JP4098321B2 - Wireless relay device - Google Patents

Description

  The present invention relates to a radio relay apparatus that controls the gain of a signal transmitted and received between a base station and a mobile station.

Conventionally, in a wireless communication system, there has been a wireless relay device that automatically measures gain by measuring a propagation loss (propagation loss) between a base station and a wireless relay device (booster) (for example, a patent) References 1 and 2). In such a radio relay apparatus, the peripheral base station existing around the base station is recognized based on the peripheral base station information transmitted from the base station, and the minimum propagation loss among the propagation losses of these base stations is recognized. The gain was controlled based on. Originally, the purpose of gain control is to suppress the influence of noise on the base station by allowing the base station to receive the noise power transmitted from the radio relay apparatus as low as possible.
JP 2001-69091 A (paragraph 0085) JP2003-188808 (paragraph 0065)

  In Patent Documents 1 and 2, it is not particularly specified to re-read neighboring base station information. However, if the neighboring base station information is not re-read, the neighboring base station information read in the past may not include the information on the base station that has the new minimum propagation loss. Measurement leak of the target base station occurs. As a result, the radio relay apparatus sets the gain without knowing the base station that causes the minimum propagation loss, which causes a problem that the accuracy of gain control is reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radio relay apparatus capable of improving the accuracy of gain control.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a wireless relay apparatus for controlling gain, a neighboring base station information reading means for reading neighboring base station information transmitted from a base station, the own apparatus, Propagation loss measuring means for measuring the propagation loss with the base station included in the neighboring base station information read by the neighboring base station information reading means, and the smallest propagation loss among the propagation losses measured by the propagation loss measuring means Gain control means for controlling the gain based on the base station information reading means, the peripheral base station information reading means, when the base station that minimizes the propagation loss has changed, the peripheral of the base station that has newly minimized the propagation loss Provided is a wireless relay device that reads base station information.

According to the present invention, when the base station that minimizes the propagation loss changes, the accuracy of identifying the base station having the smallest propagation loss by reading the neighboring base station information of the base station that newly has the smallest propagation loss. It is possible to improve the accuracy of the gain control.
According to a second aspect of the present invention, in the wireless relay device according to the first aspect, the neighboring base station information reading means newly has a minimum propagation loss when the change continues for a predetermined threshold value or more. The peripheral base station information transmitted from the base station is read out.

  According to the present invention, when the change of the base station that minimizes the propagation loss continues for a predetermined threshold value or more, the neighboring base station information that is newly transmitted from the base station that has the smallest propagation loss is read. By appropriately adjusting the frequency of reading the neighboring base station information, it is possible to prevent the propagation loss measurement from taking a sufficient time. Therefore, it is possible to prevent the gain update frequency from being lowered, and to improve the accuracy of gain control.

According to a third aspect of the present invention, in the wireless relay device of the second aspect, the predetermined threshold value used as a condition for reading the neighboring base station information transmitted from the base station whose propagation loss is newly minimized. The threshold determination means further includes a threshold determination means for determining the predetermined threshold so that the predetermined threshold becomes a relatively small value as the height of the antenna for the base station provided in the apparatus increases. It is characterized by determining.
According to the present invention, the propagation loss measurement time is secured by adjusting the predetermined threshold so that the frequency of reading the neighboring base station information does not become too high according to the antenna height that affects the fluctuation width of the propagation loss. However, it is possible to increase the update frequency of gain control.

According to a fourth aspect of the present invention, in the wireless relay device according to any one of the first to third aspects, the neighboring base station information reading means reads neighboring base station information every time indicated by a timer value. It is characterized by that.
According to this configuration, since the neighboring base station information is read every time indicated by the timer value, when the base station with the minimum propagation loss changes, the base station with the smallest propagation loss is determined by the newly read neighboring base station information. It becomes possible to recognize.

  According to the present invention, when the base station with the smallest propagation loss changes, the radio relay apparatus reads the base station information of the base station with the smallest propagation loss newly, thereby reading the base station with the smallest propagation loss. It is possible to improve the accuracy of specifying a station and increase the accuracy of gain control.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment of the present invention. The mobile communication system is transmitted / received between a mobile station 30 such as a mobile phone or a PHS (Personal Handyphone System), a base station 20 that relays wireless communication of the mobile station 30, and between the mobile station 30 and the base station 20. It is comprised with the radio relay apparatus 10 which amplifies a radio signal.

  The radio signal transmitted from the base station 20 includes broadcast information (BCH), and the broadcast information includes information on the base station 20 and base stations (neighboring base stations) existing around the base station 20 ( "Nearby base station information") is included below. The neighboring base station information includes the number of neighboring base stations, the identifier of each neighboring base station (scrambling code when the communication method is CDMA (Code Division Multiple Access), and FDMA (Frequency Division Multiple Access). Frequency), transmission power, reception timing, and the like.

