JPS5962229A - Heterodyne repeater with waveform equalizer - Google Patents

Abstract

PURPOSE:To attain heterodyne relaying with waveform equalization without using a modulator by providing an intermediate frequency band transversal filter, a digital demodulator and a control signal generator. CONSTITUTION:A receiving signal of radio frequency band is converted and amplified in an intermediate frequency band at a receiving section 1 and inputted to an intermediate frequency band transversal filter 8. The output of the filter 8 is branched into two; one is converted into a radio frequency band, amplified and transmitted from a transmission section 7, and the other is demodulated into 4-value base band signal of two rows at a digital demodulator 2 and compared and discriminated with plural threshold values predetermined at a control signal generator 5'. A heterodyne relay device with waveform equalizer having an adaptive transversal equalizer is obtained by controlling the filter 8 from the result of comparison and discrimination.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heterodyne repeater with a waveform equalizer used in a wideband wireless transmission system using digital modulation.

In wideband wireless transmission systems using digital modulation, in recent years, multi-level 1H modulation schemes have been progressing from the viewpoint of effective use of one frequency band, and the development of orthogonal multi-level amplitude modulation schemes is attracting particular attention. However, as the multi-direction ratio of a single modulation system increases, the waveform distortion due to frequency selective fading such as multipath fading that occurs in a wireless transmission line is more likely to be affected, leading to poor transmission quality. As a method of dealing with such waveform distortion that changes over time, conventionally, a transversal filter type waveform equalizer that can perform correction fkk control is installed in the baseband band of the receiver to reduce the waveform of the demodulated output signal that has been An adaptive transversal equalizer is used that automatically controls the amount of correction so that it is optimal. Therefore.

When relaying is busy over multiple radio sections.

- Transmit carrier r again with demodulated baseband signal
By adopting a modulated detection relay method, regenerative relay is performed for each relay, and features of digital relay such as no addition of noise are exhibited.

On the other hand, it has the disadvantage that every repeater requires a modulator r. In general, relaying methods for wideband wireless transmission involve baseband signals at each relay station. A detection relay method for demodulating and a baseband signal once every few relays? There is a heterodyne relay method in which the signal is demodulated and converted to an intermediate frequency band at each intermediate relay station in between, amplified as it is, and then converted back to a radio frequency band and transmitted. ? It is widely used when purchasing long-distance wireless lines because it has the advantage of simplifying the configuration of relay equipment without requiring it. Even in the case of the digital modulation method, the heterodyne method is useful for economical t1N formation of long-distance wireless lines. 79513) Heterodyne repeaters are also used in Europe, but the realization of a heterodyne repeater with a waveform equalizer that can equalize not only amplitude distortion but also delay distortion is based on the multilevel ratio of the modulation method, especially quadrature multilevel amplitude modulation. The development of this method is expected to have a great effect.

An object of the present invention is to provide a heterodyne repeater with a waveform equalizer that eliminates the drawbacks of the conventional detection repeater with a waveform equalizer and improves the geometric function of the heterodyne repeater with an amplitude equalizer. That's true.

The heterodyne relay device with a waveform equalizer of the present invention includes a receiving section that converts and amplifies the received signal of a digitally modulated radio frequency band (to an intermediate frequency band), and an output r of this receiving section that amplifies and converts the received signal to a radio frequency band. In a heterodyne relay device equipped with a transmitter and a transmitter that transmits a frequency band transmission number 4, an intermediate frequency band transversal filter is inserted between the receiver and the transmitter, and the output of this transversal filter is branched. Multilevel baseband signal′? A digital demodulator performs demodulation, and the output of this digital demodulator t is compared with a plurality of predetermined threshold values to identify and control the transversal filter l:, fl+IJ (q??).
Waveform equalizer with control signal generator and r? It consists of being prepared.

Next, the present invention will be explained in detail with reference to drawing r.

Figure 1 shows 200M using the 16-level quadrature amplitude modulation (QAM) method.
It is a block diagram illustrating a conventional example of a detection repeater with a waveform equalizer that performs b/s transmission, and is a block diagram illustrating a conventional example of a detection repeater with a waveform equalizer that performs b/s transmission. A receiver 1 that converts and amplifies the intermediate frequency band, and outputs two columns of four-level baseband signals? The digital demodulator 2 to demodulate, the baseband frequency band transversal filter 3 connected to the output of the 7, and the output of the 2 rows of the 7 are each compared with a plurality of predetermined thresholds (4) for identification. , reproduction of the binary baseband signal and generation of error No. 13; a control signal generator 5 for generating a control signal for the transversal filter 30 from the error output; It consists of a modulator 6 that modulates an intermediate frequency signal iQAMv using a set of binary baseband signals, and a transmitter 7 that converts and amplifies the intermediate frequency band output r of the modulator 6 into a radio frequency band and sends out a transmission signal. has been done.

Transversal Phil j13. The discriminator 4 and the control signal generator 5 constitute an adaptive transversal equalizer 9r that automatically equalizes waveform distortion depending on the input situation. The details are described in Japanese Patent Application No. 11664/1983, so please refer to this if necessary.

