JPS622729A - Digital radio communication system - Google Patents

Abstract

PURPOSE:To prevent the generation of malfunctions in any case with a digital radio communication system by delaying optionally the base band signals of one of (n) series of those signals at the transmitter side and at the same time correcting the phase relation of (n) series of base bands orthogonal to each other at the receiver side. CONSTITUTION:When bipolar signals 100v and 100h are cut off, at least one of (n) series of scrambled modulation input signals 103v and 103h is delayed optionally to secure the no-correlation between the modulation signals orthogonal to each other. The same state is also secured with input of the same code series even though both signals 100v and 100h are not cut off at a time. Each signal series is delayed by 3-0 bits against a base band signal 105h at the receiver side before both base band signals 105v and 105h which are decoded by a discriminating circuit are sent to a reception signal processor. Thus all signal series are delayed by 3 bits to the signal 105v. As a result, the phase relation between signals 105'v and 105'h can be corrected to that between signals 103v and 103h.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless communication system, and more particularly to an orthogonal polarization digital wireless communication system equipped with a cross-polarization interference removal circuit.

[Conventional technology]

In microwave and sub-millimeter wave band digital wireless communication systems, a bipolar digital multiplexed signal sent from a multiplexing terminal device is processed in a 9th order manner. That is, the signal is first converted into a unipolar signal in the transmission signal processing device provided on the transmission terminal side, then speed-converted, and additional bits such as a wireless section monitoring/equality check bit and a hum synchronization signal are inserted. Furthermore, the transmitted signal is subjected to a scrambling process to flatten the spectral signal and facilitate recovery of bit synchronization on the receiving side.

It is sent out to the modulator of the transmitting device. This scrambling process is generally performed by calculating the modulo-2 sum of an input signal and a pseudo-random code obtained from an m-sequence (longest linear code sequence) code sequence generator using a shift lenoster. On the other hand, on the receiving end station side, descrambling processing is performed using the same pseudorandom code as on the transmitting end station side, and the original signal is restored.

In conventional digital wireless communication systems, an interleaved frequency arrangement is used in which the carrier frequencies of two orthogonal polarized waves are arranged so that the carrier frequency of each polarized wave is midway between the carrier frequencies of mutually opposite polarized waves. There is. In order to simplify the device configuration and improve mass productivity, the same transmission signal processing device is used for each digital multiplexed signal, and therefore the same pseudo-random code is used for scrambling processing.

In order to make the use of nine frequency bands even more effective in recent years,
Co-channel frequency allocation using orthogonal polarization has attracted attention,
Research and development for this practical application is being actively conducted. One of these problems is the problem of eliminating cross-polarization interference that occurs between orthogonal polarizations due to rain, etc., and two various methods have been proposed. Among them, the method proposed in Japanese Patent Application Laid-Open No. 55-133156 attracts attention as a method suitable for the V'ir Innotal wireless communication system. This method detects cross-polarization interference by calculating the correlation from the demodulated baseband signals of the two polarizations without using the Ceylon signal.In this method, the data signal is sent with two orthogonal polarizations. It is based on the assumption that they are mutually independent and uncorrelated. This precondition is satisfied when data signals are normally input to the two polarized waves, and therefore the interference cancellation circuit operates normally.

[Problem that the invention seeks to solve]

However, if scrambling processing similar to the conventional method is performed, there may be cases where the digital multiplexed signals from the multiplexing terminal equipment for both +" (vertical) and H (horizontal) polarizations are disconnected, or A problem occurs when all inputs to the network terminal equipment become "0" (this condition occurs even during line operation, but is particularly problematic during line tests during construction). That is, as will be described in detail later, in the above case, the same code sequence is sent to both V and H polarizations from the transmission signal processing device that performs scrambling and processing.

There is a problem in that the receiving system including the interference cancellation circuit malfunctions.

An object of the present invention is to eliminate the above-mentioned problems, and to prevent the same code sequence from being outputted in the same phase from the transmission signal processing apparatus for both the V and H polarizations under any circumstances.

It is an object of the present invention to provide a digital wireless communication system in which malfunction does not occur in a receiving system including an interference cancellation circuit.

