JPH09247123A - Spread spectrum signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the deterioration of an error rate characteristic caused by interference at the time of multiplexing by reducing the extension of a relative peak owing to multiplexing. SOLUTION: A transmitting signal is received by a reception antenna 151, frequency- converted into a base band IQ signal by a frequency which is synchronizes with a transmission frequency in a frequency converting circuit 152, the base band IQ signal is A/D converted by an A/D converting circuit 155 and correlation is obtained by a correlator 156 as against the output. A judging circuit 157 judges a correlator output so as to obtain demodulation data and a spread symbol estimating circuit 11 estimates front and rear spread symbols which are multiplexed by a multiplex spread symbol to be a cancelled object through the use of a judgement output. Then, the timing of the spread symbol to be cancelled and the multiplex spread symbol to be the cancelled object of the A/D conversion output is adjusted by a delay circuit, the front and rear spread symbols to be cancelled which are multiplexed by the multiplex spread symbol to be the cancelled object is cancelled by a subtracting circuit, correlation is obtained by the correlator 13 as against a multiplex signal removing output and its output is judged by the judging circuit 14 so as to obtain demodulation data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum signal receiver, and more particularly, it is used as a method for transmitting high-speed data using a spread spectrum signal with a constant frequency bandwidth and transmits using a single spread code. Spread spectrum signal receiver for a system that uses a spread spectrum signal to spread a signal to generate a spread symbol and multiplex and transmit consecutive spread symbols in a relationship delayed by a single or multiple chips of the spread code. Regarding

[0002]

2. Description of the Related Art FIG. 16 shows a case where a transmission signal is spread by using a single spreading code to generate spreading symbols, and a plurality of consecutive spreading symbols are delayed by a single chip or a plurality of chips of the spreading code. FIG. 3 is a block diagram showing a configuration of a spread spectrum signal receiver that receives the spread spectrum signal transmitted by the above method.

Here, an 11-chip Barker code is used as a spreading code and QPSK modulation is used as a modulation method, and five consecutive spreading symbols are delayed by repeating chip intervals of 2, 2, 2, 2 and 3 chips, respectively. A case of receiving the spread spectrum signals multiplexed by the above will be described.

FIG. 17 is a diagram for explaining the multiplex operation, which is performed for each of the I and Q signals. The n-4th to n + 4th symbols shown in FIG. 17 are the Barker codes (1, -1,1,1, -1, -1,1,1,1, -1, -1, -1, respectively) for continuous transmission data.
Spread symbols 171 to 179 spread by using -1). In this example, the consecutive spreading symbols are 2, 2,
The spread symbols are sequentially delayed at intervals of 2, 2 and 3 chips, 5 spread symbols are multiplexed for each chip, and the nth spread spread symbol 180 is transmitted.

In the receiver shown in FIG. 16, the multiplexed spread spectrum signal is received by the receiving antenna 151 and converted into baseband I and Q signals 153 and 154 by the frequency conversion circuit 152 at a frequency synchronized with the transmission frequency. Then, each of the I and Q signals is A / D converted by the A / D conversion circuit 155 and despread by the correlator 156, so that each of the multiplexed spread symbols is generated at a time corresponding to each of the multiplexed spread symbols. The correlation peak corresponding to the symbol is obtained, and the demodulation data 158 is obtained by the determination circuit 157.

[0006]

In the example shown in FIG. 16, the correlation peaks of the I and Q signals at the output of the correlator 156 have no amplitude due to the interference of the spread symbols in the case of the non-multiplexed spread spectrum signal. However, in the case of multiplexing, as shown in FIG. 18, it becomes one of the signal points of ± 7, ± 9, ± 11, ± 13 and ± 15 depending on the data of the symbols before and after, and the interference at the time of multiplexing. Will spread.

