KR101494768B1 - Method and apparatus for setting channel of mobile communication terminal - Google Patents

Abstract

The present invention relates to a channel setting method and apparatus of a mobile communication terminal. A method of establishing a channel of a mobile communication terminal, the method comprising: transmitting an RRC connection request message 1 to a cell in a first frequency band in an RRC (Radio Resource Control) idle state; 1, transmitting RRC connection request message 2 to a cell in a second frequency band if response message 1 is an RRC connection reject message, receiving RRC connection request message 2 from a cell in second frequency band, 2, and if the response message 2 is an RRC connection setup message, transmitting an RRC connection setup completion message to a cell in the second frequency band. Accordingly, since the RRC connection procedure is performed smoothly, there is an advantage that the waiting time of the data service of the mobile communication terminal is minimized.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for setting a channel of a mobile communication terminal,

The present invention relates to a method and an apparatus for setting a channel of a mobile communication terminal, and more particularly, to a mobile communication terminal performing a radio resource control (RRC) connection procedure in an environment in which cells operating in different frequency bands exist in the same area To a method and apparatus for setting a control channel.

The mobile communication service is continuously evolving from the first generation mobile communication service based on the low quality voice call provided by the analog cellular cellular AMPS (Advanced Mobile Phone Service). In the second generation mobile communication service, improved voice communication and low speed (14.4 Kbps) data service provided by digital cellular system Global System for Mobile (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) Respectively. Also, in the 2.5th generation mobile communication service, PCS (Personal Communication Service) which can be used all over the world in addition to securing the frequency of GHz band has been developed, so that it is possible to provide data communication with an improved voice communication and low speed (144 Kbps).

The third generation mobile communication service is classified and provided as a WCDMA (Wideband Code Division Multiple Access) system proposed by the 3rd Generation Partnership Project (3GPP) as a main axis and a synchronous CDMA-2000 system proposed by 3GPP2 as a main axis have. In particular, the WCDMA system is a wireless protocol recommended by IMT-2000, and many communication service providers provide services worldwide.

In 3GPP Release 8, a network architecture called EPC (Evolved Packet Core) is described. The EPC supports the evolved-UMTS Terrestrial Radio Access Network (E-UTRAN), which is an evolved RAN, by evolving the core network of the existing 3GPP system architecture, and in order to increase the efficiency of the packet network, The network structure is simplified. A wireless communication system including such EPC and E-UTRAN may be referred to as an EPS (Evolved Packet System), and this is an LTE mobile communication system currently being implemented and serviced in Korea.

In the early stage of the introduction of the EPC network, the WCDMA network and the EPC network are mixed until the entire WCDMA network is replaced with the EPC network. Is set. Accordingly, in an environment where heterogeneous networks are mixed, a multimode mobile communication terminal capable of performing both a mode of connecting to a WCDMA network and a mode of connecting to an EPC network is used. In addition, in a mixed environment including a CDMA network, a multimode mobile communication terminal capable of performing a mode of accessing a CDMA network is used. When a multi-carrier that operates a plurality of E-UTRA frequency bands is supported in an EPC network, a multiband mobile communication terminal capable of accessing all cells of different frequency bands is used. In addition, if both the multimode function and the multiband function are provided, it is referred to as a multimode-multiband mobile communication terminal.

Meanwhile, in order to start a CS (Circuit Service) or a PS (Packet Service) call in an idle state, the mobile communication terminal must first perform an RRC connection establishment to establish an RRC connection do. Here, the idle state means a mode in which there is no control channel between the mobile communication terminal and the base station. When a control channel is established between the mobile communication terminal and the base station through the RRC connection procedure, control information is transmitted and received for call setup between the mobile communication terminal and the base station through a control channel, and a radio bearer for data transmission And transmits / receives data through the radio bearer.

In order to establish the RRC connection, the RRC connection establishment request message is transmitted while the mobile communication terminal is registered in the appropriate cell. When the RRC connection establishment message is received as the response message, the RRC connection establishment completion message is transmitted to complete the RRC connection procedure .