The radio relay apparatus 10 according to the present embodiment includes a first antenna A1 that is an antenna for base stations, a second antenna A2 that is an antenna for mobile stations, a first variable gain amplifier 11, A second variable gain amplifier 12, a receiver 13, and a control unit 14 are provided.
The first antenna A1 outputs the signal received from the base station 20 to the receiver 13 and the second variable gain amplifier 12, and transmits the signal output from the first variable gain amplifier 11 to the base station 20. To do.

The second antenna A <b> 2 outputs the signal received from the mobile station 30 to the first variable gain amplifier 11 and transmits the signal output from the second variable gain amplifier 12 to the mobile station 30.
The receiver 13 measures the reception voltage (reception level) of the signal transmitted from the base station 20 based on the output signal from the first antenna A1, and sends information about the measured reception voltage to the control unit 14. Output.

The control unit 14 includes a memory such as a RAM and a ROM, a CPU that executes processing according to a program stored in the memory, and an internal clock that measures time. When the CPU executes processing according to the program, the functions shown in FIG.
The neighboring base station information reading unit 141 reads neighboring base station information from the signal transmitted from the base station 20. Here, the conditions and timing for the neighboring base station information reading unit 141 to read the neighboring base station information include the following.

(1) When the radio relay apparatus 10 is turned on, the base station information transmitted by the base station with the maximum received power is read.
(2) When the base station with the minimum propagation loss changes, the neighboring base station information transmitted by the base station with the new minimum propagation loss is read.
Although it is possible to read the neighboring base station information immediately when the base station with the minimum propagation loss changes, in this embodiment, the minimum propagation loss is reduced so that the frequency of reading the neighboring base station information does not increase. When the base station change continues for a predetermined threshold or more, the neighboring base station information transmitted by the base station with the minimum propagation loss is read. Note that the predetermined threshold may be time or the number of times the base station with the minimum propagation loss has been determined.

(3) Read the neighboring base station information again after the timer value counted by the base station information clear timer has elapsed after reading the neighboring base station information. As described above, by periodically reading out the neighboring base station information every time indicated by the timer value, it is possible to prevent a recognition failure that the base station having the minimum propagation loss has changed.

  The propagation loss measuring unit 142 measures the propagation loss between each base station included in the neighboring base station information read by the neighboring base station information reading unit 141 and the own device 10. Specifically, the propagation loss measurement unit 142 reads the transmission power of the base station from the neighboring base station information, and acquires the reception voltage of the base station measured by the receiver 13 from the receiver 13. Then, the difference between the transmission power and the reception power is calculated as the propagation loss of the base station.

  The gain control unit 143 controls the gain based on the minimum propagation loss among the base station propagation losses measured by the propagation loss measurement unit 142. Specifically, the gain control unit 143 calculates an optimum gain based on the minimum propagation loss, and sets the calculated gain in the first variable gain amplifier 11 and the second variable gain amplifier 12.

  The threshold value determination unit 144 determines a predetermined threshold value so that the reading frequency of the neighboring base station information is optimized. For example, depending on the propagation state between the base station 20 and the radio relay apparatus 10, the propagation loss between the base station 20 and the radio relay apparatus 10 can be large or small. For example, when the antenna height for the base station of the radio relay apparatus 10 is low, the fluctuation width of the propagation loss becomes large due to the influence of surrounding reflectors and the like. On the other hand, when the height of the antenna for the base station is high, the fluctuation width of the propagation loss is small because it is close to line-of-sight propagation. For this reason, the threshold value determining unit 144 adjusts the predetermined threshold value to be large when the fluctuation width of the propagation loss is large and to decrease the predetermined threshold value when the fluctuation width is small. Can be read at an optimum frequency.

The first variable gain amplifier 11 amplifies the signal according to the gain set by the control unit 14 and outputs it from the first antenna A1.
The second variable gain amplifier 12 amplifies the signal according to the gain set by the control unit 14 and outputs the amplified signal from the second antenna A2.

Next, an operation example of the radio relay apparatus 10 according to the present embodiment will be described. The operation of the wireless relay device 10 can be broadly classified into an initial state operation immediately after the power is supplied to the wireless relay device 10 and a steady state operation.
(initial state)
FIG. 3 shows an operation flow in the initial state. First, when the power is turned on, the wireless relay device 10 performs a cell search (step S101). The neighboring base station information reading unit 141 reads neighboring base station information transmitted by the base station with the maximum received power (step S102), and is a list of neighboring base stations existing around the base station with the largest received power. A cell list is created (step S103). Next, a cell search for undetected cells in the neighboring cell list is performed (step S104).

  The receiver 13 measures the reception level of the detected cell (detected neighboring base station), and the propagation loss measuring unit 142 calculates the propagation loss between the neighboring base station and the radio relay apparatus 10 (step S105). Is determined to be the smallest cell (base station) (step S106).

