JP2011146794A - Wireless communication base station apparatus and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication base station apparatus for reducing interference to be given to a different wireless communication system sharing a frequency in an uplink, and to provide a wireless communication method. <P>SOLUTION: A UL frequency allocating part 105 respectively acquires location information of a terminal from a terminal location information managing part 103 and location information of an FSS earth station from an interference receiving fixed station location information managing part 104, and allocates a UL frequency to each terminal on the basis of a relation among the acquired location information of the terminal and location information of the FSS earth station, and location information of its own station. Specifically, the UL frequency allocating part 105 does not allocate an FSS using band to a terminal which is located in the direction of the FSS earth station with respect to the base station within a cell of the base station and is farther than the FSS earth station. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication base station apparatus and a radio communication method that share a frequency band with different communication systems.

  At the World Radio Communications Conference (WRC-07) held at the end of 2007, new frequency bands were allocated for IMT-Advanced mobile communication services. As a result, more than 100 countries around the world have announced that they will use the 3.4 to 3.6 GHz band for IMT-Advanced services, and this frequency band has become the de facto international frequency for mobile communications.

  However, this band is called C-band, and is used in the existing Fixed Satellite Communication (FSS), and in countries that have a large land area, such as TV just below the equator where rainfall attenuation is significant. It is used as an emergency line for broadcasting and disasters. In such countries, the FSS has become an important communication means, and it is necessary for IMT-Advanced to not interfere with the FSS when sharing the same frequency as the FSS.

  For example, as shown in FIG. 1, by applying the technology described in Non-Patent Document 1, etc., an IMT-Advanced terminal (hereinafter simply referred to as “terminal”) performs directivity control, and an IMT-Advanced base station (hereinafter referred to as “terminal”). A method is considered in which a beam directed to a “base station” is formed and transmitted. According to this method, useless radiation can be suppressed and interference with the FSS earth station can be reduced.

Nobuyoshi Kikuma, "Adaptive signal processing with array antenna", Science and Technology Publishing

  However, in the technique described in Non-Patent Document 1 described above, even when the terminal forms a beam toward the base station, as shown in FIG. 2, the FSS earth station is located between the terminal and the base station. The directivity of the terminal faces the direction of the FSS earth station, causing interference to the FSS earth station. In particular, when the terminal, the base station, and the FSS earth station are located in a straight line, there is a high possibility that interference with the FSS earth station appears more remarkably.

  In addition, when the terminal, the base station, and the FSS earth station are located in a state that is close to a straight line in this way, and a structure such as a house, a building, or a steel tower exists near the FSS earth station as shown in FIG. The distance attenuation of the multipath reflected by these structures is small, and the multipath gives large interference to the FSS earth station.

  An object of the present invention is to provide a radio communication base station apparatus and a radio communication method for reducing interference given to other radio communication systems sharing a frequency in an uplink.

  A radio communication base station apparatus according to the present invention includes a terminal position information management unit that manages position information of a radio communication terminal apparatus that is a communication partner, and a fixed station in another radio communication system that uses a frequency overlapping with its own radio communication system. Fixed station position information managing means for managing the position information of the other wireless communication system based on the position of the wireless communication terminal apparatus and the position of the fixed station as an uplink frequency to the wireless communication terminal apparatus Frequency allocation means for controlling whether to allocate or not.

  The radio communication method of the present invention manages a terminal location information management step for managing location information of a radio communication terminal device, and location information of a fixed station in another radio communication system that uses a frequency overlapping with its own radio communication system. Based on the fixed station position information management step, the position of the wireless communication terminal device and the position of the fixed station, the wireless communication base station device uses the bandwidth of the other wireless communication system as an uplink frequency to the wireless communication terminal device. And a frequency allocation step for controlling whether or not to allocate the frequency.

  ADVANTAGE OF THE INVENTION According to this invention, the interference given to the other radio | wireless communications system which shares a frequency in an uplink can be reduced.

