JP2782620B2 - Spread spectrum receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum receiver, and more particularly to a spread spectrum receiver capable of demodulating a received signal which is distorted by a transmission path involving multipath such as mobile communication.

[0002]

2. Description of the Related Art A communication system using a spread spectrum system and a CDMA (Co) system which is a multiple access system using the communication system.
The de Division Multiple Access communication system has the advantage that it is resistant to interference and interference and is less susceptible to multipath distortion. Also, a diversity effect can be expected by combining multipath components using a RAKE receiver,
Research and development for the purpose of application to mobile communication are being actively conducted.

Hereinafter, a conventional spread spectrum receiver using a RAKE receiver will be described with reference to the drawings. FIG. 3 is a block diagram of a conventional spread spectrum receiver. In FIG. 3, reference numerals 1, 2, and 3 denote demodulators operating at mutually independent phases, and reference numeral 5 denotes demodulated signals from demodulators 1 to 3. Is a symbol synthesizing device for synthesizing the phases by combining them. Reference numeral 6 denotes a transmission path state estimating unit. Reference numeral 7 denotes a determination unit that determines a signal that is a signal demodulated and combined by the symbol combining device 5. Reference numeral 11 denotes a received signal. This is the phase information of each ray of the multipath.

FIG. 2A shows the demodulation timing of each of the demodulators 1 to 3 in the spread spectrum receiver shown in FIG. Note that, in FIG.
Are the rays of the multipath, and their correlation levels are shown. Next, the operation of the spread spectrum receiver shown in FIG. 3 will be described with reference to FIG. The transmission path state estimating means 6 estimates the multipath state of the transmission path from the received signal 11. Specifically, by measuring the correlation level in each phase of the spread code, each of the rays 13 to 15 is measured.
Can be estimated.

The demodulators 1 to 3 perform demodulation in synchronization with the phase of each ray estimated by the transmission path state estimating means 6. In this case, since the number of demodulators is set to three, each of the demodulators 1, 2, and 3 respectively outputs the beam 13, 13 shown in FIG.
Demodulation is performed in synchronization with phases 4 and 15. The signals demodulated in each of the demodulators 1, 2, and 3 are subjected to maximum ratio combining in the symbol combiner 5, and the combined signal is determined by the determiner 7 to obtain demodulated data. The transmission path state estimating means 6 provides relative demodulation information of the beam 14 and the beam 15 to the demodulation device 2 and the demodulation device 3 with reference to the phase of the beam 13.
In each of the demodulation devices 1 to 3, demodulation can be performed in synchronization with the phases of the beams 13 to 15.

[0006]

However, in the above-mentioned conventional spread spectrum receiver, a multipath element wave whose delay amount is larger than the symbol interval exists, and the element wave has a small delay amount of the next symbol. When the beam overlaps with the ray, the two rays cannot be separated, so that there is a problem that the reception performance is deteriorated. That is, FIG.
As shown in (B), even if there is a ray 16 with a delay amount larger than the symbol interval, if there is no overlap with the ray for the next symbol, it can be demodulated separately. Although good reception characteristics can be obtained, as shown in FIG.
Exists and the ray overlaps with the ray 18 for the next symbol, the two rays cannot be separated, so that the ray for one symbol demodulates another symbol. In this case, the noise is added as noise, and the reception performance is degraded.

Therefore, the present invention improves the reception performance even when there is a multipath ray whose delay amount is larger than the symbol interval and the ray overlaps with a ray whose delay amount of the next symbol is small. It is an object of the present invention to provide a spread spectrum receiver that does not deteriorate.

[0008]

In order to achieve the above object, a spread spectrum receiver according to the present invention, in a receiver of a communication system using a spread spectrum system, detects a multipath state of a transmission path by a received signal. Channel state estimating means for estimating, a plurality of demodulators for independently demodulating in synchronization with each elementary wave of a multipath based on the channel state estimated by the channel state estimating means, and the plurality of demodulators A symbol combiner that combines the signal demodulated in step (1) and other symbols included in the signal demodulated by the symbol combiner.
Multipath cancels out unwanted multipath waves
Erasing means, a determiner for determining a signal output from the multipath erasing means , and a transmission path state determined by the transmission path state estimating means and a signal determined by the determiner. At least one of an undesired wave demodulator, the multipath erasing means for demodulating the unnecessary wave multipath adversely affecting other symbols contained in the received signal
Is earlier than the signal demodulated by the unnecessary wave demodulator.
It is designed to cancel unnecessary waves of the multipath.

