JP6107943B2 - COMMUNICATION SYSTEM, TERMINAL DEVICE, AND COMMUNICATION METHOD - Google Patents

Description

  The present invention relates to a communication system, a terminal device, and a communication method.

  In a communication system having a base station apparatus (hereinafter sometimes referred to as “base station”) and a terminal apparatus (hereinafter sometimes referred to as “terminal”), MTC (Machine Type Communication) has recently been introduced as a new terminal. Terminals are attracting attention. As an example of the MTC terminal, for example, a smart meter which is a power meter having a wireless communication function, a vending machine having a wireless communication function, a sensor having a wireless communication function, and the like can be given. A smart meter having a wireless communication function transmits, for example, measured power consumption data to the base station. The vending machine having a wireless communication function transmits, for example, sales information, inventory information in the vending machine, and the like to the base station. Further, as a sensor having a wireless communication function, a GPS (Global Positioning System) sensor having a wireless communication function can be cited, and this GPS sensor transmits user's current position information to a base station.

  Here, since the MTC terminal transmits / receives the specific data (information) as described above, compared to a general terminal (for example, a smartphone) that transmits / receives various types of data, the type of data desired as a communication target, And the amount of data is small. That is, in the MTC terminal, “small size user data” (hereinafter sometimes referred to as “small data”) such as measurement data is intermittently transmitted and received in relatively many cases.

  Further, when an MTC terminal in the idle mode (standby state) performs transmission / reception of small data, many control messages are exchanged with the base station in order to establish a communication connection (that is, to shift to the connection mode). . Since the amount of small data is small, if a large number of control messages are exchanged when establishing a communication connection for small data, the overhead of the control messages increases, which is not preferable from the viewpoint of efficiency of using communication resources.

  Therefore, in order to reduce the exchange of control messages, even when the MTC terminal is in the idle mode, the radio bearer (DRB: Data Radio Bearer) for data signal that has already been set is maintained without being released. There is prior art.

3GPP TR23.887 V0.8.0

  Here, in order to increase the utilization efficiency of communication resources, it is conceivable to compress the header added to the small data. The header compression is performed, for example, by omitting the second and subsequent transmissions of a field whose contents are always constant among a plurality of fields included in the header. Information indicating which of the plurality of fields included in the header is always constant and does not change is notified in advance from the transmission side to the reception side. Therefore, the receiving side can restore the field from which the second and subsequent transmissions are omitted by using the header received first time and the information notified in advance.

  However, when an MTC terminal in the idle mode moves between base stations (reselects a cell), information held by the base station before movement is not taken over by the destination base station. For this reason, each time the MTC terminal in the idle mode moves between base stations, the information used for decompression of the compressed header (for example, information indicating a field whose contents are always constant and does not change) is transferred to the destination base station. You must notify the station again. Therefore, even when the MTC terminal is in the idle mode, the overhead of information used for decompression of the compressed header is increased if movement between base stations is performed without releasing the DRB.

  The disclosed technology has been made in view of the above, and an object thereof is to provide a communication system, a terminal device, and a communication method that can reduce the overhead of information used for decompression of a compressed header.

  In the disclosed aspect, a terminal device that transmits user data to a base station in a random access procedure that is executed in response to occurrence of uplink user data uses random information that is used for decompression of a compressed header added to the user data. Notify the network controller before starting the access procedure.

  According to the aspect of an indication, the overhead of the information used for decompression | restoration of a compression header can be reduced.

FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment. FIG. 2 is a block diagram illustrating an example of a terminal according to the first embodiment. FIG. 3 is a block diagram illustrating an example of the base station according to the first embodiment. FIG. 4 is a diagram illustrating an example of the MME according to the first embodiment. FIG. 5 is a diagram illustrating an example of a header field configuration according to the first embodiment. FIG. 6 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. FIG. 7 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. FIG. 8 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. FIG. 9 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. FIG. 10 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. FIG. 11 is a diagram illustrating a hardware configuration example of the terminal. FIG. 12 is a diagram illustrating a hardware configuration example of the base station. FIG. 13 is a diagram illustrating a hardware configuration example of the MME.

