JP2013102479A - Mobile communication system, base station apparatus, mobile station device, and communication control method - Google Patents

Abstract

【Task】
Reduce inter-carrier interference so that all frequencies can be used even near the cell edge.
[Solution]
When an interference signal that causes inter-carrier interference is detected, the mobile station 14 notifies the communicating base station 12-1 (S100). The base station 12-1 sequentially requests the adjacent base stations 12-2, 3... To suspend wireless transmission until notified by the mobile station 14 that the interference signal power has been reduced (S102). , S110). When the power of the detected interference signal is reduced, the mobile station 14 notifies the reduction amount to the base station 12-1 (S116). At this time, the base station 12-1 estimates that the base station 12-3 that requested the temporary stop of radio transmission immediately before S116 is a source of the interference signal detected by the mobile station 14. Then, the base station 12-3 is requested to reduce the transmission power by the reduction amount notified in S116 (S118).
[Selection] Figure 5

Description

  The present invention relates to a mobile communication system, a base station apparatus, a mobile station apparatus, and an interference reduction method, and more particularly to a technique for reducing inter-carrier interference that is likely to occur in the vicinity of a cell edge due to a transmission wave from a nearby base station apparatus.

  In the OFDMA (Orthogonal Frequency Division Multiple Access) scheme, if the orthogonality between subcarriers is lost, inter-carrier interference occurs, and demodulation of the OFDM signal becomes difficult. For this reason, in a mobile communication system in which each base station adopting the OFDMA scheme communicates using a predetermined total frequency, a cell design is performed so that ranges using all frequencies do not overlap between adjacent base stations. Interference is prevented from occurring (see, for example, Non-Patent Document 1).

Mobile WiMAX- Part I: A Technical Overview and Performance Evaluation [online], WiMAX FORUM, 2006, p27-29. Retrieved from the Internet: <URL: http: //www.intel.com/netcomms/technologies/wimax/WiMAX_Overview_v2 .pdf>

  However, in the conventional mobile communication system, communication using all frequencies cannot be performed in the vicinity of the cell edge, so that use of radio resources is wasted.

  The present invention has been made in view of the above-described conventional problems, and a mobile communication system, a base station apparatus, and a mobile station apparatus that can reduce inter-carrier interference so that all frequencies can be used even near the cell edge. And an interference reduction method.

  In order to solve the above problems, a mobile communication system according to the present invention is a mobile communication system including a plurality of base station apparatuses that communicate with a mobile station apparatus using an orthogonal frequency division multiple access scheme, and the mobile station apparatus includes: Detecting an interference signal that interferes with a channel used for communication with the base station apparatus based on the received signal, and detecting the interference signal when the interference detection means detects the interference signal. An interference notification means for notifying the base station apparatus, and an interference power reduction amount notification for notifying the base station apparatus of a reduction amount of the interference signal power when the power of the interference signal detected by the interference detection means is reduced. And the base station apparatus is configured to receive a notification from the interference notification means until receiving a notification from the interference power reduction amount notification means. Next, when receiving a notification from the transmission stop request means for requesting the suspension of radio transmission and the interference power reduction amount notification means, the base station from which the transmission stop request means has requested a pause of the radio transmission immediately before Transmission power reduction requesting means for requesting the apparatus to reduce the transmission power of each channel by a reduction amount related to the notification.

  According to the present invention, when an interference signal that causes inter-carrier interference is detected in a mobile station device, the base station device that communicates with the mobile station device is in close proximity to the adjacent base station device until the interference signal power is reduced. In response to this, the wireless transmission is requested to be temporarily stopped. At this time, when a reduction in interference signal power is confirmed in the mobile station apparatus, the base station apparatus that has temporarily stopped radio transmission immediately before that is the source (interference source) of the interference signal detected by the mobile station apparatus It is estimated to be. Then, the base station apparatus estimated to be the interference source reduces its transmission power by the amount of interference signal power detected by the mobile station apparatus. In this way, even if inter-carrier interference occurs in the mobile station device, the transmission power of the interference signal that causes it is immediately reduced, so the cell edge where the transmission wave (interference wave) from the adjacent base station device is easy to reach Communication can be performed using all frequencies even in the vicinity.

