JP4592662B2 - Radio base apparatus, transmission power control method, and transmission power control program - Google Patents

Description

  The present invention relates to a radio base apparatus, a transmission power control method, and a transmission power control program, and in particular, in a mobile communication system in which a plurality of mobile terminal apparatuses are spatially multiplexed to a radio base station, each terminal that is spatially multiplexed The present invention relates to a radio base apparatus, a transmission power control method, and a transmission power control program that improve reception performance of uplink signals from the apparatus.

  2. Description of the Related Art In recent years, mobile communication systems (for example, Personal Handyphone System: hereinafter referred to as PHS), which are rapidly developing, are divided into a plurality of times by spatially dividing the same time slot of the same frequency in order to improve the frequency utilization efficiency of radio waves. A PDMA (Path Division Multiple Access) system has been proposed that allows a user's mobile radio terminal apparatus (terminal) to be spatially multiplexed to a radio base station (base station).

  In this PDMA system, an adaptive array technology is currently employed. Adaptive array processing accurately extracts a signal from a desired terminal by calculating and adaptively controlling a weight vector consisting of a reception coefficient (weight) for each antenna of the base station based on a signal received from the terminal. It is processing to do.

  Through such adaptive array processing, the uplink signal from the antenna of each user terminal is received by the array antenna of the base station, separated and extracted with reception directivity, and the downlink signal from the base station to the terminal is The data is transmitted from the array antenna with transmission directivity with respect to the terminal antenna.

  Such adaptive array processing is a well-known technique and is described in detail in, for example, Non-Patent Document 1, and therefore, description of its operation principle is omitted here.

In such a spatial multiplex connection using adaptive array technology, radio waves of a plurality of user terminals that are multiplex connected tend to influence each other as interference waves, and in order to maintain a stable spatial multiplex connection, There is always a need to reduce the effects of unwanted interference waves.
Nobuyoshi Kikuma, “Adaptive signal processing by array antenna” (Science and Technology Publishing), pages 35-49, “Chapter 3 MMSE Adaptive Array”

  In a PDMA base station that allows such a spatial multiplex connection, the power ratio (Desired user's power: Desired user's power, hereinafter referred to as DD ratio) of received signals from a plurality of user terminals that are multiplex-connected is consistent with each other. desirable.

  This is because if there is a large difference in the received power from multiple user terminals, the interference cancellation capability of adaptive array processing will not be achieved, and the received signal with the lower received power may be regarded as a reception error. Because there is.

  For this reason, the base station side estimates the uplink received power so that the base station received power values from a plurality of users connected in space multiplexing are as much as possible, and instructs the transmission power value to the terminal based on the result, In response to this, transmission power control has been proposed in which the terminal controls to increase or decrease the uplink transmission power.

  However, the terminal performs uplink transmission power control only after receiving a transmission power value instruction signal from the base station, and the terminal does not voluntarily perform uplink transmission power control. Therefore, if the transmission power value instruction signal from the base station does not reach the terminal due to some error in the downlink from the base station, the terminal cannot adjust the uplink transmission power.

  In addition, in the PDMA base station, uplink power estimation of a plurality of user terminals that are spatially multiplexed is performed, but if the actual received power value is low, the uplink power estimation accuracy may deteriorate due to the influence of noise or the like. Even if the transmission power value is instructed to the terminal using such an inaccurate value, efficient transmission power control is difficult.

  Furthermore, since the propagation environment varies greatly depending on the state of the terminal, that is, whether the user is stationary or moving at high speed, the transmission power control from the base station to the terminal follows a fluctuation in the propagation path environment. Therefore, effective transmission power control is difficult.

  Therefore, an object of the present invention is to provide a radio base apparatus and transmission capable of improving uplink reception performance from a spatially-multiplexed terminal by executing transmission power control in an appropriate manner according to a propagation environment. A power control method and a transmission power control program are provided.

The invention of the radio base apparatus according to claim 1 is a radio base apparatus capable of spatial multiplexing connection with a plurality of terminal apparatuses, and signal processing for transmitting / receiving signals to / from the plurality of terminal apparatuses via the spatial multiplexing connection And a transmission power value for each terminal device so that the received power from the plurality of terminal devices is uniform based on the means and the received power from each of the plurality of terminal devices connected in space. Transmission power instruction means for instructing, transmission control means for controlling the transmission power instruction means to transmit an instruction of the transmission power value until there is a response to the transmission power instruction from all of the plurality of terminal devices, and A terminal device that does not respond is provided with recalculation means for recalculating the transmission power value so that the transmission power value increases .

