JP2011101178A - Radio base station and method of controlling communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ease dependence of transmission power on a distance between a radio terminal and other radio base stations in the radio terminal connected to a radio base station. <P>SOLUTION: A small cell base station 100 calculates the maximum P(MAX) of transmission power density of an uplink of the radio terminal 200 so that the maximum P(MAX) is proportional to (1-B)th power (B is larger than 0 and is less than 1) of propagation loss PL from the radio terminal 200 to a large cell base station 300 (small cell terminal &rarr; large cell base station). Further, the small cell base station 100 decides a transmission power of the radio terminal 200 so that conditions of the calculated P(MAX) are met, and notifies the radio terminal 200 of the transmission power. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a radio base station that controls transmission power of the radio terminal based on a propagation loss between the radio terminal and another radio base station existing in a cell, and a communication control method in the radio base station About.

  LTE standardized by 3GPP, a standardization organization for wireless communication systems, as a next-generation wireless communication system that realizes higher-speed and larger-capacity communication than the currently used third-generation and 3.5-generation wireless communication systems There is. Technical specifications of LTE have been determined as 3GPP Release 8, and Release 9 which is an improved version of Release 8 and LTE Advanced which is an advanced version of LTE are currently being studied.

  In LTE Release 9, a small cell base station (Home eNodeB), which is a small base station that can be installed indoors by forming a cell (small cell) that is a communication area with a radius of about [m] to about a dozen [m]. ) Detailed functions and requirements are being standardized. The small cell base station distributes the traffic of the large cell base station (Macro eNodeB) that forms a large cell (large cell), which is a communication area with a radius of several hundred meters, and covers the dead zone in the large cell. It is installed for the purpose.

  By the way, when a small cell base station is installed in a large cell, in order to control the interference given to the large cell base station by a wireless terminal (small cell terminal) connected to the small cell base station, A method for controlling the transmission power of a link has been proposed (see Non-Patent Document 1).

  When the above-described power control method is employed, in the wireless communication system, the maximum value I (CAP) of the density of interference power that each small cell terminal gives to the large cell base station is determined. I (CAP) is stored in the small cell base station. I (CAP) is a constant that does not depend on the propagation loss PL (small cell terminal → large cell base station) from the small cell terminal to the large cell base station. In LTE, the power density indicates power per resource block (RB).

  The small cell base station calculates the maximum value P (MAX) of the uplink transmission power density of each small cell terminal using the formula (1) P (MAX) = I (CAP) × PL (small cell terminal → large cell base station) ). Here, PL (small cell terminal → large cell base station) is obtained by an existing method.

  Next, the small cell base station determines the uplink transmission power of each small cell terminal so as to satisfy the condition of the maximum value P (MAX) of the uplink transmission power density of the small cell terminal, and sends it to the small cell terminal. Notice.

3GPP TR25.967 v.9.0.0 “Home Node B Radio Frequency (RF) Requirements (FDD)”, Section 7.3 “Control of HNB uplink interference”, May 2009

  However, in the method disclosed in Non-Patent Document 1, the maximum value I (CAP) of the interference power density given to the large cell base station by the small cell terminal is a constant value in each small cell terminal. Further, the maximum value P (MAX) of the uplink transmission power density of each small cell terminal defined by Expression (1) is a propagation loss PL (small cell terminal → large cell base) from the small cell terminal to the large cell base station. Station). Therefore, a small cell terminal far from the large cell base station is set to a large transmission power density, while a small cell terminal close to the large cell base station is limited to a small transmission power density. The magnitude of transmission power density leads to the magnitude of throughput. Therefore, a large difference in the maximum value of the transmission power density of the small cell terminal depending on the distance between the small cell terminal and the large cell base station may lead to dissatisfaction of the user of the small cell terminal.

  Therefore, the present invention provides a radio base station and a communication control method in which transmission power in a radio terminal connected to the radio base station is less dependent on the distance between the radio terminal and another radio base station. For the purpose.