  Next, it is determined whether or not the cell with the smallest propagation loss is the cell from which the neighboring base station information is read in step S102 (step S107). If the cell with the smallest propagation loss is not the information readout cell (step S107: No), the cell with the smallest propagation loss is set as the information readout cell (step S108), and the processing from step S102 is repeated.

On the other hand, when the cell with the smallest propagation loss is the information read cell (step S107: Yes), the gain control unit 143 sets the gain based on the minimum propagation loss (step S109).
(steady state)
Next, the operation of the wireless relay device 10 in a steady state will be described with reference to the operation flow shown in FIG. It is assumed that the wireless relay device 10 is set in advance with a timer value of the base station information clear timer and a predetermined threshold value to be compared with the cell change counter.

  First, the radio relay apparatus 10 performs a cell search for undetected cells in the neighboring cell list (step S201). Next, the reception level of the signal transmitted from the detection cell is measured (step S202), and the propagation loss is calculated (step S203). Then, the neighboring base stations included in the neighboring cell list are rearranged in the order of propagation loss (step S204), and the gain is set based on the minimum propagation loss (step S205).

Next, it is determined whether or not the timer value of the base station information clear timer has elapsed (step S206). If it is determined that the time indicated by the timer value has elapsed, the process returns to the initial state (step S101 in FIG. 3) (step S206: Yes, step S214).
On the other hand, when it is determined that the time indicated by the timer value has not elapsed (step S206: No), the radio relay apparatus 10 determines whether or not the minimum propagation loss cell is an information read cell (step S206). S207). If the minimum propagation loss cell is an information read cell (step S207: Yes), the minimum propagation loss cell has not changed, and the process returns to step S201 to perform cell search for undetected cells in the neighboring cell list. Repeat the process.

  On the other hand, when the propagation loss minimum cell is not the information read cell (step S207: Yes), the cell propagation counter is incremented because the propagation loss minimum cell has changed (step S208). Next, it is determined whether or not the cell change counter has reached a predetermined threshold value. When the predetermined threshold value has not been reached (step S208: No), the process returns to step S201, and an undetected cell in the neighboring cell list. Repeat the cell search process.

On the other hand, when the cell change counter reaches a predetermined threshold (step S209: Yes), the cell change counter is reset (step S210), and the minimum propagation loss cell is set as an information read cell (step S211).
Then, the neighboring base station information transmitted from the cell set as the information reading cell is read (step S212), and a neighboring cell list is created based on the read neighboring base station information (step S213), and after step S201 Repeat the process.

  As described above, in the steady state, the radio relay apparatus 10 measures the propagation loss with the neighboring base stations, and when the change of the propagation loss minimum cell continues up to the predetermined threshold, the propagation loss is newly minimized. Reread the neighboring base station information from the selected cell. Regardless of whether or not there is a change in the minimum propagation loss cell, the neighboring base station information list is cleared after the timer value of the base station information clear timer has elapsed, and the neighboring base station information is reread.

  FIG. 5 is a graph showing the measurement result of the propagation loss of the base station over time. The relationship between the propagation loss measurement result and the neighboring base station information readout will be described with reference to FIG. Here, it is assumed that base station A corresponds to cell A and base station B corresponds to cell B. Further, it is assumed that the predetermined threshold is T seconds (S). The gain of the wireless relay device 10 is controlled by the value of the minimum propagation loss indicated by the dotted line graph in FIG.

  As shown in the graph, the base station with the minimum propagation loss changes from the base station A to the base station B between the time A and the time B, but the base station B continues to be the base station with the minimum propagation loss. The wireless relay device 10 does not read out the neighboring base station information of the base station B because the waiting time is less than the threshold T seconds.

  On the other hand, during T seconds from time C to time D, since the base station B continues to be the base station with the minimum propagation loss, the radio relay apparatus 10 reads the peripheral base station information of the base station B. That is, at time D, the BCH read target cell changes from cell A to cell B. As described above, the frequency of reading the neighboring base station information can be reduced by reading the neighboring base station information only when the change of the base station having the minimum propagation loss continues for the threshold T seconds or more.

  FIG. 6 shows an arrangement example of base stations. There is a limit to the number of base stations included in the peripheral base station information. Since the base station B and the base station C are adjacent to each other, there is a high rate that the information on the base station C is included in the peripheral base station information of the base station B, but the base station A and the base station C are not adjacent to each other. Therefore, the rate at which the base station C information is included in the base station A peripheral base station information is low. In such a state, a case where the wireless relay device 10 is installed at a position as shown in FIG. 6 will be examined with reference to FIG. Note that the propagation loss between the radio relay apparatus 10 and the base station A is La, the propagation loss between the base stations B is Lb, the propagation loss between the base stations C is Lc, and the relationship is La> Lb> Lc. In the radio relay apparatus 10, the received power of the base station A is Pra, the received power of the base station B is Prb, the received power of the base station C is Prc, and these relations are Prc> Pra> Prb. Further, it is assumed that the base station C is not initially installed.

