JP2002185367A - Radio transmission system of digital information, transmitter and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio transmission system of digital information capable of alleviating a quality deterioration of a transmission signal due to an AC coupling in a modulator input signal of a transmitter, by using signs of a DC balance for a preamble period of the transmission signal, to provide the transmitter and a receiver used for the system. SOLUTION: The radio transmission system of the digital information transmits a radio frequency to be modulated obtained by modulating a radio frequency signal by a transmission base band signal obtained by frame combining a base band digital modulation signal modulated by the digital information and a spectrum spread signal. The spectrum spread signal has self-correlation characteristics becoming zero for a prescribed period before or after a correlation peak of phase zero and signs of DC balance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital information radio transmission system capable of high-speed transmission in a multipath environment, and a transmitter and a receiver thereof.

[0002]

2. Description of the Related Art Spread-spectrum communication has the advantage of being resistant to multipath and narrow-band interference, and has been used as a medium-speed wireless LAN communication system having a transmission speed of several hundred kbps to several Mbps. On the other hand, in spread spectrum communication, a signal obtained by multiplying an information signal by a high-speed despreading code is transmitted, so that the transmission bandwidth becomes larger than the bandwidth of the information signal. For this reason, it has been said that spread spectrum communication is not suitable for high-speed transmission at a transmission speed of 10 Mbps or more.

However, in recent years, spread spectrum communication systems with good frequency use efficiency have been developed one after another.
Wireless LAN with a maximum transmission speed of 11 Mbps in 1999
The standard IEEE 802.11b has been formulated. However, even with IEEE802.11b, the effective maximum throughput is about 7 to 8 Mbps, and 10 Mbps.
An environment equivalent to Ethernet cannot be realized by wireless LAN. It is said that a wireless transmission speed of 20 Mbps or more is required in order to use an application requiring a large transmission capacity such as image information transmission of a real-time under a wireless LAN environment.

Accordingly, the inventors of the present application have proposed IEEE80.
A transmission method and apparatus capable of realizing high-speed transmission of 20 Mbps or more using the same transmission band as 2.11b have been developed and a patent application has been filed (Japanese Patent Application No. 11-1149469).
issue). By using the transmission method and apparatus according to the prior application, an environment equivalent to 10 Mbps Ethernet can be realized in a wireless LAN.

FIG. 8 shows a block diagram of a transmitter of a wireless transmission device in Japanese Patent Application No. 11-1149469. In FIG. 8, the preamble generation circuit 1 operates during the preamble period of the transmission signal, and repeatedly transmits a code 51 (hereinafter, referred to as an orthogonal code) having an autocorrelation side lobe of zero. The information modulation circuit 2 operates during the data period of the transmission signal, and the information-modulated transmission data 52 is repeatedly transmitted. Here, as the orthogonal code of code length 4, for example,

(Equation 4) There is. The autocorrelation function of the orthogonal code C having a code length of 4 is shown in FIG.
Shown in It can be seen that the autocorrelation side lobe of the orthogonal code C is zero.

On the other hand, FIG. 9 shows a block diagram of a transmitter of a wireless transmission device in Japanese Patent Application No. 11-1149469. In FIG. 9, a received signal 61 is converted into a digital received signal 62 by an AD conversion circuit 13, and an output 70 obtained by averaging an output 63 of a matched filter circuit 14 by an averaging circuit 21 is applied to a transmission line characteristic extraction circuit 15. Then, the impulse response signal 64A and the signal vector signal 64B are extracted from the preamble period of the digital reception signal 62 using the impulse response circuit 22 and the signal vector generation circuit 23, respectively. Here, since the signal transmitted during the preamble period is an orthogonal code, the impulse response signal 64A and the signal vector signal 64B are obtained with high accuracy. The decision feedback equalizer 16 creates a replica signal of intersymbol interference based on the impulse response signal 64A, the signal vector signal 64B, and the received data signal 66 fed back, and uses the intersymbol interference replica signal to generate a digital signal. Waveform equalization processing is performed on the data period of the reception signal 62. This waveform equalization processing output 65
Is demodulated by the information modulation / demodulation circuit 17 into a reception data signal 66.

