JP2008048175A - Mobile communication terminal and mobile communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to effectively use resources of a mobile communication network, and keep communication quality good. <P>SOLUTION: A mobile communication terminal is provided with an inner loop control unit 13 which measures SIR (Signal-to Interference power Ratio) of a received signal from a mobile communication network, and notifies a transmission power control command which controls transmission power of the mobile communication network to the mobile communication network responding to a comparison result of the SIR and the target SIR; an outer loop control unit 14 which measures a BLER (Block Error Rate), and establishes the target SIR according to the comparison result of the BLER and a target BLER; and a target BLER change unit 17 which notifies the mobile communication network of a change request message which requests change of the target BLER based on predetermined conditions, and changes the target BLER when the change of the target BLER is permitted by the mobile communication network. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mobile communication technique using a code division multiplex communication system (CDMA) system, and more particularly to a mobile communication terminal and a mobile communication system that control downlink transmission power.

  The downlink transmission power control in the CDMA system needs to maintain the downlink communication quality while suppressing the transmission power of the base station. Thus, a method is used in which target quality is provided for a service (bearer) with which a mobile communication terminal is communicating, and transmission power of a base station is controlled so that downlink communication quality follows the target quality. Specifically, in a mobile communication terminal using a CDMA system, a closed loop transmission power control method including inner loop control and outer loop control is used.

  In the inner loop control, the SIR (Signal-to-Interference power Ratio) of the communication channel received by the mobile communication terminal is controlled to a certain target value, whereas in the outer loop control, the communication quality (BER ( The target SIR is controlled so that the target value is (Bit Error Rate) or BLER (Block Error Rate)). A TPC (Transmit Power Control) bit for controlling the transmission power of the base station is determined on the uplink physical channel from the mobile communication terminal to the base station according to the comparison result between the SIR of the received communication channel and the target SIR. Sent.

Various improved techniques have been proposed for such a closed-loop transmission power control method. Specifically, a technique for jumping up the target SIR by a certain amount at a predetermined timing has been proposed in order to reduce the probability of failing to receive specific data in the mobile communication terminal (see Patent Document 1). For the purpose of performing highly accurate transmission power control, a technique has been proposed in which the transmission power adjustment width is made variable by changing and controlling the TPC bit in the mobile communication terminal (see Patent Document 2).
JP 2004-112097 A JP 2006-173937 A

  However, in the background art described above, it is possible to temporarily improve communication quality, but it is impossible to maintain good communication quality. Furthermore, in the background art described above, since the target SIR or TPC bit is changed and controlled regardless of the resources on the mobile communication network side, even if there is a margin in resources such as subscriber capacity on the mobile communication network side. I couldn't make effective use of that margin.

  In view of the above problems, an object of the present invention is to provide a mobile communication terminal and a mobile communication system that can effectively use resources of a mobile communication network and can maintain good communication quality.

  In order to achieve the above object, a first feature of the present invention is to measure a first reception quality that is a quality of a received signal from a mobile communication network, and to obtain a first reception quality and a target value of the first reception quality. An inner loop control unit that notifies the mobile communication network of a transmission power control command for controlling the transmission power of the received signal according to the result of comparison with the first target quality, and reception in a period longer than the first reception quality The second reception quality that is the quality of the signal is measured, and the first target quality is determined according to the comparison result between the second reception quality and the second target quality that is a target value specified in advance by the mobile communication network. When a change request message for requesting a change of the second target quality is notified to the mobile communication network based on the outer loop control unit to be set and a predetermined condition, and the change of the second target quality is permitted by the mobile communication network First And summarized in that and a target quality changing unit for changing the target quality.

  Here, “first reception quality” means, for example, SIR, and “second reception quality” means, for example, BER or BLER. The power control command means, for example, a TPC bit.

  According to this feature, the target quality changing unit notifies the mobile communication network of a change request message for requesting the change of the second target quality (for example, the target BLER) based on a predetermined condition, and the second change is made by the mobile communication network. By changing the second target quality when the change of the target quality is permitted, it is possible to utilize the resources of the mobile communication network and keep the reception quality good.

  The second feature is that the mobile communication terminal according to the first feature further comprises a communication environment detection unit for detecting the communication environment of the terminal based on the received signal, and the target quality changing unit detects deterioration of the communication environment. In this case, the gist is to request the mobile communication network to change the second target quality.

