JP2010219918A - Radio base station, radio base station monitoring system, transmission power setting method of radio base station, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an interference with an outdoor base station minimum by appropriately setting a transmission power of a radio signal of a base station. <P>SOLUTION: The indoor radio base station includes a received electric field intensity measuring means for measuring a received electric field intensity of the radio signal from an outdoor radio base station, a building penetration loss estimating means for estimating a building penetration loss of a radio signal in the building where the indoor radio base station is installed, and a transmission power setting means for setting a maximum transmission power of the indoor radio base station on the basis of the building penetration loss estimated by the building penetration loss estimating means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a radio base station, a radio base station monitoring system, a radio base station transmission power setting method, a program, and a recording medium, and in particular, transmission for minimizing radio signal interference between an indoor base station and an outdoor base station. It relates to a technique for power setting.

  In a mobile communication network, a wide area is generally divided into small zones called radio cells, and one radio base station is provided for about 1 to 10 radio cells. Wireless base stations are classified into outdoor base stations that are installed on dedicated rooftops or rooftops of buildings with good visibility conditions, and indoor base stations that mainly cover one building. The radio cell of the outdoor base station varies depending on the installation environment such as an urban area or a suburb, and the radius of the radio cell is about 100 to 10 km. On the other hand, since an indoor base station is installed in a building, the radius of the radio cell is usually 100 m or less, and in a base station for a general house called a femtocell base station, the radio cell radius may be several tens m or less. .

  As described above, since there is a large difference in the size of the radio cell between the outdoor base station and the indoor base station, the topology is such that the outdoor base station radio cell includes the indoor base station radio cell. It is common. Here, when the indoor base station and the outdoor base station use the same frequency carrier, when the transmission power of the indoor base station and the transmission power of the wireless terminal existing in the wireless cell of the indoor base station are set excessively, The interference with the radio cell of the outdoor base station becomes excessive, and the system capacity is deteriorated. On the other hand, when the transmission power is set too low, there is a problem that a dead zone where the communication service cannot be received occurs indoors, and it is necessary to appropriately set the transmission power of the radio base station and the subordinate radio terminals.

As a conventional technique for setting the transmission power of an indoor base station, for example, there is Patent Document 1. In Patent Document 1, an indoor base station measures a received signal code power (RSCP) of a common pilot channel (CPICH) of neighboring outdoor base stations, and the common pilot channel for all transmission powers is measured. In consideration of the ratio and the building intrusion loss (Minimum Interior Loss), a method of setting the downlink transmission power obtained by the following equation 1 is disclosed (FIGURE 4, step 108).
<Formula 1>
Power = (Minimum Interior Loss) + (Large Marco Node B RSCP value) −10 log 10 (Percentage of the Total Femtocell Basement Power Allocated to CPICH)

  Here, (Large Mark Node B RSCP value) represents the highest received electric field strength when a common pilot channel signal is received from a plurality of outdoor base stations in an indoor base station. In Patent Document 1, the building intrusion loss (Minimum Interior Loss) is given by a central monitoring system, and details thereof are not specified. Assuming that the building intrusion loss is correctly estimated, if the downlink transmission power is set according to Equation 1 above, the received electric field strengths of the outdoor base station and indoor base station are equal in the vicinity of the building boundary. The cell is equal to the whole building.

  Similarly, in Patent Document 1, a method of collecting received field strength measurement values of radio signals from an outdoor base station from terminals under the base station and determining maximum downlink transmission power and maximum uplink transmission power using the measurement results Is disclosed (Figure 6).

Next, Non-Patent Document 1 is known as a conventional technique for obtaining a building entry loss. In Non-Patent Document 1, it is a building intrusion loss derived based on measurement results in various buildings such as office buildings in urban areas, and the building intrusion loss can be obtained by the following empirical formula (Formula 2).
<Formula 2>
Loss [dB] = 0.6d−0.6Hm + 10

  However, in the above formula 2, d represents the distance [m] from the window in the building to the inside, Hm represents the reception floor height [m], the first term (0.6d) on the right side is the indoor path loss, and the second term (0.6Hm) is the height correction, and the third term (10) is the loss due to the outer wall of the building. According to the non-patent document 1, the standard deviation of the estimation error of the building intrusion loss according to Equation 2 is about 10 dB.

  Patent Document 2 discloses a method of estimating the electric field strength on the building surface by three-dimensional radio wave propagation estimation or the like and estimating the electric field strength inside the building based on the electric field strength.