However, the mobile communication terminal may transmit an RRC connection reject message rejecting the RRC connection setup as a response message to the RRC connection request message in the cell in which the mobile communication terminal has registered the location.

If the wait time information is included in the RRC connection rejection message, the mobile communication terminal waits for the wait time and then transmits the RRC connection request message again.

Here, a load balancing function for selecting a frequency to be used by a mobile communication terminal is implemented in an EPC network supporting a plurality of E-UTRA frequency bands. In this case, It responds by including redirection information in the RRC connection rejection message. In this case, the mobile communication terminal performs channel setting on cells in frequency bands other than the current location registered cell according to the redirection information.

However, even if the load balancing function is implemented, since redirection information for band change can not be generated if the base station does not know the load state of a cell operating in a different frequency band, if a problem such as overload occurs, Continue to export the RRC connection rejection message containing the information.

According to the related art, in such a situation, the mobile communication terminal continuously transmits an RRC connection request message to the same cell even if the current location registered cell is in a busy state of overload after unconditionally waiting for the corresponding waiting time, You will try to configure it.

Therefore, the user of the mobile communication terminal has inconvenience that the data service can not be used while the RRC connection setting is denied. Since the waiting time information included in the RRC connection rejection message normally uses a few seconds, even if the RRC connection is rejected only once, the user of the mobile communication terminal feels uncomfortable for quite a long time.

Korean Patent Registration No. 10-0895180, filed on April 20, 2009.

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the problems of the related art as described above, and it is an object of the present invention to provide a method and apparatus for preventing RRC connection from being rejected in a cell where a location is registered during an RRC connection procedure in an environment in which cells operating different frequency bands exist in the same area A mobile communication terminal can perform an RRC connection procedure for cells of different frequency bands by itself.

The problems to be solved by the present invention are not limited to those mentioned above, and another problem to be solved can be clearly understood by those skilled in the art from the following description.

A method of setting a channel of a mobile communication terminal as a first aspect of the present invention includes: transmitting an RRC connection request message 1 to a cell in a first frequency band in an RRC idle state; The method comprising: receiving a response message 1 for message 1; transmitting RRC connection request message 2 to a cell in a second frequency band if response message 1 is an RRC connection reject message; Receiving a response message 2 for the RRC connection request message 2 and transmitting the RRC connection setup complete message to the cell of the second frequency band if the response message 2 is an RRC connection setup message.

Here, the step of transmitting the RRC connection request message 1 may be performed in a mode connected to the first wireless network, and if the response message 2 is an RRC connection refusal message, a transition is made to a mode of accessing a second wireless network .

The step of transmitting the RRC connection request message 2 may use neighbor cell information included in the system information of the cell of the first frequency band as information of the cell of the second frequency band.

The step of transmitting the RRC connection request message 2 may include selectively counting the number of times the RRC connection refusal message is received from the cell of the first frequency band and comparing the count with the predetermined number of times.

When counting the number of times, when the waiting time information is included in the RRC connection refusal message, the count may be counted.

As a second aspect of the present invention, a channel setting apparatus of a mobile communication terminal transmits a RRC connection request message 1 to a cell in a first frequency band in an RRC idle state, and receives a response message 1 for the RRC connection request message 1 If the RRC connection establishment message is received as the response message 2 for the RRC connection request message 2, the RRC connection request message 2 is transmitted to the cell of the second frequency band if the response message 1 is the RRC connection reject message. And a second communication unit for transmitting an RRC connection setup completion message to a cell in the second frequency band.

A first channel setting unit connected to the first wireless network through the first communication unit and the second communication unit to perform channel setting; and a second channel setting unit connected to the second wireless network when the response message 2 is an RRC connection refusal message, And a second channel setting unit for performing setting.

The second communication unit may use neighbor cell information included in the system information for the cell of the first frequency band as information of the cell of the second frequency band.

The second communication unit may count the number of times the RRC connection rejection message is received from the cell of the first frequency band and may selectively transmit the RRC connection request message 2 according to a result of comparison with a predetermined number of times.

