JP2017017482A - Radio communication relay device and radio communication relay method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication relay device and a radio communication relay method, capable of minimizing a required distance between a reception antenna and a transmission antenna of the radio communication relay device while assuring throughput of an access link from the radio communication relay device to a mobile station (UE).SOLUTION: A radio communication relay device performs radio communication of a backhaul link with a base station at a first frequency within a predetermined frequency bandwidth allocated to a mobile communication system, demodulates a received radio signal of the backhaul link at the first frequency, and generates a radio signal of an access link at a second frequency by modulating the demodulated signal. The radio communication relay device determines at least either EPRE or the maximum number of PRB for transmitting a radio signal of an access link at the second frequency based on a received signal level of a radio signal of the backhaul link at the first frequency, and performs radio communication of the generated access link at the second frequency with a mobile station located in a cell of the base station.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication relay device and a wireless communication relay method for relaying mobile communication wireless communication.

  2. Description of the Related Art Conventionally, with the start of service in a mobile communication system using LTE (Long Term Evolution) (see Non-Patent Document 1) in mobile communication, high-speed data communication has become possible, and various services can be provided. For example, when 2 × 2 MIMO is applied with a frequency band of 15 MHz, the maximum theoretical throughput of LTE between a base station and a user equipment (UE: User Equipment) as a mobile station reaches 100 Mbps.

  However, in an actual commercial environment, particularly a cell edge user apparatus, only a throughput of several Mbps can be enjoyed due to the deterioration of the received signal quality. Furthermore, since the frequency band used for radio communication between the base station and the user apparatus (mobile station) is shared by a plurality of UEs, the actual throughput per user apparatus may be less than 1 Mbps. In order to solve this problem, studies have been made on a frequency conversion relay that receives a radio wave from a base station, demodulates it, remodulates and amplifies it to a different frequency, and transmits it to a user apparatus. Frequency conversion relays can mainly expand the coverage and capacity of base stations by introducing high gain antennas and advanced reception technology. However, when this frequency conversion relay is performed, it has been found that there is a possibility that sneak interference may occur in which a radio signal for access with the user apparatus interferes with a radio signal of a backhaul with the base station. Therefore, it is necessary to install the antenna for the backhaul between the base station and the antenna for the access between the user apparatus separately.

In order to solve the above problems, a radio communication relay apparatus according to an aspect of the present invention is a radio communication relay apparatus that relays radio communication between a base station and a mobile station in a mobile communication system, and is assigned to the mobile communication system. A first wireless communication unit that performs backhaul link wireless communication with a base station using a first frequency within a predetermined frequency band, and a second frequency different from the first frequency within the frequency band A second wireless communication unit that performs wireless communication of an access link with a mobile station located in the cell of the base station, and a backhaul link of the first frequency received by the first wireless communication unit A baseband processing unit that generates a radio signal of the access link of the second frequency by modulating the demodulated signal, and the first frequency received by the first wireless communication unit Transmission power (EPRE) and maximum physical per subcarrier in the radio signal of the access link of the second frequency transmitted by the second radio communication unit based on the received signal level of the radio signal of the backhaul link of A control unit that determines at least one of the number of resource blocks (maximum number of PRBs).
In the wireless communication relay device, the control unit transmits the second wireless communication unit when the received signal level of the backhaul link wireless signal of the first frequency is equal to or lower than a first threshold. The transmission power per subcarrier (EPRE) in the radio signal of the access link of the second frequency is set to zero, the reception signal level of the radio signal of the backhaul link of the first frequency is greater than the first threshold and If the threshold is smaller than 2, the transmission power (EPRE) per subcarrier in the radio signal of the access link of the second frequency transmitted by the second radio communication unit is proportional to the received signal level. When the received signal level of the backhaul link radio signal of the first frequency is equal to or higher than the second threshold, the second radio communication unit transmits the received signal level. Serial second transmission power per one subcarrier in the radio signal of the access link frequency (EPRE) may be determined to the maximum allowed.
In the wireless communication relay device, the control unit transmits the second wireless communication unit when the received signal level of the backhaul link wireless signal of the first frequency is equal to or lower than a first threshold value. The maximum physical resource block number (maximum number of PRBs) in the radio signal of the access link of the second frequency is set to zero, and the reception signal level of the radio signal of the backhaul link of the first frequency is larger than the first threshold value. If the threshold is smaller than the second threshold, the maximum physical resource block number (maximum number of PRBs) in the radio signal of the access link of the second frequency transmitted by the second radio communication unit is proportional to the received signal level. If the received signal level of the backhaul link radio signal of the first frequency is equal to or higher than the second threshold value, the second radio communication unit transmits the signal. Maximum physical resource blocks (the maximum PRB numbers) may be determined in the maximum allowed in the radio signal of the access link of said second frequency.
Further, in the wireless communication relay device, the control unit includes a transmission power (EPRE) per subcarrier and a maximum number of physical resource blocks in the access link radio signal based on a received signal level of the backhaul link radio signal. The determination of at least one of (maximum number of PRBs) may be performed periodically.
The wireless communication relay device includes a first individual device including the first wireless communication unit and a second individual device including the second wireless communication unit, the baseband processing unit and the The control unit may be included in each of the first individual device and the second individual device.
In the wireless communication relay device, the wireless communication relay device may be incorporated in a base station device of a small cell base station.
In the wireless communication relay device, the base station with which the first wireless communication unit performs backhaul link wireless communication may be a macro cell base station.

