JPH09149012A - Diversity receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a receiver without deteriorating reception sensitivity. SOLUTION: Reception equalization sections 20A, 20B conduct digital demodulation processing and equalization processing of a reception signal and an adder section 30 synthesizes equalization outputs. An identification section 40 identifies and recovers the synthesis signal and a delay section 60 and a multiplier section 70 are used to feed back the identification recovery signal to the adder section 30. A coefficient update section 80 generates a coefficient for multiplication so as to reduce the equalization error. An equalization error detection section 90 detects an equalization error. A control section 100 inhibits the use of the reception equalization section 20B when the equalization error is less than a 1st value in the diversity reception state immediately and when the equalization error is higher than a 2nd value in this state, the use inhibit state is released immediately. Furthermore, the control section 100 reduce the power consumption of the reception equalizer section 20B in the state that a single reception is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combining type diversity receiver and a selecting type diversity receiver provided in a digital radio communication system.

[0002]

2. Description of the Related Art Generally, in a digital radio communication system, a diversity system is used as a reception system in order to prevent a decrease in code error rate due to frequency selective fading. In this diversity system, a plurality of diversity branches having a small correlation are set, and the reception signals of the plurality of diversity branches are used to suppress a decrease in the code error rate due to frequency selective fading.

The diversity method further includes a combining method and a selecting method. Here, the combining method is a method of combining received signals of a plurality of diversity branches in phase and outputting the combined signal as a received signal of a receiver. The selection method is a method in which the reception signals of a plurality of diversity branches are selectively selected and the selection signals are output as reception signals of the receiver.

In both of the conventional combining type and selection type diversity receivers, circuits of all diversity branches are always driven regardless of whether or not the influence of frequency selective fading is great. .

Further, in the conventional diversity receiver of the selection method, when the reception signals of a plurality of diversity branches are selectively selected, the reception signal of the diversity branch having a large input level is selected in a frame unit or the transmission frame. The known information is multiplexed on the above, the code error rate of this known information is counted,
The received signal of the diversity branch with the smallest code error rate has been selected for each frame.

[0006]

However, in the configuration in which all the diversity branch circuits are driven all the time, a high receiving sensitivity can be obtained, but the power consumption of the receiver increases.

Further, when the reception signals of a plurality of diversity branches are selectively selected, the configuration in which the reception signals of the diversity branches having a large input level are selected cannot necessarily improve the code error rate. there were. This is because in a communication system in which frequency selective fading is present, the code error rate is not always small when the input level of the received signal is high.

Further, in the case where the reception signals of a plurality of diversity branches are selectively selected, the configuration in which they are selected in transmission frame units can improve the code error rate when the digital radio communication system is a mobile communication system. There was a problem that I could not. This is because, in this case, the transmission line characteristics change momentarily.

Therefore, it is a first object of the present invention to provide a diversity receiver of the combining system which can reduce the power consumption of the receiver without lowering the receiving sensitivity.

A second object of the present invention is to provide a diversity receiver of the selection system which can reduce the power consumption of the receiver without lowering the receiving sensitivity.

A third object of the present invention is to provide a diversity receiver capable of improving the code error rate even when the transmission line characteristics fluctuate every moment.

[0012]

In order to solve the first problem, the first invention is an equalization for correcting the waveform distortion of the received signal for each diversity branch in the diversity receiver of the combining system. Means, a synthesizing means for synthesizing the reception signals of the plurality of diversity branches whose waveform distortion has been corrected by this equalizing means, and a synthesizing output of this synthesizing means,
Equalization error detection means for detecting the equalization error of the equalization means, and use of the predetermined diversity branch when the equalization error detected by the equalization error detection means becomes smaller than a predetermined first value. If the equalization error becomes larger than the second value, which is larger than the first value, in this prohibited state,
The use control means for releasing the use prohibition state and the power saving means for reducing the power consumption of the diversity branch whose use is prohibited by the use control means are provided.

In order to solve the second problem, a second invention is, in a diversity receiver of a selection system, an equalizing means for correcting a waveform distortion of a received signal for each diversity branch, and each diversity branch. For each, the equalization error detection means for detecting the equalization error of the equalization means, and when the equalization error of the predetermined diversity branch becomes smaller than the predetermined value, use of a predetermined diversity branch other than this diversity branch is prohibited. In this prohibition state, if the equalization error of the predetermined diversity branch becomes larger than the predetermined value,
The use control means for releasing the use prohibition state and the power saving means for reducing the power consumption of the diversity branch whose use is prohibited by the use control means are provided.

In order to solve the third problem, a third invention is, in a diversity receiver of a selection system, an equalizing means for correcting the waveform distortion of the received signal for each diversity branch, and each diversity branch. For each symbol, the equalization error detection means for detecting the equalization error of the equalization means, and for each symbol, the equalization error of the received signal of the diversity branch having the smallest equalization error detected by the equalization error detection means. And a selection means for selecting the encoded output or the identification reproduction output.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the first, second, and third inventions will be described below in detail with reference to the drawings.

[One Embodiment of the First Invention] First, the first
An embodiment of the invention will be described.

[Structure] FIG. 1 is a block diagram showing the structure of an embodiment of the first invention.

