes a PDCP unit 42 to a BB unit 48.

  FIG. 8 shows the HSUPA system, and FIG. 9 shows the HSDPA system. As shown in FIG. 8, in the HSUPA system, the data unit when output from the PDCP unit 42 in the terminal 60 to the RLC unit 43 is RLC SDU (PDCP PDU).

  The RLC unit 43 divides the RLC SDU into, for example, four RLC SDUs, adds a header to the divided RLC SDU, and outputs the RLC PDU to the MAC-es unit 46 inside the terminal 60 as an RLC PDU.

  The MAC-es unit 46 divides one RLC PDU into eight, for example, and outputs the divided RLC PDUs to the MAC-e unit 47 as MAC-es SDUs.

  The MAC-e unit 47 adds a header to the MAC-es SDU and outputs it to the signal processing unit 48 as a MAC-e PDU. The signal processing unit 48 encodes and modulates the MAC-e PDU as transmission data, and transmits the encoded data to the base stations (Node B) 20 and 30. At this time, HARQ (Hybrid Automatic Repeat Request) control is performed and transmitted to the base stations 20 and 30, and the transmission data is stored in a buffer. As described above, the terminal 60 creates four RLC PDUs from one RLC SDU and eight MAC PDUs from one RLC PDU (for example, Non-Patent Document 5 below).

  The base stations 20 and 30 create MAC-e PDUs from the received data, and transmit the MAC-e PDUs to the radio control station 10 that is a host device. In the radio control station 10, the MAC-es unit 16 transmits to the upper RLC unit 13 when eight MAC-es SDUs are prepared.

  The RLC unit 13 collects eight MAC-es SDUs to create one RLC PDU, and when four RLC PDUs are assembled, the four RLC PDUs are grouped to create one RLC SDU, and the upper PDCP unit 12 Send to.

  The radio control station 10 can reproduce the RLC SDU created by the terminal 60.

  FIG. 9 is an example of data flow and packet creation in the HSDPA system. One RLC SDU in the radio control station 10 is divided into four RLC PDUs as going down, and further one RLC PDU is divided into eight MAC-d PDUs. Then, the radio base stations 20 and 30 create a transmission packet and transmit it to the terminal 60. At this time, HARQ control is performed, and transmission data is stored in the buffers of the radio base stations 20 and 30.

  When the terminal 60 completes eight MAC-d PDUs, the terminal 60 outputs the MAC-d PDUs in a lower order, and creates an RLC PDU by combining them. Further, when four RLC PDUs are prepared, they are output to the lower order, and RLC SDUs are generated by combining them.

  FIG. 10 shows an uplink (uplink) data flow and packet creation example in the E3G system. Also in this case, as in FIG. 8, the RLC SDU generated by the terminal 60 is divided into four RLC PDUs and eight MAC PDUs toward the upper level, and the radio base stations (eNodeBs) 51 and 52 are transmitted as transmission packets. Sent to.

  In the radio base stations 51 and 52, when eight MAC PDUs are prepared, one RLC PDU is created, and when four RLC PDUs are prepared, it is transmitted to the upper apparatus (MME / UPE) 50. One RLC SDU is created from the RLC PDU. Packet integration and division are performed in substantially the same manner as in the example of FIG.

FIG. 11 illustrates a downlink (downlink) data flow and an example of packet creation in the E3G system. As in FIG. 9, packet integration and division are performed.
3GPPTS25.321 V5.12.0 3GPPTS25.321 V6.10.0 (especially the configuration of MAC-d, MAC-hs, MAC-e, MAC-es is shown in Fig.4.2.4.1 on page 19) 3GPPTS25.322 V5.13.0 3GPPTS25.322 V6.9.0 3GPPR3.018V0.6.0_6.8.4.3.2

  As described above, in the case of the HSPA system or the E3G system, an RLC PDU cannot be created unless eight MAC PDUs are prepared, and an RLC SDU is created unless four RLC PDUs are prepared. It is not possible.

  FIG. 12 is a diagram illustrating an example of processing in the MAC unit 44 of the terminal 60 or the MAC unit 14 of the radio base stations 51 and 52 in the E3G system. The number indicates the sequence number of the MAC PDU.

  Considering the uplink direction, MAC PDUs with sequence numbers “1” to “8” are transmitted to the upper RLC unit 13 because eight MAC PDUs are arranged. However, the sequence number “12” is being retransmitted by the retransmission control. In this case, if the “12” MAC PDU is not delivered even after a certain time has elapsed, this MAC PDU is discarded together with the MAC PDUs “9” to “16” already delivered, for example. FIG. 13 shows an example of processing in the RLC unit 43 of the terminal 60. When four RLC SDUs are prepared, it is transmitted to the host device 10.

Then, when the terminal 60 performs a handover in a state where the MAC PDU is not delivered, the handover target radio base station 52 transmits the MAC PDUs having sequence numbers “9” to “16” to the terminal 60 in order to prevent data loss. Have a new transmission. For example, when one MAC PDU is not delivered, 31 transmitted MAC PDUs may be retransmitted to the handover destination radio base station 52 (for example, all of the sequence numbers “9” to “40” are retransmitted). To do). In such a case, the handover source radio base station 51 cannot transfer the RLC SDU to the host device 10 or the handover destination base station 52 (see FIG. 14).
However, it is inefficient to retransmit the MAC PDU already delivered from the terminal 60 to the handover source radio base station 51 in this way from the terminal 60 to the handover destination radio base station 52. Transmission of duplicate MAC PDUs requires extra transmission time, resulting in a reduction in throughput.

  On the other hand, in the downlink direction, the MAC PDU being retransmitted remains in the handover source radio base station 51 due to the handover. The remaining data (hereinafter referred to as “residual data”) needs to be transferred to the handover destination radio base station 52, but the terminal 60 prevents the data loss of the MAC PDU being retransmitted to the handover destination radio base station 52. Request to send At this time, the handover destination radio base station 52 requests the host apparatus 10 for data in units of RLC SDUs including the MAC PDU being retransmitted, and the handover destination radio base station 52 transmits a MAC to the terminal 60. A PDU is transmitted.

  Therefore, in the downlink direction, the MAC PDU that has already been transmitted from the handover source radio base station 51 to the terminal 60 is transmitted from the handover destination radio base station 52 to the terminal 60. The transmission of the MAC PDU causes a decrease in throughput. Due to the decrease in throughput, for example, when moving images are transmitted in real time, the moving images are displayed on the terminal 60 side in a state of dropping frames, which also affects the service.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system, a wireless base station, and a wireless communication that improve throughput even when handover is performed during retransmission control. It is to provide a method.

  In order to achieve the above object, according to an embodiment of the present invention, when radio communication is performed between a first radio base station and a terminal, the first radio base station is replaced by handover. In a radio communication system in which radio communication is performed between a second radio base station and the terminal, data remaining in the first radio base station is transferred to the first radio base station in the second radio base station. When transferring to a base station, a dummy packet is created for an undelivered packet that has not been acknowledged among transmission packets transmitted from the terminal to the first radio base station, and the dummy packet is A data packet creation unit that creates a data packet including the data packet creation unit, and a transfer unit that forwards the created data packet to the handover destination radio base station, wherein the second radio base station includes the data packet A data packet receiving unit that receives a packet, and a request for transmitting the undelivered packet from the received data packet to the terminal, and an undelivered packet receiving unit that receives the undelivered packet from the terminal. It is characterized by that.

  In order to achieve the above object, according to another embodiment of the present invention, in a radio base station that performs radio communication with a terminal, when handover is performed by the terminal, the remaining data is transferred to the handover destination radio. Whether the packet transmitted from the terminal is a packet that has not been acknowledged for delivery or is not yet being transmitted, or has been acknowledged for delivery, when transferred to the base station A packet identification unit for identifying the packet, a data packet creation unit for creating a dummy packet for the packet identified by the packet identification unit as the undelivered packet, and creating a data packet including the dummy packet; And a transfer unit that transfers the received data packet to a handover destination radio base station.

    Furthermore, in order to achieve the above object, according to another embodiment of the present invention, when wireless communication is performed between the first radio base station and the terminal, the first radio base is performed by handover. In a radio communication method in a radio communication system in which radio communication is performed between a second radio base station and the terminal instead of a station, data remaining in the first radio base station in the first radio base station When a packet is transferred to the second radio base station, a dummy packet is created for an undelivered packet that has not been acknowledged among transmission packets transmitted from the terminal to the first radio base station. Then, a data packet including the dummy packet is created, the created data packet is transferred to the radio base station that is a handover destination, and the data packet is transmitted to the second radio base station. Receiving the door, requesting a transmission request of the undelivered from the data packet received packet to the terminal, the packet of the undelivered characterized in that it received from the terminal.

  According to the present invention, it is possible to provide a radio communication system, a radio base station, and a radio communication method capable of improving throughput even when handover is performed during retransmission control.

FIG. 1 is a diagram illustrating a configuration example of a W-CDMA system. FIG. 2 is a diagram illustrating a configuration example of the HSPA system. FIG. 3 is a diagram illustrating a configuration example of the E3G system. FIG. 4 is a diagram illustrating a configuration example of the infrastructure side of W-CDMA. FIG. 5 is a diagram illustrating a configuration example of the HSPA infrastructure side. FIG. 6 is a diagram illustrating a configuration example of the E3G infrastructure side. FIG. 7 is a diagram illustrating a configuration example of a terminal. FIG. 8 is a diagram showing a data flow and a packet creation example. FIG. 9 is a diagram showing a data flow and a packet creation example. FIG. 10 is a diagram showing a data flow and a packet creation example. FIG. 11 is a diagram showing a data flow and a packet creation example. FIG. 12 is a diagram illustrating an example of transmission to a higher level of a MAC PDU. FIG. 13 is a diagram illustrating an example of transmission of RLC PDU to the upper level. FIG. 14 is a diagram showing an example of RLC SDU transfer in the E3G system. FIG. 15 is a diagram showing an example of the data configuration. FIG. 16 is a diagram illustrating an example of a dummy MAC PDUI type. FIG. 17 is a diagram illustrating an example of a dummy MAC PDUII type. FIG. 18 is a diagram showing an example of a dummy MAC PDUIII type. FIG. 19 is a diagram illustrating an example of a dummy MAC PDUIV type. FIG. 20 is a diagram showing an example of a dummy MAC PDUV type. FIG. 21 is a diagram showing an example of a dummy MAC PDUVI type. FIG. 22 is a diagram showing an example of a dummy MAC PDUVII type. FIG. 23 is a diagram illustrating a configuration example of the E3G system. FIG. 24 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 25 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 26 is a diagram illustrating a configuration example of MME / UPE. FIG. 27 is a diagram illustrating a configuration example of a terminal. FIG. 28 is a diagram showing an example of a processing sequence. FIG. 29 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 30 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 31 is a diagram illustrating a configuration example of a terminal. FIG. 32 is a diagram illustrating an example of RLC PDU. FIG. 33 is a diagram showing an example of a processing sequence. FIG. 34 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 35 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 36 is a diagram illustrating an example of RLC PDU. FIG. 37 is a diagram showing an example of a processing sequence. FIG. 38 is a diagram illustrating an example of a dummy MAC PDU. FIG. 39 is a diagram illustrating an example of a dummy MAC PDU. FIG. 40 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 41 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 42 is a diagram illustrating a configuration example of a terminal. FIG. 43 is a diagram showing an example of a processing sequence. FIG. 44 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 45 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 46 is a diagram illustrating an example of RLC PDU. FIG. 47 is a diagram showing an example of a processing sequence. FIG. 48 is a diagram illustrating an example of RLC PDU. FIG. 49 is a diagram illustrating a configuration example of a transfer source radio base station. FIG. 50 is a diagram illustrating a configuration example of a transfer destination radio base station. FIG. 51 is a diagram showing an example of a processing sequence. FIG. 52 is a diagram illustrating an example of RLC PDU. FIG. 53 is a diagram illustrating an example of RLC PDU. FIG. 54 is a diagram illustrating an example of RLC PDU. FIG. 55 is a diagram illustrating an example of RLC PDU. FIG. 56 is a diagram illustrating a configuration example of a terminal.

