JP4276053B2 - Transmission power control method - Google Patents

Description

The present invention relates to a DS-CDMA (Direct-Direct Communication) that assumes so-called transmission power control in which a transmission / reception station adjusts transmission power from the opposite station so that reception quality from the opposite station is constant.
The present invention relates to a transmission power control method in a mobile communication system, and more particularly to a transmission power control method that can reduce deterioration of reception quality due to parasitic vibration.

In mobile communication systems, various methods of multiple access have been devised as methods for effectively using resources such as limited frequencies.
A method called Division Multip1e Access (spreading code division multiple access) method is generally known.
In the CDMA system, individual spreading codes are assigned and multiplexed for each communication channel, and pilot symbols are inserted into transmission symbols for transmission. On the receiving side, amplitude and phase fluctuations are extracted from the despread signals of the pilot symbols. DS-CDMA (Direct
The Sequence Code Division Multiple Access (direct sequence code division multiple access) method is frequently used.

However, in the mobile communication system as described above, there is a problem that a signal wirelessly transmitted from a certain transmission station and a signal wirelessly transmitted from another transmission station interfere with each other. In order to solve such a problem, transmission power control has been conventionally performed as an interference reduction method in digital mobile communication.
Transmission power control includes open loop control and closed loop control. Among these, closed loop control is a transmission power control command (Transmit control) at a known timing of a fixed period based on a signal received by a communication data receiving station.
A power control command (hereinafter referred to as TPC) bit is inserted into a signal to a communication data transmission station, and the communication data transmission station receiving the bit controls the current transmission power in steps of ± several dB. By the above control method, it is ensured that the signal transmitted from the transmission station of the communication data is received by the receiving station with the same intensity, and interference can be prevented.
The DS-CDMA method employs closed loop control as a transmission power control method.

    Further, as a conventional device for performing transmission power control by closed loop control, Japanese Patent Application Laid-Open No. 10-242905 published on September 11, 1998, “staged transmission power control circuit” (Applicant: Hitachi Kokusai Electric, Inc.) : Tokuhiro Hattori et al. (Hereinafter referred to as Patent Document 1) and Japanese Patent Laid-Open No. 2001-69076 “CDMA Base Station Device” published on March 16, 2001 (Applicant: Hitachi Kokusai Electric Inc., Inventor: Kohei Sasaki) (Hereinafter, Patent Document 2) is known.

In Patent Document 1, the gain indicated by the TPC bit is output as a count output of a predetermined number of bits corresponding to the unit control amount in accordance with the control timing of the TPC bit, and a control voltage corresponding to the count output is output Then, in the step-type transmission power control circuit that changes and amplifies the gain of the signal to be transmitted corresponding to the control voltage, the count output is set to 2 ⁿ (n is a natural number), and unit control in the count output A step-type transmission power control circuit is described in which the amount of phase jump per control amount is kept small by reducing the amount to 1/2 ⁿ and does not cause deterioration of characteristics.
Further, Patent Document 2 multiplies a plurality of spread signals transmitted by a multiplication unit to a plurality of mobile station apparatuses and a transmission power multiplication coefficient based on a determination result of a TPC bit corresponding to each mobile station apparatus. The processing for controlling the power of each spread signal is performed on these multiple spread signals in a time-sharing manner, and the addition means sequentially accumulates a plurality of multiplication results obtained and multiplexes, and the transmission means obtains the multiplexed signal obtained thereby. A CDMA base station apparatus is described in which the circuit configuration can be simplified by transmitting to a mobile station apparatus.

JP 10-242905 A (page 2-3, FIGS. 1 and 2) JP 2001-69076 A (pages 2, 4-7, FIG. 1)

Next, the configuration and operation of a conventional general transmission power control apparatus will be described with reference to FIG. FIG. 4 is a configuration block diagram of a conventional general transmission power control apparatus. The transmission power control apparatus of FIG. 4 is provided in a communication station of the DS-CDMA mobile communication system, and based on the quality of the received signal from the opposite station that is the communication target, Transmission power control is performed.
4 includes a despreading unit 201, a detection unit 202, a determination / decoding unit 203, an SIR measurement unit 204, an insertion TPC generation unit 205, an encoding unit 206, and a frame generation unit. 207, a modulation unit 208, and a spreading unit 209.