  In the aspect of the present invention, the interference power reduction amount notifying unit may reduce the interference signal power reduction amount and the reduced interference signal when the interference signal power detected by the interference detection unit is reduced. When the interference power information indicating the channel is notified to the base station apparatus, and the transmission power reduction requesting unit is notified by the interference power reduction amount notifying unit, the transmission stop requesting unit immediately stops the wireless transmission temporarily. The base station apparatus that has requested the stop is requested to reduce the transmission power of the channel indicated by the interference channel information related to the notification by the reduction amount related to the notification. According to this aspect, since only the transmission power of the channel related to the interference signal that causes the inter-carrier interference is reduced, it is possible to suitably reduce the inter-carrier interference while suppressing the reduction amount of the transmission power in the base station apparatus.

  The mobile station apparatus according to the present invention is a mobile station apparatus that communicates with a base station apparatus using an orthogonal frequency division multiple access scheme, and that interferes with a channel used for communication with the base station apparatus based on a received signal. An interference detection means for detecting an interference signal that gives an interference signal, an interference notification means for notifying the base station apparatus of the detection of the interference signal when the interference detection means detects the interference signal, and the interference detection means Interference power reduction amount notification means for notifying the base station apparatus of a reduction amount of the interference signal power when the power of the interference signal is reduced.

  The base station apparatus according to the present invention is a base station apparatus that communicates with a mobile station apparatus by an orthogonal frequency division multiple access method, and the mobile station apparatus receives notification of detection of an interference signal from the mobile station apparatus. Until the notification of the reduction amount of the interference signal power is sent by the mobile station device, the transmission stop request means for sequentially requesting the temporary stop of the radio transmission to the adjacent base station device, and the reduction amount of the interference signal power by the mobile station device. A transmission power reduction requesting unit for requesting the base station apparatus that has requested temporary suspension of wireless transmission immediately before the transmission stop requesting unit to reduce the transmission power of each channel by the reduction amount when notified. , Including.

  The communication control method according to the present invention is an interference reduction method for reducing interference waves to a mobile station device that communicates with a base station device using an orthogonal frequency division multiple access method, wherein the mobile station device receives a received signal. Based on an interference detection step for detecting an interference signal that interferes with a channel used for communication with the base station device, and detecting an interference signal when the interference signal is detected in the interference detection step. An interference notification step for notifying the base station apparatus when the power of the interference signal detected in the interference detection step is reduced, and notifying the base station device of the reduction amount of the interference signal power. Including, until the base station apparatus receives the notification in the interference notification step until the base station apparatus receives the notification in the interference power reduction amount notification step. Then, when receiving the notification by the transmission stop request step for requesting the temporary stop of the radio transmission and the interference power reduction amount notifying step, the temporary stop of the radio transmission is requested in the previous transmission stop request step. A transmission power reduction requesting step for requesting the base station apparatus to reduce the transmission power of each channel by a reduction amount related to the notification.

1 is an overall configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a block diagram of the mobile station which concerns on embodiment of this invention. It is a block diagram of the base station which concerns on embodiment of this invention. It is a figure which shows an example of the information memorize | stored in a request | requirement state memory | storage part. It is a sequence diagram which shows the process of the mobile communication system which concerns on embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a mobile communication system 10 according to an embodiment of the present invention. As shown in the figure, the mobile communication system 10 includes a plurality of base stations 12 (only the base stations 12-1 to 7 are shown here) and a plurality of mobile stations 14 (only one is shown here). It is comprised including. The mobile station 14 is, for example, a portable mobile phone, a portable information terminal, or a data communication card.