[0007] The transceiver having the above configuration effectively suppresses signal quality degradation due to intersymbol interference occurring in a multipath environment. Further, since data is transmitted by information modulation, higher-speed data transmission becomes possible as compared with normal spread spectrum communication. For example, when information modulation is QPSK modulation, high-speed data transmission at twice the chip rate is enabled.

[0008]

When the wireless transmission device according to the above-mentioned prior application is used, the IEEE standard is used in a wireless LAN environment.
20Mbps using the same transmission band as E802.11b
Although high-speed transmission of s or more is possible, the measurement accuracy of the transmission path characteristic information in the transmission path characteristic extraction means may deteriorate due to physical limitations of hardware. This will be described below.

In general, it is difficult to realize a wideband DC amplifier, and some modulators require that a modulation signal be input by AC coupling. For example, there is a configuration in which the input signal of the modulator is AC-coupled to prevent the inflow of a DC component, and the DC bias point is stably operated inside the modulator to reduce the origin offset amount. Here, when a signal having a non-zero DC component is input to this modulator, the DC component required as transmission information is cut off by AC coupling, so that the spectrum of the transmission signal is distorted. In order to prevent the quality degradation of the transmission signal, a rare modulator that can input the modulation signal by DC coupling must be used, or physical measures must be taken on the hardware, causing a cost increase. Becomes

On the other hand, when a signal having a DC component of zero is input to the modulator, the transmission signal is transmitted without being greatly affected by AC coupling of the modulator input signal. Therefore, there is no limitation in selecting the modulator, and there is no need to provide a new circuit on hardware, so that the load on the device can be reduced and the modulator can be realized at low cost.

The complex spreading code used in the preamble period of the transmission signal of the wireless transmission device in Japanese Patent Application No. 11-114469 is an orthogonal code, which means that the DC component does not become zero. This will be described using mathematical expressions.

A code having a zero autocorrelation sidelobe can be expressed by the following equation (2).

(Equation 5) Here, d _n is the autocorrelation side lobe becomes zero cycle N
Means that an infinite synchronization code is represented by one cycle. When this complex code is subjected to discrete Fourier transform,

(Equation 6) Becomes On the other hand, if the discrete Fourier transform is used,

(Equation 7) Can be expressed as

However,

(Equation 8) And

[Outside 1] It is. Substituting equation (4) into equation (2) and transforming,

(Equation 9) Becomes

[0014]

[Outside 2]

[0015]

(Equation 10)

[0016]

[Outside 3]

After all, the radio transmission apparatus disclosed in Japanese Patent Application No. 11-149469 uses an orthogonal code, that is, a code with no DC balance, as a spread code transmitted during a preamble period of a transmission signal. In a situation where DC cutoff must be performed in a band, there is a problem that the spectrum waveform of a transmission signal is distorted, and the performance of the wireless transmission device is deteriorated. Therefore, it is necessary to take physical measures on hardware as a means for preventing this deterioration, and an increase in the number of parts has caused high cost.

According to the present invention, the use of a code with a DC balance during the preamble period of a transmission signal reduces, at low cost, the quality degradation of the transmission signal due to AC coupling in the modulator input signal of the transmitter, and It is an object of the present invention to provide a digital information transmission system that enables high-speed transmission. The present invention further reduces the quality degradation of a transmission signal due to AC coupling in a modulator input signal of a transmitter at low cost by using a code with DC balance during a preamble period of the transmission signal, and achieves a high speed. It is an object of the present invention to provide a transmitter and a receiver used in a digital information transmission system that enables transmission.

[0019]

In order to achieve the above object, a radio transmission system for digital information according to the present invention is obtained by synthesizing a baseband digital modulation signal modulated by digital information and a spread spectrum signal by a frame. A radio transmission system for digital information, in which a modulated radio frequency obtained by modulating a radio frequency signal by a transmission baseband signal is transmitted to a radio transmission path, wherein the spread spectrum signal has an autocorrelation characteristic of a correlation peak having a phase of zero. It has a configuration characterized in that the sign becomes zero in a certain period before and after and has a DC-balanced sign. Here, codes are transmitted in a preamble period {d _n} is the formula Conditions:

[Equation 11] Can be adopted.