The second communication unit may count the number of times when the waiting time information is included in the RRC connection rejection message.

According to an embodiment of the present invention, when an RRC connection is rejected in a cell where location registration is performed during an RRC connection procedure in an environment where cells operating different frequency bands exist in the same area, RRC connection procedure is performed on the cell. Also, when all RRC connections are rejected in all frequency bands of the first radio network with relatively better communication quality, the RRC connection procedure is performed by transiting to the second radio network.

Therefore, compared to the prior art, since the RRC connection procedure is performed smoothly, the latency of the data service of the mobile communication terminal is minimized, and the probability of receiving the communication service through the first wireless network having the relatively higher communication quality is maximized do.

1 is a block diagram partially illustrating a wireless region of a mobile communication system to which a channel setting apparatus according to an embodiment of the present invention can be applied.
2 is a block diagram of a channel setting device according to an embodiment of the present invention.
3 is a flowchart illustrating a channel setting method of a mobile communication terminal according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

1 is a block diagram partially illustrating a wireless region of a mobile communication system to which a channel setting apparatus according to an embodiment of the present invention can be applied.

The channel setting apparatus 100 according to an embodiment of the present invention may be included in the mobile communication terminal 40 and the mobile communication terminal 40 may include the first base station 10 to the third base station 30 A mobile communication service including a data communication service can be provided from a plurality of base stations including the base station. For example, the mobile communication terminal 40 may be a multi-band mobile communication terminal capable of receiving a mobile communication service through a wireless network operating a plurality of frequency bands such as an EPC network, or a multi-band mobile communication terminal such as a WCDMA network or a CDMA network Multi-band mobile communication terminal capable of receiving mobile communication service through a legacy wireless network.

Here, the first base station 10 is a base station operating a first frequency band in a cell of a first radio network, the second base station 20 is a base station operating a second frequency band in a cell of the first radio network, And the third base station 30 is assumed to be a base station operating a specific frequency band in a cell of the second wireless network. For example, the first base station 10 may use the band 5 (850 MHz band) of the E-UTRA frequency band in the EPC network and the second base station 20 may use the band 3 (1800 MHz band ), And the third base station 30 can use band 1 (2.1 GHz band) of the E-UTRA frequency band in the WCDMA network.

2 is a block diagram of a channel setting device according to an embodiment of the present invention.

The channel setting apparatus 100 according to the embodiment of the present invention includes a first channel setting unit 110 and a second channel setting unit 120. The first channel setting unit 110 includes a first channel setting unit 110, And includes a communication unit 111 and a second communication unit 113.

The first channel setting unit 110 accesses the first wireless network through the first communication unit 110 and the second communication unit 113 and performs channel setting such as an RRC connection procedure.

The first communication unit 111 transmits the RRC connection request message 1 to the first base station 10 in the RRC idle state and receives the response message 1 for the RRC connection request message 1 from the first base station 10, 1 is an RRC connection setup message, it transmits an RRC connection setup complete message to the first base station 10. If response message 1 is an RRC connection rejection message, perform the following procedure selectively according to the latency information or redirection information included in the RRC connection rejection message.

If the first communication unit 111 includes the redirection information for changing the frequency band in the RRC connection rejection message, the first communication unit 111 requests the second communication unit 113 to perform channel setting such as an RRC connection procedure. The RRC connection request message 1 is retransmitted after waiting for a waiting time according to a band change condition such as when the RRC connection reject message has been received and counted the number of times that the RRC connection reject message has been received, 2 communication unit 113 to perform channel setting such as an RRC connection procedure. When the first communication unit 111 requests the second communication unit 113 to set up a channel such as an RRC connection procedure, it transmits the information of the second base station 20 from the neighboring cell information included in the system information for the first base station 10 And provides it to the second communication unit 113.

If the response message 1 is the RRC connection rejection message, the second communication unit 113 transmits the RRC connection request message 2 to the second base station 20, and when the RRC connection setup message is received as the response message 2 for the RRC connection request message 2 2 < / RTI > If response message 2 is an RRC connection rejection message, perform the following procedure selectively according to the latency information or redirection information included in the RRC connection rejection message.