  As shown in FIG. 1, each base station 12 is arranged such that an end (cell edge) of a cell 16 indicating a communication coverage area overlaps an end of its adjacent cell. For example, the cell 16-1 of the base station 12-1 has areas overlapping with the cells 16-2 to 7-7 of the adjacent base stations 12-2 to 7-7, respectively. Each base station 12 transmits / receives a radio signal to / from the mobile station 14 located in the own cell by a TDD (Time Division Duplex) method, and also uses OFDMA (Orthogonal Frequency Division Multiple Access). Multiplex communication is performed by a multiple access) method and a TDMA (Time Division Multiple Access) method.

  The radio transmission path between the base station 12 and the mobile station 14 is composed of a reception frame and a transmission frame each including a plurality of time slots (for example, 4 slots) by time division multiplexing. In addition, for each time slot, a plurality of subchannels (for example, 28 subchannels) composed of a plurality of subcarriers (for example, 16 subcarriers) by orthogonal division multiplexing are defined. A channel used for each communication is specified by a channel number for identifying a channel or a combination of a slot number for identifying a time slot and a subchannel number for identifying a subchannel frequency.

  In the mobile communication system 10, when an interference signal that causes inter-carrier interference is detected in the mobile station 14, the base station 12 communicating with the mobile station 14 communicates with the adjacent base station 12 until the interference signal power is reduced. Sequentially request for temporary suspension of wireless transmission. Here, when the reduction of the interference signal power is confirmed in the mobile station 14, the base station 12 that temporarily stopped the radio transmission immediately before is the source (interference source) of the interference signal detected by the mobile station 14. Presumed. Then, the base station 12 estimated to be an interference source reduces its transmission power by the amount of interference signal power reduction in the mobile station 14. Thus, in the mobile communication system 10, even if inter-carrier interference occurs in the mobile station 14, the transmission power of the interference signal that causes it is immediately reduced. Communication can be performed using all the frequencies in the channel configuration even near the cell edge where it is easy.

  Below, the structure and function for implement | achieving the said process are demonstrated in detail based on FIGS.

  FIG. 2 is a block diagram of the mobile station 14. As shown in the figure, the mobile station 14 includes an antenna 20, a radio unit 22, an IFFT (Inverse Fast Fourier Transform) unit 24, an FFT (Fast Fourier Transform) unit 26, a baseband signal. The processing unit 28 and the control unit 38 are included.

  The antenna 20 radiates a radio signal supplied from the radio unit 22, receives a radio signal transmitted from the mobile station 14 or the adjacent base station 12, and outputs the received radio signal to the radio unit 22. . Note that transmission and reception are switched in a time division manner.

  The radio unit 22 down-converts a radio signal received by the antenna 20 into a baseband signal. The baseband signal is subjected to symbol synchronization, guard interval removal, conversion to a digital signal, and the like, and the obtained digital signal is output to the FFT unit 26.

  The radio unit 22 also converts the digital signal input from the IFFT unit 24 into an analog signal, adds a guard interval, and the like to acquire a baseband signal, and wirelessly transmits the obtained baseband signal. Supplied to the unit 22.

  The IFFT unit 24 converts the complex symbol sequence input from the baseband signal processing unit 28 (mapping unit 30) into a digital signal by inverse fast Fourier transform (IFFT), and outputs the converted digital signal to the radio unit 22. .

  The FFT unit 26 converts the digital signal input from the radio unit 22 into a complex symbol sequence representing the phase and amplitude of each subcarrier by fast Fourier transform (FFT), and the converted complex symbol sequence is a baseband signal processing unit. It outputs to 28 (demapping part 32).

  The baseband signal processing unit 28 includes a mapping unit 30, a demapping unit 32, and an interference detection unit 34. The baseband signal processing unit 28 includes a transmission / reception message and a complex symbol sequence representing the phase and amplitude of each subcarrier in the baseband signal. Convert between each other.

  The mapping unit 30 converts the transmission message (binary data) input from the control unit 38 into a corresponding complex symbol sequence according to the modulation scheme, and outputs the converted complex symbol sequence to the IFFT unit 24.

