JP2009010984A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speedily recover quality after selective combination, even in a case where radio channel equality is reduced by an external failure. <P>SOLUTION: During soft hand-over, a base station control station determines a base station to which best line quality is provided, in accordance with signal quality of a plurality of transmission signals received from base stations, and notifies the base station (BTS_A) to which the best line quality is provided, about an instruction to increase/decrease reference quality for the base station. The base station judges whether or not increase/decrease is instructed and performs transmit power control, based on system setting values, on a base station (BTS_B) that does not receive the increase/decrease instruction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless communication system. In particular, the present invention relates to reception of a reference radio channel during soft handover in which a mobile station is simultaneously connected to a plurality of base stations in a mobile communication system of code division multiple access (hereinafter abbreviated as CDMA (code division multiple access)). The present invention relates to a radio communication system that controls transmission power so that quality satisfies predetermined reception quality.

  In general, in a CDMA system in a cellular mobile communication system, a plurality of mobile terminals share the same frequency band and communicate with a base station. Therefore, when a mobile terminal and a base station communicate with each other, a signal transmitted from the mobile terminal to the base station (desired signal) is a signal transmitted from the other mobile terminal to the base station (undesired signal). This may cause interference and hinder communication between the desired mobile terminal and the base station. The interference level increases in proportion to the reception level of the undesired signal wave received by the base station, and the reception level of the undesired signal is proportional to the transmission power transmitted from the undesired mobile terminal. Therefore, in order to minimize the interference level, the transmission power from the mobile terminal is controlled by the base station, and transmission power control is required so that the reception level at the base station is always the minimum necessary.

  Conventionally, for transmission power control, the signal-to-interference ratio SIR (Signal to Interference Ratio) measured at the base station and reception quality such as reception power are compared with a predetermined target value, and the transmission power is increased based on the result. Alternatively, the base station notifies the mobile station to decrease, and the mobile station is known to perform closed loop power control such as determining the transmission power based on the notification from the base station, and further, the base station and the base station control station Also, it is known that the quality target value of the closed loop power control of the base station is controlled so that the reception quality at the base station control station becomes equal to the target value.

  In transmission power control during soft handover in which a mobile station is simultaneously connected to a plurality of base stations, a base station control station connected to a plurality of base stations as disclosed in “Japanese Patent Laid-Open No. 10-13922” And comparing the data quality after the selective combination with a predetermined target value, and based on the result, notifies all the connected base stations of the correction value for the target value of the closed-loop power control. Is known to further reduce the transmission power of a mobile station by controlling the transmission power with the corrected target value.

  In the above conventional method, the received power at the base station suddenly changes due to actual external disturbances (base station or base station control station failure, other interference waves, weather, buildings, machinery, heavy machinery, etc.) The case of decreasing is not taken into consideration. The case where the electric field conductivity fluctuates due to the direct wave and the reflected wave being blocked as in the shadow effect will be described below.

  FIG. 17 is a diagram showing a configuration in a hander in a conventional mobile communication system. For example, as shown in FIG. 17, during a soft handover in which a mobile station (MS) 800 is simultaneously communicating with a base station A (BTS_A) 850 and a base station B (BTS_B) 870, a base station control station (BSC) 860 Consider a case where there is a difference in signal quality between BTS_A850 and BTS_B870, in which most of the signals after selective combining in BTS are signals via BTS_A850.

  The MS 800 includes a transmitter (Tx804) that performs transmission processing, a variable gain amplifier 803, a transmission power control determination unit (TPC (transfer power control) determination unit) 805 that performs transmission power control, 805, a circulator 802, a transmission / reception antenna 801, and reception processing A receiver (Rx806) is provided. The BTS_A 850 includes a transmission / reception antenna 851 and a circulator 852, an Rx 853 for reception processing, an SIR 854 for measuring the SIR of the received signal, a target SIR setting unit 856 for setting and storing the target SIR, a comparison unit 855 for comparing the target SIR and the reception SIR, An adder 857 for adding a transmission power control signal to the transmission signal and a Tx 858 for performing transmission processing are provided. Also, BTS_B870 has the same configuration as BTS_A850. Further, the BSC 860 compares the selective combining unit 861 that performs selective combining, the FER unit 862 that measures the received FER (frame error rate) after the selective combining, the target FER storage unit 864 that stores the target FER, and the received FER and the target FER. And a comparator 863 for adding a transmission power control signal to the control signal.

  First, closed loop transmission power control between the MS 800 and the BTS_A 850 will be described. The uplink signal transmitted from the MS 800 (the uplink signal is a signal transmitted from the MS to the BSC 860) is received by the antenna 851 of the BTS_A850. The signal received from the antenna passes through the circulator 852, is subjected to reception processing by Rx853, and is transmitted to the SIR measurement unit 854 and the BSC 860. The SIR measurement unit 854 measures the SIR (Signal Information Ratio) of the input received signal and transfers it to the comparison unit 855. The comparison unit 855 compares the input received SIR with a predetermined target SIR. As a result, if the received SIR is smaller than the target SIR, the comparison result is obtained from the transmission power control signal that means an increase in transmission power. When the received SIR is larger than the target SIR, the adder 857 adds a transmit power control signal indicating a decrease in transmit power to the downlink signal (the downlink signal is a signal transmitted from the BSC 860 to the MS). The transmission signal to which the transmission power control signal is added is transmitted from the antenna 851 to the MS 800 after passing through the circulator 852.

  A signal transmitted from the BTS_A 850 is received from the MS antenna 801 and transferred to the Rx 806 via the circulator 802. In Rx, the transmission power control signal is extracted from the received signal and transferred to the TPC determination unit 805. The TPC determination unit 850 determines the meaning of the transmission power control signal. If the determination result is a transmission power increase instruction, the TPC determination unit 850 controls gain increase for the variable gain increaser 803. If the determination result is a transmission power control decrease instruction, the gain decrease control is performed for the variable gain increaser 803. The transmission signal of the MS is subjected to transmission processing at Tx 804 and then transmitted from the antenna 801 after being increased or decreased to a predetermined gain by the variable gain increaser 803 controlled by the TPC determination unit 805. By repeating this operation, the received SIR at BTS_A850 converges to the target SIR.

  Next, transmission power control during handover will be described. Since MS 800 communicates between BTS_A 850 and BTS_B 870, uplink signals transmitted from MS 800 are received by the antennas of BTS_A 850 and BTS_B 870, and The BTS performs the above operation and transmits a transmission signal to which a transmission power control signal is added from each antenna. The transmission power control increase / decrease instructions for BTS_A 850 and BTS_B 870 do not always coincide with each other due to the difference in the radio channel and the initial value of the target SIR.