In FIG. 19, the signal points are ± 7, ± 9, ± 11, ±.
It is a figure for demonstrating the reason which becomes either 13 or ± 15. A Barker code (1, -1,1,1,
1, -1, 1, 1, 1, 1, -1, -1, -1) depending on whether the modulation data is +1 or -1.
Spreading symbols shown in (1, -1,1,1, -1 ,,
1,1,1, -1, -1, -1, -1) or (-1,1, -1, -1,
-1,1, -1, -1, -1, -1,1,1,1). Here, the modulation data is ... +1, -1, +1, +1, -1,
As an example, the case of +1, +1, +1, -1, -1, -1, ... Is shown in FIG. 19 for the delay multiplexing operation, the despreading operation shown in FIG. 17, and the resulting correlation peak value. Shows. As shown in FIG. 19, when the receiver performs the despreading operation of each symbol on the multiplexed signal, the correlation peak values are ± 7, ± 9, ± 11, ± 1.
It will be either 3, ± 15.

As described above, when the correlation peak of the received signal spreads, the error rate becomes high at a signal point near the decision boundary, and this influence causes a problem that the overall error rate characteristic deteriorates.

FIG. 20 is a diagram for explaining the judgment boundary. In the case of the BPSK signal, since the judgment is made according to the sign of the sign of the demodulated data, the judgment boundary is the point of "0", whereas in the case of the QPSK signal, the sign of the sign of the I signal and the sign of the Q signal are usually judged. Since information is assigned to each of the positive and negative judgments of the sign, the I axis and the Q axis serve as the judgment boundaries in the IQ phase plane. Therefore, as described above, when the correlation peak of the received signal is widened, the error rate becomes high at the signal points near the decision boundary.

Therefore, a main object of the present invention is to provide a spread spectrum signal receiver capable of reducing the spread of the correlation peak due to multiplexing and improving the deterioration of the error rate characteristic caused by interference at the time of multiplexing.

[0011]

The invention according to claim 1 is
A reception antenna for receiving a transmission signal, a frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with the transmission frequency, and an A / D conversion means for A / D converting the baseband IQ signal, A transmission signal including a first correlator that obtains a correlation with respect to the output of the A / D conversion means, and a first determination means that determines the output of the first correlator to obtain demodulated data, and uses a single spreading code. In a spread spectrum signal receiver for receiving a spread spectrum signal transmitted by multiplexing a plurality of spread symbols to generate a spread symbol and multiplexing a plurality of consecutive spread symbols with a delay of only one or a plurality of chips of the spread code, Spreading symbol estimation means for estimating the spreading symbols before and after being multiplexed in the multiple spreading symbol to be canceled using the determination data output from the first determining means. And a spreading symbol to be canceled output from the spreading symbol estimation means and a multiple spreading symbol to be canceled from the A / D conversion means output are sequentially delayed to be multiplexed on the multiple spreading symbol to be canceled. Multiplexed signal removing means for canceling by subtracting spread symbols to be canceled before and after, a second correlator for obtaining a correlation with the output of the multiplex signal removing means, and demodulated data by determining the output of the second correlator And a second determining means for obtaining

According to the second aspect of the invention, similarly to the spread spectrum signal receiver of the first aspect, after being multiplexed on the multiple spread symbol to be canceled using the determination data output from the first determining means. Spreading symbol estimating means for estimating the spreading symbol of the spreading symbol, the spreading symbol to be canceled at the output of the spreading symbol estimating means, and the timing of the multiple spreading symbol to be canceled at the output of the A / D converting means are adjusted by sequentially delaying them. And a second correlator for obtaining a correlation with respect to the output of the multiplex signal removing means by subtracting the spreading symbols to be canceled before and after being multiplexed with the multiplex spreading symbol to be canceled. Second determining means for determining the output of the second correlator to obtain demodulated data, and second determining means Constructed and a second spread symbols estimating means for estimating the spread symbols before multiplexed in multiplexed spread symbols to be canceled subject using force.

In the invention according to claim 3, the multiplex signal removing means according to claim 1 or 2 comprises a plurality of first delay means for sequentially delaying the timings of the spreading symbols to be canceled, which are output from the spreading symbol estimating means, A second delay unit that delays the timing of the multiple spreading symbol that is the target of cancellation of the output of the A / D conversion unit, and a plurality of first multiple spreading symbols that are delayed by the second delay unit and that are the targets of cancellation. Subtracting means for subtracting the spreading symbol to be canceled delayed by the delaying means.