  The demapping unit 32 converts the complex symbol sequence input from the FFT unit 26 into a corresponding received message (binary data) according to the modulation method, and converts the converted received message to the interference detection unit 34 and the control unit 38. Output.

  The interference detection unit 34 includes a correlation calculation unit 36 and detects an interference signal that interferes with a channel used for communication with the base station 12 based on the received message input from the demapping unit 32. Specifically, the correlation value between the received message (binary data) input from the demapping unit 32 and the known reference signal (binary data) stored in the interference detection unit 34, which is calculated by the correlation calculation unit 36. Based on this, an interference signal component included in the received signal is detected (extracted). When the interference signal is thus detected, the interference detection unit 34 notifies the control unit 38 of the channel and power (interference level) of the interference signal.

  The control unit 38 includes a CPU, a memory, and the like, and controls each unit of the mobile station 14. In addition, processing related to a transmission / reception message exchanged with the baseband signal processing unit 28 is performed. In particular, the base station 12 is notified of information relating to the interference signal detected by the interference detection unit 34, including the interference information notification unit 40. These functions are realized by the CPU executing various control programs stored in the memory.

  When the interference detection unit 34 detects an interference signal, that is, when the interference signal power notified from the interference detection unit 34 is greater than or equal to a predetermined value, the interference information notification unit 40 determines whether or not the interference signal is detected. By rewriting a predetermined portion in the transmission message shown, the base station 12 in communication is notified that an interference signal has been detected. Further, when the interference signal power notified from the interference detection unit 34 after notification of the fact is reduced, the interference information notification unit 40 indicates the interference channel information indicating the reduction amount of the interference signal power and the channel of the reduced interference signal ( The channel number related to the interference signal, the combination of the slot number and the subchannel number related to the interference signal) is stored in a predetermined part in the transmission message, and the base station that is communicating the reduction amount of the interference signal power and the interference channel information 12 is notified.

  FIG. 3 is a block diagram of the base station 12. As shown in the figure, the base station 12 includes an antenna 50, a radio unit 52, an IFFT unit 54, an FFT unit 56, a baseband signal processing unit 58, a communication I / F unit 64, a control unit 66, and a request state storage unit 72. It is comprised including. In addition, the antenna 50, the radio | wireless part 52, IFFT part 54, and the FFT part 56 in the same figure are respectively the same structures and functions as the antenna 20, the radio | wireless part 22, the IFFT part 24, and the FFT part 26 of the mobile station 14 in FIG. Therefore, the detailed description is omitted here.

  The baseband signal processing unit 58 includes a mapping unit 60 and a demapping unit 62, and mutually converts a transmission / reception message and a complex symbol sequence representing the phase and amplitude of each subcarrier in the baseband signal. It is.

  The mapping unit 60 corresponds to the complex corresponding to the transmission message (binary data) input from the communication I / F unit 64 and the known reference signal (binary data) stored in the baseband signal processing unit 58 according to the modulation method. The symbol string is converted into a symbol string, and the converted complex symbol string is output to IFFT section 54.

  The demapping unit 62 converts the complex symbol sequence input from the FFT unit 56 into a corresponding received message (binary data) according to the modulation method, and converts the converted received message into the communication I / F unit 64 and the control unit. 66. Further, the transmission power for each subchannel is controlled in accordance with an instruction from a transmission control unit 70 described later.

  The communication I / F unit 64 outputs a transmission message transmitted from a host device (not shown) via a communication line (wired line or wireless line) to the mapping unit 60 and transmits a transmission stop request transmitted from the adjacent base station 12 A message and a transmission power reduction request message (described later) are output to control unit 66. In addition, the reception message input from the demapping unit 62 is output to the host device, and the transmission stop request message and the transmission power reduction request message are transmitted to the designated adjacent base station 12 according to the instruction of the control unit 66.