Diagram for explaining the technology described in Non-Patent Document 1. The figure which shows a mode that a terminal gives interference to a FSS earth station The figure which shows a mode that the multipath reflected by the structure gives interference to a FSS earth station The block diagram which shows the structure of the base station which concerns on Embodiment 1, 3, 4 of this invention The block diagram which shows the structure of the terminal which concerns on Embodiment 1, 3, 4 of this invention Schematic diagram showing the area where the interfered system use band cannot be allocated Schematic diagram showing the interfered system use band allocation impossible area and the interfered system use band assignment condition area The block diagram which shows the structure of the monitor station which concerns on Embodiment 2, 4 of this invention The block diagram which shows the structure of the base station which concerns on Embodiment 2 of this invention. Schematic diagram showing how to control the size of the area where the interfered system use band cannot be allocated The block diagram which shows the structure of a base station and a monitor station when a monitor station and a base station are wired-connected The schematic diagram which shows the interfered system use band allocation non-assignment area which concerns on Embodiment 3 of this invention. Diagram showing beam width definition The figure which shows an example of the range determination method of the interfered system use band allocation non-allocable area which concerns on Embodiment 4 of this invention. The figure which shows the other example of the range determination method of the interfered system use band allocation non-allocable area which concerns on Embodiment 4 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in the embodiment, components having the same function are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
FIG. 4 is a block diagram showing the configuration of the IMT-Advanced base station apparatus (hereinafter simply referred to as “base station”) according to Embodiment 1 of the present invention. In this figure, a reception processing unit 102 receives a signal transmitted from an IMT-Advanced terminal (hereinafter simply referred to as “terminal”) via an antenna 101, and converts the received signal into an A / D conversion process and a baseband band. Predetermined radio reception processing such as down-conversion processing, demodulation / decoding, and the like, and output to terminal location information management section 103.

  The terminal location information management unit 103 extracts terminal location information included in the signal output from the reception processing unit 102, holds the extracted terminal location information, and outputs it to a UL (Up Link) frequency allocation unit 105.

  The interfered fixed station location information management unit 104 stores in advance location information of the interfered fixed station (that is, the FSS earth station) located in the cell of the local station, and the UL frequency allocation unit 105 as necessary. Is read out. In the following description, the FSS wireless communication system is referred to as an interfered system.

  UL frequency allocating section 105 acquires terminal position information from terminal position information managing section 103 and interfered fixed station position information from interfered fixed station position information managing section 104, and acquires the acquired terminal position information and received position information. The UL frequency is allocated to each terminal from the relationship between the position information of the fixed interference station and the position information of the own station, and UL frequency allocation information indicating the allocated UL frequency is output to the transmission processing unit 106. Note that the UL frequency allocation unit 105 may appropriately change the allocation frequency according to the reception quality of the UL signal transmitted from the terminal. The UL frequency allocating unit 105 preliminarily determines the UL frequency to be allocated to the terminal position based on the position information of the interfered fixed station held by the interfered fixed station position information management unit 104 and the position information of the own station. The UL frequency to be allocated may be determined using the terminal position information acquired from the terminal position information management unit 103 and the corresponding information.

  The transmission processing unit 106 encodes, modulates, and converts digital signals from UL frequency allocation information output from the UL frequency allocation unit 105 and UL signals such as transmission data input from a transmission data generation unit (not shown). Predetermined radio transmission processing such as processing and up-conversion processing to a radio frequency band is performed, and radio transmission is performed from the antenna 107.

  FIG. 5 is a block diagram showing a configuration of terminal 200 according to Embodiment 1 of the present invention. In this figure, a reception processing unit 202 receives a signal transmitted from a base station via an antenna 201, and performs A / D conversion processing, down-conversion processing to a baseband band, demodulation / decoding, etc. on the received signal. A predetermined radio reception process is performed and output to the arrival direction estimation unit 203 and the UL frequency information acquisition unit 204.