  Hereinafter, embodiments of a communication system, a terminal device, and a communication method disclosed in the present application will be described with reference to the drawings. In addition, the communication system, the terminal device, and the communication method disclosed in the present application are not limited by this embodiment. Moreover, the same code | symbol is attached | subjected to the structure which has the same function in each Example, and the step which performs the same process, and the overlapping description is abbreviate | omitted. In the following, a case where the communication system is an LTE (Long Term Evolution) system and an LTE-A (LTE-Advanced) system in 3GPP (3rd Generation Partnership Project) will be described as an example. is not.

[Example 1]
<Outline of communication system>
FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment. In FIG. 1, the communication system 1 includes a terminal 10, a base station 20, an MME (Mobility Management Entity) 30, and an S-GW (Serving-Gateway) 40. The MME 30 is a network control device. A C-plane path through which control messages are exchanged is set between the base station 20, the MME 30, and the S-GW 40. A U-plane path through which user data is exchanged is set between the base station 20 and the S-GW 40. The terminal 10 is an MTC terminal, and therefore the data transmitted and received by the terminal 10 is small data. In this embodiment, a case where small data is transmitted with a control message using C-plane instead of U-plane will be described as an example.

  Also, under the MME 30, there are a plurality of base stations 20 including a base station to which the terminal 10 is connected (that is, a serving base station). The terminal 10 transmits information used for decompression of the compressed header to the base station 20 to which the terminal 10 is connected among the plurality of base stations 20. On the other hand, the MME 30 uses the base station to which the terminal 10 is connected and a plurality of base stations around the connected base station (for example, tracking in which the terminal 10 is located) as information used for decompression of the compressed header. Including the base stations in the area) to all the base stations 20 under the MME 30 at the same time. Note that the MME 30 may notify information used for decompression of the compressed header to all the base stations 20 under the MME 30 or only to a plurality of base stations 20 around the terminal 10. .

<Example of terminal configuration>
FIG. 2 is a block diagram illustrating an example of a terminal according to the first embodiment. In FIG. 2, a terminal 10 that is an MTC terminal includes a transmission unit 11, an antenna 12, a reception unit 13, and a control information processing unit 14.

  The user data input to the control information processing unit 14 is small data. The control information processing unit 14 forms information used for decompression of the compressed header (hereinafter may be referred to as “header information”). The contents of the header information will be described later. Further, the control information processing unit 14 compresses the header using the header information to form a compressed header. Further, the control information processing unit 14 forms various control messages and outputs them to the transmission unit 11. The formation of the control message in the control information processing unit 14 may be performed according to the control message input from the receiving unit 13. In addition, the control information processing unit 14 adds the small data or the header information to which the compressed header is added to the specific control message and outputs it to the transmission unit 11.

  The transmission unit 11 transmits the small data to which the header information, the control message, and the compressed header are added to the base station 20 via the antenna 12 via the uplink.

  The receiving unit 13 receives the control message transmitted from the base station 20 via the antenna 12 on the downlink and outputs the control message to the control information processing unit 14.

<Configuration example of base station>
FIG. 3 is a block diagram illustrating an example of the base station according to the first embodiment. In FIG. 3, the base station 20 includes an antenna 21, a reception unit 22, an eNB communication control unit 23, a network IF (interface) 24, a transmission unit 25, and a storage unit 26.

  The receiving unit 22 receives the header information, the control message, and the small data added with the compressed header transmitted from the terminal 10 via the uplink via the antenna 21 and outputs the small data to the eNB communication control unit 23.

  The eNB communication control unit 23 forms various control messages and outputs them to the transmission unit 25 or the network IF 24. The formation of the control message in the eNB communication control unit 23 may be performed according to a control message input from the reception unit 13 or a control message input from the network IF 24. Further, the eNB communication control unit 23 stores the header information in the storage unit 26 together with the identifier of the terminal 10. In addition, the eNB communication control unit 23 restores the compressed header added to the small data using the header information. In addition, the eNB communication control unit 23 outputs small data to which the header information input from the reception unit 22 and the restored header (hereinafter sometimes referred to as “restored header”) are added to the network IF 24.

  The storage unit 26 stores header information in association with the identifier of each of the plurality of terminals 10.

  The transmission unit 25 transmits the control message input from the eNB communication control unit 23 to the terminal 10 via the antenna 21 on the downlink.

  The network IF 24 is connected to the MME 30 via a C-plane path, transmits small data to which header information, a control message, and a restoration header are added to the MME 30 and receives a control message from the MME 30. The network IF 24 is connected to the S-GW 40 via a U-plane path.