Explanation of symbols

11: MME / UPE 21: Transfer source radio base station (eNodeB)
31: Transfer destination radio base station (eNodeB) 40: Terminal 214: Error confirmation unit 218: Retransmission control unit 219: Temporary storage unit 221: Transfer packet creation unit 222: Transfer control unit 223: Dummy packet creation unit 224: Dummy packet information Creation unit 225: Transfer packet information creation unit 250: HARQ temporary storage unit 251: HARQ control unit 260: Dummy MAC PDU information creation unit 261: Dummy MAC PDU creation unit 262: Dummy RLC PDU information creation unit 263: Dummy RLC PDU creation unit 264: Transfer RLC SDU information creation unit 265: Transfer RLC SDU creation unit 270: ACK / NACK extraction unit 272: HARQ control unit 275: Dummy MAC PDU creation unit 277: Transfer RLC PDU creation unit 278: Transfer RLC PDU information creation unit 279 : Transfer RLC S U creation unit 280: transfer RLC SDU information creation unit 314: error confirmation unit 318: retransmission control unit 319: temporary storage unit 322: dummy packet identification unit 323: dummy packet identification information extraction unit 350: HARQ control unit 351: HARQ temporary storage Unit 352: RLC SDU identification unit 353: transfer RLC SDU identification information extraction unit 354: RLC PDU identification unit 355: transfer RLC PDU identification information extraction unit 356: MAC PDU identification unit 357: dummy MAC PDU identification information extraction unit 370: ACK / NACK extraction unit 371: retransmission control unit 377: temporary storage unit 382: dummy packet identification unit 383: dummy packet identification information extraction unit 390: HARQ control unit 391: HARQ temporary storage unit 392: RLC SDU identification unit 393: transfer RLC SDU identification Information extraction unit 394: LC PDU identification unit 395: Forwarding RLC PDU identification information extraction unit 396: MAC PDU identification unit 397: Dummy MAC PDU identification information extraction unit 413: ACK / NACK extraction unit 414: Retransmission control unit 420: HARQ control unit 427: HARQ temporary storage Unit 433: Temporary storage unit 434: Retransmission control unit 440: HARQ temporary storage unit 441: HARQ control unit

  The best mode for carrying out the present invention will be described below.

  First, Example 1 will be described. In the first embodiment, an example in the uplink direction (from the terminal to the radio base station) will be described.

  FIG. 15 shows an example of the data structure of RLC SDU, RLC PDU, and MAC PDU. As shown in FIG. 15, consider the following example. That is, among the MAC PDUs included in the RLC PDU sequence number “7”, sequence numbers “9” to “11” have been delivered from the terminal to the radio base station. The MAC PDU with the sequence number “12” is being retransmitted by retransmission control. In addition, it is assumed that the MAC PDU having the sequence number “13” has been delivered and that “14” and later are not received (the terminal does not output the MAC PDU to the radio base station). For this reason, the RLC PDU with the sequence number “7” cannot be transmitted to the upper layer, and the RLC SDU with the sequence number “21” cannot be transmitted (or cannot be transferred). RLC SDUs that remain without being transmitted and MAC PDUs included in the RLC SDUs are referred to as residual data.

  Consider a case where the terminal performs handover in such a state. The handover source radio base station needs to transmit data (residual data) to the handover destination radio base station in order to prevent data loss. Conventionally, when one MAC PDU is being retransmitted, the RLC SDU cannot be configured, and the terminal 40 newly transmits an RLC SDU including the MAC PDU being retransmitted to the handover destination radio base station.

  In this embodiment, as shown in FIG. 16, data including errors contained in the MAC PDU being retransmitted is discarded, and a dummy MAC PDU is configured with specific pattern data (for example, all “0”, etc.) Transfer from the handover source radio base station to the handover destination radio base station. As a result, the handover destination radio base station requests data transmission from the terminal 40 only for the dummy MAC PDU, so that the data is transmitted, so that no duplicate MAC PDU is transmitted. Therefore, throughput can be improved.

  When transferring a dummy MAC PDU with a specific pattern, it is necessary to recognize in advance by data transmission / reception or the like that the data with the specific pattern is a dummy MAC PDU between the handover source and the handover destination.

  FIG. 17 shows an example in which a MAC PDU being retransmitted is not a specific pattern, and data being retransmitted that contains an error is used as it is as a dummy MAC PDU. In this case, in order to identify the handover target radio base station as a dummy MAC PDU, the RLC PDU (or RLC SDU) including the dummy MAC PDU is notified. For example, information may be inserted into a header when transmitting, or may be separately transmitted with a control signal.

  FIG. 18 shows an example in which a dummy MAC PDU with a specific code is configured for an unreceived MAC PDU, not a retransmitting MAC PDU. This is because by creating a dummy MAC PDU for an unreceived MAC PDU, an RLC SDU can be constructed and transferred to the handover destination radio base station. Also in this case, the radio base station is notified in advance that the specific pattern is a dummy MAC PDU.

  For ease of explanation, FIG. 16 is referred to as a dummy MAC PDU type, FIG. 17 as a dummy MAC PDU II type, and FIG. 18 as a dummy MAC PDU III type. In addition to the present embodiment, the transfer unit from the handover source to the handover destination radio base station is mainly described as an RLC SDU unit in all the following embodiments. However, the same can be applied to an RLC PDU unit as well. Has the effect of.

  Note that FIGS. 18 to 20 showing the dummy MAC PDU in the downlink direction will be described in the fourth and subsequent embodiments.

  Next, the configuration and operation in the first embodiment will be described. FIG. 23 shows a system configuration example of the E3G system, FIG. 24 shows a transfer source (handover source) radio base station, FIG. 25 shows a transfer destination (handover destination) radio base station, FIG. 26 shows an MME / UPE that is a host device, and FIG. Reference numeral 27 denotes a configuration example of the terminal.

  As shown in FIG. 23, the E3G system includes an MME / UPE 11, a handover source transfer source radio base station (eNode_B) 21, a handover destination transfer destination radio base station (eNode_B) 31, and a terminal (UE) 40. Composed. The internal configuration of the MME / UPE 11 or the like indicates functional blocks, and the description of each block is omitted because it has been described in the related art.

  FIG. 24 is a diagram illustrating a specific configuration example of the transfer source radio base station 21. As shown in the figure, the transfer source radio base station 21 includes a reception radio unit 211, a demodulation unit 212, a decoding unit 213, an error confirmation unit 214, a received electric field strength information extraction unit 215, and a handover control unit 216. A retransmission control unit 218, a temporary storage unit 219, a packet creation unit 220, a transfer packet creation unit 221, a transfer control unit 222, a dummy packet creation unit 223, a dummy packet information creation unit 224, and a transfer packet An information creation unit 225, an ACK / NACK creation unit 226, a scheduler unit 228, an uplink transmission control information creation unit 229, an encoding unit 230, a modulation unit 231, and a transmission radio unit 232 are provided.

  FIG. 25 is a diagram illustrating a specific configuration example of the transfer destination radio base station 31. As shown in the figure, the transfer destination radio base station 31 includes a reception radio unit 311, a demodulation unit 312, a decoding unit 313, an error confirmation unit 314, a handover control unit 316, a retransmission control unit 318, Storage unit 319, transfer control unit 320, transfer packet reception unit 321, dummy packet identification unit 322, dummy packet identification information extraction unit 323, transfer packet creation unit 324, ACK / NACK creation unit 326, scheduler Unit 328, uplink transmission control information creation unit 329, encoding unit 330, modulation unit 331, and transmission radio unit 332.

  FIG. 26 is a diagram illustrating a specific configuration example of the MME / UPE 11 that is the host device. As shown in the figure, the MME / UPE 11 includes a PDCP unit 12, and the PDDCP unit 12 includes a ROHC (Robust Header Compression) unit 121, an encryption unit 122, and a PDCP PDU creation unit 123. The MME / UPE 11 is a device that performs routing after forming a data unit including a predetermined number of data blocks.

  FIG. 27 is a diagram illustrating a specific configuration example of the terminal 40. As shown in the figure, the terminal 40 includes a transfer packet reception unit 401, a transmission packet creation unit 402, an encoding unit 403, a modulation unit 404, a transmission radio unit 405, a reception electric field strength measurement unit 406, A reception field strength information creation unit 408, a reception radio unit 409, a demodulation unit 410, a decoding unit 411, an uplink transmission control information extraction unit 412, an ACK / NACK extraction unit 413, and a retransmission control unit 414 are provided.

  Each part 11 of the E3G system configured as described above operates as follows. That is, the transfer packet reception unit 401 of the terminal 40 receives, for example, image data captured by the camera of the terminal 40, and the transmission packet creation unit 402 creates a transmission packet from the received image data. The transmission packet is encoded and modulated by the encoding unit 403 and the modulation unit 404, converted to a predetermined frequency by the transmission radio unit 405, and transmitted to the transfer source radio base station 21 via the antenna.

  The transmission packet transmitted from the terminal 40 is received by the reception radio unit 211 of the transfer source radio base station 21, demodulated and decoded via the demodulation unit 212 and the decoding unit 213, and output to the error confirmation unit 214. The error confirmation unit 214 determines whether or not there is an error in the data for the decoded transmission packet based on the CRC code, outputs the determination result to the retransmission control unit 218, and transmits the transmission packet from the decoding unit 213. Data is temporarily stored in the temporary storage unit 219.

  On the other hand, the reception field strength measurement unit 406 of the terminal 40 measures the reception field strength from the radio base stations 21 and 31, and the reception field strength information creation unit 408 creates reception field strength information. The information is transmitted from the terminal 40 to the transfer source radio base station 21 via the encoding unit 403, the modulation unit 404, and the transmission radio unit 405.

  The reception field strength information is output to the reception field strength information extraction unit 215 via the reception radio unit 211, the demodulation unit 212, and the decoding unit 213. Then, the handover control unit 216 determines the handover of the terminal 40 from the received electric field strength information. When the handover control unit 216 determines that the handover of the terminal 40 has been executed, the handover control unit 216 outputs a control signal to each unit as shown by a two-dot chain line in FIG. Each part operates.

  When the control signal indicating that the handover is performed by the handover control unit 216 is input to the retransmission control unit 218 of the transfer source radio base station 21, the transmission packet decoded from the decoding unit 213 is a packet that is being retransmitted. It is determined whether the packet has not been received or has been delivered.

  The determination is performed as follows. That is, when a signal indicating “no error” is input from the error checking unit 214, the retransmission control unit 218 determines that the transmission packet is a “delivered” packet, and a signal indicating “with error” is input. At this time, it is determined that the transmission packet is a packet being “retransmitted”, and when both signals indicating “error” and “no error” are not input, the transmission packet is determined to be an “unreceived” packet.

  When the retransmission control unit 218 determines that the transmission packet is a “delivered” packet, the retransmission control unit 218 outputs a control signal instructing packet creation to the packet creation unit 220, and the packet creation unit 220 transmits the packet from the temporary storage unit 219 based on the control signal. Data included in the packet is read to create a packet and output it to the transfer packet creation unit 221.

  In the temporary storage unit 219, the transmission packet order is stored so as to be rearranged in the transmission order, or is read out by the dummy packet creation unit 223 so as to be in the transmission order.

  The transfer packet creation unit 221 creates a transfer packet by, for example, integrating a plurality of packets, and outputs the transfer packet to the transfer control unit 222. The transfer control unit 222 transfers the transfer packet to the transfer destination radio base station 31.

  On the other hand, when the retransmission control unit 218 determines that the transmission packet is a “retransmitting” packet, the retransmission control unit 218 instructs the dummy packet generating unit 223 to create a dummy packet indicating “retransmitting” and For packets, the packet creation unit 220 is instructed to create packets. Furthermore, the retransmission control unit 218 also instructs the dummy packet information creation unit 224 to create a “during retransmission” dummy packet. Based on this instruction, the dummy packet creation unit 223 reads data of a specific pattern (for example, all “0”, etc.) from the dummy packet information creation unit 224 and creates a dummy packet. Alternatively, the dummy packet creation unit 223 reads data including an error during retransmission from the temporary storage unit 219 and creates a dummy packet.

  The transfer packet creation unit 221 creates a transfer packet by integrating a plurality of created dummy packets and packets from the packet creation unit 220 together.

  On the other hand, the dummy packet information creation unit 224 creates dummy packet information indicating that the packet is a “during retransmission” dummy packet or the sequence number of the dummy packet, and outputs the dummy packet information to the transfer packet information creation unit 225. The transfer packet information creation unit 225 creates transfer packet information from the dummy packet information. The transfer packet information includes information indicating that the packet is a “during retransmission” dummy packet, dummy packet information indicating a dummy packet sequence number, a dummy bit pattern included in the dummy packet, a dummy bit length, and the like.

  The forwarding packet creation unit 221 reads forwarding packet information from the forwarding packet information creation unit 225 and adds it as dummy packet identification information to the header of the forwarding packet to create a forwarding packet. Then, the transfer packet is transferred from the transfer control unit 222 to the transfer destination radio base station 31.