International Publication WO2008 / 093100 Pamphlet JP-T-2001-506460

Hideaki Okamoto, Shinichi Ichitsubo, “Examination of invasion characteristics of buildings at 800MHz to 8GHz in the city”, 2005 IEICE General Conference, S.P. 23-24, ABS-1-12

  The first problem is that the actual building transmission loss varies depending on the size of the building where the indoor base station is installed and the installation location, so it is uniquely given by the central monitoring system according to Equation 1 in Patent Document 1. This means that there is a possibility that it will deviate greatly from the transmission loss. For example, building transmission loss of radio waves is greatly influenced by the material of the outer wall such as wood, the height of the outer wall, the ratio of the window glass, the number of inner walls, the floor area, etc. These data are generally available Since it is not included in the digital map information, it is not easy to accurately predict the building transmission loss in advance.

  In addition, the second problem is that the number of wireless terminals existing inside the wireless cell of the indoor base station is generally smaller than that of the outdoor base station, so that it is not always distributed over the entire wireless cell. Therefore, even if measurement information is collected from a wireless terminal as in FIG. 6 of Patent Document 1, there is a possibility that transmission power setting that correctly estimates building transmission loss cannot be performed.

  In addition, Equation 2 in Non-Patent Document 1 represents the tendency of building intrusion loss as a whole, but the loss of individual buildings includes an error due to differences in building materials and structures. was there. Therefore, if the transmission power setting of the indoor base station is too large, it gives excessive interference to the radio cell of the outdoor base station, and if the transmission power setting of the indoor base station is too small, the problem that the indoor cannot be sufficiently covered was there.

  In view of the circumstances described above, an object of the present invention is to appropriately set the transmission power of a radio signal of an indoor base station so that interference with an outdoor base station can be minimized.

  A radio base station according to one aspect of the present invention is a radio base station installed indoors, and as shown in FIG. 1, a received electric field strength for measuring a received electric field strength of a radio signal from an outdoor radio base station. Based on the building intrusion loss estimated by the measuring means, the building intrusion loss estimating means for estimating the building intrusion loss of the radio signal in the building where the indoor radio base station is installed, the indoor radio Transmission power setting means for setting the maximum transmission power of the base station.

  A radio base station monitoring system according to an aspect of the present invention is a radio base station monitoring system that monitors a communication state of a radio base station, and is a radio signal transmitted by an outdoor radio base station as shown in FIG. Receiving field strength estimating means for estimating the received field strength of the radio signal in the field near the building where the indoor radio base station is installed, and the received field strength estimated by the receiving field strength estimating means for the radio signal in the building Estimation result notifying means for notifying an indoor radio base station that estimates a building intrusion loss and obtains a maximum transmission power.

  A radio base station transmission power setting method according to an aspect of the present invention is a radio base station transmission power setting method installed indoors, and is an estimated value of a received electric field strength of a radio signal from an outdoor radio base station An estimated value acquisition step of acquiring from the radio base station monitoring system that monitors the communication state of the radio base station, and measuring the received electric field strength of the radio signal from the outdoor radio base station to obtain the measured value of the received electric field strength A measurement value acquisition step to be acquired, a building intrusion loss estimation step for estimating a building intrusion loss of a radio signal in a building in which an indoor radio base station is installed, using an estimated value and a measurement value of a received electric field strength, and a building intrusion A transmission power setting step for setting the maximum transmission power of the indoor radio base station based on the building intrusion loss estimated in the loss estimation step.

  A program according to one aspect of the present invention is a program used in a radio base station installed indoors, and an estimated value of the received electric field strength of a radio signal from an outdoor radio base station is transmitted to a computer. An estimated value acquisition process acquired from a radio base station monitoring system for monitoring the communication state of the radio, and a measurement value acquisition for measuring a received electric field strength of a radio signal from an outdoor radio base station and acquiring the measured value of the received electric field strength Estimated by the building intrusion loss estimation process and the building intrusion loss estimation process that estimate the building intrusion loss of the radio signal in the building where the indoor radio base station is installed using the estimated value and the measured value of the received electric field strength And a transmission power setting process for setting the maximum transmission power of the indoor radio base station based on the building intrusion loss.

  A recording medium according to one aspect of the present invention is a computer-readable recording medium on which the above program is recorded.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to set appropriately the transmission power of an indoor base station by correctly estimating a building penetration loss according to the building in which an indoor base station is installed. As a result, it is possible to secure a cover area in the building where the indoor base station is installed and to prevent excessive interference with the outdoor base station, thereby increasing the system capacity of the indoor base station and the outdoor base station. It becomes possible.