The invention of the radio base apparatus according to claim 2 is a radio base apparatus capable of spatial multiplexing connection with a plurality of terminal apparatuses, and signal processing for transmitting / receiving signals to / from the plurality of terminal apparatuses via the spatial multiplexing connection based means and, on receiving power from each of the fading rate and a measuring means for measuring a received power, the plurality of terminal devices are spatially multiplexed connection from each of the plurality of terminal devices are spatially multiplexed connection Based on the measured fading speed and the received power, the transmission power instruction means for instructing each terminal device the transmission power value so that the received power from the plurality of terminal devices is uniform. In the radio base apparatus comprising: a transmission frequency adjusting unit that adjusts the number of times the transmission power instruction unit transmits the transmission power value instruction, the transmission frequency adjusting unit is measured by the measuring unit. Been for the fading speed is high terminal device, and performing adjustment so as to shorten the period of transmitting the instruction of the transmission power value.

The invention of a transmission power control program according to claim 3 is a transmission power control program in a radio base apparatus capable of spatial multiplexing connection with a plurality of terminal devices, and is connected to the computer via the spatial multiplexing connection with the plurality of terminal devices. Each terminal device so that the received power from the plurality of terminal devices is uniform based on the step for transmitting and receiving signals and the received power from each of the plurality of terminal devices connected in space A step of instructing the transmission power value, and a step of controlling the transmission power instruction means to transmit the instruction of the transmission power value until there is a response to the transmission power command from all of the plurality of terminal devices. The terminal device that has not made a response is caused to execute a step of recalculating the transmission power value so that the transmission power value increases .

The invention of a transmission power control program according to claim 4 is a transmission power control program in a radio base apparatus capable of spatial multiplexing connection with a plurality of terminal devices, and is connected to the computer via the spatial multiplexing connection with the plurality of terminal devices. a method for transmitting and receiving signals Te, and measuring the fading rate and the received power from each of the plurality of terminal devices are spatially multiplexed connection, received from each of the plurality of terminal devices are spatially multiplexed connection Based on the received power, the step of instructing the transmission power value to each terminal device so that the received power from the plurality of terminal devices is uniform, and based on the measured fading speed and received power, And adjusting the number of times of transmitting the instruction of the transmission power value. The step of, said for the measured fading speed is high terminal device adjusts to shorten the period of transmitting the instruction of the transmission power value.

  Therefore, according to the present invention, it is possible to improve the probability of reception of the transmission power instruction signal at the terminal by continuously transmitting the transmission power instruction signal to the terminal spatially connected to the PDMA base station.

  Furthermore, by measuring the propagation environment and carrying out fine transmission power control adapted to fading and reception power values, it is possible to improve the efficiency of transmission power control and thus improve the uplink reception performance from spatial multiplexing terminals. .

  As described above, according to the present invention, a transmission power instruction signal is continuously transmitted to a terminal that is spatially multiplexed with a PDMA base station, or the propagation environment is measured and finely adapted to the fading and reception power values. By performing the transmission power control, it is possible to improve the efficiency of the transmission power control and to improve the uplink reception performance from the spatial multiplexing terminal.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a conceptual diagram schematically illustrating a state in which two users A and B terminals are spatially multiplexed with a PDMA base station.

  Referring to FIG. 1, it is assumed that terminal 2 of user A and terminal 3 of user B are connected to PDMA base station 1 by spatial multiplexing.

  As described above, in a conventional PDMA base station, a transmission power instruction signal is transmitted to each user terminal so that an uplink signal can be received with almost uniform reception power from any user terminal connected in multiple.

  In FIG. 1, for example, the user B terminal 3 that has received the transmission power instruction signal from the PDMA base station 1 sends back an uplink signal (response) indicating that the transmission power instruction has been received to the base station 1.

  FIG. 2 is a diagram schematically illustrating the principle of transmission power control according to the present invention. More specifically, FIG. 2 is a timing diagram showing an aspect of transmission power control for a certain spatial multiplexing terminal in the PDMA base station. Each block unit in FIGS. 2A and 2B represents one time slot section.

  As shown in FIG. 2, the uplink received power from the terminal is estimated by averaging the instantaneous value (hereinafter referred to as RSSI) of the uplink received power measured at the base station for a certain period (for example, one time slot interval). Is done.

