JP2000295121A - Wireless communication device and wireless communication system - Google Patents

Abstract

(57) [Problem] In an environment where the magnitude of an interference wave changes, gain control takes time to follow the magnitude of the interference wave. When a signal is received, a signal-to-interference power ratio is measured. If the signal-to-interference power ratio is larger than a reference value, the reception of the signal is terminated, and then the signal is received. Hold the gain for. When the signal-to-interference power ratio is smaller than the reference value, the gain before receiving the signal is restored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a communication apparatus in a wireless communication system.

[0002]

2. Description of the Related Art In radio communication, automatic gain control (AGC) is usually performed because a received signal level varies depending on a propagation environment. Conventionally, this AGC circuit controls the received signal by performing envelope detection, measuring the received electric field strength, and using the value to control the level of the received signal input to the demodulator to be constant.

However, since this AGC circuit operates even when no signal is being received, when a large-level signal is suddenly received from a state in which no signal is received, the level fluctuation is caused. There is a drawback that it takes time to follow up, and in particular, in packet communication, the throughput is reduced.

Therefore, an AGC circuit as shown in FIG. 5 has been conventionally proposed.

In FIG. 5, a signal received by an antenna 11 is demodulated by a demodulation circuit 150 via an antenna duplexer 12 and an AGC circuit 140.

Here, in the AGC circuit 140, the received signal input from the antenna duplexer 12 is converted into a gain variable circuit 141.
After passing through, the gain control section 143 controls the gain of the gain variable circuit 141 so that the signal level becomes equal to the reference level.

[0007] Further, at the end of packet reception, gain control section 143 holds the value of the gain control signal until the next packet is received, thereby speeding up the AGC operation.

[0008]

However, in the conventional example, when the signal is received in a low SNR (signal-to-noise ratio) (or signal-to-interference power ratio) environment, an error due to the interference signal is large in the reception level measurement value. Therefore, there is a problem that an error of the gain control signal becomes large and it takes time to pull in the AGC at the time of receiving the next packet.

[0009]

SUMMARY OF THE INVENTION The present invention provides a gain control unit, a measurement unit for measuring reception quality, and a gain of the gain control unit after the reception of the reception signal is completed in accordance with the measured quality. It is characterized by comprising setting means for setting

According to this configuration, the gain control of the next signal is started according to the gain when the reception quality is high, so that the gain can be pulled in at a high speed and the throughput can be improved.

[0011]

FIG. 1 is a block diagram of a wireless communication apparatus embodying the present invention. In FIG. 1, 11 is an antenna, 12 is an antenna duplexer, 13 is a transmission circuit, 14
Is an AGC circuit for controlling and outputting the level of the received signal output from the antenna duplexer 12, and 15 is a demodulation circuit.

Reference numeral 16 denotes a received signal detection circuit for detecting a signal from the output signal of the AGC circuit 14, and 17 denotes an AGC circuit 14
A CIR measurement circuit 18 for measuring a signal-to-interference power ratio (CIR) based on the output from the AGC circuit 18 outputs an AGC control signal to the AGC circuit 14 in accordance with the output of the received signal detection circuit 16.

In FIG. 1, the CIR measured by the CIR measuring circuit 17 is used as data representing the reception quality. Instead of the CIR (or SNR (Signal Noise Ratio)), the error rate of the reception signal is used as the reception quality. May be used as data representing Alternatively, the interference power itself or the number of times a reception error has occurred may be used.

In FIG. 1, a transmission signal output from a transmission circuit 13 is transmitted from an antenna 11 through an antenna duplexer 12. Here, the antenna duplexer 12
Switches between transmission and reception by a switch or a filter according to the frequency difference between the uplink and the downlink.

The signal received by the antenna 11 is passed through an antenna duplexer 12, is appropriately level-converted by an AGC circuit 14, is input to a demodulation circuit 15, and is demodulated.

The output of the AGC circuit 14 is input to a received signal detection circuit 16 to determine the presence or absence of a signal of a desired level or the presence or absence of a desired signal pattern, and output the determination result to an AGC control circuit 18. .

The output of the AGC circuit 14 is input to a CIR measurement circuit 17 where the signal-to-interference power ratio is measured, and the result of the determination is output to an AGC control circuit 18.