1 is a configuration diagram of a radio base station and a radio base station monitoring system according to the present invention. It is a block diagram of the wireless network in 1st Embodiment of this invention. It is a block diagram of the wireless base station (indoor base station) in 1st Embodiment of this invention. It is an internal block diagram of the radio base station monitoring system in 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the propagation estimation means of the radio base station monitoring system in 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the building penetration loss estimation means of the wireless base station (indoor base station) in 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the propagation estimation means of the radio base station monitoring system in 2nd Embodiment of this invention.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
Referring to FIG. 2, there is shown a configuration of a wireless network in the first embodiment as an embodiment of the present invention. The outdoor base station 10 communicates with terminals located in a wide area indicated by the wireless cell 40 via the wireless link 80. The indoor base station 20 covers the wireless cell 50 that is mainly near the indoor base station installation building 70. The radio base station monitoring system 30 is located inside the wired network 90, monitors the communication state of the outdoor base station 10 and the indoor base station 20, and is connected via wired links 60 and 61, respectively.

  A detailed configuration of the indoor base station 20 is shown in FIG. The wireless transmitter / receiver 21 transmits / receives a physical signal in the wireless link 80 and outputs the received signal to the received electric field strength measuring means 22. The received electric field strength measuring means 22 measures the received electric field strength of the pilot channel of a neighboring outdoor base station such as the outdoor base station 20 and outputs the result to the building intrusion loss estimating means 23. The building intrusion loss estimating means 23 estimates the amount of signal attenuation when the radio signal of the outdoor base station enters the building or when the radio signal of the indoor base station penetrates outside the building, and the appropriate maximum transmission power Is calculated. The transmission power setting unit 24 outputs the maximum transmission power calculated by the building intrusion loss estimation unit 23 to the wireless transceiver 21. The wired transmitter / receiver 25 relays the signal of the wired network with the wireless terminal via the wired link 60 and notifies the wireless base station monitoring system 30 of the monitoring information of the indoor base station.

  FIG. 4 shows an internal configuration of the radio base station monitoring system 30 in the first embodiment of the present invention. The propagation estimating means 36 refers to the map information and the radio base station antenna setting information from the map information database 31 and the radio base station database 32, and estimates the received electric field strength in the vicinity of the indoor base station. The propagation estimation method uses a deterministic method such as ray tracing to predict the radio wave propagation status with high accuracy, even if it uses a statistical model represented by Okumura and Hajime. There may be. The propagation estimation result communication means 33 outputs the received electric field strength near the indoor base station estimated by the radio wave propagation estimation means 36 to the indoor base station 20 via the data transmission / reception means 37. In addition, the monitoring information collection unit 34 inputs a general base station activation state and communication state from the data transmission / reception unit 38 and stores them in the monitoring information database 35.

  Although the configuration of the embodiment has been described in detail above, other outdoor base stations 10 and wireless terminals are well known to those skilled in the art and are not directly related to the present invention, so the detailed configuration is omitted. .

  Next, the operation of the radio wave propagation estimating means 36 of the radio base station monitoring system 30 is shown in FIG.

  The radio base station monitoring system 30 starts an estimation process upon acquiring a base station activation state change from the indoor base station 20 (step S101). First, the antenna setting information and pilot signal transmission power of the outdoor base station 10 are acquired from the radio base station database 32 (step S102). Next, terrain information and building information in the vicinity of the radio cell 40 are acquired from the map information database 31 (step S103), and the pilot signal reception electric field strength of the outdoor base station 10 outdoors near the indoor base station installation building 70 is estimated (step S103). Step S104). Finally, the received field strength estimation value of the outdoor base station 10 in the outdoor of the building is transmitted to the indoor base station 20, and the process ends (step S105). Thus, the propagation estimation means 36 can estimate the received electric field strength in the vicinity of the building boundary of the indoor base station 20.

  FIG. 6 shows the operation of the building intrusion loss estimating means 23 of the indoor base station 20.