In FIG. 1, the first aspect of the present invention is a space for preventing a decrease in code error rate due to frequency selective fading by using received signals of a plurality of antennas arranged at spatially separated positions. A case where the present invention is applied to a diversity receiver will be described as a representative.

Further, FIG. 1 illustrates a case where the first invention is applied to a space diversity receiver provided with two diversity branches as a representative. Here, of the two diversity branches, A is added to the code of the component of the circuit of one diversity branch, and B is added to the code of the component of the circuit of the other diversity branch.

The combining type space diversity receiver shown in the figure has input terminals 10A and 10B and a reception equalizer section 20.
A, 20B, an addition unit 30, an identification unit 40, an output terminal 50, a delay unit 60, a multiplication unit 70, and a coefficient update unit 80.
And an equalization error detector 90 and a controller 100.

Here, the input terminal 10A is supplied with a signal which is received by one of two receiving antennas (not shown) and frequency-converted from a radio band to an intermediate frequency band by a frequency converter (not shown). Similarly, the input terminal 10
A signal received by the other antenna and frequency-converted from the wireless band to the intermediate frequency band by the frequency converter (not shown) is supplied to B.

The reception equalizer unit 20A has a function of performing digital demodulation (for example, quadrature detection) of the reception signal supplied to the input terminal 10A, a function of correcting waveform distortion of the reception signal, and the like. Similarly, the reception equalizer unit 20B also has a function of digitally demodulating the reception signal supplied to the input terminal 10B, a function of correcting waveform distortion of the reception signal, and the like.

The adder unit 30 includes reception equalizer units 20A and 20A.
It has a function of combining the output signals of B in-phase and combining the output signals of the multiplication unit 70 with them. Identification unit 40
Has a function of identifying the logical level of the output signal of the adder unit 30 on a symbol-by-symbol basis and reproducing the digital signal after the encoding process for wireless transmission. The output terminal 50 has
This identification reproduction signal is supplied.

The delay section 60 has a function of delaying the output signal of the identification section 40 for a predetermined time. The multiplication unit 70 has a function of multiplying the delay output of the delay unit 60 by the coefficient k5 generated by the coefficient updating unit 80 and supplying the result to the addition unit 30.

The coefficient updating unit 80 detects the equalization error by obtaining the difference between the output signal of the adding unit 30 and the output signal of the discriminating unit 40, and the multiplication unit 70 reduces the equalization error. Coefficient k5 and multiplying units 224A to 227 described later.
A, coefficients 224B to 227B k1A to k4A, k1B
It has a function of generating ~ k4B. This generation is performed based on, for example, the RLS (recursive least square error method) algorithm.

The equalization error detector 90 has a function of detecting an equalization error by obtaining the difference between the output signal of the adder 30 and the output signal of the discriminator 40.

The control unit 100 includes two reception equalizer units 20.
In the reception state using A and 20B (hereinafter referred to as "diversity reception state"), the equalization error detection unit 90
The equalization error detected by the first value TH1
As soon as it becomes smaller, the use of the reception equalizer unit 20B is stopped, and in this use disabled state, the equalization error is the first
When it becomes larger than the second value TH2 which is larger than the value TH1 of, the function has a function of releasing the use prohibition stop state immediately.

In other words, when the equalization error becomes smaller than the first value TH1 in the diversity reception state, the control section 100 immediately receives the reception state using only the reception equalizer section 20A (hereinafter, "single reception"). State)), and when the equalization error becomes larger than the second value TH2 in the state where the single reception state is set, the reception state is immediately returned to the diversity reception state.

Further, the control unit 100 has a function of reducing the power consumption of the reception equalizer unit 20B in the state where the single reception state is set. In this case, this power saving state may be set at the same time as the setting of the single reception state. However, in this embodiment, the equalization error is the second value TH2 in the state where the single reception state is set. If it is smaller, it is set for the first time. Also, in this case,
When the equalization error is smaller than the second value TH2, it is set immediately.

The use of the reception equalizer unit 20B is prohibited by, for example, cutting off the output of the reception equalizer unit 20B. Setting the power saving state of the reception equalizer unit 20B is performed, for example, by setting the power supply of the reception equalizer unit 20B to the cutoff state.

The reception equalizer section 20A includes a reception section 21A and
It has a transversal filter unit 22A.

Here, the receiving section 21A has an input terminal 10A.
It has a function of automatically amplifying the received signal supplied to the device to a predetermined level, a function of removing unnecessary components from the amplified output, a function of digitally demodulating the removed output. The transversal filter unit 22A includes the receiving unit 21.
It has a function of correcting the waveform distortion of the A output signal.

Although not described in detail, the reception equalizer unit 20B also has a reception unit 21B and a transversal filter unit 22B.

The transversal filter unit 22A includes a plurality of delay units 221A to 223A and a plurality of multiplication units 224.
A to 227A and an addition unit 228. The number of delay units and the number of multiplication units are determined based on the transmission path characteristics of wireless signals. In the figure, the case where three delay units and four multiplication units are provided is shown as a representative.