Next, the configuration of each unit in FIG. 4 will be described.
The despreading unit 201 performs a correlation operation between a baseband received signal (BB received signal in the figure, hereinafter received signal) received from the opposite station and a reference code (not shown) to despread the baseband received signal. It is something to do.
The detection unit 202 performs transmission path estimation, synchronous detection, and demodulation of the received signal after despreading.
The determination / decoding unit 203 determines a received signal after demodulation from the detection unit 202, performs decoding such as error correction, and extracts received data.

The SIR measurement unit 204 measures the quality of the received signal after despreading, and based on the measurement result, the instantaneous desired signal power to interference signal power ratio (Signal to Interferrence) for each control period.
Ratio: SIR) is obtained and output.
The inserted TPC generation unit 205 compares the instantaneous SIR (in the figure, instantaneous SIR) from the SIR measurement unit 204 with the reference quality (TargetSIR in the figure), and based on the comparison result, as a command for transmission power control for the opposite station The generation TPC is generated and output.

    Specifically, the insertion TPC generation unit 205 outputs a power DOWN insertion TPC if instantaneous SIR> TargetSIR, and outputs a power UP insertion TPC if instantaneous SIR <TargetSIR. Therefore, the relationship between the instantaneous SIR and the output insertion TPC is as shown in FIG. FIG. 5 is an explanatory diagram showing the concept of the insertion TPC output from the insertion TPC generation unit 205 of FIG. As shown in FIG. 5, the insertion TPC is used by negotiating with the opposite station as a system specification, for example, power up when TPC = 1 and power down when TPC = 0.

The encoding unit 206 performs encoding such as error correction on transmission data to be transmitted.
The frame generation unit 207 generates a data frame by time-multiplexing the data encoded by the encoding unit 206, the inserted TPC, the reference signal for synchronous detection, and the like.
The modulation unit 208 modulates the data time-multiplexed by the frame generation unit 207.
Spreading section 209 spreads the modulated signal with a spreading code (not shown), and outputs the modulated signal after the spreading processing as a baseband transmission signal (BB transmission signal in the figure).

Next, the operation of the transmission power control apparatus in FIG. 4 will be described.
First, the received signal from the opposite station is despread by the reference code in the despreading section 201, and the despread received signal is input to the SIR measurement section 204 and the detection section 202, respectively. The detection unit 202 performs demodulation processing such as channel estimation and synchronous detection on the received signal after despreading, and the demodulated signal is determined by the determination / decoding unit 203.
“0” and “1” binary determination or decoding processing is performed, and received data is extracted.

On the other hand, the SIR measurement unit 204 obtains an instantaneous reception SIR in units of transmission power control periods from the received symbols after despreading, and outputs them to the insertion TPC generation unit 207. The instantaneous SIR is compared with the reference quality TargetSIR in the insertion TPC generation unit 207. If the instantaneous SIR> TargetSIR, the power DOWN insertion TPC (TPC = 0) is the instantaneous SIR <TargetSIR, and the power UP is inserted. TPC (TPC = 1) is generated and output to the frame generation unit 207.
The generated and output insertion TPC is time-multiplexed by the frame generation unit 207 together with the transmission data encoded by the encoding unit 206 and the reference signal for synchronous detection. The multiplexed transmission data is subjected to modulation processing in the modulation unit 208, and further subjected to spreading processing using a spreading code in the spreading unit 209 and output as a baseband transmission signal. Thereafter, the baseband transmission signal is wirelessly transmitted to the opposite station.

By the way, in an actual transmission power control apparatus, it is known that a delay (control delay) occurs between the output of the inserted TPC and the transmission power control in the opposite station.
Here, the control delay will be described with reference to FIGS. FIG. 6 is a table showing the relationship between insertion TPC due to control delay and reception SIR, and FIG. 7 is a graph showing the relationship between control delay and reception SIR. 6, FIG. 6A is a table showing a relationship in a time series when there is no delay in the control cycle unit time (hereinafter, control delay), and FIG. 6B is a case where the control delay = 1. 6C is a table showing the relationship in the time series, and FIG. 6C is a table showing the relationship in the case of the control delay = 2 in the time series. 6A to 6C, TargetSIR = 10 dB in all cases, and the power control amount for one TPC (Up, Down) at the opposite station is ± 1 dB.
In addition, the graph of FIG. 7 is a graph display of the reception SIR values in FIGS. 6A to 6C, where the vertical axis represents the reception SIR and the horizontal axis represents the control cycle unit time.