[Failure to solve the problem]

The present invention provides a multi-phase multi-level digital wireless communication system using two mutually orthogonal polarized waves, in which at least one series of baseband signals of at least one set of n series of baseband signals is transmitted to a transmitting side. Then, by arbitrarily delaying the mutually orthogonal multiphase multilevel digital modulation signals, the relationship between the mutually orthogonal multiphase multilevel digital modulation signals is made uncorrelated, and on the receiving side, the demodulated baseband signal is sent to a delay circuit as a set of n sequences complementary to the delay applied on the transmitting side. are provided and configured to correct the phase relationship of each of the n series of baseband signals that are orthogonal to each other.

〔Example〕

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

First, the structure and operation of the transmitter and receiver devices to which the present invention is applied will be explained. FIG. 1 is a block diagram showing an example of the configuration of a transmission signal processing device on the transmission terminal station side in an orthogonal polarization digital wireless communication system.

FIG. 2 is a block diagram showing an example of the configuration of an interference cancellation and waveform equalization circuit of a reception terminal station. In the following description, the vertical system will be denoted by V, and the horizontal system will be denoted by h.

In FIG. 1, lv and lh are bipolar signals 100v and 100h input from a multiplexing terminal equipment (not shown).
The unipolar signal 101V.

101hi/i: code conversion circuit to convert p 2 vr
This is a parity counting circuit that counts the number of "1's" or "0"s in the 2 hD unipolar signal and determines whether it is an odd number or an even number.

3v, 3b are sync signals from staff operation,・
Speed conversion circuit that inserts error check bit etc. 4v, 4h are speed converted signals 102v, 102h
This is a scrambling circuit that performs scrambling processing on each. Furthermore, 5v.

5h is a code sequence generator that generates pseudo-random codes (m-sequence linear codes) for scrambling processing. Scrambled modulated input signals 103v, 103h#i
The signal is sent to a modulator of a transmitting device (not shown) for each polarized wave. V
, H, and each of the transmission signal processing devices 6v, 6h for each polarization and each transmission signal processing device (not shown) for other carrier frequencies are controlled by a common bit clock generator 7 and frame clock generator 8. In the conventional method, each code sequence generator 5
v and 5h are all the same, and the same pseudo-random code is used for scrambling processing of each polarization of V and H.

Figure 2 shows Japanese Patent Application Laid-Open No. 55-133156, which removes cross-polarization interference using the correlation of demodulated baseband signals.
1 is a block diagram of a configuration example of a receiving circuit including an interference cancellation circuit using a correlation method proposed in the publication; FIG. In FIG. 2, the detection outputs 104V and 104h of the V r H polarized waves detected by the detectors 9ma and 9h are passed through the waveform fixtures 10v and 10h, which are composed of transpersal filters, respectively, to the identification judgment circuit 11v. . on the other hand.

The detected outputs 104v and 104h#'i of each polarized wave are branched, respectively, and coupled to the oppositely polarized signal through interference removal circuits 12h and 12ma (comprised of transversal filters). The inputs of the waveform equalization correlators 13v, 13h and the interference control correlators 14v, 14h are the baseband signal 105v of each polarization, the LO5h, and its ± bits (k is an integer fil, 2..., transformer (The upper limit is determined by the number of stages of the parsal filter) as a shifted signal.

Error signal 106 from the identification judgment circuit 11v, llh,
By determining the correlation with 106h, waveform distortion and cross-polarization interference components are respectively detected, and the waveform equalizer and interference cancellation circuit are controlled so that each error component is minimized. In other words, the waveform distortion component included in the error signal 106v of the V polarization identification/judgment circuit 11v is
The waveform equalization correlator 13v detects the V-polarized baseband signal 105 and the reference signal bit-shifted to ±, and the waveform equalizer 10v uses this detection signal! It is equalized by controlling lI. On the other hand, the interference component from the H polarization is detected by the interference control correlator 14V using the baseband signal 105h of the H polarization and the reference signal bit-shifted to ±, and is removed by controlling the interference cancellation circuit 12v. .

Here, two polarized baseband signals 105v and 105h
If they are uncorrelated, the waveform distortion component and the cross-polarization interference component can be separated and detected from the error signal 106v. However, as mentioned above, the signals 1057 and 1
When 05h has the same code and sequence and almost the same phase (within a bit shift of 2), the waveform equalization correlator 13v and the interference control phase opener 14v output the waveform distortion component and the cross polarization component at O, where the reference signal is the same. It will no longer be possible to separate and detect the Such a state is represented by the bipolar signal 100vt100 in FIG.
This occurs when both h are disconnected. At this time, the input 102 of the scramble circuits 4v and 4h.

Both 102h are a series of "0" or "1".