Here, the delay sections 221A to 223A have a function of delaying the output signal of the reception section 21A to generate four reception signals having different phases. The delay time of each of the delay units 221A to 223A is usually 1
It is set to a symbol long time or a half symbol long time. The multiplying units 224A to 227A apply the coefficients k1A, k generated by the coefficient updating unit 80 to the corresponding received signals.
It has a function of multiplying 2A, k3A, and k4A. The addition unit 228A has a function of combining the multiplication outputs of the multiplication units 224A to 227A.

Although not described in detail, the transversal filter unit 22B also includes three delay units 221B to 221B.
223B, four multiplication units 224B to 227B, and an addition unit 228B.

The above is the configuration of the embodiment of the first invention. In the above configuration, the transversal filter units 22A and 22B and the coefficient updating unit 80 constitute an equalizer that corrects the waveform distortion of the received signal for each diversity branch. A diversity combining decision feedback equalizer is configured by adding the addition unit 30, the delay unit 60, and the multiplication unit 70 to this.

[Operation] The operation of the above configuration will be described. First, the operation of the entire receiver shown in FIG. 1 will be described.

The received signal supplied to the input terminal 10A is
The reception equalizer unit 20A receives digital demodulation processing, equalization processing, and the like. As a result, the received signal is frequency-converted from the intermediate frequency band to the base band, and the waveform distortion is corrected so that the frequency characteristic becomes flat. Similarly,
The reception signal supplied to the input terminal 10B is also subjected to digital demodulation processing, equalization processing, and the like by the reception equalizer unit 20B.

The output signals of the reception equalizer sections 20A and 20B are combined by the adding section 30 in a phase-matched state. At this time, the identification reproduction signal output from the identification section 40 is also combined together via the delay section 60 and the multiplication section 70 in order to improve the equalization accuracy.

This combined signal is supplied to the identifying section 40, the coefficient updating section 80, and the equalization error detecting section 90. Identification unit 4
The combined signal supplied to 0 has a logic level identified for each symbol. As a result, the digital signal that has been subjected to the encoding process for wireless transmission is reproduced.

This identification reproduction signal is supplied to the output terminal 50, the delay section 60, the coefficient updating section 80, and the equalization error detecting section 90. The identification reproduction signal supplied to the output terminal 50 is supplied to a decoding unit (not shown) and is decoded. As a result, the digital signal before undergoing the encoding process for wireless transmission is reproduced.

The identification reproduction signal supplied to the delay unit 60 is
After being delayed for a predetermined time, the data is supplied to the multiplication unit 70. The identification reproduction signal supplied to the multiplication unit 70 is supplied to the addition unit 30 after being multiplied by the coefficient k5 generated by the coefficient update unit 80. The identification reproduction signal supplied to the adder 30 is
It is combined with the output signals of the reception equalizer units 20A and 20B.
By this feedback action, a synthetic signal with high equalization accuracy can be obtained.

The coefficient updating unit 80 detects the equalization error by obtaining the difference between the output signal of the adding unit 30 and the output signal of the discriminating unit 40, for example, in symbol units, and reduces the equalization error. , The coefficient k5 of the multiplication unit 70 and the multiplication unit 22
4A to 227A and 224B to 227B coefficients k1A to k
4A, k1B to k4B are obtained. Thereby, the addition unit 3
A composite signal with a small equalization error is obtained from 0.

The equalization error detector 90 detects the equalization error by obtaining the difference between the output signal of the adder 30 and the output signal of the discriminator 40, for example, in symbol units. This detection signal is supplied to the control unit 100.

When the equalization error becomes smaller than the first value TH1 in the diversity reception state, the control unit 100
Immediately, the output of the reception equalizer unit 20B is cut off. As a result, use of the reception equalizer unit 20B is prohibited. As a result, the reception state is changed from the diversity reception state to the single reception state.

In this use prohibited state, if the equalization error is smaller than the second value TH2, the control section 100 immediately
The power of the reception equalizer unit 20B is cut off. As a result, the power consumption of the reception equalizer unit 20B is reduced. In this case, the power consumption is 0. As a result, the power consumption of the space diversity receiver is reduced.

In this state, the equalization error is the second value T
When it becomes larger than H2, the control unit 100 immediately releases the cutoff state of the output of the reception equalizer unit 20B. As a result, the use prohibited state of the reception equalizer unit 20B is released.
As a result, the reception state is returned from the single reception state to the diversity reception state.

Along with this, the control unit 100
The power of the reception equalizer unit 20B is turned on. As a result, the power consumption of the reception equalizer unit 20B is returned to the original power consumption.

The control operation of the control unit 100 described above is shown in FIG.
This will be described with reference to FIG. 2 is a characteristic diagram showing the relationship between the equalization error and the code error rate in the diversity reception state and the single reception state.

In the figure, CE is the code error rate when the equalization error is the second value TH2. This code error rate CE is set to at least the allowable minimum code error rate.

Now, it is assumed that the equalization error is E1 in the diversity reception state. In this state, if the transmission line characteristic is improved, the equalization error is reduced. As a result, it is assumed that the equalization error becomes E2. In this case, the point on the characteristic curve moves from a to b.

If the equalization error E2 is smaller than the first value TH1, the reception state is immediately switched from the diversity reception state to the single reception state. In this state, the equalization error is usually larger than in the diversity reception state. As a result, it is assumed that the equalization error becomes E3. In this case, the point on the characteristic curve moves from b to c. If the equalization error E3 is smaller than the second value TH2, the reception equalizer unit 20B is immediately set to the power saving state. This reduces the power consumption of the receiver.