Further, the transmitter according to the present invention comprises: a preamble generating means for repeatedly outputting a DC balanced code in which the autocorrelation function becomes zero for a predetermined period before and after the correlation peak having a zero phase difference during the preamble period; Channel coding means for outputting a channel code corresponding to transmission data during a period, information modulating means for further modulating the channel code with information, a preamble signal output from the preamble generating means and the information A frame synthesizing unit for synthesizing the information modulation signal output from the modulation unit to obtain a frame modulation signal. In this case, the preamble generating means performs the following condition during the preamble period:

(Equation 12) Is output so as to output a code {d _n } satisfying the following.

Further, the receiver according to the present invention provides a modulated radio signal obtained by modulating a radio frequency signal with a transmission baseband signal obtained by synthesizing a baseband digital modulation signal modulated by digital information and a spread spectrum signal. A / D conversion means for performing A / D conversion on the reception signal of the modulated radio frequency to receive a frequency, a matched filter means for obtaining a despread signal from an output signal of the A / D conversion means, and the despread signal. Averaging means for averaging, transmission path characteristic extracting means for obtaining transmission path characteristic information necessary for waveform equalization from a matched filter output average signal output from the averaging processing means, and the transmission path characteristic Waveform equalizing means for equalizing the waveform of the digital reception signal based on information; and a waveform output from the waveform equalizing means. Has an information modulation and demodulation means for demodulating the signal, a configuration in which a channel coding and decoding means for further decoding the demodulated signal output from the information modulation and demodulation means.

Further, the receiver according to the present invention is a modulated radio which modulates a radio frequency signal by a transmission baseband signal obtained by synthesizing a baseband digital modulation signal modulated by digital information and a spread spectrum signal in a frame. Frequency, wherein the spread spectrum signal is:

(Equation 13) AD conversion means for AD converting the received signal of the modulated radio frequency so as to receive the modulated radio frequency having a code {d _n } satisfying the following condition; and a digital reception signal output from the AD conversion means. said a matched filter means for determining a correlation before and half or rear half of the code {d _n}, the symbols to be transmitted in synchronization with the despread signal output from said matched filter means preamble period and and sign inverting means for generating a code repeating half cycle of the period of {d _n} "+1" and "-1" alternately multiplies the despread signal, averaging the multiplication output of the positive negative sign inverting means Averaging means for detecting a match with the UW pattern or its sign-inverted pattern and detecting the detected U
UW detecting means for outputting information on the direction of W, and multiplying a matched filter output average signal output from the averaging means by "+1" or "-1" based on a UW information signal output from the UW detecting means Average signal sign correction means for performing transmission path characteristic extraction means for obtaining transmission path characteristic information necessary for waveform equalization from a matched filter output correction average signal output from the average signal code correction means; A waveform equalizer for waveform equalizing the digital reception signal based on information; an information modulation demodulator for demodulating a waveform equalized signal output from the waveform equalizer; and A transmission line encoding / decoding unit for decoding the output demodulated signal with respect to the transmission line code may be further provided.

[0023]

FIG. 1 is a block diagram of a transmitter according to an embodiment of the present invention. The block configuration of the transmitter shown in FIG. 1 is obtained by adding a transmission line coding circuit 102 to the configuration of the transmitter of the transmission device in Japanese Patent Application No. 11-149469 shown in FIG. It has the same block configuration as in the case. In FIG. 1, a preamble generation circuit 101 operates during a preamble period of a transmission packet, and an autocorrelation function becomes zero for a certain period before and after a correlation peak with a phase difference of zero, and a code with DC balance is repeated as a preamble signal 151. Output. This code has, for example, an autocorrelation function:

[Equation 14] There is a sign represented by However, d _n is an element of complex symbol period 2N. Hereinafter, this code is called a pseudo-orthogonal code, and will be described using mathematical expressions.