If the second communication unit 113 includes the redirection information for changing the frequency band in the RRC connection rejection message, the second communication unit 113 requests the first communication unit 111 to perform channel setting such as an RRC connection procedure. The RRC connection request message 2 is transmitted again after waiting for a waiting time according to the wireless network change condition such as when the number of times the RRC connection reject message is received and when the RRC connection reject message is received a predetermined number of times, And requests the second channel setting unit 120 to perform channel setting such as an RRC connection procedure. The wireless network change condition may be added to the condition that the RRC connection is rejected in all the frequency bands while satisfying the band change condition used in the first communication unit 111. [

If the channel setting such as the RRC connection procedure by the first channel setting unit 110 is rejected by the network node such as the base station, the second channel setting unit 120 accesses the second wireless network and sets a channel setting such as an RRC connection procedure . If the response message 2 is an RRC connection refusal message and satisfies the wireless network change condition, the second channel setting unit 120 may access the third base station 30 and perform channel setting such as an RRC connection procedure.

3 is a flowchart illustrating a channel setting method of a mobile communication terminal according to an embodiment of the present invention.

As described above, a method of setting a channel of a mobile communication terminal according to an embodiment of the present invention includes transmitting RRC connection request message 1 to a cell in a first frequency band through a first wireless network in an RRC idle state (S201, S203 (S205) of receiving a response message 1 for the RRC connection request message 1 from the cell of the first frequency band, and if the response message 1 is an RRC connection refusal message, receiving an RRC connection reject message from the cell of the first frequency band (S207, S209) of counting the number of received times and determining whether the counted number of times of reception satisfies the band change condition.

A step (S211) of retransmitting the RRC connection request message 1 after waiting for a waiting time when the number of times of receiving the RRC connection refusal message from the cell of the first frequency band does not satisfy the band changing condition (S211) (S213) of neighboring cell information included in the system information on the cell of the frequency band. (S215, S217) transmitting an RRC connection request message 2 to a cell of a second frequency band operating in the first radio network using the identified neighbor cell information, and transmitting the RRC connection request message 2 (Step S219).

If the response message 2 for the RRC connection request message 2 from the cell of the second frequency band is the RRC connection reject message, the number of times the RRC connection reject message is received from the cell of the second frequency band is counted, (S225) of retransmitting the RRC connection request message 2 after waiting for a waiting period if the condition for changing the wireless network is not satisfied (S225) (S227). If the response message 2 is an RRC connection setup message, a control channel is set by transmitting an RRC connection setup completion message to a cell of a second frequency band, or a second wireless network (Step S229) of setting a control channel in the cell of step S229.

Hereinafter, a process of setting a channel through an RRC connection procedure or the like by a channel setting apparatus of a mobile communication terminal according to an embodiment of the present invention will be described in detail with reference to FIG. 1 to FIG. In the following description, the first base station 10 uses the band 5 (850 MHz band) of the E-UTRA frequency band in the EPC network and the second base station 20 uses the band 3 (1800 MHz) of the E-UTRA frequency band in the EPC network. Band) of the E-UTRA frequency band in the WCDMA network and the third base station 30 uses the band 1 (2.1 GHz band) of the E-UTRA frequency band in the WCDMA network.

First, the first communication unit 111 of the first channel setting unit 110 constituting the channel setting apparatus 100 registers with the first base station 10 of the cell using the band 5 of the EPC network and camps on (S201) and transmits an RRC connection request message 1 to the first base station 10 in the RRC idle state (S203).

When the first base station 10 transmits a response message 1 for the RRC connection request message 1, the first communication unit 111 receives the response message 1 (S205).

The first communication unit 111 confirms whether the response message 1 is an RRC connection setup message or an RRC connection rejection message (S207). If the RRC connection setup message is received, the first communication unit 111 transmits an RRC connection A setup completion message is transmitted to inform that the RRC connection procedure is completed, and a control channel is set (S229).