A wireless communication relay method according to another aspect of the present invention is a wireless communication relay method for relaying wireless communication between a base station and a mobile station in a mobile communication system, and is a predetermined communication assigned to the mobile communication system. Wireless communication of the backhaul link with the base station using the first frequency within the frequency band of the first frequency, demodulating the received radio signal of the backhaul link of the first frequency, and modulating the demodulated signal Generating a radio signal of an access link having a second frequency different from the first frequency in the frequency band, and based on the received signal level of the radio signal of the backhaul link having the received first frequency. The transmission power per subcarrier (EPRE) and the maximum number of physical resource blocks (maximum PRB) in the radio signal of the access link of the second frequency ) And a mobile station located in the cell of the base station based on the transmission power (EPRE) per subcarrier and the maximum number of physical resource blocks (maximum number of PRBs). And performing wireless communication at the second frequency of the generated access link.
In the wireless communication relay method, when the reception signal level of the radio signal of the backhaul link of the first frequency is equal to or lower than the first threshold value, per subcarrier in the radio signal of the access link of the second frequency When the transmission power (EPRE) is set to zero and the received signal level of the radio signal of the backhaul link of the first frequency is larger than the first threshold value and smaller than the second threshold value, The transmission power (EPRE) per subcarrier in the radio signal of the access link is determined in proportion to the received signal level, and the received signal level of the backhaul link radio signal of the first frequency is equal to or higher than a second threshold value. In this case, the permissible maximum transmission power (EPRE) per subcarrier in the radio signal of the access link of the second frequency It may be determined.
In the wireless communication relay method, when the reception signal level of the backhaul link radio signal of the first frequency is equal to or lower than the first threshold, the maximum physical resource in the radio signal of the access link of the second frequency When the number of blocks (maximum number of PRBs) is set to zero and the received signal level of the radio signal of the backhaul link of the first frequency is larger than the first threshold and smaller than the second threshold, the second A maximum physical resource block number (maximum number of PRBs) in the radio signal of the frequency access link is determined in proportion to the received signal level, and the received signal level of the radio signal of the backhaul link of the first frequency is the second If the threshold value is exceeded, the maximum number of physical resource blocks (maximum number of PRBs) in the radio signal of the access link of the second frequency is allowed. It may be determined to a large value.
In the wireless communication relay method, the transmission power per subcarrier (EPRE) and the maximum number of physical resource blocks (maximum number of PRBs) in the access link radio signal based on the received signal level of the backhaul link radio signal At least one of the determinations may be performed periodically. In the wireless communication relay method, the base station may be a macro cell base station.

  ADVANTAGE OF THE INVENTION According to this invention, the separation of the receiving antenna of a radio | wireless communication relay apparatus and a transmission antenna can be minimized while ensuring the throughput of the access link from a radio | wireless communication relay apparatus to a mobile station (UE).

