JP2003032184A - Receiver and transmission power control method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control a target SIR in an outer loop control by following a propagation environment that fluctuates greatly. SOLUTION: An error correction decoding section 103 performs error correction decoding processing on an output signal of a deinterleave section 102 to obtain received data. Error correction encoding section 104 performs the same error correction encoding processing as that of the communication partner on the received data. The BER estimating unit 105 includes an error correction encoding unit 10
The BER is estimated from the output signal of No. 4 and the output signal of the deinterleave unit 102. The subtractor 106 subtracts the target BER from the BER estimated by the BER estimator 105. The correction value generation unit 107 generates a target SIR correction value based on the result of the subtraction performed by the subtraction unit 106.
The target SIR generation unit updates the target SIR based on the correction value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver and a transmission power control method for a CDMA mobile communication system using outer loop control.

[0002]

2. Description of the Related Art In a CDMA mobile communication system,
Transmission power control is performed to prevent deterioration of communication quality due to excessive transmission power. Closed loop control, which is one of the transmission power control, is performed by the receiving side device so that the SIR (desired wave power to interference wave power ratio) approaches the target SIR.
(Transmit Power Control) to instruct to increase / decrease the transmission power based on the comparison result between the target SIR and
Is generated and sent to the transmission side device, and the transmission side device wirelessly transmits data with power based on TPC.

In outer loop control, which is a type of closed loop control, the target SIR is controlled according to the propagation environment so as to be set to the minimum value required to satisfy the required communication quality.

In the conventional outer loop control, BLER (block error rate) is used as the communication quality, the BLER is estimated by the number of blocks in which the calculation results of the CRC associated with each transmission unit match, and this BLER is the required BLER. The target SIR is controlled so that

[0005]

However, the BLE
Since it takes a long time to estimate R, the conventional outer loop control requires the target S when the propagation environment fluctuates greatly.
There is a problem that it is difficult to control the IR by following the fluctuation of the propagation environment.

The present invention has been made in view of the above circumstances, and provides a receiving apparatus and a transmission power control method capable of controlling a target SIR in an outer loop control by following a propagation environment where fluctuations are large. With the goal.

[0007]

A receiving apparatus of the present invention comprises a bit error rate estimating means for estimating a bit error rate of a specific channel included in a received signal, and a desired desired wave power based on the bit error rate. And a target SIR control means for controlling the power ratio to the interference wave.

With this configuration, since the bit error rate can be estimated in a short time, in the outer loop control,
Even if the fluctuation is severe, the target desired power to interference power ratio can be controlled by following the fluctuation of the propagation environment.

In the receiving apparatus of the present invention, the bit error rate estimating means adopts a configuration for estimating the bit error rate of the channel specified according to the error correction capability of the error correction coding process applied to each channel.

With this configuration, the transmission power can be controlled accurately, so that it is possible to improve the followability to changes in the propagation environment and suppress the deterioration of the communication quality due to the excessive transmission power.

In the receiving apparatus of the present invention, the bit error rate estimating means adopts a configuration for estimating the bit error rate of the most important channel.

With this configuration, it is possible to improve the followability to changes in the propagation environment, and it is possible to more accurately receive the desired channel.

In the receiving apparatus of the present invention, the bit error rate estimation means estimates the bit error rate of each channel multiplexed in the received signal, and the target SIR control means determines the bit error rate of each channel by a specific ratio. In the configuration, the target desired power to interference power ratio is controlled based on the value obtained by weighting and adding.

With this configuration, it is possible to prevent a sudden change in the transmission power, so that it is possible to enhance the followability to the change in the propagation environment and suppress the deterioration of the communication quality due to the excessive transmission power.

The base station apparatus of the present invention has a configuration including any one of the above receiving apparatuses. Further, the communication terminal device of the present invention has a configuration including any one of the above receiving devices.

With these configurations, the target desired power to interference power ratio can be controlled in accordance with the fluctuation of the propagation environment even when the fluctuation is severe, so that high quality wireless communication is performed. be able to.

The transmission power control method of the present invention comprises a step of estimating a bit error rate of a received signal, and a step of controlling a target desired power to interference power ratio based on the bit error rate. Take.

Since the bit error rate can be estimated in a short time by this method, the target desired power to interference power ratio is controlled in accordance with the fluctuation of the propagation environment even when the fluctuation is severe. be able to.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is to control a target SIR based on BER (bit error rate). Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 1 of the present invention.
The signal received by the receiver of FIG. 1 is subjected to predetermined radio processing (down conversion, amplification, etc.) and then input to the despreading unit 101.