According to a fourth aspect of the present invention, in addition to the third aspect of the present invention, the amplitude level of the spreading symbol to be canceled which is further delayed by the plurality of first delay means is a multiple spreading symbol to be canceled. Amplitude adjusting means is included to adjust the amplitude level of 1 to a level obtained by dividing the amplitude level of 1.

In the invention according to claim 5, the multiplexed signal removing means according to claim 1 or 2 is such that the amplitude level of the spread symbol to be canceled is the amplitude of the spread symbol to be canceled. Amplitude adjusting means for adjusting the level to a level obtained by multiplying the number of multiplexes, a plurality of first delay means for sequentially delaying the timing of the spreading symbols to be canceled in the spreading symbol estimating means output, and the output of the amplitude adjusting means. Second delay means for delaying
The subtraction unit subtracts the spread symbols to be canceled delayed by the plurality of first delay units from the multiple spread symbols delayed by the plurality of second delay units and to be canceled.

In a sixth aspect of the present invention, a receiving antenna for receiving a transmission signal, frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with or close to the transmission frequency, and baseband IQ.
A / D conversion means for A / D converting the signal, a correlator for obtaining a correlation with the output of the A / D conversion means, a differential demodulation means for differentially demodulating the correlator output, and an output of the differential demodulation means And a decision means for obtaining demodulated data by spreading the transmission signal using a single spreading code to generate spreading symbols, and delaying successive spreading symbols by a single or multiple chips of the spreading code. In a spread spectrum signal receiver that receives a plurality of spread spectrum signals transmitted by multiplexing with, random transmission data is assumed, and the occurrence probability of a signal point on the IQ phase plane of the differential demodulation means output is obtained in advance, The average coordinates are calculated in consideration of the occurrence probability,
The determination means subtracts the IQ coordinate value of the average coordinate from the determination target data of the IQ signal, and then makes the determination.

According to a seventh aspect of the present invention, in a spread spectrum signal receiver similar to the sixth aspect, assuming random transmission data, the occurrence probability of a signal point on the IQ phase plane of the differential demodulation means output is calculated in advance. The average coordinate is calculated in consideration of the occurrence probability, and the IQ of the average coordinate is determined by the determining means.
The coordinate value is used as a reference for determining the IQ signal.

[0018]

1 is a schematic block diagram showing the overall configuration of a first embodiment of the present invention. In FIG. 1, the receiving antenna 151, the frequency conversion circuit 152, and the A /
The D conversion circuit 155, the correlator 156, and the determination circuit 17 are the same as those in the conventional example shown in FIG. A signal 16 of a multiple spread symbol to be canceled is output from the A / D conversion circuit 155 and given to the multiple signal removal circuit 12. On the other hand, the judgment data output from the judgment circuit 157 is given to the spread symbol estimation circuit 11, and the spread symbol estimation circuit 11 uses the judgment data 17 to estimate the spread symbols 18 before and after the cancellation and to cancel the multiplexed signal. Enter in 12. The multiplex signal removal circuit 12 removes the multiplexed spreading symbols to be canceled, which are estimated from the multiple spreading symbols to be canceled. The canceled spread symbol 19 from which the multiplex signal has been removed by the multiplex signal removal circuit 12 is input to the correlator 13, and the obtained correlation peak is input to the determination circuit 14 for determination, and demodulation data 15 from which the multiplex signal has been removed is obtained. It is output from the determination circuit 14.

FIG. 2 is a diagram showing the configuration of the multiplex signal elimination circuit shown in FIG. In FIG. 2, the A / D conversion circuit 15
The multiple spreading symbol 16 to be canceled, which is output from No. 5, is input to the delay circuit 40, the timing is adjusted, and the additional spread symbol 16 is input to the subtraction circuit 41 as an addition value. on the other hand,
The spread symbols 18 to be canceled estimated by the spread symbol estimation circuit 11 are collectively input to the delay circuit 31 for each spread symbol of 11 chips. Delay circuits 32 to 38 are connected in series to the delay circuit 31, and the spread symbol of 11 chips is 2 chips or 3 chips.
The delay circuits 31 for delaying the chips are sequentially delivered to the delay circuits 31, and the respective outputs are input as subtraction values to the subtraction circuit 41 as spread symbols to be canceled. The subtraction circuit 41 subtracts the subtraction input from the chip corresponding to the multiple spreading symbol to be canceled, and outputs the canceled spreading symbol 19.