Hereinafter, the control delay state will be described.
First, the state without control delay will be described. As shown in the top column of FIG. 6A, when the reception SIR at the time of control is 9.5 dB, the insertion TPC generation unit 207 generates an UP command as the insertion TPC compared with TargetSIR = 10 dB. The UP command is transmitted to the opposite station.
Then, in the opposite station, control of +1 dB is performed based on the inserted TPC. Therefore, in the next control, as shown in the second column from the left in FIG. 6A, reception SIR = 10.5 dB. At this time, a Down command is generated and output from the inserted TPC generation unit 207 as shown in the shaded portion in the second column from the left in FIG. 6A, and the Down command is transmitted to the opposite station. The Then, in the opposite station, control of -1 dB is performed based on the inserted TPC, and in the next control, as shown in the shaded portion in the third column from the left in FIG. .5 dB.
That is, in the state without the control delay, the transmission power control by the insertion TPC is immediately reflected in the opposite station, and at the next control, the own station can receive the reception signal in which the transmission power control is reflected.

On the other hand, when the control delay = 1 in FIG. 6B, the transmission power control by the insertion TPC is reflected with a delay of one unit time compared to the case without the control delay. For example, the power control by the Down command in the shaded portion in the second column from the left in FIG. 6B is reflected in the received SIR in the fourth shaded portion from the left, and the received SIR decreases by 1 dB.
In the case of the control delay = 2 in FIG. 6C, the transmission power control by the insertion TPC is reflected with a delay of 2 unit time from the case of no control delay. For example, the power control by the Down command in the shaded portion in the second column from the left in FIG. 6C is reflected in the received SIR in the fifth shaded portion from the left, and the received SIR decreases by 1 dB.

Therefore, in the conventional general transmission power control apparatus, when there is a control delay, there is a problem that parasitic vibration is generated due to this and reception characteristics are deteriorated.
The graph of FIG. 6 shows the state of the reception SIR for each control delay. When the control delay = 2, the reception SIR has an error of ± 2 dB or more from the TargetSIR, and the cycle is shorter. Causes a large amplitude fluctuation in the signal line, resulting in degradation of the received signal quality. That is, as the control delay is delayed, the amplitude of the parasitic vibration that occurs regardless of the original received signal increases, and the deterioration of the received signal quality becomes more significant.

In addition, since the measurement result of the instantaneous SIR in the SIR measurement unit 204 actually includes a measurement error, the reception SIR has a larger error (vibration) in addition to the parasitic vibration, and the received signal quality Deteriorates further.
In an actual transmission power control apparatus, it is difficult to eliminate the control delay due to the configuration of the apparatus. Therefore, a transmission power control method or apparatus that can reduce signal quality degradation due to the influence of parasitic vibration is desired.

    The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transmission power control method capable of reducing deterioration in reception quality due to parasitic vibration caused by control delay.

The present invention for solving the problems of the conventional example described above measures the desired signal power to interference signal power ratio of the signal from the opposite station, and based on the comparison result between the measured value and the reference value, the transmission power in the opposite station A transmission power control method for generating or transmitting a power control command for increasing or decreasing each unit period and transmitting it to the opposite station, and controlling the transmission power in accordance with the power control command received at the opposite station. Based on the absolute value of the difference between the power ratio and the reference value, the value of the desired wave power to interference wave power ratio is divided into a plurality of stages, and when the measured value is the first stage closest to the reference value, the unit the measurements in each cycle to generate alternately opposite power control command to the power control commands and the power control commands increases or decreases corresponding to the direction to approach the reference value, far to the measured value most reference value second If this is the stage, For each unit period, an ascending or descending power control command corresponding to the direction in which the measured value approaches the reference value is generated, and when the measured value is a stage excluding the first stage and the second stage, Ascend or descend power control command corresponding to the direction in which the measured value approaches the reference value and the power control command opposite to the power control command, so that the ratio of the former is greater than the latter and is far from the reference value. When the fading frequency in the transmission path is estimated and the estimated fading frequency exceeds the specified value, the first step is performed with the fading frequency lower than the specified value. It is set narrower than the small case .