  The dummy packet identification information may be transferred from the transfer packet information creation unit 225 to the transfer destination radio base station 31 as a separate control signal.

  When the retransmission control unit 218 determines that the transmission packet is an “unreceived” packet, the retransmission control unit 218 instructs the dummy packet creation unit 223 to create a dummy packet and sends the packet creation unit 220 to the packet creation unit 220 in substantially the same way as “during retransmission”. Packet creation is instructed for other transmission packets. Further, the retransmission control unit 218 instructs the dummy packet information creation unit 224 to create a “unreceived” dummy packet.

  The dummy packet creation unit 223 reads data of a specific pattern from the dummy packet information creation unit 224 and creates a dummy packet. The created dummy packet and a plurality of packets created by the packet creation unit 220 are integrated into a transfer packet by the transfer packet creation unit 221 and transferred to the transfer destination radio base station 31 from the transfer control unit 222.

  At this time, the transfer packet creation unit 221 adds dummy packet identification information indicating that the transfer packet includes a “unreceived” dummy packet from the transfer packet information creation unit 225 to the header, or It is transferred from the transfer packet information creation unit 225 to the transfer destination radio base station 31 as a control signal.

  The retransmission control unit 218 instructs the ACK / NACK creation unit 226 to create “NACK” when there is “error” from the signal indicating that there is no error from the error confirmation unit 214. In the case of “no error”, an instruction is given to create “ACK”. The ACK / NACK creation unit 226 outputs the created signal indicating “NACK” or “ACK” to the encoding unit 230, is encoded, and is transmitted to the terminal 40 via the modulation unit 231 and the transmission radio unit 232. The

  Further, the scheduler unit 228 receives information (for example, CQI) indicating the radio channel quality from the terminal 40, determines “which terminal transmits the packet” based on the information, and performs transmission control on the terminal 40. It instructs the uplink transmission control information creation unit 229 to create information. The uplink transmission control information creation unit 229 creates uplink transmission control information indicating a modulation method, an encoding method, and the like for the determined terminal 40. The created uplink transmission control information is transmitted to the terminal 40 via the encoding unit 230 and the like, and based on this control information, the terminal 40 transmits the transmission packet to the transfer source radio base station 21 as described above. .

  The handover destination radio base station (transfer destination radio base station) 31 receives the transfer packet transferred from the transfer source radio base station 21. The transfer packet is transferred to the transfer control unit 320, temporarily held by the transfer packet receiving unit 321, and divided from the transfer packet to the packet.

  Further, the transfer packet receiving unit 321 outputs the dummy packet identification information added to the header of the transfer packet or the packet identification information transferred as a control signal to the dummy packet identification information extraction unit 323.

  The dummy packet identification information extraction unit 323 extracts a dummy packet pattern from the dummy packet identification information. For example, all dummy packets are “0”, and all unreceived dummy packets are “0”. The dummy packet identification information extraction unit 323 extracts dummy packet identification information indicating whether the packet is a “retransmitting” packet, a “unreceived” packet, or a “delivered” packet, and transmits the information to the retransmission control unit 318. Output to.

  The dummy packet identifying unit 322 determines whether the dummy packet is a dummy packet having a specific pattern (for example, type I shown in FIG. 16 or type III shown in FIG. 18) from the dummy pattern extracted by the dummy packet identification information extracting unit 323, or retransmission. It is identified whether it is a dummy packet of medium data (for example, type II in FIG. 17) or a delivered packet. The identification result is output to retransmission control section 318.

  In the case of a dummy packet with a specific pattern, the retransmission control unit 318 discards the packet. In the case of a dummy packet of retransmission data or a “delivered” packet, the retransmission control unit 318 outputs the packet to the temporary storage unit 319 and temporarily stores it.

  The retransmission control unit 318 operates as follows based on the dummy packet identification information from the dummy packet identification information extraction unit 323. That is, when the dummy packet is “resending”, the scheduler unit 328 is instructed to request the terminal 40 to newly transmit the packet. At this time, it is instructed to transmit the sequence number of the “during retransmission” dummy packet (sequence number “12” in the above example).

  The scheduler unit 328 instructs the uplink transmission control information creation unit 329 to create transmission control information of the terminal 40, assuming that the terminal 40 has been selected. The uplink transmission control information creation unit 329 creates transmission control information indicating the encoding of the terminal 40 and transmits the transmission control information to the terminal 40 via the encoding unit 330, the modulation unit 321, and the transmission radio unit 332.

  In the terminal 40, the transmission packet receiving unit 401 receives the transmission control information, and the transmission packet creating unit 402 creates a transmission packet under the control of the retransmission control unit 414. The created transmission packet is transmitted to the transfer destination radio base station 31 via the encoding unit 403 and the like.

  The transmission packet is transferred to the error confirmation unit 314 via the reception radio unit 311 of the transfer destination radio base station 31 or the like. An error is confirmed by the error confirmation unit 314, and if there is an error in the transmitted transmission packet, a “NACK” signal is created under the control of the retransmission control unit 318, transmitted to the terminal 40 and retransmitted.

  In the temporary storage unit 319, when the dummy packet is a dummy packet due to data being retransmitted, the data being retransmitted is stored in the temporary storage unit 319 as it is, so this is combined with the data of the newly transmitted or retransmitted transmission packet. Then, the error confirmation unit 314 confirms, and if there is no error, the transmission packet is output to the transfer packet creation unit 324. The transfer packet creation unit 324 creates a transfer packet from the transmission packet, and transfers the transfer packet from the transfer control unit 320 to the MME / UPE 11 that is the host device.

  When the dummy packet is a dummy packet according to a specific pattern, it is discarded, so that a newly transmitted transmission packet is stored in the temporary storage unit 319 and is transferred as a transfer packet via the transfer packet creation unit 324 and the transfer control unit 320. Transferred to MME / UPE11.

  When the packet is “not received”, the retransmission control unit 318 requests the terminal unit 40 to newly transmit a packet corresponding to “not received” to the scheduler unit 328, as in the case of “resending”. Instruct as much as possible. A transmission packet corresponding to “not received” is transmitted from the terminal 40, and the transmission packet is transferred to the MME / UPE 11 as a transfer packet via the temporary storage unit 319, the transfer packet creation unit 324, and the like.

  When the packet is “delivered”, the transfer packet creation unit 324 reads the packet data stored in the temporary storage unit 319 to create a transfer packet, and transfers the packet to the MME / UPE 11 via the transfer control unit 320. .

  FIG. 28 is a diagram illustrating a sequence example of upstream processing according to the first embodiment. This is a summary of the above-described processing, and there are portions that are redundantly described.

  First, when the handover of the terminal 40 is detected (S10), the transfer source radio base station (BTS1) 21 detects a packet transmitted from the terminal 40 (S11). That is, the transfer source radio base station 21 detects whether the packet is a “retransmitting” packet, a “unreceived” (or “untransmitted”) packet, or a “delivered” packet.

  Then, the transfer source wireless base station 21 creates a transfer packet from the “delivered” packet for the “delivered” packet (S12), and a dummy packet (for example, for the “retransmitting” packet). 16 and FIG. 17) (S13), dummy packets (for example, the packets shown in FIG. 18) are also created for “unreceived” packets (S14), and the dummy packets and the like are collected. By doing so, a transfer packet is created (S15).

  Thereafter, when the handover is actually executed (S16), dummy packet identification information (indicating whether it is a “delivered” packet, a “retransmitting” packet, or an “unreceived” packet) indicating the type of the dummy packet is displayed. The transfer packet information including it is notified (S17). Then, the transfer packet is transferred to the transfer destination radio base station 31 (S18). The transfer packet information may be added to the transfer packet and transferred at the same time, or may be transferred separately as shown in FIG.

  The transfer destination radio base station (BTS2) 31 confirms a packet to be retransmitted (S19), and outputs a transmission request for a packet being “retransmitted” or “not received” to the terminal (UE1) 40 (S20). The terminal 40 confirms the transmission target packet (S21) and transmits the target packet (S22).

  Next, Example 2 will be described. In the second embodiment, the packet is specifically an MAC PDU, RLC PDU, or RLC SDU. In addition, the dummy packet is an example of a dummy MAC PDU type for “retransmitting” MAC PDU packets and a dummy MAC PDU III type for “unreceived” MAC PDUs.

  29 is a configuration example of the transfer source radio base station 21 in the second embodiment, FIG. 30 is a configuration example of the transfer destination radio base station 31, FIG. 31 is a configuration example of a terminal, and FIG. 32 is an RLC PDU including a dummy MAC PDU. FIG. 33 is a diagram showing a configuration example, and FIG. 33 shows an example of a processing sequence.

  As shown in FIG. 29, the transfer source radio base station 21 in the second embodiment has a MAC PDU, an RLC PDU, and an RLC SDU compared to the transfer source radio base station 21 (FIG. 24) in the first embodiment. Specifically configured to create.

  That is, the transfer source radio base station 21 newly adds a HARQ temporary storage unit 250, a HARQ control unit 251, a MAC PDU information creation unit 252, a MAC PDU creation unit 253, an RLC PDU information creation unit 254, and an RLC. PDU creation unit 255, transmission RLC SDU information creation unit 256, transmission RLC SDU creation unit 257, dummy MAC PDU information creation unit 260, dummy MAC PDU creation unit 261, dummy RLC PDU information creation unit 262, dummy An RLC PDU creation unit 263, a transfer RLC SDU information creation unit 264, a transfer RLC SDU creation unit 265, an ARQ temporary storage unit 266, and an ARQ control unit 267 are provided.

  Also, as shown in FIG. 30, in the transfer destination radio base station 31, a HARQ control unit 350, a HARQ temporary storage unit 351, an RLC SDU identification unit 352, and a transfer RLC SDU identification information extraction unit 353 are newly added. RLC PDU identification unit 354, transfer RLC PDU identification information extraction unit 355, MAC PDU identification unit 356, dummy MAC PDU identification information extraction unit 357, MAC PDU creation unit 358, ARQ control unit 359, ARQ temporary A storage unit 360, an RLC PDU creation unit 361, and an RLC SDU creation unit 362 are provided.

  Furthermore, as shown in FIG. 31, also in terminal 40, HARQ control section 420, ARQ ACK / NACK extraction section 421, ARQ control section 422, RLC SDU (PDCP PDU) reception section 423, RLC The PDU creation unit 424, the ARQ temporary storage unit 425, the MAC PDU creation unit 426, the HARQ temporary storage unit 427, and the transmission packet creation unit 428 are provided.

  Each unit 11 and the like in the E3G system configured as described above operates as follows. That is, the transmission packet creation unit 428 of the terminal 40 creates a transmission packet and transmits it to the transfer source radio base station 21 via the encoding unit 403 and the like. This transmission packet is transmitted in units of MAC PDUs.

  The transfer source radio base station 21 transmits the transmitted MAC PDU to the error confirmation unit 214 via the reception radio unit 211 or the like. The error check unit 214 detects an error in the MAC PDU and outputs “error” or “no error” information to the HARQ control unit 251. The error confirmation unit 214 outputs the transmission packet to the HARQ temporary storage unit 250 regardless of whether there is an error or the like.

  When the handover control unit 216 detects the handover of the terminal 40, the following operation is performed.

  The HARQ control unit 251 detects the type of the MAC PDU based on information from the error confirmation unit 214. That is, if the received MAC PDU is “error”, the HARQ control unit 251 determines that the MAC PDU is a “retransmitting” MAC PDU, and if “no error”, the HARQ control unit 251 determines that the MAC PDU is “delivered”. If neither information is obtained, it is determined that the MAC PDU is “unreceived”.

  When the HARQ control unit 251 determines that the MAC PDU is “delivered”, the HARQ control unit 251 instructs the MAC PDU information creation unit 252 and the MAC PDU creation unit 253 to create a MAC PDU. The MAC PDU creation unit 253 creates a MAC PDU, performs reordering processing in the ARQ temporary storage unit 266, and creates a RLC PDU by the RLC PDU creation unit 255 when a plurality (for example, 8) are prepared. Further, when a plurality of RLC PDUs (for example, four) are prepared by the transmission RLC SDU creation unit 257, RLC SDUs are created. The created RLC SDU is transferred from the transfer control unit 222 to the transfer destination radio base station 31 and the MME / UPE 11 which is a host device.

  Further, when the HARQ control unit 251 determines that the transmission packet is a MAC PDU that is “retransmitting”, the HARQ control unit 251 generates a dummy MAC PDU type MAC PDU for the dummy MAC PDU creation unit 261 and the dummy MAC PDU information creation unit 260. And instructing the MAC PDU creation unit 253 to create a MAC PDU other than the “resending” MAC PDU.

