JP6174365B2 - Base station and method - Google Patents

Description

  The present invention relates to a wireless communication system.

  In the LTE (Long Term Evolution) system, packet-based wireless communication is used. In such packet-based wireless communication, wireless communication is realized by a plurality of hierarchized layers executing various functions for wireless communication. In the LTE system, it is specified that wireless communication is realized by a layer structure as shown in FIG. As shown in FIG. 1, a PHY (Physical) layer, a MAC (Media Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an RRC (Radio Resource Control layer) are used. .

  Among these, the PDCP layer provides functions such as IP (Internet Protocol) packet concealment processing, falsification detection, and header compression. For the concealment process and the alteration detection, a COUNT value composed of an HFN (Hyper Frame Number) and a PDCP SN (Sequence Number) is used.

  The PDCP SN is incremented every time a PDCP packet is transmitted from the PDCP layer to the RLC layer, and a PDCP SN in a range from “0” to “4095” is cyclically given to the PDCP packet. For example, the sequence number “0” is assigned to the PDCP packet transmitted to the RLC layer next to the PDCP packet with the sequence number “4095”. The HFN is incremented every time the PDCP SN circulates, and an HFN ranging from “0” to “1048576” is added to the PDCP packet. The COUNT value is configured to have HFN in the upper bits and PDCP SN in the lower bits. In the LTE system, only the PDCP SN of the COUNT value is transmitted to the receiving side, and the HFN is not transmitted. For this reason, the receiving side needs to estimate the HFN of the received packet from the reception status.

  To summarize the operation of the PDCP layer, on the transmitting side, the PDCP entity performs confidential processing, falsification detection, and header compression on a packet received from an upper layer, that is, a PDCP SDU (Service Data Unit) using a COUNT value. The packet is transmitted to the RLC layer as a PDCP packet, that is, a PDCP PDU (Packet Data Unit) with the PDCP SN added to the header.

  On the other hand, on the receiving side, as shown in FIG. 2, the PDCP entity manages a reception window for correcting the order of received packets. In the LTE system, the size of the reception window is set to 2047 which is 1/2 of the upper limit value “4095” of PDCP SN. When the PDCP SN of the packet received from the transmission side is within the range of the reception window, the PDCP entity estimates the HFN used for the decryption process of the packet from the current reception status, and the estimated HFN and the PDCP SN of the header The deciphering process is executed on the received packet based on the COUNT value constituted by: Thereafter, the PDCP entity sends the processed packet to the upper layer and updates the reception window. On the other hand, if the PDCP SN of the packet received from the transmission side is outside the range of the reception window, the PDCP entity discards the packet.

3GPP TS 36.323 V8.6.0 (2009-06)

  In a base station (evolved NodeB: eNB) that receives a packet addressed to a user apparatus (User Equipment: UE) from a network device, the PDCP / RLC packet is discarded at a predetermined discard timing. For example, when the PDCP / RLC SDU in the buffer of the base station stays more than a threshold, the base station discards the PDCP / RLC SDU from the buffer. For voice data packets that require real-time performance, the base station uses a timer (Discard Timer) for measuring the dwell time. When the timer expires, the PDCP / RLC SDU is discarded from the buffer. To do. Note that PDCP / RLC SDUs that have already been mapped to transport blocks, that is, PDCP / RLC SDUs that are stored in MAC PDUs to generate transport blocks are not subject to discarding.

  In this way, when a large number of PDCP / RLC SDUs are continuously discarded due to a predetermined destruction trigger in the base station, the user apparatus cannot appropriately update the reception window, and the HFN is between the PDCP layers of the eNB-UE. This mismatch will occur. When an HFN mismatch occurs, the UE fails in the concealment process and cannot normally extract the PDCP SDU. As shown in FIG. 3, for example, in the base station on the transmitting side, PDCP packets from HCP “0” PDCP SN “0” to “4095” are continuously discarded, and HFN “1” PDCP SN ”. It is assumed that PDCP packets from “0” to “2” are transmitted to the user device on the receiving side. In this case, the user apparatus misidentifies the received PDCP packet as a PDCP packet from PDCP SN “0” to “2” of HFN “0”, and an HFN mismatch occurs.

