JP2004328071A - Receiver, control method of receiver and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver which performs the AGC by evaluating the RSSI without using an IC for directly obtaining the RSSI from the amplitude of a received signal. <P>SOLUTION: A measuring unit 2 calculates the output signal intensity information I<SP>2</SP>+ Q<SP>2</SP>from level information of I-signals and level information of Q-signals. A memory 5 has stored the RSSI and correspondence information indicating the correspondence of control level information CL to the output signal intensity information I<SP>2</SP>+ Q<SP>2</SP>. An RSSI evaluator 4 retrieves a stored RSSI value corresponding to the output signal intensity information I<SP>2</SP>+ Q<SP>2</SP>measured by the measuring unit 2 and the control level information CL given by a gain adjuster 3 from the memory 5, and presents the retrieved RSSI value to the gain adjuster 3 and a controller 70. The gain adjuster 3 adjusts the control level information CL according to the presented RSSI value so as to make the output signal intensity information I<SP>2</SP>+ Q<SP>2</SP>approach to an expected target value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for evaluating the strength of a received signal and controlling the gain of a variable gain amplifier that amplifies the received signal according to the evaluated strength.
[0002]
[Prior art]
When starting wireless communication using a predetermined frequency channel, a conventional wireless communication device receives a signal on the frequency channel and measures the strength of the signal. If the measured strength of the received signal is equal to or less than a predetermined threshold value, it is determined that the frequency channel is not being used by another wireless communication device, and wireless communication is started using the frequency channel by itself. I do.
[0003]
In addition, the strength of a received signal is measured even after the start of wireless communication, and the gain of a variable gain amplifier that amplifies the received signal is automatically controlled (AGC: Automatic Gain Control) according to the measured strength of the received signal. , The output level of the variable gain amplifier is maintained at a constant level at which a good dynamic range can be obtained.
The strength of the received signal measured here is indicated by an index called RSSI (Received Signal Strength Indicator).
[0004]
A conventional wireless communication device includes an IC (Integrated Circuit) for measuring RSSI, and directly obtains RSSI from the amplitude of a received signal using the IC. As an IC that can be used for RSSI measurement, for example, there is an AD8310 manufactured by Analog Devices (see Non-Patent Document 1).
FIG. 6 shows a typical configuration of a wireless communication device including an IC 990 for measuring RSSI. If the IC 990 indicates the RSSI exceeding the predetermined threshold to the control unit 970, the control unit 970 gives up using the frequency channel.
[0005]
The gain adjuster 980 adjusts the received signal level control signal RXLC according to the RSSI to control the gain of the variable gain amplifier 940, so that even when the intensity of the received signal RX changes, the gain is supplied to the baseband unit 960. The I signal and the Q signal are maintained at a constant intensity at which a good dynamic range can be obtained.
[0006]
[Non-patent document 1]
"Fast, Voltage-Out DC-440 MHz 95 dB Logarithmic Amplifier AD8310", Rev. A, Analog Devices, Inc. , 1999, Product Data Sheet [0007]
[Problems to be solved by the invention]
However, in the wireless communication device of the related art, the IC provided for measuring the RSSI hinders a reduction in the number of components constituting the device. This is a problem in mobile phones and portable wireless information terminals that are strongly demanded to be reduced in size and weight.
[0008]
In view of the above problems, an object of the present invention is to provide an RSSI evaluation device and an RSSI evaluation method that evaluate RSSI without using an IC that directly obtains RSSI from the amplitude of a received signal.
[0009]
[Means for Solving the Problems]
(1) In order to solve the above problem, a receiving apparatus according to the present invention is a receiving apparatus that is configured using variable gain amplifying means for controlling the gain according to the level of a control signal and amplifying the received signal, A level of a control signal, a strength of a received signal, and storage means for storing correspondence information indicating a correspondence between the strength of an output signal from the variable gain amplifying means and the variable gain amplifying means. Measuring means for measuring the strength of the output signal, and the level of the control signal given to the variable gain amplifying means, the strength of the received signal indicated by the correspondence information corresponding to the measured strength, An evaluation unit for evaluating the obtained received signal strength as an actual received signal strength, and a gain adjusting unit for adjusting the level of the control signal according to the evaluated received signal strength are provided.
(2) Further, the storage unit stores the intensity value of the received signal in correspondence with each of a plurality of different combinations of the level value of the control signal and the intensity value of the output signal. The level value of the control signal given to the variable gain amplifying means and the intensity value of the received signal stored in the storage means corresponding to the measured intensity value are searched, and the searched intensity value is calculated. It may be used to evaluate the actual received signal strength.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The receiving device according to the embodiment is configured using a variable gain amplifier whose gain is controlled according to the level of a control signal and amplifies the received signal.