According to the present invention, the power control command for measuring the desired signal power to interference signal power ratio of the signal from the opposite station and increasing or decreasing the transmission power in the opposite station based on the comparison result between the measured value and the reference value is provided. A transmission power control method for generating a unit period and transmitting it to an opposite station and controlling transmission power according to a power control command received at the opposite station, wherein a difference between a desired signal power to interference signal power ratio and a reference value Based on the absolute value, the value of the desired wave power to interference wave power ratio is divided into a plurality of stages, and when the measured value is the first stage closest to the reference value, the measured value is set as the reference value for each unit period. generate alternately opposite power control commands to the raising or lowering of the power control commands and the power control commands corresponds to the direction to approach, when the measured value is distant second stage gold standard value, the unit Measured value at each cycle as reference value If the measured value is a stage excluding the first stage and the second stage, the measured value is made closer to the reference value for each unit period. The corresponding power control command of rising or falling and the power control command opposite to the power control command are set so that the former ratio is higher than the latter, and the former ratio is higher at a stage farther from the reference value. And the fading frequency in the transmission path is estimated, and when the estimated fading frequency exceeds the specified value, the first stage is set to be narrower than the case where the fading frequency is smaller than the specified value. Since the control method is used, there is an effect that deterioration of reception quality due to parasitic vibration caused by control delay can be reduced.

Embodiments of the present invention will be described with reference to the drawings.
The function realizing means described below may be any circuit or device as long as it can realize the function, and part or all of the function can be realized by software. is there. Furthermore, the function realizing means may be realized by a plurality of circuits, and the plurality of function realizing means may be realized by a single circuit.

    In the transmission power control method according to the embodiment of the present invention, the absolute value of the difference between the desired signal power to interference signal power ratio (received SIR) of the signal from the opposite station and the reference quality is divided into a plurality of stages. Is used as a reception quality window, it is determined which reception quality window the received SIR belongs to, and a predetermined insertion power control command (insertion TPC) is issued for each unit period time corresponding to the reception quality window to which the received SIR belongs. It is generated and inserted into the transmission signal, and deterioration of reception quality due to parasitic vibration caused by control delay can be reduced.

First, the transmission power control method according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram of a transmission power control method according to an embodiment of the present invention.
In the transmission power control method according to the embodiment of the present invention (hereinafter, this control method), the difference between the reference quality (TargetsIR) and the reception quality (reception SIR) is divided into a plurality of stages, and each stage is defined as a reception quality window. It is provided to determine which stage the received SIR belongs to, and the insertion TPC is generated in a prescribed order according to the stage.

    In the conceptual diagram of FIG. 1, the reception quality window is, for example, an area of 3 dB from TargetSIR (area (1) in FIG. 1, hereinafter referred to as the first area, corresponding to the first stage of claims), +3 dB from TargetSIR. To + 5DB, −3 dB to −5 dB region (region (2) in FIG. 1, hereinafter referred to as second region, corresponding to the third stage of claims), other regions (of (3) in FIG. 1) Area, hereinafter referred to as a third area, corresponding to the second stage of claims).

Here, when the instantaneous SIR is in the first region, the insertion TPC is generated by alternately repeating Up and Down. For example, when reception SIR <TargetSIR, insertion TPCs are generated in the order of UP, Down, UP, and Down. When reception SIR> TargetSIR, insertion TPCs are generated in the order of Down, UP, Down, and UP.
When the instantaneous SIR is in the second region, the control insertion TPC approaching the reference quality and the control insertion TPC away from the reference quality are repeated so as to increase the ratio of the control insertion TPC closer to the target quality. An insertion TPC is generated so as to approach For example, when reception SIR <TargetSIR, up, Up, Down, Up, Up, Down in the order of 6 control cycle units, and when reception SIR> TargetSIR, down, Down, Up, up to 6 control cycle units of time. An insertion TPC is generated in the order of Down, Down, and Up.
When there is an instantaneous SIR in the third area, UP is generated as an insertion TPC when reception SIR <Target SIR, and Down is generated as insertion TPC when reception SIR> Target SIR.

Note that the TPC repeating pattern in each of the above regions is merely an example, and the pattern may be changed.
In this control method, the reception quality window has three stages, but the number of stages may be different. At this time, in the reception quality window at the stage closest to the reference quality, the control method in the first area is used. In the reception quality window at the stage farthest from the reference quality, the control method in the third area is used. In other reception quality windows, it is preferable to use the control method in the second area. In particular, it is desirable that the reception quality window for performing the control method in the second region is generated so that the proportion of the control TPC closer to the reference quality increases as the reception quality window at a stage farther from the reference value. .

According to the control method described above, even if there is a control delay, if the reception quality is within the first region, the opposite station receives the inserted TPC in which UP and Down appear alternately, and performs power control. A reception signal having the same quality as that without delay can be obtained.
Moreover, even if the reception quality deviates from the first region due to the influence of the transmission path or the like, the occurrence of parasitic vibration can be prevented as much as possible by performing the gentle transmission power control in the second region described above. When the reception quality is in the third region, the reception quality can be quickly brought close to targetSIR by performing conventional control regardless of the presence or absence of parasitic vibration.
Therefore, according to the present control method, the amplitude of the parasitic vibration generated due to the control delay can be reduced, so that the deterioration of the reception quality due to the parasitic vibration can be reduced.