  In view of the above problems, an object of the present invention is to provide a technique for avoiding a mismatch of HFN between a base station and a user apparatus due to continuous discard of packets.

  In order to solve the above-described problem, one aspect of the present invention is to transmit and receive a packet between a network device and a user device, store a packet received from the network device, and respond to a predetermined packet discard event. Then, using the packet management unit for discarding the stored packet and a count value having a sequence number and a hyperframe number for each packet, PDCP (Packet Data Convergence Protocol for the stored packet) ) PDCP layer processing unit that executes layer processing and generates a PDCP packet by assigning a sequence number related to the processed packet to the processed packet, and continuous packet discarding that continuously discards the stored packet In response to an event Window update for generating a window update packet for causing the user apparatus to update a reception window for processing in the PDCP layer of the user apparatus, and instructing the transmission / reception unit to transmit the generated window update packet to the user apparatus The present invention relates to a base station having a packet generator.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to avoid the mismatch of HFN between the base station and user apparatus accompanying the continuous discard of a packet.

FIG. 1 is a schematic diagram illustrating a layer structure in LTE. FIG. 2 is a schematic diagram illustrating an example operation in the PDCP layer. FIG. 3 is a schematic diagram showing a specific example of HFN mismatch. FIG. 4 is a schematic diagram illustrating a wireless communication system according to an embodiment of the present invention. FIG. 5 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention. FIG. 6 is a schematic diagram illustrating non-discarded packets according to an embodiment of the present invention. FIG. 7 is a flowchart showing packet transmission processing in the base station according to one embodiment of the present invention.

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

  In summary of an embodiment of the present invention described later, when PDCP packets are continuously discarded in a base station, the base station updates a window update packet for updating a reception window of a user apparatus so as to maintain HFN consistency. Is transmitted to the user device. When receiving the window update packet, the user apparatus receives the window update packet having a PDCP SN within the range of the reception window, and updates and shifts the currently set reception window according to the received window update packet. As a result, it is possible to avoid occurrence of HFN mismatch between the base station and the user apparatus due to a continuous packet discard event in the base station.

  The window update packet according to one embodiment is generated from a part of packets (non-discarded packets) that are maintained in the buffer without being discarded. That is, when a packet continuous discard event that continuously discards stored packets such as PDCP / RLC SDUs occurs, the base station has a PDCP SN corresponding to the size of the reception window of the user apparatus that is sequentially updated. A non-discarded packet is selected, a window update packet is generated from the selected non-discarded packet and transmitted to the user apparatus. In this way, the user equipment can update or shift the reception window by receiving a window update packet having a PDCP SN within the currently set reception window and the sequentially updated reception window. become.

  The window update packet according to another embodiment is generated as a dummy packet that has no actual data and has a header having a sequence number within the range of the reception window. That is, when a packet continuous discard event that continuously discards stored packets such as PDCP / RLC SDU occurs, the base station discards the stored packets and has a PDCP SN within the range of the reception window. A dummy packet is generated, and the dummy packet is transmitted to the user apparatus as a window update packet. In this way, the user equipment can update or shift the reception window by receiving a window update packet having a PDCP SN within the currently set reception window and the sequentially updated reception window. become.

  First, a radio communication system according to an embodiment of the present invention will be described with reference to FIG. In the embodiment described later, the wireless communication system is an LTE system, but the present invention is not limited to this. The present invention can be applied to any other wireless communication system having a layer structure similar to the LTE system, such as an LTE-Advanced system.

  FIG. 4 is a schematic diagram illustrating a wireless communication system according to an embodiment of the present invention. As illustrated in FIG. 4, the wireless communication system 10 includes a base station (eNB) 100, one or more user apparatuses (UE) 200, a network apparatus 300, and a network 400.

  The base station 100 wirelessly connects to the user apparatus 200, thereby transmitting a downlink (DL) packet received from the network apparatus 300 such as a host station or a server connected to the network 400 to the user apparatus 200. The uplink (UL) packet received from the user device 200 is transmitted to the network device 300.