The receiving device stores the correspondence information indicating the correspondence between the level of the control signal, the intensity of the received signal, and the intensity of the output signal from the variable gain amplifying unit, and the output from the variable gain amplifier. The RSSI is evaluated with reference to the correspondence information from the signal level and the control signal level, and control is performed so as to give a good dynamic range to the output signal from the variable gain amplifier according to the evaluated RSSI. Adjust the signal level.
(overall structure)
FIG. 1 is a block diagram showing the overall configuration of the receiving apparatus according to the present embodiment.
[0011]
The receiving device includes an antenna 10, an RF amplifier 20, a frequency converter 30, a variable gain amplifier 40, a D / A converter 41, a demodulation unit 50, A / D converters 51 and 52, a baseband unit 60, a measurement unit 2, a gain, It comprises an adjustment unit 3, an RSSI evaluation unit 4, a storage unit 5, and a control unit 70.
Here, the measurement unit 2, the gain adjustment unit 3, the RSSI evaluation unit 4, and the storage unit 5 specifically include a DSP (Digital Signal Processor) and a ROM (Read Only) that stores a program executed by the DSP. Memory), and the function of each unit is realized by the DSP executing the program.
[0012]
The received signal RX received by the antenna 10 is amplified by the RF amplifier 20, frequency-converted by the frequency converter 30 into an intermediate frequency signal, and then amplified by the variable gain amplifier 40. The demodulation unit 50 demodulates an output signal from the variable gain amplifier 40 into an I signal and a Q signal.
The A / D converters 51 and 52 digitally convert the I signal and the Q signal, respectively, and supply them to the baseband unit 60 and the measurement unit 2. The I signal and the Q signal after the digital conversion are time-series numerical information indicating respective signal levels.
[0013]
The baseband unit 60 supplies the digitally converted I signal and Q signal to, for example, an information processing unit (not shown). In another example, the baseband unit 60 converts the digital signal into an audio signal and emits it from a speaker (not shown).
The D / A converter 41 converts the control level information CL provided from the gain adjustment unit 3 into a reception signal level control signal RXLC, and supplies the received signal level control signal RXLC to the variable gain amplifier 40 as a gain control signal.
[0014]
The control unit 70 controls the operation of the entire receiving device.
(Details of I signal and Q signal)
As an example, the details of the I signal and the Q signal when the modulation method is π / 4 shift QPSK will be described.
FIG. 2 is a typical constellation chart of a π / 4 shift QPSK modulated I signal versus Q signal. The levels of the I and Q signals transition on the curves shown in this chart.
[0015]
FIG. 3 is a time displacement graph in which the square root value of the sum of squares of the levels of the I signal and the Q signal which transition in this manner is plotted in a time series. That is, it shows the time displacement of the square root value of the sum of squares of the I signal and the Q signal after the above-mentioned digital conversion.
(Details of receiving device)
The gain adjuster 3 first outputs an initial value of the control level information CL.
[0016]
The measuring unit 2 sums the squares of the level information of the I signal and the level information of the Q signal given from the A / D converters 51 and 52 at every predetermined sampling time, and outputs the output signal strength information I ² + Q ² is calculated. That is, time-series numerical information as shown in FIG. 3 is obtained.
The RSSI evaluation unit 4 uses the maximum value of the output signal strength information I ² + Q ² calculated within a predetermined time in the past by the measurement unit 2 and the latest control level information CL to store the correspondence stored in the storage unit 5. The strength RSSI of the received signal RX is evaluated with reference to the information.
[0017]
The storage unit 5 stores correspondence information indicating the correspondence among the strength RSSI of the received signal RX, the control level information CL, and the output signal strength information I ² + Q ² .
FIG. 4 shows a specific example of the correspondence information stored in the correspondence information table 100 in the storage unit 5.
The correspondence information table 100 includes an RSSI column 101, a CL column 102, and an I ² + Q ² column 103. The output obtained when the received signal RX having the strength indicated in the RSSI column is amplified by the gain indicated in the CL column. The signal strength is stored in the column I ² + Q ² . The correspondence information table 100 stores different combinations of RSSI values, CL values, and I ² + Q ² values in each of a plurality of rows. The correspondence information is obtained in advance outside the scope of the present invention, and is stored in the correspondence information table 100.