  MS 800 receives transmission signals from BTS_A 850 and BTS_B 870 and performs reception processing by maximum ratio combining. In the determination by TPC determination section 805, if there is at least one instruction to decrease the transmission power control signal, variable gain amplifier 803 The gain reduction control is performed for. Conversely, in order to determine gain amplification, for example, all transmission power control signals must be instructed to increase. This operation means that a determination is made based on a received signal having good reception quality.

  Next, target SIR update control between the BTS and BSC during handover will be described. The uplink signals received and processed by BTS_A850 and BTS_B870 are sent to BSC860. In the BSC 860, the reception signals of BTS_A850 and BTS_B870 are selectively combined by the selection combining unit 861, and a high-quality signal is transferred to the upper station. The selectively synthesized signal is input to the FER unit 862, and the FER unit measures the FER of the input signal and transfers it to the comparison unit 863. The comparison unit 863 compares the target FER determined by the system with a target SIR update control signal that indicates an increase in the target SIR of the BTS and the comparison result when the received FER is larger than the target FER. If the received FER is smaller than the target FER, a target SIR update signal indicating a decrease in the target SIR is transmitted to the adder 865. The adder 865 puts the signal input from the comparison unit 863 on the BTS-BSC control signal and transmits the signal to the BTS_A 850 and BTS_B 870 during handover. BTS_A 850 and BTS_B 870 decode the control signal received from BSC 860 to decode whether the target SIR update signal is an instruction to increase or decrease the target SIR. If the decoding result is an increase instruction, the target SIR is increased. If the decoding result is a decrease instruction, the target SIR is decreased. By repeating this operation, it is possible to converge the signal after selective combining in the BSC 860 to the quality of the target FER. In the prior art, it is known that the target SIR update period T between BTS and BSC is sufficiently longer than the closed loop transmission power control period τ between BTS and MS.

  FIG. 18 is a graph showing transmission power control in a conventional mobile communication system. Next, the case where the radio channel quality is sufficiently higher between BTS_A and MS than between BTS_B and MS during handover will be described using the graph of FIG. Here, FIG. 18 (A) is a graph showing the transition of transmission power in the MS, FIG. 18 (B) is a graph showing the transition of the target SIR and the transition of the reception SIR in each BTS, and FIG. 18 (C). Represents the transition of the received FER after selective combining in the BSC.

  The target SIRs of BTS_A 850 and BTS_B 870 differ from each other due to a difference in initial values when a handover is added. The uplink signal transmitted from the MS 800 is received by the BTS_A 850 and the BTS_B 870, and each reception SIR is measured to perform closed loop transmission power control. In MS 800, reception processing and transmission power control determination are performed by the maximum ratio combining of received signals, so that the transmission power control determination result is to control variable gain increaser 803 based on the BTS_A850 signal with good radio path quality. Become. Therefore, the transmission power 901 of the MS 800 from t0 to t2 is controlled so that the reception SIR 903 of the BTS_A 850 converges to the target SIR 902 of the BTS_A 850. On the other hand, the reception SIR 905 of BTS_B 870 is lower than the target SIR 904 because the radio channel quality is poor, and the transmission power control signal is urged to increase the transmission power, but the transmission power control determination of MS 800 uses the transmission power control signal of BTS_A 850. In addition, the target SIR of BTS_B870 cannot converge.

  Next, looking at the reception FER 908 of the BSC 860 at time t0 to t2, the quality is better than the target FER 907. This means that most of the signals after selective synthesis are received signals from the BTS_A850 with good quality, and the target SIR update control substantially determines the target SIR based on the FER of the BTS_A850 signal. become. In the case of this graph, since the reception FER 908 is better than the target FER 907, control is performed at an interval of the target SIR update period T910 so as to lower the target SIR, and the reception FER 908 converges to the target FER 907. Further, it can be seen that the transmission power 901 of the MS 800 also decreases as the target SIR of the BTS_A 850 and the BTS_B 870 decreases.

  Next, assuming that the received power suddenly decreases due to an obstacle appearing between the MS 800 and the BTS_A 850 after the time t2, the reception SIR 903 of the BTS_A 850 rapidly decreases from the time t2 to the time t3 in the graph. As a result, the reception FER 908 of the BSC 860 also deteriorates rapidly. When the reception SIR 903 of the BTS_A 850 is lowered, there is an intersection tA with the reception SIR 905 of the BTS_B 870, and when this tA is passed, the selection signal destination in the selection combining unit 861 of the BSC 860 moves from the signal of BTS_A 850 to the signal of BTS_B 870. become. Also, in MS 800, the transmission power control determination is changed to be determined based on the transmission power control signal of BTS_B 870 as the quality of the downstream signal of BTS_A 850 850 decreases, and between 800 and t3, MS 800 determines the target SIR 904 of BTS_B 870. Increase transmission power to satisfy The reception FER 908 in the BSC 860 converges to a certain FER 909 by this closed loop transmission power control. However, the reception FER 908 at this time does not satisfy the target FER 907. This is because the target SIR 904 of the BTS_B 870 that has converged at this time is a value that is controlled and determined when the radio channel quality of the MS 800 and the BTS_A 850 is good and the signal after selective combining in the BSC 860 is almost a BTS_A 850 signal. That's why.

After t3, since the reception FER 908 at the BSC 860 is worse than the target FER 907, the target SIRs of BTS_A850 and BTS_B870 are controlled to increase and gradually approach the target FER at the target SIR update cycle T910.
However, since the target SIR update period T is very long, it takes time to settle down to the target FER, and a state in which the quality cannot be maintained continues for a considerable time. Further, if the reception FER 909 after the selection destination in the selection combining unit 861 of the BSC 860 is changed from the signal of BTS_A 850 to the signal of BTS_B 870 exceeds the FER 906 where the call release occurs, and is held for a time during which synchronization cannot be maintained. A problem that causes call disconnection occurs.

  In view of the above points, the object of the present invention is a wireless that can quickly converge to a target signal quality and recover even if the data quality deteriorates rapidly during the soft handover, such as the shadow effect. It is to provide a communication system. It is a further object of the present invention to provide a cellular mobile communication system in which call disconnection is reduced against shadow fluctuations caused by external failures.

  In order to achieve the above object, the present invention provides a mobile communication system and a base station that are engaged in a call in a code division multiple access mobile communication system so that the reception quality of each radio channel is equal to a predetermined reference quality. During soft handover in which a mobile station is connected to a plurality of base stations at the same time, the plurality of base stations are connected to the base station control station via a wired line, and the plurality of base stations are connected to the base station control station. In a mobile communication system in which a plurality of transmission signals are selectively combined in a base station control station, the base station control station is present with respect to the base station so that the signal quality after selective combining is equal to a predetermined quality. One feature is that it has a function of updating a reference quality value used in transmission power control in a cycle, and the update for this control has a short cycle time.

