JP6391292B2 - Mobile station, communication system, and backoff indicator application method - Google Patents

Description

  The present invention relates to a mobile station, a communication system, and a backoff indicator application method.

  In the LTE (Long Term Evolution) system, random access (RA: Random Access) is performed when a mobile station (UE: User Equipment) establishes a connection with a base station (eNB: evolved Node B) at the time of transmission or handover. Is called.

  FIG. 1 shows a random access procedure in the LTE system. The mobile station transmits a preamble randomly selected from a plurality of preambles (RA preamble) prepared in the cell (step S11). The RA preamble is also called message 1 (Msg. 1). When the base station detects the preamble, it transmits the response information (RA Response) (step S12). The RA response is also called message 2 (Msg. 2). The mobile station that has received the RA Response transmits a connection request signal (RRC (Radio Resource Control) Connection Request) when the RA preamble included in the RA Response is included (step S13). RRC Connection Request is also called Message 3 (Msg. 3). When receiving the RRC Connection Request, the base station transmits a connection setting signal (RRC Connection Setup) including cell setting information for establishing a connection (Step S14). RRC Connection Setup is also called Message 4 (Msg. 4). If the RRC Connection Setup contains the identifier (RNTI: Radio Network Temporary Identifier) addressed to itself and the content of message 3, the mobile station completes the random access process and sends a connection setup completion notification (RRC Connection Setup Complete). By transmitting, a connection is established (step S15). On the other hand, if the identifier addressed to itself or the content of the message 3 is not included, the mobile station regards the failure as a random access and performs the process from the preamble transmission (step S11) again (see Non-Patent Documents 1 and 2). ).

  In this way, a random access procedure in which a mobile station randomly selects a random access channel resource is called a contention-based random access procedure. In the contention-based random access procedure, a connection is established when contention resolution is successful. If the contention resolution is not successful, that is, if the RA preamble addressed to itself is not included in the message 2 or if the identifier addressed to itself or the content of the message 3 is not included in the message 4, the preamble is transmitted again. Redo the process. In addition, when the back-off indicator (back-off timer value) indicating the waiting time until the random access is restarted is included in the message 2, the mobile station transmits the message 1 for the time specified by the back-off indicator. Just delay.

3GPP TS 36.300 V12.1.0 (2014-03) 3GPP TS 36.321 V12.1.0 (2014-03)

  In the above random access procedure, the base station cannot distinguish between the emergency call (AC10) or the important call (AC11-15) when the message 1 is received. When network congestion occurs due to signals in the random access procedure, the base station reduces the congestion by ignoring or rejecting the random access procedure from the mobile station. Ignoring the random access procedure means replying with the RA preamble of another mobile station in message 2, not replying message 4 to message 3, or replying with the identifier of another mobile station in message 4 Or reply without putting the content of message 3 into message 4. Further, the rejection of the random access procedure means that RRC Connection Reject is transmitted in response to the message 3.

  If the random access procedure is ignored, the base station cannot distinguish between an emergency call or an important call and the back-off indicator backs off the random access attempt of the emergency or important call. As a result, there is a possibility that an emergency call or an important call cannot be communicated.

  Further, when rejecting the random access procedure, the base station can reject the message 3 after confirming the connection cause (Establishment Cause) of the message 3, but it is necessary to process the message 3, so that the processing load is increased. Becomes higher. Furthermore, if the network is congested, the base station may not be able to process message 3.

  An object of the present invention is to prioritize emergency call or important call processing by allowing a mobile station to autonomously distinguish between emergency calls or important calls and applying a back-off indicator in a random access procedure.

A mobile station according to an aspect of the present invention is:
A random access procedure processing unit that transmits a message for establishing a connection with the base station using a random access procedure;
In response to the message, the emergency call / important call back-off change information indicating whether the mobile station ignores the back-off indicator when resuming the random access procedure for the emergency call or the important call, a back-off indicator, An emergency call / important call backoff change information receiving unit for receiving a message including the base station,
When the random access procedure fails, a call type determination unit that determines whether the call to be transmitted is an emergency call or an important call;
A backoff indicator application unit for determining whether to apply the backoff indicator according to the emergency call / important call backoff change information when the call to be transmitted is an emergency call or an important call;
It is characterized by having.

A communication system according to an aspect of the present invention includes:
A communication system comprising a base station and a mobile station that establishes a connection between the base station using a random access procedure,
The base station
The emergency call / important call back-off change information is set to indicate whether or not the back-off indicator is ignored when the mobile station resumes the random access procedure for the emergency call / important call. An information setting section;
A transmitter that transmits backoff change information for emergency calls and important calls;
Have
The mobile station
A random access procedure processing unit for transmitting a message for establishing a connection with the base station using a random access procedure;
In response to the message, and the emergency call-critical call for back-off change information, the emergency call-critical call for back-off change information receiving unit for receiving a message from said base station comprising a back-off indicator,
When the random access procedure fails, a call type determination unit that determines whether the call to be transmitted is an emergency call or an important call;
If transmit target call is an emergency call or important calls, the backoff indicator application section for determining whether to apply the backoff indicator in accordance with the emergency call, important call for back-off change information,
It is characterized by having.