FIG. 3 is a diagram for explaining the processing operation of the spread symbol estimation circuit shown in FIG. The correlator 156 shown in FIG. 1 performs the despreading operation on the n-th symbol shown in FIG. 17, and the determination circuit 157 determines the sign of the sign of the correlation peak obtained thereby, and the spread symbol estimation circuit. 11 uses the obtained positive / negative (± 1) data to perform spreading by Barker code. More specifically, a shift register, for example, is used as the spread symbol estimation circuit 11, sets an 11-bit Barker code at "H" / "L" level, and if the data is +1,
The bit data can be output in that order, and if the data is -1, it can be inverted and output.

FIG. 4 is a diagram for explaining the operation of the multiple signal removing circuit shown in FIG. Spreading symbol estimation circuit 1
The 11-bit spread symbols 18 to be canceled output by 1 are sequentially input to the delay circuits 31 to 38 shown in FIG. 2 in 11-bit groups, and 11-bit groups are input each time a new estimation symbol is input. 4 and each of the four spreading symbols 16 before and after the multiple spreading symbol 16 to be canceled are always held. If there is no noise between transmission and reception, the multiple spreading symbol 16 to be canceled is the same as the multiple signal shown in FIG. The spreading symbol 18 to be canceled is the correlator 15
6. Since it passes through the decision circuit 157 and the spread symbol estimation circuit 11, there is a delay, and the multiple spread symbol 16 to be canceled is also input to the delay circuits 31 to 38 in order to match the timing. Finally, the subtraction circuit 41 performs an operation reverse to the multiplexing operation shown in FIG. 17 to cancel. This processing procedure is shown in FIG.

The spread symbol estimation circuit 11 is provided for each system of the IQ signal, and the estimation operation and the removal operation described so far are all performed independently for each IQ signal.

As described above, according to the first embodiment of the present invention, it is possible to estimate and cancel a multiplexed signal multiplexed in demodulation symbols, and improve the deterioration of error rate characteristics due to interference during multiplexing. You can

FIG. 5 is a block diagram showing a second embodiment of the present invention. In the above-described first embodiment shown in FIG. 1, the decision data of the received signal by the decision circuit 157 is used to estimate the spread symbols before and after being multiplexed with the symbols to be demodulated by the spread symbol estimation circuit 11, While the signal removal circuit 12 cancels the multiplexed signal, the second embodiment shown in FIG. 5 uses the received signal determination data and the determination data after the multiplexed signal is cancelled. This is to cancel the multiplexed signal by estimating the spread symbols before and after being multiplexed in the demodulated symbol.

For this reason, the receiving antenna 151 to the decision circuit 157 are constructed in the same manner as in FIG. 1, but the spread symbol estimation circuit 11 outputs the spread symbols to be canceled and the multiplexed signal removing circuit 12 is provided. Given to. On the other hand, the spread symbol 62 to be canceled, which is located before the multiple spread symbol 16 to be canceled and which is to be canceled, is given from the spread symbol estimation circuit 111 to the multiple signal removal circuit 12. The spread symbol estimation circuit 111 estimates the correlation peak obtained from the output of the multiplex signal removal circuit 12 via the correlator 13 using the demodulated data determined by the determination circuit 14. The multiplex signal removing circuit 12 removes the multiplexed spreading symbols to be canceled which are estimated from the multiple spreading symbols to be canceled. The canceled spread symbol 19 from which the multiplex signal has been removed has the same structure as in the embodiment of FIG.
The correlation peak obtained by inputting to the correlator 13 is determined by the determination circuit 14, and demodulated data 15 from which the multiplexed signal is removed is output.

FIG. 6 is a block diagram showing a concrete example of the multiple signal removing circuit shown in FIG. In the same manner as in FIG. 2 described above, the multiple spread symbols 16 to be canceled output from the A / D conversion circuit 155 are adjusted in timing by the delay circuit 58 and input to the subtraction circuit 41 as an added value. On the other hand, the delay circuits 50, 51 and 52 are connected in series, and the delay circuit 50 includes the spread symbol estimation circuit 1
The subsequent spreading symbols 18 to be canceled which are estimated by 1 are collectively input to the delay circuit 50 for each spreading symbol of 11 chips and sequentially delayed.