  In order to achieve the above object, in the mobile communication system, the base station control station updates the reference quality value used in the transmission power control of the base station to be the same as the transmission power control period time. Other features.

  Furthermore, in order to achieve the above object, a mobile station and a base station in a call in a code division multiple access mobile communication system perform transmission power control so that the reception quality of each radio channel is equal to a predetermined reference quality. A plurality of base stations are connected to the base station control station via a wired line, and a plurality of base stations are connected to the base station control station during a soft handover in which the mobile station is simultaneously connected to the plurality of base stations. In a mobile communication system in which transmission signals are selectively combined in a base station control station, the base station control station provides the best channel quality according to the signal quality of a plurality of transmission signals received from the base station during soft handover. A means for determining a base station and a function for notifying a base station that provides the best channel quality of a reference quality increase / decrease instruction to the base station. Means for determining the presence or absence, the base station does not receive an increase or decrease instruction, to perform a transmit power system settings based on, and other features.

  In order to achieve the above object, in the base station control station, the means for determining the base station that provides the best channel quality is selected by selective combining with the signal received from the base station during handover before selective combining. Another feature was to determine by measuring the proportion of the signal.

  In order to achieve the above object, in the base station, the means for determining whether or not there is a reference quality increase / decrease instruction from the base station control station is realized by having a function of managing the standby time. It was.

  In order to achieve the above object, in the base station, the base station that does not receive the reference quality increase / decrease instruction from the base station control station sets the reference quality value for transmission power control to the system initial setting value. It was characterized.

  Furthermore, in order to achieve the above object, a mobile station and a base station in a call in a code division multiple access mobile communication system perform transmission power control so that the reception quality of each radio channel is equal to a predetermined reference quality. A plurality of base stations are connected to the base station control station via a wired line, and a plurality of base stations are connected to the base station control station during a soft handover in which the mobile station is simultaneously connected to the plurality of base stations. In a mobile communication system in which a transmission signal is selectively combined in a base station control station, the base station includes means for comparing a difference between a reference quality and a reception quality with a predetermined threshold, and the base station determines the base station based on the comparison result. When a station has a function to determine whether or not it is a base station that independently provides the best channel quality, and determines that the base station is not a base station that provides the best channel quality In That performs transmission based power control system initialization values, and other features.

In addition, in order to achieve the above object, when the base station determines that the difference between the reference quality and the reception quality and the predetermined threshold value are smaller than the threshold value, in the base station Another feature is that the base station determines that the base station is providing the best channel quality.
In addition, in order to achieve the above object, the result of comparing the difference between the reference quality and the reception quality and the predetermined threshold in the described base station is determined that the difference between the reference quality and the reception quality is larger than the threshold. In such a case, it is possible to provide a feature that determines that the base station is not a base station that provides the best channel quality.

In addition, in order to achieve the above object, when the base station determines that the difference between the reference quality and the reception quality and the predetermined threshold value are smaller than the threshold value, in the base station Only, it is possible to provide a feature according to a reference quality increase / decrease instruction from the base station control station.
In addition, in order to achieve the above object, when the base station determines that the difference between the reference quality and the reception quality and the predetermined threshold value are smaller than the threshold value, in the base station Can be configured to perform transmission power control by setting the reference quality of the base station to the system initial setting value.

  According to the present invention, it is possible to solve the above-described problems of the conventional technique and to quickly recover the quality after selective combining even when the wireless channel quality is deteriorated due to an external failure. High signal can be supplied. Furthermore, it is possible to realize a cellular mobile communication system in which call disconnection is reduced with respect to shadow fluctuation due to an external failure.

Hereinafter, embodiments of the invention will be described.
(1) Description of Embodiment 1 FIG. 1 is a diagram showing a configuration during handover in a cellular mobile communication system to which the present invention is applied. That is, FIG. 1 is a diagram illustrating an MS 400 during soft handover and BTS_A 100, BTS_B 200, and BSC 300 that are handover destinations in a CDMA mobile communication system to which the transmission power control method of the present invention is applied. The MS 400 receives the downlink radio channel from the BTS_A 100 and the downlink radio channel from the BTS_B 200, and transmits a common uplink radio channel to both BTSs.

  Further, the transmission power of the MS 400 and each BTS is controlled between the BTS_A 100 and the MS 400 and between the BTS_B 200 and the MS 400 by transmission power control. The transmission power control is realized by using, for example, a TPC bit of the dedicated physical channel 250 including a header, a TPC bit, and user information. At this time, as an example, when the BTS_A 100 and the BTS_B 200 give an instruction to increase the transmission power to the MS 400, the TPC bit is set to “11”, and conversely, when the instruction to lower the transmission power is given, the TPC bit Is added to the downstream physical channel as “00” and transmitted. When receiving the dedicated physical channel 250, the MS 400 looks at the TPC bit. If it is determined to be “11”, the MS 400 increases the transmission power to the BTS, and conversely if it determines “00”, the MS 400 decreases the transmission power. Also, the data format is the same for the uplink direction, and the transmission power of the BTS is controlled by the TPC bit.

  The BTS_A 100 is connected to the BSC 300 via the wired line 410, and the BTS_B 200 is connected to the BSC 300 via the wired line 420. In the BSC 300, the upstream signal is selectively combined and the higher quality upstream signal is transmitted. Can be sent to the station. Between each BTS and the BSC 300, there is a control for updating the target SIR of the BTS based on the comparison result between the FER and the target FER at the BSC 300. This control is performed by using the inter-station control channel 252 between the BTS and the BSC 300. It is realized by using. When the BSC 300 wants to instruct the BTS to update the target SIR, it sends the target SIR update signal on the data part of the inter-station control channel 252 and the BTS decodes the contents of the target SIR update signal and decodes the result. The target SIR is updated accordingly.

  In this embodiment, as an example, it is assumed that the radio channel quality during handover is higher in the radio channel quality between BTS_A 100 and MS 400 than the radio channel quality between BTS_B 200 and MS 400. In each embodiment, the reference quality at the base station is described using SIR, and the signal quality at the base station control station is described using FER. However, the present invention is not limited to this. Appropriate parameters can be used. For example, signal specific interference power per bit Eb / No (Bit Energy Noise), bit error rate, frame error rate, carrier-to-interference power CIR (carrier interference ratio) ), A call loss rate, or the like.