In this state, if the transmission line characteristics deteriorate, the equalization error increases. As a result, the equalization error E4
Let's say In this case, the point on the characteristic curve moves from c to d.

If the equalization error E4 is larger than the second value TH2, the code error rate is larger than CE. But,
In this case, the reception state is immediately returned from the single reception state to the diversity reception state. As a result, the point on the characteristic curve moves from d to e. As a result, the equalization error is
It is set to, for example, E5, which is smaller than the second value TH2. As a result, the code error rate is set to a value smaller than CE.

The above is the overall operation of FIG. Next, the operation of the reception equalizer unit 20A will be described.

The received signal in the intermediate frequency band supplied to the input terminal 10A is supplied to the receiver 21A, amplified to a predetermined level, and then the unnecessary components are removed. Then, the received signal is digitally demodulated. As a result, a baseband received signal is obtained.

The received signal in the base band is supplied to the transversal filter unit 22A, and the waveform distortion is corrected so that the frequency band becomes flat. That is, the signal supplied to the transversal filter unit 22A is
First, the delay circuits 221A to 223A connected in series delay. As a result, four signals having different phases are obtained.

Each signal has a corresponding multiplication unit 224A to 224A.
7A and is multiplied by the coefficients k1A to k4A generated by the coefficient updating unit 80. The output of each multiplication is the addition unit 2
28A. As a result, a received signal having flat frequency characteristics can be obtained.

The above is the operation of the reception equalizer section 20A. Although detailed description is omitted, the reception equalizer unit 20
Similar operations are performed in B as well.

[Effect] According to this embodiment described in detail above, the following effects can be obtained.

(1) First, according to this embodiment, when the equalization error becomes smaller than the first value TH1 in the state where the diversity reception state is set, the reception state is immediately changed to the single reception state. Switch to, in this state,
When the equalization error is smaller than the second value TH2, the reception equalizer unit 20B is immediately set to the power saving state. Therefore, it is possible to reduce the power consumption of the receiver without lowering the reception sensitivity. You can

(2) According to this embodiment, when the power saving state is set, the single receiving state is first set instead of the simultaneous setting of the single receiving state. Since the equalization error is set only when the equalization error is smaller than the second value TH2, it is possible to quickly deal with the case where the equalization error temporarily becomes small for some reason.

That is, when setting the power saving state,
You may make it set simultaneously, when setting a single reception state. However, in this case, if the equalization error temporarily becomes small for some reason, it cannot be quickly dealt with. In this embodiment, this is
Since the power saving state is set by cutting off the power supply of the reception equalizer unit 20B, it is necessary to restart the power supply of the reception equalizer unit 20B in order to cancel the power saving state. It can be done because there is.

On the other hand, in this embodiment, in the state where the single reception state is set, the power saving state is set only when the equalization error is smaller than the second value TH2. When the error temporarily becomes small, the power saving state is not set. Thus, according to this embodiment, it is possible to promptly deal with the case where the equalization error temporarily becomes small for some reason.

[Other Embodiments of the First Invention] Although one embodiment of the first invention has been described in detail above, the first invention is limited to the above-described embodiment. Not something.

(1) For example, in the above embodiment, when setting the single reception state, the setting is made immediately when the equalization error becomes smaller than the first value TH1. However, the first invention may be set only when the predetermined condition is satisfied after the equalization error becomes smaller than the first value TH1.

Here, as the predetermined condition, for example, the condition that the equalization error is continuously smaller than the first value TH1 for a predetermined time and the average value of the equalization error for a predetermined time is the first. The value TH1 may be smaller than the value TH1.

With such a structure, it is possible to prevent the single reception state from being set by mistake when the equalization error temporarily becomes small for some reason.

(2) In the above embodiment, when setting the power saving state, if the equalization error is smaller than the second value TH2, the setting is made immediately. However, the first invention may be set only when the predetermined condition is satisfied after the equalization error becomes smaller than the first value TH1. The predetermined condition in this case may be as described above.

With such a structure, it is possible to more promptly deal with the case where the equalization error temporarily becomes smaller due to some cause than in the previous embodiment.

(3) Further, in the above embodiment, the case where the power saving state is set is first set when the equalization error is smaller than the second value TH2 in the single reception state. However, the first invention may be set at the same time when the single reception state is set.

This configuration is effective when the single reception state is set only when a predetermined condition is satisfied after the equalization error becomes smaller than the first value TH1 as in (1). This is because in such a case, even if the power saving state is set at the same time as the single reception state, it is possible to quickly deal with the case where the equalization error temporarily becomes small due to some cause. .

(4) In the above embodiment, when the reception state is changed from the single reception state to the diversity reception state, when the equalization error becomes larger than the second value TH2, it is changed immediately. Explained. However, the first invention may be set only when the predetermined condition is satisfied after the equalization error becomes smaller than the second value TH2. The predetermined condition in this case may be as described above.

With such a configuration, it is possible to prevent the reception state from being erroneously changed from the single reception state to the diversity reception state when the equalization error temporarily becomes large for some reason. it can.