  The present invention detects a change in propagation environment from each terminal, and appropriately controls the mode of transmission power control for each terminal accordingly. When the propagation environment fluctuates, for example, when the fluctuation of the reception coefficient of the propagation path is large, that is, when fading is large (fading speed is fast) or when the distance between the terminal and the base station changes, the received power from the terminal changes There are cases.

  For example, referring to FIG. 2A, the base station control in the case where the base station measures that the uplink RSSI at the base station is low while the fading of the propagation path from a certain terminal is gentle is shown. .

  In this case, since the RSSI is low, the accuracy of the estimation of the uplink received power of the corresponding terminal deteriorates due to the influence of noise or the like. Therefore, in such a case, the RSSI is averaged over a relatively long section (a plurality of slots) in which the influence of noise can be removed, and the uplink received power is estimated. Based on the result, a transmission power instruction value for the terminal is estimated, and a transmission power instruction signal is transmitted.

  Note that if the RSSI averaging interval is lengthened, the transmission frequency of the transmission power instruction signal is reduced. Therefore, if the terminal fails to receive the transmission power instruction signal, the terminal should perform transmission power control over a long period of time. Cannot be performed, and the influence on transmission power control is large. Therefore, when the averaging period of the RSSI is long, the transmission power instruction signal may be continuously transmitted to ensure complete reception by the terminal. In this case, the number of continuous transmissions may be fixed to a predetermined number. In addition, when a response indicating that the transmission power instruction signal has been received is returned from the terminal or all terminals spatially multiplexed to the base station, the continuous transmission of the terminal power control signal is terminated. May be.

  On the other hand, referring to (B) of FIG. 2, the base station control when the received power value RSSI from a certain terminal is large, but the base station has measured that the propagation environment changes, that is, fading and power fluctuations are severe. Show.

  In this case, the period of transmission power control is shortened in order to improve the followability of transmission power control to propagation environment fluctuations. That is, as shown in FIG. 2A, when the fluctuation (fading) of the propagation environment is small, the transmission power control effect can be obtained even in a transmission control period of about once per second, for example. When the fluctuation is large, the transmission power control cycle is shortened about once every several milliseconds. For this reason, the RSSI averaging period is shortened (one time slot section in the example of (B)), and the transmission power instruction signal is transmitted more frequently (the transmission power control cycle is set to every other slot).

  However, in this case, since the averaging interval is short, it is conceivable that the error of the uplink power estimation value becomes large. Therefore, the transmission power value that is actually instructed to the terminal may be set and instructed so that the absolute value of the amount of change calculated to increase or decrease from the current transmission power value is slightly reduced. . For example, even if a calculation result instructing the terminal to lower the transmission power by 10 dB from the current value is obtained based on the estimated uplink power value, it is actually instructed to reduce it by 8 dB in order to reduce the influence of the error. What should I do? On the other hand, even if a calculation result instructing to increase the transmission power by 10 dB is obtained, it may be instructed to actually increase the transmission power by 8 dB.

  Next, FIG. 3 is a schematic block diagram showing a configuration of PDMA base station 1000 according to the embodiment of the present invention for performing the transmission power control described with reference to FIG.

  Referring to FIG. 3, PDMA base station 1000 includes a plurality of antennas, for example, array antennas including antennas 11 and 12.

  The antennas 11 and 12 are connected to the radio units 21 and 22, respectively. The radio units 21 and 22 have exactly the same configuration, and only the configuration of the radio unit 21 is shown and described.

The radio unit 21 includes a switch 110, a transmission unit 111, a reception unit 112, and a D / A
A converter 113 and an A / D converter 114 are provided.

  At the time of reception, the switch 110 is switched so that a signal received by the antenna 11 is given to the reception unit 112. The received signal given to the receiving unit 112 is subjected to various analog signal processing such as amplification and frequency conversion, converted into a digital signal by the A / D converter 114, and given to the user signal processing unit 50. .

  The user signal processing unit 50 separates and extracts each user's signal by adaptive array processing described later. The separated received signal of each user is given to a normal modem unit 60 and baseband processing and TDMA / TDD processing unit 70, where necessary demodulation processing and time division processing are performed, and restored to the original signal. It is supplied to the public line network 90.