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows schematic structure of the mobile communication system by which the base station and radio | wireless communication relay apparatus which concern on one Embodiment of this invention are arrange | positioned. The block diagram which shows an example of schematic structure of the radio | wireless communication relay apparatus which concerns on this embodiment. Explanatory drawing which shows an example of frequency f1, f2 and signal level of each of the BH link signal and AC link signal in the radio | wireless communication relay apparatus which concerns on this embodiment. Explanatory drawing which shows an example of the relationship between the distance from a macrocell base station, the received signal level of the BH link signal transmitted from a macrocell base station, and the received signal level of the AC link signal transmitted from a radio | wireless communication relay apparatus. (A), (b), and (c) are respectively a BH link signal and an AC link when a wireless communication relay apparatus is installed at positions separated by distances A, B, and C from the macro cell base station in FIG. Explanatory drawing which shows the relationship between a signal and an AC spurious signal. The graph which shows an example of the relationship between the received signal level (RSRP) of a BH link signal, and the transmission power (EPRE) per subcarrier in an AC link signal. Explanatory drawing which shows the other example of the relationship between the distance from a macrocell base station, the received signal level of the BH link signal transmitted from a macrocell base station, and the received signal level of the AC link signal transmitted from a radio | wireless communication relay apparatus. . (A), (b), and (c) are the BH link signal and the AC link when the wireless communication relay device is installed at positions separated from the macrocell base station in FIG. 7 by the distances A, B, and C, respectively. Explanatory drawing which shows the relationship between a signal and an AC spurious signal. The graph which shows an example of the relationship between the received signal level (RSRP) of a BH link signal, and the maximum number of PRBs in an AC link signal. Explanation showing still another example of the relationship among the distance from the macro cell base station, the reception signal level of the BH link signal transmitted from the macro cell base station, and the reception signal level of the AC link signal transmitted from the wireless communication relay device Figure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing a schematic configuration of a mobile communication system in which a base station and a wireless communication relay device according to an embodiment of the present invention are arranged. In FIG. 1, the mobile communication system according to the present embodiment is a communication system compliant with LTE specifications, and includes a macro cell base station 10 and a plurality of radio communication relay devices 20 in a macro cell 10A that is a radio communication area thereof. .

  In the example of FIG. 1, an access link area (hereinafter referred to as an “AC link area”) 20A that is a transmission area of the wireless communication relay device 20 is normally included inside the macro cell 10A, but is one of the AC link areas. The part may be outside the macro cell 10A.

  When the user apparatus (UE) 30 which is a mobile station is located in the macro cell 10A, the user apparatus (UE) 30 can perform radio communication for the telephone or data communication with the macro cell base station 10. Further, when the user apparatus 30 is located in the AC link area 20A, the user apparatus 30 can receive wireless communication for telephone or data communication from the macrocell base station 10 via the wireless communication relay apparatus 20. .

  In the following description, a wireless communication link between the wireless communication relay device 20 and the user device 30 is referred to as an access link (hereinafter referred to as “AC link”). Further, the macro cell 10A is appropriately referred to as a backhaul link area (hereinafter referred to as “BH link area”), and a radio communication link between the macro cell base station 10 and the radio communication relay device 20 is referred to as a backhaul link (hereinafter referred to as “BH link”). Called).

  The macro cell (BH link area) 10A is, in order from the side far from the macro cell base station 10, the first macro cell area 11A on the cell edge side where the received signal level (received electric field strength) is weak, and the second received signal level is medium. The macro cell area 12A is the third macro cell area 13A at the center of the cell edge where the received signal level is high. Therefore, the modulation and coding scheme (MCS) used for communication between the macro cell base station 10 and the user apparatus 30 is switched as follows, for example, so that communication can be reliably performed in each area. For example, 64QAM (Quadrature Amplitude Modulation) that provides high throughput is used in the first macrocell area 13A in the center, and 16QAM is used in the second macrocell area 12A. In the third macro cell area 11A at the cell edge, QPSK (Quarter Phase Shift Keying) whose throughput is significantly inferior to 64QAM is used.