The delay circuits 53, 54, 55 and 5 are also provided.
6 are connected in series, and the spread symbols 62 to be canceled are collectively input to the delay circuit 53 for each spread symbol of 11 chips and sequentially delayed. Then, the spread symbols to be canceled are input as subtraction values to the subtraction circuit 41 from the delay circuits 50 to 56, and the subtraction circuit 41 subtracts the subtraction inputs from the chips corresponding to the multiple spread symbols to be canceled, The canceled spread symbol 19 is output.

FIG. 7 is a block diagram showing the structure of a multiple signal removing circuit according to the third embodiment of the present invention. 7, the configuration is the same as that shown in FIG. 2 except for the amplitude adjusting circuit 80. The amplitude adjusting circuit 80 adjusts the amplitude of the spreading symbol to be canceled according to the amplitude fluctuation of the signal 16 of the multiple spreading symbol to be canceled and inputs it to the subtracting circuit 19. in this way,
By adjusting the amplitude of the spreading symbol to be canceled by the amplitude adjusting circuit 80, there is an advantage that the multiplexed signal can be removed without being affected by the amplitude fluctuation of the signal 16 of the multiple spreading symbol to be canceled.

FIG. 8 is a block diagram of a multiple signal removing circuit showing a fourth embodiment of the present invention. The embodiment shown in FIG. 8 is the same as the above-described FIG. 6 except for the amplitude adjusting circuit 80. This amplitude adjusting circuit 80 also adjusts the amplitude of the spreading symbol to be canceled according to the amplitude fluctuation of the signal 16 of the multiple spreading symbol to be canceled and inputs it to the subtracting circuit 41 in the same manner as in FIG. That is, the multiplexed signal is removed without being affected by the amplitude variation of the signal 16 of the multiplexed spreading symbol to be canceled.

FIG. 9 is a block diagram of a multiple signal removing circuit showing a fifth embodiment of the present invention. In the embodiment shown in FIG. 9, the amplitude adjusting circuit 70 is connected to the preceding stage of the delay circuit 40. The amplitude adjusting circuit 70 adjusts the amplitude fluctuation of the signal 16 of the multiple spread symbol to be canceled and inputs it to the subtracting circuit 41 via the delay circuit 40. In this embodiment as well, it is affected by the amplitude fluctuation. It is possible to remove multiple signals without having to do so.

FIG. 10 is a block diagram showing a multiple signal removing circuit according to a sixth embodiment of the present invention. This embodiment is configured in the same manner as the embodiment shown in FIG. 6 except for the amplitude adjusting circuit 70. Amplitude adjusting circuit 70
Adjusts the amplitude variation of the signal 16 of the multiple spreading symbol to be canceled in the same manner as the embodiment of FIG.
By inputting to the subtraction circuit 41 via the delay circuit 40, the multiplexed signal is removed without being affected by the amplitude fluctuation.

FIG. 11 is a diagram showing the result of computer simulation on the effect of improving the error characteristic when the second embodiment of the present invention is carried out. In FIG. 11, when the bit error rate BER = 10 ⁻⁴ ,
In contrast to the characteristics in the case of not being multiplexed, in the conventional demodulation method, the power increase due to 5 multiplexing is 7.0 dB and the interference due to multiplexing is 2.3 dB, resulting in a total degradation of 9.3 dB. On the other hand, when the embodiment of the present invention is implemented, 2.1 dB is improved in the interference group due to multiplexing. In this way, by canceling the spread symbols before and after being multiplexed in this embodiment, the correlation peak does not spread due to multiplexing, and the deterioration of the error rate characteristic caused by interference during multiplexing is improved. by this,
While realizing high-speed data transmission by multiplexing, it is possible to obtain the same error rate characteristic as in the case where there is no interference due to multiplexing.

