MXPA00007166A - Base station and method of transmission power control - Google Patents

Abstract

A radio network controller sends the stations for diversity handover the same value indicating the target quality for transmission power control at the same time. As a result, position finding can be correctly performed during diversity handover, and interferences with other base stations can be decreased. Transmission power is controlled such that the target quality is high for emergent services whereas it is not high for less emergent and less accurate services. Therefore, location finding is performed properly depending on required accuracy while reducing interferences with other base stations.

Description

BASE STATION DEVICE AND TRANSMISSION POWER CONTROL METHOD Technical Field The present invention relates to a base station apparatus having a function of detecting the position of a terminal apparatus in the communication and its method of controlling the transmission power.

Background of the Technique A method for detecting the position of a terminal apparatus in communication with a base station apparatus in a CDMA-based radio communication system is described in "Requirements and Objectives for the 3G Mobile System and Services (ARIB) 1998.7.21" ( "Requirements and Objectives for 3G Mobile Services and System (ARIB) 1998.7.21)", etc. Figure 1 is a diagram showing a radio communication system including a base station apparatus having a function of position detection. When the apparatus of the base station 1 detects the position of the terminal apparatus 2 which is carrying out radio communication, the apparatus of the base station 1 detects the angle of the address? of the terminal apparatus 2, the angle between the arrival direction of a reception signal and the base station takes advantage of the antenna characteristics of the network. This method for detecting the address of the terminal apparatus is described in the "Introductory Course for Adaptive Signal Processing Technology Utilizing the High Resolution Arrival Wave Estimation and the Directional Antenna" ("Introductory Course for Adaptive Signal Processing Technology"). Using Array Antenna and High Resolution Arriving bird Estimation "), etc. After detecting the steering angle? of the terminal apparatus 2 formed with the station itself, the apparatus of the base station 1 measures the distance between the station itself and the terminal apparatus 2. The method of measuring the distance L between the apparatus of the base station 1 and the terminal apparatus 2 will be explained later using the slot synchronization chart or graph in Figure 2. The propagation delay t for a downlink signal sent from the apparatus of the base station 1 to the terminal apparatus 2 is taken. similarly, the propagation delay t is taken for an uplink signal sent from the terminal apparatus 2 to arrive at the apparatus of the base station 1. Further, the delay of the apparatus d is taken after the terminal apparatus 2 complements the reception of the downlink signal until it starts to send the uplink signal. This delay of the device d is generated due to the delays in the processing of the components of the apparatus and the fluctuation of the timing, etc. As shown in Figure 2, the length of the slot S and the delay of the apparatus d are known to the apparatus of the base station 1, and therefore measuring the measurement time T after the base station apparatus 1 begins to transmit the downlink signal to the terminal apparatus 2 until the apparatus of the base station 1 starts to receive the uplink signal sent from the terminal apparatus 2, it is possible to calculate the delay of the propagation ta from the expression (1) that is given immediately: t = (T-S-d) / 2 (1).

Then, the apparatus of the base station 1 can calculate the distance L between the station itself and the terminal apparatus 2 of the later expression (2), where C is the speed of light: L = t X C (2) Here, in an environment of multiple paths or trajectories, there is not only a direct wave, which arrives directly from the transmission side on the receiving side but also a delay wave, which arrives after being reflected by the mountains and the buildings, etc. In general, a communication system with high resolution with respect to a delay wave such as a CDMA system carries out a combination of RAKE that combines the reception signals of the direct and delayed waves arriving at different times to improve its quality of reception. further, the CDMA system effects the control of the power of the transmission on the power level of the reception signal to reduce the interference with other stations while maintaining its desired reception quality. In a radio communication system, when a terminal apparatus moves away from a base station apparatus, with which it is communicating, the terminal apparatus performs the delivery processing to enter into communication with another adjacent base station apparatus. This delivery processing includes the diversity delivery processing by which a terminal apparatus communicates with a plurality of base station apparatus (the base station apparatus A and the base station apparatus B) simultaneously. During this delivery of diversity or differential reception, a radio network control apparatus combines the reception signals from a plurality of base station apparatus and sends the combined signal to a switchboard. During the delivery of diversity or differential reception, any of the devices of the base station performs control of the transmission power to satisfy the quality of the reception. Therefore, if any of these devices of the base station has good reception quality, this apparatus of the base station sends to a terminal apparatus a command to reduce its transmission power to reduce the interference in the system and the terminal apparatus follows the instruction of the command. For example, even if the apparatus of the base station A sends to the terminal apparatus a command to increase the transmission power, if the apparatus of the base station B sends to the terminal apparatus a command to reduce the power of the transmission, the terminal apparatus reduces the power of the transmission. Here, although the apparatus of the base station A is carrying out the detection of the previous position, if the terminal apparatus reduces its transmission power according to the instruction of the base station apparatus B, the reception power in the apparatus of the base station A is reduced and the operation of the position detection is impaired. Furthermore, even if both devices of the base station perform position detection during the delivery of differential diversity or reception, the quality of the reception becomes unstable and the accuracy of the position detection deteriorates.