  In the communication system according to the present embodiment, the radio communication relay device 20 is configured so that a high reception signal level (reception electric field strength) can be obtained even in the user device 30 located in the second macro cell area 12A or the first macro cell area 11A. Is arranged. The wireless communication relay device 20 establishes a BH link with the macro cell base station 10 and establishes an AC link with the user device 30. With the BH link and the AC link established in this way, the wireless communication relay device 20 calls the first frequency (hereinafter referred to as “BH side frequency”) of the BH link (downlink) signal received from the macrocell base station 10. ) F1 is frequency-converted to a different second frequency (hereinafter referred to as “AC side frequency”) f2, and a signal of AC side frequency f2 is amplified to a predetermined transmission power and transmitted to the user apparatus 30 (hereinafter referred to as “frequency”). "Conversion relay").

  The frequency conversion relay of the radio communication relay device 20 can increase the reception signal level of the downlink signal in the AC link area 20A out of the second macro cell area 12A and the first macro cell area 11A. Therefore, in the AC link area 20A, 16QAM or 64QAM can be used as a modulation and coding scheme, and a higher throughput than before performing frequency conversion relay can be obtained.

FIG. 2 is a block diagram illustrating an example of a schematic configuration of the wireless communication relay device 20 according to the present embodiment. The wireless communication relay device 20 includes a BH-side wireless communication unit 210 as a first wireless communication unit, an AC-side wireless communication unit 220 as a second wireless communication unit, a baseband processing unit 230, a control unit 240, Is provided.
The BH side radio communication unit 210 includes a reception antenna 210a, a radio signal amplifier, a reception processing unit, and the like, and communicates with the macro cell base station 10 by a BH side frequency f1 within a predetermined frequency band assigned to the mobile communication system. BH link wireless communication is performed. A plurality of (for example, two or four) receiving antennas 210a may be provided. A BH link radio signal (hereinafter referred to as “BH link signal”) 211 from the macro cell base station 10 is received by the reception antenna 210 a of the BH side radio communication unit 210.

  The AC-side radio communication unit 220 includes a radio signal transmission processing unit, an amplification unit, a transmission antenna 220a, and the like, and is a user located in the macro cell 10A with an AC-side frequency f2 different from the BH-side frequency f1 in the frequency band. AC link wireless communication with the device 30 is performed. A plurality of (for example, two or four) transmission antennas 220a may be provided. An AC link radio signal (hereinafter referred to as an “AC link signal”) 221 to the user apparatus 30 is transmitted from the transmission antenna 220 a of the AC side radio communication unit 220. When transmitting the AC link radio signal 221 to the user apparatus 30, a spurious signal 222 (hereinafter referred to as “AC spurious signal”) 222 of the AC link radio signal 221 is generated, as will be described later. There is a possibility that the AC spurious signal 222 may be received by wrapping around the reception antenna 210a side of the BH side wireless communication unit 210.

  The baseband processing unit 230 demodulates the BH link signal 211 having the BH side frequency f1 received by the first wireless communication unit 210, modulates the demodulated signal with a predetermined modulation encoding method, and generates the AC having the AC side frequency f2. Generate a link signal.

  The control unit 240 is composed of, for example, a computer having a CPU, a memory, and the like, and by reading and executing a predetermined control program, the BH-side wireless communication unit 210, the AC-side wireless communication unit 220, and the baseband processing unit 230. To control. Moreover, the control part 240 performs the process which determines the transmission parameter of the AC link signal of the AC side frequency f2 transmitted by the AC side radio | wireless communication part 220 based on the received signal level of a BH link signal so that it may mention later. For example, at least one of transmission power (EPRE) per subcarrier and maximum physical resource block number (maximum PRB number) is determined as the transmission parameter of the AC link signal.

  FIG. 3 is an explanatory diagram illustrating an example of frequencies f1 and f2 and signal levels of the BH link signal and the AC link signal transmitted and received by the wireless communication relay device 20 according to the present embodiment.