  According to this feature, when the deterioration of the communication environment is detected, the communication quality can be automatically improved according to the communication environment of the own terminal by requesting the mobile communication network to change the second target quality. it can.

  The gist of the third feature is that, in the mobile communication terminal according to the first feature, the target quality changing unit requests the mobile communication network to change the second target quality in response to a user input.

  According to this feature, the target quality changing unit can improve the communication quality at the user's discretion by requesting the mobile communication network to change the second target quality in accordance with the user input.

  A fourth feature is a mobile communication system having a mobile communication network and a mobile communication terminal, wherein the mobile communication terminal measures a first reception quality which is a quality of a received signal from the mobile communication network, and also receives a first reception. An inner loop control unit for notifying the mobile communication network of a transmission power control command for controlling the transmission power of the received signal according to the result of comparison between the quality and the first target quality that is the target value of the first reception quality; The second received quality, which is the quality of the received signal in a period longer than the first received quality, is measured, and the second received quality is compared with the second target quality that is a target value specified in advance by the mobile communication network. Based on the result, an outer loop control unit for setting the first target quality and a change request message for requesting the change of the second target quality are notified to the mobile communication network based on a predetermined condition. And a target quality changing unit that changes the second target quality when the change of the second target quality is permitted. When the mobile communication network receives the change request message from the mobile communication terminal, Based on this, the gist is to determine whether or not to permit the change of the second target quality.

  According to this feature, similarly to the first feature, it is possible to use the resources of the mobile communication network and maintain good reception quality.

  According to a fifth feature, in the mobile communication system according to the fourth feature, when the mobile communication network receives a change request message from the mobile communication terminal, the mobile communication network 2 The gist is to determine whether or not to allow the change of the target quality.

  According to this feature, when the mobile communication network receives a change request message from the mobile communication terminal, whether to permit the change of the second target quality based on the traffic amount in the area where the mobile communication terminal is located. It is possible to appropriately determine whether or not to allow the mobile communication terminal to change the second target quality.

  ADVANTAGE OF THE INVENTION According to this invention, the mobile communication terminal and mobile communication system which can utilize the resource of a mobile communication network effectively and can maintain communication quality favorable can be provided.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(Example of overall configuration of mobile communication system)
The mobile communication system according to the present embodiment includes a mobile communication terminal 1 and a mobile communication network 5 as shown in FIG. FIG. 1 shows a W-CDMA mobile communication system. Further, the mobile communication network 5 includes base stations 2 a and 2 b, a base station controller (RNC) 3, and a core network 4.

  The core network 4 is a network for performing position control, call control, and service control in the mobile communication system, and includes, for example, an ATM switching network, a packet switching network, a router network, and the like. The core network 4 is also connected to other public networks (PSTN) or the like, and the mobile communication terminal 1 can communicate with a fixed telephone or the like.

  The base station control device 3 functions as a host device of the base stations 2a and 2b, and manages radio resources used by the base stations 2a and 2b. In addition, the base station control device 3 has a function of executing transmission power control (outer loop control) described later, and receives signals from the mobile communication terminals 1 from the subordinate base stations 2a and 2b during handover, It also has a handover control function for selecting data with better quality and sending it to the core network 4 side.

  The base stations 2 a and 2 b manage radio resources by the base station control device 3 and perform radio communication with the mobile communication terminal 1. The base stations 2a and 2b also have a function of executing transmission power control (inner loop control) described later.

  In some cases, the functions of the base station control device 3 are incorporated in the base stations 2a and 2b, and the base stations 2a and 2b execute the functions of the base station control device 3.

  The mobile communication terminal 1 establishes a radio line with the base stations 2a and 2b by being located in the radio area of each base station 2a and 2b, and communicates with other communication devices via the core network 4 Communicate between each other. Furthermore, the mobile communication terminal 1 has an inner loop control function and an outer loop control function.

  That is, the mobile communication terminal 1 measures the SIR of the received signal from the mobile communication network 5 and sends the TPC bit (power control command) according to the result of comparison between the measured SIR and the target SIR. Notify 5 side. Further, the mobile communication terminal 1 measures the BLER of the received signal, and sets the target SIR according to the result of comparison between the measured BLER and the target BLER.