FIG. 12 is a block diagram showing a seventh embodiment of the present invention. In this embodiment, an average coordinate after differential demodulation is obtained, and the average coordinate value is added to the determination target data, and then the determination is performed. That is, in the conventional example shown in FIG. 16 described above, when the number of multiplexed signals becomes large, 8 or 9 chips out of 11 chips become the same received signal for consecutive multiple spread symbols, so There is a specific transition pattern with a high probability in the transition of. When differential demodulation is performed on this transition pattern, there is a high probability that a specific signal point among the signal points spread by the aforementioned differential demodulation has a high probability, and the distribution is such that the arrangement of signal points with a high probability is due to the quadrant. Differently, there is no symmetry of distribution between quadrants. As a result,
As described above with reference to FIG. 20, since there is no decision boundary in the center of the signal point distribution and the signal point distribution, the conventional IQ
When the positive / negative sign judgment of the signal is used, a judgment error is likely to occur and the error rate characteristic is deteriorated. This embodiment solves this problem.

In FIG. 12, the receiving antenna 151, the frequency conversion circuit 152, the A / D conversion circuit 155, the correlator 156 and the determination circuit 157 are the same as those in the conventional example shown in FIG. The differential demodulation circuit 159, the subtraction circuit 100, and the average coordinate value memory circuit 110 are provided between the correlator 156 and the determination circuit 157. The average coordinate value memory circuit 110 is composed of, for example, a switch circuit or a memory circuit, and the average coordinate value subtraction circuit 10 is used.
Give to 0. The subtraction circuit 100 subtracts the average coordinate value given from the average coordinate value memory circuit 110 from the output signal of the differential demodulation circuit 159, and gives it to the judgment circuit 157. The determination circuit 157 determines the positive / negative sign of each IQ signal in the same manner as the conventional example, and obtains the demodulated data 15.

The case of the conditions described in the conventional example will be described below. The correlation value of the output of the correlator 156 is ± 7, ± for each IQ signal due to interference during multiplexing.
Any of 9, ± 11, ± 13 and ± 15. I
When viewed on the Q phase plane, the number of signal points in each quadrant is 25, and the quadrant has the same distribution as long as the modulation data is random.

In the example shown in FIG. 12, two consecutive signal points are 8 out of 11 chips of the input of the correlator 156.
Since the chips or 9 chips are the same, a transition pattern with a high specific probability is generated. As an example of the transition pattern, the transitions when the signs from the correlation values 9, 11 and 13 do not change are 9 → 9, 11 → 11 and 13 →, respectively.
The probability of being 13 is the highest, but the probability of being 9 → -15, 11 → −13 and 13 → −11 is the highest when the sign changes, respectively.

FIG. 13 shows a case in which the value of the Q axis is fixed to 11, and the value of the I axis transits from 11 → −11 without interference due to multiplexing and when transits from 11 → −13 due to interference due to multiplexing. It is a figure showing the difference in the amount of phase rotations obtained after differential demodulation. From FIG. 13, it can be seen that the latter has a larger amount of phase rotation than the former. Due to the influence of some of these transition patterns, in the IQ phase plane after the differential demodulation, the arrangement of signal points having a high probability differs depending on the quadrant, and the symmetry about the quadrant disappears.

FIG. 14 is a diagram showing the distribution of signal points after differential demodulation in the case of S / N = 18 dB as an example. As is apparent from FIG. 14, the negative portions of the I and Q axes are close to the signal points of the second and fourth quadrants, respectively, and the distribution of signal points and the decision boundary at the center of the distribution do not exist. I understand. Therefore, in order to realize this, if random data is assumed and the occurrence probability of signal points in all quadrants is obtained, and the coordinates of average signal points are obtained in consideration of the occurrence probability,
(-30.4, -30.4), and the shift amount from the origin is obtained. In this embodiment, this average coordinate value is set in the average coordinate value memory circuit 110, subtracted from the output signal of the differential demodulation circuit 159 by using the subtraction circuit 100, and the determination circuit 157 uses the IQ signal as in the conventional example. The sign of each of the signals is determined, and demodulated data 15 is obtained.

FIG. 15 is a block diagram showing an eighth embodiment of the present invention. In this embodiment, the average coordinate value memory circuit 11 is applied to the output signal of the differential demodulation circuit 159.
The determination circuit 120 uses the average coordinate value from 0 as the determination reference.
To determine the magnitude relationship. In this example, the average coordinate value obtained similarly to the embodiment shown in FIG. 12 may be set in the average coordinate value memory 110 as well.