Next, the configuration of the transmission power control apparatus according to the embodiment of the present invention that performs transmission power control using this control method will be described with reference to FIG. FIG. 2 is a configuration block diagram of the transmission power control apparatus according to the embodiment of the present invention. 2 is provided in the communication station of the DS-CDMA mobile communication system. The transmission power control apparatus shown in FIG. Transmission power control is performed.
A transmission power control apparatus (hereinafter, this control apparatus) according to an embodiment of the present invention includes despreading section 101, detection section 102, determination / decoding section 103, SIR measurement section 104, and insertion TPC generation section. 105, a fading frequency estimation unit 106, a TPC generation window control unit 107, an encoding unit 108, a frame generation unit 109, a modulation unit 110, and a spreading unit 111.

Next, the structure of each part of this control apparatus is demonstrated.
The despreading section 101 performs a correlation operation between a baseband received signal (BB received signal in the figure, hereinafter received signal) received from the opposite station and a reference code (not shown) to despread the baseband received signal. It is something to do.
The detector 102 performs demodulation processing such as transmission path estimation and synchronous detection of the received signal after despreading.
The determination / decoding unit 103 determines the received signal after demodulation from the detection unit 102 and performs decoding such as error correction to extract received data.
The SIR measurement unit 104 measures the quality of the received signal after despreading, and obtains and outputs an instantaneous desired signal power to interference signal power ratio (SIR) for each control period from the measurement result.
The inserted TPC generation unit 105 compares the instantaneous SIR (instantaneous SIR in the figure) from the SIR measurement unit 104 with the reference quality (TargetSIR in the figure), and as a command for transmission power control for the opposite station based on the comparison result. The generation TPC is generated and output.

Unlike insertion TPC 205 in the conventional general transmission power apparatus shown in FIG. 4, insertion TPC generation section 105 generates an insertion TPC by this control method described above, and outputs it to frame generation section 109.
The insertion TPC generation unit 105 includes a memory (not shown), and each time an insertion TPC is generated, information about the insertion TPC (Up or Down, etc.) is stored in the memory as a history. In the insertion TPC generation unit 105, the memory may store the information of the insertion TPC for a predetermined control cycle time and erase the information of the previous insertion TPC.

    The inserted TPC generation unit 105 determines which reception quality window the instantaneous SIR belongs to. If the instantaneous SIR belongs to the first or second region, the insertion TPC generation unit 105 stores the history of the inserted TPC stored in the memory. The insertion TPC to be generated next is determined by reference and generated, and is output to the frame generation unit 109. In addition, when the instantaneous SIR belongs to the third region, the insertion TPC generation unit 105 specifies and generates the next generation TPC to be generated based on the determination result, and outputs it to the frame generation unit 109.

Here, a method of generating an insertion TPC in the insertion TPC generation unit 105 will be described with reference to FIG. FIG. 3 is a flowchart showing insertion TPC generation processing in the insertion TPC generation unit 105 of this control apparatus.
In FIG. 3, the insertion TPC generation unit 105 determines the difference between the instantaneous SIR from the SIR measurement unit 104 and the TargetSIR (S1), and determines which reception quality window the instantaneous SIR belongs to (S2). If the instantaneous SIR belongs to the first area as a result of the determination in the process S2 (area 1 of S2), the insertion TPC generation unit 105 next refers to the history of the insertion TPC stored in the memory (S3 ), Specifying and generating an insertion TPC to be generated based on the history (S4). In the processes S3 and S4, the insertion TPC generation unit 105 specifically refers to the information of the insertion TPC generated at the immediately preceding control cycle timing from the history of the insertion TPC, and identifies the insertion TPC to be generated from the information. To do.

    When the instantaneous SIR belongs to the first region, the insertion TPC generation unit 105 generates Down as a new insertion TPC if the insertion TPC at the immediately preceding control cycle timing is Up, and conversely if it is Down, Up Is generated. Therefore, when the instantaneous SIR <TargetSIR, the insertion TPC generation unit 105 generates the insertion TPC in the order of Up, Down, Up, Down, and when the reception SIR> TargetSIR, the insertion TPC is generated in the order of Down, Up, Down, Up. .