If the response message 1 is confirmed by the RRC connection refusal message in step S207, the first communication unit 111 confirms the waiting time information or the redirection information included in the corresponding RRC connection refusal message. Here, when the RRC connection reject message includes the redirection information for changing the frequency band, the first communication unit 111 immediately requests the second communication unit 113 to perform channel setting such as an RRC connection procedure. This corresponds to a general frequency band changing procedure and is not shown in FIG.

When the RRC connection refusal message includes the waiting time information, the first communication unit 111 counts the number of times the RRC connection refusal message is received from the first base station 10, Is satisfied. For example, when the RRC connection refusal message is received a predetermined number of times, it can be determined that the band changing condition is satisfied (S209).

If the number of times that the RRC connection refusal message is received from the first base station 10 does not satisfy the band changing condition, the first communication unit 111 waits for the waiting time and then transmits an RRC connection request message 1 again (S211).

However, if it is determined in step S209 that the number of times that the RRC connection refusal message is received from the first base station 10 satisfies the band change condition, the first communication unit 111 transmits the RRC connection rejection message to the second communication unit 113, You are asked to perform the configuration. At this time, the first communication unit 111 transmits the information of the second base station 20 in the neighbor cell information of the SIB 5 (System Information Block 5) included in the system information broadcasted by the eNodeB of the first base station 10 And can provide it to the second communication unit 113 (S213).

Next, the second communication unit 113 registers with the second base station 20 of the cell using the band 3 of the EPC network and camps on (S215) using the neighboring cell information provided from the first communication unit 113, , And transmits an RRC connection request message 2 to the second base station 20 in the RRC idle state (S217).

When the second base station 20 transmits a response message 2 to the RRC connection request message 2, the second communication unit 113 receives the response message 2 (S219).

The second communication unit 113 confirms whether the response message 2 is an RRC connection setup message or an RRC connection rejection message (S221). If the response message 2 is an RRC connection setup message, the second communication unit 113 transmits an RRC connection A setup completion message is transmitted to inform that the RRC connection procedure is completed, and a control channel is set (S229).

If the response message 2 is confirmed by the RRC connection refusal message in step S221, the second communication unit 113 checks the waiting time information or the redirection information included in the corresponding RRC connection refusal message. Here, when the RRC connection reject message includes the redirection information for changing the frequency band, the second communication unit 113 immediately requests the first communication unit 111 to perform channel setting such as an RRC connection procedure. However, in the normal case, the redirection information is not included in the RRC connection rejection message as it is redirected from the band 5 to the band 3 of the EPC network in step S215.

The second communication unit 113 counts the number of times the RRC connection refusal message is received from the second base station 20 when the RRC connection refusal message includes the waiting time information, Is satisfied. For example, when an RRC connection refusal message is received a predetermined number of times, it can be determined that the band change condition is satisfied (S223).

For example, the reference number for determining whether the radio network change condition is satisfied is calculated by summing the number of times the RRC connection rejection message is received from the first base station 10 and the number of times the RRC connection rejection message is received from the second base station 20 As shown in Equation (1).

Here, if the maximum value of the counter for counting the number of times of reception of the RRC connection reject message is set to a value obtained by subtracting 1 from the reference number of Equation (1), it is easy to determine whether the wireless network change condition is satisfied in step S223.

If the number of times that the RRC connection refusal message is received from the second base station 20 does not satisfy the wireless network change condition, the second communication unit 113 waits for the waiting time and then transmits an RRC connection request message 2 (S225).

However, if it is determined in step S223 that the number of times the RRC connection refusal message is received from the second base station 20 satisfies the wireless network change condition, the second communication unit 113 transmits the RRC connection procedure And so on.

Then, the second channel setting unit 120 transitions to a mode for accessing the third base station 30 using the band 1 (2.1 GHz band) of the E-UTRA frequency band in the WCDMA network, And transmits a new RRC request message to the RRC connection procedure (S229).