  On the other hand, at the time of transmission, the transmission signal given from the public line network 90 is given to the baseband processing and TDMA / TDD processing unit 70 and the modem unit 60, and necessary time division processing and modulation processing are performed, and user signal processing is performed. Given to part 50.

  In the user signal processing unit 50, downlink transmission directivity is controlled by adaptive array processing, and is converted into an analog signal by the D / A converter 113 of the radio unit 21.

  The transmission signal converted into the analog signal is subjected to various analog signal processing necessary for wireless transmission, such as amplification and frequency conversion, in the transmission unit 111.

  At the time of transmission, the switch 110 is switched so as to connect the transmission unit 111 and the antenna 11, and the transmission signal wirelessly processed by the transmission unit 111 is transmitted from the antenna 11.

  Similar processing is executed via the wireless unit 22.

  The PDMA base station 1000 of FIG. 3 includes a control unit / transmission power instruction value calculation unit 80 which is a characteristic part of the present invention, and includes a user signal processing unit 50, a modem unit 60, baseband processing, and TDMA / TDD. Based on information from the processing unit 70, transmission power control for each user, in particular, a transmission power instruction value is calculated and the result is given to the user signal processing unit 50. The operation of the control unit / transmission power command value calculation unit 80 will be described later.

  The processes of the user signal processing unit 50 and the control unit / transmission power instruction value calculation unit 80 shown in FIG. 3 are actually realized by software using a digital signal processor (DSP) of the base station.

  FIG. 4 is a functional block diagram showing a configuration of the user signal processing unit 50 shown in FIG. 3 realized by a DSP. The user signal processing unit 50 includes a user A signal processing unit 51, a user B signal processing unit B 52, and a user RSSI computer 53.

  The user A signal processing unit 51 and the user B signal processing unit 52 have exactly the same configuration, and only the configuration of the user A signal processing unit 51 will be illustrated and described.

  A digital reception signal x1 (t) given from the reception unit 112 of the wireless unit 21 corresponding to the antenna 11 of FIG. 3 via the A / D converter 114 and a reception unit (not shown) of the wireless unit 22 corresponding to the antenna 12 A digital received signal x2 (t) given from an A / D converter (not shown) is commonly given to the user A signal processing unit 51 and the user B signal processing unit 52.

  Hereinafter, the processing of these digital signals given to the user A signal processing unit 51 will be described. These signals given to the user A signal processing unit 51 are subjected to adaptive array processing in software by a DSP (not shown) of the base station 1000 according to the functional block diagram shown in FIG.

  Referring to FIG. 4, the received signal vector composed of two systems of digital received signals x1 (t) and x2 (t) given from radio sections 21 and 22 to user A signal processing section 51 is represented by multipliers MR1 and MR2. And a reception weight vector calculator 51c and a reception response vector estimation unit / fading speed estimation unit 51d.

  On the other hand, the reception weight vector calculator 51c calculates a weight vector composed of the weight for each antenna by an adaptive array algorithm, and supplies the weight vector to the other input of each of the multipliers MR1 and MR2, and the received signal vector from the corresponding antenna, respectively. Complex multiplication. The adder AD1 obtains an array output signal y1 (t) that is the sum of the complex multiplication results.

  The array output signal as a result of the complex multiplication sum as described above is re-modulated to the reception signal S1 (t) of the user A by the determination unit 51a, and is then separated and extracted as the reception signal from the user A of FIG. In addition to being supplied to the modem unit 60, it is provided to the reception weight vector calculator 51c and the reception response vector estimation unit / fading speed estimation unit 51d. Similarly, from the user B signal processing unit 52, the separated received signal from the user B is supplied to the modem unit 60.

  The reception weight vector calculator 51c is a known reference signal output from the memory 51b during a predetermined reference signal period according to an instruction from the determination unit 51a (for example, a preamble (PR) composed of a known bit string and a unique word in PHS). (UW)) and the received signal S1 (t) given from the determination unit 51a after the end of the reference signal period, a known adaptive array such as an RLS (Recursive Least Squares) algorithm or an SMI (Sample Matrix Inversion) algorithm. A reception weight vector is calculated by an algorithm.

  Such RLS algorithm and SMI algorithm are well-known techniques in the field of adaptive array processing, and as described above, from No. 35 of "Adaptive signal processing by array antenna" (Science & Technology Publishing) by Nobuyoshi Kikuma. Since it is described in detail in “Chapter 3 MMSE Adaptive Array” on page 49, the description thereof is omitted here.

