JP2014060785A - Wireless base station, and frequency band selection method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of autonomously adjusting a use frequency band of a base station to be newly constructed so as not to degrade a wireless quality of a peripheral existing base station, and to provide a wireless base station.SOLUTION: A wireless base station communicating with a wireless terminal transmits information related to a frequency band that the own station wants to use to a peripheral wireless base station via a channel, acquires information on a frequency band that the peripheral wireless base station makes the own station avoid to use as a response to the information, and selects a frequency band available for the self station, that is based on the information from the peripheral wireless base station, for the wireless communication with the wireless terminal.

Description

  The present invention relates to a radio base station and a frequency band selection method for the radio base station.

  As a general method for improving the communication environment in wireless communication, a new base station can be mentioned. In this case, a newly established base station allocates free radio resources to the terminal requesting connection regardless of the amount of interference that may occur with the existing neighboring base stations. There is a risk of affecting the radio communication environment of the radio base station.

  Therefore, when installing a new wireless base station, perform field tests to select candidate locations for installing the base station, and measure frequency bands with high interference with existing base stations around the candidate locations. After that, a frequency band with a small amount of interference is selected as a frequency band used by a newly installed base station, or the maximum transmission power of the base station is determined. For this field test, a spectrum analyzer, a device for collecting communication quality data (see Patent Document 1), or the like is used. Then, the base station is manually adjusted so that the determined use frequency band and transmission power are obtained.

JP 2001-119334 A

  However, every time a radio base station is installed, it is necessary to use a special device such as a spectrum analyzer or a device for collecting communication quality data in order to perform a field test around the installation location. ineffective. Therefore, in recent years, there is a demand for a technique in which the base station itself autonomously adjusts parameters such as a used frequency and a maximum transmission output.

  An object of the present invention made in view of such a point is that, when a new radio base station is installed, the radio quality of existing existing base stations in the vicinity is not deteriorated without performing a field test or the like that requires manual labor. Another object of the present invention is to provide a method and a radio base station for autonomously adjusting the frequency band used by a newly installed base station.

  The invention of the radio base station that communicates with the radio terminal according to the first aspect of achieving the above object transmits information on a frequency band that the local station wants to use to a neighboring radio base station via a line, and As a response to the above, the peripheral radio base station acquires information on a frequency band that the local station avoids using, and is used by the local station based on information from the peripheral radio base station for wireless communication with the wireless terminal. A possible frequency band is selected.

  Furthermore, the invention for selecting a frequency band to be used by a radio base station that communicates with a radio terminal according to the second aspect of achieving the above object is to provide information on a frequency band that the local station wants to use via a line. Transmitting to the peripheral radio base station, and as a response to the information, acquiring the information of the frequency band that the peripheral radio base station avoids its own use, and for the radio communication with the radio terminal, the peripheral Selecting a frequency band that can be used by the local station based on information from the wireless base station.

  According to the present invention, when a newly installed base station is activated for the first time, the base station is used based on the wireless communication status of existing neighboring base stations before starting wireless communication processing with the wireless terminal. A possible frequency band is acquired, and a frequency band to be used for communication with the wireless terminal that has requested communication is selected in the usable frequency band. Therefore, the newly installed base station can autonomously adjust the used frequency band so as not to deteriorate the radio quality of the existing base stations in the vicinity even if a field test requiring manual labor is not performed.

It is a figure which shows schematic structure of the wireless base station which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the radio | wireless communications system using the radio | wireless base station of FIG. FIG. 2 is a sequence diagram showing an operation of the radio base station in FIG. 1. An example of the interference avoidance process in the wireless base station of FIG. 1 is shown. It is a figure for demonstrating the interference avoidance process in the wireless base station of FIG. It is a functional block diagram of the base station which concerns on 2nd Embodiment of this invention. FIG. 7 is a sequence diagram showing an operation of the radio base station of FIG. 6. It is a flowchart which shows operation | movement of the wireless base station of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of a radio base station according to the first embodiment of the present invention. This radio base station 10 is based on LTE, for example, and relays communication of a mobile phone terminal.