As described above, in the embodiments shown in FIGS. 12 and 15, by arranging the decision boundary at the center between the signal point distributions, points that are apt to be erroneously decided are eliminated and the error rate characteristic is deteriorated. Is improved. As a result, it is possible to improve the deterioration of the error rate due to multiplexing while realizing high-speed data transmission by multiplexing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a specific block diagram of the multiplex signal elimination circuit shown in FIG.

FIG. 3 is a diagram for explaining the processing operation of the spread symbol estimation circuit shown in FIG.

FIG. 4 is a diagram for explaining a method of canceling by performing an operation opposite to the multiplexing operation by the subtraction circuit shown in FIG.

FIG. 5 is a block diagram showing the overall configuration of a second embodiment of the present invention.

6 is a block diagram showing a specific example of the multiplex signal removing circuit shown in FIG.

FIG. 7 is a block diagram of a multiple signal removing circuit according to a third embodiment of the present invention.

FIG. 8 is a block diagram of a multiple signal elimination circuit according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram of a multiple signal removing circuit according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram of a multiplex signal removing circuit according to a sixth embodiment of the present invention.

FIG. 11 is a diagram for explaining the effect of the present invention.

FIG. 12 is a block diagram showing a seventh embodiment of the present invention.

FIG. 13 is a diagram showing an example of a transition pattern in the seventh embodiment of the invention.

FIG. 14 is a diagram for explaining a signal point distribution after differential demodulation.

FIG. 15 is a block diagram showing an eighth embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of a conventional spread spectrum signal receiver.

FIG. 17 is a diagram for explaining a signal multiplexing method in a conventional spread spectrum signal receiver.

FIG. 18 is a diagram for explaining a correlation peak in a conventional spread spectrum signal receiver.

FIG. 19 is a diagram for explaining the value of a correlation peak.

FIG. 20 is a diagram showing a determination boundary between an I coordinate and a Q coordinate in a conventional example.

[Explanation of symbols]

 11,111 Spreading symbol estimation circuit 12 Multiplex signal removal circuit 13,156 Correlator 14,157 Judgment circuit 31-38,40,50-56,58 Delay circuit 41 Subtraction circuit 70,80 Amplitude adjustment circuit 100 Subtraction circuit 110 Average coordinate value Memory circuit 151 Reception antenna 152 Frequency conversion circuit 155 A / D conversion circuit 159 Differential demodulation circuit

Claims (7)