<Configuration example of MME>
FIG. 4 is a block diagram illustrating an example of the MME according to the first embodiment. 4, the MME 30 includes a network IF 31, an MME communication control unit 32, a storage unit 33, and a network IF 34.

  The network IF 31 is connected to the base station 20 through a C-plane path, receives small information to which header information, a control message, and a restoration header are added from the base station 20 and outputs the small data to the MME communication control unit 32. Further, the network IF 31 transmits a control message input from the MME communication control unit 32 to the base station 20.

  The MME communication control unit 32 forms various control messages and outputs them to the network IF 31 or the network IF 34. The formation of the control message in the MME communication control unit 32 may be performed according to a control message input from the network IF 31 or the network IF 34. In addition, the MME communication control unit 32 stores the header information in the storage unit 33 together with the identifier of the terminal 10. Further, the MME communication control unit 32 outputs the small data input from the network IF 31 to the network IF 34.

  The storage unit 33 stores header information in association with the identifier of each of the plurality of terminals 10.

  The network IF 34 is connected to the S-GW 40 via a C-plane path, transmits a control message and small data to which a restoration header is added, to the S-GW 40, and receives a control message from the S-GW 40.

<Header field configuration example>
FIG. 5 is a diagram illustrating an example of a header field configuration according to the first embodiment. FIG. 5 shows a field configuration of RTP / UDP / IP (Real-time Transport Protocol / User Datagram Protocol / Internet Protocol) v4 as an example. As shown in FIG. 5, the header includes a plurality of fields. Among the plurality of fields shown in FIG. 5, the field indicated by the underline of the straight line is a field whose contents are always constant and does not change, that is, a field that does not change. The field indicated by the underline of the wavy line is a field that can be calculated from the values of other fields. In addition, a field not underlined is a field whose value changes for each small data (for each packet).

  The header information includes at least one of information indicating an invariable field among the plurality of fields and information indicating a field that can be calculated from values of other fields. The terminal 10 can compress the header by omitting the unchanged field from the header from the second transmission onward by including information indicating the unchanged field in the header information. In addition, the terminal 10 can compress the header by omitting the field that can be calculated from the value of the other field from the header by including information indicating the field that can be calculated from the value of the other field in the header information. Then, the base station 20 can specify the fields that are invariable and the fields that can be calculated from the values of other fields using the header information, and restore these fields. That is, the base station 20 can restore the compressed header from which the invariant field is omitted using the uncompressed header and the header information. Further, the base station 20 can restore the compressed header from which the field that can be calculated from the values of the other fields is omitted using the header information.

  Of the fields shown in FIG. 5, V is a version number, P is a padding bit, X is an extension bit, CC is a contributing source count, and M is a marker bit.

<Sequence example of communication system processing>
Below, the sequence examples 1-5 of the process of the communication system 1 are demonstrated. 6 to 10 are sequence diagrams illustrating an example of processing of the communication system according to the first embodiment. The terminal 10 in the sequence examples 1 to 5 transmits the small data to the base station 20 in a random access procedure (hereinafter sometimes referred to as “small data RA procedure”) executed in response to the occurrence of uplink small data. Send. The small data RA procedure is executed every time small data is generated.

<Sequence example 1>
Sequence example 1 is shown in FIG. FIG. 6 is a sequence executed before small data to be transmitted from the terminal 10 is generated. That is, the terminal 10 of this example notifies the header information to the MME 30 in advance before the start of the small data RA procedure. For example, the terminal 10 notifies the MME 30 of the header information in the “attach procedure” executed before the start of the small data RA procedure. The “attach procedure” is a procedure including a process of making an attach request (Attach Request) to the network first after the terminal 10 is turned on. Further, since the attach procedure is executed before the small data RA procedure corresponding to the “second random access procedure”, the attach procedure corresponds to the “first random access procedure”. Note that the information exchanged in steps S52 to S58 in FIG. 6 corresponds to a control message.

  That is, as shown in FIG. 6, after the random access procedure (Random Access) is executed, with the RRC (Radio Resource Control) Connection being set (Setup) (step S51), the terminal 10 performs the Attach Request, RRC. Connection Setup Complete, header information (Header Information), and an uncompressed header (Non-compressed Header) are transmitted to the currently connected base station 20 (step S52). That is, the terminal 10 transmits header information to the base station 20 together with the Attach Request. RRC Connection Setup Complete includes S-TMSI that is an identifier of the terminal 10.