  The dummy MAC PDU creation unit 261 reads the data of the specific pattern from the dummy MAC PDU information creation unit 260 and creates a dummy MAC PDU type for the “resending” MAC PDU.

  The dummy MAC PDU information creation unit 260 creates packet information indicating identification information for identifying a dummy pattern, a dummy MAC PDU sequence number, a dummy bit pattern, and a dummy bit length, and a dummy MAC PDU creation unit 261. The information is added as a header. Alternatively, these pieces of information may be directly transferred to the transmission destination radio base station 31 as control signals.

  The created dummy MAC PDU is transferred to the dummy RLC PDU creation unit 263, and the MAC PDU stored in the ARQ temporary storage unit 266 is also transferred to the dummy RLC PDU creation unit 263. The dummy RLC PDU creation unit 263 creates a dummy RLC PDU including a dummy MAC PDU by integrating a plurality of dummy MAC PDUs and MAC PDUs. An example of a dummy RLC PDU is shown in FIG.

  Then, the transfer RLC SDU creation unit 265 collects a plurality of dummy RLC PDUs and RLC PDUs from the RLC PDU creation unit 255, etc., and RLC SDUs (hereinafter referred to as RLC SDUs including dummy MAC PDUs) The RLC SDU that does not include the dummy MAC PDU is referred to as “delivered RLC SDU”), and the transfer RLC SDU is transferred from the transfer control unit 222 to the transfer destination radio base station 31.

  The transfer RLC SDU creation unit 265 and the transmission RLC SDU creation unit 257 add identification information indicating whether the transmitted RLC SDU is “delivered RLC SDU” or “transfer RLC SDU” to the header. Such identification information may be directly transmitted to the transfer destination radio base station 31 as a separate control signal.

  When the HARQ control unit 251 determines that the transmission packet is a “unreceived” MAC PDU, it similarly instructs the dummy MAC PDU creation unit 261 and the like to create a dummy MAC PDU III type MAC PDU, and otherwise. The MAC PDU creation unit 253 and the like are instructed to create a normal MAC PDU. The subsequent processing is the same as in the case of “Resending”.

  In the transfer destination radio base station 31, the “transfer RLC SDU” or “delivered RLC SDU” is received by the transfer control unit 320 and output to the RLC SDU identification unit 352.

  The RLC SDU identification unit 352 identifies whether the transferred RLC SDU is “transfer RLC SDU” or “delivered RLC SDU”. The identification is performed from identification information in the header or information transferred as a control signal. When the RLC SDU is a “transfer RLC SDU”, the RLC SDU identification unit 352 outputs the RLC SDU to the RLC PDU identification unit 354. On the other hand, the RLC SDU identification unit 352 outputs the RLC SDU to the HARQ temporary storage unit 351 when it is “delivered RLC SDU”. Although the RLC SDU has been delivered and does not need to be transmitted from the terminal 40, the HARQ control unit 350 is temporarily stored in order to reliably identify the “delivered RLC SDU”.

  The RLC PDU identifying unit 354 divides the “transfer RLC SDU” into a plurality of RLC PDUs and identifies whether or not each RLC PDU includes a dummy MAC PDU. The identification is performed based on identification information added to the header or information based on a control signal or the like.

  When the RLC PDU identification unit 354 determines that the dummy MAC PDU is not included in the RLC PDU, the RLC PDU identification unit 354 outputs the RLC PDU to the HARQ temporary storage unit 351.

  On the other hand, the RLC PDU identifying unit 354 outputs the RLC PDU to the MAC PDU identifying unit 356 when the RLC PDU includes a dummy MAC PDU.

  The MAC PDU identification unit 356 divides the RLC PDU and determines whether each MAC PDU is a dummy MAC PDU or a delivered MAC PDU. This determination is also made based on the identification information and control signal added to the header. In the case of a delivered MAC PDU, it is stored in the HARQ temporary storage unit 351. In the case of a dummy MAC PDU, the MAC PDU identification unit 356 discards the dummy data and requests the HARQ control unit 350 to perform a new transmission.

  Then, the HARQ control unit 350 requests the terminal 40 to transmit a MAC PDU corresponding to the MAC PDU identified as the dummy MAC PDU. This request includes the sequence number of the dummy MAC PDU.

  For example, as in the first embodiment, the HARQ control unit 350 instructs the scheduler unit 328 to select the terminal 40, and the request is transmitted from the scheduler unit 328 via the uplink transmission control information creation unit 329, the encoding unit 330, and the like. Thus, the uplink transmission control information is transmitted to the terminal 40.

  In the terminal 40, uplink control information is extracted by the uplink control information extraction unit 412 via the reception radio unit 409 and the dummy MAC PDU temporarily stored in the HARQ temporary storage unit 427 or the ARQ temporary storage unit 425 is stored in the HARQ control unit. The data is read out under the control of 420 and the ARQ control unit 422. The read MAC PDU is transmitted to the transfer destination radio base station 31 via the transmission packet creation unit 428 and the like.

  The transfer destination radio base station 31 performs error checking on the MAC PDU received via the receiving radio unit 311 and the like in the error checking unit 314. When there is no error, the HARQ control unit 350 instructs the ACK / NACK creation unit 326 to create an “ACK” signal and transmits it to the terminal 40 via the coding unit 330 and the like. Further, the HARQ control unit 350 stores the received MAC PDU in the HARQ temporary storage unit 351. A plurality of MAC PDUs are rearranged in order, read from the RLC PDU creation unit 361, and temporarily stored in the ARQ temporary storage unit 360. The RLC PDU creation unit 361 creates an RLC PDU from the MAC PDU stored in the ARQ temporary storage unit 360, and the RLC SDU creation unit 362 creates an RLC SDU from a plurality of RLC PDUs. The created RLC SDU is transferred from the transfer control unit 320 to the MME / UPE 11.

  On the other hand, when the error confirmation unit 314 determines that the received MAC PDU has an error, the HARQ control unit 350 instructs the ACK / NACK creation unit 326 to create a “NACK” signal. The created “NACK” signal is transmitted to terminal 40 via encoding section 330 and the like. The MAC PDU including the error is stored in the HARQ temporary storage unit 351 by the HARQ control unit 350. The error confirmation unit 314 performs error confirmation on the retransmitted MAC PDU, and performs the above-described processing if there is no error.

  FIG. 33 is a diagram illustrating a sequence example of processing in the second embodiment. Briefly, when the transfer source wireless base station (BTS1) 21 detects a handover (S10), the MAC PDU received from the terminal 40 is not delivered (including both “not received” and “retransmitting”). Whether it is a PDU or a delivered MAC PDU is detected (S30).

  Then, the transfer source radio base station 21 creates a normal MAC PDU for the delivered MAC PDU (S12), and creates a dummy MAC PDU for the undelivered MAC PDU (S31).

  Thereafter, the transfer source radio base station 21 creates a dummy RLC PDU from a plurality of MAC PDUs including the dummy MAC PDU, and creates a normal RLC PDU from the normal MAC PDU (S32).

  Next, the transfer source radio base station 21 creates a transfer RLC SDU (dummy RLC SDU) from the dummy RLC PDU and the normal RLC PDU (S33), and a handover is performed (S16).

  Next, the transfer source wireless base station 21 notifies the dummy information (S34). The dummy information includes information such as whether the dummy MAC PDU is included in the MAC PDU constituting the transferred RLC SDU. Of course, this dummy information may be added to the header during RLC SDU transfer (S35).

  The transfer destination radio base station 31 confirms the MAC PDU to be retransmitted (S36), and requests the terminal 40 to transmit the MAC PDU (S20). The terminal 40 confirms the MAC PDU to be retransmitted (S37), and transmits the MAC PDU to the transfer destination radio base station 31 (S22).

  As described above, in the second embodiment, only the dummy MAC PDU is retransmitted from the terminal 40 in the handover destination transfer destination radio base station 31. For example, in the example shown in FIG. 12, only the MAC PDU of sequence number “12” is retransmitted. Compared with the case of transmitting MAC PCUs with sequence numbers “9” to “16” (when transmitting including MAC PDUs that have already been delivered), the transmission time is shortened and the throughput is improved.

  Next, Example 3 will be described. The entire system is the same as that in the first and second embodiments (see FIG. 23).

  In the third embodiment, the “retransmitting” MAC PDU is configured by data being retransmitted including an error (see FIG. 17, dummy MAC PDUII type), and the “unreceived” MAC PDU is configured by a specific pattern ( See FIG. 18, dummy MAC PDUIII type). Further, in the third embodiment, the number of retransmissions and the transmission method (RV information indicating whether the transmission is performed using only the parity or the parity and data, etc.) in the transfer source wireless base station 21 and the like Is generated, added to the transfer RLC SDU, and transferred to the transfer destination radio base station 31. The transfer destination radio base station 31 requests retransmission to the terminal 40 based on the retransmission information, receives the MAC PDU corresponding to the dummy MAC PDU, and continues the retransmission.

  34 shows a configuration example of the transfer source radio base station 21, FIG. 35 shows a configuration example of the transfer destination radio base station 31, FIG. 36 shows a configuration example of the dummy RLC PDU, and FIG. 37 shows a processing sequence example.

  The configuration of the transfer source radio base station 21 shown in FIG. 34 is substantially the same as the configuration of the transfer source radio base station 21 of the second embodiment (see FIG. 29). The point that HARQ control section 251 creates retransmission information and outputs it to dummy MAC PDU information creation section 260 is added.

  The configuration of the transfer destination radio base station 31 shown in FIG. 35 is also substantially the same as the configuration of the transfer destination radio base station 31 of the second embodiment (see FIG. 30), and the HARQ control unit 350 controls retransmission based on the retransmission information. A point to be added is added. In the third embodiment, the configuration example of the terminal 40 is the same as that of the second embodiment (see FIG. 31).

  Next, the operation in the third embodiment will be described with reference to FIG. 33 as appropriate.

  The terminal 40 sequentially transmits the MAC PDU to the transfer source wireless base station 21 as a transmission packet. The transfer source radio base station 21 is decoded via the reception radio unit 211 and the like, and the error check unit 214 checks the MAC PDU error. The received MAC PDU is stored in the HARQ temporary storage unit 250.

  As in the first embodiment, the HARQ control unit 251 determines that the received MAC PDU is “in error” and is a “retransmitting” MAC PDU, and “no error” and “delivered” MAC PDU. If neither “with error” nor “with no error” is determined, it is determined as an “unreceived” MAC PDU (S40).

  Also, the HARQ control unit 251 creates retransmission information, data length, and retransmission information indicating the transmission method at the previous transmission, and notifies the dummy MAC PDU information creation unit 260 of the retransmission information.

  The dummy MAC PDU creation unit 261 creates a dummy MAC PDU using the data being retransmitted stored in the HARQ temporary storage unit 250 for the MAC PDU being “retransmitted” (S41), and a dummy RLC PDU creation unit To H.263.

  Also, the dummy MAC PDU creation unit 261 creates a dummy MAC PDU using a specific pattern (all “0”, “1”, etc.) for the “unreceived” MAC PDU (S42), and creates a dummy RLC PDU. To the unit 263.

  For the “delivered” MAC PDU, the MAC PDU creation unit 253 creates a normal MAC PDU (S12).

  The dummy MAC PDU information creation unit 260 creates dummy MAC PDU information indicating the sequence number of the dummy MAC PDU and outputs the dummy MAC PDU information to the dummy RLC PDU information creation unit 262, and the retransmission information notified from the HARQ control unit 251 is also dummy. The data is output to the RLC PDU information creation unit 262.

  The dummy RLC PDU creation unit 263 collectively transfers the dummy MAC PDU from the dummy MAC PDU creation unit 261 and the MAC PDU from the ARQ temporary storage unit 266 to transfer the RLC PDU (similar to the second embodiment, the dummy MAC PDU is generated). An RLC PDU including the same is created (S43). The created transfer RLC PDU is output to the transfer RLC SDU creation unit 265. FIG. 36 is a diagram illustrating a configuration example of a transfer RLC PDU.

  The transfer RLC SDU creation unit 265 collectively creates the transfer RLC SDU by combining the RLC PDU from the RLC PDU creation unit 255 and the transfer RLC PDU from the dummy RLC PDU creation unit 263 (S44). The transfer RLC SDU is output to the transfer control unit 222.

  Information such as retransmission information is output to the transfer control unit 222 via the dummy RLC PDU information creation unit 262 and the transfer RLC SDU information creation unit 264.