  In order to solve the above-described problems, the present invention has the following features. The first feature of the present invention is that the wireless terminal is based on a propagation loss between a wireless terminal (wireless terminal 200) existing in the cell (FC1) and another wireless base station (large cell base station 300). When the propagation loss is less than a predetermined value, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is a radio base station (small cell base station 100) that controls the transmission power of When the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss for making the interference given to the other wireless base station constant by the wireless terminal is larger than the predetermined value The ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is the transmission power density of the wireless terminal with respect to the propagation loss for making the interference given to the other wireless base station by the wireless terminal constant. The maximum of To be smaller than, and summarized in that a transmission power density determination unit for determining a maximum value of transmission power density of the wireless terminal (transmission power density determining unit 121).

  In such a radio base station, when the propagation loss is less than a predetermined value, the ratio of the maximum value of the transmission power density of the radio terminal to the propagation loss is constant interference that the radio terminal gives to the other radio base station. A ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss to be larger, and when the propagation loss is a predetermined value or more, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss However, the maximum transmission power density of the wireless terminal is smaller than the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss for making the interference given to the other wireless base station constant by the wireless terminal. Determine the value. As a result, even if the distance between the wireless terminal and another wireless base station changes, the transmission power density of the wireless terminal does not change as much as before, and the transmission power in the wireless terminal connected to the wireless base station Dependence on the distance between the wireless terminal and another wireless base station can be mitigated.

  According to a second aspect of the present invention, the transmission power density determination unit sets the maximum value of the transmission power density of the wireless terminal so that the transmission power density determination unit is proportional to the power of the propagation loss with an index greater than 0 and less than 1. The gist is to calculate.

  A third feature of the present invention is that a transmission power instruction unit (transmission power instruction unit 122) instructs the wireless terminal to transmit power corresponding to a transmission power density equal to or lower than a maximum value of the transmission power density of the wireless terminal. It is a summary to provide.

  A fourth feature of the present invention is a communication control method in a radio base station that controls transmission power of the radio terminal based on a propagation loss between the radio terminal present in the cell and another radio base station. Then, when the propagation loss is less than a predetermined value, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss makes the interference given by the wireless terminal to the other wireless base station constant. A ratio of a maximum value of the transmission power density of the wireless terminal to the propagation loss of the wireless terminal, and a ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss when the propagation loss is a predetermined value or more. The transmission power of the wireless terminal is smaller than the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss for making the interference given to the other wireless base station constant by the wireless terminal. density And summarized in that comprising the step of determining a maximum value.

  According to a feature of the present invention, there is provided a radio base station and a communication control method that alleviate dependence of transmission power in a radio terminal connected to a small cell base station on the distance between the radio terminal and the large cell base station. Can be provided.

1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the small cell base station which concerns on embodiment of this invention. It is a figure which shows the correspondence of propagation loss and interference power density in each of embodiment of this invention, and the conventional. It is a figure which shows the correspondence of the propagation loss and the maximum value of transmission power density in each of embodiment of this invention and the conventional. It is a sequence diagram which shows the operation example of the propagation loss estimation in the radio | wireless communications system which concerns on embodiment of this invention. It is a sequence diagram which shows the operation example of the transmission power control in the radio | wireless communications system which concerns on embodiment of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) the configuration of the wireless communication system, (2) the operation of the wireless communication system, (3) the operation and effect, and (4) other embodiments will be described. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Configuration of Radio Communication System (1.1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system 1 according to an embodiment of the present invention. The wireless communication system 1 has, for example, a configuration based on LTE Release 9 which is a 3.9th generation (3.9G) mobile phone system and LTE-Advanced which is positioned as a 4th generation (4G) mobile phone system.

  As shown in FIG. 1, the radio communication system 1 includes a small cell base station (for example, a femtocell base station or a picocell base station) 100 that forms a small cell (for example, a femtocell or picocell) FC1, and a large cell (for example, , Macro cell) large cell base station (for example, macro cell base station) 300 that forms MC1. The radius of the large cell MC1 is, for example, about several hundred [m], and the radius of the small cell FC1 is, for example, about several [m] to several tens [m]. A radio terminal (small cell terminal) 200 is connected to the small cell base station 100.