    Further, even when the instantaneous SIR belongs to the second area (determination 2 in S2) based on the determination in the process S2, the insertion TPC generation unit 105 refers to the history of the insertion TPC stored in the memory (S5). ), Specifying and generating an insertion TPC to be generated based on the history (S6). In the processes S5 and S6, the insertion TPC generation unit 105 specifically refers to the information of the insertion TPC generated at the previous and previous control cycle timings from the history of the insertion TPC, and stores the two insertion TPC information. The insertion TPC to be generated is specified from the combination.

For example, when the instantaneous SIR belongs to the second region, and when the instantaneous SIR <TargetSIR, the information of the inserted TPC generated at the two previous and previous control cycle timings is (Up, Up) ( Hereinafter, this notation is used), the insertion TPC generation unit 105 generates Down as a new insertion TPC. Similarly, in the case of (Down, Up) or (Up, Down), the insertion TPC generation unit 105 generates Up as a new insertion TPC. Therefore, the insertion TPC generation unit 105 generates insertion TPCs in the order of Up, Up, Down, Up, Up, and Down.
Further, when instantaneous SIR> Target SIR, if the information of the insertion TPC generated at the previous and previous control cycle timings is (Down, Down), the insertion TPC generation unit 105 sets the new insertion TPC as the new insertion TPC. Generate Up. Similarly, in the case of (Down, Up) or (Up, Down), the insertion TPC generation unit 105 generates Down. Therefore, the insertion TPC generation unit 105 generates the insertion TPC in the order of Down, Down, Up, Down, Down, Up.

Also, if the instantaneous SIR belongs to the third region (S3 region 3) based on the determination in the process S2, Up is inserted as the insertion TPC when reception SIR <TargetSIR, and insertion when reception SIR> TargetSIR. Down is generated as TPC (S7).
In any region, the insertion TPC generation unit 105 stores information on the newly generated insertion TPC in the memory when the insertion TPC is generated, and outputs the generated insertion TPC to the frame generation unit 108. To do.

When the insertion TPC is generated and output in each region, the insertion TPC generation unit 105 refers to the new instantaneous SIR at the next control cycle timing and compares it with TargetSIR (S1). The insertion TPC generation unit 105 realizes the insertion TPC generation processing by repeating the above-described processing.
In this control apparatus, the insertion TPC generation unit 105 may change the period of the insertion TPC history to be referred to when generating the insertion TPC in each region.

    Further, the insertion TPC generation unit 105 performs a process of narrowing or expanding the first and second regions based on a control signal from a TPC generation window control unit 107 described later. Specifically, the insertion TPC generation unit 105 can change the first and second regions by changing the value of the difference between the reception SIR and the Target SIR corresponding to the boundary between the first and second regions.

    In FIG. 2, a fading frequency estimation unit 106 estimates a fading frequency in the transmission path from the result of transmission path estimation in the detection unit 102. Specifically, fading frequency estimation section 106 performs complex conjugate multiplication of the amplitude phase fluctuation amount (average amplitude phase fluctuation amount) averaged over a plurality of received symbols and the previous averaged amplitude phase fluctuation amount. Thus, the phase rotation amount is obtained, and the fading frequency is estimated from the phase rotation amount.

The TPC generation window control unit 107 controls the boundary of the reception quality window of the insertion TPC generation unit 105 according to the change in the transmission path such as fading based on the fading frequency estimation result from the fading frequency estimation unit 106. .
For example, when the fading frequency exceeds a specified value and the fading is determined to be fast, the TPC generation window control unit 107 places importance on the followability of TPC rather than suppression of parasitic vibration, and the first and second in FIG. A control signal for controlling the boundary so as to narrow the region is output to the insertion TPC generation unit 105. Conversely smaller than the fading frequency is a specified value, when the fading is judged to slow, with an emphasis on the suppression of parasitic oscillations, the control signal for controlling the boundary so as to widen the first and second region in FIG. 1 Is output to the insertion TPC generation unit 105.
The TPC generation window control unit 107 may control the boundary of either the first region or the second region based on the fading frequency estimation result.

The encoding unit 108 performs encoding such as error correction on transmission data to be transmitted.
The frame generation unit 109 generates a data frame by time-multiplexing the data encoded by the encoding unit 108 with the insertion TPC, the reference signal for synchronous detection, and the like.
The modulation unit 110 modulates the data time-multiplexed by the frame generation unit 109.
Spreading section 111 spreads the modulated signal with a spreading code (not shown), and outputs the modulated signal after spreading processing as a baseband transmission signal (BB transmission signal in the figure).

