JP2012222496A - Base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station capable of forming an optimum service area in accordance with the change of a communication environment within the service area of the own station.SOLUTION: A base station 1 includes: a communication information acquisition part 16 for periodically acquiring communication information including time information, mobile terminal position information, and modulation system information; a storage part 17 for storing the communication information; a communication information analysis part 18 for analyzing a communication environment with referring to the storage part 17; and an antenna tilt angle control part 14 for adjusting the largeness of a service area by controlling the antenna tilt angle of an antenna based on the analysis result of the communication environment by the communication information analysis part 18.

Description

  The present invention relates to a base station that performs antenna tilt control and adaptively controls a service area.

  Conventionally, when installing a base station, a service area (cell) that can communicate with a mobile terminal is determined based on various factors such as traffic volume, interference with surrounding areas, radio wave propagation characteristics, and installation location. Determine the antenna tilt angle of the base station antenna. However, the optimum service area varies with the increase of base stations and the change of surrounding communication environment (radio wave propagation environment). Therefore, a base station capable of adaptively controlling the service area is required.

  Therefore, by measuring the received signal strength (RSSI) from the surrounding base stations during times when the load on the base station is low, at the time of restarting, etc., and adjusting the antenna tilt angle according to the measurement results, A base station capable of forming an optimum service area with less interference even during operation is known (see, for example, Patent Document 1).

Japanese Patent Publication No. 2008-211667

  However, although the base station described in Patent Literature 1 can cope with changes in the communication environment between base stations by measuring RSSI from surrounding base stations, the communication environment within the service area of the own station Change (for example, the appearance of a new building) could not be detected. Therefore, for example, when a new high-rise building appears, the received radio wave intensity from the base station becomes weak behind the high-rise building, and the communication quality may deteriorate.

  In order to solve the above problems, an object of the present invention is to provide a base station capable of forming an optimum service area in response to changes in the communication environment within the service area of the own station.

  In order to solve the above problems, a base station according to the present invention stores a communication information acquisition unit that acquires communication information including position information of a mobile terminal, time information, and information on a modulation scheme during communication, and stores the communication information A storage unit, a communication information analysis unit that analyzes the communication environment based on the communication information with reference to the storage unit, and a service that controls the antenna tilt angle of the antenna according to the analysis result of the communication information analysis unit And an antenna tilt angle control unit that adjusts the size of the area.

  Further, in the base station according to the present invention, the communication information analysis unit determines the presence or absence of a radio wave insensitive zone by obtaining a data communication amount for each distance, and the antenna tilt angle control unit includes the communication information analysis unit. If it is determined that there is a radio wave insensitive zone, the size of the service area is adjusted so that the radio wave insensitive zone is not included.

  Further, in the base station according to the present invention, the communication information analysis unit determines a degree of communication congestion by obtaining a data communication amount for each time, and the antenna tilt angle control unit is determined by the communication information analysis unit. When it is determined that there is an area with a small amount of data communication according to the time zone, the size of the service area is adjusted so that the area is not included.

  According to the present invention, it is possible to form an optimum service area by controlling the antenna tilt angle of the antenna in accordance with a change in the communication environment within the service area of the own station.

It is a functional block diagram which shows schematic structure of the base station which concerns on 1st Embodiment by this invention. It is a figure which shows the example of the communication information memorize | stored in the memory | storage part of the base station which concerns on 1st Embodiment by this invention. It is a figure for demonstrating an antenna tilt angle. It is a figure for demonstrating control of an antenna tilt angle. 4 is a flowchart illustrating an operation of the base station according to the first embodiment of the present invention. It is a figure explaining operation | movement of the base station which concerns on 1st Embodiment by this invention. It is a figure which shows the example of an analysis of the communication information analysis part of the base station which concerns on 1st Embodiment by this invention. It is a flowchart which shows operation | movement of the base station which concerns on 2nd Embodiment by this invention. It is a figure which shows the example of an analysis of the communication information analysis part of the base station which concerns on 2nd Embodiment by this invention.

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

(First embodiment)
FIG. 1 is a functional block diagram showing a schematic configuration of a base station according to the first embodiment of the present invention. The base station 1 includes a radio communication unit 11, a transmission unit 12, a reception unit 13, an antenna tilt angle control unit 14, a control unit 15, a communication information acquisition unit 16, a storage unit 17, and a communication information analysis unit. 18 and performs wireless communication with a plurality of mobile terminals in the service area.

  The control unit 15 controls the operation of each processing unit (wireless communication unit 11, transmission unit 12, reception unit 13, antenna tilt angle control unit 14, communication information acquisition unit 16, storage unit 17, communication information analysis unit 18). . Further, the control unit 15 determines a modulation scheme based on SINR (Signal-to-Interference plus Noise power Ratio) of a signal received from the mobile terminal. For example, when the SINR is large (the quality of received data is high), a modulation scheme (for example, 64QAM) with a large modulation multi-value number is adopted to increase the data rate, and when the SINR is small, the data rate is decreased. A modulation scheme (for example, BPSK) with a small modulation multilevel number is employed.