  The large cell base station 300 is installed at a location based on a station design in which a communication carrier considers inter-cell interference. On the other hand, the small cell base station 100 is configured to be small enough to be installed in an arbitrary place (specifically, indoors) by the user. The small cell base station 100 is installed in the large cell MC1 for the purpose of distributing the traffic of the large cell base station 300 and covering the dead zone in the large cell MC1.

  The large cell base station 300 is connected to the core network 500 via a dedicated line. On the other hand, the small cell base station 100 is connected to a core network 500 of a communication carrier through a general public line such as ADSL or FTTH. In addition, a host device 400 such as an MME (Mobility Management Entity) is connected to the core network 500.

  When the small cell base station 100 and the wireless terminal 200 are connected to perform communication, the uplink used for the communication (the link from the wireless terminal 200 to the small cell base station 100, hereinafter referred to as “small cell In the case where communication is performed by connecting the frequency band of “uplink”) and the large cell base station 300 and a wireless terminal (not shown) to perform communication, the uplink (not shown, wireless terminal to large cell base) is used for the communication. If the frequency band of the link is toward the station 300 and is hereinafter referred to as “large cell uplink”), the radio signal transmitted from the radio terminal 200 to the small cell base station 100 using the uplink is used. The large cell base station 300 receives interference.

In the present embodiment, when the large cell base station 300 receives interference from the radio terminal 200, the small cell base station 100 controls the transmission power of the radio terminal 200 to reduce the interference.
(1.2) Configuration of Small Cell Base Station FIG. 2 is a block diagram showing the configuration of the small cell base station 100. As illustrated in FIG. 2, the small cell base station 100 includes an antenna unit 101, a wireless communication unit 110, a control unit 120, a storage unit 130, and a wired communication unit 140.

  The wireless communication unit 110 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, and the like, and transmits and receives a wireless signal via the antenna unit 101. In addition, the wireless communication unit 110 performs encoding and modulation of a transmission signal and demodulation and decoding of a reception signal.

  The control unit 120 is configured using, for example, a CPU, and controls various functions included in the large cell base station 300. The storage unit 130 is configured using a memory, for example, and stores various types of information used for controlling the large cell base station 300 and the like. The wired communication unit 140 communicates with other large cell base stations and small cell base stations 100 via the core network 500.

  The control unit 120 includes a transmission power density determination unit 121 and a transmission power instruction unit 122.

  The transmission power density determination unit 121 receives a received signal strength (RSRP (large cell base station) of a reference signal (RS) from the large cell base station 300 in the radio terminal 200 via the antenna unit 101 and the radio communication unit 110. → small cell terminal)) is received from the radio terminal 200. Here, RSRP (large cell base station → small cell terminal) is measured in radio terminal 200.

  Next, the transmission power density determination unit 121 uses an existing method to determine the propagation loss PL (large cell) from the large cell base station 300 to the radio terminal 200 based on RSRP (large cell base station → small cell terminal). Base station → small cell terminal).

  Specifically, the transmission power density determination unit 121 divides the transmission power of the reference signal of the large cell base station 300 by RSRP (large cell base station → small cell terminal), thereby obtaining PL (large cell base station → small cell base station). Cell terminal). Here, the large cell base station 300 transmits the transmission power of the reference signal to a wireless terminal (not shown) connected to itself. The transmission power density determination unit 121 can receive the transmission power of the reference signal via the antenna unit 101 and the wireless communication unit 110.

  Further, the transmission power density determination unit 121 estimates a propagation loss PL (small cell terminal → large cell base station) from the radio terminal 200 to the large cell base station 300. Specifically, the transmission power density determination unit 121 performs PL (large cell base station → small cell terminal) when the difference between the frequency bands used in the uplink direction and the downlink direction is less than or equal to a predetermined value. Is PL (small cell terminal → large cell base station). On the other hand, when the difference between the frequency bands used in the uplink direction and the downlink direction exceeds a predetermined value, the transmission power density determination unit 121 corrects PL (large cell base station → small cell terminal) with a predetermined correction. The value corrected by the technique is estimated to be PL (small cell terminal → large cell base station).