Next, the operation of this control apparatus will be described.
First, the received signal from the opposite station is despread by the reference code in the despreading section 101, and the despread received signal is input to the SIR measuring section 104 and the detecting section 102, respectively. Detection section 102 performs demodulation processing such as transmission path estimation and synchronous detection on the received signal after despreading, and outputs the demodulated signal to determination / decoding section 103 and fading estimation section 106.
In the determination / decoding unit 103, the demodulated signal is subjected to binary determination of “0” and “1” or decoding processing, and received data is extracted.
The processing in fading estimation unit 106 will be described later.

On the other hand, SIR measuring section 104 obtains an instantaneous received SIR for each transmission power control period from the received symbol after despreading, and outputs it to insertion TPC generating section 207.
In the insertion TPC generation unit 105, the instantaneous SIR is compared with the reference quality TargetSIR to determine the difference from the TargetSIR, to determine which reception quality window belongs, and to be stored in the memory according to the result. By referring to the inserted TPC history, the inserted TPC is generated and output every transmission power control period.
The inserted TPC output from the inserted TPC generation unit 105 is time-multiplexed together with the reference signal for synchronous detection and the transmission data encoded by the encoding unit 108 in the frame generation unit 109. The multiplexed transmission data is subjected to modulation processing in the modulation unit 110, and further subjected to spreading processing using a spreading code in the spreading unit 111 and output as a baseband transmission signal. Thereafter, the baseband transmission signal is wirelessly transmitted to the opposite station.

    For example, when the instantaneous SIR belongs to the first area, the operation in the insertion TPC generation unit 105 is performed according to the processing S3 and S4 in the flowchart of FIG. , And a new insertion TPC is identified and generated based on the information, and is output to the frame generation unit 109. The insertion TPC generation unit 105 determines a new instantaneous SIR from the SIR measurement unit 104 at the next control cycle timing, and thereafter repeats the same operation.

    When the instantaneous SIR belongs to the second region, the information on the insertion TPC at the previous and previous control cycle timings stored in the memory is referred to in accordance with the processes S5 and S6 in the flowchart of FIG. Based on the information, a new insertion TPC is identified and generated, and is output to the frame generation unit 109. As in the case of the first region, the insertion TPC generation unit 105 determines a new instantaneous SIR from the SIR measurement unit 104 at the next control cycle timing, and thereafter repeats the same operation.

    If the instantaneous SIR belongs to the third area, UP is set as an insertion TPC when reception SIR <Target SIR, and Down is set as insertion TPC when reception SIR> Target SIR, according to processing S7 in the flowchart of FIG. Is generated and output to the frame generation unit 109. As in the case of the first and second regions, the insertion TPC generation unit 105 determines the new instantaneous SIR from the SIR measurement unit 104 at the next control cycle timing, and thereafter repeats the same operation.

In the process of performing the above series of operations, the fading frequency estimation unit 106 estimates the fading frequency based on the result of the transmission path estimation from the detection unit 102 and outputs it to the TPC generation window control unit 107.
The TPC generation window control unit 107 uses a fading frequency estimation result and compares it with a preset specified value. As a result of the comparison, when the fading frequency exceeds a specified value and it is determined that fading is fast, a control signal for controlling the boundary to narrow the first and second regions is output to the insertion TPC generation unit 105, in the insertion TPC generating section 105, so as to narrow the first and second regions, the boundary is strange notice.
Conversely, when it is determined that the fading frequency is smaller than the specified value and fading is slow, a control signal for controlling the boundary to widen the first and second regions is output to the insertion TPC generation unit 105 and inserted. in TPC generator 105, so as to widen the first and second regions, the boundary is strange notice. The above is the operation of the present control device.

In this control apparatus, the insertion TPC generation unit 105 determines a region to which the instantaneous SIR belongs, and then generates a series of insertion TPCs shown in FIG. 1 for a specific period according to the region. It is good also as a control method. In this case, when the instantaneous SIR belongs to the first region and the instantaneous SIR <TargetSIR, the insertion TPC generation unit 105 inserts the TPC in the order of Up, Down, Up, and Down over four control cycle times. When reception SIR> TargetSIR, the insertion TPC is generated in the order of Down, Up, Down, Up. Similarly, when the instantaneous SIR belongs to the second region, the insertion TPC generation unit 105 generates the six insertion TPCs illustrated in FIG. 1 over six control cycle times. Note that a series of insertion TPC patterns generated in each region may be different.
While the insertion TPC is generated by this control method, an instantaneous SIR is input to the insertion TPC generation unit 105, but until all the insertion TPCs are generated, the insertion TPC generation unit 105 Refer to the instantaneous SIR and do not compare with TargetSIR.
Therefore, according to the above control method, the inserted TPC generation unit 105 refers to the new instantaneous SIR after generating the inserted TPC for one instantaneous SIR. It is controlled to be close to TargetSIR without being affected by the control delay.