Using a discrete Fourier transform, a similar calculation that yields equation (7) gives:

(Equation 15) Becomes

[Outside 4]

[0025]

(Equation 16)

As shown in equation (10), the spectrum of the pseudo-orthogonal code has a period of 2N.

[Equation 17] Becomes Also, by using the discrete inverse Fourier transform,

(Equation 18) Becomes

As described above, a pseudo-orthogonal code having a period of 2N is:

[Outside 5] It can be seen that the code is inverted and recursive. As the pseudo orthogonal code of N = 4, for example,

[Equation 19] There is. FIG. 4 shows the autocorrelation function of the pseudo orthogonal code G with N = 4.
Shown in The correlation peak of the pseudo-orthogonal code G alternates between positive and negative every four chips, and the signal point arrangement of each chip is equal to the QPSK signal point arrangement.

On the other hand, during the data period of the transmission packet, the transmission line coding circuit 102 operates to output a transmission line code 152 corresponding to the transmission data in order to suppress the DC component of the transmission data. As a transmission line code for sufficiently suppressing the DC component, for example, there is a Manchester code. However, although this code is excellent at suppressing the DC component,
Since the coding rate is 1/2, the transmission efficiency is reduced. Therefore, in practice, if the DC component can be suppressed to some extent,
By using a channel code with a higher coding rate,
A reduction in transmission efficiency can be minimized. The information modulation circuit 103 outputs an information modulation signal 153 corresponding to the input transmission line code 152. In this embodiment, a case where QPSK modulation is used as an example of information modulation performed by the information modulation circuit 103 is described. Frame synthesis circuit 1
In 04, a frame is synthesized from the preamble signal 151 output from the preamble generation circuit 101 and the information modulation signal 153 output from the information modulation circuit 103, and output as a transmission signal 154.

FIG. 5 shows a frame configuration of a transmission packet when the pseudo orthogonal code G represented by the equation (12) is used as the spread spectrum code. In FIG.

(Equation 20) And PLCP (Physical Layer Convergence Proceed
dure) header, UW (Uniqe Word), CRC (Cyclic R)
edundancy Check) is omitted. Since a pseudo orthogonal code G having an 8-chip cycle is transmitted during the preamble period, a code having a 4-chip cycle is transmitted repeatedly alternately in a positive and negative manner every cycle. Therefore, the entire frame configuration is the same as the frame configuration example of the conventional transmission packet when the orthogonal code C having the code length 4 shown in FIG. 6 is used. The frame structure of the transmission packet shown in FIGS. 5 and 6 is a case where a spread spectrum signal having a chip rate of 11 Mcps and a QPSK signal having a symbol rate of 11 Msps are used, and the signal waveforms are all 11 Msps QPSK signals.

FIG. 2 is a block diagram of a receiver according to an embodiment of the present invention. The block configuration of the receiver shown in FIG. 2 is different from the configuration of the receiver of the transmission device in Japanese Patent Application No. 11-149469 shown in FIG.
Are added, and the other configuration is the same as that of FIG. In FIG. 2, a received signal 161 is AD-converted by an AD conversion circuit 113 to become a digital received signal 162. The digital reception signal 162 is branched into two, one of which is applied to the matched filter circuit 114 and the other is applied to the waveform equalization circuit 116. The matched filter circuit 114 operates during the preamble period, and performs a correlation operation between the received signal and the reference code sequentially.
The reference code is a spread code transmitted during the preamble period. However, since the configuration of the transmission path characteristic extraction circuit 115 described later can be easily realized, the spread code is set to (−π /
Use the one rotated only 4).

Here, the transmitter uses 2 as a spreading code.
When a pseudo-orthogonal code having a period of N chips is used, the sign is changed and recursed at a period of N chips, and the recursion is performed. Therefore, the arithmetic circuit of the matched filter circuit 114 is equivalent to the length N, and the circuit configuration can be simplified. Matched filter circuit 114
FIG. 3 shows an embodiment of a block diagram of a receiver in the case where the arithmetic circuit of No. is equivalent to the length N and the circuit configuration is simplified.