  On the other hand, the reception response vector estimator / fading speed estimator 51d receives the user A based on the received signal S1 (t) of the user A signal processor 51 and the received signal S2 (t) of the user B signal processor 52. The reception coefficient of the received signal propagation path, that is, the reception response vector is estimated, and the fading speed of the user A is estimated based on the estimation result.

  More specifically, the reception response vector estimator / fading speed estimator 51d uses a known algorithm to receive signal vectors x1 (t) and x2 (t) received by the two antennas 11 and 12, and an adaptive array. The product of the received signals S1 (t) and S2 (t) of the users A and B extracted and remodulated by the process is ensemble averaged (time average) over a predetermined time, thereby calculating the reception response vector of each user.

  The magnitude of fading (fading speed) in the propagation environment is represented by the Doppler frequency fD, and is estimated as follows, for example. That is, the correlation value of two reception response vectors that are temporally mixed in the user reception signal extracted by adaptive array processing is calculated. If there is no fading, the two received response vectors match and the correlation value is 1. On the other hand, if fading is severe, the difference in the reception response vector becomes large and the correlation value becomes small. If the relationship between the correlation value of the reception response vector and the Doppler frequency fD is experimentally obtained in advance and the table is stored in the memory, the correlation value of the reception response vector is calculated, and the Doppler at that time is calculated. The frequency fD can be estimated.

  The fading speed of user A estimated by the reception response vector estimation unit / fading speed estimation unit 51d is given to the control unit / transmission power command value calculation unit 80 in FIG. In addition, the user A signal processing unit 51 reception response vector estimation unit / fading speed estimation unit 51d estimates the user A reception response vector H1, and the user B signal processing unit 52 reception response vector estimation unit / fading speed (not shown). The reception response vector H2 of the user B estimated by the estimation unit is given to the user RSSI calculator 53, and the user RSSI calculator 53 calculates the RSSI for each user by a known algorithm based on these reception response vectors. Then, it is given to the control unit / transmission power command value calculation unit 80 in FIG.

  Although not shown in FIG. 4, the transmission signal from the modem unit 60 in FIG. 3 is weighted by complex multiplication with the transmission weight vector in each of the user A signal processing unit 51 and the user B signal processing unit 52. The two digital transmission signals are combined and supplied to the radio units 21 and 22, respectively. Digital transmission signals given to the radio units 21 and 22 are transmitted via the antennas 11 and 12, respectively.

  Since signals transmitted via the same antennas 11 and 12 as at the time of reception are weighted by a weight vector targeting a specific terminal in the same manner as the received signals, radio signals transmitted from these antennas are Therefore, it is skipped with transmission directivity targeting this specific terminal.

  3 is the user signal processing unit 50, the modem unit 60, the baseband processing and the TDMA / TDD processing unit in the manner described in relation to FIG. Based on information from 70, transmission power control including calculation of a transmission power instruction value for each user is executed, and a signal for instructing transmission power to each user is described in a manner described below. 4 is sent to a transmission system circuit (not shown) of each user signal processing unit and transmitted to a corresponding user terminal via a corresponding radio unit.

  Next, FIG. 5 is a flowchart showing a basic operation of transmission power control executed by the DSP (particularly, the control unit / transmission power command value calculation unit 80 of FIG. 3) of the PDMA base station of FIG.

  First, in step S1, based on the estimated uplink received power, a transmission power instruction value for each terminal that is spatially multiplexed with the PDMA base station is calculated.

  Next, in step S2, the calculated transmission power instruction value is transmitted from the base station to the terminal.

  Then, in step S3, it is determined whether or not the base station has received an uplink response signal indicating that the transmission power instruction signal has been received from all terminals. If there is still no response from all the terminals, the process proceeds to step S4, and for the terminal that has responded, as shown in FIG. 2, the uplink received power is newly estimated (RSSI averaging). The transmission power instruction value is recalculated (for example, it is preferable to decrease the instruction value), and the process returns to step S2 to transmit a new transmission power instruction value to the terminal.

  Here, it is preferable to recalculate the transmission power instruction value to the terminal that has responded so that the reception condition of the terminal that has not responded is restored and the performance between terminals is uniform. This is because it can be realized.

  On the other hand, if there is a response from all the terminals in step S3, the process proceeds to step S5, and the transmission of the power instruction signal is terminated.