  The arrival direction estimation unit 203 estimates the direction of the base station based on the signal output from the reception processing unit 202, and outputs the estimation result to the transmission processing unit 206. Although not shown, when a plurality of reception antennas are required for direction of arrival estimation, a reception antenna may be prepared in addition to the antenna 201.

  The UL frequency information acquisition unit 204 acquires UL frequency allocation information from the signal output from the reception processing unit 202 and notifies the transmission processing unit 206 of the acquired UL frequency allocation information.

  The position information acquisition unit 205 acquires the position information of its own terminal by a positioning function such as a positioning means using GPS (Global Positioning System) or information received from a base station, and sends the acquired position information to the transmission processing unit 206. Notice.

  The transmission processing unit 206 encodes, modulates, and converts digital signals from the terminal location information notified from the location information acquisition unit 205 and UL signals such as transmission data input from a transmission data generation unit (not shown). Predetermined radio transmission processing such as processing and up-conversion processing to a radio frequency band is performed, and radio transmission is performed from the antenna 207. Here, before the UL frequency is allocated from the base station according to the location of the terminal, for example, when transmitting location information for the first time, interference is avoided by transmitting using a band other than the interfered system use band. . In addition, when the UL frequency is allocated according to the position from the base station, the transmission processing unit 206 uses the frequency indicated in the UL frequency allocation information output from the UL frequency information acquisition unit 204 to determine the direction of arrival. A beam is formed in the direction of the base station output from the estimation unit 203 and transmitted.

  Next, the operation of UL frequency allocation section 105 of the base station shown in FIG. 4 will be described in detail. In the cell of the base station, the UL frequency allocating unit 105 transmits the UL frequency as a UL frequency to a terminal that is in the direction of the fixed station that is interfered with the base station and that is far from the fixed station. Does not allocate used bandwidth. This state is schematically shown in FIG. In FIG. 6, the interfered system use band is not assigned as a UL frequency to a terminal that exists in an area covered by diagonal lines including the interfered fixed station (area where the interfered system use band cannot be assigned). Thereby, even if a terminal forms a beam in the direction of the base station, it is possible to reduce interference given to the interfered fixed station.

  However, as shown in FIG. 7, the UL frequency allocation unit 105 reduces the area where the interfered system use band cannot be allocated, and on both sides of the area (interfered system use band allocation condition area), under a predetermined condition, A band to be used for the interfered system may be allocated. As the predetermined condition, for example, when the number of terminals existing in the own cell exceeds a certain number or more (that is, when resources of the UL frequency to be allocated are exhausted), or when the interference system of the terminal is used A case where the UL quality outside the band is less than a predetermined value may be considered.

  As described above, according to Embodiment 1, in a cell of a base station, a terminal that is in the same direction as the interfered fixed station with respect to the base station and is located farther than the interfered fixed station By not assigning the interfered system use band, even if the terminal forms a beam toward the base station, it is possible to reduce interference given to the interfered fixed station.

(Embodiment 2)
FIG. 8 is a block diagram showing a configuration of monitor station 300 according to Embodiment 2 of the present invention. The monitor station 300 is arranged at the position of the interfered fixed station. In FIG. 8, the reception processing unit 302 receives the UL signal transmitted from the terminal via the antenna 301, and performs filtering processing, A / D conversion processing, and baseband transmission on the received signal as necessary. Pre-processing necessary for measuring the interference level such as down-conversion processing is performed, and the result is output to the interference level measuring unit 303.

  The interference level measurement unit 303 measures the reception level of the signal output from the reception processing unit 302, that is, the interference level in the interfered system, and outputs interference level information indicating the measured interference level to the transmission processing unit 304. The reception level to be measured may be a total of all received signals, a value for each terminal, or a value for each frequency component. Further, the measurement of the interference level and the transmission of the interference level information are performed periodically.