    According to this control method and this control apparatus, the absolute value of the difference between the received SIR and the reference quality is divided into a plurality of stages, each stage is defined as a reception quality window, and the reception quality window to which the received SIR belongs is determined. Then, in accordance with the reception quality window to which the reception SIR belongs, a specified insertion TPC is generated every unit cycle time and inserted into the transmission signal, so that the reception quality due to the parasitic vibration generated due to the control delay There is an effect that can reduce the deterioration of.

    In particular, in the present control method, in the reception quality window closest to the reference quality, by alternately generating UP and Down insertion TPCs, the same reception quality as when there is no control delay can be obtained. In the reception quality window close to the quality, the reception SIR is gradually reduced to the reference quality by generating the insertion TPC in the direction in which the reception SIR approaches the reference quality and the insertion TPC in the opposite direction so as to increase the ratio of the former. In the reception quality window farthest from the reference quality, by generating an UP or Down insertion TPC, it is possible to approach the reference quality most quickly. It is possible to reduce the deterioration of reception quality by suppressing the amplitude of the parasitic vibration.

    Moreover, according to this control apparatus, the boundary of a reception quality window is changed based on a fading frequency estimation result with respect to the fading frequency estimation part which estimates a fading frequency from the transmission-path estimation result of a received signal, and an insertion TPC generation part. By providing the insertion TPC generation window control unit for performing control, it is possible to realize transmission power control in consideration of the influence of fading and to effectively reduce deterioration of reception quality due to parasitic vibration.

    The present invention can reduce degradation of received signal quality due to parasitic oscillation caused by delay control in a CDMA mobile communication system that performs transmission power control by closed loop control.

It is a conceptual diagram of the transmission power control method which concerns on embodiment of this invention. It is a block diagram of the configuration of a transmission power control apparatus according to an embodiment of the present invention. It is the flowchart figure which showed the production | generation process of the insertion TPC in the insertion TPC production | generation part 105 of this control apparatus. It is a block diagram of a conventional general transmission power control apparatus. FIG. 5 is an explanatory diagram showing a concept of an insertion TPC output by an insertion TPC generation unit 205 in FIG. 4. It is the table | surface figure which showed the relationship between insertion TPC by control delay, and reception SIR. It is the graph which showed the relationship between control delay and reception SIR.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 101,201 ... Despreading part 102,202 ... Detection part 103,203 ... Determining / encoding part 104,204 ... SIR measurement part 105,205 ... Insertion TPC generation part 106 ... Fading frequency estimation part 107 ... TPC generation window control unit, 108, 206 ... Coding unit, 109, 207 ... Frame generation unit, 110, 208 ... Modulation unit, 111, 209 ... Spreading unit

Claims (1)

A power control command for measuring the desired signal power to interference signal power ratio of the signal from the opposite station and increasing or decreasing the transmission power in the opposite station based on the comparison result between the measured value and the reference value for each unit period A transmission power control method for generating and transmitting to the opposite station and controlling transmission power according to a power control command received at the opposite station,
Dividing the value of the desired signal power to interference wave power ratio into a plurality of stages based on the absolute value of the difference between the desired signal power to interference signal power ratio and the reference value;
When the measured value is the first stage closest to the reference value, an ascending or descending power control command corresponding to a direction in which the measured value approaches the reference value for each unit period, and the power control command; Generates alternating power control commands,
When the measured value is the second stage farthest from the reference value, an ascending or descending power control command corresponding to a direction in which the measured value is brought closer to the reference value for each unit cycle is generated.
When the measured value is a stage excluding the first stage and the second stage, an ascending or descending power control command corresponding to a direction in which the measured value approaches the reference value for each unit period, and the A power control command opposite to the power control command is generated so that the ratio of the former is greater than that of the latter, and the ratio of the former is increased at a stage farther from the reference value ,
A fading frequency in a transmission path is estimated, and when the estimated fading frequency exceeds a specified value, the first stage is set narrower than in the case where the fading frequency is smaller than the specified value. A transmission power control method.

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