  The system configuration in the first embodiment is the same as the conventional configuration of FIG. 17, but the main feature is that the target SIR update period T510 between the BTS and the BSC 300 is set shorter than the conventional one. It is. The operation of the first embodiment will be described using a graph.

  FIG. 2 is a graph showing transmission power control in Embodiment 1 to which the present invention is applied. 2A is a graph showing the transmission power of the MS 400 from the top, FIG. 2B is a graph showing the target SIR and reception SIR of the BTS_A 100 and BTS_B 200, and FIG. 2C is a graph showing the reception FER at the BSC. Compared to the conventional graph of FIG. 18, in particular, the target SIR update period T510 is set shorter.

  Times t0 to t3 are when the radio channel quality between the BTS_A 100 and the MS 400 is good. Since the closed-loop transmission power control during handover by the MS 400 selects a transmission power control signal with good quality, the closed-loop transmission power control is performed based on the transmission power control signal of the BTS_A100, and the reception SIR 503 at the BTS_A100 is the target SIR502. Converge to. Conversely, reception SIR 505 at BTS_B 200 is lower than target SIR 504 because MS 400 does not perform closed-loop transmission power control based on the transmission power control signal of BTS_B 200. Since the reception FER 508 at t1 is better in quality than the target FER 507, the BSC 300 issues a control signal for lowering the target SIR to the BTS_A100 and BTS_B200 during the target SIR update time at t1. The BTS_A100 and BTS_B200 that have received the control signal lower the target SIR according to the control signal. When the target SIR decreases, the reception SIR 503 of the BTS_A 100 at t1 becomes higher than the target SIR 502, the MS 400 lowers the transmission power 501 by the closed loop transmission power control, and the reception SIR 503 of the BTS_A 100 converges to the target SIR 502. Furthermore, the reception FER 508 at the BSC 300 also converges to the target FER 507.

  Next, if the quality of the radio channel is deteriorated due to an obstacle entering the radio channel between the BTS_A 100100 and the MS 400 after t3, the reception SIR 503 at the BTS_A 100 is drastically lowered. Along with this, the reception FER 508 of the BSC 300 also deteriorates rapidly, and the transmission power 501 of the MS 400 increases by the closed loop transmission power control. In the BSC 300, when the reception SIR 503 of the BTS_A100 becomes lower than the reception SIR 505 of the BTS_B200, the signal selected by the selection combining unit changes from the signal via the BTS_A100 to the signal via the BTS_B200, and the increase in the reception FER 508 stops. Next, at t4, the target SIR is raised by the target SIR update control, and the FER is improved immediately. Furthermore, since the time exceeding the call release FER 506 is shortened, loss of synchronization does not occur and call release does not occur. If this operation is repeated, the received FER converges to the target FER after t7 and satisfies the quality. As described above, by shortening the target SIR update cycle T510, even when the reception FER 508 is deteriorated, the target FER 507 can be quickly approached.

  FIG. 4 is a block diagram showing the configuration of BTS_A100 and BTS_B200. In the figure, an antenna 101 that transmits and receives radio signals, a circulator 102 that distributes uplink and downlink signals, a reception unit (RxRF) 103 that performs reception processing at high frequencies and intermediate frequencies, and a despreading circuit 104a that performs despreading processing 104n, decoding units 105a to 105n that perform upstream signal decoding processing, an upstream information unit 106 that inserts and separates a call signal and a control signal from the upstream signal, an upstream LIF unit 107 that has a transmission interface to the BSC 300, and an SIR of the upstream signal Uplink SIR measurement unit 108 to measure, comparator S109 that compares reception SIR with target SIR specified by control unit 150 and creates a transmission power control signal based on the comparison result, and downlink LIF unit having a reception interface from BSC 300 111. Downlink information for separating and inserting a call signal and a control signal from a downlink signal Unit 111, encoding units 112a to 112n for encoding the downlink signal, frame creation units 113a to 113n for adding the transmission power control signal input from the comparator to the downlink signal and generating a frame, and a spreading circuit for performing spreading processing 114a to 114n, an addition circuit 115 for adding up signals input from the spreading circuit, a transmission unit (TxRF) 116 for performing high frequency / intermediate frequency processing of down signals, and a control unit for updating the target SIR by a control signal from the BSC 300 150.

  Next, FIG. 5 is a block diagram showing the configuration of the BSC 300. In the figure, line interface units (LIF units) 301a to 301n having an interface with a BTS, a switch (SW) 302 that performs signal exchange processing, a selection combining unit 320 that performs selection combining processing in the hand bar, and a higher station An upper station IF unit 304 having a transmission interface, an uplink FER measurement unit 305 that measures the FER of the uplink signal after selective combining, a comparator 306 that compares the measured FER with a target FER input from the control unit, and a comparator A control signal generator 307 that generates a control signal based on the comparison result of the above, an upper station IF 308 having a reception interface to the upper station, an adder 309 that inserts the control signal into the downlink signal, and a downlink signal replicated to the BTS that is being handed over And a target SIR control unit 350 that estimates a main path.

  In the CDMA mobile communication system configured as described above, the MS 400 and BTS that are undergoing handover perform transmission power control at a closed loop power control period τ so that the reception quality of each radio channel is equal to a predetermined reference quality, In the BSC 300, the target SIR is corrected and controlled at a predetermined target SIR update period T so that the received FER becomes equal to the predetermined target FER.

  More specifically, first, the BTS_A 100 receives the uplink signal transmitted from the MS 400 by the antenna 101 and transfers it to the RxRF 103 via the circulator 102. In the RxRF 103, demodulation of the baseband signal and reception processing at a high / intermediate frequency are performed, and the baseband signal is transferred to the despreading circuits 104a to 104n. In the despreading circuits 104a to 104n, the uplink signal is subjected to despreading processing using the designated spreading code, and the uplink signal of the MS 400 is extracted. The extracted uplink signal of the MS 400 is input to the uplink channel SIR measurement unit 108 and the decoding units 105a to 105n. Decoding sections 105 a to 105 n perform error correction control processing such as deinterleaving and Viterbi decoding on the input uplink signal, add quality information of the radio channel, and transmit the uplink signal to uplink information section 106. The uplink information unit 106 separates the control signal and the call signal from the uplink signal, selects a signal to be transmitted to the BSC 300, and transmits the signal to the BSC 300 via the uplink LIF unit 107.

  On the other hand, the uplink channel SIR measurement unit 108 measures the SIR of the input uplink signal and transfers the received SIR to the comparison unit 109. The comparison unit 109 compares the input reception SIR with the target SIR specified by the control unit 150. If the reception SIR is smaller than the target SIR, the comparison unit 109 receives a transmission power control signal indicating an increase in transmission power. When the SIR is larger than the target SIR, a transmission power control signal that means a reduction in transmission power is generated, and the signal is transmitted to the frame generation units 113a to 113n.