[0018]
The RSSI evaluator 4 determines whether the maximum value of the output signal strength information I ² + Q ² given within the past predetermined time from the measuring unit 2 matches the control level information CL given from the gain adjuster 3, respectively. Alternatively, the RSSI value stored in the row indicating the closest value is searched from the correspondence information table 100, and the searched RSSI value is presented to the gain adjustment unit 3 and the control unit 70.
[0019]
The RSSI evaluation unit 4 holds the RSSI information held in two rows each indicating a range including the output signal strength information I ² + Q ² provided from the measurement unit 2 and the control level information CL provided from the gain adjustment unit 3. Values may be searched, and values obtained by interpolating the values may be presented to the gain adjustment unit 3 and the control unit 70.
The gain adjuster 3 has a variable gain for amplifying the I signal and the Q signal to a level within a range in which the A / D converters 51 and 52 satisfactorily convert the digital signals (that is, a good dynamic range is given). The gain of the amplifier 40 is stored in advance corresponding to the RSSI value (not shown). Then, it outputs the control level information CL indicating the gain stored corresponding to the RSSI value presented from the RSSI evaluation unit 4.
[0020]
The control level information CL output from the gain adjustment unit 3 is converted into a gain control signal RXLC by the D / A converter 41 to control the gain of the variable gain amplifier 40. As a result, a good dynamic range is given to each of the I signal and the Q signal.
FIG. 5 is a flowchart illustrating a series of processes performed by the receiving device.
The gain adjustment unit 3 outputs an initial value of the control level information CL (S01).
[0021]
The measurement unit 2 calculates output signal strength information I ² + Q ² from the level information of each of the I signal and the Q signal provided from the A / D converters 51 and 52 (S02).
The RSSI evaluator 4 calculates the RSSI corresponding to the maximum value in the past predetermined time of the output signal strength information I ² + Q ² calculated by the measurement unit 2 and the latest control level information CL adjusted by the gain adjustment unit 3. A value is retrieved from the storage unit 5 (S03).
[0022]
The RSSI evaluation unit 4 presents the retrieved RSSI value to the gain adjustment unit 3 and the control unit 70 (S04).
The gain adjustment unit 3 outputs control level information CL that gives a good dynamic range to each of the I signal and the Q signal according to the RSSI value searched and presented by the RSSI evaluation unit 4 (S05).
[0023]
The receiving device repeats the processing of steps S02 to S05 (S06).
(Summary)
As described above, the receiving apparatus according to the present embodiment uses the software processing using the DSP to calculate the gain control signal given to the variable gain amplifier and the intensity of the output signal actually obtained from the variable gain amplifier. Referring to the correspondence information stored in advance, the RSSI of the received signal actually given to the variable gain amplifier is evaluated, and the gain of the variable gain amplifier is adjusted.
[0024]
According to this configuration, in a receiving device including a variable gain amplifier, an IC provided only for measuring RSSI is replaced by software processing by a DSP, and the IC can be omitted.
(Other modifications)
Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. The following cases are also included in the present invention.
(1) The present invention may be a computer program for realizing a method including the steps described in the embodiment using a computer system, or may be a digital signal representing the program.
[0025]
Further, the present invention may be a computer-readable recording medium on which the program or the digital signal is recorded, such as a flexible disk, a hard disk, a CD, an MO, a DVD, and a semiconductor memory.
Further, the present invention may be the computer program or the digital signal transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, or the like.
[0026]
Further, the program or the digital signal may be recorded on the recording medium and transferred, or may be transferred via the network or the like, and may be implemented in another independent computer system.
(2) In the embodiment, the example in which the correspondence information is stored in the table as a combination of each specific value of RSSI, CL, and I ² + Q ² has been described, but the expression form of the correspondence information is limited to the format. Not done.
[0027]
For example, the correspondence relationship information, RSSI, CL, and I may be held in relation of the type established between the ^{2 +} Q ^2, to the relational expression, a control level information CL adjusted by the gain adjusting unit 3, the measurement The RSSI may be calculated by substituting the output signal strength information I ² + Q ² calculated by the unit 2 and solving for the RSSI.
(3) In the embodiment, in order to evaluate the RSSI value, the maximum value of the output signal strength information I ² + Q ² calculated in the past predetermined time is used, but the output calculated in the past predetermined time is used. may be used an average value of the signal strength information I ^{2 +} Q ² (so-called moving average), in synchronism with the arrival time of the symbol points can be used the values of the output signal intensity is sampled information I ^{2 +} Q ^2.
(4) In addition, when a time-division multiplexing access method is adopted as a communication method and a fixed symbol sequence is communicated at the beginning of each time slot, for example, in a preamble portion, the control level information CL is adjusted only in that portion. May be.