Description of the invention It is an object of the present invention to provide a base station apparatus and a method of controlling the power of the transmission capable of accurately detecting the position of a terminal apparatus even during the delivery of differential diversity or reception. This object can be achieved when the transmission power is checked for the position detection during the delivery of the diversity or differential reception by adjusting the same target quality or target for all the base station devices involved in the delivery of diversity or differential reception and decreasing deterioration of the quality and fluctuations of a transmission signal through the control of transmission power from a base station apparatus that carries out the detection of the position involved in the delivery of diversity or differential reception.

Brief Description of the Drawings Figure 1 is an explanatory drawing for explaining the detection of the position of a terminal apparatus; Figure 2 is a diagram of slots or slots to explain the detection of the position of a terminal apparatus; Figure 3 is a drawing showing a system configuration of a base station apparatus, an apparatus of the mobile station and a controller of the radio network according to an embodiment of the present invention; Figure 4 is a block diagram showing a configuration of the base station apparatus according to the embodiment of the present invention; Figure 5 is a block diagram showing a configuration of the apparatus of the mobile station communicating with the apparatus of the station shown in Figure 4; and Figure 6 is a drawing showing a relationship between the power of an advance wave and the delay wave and time.

Best Way to Carry Out the Invention Now with reference to the accompanying drawings, one embodiment of the present invention will be explained in detail below. Figure 3 is a block diagram showing a configuration of the apparatus of the base station, the apparatus of the mobile station, which is a communication terminal, and the controller of the radio network, which controls the apparatus of the base station according to one embodiment of the present invention. First, the delivery of the diversity or differential reception will be explained using Figure 3. The apparatus of the mobile station 103 is in a state of delivery of diversity or differential reception in which it is communicating with the apparatus of the alOl base station and the bl02 base station apparatus simultaneously. Here, suppose the case where the base station apparatus alOl is detecting the position of the apparatus of the mobile station 103. The base station apparatus alOl and the base station apparatus bl02 notify the controller 104 of the radio network that the apparatus of the mobile station 103 is in a state of delivery of differential diversity or reception. The controller 104 of the radio network sends the device of the base station alOl and the base station apparatus bl02 the data to be sent to the apparatus of the mobile station 103. The base station apparatus alOl broadcasts the data using the display code A and sends them to the apparatus of the mobile station 103, and the base station apparatus bl02 displays the data using the display code B and sends them to the apparatus of the mobile station 103. The apparatus of the mobile station 103 performs the inverse operation to the display of the signal from the base station device alOl using the display code A and performs the inverse operation of the signal display from the base station apparatus bl02 using the display code B and combines these signs The apparatus of the mobile station 103 displays the data using the display code C and sends them. The base station apparatus alOl performs the inverse operation of the display of the reception signal using the display code C and sends it to the controller of the radio network 104. Similarly, the base station apparatus bl02 also performed the inverse operation to the display of the reception signal using the display code C and sends it to the controller of the radio network 104. The controller of the radio network 104 combines or selects the signals of both devices of the base station and sends them to the network. Then, the control of the transmission power during the delivery of diversity or differential reception will be explained. During the delivery of diversity or differential reception, as described above, only one of the devices of the base station is required to have good reception quality. Therefore, it is desirable to carry out the control of the common transmission power on the base station apparatus alOl and the base station apparatus bl02 based on the signals collected in the controller of the radio network. However, the collection of the signals in the controller of the radio network and then the return of the control information of the transmit power to the base station apparatus will increase the control delays, making it impossible to effect the correct control of the potency of transmission. Therefore, the control is carried out on the base station device alOl and the base station apparatus bl02 independently so that the quality of reception will not become excessively high in either of the two apparatuses. That is, the apparatus of the mobile station 103 is controlled so that the power of the transmission is increased only when the control of the power of the transmission is commanded from both the base station apparatus and the base station apparatus. bl02 instructing that the power of the transmission be "increased". In this case, if none of the apparatus of the station instructs for the transmission power to be reduced, the apparatus of the mobile station 103 decreases the power of the transmission. Therefore, if the device of the base station alOl is carrying out the detection of the position of the apparatus of the mobile station 103, the operation of the detection of the position becomes unstable. In this case, the following processing is performed. The base station apparatus alOl and the base station apparatus bl02 notify the radio network controller 104 that the apparatus of the mobile station 103 is in a state of differential diversity reception. In response to this information, the radio network controller changes the quality of the target or target (e.g., level) of the transmission power control to a level sufficient for position detection and notifies the device of the base station alOl and the apparatus of the base station bl02. Each apparatus of the base station is independently carrying out the control of the power of the transmission and