  Next, the base station 20 transmits an Attach Request to the MME 30 and forms an Initial UE Message including S-TMSI, header information, and an uncompressed header, and transmits it to the MME 30. The MME 30 supports S-TMSI. In addition, the header information and the uncompressed header are stored (step S53).

  Through the processes of Step S52 and Step S53, the header information is notified from the terminal 10 to the MME 30 together with the Attach Request in the attach procedure executed before the start of the small data RA procedure.

  Next, Default bearer creation is performed between the MME 30 and the S-GW 40 (step S54).

  Next, the MME 30 notifies Attach Accept to the terminal 10 via the base station 20 (step S55).

  Next, the MME 30 transmits the header information and the uncompressed header together with the UE Context Release Command and S-TMSI to a plurality of base stations 20 including the base stations 20 around the terminal 10 (step S56). That is, the MME 30 notifies the base station 20 of the header information before starting the small data RA procedure.

  Next, the base station 20 transmits RRC Connection Release to the terminal 10 (step S57), and transmits UE Context Release Complete to the MME 30 (step S58). As a result, the RRC connection set in step S51 is released.

<Sequence example 2>
Sequence example 2 is shown in FIG. FIG. 7 is a sequence executed before small data to be transmitted from the terminal 10 is generated. That is, similarly to the sequence example 1, the terminal 10 of this example notifies the MME 30 of the header information in advance before the start of the small data RA procedure. For example, the terminal 10 notifies the MME 30 of the header information in the “location registration procedure” that is executed before the start of the small data RA procedure. The “location registration procedure” is a procedure including a process in which the terminal 10 makes a location registration request (TAU (Tracking Area Update) Request). Further, since the location registration procedure is executed before the execution of the small data RA procedure corresponding to the “second random access procedure”, the location registration procedure is similar to the “attachment procedure”. Is equivalent to. Note that the processing of steps S51 and S56 to S58 in FIG. 7 is the same as that in FIG. The information exchanged in steps S61 to S63 in FIG. 7 corresponds to a control message.

  That is, as shown in FIG. 7, the terminal 10 transmits a TAU Request, RRC Connection Setup Complete, header information, and an uncompressed header to the base station 20 (step S61). That is, the terminal 10 transmits header information to the base station 20 together with the TAU Request. RRC Connection Setup Complete includes S-TMSI.

  Next, the base station 20 transfers the TAU Request to the MME 30 and forms an Initial UE Message including S-TMSI, header information, and an uncompressed header, and transmits it to the MME 30. The MME 30 supports S-TMSI. In addition, the header information and the uncompressed header are stored (step S62).

  Through the processes in steps S61 and S62, the header information is notified from the terminal 10 to the MME 30 together with the TAU Request in the location registration procedure executed before the start of the small data RA procedure.

  Next, the MME 30 notifies the terminal 10 of TAU Accept via the base station 20 (step S63).

<Sequence example 3>
Sequence example 3 is shown in FIG. FIG. 8 is a sequence subsequent to the sequence of FIG. 6 or FIG. 7. In FIG. 8, the small data RA procedure is executed. Of the information exchanged in steps S72 to S81 in FIG. 8, information other than the small data corresponds to a control message.

  That is, when small data to be transmitted is generated (step S71), the terminal 10 transmits a Random Access Preamble to the base station 20 (step S72). On the other hand, the base station 20 transmits a Random Access Response to the terminal 10. Transmit (step S73).

  Next, the terminal 10 transmits an RRC Connection Request including S-TMSI and a Small Data Indicator to the base station 20 (Step S74). The Small Data Indicator is an indicator that indicates that the terminal 10 transmits small data, and is transmitted prior to transmission of the small data.

  The base station 20 has already received notification of header information from the MME 30 in step S56 (FIGS. 6 and 7) when the small data indicator is received in step S74. Therefore, the base station 20 allocates communication resources to the small data, and transmits RRC Connection Setup including the allocation result (UL (Uplink) grant for small data transmission) to the terminal 10 (step S75). Note that one unit of communication resource is defined by, for example, one unit of time and one unit of frequency, and may be referred to as RE (Resource Element).

  Next, the terminal 10 uses the communication resource allocated by the base station 20 to transmit RRC Connection Setup Complete and small data to which the compressed header is added to the base station 20 (step S76).