(5) Further, in the above embodiment, the case of setting the power saving state is described by cutting off the power supply of the reception equalizer unit 20B. However, in the first invention, the power saving state may be set by another method. For example, the power saving state may be set by cutting off or thinning out the control clock of the transversal filter unit 22B.

(6) Further, in the above embodiment, the case where the first invention is applied to the space diversity receiver having two diversity branches has been described. However, the first invention can also be applied to a space diversity receiver having three or more diversity branches.

In this case, the use prohibition states of the diversity branches may be set one by one, or may be set collectively for a plurality of them. That is, assuming that there are now three diversity branches, in the former case, if the equalization error is smaller than the first value TH1, first, the first diversity branch is set to the disabled state, and in this state. If the equalization error is smaller than the first value TH1, the second diversity branch is set to the use prohibited state. On the other hand, in the latter case, if the equalization error is smaller than the first value TH1, the two diversity branches are set in the use prohibited state.

(7) Further, in the above embodiment, the case where the first invention is applied to the space diversity receiver has been described. However, the first invention can also be applied to diversity receivers other than the space diversity receiver.

(8) In the above embodiment, the case where the equalization error is detected in symbol units (symbol period) has been described. However, in the first aspect of the invention, the detection may be performed in a cycle longer than this.

(9) In the above embodiment, when the coefficient updating unit 80 updates the coefficient based on the equalization error,
The case of updating based on the equalization error detected independently of the equalization error detection unit 90 has been described. However, in the first aspect, the equalization error detected by the equalization error detection unit 90 may be used for detection. This is effective when both equalization error detection cycles are the same.

(10) In the above embodiment, the case of detecting the equalization error is described based on the equalized output signal of the information signal and the identification reproduction signal. However, according to the first aspect of the present invention, a known training signal is multiplexed in a predetermined cycle on the information signal, and based on the equalized output signal of the multiplexed training signal and the training signal output from the training signal generator, The equalization error may be detected.

According to such a configuration, since it is not affected by the identification reproduction error or the like, it is possible to improve the detection accuracy of the equalization error as compared with the configuration which detects the equalization error based on the identification reproduction signal. .

In the first aspect of the invention, the detection of the equalization error by the information signal and the detection of the equalization error by the training signal may be used together.

(11) In addition to this, the first invention is
Needless to say, various modifications can be made without departing from the spirit of the invention.

[Embodiments of Second and Third Inventions] Next, embodiments of the second and third inventions will be described.

[Structure] FIG. 3 is a block diagram showing the structure of an embodiment of the second and third inventions.

In FIG. 3 as well, similar to FIG. 1, a case where the second and third inventions are applied to a space diversity receiver having two diversity branches will be described as a representative.

The space diversity receiver of the selection system shown in the figure has input terminals 110A and 110B, reception equalizer sections 120A and 120B, a selection section 130, and a selection control section 1.
40, an output terminal 150, and a controller 160.

Here, the signals received by the corresponding receiving antennas and converted into the intermediate frequency band are supplied to the input terminals 110A and 110B. Reception equalizer unit 120A,
In addition to the digital demodulation function, the equalization function, etc., the 120B is provided with an identification reproduction function, an equalization error detection function, a coefficient updating function, etc. This is because, in the case of the selection method, it is necessary to generate a coefficient for equalization for each diversity branch.

The selection unit 130 includes a reception equalizer unit 120A,
It has a function of selectively selecting the identification reproduction signal of 120B. The selection control unit 140 includes reception equalizer units 120A and 12A.
It has a function of controlling the selection operation of the selection unit 130 based on the 0B equalization error detection signal.

The control unit 160 includes two reception equalizer units 12
In the diversity reception state using 0A and 120B, if the equalization error detected by the reception equalizer unit 120A becomes continuously smaller than the predetermined value TH for a predetermined time, the reception equalizer unit 20B Has a function of releasing the use prohibition state immediately when the equalization error becomes larger than the value TH11 in the use prohibition state.

In other words, the control section 100 sets the single reception state using only the reception equalizer section 20A when the equalization error continuously becomes smaller than TH for a predetermined time in the diversity reception state. In the state where this single reception state is set, when the equalization error becomes larger than TH, it has a function of immediately returning the reception state to the diversity reception state.

Further, the control unit 100 has a function of reducing the power consumption of the reception equalizer unit 20B in the state where the single reception state is set. In this case, the power saving state is set at the same time as the setting of the single reception state, and is released at the same time as the release of the single reception state.

The setting of the reception equalizer unit 20B to the use prohibited state is performed by, for example, prohibiting the selection of the reception equalizer unit 20B in the selection unit 130. For this reason, in this embodiment, the control unit 160 gives the selection control unit 140 a control signal for instructing prohibition of the selection of the reception equalizer unit 20B. Setting the reception equalizer unit 20B to the power saving state is performed by setting the power supply of the reception equalizer unit 20B to the cutoff state.

The reception equalizer section 120A has a reception section 121A.
, Transversal filter unit 122A, and identification unit 1
23A, a delay unit 124A, a multiplication unit 125A, a coefficient update unit 126A, and an equalization error detection unit 127A.

Here, the receiving unit 121A has an amplifying function, a filtering function, and the like as the receiving unit 21A of FIG.
It has a digital demodulation function. The transversal filter unit 122A has an equalizing function similarly to the transversal filter unit 22A in FIG.