increasing the quality of the target or control target of the transmission power will improve the quality of the power of the reception that arrives at each base station, which will also improve the performance of position detection. This is a simple processing such that the radio network controller changes the target quality or control target of the transmission power for a plurality of devices of the base station simultaneously, making it possible to obtain extremely effective results. More specifically, the operations of the above base station apparatus and the mobile station apparatus will be explained using FIG. 4 and FIG. 5. FIG. 4 is a block diagram showing a configuration of the base station apparatus of FIG. according to the embodiment of the present invention. Figure 5 is a block diagram showing a configuration of the mobile station apparatus which carries out a communication with the base station shown in Figure 4. Here, it is assumed that a CDMA system (Multiple Access to Code Division) is used. In Figure 4, the RF receiving sections 215 and 217 amplify the signals received by the antennas 212 to 214 respectively, converting their frequency to an intermediate frequency or frequency of the baseband, subjecting the signals to coherent detection and outputting the signals to the adapted filters 218 to 220. The adapted filters 218 to 220 perform the inverse operation to the display on the output signals from the RF reception sections 215 to 217 by their specific deployment codes and output the display signals to delay the measurement circuit of the profile 230 and the selection circuits 227 to 229. The measurement circuit 230 of the delay profile measures the delay profiles (power of reception in a predetermined time) of the adapted filters 218 to 220 and outputs the measurement result to the detection circuit of timing 222. Figure 6 illustrates an example of the result of the measurement ion of the delay profile. In Figure 6, the horizontal axis expresses the time and the vertical axis expresses the power. In a radio communication, there is not only a direct wave, which is a transmission signal that arrives directly on the receiving side but also a delay wave, which arrives after being reflected by mountains and buildings, etc. Figure 6 shows that a direct wave signal of power pO arrives at time tO and a delay wave signal of power pl arrives at time ti. The detection circuit 222 of the timing detects the time in which a signal arrives from a delay profile and outputs the information about the time in which the first reception path between the detected routes or paths was received, at selection circuits 227 and 229 and to the position detection circuit 224. The selection circuits 227 to 229 output the output signals of the adapted filters 218 to 220 at the time at which the first arrival signal reaches the address of the arrival estimator 221 based on the information output from the detection circuit 222 of the timing. The address of the arrival estimator 221 estimates the arrival direction of the reception signal from the output signals of the selection circuits 227 to 229, detects the angle of the direction between the station itself and the mobile station apparatus and makes output the information on the detected address angle to the position detecting circuit 224. The position detecting circuit 224 measures a delay of the information propagation at the time at which the first arrival signal has arrived and the information of the displacement of the timing and calculates the distance between the station itself and the apparatus of the mobile station. Then, the position detection circuit 224 outputs the terminal position information indicating the distance and angle of the direction between the station itself and the mobile station apparatus to a central control station, which does not It is shown in the Figure. The duplexer of the antenna 202 allows the same antenna to be used for both transmission and reception and outputs a signal received by the antenna 201 to the RF receiving section 203 and sends an output of the transmission signal from the section of the RF transmission 211 to the antenna 201. The RF reception section 203 amplifies the input of the reception signal from the duplexer of the antenna 202 and converts its frequency to an intermediate frequency or frequency of the baseband and makes output the signal to the adapted filter 204. The adapted filter 204 performs the inverse operation to the display by multiplying the output signal of the RF receiving section 203 by its specific deployment code and outputs the signal of the reverse operation of the display to the measurement circuit of the delay profile 225 and to the selection circuit 226. The delay profile measurement circuit 225 measures a delay profile of the output signal of the adapted filter 204 and outputs the result of the measurement to the timing detection circuit 231. The timing detection circuit 231 detects the time at which the signal exists from the delay profile and outputs the detected time information to the selection circuit 226. The Selection circuit 226 outputs the adapted filter output signal 204 to channel estimators 205 and 206. More specifically, the selection circuit 226 sends an advance wave to the estimator of channel 205 and a delay wave to the estimator of channel 206. The estimators of channel 205 and 206 estimate the variations of the amplitude and the phase of the reception signal due to the fading. Then, the RAKE 207 combination circuit synchronizes the advance wave and the delay wave and compensates for the variations of the phase and the amplitude of the fading estimated by the channel 205 estimator for the advance wave and compensates for the variations of the phase and the amplitude of the fading estimated by the estimator of channel 206 for the delay wave. Then, the RAKE combination circuit 207 performs the combination of RAKE on the corrected signals to obtain a demodulated signal and outputs the data part to the central control station, which is not shown in the Figure, and outputs a power control command to the RF transmission section 211. In addition, the RAKE combination circuit 207 performs the RAKE combination by adding the above compensated receive data to obtain the reception signal. The estimated values of the channel from the channel estimators 205 and 206 are also output to the control circuit 208 of the transmission power. The multiplexing circuit 209 multiplexes the control command of the transmission power calculated by the power control circuit of the transmission 208 with the signal of the transmission. The modulation