Despreading section 101 performs despreading processing for multiplying a received signal by a spreading code unique to a user, and despreads the signal after deinterleaving section 102 and SIR measuring section 109.
Output to. Deinterleaving section 102 performs processing (deinterleaving) on the signal after despreading to restore the data order exchanged by the transmission device of the communication partner, and outputs it to error correction decoding section 103 and BER estimation section 105. To do.

The error correction decoding unit 103 performs error correction decoding processing such as Viterbi decoding for correcting an error caused by the influence of the propagation path distortion in the output signal of the deinterleave unit 102, such as Viterbi decoding, and performs error correction. The signal after the decoding process is output to error correction coding section 104. The error correction coding unit 104 performs the same error correction coding processing as that performed by the transmission device of the communication partner, such as convolutional coding, on a specific channel included in the received data, and performs the error correction coding processing after the error correction coding processing. The signal is output to the BER estimation unit 105.

The BER estimation unit 105 compares the output signal of the error correction coding unit 104 with a specific channel included in the output signal of the deinterleave unit 102, counts the number of different bits, and regards this as an erroneous bit. Assuming that the ratio of the number of error bits to the predetermined number of received bits (BER: Bit Er
error rate) and outputs the estimated BER to the subtraction unit 106. The subtraction unit 106 subtracts the target BER from the BER estimated by the BER estimation unit 105, and outputs the subtraction result to the correction value generation unit 107.

The correction value generator 107 outputs the target S when the subtraction result of the subtractor 106 is a positive number, that is, when the estimated BER exceeds the target BER.
When the correction value that raises the IR is generated and the subtraction result in the subtraction unit 106 is a negative number, that is, when the estimated BER is less than the target BER, the target S
A correction value that lowers IR is generated. Then, the correction value generation unit 107 outputs the generated correction value to the target SIR generation unit 108. Target SIR generator 108
Updates the target SIR based on the correction value output from the correction value generation unit 107, and updates the updated target SI.
The R is output to the subtraction unit 110.

The SIR measuring section 109 measures the desired wave power and the interference wave power from the output signal of the despreading section 101, and SI
R (desired wave power to interference wave power ratio) is calculated, and the calculated S
The IR is output to the subtraction unit 110. The subtraction unit 110 uses the SI
The target S is calculated from the SIR calculated by the R measurement unit 109.
The IR is subtracted, and the subtraction result is output to the TPC generation unit 111.

The TPC generation unit 111 generates a TPC command for lowering the transmission power when the subtraction result of the subtraction unit 110 is a positive number, that is, when the calculated SIR exceeds the target SIR. Subtraction unit 11
If the subtraction result at 0 is a negative number, that is,
When the calculated SIR falls below the target SIR, a TPC command that raises the transmission power is generated. The generated TPC command is sent to the transmitting device of the communication partner.

In this way, by correcting the target SIR based on the BER of a specific channel, the BER
The target SI can be estimated in a short time.
It is possible to control R by following changes in the propagation environment.

(Embodiment 2) Here, in a mobile communication system, DCCH (Dedicated Control Channel) and D
Generally, TCH (Dedicated Traffic Channel) is multiplexed and transmitted / received. Then, these signals may be subjected to different error correction coding processing in the transmission side apparatus. For example, if DCCH is subjected to error correction coding processing using a turbo code and DTCH is subjected to error correction coding processing using a convolutional code, the turbo code has a higher error correction capability, so
CH is more strongly decoded.

In the second embodiment, a case will be described in which the target SIR is controlled based on the BER of the channel error-correction coded by a method having a high error correction capability. FIG. 2 is a block diagram showing the configuration of the receiving apparatus according to the present embodiment. However, in the receiving apparatus of FIG. 2, the same components as in FIG. 1 are assigned the same reference numerals as those in FIG. 1 and description thereof is omitted. Further, in the signal received by the receiving apparatus in FIG. 2, it is assumed that DCCH is subjected to error correction coding processing by a convolutional code and DTCH is subjected to error correction coding processing by a turbo code.

The receiving apparatus of FIG. 2 has two error correction decoding sections 103 and a channel selection section 201 is added, as compared with FIG.

Deinterleaving section 102 outputs DCCH to error correction decoding section 103-1 and channel selection section 201, and outputs DTCH to error correction decoding section 103-2 and channel selection section 201.

Error correction decoding section 103-1 carries out error correction decoding processing by Viterbi decoding on the DCCH output from deinterleaving section 102 to obtain received data.
The error correction decoding unit 103-2 includes the deinterleaving unit 10
The DTCH output from 2 is subjected to error correction decoding processing by turbo decoding to obtain received data and output to the error correction coding unit 104. Error correction coding unit 104
Performs error correction coding processing by a turbo code on the output signal of error correction decoding section 103-2, and outputs the signal after the error correction coding processing to BER estimation section 105.