According to another aspect of the present invention, there is provided a spread spectrum receiver for use in a communication system using a spread spectrum system, which estimates a multipath state of a transmission line based on a received signal. Estimating means, a plurality of demodulators for performing independent demodulation in synchronization with each elementary wave of a multipath based on the channel state estimated by the channel state estimating means, and signals demodulated by the plurality of demodulators And a symbol combiner that combines the symbols, and adversely affects other symbols included in the signal demodulated by the symbol combiner.
A multipath elimination means for canceling unnecessary multipath waves,
A determining unit that determines a signal output from the multipath erasing unit; and a reception quality measuring unit that measures reception quality using the signal output from the multipath erasing unit and the signal determined by the determining unit. Amplitude and phase control for generating a replica of a multipath unnecessary wave that adversely affects other symbols included in a received signal using the signal determined by the determiner and the reception quality information measured by the reception quality measurement unit and means, said multipath erasing means
Is the replica generated by the amplitude and phase control means.
Power to cancel the unwanted waves of the multipath.
ing.

According to another aspect of the present invention, there is provided a spread spectrum receiver for use in a communication system using a spread spectrum system, which estimates a multipath state of a transmission line based on a received signal. State estimating means, a plurality of demodulators for performing independent demodulation in synchronization with each elementary wave of the multipath based on the channel state estimated by the channel state estimating means, and demodulated by the plurality of demodulators A symbol combiner that combines signals and other symbols included in the signal demodulated by the symbol combiner are adversely affected.
Multipath elimination means to cancel unnecessary multipath waves
And a determiner for determining the signal output from the multipath canceling means , and a transmission path state obtained by the transmission path state estimating means and a signal included in the received signal using the signal determined by the determiner. And a plurality of unnecessary wave demodulators for demodulating multipath unnecessary waves that adversely affect the symbols of the symbols, and the reception quality is measured using the signal output from the multipath canceling unit and the signal determined by the determination unit. Reception quality measurement means, and amplitude / phase control means for generating a replica of the unnecessary multipath wave included in the reception signal using the signal determined by the determination unit and the reception quality information measured by the reception quality measurement means It equipped with a door, before
The multipath elimination means is restored by the unnecessary wave demodulator.
Tuned signal and generated by said amplitude and phase control means
Unnecessary waves of the multipath are hit by the replica
It is made to disappear.

According to the present invention, the demodulated data after the determination and the information obtained from the transmission path state estimating means, or the output of the symbol combining apparatus and the information on the reception quality obtained from the demodulated data which has determined the demodulated data, Alternatively, by using both pieces of information, a means is provided to cancel a multipath beam that adversely affects other symbols whose delay amount is larger than the symbol interval and overlaps with an adjacent symbol. Even if there is a delay ray to be given, it is possible to prevent the reception performance from deteriorating. Therefore, it is possible to realize a spread spectrum receiver with less deterioration in reception performance.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the spread spectrum receiver according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of a spread spectrum receiver according to the present invention. In this figure, 1, 2,
3 is a demodulation device that operates in a phase independent of each other, 4
Is an unnecessary wave demodulator for demodulating the unnecessary wave assigned by the transmission path state estimating means 6, 5 is a symbol combining device for combining the phases of the demodulated signals from the demodulators 1 to 3, and
Reference numeral 6 denotes a transmission path state estimating means for estimating the state of the transmission path by detecting each elementary wave of the multipath. Reference numeral 7 denotes a determinator for determining a demodulated and combined signal from which the multipath is removed as a symbol. .

8 is a reception quality measuring means for measuring the reception quality from the input and output of the decision unit 7, 9 is an amplitude and phase control means for generating a multipath replica to be removed from the demodulated data and the reception quality information, Reference numeral 10 denotes a multipath eliminator that removes a multipath component that adversely affects the output of the symbol synthesizer 5 based on information from the unnecessary wave demodulator 4 and the amplitude / phase controller 9. Further, reference numeral 11 denotes a received signal, and reference numeral 12 denotes phase information of each beam of the multipath obtained by the transmission path state estimating means 6. In FIG. 1, the number of demodulators is three and the number of unnecessary wave demodulators is one. However, the number of demodulators does not need to be particularly limited, and there are a plurality of multipath beams to be removed. At this time, a plurality of unnecessary demodulation devices may be provided.