  A downlink signal received from the BSC 300 is input to the downlink information unit 111 via the downlink LIF 110. In the downlink information section, a control signal that needs to be terminated at BTS_A100 (for example, a control signal for instructing increase / decrease of the target SIR) is transferred to the control section 150, and is encoded into a signal to be transmitted to the MS400. The data is transferred to the units 112a to 112n. The downlink signals input to the encoding units 112a to 112n are subjected to interleaving, encoding processing, and the like, and transmitted to the frame creation units 113a to 113n. In frame creation sections 113a to 113n, the transmission power control signal input from comparison section 109 is added to the downlink signal input from encoding sections 112a to 112n and transferred to spreading circuits 114a to 114n. Spreading circuits 114 a to 114 n spread the downstream signal and transmit it to addition circuit 115. The adder circuit 115 adds the downstream signals input from the respective spreading circuits and transfers them to the TxRF 116. The downlink signal input to the TxRF 116 is subjected to high / intermediate frequency transmission processing and transmitted from the antenna 101 to the MS 400 via the circulator 102. In BTS_B200, the same processing is performed with the same configuration, and the downlink signal to which the transmission power control signal is added is transmitted from the antenna.

  In MS 400, the downlink signals received from BTS_A100 and BTS_B200 are subjected to reception processing by, for example, maximum ratio combining, etc., and as a result, transmission power control determination using a transmission power control signal of a good quality signal is performed. Will do. In this case, since the radio channel quality with the BTS_A 100 is better, the transmission power control signal of the BTS_A 100 is decoded and the transmission power of the MS 400 is determined according to the power increase / decrease instruction.

  On the other hand, the uplink signal transmitted from the BTS_A 100 to the BSC 300 is input to the SW 302 via the line interface (LIF) 301a, and the uplink signal transmitted from the BTS_B 200 to the BSC 300 is input to the SW 302 via the LIF 301n. The In SW 302, the uplink signals of BTS_A 100 and BTS_B 200 in the handover are exchanged with the selective combining unit 320.

(2) Description of Embodiment 2 Next, Embodiment 2 will be described. First, the base station control station will be described.
FIG. 7 is a diagram showing a block configuration of the selection / combination unit in the base station control station. The selection / combination unit 320 includes buffers 321a to 321n, a selection determination unit 322, and a selection unit 323 as shown in the figure. The uplink signal input from the SW 302 is temporarily buffered via the signal lines 324a to 324n. The delay difference of the signal to be compared is absorbed. The selection determination unit 323 compares the quality information added to the uplink signals of BTS_A100 and BTS_B200, and performs selection determination of a signal with higher quality. The determination result is communicated to the selection unit 323 and the target SIR update control unit 350 through the signal line 325. When the determination result is notified to the selection unit 323, the selection unit 323 reads a signal according to the determination result from the selection determination unit 322, and the read signal is transferred to the uplink FER measurement unit 305 and the upper station IF 304.

  The signal input to the upper station IF 304 is transmitted to the upper station. Uplink FER measuring section 305 measures the FER of the input signal after selective combining and transmits the received FER to comparing section 306. The comparison unit 306 compares the input received FER with a target FER determined by the system in advance, and when the received FER is lower than the target FER, an instruction to lower the BTS target SIR is received, and the received FER is higher than the target FER. In this case, a target SIR update signal having a meaning of increasing the target SIR of the BTS is input to the control signal creation unit 307. The control signal creation unit 307 converts the target SIR update signal input from the comparison unit 306 into a downlink control signal format, and transmits it to the selection / separation unit 310 via the adder 309.

  FIG. 8 is a diagram showing a block configuration of a target SIR update control unit in the base station control station. The target SIR update control unit 350 includes a selection / synthesis unit interface 351, a main path estimation unit 360, and an interface 353 to a selection / separation unit as shown in FIG. 8, and these are connected by an internal bus 354. The selection determination result signal input by the selection combining unit 320 is input via the selection combining unit interface (IF 351) and transferred to the main path estimation unit 360.

FIG. 10 is a flowchart showing a means for estimating a main path in base station control. The main path estimation unit 360 estimates the main path using a flowchart as shown in FIG.
When a selection determination result signal is input via the selection synthesis unit IF351, first, the process proceeds to step 361, where it is determined whether or not the selected signal is a BTS_A100 signal. If it is determined that the signal is a signal of BTS_A100, the process proceeds to step 362, the ratio of selecting the signal of BTS_A100 is measured, and the process proceeds to step 363. In step 363, it is determined whether or not the result measured in step 362 is equal to or greater than a prescribed threshold th. If it is determined that the determination result is greater than or equal to th, the process proceeds to step 364, where it is determined that the main path is a communication path from the BTS_A 100. If it is determined that the result determined in step 363 is less than th, the process proceeds to step 367 and it is determined that the main path is not applicable.

  On the other hand, when it is determined in step 361 that the selection signal is a signal received from BTS_B200, the process proceeds to step 365, and the ratio of selection of the reception signal of BTS_B200 is measured. Next, the process proceeds to step 366, and if it is determined that the result measured in step 365 is equal to or greater than the prescribed threshold th, the process proceeds to step 368, where it can be determined that the main path is a communication path from BTS_B200. If it is determined that the determination result in step 366 is less than the prescribed threshold th, the process proceeds to step 367, where it is determined that the main path is not applicable.

  After the determination of the main path is determined by steps 364, 367, and 368, the process proceeds to step 369, where it is determined whether it is the target SIR update time, and if it is the update time, the process proceeds to step 370 and the selection separation unit IF353 is set. To the selection / separation unit 310. If it is determined that the determination in step 369 is not the target SIR update time, the selection separation unit 310 is not notified and the process ends.

  In the selection / separation unit 310, the downlink signal input from the higher-level station IF 308 is duplicated and transmitted to all BTSs during handover. The control signal carrying the target SIR update signal is notified from the control unit 350. A BTS to be transmitted is selected based on the signal. When the control unit 350 notifies that the communication path via the BTS_A100 is the main path, the control signal carrying the target SIR update signal is transmitted only to the signal connected to the BTS_A100 and not transmitted to the BTS_B200. . If the control unit 350 notifies that there is no main path, it transmits to all BTSs in the handover. The downlink signal transmitted from the selection / separation unit 310 to the SW 302 is transmitted to each BTS via the LIFs 301a to 301n.

  The downlink signal transmitted from the BSC 300 is input to the downlink information unit 111 via the downlink LIF 110 of BTS_A100 and BTS_B200. The downlink information unit 111 extracts the control signal from the downlink signal and transfers it to the control unit 150.