  The control unit 66 includes a CPU, a memory, and the like, and controls each unit of the base station 12. Further, based on the received message output from the demapping unit 62, whether or not there is a notification from the communicating mobile station 14 that an interference signal has been detected, and the interference signal power detected at the mobile station 14 is reduced. It is determined whether or not there has been a notification to the effect, or a reduction amount of interference signal power, interference channel information, and the like are extracted from a predetermined portion of the received message.

  Furthermore, the control unit 66 includes a transmission control request unit 68 and a transmission control unit 70. When an interference signal is detected in the mobile station 14 that is in communication, the control unit 66 temporarily stops the radio transmission or transmits the transmission power to the adjacent base station 12. In response to a request from the adjacent base station 12, the wireless transmission is temporarily stopped or transmission power is reduced. These functions are realized by the CPU executing various control programs stored in the memory.

  The transmission control requesting unit 68 receives the notification that the interference signal has been detected by the mobile station 14 in communication until the notification that the detected interference signal has been reduced until the adjacent base station 12 receives the notification. Sequentially, a temporary stop of wireless transmission is requested. Specifically, with respect to the adjacent base station 12 whose request state stored in the request state storage unit 72, which will be described later, is “unrequested”, at a predetermined interval in order from the smallest reference number (for example, every frame) A transmission stop request message addressed to each adjacent base station 12 is created so as to request a temporary stop of radio transmission, and is output to the communication I / F unit 64.

  When the transmission control request unit 68 receives a notification that the interference signal power has been reduced by the mobile station 14 (including the reduction amount of the interference signal power and the interference channel information), the transmission control request unit 68 requests to pause the radio transmission immediately before that. The requested adjacent base station 12 is requested to reduce the transmission power of the channel indicated by the notified interference channel information by the notified reduction amount. Specifically, the amount of reduction of the interference signal power to the base station 12 having the largest reference number among the adjacent base stations 12 whose request state stored in the request state storage unit 72 described later is “Requested” and A transmission power reduction request message including interference channel information is created and output to communication I / F unit 64.

  FIG. 4 is a diagram illustrating an example of information stored in the request state storage unit 72. As shown in the figure, the request state storage unit 72 stores, for each base station ID that identifies an adjacent base station 12, a request state and request contents relating to a message transmitted to the base station 12. . Here, the request states “requested”, “in request”, and “unrequested” in the same figure are “state in which a response to the transmission stop request message has been received” and “transmission stop request message, respectively. “Not received” and “Not transmitting transmission stop request message”. The request state and request contents in the request state storage unit 72 are obtained when the transmission control request unit 68 makes a request to the adjacent base station 12 and receives a response from the adjacent base station 12 that made the request. For example, it is updated by the control unit 66. The request contents shown in the figure are used for later operation analysis and more advanced request operations, and are not essential information.

  The transmission control unit 70 suspends wireless transmission or reduces transmission power according to a request from the adjacent base station 12. In other words, when receiving a transmission stop request message from the adjacent base station 12, the transmission control unit 70 instructs the wireless unit 52 to temporarily stop wireless transmission of all subchannels (for example, only one frame), and perform wireless transmission. Is returned to the sender of the transmission stop request message.

  Further, when receiving the transmission power reduction request message from the adjacent base station 12, the transmission control unit 70 is configured to reduce the transmission power of the channel indicated by the interference channel information included in the message by a reduction amount included in the message. The band signal processing unit 58 (mapping unit 60) is instructed.

  Note that the transmission control unit 70 sets a CNR (Carrier to Noise Ratio) necessary for ongoing communication on the channel indicated by the interference channel information as a lower limit, and does not lower the transmission power below that. It may be. In addition, the transmission control request unit 68 may create a transmission power reduction request message including only the reduction amount of the interference signal power. In this case, the transmission control unit 70 determines that the transmission power of all subchannels is The wireless unit 52 is instructed to reduce the amount of reduction included in the message.

  Next, operations of the base station 12 and the mobile station 14 in the mobile communication system 10 will be described with reference to FIG.