  Furthermore, the mobile communication terminal 1 detects the communication environment of its own terminal based on the received signal and requests the mobile communication network 5 to reduce the target BLER when it detects the deterioration of the communication environment. Here, “communication environment” means, for example, downlink interference amount, noise amount, SIR, BLER, BER, or Ec / No. Note that Ec / No is the ratio of energy per in-band received power density to the desired wave. When such a value indicating the communication environment is smaller than a preset threshold value, it is determined that the communication environment has deteriorated.

(Example of overall operation of mobile communication system)
Next, an overall operation example of the mobile communication system will be described. FIG. 2 is a sequence diagram showing an operation example of the mobile communication system according to the present embodiment.

  As shown in steps S11 and S12, at the start of communication, the base station control device 3 sends a target BLER corresponding to a service (bearer) communicated with the mobile communication terminal 1 to the mobile communication terminal 1 via the base station 2a. Notice.

  In step S13, the mobile communication terminal 1 determines the communication environment based on downlink interference amount, noise amount, SIR, BLER, BER, Ec / No, or the like. Here, it is assumed that the value indicating the communication environment is smaller than a preset threshold value. For this reason, the mobile communication terminal 1 determines that the communication environment of its own terminal has deteriorated.

  In step S14 and step S15, the mobile communication terminal 1 notifies the base station controller 3 of a change request message for requesting change of the target BLER via the base station 2a. For example, when the target BLER notified in step S11 and step S12 is 5%, the target BLER is changed to a lower value (4%, 3%, 2%, etc.). Means that.

  In step S <b> 16, the base station control device 3 determines whether to permit the change of the target BLER based on a predetermined standard. Here, the “predetermined reference” means, for example, the traffic amount in the area where the mobile communication terminal 1 is located. That is, when the amount of traffic in the area where the mobile communication terminal 1 is located is larger than a certain threshold value, the transmission power to the mobile communication terminal 1 cannot be increased, so the base station control device 3 changes the target BLER. I refuse. On the other hand, when the traffic volume in the area where the mobile communication terminal 1 is located is smaller than a certain threshold value, the transmission power for the mobile communication terminal 1 can be increased, so the base station control device 3 changes the target BLER. to approve.

  In steps S17 and S18, the base station control device 3 notifies the mobile communication terminal 1 via the base station 2a of a message indicating whether or not the change of the target BLER is permitted according to the determination result of step S16. . Here, it is assumed that the base station control device 3 notifies the mobile communication terminal 1 of a message indicating that the change of the target BLER is permitted via the base station 2a.

  In step S19, the mobile communication terminal 1 determines whether or not to change the target BLER based on the message notified in step S18. In step S18, since the message indicating that the change of the target BLER is permitted is received, the mobile communication terminal 1 changes the target BLER.

  In step S20, the mobile communication terminal 1 performs outer loop control and inner loop control using the changed target BLER, and transmits a TPC bit to the base station 2a.

  In step S22, the base station 2a changes the transmission power of the dedicated channel for the mobile communication terminal 1 according to the TPC bit received in step S20.

(Configuration example of mobile communication terminal)
Next, a configuration example of the mobile communication terminal 1 will be described. FIG. 3 is a functional block diagram of the mobile communication terminal 1.

  The mobile communication terminal 1 includes an antenna 100, a radio communication unit 10, a despreading unit 11, a RAKE receiving unit 12, an inner loop control unit 13, an outer loop control unit 14, a transmission signal generation unit 15, a signal A processing unit 16, a target BLER changing unit 17, a control unit 18, a communication environment detecting unit 23, a speaker 19, a microphone 20, an input unit 21, and a display unit 22 are provided.

  A reception signal received by the antenna 100 is input to the wireless communication unit 10 and down-converted. The despreading unit 11 performs a despreading process on the down-converted received signal using a scrambling code or a channelization code assigned from the mobile communication network 5 side. The RAKE receiving unit 12 performs RAKE combining and error correction / decoding on the received signal after the despreading process. The data series output from the RAKE receiving unit 12 is input to the signal processing unit 16, the outer loop control unit 14, and the inner loop control unit 13.

  The outer loop control unit 14 includes a long section quality measurement unit 141, a target BLER setting unit 143, a BLER comparison determination unit 142, and a target SIR setting unit. The inner loop control unit 13 includes a SIR measurement unit 131, a SIR comparison / determination unit 132, and a TPC bit generation unit 133.