Next, the base station will be described.
FIG. 6 is a diagram illustrating a block configuration of a control unit in the base station. The control unit 150 includes an information unit IF153, a target SIR control unit 160, a comparator IF151, and a timer 154 as shown in FIG. 6, and the control signal input from the downlink information unit 111 is sent to the target SIR via the information unit IF153. Input to the control unit 160.

FIG. 9 is a flowchart for realizing the target SIR update control in the base station. The target SIR control unit 160 performs control according to this flowchart.
First, in step 161, it is determined whether a control signal is input. If a control signal is input from the information unit IF 153, the process proceeds to step 162, the timer value is reset, and the process proceeds to step 163. In step 163, the target SIR is increased or decreased according to the instruction of the control signal. Next, the routine proceeds to step 164, where the updated target SIR is instructed to the comparator 109 via the comparator IF151, and the processing is completed. On the other hand, if it is determined in step 161 that there is no control signal, the process proceeds to step 165, where it is determined whether or not the timer value exceeds the specified time Th. When it is determined that the determination result does not exceed the specified time Th, the process returns to step 161. If it is determined that the determination result exceeds the specified time Th, the process proceeds to step 166 and the target SIR is changed to an initial set value. Thereafter, the process proceeds to step 164 to notify the comparator and the process ends.

  Next, when the radio channel quality between the BTS_A 100 and the MS 400 is good, the radio channel quality rapidly decreases due to an obstacle entering the radio channel between the BTS_A 100 and the MS 400. The operation will be described. FIG. 3 is a graph showing transmission power control according to the second embodiment to which the present invention is applied. 3A is a graph showing the transmission power of the MS 400, FIG. 3B is a graph showing the target SIR and reception SIR of the BTS_A 100 and BTS_B 200, and FIG. 3C is a graph showing the reception FER at the BSC. .

  Times t0 to t2 are when the radio channel quality between the BTS_A 100 and the MS 400 is good. When the MS 400 performs closed loop transmission power control based on the transmission power control signal of the BTS_A 100, the reception SIR 603 at the BTS_A 100 converges to the target SIR 602, but the reception SIR 605 at the BTS_B 200 becomes lower than the target SIR 604.

  Since the reception FER 608 at t1 is better in quality than the target FER 607, when the BSC 300 determines that the communication path from the BTS_A 100 is the main path, the target SIR update signal at t1 is an instruction to lower the target SIR only. Send to. When receiving the target SIR update signal from the BSC 300, the control unit 150 of the BTS_A 100 lowers the target SIR according to the content. In BTS_B200, as shown in the time t1 to t2, the control signal does not reach even after t1, and therefore, in the processing in the target SIR control unit 160, the timer value becomes the predetermined time Th in the determination of step 165 in FIG. The target SIR is changed to the initial set value 609.

  When the target SIR 602 in the BTS_A 100 decreases, the reception SIR 603 at t1 becomes higher than the target SIR. Therefore, the transmission power 601 of the MS 400 is lowered by the closed loop transmission power control, and the reception SIR 603 converges to the target SIR 602. Further, the reception FER at the BSC 300 also converges to the target FER 607.

  Next, if an obstacle enters between the radio channels between the BTS_A 100 and the MS 400 after t2, and the radio channel quality deteriorates, the reception SIR 603 at the BTS_A 100 rapidly decreases. Along with this, the reception FER 608 of the BSC 300 also deteriorates rapidly, and the transmission power of the MS 400 increases the transmission power by closed-loop transmission power control. When the reception SIR 603 of the BTS_A 100 becomes lower than the reception SIR 605 of the BTS_B 200, the signal selected by the selection combining unit of the BSC 300 changes from the signal via the BTS_A 100 to the signal via the BTS_B 200, and the increase of the reception FER 608 stops. In MS400, the closed loop transmission power control is changed from the transmission power control signal of BTS_A100 to the control based on the transmission power control signal of BTS_B200, and the transmission power is increased toward the target SIR of BTS_B200 that is already at the initial setting value. Let By this operation, the time exceeding the call release FER 606 is shortened, so that synchronization is not lost and call release does not occur.

  Normally, the initial setting value 609 of the target SIR is set so that the reception FER of the BSC 300 is higher than the target FER when the reception SIR converges to the target SIR. After t3, the target SIR update control and the closed loop transmission power control operate so as to converge to the target FER 607 of the BSC 300. Also, if the radio link between the BTS_A 100 and the MS 400 remains lowered, the BSC 300 determines that the main path at t4 is a communication path from the BTS_B 200, and the BTS_A 100 sets the target SIR 602 to the initial setting value of the BTS_A 100. change.

  By the above operation, the time when the quality of the target FER is not satisfied can be shortened. The specified time Th can be set to a value larger than the SIR update cycle T, for example. In addition, the initial setting value of the target SIR is appropriately set to a value that is high enough to allow sufficient call connection, an experience value / setting value corresponding to the infrastructure / environment / system installation status, a value lower than the maximum value that the MS can output, etc. Can be set.

(3) Description of Embodiment 3 Next, Embodiment 3 will be described. The system to which the present invention is applied is the same as that shown in FIG. 1, and the MS 400 and the BSC 300 are the same as the conventional apparatus. FIG. 11 shows a block configuration diagram of the BTS used in the third embodiment.

  A characteristic configuration of the BTS is mainly in the control unit 170 that performs update control of the target SIR. After measuring the SIR of the upstream signal by the upstream channel SIR measurement unit 108, the reception SIR is transferred to the comparator 109 and the control unit 170. The comparator 109 is the same as the operation described in the second embodiment.

  FIG. 12 is a diagram illustrating a block configuration of a control unit in the base station in the third embodiment. The control unit 170 includes an SIR measurement unit IF 172 having an interface with the uplink channel SIR measurement 108, an interface 171 with the comparator 109, a target SIR control unit 180 for controlling the target SIR update, and an interface with the downlink information unit 111. And an information unit IF 173 that is connected to each other via an internal bus 175.