  The radio base station 10 includes a line connection unit 11, a baseband unit 12, a control unit 13, an acquisition unit 14, a selection unit 15, a storage unit 16, a phase lock loop (PLL) 17, a transmission unit 18, and a reception unit. 19 is provided.

  The line connection unit 11 is connected to a line concentrator connected to the backbone network via a backhaul line 20 that is a relay line. The baseband unit 12 is configured by LSI (Logic Scale Integration) or the like, and performs baseband processing of signals transmitted / received by the transmission unit 18 and the reception unit 19 and signals transmitted / received via the line connection unit 11.

  The control unit 13 includes a CPU and includes an acquisition unit 14 and a selection unit 15. The acquisition unit 14 is information relating to a frequency band that can be used based on a wireless communication state such as a frequency band used by an existing base station (hereinafter referred to as a peripheral base station) located in the vicinity of the own station and a maximum transmission power. To get. Then, the selection unit 15 allocates a band (radio resource) to the wireless terminal that has made a connection request to the local station based on the information on the usable frequency band acquired by the acquisition unit 14. Here, the storage unit 16 is the frequency band of the neighboring base station and the maximum transmission output obtained when the acquisition unit 14 acquires the usable frequency band, and the channel frequency assigned to the wireless terminal by the selection unit 15. Stores information such as the maximum transmission output of the own station and position information.

  Further, the control unit 13 sets the frequency bands of the transmission unit 18 and the reception unit 19 according to the usable frequency band selected by the selection unit 15. Further, the control unit 13 converts the information stored in the storage unit 16 such as the channel frequency assigned to the wireless terminal by the selection unit 15 and the maximum transmission output and position information into a baseband signal in the baseband unit 12, The data is transmitted to the neighboring base stations via the line connection unit 11 and the backhaul line 20.

  FIG. 2 shows an example of a radio communication system using the radio base station 10 according to the present embodiment. Base stations 100A to 100E are already provided, and terminals 1 to 4 are located in the communicable area and can communicate, but terminal 5 is outside this area and cannot communicate. It is assumed that the base station 10 is newly established to expand the area where the base stations 100A to 100E are performing the communication relay service. Since the base station 10 is newly installed, the terminal 5 that has been outside the communicable area can communicate. The base stations 100A to 100E and the base station 10 are each connected to the line concentrator 21 via the backhaul line 20.

  The base station 10 according to the present invention exchanges information with a base station already provided through a backhaul line 20 by a method described in detail below with reference to FIG. This adjusts the frequency band used.

  FIG. 3 is a sequence diagram showing an operation of radio base station 10 according to the present embodiment. Here, it is assumed that the base station 10 autonomously adjusts the downlink frequency band to avoid interference. The newly installed base station 10 has a frequency band that it wants to use as a downlink frequency band, a maximum transmission power, and location information of the base station when it is first activated before it starts a service as a relay base station. The communication parameter information such as the signal is converted by the baseband unit 12 and transmitted to the surrounding base stations 100A to 100C where interference may occur through the line connection unit 11 and the line concentrator 21. Here, the frequency band that the local station wants to use as the downlink frequency band includes, for example, a numerical range determined for each telecommunications carrier and a numerical range arbitrarily determined by the telecommunications carrier when installing the base station. It is done.

  The neighboring base stations 100A to 100C need to avoid using the base station 10 within the frequency band that the base station 10 wants to use based on the received communication parameter information of the base station 10 (ie, avoid interference). ) It is determined whether there is a frequency band, and when there is a frequency band that needs interference avoidance, the frequency band is notified to the base station 10 via the backhaul line 20 as an interference avoidance frequency band. This determination and notification may be performed not at the base stations 100A to 100C but at a base station management center (not shown) that manages and manages the base stations. Although not shown, if there is no frequency band that needs interference avoidance, base stations 100A to 100C notify base station 10 to that effect. By the same operation, the base station 10 acquires an interference avoidance frequency band for the uplink frequency band.