The identifying section 123A identifies the logical level of the equalized output signal of the transversal filter section 122A,
It has a function of reproducing a digital signal after encoding processing for wireless transmission.

The delay unit 124A has a function of delaying this identification reproduction signal, and the multiplication unit 125A has a function of multiplying this delay signal by a coefficient k5A and feeding it back to the addition unit 1227A of the transversal filter unit 122A.

The coefficient updating unit 126A detects the equalization error by obtaining the difference between the output signal of the transversal filter unit 122A and the output signal of the identification unit 123A, for example, in symbol units, and this equalization error is detected. The coefficient k5 of the multiplication unit 125A and the multiplication unit 122, which will be described later, are reduced so that
It has a function of generating coefficients k1A to k4A of 4A to 1227A.

The equalization error detection unit 127A obtains the difference between the output signal of the transversal filter unit 122A and the output signal of the identification unit 123A on a symbol-by-symbol basis.
It has a function to detect equalization error.

The reception equalizer section 120B is not described in detail, but the reception section 12 is similar to the reception equalizer section 120A.
1B, a transversal filter unit 122B, an identification unit 123B, a delay unit 124B, a multiplication unit 125B,
The coefficient updating unit 126B and the equalization error detecting unit 127B are included.

The transversal filter section 122A is
Although detailed description is omitted, like the transversal filter unit 22A of FIG. 1, the three delay units 1221A to 1221A to 1212 are provided.
23A, four multiplication units 1224A to 1227A, and an addition unit 1228.

The transversal filter section 122B is
Although detailed description is omitted, like the transversal filter unit 122A, the three delay units 1221B to 1223 are provided.
B, four multiplication units 1224B to 1227B, and an addition unit 1228.

The above is the configuration of one embodiment of the second and third inventions.

[Operation] The operation of the above configuration will be described.

The reception signal supplied to the input terminal 110A is subjected to digital demodulation processing, equalization processing, identification reproduction processing, etc. by the reception equalizer section 120A. This allows
The digital signal after being encoded for wireless transmission is reproduced. Similarly, the reception signal supplied to the input terminal 110B is also subjected to digital demodulation processing, equalization processing, identification reproduction processing, etc. by the reception equalizer section 120B.

The identification reproduction signals of the reception equalizer sections 120A and 120B are supplied to the selection section 130, and one having a smaller equalization error is selected. This selection signal is supplied to the output terminal 150 and decoded by a decoding unit (not shown).

The selection operation of the selection unit 130 is controlled by the selection control unit 160 based on the equalization error detected by the equalization error detection units 127A and 127B. Here, the equalization error detection units 127A and 127B detect the equalization error in symbol units. In accordance with this, the selection control unit 140 controls the selection operation of the selection unit 130 in symbol units. By this means, it is possible to improve code errors even when the transmission path characteristics change momentarily.

The equalization error detected by the equalization error detector 127A is further supplied to the controller 140. In the diversity reception state, the control unit 140 instructs the selection control unit 140 to prohibit the selection of the reception equalizer unit 120B when the equalization error continuously becomes smaller than the predetermined value TH for a predetermined time.

Upon receiving this instruction, the selection control unit 140 controls the selection operation of the selection unit 130 so that the identification reproduction signal of the reception equalizer unit 120B is not selected. That is, the selection operation of the selection unit 140 is controlled so that the selection signal of the selection unit 140 is fixed to the identification reproduction signal of the reception equalizer unit 120A. In this case, when the identification reproduction signal of the reception equalizer unit 120B is selected by the selection unit 130, the selection signal is changed from the identification reproduction signal of the reception equalizer unit 120B to the identification reproduction signal of the reception equalizer unit 120A. Fix after switching.

As a result, the use of the reception equalizer section 120B is prohibited. As a result, the reception state is switched from the diversity reception state to the single reception state.

At the same time, the control section 160 shuts off the power supply of the reception equalizer section 120B. As a result, the power consumption of the reception equalizer unit 120B is reduced. In this case, the power consumption is 0. As a result, the power consumption of the space diversity receiver is reduced.

In this state, if the equalization error becomes larger than TH, the control section 160 immediately causes the selection control section 14 to proceed.
0 is instructed to cancel the prohibition of the selection of the identification reproduction signal of the reception equalizer unit 120B.

Upon receiving this instruction, the selection control unit 140 controls the selection operation of the selection unit 130 so that the identification reproduction signal of the reception equalizer unit 120B is also selected. As a result, the use prohibited state of the reception equalizer unit 120B is released. As a result, the reception state is returned from the single reception state to the diversity reception state.

Along with this, the control section 160
The power of the reception equalizer unit 120B is turned on. This allows
The power consumption of the reception equalizer unit 120B is returned to the original power consumption.

The control operation of the above-mentioned control section 160 is shown in FIG.
This will be described with reference to FIG. 4. FIG. 4 is a characteristic diagram showing the relationship between the equalization error and the code error rate in the diversity reception state and the single reception state.

In the figure, the characteristic curve C1 shows the characteristic in the diversity reception state, and C2 shows the characteristic in the single reception state. CE is a code error rate on the characteristic curve C2 when the equalization error is TH. This code error rate CE is set to at least the allowable minimum code error rate.