  The transfer control unit 222 adds information including retransmission information to the transfer RLC SDU to the header and transfers the information to the handover destination (transfer destination) radio base station 31 (S46). Of course, as in the second embodiment, information including retransmission information may be separately transmitted as a control signal (S34, S45).

  The transfer destination radio base station 31 receives the transfer RLC SDU by the transfer control unit 320 and temporarily holds it by the RLC SDU identification unit 352. Further, the transfer RLC SDU identification information extraction unit 353 extracts retransmission information or the like added to the header or transmitted as a control signal.

  The RLC SDU identification unit 352 identifies whether or not the received RLC SDU is a transfer RLC SDU from the information added to the header. If the RLC SDU is a transfer RLC SDU, the RLC SDU is output to the RLC PDU identification unit 354. If not, the RLC PDU is output to the HARQ temporary storage unit 351.

  The RLC PDU identification unit 354 divides the transfer RLC SDU and identifies whether each RLC PDU is a transfer RLC PDU. If it is a forward RLC PDU, it is output to the MAC PDU identification unit 356, and if not, it is output to the HARQ temporary storage unit 351.

  The MAC PDU identification unit 356 divides the forward RLC PDU and identifies whether each MAC PDU is a “delivered” MAC PDU, a “retransmitting” MAC PDU, or an “unreceived” MAC PDU. The identification is performed from the identification information extracted by the dummy MAC PDU identification information extraction unit 357.

  The HARQ control unit 350 requests the terminal 40 to retransmit the MAC PDU “under retransmission” based on the retransmission information.

  For example, when the number of retransmissions is “1”, a request is made to transmit data (MAC PDU) and parity from the terminal 40, or when “2”, the parity is requested to be transmitted from the terminal 40 only. For example, a request according to the number of retransmissions is made, or a restriction is placed on the number of retransmissions, and a request for retransmission is not made when the request is exceeded.

  For the MAC PDU “not received”, the HARQ control unit 350 requests the terminal 40 to newly transmit the MAC PDU having the sequence number. The following processing is performed in the same manner as in the second embodiment.

  Also in the third embodiment, since only the dummy MAC PDU is retransmitted from the terminal 40 in the transfer destination radio base station 31 of the handover destination, the transmission time is shortened and the throughput can be improved as in the second embodiment. it can.

  In the first to third embodiments, the transfer RLC SDU and the transfer packet do not include the delivered data packet, and may be all dummy packets. Also in this case, it can be carried out in the same manner as in the first to third embodiments, and the same effects are obtained.

  In the second and third embodiments, it has been described that the identification of the dummy MAC PDU is performed based on information added to the dummy pattern or the header. In the fourth embodiment, an identifier (for example, represented by bits) for identifying a dummy MAC PDU is added to the head (see FIG. 38) or the tail of the dummy MAC PDU (see FIG. 39). The transfer destination radio base station 31 simply determines whether or not the MAC PDU is a dummy MAC PDU, whether the MAC PDU is a dummy MAC PDU, a dummy MAC PDU having a specific pattern in the case of a dummy MAC PDU, or a dummy MAC PDU using data being retransmitted. Can be identified.

  The identifier is created by the dummy MAC PDU creation unit 261 or the dummy MAC PDU information creation unit 260 of the transfer source wireless base station 21. Since the HARQ control unit 251 identifies the type of the received MAC PDU, it may be created by the dummy MAC PDU information creation unit 260 or the like based on the information.

  By adding this identifier, the transfer-destination wireless base station 31 can simply identify the dummy MAC PDU from the identifier, so that the dummy MAC PCU can be easily and easily identified.

  Next, Example 5 will be described. Example 5 is an example in the downlink direction from a radio base station to a terminal. The point that the handover is performed during the retransmission control is the same as in the first embodiment.

  FIG. 23 is a system configuration example of the E3G system in the fifth embodiment, FIG. 26 is a configuration example of the MME / UPE 11 in the fifth embodiment, FIG. 40 is a configuration example of the transfer source radio base station 21, and FIG. 42 shows a configuration example of the station 31, FIG. 42 shows a configuration example of the terminal 40, and FIG. 42 shows a sequence example of the overall processing.

  Since the description of the E3G system shown in FIG. 23 has been described in the first embodiment, a description thereof will be omitted. As shown in FIG. 40, the transfer source radio base station 21 includes a reception radio unit 211, a demodulation unit 212, a decoding unit 213, a received electric field strength information extraction unit 215, a handover control unit 216, and a retransmission control unit 218. A temporary storage unit 219, a packet creation unit 220, a transfer packet creation unit 221, a transfer control unit 222, a dummy packet creation unit 223, a dummy packet information creation unit 224, a transfer packet information creation unit 225, A scheduler unit 228, an encoding unit 230, a modulation unit 231, a transmission radio unit 232, an ACK / NACK extraction unit 270, and a downlink transmission control information creation unit 271 are provided. The same components as those of the transfer source radio base station 21 in the first embodiment are denoted by the same reference numerals.

  As shown in FIG. 41, the transfer destination radio base station 31 includes a reception radio unit 311, a demodulation unit 312, a decoding unit 313, a handover control unit 316, a scheduler unit 328, an encoding unit 330, and a modulation unit. 331, transmission radio section 332, ACK / NACK extraction section 370, retransmission control section 371, transfer control section 372, temporary storage section 377, downlink transmission control information creation section 379, and forward packet reception section 380 A forward packet identification information extraction unit 381, a dummy packet identification unit 382, a dummy packet identification information extraction unit 383, and a transmission packet creation unit 384. The same components as those in the transfer destination radio base station 31 of the first embodiment are denoted by the same reference numerals.

  As illustrated in FIG. 42, the terminal 40 includes an encoding unit 403, a modulation 404, a transmission radio unit 405, a reception radio unit 409, a demodulation unit 410, a decoding unit 411, and a downlink transmission control information extraction unit 431. An error confirmation unit 432, a temporary storage unit 433, a retransmission control unit 434, and an ACK / NACK creation unit 435.

  Next, the operation will be described. First, the ROHC unit 121 of the MME / UPE 11 that is the host device compresses the IP header, encrypts it with the encryption unit 122, and the PDCP PDU creation unit 123 performs PDCP PDU information (for example, sequence number), data length, A transfer packet is created by adding a CRC or the like to the encrypted data as a header. The created transfer packet is transferred to the transfer source radio base station 21.

  The transfer source wireless base station 21 receives the transfer packet by the transfer control unit 222 and outputs it to the temporary storage unit 219. The packet creation unit 220 reads the transfer packet stored in the temporary storage unit 219 and creates a transmission packet by dividing the transfer packet. The created transmission packet is encoded by the encoding unit 230, modulated by the modulation unit 231, and transmitted to the terminal 40 by the transmission radio unit 232 at a predetermined radio frequency. The transmission packet is temporarily stored in the temporary storage unit 219.

  The terminal 40 receives the transmission packet by the reception radio unit 409, demodulates it by the demodulation unit 410, and decodes it by the decoding unit 411. The error confirmation unit 432 confirms the error of the decoded packet by using CRC, and notifies the retransmission control unit 434 of the result.

  If there is no error in the decoded packet, retransmission control section 434 instructs ACK / NACK creation section 435 to generate an “ACK” signal, and if there is an error, it generates ACK / NACK creation section 435 to generate a “NACK” signal. To instruct. The created “ACK” signal or “NACK” signal is transmitted to the transfer source radio base station 21 via the encoding unit 403, the modulation unit 404, and the transmission radio unit 405.

  The transfer source radio base station 21 modulates or decodes the “ACK” signal or “NACK” signal transmitted from the terminal 40 via the reception radio unit 211, the demodulation unit 212, and the decoding unit 213. The decoded “ACK” signal or the like is output to the ACK / NACK extraction unit 270, extracts whether the received signal is an “ACK” signal or a “NACK” signal, and outputs the result to the retransmission control unit 218. . Note that the encoding and modulation schemes of the transfer source wireless base station 21 and the terminal 40 are performed based on the transmission control information notified in advance.

  When receiving the “ACK” signal, the retransmission control unit 218 deletes the transmission packet stored in the temporary storage unit 219, and when receiving the “NACK” signal, the retransmission control unit 218 transmits a transmission method ( Instructing the scheduler unit 228 to transmit to the terminal 40 while instructing to create transmission control information by changing the modulation, encoding method, etc.).

  Since the packet to be retransmitted is stored in the temporary storage unit 219, the packet creation unit 220 reads the packet from the temporary storage unit 219, creates a retransmission packet to be retransmitted, and passes through the encoding unit 230 or the like. To the terminal 40. Thereby, the transmission packet is retransmitted from the transfer source radio base station 21 to the terminal 40.

  Consider a case where handover from the transfer source radio base station 21 to the transfer destination radio base station 31 is performed during such a series of operations.

  When the handover control unit 216 detects the occurrence of the handover of the terminal 40 from the received field strength information from the received field strength information extraction unit 215, the handover control unit 216 instructs the retransmission control unit 218, the dummy packet creation unit 223, and the like to operate.

  The transfer source radio base station 21 does not confirm the delivery of the transfer packet to the MME / UPE 11 that is the host device unless the delivery confirmation of the transmission packet transmitted to the terminal 40 is performed. Therefore, when the transmission packet from the terminal 40 is being retransmitted or has not been transmitted, delivery confirmation of the transfer packet is not performed. As a result, transmission packets “under retransmission” and “untransmitted” (hereinafter referred to as “undelivered” transmission packets) remain as residual data in the transfer source radio base station 21 that is the handover source. Such residual data is data that should be transferred to the transfer destination radio base station 31 that is the handover destination. By transferring the residual data, data is transmitted from the transfer destination radio base station 31 to the terminal 40 continuously after the handover.

  On the other hand, the retransmission control unit 218 of the transfer source wireless base station 21 deletes the transmission packet for which the delivery confirmation has been made from the temporary storage unit 219. As a result, the transmission packet whose delivery has been confirmed does not exist in the transfer source radio base station 21. On the other hand, in the transfer destination radio base station 31 that is the handover destination, delivery confirmation of the transmission packet transmitted by the transfer source radio base station 21 has not been made. Therefore, the transfer destination radio base station 31 requests the MME / UPE 11 to retransmit the transmission packet whose delivery has been confirmed, and again transmits the transmission packet transmitted from the transfer source radio base station 21 to the terminal 40. The data is transmitted from the station 31 to the terminal 40.

  Therefore, in the fifth embodiment, for the transmission packet that has been confirmed for delivery, a transmission packet is created with dummy data, and information indicating that the delivery has been confirmed is added, and the transfer source radio base station 21 that is the handover source Then, the data is transferred to the handover destination transfer destination radio base station 31. Since the transfer destination radio base station 31 can confirm the delivery of the transmission packet, the transmission packet is not transmitted to the terminal 40, the transmission time can be reduced, and the throughput can be improved.

  The “undelivered” transmission packet also uses “untransmitted” data or “retransmitting” data, creates a transmission packet using the data as dummy data, and transfers it to the transfer destination radio base station 31. Information indicating “undelivered” is also added and transferred (or may be transferred as a separate control signal as in the first embodiment). Data can be transmitted from the transfer destination radio base station 31 to the terminal 40 using “untransmitted” data included in the “undelivered” transmission packet.

  The transmission packet is created using the dummy data as follows. That is, the retransmission control unit 218 of the transfer source radio base station 21 creates “delivered” or “undelivered” dummy packets based on the “ACK” signal from the ACK / NACK extraction unit 270 or other signals, respectively. .

  Originally, “undelivered” dummy packets should be created separately as “during resending” dummy packets and “unsent” dummy packets. In the sixth embodiment, “under resending” and “ “Unsent” is treated as “undelivered” to speed up processing.

  In the case of “ACK”, the retransmission control unit 218 instructs the dummy packet creation unit 223 and the dummy packet information creation unit 224 to create a “delivered” dummy packet because the transmission packet has been confirmed for delivery.

  For example, as shown in FIG. 19, the dummy packet creation unit 223 creates a dummy packet based on specific pattern data such as all “0” and all “1”. The dummy packet information creation unit 224 creates dummy packet information indicating specific pattern information, delivery confirmation completed, and the like.

  The transfer packet creation unit 221 creates a transfer packet by collecting a plurality of dummy packets. The transfer packet information creation unit 225 creates transfer packet information from the dummy packet information from the dummy packet information creation unit 224, for example, by adding information such as the fact that a “delivered” dummy packet is included in the transfer packet.