  FIG. 5 is a sequence diagram showing processing of the mobile communication system 10. Here, the mobile station 14 in communication with the base station 12-1 is located in an area where the cell 16-1 of the base station 12-1 and the cell 16-3 of the base station 12-3 overlap (FIG. 1). For example, a case where inter-carrier interference occurs in the mobile station 14 due to a transmission wave from the base station 12-3 will be described.

  In this case, the mobile station 14 detects an interference signal based on the received signal and the known reference signal. However, at this point in time, since it is unclear from which adjacent base station 12 the detected interference signal is transmitted, the mobile station 14 informs the base station 12-1 only that the interference signal has been detected. Notification is made (S100).

  Upon receiving a notification from the mobile station 14 that an interference signal has been detected, the base station 12-1 receives the adjacent base stations 12-2 to 7-7 whose request state stored in the request state storage unit 72 is “unrequested” On the other hand, the wireless transmission is requested to be paused in order from the smallest reference number. Here, first, the base station 12-2 is requested to pause wireless transmission (S102). When receiving a response from the base station 12-2 indicating that wireless transmission has been suspended (S104), the base station 12-1 reduces the interference signal power from the mobile station 14 for a predetermined time (for example, one frame). A notification to that effect is waited (S106).

  If there is no notification from the mobile station 14 after a predetermined time has elapsed, that is, if a time-out occurs (S108), the same processing as the processing for the base station 12-2 is performed for the base station 12-3. That is, the base station 12-1 requests the base station 12-3 to suspend wireless transmission (S110). Thereafter, upon receiving a response from the base station 12-3 indicating that the radio transmission has been suspended (S112), the base station 12-1 waits for a notification that the interference signal power has been reduced by the mobile station 14 for a predetermined time. (S114).

  Here, the case where the transmission wave from the base station 12-3 causes inter-carrier interference in the mobile station 14 is illustrated, so when the base station 12-3 temporarily stops wireless transmission, the mobile station 14 detects until then The power of the interference signal that has been reduced is reduced (here, it is assumed that the interference signal power in the channel CH3 is reduced by N [dB]). Here, the mobile station 14 notifies the base station 12-1 that the interference signal power has been reduced (including the interference signal power reduction amount N [dB] and the channel number CH3 related to the interference signal) (S116). .

  Upon receiving notification from the mobile station 14 that the interference signal power has decreased before the time-out, the base station 12-1 stops the wireless transmission by the base station 12-3 that requested the temporary stop of the wireless transmission immediately before and the mobile station 14 is estimated to correlate with the reduction in interference signal power at 14, that is, the base station 12-3 is the source of the interference signal detected at the mobile station 14. Then, the base station 12-1 requests the base station 12-3 to reduce the transmission power of the channel number CH3 notified in S116 by the reduction amount N [dB] notified in S116 (S118). .

  In this way, since only the transmission power of the interference signal that caused the inter-carrier interference is reduced, it is generated at the mobile station 14 located near the cell edge while minimizing the reduction amount of the transmission power in the base station 12-3 as the interference source. Thus, the inter-carrier interference can be suitably reduced.

  Note that in the mobile communication system 10, the “interference signal power reduction amount” is notified to the base station 12-1 in S 116 instead of “total interference signal power”. Assuming that the transmission source is located other than the base station 12-3, that is, even if the power of the interference signal detected by the mobile station 14 is the total power of two or more interference signals, the above sequence is repeated twice or more. When executed, the two or more interference signals are reduced.

  According to the mobile communication system 10 described above, even if inter-carrier interference occurs in the mobile station 14, the transmission power of the interference signal that causes it is immediately reduced, so that the transmission wave from the adjacent base station 12 arrives. Communication can be performed using all frequencies even near the cell edge where it is easy to do.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible.

  For example, in the above-described embodiment, a configuration in which the base station 12 requests the neighboring base station 12 to pause radio transmission or reduce transmission power, and pauses radio transmission according to a request from the neighboring base station 12. However, the base station 12 may have only one of the configurations.