  In the PDCP layer, the base station 100 executes concealment processing, falsification detection, header compression, and the like on the PDCP SDU received from the upper layer, and transmits the PDCP packet generated as the PDCP PDU to the RLC layer. A COUNT value composed of HFN and PDCP SN is used for concealment processing and falsification detection. The PDCP SN is incremented every time a PDCP packet is transmitted from the PDCP layer to the RLC layer, and a PDCP SN in a range from “0” to “4095” is cyclically given to the PDCP packet. The HFN is incremented every time the PDCP SN circulates, and an HFN ranging from “0” to “1048576” is added to the PDCP packet. The COUNT value is configured to have HFN in the upper bits and PDCP SN in the lower bits. In the LTE system, only the PDCP SN is described in the header of the PDCP packet and notified to the receiving side. On the other hand, the HFN is not described in the PDCP packet, and the receiving side needs to estimate the HFN for performing the deciphering process on the received packet based on the reception status and the PDCP SN.

  In addition, the base station 100 temporarily stores the packet addressed to the user apparatus 200 received from the network apparatus 300 in the buffer, and discards the packet staying in the buffer in response to a predetermined discard event. For example, if the PDCP / RLC SDU in the buffer of the base station 100 stays above the threshold, the base station 100 discards the PDCP / RLC SDU from the buffer. For voice data packets that require real-time performance, the base station 100 uses a timer (Discard Timer) for measuring the dwell time, and when the timer expires, the PDCP / RLC SDU is read from the buffer. Discard. Note that PDCP / RLC SDUs that have already been mapped to transport blocks, that is, PDCP / RLC SDUs that are stored in MAC PDUs to generate transport blocks are not subject to discarding.

  In a typical hardware configuration, the base station 100 wirelessly communicates with a CPU (Central Processing Unit) such as a processor, a memory device such as a RAM (Random Access Memory), an auxiliary storage device such as a hard disk device, and the user device 200. The wireless communication apparatus includes a wireless communication apparatus for transmitting and receiving signals, an interface apparatus for exchanging various data and / or various instructions with the network apparatus 300 via the network 400, and the like. For example, each function and process of the base station 100 to be described later is performed by loading data or a program stored in the auxiliary storage device into the memory device, and via the wireless communication device and / or the interface device according to the loaded program. This is realized by processing the acquired data.

  Typically, the user apparatus 200 may be any appropriate information processing apparatus having a wireless communication function such as a mobile phone, a smartphone, a tablet, and a mobile router as illustrated. The user apparatus 200 manages a reception window for correcting the order of received packets in the PDCP layer. In the LTE standard specification, the size of the reception window is set to 2047 which is ½ of the upper limit value “4095” of PDCP SN. When the PDCP SN of the packet received from the base station 100 is within the range of the window, the user apparatus 200 estimates the HFN used for the packet deciphering process based on the current reception status in the PDCP layer, and the estimated HFN And a decipher process on the received packet based on the COUNT value composed of the PDCP SN assigned to the header. After executing the PDCP layer processing, the user apparatus 200 updates or shifts the reception window. On the other hand, when the PDCP SN of the packet received from the base station 200 is outside the range of the reception window, the user apparatus 200 discards the packet.

  The network device 300 is a service provider server on the network 400, a management node for managing the base station 100 and the user device 200, or the like. The network device 300 transmits various data to be provided to the user device 200 to the base station 100.

  The network 400 is an operator network of the wireless communication system 10 or the Internet. Base station 100 and network device 300 exchange IP packets via network 400.

  Next, with reference to FIGS. 5-6, the structure of the base station by one Example of this invention is demonstrated. FIG. 5 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention.

  As illustrated in FIG. 5, the base station 100 includes a transmission / reception unit 110, a packet management unit 120, a PDCP layer processing unit 130, and a window update packet generation unit 140.

  The transmission / reception unit 110 transmits and receives packets between the network device 300 and the user device 200. Specifically, in order to convert the IP packet received from the network device 300 into a wireless signal addressed to the user device 200, the transmission / reception unit 110 performs various wireless processes such as an encoding process, a modulation process, and a multiplexing process, The generated radio signal is transmitted to the user apparatus 200. In addition, the transmission / reception unit 110 generates and generates various radio processes such as a decoding process, a demodulation process, and a demultiplexing process in order to convert a radio signal received from the user apparatus 200 into an IP packet addressed to the network apparatus 300. The IP packet is transmitted to the network device 300.