This CIR indicates the reception quality of the received signal.

The AGC control circuit 18 outputs an AGC control signal to the AGC circuit 14 according to a signal from the reception signal detection circuit 16.

The AGC circuit 14 is configured, for example, as shown in FIG. In FIG. 2, the received signal is appropriately level-converted by a gain variable circuit 21 and output to a demodulation circuit 15.

At the same time, the level measuring circuit 22 measures the output signal level from the variable gain circuit 21. The measured value is input to the gain control circuit 23 and outputs a control signal to the gain variable circuit 21 so that the level becomes equal to the reference level.

The gain control circuit 23 stores the control value of the control signal of the gain variable circuit 21 in the storage circuit 24 or reads out the control value of the control signal from the storage circuit 24 in accordance with the AGC control signal output from the AGC control circuit 18. And outputs it to the gain variable circuit 21.

The receiving operation will be described in detail with reference to FIG.

First, when no signal is received, that is, when a desired signal is not detected by the received signal detection circuit 16 (S302), the AGC control circuit 18
The GC circuit 14 outputs an AGC control signal so as to be held at the control value stored in the storage circuit 24 (S
301).

Thereafter, when the reception signal detection circuit 16 determines that the desired signal has been received based on the reception level or the reception signal pattern, the fact is transmitted to the AGC control circuit 18 (S302).

Then, the AGC control circuit 18
An AGC control signal for instructing to release the hold and to start the gain control is output to 14 (S30).
3).

During this time, the CIR is measured by the CIR measuring circuit 17, and if the CIR is higher than the reference value, the gain control circuit 23
The control circuit 24 stores a control value at an appropriate time during reception of a desired signal.
AGC control signal is output so as to store the AGC control signal (S30).
5).

The gain control circuit 23 includes a level measurement circuit 22
When the pull-in of the gain control according to the level measured by the above is completed, the gain variable circuit 2 when the pull-in of the gain control is completed until the reception started from S302 is completed.
Hold the gain of 1.

When the gain control is completed, that is, when the CIR at the time when the output signal level of the gain variable circuit 21 becomes equal to the reference level is higher than the reference value, the storage circuit 24 stores the gain at that time. The gain of the variable circuit 21 is stored. This gain is used as the gain of the gain variable circuit 21 after reception is completed.

Further, the output signal level of the gain variable circuit 21 when the pull-in of the gain control is completed is stored in the storage circuit 24, and the gain control circuit 23 stores the output signal level and the reference level stored in the storage circuit 24. May be set in accordance with the above.

Thereafter, when the demodulation circuit 15 detects the end of reception, the AGC control signal from the AGC control circuit 18
The AGC circuit 14 holds with the control value stored in the storage circuit 24 (S301). In addition, the end of reception,
This can be performed according to the output of the reception signal detection circuit 16.

If the CIR is equal to or smaller than the reference value in S304, the AGC control circuit 18 outputs an AGC control signal so as to return to the gain stored in the storage circuit 24 after the reception is completed (S306) (S306). S301).

As described above, in the present embodiment, the gain is set according to the control value stored in the storage circuit 24 until a signal is detected.

When a signal is detected, the gain is controlled according to the level of the signal.

Then, the gain is used from when an appropriate gain is set according to the level of the signal until reception of the signal ends.

If the CIR during the reception of the signal is lower than the reference value, the gain before the start of the signal (gain according to the control value stored in the storage circuit 24) is obtained. Return to

On the other hand, if the CIR is higher than the reference value, the gain after reception is the same as the gain during signal reception. Further, the control value of the storage circuit 24 is updated according to the gain.

In the above embodiment, if the CIR is low, the gain after reception is returned to the gain before reception. However, the control value of the storage circuit 24 may be updated with a weight according to the CIR. .

That is, the gain before the signal is detected is G
1. Assuming that the gain set according to the received signal is G2, the gain G3 after the end of the reception is G3 = ((1-a) × G
1 + axG2) / 2. Note that a is
This is a weight determined according to the CIR. This weight a is
Taking a value in the range from 0 to 1, taking a large value if the CIR is high, and taking a small value if the CIR is small.