FIG. 3 is a block diagram showing a receiver according to an embodiment of the present invention.
This is a block configuration in which a positive / negative sign inversion circuit 119 and an average signal sign correction circuit 124 are added before and after 1, and a UW detection circuit 120 is added, and the other configurations are the same as those in FIG. In FIG. 3, the fact that the arithmetic circuit of the matched filter circuit 114 can be realized with a length corresponding to the length N will be described below using mathematical expressions.

A pseudo-orthogonal code having a period of 2N is expressed by the following equation (11).

(Equation 21) , And recursion is performed by changing the code at the cycle of N chips, so that the left side of the equation (8) can be transformed into the following equation.

(Equation 22) From the result of equation (14) and equation (8),

(Equation 23) Becomes

The impulse response of the unknown transmission line

(Equation 24) And At this time, the preamble period of the received signal is given by a convolution operation of the impulse response and the pseudo orthogonal code,

(Equation 25) Becomes In the matched filter, a correlation between the received signal and the above-described reference code is obtained.

Assuming that the length of the operation circuit of the matched filter is N, the output is

(Equation 26) Becomes

Further, N to 2N of a pseudo orthogonal code having a period of 2N
Using the equation (13), the matched filter output in the -1 interval is

[Equation 27] Becomes That is, as the output of the matched filter having the arithmetic circuit of length N,

[Equation 28] Is obtained.

As described above, when a pseudo orthogonal code having a period of 2N chips is used for the transmission signal in the preamble period, the matched filter circuit 114 can be realized by an arithmetic circuit having a length of N. For example, when the pseudo-orthogonal code G having an 8-chip period shown in Expression (12) is used as the spreading code, the arithmetic circuit of the matched filter circuit 114 has a length of 4. In this case, the reference symbol T ′ used for the correlation operation in the matched filter circuit 114 is used.
Is given by

(Equation 29) As a result, the despread signal 163 output from the matched filter circuit 114 multiplies the impulse response of the transmission path by four times, and
The signal rotated by / 4 is sampled at one chip cycle,
The sequence is an eight-chip cycle that alternates between positive and negative every four chips. The despread signal 163 is applied to the sign inverting circuit 119.

FIG. 7 shows a matched filter circuit 114 when a pseudo orthogonal code G having a period of 8 chips is used as a spreading code.
8 shows an example of an 8-chip cycle despread signal 163 output from the. In FIG.

[Equation 30] And Here, h _k is the impulse response of the transmission line sampled at one chip cycle. Despread signal 1
It can be seen that 63 is a signal having an eight-chip cycle that alternates between positive and negative every four chips. Therefore, this despread signal 163
If the inversion and non-inversion operations are alternately performed in a 4-chip cycle, the impulse response of the transmission path is quadrupled, and π /
The signal rotated four times can be treated as a series repeatedly output at a cycle of four chips. Thus, the configuration of an averaging circuit 121 described later is equivalent to the case of averaging the despread signal with a 4-chip cycle, and the circuit can be simplified. These operations can be realized in the sign inverting circuit 119 by a method described below.

The sign inverting circuit 119 first finds the maximum correlation peak value in the first four chips of the despread signal 163. In the next four chips, a threshold determination is performed on the despread signal 163 in order to determine the inversion and non-inversion start positions. The threshold value is obtained by multiplying the maximum value of the correlation peak by a certain constant, for example, 1/8. Inverting and non-inverting of the despread signal 163 are repeated in a 4-chip cycle in synchronization with the preceding wave timing obtained by the threshold value determination, the direction of the despread signal 163 is aligned, and output as a code-corrected despread signal 168. . One of the code correction despread signals 168 is applied to the averaging circuit 121 and the other is applied to the UW detection circuit 120.