  The packet management unit 120 stores the packet received from the network device 300, and discards the stored packet in response to a predetermined packet discard event. Specifically, the packet management unit 120 stores PDCP SDUs provided from higher layers in a buffer, and provides the stored PDCP SDUs to the PDCP layer processing unit 130. Further, when detecting a predetermined discard event, the packet management unit 120 discards the packet staying in the buffer. The discard event may be, for example, that the number of PDCP SDU packets stays in the buffer more than a threshold, or that a timer (Discard Timer) for counting the stay time has passed for a predetermined time. When it is detected that any discard event has occurred, the packet management unit 120 discards the PDCP SDU from the buffer. Note that a PDCP SDU that has already been mapped to a transport block, that is, a PDCP SDU that is stored in a MAC PDU to generate a transport block may be excluded from discarding.

  In one embodiment, in response to a continuous packet discard event that continuously discards packets stored in the buffer, the packet management unit 120 corresponds to the size of the reception window of the user apparatus 200 from the stored packets. The non-discarded packet may be selected and the selected non-discarded packet may be maintained in the buffer without being discarded. The maintained non-discarded packet is used for generating a window update packet. That is, the window update packet generation unit 140 may generate a window update packet from the selected non-discarded packet and instruct the transmission / reception unit 110 to transmit the generated window update packet to the user apparatus 200. As described above, in this embodiment, when a packet continuous discard event is detected, the packet management unit 120 selects a part of the stored packet as a packet not subject to discard so that the reception window of the user apparatus 200 is sequentially updated. Then, the selected non-discarded packet is kept in the buffer without being discarded. The window update packet generation unit 140 generates a window update packet for causing the user apparatus 200 to update a reception window for processing in the PDCP layer of the user apparatus 200 using the non-discarded packet, and generates the generated window Instructs the transmission / reception unit 110 to transmit the update packet. As a result, the user apparatus 200 receives a window update packet having a PDCP SN within the range of the reception window in each reception window that is sequentially updated, and the reception window that is consistent with the HFN in the base station 100 is updated. It becomes possible.

  For example, the packet management unit 120 first selects at least one packet from among packets having a PDCP SN within the range of the reception window currently set in the user apparatus 200 as a non-discarded packet. Further, the packet management unit 120 selects a packet having a PDCP SN corresponding to the window end position of the reception window with the selected non-discarded packet as the window start position as the next non-discarded packet. Thereafter, the packet management unit 120 selects a packet having a PDCP SN corresponding to the window end position of the reception window updated when the user apparatus 200 receives the non-discarded packet as a further non-discardable packet. Thereafter, the subsequent non-discarded packets are selected according to the same procedure. In this way, the packet management unit 120 maintains the PDCP SDU having the PDCP SN within the range of the reception window that is sequentially updated in the buffer as a packet not to be discarded so that the reception window of the user apparatus 200 is sequentially updated. To do.

  As an example of selection of such a packet that is not to be discarded, the packet management unit 120 identifies and identifies the packet that is transmitted first among the packets that are waiting for a delivery confirmation ACK for the packet that has already been transmitted to the user apparatus 200. The packet corresponding to the window end position of the reception window having the received packet as the window start position and each packet corresponding to the window end position of the reception window that is sequentially updated may be selected as non-discarded packets. Specifically, since the size of the reception window is defined as 2047 in the LTE standard specifications, the packet management unit 120 is first in the packets waiting for delivery confirmation for the packets already transmitted to the user apparatus 200. When the COUNT value of the transmitted packet is X, each packet having a COUNT value of X + 2047, X + 2047 + 1 × 2048, X + 2047 + 2 × 2048,..., X + 2047 + n × 2048 may be selected as a non-discarded packet. That is, as illustrated in FIG. 6, the packet management unit 120 firstly transmits a packet (COUNT value “X” in FIG. 6) among the packets that are waiting for delivery confirmation for the packet that has already been transmitted to the user apparatus 200. Identify "packets". Next, the packet management unit 120 receives the packet corresponding to the window end position of the reception window (the packet having the COUNT value “X + 2047” in FIG. 6) and the non-discarded packet that have the specified packet as the window start position. Thus, each packet (COUNT value “X + 4095”, “X + 6143”, etc. in FIG. 6) corresponding to the end position of the reception window that is sequentially updated may be selected as a packet not to be discarded. According to the selection method, since the non-discarded packet corresponding to the window end position of each reception window that is sequentially updated is transmitted to the user apparatus 200, the reception windows before and after the update are not overlapped and separated in the user apparatus 200. It is possible to maintain HFN consistency with a minimum number of non-discarded packets.