  In FIG. 3, the frequency band of the BH link and the AC link relayed by the wireless communication relay device 20 of the present embodiment has a width within the range of 100 MHz to 200 MHz of the GHz band allocated from the range of 1 GHz to 10 GHz, for example. It is a frequency band (for example, 160 MHz). Further, each of the BH side frequency f1 and the AC link side frequency f2 has a band of 15 MHz, for example, and is set so as not to overlap each other within the same frequency band. For example, the BH link signal 211 having the BH side frequency f1 is located on the low frequency side within the same frequency band, and the AC link signal 221 having the AC side frequency f2 is located on the high frequency side within the same frequency band.

  In the wireless communication relay device 20 having the above configuration, as described above, when the BH link signal 211 having the BH side frequency f1 and the AC link signal 221 having the AC side frequency f2 are close to each other within the same frequency band, the following is performed. May cause sneak interference. The wireless communication relay device 20 is installed in an area where the reception level of the BH link signal 211 is relatively weak, and the AC link signal 221 is amplified from the wireless communication relay device 20 and transmitted. Therefore, as shown in FIG. 3, there is a possibility that wraparound interference occurs in which the relatively strong and broadband spurious signal 222 of the AC link signal 221 wraps around the BH link signal 211 and interferes.

  Therefore, in the wireless communication relay device 20 of the present embodiment, the transmission parameter of the AC link signal 221 is determined based on the received signal level of the BH link signal 211 so as to suppress the sneak interference as described below. Is controlling. For example, based on the received signal level of the BH link signal 211, at least the transmission power (EPRE) per subcarrier and the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221 so as to suppress the sneak interference. One of them is controlled to determine.

  For example, reference signal received power (RSRP) is used as the received signal level of the BH link signal 211. Instead of the reference signal received power (RSRP), the received electric field strength of the BH link signal 211 or reference signal received quality (RSRQ) may be used. The reference signal received quality (RSRQ) is the ratio of RSRP to the total received power (RSSI: Received Signal Strength Indicator).

  The reception signal level of the BH link signal 211 may be measured by the wireless communication relay device 20 or acquired based on the reception report from the user device 30 located near the wireless communication relay device 20. Also good.

  4 shows the distance from the macro cell base station 10, the received signal level of the BH link signal 211 transmitted from the macro cell base station 10, and the received signal level of the AC link signal 221 transmitted from the wireless communication relay device 20. It is explanatory drawing which shows an example of a relationship. 5 (a), (b) and (c) respectively show the case where the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 in FIG. 4 by distances A, B and C. It is explanatory drawing which shows the relationship between the BH link signal 211, the AC link signal 221, and the AC spurious signal 222.

  In this example, control is performed so as to determine transmission power (EPRE) [dBm] per subcarrier in the AC link signal 221 based on the received signal level of the BH link signal 211.

  When the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 in FIG. 4 by a distance A, the received signal level (received electric field strength) of the BH link signal 211 as shown in FIG. ) Is relatively strong and sufficiently higher than the reception signal level of the AC spurious signal 222, and therefore, performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is unlikely to occur. Therefore, the transmission power (EPRE) [dBm] per subcarrier in the AC link signal 221 is set to a large value (for example, a preset allowable maximum value) so that high throughput can be obtained for the AC link signal 221. Yes.

  When the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 in FIG. 4 by a distance B, the received signal level (received electric field strength) of the BH link signal 211 as shown in FIG. ) Becomes weaker and approaches the reception signal level of the AC spurious signal 222, so that performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is likely to occur. Therefore, the transmission power per subcarrier (EPRE) [dBm] in the AC link signal 221 is set to a small value, and interference of the AC spurious signal 222 with respect to the BH link signal 211 is suppressed. As a result, the AC link signal 221 The throughput is secured.

  When the wireless communication relay device 20 is installed at the position of the cell edge away from the macro cell base station 10 in FIG. 4 by the distance C, the received signal level (reception) of the BH link signal 211 is received as shown in FIG. Electric field strength) is further weakened and is lower than the reception signal level of the AC spurious signal 222, and therefore, performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is more likely to occur. Therefore, the AC link signal 221 is stopped by setting the transmission power (EPRE) [dBm] per subcarrier in the AC link signal 221 to zero. In this case, the wireless communication relay device 20 may output an alarm to notify that the AC link signal 221 has stopped.