  When the terminal makes a communication request (downlink frequency band allocation request), the base station 10 performs interference avoidance determination described in detail with reference to FIG. A frequency band is assigned as a downlink frequency band to a wireless terminal that has requested communication.

  FIG. 4 shows an example of interference avoidance processing in the radio base station according to the present embodiment. The acquisition unit 14 of the base station 10 acquires the interference avoidance frequency band by the method according to the sequence diagram of FIG. When there is a communication request from the terminal to the base station 10 (step S301), the acquisition unit 14 of the base station 10 determines whether there is a band that does not overlap with the interference avoidance frequency band in the frequency band that the local station wants to use for the downlink. Is determined (step S302). That is, the acquisition unit 14 determines whether or not a downlink frequency band can be allocated to a terminal without using any overlapping band with the base stations 100A to 100C. If there is a frequency band that does not overlap with the interference avoidance frequency band in the frequency band that the local station wants to use, the selection unit 15 selects the frequency band (hereinafter referred to as “band I usable by the base station 10”). Then, an allocation process is performed (step S303). Thereby, the downlink frequency band is selected.

  On the other hand, when there is no band that does not overlap with the interference avoidance frequency band in the frequency band that the local station wants to use, the selection unit 15 of the base station 10 has a frequency band with the smallest amount of interference (hereinafter, the interference avoidance frequency band). The allocation process is performed in “band II usable by the base station 10” (step S304). Here, the band with the smallest amount of interference is calculated based on, for example, the positional relationship with the neighboring base stations and the maximum transmission output. Further, if it is determined in step S302 that there is no band I that can be used by the base station 10, the base station 10 may reject the terminal communication request (not shown). In this case, in step S304, the selection unit 15 does not allocate a small band that causes interference to the terminal, and as a result, the communication quality of the wireless terminal during other communication can be kept high.

  5A and 5B, the band that the base station 10 wants to use, the band that the peripheral base stations 100A to 100C are using, and the base station 10 that are used in the case of flowing from the step S302 to S303. FIG. 5A shows the relationship with the possible band I, and FIG. 5B shows the relationship as case 2 in the case of flowing from step S302 to S304.

  In Case 1, the band III that the base station 10 desires to use is a band III that is not used by the peripheral base stations 100A to 100C of the base station 10. Therefore, the selection unit 15 of the base station 10 performs band allocation processing for terminals in the band I corresponding to the band III. On the other hand, in case 2, all the bands that the base station 10 wants to use are being used by the peripheral base stations 100A to 100C. At this time, the selection unit 15 of the base station 10 performs band allocation processing on the terminals in the band II, which is the band with the smallest amount of interference among the bands used by the neighboring base stations 100A to 100C.

As described above, according to the base station 10 according to the present embodiment, when the frequency band to be used by the base station 10 is determined, interference is likely to occur by communicating with the existing peripheral base stations 100A to 100C. The frequency band to be used is determined avoiding the frequency band. Therefore, the communicable area can be expanded without impairing the communication quality of the peripheral base stations 100A to 100C.
(Second Embodiment)
FIG. 6 is a functional block diagram of a base station according to the second embodiment of the present invention. The base station 60 is configured to supply the reception output of the reception unit 19 to the acquisition unit 14 of the control unit 13 in the configuration shown in FIG. 1, and the other configuration is the same as that of FIG. Are given the same reference numerals. The acquisition unit 14 acquires a usable frequency band based on a signal received by the reception unit 19. For this reason, the acquisition unit 14, based on the reception signal of the reception unit 19, the downlink frequency band used by the neighboring base stations, the uplink frequency band of the terminals located around the base station 60, and reception thereof The power is measured, and a frequency band in which the received power value exceeds a predetermined threshold is acquired as an interference avoidance frequency band. This prevents the base station 60 from using a frequency band that reaches the base station 60 with a power value exceeding a predetermined threshold, and prevents communication quality from being impaired.