circuit 210 carries out the processing of the primary modulation such as the QPSK modulation and the modulation of the display on this result. The RF transmission section 211 performs quadrature modulation, frequency conversion and amplification processing, etc. With respect to the amplification, the power is controlled based on the control command of the received transmission power. This radio signal is transmitted from the antenna 201 by means of the duplexer of the antenna 202. Then, the configuration of the apparatus of the mobile station carrying out a radio communication with the apparatus of the base station in Figure 4 will be explained using the block diagram in Figure 5. This apparatus of the mobile station is provided with two receiving systems for carrying out the diversity delivery or differential reception. The duplexer 302 of the antenna allows the same antenna to be used for both transmission and reception and outputs a signal received by the antenna 301 to the RF reception sections 303a and 303b and sends an output of the signal of the transmission from the RF transmission section 313 to the antenna 301. The RF reception sections 303a and 303b amplify the input of the reception signal from the antenna duplexer 302 and convert their frequency to an intermediate frequency or frequency of the baseband and outputs the signals to the adapted filters 304a and 304b respectively. The adapted filters 304a and 304b perform the inverse operation to the display by multiplying the output signals of the RF reception sections 303a and 303b by their specific deployment code and output the signals of the inverse operation of the display to the profile measurement circuit delay 307 and selection circuits 305a and 305b. The measuring circuit of the delay profile 307 measures the delay profiles of the output signals of the adapted filters 304a and 304b and outputs the measurement result to the timing detection circuit 308. The timing detection circuit 308 detects the time at which the signals exist from the delay profiles and outputs the detected time information to the selection circuits 305a and 305b. The selection circuits 305a and 305b output the output signals of the adapted filters 304a and 304b to the channel estimators 306a and 306b. More specifically, selection circuits 305a and 305b send a forward wave to the channel estimator 306a and a delay wave to the channel estimator 306b. The estimators of the channels 306a and 306b estimate the variations of the phase and of the amplitude due to the fading of their respective reception signals. The combination circuit of RAKE 309 synchronizes the advance wave and the delay wave and compensates for the variations of the phase and the amplitude of the fading estimated by the channel estimator 306a for the advance wave and compensates for the variations of the phase and the amplitude of the fading estimated by the channel estimator 306b for the delay wave. Then, the RAKE combination circuit 309 performs the combination of RAKE on the corrected signals to obtain a demodulated signal and outputs the data part to the central control station, which is not shown in the Figure, and it outputs a power control command to the RF transmission section 313. In addition, the RAKE combination circuit 309 performs the RAKE combination by adding the data of the previous compensated reception to obtain the reception signal. The estimated values of the channel from the channel estimators 306a and 306b are also output to the power control circuit of the transmission 310. The multiplexing circuit 311 multiplexes the control command of the transmission power calculated by the circuit control of the transmission power 310 with the signal of the transmission. The modulation circuit 312 carries out the processing of the primary modulation such as the modulation of QPSK and the modulation of the display on this result. The RF 313 transmission section carries out the modulation of the quadrature, the conversion of the frequency and the processing of the amplification, etc. With respect to the amplification, the power is controlled based on the control command of the power of the received transmission. This radio signal is transmitted from the antenna 301 by means of the duplexer 302 of the antenna. Then, the operation of detecting the position in a state of delivery of diversity or differential reception carried out by the apparatus of the base station with the above configuration of the present invention, will be explained. Assume a case in which the apparatus of the mobile station sends to the controller of the radio network the information that the apparatus of the mobile station is in a state of delivery of differential diversity or reception. The controller of the radio network sends an instruction for a change to all of the base station devices involved in the delivery of differential diversity or reception to increase the quality of the target or control target of the transmission power to the apparatus of the mobile station. This instruction for a change is input to the transmission power control circuit 208 of the base station apparatus as the quality of the target or target. Each base station device monitors the power of the transmission based on the quality of the target or target changed. As an example of the method of controlling the transmission power, the power of the desired wave (S) and the power of the interference wave (I) in a reception signal are measured and if the ratio (SIR) is lower than the target or target quality, a control command of the transmission power to increase the power of the transmission is generated, and if the ratio is higher than the target or target quality, a control command of the Transmission power to reduce the power of the transmission, is generated. This target quality or control objective of the transmission power is changed between an immediate attention that requires a service, which requires a certain degree of accuracy and another special service when appropriate. For example, the control is carried out in such a way that a service that requires immediate attention such as an emergency call and a service that requires accuracy such as a delivery of differential diversity or reception, the quality of target or target is increased, while for a service that does not require immediate attention and a service with little accuracy, the quality of target or target is not increased as much. Performing such control makes it possible to carry out the position detection according to the required accuracy and also reduces the interference with other devices of the base station.