A back-off indicator application method according to an aspect of the present invention includes:
A backoff indicator application method in a mobile station that establishes a connection with a base station using a random access procedure,
Sending a message to establish a connection with the base station using a random access procedure;
In response to the message, the emergency call / important call back-off change information indicating whether the mobile station ignores the back-off indicator when resuming the random access procedure for the emergency call or the important call, a back-off indicator, Receiving from the base station a message comprising:
Determining whether the call to be transmitted is an emergency call or an important call if the random access procedure fails;
Determining whether to apply the back-off indicator according to the emergency call / important call back-off change information when the call to be transmitted is an emergency call or an important call;
It is characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to give priority to the processing of an emergency call or an important call by a mobile station distinguishing an emergency call or an important call autonomously in a random access procedure, and applying a back-off indicator.

The figure which shows the random access procedure in a LTE system Configuration diagram of a base station according to an embodiment of the present invention Schematic diagram of MAC header used in an embodiment of the present invention Examples of backoff parameter values used in embodiments of the present invention Configuration diagram of a mobile station according to an embodiment of the present invention 6 is a flowchart illustrating a method for applying a backoff indicator in a mobile station according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  In an embodiment of the present invention, a random access procedure between a mobile station and a base station will be described. The mobile station uses a random access procedure with the base station when establishing a connection. When the random access procedure fails, the mobile station ignores the back-off indicator notified in the random access procedure when the call to be transmitted is an emergency call or an important call, for example, the message 1 ( RA preamble).

  In addition, the base station controls the above operation of the mobile station, and the emergency call / important call back indicates that the mobile station ignores the back-off indicator when the mobile station resumes the random access procedure for the emergency call or the important call. The off change information may be transmitted to the mobile station. When the mobile station receives the emergency call / important call back-off change information, the mobile station ignores the back-off indicator when resuming the random access procedure for the emergency call or the important call.

  The configurations and operations of the base station and mobile station will be described in detail below.

<Configuration and operation of base station>
FIG. 2 shows the configuration of a base station according to an embodiment of the present invention. The base station 10 includes an uplink (UL) signal receiving unit 101, a downlink (DL) signal transmitting unit 103, an emergency call / important call backoff change information setting unit 105, and a random access (RA) procedure processing unit. 107.

  The UL signal receiving unit 101 receives an uplink signal from a mobile station. Regarding the random access procedure, the UL signal receiving unit 101 receives message 1 (RA preamble), message 3 (RRC Connection Request), and RRC Connection Setup Complete.

  The DL signal transmission unit 103 transmits a downlink signal to the mobile station. With regard to random access handling, the DL signal transmission unit 103 transmits message 2 (RA Response) and message 4 (RRC Connection Setup).

  The emergency call / important call back-off change information setting unit 105 indicates that the mobile station ignores the back-off indicator when the mobile station resumes the random access procedure for the emergency call / important call. Set the information. The emergency call / important call back-off change information may be set in the message 2 used to notify the back-off indicator.

  FIG. 3 shows an example of a MAC (Medium Access Control) header of message 2 used in the embodiment of the present invention. As shown in FIG. 3A, the MAC header of message 2 is divided into a plurality of subheaders, and a backoff indicator (E / T / R / R / BI subheader or Backoff Indicator MAC subheader) BI: Backoff Indicator) is notified. As shown in FIG. 4, the back-off indicator is set with a back-off timer value that delays the transmission of the message 1, for example, corresponding to indexes 0 to 15.

  As shown in FIG. 3B, one unused bit (R: Reserved) in the first subheader can be used as backoff change information (C bit: Congestion bit) for emergency call / important call. For example, C bit = 1 indicates that the mobile station ignores the backoff indicator when resuming the random access procedure for an emergency call or an important call, and C bit = 0 indicates that the mobile station for an emergency call or an important call. Indicates that the mobile station applies the back-off indicator even when resuming the random access procedure.

  The RA procedure processing unit 107 controls a random access procedure with the mobile station. When receiving the message 1 from the mobile station, the RA procedure processing unit 107 puts the RA preamble received from the mobile station into the message 2 and transmits it from the DL signal transmission unit 103 to the mobile station. In addition, a back-off indicator is put in message 2 in order to delay the restart of the random access procedure for the mobile station that has ignored message 1. Further, when receiving the message 3 from the mobile station, the RA procedure processing unit 107 puts the identifier (RNTI) received from the mobile station and the content of the message 3 in the message 4 and transmits it from the DL signal transmission unit 103 to the mobile station. .