FIG. 6 is a graph showing an example of the relationship between the reception signal level (RSRP) of the BH link signal and the transmission power (EPRE) per subcarrier in the AC link signal in the wireless communication relay device 20 of the present embodiment.
In FIG. 6, when the received signal level of the BH link signal is in a range (range (c) in the figure) that is equal to or less than the first threshold (RSRP1), transmission power (EPRE) per subcarrier in the AC link signal Is set to zero, and the AC link signal is stopped.

  In FIG. 6, when the received signal level of the BH link signal is in a range that is higher than the first threshold value (RSRP1) and smaller than the second threshold value (RSRP2) (range (b) in the figure), the AC link The transmission power per subcarrier (EPRE) [dBm] in the signal is determined to be proportional to the reception signal level of the BH link signal. Thus, by determining the EPRE [dBm] of the AC link signal according to the reception signal level of the BH link signal, it is possible to prevent the transmission level of the AC link signal from being suppressed more than necessary.

  In FIG. 6, when the received signal level of the BH link signal is in a range (range (a) in the figure) that is equal to or higher than the second threshold (RSRP2), transmission power (EPRE) per subcarrier in the AC link signal [DBm] is determined as an allowable maximum value.

  As described above, as illustrated in FIGS. 4 to 6, by appropriately determining the transmission power (EPRE) [dBm] per subcarrier in the AC link signal 221 based on the reception signal level of the BH link signal 211. The separation between the reception antenna 210a and the transmission antenna 220a of the wireless communication relay device 20 can be minimized while ensuring the throughput of the AC link signal.

  7 shows the distance from the macro cell base station 10, the received signal level of the BH link signal 211 transmitted from the macro cell base station 10, and the received signal level of the AC link signal 221 transmitted from the wireless communication relay device 20. It is explanatory drawing which shows the other example of a relationship. FIGS. 8A, 8B, and 8C show the case where the wireless communication relay device 20 is installed at a distance from the macrocell base station 10 in FIG. 7 by distances A, B, and C, respectively. It is explanatory drawing which shows the relationship between the BH link signal 211, the AC link signal 221, and the AC spurious signal 222.

  In this example, control is performed so as to determine the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221 based on the reception signal level of the BH link signal 211.

  When the wireless communication relay device 20 is installed at a position away from the macro cell base station 10 in FIG. 7 by a distance A, the received signal level (received electric field strength) of the BH link signal 211 as shown in FIG. ) Is relatively strong and sufficiently higher than the reception signal level of the AC spurious signal 222, and therefore, performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is unlikely to occur. Therefore, the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221 is set to a larger value (for example, a preset allowable maximum value: 100 in the illustrated example), and a high throughput is obtained for the AC link signal 221. I am trying to do it.

  When the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 in FIG. 7 by a distance B, the received signal level (received electric field strength) of the BH link signal 211 as shown in FIG. ) Becomes weaker and approaches the reception signal level of the AC spurious signal 222, so that performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is likely to occur. Therefore, as shown in FIG. 8B, the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221 is set to a smaller value (20 in the illustrated example), and the AC spurious signal 222 corresponding to the BH link signal 211 is changed. As a result, the throughput of the AC link signal 221 can be secured.

  When the wireless communication relay device 20 is installed at a cell edge position away from the macrocell base station 10 in FIG. 7 by a distance C, the received signal level (reception) of the BH link signal 211 is received as shown in FIG. Electric field strength) is further weakened and is lower than the reception signal level of the AC spurious signal 222, and therefore, performance degradation due to interference of the AC spurious signal 222 with respect to the BH link signal 211 is more likely to occur. For this reason, the AC link signal 221 is stopped by setting the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221 to zero. In this case, the wireless communication relay device 20 may output an alarm to notify that the AC link signal 221 has stopped.

FIG. 9 is a graph showing an example of the relationship between the reception signal level (RSRP) of the BH link signal and the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal in the wireless communication relay device 20 of the present embodiment.
In FIG. 9, when the received signal level of the BH link signal is in the range (the range (c) in the figure) that is equal to or less than the first threshold value (RSRP1), the maximum PRB number in the AC link signal is set to zero, Stop.