[0028]
In this part, since the control level information CL can be adjusted based on the fixed symbol sequence, an improvement in adjustment accuracy can be expected.
(5) The gain adjuster 3 adjusts the control level information CL according to the RSSI value evaluated by the RSSI evaluator 4, but the adjustment by this method and the maximum value of the output signal strength information I ² + Q ² Adjustment by feedback control for adjusting the control level information CL so as to approach a predetermined target value may be switched.
[0029]
As a specific example of this switching, in a communication using a time division multiple access system as a communication system, a control channel to which a time slot is allocated at a longer interval than a link channel is used in accordance with the RSSI value evaluated by the RSSI evaluation unit 4. In this case, the control level information CL may be adjusted by the control, and the adjustment by the feedback control may be performed on the link channel.
[0030]
Further, the control level information CL may be adjusted according to the RSSI value evaluated by the RSSI evaluation unit 4 until the time variation of the RSSI value converges within a predetermined range, and after the convergence, adjustment by feedback control may be performed. Good.
[0031]
【The invention's effect】
The receiving apparatus according to the present invention is a receiving apparatus in which the gain is controlled in accordance with the level of the control signal and the variable gain amplifying means for amplifying the received signal is used. And storage means for storing correspondence information indicating the correspondence between the intensity of the output signal from the variable gain amplifying means, and measurement means for measuring the intensity of the output signal obtained from the variable gain amplifying means. The level of the control signal given to the variable gain amplifying means, and the strength of the received signal indicated by the correspondence information corresponding to the measured strength, and the obtained strength of the received signal is actually calculated. Evaluating means for evaluating the strength of the received signal, and gain adjusting means for adjusting the level of the control signal according to the evaluated strength of the received signal are provided.
[0032]
According to this configuration, from the gain control signal given to the variable gain amplifier and the intensity of the output signal actually obtained from the variable gain amplifier, the variable gain amplifier The RSSI of the actually received signal is evaluated to adjust the gain of the variable gain amplifier. Since this configuration can be realized as a digital signal processing function using a DSP, a conventional IC that directly obtains RSSI from the amplitude of a signal is replaced with a DSP that realizes the function, thereby eliminating the need for the conventional IC. By evaluating the RSSI, the gain of the variable gain amplifier can be adjusted.
[0033]
A recent receiving apparatus digitally processes various signal processings such as AGC control for maintaining a received signal at a constant strength at which a good dynamic range can be obtained by using a DSP. Can be realized without increasing the number of components by adding a DSP program in such a receiving apparatus.
In addition, since this configuration considers the output signal actually obtained from the variable gain amplifier, the RSSI is evaluated even in a state where the output signal does not converge to the target strength, that is, in a transient state, and the variable gain amplifier is evaluated. Gain can be adjusted. Therefore, the present invention can be applied favorably even when the duration is relatively short and sufficient convergence cannot be obtained during the duration, such as a received signal in a control channel.
[0034]
The output signal obtained from the variable gain amplifying means is quadrature-demodulated into an I signal and a Q signal, and the measuring means calculates the sum of squares of the levels of the I signal and the Q signal, thereby obtaining the measurement result. May be performed.
This configuration is suitable for a wireless device adopting the quadrature modulation / demodulation method.
Further, the storage unit stores the intensity value of the received signal corresponding to each of a plurality of different combinations of the level value of the control signal and the intensity value of the output signal, and the evaluation unit includes the variable gain amplifier. Searching for the intensity value of the received signal stored in the storage means corresponding to the level value of the control signal given to the means and the measured intensity value, and using the searched intensity value to determine the actual value. May be evaluated.
[0035]
According to this configuration, the correspondence information is stored in a table in the form of a combination of specific values and searched, so that it is suitable for implementation using a computer program.
The method for controlling a receiving apparatus according to the present invention is a method for controlling a receiving apparatus, wherein a gain is controlled according to a level of a control signal, and the variable gain amplifying unit amplifies the received signal. Is executed using the correspondence information indicating the correspondence between the strength of the received signal and the strength of the output signal from the variable gain amplifying means, and measures the strength of the output signal obtained from the variable gain amplifying means. A measuring step, a level of the control signal given to the variable gain amplifying unit, and a strength of the reception signal indicated by the correspondence information corresponding to the measured strength, and a strength of the obtained reception signal. And a gain adjusting step of adjusting the level of the control signal in accordance with the estimated strength of the received signal.
[0036]
By controlling the receiving device using this method, the same effect as described above can be obtained.