  The transmission processing unit 304 performs predetermined wireless transmission processing such as encoding, modulation, digital-analog conversion processing, up-conversion processing to a radio frequency band, and the like on the interference level information output from the interference level measurement unit 303. Wireless transmission. However, at this time, transmission is performed using a frequency other than the band used by the interfered system.

  FIG. 9 is a block diagram showing a configuration of base station 400 according to Embodiment 2 of the present invention. FIG. 9 differs from FIG. 4 in that an interference level information acquisition unit 401 is added and the UL frequency allocation unit 105 is changed to a UL frequency allocation unit 402.

  The interference level information acquisition unit 401 extracts the interference level information transmitted from the monitor station 300 included in the signal output from the reception processing unit 102, and outputs the extracted interference level information to the UL frequency allocation unit 402.

  The UL frequency allocation unit 402 controls the size of an area to which no interfered system use band is allocated (an interfered system use band unallocated area) according to the interference level output from the interference level information acquisition unit 401. That is, as shown in FIG. 10, when the interference level is larger than a predetermined threshold, the area where the interfered system use band cannot be allocated is expanded, and when the interference level is less than the predetermined threshold, the interfered system use band is expanded. Reduce the unallocated area. Here, “interfered system use band allocation condition area” is shown in FIG. 10, but this is not always necessary.

  As a result, it is possible to increase the number of terminals to which the interfered system use band is allocated without increasing the interference given to the interfered fixed station, thereby improving the throughput of the IMT-Advanced system.

  As described above, according to the second embodiment, according to the interference level given to the interfered fixed station, the size of the area where the interfered system use band is not assigned to the UL frequency is controlled, and given to the interfered fixed station. While reducing interference, the throughput of an IMT-Advanced system can be improved.

  In this embodiment, the case where the monitor station and the base station are wirelessly connected has been described as an example. However, the monitor station and the base station may be connected by wire. In this case, as shown in FIG. 11, the interference level information is notified from the transmission processing unit of the monitor station to the frequency allocation unit of the base station.

(Embodiment 3)
The configurations of the base station and the terminal according to Embodiment 3 of the present invention are the same as the configurations of FIGS. 4 and 5 shown in Embodiment 1, and only some functions are different. Is used to explain different functions.

  The UL frequency allocating unit 105 is connected to a terminal that is in the same direction as the interfered fixed station with respect to the base station in a cell of the base station and is located farther than the interfered fixed station. The use band is not assigned as the UL frequency. Further, when the interfered fixed station is located near the base station, the interfered system use band is not assigned as a UL frequency to a terminal located in a direction opposite to the interfered fixed station with respect to the base station.

  This is schematically shown in FIG. In FIG. 12, no interference system use band is assigned as a UL frequency to a terminal existing in an area covered with diagonal lines including an interference fixed station. Thereby, even when the interfered fixed station is located near the base station, it is possible to reduce interference given to the interfered fixed station.

  As described above, according to the third embodiment, in the cell of the base station, by not allocating the interfered system use band to the terminal located in the opposite direction to the interfered fixed station with reference to the base station, Even when the fixed station is located near the base station, it is possible to reduce interference given to the interfered fixed station.

(Embodiment 4)
The configurations of the base station and the terminal according to Embodiment 4 of the present invention are the same as the configurations of FIG. 4 and FIG. 5 shown in Embodiment 1, and also the monitor station according to Embodiment 4 of the present invention. The configuration is the same as the configuration of FIG. 8 described in the second embodiment, and only some functions are different. Therefore, the different functions will be described with reference to these drawings. In the present embodiment, the range of “interfered system use band unallocated area” in the first embodiment and the third embodiment and the initial range of “interfered system use band unallocated area” in the second embodiment are defined. An example of a specific method for determination will be shown.