  The wireless communication unit 11 transmits the transmission signal input from the transmission unit 12 to the mobile terminal via the antenna 2. In addition, the wireless communication unit 11 outputs a signal received via the antenna 2 to the reception unit 13.

  The transmission unit 12 generates a transmission signal by performing modulation based on the modulation scheme determined by the control unit 15, and outputs the generated transmission signal to the wireless communication unit 11. The receiving unit 13 performs processing such as AD conversion and demodulation on the signal input from the wireless communication unit 11 to generate a baseband signal, and outputs the generated baseband signal to the control unit 15.

  The communication information acquisition unit 16 periodically acquires communication information including time information, location information of the mobile terminal, and information on a modulation method (BPSK, 16QAM, etc.) during communication, and stores the acquired communication information in the storage unit 17. Output to. The time information is acquired from time data included in a GPS signal transmitted from, for example, a GPS (Global Positioning System) satellite. The location information of the mobile terminal is received from the mobile terminal. The mobile terminal acquires position information (latitude / longitude information) from the GPS signal. The modulation method is acquired from the control unit 15.

  The storage unit 17 stores a program for operating the base station 1 and the like, and stores communication information input from the communication information acquisition unit 16. FIG. 2 is a diagram illustrating an example of communication information stored in the storage unit 17. Although only the mobile terminals A and B are shown in this figure, the storage unit 17 stores communication information for all mobile terminals located in the service area.

  The communication information analysis unit 18 refers to the storage unit 17, statistically analyzes the communication environment based on the communication information, and outputs the analysis result to the antenna tilt angle control unit 14. In the present embodiment, the communication information analysis unit 18 determines the presence / absence of a radio wave insensitive zone by obtaining the data communication amount for each distance. Here, the radio wave insensitive zone refers to an area where radio waves from the base station are below a predetermined threshold. Further, the data communication amount is defined by (number of modulation schemes) × (number of mobile terminals).

  The antenna tilt angle control unit 14 adjusts the size of the service area by controlling the antenna tilt angle of the antenna 2 according to the analysis result input from the communication information analysis unit 18. FIG. 3 is a diagram for explaining the antenna tilt angle. The antenna 2 of the base station 1 emits a directional beam. At this time, an angle formed between the maximum beam directing direction and the horizontal direction is defined as an antenna tilt angle. As can be understood from this figure, by reducing the antenna tilt angle, the directional beam reaches farther and the service area can be expanded. Conversely, by increasing the antenna tilt angle, the distance that the directional beam reaches can be reduced, and the service area can be reduced.

  FIG. 4 is a diagram illustrating an example in which the antenna tilt angle of the antenna 2 is mechanically controlled. When the base station 1 has a sector configuration, the antenna tilt angle of the antenna 2 corresponding to each sector can be controlled as shown in FIG. As shown in FIG. 4B, when the antenna is directed downward, the antenna tilt angle increases, and the radio wave reach range is reduced from area a to area a '. In the case where the antenna 2 is an adaptive array antenna, the antenna tilt angle may be electrically controlled by adjusting the antenna weight.

  Next, the operation of the base station 1 configured as described above will be described. FIG. 5 is a flowchart showing the operation of the base station 1. The base station 1 acquires communication information by the communication information acquisition unit 16 and stores the communication information in the storage unit 17 (step S101). Subsequently, the base station 1 uses the communication information analysis unit 18 to statistically analyze the communication information with reference to the communication information stored in the storage unit 17 (step S102). And the communication information analysis part 18 determines the presence or absence of an electromagnetic wave dead zone by calculating | requiring the data communication amount for every distance (step S103).

  Here, the operation of the base station 1 will be described with reference to FIG. Area A indicates a service area (cell) when the antenna tilt angle of the antenna 2 is reduced, and area A ′ indicates a service area when the antenna tilt angle of the antenna 2 is increased. When the base station 1 is installed, the operation is started with the area A as the service area. However, when the building B is newly constructed after that, the radio wave insensitive zone C is generated behind the building B. In the radio wave insensitive zone C, the radio wave received from the base station 1 is weak, and the modulation method for communication also changes to a low order. In the worst case, communication becomes impossible.

  FIG. 7 is a diagram illustrating the amount of data communication with respect to the distance from the base station 1 in the Line α direction illustrated in FIG. 6. As shown in FIG. 7, the communication information analysis unit 18 obtains the data communication amount in a plurality of directions with the base station 1 as the center, thereby reducing the data communication amount (the data communication amount is equal to or less than a predetermined threshold). Is detected and the area is estimated as a radio wave insensitive zone. The communication information analysis unit 18 notifies the antenna tilt angle control unit 14 of the position of the radio wave insensitive zone (for example, the distance from the base station 1 to the radio wave insensitive zone). If the base station 1 determines in step S103 that there is a radio wave insensitive zone, the antenna tilt angle control unit 14 controls the antenna tilt angle of the antenna 2 in accordance with the position of the radio wave insensitive zone, and the radio wave insensitive zone. The service area is adjusted so as not to be included (step S104).