  The long section quality measuring unit 141 measures BLER in a long section of about several hundred ms to several s, for example, according to the number of transport blocks having the same CRC result in the data series output from the RAKE receiving unit 12. The long interval quality measurement unit 141 notifies the BLER comparison determination unit 142 of the BLER obtained by this measurement.

  The target SIR setting unit sets the target BLER in the BLER comparison determination unit 142. The BLER comparison / determination unit 142 calculates a correction value for the target SIR as a value proportional to the difference between the measured BLER and the set target BLER value. The target SIR setting unit notifies the SIR comparison determination unit 132 of the target SIR value.

  Thereby, the target SIR increases when the measured BLER is larger than the target BLER value, that is, when the reception quality is poor, and decreases when the measured BLER value is smaller than the target BLER value, that is, when the reception quality is good. To do.

  The SIR measuring unit 131 measures the SIR based on the signal power value and the interference power value input from the RAKE receiving unit 12.

  The SIR comparison / determination unit 132 compares the SIR measured by the SIR measurement unit 131 with the target SIR set by the target SIR setting unit, and determines whether or not the measured SIR value is equal to or greater than the target SIR value. . The SIR comparison / determination unit 132 notifies the TPC bit generation unit 133 of the determination result.

  Based on the determination result of the SIR comparison / determination unit 132, the TPC bit generation unit 133 generates a TPC bit for increasing the transmission power when the measured SIR does not reach the target SIR, and the measured If the SIR is greater than or equal to the target SIR value, a TPC bit that reduces transmission power is generated.

  On the other hand, the data series from the RAKE receiving unit 12 is input to the signal processing unit 16 and subjected to orthogonal demodulation, decoding processing, error correction decoding, and the like, and then supplied to the control unit 18 as received data. As a result, the control unit 18 supplies an audio signal to the speaker 19 or supplies an image signal to the display unit 22.

  Further, the audio signal input to the microphone 20 is converted into a digital signal by the control unit 18 and supplied to the signal processing unit 16. The signal processing unit 16 performs compression processing, error correction coding processing, and the like on the data from the control unit 18 and supplies the data to the transmission signal generation unit 15.

  The transmission signal generator 15 multiplexes transmission data of various transmission channels. The multiplexed transmission data is supplied to the radio communication unit 10, subjected to modulation processing and spread spectrum processing, up-converted, and transmitted from the antenna 100.

  The input unit 21 is provided with a key group including various keys. The input unit 21 inputs user instructions by pressing these keys. An LCD or the like is used as the display unit 22.

  In addition, the control unit 18 controls the entire mobile communication terminal, acquires information on the communication environment described above, and notifies the communication environment detection unit 23 of the information. The communication environment detection unit 23 detects the communication environment described above based on the information notified from the control unit 18.

(Target BLER change request processing)
Next, a specific processing procedure of the target BLER change request processing by the mobile communication terminal 1 will be described. FIG. 4 is a flowchart showing a specific processing procedure of the target BLER change request processing.

  In step S101, the communication environment detection unit 23 determines the communication environment of the own terminal based on downlink interference amount, noise amount, SIR, BLER, BER, Ec / No, or the like.

  In step S102, the communication environment detection unit 23 determines whether or not the communication environment has deteriorated by comparing a value indicating the communication environment with a preset threshold value. When it is determined that the communication environment has deteriorated, the process proceeds to step S103.

  In step S <b> 103, the target BLER change unit 17 transmits a change request message for requesting change of the target BLER to the mobile communication network 5 side via the transmission signal generation unit 15, the wireless communication unit 10, and the antenna 100.

(Target BLER change process)
Next, a specific processing procedure of the target BLER change process by the mobile communication terminal 1 will be described. FIG. 5 is a flowchart showing a specific processing procedure of the target BLER change processing.

  In step S201, the target BLER changing unit 17 sends a message indicating whether or not the target BLER can be changed via the antenna 100, the despreading unit 11, the RAKE receiving unit 12, the signal processing unit 16, and the control unit 18. Receive from the side.

  In step S202, the target BLER changing unit 17 determines whether or not the message received in step S201 indicates permission to change the target BLER. When it is determined that the message received in step S201 indicates permission to change the target BLER, the process proceeds to step S203. On the other hand, when it is determined that the message received in step S201 indicates the target BLER change refusal, the process proceeds to step S204.