  Further, the base station 12 that has received the notification that the interference signal has been detected is not only the adjacent base station 12 but also the neighboring base station 12 that is located within a range in which interference can be given to the mobile station 14 that is in communication. On the other hand, the wireless transmission may be requested to be temporarily stopped and the transmission power may be reduced (the adjacent range ≧ the adjacent range).

10 mobile communication systems, 12 base stations, 14 mobile stations, 16 cells (cover area), 20, 50 antennas, 22, 52 radio units, 24, 54 IFFT units, 26, 56 FFT units, 28, 58 baseband signal processing units, 30, 60 mapping unit, 32, 62 demapping unit, 34 interference detection unit, 36 correlation calculation unit, 38, 66 control unit, 40 interference information notification unit, 64 communication I / F unit, 68 transmission control request unit, 70 transmission Control unit, 72 request state storage unit.

Claims (4)

A mobile communication system including a plurality of base station apparatuses that communicate with a mobile station apparatus by an orthogonal frequency division multiple access method,
The mobile station device
Interference detecting means for detecting an interference signal that interferes with a channel used for communication with the base station apparatus, based on a received signal;
When an interference signal is detected by the interference detection means, an interference notification means for notifying the base station apparatus of the detection of the interference signal;
An interference power reduction amount notification means for notifying the base station apparatus of a reduction amount of the interference signal power when the power of the interference signal detected by the interference detection means is reduced;
Including
The base station device
Until receiving notification by the interference power reduction amount notification means after receiving notification by the interference notification means, transmission stop request means for requesting temporary stop of radio transmission sequentially to neighboring base station devices,
When receiving the notification by the interference power reduction amount notifying unit, the transmission stop requesting unit reduces the transmission power of each channel related to the notification to the base station apparatus that has requested temporary stop of radio transmission immediately before Transmission power reduction request means for requesting to reduce only,
A mobile communication system comprising: A mobile station apparatus that communicates with a base station apparatus by an orthogonal frequency division multiple access method,
Interference detecting means for detecting an interference signal that interferes with a channel used for communication with the base station apparatus, based on a received signal;
When an interference signal is detected by the interference detection means, an interference notification means for notifying the base station apparatus of the detection of the interference signal, and when the power of the interference signal detected by the interference detection means is reduced, Interference power reduction amount notifying means for notifying the base station apparatus of a reduction amount of interference signal power;
A mobile station apparatus comprising: A base station apparatus that communicates with a mobile station apparatus by an orthogonal frequency division multiple access method,
A transmission requesting a temporary stop of radio transmission sequentially from a neighboring base station apparatus until the mobile station apparatus is notified of the reduction amount of the interference signal power after the mobile station apparatus is notified of the detection of the interference signal. Stop request means;
When the reduction amount of the interference signal power is notified by the mobile station device, the transmission stop request means reduces the transmission power of each channel to the base station device that has requested a temporary stop of radio transmission immediately before A transmission power reduction request means for requesting reduction by an amount;
A base station apparatus comprising: A communication control method for reducing interference waves for a mobile station apparatus that communicates with a base station apparatus by an orthogonal frequency division multiple access method,
The mobile station device is
An interference detection step of detecting an interference signal that interferes with a channel used for communication with the base station device, based on a received signal;
When an interference signal is detected in the interference detection step, an interference notification step of notifying the base station device of the detection of the interference signal;
An interference power reduction amount notification step of notifying the base station device of a reduction amount of the interference signal power when the power of the interference signal detected in the interference detection step is reduced;
Including
The base station device is
From receiving the notification by the interference notification step until receiving the notification by the interference power reduction amount notification step, a transmission stop requesting step for requesting a temporary stop of radio transmission sequentially to neighboring base station devices,
When receiving the notification in the interference power reduction amount notification step, the transmission power of each channel is reduced according to the notification to the base station apparatus requested to temporarily stop wireless transmission in the transmission stop request step immediately before A transmission power reduction requesting step for requesting reduction by an amount;
The communication control method characterized by including.

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