With respect to position detection, first, the signal received by the antenna 212 is amplified and its frequency converted to an intermediate frequency or frequency of the baseband by the RF reception section 215. To the output signal from the RF reception section 215 the reverse operation is performed to the display by the adapted filter 218 using its specific deployment code and the measurement circuit is output to the delay profile 230 and to the selection circuit 227. Similarly , the signal received by the antenna 213 is amplified and its frequency converted to an intermediate frequency or frequency of the baseband by the RF reception circuit 216. The output of the RF reception circuit 216 is applied to the output signal. Inverse to the display using a specific display code by the adapted filter 219 and the measurement circuit of the delay profile 230 and the selection circuit 228. In further, the signal received by the antenna 214 is amplified and its frequency converted to an intermediate frequency or frequency of the baseband by the RF reception circuit 217. The output signal of the RF reception circuit 217 is reverse operation to the deployment using a specific deployment code by the adapted filter 220 and output to the measurement circuit of the delay profile 230 and the selection circuit 229. The measurement circuit of the delay profile 230 measures the delay profiles of the output signals of the adapted filters 218 and 220 and the timing detection circuit 222 detects the arrival time of each reception signal and outputs the information on the arrival time of the first arrival signal (wave of reception). advance) of the detected arrival times to the selection circuits 227 to 229 and the detection circuits of the position 224. The selection circuits 227 to 229 h the output signals of the matched filters 218 to 220 are output at the arrival time of the first arrival signal to the arrival estimator address 221 based on the information output from the timing detection circuit 222. The address of the arrival estimator 221 estimates the arrival direction of the reception signal based on the output signals of the selection circuits 227 to 229, detects the direction angle formed between the station itself and the mobile station apparatus and outputs the information about the detected address angle to the position detection circuit 224. The position detection circuit 224 measures a delay of the propagation from the information on the arrival time of the first arrival signal and the time displacement information and calculates the distance between the station itself and the apparatus of the mobile station. Then, the position detection circuit 224 outputs the terminal position information indicating the distance and angle of the direction between the station itself and the apparatus of the mobile station to the controller of the radio network. As shown above, carrying out the processing of simultaneously indicating the target or target quality for the control of the transmission power from the control of the radio network to the base station apparatus involved in the delivery of the diversity or Differential reception, that is, the simple processing of sending the same value to all the devices of the base station involved in the delivery of diversity or differential reception, makes it possible to carry out the detection of the position correctly even during the delivery of the diversity or differential reception and reduces interference with other devices of the base station. Therefore, it is possible to control the transmission power to a level where the detection of the position is possible without problems even during the delivery of the diversity or differential reception during which the quality of the reception is unstable. The above modality describes the case where the target quality of the transmission power control is changed when the position detection is made during the delivery of the diversity or differential reception, but the present invention is not limited to such a unique situation. The present invention is also applicable to cases where the operation of the control of the power of the transmission is changed in a specific situation or when a specific service is provided. For example, it is possible to perform such a control that raises the target or target quality for a service that requires immediate attention and does not raise the target or target quality much for a service that does not require immediate attention and with low accuracy. The operation of such transmission power control in accordance with the required accuracy can also reduce the interference with other devices of the base station. This application is based on Japanese Patent Application No. HEI 10-336112 filed on November 26, 1998, the entire contents of which is expressly incorporated herein for reference.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (7)