The program according to the present invention is a computer-executable program for controlling a receiving device in which a gain is controlled in accordance with a level of a control signal and configured using a variable gain amplifying means for amplifying a received signal, The processing is performed using correspondence information indicating the correspondence between the signal level, the strength of the received signal, and the strength of the output signal from the variable gain amplifying means, and the strength of the output signal obtained from the variable gain amplifying means. Measuring the level of the control signal given to the variable gain amplifying means, the strength of the received signal indicated by the correspondence information corresponding to the measured strength, An evaluation step of evaluating the signal strength as the actual received signal strength; and a gain adjusting step of adjusting the level of the control signal according to the evaluated received signal strength. To execute and up to a computer.
[0037]
By controlling the receiving device using this program, the same effects as described above can be obtained.
[Brief description of the drawings]
FIG. 1 shows the overall configuration of a receiving device.
FIG. 2 is a constellation chart in π / 4 shift QPSK modulation.
FIG. 3 is a time-series displacement graph of a square root value of a sum of squares of an I signal and a Q signal.
FIG. 4 is a specific example of correspondence information.
FIG. 5 is a flowchart illustrating an example of a process performed by the receiving device.
FIG. 6 shows a typical configuration example of a conventional receiving apparatus.
[Explanation of symbols]
2 Measurement unit 3 Gain adjustment unit 4 RSSI evaluation unit 5 Storage unit 10 Antenna 20 RF amplifier 30 Frequency converter 40 Variable gain amplifier 41 D / A converter 50 Demodulation unit 51, 52 A / D converter 60 Baseband unit 70 Control unit 100 Correspondence information table 101 RSSI column 102 CL column 103 I ² + Q ² column 940 Variable gain amplifier 960 Baseband unit 970 Control unit 980 Gain adjustment unit 990 IC

Claims (5)

A gain is controlled according to the level of the control signal, a receiving device configured using variable gain amplifying means for amplifying the received signal,
Storage means storing correspondence information indicating the correspondence between the level of the control signal, the strength of the received signal, and the strength of the output signal from the variable gain amplifying means,
Measuring means for measuring the intensity of the output signal obtained from the variable gain amplifying means,
The level of the control signal supplied to the variable gain amplifying means and the strength of the received signal indicated by the correspondence information are determined in correspondence with the measured strength, and the determined strength of the received signal is actually received. An evaluation means for evaluating the strength of the signal;
A receiving apparatus comprising: gain adjusting means for adjusting a level of the control signal according to the evaluated strength of the received signal. An output signal obtained from the variable gain amplifying means is quadrature demodulated into an I signal and a Q signal,
The receiving apparatus according to claim 1, wherein the measuring unit performs the measurement by calculating a sum of squares of the levels of the I signal and the Q signal. The storage unit stores the intensity value of the received signal, corresponding to each of a plurality of different combinations of the level value of the control signal and the intensity value of the output signal,
The evaluation unit searches for the intensity value of the received signal stored in the storage unit corresponding to the level value of the control signal given to the variable gain amplification unit and the measured intensity value. 3. The receiving apparatus according to claim 1, wherein the strength of the actual received signal is evaluated using the searched strength value. A gain is controlled according to the level of the control signal, a control method of the receiving apparatus configured using a variable gain amplifying means for amplifying the received signal,
The level of the control signal, the strength of the received signal, and executed using the correspondence information indicating the correspondence between the strength of the output signal from the variable gain amplifying means,
A measuring step of measuring the intensity of the output signal obtained from the variable gain amplifying means,
The level of the control signal supplied to the variable gain amplifying means and the strength of the received signal indicated by the correspondence information are determined in correspondence with the measured strength, and the determined strength of the received signal is actually received. An evaluation step of evaluating the signal strength;
A gain adjusting step of adjusting the level of the control signal according to the evaluated strength of the received signal. The gain is controlled according to the level of the control signal, a computer-executable program for controlling the receiving device configured using a variable gain amplifying means to amplify the received signal,
The level of the control signal, the strength of the received signal, and executed using the correspondence information indicating the correspondence between the strength of the output signal from the variable gain amplifying means,
A measuring step of measuring the intensity of the output signal obtained from the variable gain amplifying means,
The level of the control signal supplied to the variable gain amplifying means and the strength of the received signal indicated by the correspondence information are determined in correspondence with the measured strength, and the determined strength of the received signal is actually received. An evaluation step of evaluating the signal strength;
A gain adjusting step of adjusting a level of the control signal according to the evaluated strength of the received signal.

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