  Next, FIG. 6 shows the embodiment of the present invention described in relation to FIG. 2 executed by the DSP of the PDMA base station of FIG. 3 (particularly, the control unit / transmission power command value calculation unit 80 of FIG. 3). It is a flowchart explaining the continuous transmission operation | movement by.

  For example, as described with reference to FIG. 2A, there is a case where the transmission power instruction signal is continuously transmitted from the base station in order to increase the probability of reception of the transmission power instruction signal at the terminal. FIG. 6 illustrates the continuous transmission operation of such a transmission power instruction signal.

  Referring to FIG. 6, first, in step S11, based on the estimated uplink received power, a transmission power instruction value for each terminal that is spatially multiplexed with the PDMA base station is calculated.

  Next, in step S12, the calculated transmission power instruction value is transmitted from the base station to the terminal.

  Then, in step S13, it is determined whether or not the base station has received an uplink response signal indicating that the transmission power instruction signal has been received from all terminals. If there is still no response from all the terminals, the process proceeds to step S14, and it is determined whether or not the number of continuous transmissions of the transmission power instruction signal has reached a preset number.

  If the number of times of continuous transmission is not greater than or equal to the set value, the process returns to step S12 and continues to transmit the transmission power instruction signal. At this time, for a terminal having no response, control may be performed to increase downlink transmission power when a transmission power instruction signal is transmitted to the terminal.

  If it is determined in step S13 that there is a response from all terminals, or if it is determined in step S14 that the number of continuous transmissions is equal to or greater than the set value, the process proceeds to step S15. Then, the transmission of the power instruction signal is terminated.

  Next, FIG. 7 shows the embodiment of the present invention described with reference to FIG. 2 executed by the DSP of the PDMA base station of FIG. 3 (particularly, the control unit / transmission power command value calculation unit 80 of FIG. 3). It is a flowchart explaining the transmission power control adapted to the propagation environment by the.

  In the present invention, for example, as described with reference to FIGS. 2A and 2B, transmission power control suitable for a propagation environment such as fading and reception power is performed. FIG. Such a transmission power control operation will be described.

  First, in step S21, it is assumed that information such as the number of RSSI averaging sections and the number of times of continuous transmission of the transmission power instruction signal is held in advance as default values at the start of a call. When a call is started between the PDMA base station and the spatial multiplexing terminal, in step S22, the reception response vector estimation unit / fading rate estimation unit 51d and the user RSSI computer 53 shown in the functional block diagram of FIG. The fading speed of the user and the user RSSI are measured.

  Next, in step S23, it is determined based on the measured user RSSI whether the received power is low.

  If it is determined in step S23 that the received power is low, the process proceeds to step S24, and the RSSI averaging section is lengthened as described in relation to FIG.

  In step S25, the transmission power instruction value calculated after the RSSI averaging is continuously transmitted to the terminal as many times as possible. This continuous transmission may be performed according to the flowchart shown in FIG.

  On the other hand, if it is determined in step S23 that the received power is low, the process proceeds to step S26 to determine whether or not the measured fading speed is high.

  If it is determined in step S26 that fading is fast, the process proceeds to step S27 to shorten the RSSI averaging section as described in connection with FIG.

  In step S28, in order to eliminate the influence of the error, an instruction value obtained by multiplying the calculated transmission power instruction value (change amount of transmission power) by 0.8 is transmitted to the terminal as an actual transmission power instruction value. .

  On the other hand, if it is determined in step S26 that fading is not fast, the process is terminated.

  In addition, in step S25 of FIG. 7, when it is necessary to transmit other information to the terminal while the power instruction value is continuously transmitted, the continuous transmission is stopped and the information is transmitted with priority. You may comprise.

  Further, in step S28 of FIG. 7, the coefficient to be multiplied by the calculated power instruction value (change amount of transmission power) does not need to be fixed as 0.8, and can be appropriately changed depending on the fading speed and the user RSSI. It may be.

  For example, 0.5 may be applied when RSSI is low, and 0.8 may be applied when RSSI is high, or 0.8 may be applied when fading speed is high, and 0.5 may be applied when slow.

  Note that the averaging of RSSI as shown in FIG. 2 is initialized when a response from the terminal is returned.

  Alternatively, a moving average technique that prioritizes the latest information by weighting may be used for averaging the RSSI.