  The target SIR update control is controlled by the target SIR control unit 180. FIG. 13 is a flowchart for realizing target SIR update control in the base station in the third embodiment. The operation of the target SIR control unit 180 will be described using this flowchart. First, in step 181, a value obtained by subtracting the received SIR input via the SIR measurement unit IF 172 from the current target SIR is obtained as ΔSIR. Next, the process proceeds to step 182 where ΔSIR calculated in step 182 is compared with a predetermined threshold value Xth. If it is determined that the comparison result is smaller than Xth, the process proceeds to step 183 to determine whether or not the information unit IF 173 has a control signal including the target SIR update signal. If it is determined that the control signal is input as a result of the determination, the process proceeds to step 184, and the target SIR is increased or decreased in accordance with the instruction of the target SIR update signal. Next, the process proceeds to step 185, and the result of step 184 is notified to the comparator 109 via the comparator IF 171. If it is determined in step 183 that a control signal has not been input, the process ends. On the other hand, if it is determined that the comparison result in step 182 indicates that ΔSIR is greater than the threshold value Xth, the process proceeds to step 186. In step 186, the target SIR is changed to an initial set value. The initial setting value in this case is not limited to the system initial value, and a value that can maintain sufficient quality can also be set. After the target SIR is changed to the initial setting, the process proceeds to step 185 to notify the comparator 109 and the process ends. In this flow, when ΔSIR exceeds Xth, the target SIR update signal from the BSC 300 is ignored.

  Next, when the radio channel quality between the BTS_A 100 and the MS 400 is good and the radio channel quality is rapidly deteriorated due to an obstacle entering the radio channel between the BTS_A 100 and the MS 400, etc. The operation will be described. FIG. 14 is a graph showing transmission power control in Embodiment 3 to which the present invention is applied. 14A is a graph showing the transmission power of the MS 400, FIG. 14B is a graph showing the target SIR and reception SIR of the BTS_A100 and BTS_B200, and FIG. 14C is a graph showing the reception FER at the BSC 300.

  Times t0 to t2 are when the radio channel quality between the BTS_A 100 and the MS 400 is good. When the MS 400 performs closed loop transmission power control based on the transmission power control signal of the BTS_A 100, the reception SIR 703 at the BTS_A 100 converges to the target SIR 702, but the reception SIR 705 at the BTS_B 200 becomes lower than the target SIR 704.

  Since the reception FER 708 at t1 has better quality than the target FER 707, an instruction to lower the target SIR is transmitted to the BTS_A100 and BTS_B200 in the target SIR update signal at t1. When the control unit 170 of the BTS_A 100 receives the target SIR update signal from the BSC 300, update control of the target SIR is determined in the flowchart of FIG. The value of ΔSIR at step 181 is a small value because the values of the target SIR and the reception SIR are extremely equal. In the determination at step 182, it is determined that the value of ΔSIR is smaller than Xth, the process proceeds to step 183 and step 184, and the target SIR is updated based on the target SIR control signal received from the BSC 300. In this case, the target SIR is decreased and notified to the comparator.

  On the other hand, in the target SIR update control unit 180 of BTS_B200, since there is a difference between the target SIR and the reception SIR, the value of ΔSIR in Step 181 becomes large, and in the determination in Step 182, it is determined that ΔSIR is larger than Xth. The After the determination, the process proceeds to step 186, where the target SIR is changed to the initial set value and notified to the comparator 109.

  When the target SIR 702 at the BTS_A 100 decreases, the reception SIR 703 at t1 becomes higher than the target SIR. Therefore, the transmission power 701 of the MS 400 is lowered by the closed loop transmission power control, and the reception SIR 703 converges to the target SIR 702. Further, the reception FER 708 in the BSC 300 converges to the target FER 707.

  Next, assuming that the radio channel quality is degraded due to an obstacle entering the radio channel between the BTS_A 100 and the MS 400 after t2, the reception SIR 703 at the BTS_A 100 is rapidly degraded. Along with this, the reception FER 708 of the BSC 300 also deteriorates rapidly, and the transmission power of the MS 400 increases the transmission power by closed loop transmission power control. When the reception SIR 703 of the BTS_A 100 becomes lower than the reception SIR 705 of the BTS_B 200, the signal selected by the selection combining unit of the BSC 300 changes from the signal via the BTS_A 100 to the signal via the BTS_B 200, and the increase of the reception FER 708 stops. In MS400, the closed loop transmission power control is changed from the transmission power control signal of BTS_A100 to the control based on the transmission power control signal of BTS_B200, and the transmission power is increased toward the target SIR of BTS_B200 that is already at the initial setting value. Let By this operation, the time exceeding the call release FER 706 is shortened, so that synchronization is not lost and call release does not occur.

  Usually, the initial setting value of the target SIR is set so that the reception FER of the BSC 300 is higher than the target FER when the reception SIR converges to the target SIR. After t3, the target SIR update control and the closed loop transmission power control operate so as to converge to the target FER 708 of the BSC 300. If the radio link between the BTS_A 100 and the MS 400 remains lowered, the target SIR 702 of the BTS_A 100 is changed to an initial set value when it is determined that the difference between the target SIR 702 of the BTS_A 100 and the reception SIR 703 exceeds Xth.

  By the above operation, the time when the quality of the target FER is not satisfied can be shortened. Note that the initial setting values of the threshold value Xth and the target SIR can be set as appropriate based on experience values, setting values, and the like according to the infrastructure, environment, and system setting status.

(4) Description of Embodiment 4 Next, Embodiment 4 will be described. The system to which the present invention is applied is the same as that shown in FIG. 1, and the MS 400 and the BTS 100 have the same configuration as that of a conventional apparatus. FIG. 15 shows a block configuration diagram of the BSC 300 used in the fourth embodiment.

  A feature of the BSC 300 is that the target SIR update control is performed independently for each BTS. More specifically, uplink signals from the BTS 100 and BTS 200 during handover are input to the BSC 300 via the LIF 301a and the LIF 301n. The input uplink signal is exchanged by the SW 302 and transferred to the selection combining unit 380 and the uplink FER measurement unit 381 through the signal line 324a and the signal line 324n. The signals input to the selection combining unit 380 are selectively combined and transferred to the upper station. On the other hand, the uplink FER measurement unit 381 measures the FER of each input uplink signal and transfers the FER to the comparator 382. The comparator 382 compares the FER input from the uplink FER measurement unit with the target FER specified by the control unit for each signal, and if the received FER is lower than the target FER, the BTS target When the received FER is higher than the target FER, an instruction to lower the SIR is transmitted to the control signal creation unit 383, which is a target SIR update signal having the meaning of an instruction to raise the target SIR of the BTS. The control signal generation unit 383 converts the target SIR update signal input from the comparison unit into a downlink control signal format, and adds a signal corresponding to each BTS to a signal connected to each BTS via adders 384a and 384n. Inserted.

  Next, when the radio channel quality between the BTS_A 100 and the MS 400 is good and the radio channel quality sharply deteriorates due to an obstacle entering between the radio channels between the BTS_A 100 and the MS 400, etc. The operation will be described. FIG. 16 is a graph showing transmission power control in Embodiment 4 to which the present invention is applied. 16A shows the transmission power of the MS 400, FIG. 16B shows the target SIR and reception SIR of the BTS_A 100 and BTS_B 200, and FIG. 16C shows the signal received from the BTS_A 100 in the BSC 300 from the FER 759 and the BTS_B 200. 6 is a graph showing the FER 761 of the selected signal and the FER 758 after selective synthesis.