  In step S203, the target BLER changing unit 17 changes the target BLER. Here, as a method for changing the target BLER, for example, the following two methods can be used. 1) Select one of the target BLER options prepared in advance. 2) The target BLER is continuously changed. As will be described later, the target BLER may be designated by the user.

  On the other hand, in step S204, the target BLER changing unit 17 maintains the previous value without changing the value of the target BLER.

(Configuration example of base station controller)
Next, a configuration example of the base station control device 3 will be described. FIG. 6 is a functional block diagram of the base station control device 3.

  The base station control device 3 includes a first communication I / F 31, a second communication I / F 32, a base station control unit 33, a traffic amount detection unit 34, a target BLER control unit 35, and a target BLER storage unit 36. Is provided.

  The first communication I / F 31 exchanges various data with the base stations 2a and 2b in FIG. The second communication I / F 32 exchanges various data with the core network 4.

  The base station control unit 33 performs radio channel control, resource control, and the like of the base stations 2a and 2b, and performs radio channel control, resource control, bearer control, and the like of the mobile communication terminal 1. The traffic amount detection unit 34 detects the traffic amount in the area where the mobile communication terminal 1 is located.

  The target BLER storage unit 36 holds the target BLER for each bearer as shown in FIG. The target BLER control unit 35 receives the target BLER change request from the mobile communication terminal 1 and determines whether or not to permit the target BLER change request according to the traffic amount detected by the traffic amount detection unit 34.

(Target BLER change determination process)
Next, a specific processing procedure of the target BLER change determination process by the base station control device 3 will be described. FIG. 8 is a flowchart showing a specific processing procedure of the target BLER change determination process.

  In step S <b> 301, the target BLER control unit 35 receives a target BLER change request from the mobile communication terminal 1 via the first communication I / F 31.

  In step S302, the target BLER control unit 35 determines whether or not to permit the target BLER change request according to the traffic volume detected by the traffic volume detection unit 34. When it determines with permitting a target BLER change request | requirement, it transfers to step S303. On the other hand, if it is determined to reject the target BLER change request, the process proceeds to step S304.

  In step S303, the target BLER control unit 35 notifies the mobile communication terminal 1 via the first communication I / F 31 of a message indicating that the change of the target BLER is permitted.

  In step S304, the target BLER control unit 35 notifies the mobile communication terminal 1 of a message indicating that the change of the target BLER is rejected via the first communication I / F 31.

(Action / Effect)
As described above in detail, according to the present embodiment, the mobile communication terminal 1 notifies the mobile communication network 5 of a change request message for requesting the change of the target BLER, and the mobile communication network 5 changes the target BLER. If the target BLER is changed, resources on the mobile communication network 5 side can be effectively used to maintain good communication quality.

  Further, according to the present embodiment, when the mobile communication terminal 1 detects the deterioration of the communication environment, the mobile communication terminal 1 automatically requests the mobile communication network 5 to change the target BLER, so that the communication environment of the own terminal is set. The communication quality can be automatically improved accordingly.

  Furthermore, according to the present embodiment, when the mobile communication network 5 receives a change request message from the mobile communication terminal 1, the change of the target BLER is permitted based on the traffic amount in the area where the mobile communication terminal 1 is located. By determining whether or not to do so, it is possible to appropriately determine whether or not the mobile communication terminal 1 is allowed to change the target BLER.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the configuration in which the target BLER change request is automatically performed has been described. However, the target BLER change request may be manually performed. The case where the target BLER change request is manually performed will be described below.

  FIG. 9 is a flowchart showing a processing procedure when the target BLER change request is manually performed.

  In step S401, the control unit 18 illustrated in FIG. 3 displays a communication quality adjustment screen as illustrated in FIG. 10 on the display unit 22 in accordance with the user input received by the input unit 21. In the example of FIG. 10, the communication quality “high” is to change the target BLER to about 1%, and the communication quality “medium” is to change the target BLER to about 2.5%, for example. The quality “low” is, for example, changing the target BLER to about 4%.

  In step S402, the input unit 21 receives user input for selecting communication quality.

  In step S403, the target BLER changing unit 17 notifies the mobile communication network 5 side of a change request message according to the communication quality selected in step S402.