The UW detection circuit 120 operates during the UW period, and outputs a UW signal to the code-corrected despread signal 168 during the UW period.
Perform detection. It detects whether the UW detection result matches the UW pattern or its sign-inverted pattern, and outputs a UW information signal 171 that is information on the detected UW direction. The sign correction despread signal 168 from the positive / negative sign inversion circuit 119 is applied to the averaging circuit 121, and the sign correction despread signal 168 at each timing of the preceding wave, the one-chip delay wave, the two-chip delay wave, and the three-chip delay wave is applied. Is obtained as a matched filter output average signal 169 to which the influence of thermal noise or the like is sufficiently applied.

The average signal sign correction circuit 124 generates a matched filter output average signal 1 based on the UW information signal 171.
69 is multiplied by “+1” or “−1”, and a matched filter output correction average signal 170 corresponding to the direction of the impulse response of the transmission path is output. As this identification method, for example, the following methods are available. The positive / negative direction of the matched filter output average signal 169 can be determined based on whether the UW detection result matches the UW pattern or its sign-inverted pattern. Average processing circuit 121
By measuring the phase at which averaging of the code-corrected despread signal 168 starts and the phase of the UW signal, the phase relationship between the two can be determined. Therefore, the positive and negative directions of the matched filter output average signal 169 can be determined. , UW detection results have a one-to-one correspondence with the orientation with respect to the UW pattern. For example, if the UW detection result has the same sign as the UW pattern, the matched filter output average signal 16
9 is used in a non-inverted manner. Conversely, if the UW detection result has a different sign to the UW, the matched filter output average signal 169
May be used in a reversed relationship.
By performing the above operation, the matched filter output average signal 1
69 is output as a matched filter output correction average signal 170 having a sign corresponding to the impulse response of the transmission path.

Using equation (12) as the pseudo-orthogonal code G,
Since the matched filter output correction average signal 170 in the case where the equation (20) is used as the reference code T ′ used for the correlation operation in the matched filter circuit 114 becomes a periodic function of a 4-chip cycle, the Expressed by the vector of 4,

(Equation 31) Becomes The matched filter output correction average signal 170 is 2
One is applied to an impulse response circuit 122 and the other is applied to a signal vector generation circuit 123. Further, the timings of the preceding wave, the one-chip delayed wave, the two-chip delayed wave, and the three-chip delayed wave are given from the synchronization circuit.

The signals input to the transmission line characteristic extraction circuit 115 shown in FIGS. 2 and 3 are both signals represented by the following equation (21). The transmission line characteristic extraction circuit 115 includes an impulse response circuit 122 and a signal vector. It is composed of a circuit 123. The matched filter output correction average signal 170 output from the average signal sign correction circuit 124 is applied to the impulse response circuit 122, an operation of rotating the phase by (−π / 4) is performed, and sampling is performed at one chip interval. The transmission path impulse response signal 164A is output.
Therefore, equation (21) is transformed into the following equation.

(Equation 32)

[0044]

[Outside 6] This operation is given assuming that the complex vector is (p, q).

[Equation 33] This is realized by a conversion operation as follows. Equation (2
The result of 2) is that the impulse response signal 164A indicates the impulse response of the transmission path in the digital reception signal 162 by 4
√ Indicates that the value is doubled.

The matched filter output correction average signal 170 output from the average signal code correction circuit 124 is applied to the signal vector generation circuit 123, and the complex conjugate of the impulse response corresponding to the first arriving wave is added to each signal vector of QPSK modulation. Is calculated and output as a signal vector signal 164B. The signal vector S (1,1) corresponding to the QPSK data (1,1) is expressed by the following equation.

(Equation 34) This signal vector S (1,1) is the average of the matched filter output correction average signal 170.

[Outside 7] It is obtained by further dividing by 4. Further, by performing a rotation operation of 90 degrees, 180 degrees and 270 degrees by exchanging the real part and the imaginary part of the signal vector S (1, 1) and inverting the sign, the signal vectors S (-1, 1), S (-
1, -1) and S (1, -1) are obtained.

The digital feedback signal 162, the impulse response signal 164A, the signal vector signal 164B, and the demodulation signal 166 output from the information modulation / demodulation circuit 117 are applied to the decision feedback equalization circuit 116, and operate during the data period. , And performs a decision feedback waveform equalization of the received signal.