  Next, based on the estimated PL (small cell terminal → large cell base station), the transmission power density determining unit 121 determines the interference power that the radio terminal 200 gives to the large cell base station 300 according to the following equation (2). The maximum density value I (CAP) is calculated.

…式（２）

... Formula (2)

  Here, the constant A is a positive real number predetermined in the radio communication system 1, and the constant B is a real number greater than 0 and less than 1 predetermined in the radio communication system 1, and is stored in the storage unit 130. Yes. Conventionally, I (CAP) is predetermined, but in this embodiment, constants A and B are predetermined. Expression (2) is expressed by the following expression (3) in decibel notation.

  I (CAP) [dB] = − B [dB] × PL (small cell terminal → large cell base station) [dB] + A [dB] (3)

  The solid line part in FIG. 3A shows the correspondence between PL (small cell terminal → large cell base station) and I (CAP) based on the formula (2), and the dotted line part in FIG. The correspondence relationship between (small cell terminal → large cell base station) and I (CAP) is shown. Also, the solid line portion in FIG. 3B shows the correspondence between PL (small cell terminal → large cell base station) and I (CAP) based on Equation (3) in the case of decibel notation, and FIG. The dotted line portion in FIG. 4 indicates the correspondence between conventional PL (small cell terminal → large cell base station) and I (CAP) in the case of decibel notation.

  As shown in FIGS. 3A and 3B, conventionally, I (CAP) is calculated to have a predetermined value regardless of PL (small cell terminal → large cell base station). On the other hand, in this embodiment, I (CAP) is larger as PL (small cell terminal → large cell base station) is larger, in other words, as the distance between the radio terminal 200 and the large cell base station 300 is longer, I (CAP) is calculated to be small.

  Again, referring back to FIG. The transmission power density determination unit 121 calculates the maximum value P (MAX) of the uplink transmission power density of the radio terminal 200 by the following equation (4).

  P (MAX) = I (CAP) × PL (small cell terminal → large cell base station) (4)

  P (MAX) is calculated by the following equation (5) from the equations (2) and (4).

…式（５）

... Formula (5)

  Expression (5) is expressed by the following expression (6) in decibel notation.

  P (MAX) [dB] = (1-B) [dB] × PL (small cell terminal → large cell base station) [dB] + A [dB] (6)

  Conventionally, as is clear from Equation (1), P (MAX) is proportional to the power of PL (small cell terminal → large cell base station), but in this embodiment, P (MAX) is PL It is proportional to the 1-B power of (small cell terminal → large cell base station).

  The solid line part in FIG. 4 (a) shows the correspondence between PL (small cell terminal → large cell base station) and P (MAX) based on equation (5), and the dotted line part in FIG. The correspondence relationship between PL (small cell terminal → large cell base station) and P (MAX) is shown. Also, the solid line part in FIG. 4 (b) shows the correspondence between PL (small cell terminal → large cell base station) and P (MAX) based on Expression (6) in the case of decibel notation, and FIG. 4 (b). The dotted line portion indicates the correspondence between conventional PL (small cell terminal → large cell base station) and P (MAX) in the case of decibel notation.

  As shown in FIGS. 4A and 4B, conventionally, P (MAX) is calculated to be proportional to the first power of PL (small cell terminal → large cell base station). Then, P (MAX) is calculated so as to be proportional to 1-B power of PL (small cell terminal → large cell base station). Therefore, in this embodiment, when PL (small cell terminal → large cell base station) is greater than or equal to a predetermined value, in other words, when the distance between the radio terminal 200 and the large cell base station 300 is less than or equal to the predetermined distance. P (MAX) becomes a larger value than before, and when PL (small cell terminal → large cell base station) is less than a predetermined value, in other words, the distance between the radio terminal 200 and the large cell base station 300 is If the distance exceeds the predetermined distance, P (MAX) becomes a smaller value than before.