When the indoor base station 20 is activated, the building intrusion loss estimating means 23 obtains an estimated value of the received electric field strength in the building outdoor with respect to the pilot signal of the outdoor base station from the radio base station monitoring system 30 (step S201). Next, an actual pilot signal reception field strength measurement value of the outdoor base station is acquired from the reception field strength measurement means 22 (step S202). Here, the building intrusion loss is estimated using the following expression 3 (step S203). In Equation 3, the building intrusion loss is estimated by taking the difference between the estimated value and the actually measured value.
<Formula 3>
Building penetration loss [dB] = Received field strength estimate outside building-Received field strength measurement

Subsequently, using this building entry loss, the maximum transmission power is obtained according to the following equation 4 (step S204). Then, the determined maximum transmission power is output to the transmission power setting means 24 as a maximum transmission power setting value (step S205).
<Formula 4>
Maximum transmission power [dBm] = building penetration loss [dB] + outdoor base station pilot signal reception field strength measurement [dBm] + pilot signal transmission power ratio [dB] + margin [dB]

  In the first embodiment of the present invention, as described above, in the indoor base station, the received electric field strength (estimated value) in the outdoor of the indoor base station installation building obtained by the radio wave propagation estimating means and the actual reception from the outdoor base station. By taking the difference from the measured signal strength (actual measured value), it is possible to accurately grasp the building entry loss. By setting the maximum transmission power of the indoor base station based on this building intrusion loss, it becomes possible to minimize the amount of interference between the outdoor base station and the indoor base station and maximize the system capacity.

[Second Embodiment]
Next, as a second embodiment of the present invention, the radio wave propagation estimation means 36 of the radio base station monitoring system 30 in the first embodiment predicts the propagation loss inside the building 70 where the indoor base station 20 is installed. An example of setting a more appropriate margin will be shown.

  FIG. 7 is a flowchart showing the operation of the propagation estimating means of the radio base station monitoring system according to the second embodiment of the present invention. Steps S301, 302, and 304 are the same as steps S101, 102, and 104 in the first embodiment. The propagation estimation means 36 acquires the height and floor length of the indoor base station installation building 70 in addition to the topographic information and building information in the vicinity of the wireless cell 40 from the map information database 31 (step S303). Next, the maximum propagation loss in the building is estimated according to the above equation 2 using the height information and floor length information of the indoor base station installed building 0. However, the maximum propagation loss in the building is estimated except for the third term of equation 2 (loss due to the building outer wall) (step S305). Next, the estimated value of the received electric field intensity of the outdoor base station pilot signal outside the building and the maximum propagation loss in the building are transmitted to the indoor base station 20 (step S306).

  In the second embodiment of the present invention, the transmission power of the indoor base station can be set more appropriately by adding the in-building maximum propagation loss as a margin in step S204 of FIG.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible. For example, as an application example of the present invention, a radio base station installed indoors and a monitoring system thereof in a land public mobile communication system can be cited.

  The program executed by the radio base station in the present embodiment has a module configuration including the above-described means (reception field strength measurement means 22, building intrusion loss estimation means 23, transmission power setting means 24, etc.). Specific means are realized using actual hardware. That is, when the computer (CPU) reads a program from a predetermined recording medium and executes it, the above-mentioned means are loaded onto the main storage device and generated.

  In addition, the program executed in the wireless base station in the present embodiment may be configured to be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program may be provided or distributed via a network such as the Internet.

  The program is a file in an installable or executable format, such as a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, DVD, nonvolatile memory card, or the like. It may be configured to be provided by being recorded on a computer-readable recording medium. Further, the program may be provided by being incorporated in advance in a ROM or the like.

  In this case, the program code itself read from the recording medium or loaded and executed through the communication line realizes the functions of the above-described embodiments. And the recording medium which recorded the program code comprises this invention.

DESCRIPTION OF SYMBOLS 1 Radio base station 6 Reception electric field strength estimation means 7 Estimation result notification means 10 Outdoor base station 20 Indoor base station 21 Radio transmitter / receiver 2,22 Reception electric field strength measurement means 3,23 Building penetration loss estimation means 4,24 Transmission power setting means DESCRIPTION OF SYMBOLS 25 Wired transmitter / receiver 5,30 Wireless base station monitoring system 31 Map information database 32 Wireless base station database 33 Propagation estimation result communication means 34 Monitoring information collection means 35 Monitoring information database 36 Radio wave propagation estimation means 37 Data transmission / reception means 40, 50 Wireless cell 60, 61 Wired link 70 Indoor base station installed building 80 Wireless link 90 Wired network

Claims (15)