  Here, let φ be the upper limit of the width of the beam formed when the terminal transmits to the base station (hereinafter referred to as “beam width”). That is, all the terminals perform transmission with a beam width of φ or less. Specifically, as shown in FIG. 13, the angle at which the gain is 3 dB lower than the antenna front direction is called the beam width (or half-value width).

  FIG. 14 shows a method of determining the range (or initial range) of the area where the interfered system use band cannot be allocated. First, when there is a terminal that performs transmission at the upper limit φ of the beam width at the cell edge, no interference is given to the interfered fixed station, that is, the range of the terminal position where no interfered fixed station exists in the beam. Ask. Next, the area in the cell on the side where the angle between the two terminals existing at the limit position that does not interfere with the interfered fixed station and the interfered fixed station is connected by a straight line, and the angle when the line is connected is smaller than 180 ° (A range covered with oblique lines) is an area where the interfered system use band cannot be allocated.

  In FIG. 14, as shown in FIG. 14 (a), FIG. 14 (b), and FIG. 14 (c) in order of increasing distance between the base station and the interfered fixed station, as shown in FIG. The closer the distance to the interference fixed station is, the larger the range of the non-interfered system use band allocation area is, and the farther the area is, the smaller the range of the non-interference system use band allocation area is.

  An example in which the base station and the interfered fixed station are close to each other is shown in FIG. In this case, similarly, in the area opposite to the interfered fixed station when viewed from the base station, when there is a terminal having a beam width φ at the cell edge, a range of terminal positions that do not interfere with the interfered fixed station is obtained. . Next, an area in the cell on the side where the angle between the two terminals existing at the limit position that does not interfere with the interfered fixed station and the base station is connected by a straight line and the angle when the line is connected is smaller than 180 ° (see FIG. The area covered with diagonal lines in the upper part of FIG.

  Here, in either case of FIG. 14 and FIG. 15, in addition to the range determined by the above-described method, the area around the interfered fixed station may also be an area where the interfered system use band cannot be allocated. This is because when there is a terminal near the interfered fixed station, even if the beam is not directed toward the interfered fixed station, there is a possibility of giving large interference due to reflection, etc. It is valid.

  Further, the range determined by the above-described method may be used as the lower limit value of the area where the interfered system use band cannot be allocated, instead of being used as the range of the interfered system use band cannot be assigned (or the initial value of the range). That is, in order to more reliably reduce interference with the interfered fixed station, the actual interfered system use band unallocated area may be a wider range than the range determined by the above method.

  As described above, according to the above method, since the upper limit value of the beam width of each terminal is determined, and the position of the interfered fixed station and the cell range are fixed, the base station uses the interfered system in advance. It is possible to determine the range of the band unassignable area and hold the information. That is, UL frequency allocating section 105 (or UL frequency allocating section 402) obtains the position information of the interfered fixed station, the position information of the own station, and the upper limit value of the beam width of the terminal obtained from the interfered fixed station position information management section 104 Based on φ, the range (or initial range) of the interfered system use band unassignable area is determined, and the UL frequency of each terminal is determined based on the terminal position information acquired from the terminal position information management unit 103. Make an assignment.

  Thus, according to the fourth embodiment, two terminals existing at the cell edge do not interfere with the interfered fixed station based on the upper limit value of the beam width of the terminal, the position of the terminal, and the position of the interfered fixed station. By obtaining the limit of the position and setting the inside of the limit position as the non-interfered system use band assignable area, the interfered system use band assignable area can be effectively set.

  In each of the above-described embodiments, the position of the interfered fixed station has been described as being constant, but when the number of the interfered fixed station increases or decreases, What is necessary is just to update the information of the interfered fixed station location information management part 104 each time. Moreover, what is necessary is just to update the information which shows the correspondence of the terminal position and UL frequency which the UL frequency allocation part 105 has as needed.

  The present invention is not limited to IMT-Advanced or FSS, but is applicable to a cellular radio communication system that shares a frequency with a radio communication system having a fixed station (or semi-fixed station).