  Next, the base station 20 decompresses the compressed header using the header information, forms an S-TMSI and an Initial UE Message including the small data with the decompressed header added, and transmits it to the MME 30 (step S77).

  Next, the MME 30 forms a GTP-U (GPRS (General Packet Radio Service) Tunneling Protocol for User Plane) including small data to which a TEID (Tunnel Endpoint Identifier) and a restoration header are added, and transmits the GTP-U to the S-GW 40. (Step S78).

  Next, the S-GW 40 transmits DL (Downlink) Data Notification to the MME 30 (step S79).

  Next, the MME 30 transmits a DL NAS (Non Access Stratum) Transport including the Release Command to the base station 20 (step S80).

  Next, the base station 20 transmits RRC Connection Release to the terminal 10 (step S81). As a result, the RRC connection set in steps S74 and S75 is released. That is, the base station 20 releases the connection between the base station 20 and the terminal 10 when the reception of the small data transmitted from the terminal 10 is completed. Here, “complete reception of small data” means that the small data transmitted from the terminal 10 has reached the S-GW 40.

<Sequence example 4>
Sequence example 4 is shown in FIG. FIG. 9 is a sequence subsequent to the sequence of FIG. 6 or FIG. 7, and in FIG. 9, the small data RA procedure is executed. However, FIG. 9 is a sequence when the process of step S56 of FIGS. 6 and 7 is not performed, that is, when the header information is not notified from the MME 30 to the base station 20 in the attach procedure and the location registration procedure. is there. In FIG. 9, the processes of steps S82 and S83 are added to the sequence of FIG. Note that the processes in steps S71 to S81 in FIG. 9 are the same as those in FIG. The information exchanged in steps S82 and S83 in FIG. 9 corresponds to a control message.

  That is, the base station 20 has not received notification of header information from the MME 30 at the time of receiving the Small Data Indicator in step S74. Therefore, the base station 20 transmits a notification request (Header Information Request) including the S-TMSI of the terminal 10 that is the acquisition target of the header information to the MME 30 (step S82).

  The MME 30 that has received the notification request from the base station 20 transmits the header information corresponding to the S-TMSI requested from the base station 20 and the uncompressed header to the base station 20 together with the S-TMSI in response to the notification request. (Step S83).

<Sequence example 5>
Sequence example 5 is shown in FIG. FIG. 10 is a sequence subsequent to the sequence of FIG. 6 or FIG. 7. In FIG. 10, the small data RA procedure is executed. Note that the processing in steps S71 to S73, S75, S76, and S78 to S81 in FIG. 10 is the same as that in FIG. Information exchanged in steps S91 and S92 in FIG. 10 corresponds to a control message.

  When the header information notified in the attach procedure or the location registration procedure is changed, the terminal 10 transmits the RRC Connection Request including S-TMSI, the changed header information, and the uncompressed header to the base station 20. (Step S91). That is, when the header information is changed, the header information is notified from the terminal 10 to the base station 20. Note that the header information transmitted in step S91 also serves as a small data indicator.

  The base station 20 gives priority to the header information notified in the attach procedure or the location registration procedure, and uses the header information after the change notified in step S91 in the small data RA procedure to compress the small data. Restore the header. Then, the base station 20 forms an Initial UE Message including S-TMSI and small data to which a restoration header is added and transmits it to the MME 30 (step S92).

  As described above, according to the present embodiment, the terminal 10 transmits small data to the base station 20 in the small data RA procedure executed in response to the generation of uplink small data. Further, the terminal 10 notifies the MME 30 of the header information before starting the small data RA procedure. For example, in the attach procedure executed before the start of the small data RA procedure, the terminal 10 notifies the header information to the MME 30 together with the attach request. Further, for example, the terminal 10 notifies the MME 30 of the header information together with the location registration request in the location registration procedure executed before the start of the small data RA procedure.

  Thereby, since the terminal 10 does not need to notify the header information every time it moves between the plurality of base stations 20 (each time the cell is reselected), the overhead of the header information can be reduced. That is, the header information notified from the terminal 10 to the MME 30 is notified from the MME 30 to a plurality of base stations 20 including the base stations 20 around the terminal 10. Therefore, when the terminal 10 in the idle mode moves to a cell under any of the neighboring base stations 20, it is not necessary to notify the destination base station 20 of header information again. That is, it is possible to omit notification of header information to the destination base station 20. Therefore, header information overhead can be reduced.