  In FIG. 9, when the received signal level of the BH link signal is larger than the first threshold (RSRP1) and smaller than the second threshold (RSRP2) (range (b) in the figure), the AC link The maximum number of PRBs in the signal is determined to be proportional to the received signal level of the BH link signal. Thus, by determining the maximum PRB number of the AC link signal according to the reception signal level of the BH link signal, it is possible to prevent the transmission level of the AC link signal from being suppressed more than necessary.

  In FIG. 9, when the received signal level of the BH link signal is in a range equal to or higher than the second threshold (RSRP2) (range (a) in the figure), the maximum number of PRBs in the AC link signal is determined as the allowable maximum value. .

  As described above, as shown in FIGS. 7 to 9, while appropriately determining the maximum number of PRBs in the AC link signal 221 based on the reception signal level of the BH link signal 211, while ensuring the throughput of the AC link signal. The separation between the reception antenna 210a and the transmission antenna 220a of the wireless communication relay device 20 can be minimized.

  Note that the adjustment example of the transmission parameter of the AC link signal described with reference to FIGS. 4 to 6 may be combined with the adjustment example of the transmission parameter of the AC link signal described with reference to FIGS.

  10 shows the distance from the macro cell base station 10, the received signal level of the BH link signal 211 transmitted from the macro cell base station 10, and the received signal level of the AC link signal 221 transmitted from the wireless communication relay device 20. It is explanatory drawing which shows the further another example of a relationship.

  In this example, based on the received signal level of the BH link signal 211, control is performed so as to determine both the transmission power (EPRE) per subcarrier and the maximum number of physical resource blocks (maximum number of PRBs) in the AC link signal 221. doing.

  In FIG. 10, when the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 by a distance A, the EPRE and the maximum PRB in the AC link signal 221 are based on the received signal level of the BH link signal 211. Both numbers are set to a larger value (for example, a preset allowable maximum value). Thereby, a high throughput is obtained for the AC link signal 221.

  In addition, in FIG. 10, when the wireless communication relay device 20 is installed at a position away from the macrocell base station 10 by the distance B, the EPRE in the AC link signal 221 is set based on the received signal level of the BH link signal 211. The maximum PRB number is set to a small value (20 in the illustrated example) as well as a small value. Thereby, the interference of the AC spurious signal 222 with respect to the BH link signal 211 is suppressed, and as a result, the throughput of the AC link signal 221 can be ensured.

  In addition, in FIG. 10, when the wireless communication relay device 20 is installed at a cell edge position away from the macro cell base station 10 by a distance C, the AC link signal 221 has a level based on the received signal level of the BH link signal 211. The AC link signal 221 is stopped by setting at least one of the EPRE and the maximum PRB number to zero.

  In the example of FIG. 10, when the reception signal level of the BH link signal is larger than the first threshold (RSRP1) and smaller than the second threshold (RSRP2), the EPRE and the maximum number of PRBs in the AC link signal are set as follows. You may determine so that it may be proportional to the received signal level of a BH link signal.

  In each of the above embodiments, the process of determining at least one of the EPRE and the maximum PRB number in the AC link signal based on the reception signal level of the BH link signal may be executed periodically (for example, once a day). .

  Moreover, although each said embodiment demonstrated the case where the radio | wireless communication relay apparatus 20 was installed in the macrocell 10A, this invention is applicable also when the radio | wireless communication relay apparatus 20 is installed in other cells other than the macrocell 10A. The same can be applied.