[Claims] 1. A receiving antenna for receiving a transmission signal, frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with a transmission frequency, and A / D conversion of the baseband IQ signal. A / D conversion means and a first for obtaining a correlation with the output of the A / D conversion means
And a first determining unit that determines the output of the first correlator to obtain demodulated data, and spreads a transmission signal by using a single spreading code to generate a spreading symbol, In a spread spectrum signal receiver for receiving a spread spectrum signal transmitted by multiplexing a plurality of spread symbols with a delay of only one or a plurality of chips of a spread code, the judgment data output from the first judging means is used. Spreading symbol estimation means for estimating the spreading symbols before and after being multiplexed in the multiple spreading symbol to be canceled, and the spreading symbol to be canceled of the output of the spreading symbol estimating means and the cancellation of the output of the A / D converting means. The target multi-spreading symbol is adjusted by sequentially delaying the timing, and the target multi-spreading symbol is canceled. The multiplex signal canceling means for canceling by subtracting the spread symbols to be canceled before and after the multiplex multiplexing, a second correlator for obtaining a correlation with the output of the multiplex signal removing means, A second spread spectrum signal receiver having a second judging means for judging a correlator output to obtain demodulated data. 2. A receiving antenna for receiving a transmission signal, frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with a transmission frequency, and A / D conversion for the baseband IQ signal. A / D conversion means and a first for obtaining a correlation with the output of the A / D conversion means
And a first determining unit that determines the output of the first correlator to obtain demodulated data, and spreads a transmission signal by using a single spreading code to generate a spreading symbol, In a spread spectrum signal receiver for receiving a spread spectrum signal transmitted by multiplexing a plurality of spread symbols with a delay of only one or a plurality of chips of a spread code, the judgment data output from the first judging means is used. Spreading symbol estimation means for estimating a spreading symbol after being multiplexed into a multiple spreading symbol to be canceled by the above, a spreading symbol to be canceled in the output of the spreading symbol estimating means, and a canceling of the output of the A / D converting means. The target multi-spreading symbol is adjusted by sequentially delaying the timing to cancel the multi-spreading symbol. Multiplex signal canceling means for canceling by subtracting spread symbols to be canceled before and after being multiplexed, a second correlator for obtaining a correlation with the output of the multiplex signal removing means, and an output of the second correlator And a second spreading symbol estimation for estimating the previous spreading symbol multiplexed on the multiple spreading symbol to be canceled by using the output of the second determining means. And a spread spectrum signal receiver. 3. The multiple signal removing means includes a plurality of first delay means for sequentially delaying the timing of the spreading symbols to be canceled in the output of the spreading symbol estimating means, and the canceling of the output of the A / D converting means. Second delay means for delaying the timing of the target multiple spreading symbol, and cancellation delayed by the plurality of first delay means from the multiple spreading symbol to be canceled delayed by the second delay means. A spread spectrum signal receiver according to claim 1 or 2 including subtraction means for subtracting the spreading symbols to be performed. 4. The amplitude level of the spread symbols to be canceled delayed by the plurality of first delay means is a level obtained by dividing the amplitude level of the multiple spread symbols to be canceled by the number of multiplexes. Spread spectrum signal receiver according to claim 3 including amplitude adjusting means for adjusting. 5. The multiplex signal removing means sets the amplitude level of the multiplex spreading symbol to be canceled in the output of the A / D converting means to a level obtained by multiplying the amplitude level of the spreading symbol to be canceled by the number of multiplexes. Adjusting means, a plurality of first delay means for sequentially delaying the timing of the spreading symbol to be canceled in the output of the spreading symbol estimating means, and a second delay for delaying the output of the amplitude adjusting means. And subtraction means for subtracting the spread symbols to be canceled delayed by the plurality of first delay means from the multiple spread symbols to be canceled which are delayed by the plurality of second delay means. Claim 1 or 2
Spread spectrum signal receiver. 6. A reception antenna for receiving a transmission signal, frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with a transmission frequency or a frequency close to the transmission frequency, and the baseband IQ signal is converted into an A / A signal. A / D conversion means for D conversion, a correlator for obtaining a correlation with the output of the A / D conversion means, a differential demodulation means for differentially demodulating the correlator output, and an output of the differential demodulation means And a decision means for obtaining demodulated data by spreading the transmission signal using a single spreading code to generate spreading symbols, and delaying the continuous spreading symbols by a single chip or a plurality of chips of the spreading code. In a spread spectrum signal receiver that receives spread spectrum signals that are multiplexed and transmitted by using the above, assuming the random transmission data, output the differential demodulation means in advance. Determination the probability of a signal point on the IQ phase plane, the average coordinates determined in consideration of the occurrence probability, I average coordinates from the determination target data of the IQ signal by said determining means
A spread spectrum signal receiver characterized by making a determination after subtracting each Q coordinate value. 7. A reception antenna for receiving a transmission signal, frequency conversion means for frequency-converting the received signal into a baseband IQ signal at a frequency synchronized with a transmission frequency or a frequency close to the transmission frequency, and the baseband IQ signal is converted into an A / A signal. A / D conversion means for D conversion, a correlator for obtaining a correlation with the output of the A / D conversion means, a differential demodulation means for differentially demodulating the correlator output, and an output of the differential demodulation means And a decision means for obtaining demodulated data by spreading the transmission signal using a single spreading code to generate spreading symbols, and delaying the continuous spreading symbols by a single chip or a plurality of chips of the spreading code. In a spread spectrum signal receiver that receives spread spectrum signals transmitted by multiplexing a plurality of signals, assuming the random transmission data, the differential demodulation procedure is performed in advance. The generation probability of a signal point on the output IQ phase plane is calculated, the average coordinate is calculated in consideration of the generation probability, and the IQ coordinate value of the average coordinate is judged by the judging means as the judgment standard of the IQ signal. And a spread spectrum signal receiver.