Now, it is assumed that the equalization error is E1 in the diversity reception state. In this state, if the transmission line characteristic is improved, the equalization error is reduced. As a result, it is assumed that the equalization error becomes E2. In this case, the point on the characteristic curve moves from a to b on the characteristic curve C1.

If the equalization error E2 is continuously smaller than the first value TH1 for a predetermined time, the reception state is switched to the single reception state. As a result, the point on the characteristic curve moves from b on the characteristic curve C1 to c on the characteristic curve C2. At the same time, the reception equalizer unit 120B is set to the power saving state. This reduces the power consumption of the receiver.

In this state, if the transmission line characteristics deteriorate, the equalization error increases. As a result, the equalization error E3
Let's say In this case, the point on the characteristic curve moves from c to d on the characteristic curve C2.

If the equalization error E3 is larger than TH,
The code error rate is larger than CE. But in this case,
The reception state is returned to the diversity reception state. As a result, the point on the characteristic curve moves from d on the characteristic curve C2 to e on the characteristic curve C1. As a result, the bit error rate is C
It is set to a value smaller than E.

At the same time, the reception equalizer unit 120
The power saving state of B is released. As described above, the power consumption can be reduced without lowering the reception sensitivity.

The above is the overall operation of FIG. The operation of each unit of the reception equalizer units 120A and 120B is almost the same as the operation of the corresponding unit in FIG.

[Effects of the Embodiment of the Second Invention] According to the embodiment of the second invention described in detail above, the following effects can be obtained.

(1) First, according to this embodiment, when the diversity reception state is set and the equalization error becomes continuously smaller than the predetermined value TH for a predetermined time, the reception state is changed. Since the power state of the reception equalizer unit 120B is set to the power saving state while switching to the single reception state, the power consumption of the receiver can be reduced without lowering the reception sensitivity.

(2) According to this embodiment, when the power saving state is set, if the equalization error becomes smaller than TH, the state is not set immediately but this state continues for a predetermined time. Since the setting is made for the first time, it is possible to quickly deal with the case where the equalization error temporarily becomes small for some reason.

[Effect of Embodiment of Third Invention] According to the embodiment of the third invention described in detail above, the equalization error is detected in the unit of symbol, and the identification reproduction is performed by this detection output. Since the signal selection operation is controlled, the code error rate can be improved even when the transmission path characteristics fluctuate from moment to moment.

[Other Embodiments of the Second Invention] Although one embodiment of the second invention has been described in detail above, the second invention is limited to the above-described embodiment. Not something.

(1) For example, in the above embodiment, when the single reception state and the power saving state are set, it is only when the equalization error becomes smaller than the predetermined value TH continuously for a predetermined time. The case of setting is explained. However, this second
The invention may be set only when a condition other than the above is satisfied. For example, it may be set only when the average value of the equalization error for a predetermined time is smaller than TH.

(2) In the second aspect of the invention, the single reception state and the power saving state are not set when a predetermined condition is satisfied after the equalization error becomes smaller than TH.
It may be set as soon as the equalization error becomes smaller than TH.

(4) Further, in the above embodiment, when the reception state is changed from the single reception state to the diversity reception state, when the equalization error becomes larger than TH, it is immediately changed. However, the second invention may be set only when the predetermined condition is satisfied after the equalization error becomes larger than TH.

(5) Further, in the above embodiment, the case of setting the power saving state is described by cutting off the power supply of the reception equalizer unit 120B. However, in the second invention, as in the first invention, for example, the power saving state may be set by interrupting or thinning the control clock of the transversal filter unit 122B.

(6) Further, in the above embodiment, the case where the second invention is applied to the space diversity receiver having two diversity branches has been described. However, the second invention can also be applied to a space diversity receiver having three or more diversity branches, like the first invention.

(7) Further, in the above embodiment, the case where the second invention is applied to the space diversity receiver has been described. However, the second invention can also be applied to diversity receivers other than the space diversity receiver, as in the first invention.

(8) Further, in the above embodiment, the case where the equalization error is detected in the symbol unit (symbol period) has been described. However, in the second aspect of the invention, the detection may be performed in a cycle longer than this.

(9) In the previous embodiment, when the coefficient updating units 126A and 126B update the coefficient based on the equalization error, the equalization error detected independently of the equalization error detection unit 90 is detected. The case of updating based on is explained. But,
In the second aspect of the invention, the equalization error detected by the equalization error detector 90 may be used for detection.

(10) In the above embodiment, the case of detecting the equalization error is described based on the equalized output signal of the information signal and the identification reproduction signal. But,
In the second invention, similarly to the first invention, the known training signal may be used for detection.

(11) In addition to this, the second invention is
Needless to say, various modifications can be made without departing from the spirit of the invention.

[Other Embodiments of the Third Invention] The one embodiment of the third invention has been described above in detail. However, the third invention is limited to the above-described embodiment. Not something.

(1) For example, in the above embodiment, the case where the third invention is applied to the space diversity receiver having two diversity branches has been described. But,
The third invention can be applied to a space diversity receiver having three or more diversity branches as in the first invention.

(2) Further, in the above embodiment, the case where the third invention is applied to the space diversity receiver has been described. However, the third invention can also be applied to diversity receivers other than the space diversity receiver, as in the first invention.