FIG. 2 is a block diagram of one embodiment of the present invention.

In a heterodyne repeater equipped with a receiving section 1 and transmitting sections 7 and 2, an intermediate frequency band transversal filter 8 inserted between the receiving section 1 and the transmitting section 7 branches the output of A digital demodulator 2 demodulates a 4-level baseband signal, and its output r is compared with a predetermined ratio of multiple (4) threshold values and identified by a transversal filter 8.
Adaptive transversal equalizer (waveform, etc. 1) consisting of a control signal generator for generating control signals r and a control signal generator for generating control signals 9
This is a heterodyne repeater equipped with a t-waveform equalizer. As is clear from this configuration, although a digital demodulator r is used for waveform geometric ratio, a modulator is not required, and the configuration of the relay device is simpler than that of the detection relay 1 shown in FIG.

FIG. 3 is a more detailed block diagram of one embodiment of the adaptive waveform equalizer q shown in FIG. and.

Variable weighting circuits 20, 21 and 2 are connected to the intermediate, front and rear stages to equalize the in-phase distortion among the waveform distortions.
2 and the orthogonal distortion among the waveform distortions connected to the front and rear stages of the delay circuit? Variable weighting for equal ratio is done by circuits 31 and 3.
2 and each weighting mentioned above is the output of the circuit? and signal synthesis circuits 33 and 34 for synthesis.

It is a 3-tap transversal filter consisting of a 90° directional coupling circuit 40 that combines the outputs with a phase relationship of 90°, and the output is sent to the transmitter 7 in FIG. 2, and a portion is branched. and sent to the digital demodulator 2. The digital demodulator 2 includes a carrier wave reproducing circuit 44 using a Costas loop r that reproduces carrier wave sound through baseband processing, and a carrier wave reproducing circuit 44 that uses a Costas loop r to reproduce carrier wave sound through baseband processing. Receiving and modulating input wave? Synchronous detection 2 rows of 4-value baseband signal DI, e D,...
: *Is it a bit synchronized signal from the generated synchronous detection circuit 41 and its output? It is composed of a clock synchronization circuit 43 for regeneration. The control signal generation circuit q compares the demodulated two-column baseband signal Dp' + D + 2kH with four threshold values set in advance when there is no distortion, detects the deviation r, and identifies the intermediate tap. Variable weighting is applied to each control error signal Y′l Y of circuit 2o, and variable weighting other than the above is applied to circuit 21.22°31
．． 32 control error signals Y,, YQ (!: Purple occurs.

an identification regeneration/error signal generation circuit 42 for reproducing the 21-channel digital signals P, P', Q, and Q'v; an out-of-sync detection circuit 45 for detecting out-of-synchronization of the carrier wave regeneration circuit 44; and an identification regeneration/error signal generation circuit. 42 Exclusive OR circuit (EX-OR) for processing logical operations 51 to 53.
55-59. Exclusive N0I (Circuit (EX-NO 几) 5
4.60. Shift register 71.72.73.74
．． Each variable weighting circuit is configured based on the maximum slope method so that the peak value of waveform distortion is minimized by Narushima digital processing from integrating circuits 80 to 82, 91, and 92 with reset. Control signal r(-1)' (0)l (+1)
! d(-1)l d(+1)r occurs. This control signal generation circuit generates an error signal generated in response to distortion, which is conventionally known as the geometric ratio algorithm of an adaptive waveform controller, and an output signal of the equal ratio generator. Correlation with a certain time relationship? This is a circuit realized by a simple Ft'J configuration using a geometric ZF (zero forcing) type geometric algorithm. Each variable weighting is set to the initial value of the circuit, and F1 is set to improve the pull-in characteristic of the first order
has been completed. The details of the operation of this circuit and the detailed explanation of the discrimination/regeneration/error signal generation circuit 42 and the @integrator circuit with reset (80 to 82, etc.) can be found in Japanese Patent Application No. 56-215271 filed by the same applicant as the present invention. Please refer to it if necessary.

Traditionally, ZF type equirhi algorithm? In the adaptive waveform equalizer used, the delay time of each delay circuit of the transversal filter is usually selected to be equal to the reciprocal of the modulation rate, and the intermediate frequency band transversal filter has an intermediate frequency that is an integer of the modulation frequency. It is clear that it can be used without problems when it is twice the modulation frequency r, and is used in special cases where it can be selected to be an integer submultiple of the modulation frequency r.

However, the modulation frequency and intermediate frequency are restricted by other conditions, the radio frequency used is high, and therefore the method cannot be unconditionally applied to a wideband wireless transmission system in which the frequency fluctuation of the intermediate frequency is large. In the embodiment of the present invention described above, the delay time τr of the delay circuit 10.11 is not the reciprocal of the modulation frequency, but is slightly shifted, so that the signal S1 of the intermediate tap of the delay circuit and the signals S of the preceding and succeeding stages. and S2
Toga.