Channel selecting section 201 selects a DCCH from the DCCH and DTCH output from deinterleaving section 102 and outputs it to BER estimating section 105. B
The ER estimation unit 105 compares the output signal of the error correction coding unit 104 with the output signal of the channel selection unit 201, and outputs BE.
Estimate R.

In this way, the control of the target SIR is
Since the transmission power can be accurately controlled by performing the error correction coding based on the BER of the channel that has been subjected to the error correction coding with a method having a high error correction capability, it is possible to enhance the followability to the change of the propagation environment and It is possible to suppress the deterioration of the communication quality due to the excessive transmission power as compared with the first embodiment.

In this embodiment, the case where the BER of the channel error-correction-coded is estimated by a method having a high error-correction capability has been described, but the present invention is not limited to this and is multiplexed on data. It is also possible to estimate the BER of the most important channel among the channels. In this case, it is possible to improve the followability to changes in the propagation environment, and it is possible to more accurately receive the desired channel.

(Third Embodiment) In the third embodiment, a case will be described in which the target SIR is controlled based on the value obtained by weighting and adding the BER of each channel multiplexed in the data at a specific ratio.

FIG. 3 is a block diagram showing the configuration of the receiving apparatus according to this embodiment. However, in the receiving apparatus of FIG. 3, the same components as in FIG. 2 are assigned the same reference numerals as those in FIG. 2 and their explanations are omitted. Further, in the signal received by the receiving apparatus of FIG. 3, it is assumed that the DTCH is subjected to the error correction coding processing by the turbo code and the DCCH is subjected to the error correction coding processing by the convolutional code.

The receiving apparatus of FIG. 3 has BE compared with FIG.
An R calculation unit 301 is added, and a configuration having two error correction coding units 104 and two BER estimation units 105 is adopted.

The error correction coding unit 104-1 performs error correction coding processing by Viterbi decoding on the error correction decoding unit 103-.
1 output signal, and outputs the signal after the error correction coding process to the BER estimation unit 105-1. The error correction coding unit 104-2 performs error correction coding processing by a turbo code on the output signal of the error correction decoding unit 103-2, and the signal after the error correction coding processing is performed by the BER estimation unit 105.
Output to -2.

The BER estimation section 105-1 compares the output signal of the error correction coding section 104-1 with the output signal of the deinterleaver 102 to estimate the first BER, and the estimated first BER is BER. It is output to the arithmetic unit 301. BER
The estimation unit 105-2 compares the output signal of the error correction encoding unit 104-2 with the output signal of the deinterleaver 102 to estimate the second BER, and the estimated second BER is BE.
It is output to the R calculation unit 301.

The BER calculator 301 weights and adds the first BER and the second BER at a specific ratio, and outputs the addition result to the subtractor 106. The subtraction unit 106 subtracts the target BER from the addition result of the BER calculation unit 301, and outputs the subtraction result to the correction value generation unit 107.

In this way, the control of the target SIR is
By performing the weighted addition of the BER of each channel multiplexed in the data at a specific ratio, it is possible to prevent a sudden change in the transmission power, and thus it is possible to improve the followability to the change in the propagation environment. While you can
It is possible to suppress the deterioration of communication quality due to an excessive transmission power as compared with the first embodiment.

[0043]

As described above, according to the present invention,
By controlling the target SIR based on the BER, it is possible to control the target SIR by following changes in the propagation environment in outer loop control.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 3 of the present invention.

[Explanation of symbols]

103 error correction decoding unit 104 error correction coding unit 105 BER estimation unit 106 Subtraction unit 107 correction value generation unit 108 Target SIR generator 201 channel selector 301 BER calculation unit

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Claims (7)

[Claims] 1. A bit error rate estimating means for estimating a bit error rate of a specific channel included in a received signal, and a target SIR control for controlling a target desired power to interference wave power ratio based on the bit error rate. And a receiving device. 2. The bit error rate estimation means estimates the bit error rate of a channel specified according to the error correction capability of the error correction coding process performed on each channel. Receiver. 3. The receiving apparatus according to claim 1, wherein the bit error rate estimating means estimates the bit error rate of the most important channel. 4. The bit error rate estimation means estimates the bit error rate of each channel multiplexed in the received signal, and the target SIR control means weights and adds the bit error rate of each channel at a specific rate. The receiving apparatus according to claim 1, wherein the target desired power to interference power ratio is controlled based on the above. 5. A base station apparatus comprising the receiving apparatus according to any one of claims 1 to 4. 6. A communication terminal device comprising the receiving device according to claim 1. 7. A transmission power control comprising: a step of estimating a bit error rate of a received signal; and a step of controlling a target desired wave power to interference wave power ratio based on the bit error rate. Method.