(3) Further, in the above embodiment, when the coefficient updating units 126A and 126B update the coefficient based on the equalization error, the case where the equalization error is detected in the symbol unit (symbol period) is described. explained. However, in the third aspect of the invention, the detection may be performed in a cycle longer than this.

(4) In the above embodiment, when the coefficient updating units 126A and 126B update the coefficient based on the equalization error, the equalization error detected independently of the equalization error detection unit 90 is detected. The case of updating based on is explained. But,
In the third invention, the equalization error detection units 127A and 127A are
It may be updated based on the equalization error detected by B. However, this configuration has the coefficient updating unit 126.
A and 126B are limited to the case of updating the coefficient based on the equalization error detected in the symbol unit as in the previous embodiment.

(5) In the above embodiment, when the coefficient updating units 126A and 126B update the coefficient based on the equalization error, the equalization error is discriminated from the equalization output signal of the information signal and the discrimination reproduction signal. The case of detection based on However, in the third invention, the equalization error for updating the coefficient may be detected using a known training signal as in the first invention.

(6) Further, in the above embodiment, the case where the third invention is applied to the diversity receiver for selecting the identification reproduction output has been described. However, the third invention can also be applied to the diversity receiver that selects the equalized output.

(7) In addition to this, it goes without saying that the third invention can be variously modified and implemented without departing from the scope of the invention.

[0148]

As described above in detail, according to the first aspect of the invention, when the equalization error becomes smaller than the predetermined first value in the state where the diversity reception state is set,
The reception state is switched to the single reception state, and in this state, when the equalization error is smaller than the second value, the predetermined diversity branch is set to the power saving state, so that the reception sensitivity is not lowered, The power consumption of the receiver can be reduced.

According to the second invention, when the equalization error becomes smaller than a predetermined value in the state where the diversity reception state is set, the reception state is switched to the single reception state and the predetermined reception state is set. Since the diversity branch is set to the power saving state, the power consumption of the receiver can be reduced without lowering the reception sensitivity.

Further, according to the third aspect of the invention, the equalization error is detected in symbol units, and the selection operation of the identification reproduction signal is controlled based on the detection output, so that the transmission line characteristic changes every moment. Even if it fluctuates, the code error rate can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a first invention.

FIG. 2 is a characteristic diagram for explaining the operation of the embodiment of the first invention.

FIG. 3 is a block diagram showing a configuration of an embodiment of second and third inventions.

FIG. 4 is a characteristic diagram for explaining the operation of an embodiment of the second and third inventions.

[Explanation of symbols]

10A, 10B, 110A, 110B ... Input terminals 20A, 20B, 120A, 120B ... Reception equalizer section 30 ... Addition section 40, 123A, 123B ... Identification section 50, 150 ... Output terminals 60, 124A, 124B ... Delay section 70 , 125A, 125B ... Multiplying section 80, 126A, 126B ... Coefficient updating section 90, 127A, 127B ... Equalization error detecting section 100, 160 ... Control section 21A, 21B, 121A, 121B ... Receiving section 22A, 22B, 122A, 122B. ... Transversal filter unit 211A to 213A, 211B to 213B, 1211A
-1213A, 1211B-1213B ... Delay part 214A-217A, 214B-217B, 1214A
˜1217A, 1214B to 1217B ... Multiplier 218A, 218B, 1218A, 1218B ... Adder

Claims (3)

[Claims] 1. A combining type diversity receiver provided in a digital wireless communication system, wherein equalization means for correcting waveform distortion of a received signal is corrected for each diversity branch, and waveform distortion is corrected by this equalization means. The combining means for combining the received signals of the plurality of diversity branches, the equalization error detecting means for detecting the equalization error of the equalizing means based on the combined output of the combining means, and the equalization error detecting means. When the detected equalization error becomes smaller than the predetermined first value, the use of the predetermined diversity branch is prohibited, and in this use prohibited state, the equalization error is larger than the second value. When it becomes larger than the value, use control means for releasing this use prohibition state and power saving for reducing the power consumption of the diversity branch which is prohibited by this use control means Diversity receiver combining scheme, characterized in that a means. 2. A selection type diversity receiver provided in a digital wireless communication system, wherein equalization means for correcting waveform distortion of a received signal for each diversity branch, and said equalization means for each diversity branch. Equalization error detecting means for detecting the equalization error of, and when the equalization error of a predetermined diversity branch becomes smaller than a predetermined value, the use of a predetermined diversity branch other than this diversity branch is prohibited In this state, when the equalization error of the predetermined diversity branch becomes larger than the predetermined value, use control means for releasing the use prohibition state and consumption of the diversity branch prohibited by the use control means A diversity receiver of a selection method, which is provided with a power saving means for reducing power. 3. A selection type diversity receiver provided in a digital radio communication system, wherein equalization means for correcting waveform distortion of a received signal for each diversity branch and symbol unit for each diversity branch are provided. Equalization error detection means for detecting equalization error of the equalization means, and for each symbol, equalization output or identification reproduction of the reception signal of the diversity branch having the smallest equalization error detected by the equalization error detection means. A diversity receiver of a selection method, comprising: a selection unit that selects an output.