  Times t0 to t2 are when the radio channel quality between the BTS_A 100 and the MS 400 is good. When the MS 400 performs closed loop transmission power control based on the transmission power control signal of the BTS_A 100, the reception SIR 753 at the BTS_A 100 converges to the target SIR 752, but the reception SIR 755 at the BTS_B 200 is lower than the target SIR 754.

  Since the FER 759 via the BTS_A100 at t1 has better quality than the target FER757, an instruction to lower the target SIR is transmitted to the BTS_A100 in the target SIR update signal at t1. On the other hand, since the FER 761 via the BTS_B 200 has a lower quality than the target FER 757, an instruction to increase the target SIR is transmitted to the BTS_B 200 in the target SIR update signal at t1. The same operation is performed at t2.

  Next, considering the case where the quality of the radio channel has deteriorated due to an obstacle entering the radio channel between the BTS_A 100 and the MS 400 after t2, the reception SIR 753 at the BTS_A 100 rapidly decreases. Along with this, the FER 759 of the BTS_A100 is rapidly deteriorated, and the FER 759 of the BTS_A100 in the BSC 300 is also rapidly deteriorated. The transmission power of the MS 400 is increased by the closed loop transmission power control because the reception SIR at the BTS_A 100 is lower than the target SIR.

  When the reception SIR 753 of the BTS_A 100 becomes lower than the reception SIR 755 of the BTS_B 200, the signal selected by the selection combining unit of the BSC 300 changes from the signal via the BTS_A 100 to the signal via the BTS_B 200, and the closed loop transmission power control is performed also in the MS 400. Changes from the transmission power control signal of BTS_A100 to the control based on the transmission power control signal of BTS_B200. With this handover, the MS 400 increases the transmission power to meet the target SIR of the BTS_B 200, thereby reducing the FER 761 of the BTS_B 200. In addition, since the signal to be selected in the BSC 300 is changed, the increase of the FER 758 after the synthesis stops and decreases.

Thus, since the target SIR of BTS_B200 is controlled independently of BTS_A100, if there is a difference between the target SIR and the received SIR, the target SIR is controlled to be increased by the target SIR update control of BSC300. Therefore, even when a handover is suddenly performed, the target SIR is high, so that the FER after synthesis can be rapidly lowered. Since this operation shortens the time exceeding the call release FER 756, loss of synchronization does not occur, and call release does not occur.
By the above operation, the time when the quality of the target FER is not satisfied can be shortened.

1 is a diagram showing a configuration during handover in a cellular mobile communication system to which the present invention is applied. FIG. It is a graph showing transmission power control in Embodiment 1 to which the present invention is applied. It is the graph showing transmission power control of Embodiment 2 to which the present invention is applied. It is a figure showing the block configuration of the base station in Embodiment 2 to which this invention is applied. It is a figure showing the block configuration of the base station control station in Embodiment 2 to which this invention is applied. It is a figure showing the block configuration of the control part in a base station. It is a figure showing the block configuration of the selection synthetic | combination part in a base station control station. It is a figure showing the block configuration of the target SIR update control part in a base station control station. It is a flowchart which implement | achieves target SIR update control in the base station in Embodiment 2 to which this invention is applied. It is a flowchart showing the means to estimate the main path in base station control. It is a figure showing the block configuration of the control part in the base station in Embodiment 3 to which this invention is applied. FIG. 11 is a diagram illustrating a block configuration of a control unit in a base station in a third embodiment. 10 is a flowchart for realizing target SIR update control in a base station in the third embodiment. It is a graph showing transmission power control in Embodiment 3 to which the present invention is applied. It is a figure showing the block configuration of the base station control station in Embodiment 4 to which this invention is applied. It is a graph showing transmission power control in Embodiment 4 to which the present invention is applied. It is a figure showing the structure in the hander in the conventional mobile communication system. It is a graph showing transmission power control in the conventional mobile communication system.

Explanation of symbols

100 base station 300 base station control station 400 mobile station 600 closed loop power control interval τ
601 Transmission power of mobile station 602 Target SIR of base station A
603 Received SIR of base station A
604 Target SIR of base station B
605 Base station B received SIR
606 Call release FER
607 Target FER of base station control station
608 Base station control station receive FER
101 Antenna 102 Circulator 103 Reception Radio Modules 104a to 104n Despreading Circuits 105a to 105n Decoding Unit 106 Uplink Information Unit 107 Uplink LIF
108 Uplink SIR Measurement Unit 109 Comparator 150 Control Unit 110 Downlink LIF
111 Downlink information sections 112a to 112n Encoding sections 113a to 113n Frame creation sections 114a to 114n Spreading circuit 115 Addition circuit 116 Transmission wireless modules 301a to 301n LIF
302 SW
320 Selection combining unit 304 Host station IF
305 Uplink FER measurement unit 306 Base station control station comparator 307 Control signal creation unit 308 Upper station IF
309 Adder 310 Selective separation unit 350 Target DIR update control unit

Claims (1)

Controls a first base station that communicates with a wireless terminal that is handing over by a first path, a second base station that communicates with the wireless terminal by a second path, and the first and second base stations A base station control station, wherein the base station control station sets a target reference quality set in the base station for closed-loop transmission power control between the wireless terminal and the first and second base stations. In a wireless communication system for transmitting a control signal to be controlled to the base station,
The base station control station
A signal quality measurement unit that measures the signal quality of the transmission signal from each base station;
A control signal creating unit that creates a control signal for increasing or decreasing the target reference quality used in transmission power control so that the signal quality measured by the signal quality measuring unit is equal to a predetermined target signal quality;
The signal quality measurement unit measures the quality of the transmission signal from each base station for each base station,
A comparator for comparing the signal quality of the transmission signal for each base station measured by the signal quality measurement unit and the target signal quality;
A control signal for instructing increase / decrease of the target reference quality used in the closed-loop transmission power control so that the signal quality for each base station measured by the signal quality measurement unit is equal to the target signal quality; Create for each base station,
Based on the comparison result of the comparator,
Notifying the base station that the quality of the transmission signal is higher than the target signal quality, a control signal for instructing to reduce the target reference quality,
A base station having a transmission signal quality lower than the target signal quality is notified of a control signal for an instruction to increase the target reference quality;
A radio communication system configured to notify a corresponding base station of a control signal for increasing / decreasing a target reference quality created for each base station.

Images