The method of measuring the CIR representing the reception quality by the CIR measuring circuit 17 is arbitrary. For example, the CIR measuring circuit 17 measures the beat based on the interference signal. , And in the case of spread spectrum communication, a method of obtaining from the signal components by correlation detection and the total received power. Also, the method of measuring CIR is not limited to the above method.

In order to measure an error rate as reception quality, an error may be detected when decoding a received signal.

FIG. 4 shows a modified flow of the receiving operation shown in FIG. The configuration of the wireless communication device that performs the receiving operation of FIG. 4 is the same as that of FIG.

In FIG. 4, after the power is turned on or reset, that is, after the control value stored in the storage circuit 24 is initialized, the control value is stored for the first time only (S314) regardless of the CIR of the received signal. 3 in that it is stored in a circuit 24.

FIG. 4 also has the same operation and effect as FIG. 3, but furthermore, the first one after power-on or reset.
By storing the control value in the storage circuit 24 only for the first time, the control value initialized after the power is turned on or reset is set to the vicinity of the reception level although there is some error due to the interference signal. AGC pull-in time can be shortened.

[0045]

As described above, according to the present invention,
Since the next signal is received according to the gain when the reception quality is high, the influence of the gain control error due to the interference signal can be reduced, and the time required for gain control when receiving a high quality signal can be shortened. Since the preamble period can be shortened, a high-quality signal can be received at a high speed, and the throughput can be improved.

Also, after initializing the control values stored in the storage means, the control values are stored in the storage means only for the first time, regardless of the reception quality. However, since the gain hold value can be set close to the reception level, the time required for the next gain control can be shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a wireless communication device embodying the present invention.

FIG. 2 is a block diagram showing an AGC circuit of the wireless communication device embodying the present invention.

FIG. 3 is a diagram showing a flow of a first receiving operation implementing the present invention.

FIG. 4 is a diagram showing a flow of a second receiving operation implementing the present invention.

FIG. 5 is a block diagram showing an AGC circuit of a conventional wireless communication device.

[Explanation of symbols]

 Reference Signs List 14 AGC circuit 15 Demodulation circuit 16 Received signal detection circuit 17 CIR measurement circuit 18 AGC control circuit 21 Gain variable circuit 22 Level measurement circuit 23 Gain control circuit 24 Storage circuit

Claims (12)

[Claims] 1. A gain control means, a measurement means for measuring the quality of a received signal, and a setting means for setting a gain of the gain control means after the reception of the received signal is completed, according to the measured quality. A wireless communication device and a wireless communication system, comprising: 2. The wireless communication apparatus and wireless communication system according to claim 1, wherein said measuring means measures a signal-to-interference power ratio as reception quality. 3. The wireless communication apparatus and wireless communication system according to claim 1, wherein said measuring means measures a reception error rate as reception quality. 4. The gain control means includes: a gain variable means for amplifying or attenuating a received signal level; a means for detecting an output level of the gain variable means; a gain variable control means for controlling the gain variable means; 2. The wireless communication device and wireless communication system according to claim 1, further comprising storage means for storing a control value of said variable gain control means. 5. The variable gain control means stores a control value of the variable gain control means in the storage means when a reception quality higher than a reference value is detected by the measuring means. Item 5. The wireless communication device and the wireless communication system according to Item 4. 6. The storage device according to claim 1, wherein the setting unit detects the reception quality higher than a reference value by the measurement unit, or receives a desired signal first after the storage unit is initialized. 5. The wireless communication apparatus and wireless communication system according to claim 4, wherein a control value of said variable gain control means is stored in said means. 7. The apparatus according to claim 1, wherein said measuring means measures reception quality of the spread spectrum signal.
A wireless communication device and a wireless communication system according to any one of the above. 8. A gain setting method comprising: measuring reception quality; and setting a gain after reception is finished according to the measured reception quality. 9. The gain setting method according to claim 8, wherein a signal-to-interference power ratio is measured as the reception quality. 10. The gain setting method according to claim 8, wherein a reception error rate is measured as reception quality. 11. If the measured reception quality is higher than a reference value, a gain is set according to the received signal. If the measured reception quality is lower than the reference value, the gain is returned to the gain before receiving the signal. 9. The gain setting method according to claim 8, wherein: 12. A storage medium storing a program for judging reception quality and setting a gain after reception according to the reception quality.