FIG. 2 shows the demodulation timing of each of the demodulation devices 1 to 3 and the unnecessary wave demodulation device 4. FIG.
The correlation levels of three multipath rays 13 to 15 in a symbol are shown. FIG. 8B shows the correlation level of each multipath ray 13 to 16 with respect to a symbol at a certain time T and an adjacent time T + 1. The correlation level of each of the rays 17 to 20 of the multipath with respect to the symbol is shown. In this case, the rays 16 located within the interval between adjacent symbols beyond one symbol interval do not overlap with the rays 17 to 20 in the adjacent symbols. Also, (C)
Shows the correlation level of each elementary wave of the multipath with respect to the symbol at a certain time T and the time T + 1 adjacent to the time T, as in FIG. 7B. In this case, the correlation level exceeds one symbol interval. The ray 16 located within the interval between adjacent symbols overlaps with the ray 18 in the adjacent symbol.

In the spread spectrum receiving apparatus according to the present invention, the received signal 11 is input to demodulators 1 to 3, the unnecessary wave demodulator 4 and the transmission path state estimating means 6. The transmission path state estimating means 6 estimates the multipath state of the transmission path from the received signal 11. Specifically, by measuring the correlation level of the received signal 11 at each phase of the spread code generated from the built-in spread code generator, the received power level and phase of each ray are estimated.
The transmission path state estimating means 6 controls the demodulation of the demodulation devices 1 to 3 and the unnecessary wave demodulation device 4 according to the estimated multipath state.

Each of the demodulators 1 to 3 is assigned each ray so that each ray estimated by the transmission path state estimating means 6 is demodulated in synchronization with its phase. FIG.
In the example, since the number of demodulators is set to three, an elementary wave is allocated to each of the demodulators 1 to 3 and demodulated. For example, the demodulation device 1 outputs the ray 13 at the symbol at time T and the ray 17 at the symbol at time T + 1.
Is demodulated in synchronization with the phase. Also,
The demodulator 2 demodulates the beam 14 at the symbol at time T and the beam 18 at the symbol at time T + 1 in synchronization with the phase. Further, the demodulator 3 demodulates the ray 15 at the symbol at time T and the ray 19 at the symbol at time T + 1 in synchronization with the phase.

In this case, each of the multipath rays 13 to 16 for a symbol at a certain time T and each of the multipath rays 1 for a symbol at an adjacent time T + 1
Each of the phase information 7 to 20 is supplied from the transmission path state estimation device 6 to the demodulation devices 1 to 3, respectively. Each demodulator 1 to 3
In the above, a spread code is generated in accordance with given phase information to perform demodulation. And each demodulation device 1,
The signals demodulated in 2 and 3 are subjected to maximum ratio combining in the symbol combining device 5. The signal synthesized by the symbol synthesizing device 5 is converted into a multipath erasing device 10 described later.
After passing through, the demodulator 7 makes a decision to obtain demodulated data.

The unnecessary wave demodulation device 4 includes demodulation devices 1 to 1.
The demodulation of the beam assigned in synchronization with the phase of the beam estimated by the transmission path state estimating means 6 is performed in substantially the same manner as in 3.
The rays assigned to the unnecessary wave demodulator 4 are rays whose delay amount exceeds one symbol. That is, the unnecessary wave demodulator 4 is one of the symbols demodulated by the demodulators 1 to 3.
Demodulation is performed on the symbol before the symbol time.

Since the signal to be demodulated by the unnecessary wave demodulation device 4 is data that has already been determined by the determiner 7, the determined demodulated data is supplied from the determiner 7 for reliable operation. The demodulation operation is performed using the information. In the example of FIG. 1, since the number of unnecessary wave demodulation devices 4 is set to one,
Demodulates in synchronization with the phase of the ray 16 shown in FIG. This is because the unnecessary wave demodulation device 4 is configured as shown in FIG.
As shown in FIG. 2A, when there is no delayed wave exceeding the symbol interval, or as shown in FIG. 2B, there is a delayed wave exceeding the symbol interval, but the delay wave element for the adjacent symbol is present. If the waves do not overlap, the demodulation operation is stopped by the information from the transmission path state estimating means 6.