The operation of the decision feedback waveform equalization will be described below using mathematical expressions. The i-th transmission symbol in the data period is TS _i , and the i-th reception symbol is RS _i . At this time, the following equation (25) holds.

(Equation 35) By multiplying both sides of equation (25) by h ₀ ^* ,

[Equation 36] Is obtained.

On the other hand, the operation of the decision feedback equalizer 116 is as follows.

(37) Can be expressed as Here, EQ _i is the waveform equalized signal 165 for the i-th received symbol, and TS ′
_ik is a QPSK signal before k symbols estimated from the determination data before k symbols. RS _i is given by a digital reception signal 162, h ₀ ^* , h ₁ , h ₂ , h ₃ are given by an impulse response signal 164 A, and h ₀ ^* TS ′ _ik is given by a signal vector 164 and a demodulation signal 166.

QPSK demodulation is positive in the last three symbols
If not, TS ’ _ik= TS_ikIs formed
Therefore, substituting equation (26) into equation (27)
Than,

(38) Is obtained.

The information modulation / demodulation circuit 117 performs QPSK demodulation of the waveform equalized signal 165, and outputs a demodulated signal 166. The demodulated signal 166 is also output to the decision feedback equalizer 116 as a feedback signal.
The transmission line code decoding circuit 118 decodes the demodulated signal 116 for the transmission line code and outputs a received data signal 167.

[0051]

As described above in detail, in the digital communication transceiver according to the present invention, the autocorrelation function becomes zero during a certain period before and after the correlation peak of zero phase difference during the preamble period of the transmission signal, and the DC Since the transmission path characteristics are estimated using the balanced spreading code, the signal quality deterioration that occurs when the modulator input of the transmitter is AC-coupled is not considered. In this way, there is no need to take countermeasures against deterioration due to the addition of new circuits on the hardware, and it is possible to reduce this signal quality deterioration at low cost and to realize a digital communication transceiver capable of high-speed transmission. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a transmitter according to the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a receiver according to the present invention.

FIG. 3 is a block diagram showing another configuration example of the receiver according to the present invention.

FIG. 4 is a diagram for explaining a signal format of a transmission signal used in the present invention.

FIG. 5 is a diagram for explaining a signal format of a transmission signal used in the present invention.

FIG. 6 is a diagram for explaining a signal format of a conventional transmission signal.

FIG. 7 is a diagram for explaining the operation of the receiver according to the present invention.

FIG. 8 is a block diagram showing a configuration of a conventional digital information wireless transmission system transmitter.

FIG. 9 is a block diagram showing a configuration of a conventional digital information wireless transmission system receiver.

FIG. 10 is a diagram for explaining a signal format used in a conventional digital information wireless transmission system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 preamble generation circuit 2 information modulation circuit 3 frame modulation circuit 13 AD conversion circuit 14 matched filter circuit 15 transmission line characteristic extraction circuit 16 decision feedback equalization circuit 17 information modulation demodulation circuit 21 average processing circuit 22 impulse response circuit 23 signal vector generation Circuit 51 Preamble signal 52 Information modulation signal 53 Transmission signal 61 Receive signal 62 Digital reception signal 63 Matched filter circuit output 64A Impulse response signal 64B Signal vector signal 65 Waveform equalization output 66 Receive data 70 Average processing output 101 Preamble generation circuit 102 Transmission Channel coding circuit 103 information modulation circuit 104 frame synthesis circuit 113 AD conversion circuit 114 matched filter circuit 115 transmission line characteristic extraction circuit 116 decision feedback equalization circuit 117 information modulation / demodulation Circuit 118 Transmission line code decoding circuit 119 Positive / negative sign inversion circuit 120 UW detection circuit 121 Average processing circuit 122 Impulse response circuit 123 Signal vector generation circuit 124 Average signal code correction circuit 151 Preamble signal 152 Transmission line code 153 Information modulation signal 154 Transmission signal 161 Received signal 162 Digital received signal 163 Matched filter circuit output 164A Impulse response signal 164B Signal vector signal 165 Waveform equalization output 166 Demodulation output 167 Received data 168 Code corrected despread signal 169 Average processing output 170 Matched filter output corrected average signal 171 UW information signal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K004 AA05 FA05 FB05 FE10 FG04 FH03 5K022 EE02 EE11 EE21 EE33 5K029 AA04 AA18 DD05 FF09 GG07 GG10 HH01 HH05 HH08 HH29 5K033 AA04 AA07 DA17 DB10