A wireless base station installed indoors,
A received electric field strength measuring means for measuring a received electric field strength of a radio signal from an outdoor radio base station;
A building intrusion loss estimating means for estimating a building intrusion loss of a radio signal in a building in which the indoor radio base station is installed;
Transmission power setting means for setting the maximum transmission power of the indoor radio base station based on the building penetration loss estimated by the building penetration loss estimation means,
A radio base station characterized by comprising:   The building intrusion loss estimation means includes an estimated value of the received electric field strength of the radio signal from the outdoor radio base station acquired from the radio base station monitoring system that monitors the communication state of the radio base station, and the received electric field strength measurement. The radio base station according to claim 1, wherein the building intrusion loss is estimated by taking a difference from the measured value of the received electric field strength obtained by the means.   The building intrusion loss estimating means calculates the maximum transmission power of the indoor radio base station using the estimated building intrusion loss and the measured value of the received electric field strength obtained by the received electric field strength measuring means. The radio base station according to claim 1 or 2.   The building intrusion loss estimating means is a wireless base station monitoring system that monitors a communication state of a wireless base station, and is determined based on map information and wireless base station antenna setting information. The radio base station according to any one of claims 1 to 3, wherein the building entry loss is estimated using an estimated value of a received electric field strength of a signal.   The building intrusion loss estimating means is the estimated maximum propagation loss in the building determined based on the height and floor length of the building in the radio base station monitoring system for monitoring the communication state of the radio base station. 5. The radio base station according to claim 1, wherein a maximum transmission power of the indoor radio base station is calculated using the building intrusion loss. A radio base station monitoring system for monitoring a communication state of a radio base station,
A reception electric field strength estimating means for estimating a reception electric field strength of a radio signal in a field near a building where an indoor radio base station is installed, with a radio signal transmitted by an outdoor radio base station;
An estimation result notifying means for notifying the received radio field strength estimated by the received electric field strength estimating means to the indoor radio base station for estimating a maximum transmission power by estimating a building penetration loss of a radio signal in the building;
A radio base station monitoring system comprising: Map information holding means for holding map information including terrain information and building information;
Radio base station information holding means for holding antenna setting information of the radio base station;
The radio base station monitoring system according to claim 6, further comprising:   The received electric field strength estimating means estimates the received electric field strength of a radio signal in the field near the building based on map information including terrain information and building information and antenna setting information of the radio base station. The radio base station monitoring system according to claim 6 or 7.   The radio base according to any one of claims 6 to 8, wherein the reception electric field strength estimating means estimates a maximum propagation loss inside the building based on a height and a floor length of the building. Station monitoring system.   The estimation result notifying means includes a field intensity of a radio signal in the vicinity of the building estimated based on map information including terrain information and building information and antenna setting information of a radio base station, the height of the building, The radio base station according to any one of claims 6 to 9, wherein a maximum propagation loss in the building estimated based on a floor length is notified to the indoor radio base station. Monitoring system. A transmission power setting method for a radio base station installed indoors,
An estimated value acquisition step of acquiring an estimated value of the received electric field strength of a radio signal from an outdoor radio base station from a radio base station monitoring system that monitors a communication state of the radio base station;
A measurement value acquisition step of measuring a reception field strength of a radio signal from an outdoor radio base station and acquiring a measurement value of the reception field strength;
A building intrusion loss estimating step for estimating a building intrusion loss of a radio signal in a building in which the indoor wireless base station is installed, using the estimated value and the measured value of the received electric field strength;
A transmission power setting step for setting the maximum transmission power of the indoor radio base station based on the building intrusion loss estimated in the building intrusion loss estimation step;
A transmission power setting method for a radio base station, comprising:   The radio base according to claim 11, wherein the building intrusion loss estimation step estimates the building intrusion loss by taking a difference between the estimated value of the received electric field strength and the measured value of the received electric field strength. Station transmission power setting method. A program used in a radio base station installed indoors,
On the computer,
An estimated value acquisition process for acquiring an estimated value of the received electric field strength of a radio signal from an outdoor radio base station from a radio base station monitoring system that monitors a communication state of the radio base station;
A measurement value acquisition process for measuring a reception field strength of a radio signal from an outdoor radio base station and acquiring a measurement value of the reception field strength;
Using the estimated value and the measured value of the received electric field strength, a building intrusion loss estimation process for estimating a building intrusion loss of a radio signal in a building in which the indoor wireless base station is installed;
A transmission power setting process for setting the maximum transmission power of the indoor radio base station based on the building intrusion loss estimated in the building intrusion loss estimation process;
A program characterized by having executed.   The program according to claim 13, wherein the building intrusion loss estimation processing estimates the building intrusion loss by taking a difference between the estimated value of the received electric field strength and the measured value of the received electric field strength.   15. A recording medium on which the program according to claim 13 or 14 is recorded and readable by a computer.

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