  It is noted that the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. The present disclosure is therefore not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

10 Macrocell base station 10A Macrocell (BH link area)
20 Wireless communication relay device 20A AC link area 30 User device (mobile station)
210 BH side radio communication unit 210a reception antenna 211 BH link signal 220 AC side radio communication unit 220a transmission antenna 221 AC link signal 222 AC spurious signal 230 baseband processing unit 240 control unit

3GPP TS36.300

Claims (8)

A wireless communication relay device that relays wireless communication between a base station and a mobile station in a mobile communication system,
A first radio communication unit that performs radio communication of a backhaul link with a base station using a first frequency within a predetermined frequency band assigned to the mobile communication system;
A second radio communication unit that performs radio communication of an access link with a mobile station located in a cell of the base station by a second frequency different from the first frequency in the frequency band;
Baseband processing for demodulating the backhaul link radio signal of the first frequency received by the first radio communication unit and modulating the demodulated signal to generate a radio signal of the access link of the second frequency And
Based on the received signal level of the radio signal of the backhaul link of the first frequency received by the first radio communication unit, the radio of the access link of the second frequency transmitted by the second radio communication unit And a controller that determines at least one of transmission power (EPRE) per subcarrier and maximum physical resource block number (maximum PRB number) in the signal. The wireless communication relay device according to claim 1,
The controller is
When the reception signal level of the radio signal of the backhaul link of the first frequency is equal to or lower than the first threshold value, one sub in the radio signal of the access link of the second frequency transmitted by the second radio communication unit Zero transmission power per carrier (EPRE)
When the received signal level of the radio signal of the backhaul link of the first frequency is larger than the first threshold and smaller than the second threshold, the second frequency transmitted by the second radio communication unit Determining the transmission power per subcarrier (EPRE) in the radio signal of the access link in proportion to the received signal level;
When the reception signal level of the radio signal of the backhaul link of the first frequency is equal to or higher than the second threshold value, one sub in the radio signal of the access link of the second frequency transmitted by the second radio communication unit A wireless communication relay device, wherein transmission power per carrier (EPRE) is determined as an allowable maximum value. In the wireless communication relay device according to claim 1 or 2,
The controller is
When the reception signal level of the radio signal of the backhaul link of the first frequency is less than or equal to the first threshold, the maximum physical in the radio signal of the access link of the second frequency transmitted by the second radio communication unit Set the number of resource blocks (maximum number of PRBs) to zero,
When the received signal level of the radio signal of the backhaul link of the first frequency is larger than the first threshold and smaller than the second threshold, the second frequency transmitted by the second radio communication unit Determining the maximum number of physical resource blocks (maximum number of PRBs) in the radio signal of the access link in proportion to the received signal level;
When the reception signal level of the radio signal of the backhaul link of the first frequency is equal to or higher than the second threshold, the maximum physical in the radio signal of the access link of the second frequency transmitted by the second radio communication unit A wireless communication relay device, wherein the number of resource blocks (maximum number of PRBs) is determined as an allowable maximum value. In the wireless communication relay device according to any one of claims 1 to 3,
The control unit includes at least one of transmission power (EPRE) per subcarrier and maximum physical resource block number (maximum PRB number) in the access link radio signal based on a reception signal level of the backhaul link radio signal. A wireless communication relay device, wherein the determination is periodically performed. In the wireless communication relay device according to any one of claims 1 to 4,
A first individual device including the first wireless communication unit, and a second individual device including the second wireless communication unit,
The baseband processing unit and the control unit are included in the first individual device or the second individual device, respectively. In the wireless communication relay device according to any one of claims 1 to 5,
The wireless communication relay device is incorporated in a base station device of a small cell base station. In the wireless communication relay device according to any one of claims 1 to 6,
A radio communication relay device, wherein the base station with which the first radio communication unit performs backhaul link radio communication is a macro cell base station. A wireless communication relay method for relaying wireless communication between a base station and a mobile station in a mobile communication system,
Performing wireless communication of a backhaul link with a base station using a first frequency within a predetermined frequency band assigned to the mobile communication system;
Demodulate the received backhaul link radio signal of the first frequency, and modulate the demodulated signal to generate an access link radio signal of a second frequency different from the first frequency in the frequency band To do
Based on the received signal level of the received radio signal of the backhaul link of the first frequency, the transmission power (EPRE) per subcarrier and the maximum number of physical resource blocks in the radio signal of the access link of the second frequency Determining at least one of (maximum number of PRBs);
Based on the transmission power per one sub-carrier (EPRE) and the maximum number of physical resource blocks (maximum number of PRBs), the generated access link of the generated access link with the mobile station located in the cell of the base station. Performing wireless communication at a frequency of 2, including a wireless communication relay method.

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