  When the power of the wireless relay device 10 is turned on, the wireless relay device 10 measures the propagation loss with the base station A having the maximum received power, reads the neighboring base station information of the base station A, and determines the base from the neighboring base station information. As station B information, a scrambling code in the case of CDMA, a frequency, and transmission power in the case of FDMA are listed. If the neighboring base station information is not read, in order to measure the propagation loss with the base station B, the base station B must start by searching for the scrambling code used by the base station B. The more it takes, the longer it takes to measure.

Before the base station C is installed, the base station C information is not included in the base station A and B peripheral base station information. However, as described above, the peripheral base station information read timing is defined. By periodically reading the neighboring base station information of the base station B with the smallest propagation loss, the new establishment of the base station C can be recognized.
In this way, even when the base station C having the minimum propagation loss is newly installed near the radio relay apparatus 10, the gain of the radio relay apparatus 10 is lowered so as to correspond to the base station C, and The influence of noise and interference can be reduced.

  As described above, when there is a change in the base station having the smallest propagation loss, the neighboring base station information is read, and the propagation loss between the base station included in the neighboring base station information and the radio relay apparatus 10 is read. Therefore, the accuracy of specifying the base station with the smallest propagation loss can be improved, and the accuracy of gain control can be improved. In addition, by adjusting the frequency of reading out neighboring base station information, it is possible to allocate time as much as possible to measure the propagation loss necessary for gain control, increase the frequency of gain control update, and increase the accuracy of gain control. Can do.

In addition, by re-reading the neighboring base station information periodically by setting a timer value, it is possible to prevent a recognition leak when there is a change in the base station with the minimum propagation loss and to reliably identify the base station with the minimum propagation loss. be able to.
Note that the timing and conditions for the wireless relay device 10 to read out the neighboring base station information are not limited to the above-described embodiment. For example, the neighboring station information included in the broadcast information transmitted from the base station 20 is changed. If the information (change information) indicating whether or not the content of the neighboring base station information is changed is read, the neighboring base station information may be read.

  Further, the gain control may be performed for one of the upstream signal amplification and the upstream signal amplification. When both are performed, the upstream signal amplification gain and the downstream signal amplification gain are different. May be.

  This can be used for appropriate control of gain in the wireless relay device.

It is a figure which shows the structure of the mobile communication system which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the control part of the radio relay apparatus concerning the embodiment. It is a figure which shows the operation | movement flow of the radio relay apparatus in the initial state which concerns on the same embodiment. It is a figure which shows the operation | movement flow of the radio relay apparatus in the steady state which concerns on the same embodiment. It is a graph which shows the measurement result of the propagation loss of the base station by progress of time concerning the embodiment. It is a figure which shows the example of arrangement | positioning of the base station which concerns on the same embodiment. It is a figure for demonstrating the propagation loss with each base station of the radio relay apparatus concerning the same embodiment, received power, and neighboring base station information.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio relay apparatus A1 1st antenna A2 2nd antenna 11 1st gain variable amplifier 12 2nd gain variable amplifier 13 Receiver 14 Control part 20 Base station 30 Mobile station 141 Peripheral base station information reading part 142 Propagation loss Measurement unit 143 Gain control unit 144 Threshold value determination unit

Claims (4)

In the wireless relay device for controlling the gain,
Neighboring base station information reading means for reading neighboring base station information transmitted from the base station;
Propagation loss measuring means for measuring the propagation loss between the own apparatus and the base station included in the peripheral base station information read by the peripheral base station information reading means;
Gain control means for controlling the gain based on the minimum propagation loss among the propagation losses measured by the propagation loss measuring means,
The neighboring base station information reading means includes
A radio relay apparatus, which reads out neighboring base station information of a base station whose propagation loss is minimized when a base station whose propagation loss is minimized changes. The neighboring base station information reading means includes
The radio relay apparatus according to claim 1, wherein when the change continues for a predetermined threshold value or more, neighboring base station information transmitted from a base station whose propagation loss is newly minimized is read. A threshold value determining means for determining the predetermined threshold value used as a condition for reading out the neighboring base station information transmitted from the base station having the newly minimized propagation loss ;
The threshold value determining means includes
The wireless relay according to claim 2 , wherein the predetermined threshold is determined so that the predetermined threshold becomes a relatively small value as the antenna height for the base station provided in the own apparatus becomes higher. apparatus. The neighboring base station information reading means includes
The wireless relay device according to any one of claims 1 to 3, wherein neighboring base station information is read every time indicated by a timer value.

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