  Again, referring back to FIG. The transmission power density determination unit 121 satisfies the calculated P (MAX) condition, in other words, the transmission power density of the resource block corresponding to the uplink of the radio terminal 200 is equal to or less than P (MAX). Then, the uplink transmission power in the radio terminal 200 is calculated.

  The transmission power instruction unit 122 transmits a transmission power notification, which is a notification including the calculated transmission power, to the radio terminal 200 via the radio communication unit 110 and the antenna unit 101. When receiving the transmission power notification, the radio terminal 200 transmits a radio signal to the uplink with the transmission power included in the transmission power notification.

(2) Operation of Radio Communication System FIG. 5 is a sequence diagram showing an operation example of propagation loss estimation in the radio communication system 1 according to the embodiment of the present invention.

  In step S101, the large cell base station 300 transmits a reference signal. The radio terminal 200 that exists in the MC 1 and is connected to the small cell base station 100 receives the reference signal from the large cell base station 300.

  In step S102, the radio terminal 200 measures RSRP (large cell base station → small cell terminal), which is the received signal strength of the reference signal. In step S103, the radio terminal 200 is connected to RSRP (large cell base station → small cell terminal). Transmit to the small cell base station 100. The small cell base station 100 receives RSRP (large cell base station → small cell terminal) from the radio terminal 200.

  In step S104, the small cell base station 100 determines the propagation loss PL (large cell base station → small cell) from the large cell base station 300 to the radio terminal 200 based on the received RSRP (large cell base station → small cell terminal). Terminal). In step S105, the small cell base station 100 determines a propagation loss PL (small cell terminal → large cell base) from the radio terminal 200 to the large cell base station 300 based on the calculated PL (large cell base station → small cell terminal). Station).

  FIG. 6 is a sequence diagram showing an operation example of transmission power control in the wireless communication system 1 according to the embodiment of the present invention.

  In step S201, the small cell base station 100 determines the density of interference power that the wireless terminal 200 gives to the large cell base station 300 based on the PL (small cell terminal → large cell base station) estimated in step S105 of FIG. The maximum value I (CAP) is calculated.

  In step S202, the small cell base station 100 determines the maximum value of the uplink transmission power density of the radio terminal 200 based on the calculated I (CAP) and the estimated PL (small cell terminal → large cell base station). P (MAX) is calculated.

  In step S203, the small cell base station 100 satisfies the calculated P (MAX) condition, in other words, the transmission power density of the resource block corresponding to the uplink of the radio terminal 200 is equal to or less than P (MAX). Thus, the uplink transmission power in the radio terminal 200 is calculated.

  In step S204, the small cell base station 100 transmits a transmission power notification, which is a notification including the calculated transmission power, to the radio terminal 200. The wireless terminal 200 receives the transmission power notification.

(3) Operation / Effect In the wireless communication system 1 according to the present embodiment, the small cell base station 100 sets the maximum value P (MAX) of the uplink transmission power density of the wireless terminal 200 from the wireless terminal 200 to the large cell base station. It is calculated to be proportional to the (1-B) power (where B is a value greater than 0 and less than 1) of propagation loss PL to 300 (small cell terminal → large cell base station). Furthermore, the small cell base station 100 determines the transmission power of the radio terminal 200 so as to satisfy the calculated P (MAX) condition, and notifies the radio terminal 200 of the transmission power.

  Thereby, the region where the propagation loss PL (small cell terminal → large cell base station) from the radio terminal 200 to the large cell base station 300 is less than the predetermined value, in other words, the distance from the large cell base station 300 is the predetermined distance. In the region that is less than the region, the transmission power of the radio terminal 200 in the region is larger than before, and the region where PL (small cell terminal → large cell base station) is equal to or greater than a predetermined value, in other words, the large cell base station In an area where the distance from 300 is equal to or greater than a predetermined distance, the transmission power of the radio terminal 200 in the area is smaller than in the past. Therefore, even if the distance between the radio terminal 200 and the large cell base station 300 changes, the transmission power density of the radio terminal 200 does not change as much as before, and the transmission power in the radio terminal 200 is large compared to the radio terminal 200. Dependence on the distance from the cell base station 300 can be mitigated.