Claims (6)

[Claims] 1. A transmission baseband signal obtained by synthesizing a baseband digital modulation signal modulated by digital information and a spread spectrum signal by a frame.
A radio transmission system for digital information in which a modulated radio frequency obtained by modulating a radio frequency signal is transmitted to a radio transmission path, wherein the spread spectrum signal has an autocorrelation characteristic which becomes zero for a predetermined period before and after a correlation peak having a phase of zero. And a DC balanced code. 2. A code ｛d transmitted during a preamble period
_n ｝ is the condition of the following equation: 2. The wireless transmission system for digital information according to claim 1, wherein the following is satisfied. 3. A preamble generating means for outputting a code having a DC-balanced state in which the autocorrelation function becomes zero during a predetermined period before and after a correlation peak having a phase difference of zero during a preamble period, and corresponds to transmission data during a data period. Channel coding means for outputting a channel code; information modulating means for further modulating the channel code; a preamble signal output from the preamble generating means; and information output from the information modulating means. A wireless transmission wave transmitter for digital information, comprising: frame synthesizing means for synthesizing a modulation signal to obtain a frame modulation signal. 4. The preamble generating means according to claim 1, wherein: 4. The transmitter according to claim 3, wherein the transmitter outputs a code {d _n } satisfying the following equation. 5. A transmission baseband signal obtained by frame-synthesizing a baseband digital modulation signal modulated by digital information and a spread spectrum signal,
AD conversion means for AD converting the received signal of the modulated radio frequency to receive a modulated radio frequency obtained by modulating a radio frequency signal, and a despread signal for obtaining a despread signal from an output signal of the AD conversion means. Matched filter means, averaging means for averaging the despread signal, and a transmission path for obtaining transmission path characteristic information required for waveform equalization from a matched filter output average signal output from the averaging means Characteristic extracting means, waveform equalizing means for waveform equalizing the digital reception signal based on the transmission path characteristic information, and information modulation / demodulation for demodulating a waveform equalized signal output from the waveform equalizing means. Means for decoding digital information, further comprising: a transmission path encoding / decoding means for further decoding a demodulated signal output from the information modulation / demodulation means. Transmitting receiver. 6. A transmission baseband signal obtained by frame combining a baseband digital modulation signal modulated by digital information and a spread spectrum signal,
A modulated radio frequency obtained by modulating a radio frequency signal, wherein the spread spectrum signal has the following condition: AD conversion means for AD-converting the reception signal of the modulated radio frequency to receive the modulated radio frequency having the code {d _n } satisfying the following condition; and a digital reception signal output from the AD conversion means. said a matched filter means for determining a correlation before and half or rear half of the code {d _n}, the symbols to be transmitted in synchronization with the despread signal output from said matched filter means preamble period and and sign inverting means for generating a code repeating half cycle of the period of {d _n} "+1" and "-1" alternately multiplies the despread signal, averaging the multiplication output of the positive negative sign inverting means Averaging means for detecting a match between the UW pattern or its sign-inverted pattern and detecting the detected U
UW detecting means for outputting information of the direction of W, and multiplying a matched filter output average signal output from the averaging means by "+1" or "-1" based on a UW information signal output from the UW detecting means Average signal sign correction means for performing transmission path characteristic extraction means for obtaining transmission path characteristic information necessary for waveform equalization from a matched filter output correction average signal output from the average signal code correction means; Waveform equalizing means for equalizing the waveform of the digital reception signal based on information; information modulation / demodulation means for demodulating a waveform equalization signal output from the waveform equalization means; and Transmission line encoding / decoding means for decoding the output demodulated signal with respect to a transmission line code. Machine.