<Configuration and operation of mobile station>
FIG. 5 shows the configuration of a mobile station according to an embodiment of the present invention. The mobile station 20 includes a downlink (DL) signal reception unit 201, an uplink (UL) signal transmission unit 203, an emergency call / important call backoff change information reception unit 205, a call type determination unit 207, An off indicator application unit 209 and a random access (RA) procedure processing unit 211 are included.

  The DL signal receiving unit 201 receives a downlink signal from the base station. Regarding the random access procedure, the DL signal receiving unit 201 receives message 2 (RA Response) and message 4 (RRC Connection Setup).

  The UL signal transmission unit 203 transmits an uplink signal to the base station. Regarding the random access procedure, the UL signal transmission unit 203 transmits message 1 (RA preamble), message 3 (RRC Connection Request), and RRC Connection Setup Complete.

  The emergency call / important call back-off change information receiving unit 205 receives the emergency call / important call back-off change information included in the signal (message 2) received by the DL signal receiving unit 201.

  The call type determination unit 207 determines the type of call to be transmitted. Specifically, when the random access procedure fails, the call type determination unit 207 determines whether the call to be transmitted is an emergency call (AC10) or an important call (AC11 to 15). In the failure of the random access procedure, the message 2 does not include the RA preamble addressed to itself, the message 4 is not returned to the message 3, and the message 4 includes an identifier of another mobile station Or the content of message 3 is not included in message 4.

  The back-off indicator application unit 209 determines whether to apply the back-off indicator notified in the random access procedure based on whether the call to be transmitted is an emergency call or an important call. Specifically, when the backoff indicator application unit 209 receives emergency call / important call backoff change information together with the backoff indicator, the mobile station resumes the random access procedure for the emergency call or the important call. Ignore backoff indicator. In this case, the emergency call or important call message 1 (RA preamble) may be transmitted at the next transmission timing. As usual, a message 1 other than an emergency call or an important call is transmitted with a backoff indicator applied and delayed by a time specified by the backoff indicator.

  The back-off indicator application unit 209 also displays the back-off indicator when the mobile station resumes the random access procedure for the emergency call or the important call when the emergency call / important call back-off change information is not received together with the back-off indicator. Apply. In this case, all messages 1 (RA preamble) including an emergency call or an important call are transmitted with a delay specified by the back-off indicator as usual.

  The RA procedure processing unit 211 controls a random access procedure with the base station. The RA procedure processing unit 211 transmits a message 1 (RA preamble) from the UL signal transmission unit 203 to the base station in order to establish a connection. Also, when the RA preamble addressed to itself is included in the message 2 received from the base station, the RA procedure processing unit 211 transmits the message 3 with the mobile station identifier (RNTI). On the other hand, if the message 2 received from the base station does not include the RA preamble addressed to it, the RA procedure processing unit 211 considers that the random access procedure has failed due to the collision of the RA preamble, and the message 1 (RA preamble) Redo the transmission procedure and restart the random access procedure. Further, when the message 4 includes an identifier (RNTI) addressed to itself and the content of the message 3, the RA procedure processing unit 211 transmits RRC Connection Setup Complete from the UL signal transmission unit 203 to the base station. On the other hand, when the message 3 is ignored or when the message 4 is received, the RA procedure processing unit 211 does not contain the identifier (RNTI) addressed to itself or the content transmitted by the message 3, and the contention resolution (Contention Resolution) ), The random access procedure is considered to have failed, and the random access procedure is resumed from the message 1 transmission procedure. The resumption of the random access procedure is performed, for example, at the next transmission timing when the back-off indicator application unit 209 determines to ignore the back-off indicator. On the other hand, when the back-off indicator applying unit 209 determines to apply the back-off indicator, the random access is resumed after waiting for the time specified by the back-off indicator in the message 2.

  FIG. 6 shows a backoff indicator application method in a mobile station according to an embodiment of the present invention.

  In order to establish a connection with the base station, the mobile station transmits message 1 (RA preamble) (step S101), and receives message 2 (RA Response) as response information (step S103).

  When own RA preamble is included in the received message 2 (step S105: YES), the mobile station continues the random access procedure by transmitting the message 3 as usual (step S107).

  On the other hand, when the received message 2 does not include its own RA preamble (step S105: NO), the mobile station reads the back-off indicator (BI) subheader, which is the first subheader in the message 2, and includes it. The emergency call / important call back-off change information (C bit) is confirmed.

  If the C bit is 0 (step S109: NO), the random access procedure is continued as usual (step S107). That is, even when the random access procedure is resumed for the emergency call or the important call, the back-off indicator is applied and the message 1 is transmitted.