They are selected so that they are in phase with each other. Therefore, even if the intermediate frequency varies slightly, each (i) maintains an almost in-phase relationship, and the control loop converges and operates normally.On the other hand, the modulation frequency generally fluctuates little, and is the reciprocal of the modulation frequency of the delay time τ. Since the deviation from τr is not large, the uniformity ability remains unchanged.Contrary to the above explanation, the delay time τr intermediate frequency signals S□ and S.

and S2 are selected so that they are in opposite phase to each other.

A similar effect can be obtained by reversing the polarity of the control loops of So and S2. The selection of the above delay time τ is also described in detail in the aforementioned Japanese Patent Application No. 56-215271, so please refer to it if necessary.

In the above embodiment, the case of 16-value QAM was explained, but a similar configuration is possible for multi-value QAM other than 16-value and non-orthogonal multi-value amplitude modulation.

Since the polyphase phase keying (PSK) method can also be considered as a type of QAM, the present invention can be applied thereto. In the embodiment shown in FIG. 3, signals r are synthesized from the front, middle, and rear stages of two delay circuits having equal delay times through variable weighting circuits.
As shown in the intermediate frequency band transversal filter of the tap, configurations other than 3 taps are also possible, and the delay times do not necessarily have to be equal, and variable weighting for equalizing orthogonal distortion to the intermediate taps is added to the circuit r. Symmetrical circuit configurations can also be used. Also, the digital demodulator 2 performs carrier wave regeneration using a baseband processing method using Costas loop r?
Although the demodulator used here has been described, any type of demodulator can be used. The control signal generation circuit shown in FIG. 3 is an example of a simple circuit configuration for realizing the ZF type geometric algorithm used in the present invention. circuit can be used. For example, in the circuit of the embodiment, the identification reproduction/error signal generation circuit 42 uses variable weighting of the intermediate taps of the transversal filter as error signals Y, ', Yd for circuit control, and variable weighting of the intermediate taps other than the intermediate taps for circuit control. Although the circuit is configured to generate two types of error signals r and an error signal YY of plQ, a circuit configuration using a known method of using only one type of error signal r may also be adopted.

In addition, the circuit of the embodiment is an integration circuit with reset (80 to 82
etc.) 2 is used to set the initial value of each variable weighting circuit, but a separate voltage generator r for initial value setting is provided, and the output r of the voltage generator is determined by the output of the out-of-synchronization detection circuit 45. A known method of switching and supplying variable weights to the circuit may be used. Furthermore, is the signal that activates reset function 2 also carrier synchronized? Is there a method other than the detection method of the embodiment, such as detecting a bit synchronization sound or monitoring the code error rate and performing a reset 7 when it exceeds a certain value? It can also be adopted.

As explained in detail above, according to the heterodyne repeater with waveform equalizer of the present invention, an intermediate frequency Wj transversal filter, a digital demodulator, a control signal generator and... By equipping a digitally modulated wideband wireless transmission signal with waveform equalization, it can be relayed heterodyne, and each relay station has a modulator? This has the effect of simplifying the configuration of the relay device and making it possible to configure an economical digital wireless line.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional detection repeater with a waveform equalizer, FIG. 2 is a block diagram of an embodiment of a heterodyne repeater with a waveform equalizer according to the present invention, and FIG. 3 is an adaptation of FIG. FIG. 2 is a block diagram of one embodiment of a type waveform equalizer. ■... Receiving section, 2... Digital demodulator, 3... Baseband frequency band transversal filter, 4... Discriminator 1 51
... Control signal generator 16 ... Modulator %7
. . . Transmission section, 8 . . . Intermediate frequency band transversal filter, 9. q...Adjustable transversal equalizer, 10.11...Delay circuit, 20.21.22.31.32...Variable weighting circuit, 33 .34...Signal synthesis circuit, 40
... Directional coupling circuit, 41 ... Synchronous detection circuit 142 ... Discrimination reproduction/error signal generation circuit, 43 ... Clock synchronization circuit, 44 ... ...
・Carrier regeneration circuit, 45...Out-of-synchronization detection circuit% 51.52.53.55゜59...Exclusive OR circuit, 54.60...Exclusive N0i (,
Circuit, 71.72.73.74...Shift register, 80.81.82.91.92...Ki integration circuit with reset. ′---1・

Claims (1)

[Claims] A receiving section that converts and amplifies the digitally modulated received signal of an unrelated frequency band to an intermediate frequency band, a transmitting section that amplifies and converts the output of this receiving section, and sends out a transmitted signal of a radio frequency band. t-heterodyne relay device, an intermediate frequency band transversal filter inserted between the receiving section and the transmitting section, and a digital demodulator that splits the output of the transversal filter and demodulates the multi-channel baseband signal. , a control signal generator for generating a control signal 2 for controlling the transversal filter 2 by comparing and identifying the output r of the digital demodulator with a plurality of predetermined threshold values; and a waveform equalizer having r. A heterodyne repeater with a waveform equalizer.