  Further, the MME 30 notifies the header information to the base station 20 before the start of the small data RA procedure.

  Thereby, since the base station 20 can grasp | ascertain header information in advance before the start of the small data RA procedure performed according to generation | occurrence | production of small data, it can decompress | restorate a compression header reliably.

  The header information includes at least one of information indicating a field that is invariable among a plurality of fields included in the header and information indicating a field that can be calculated from the values of other fields. The compressed header added to the small data is restored using the header information notified from the MME 30.

  As a result, the base station 20 uses the header information to identify invariant fields and fields that can be calculated from the values of other fields in the compressed header, and restore these fields omitted in the compressed header. be able to.

  Further, when receiving a notification request from the base station 20, the MME 30 notifies the base station 20 of header information.

  Thereby, the header information can be notified to the base station 20 as required by the base station 20.

  In addition, when small data is generated, the terminal 10 transmits a small data indicator indicating that the terminal 10 transmits small data to the base station 20 in the small data RA procedure. The base station 20 transmits a notification request to the MME 30 when the header information is not received at the time of receiving the Small Data Indicator.

  Thereby, the base station 20 can receive the notification of the header information when the small data is generated even when the notification of the header information is not received before the start of the small data RA procedure.

  Further, when the header information is changed, the terminal 10 notifies the base station 20 of the changed header information in the small data RA procedure. The base station 20 restores the compressed header using the changed header information notified by the terminal 10 in the small data RA procedure in preference to the header information notified by the terminal 10 before the start of the small data RA procedure. .

  As a result, the base station 20 can restore the compressed header based on the latest header information.

[Other embodiments]
[1] In step S74 of FIG. 8 and FIG. 9, the terminal 10 may transmit to the base station 20 information indicating whether or not the terminal 10 performs header compression together with the Small Data Indicator. Then, the base station 20 may transmit a notification request to the MME 30 when the terminal 10 performs header compression. Thereby, since the header information can be notified to the base station 20 only when the terminal 10 is a terminal that performs header compression, the overhead of the header information can be further reduced.

  [2] The terminal 10, the base station 20, and the MME 30 do not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each unit is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed / integrated in arbitrary units according to various loads or usage conditions. Can be configured.

  Furthermore, various processing functions performed in the terminal 10, the base station 20, and the MME 30 are performed on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit) or MCU (Micro Controller Unit)). All or any part may be executed. In addition, various processing functions may be executed in whole or in any part on a program that is analyzed and executed by a CPU (or a microcomputer such as an MPU or MCU) or on hardware based on wired logic. Good.

  [3] The terminal 10, the base station 20, and the MME 30 can be realized by the following hardware configuration, for example.

  FIG. 11 is a diagram illustrating a hardware configuration example of the terminal. As illustrated in FIG. 11, the terminal 100 includes an antenna 101, an RF (Radio Frequency) circuit 102, a processor 103, and a memory 104. Examples of the processor 103 include a CPU, a DSP (Digital Signal Processor), and an FPGA (Field Programmable Gate Array). Examples of the memory 104 include a random access memory (RAM) such as an SDRAM (Synchronous Dynamic Random Access Memory), a read only memory (ROM), and a flash memory.

  Various processing functions performed by the terminal 10 may be realized by the processor 103 executing programs stored in various memories such as a nonvolatile storage medium. That is, a program corresponding to each process executed by the transmission unit 11, the reception unit 13, and the control information processing unit 14 may be stored in the memory 104, and each program may be executed by the processor 103. The transmission unit 11 and the reception unit 13 are realized by the RF circuit 102 and the processor 103. The control information processing unit 14 is realized by the processor 103. The antenna 12 is realized by the antenna 101.

  FIG. 12 is a diagram illustrating a hardware configuration example of the base station. As illustrated in FIG. 12, the base station 200 includes an antenna 201, an RF circuit 202, a processor 203, a network IF 204, and a memory 205.

  Examples of the processor 203 include a CPU, a DSP, and an FPGA. Examples of the memory 205 include RAM such as SDRAM, ROM, flash memory, and the like.