  For this reason, the throughput in the wireless terminal 200 does not change according to the position of the wireless terminal 200 as in the past, and it is possible to suppress dissatisfaction of the user of the wireless terminal 200 due to a large change in the throughput.

(4) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment described above, the small cell base station 100 uses the uplink transmission power density maximum value P (MAX) of the radio terminal 200 as the propagation loss PL (small cell terminal) from the radio terminal 200 to the large cell base station 300. → Large cell base station) is calculated to be proportional to (1-B) power (where B is a value greater than 0 and less than 1), but the method of deriving P (MAX) is not limited to this, When PL (small cell terminal → large cell base station) is less than a predetermined value, P (MAX) becomes larger than before, and when PL (small cell terminal → large cell base station) is greater than or equal to a predetermined value. It is only necessary that P (MAX) be calculated so as to be smaller than in the past.

  In the above-described embodiment, the large cell base station 300 is a macro cell base station that forms a macro cell, and the small cell base station 100 is a femto cell base station that forms a femto cell. The cell base station 300 and the small cell base station 100 are not limited to these, and it is sufficient that the small cell formed by the small cell base station 100 is smaller than the large cell formed by the large cell base station 300. For example, when the large cell base station 300 is a macro cell base station that forms a macro cell, the small cell base station 100 can be a base station that forms a micro cell or a pico cell. When the large cell base station 300 is a micro cell base station that forms a micro cell, the small cell base station 100 can be a base station that forms a pico cell or a femto. Furthermore, when the large cell base station 300 is a pico cell base station that forms a pico cell, the small cell base station 100 can be a base station that forms a femto.

  In the above-described embodiment, the wireless communication system 1 is configured based on LTE Release 9 or LTE-Advanced, but may be configured based on other communication standards.

  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.

  According to the radio base station and the communication control method of the present invention, it is possible to reduce the dependence of the transmission power in the radio terminal connected to the radio base station on the distance between the radio terminal and another radio base station. It is useful as a radio base station or the like.

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 100 ... Small cell base station, 101 ... Antenna part, 110 ... Wireless communication part, 120 ... Control part, 121 ... Transmission power density determination part, 122 ... Transmission power instruction | indication part, 130 ... Memory | storage part, 140 ... Wired communication unit, 200 ... Wireless terminal, 300 ... Large cell base station

Claims (4)

A radio base station that controls transmission power of the radio terminal based on a propagation loss between a radio terminal and another radio base station existing in a cell,
When the propagation loss is less than a predetermined value, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is the interference for making the interference given to the other wireless base station by the wireless terminal constant When the propagation loss is larger than a ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss, and the propagation loss is a predetermined value or more, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is The transmission power density of the wireless terminal is smaller than a ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss for making the interference given to the other wireless base station constant by the wireless terminal. A radio base station including a transmission power density determination unit that determines a maximum value.   2. The radio according to claim 1, wherein the transmission power density determination unit calculates a maximum value of the transmission power density of the radio terminal so as to be proportional to a power of the propagation loss with an index greater than 0 and less than 1. base station.   The radio base station according to claim 1, further comprising: a transmission power instruction unit that instructs the wireless terminal to transmit power corresponding to a transmission power density equal to or lower than a maximum transmission power density of the wireless terminal. A communication control method in a radio base station that controls transmission power of the radio terminal based on a propagation loss between a radio terminal and another radio base station existing in a cell,
When the propagation loss is less than a predetermined value, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is the interference for making the interference given to the other wireless base station by the wireless terminal constant When the propagation loss is larger than a ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss, and the propagation loss is a predetermined value or more, the ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss is The transmission power density of the wireless terminal is smaller than a ratio of the maximum value of the transmission power density of the wireless terminal to the propagation loss for making the interference given to the other wireless base station constant by the wireless terminal. A communication control method comprising a step of determining a maximum value.

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