  That is, when time is represented by n, the new average at n + 1 is expressed as follows.

average (n + 1) = λ * average (n) + (1-λ) * instant USER_RSSI (n)
Here, the larger the λ, the longer the averaging time, and the smaller the value, the higher the instantaneous value.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a conceptual diagram which shows typically the state in which the user terminal is spatially multiplexed with the PDMA base station. FIG. 3 is a timing diagram schematically illustrating the principle of transmission power control according to the present invention. It is a schematic block diagram which shows the structure of the PDMA base station by embodiment of this invention. It is a functional block diagram which shows the structure of the user signal processing part shown in FIG. It is a flowchart which shows the basic operation | movement of the transmission power control performed by the PDMA base station. FIG. 6 is a flowchart showing a continuous transmission operation according to an embodiment of the present invention executed by a PDMA base station. FIG. 5 is a flowchart showing transmission power control executed by a PDMA base station according to an embodiment of the present invention.

Explanation of symbols

1 PDMA base station, 2, 3 user terminals, 11, 12 antennas, 21, 22 radio unit, 50 user signal processing unit, 51 user A signal processing unit, 52 user B signal processing unit, 51a determination unit, 51b memory, 51c Reception weight vector calculator, 51d reception response vector estimation unit / fading speed estimation unit, 53 user RSSI computer, 60 modem unit, 70 baseband processing and TDMA / TDD processing unit, 80 control unit / transmission power instruction value calculation unit, 90 public Circuit network, 110 switch, 111 transmitter, 112 receiver, 113 D / A converter, 114 A / D converter, 1000 PDMA base station, MR1, MR2, MT1, MT2 multiplier, AD1 adder.

Claims (4)

A wireless base device capable of spatial multiplexing connection with a plurality of terminal devices,
Signal processing means for transmitting and receiving signals to and from the plurality of terminal devices via a spatial multiplexing connection;
Based on the received power from each of the plurality of terminal devices connected in space, the transmission for instructing the transmission power value to each terminal device so that the received power from the plurality of terminal devices is uniform. Power instruction means;
Transmission control means for controlling the transmission power instruction means to transmit an instruction of the transmission power value until there is a response to the transmission power instruction from all of the plurality of terminal devices;
A radio base apparatus comprising: a recalculation unit that recalculates a transmission power value such that the transmission power value is increased for a terminal device that has not responded. A wireless base device capable of spatial multiplexing connection with a plurality of terminal devices,
Signal processing means for transmitting and receiving signals to and from the plurality of terminal devices via a spatial multiplexing connection;
Measuring means for measuring fading speed and received power from each of the plurality of terminal devices connected in space, and
Based on the received power from each of the plurality of terminal devices are spatially multiplexed connection, the received power from the plurality of terminal devices to be uniform, indicating transmission power values for each terminal A transmission power instruction means;
In a radio base apparatus comprising: a transmission number adjusting unit that adjusts the number of times the transmission power instruction unit transmits an instruction of a transmission power value based on the measured fading speed and received power.
The radio base characterized in that the transmission frequency adjusting means adjusts the terminal device having a large fading speed measured by the measuring means so as to shorten a cycle of transmitting the transmission power value instruction. apparatus. A transmission power control program in a radio base device capable of spatial multiplexing connection with a plurality of terminal devices,
A step of transmitting and receiving signals to and from the plurality of terminal devices via a spatial multiplexing connection;
Instructing each terminal device of a transmission power value based on the received power from each of the plurality of terminal devices connected in space, so that the received power from the plurality of terminal devices is uniform. When,
Controlling the transmission power instruction means to transmit an instruction of the transmission power value until there is a response to the transmission power instruction from all of the plurality of terminal devices;
A transmission power control program for causing a terminal device that has not responded to execute a step of recalculating a transmission power value so that the transmission power value is increased . A transmission power control program in a radio base device capable of spatial multiplexing connection with a plurality of terminal devices,
Transmitting and receiving signals to and from the plurality of terminal devices via a spatial multiplex connection;
Measuring fading speed and received power from each of the plurality of terminal devices spatially connected;
Based on the received power from each of the plurality of terminal devices are spatially multiplexed connection, the received power from the plurality of terminal devices to be uniform, indicating transmission power values for each terminal Steps,
In the transmission power control program for executing the step of adjusting the number of times to transmit the indication of the transmission power value based on the measured fading speed and received power,
The step of adjusting the number of times of transmission includes adjusting the transmission power so as to shorten the cycle of transmitting the instruction of the transmission power value for the terminal device having a large measured fading speed. Control program.

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