  If the C bit is 1 (step S109: YES), the mobile station determines whether the call is an emergency call or an important call. If the call is an important call or an emergency call (step S111: YES), the mobile station ignores the back-off indicator and resumes the transmission of message 1 at the next transmission timing, for example (step S113). If it is not an important call or an emergency call (step S111: NO), the mobile station applies a back-off indicator and delays the transmission of message 1 by the time specified by the back-off indicator (step S115).

  Note that FIG. 6 illustrates the case where the message 1 is ignored, but the same applies to the case where the message 3 is ignored. In this case, in step S105, it is determined whether or not the message 4 includes the identifier (RNTI) addressed to itself and the content of the message 3, and if the identifier addressed to itself and the content of the message 3 are included, If S107 is executed and the identifier addressed to itself or the content of the message 3 is not included, step S109 is executed.

<Effect of the embodiment of the present invention>
According to an embodiment of the present invention, in a random access procedure, a mobile station autonomously distinguishes an emergency call or an important call and applies a back-off indicator, thereby allowing priority to handle an emergency call or an important call. Become. For this reason, even when the network is congested, an emergency call or important call connection is easily established.

  In addition, since the mobile station autonomously distinguishes between emergency calls and important calls, processing by the base station is reduced. Furthermore, the base station can control the processing of the emergency call or the important call by the mobile station by using the emergency call / important call back-off change information.

  For convenience of explanation, the base station and the mobile station according to the embodiment of the present invention are described using functional block diagrams, but the base station and the mobile station according to the embodiment of the present invention may be hardware, software, or A combination thereof may be realized. In addition, the functional units may be used in combination as necessary. In addition, the method according to the embodiment of the present invention may be performed in an order different from the order shown in the embodiment.

  As described above, the mobile station autonomously distinguishes the emergency call or the important call in the random access procedure and applies the back-off indicator so as to prioritize the processing of the emergency call or the important call. Without being limited to the above embodiments, various modifications and applications are possible within the scope of the claims.

DESCRIPTION OF SYMBOLS 10 Base station 101 UL signal receiving part 103 DL signal transmission part 105 Emergency call / important call backoff change information setting part 107 RA procedure processing part 20 Mobile station 201 DL signal receiving part 203 UL signal transmission part 205 Emergency call / important call Backoff change information receiving unit 207 Call type determining unit 209 Backoff indicator applying unit 211 RA procedure processing unit

Claims (4)

A random access procedure processing unit that transmits a message for establishing a connection with the base station using a random access procedure;
In response to the message, the emergency call / important call back-off change information indicating whether the mobile station ignores the back-off indicator when resuming the random access procedure for the emergency call or the important call, a back-off indicator, An emergency call / important call backoff change information receiving unit for receiving a message including the base station,
When the random access procedure fails, a call type determination unit that determines whether the call to be transmitted is an emergency call or an important call;
A backoff indicator application unit for determining whether to apply the backoff indicator according to the emergency call / important call backoff change information when the call to be transmitted is an emergency call or an important call;
A mobile station. Before Symbol back-off indicator application unit,
If the emergency call / critical call backoff change information indicates to ignore the backoff indicator, ignore the backoff indicator when resuming the random access procedure for the emergency call or important call,
The backoff indicator is applied when resuming a random access procedure for an emergency call or an important call when the backoff change information for the emergency call / important call indicates that the backoff indicator is not ignored . Mobile station. A communication system comprising a base station and a mobile station that establishes a connection between the base station using a random access procedure,
The base station
The emergency call / important call back-off change information is set to indicate whether or not the back-off indicator is ignored when the mobile station resumes the random access procedure for the emergency call / important call. An information setting section;
A transmitter that transmits backoff change information for emergency calls and important calls;
Have
The mobile station
A random access procedure processing unit for transmitting a message for establishing a connection with the base station using a random access procedure;
In response to the message, and the emergency call-critical call for back-off change information, the emergency call-critical call for back-off change information receiving unit for receiving a message from said base station comprising a back-off indicator,
When the random access procedure fails, a call type determination unit that determines whether the call to be transmitted is an emergency call or an important call;
If transmit target call is an emergency call or important calls, the backoff indicator application section for determining whether to apply the backoff indicator in accordance with the emergency call, important call for back-off change information,
A communication system. A backoff indicator application method in a mobile station that establishes a connection with a base station using a random access procedure,
Sending a message to establish a connection with the base station using a random access procedure;
In response to the message, the emergency call / important call back-off change information indicating whether the mobile station ignores the back-off indicator when resuming the random access procedure for the emergency call or the important call, a back-off indicator, Receiving from the base station a message comprising:
Determining whether the call to be transmitted is an emergency call or an important call if the random access procedure fails;
Determining whether to apply the back-off indicator according to the emergency call / important call back-off change information when the call to be transmitted is an emergency call or an important call;
A back-off indicator application method comprising:

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