  The transfer control unit 222 adds the transfer packet information from the transfer packet information generation unit 225 to the transfer packet from the transfer packet generation unit 221 as a header, and transfers the packet to the transfer destination radio base station 31. The transfer packet information may be separately transferred as a control signal as in the first embodiment.

  On the other hand, when the ACK / NACK extraction unit 270 extracts other signals, the retransmission control unit 218 instructs the dummy packet generation unit 223 and the dummy packet information generation unit 224 to generate “undelivered” dummy packets. . For example, as shown in FIG. 21 and FIG. 22, the “undelivered” dummy packet is retained for retransmission because it is not transmitted by the transfer source radio base station 21 and is not transmitted. The dummy packet using the actual data being “retransmitted”.

  The dummy packet creation unit 223 reads “undelivered” data (actually, “retransmitting” or “unsent” data) from the temporary storage unit 219 and creates a dummy packet as dummy data. In the dummy packet information creation unit 224, the type of dummy packet (information indicating that it is a “undelivered” dummy packet), undelivered information, a dummy packet sequence number, a dummy bit pattern, and a dummy bit length Is generated as dummy packet information. The subsequent steps are the same as in the case of “delivered”.

  The transfer destination radio base station 31 receives the dummy packet transferred from the transfer source radio base station 21 by the transfer control unit 372 and temporarily holds it by the transfer packet receiving unit 380.

  The transfer packet identification information extraction unit 381 extracts transfer packet information added to the header of the transfer packet (or transferred as a control signal), and transfers the transfer packet transferred from the transfer source radio base station 21 or a higher-level device. It is identified whether it is a transfer packet transferred from the MME / UPE 11. When the transfer packet identification unit 381 identifies the transfer packet from the transfer source radio base station 21, the transfer packet reception unit 380 outputs the held transfer packet to the dummy packet identification unit 382.

  The dummy packet identification unit 382 uses the dummy packet identification information extracted by the dummy packet identification information extraction unit 383 to identify whether the transfer packet that is a dummy packet is “delivered” or “not delivered”.

  The dummy packet identification unit 382 discards the dummy packet when the packet is “delivered”, and stores the data of the dummy packet in the temporary storage unit 377 when the packet is “undelivered”. Further, when the dummy packet identification unit 382 is a “undelivered” dummy packet, the dummy packet identification unit 382 requests the retransmission control unit 371 to newly transmit the corresponding packet via the dummy packet identification information extraction unit 383.

  The retransmission control unit 371 instructs the scheduler unit 328 to transmit a new packet corresponding to the “undelivered” dummy packet. The scheduler unit 328 reads the data of the corresponding “undelivered” dummy packet from the temporary storage unit 377 and causes the transmission packet creation unit 384 to create a transmission packet. The created transmission packet is transmitted to the terminal 40 through the encoding unit 384 and the like together with the transmission control information created by the downlink transmission control information creating unit 379.

  In the terminal 40, an error of the transmission packet is confirmed by the error confirmation unit 432, and an “ACK” signal or “NACK” signal is created under the control of the retransmission control unit 434 and transmitted to the transfer destination radio base station 31.

  When receiving the “ACK”, the retransmission control unit 371 of the transfer destination radio base station 31 deletes the data of the “undelivered” dummy packet stored in the temporary storage unit 377. On the other hand, when “NACK” is received, the retransmission control unit 371 controls the scheduler unit 328 and the like to retransmit the data of the “undelivered” dummy packet stored in the temporary storage unit 377.

  FIG. 43 is a sequence example of processing in the fifth embodiment. Since the description is redundant, in brief, first, when the transfer source radio base station (BTS1) 21 detects a handover (S50), the type of transfer packet transferred from the transfer source radio base station 21 to the terminal 40 ( ("Delivered" or "undelivered") is detected (S51). For "delivered" packets, a dummy packet according to a specific pattern is used. For "undelivered" packets, actual data is used as dummy data. A dummy packet is created (S52 to S54).

  Thereafter, a handover is performed from the transfer source radio base station 21 to the transfer destination radio base station (BTS2) 31 (S55). The transfer source radio base station 21 notifies the transfer destination radio base station 31 of dummy information indicating the type of dummy packet, information on whether delivery has been confirmed or not confirmed (S56), and transfers the dummy packet ( S57). As described above, dummy information may be added to the header of the transfer packet and transferred.

  The transfer destination radio base station 31 confirms the packet to be transmitted (S58, S60), performs a new transmission (S61), and resends it if necessary (S59).

  As described above, in the fifth embodiment, the transmission packet transmitted from the transfer source radio base station 21 to the terminal 40 and confirmed for delivery is not transmitted from the transfer destination radio base station 31 to the terminal 40. Compared with the case where such a transmission packet is transmitted from the transfer destination radio base station 31 to the terminal 40, the transmission time can be shortened, and the throughput can be improved.

  Next, Example 6 will be described. The sixth embodiment is an example in which the packet is specifically a MAC PDU, RLC PDU, or RLC SDU. There are two types of dummy packets, “delivered” and “undelivered”, as in the fifth embodiment.

  FIG. 23 shows an example of the overall system configuration, FIG. 26 shows an example of the configuration of the MME / UPE 11 as the host device, FIG. 44 shows an example of the configuration of the transfer source radio base station 21, FIG. 45 shows an example of the configuration of the transfer destination radio base station 31, 46 shows an example of a dummy RLC PDU, FIG. 47 shows an example of a processing sequence, FIG. 48 shows an example of a dummy RLC PDU, and FIG. 56 shows a configuration example of the terminal 40.

  Since the configuration of the E3G system illustrated in FIG. 23 has been described in the first embodiment, the description thereof is omitted. As shown in FIG. 44, the configuration of the transfer source radio base station 21 is different from the transfer source radio base station 21 (see FIG. 40) of the fifth embodiment in that HARQ control unit 272, ARQ control unit 273, ARQ temporary storage unit 274, dummy MAC PDU creation unit 275, dummy MAC PDU information creation unit 276, transfer RLC PDU creation unit 277, transfer RLC PDU information creation unit 278, transfer RLC SDU creation unit 279, transfer An RLC SDU information creation unit 280, an RLC SDU (PDCP PDU) creation unit 281, an RLC PDU creation unit 282, a MAC PDU creation unit 283, a HARQ temporary storage unit 284, and a transmission packet creation unit 284 are provided.

  Compared to the transfer destination radio base station 31 (see FIG. 41) of the fifth embodiment, the transfer destination radio base station 31 illustrated in FIG. 45 newly includes a HARQ control unit 390, a HARQ temporary storage unit 391, and an RLC SDU. Identification unit 392, transfer RLC SDU identification information extraction unit 393, RLC PDU identification unit 394, transfer RLC PDU identification information extraction unit 395, MAC PDU identification unit 396, dummy MAC PDU identification information extraction unit 397, MAC A PDU creation unit 398, an ARQ control unit 401, an ARQ temporary storage unit 402, an RLC SDU creation unit 403, an RLC PDU creation unit 404, and an error check unit 405 are provided.

  The terminal 40 illustrated in FIG. 56 is newly provided with a HARQ temporary storage unit 440 and a HARQ control unit 441 in comparison with the terminal 40 (see FIG. 42) of the fifth embodiment.

  Next, the operation of the sixth embodiment will be described. First, in the MME / UPE 11, a transfer packet is configured as in the fifth embodiment. The transfer packet is in the form of PDCP PDU (RLC SDU).

  The transfer source radio base station 21 receives a PDCP PDU as a transfer packet by the RLC SDU reception unit 281, and the RLC PDU creation unit 282 divides the RLC SDU and creates a plurality of RLC PDUs. The RLC PDU creation unit 282 temporarily stores each created RLC PDU in the ARQ temporary storage unit 274 and outputs it to the MAC PDU creation unit 283.

  The MAC PDU creation unit 283 divides the RLC PDU to create a plurality of MAC PDUs, and outputs each MAC PDU to the HARQ temporary storage unit 284 for storage.

  When the scheduler unit 228 permits transmission to the terminal 40, the scheduler unit 228 instructs the transmission packet creation unit 285 to create a transmission packet (a packet composed of one or a plurality of MAC PDUs), and downlink transmission control information The creation unit 271 is instructed to create transmission control information indicating the designated transmission method (modulation method, encoding method, etc.).

  The transmission packet creation unit 285 reads the MAC PDU stored in the HARQ temporary storage unit 274, adds a header, a CRC, and a sequence number (SN), and creates a transmission packet. The transmission packet creation unit 285 outputs the transmission packet to the encoding unit 285 and stores it in the HARQ temporary storage unit 284.

  The transmission packet is added with downlink transmission control information from the downlink transmission control information creation unit 271, is encoded by the encoding unit 230, and the like, and the transmission packet is transmitted from the transfer source radio base station 21 to the terminal 40. The

  The terminal 40 receives the transmission packet and performs error confirmation in the error confirmation unit 432 via the reception wireless unit 409 and the like. The result is notified to the HARQ control unit 441, and an “NACK” signal or an “ACK” signal is created from the ACK / NACK creation unit 435 depending on whether or not there is an error. The generated “NACK” or “ACK” signal is transmitted to the transfer source radio base station 21. Note that the HARQ control unit 441 stores transmission packets including errors in the HARQ temporary storage unit 440.

  The transfer source radio base station 21 uses the ACK / NACK extraction unit 270 to extract the “ACK” signal or “NACK” signal transmitted from the terminal 40 via the reception radio unit 211 or the like. The result is notified to the HARQ control unit 272.

  When receiving the “ACK” signal, the HARQ control unit 272 deletes the data of the transmission packet stored in the HARQ temporary storage unit 274.

  On the other hand, when receiving the “NACK” signal, the HARQ control unit 272 instructs the scheduler unit 228 to change the transmission method or the like and transmit the target transmission packet to the terminal 40. Then, the transmission packet is retransmitted to the terminal 40 in accordance with an instruction from the scheduler unit 228. In addition, when the delivery confirmation of all the MAC PDUs constituting the RLC PDU is obtained (when the “ACK” signal is received), the HARQ control unit 272 stores in the ARQ temporary storage unit 274 via the ARQ control unit 273. Control to erase the RLC PDUs made.

  A case where the terminal 40 performs handover from the transfer source radio base station 21 to the transfer destination radio base station 31 during this series of operations will be described below.

  Similar to the fifth embodiment, when detecting the occurrence of a handover, the handover control unit 216 instructs the HARQ control unit 272 and the like to start operation. When the ACK / NACK extraction unit 270 extracts the “ACK” signal, the HARQ control unit 272 includes a dummy MAC PDUIV type including dummy data of a specific pattern (for example, all “0”, “1”, etc.) (see FIG. 19). ) To the dummy MAC PDU creation unit 275 (shown as “new transmission information” in FIG. 44). Since the delivery confirmed data has already been deleted from the HARQ temporary storage unit 284, data of a specific pattern is used.

  In response to this instruction, the dummy MAC PDU creation unit 275 creates such a dummy MAC PDU IV type MAC PDU. In addition, the dummy MAC PCU information creation unit 276 determines that the MAC PDU is a dummy MAC PDUIV type, MAC PDU information indicating the SN number of the MAC PDU, etc., and delivery information indicating “delivery confirmed”. create. These are collectively used as dummy MAC PDU identification information.

  The transfer RLC PDU creation unit 277 creates an RLC PDU from a plurality of dummy MAC PDUs. Since the created RLC PDU includes a dummy MAC PDU, an RLC PDU is created as a transfer RLC PDU as in the second embodiment. An example of the created RLC PDU is shown in FIG.

  The transfer RLC SDU creation unit 279 creates a transfer RLC SDU from a plurality of transfer RLC PDUs. Note that the MAC PCU information and the delivery information indicate the transfer RLC PDU and the transfer RLC SDU in the information generation units 278 and 280 via the transfer RLC PDU generation unit 277 and the transfer RLC SDU generation unit 279. Information and the like are added, and finally transfer RLC SDU information is created. This transfer RLC SDU information includes dummy MAC PDU identification information.

  The transfer control unit 222 adds the transfer RLC SDU information as a header to the transfer RLC SDU and transfers it to the transfer destination radio base station 31. Alternatively, only the transfer RLC SDU information may be transferred separately as a control signal.

  In the transfer destination radio base station 31 of the handover destination, the transferred transfer RLC SDU is temporarily held by the transfer control unit 372. Then, the RLC SDU identification unit 392 identifies whether the received RLC SDU is a transfer RLC SDU from the transfer RLC SDU information extracted by the transfer RLC SDU identification information extraction unit 393. When the received RLC SDU is a transfer RLC SDU, the RLC SDU identification unit 392 outputs the transfer RLC SDU to the RLC PDU identification unit 394.