  According to such an embodiment, the target BLER changing unit 17 may request the mobile communication network 5 to change the target BLER in response to a user input, thereby improving the communication quality at the user's discretion. it can.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

It is a figure which shows the example of whole structure of the mobile communication system which concerns on embodiment of this invention. It is a sequence diagram which shows the operation | movement outline | summary of the whole mobile communication system which concerns on embodiment of this invention. It is a functional block diagram which shows the structural example of the mobile communication terminal which concerns on embodiment of this invention. It is a flowchart which shows the example of a process sequence of the target BLER change request process in the mobile communication terminal which concerns on embodiment of this invention. It is a flowchart which shows the process sequence example of the target BLER change process in the mobile communication terminal which concerns on embodiment of this invention. It is a functional block diagram which shows the structural example of the base station control apparatus which concerns on embodiment of this invention. It is a figure which shows the table structural example of the target BLER which the base station control apparatus which concerns on embodiment of this invention memorize | stores for every bearer. It is a flowchart which shows the process sequence example of the target BLER change determination process in the base station control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the example of a process sequence of the target BLER change request process in the mobile communication terminal which concerns on other embodiment. It is a schematic diagram which shows the example of a communication quality adjustment screen in the mobile communication terminal which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mobile communication terminal 2a, 2b ... Base station 3 ... Base station control apparatus 4 ... Core network 5 ... Mobile communication network 10 ... Wireless communication part 11 ... Despreading part 12 ... RAKE receiving part 13 ... Inner loop control part 14 ... Outer Loop control unit 15 ... transmission signal generation unit 16 ... signal processing unit 17 ... target BLER change unit 18 ... control unit 19 ... speaker 20 ... microphone 21 ... input unit 22 ... display unit 23 ... communication environment detection unit 31 ... first communication I / F
32 ... Second communication I / F
33 ... Base station control unit 34 ... Traffic volume detection unit 35 ... Target BLER control unit 36 ... Target BLER storage unit 100 ... Antenna 131 ... SIR measurement unit 132 ... SIR comparison / determination unit 133 ... TPC bit generation unit 141 ... Long section quality measurement Part 142 ... BLER comparison determination part 143 ... Target BLER setting part

Claims (5)

In accordance with a result of comparison between the first reception quality that is the quality of the received signal from the mobile communication network and the first target quality that is the target value of the first reception quality, An inner loop control unit for notifying the mobile communication network of a transmission power control command for controlling the transmission power of the received signal;
The second reception quality that is the quality of the received signal in a period longer than the first reception quality is measured, and the second reception quality and a second target quality that is a target value specified in advance by the mobile communication network According to the result of the comparison with the outer loop control unit for setting the first target quality,
Based on a predetermined condition, a change request message for requesting the change of the second target quality is notified to the mobile communication network, and when the change of the second target quality is permitted by the mobile communication network, the second target quality is changed. A mobile communication terminal comprising: a target quality changing unit that changes the target quality. Based on the received signal, further comprises a communication environment detection unit for detecting the communication environment of the terminal itself,
The mobile communication terminal according to claim 1, wherein the target quality changing unit requests the mobile communication network to change the second target quality when the deterioration of the communication environment is detected.   The mobile communication terminal according to claim 1, wherein the target quality changing unit requests the mobile communication network to change the second target quality in response to a user input. A mobile communication system having a mobile communication network and a mobile communication terminal,
The mobile communication terminal is
According to a result of comparison between the first reception quality that is the quality of the received signal from the mobile communication network and the first target quality that is the target value of the first reception quality. An inner loop control unit for notifying the mobile communication network of a transmission power control command for controlling transmission power of the received signal;
The second reception quality that is the quality of the received signal in a period longer than the first reception quality is measured, and the second reception quality and a second target quality that is a target value specified in advance by the mobile communication network According to the result of the comparison with the outer loop control unit for setting the first target quality,
Based on a predetermined condition, a change request message for requesting the change of the second target quality is notified to the mobile communication network, and when the change of the second target quality is permitted by the mobile communication network, the second target quality is changed. A target quality change unit for changing the target quality,
When the mobile communication network receives the change request message from the mobile communication terminal, the mobile communication network determines whether to permit the change of the second target quality based on a predetermined criterion. system.   When the mobile communication network receives the change request message from the mobile communication terminal, whether to permit the change of the second target quality based on the traffic volume in the area where the mobile communication terminal is located The mobile communication system according to claim 4, wherein the determination is made.

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