  In the above-described embodiment, the packet management unit 120 sets the COUNT value of the packet transmitted first among the packets waiting for delivery confirmation to the packet already transmitted to the user apparatus 200 as X. The packet corresponding to the COUNT value “X” is not limited to this. The packet corresponding to the COUNT value “X” may be any other appropriate packet.

  Note that when the base station 100 receives a delivery confirmation ACK from the user apparatus 200 for the packet transmitted first in the above-described packets waiting for delivery confirmation for the already transmitted packet, the COUNT value “X” is updated. Is done. However, even in this case, a packet once maintained as not subject to discarding is maintained as a packet not subject to discarding regardless of the update of the COUNT value “X” in the packet management unit 120. This is because each packet having COUNT values of new X + 2047, X + 2047 + 1 × 2048, X + 2047 + 2 × 2048,..., X + 2047 + n × 2048 corresponding to the updated COUNT value “X” may have already been discarded. It is because there is sex. That is, even if the transmission / reception unit 110 receives a delivery confirmation for the packet transmitted first among the packets waiting for the delivery confirmation for the packet already transmitted from the user apparatus 200, the packet management unit 120 does not change the COUNT before the update. The non-discarded packet selected based on the value may continue to be used.

  In the embodiment described above, some packets are maintained in the buffer as non-discarded packets. However, when a large amount of data addressed to a specific user device 200 flows from the network device 300, a large amount of non-discarded packets stays in the buffer. For this reason, when a packet that is not subject to discarding stays to some extent, it is also necessary to discard the packet. However, when the packet management unit 120 discards the non-discarded packet from the buffer, the user apparatus 200 fails in the deciphering process for the packet transmitted to the user apparatus 200 thereafter. For this reason, the packet management unit 120 may instruct the transmission / reception unit 110 to release the bearer established with the user apparatus 200 when the selected non-discarded packets stay for a predetermined threshold or more. The threshold value may be set for the number of packets staying with respect to the bearer (or user), or may be set for the data staying amount. As a specific example of the procedure for releasing the bearer, the transmission / reception unit 110 may transmit an RRC connection release to the user apparatus 200, or may release the call for the user apparatus 200, or may be full. You may reset all the bearers about the user apparatus 200 by configuration. It should be noted that when the bearer is released, the release may be notified to the user by an output method such as a display or a speaker.

  The PDCP layer processing unit 130 performs PDCP layer processing on the stored packets using a count value having a sequence number and a hyperframe number for each packet, and adds the packet to the processed packet. A PDCP packet is generated by assigning a sequence number related to. The PDCP layer processing unit 130 executes the above-described concealment processing, alteration detection, header compression, and the like in the PDCP layer. A COUNT value composed of HFN and PDCP SN is used for concealment processing and falsification detection.

  The PDCP SN is incremented every time a PDCP packet is transmitted from the PDCP layer to the RLC layer, and a PDCP SN in a range from “0” to “4095” is cyclically given to the PDCP packet. The HFN is incremented every time the PDCP SN circulates, and an HFN ranging from “0” to “1048576” is added to the PDCP packet. The PDCP layer processing unit 130 performs concealment processing, falsification detection, and header compression on the PDCP SDU received from the upper layer using the COUNT value, and assigns the PDCP SN to the header as a PDCP packet (PDCP PDU). Send to RLC layer.

  The window update packet generation unit 140 generates a window update packet for causing the user device 200 to update the reception window of the user device 200 in response to the continuous packet discard event, and transmits the generated window update packet to the user device 200. The transmission / reception unit 110 is instructed to do so.