1. A base station apparatus, characterized in that it comprises: receiving means for receiving the information about a change in the target quality or the purpose of the transmitting power control broadcasting to the related base station apparatus from a radio station. control that controls a plurality of devices of the base station; and means for controlling the power of the transmission to change the target quality or control purpose of the transmission power based on the information and to control the power of the transmission on a terminal communication apparatus with the Target quality changed or target changed.

2. The base station apparatus according to claim 1, characterized in that the means of controlling the power of the transmission effect the control of the power of the transmission on the communication terminal with the quality of target or target changed during the transmission. Diversity delivery or differential reception.

3. The apparatus of the base station according to claim 1, characterized in that it further comprises: estimation means for estimating the direction of arrival of the signals from the signals received from a plurality of antennas; and means for detecting the position, for detecting the position of the communication terminal apparatus from a forward wave of the signal from the estimated arrival direction.

4. A base station apparatus, characterized in that it comprises: notification means for notifying a control station controlling the devices of the base station that the delivery of differential diversity or reception is being carried out; and means for controlling the power of the transmission, to effect the control of the power of the transmission based on the information on the control of the power of the transmission whose quality of target or target has been changed in accordance with an instruction from the control station.

5. A method of controlling the transmission power, characterized in that it comprises the steps of: receiving the information about a change in the target quality or the purpose of the broadcasting control of the power of the transmission to the related base station apparatus from a control station controlling a plurality of devices of the base station; and changing the target quality of the power control of the transmission based on the information and effecting the transmission of the power control on a terminal communication device with target quality changed or target changed.

6. The method of controlling the power of the transmission according to claim 5, characterized in that the transmission power control is carried out on the communication terminal apparatus with the quality of target or target changed during the delivery of the transmission. diversity or differential reception.

7. A method for detecting the position, characterized in that it comprises the steps of: receiving the information about a change in the target quality or the purpose of the radio broadcasting control of the power of the transmission to the related base station apparatus from a station of control that controls a plurality of the devices of the base station; changing the target quality of the control of the transmission power based on the information and effecting the control of the transmission power on a communication terminal with the target quality changed; estimating the direction of arrival of the signals transmitted from the communication terminal apparatus with the target or target quality changed and received by a plurality of antennas; and detecting the position of the communication terminal apparatus from a forward wave of the signal in the estimated arrival direction. BASE STATION DEVICE AND TRANSMISSION POWER CONTROL METHOD SUMMARY OF THE INVENTION The radio network controller sends the same target quality value or target to transmit the power control to the base stations involved in the delivery of the diversity or differential reception simultaneously. This makes it possible to correctly detect the position even during the delivery of differential diversity or reception and to reduce interference with other base stations. In addition, carry out such a control that raises the target quality of the control of transmission power for a service that requires immediate attention and that does not raise the quality of target or target for a service with low accuracy and without requiring attention. Immediate, it can make compatible position detection according to the required accuracy compatible with the reduction of interference with other base stations.