  The RLC PDU identification unit 394 divides the transfer RLC SDU and identifies whether each RLC PDU is a transfer RLC PDU from the transfer RLC PDU information extracted by the transfer RLC PDU identification information extraction unit 395. The RLC PDU identifying unit 394 outputs the transfer RLC PDU to the MAC PDU identifying unit 396.

  The MAC PDU identification unit 396 divides the transfer RLC PDU, and for each MAC PDU, the MAC PDU is “delivered” or “undelivered” based on the dummy MAC PDU information extracted by the dummy MAC PDU identification information extraction unit 397. ". These identification results are notified to the HARQ control unit 390.

  When the MAC PDU is “delivered”, the HARQ control unit 390 discards the dummy MAC PDU held in the MAC PDU identification unit 396. This is because there is no problem if the delivery confirmation is made at the transfer destination radio base station 31.

  On the other hand, when the MAC PDU is “undelivered”, the HARQ control unit 390 temporarily stores the dummy MAC PDU in the HARQ temporary storage unit 391 via the MAC PDU creation unit 398 and causes the scheduler unit 328 to Instruct to send. The “undelivered” dummy MAC PDU stored in the HARQ temporary storage unit 391 is transmitted to the terminal 40 as a transmission packet by the transmission packet creation unit 384.

  The terminal 40 determines whether the error confirmation unit 432 has received the transmission packet without error and transmits “ACK” or “NACK” to the transfer destination radio base station 31. Thereafter, the processing is repeated until the transmission packet is transmitted to the terminal 40 without error.

  FIG. 47 is a diagram illustrating an example of a processing sequence according to the sixth embodiment. The processing in the sixth embodiment is summarized. Since this is a duplicate description, a brief description will be given.

  When the handover source transfer base radio base station (BTS1) 21 detects a handover (S50), it confirms whether the MAC PDU transmitted to the terminal 40 is a “delivered” MAC PDU or an “undelivered” MAC PDU. Then, a dummy MAC PDUIV type is created for the “delivered” MAC PDU, and a V-type or VI-type dummy MAC PDU is created for the “undelivered” MAC PDU (S62). Then, the transfer source radio base station 21 creates a transfer RLC PDU from the dummy MAC PDU (S64), and creates a transfer RLC SDU from the transfer RLC PDU (S65).

  Thereafter, when handover is performed (S54), the transfer source radio base station 21 notifies dummy information such as dummy MAC PDU information to the transfer destination radio base station 31 of the handover destination (S66), and transfers the transfer RLC SDU. Transfer (S67). Of course, as described above, dummy information may be added to the header of the transfer RLC SDU and transferred.

  The transfer destination radio base station 31 confirms the MAC PDU to be retransmitted (“undelivered” MAC PDU) (S68), and transmits the MAC PDU to the terminal (UE1) 40 (S58).

  Thus, in the sixth embodiment, since the MAC PDU whose delivery has been confirmed is not transmitted from the handover destination transfer destination radio base station 31 to the terminal 40, the data transmission time can be shortened and the throughput can be improved. be able to.

  Next, Example 7 will be described. In the sixth embodiment, the transfer source wireless base station 21 stores in the ARQ temporary storage unit 274 when confirmation of delivery of all the MAC PDUs constituting the RLC PDU ("ACK" is returned from the terminal 40) is obtained. It was decided to erase the stored RLC PDU.

  In the seventh embodiment, all MAC PDUs constituting the RLC PDU are stored in the ARQ temporary storage unit 274 until delivery confirmation can be performed in units of RLC PDUs. In the seventh embodiment, a dummy MAC PDU (see FIG. 20, dummy MAC PDUV type) is created using this RLC PDU and transferred to the transfer destination radio base station 31.

  Specifically, it is created as follows. That is, the transfer RLC PDU creation unit 277 (FIG. 44) of the transfer source radio base station 21 creates a transfer RLC PDU including a dummy MAC PDUV type using the RLC PDU stored in the ARQ temporary storage unit 274. The transfer RLC PDU creation unit 277 creates a dummy MAC PDU using the actual data of the MAC PDU that has not been deleted from the ARQ temporary storage unit 274. FIG. 48 is a diagram illustrating a configuration example of a transfer RLC PDU.

  The transfer RLC PDU information creation unit 278 creates delivery information indicating that the MAC PDU has been confirmed to be delivered, and MAC PDU information including a dummy MAC PDUV type and its SN number, and further confirms that the MAC PDU is a transfer RLC PDU. Transfer RLC PDU information including information to be shown is created, and these are output to the transfer RLC SDU creation unit 279 and the transfer RLC SDU information creation unit 280. The subsequent processing is the same as in the sixth embodiment.

  Since the seventh embodiment is the same as the sixth embodiment except that actual data is used for the data constituting the dummy MAC PDU, the throughput can be improved as in the sixth embodiment.

  Next, Example 8 will be described. In the sixth embodiment, the types of dummy MAC PDUs are described as “delivery confirmed” and “undelivered”. In the eighth embodiment, “undelivered” is divided into “untransmitted” and “retransmitting”, so that three types of dummy MACs of “delivery confirmed”, “untransmitted”, and “retransmitting” are provided. PDUs (type IV (FIG. 19), type VI (FIG. 21), and type VII (FIG. 22)) are created. By transferring the MAC PDU indicating “under retransmission” from the transfer source radio base station 21 to the transfer destination radio base station 31, the transfer destination radio base station 31 can continue the retransmission.

  49 is a configuration example of the transfer source radio base station 21, FIG. 50 is a configuration example of the transfer destination radio base station 31, FIG. 51 is an example of a processing sequence, FIG. 23 is a configuration example of the entire system, and FIG. Examples are shown respectively. Below, a different part from Example 6 is demonstrated.

  Based on the extraction result from the ACK / NACK extraction unit 270, the HARQ control unit 251 of the transfer source radio base station 21 detects the state of the transmission packet (consisting of one or a plurality of MAC PDUs). That is, the HARQ control unit 251 detects “delivered” when “ACK” is returned, “under retransmission” when “NACK” is returned, and “untransmitted” when neither is returned.

  The HARQ control unit 251 reads the “in retransmission” MAC PDU from the HARQ temporary storage unit 284 and instructs the dummy MAC PDU creation unit 275 to create a dummy MAC PDUVII type. In addition, the dummy MAC PDU information creation unit 276 transmits retransmission information (number of retransmissions, data length, transmission at the previous transmission) together with dummy information indicating that the dummy MAC PDU is SN number, VII type, retransmission, etc. A method (modulation method, RV information, etc.) and the like, and outputs it to the transfer RLC SDU information creation unit 280 via the transfer RLC PDU information creation unit 278. The retransmission information may be created by the transfer RLC PDU information creation unit 278 or the transfer RLC SDU information creation unit 280.

  Also, the HARQ control unit 251 reads out “unsent” MAC PDUs from the HARQ temporary storage unit 284 and instructs the dummy MAC PDU creation unit 275 to create a dummy MAC PDUVI type. The dummy MAC PDU information creation unit 276 creates retransmission information in the same manner together with dummy information indicating that the transmission has not been performed.

  The case of “delivered” is the same as in the sixth embodiment.

  Similarly to the sixth embodiment, the information created by each information creation unit 276 is added to the MAC PDU header or the like and transferred to the transfer destination radio base station 31, or may be transferred separately as a control signal. Good. Thereafter, processing similar to that in the sixth embodiment is performed, and the transfer RLC SDU is transferred to the transfer destination radio base station 31 that is the handover destination.

  The transfer destination radio base station 31 identifies the transfer RLC SDU with the RLC SDU identification unit 392 and outputs the MAC PDU divided from the RLC SDU to the MAC PDU identification unit 396.

  Based on the information extracted by the dummy MAC PDU identification information extraction unit 397, the MAC PDU identification unit 396 identifies whether the input MAC PDU is “retransmitting”, “not yet transmitted”, or “delivered” .

  When “retransmitting”, the MAC PDU identifying unit 396 notifies the HARQ control unit 290 of retransmission information, and the HARQ control unit 290 retransmits transmission data from the transfer destination radio base station 31 to the terminal 40 based on the retransmission information. . On the other hand, when “not transmitted”, new transmission is performed according to the scheduler unit 328.

  Also in the eighth embodiment, similarly to the sixth embodiment, transmission of the confirmed RLC PDU is not performed from the transfer destination radio base station 31 that is the handover destination to the terminal 40, so that the throughput can be improved. .

  Next, Example 9 will be described. In the ninth embodiment, in the sixth to eighth embodiments, an identifier is added to the beginning or end of the dummy MAC PDU to identify the dummy MAC PDU. The transfer destination radio base station 31 can easily identify the dummy MAC PDU by using this identifier. FIGS. 51 to 55 show configuration examples of transfer RLC PDUs composed of dummy MAC PDUs with identifiers added thereto.

  The creation of this identifier will be described using the configuration of the seventh embodiment. The dummy MAC PDU creation unit 275 (see FIG. 44) of the transfer source wireless base station 21 uses the “undelivered” data stored in the HARQ temporary storage unit 284 based on an instruction from the HARQ control unit 272 to perform dummy processing. In addition to creating a MAC PDU, an identifier is created and added to the beginning and end of the dummy MAC PDU.

  Also, the dummy MAC PDU creation unit 275 creates a dummy MAC PDU by adding an identifier to the beginning or end of the dummy MAC PDU for “delivered”. Thereafter, processing is performed in the same manner as in the seventh embodiment.

  The identifier may be a different identifier so that the type of the dummy MAC PDU can be identified. The transfer destination radio base station 31 can easily identify the dummy MAC PDU and also can identify the type.

  Next, Example 10 will be described. The tenth embodiment calculates time and the like during uplink transmission, and if it takes too much time, the dummy data is not transferred from the transfer source to the transfer destination radio base station 31 and transferred from the terminal 40 to the transfer destination. All the MAC PDUs constituting the RLC SDU are transmitted to the radio base station 31. Since the processing time can be reduced, the transmission time can be shortened and the throughput can be improved.

  This will be described with reference to the configuration of the second embodiment (FIGS. 29 to 31).

First, when a transfer RLC SDU including dummy data is transferred to the transfer destination radio base station 31, a dummy MAC PDU is created and a time T1 until the transfer RLC is created is calculated. For example, the time when the HARQ control unit 251 instructs the dummy MAC PDU creation unit 261 to create the dummy MAC PDU is notified to the dummy MAC PDU creation unit 261 together with the instruction, and sequentially, the dummy RLC
The PDU creation unit 263 and the transfer RLC SDU creation unit 265 are notified, and the transfer RLC SDU creation unit 265 measures the time at which the transfer RLC SDU has been created, and the difference between the time from the HARQ control 251 and the time at which the creation is completed. T1 is calculated.

  Next, the transfer RLC SDU including the dummy MAC PDU is transferred from the transfer source radio base station 21 to the transfer destination radio base station 31, and until the delivery confirmation of the transmission packet transmitted from the terminal 40 to the transfer destination radio base station 31 is obtained. The time T2 is calculated. For example, the time from when the HARQ control unit 350 receives a transfer packet until the ACK / NACK creation unit 326 is instructed to create “ACK” is T2.

  On the other hand, for all the MAC PDUs constituting the transfer RLC SDU, a time until new delivery is transmitted from the terminal 40 to the transfer destination radio base station 31 and delivery confirmation is taken is T3. For example, the time from when the transmission packet from the terminal 40 is stored in the HARQ temporary storage unit 351 in the HARQ control unit 350 until the instruction to create “ACK” is T3.

At this time,
T1 + T2> T3
Then, the transfer RLC SDU is not transferred from the handover source transfer source radio base station 21 to the handover destination transfer destination radio base station 31, and the transfer RLC SDU is configured from the terminal 40 to the transfer destination radio base station 31. All MAC PDUs to be transmitted. This is because the transfer time of the transfer RLC SDU from the transfer source to the transfer destination radio base station 31 takes more time than the transfer time from the terminal 40 to the transfer destination radio base station 31.

  The time T3 may be calculated as a threshold value.

  Next, Example 11 will be described. In the tenth embodiment, the up direction has been described. In the eleventh embodiment, the down direction will be described. Example 6 is used for the configuration and the like (see FIGS. 29 to 31).

  First, the time T4 from the start of dummy MAC PDU creation until the completion of creation of the transfer RLC SDU is calculated. For example, as in the tenth embodiment, the time from when the HARQ control unit 251 instructs the creation of the dummy MAC PDU to when the transfer RLC SDU creation unit 265 creates the transfer RLC SDU may be measured.