  The radio communication base station apparatus and radio communication method according to the present invention can be applied to a radio communication system that needs to share a frequency with other radio communication systems such as an IMT-Advanced system.

101, 107, 201, 207, 301, 305 Antenna 102, 202, 302 Reception processing unit 103 Terminal location information management unit 104 Interfering fixed station location information management unit 105, 402 UL frequency allocation unit 106, 206, 304 Transmission processing unit 203 Direction-of-arrival estimation unit 204 UL frequency information acquisition unit 205 Position information acquisition unit 303 Interference level measurement unit 401 Interference level information acquisition unit

Claims (9)

Terminal location information management means for managing location information of a wireless communication terminal device which is a communication partner;
Fixed station position information management means for managing position information of a fixed station in another wireless communication system using a frequency overlapping with its own wireless communication system;
Based on the position of the wireless communication terminal device and the position of the fixed station, frequency allocation means for controlling whether to allocate a use band of the other wireless communication system as an uplink frequency to the wireless communication terminal device;
A wireless communication base station apparatus comprising:   In the cell of the own station, the frequency allocating means is arranged in the same direction as the fixed station with respect to the own station and in a position farther than the fixed station to the other radio communication terminal device. The radio communication base station apparatus according to claim 1, wherein a use band of the communication system is not allocated.   3. The radio communication according to claim 2, wherein the frequency allocating unit allocates a use band of the other radio communication system to radio communication terminal devices located on both sides of an area where the use band of the other radio communication system is not assigned. Base station device. Further comprising interference level information acquisition means for acquiring an interference level in the fixed station;
4. The radio communication base station apparatus according to claim 1, wherein the frequency allocating unit controls a size of an area where a use band of the other radio communication system is not allocated according to the interference level. 5. .   When the fixed station is located near the own station, the frequency allocating means allocates a use band of the other radio communication system to a radio communication terminal device located in a direction opposite to the fixed station with respect to the own station. The radio communication base station apparatus according to any one of claims 1 to 4, which is not assigned.   The frequency allocating unit determines an upper limit value of a beam width directed to the own station when all wireless communication terminal devices communicating with the own station transmit to the own station, and performs transmission with the upper limit value of the beam width. When the wireless communication terminal device is present at the cell edge of the local station, two points of the position of the wireless communication terminal device that are the limit of not causing interference to the fixed station are obtained, and these two points and the fixed station are 5. The wireless communication terminal apparatus according to any one of claims 1 to 4, wherein a use band of the other wireless communication system is not allocated to a wireless communication terminal apparatus existing in an area in the cell on the side where the angle when connecting with a straight line is smaller than 180 degrees. A radio communication base station apparatus according to claim 1.   When the fixed station is located near the local station, the frequency allocating unit is configured so that a wireless communication terminal that performs transmission at the upper limit value of the beam width in a direction opposite to the fixed station with respect to the local station Two points of the position of the wireless communication terminal device that is the limit that does not give interference to the fixed station when it exists at the cell edge constituting the angle, and the angle when these two points and the own station are connected by a straight line are 180 ° The radio communication base station apparatus according to claim 6, wherein a use band of the other radio communication system is not allocated to a radio communication terminal apparatus existing in an area in a smaller cell.   The frequency allocating unit does not allocate a use band of the other radio communication system to a radio communication terminal device existing in the periphery of the fixed station in addition to an area where the use band of the other radio communication system is not assigned. The radio communication base station apparatus according to claim 6 or 7. A terminal location information management step for managing location information of the wireless communication terminal device;
A fixed station position information management step for managing position information of a fixed station of another wireless communication system that uses a frequency overlapping with its own wireless communication system;
Based on the position of the radio communication terminal apparatus and the position of the fixed station, the radio communication base station apparatus controls whether or not to allocate the use band of the other radio communication system as an uplink frequency to the radio communication terminal apparatus A frequency allocation step;
A wireless communication method comprising:

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