As described above, by using the unnecessary wave demodulation device 4, only the beam that exceeds the symbol interval and overlaps with the beam of the delayed wave for the adjacent symbol is demodulated as shown in FIG. 2C. . That is, unnecessary wave components included in the outputs of the demodulators 1 to 3 and the output of the symbol combiner 5 that combines them can be output from the unnecessary wave demodulator 4. By subtracting the output of the unnecessary wave demodulation device 4 from the output of the device 5, unnecessary wave components included in the output of the symbol combining device 5 can be removed.

In the reception quality measuring means 8, the decision unit 7
, Ie, the demodulated signal, and the output of the decision unit 7, ie, the decided demodulated data, are input, and the quality of the received demodulated signal is measured based on these information. Specifically, for example, if no error has occurred, the determined demodulated data is the same as the symbol transmitted from the transmitting side, and can be regarded as a reference value when the reception quality is the best. Therefore, by comparing the determined demodulated data with the demodulated data before the determination, it is possible to measure the reception quality according to the difference. In this case, if the difference between the determined demodulated data and the demodulated data before the determination is small, the reception quality can be regarded as high, and if the difference is large, the reception quality can be regarded as low.

The reception quality information measured in this way is supplied to the amplitude / phase control means 9. The reception quality information obtained by the reception quality measurement unit 8 and the demodulated data determined by the determination unit 7 are input to the amplitude / phase control unit 9.
A replica of the unnecessary wave component included in the demodulated data before being determined from these data is created. Specifically, for example, by configuring an adaptive filter that receives the determined demodulated data as an input and controlling the coefficients of the adaptive filter, that is, the amplitude and the phase using an adaptive algorithm based on the reception quality information, A replica of the unnecessary wave component is created.

When the output of the symbol combining device 5 does not include unnecessary wave components as shown in FIGS. 2A and 2B, the reception quality Is determined to be good, the replica of the unnecessary wave component generated by the amplitude / phase control means 9 becomes very small, and does not cause deterioration of the reception quality. The replica of the unnecessary wave component created by the amplitude and phase control means 9 in this manner is
0 and the replica of the unnecessary wave component is subtracted from the output of the symbol combining device 5. Thereby, unnecessary wave components included in the output of the symbol combining device 5 can be removed.

The method for removing unnecessary waves using the unnecessary wave demodulation device 4 and the method for removing unnecessary waves using the reception quality measuring means 8 and the amplitude / phase control means 9 described above are essentially independent of each other. Working. Therefore, in the spectrum receiving apparatus of the present invention, only one of them may be used instead of employing both means. In this case, in the method of removing the unnecessary wave using the unnecessary wave demodulation device 4, it is necessary to find the path of the unnecessary wave, but if the path can be found, the unnecessary wave can be surely removed. On the other hand, the method of removing unnecessary waves using the reception quality measuring means 8 and the amplitude / phase control means 9 does not require finding a path of unnecessary waves, but lacks certainty of removing unnecessary waves. That is, by using both methods, good reception can be performed while compensating for the disadvantages of both methods.

When a ray corresponding to a symbol at a certain time overlaps with two or more rays corresponding to a symbol at an adjacent time, two or more unnecessary wave demodulators 4 are provided. May be extracted.
In addition, the removal unit including the reception quality measurement unit 8 and the amplitude / phase control unit 9 removes an unnecessary wave even when an elementary wave corresponding to a symbol at a certain time overlaps with an elementary wave corresponding to a symbol at the next next time. It can be removed.

[0026]

As described above, according to the present invention, the demodulated data after the determination and the information obtained from the transmission path state estimating means, or the output of the symbol combining apparatus and the information on the reception quality obtained from the demodulated data which has determined the same are obtained. , Or using both information, a means is provided for canceling a multipath beam that adversely affects other symbols, such as a delay amount that is longer than a symbol interval and overlaps with an adjacent symbol. Even when there is a delayed ray that adversely affects the symbol, it is possible to prevent the reception performance from deteriorating. Therefore, it is possible to realize a spread spectrum receiver with less deterioration in reception performance.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a spread spectrum receiver according to the present invention.