  That is, as shown in FIG. 6, when it is determined that there is a radio wave insensitive zone C in the area a, the antenna tilt angle of the antenna 2 corresponding to the area a is increased, and the service area is reduced to the area a ′. At the same time, the base station 1 instructs another adjacent base station (to distinguish the base station 1 from the other base station as the base station 1 ') to expand the service area. By including the radio wave insensitive zone C in the service area of the base station 1 ′, a mobile terminal located in the radio wave insensitive zone C can communicate with the base station 1 ′ and can cover the radio wave insensitive zone C.

  Thus, according to the base station 1 of the first embodiment, by analyzing communication information, when a new building appears after the base station 1 is installed, the antenna tilt angle of the antenna 2 is controlled. In addition, the size of the service area can be adjusted so as not to include the radio wave insensitive zone, and the optimum service area can be automatically formed.

(Second Embodiment)
Next, a second embodiment according to the present invention will be described. The configuration of the base station 1 is the same as that of the first embodiment, and only the analysis method by the communication information analysis unit 18 is different. In the present embodiment, the communication information analysis unit 18 determines the degree of communication congestion in the service area by obtaining the data communication volume for each hour.

  FIG. 8 is a flowchart illustrating the operation of the base station 1 according to the second embodiment. The base station 1 acquires communication information by the communication information acquisition unit 16 and stores the communication information in the storage unit 17 (step S201). Subsequently, the base station 1 analyzes the communication information with reference to the communication information stored in the storage unit 17 by the communication information analysis unit 18 (step S202). The communication information analysis unit 18 analyzes the communication information to determine the degree of communication congestion in the service area, that is, whether it is a time zone with a large amount of communication, or whether it is a time zone with a small amount of communication. Determination is made (step S203, step S205).

  FIG. 9 is a diagram illustrating an example of the amount of data communication for each time. As shown in FIG. 9, the communication information analysis unit 18 obtains the data communication volume for each time to detect an area where the data communication volume increases according to the time zone and an area where the data communication volume decreases according to the time zone. be able to. For example, in an office district, the amount of data communication is large during the day, but the amount of data communication is small at night. If the base station 1 determines in step S203 that the data communication volume is large (the data communication volume exceeds a predetermined threshold), the base station 1 reduces the antenna tilt angle of the antenna 2 and sets the service area to Cover (step S204). On the other hand, if it is determined in step S205 that the data communication amount is small (the data communication amount is equal to or less than a predetermined threshold), the antenna tilt angle of the antenna 2 is increased and the service area is reduced. (Step S206).

  For example, consider a case where service area A is divided into eight areas (a, b, c, d, a ', b', c ', d') as shown in FIG. Among these, if it is statistically obtained from the communication information that the amount of data communication is large in the area c during daytime and the amount of data communication is small in the nighttime period, the base station 1 The service area is reduced so that c is not included. At the same time, the base station 1 instructs another adjacent base station (to distinguish the base station 1 from the other base station as the base station 1 ') to expand the service area. By including the area c with a small amount of data communication in the service area of the base station 1 ′, a mobile terminal located in the area c can communicate with the base station 1 ′. The base station 1 can increase the communication speed for mobile terminals in the service area by reducing the service area.

  As described above, according to the base station 1 of the second embodiment, by analyzing the communication information, when the data communication amount changes according to the time zone, the antenna tilt angle of the antenna 2 is controlled, The size of the service area can be adjusted so that an area with a small amount of data communication is not included, and an optimum service area can be automatically formed.

  Each of the above-described embodiments has been described as a representative example, but many changes and substitutions can be made within the spirit and scope of the present invention, and further, each embodiment can be combined to realize another embodiment. It will be apparent to those skilled in the art that it can. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, the communication information analysis unit 18 may of course simultaneously perform statistical analysis based on distance and statistical analysis based on time.

  In the above-described embodiment, the base station 1 is configured to include the control unit 15 and the communication information analysis unit 18 independently. However, the control unit 15 may include the communication information analysis unit 18.

DESCRIPTION OF SYMBOLS 1 Base station 2 Antenna 11 Wireless communication part 12 Transmission part 13 Reception part 14 Antenna tilt angle control part 15 Control part 16 Communication information acquisition part 17 Storage part 18 Communication information analysis part

Claims (3)

A communication information acquisition unit for acquiring communication information including position information of a mobile terminal, time information, and information of a modulation method at the time of communication;
A storage unit for storing the communication information;
A communication information analysis unit that references the storage unit and analyzes a communication environment based on the communication information;
An antenna tilt angle control unit that controls the antenna tilt angle of the antenna according to the analysis result of the communication information analysis unit to adjust the size of the service area;
A base station comprising: The communication information analysis unit determines the presence or absence of a radio wave insensitive zone by determining the amount of data communication for each distance,
The antenna tilt angle control unit adjusts the size of the service area so that the radio wave insensitive zone is not included when the communication information analysis unit determines that the radio wave insensitive zone is present. The base station according to claim 1. The communication information analysis unit determines the degree of communication congestion by determining the amount of data communication per hour,
The antenna tilt angle control unit adjusts the size of the service area so that the area is not included when the communication information analysis unit determines that there is an area with a small amount of data communication according to a time zone. The base station according to claim 1 or 2, characterized in that

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