  Various processing functions performed in the base station 20 may be realized by the processor 203 executing programs stored in various memories such as a nonvolatile storage medium. That is, a program corresponding to each process executed by the reception unit 22, the eNB communication control unit 23, and the transmission unit 25 may be stored in the memory 205, and each program may be executed by the processor 203. The receiving unit 22 and the transmitting unit 25 are realized by the RF circuit 202 and the processor 203. The eNB communication control unit 23 is realized by the processor 203. The storage unit 26 is realized by the memory 205. The antenna 21 is realized by the antenna 201. The network IF 24 is realized by the network IF 204.

  FIG. 13 is a diagram illustrating a hardware configuration example of the MME. As illustrated in FIG. 13, the MME 300 includes a network IF 301, a processor 302, and a memory 303.

  Examples of the processor 302 include a CPU, a DSP, and an FPGA. Examples of the memory 303 include RAM such as SDRAM, ROM, flash memory, and the like.

  Various processing functions performed by the MME 30 may be realized by the processor 302 executing programs stored in various memories such as a nonvolatile storage medium. That is, a program corresponding to each process executed by the MME communication control unit 32 may be stored in the memory 303, and each program may be executed by the processor 302. Further, the MME communication control unit 32 is realized by the processor 302. The storage unit 33 is realized by the memory 303. The network IFs 31 and 34 are realized by the network IF 301.

  [4] The disclosed technique can also be applied to user data other than small data.

10 terminal 14 control information processing unit 20 base station 23 eNB communication control unit 30 MME
32 MME communication controller

Claims (14)

A communication system comprising a terminal device, a base station, and a network control device,
The terminal device that transmits the user data to the base station in a random access procedure that is executed in response to the occurrence of uplink user data uses the information used for decompression of the compressed header that is added to the user data. It notifies the network controller prior to the start of the access procedure,
The network control device notifies the information to the base station and a plurality of base stations around the base station,
When the terminal device moves from a cell under the base station to a cell under any of the plurality of base stations, the terminal device notifies the base station under the destination cell of the information. do not do,
Communications system. The information includes at least one of information indicating an invariable field among a plurality of fields included in the header, and information indicating a field that can be calculated from values of other fields.
The communication system according to claim 1. The terminal device notifies the network control device of the information in an attach procedure.
The communication system according to claim 1. The terminal device notifies the network control device of the information together with an attach request in the attach procedure.
The communication system according to claim 3. The terminal device notifies the information to the network control device in a location registration procedure.
The communication system according to claim 1. In the location registration procedure, the terminal device notifies the network control device of the information together with a location registration request.
The communication system according to claim 5. The base station uses the information notified from the network control device to restore the compressed header added to the user data.
The communication system according to claim 1 . The network control device notifies the information to the base station when a notification request is received from the base station.
The communication system according to claim 1 . When the user data is generated, the terminal device transmits an indicator indicating that the terminal device transmits the user data to the base station in the random access procedure,
The base station transmits the notification request to the network control device when the information is not received at the time of receiving the indicator.
The communication system according to claim 8 . When the user data is generated, the terminal device transmits information indicating whether the terminal device performs header compression to the base station in the random access procedure,
The base station transmits the notification request to the network control device when the terminal device performs the header compression.
The communication system according to claim 8 . When the information is changed, the terminal device notifies the base station of the changed information in the random access procedure,
The base station uses the information after the change notified by the terminal device in the random access procedure in preference to the information notified by the terminal device before the start of the random access procedure. Restore,
The communication system according to claim 1. The plurality of surrounding base stations are base stations in a tracking area where the terminal device is located.
The communication system according to claim 1 . A transmitter for transmitting the user data to a base station in a random access procedure executed in response to occurrence of uplink user data;
Information used for decompression of the compressed header added to the user data is notified to the network control device before the start of the random access procedure, while the terminal itself is in the vicinity of the base station from a cell under the base station. When moving to a cell under any of a plurality of base stations, an information processing unit that does not notify the information to a base station under the destination cell ; and
A terminal device comprising: A communication method in a terminal device,
Information used for decompression of the compressed header added to the uplink user data is notified to the network control device before the start of a random access procedure executed in response to the occurrence of the user data,
In the random access procedure, the user data with the compressed header added is transmitted to a base station,
When the terminal device moves from a cell under the base station to a cell under any of a plurality of base stations in the vicinity of the base station, the terminal device is notified of the information to the base station under the destination cell do not do,
Communication method.

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