FIG. 2 is a diagram illustrating demodulation timings of each demodulation device according to the embodiment of the present invention and a conventional example.

FIG. 3 is a schematic block diagram of a conventional spread spectrum receiver.

[Explanation of symbols]

1, 2, 3 demodulator 4 unnecessary wave demodulator 5 symbol combiner 6 channel state estimating means 7 judging device 8 reception quality measuring means 9 amplitude and phase control means 10 multipath elimination device 11 received signal 12 multipath of each path Phase information 13-16 Multipath paths for symbols at a certain time 17-20 Multipath paths for symbols at adjacent times

Claims (3)

(57) [Claims] 1. A receiver for a communication system using a spread spectrum method, comprising: a transmission path state estimating means for estimating a multipath state of a transmission path from a received signal; and a transmission path state estimated by the transmission path state estimating means. A plurality of demodulators that independently demodulate in synchronization with each elementary wave of a multipath based on the above, a symbol combiner that combines signals demodulated by the plurality of demodulators, and a demodulator that is demodulated by the symbol combiner. Other included in the signal
Cancels unwanted multipath waves that can adversely affect symbols
Multipath elimination means, a decision unit for judging a signal output from the multipath elimination means , and a reception using the transmission path state determined by the transmission path state estimation means and the signal determined by the determination unit. At least one unnecessary wave demodulator for demodulating a multipath unnecessary wave that adversely affects other symbols included in the signal ;
The multipath canceling means is provided by the unnecessary wave demodulation device.
The demodulated signal cancels out the unnecessary waves of the multipath.
Spread spectrum receiver, characterized in that it is in Suyo. 2. A receiver of a communication system using a spread spectrum system, comprising: a transmission line state estimating means for estimating a multipath state of a transmission path from a received signal; and a transmission path state estimated by the transmission path state estimating means. A plurality of demodulators that independently demodulate in synchronization with each elementary wave of a multipath based on the above, a symbol combiner that combines signals demodulated by the plurality of demodulators, and a demodulator that is demodulated by the symbol combiner. Other included in the signal
Cancels unwanted multipath waves that can adversely affect symbols
Multipath erasing means, a determiner for determining a signal output from the multipath erasing means , and a reception quality using the signal output from the multipath erasing means and the signal determined by the determiner. Reception quality measuring means for measuring, the signal determined by the determiner and the reception quality information measured by the reception quality measurement means using a multipath spurious wave that adversely affects other symbols included in the received signal using the reception quality information Amplitude and phase control means for generating a replica, wherein the multi-path erasing means is provided by the amplitude and phase control means.
No need for multipath due to the generated replica
A spread-spectrum receiver characterized in that it cancels waves . 3. A receiver of a communication system using a spread spectrum method, comprising: a transmission line state estimating means for estimating a multipath state of a transmission path from a received signal; and a transmission path state estimated by the transmission path state estimating means. A plurality of demodulators that independently demodulate in synchronization with each elementary wave of a multipath, a symbol combiner that combines signals demodulated by the plurality of demodulators, and a demodulator that is demodulated by the symbol combiner. Other included in the signal
Cancels unwanted multipath waves that can adversely affect symbols
Multipath elimination means, a decision unit for judging a signal output from the multipath elimination means , and a reception using the transmission path state determined by the transmission path state estimation means and the signal determined by the determination unit. A plurality of unnecessary wave demodulators for demodulating unnecessary waves of a multipath that adversely affect other symbols included in the signal, and a signal output from the multipath canceling unit and a signal determined by the determiner, Reception quality measurement means for measuring reception quality, and generating a replica of the unnecessary wave of the multipath included in the reception signal using the signal determined by the determiner and the reception quality information measured by the reception quality measurement means and a amplitude phase control means for said multi-path deletion means, by the unnecessary wave demodulator
A demodulated signal and a signal generated by the amplitude and phase control means.
The unnecessary waves of the multipath are hit by the replica
A spread-spectrum receiver, characterized in that it is designed to cancel.