  FIG. 7 is a sequence diagram showing the operation of the base station 60 in this case. The acquisition unit 14 of the base station 60 measures the downlink frequency bands and the received power values of the base stations 100A to 100C based on the reception signal received by the reception unit 19 before the service is started after the initial activation. Then, the interference avoidance frequency band is grasped based on the measurement result, and the downlink frequency band is assigned to the wireless terminal that has made a communication request (downlink frequency assignment request) in a frequency band other than the interference avoidance frequency. According to a similar procedure, the base station 60 also performs interference avoidance and allocation processing for the uplink frequency band.

  FIG. 8 is a flowchart showing the operation of the radio base station according to this embodiment. The base station 60 shifts to the downlink frequency reception mode after the initial activation (step S701). Then, the acquisition unit 14 measures the downlink frequency bands of the neighboring base stations 100A to 100C and the received power based on the received signal (step S702). Furthermore, the acquisition unit 14 determines whether or not the received power intensity exceeds a predetermined threshold (hereinafter referred to as an interference avoidance determination threshold) for each downlink frequency band (step S703). As a result, when the predetermined threshold value is exceeded, the control unit 13 stores the frequency band as an interference avoidance frequency band in the storage unit 16 (step S704).

  Subsequently, the acquisition unit 14 of the base station 10 shifts to the uplink frequency reception mode (step S705). Then, the acquisition unit 14 measures the uplink frequency band from the terminal and its received power (step S706). Furthermore, the acquisition unit 14 determines whether or not the interference avoidance determination threshold is exceeded for each received uplink frequency band (step S707). As a result, when the predetermined threshold value is exceeded, the control unit 13 stores the frequency band as an interference avoidance frequency band in the storage unit 16 (step S708).

  The radio base station 60 according to the present embodiment measures the used frequency band and the maximum transmission power of the neighboring base stations based on the reception signal of the reception unit 19, and avoids interference with the radio terminal to reduce the band. Since it can be allocated, it is possible to autonomously select the used frequency band of its own station without placing a burden of notifying the neighboring base stations 100A to 100C.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation or change is possible. For example, the radio base station according to the first embodiment notifies the peripheral base stations 100A to 100C or the base station management center of the frequency band that the radio base station wants to use, but the base station 10 transmits the base station 100A through the backhaul line 20. It is also possible to obtain a use frequency band of ˜100 C and obtain a usable frequency band based on them. In this case, it is not necessary for the peripheral base stations 100A to 100C or the base station management center to perform the interference avoidance frequency determination, and the processing is simplified.

1 to 5 terminal 10 radio base station 11 line connection unit 12 baseband unit 13 control unit 14 acquisition unit 15 selection unit 16 storage unit 17 PLL
18 transmitting unit 19 receiving unit 20 backhaul line 21 concentrator 60 radio base station 100A to E radio base station

Claims (2)

In a wireless base station that communicates with a wireless terminal,
Information on the frequency band that the local station wants to use is transmitted to the surrounding wireless base station via the line, and as a response to the information, information on the frequency band that the surrounding wireless base station avoids using is acquired. ,
For wireless communication with the wireless terminal, select a frequency band that can be used by the own station based on information from the surrounding wireless base station,
A wireless base station characterized by that. In selecting the frequency band used by the wireless base station that communicates with the wireless terminal,
Information on the frequency band that the local station wants to use is transmitted to the surrounding radio base station via the line, and as a response to the information, information on the frequency band that the surrounding radio base station avoids using is acquired. Steps,
Selecting a frequency band that can be used by the local station based on information from the surrounding radio base station for radio communication with the radio terminal; and
A frequency band selection method for a radio base station, comprising:

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