  In one embodiment, as described above, when the packet management unit 120 maintains a non-discarded packet, the window update packet generator 140 generates a window update packet from the maintained non-discarded packet, The transmission / reception unit 110 may be instructed to transmit the generated window update packet to the user apparatus 200. Similarly to the PDCP packet generated by the PDCP layer processing unit 130, the window update packet generates a PDCP packet with the PDCP SN related to the non-discarded packet added to the header, and sends the generated PDCP packet to the RLC layer.

  In another embodiment, in response to the continuous packet discard event, the packet management unit 120 may discard the stored packet without setting the non-discard packet, and the window update packet generation unit 140 A dummy packet having a sequence number within the range of the reception window of the user apparatus 200 may be generated, and the transmission / reception unit 110 may be instructed to transmit the generated dummy packet to the user apparatus 200 as a window update packet. The dummy packet may be a PDCP packet including only a header having a sequence number within the range of the reception window, or may be a PDCP packet based on an invalid upper packet (for example, an IP packet). According to the present embodiment, it is possible to update the reception window consistent with HFN in the base station 100 without having to maintain the non-discarded packets as described above.

  In this case, for example, the packet management unit 120 manages the COUNT value Y of the PDCP PDU last mapped to the MAC PDU, and determines whether 2047 PDCP PDUs associated with the COUNT values after Y are continuously discarded. Thus, a packet continuous discard event may be detected. When the packet continuous discard event is detected, the packet management unit 120 specifies the count value related to the PDCP packet that is finally mapped to the MAC packet, and the window update packet generation unit 140 sets the reception window to the specified count value. The dummy packet may be generated so as to have a count value obtained by adding the sizes of. Specifically, the window update packet generation unit 140 may generate a dummy packet having a COUNT value of Y + 2047, and instruct the transmission / reception unit 110 to transmit the generated dummy packet to the user apparatus 200 as a window update packet. .

  Next, with reference to FIG. 7, the packet transmission process of the base station according to an embodiment of the present invention will be described. FIG. 7 is a flowchart showing packet transmission processing of the base station according to one embodiment of the present invention.

  As shown in FIG. 7, in step S101, the base station 100 detects a continuous packet discard event for continuously discarding packets stored in the buffer. For example, when the base station 100 detects that the number of PDCP SDU packets stays in the buffer at a threshold value or more, or detects that a predetermined time has elapsed for a timer for counting the stay time, the base station 100 determines that a continuous packet discard event has occurred. May be.

  In one embodiment, when a packet continuous discard event is detected, the base station 100 selects a packet that is not subject to discarding from the stored packets according to the size of the reception window of the user apparatus 200, and the selected packet that is not subject to discarding May be maintained in a buffer. In another embodiment, upon detecting a continuous packet discard event, the base station 100 may simply discard the stored packet.

  In step S102, the base station 100 generates a window update packet for causing the user apparatus 200 to update a reception window for processing in the PDCP layer of the user apparatus 200. When the non-discarded packet is maintained in step S101, the base station 100 may generate a window update packet from the non-discarded packet. Further, when the packet not to be discarded is not maintained in step S101, the base station 100 may generate a dummy packet having a sequence number within the range of the reception window of the user apparatus 200 as the window update packet.

  In step S103, the base station 100 transmits the generated window update packet to the user apparatus 200. When receiving the window update packet, the user apparatus 200 updates or shifts the currently set reception window.

  In step S104, the base station 100 determines whether the packet continuous discard event has ended. For example, when the base station 100 detects that the number of PDCP SDU packets staying in the buffer has dropped below a threshold value or that the timer for measuring the stay time has been reset, the packet continuous discard event has ended. You may judge. When the packet continuous discard event ends (step S104: Y), the flow proceeds to step S105. Otherwise (step S104: N), the flow returns to step S102 to generate and transmit the window update packet described above. repeat.