  Next, after receiving the transfer RLC SDU, the transfer destination radio base station 31 performs new transmission or retransmission to the terminal 40, and measures the time T5 until delivery confirmation is obtained. For example, the transfer control unit 320 measures the time when the transfer RLC SDU is received, outputs the information to the MAC PDU identification unit 356 together with the RLC SDU, notifies the HARQ control unit 350, and the HARQ control unit 350 generates the “ACK”. The HARQ control unit 350 measures the time until an instruction is given to the ACK / NACK creation unit 326.

  On the other hand, a time T5 from when all MAC PDUs constituting the transfer RLC SDU are transmitted from the transfer destination radio base station 31 to the terminal 40 until delivery confirmation is obtained is measured. For example, the HARQ control unit 350 calculates the time from when the transfer RLC SDU is received until the “ACK” creation instruction is output to the ACK / NACK creation unit 326 for all MAC PDUs.

At this time,
T4 + T5> T6
In this case, the transfer destination radio base station 31 configures a corresponding RLC SDU without transferring the transfer RLC SDU from the handover source transfer source radio base station 21 to the handover destination transfer destination radio base station 31. All MAC PDUs are transferred to the terminal 40. This is because the transfer time of the transfer RLC SDU takes longer than the transfer time of the MAC PDU at the terminal 40.

The time T6 may be set as a threshold value.
In the eleventh embodiment, as in the tenth embodiment, since the processing time can be shortened, the throughput can be improved.

  The present invention is suitable for use in a wireless communication system in which a mobile terminal such as a mobile phone or a PDA (Personal Digital Assistance) performs wireless communication with a wireless base station.

Claims (16)

Radio communication is performed between the second radio base station and the terminal instead of the first radio base station by handover from a state in which radio communication is performed between the first radio base station and the terminal. In a wireless communication system,
In the first radio base station,
When data remaining in the first radio base station is transferred to the second radio base station, a delivery confirmation is not received among transmission packets transmitted from the terminal to the first radio base station. and creating a dummy packet, forwarding the packet creation unit for creating a transfer packet containing the said dummy packet said residual data to the transmission packet undelivered,
A wireless communication system comprising: a transfer unit configured to transfer the created transfer packet to the second radio base station. In a wireless base station that performs wireless communication with a terminal,
When the remaining data is transferred to the handover destination radio base station when the handover is executed, the transmitted packet transmitted from the terminal is being retransmitted or not transmitted without acknowledgment from the terminal. A packet identification unit for identifying whether the packet is an undelivered transmission packet;
Wherein to said transmission packet identified as transmission packet of the undelivered by the packet identifying section, creating a dummy packet, and forwarding the packet creation unit for creating a transfer packet containing the said dummy packet said residual data,
A wireless base station, comprising: a transfer unit that transfers the created transfer packet to a handover target wireless base station. In a wireless base station that performs wireless communication with a terminal,
When a handover is performed, the transfer packet reception unit for receiving a first transfer packet containing residual data remaining in the handover source base station from the handover source radio base station,
From the transfer packet identification information added to the transfer packet, the forwarding packet, the dummy created for the handover source transmits packets identified as transmission packet undelivered not take delivery confirmation in the radio base station A dummy packet identification unit for identifying whether or not a packet is included;
When the dummy packet is included, a transmission request unit that requests the terminal to transmit a transmission packet corresponding to the dummy packet;
A request packet receiver for receiving the requested transmission packet from the terminal;
An error confirmation unit for confirming whether there is an error in the transmission packet received from the terminal;
A radio base station, comprising: a transmission unit configured to transmit a second transfer packet including the transmission packet received by the request packet reception unit to a host device when there is no error. When wireless communication is performed between the first wireless base station and the terminal, wireless communication is performed between the second wireless base station and the terminal instead of the first wireless base station by handover. In a wireless communication system,
In the first radio base station,
When the residual data remaining in the first radio base station is transferred to the second radio base station, an undelivered MAC PDU whose delivery has not been confirmed from the terminal to the first radio base station is received. An RLC SDU creation unit for creating a dummy MAC PDU and creating an RLC SDU including the MAC PDU and the residual data ;
A transfer unit that transfers the created RLC SDU to the radio base station that is a handover destination;
In the second radio base station,
An RLC SDU receiver for receiving the RLC SDU;
A wireless communication comprising: an undelivered MAC PDU receiver that requests the terminal to transmit a transmission request for the undelivered MAC PDU from the received RLC SDU and receives the undelivered MAC PDU from the terminal. system. In a wireless base station that performs wireless communication with a terminal,
When the remaining data is transferred to the handover destination radio base station when the handover is executed, the MAC PDU transmitted from the terminal is being retransmitted or not yet transmitted without acknowledgment from the terminal. A packet identifier for identifying whether or not the MAC PDU has not been delivered;
A data packet creation unit that creates a dummy MAC PDU for the MAC PDU identified as the undelivered MAC PDU by the packet identification unit, and creates an RLC SDU including the dummy MAC PDU and the residual data ;
A radio base station, comprising: a transfer unit that transfers the created RLC SDU to a radio base station that is a handover destination. In a wireless base station that performs wireless communication with a terminal,
A data packet receiving unit for receiving a MAC SDU including the residual data transferred from the handover source radio base station when residual data remaining in the handover source radio base station is transferred when the handover is performed; ,
From the data packet identification information added to the MAC SDU, a dummy created for the MAC PDU identified as an undelivered MAC PDU that has not been acknowledged in the handover source radio base station. A dummy packet identification unit for identifying whether or not a MAC PDU is included;
When the dummy MAC PDU is included, a transmission request unit that requests the terminal to transmit a MAC PDU corresponding to the dummy MAC PDU;
A request packet receiver for receiving the requested MAC PDU from the terminal;
An error confirmation unit for confirming whether there is an error in the MAC PDU received from the terminal;
A radio base station, comprising: a transmission unit configured to transmit an RLC SDU including the MAC PDU received by the request packet reception unit to a host device when there is no error. When wireless communication is performed between the first wireless base station and the terminal, wireless communication is performed between the second wireless base station and the terminal instead of the first wireless base station by handover. In a wireless communication system,
In the first radio base station,
When the data remaining in the first radio base station is transferred to the second radio base station, out of the transmission packets transmitted from the first radio base station to the terminal, confirmation of delivery from the terminal is performed. Either a dummy packet that has been delivered for a received packet that has been taken, or a dummy packet that has not been delivered to a terminal that has not been delivered to the terminal is created by reading specific pattern data or retransmission data from memory, and a transfer packet creating unit for creating a transfer packet and the dummy packet including said residual data,
A wireless communication system comprising: a transfer unit configured to transfer the created transfer packet to the second wireless base station. In a wireless base station that performs wireless communication with a terminal,
When a handover is performed by the terminal, when transferring the remaining data remaining in the handover destination wireless base station, a transmission packet to be transmitted to the terminal, or delivery already transmitted packet with a good delivery confirmation from the terminal A packet identification unit for identifying an undelivered transmission packet that is being retransmitted or has not been transmitted;
Data or retransmission data of a specific pattern to create a delivery completed dummy packet from the memory to the transmission packet identified as delivered previously transmitted packets by the packet identification unit, the identified transmission packets undelivered the data or retransmission data of a specific pattern to the transmission packet creating a dummy packet reads undelivered from said memory, and transfer the packet creation unit for creating a transfer packet containing any one of the dummy packet and the residual data ,
A wireless base station, comprising: a transfer unit that transfers the created transfer packet to a handover target wireless base station. In a wireless base station that performs wireless communication with a terminal,
When a handover is executed, a transfer packet receiving unit that receives a transfer packet including residual data remaining in the handover source radio base station from the handover source radio base station;
From the transfer packet identification information the added to the forwarded packets, wherein it contains a delivery already dummy packet in the transfer packet, and a dummy packet identifying unit that identifies whether either of the dummy packet undelivered,
A radio base station, comprising: a transmission unit that transmits actual data included in the undelivered dummy packet to the terminal when the undelivered dummy packet is included. When wireless communication is performed between the first wireless base station and the terminal, wireless communication is performed between the second wireless base station and the terminal instead of the first wireless base station by handover. In a wireless communication system,
In the first radio base station,
When transferring data remaining in the first radio base station to the second radio base station, out of MAC PDUs transmitted from the first radio base station to the terminal, confirmation of delivery from the terminal is performed. A dummy MAC PDU that has been delivered to a taken MAC PDU that has been taken, or a dummy MAC PDU that has not been delivered to a transmission MAC PDU that has not been delivered to the terminal is created by reading specific pattern data or retransmission data from the memory. A data packet creation unit for creating an RLC SDU including any dummy MAC PDU and the residual data ;
A transfer unit that transfers the created RLC SDU to the second radio base station;
In the second radio base station,
A data packet receiver for receiving the RLC SDU;
And a packet transmission unit that transmits a MAC PDU corresponding to the undelivered dummy MAC PDU to the terminal when the undelivered dummy MAC PDU is included in the received RLC SDU. Communications system. In a wireless base station that performs wireless communication with a terminal,
When the remaining data is transferred to the handover destination radio base station when the handover is executed, the MAC PDU to be transmitted to the terminal is a MAC PDU that has already been acknowledged and is being retransmitted. Or a packet identifier that identifies undelivered MAC PDUs that have not been transmitted;
For the MAC PDU identified as a MAC PDU that has been delivered by the packet identification unit, a delivered dummy MAC PDU is created by reading a specific pattern of data or retransmission data from the memory and identified as the undelivered MAC PDU. A data packet creation for creating a non-delivered dummy MAC PDU for the MAC PDU by reading data of a specific pattern or retransmission data from the memory and creating an RLC SDU including any dummy MAC PDU and the residual data And
A radio base station, comprising: a transfer unit that transfers the created RLC SDU to a radio base station that is a handover destination. In a wireless base station that performs wireless communication with a terminal,
A data packet receiving unit for receiving RLC SDU including the residual data transferred from the handover source radio base station when residual data remaining in the handover source radio base station is transferred when the handover is performed; ,
A dummy MAC PDU identification unit for identifying whether the RLC SDU includes a delivered dummy MAC PDU or an undelivered dummy MAC PDU from the data packet identification information added to the RLC SDU;
A radio base station comprising: a transmission unit that transmits actual data included in the undelivered dummy MAC PDU to the terminal when the undelivered dummy MAC PDU is included. When wireless communication is performed between the first wireless base station and the terminal, wireless communication is performed between the second wireless base station and the terminal instead of the first wireless base station by handover. In a wireless communication method in a wireless communication system,
In the first radio base station,
When the data remaining in the first radio base station is transferred to the second radio base station, the delivery confirmation is not received among the transmission packets transmitted from the terminal to the first radio base station. create a dummy packet to the transmission packet undelivered, creating a transfer packet containing said dummy packet the residual data,
Transfer the created transfer packet to the radio base station of the handover destination,
In the second radio base station,
Receiving the forwarded packet;
Radio communication method characterized by requesting from said received transfer packet transmission request of the transmission packet of the undelivered to the terminal, receives a transmission packet of the undelivered from the terminal. When wireless communication is performed between the first wireless base station and the terminal, wireless communication is performed between the second wireless base station and the terminal instead of the first wireless base station by handover. In a wireless communication method in a wireless communication system,
In the first radio base station,
When transferring data remaining in the first radio base station to the second radio base station, out of transmission packets transmitted from the first radio base station to the terminal, confirmation of delivery from the terminal is performed. delivery already dummy packets to take delivery already transmitted packets, or to create a dummy packet undelivered to the transmission packet undelivered to the terminal, and a either a dummy packet said residual data Create a forward packet,
Transferring the created transfer packet to the second radio base station;
In the second radio base station,
Receiving the forwarded packet;
A wireless communication method , comprising: transmitting a transmission packet corresponding to the undelivered dummy packet to the terminal when the forward packet received includes the undelivered dummy packet . In the second radio base station,
A transfer packet reception unit that receives the transfer packet,
Claim transmission request of the transmission packet of the undelivered request to the terminal from said received transfer packet, characterized in that the transmission packet of the undelivered and a not-yet-arrived packet receiving unit that receives from the terminal 1 The wireless communication system described. In the second radio base station,
A transfer packet reception unit that receives the transfer packet,
A packet transmission unit that transmits a transmission packet corresponding to the undelivered dummy packet to the terminal when the received transfer packet includes the undelivered dummy packet. The wireless communication system described.

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