As described above, according to the embodiment of the present invention, if an RRC connection is rejected in a cell registered in a location during an RRC connection procedure in an environment where cells operating different frequency bands exist in the same area, And performs the RRC connection procedure for cells of different frequency bands by itself. Also, when all RRC connections are rejected in all frequency bands of the first radio network with relatively better communication quality, the RRC connection procedure is performed by transiting to the second radio network.

Each step in the block diagrams and flowcharts attached to the present invention may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function (s). It should also be noted that in alternate embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially concurrently, or the blocks or steps may sometimes be performed in reverse order according to the corresponding function.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

The present invention can be applied to a mobile communication service system through a wireless network operating a plurality of frequency bands, such as an EPC network supporting multi-carrier. In addition, it may be used in a mobile communication service system of a heterogeneous mixed environment in which a radio network such as a WCDMA network or a CDMA network is mixed with an EPC network.

When an embodiment of the present invention is applied to a mobile communication terminal provided with a communication service from such a mobile communication service system, it is possible to provide a mobile communication terminal that is located and registered in an RRC connection procedure in an environment in which cells operating different frequency bands exist in the same area When the RRC connection is rejected in the cell, the mobile communication terminal itself performs the RRC connection procedure with respect to the cells of different frequency bands. If the RRC connection is rejected in all the frequency bands of the first radio network having relatively better communication quality, the RRC connection procedure is performed by transiting to the second radio network.

Therefore, since the RRC connection procedure is performed smoothly, the latency of the data service of the mobile communication terminal is minimized, and the probability of receiving the communication service through the first wireless network with the relatively higher communication quality is maximized.

10: first base station 20: second base station
30: third base station 40: mobile communication terminal
100: channel setting apparatus 110: first channel setting unit
111: first communication unit 113: second communication unit
120: second channel setting unit

Claims (10)

Transmitting an RRC connection request message 1 to a cell in a first frequency band in an RRC (Radio Resource Control) idle state;
Receiving a response message 1 for the RRC connection request message 1 from the cell of the first frequency band;
If the response message 1 is an RRC connection refusal message , checking neighbor cell information included in the system information of the cell of the first frequency band;
Transmitting an RRC connection request message 2 to a cell in a second frequency band using the identified neighbor cell information ;
Receiving a response message 2 for the RRC connection request message 2 from the cell of the second frequency band;
And if the response message 2 is an RRC connection setup message, transmitting an RRC connection setup completion message to the cell of the second frequency band. The method according to claim 1,
The transmitting of the RRC connection request message 1 is performed in a mode connected to the first radio network,
And if the response message 2 is an RRC connection refusal message, transitioning to a mode of accessing a second wireless network. delete The method according to claim 1,
The transmitting of the RRC connection request message 2 may include counting the number of times the RRC connection refusal message is received from the cell of the first frequency band, How to set it up. 5. The method of claim 4,
And counting the number of times when the waiting time information is included in the RRC connection refusal message when the number of times is counted. A first communication unit for transmitting an RRC connection request message 1 to a cell in a first frequency band in an RRC (Radio Resource Control) idle state and receiving a response message 1 for the RRC connection request message 1;
If the response message 1 is an RRC connection rejection message, neighbor cell information included in the system information of the cell of the first frequency band is confirmed, and an RRC connection request is transmitted to the cell of the second frequency band using the confirmed neighbor cell information And a second communication unit for transmitting an RRC connection setup completion message to the cell of the second frequency band when the RRC connection setup message is received as the response message 2 for the RRC connection request message 2, Channel setting device. The method according to claim 6,
A first channel setting unit connected to the first wireless network through the first communication unit and the second communication unit to perform channel setting;
And if the response message 2 is an RRC connection refusal message, accessing the second wireless network to perform channel setting. delete The method according to claim 6,
Wherein the second communication unit counts the number of times the RRC connection refusal message is received from the cell of the first frequency band and selectively transmits the RRC connection request message 2 according to a result of comparison with the preset number of times Channel setting device. 10. The method of claim 9,
Wherein the second communication unit counts the number of times when waiting time information is included in the RRC connection refusal message.

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