  In step S105, the base station 100 ends the generation of the window update packet and restarts the PDCP layer process.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the specific embodiment mentioned above, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

10 wireless communication system 100 base station 110 transmission / reception unit 120 packet management unit 130 PDCP layer processing unit 140 window update packet generation unit

Claims (7)

A transmission / reception unit for transmitting and receiving packets between the network device and the user device;
A packet management unit that stores packets received from the network device and discards the stored packets in response to a predetermined packet discard event;
Using a count value having a sequence number and a hyperframe number for each packet, PDCP (Packet Data Convergence Protocol) layer processing is executed for the stored packet, and the packet is processed as a packet after processing. A PDCP layer processing unit that generates a PDCP packet by assigning a sequence number according to
In response to a packet continuous discard event that continuously discards the stored packets, a window update packet for causing the user apparatus to update a reception window for processing in the PDCP layer of the user apparatus is generated. A window update packet generator that instructs the transceiver to transmit the generated window update packet to the user device;
A base station having a,
In response to the continuous packet discard event, the packet management unit identifies the packet transmitted first among the packets waiting for delivery confirmation for the packet that has already been transmitted to the user apparatus, and identifies the identified packet. A base station that selects a packet corresponding to a window end position of the reception window as a window start position and each packet corresponding to a window end position of the reception window that is sequentially updated as a packet not to be discarded . Even if the transmission / reception unit receives a delivery confirmation for the specified packet from the user device, the packet management unit includes a packet corresponding to a window end position of the reception window, where the specified packet is a window start position; utilizing each packet corresponding to the window end position of the reception window is sequentially updated as the discard eligible packets, the base station according to claim 1. The packet managing unit, discard eligible packets said selected is the stays above a predetermined threshold, instructs the transceiver to release the bearer is established between the user equipment, according to claim 1 or 2 The listed base station. A transmission / reception unit for transmitting and receiving packets between the network device and the user device;
A packet management unit that stores packets received from the network device and discards the stored packets in response to a predetermined packet discard event;
Using a count value having a sequence number and a hyperframe number for each packet, PDCP (Packet Data Convergence Protocol) layer processing is executed for the stored packet, and the packet is processed as a packet after processing. A PDCP layer processing unit that generates a PDCP packet by assigning a sequence number according to
In response to a packet continuous discard event that continuously discards the stored packets, a window update packet for causing the user apparatus to update a reception window for processing in the PDCP layer of the user apparatus is generated. A window update packet generator that instructs the transceiver to transmit the generated window update packet to the user device;
A base station having
In response to the continuous packet discard event, the packet management unit discards the stored packet,
The window update packet generation unit generates a dummy packet having a sequence number within the range of the receive window, that instructs the dummy packet the generated to the transmitting and receiving unit to transmit to the user device as the window update packet based on Chikyoku. In response to the continuous packet discard event, the packet management unit specifies a count value related to a PDCP packet that is finally mapped to a MAC (Media Access Control) packet,
The base station according to claim 4 , wherein the window update packet generation unit generates the dummy packet to have a count value obtained by adding a size of the reception window to the specified count value. A method in a base station for transmitting a packet to a user equipment comprising:
Detecting a packet continuous discard event for continuously discarding packets stored in the base station;
Generating a window update packet for causing the user equipment to update a reception window for processing in the PDCP layer of the user equipment;
Transmitting the generated window update packet to the user equipment;
Resuming PDCP layer processing upon completion of the continuous packet discard event;
A method comprising :
In response to the continuous packet discard event, the packet that has been transmitted first among the packets waiting for delivery confirmation for the packet that has already been transmitted to the user apparatus is identified, and the identified packet is set as the window start position. The method further comprising: selecting a packet corresponding to the window end position of the reception window and each packet corresponding to the window end position of the reception window, which is sequentially updated, as a packet not to be discarded . A method in a base station for transmitting a packet to a user equipment comprising:
Detecting a packet continuous discard event for continuously discarding packets stored in the base station;
Generating a window update packet for causing the user equipment to update a reception window for processing in the PDCP layer of the user equipment;
Transmitting the generated window update packet to the user equipment;
Resuming PDCP layer processing upon completion of the continuous packet discard event;
A method comprising:
Detecting the continuous packet discard event includes discarding the stored packet;
It said window generating an update packet, including METHODS generating a dummy packet having a sequence number within the range of the receive window as the window update packet.

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