In this case, the pseudo-random codes are output as they are from the scrambling circuits 4v and 4h, and the code sequence generator 5V,
If the pseudorandom codes generated in 5h are the same, the modulated human input signals 103v and 103h will be the same.

In order to prevent this situation from occurring, the first step is to
In the figure, a scrambled modulated input signal 103
At least one sequence (out of n sequences) of one of v and 103h may be arbitrarily delayed so that the relationship between mutually orthogonal modulated signals becomes uncorrelated. In addition, bipolar signal 100V.

Even if 100h are not disconnected, a similar situation will occur if the same code sequence is input. bipolar signal 100
Even in the multiplexing terminal equipment that sends out V, 100h2, scrambling processing is usually performed to facilitate the reproduction of the bit synchronization signal during unmanned signalling, and all inputs to the multiplexing terminal equipment are line-disrupted. When used, the same code sequence for scrambling processing may be sent.

Figures 3 and 4 show 16 QAM (orthogonal amplitude modulation) as a modulation method in orthogonal polarization digital wireless communication lines.
In this embodiment, signals scrambled using the same pseudo-random code are set to be uncorrelated with respect to two orthogonal polarized waves.

In Fig. 3(a), 103v and 103h are modulated input signals scrambled with the same pseudo-random code, and in Fig. 3(b), 103'h is a 7-ring flop F as a delay circuit on each signal line. This is a modulated input signal that has been processed to be uncorrelated with the input signal 103v by connecting them as shown. These flip-flops F are provided in the scramble circuit shown in FIG. 1 or on the output side. The signals 103v, 103'h are sent to a modulator (not shown) of the transmitting device.

In Fig. 4(a) and (b), 105v, 105
h is.

The baseband signal decoded by the identification determination circuit in FIG. 2,
105'v and 105'h are 103v and 105'h by connecting a flip-flop fF to each signal line
These signals are processed to be in the same sequence as the signal of 103h, and are sent to a reception code processing device (not shown). Furthermore, 107, 108, and 109 are focus clock signals for the respective signals.

Now, before the modulated input signals 103v and 103h scrambled with the same random code on the transmitting side are sent to the modulator of the transmitting device of each polarized wave, as shown in FIG.
As shown in b), each signal sequence is set to 0 for the signal 103h.
Bit, 1 bit, 2 bit.

Signals 103 and 10 are delayed by 3 bits.
3' Let the h code sequence be uncorrelated. After this.

The signals 103v, 103'h are sent to the modulator of the transmitter of each polarization.

Next, on the receiving side, before the baseband signals 105v and 105h decoded by the identification determination circuit are sent to the received signal processing device, as shown in FIGS. 4(a) and 4(b), each signal is Delay the series by 3 bits, 2 bits, 1 bit, and 0 bits.

By delaying all signal sequences by 3 bits for 105 m, 105'v and 105'h become 103v and 10
The phase relationship can be corrected to 3h.

Thereafter, signals 105'v and 105'h are sent to the received signal processing device.

It goes without saying that the number of stages and connections of flip-frogs are set depending on the modulation method, the number of multi-values, and the like.

Furthermore, in the above description, each signal sequence is all delayed by 3 bits with respect to the signal 105vK on the receiving side, but this is necessary in the case of synchronous switching, and is not necessary if synchronous switching is not performed.

〔Effect of the invention〕

As explained above, according to the present invention, in an orthogonally polarized digital wireless communication line equipped with a cross-polarized interference cancellation circuit using a correlation method, when input signals of both V and H polarizations are disconnected at the same time, Even if signals of the same code sequence are input, there is no risk of malfunction on the receiving end station side, and normal operation is guaranteed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a transmission signal processing device on the transmitting end station side of an orthogonally polarized digital wireless communication line to which the present invention is applied, and FIG. 2 shows interference cancellation and waveform equalization on the receiving end station side. Block diagram showing an example of circuit configuration, Figure 3 (a) j
(b) is an example of a configuration of a process for making orthogonal modulated signals uncorrelated on the transmitting side 1. FIG. 4(a), ω) is a process for correcting the phase relationship of demodulated baseband signals on the receiving side. It is a figure showing an example of composition. In the figure, lv, lh - code conversion circuit, 2v, 2h...
Solitary counting circuit, 3v, 3h... speed conversion circuit. 4v, 4h... scramble circuit, sv, sh...
Code sequence generator, 6v, 6h...transmission signal processing device. 7... Focus clock generator, 8... Frame clock generator, 9v, 9h-... Detector, 10v, 10h
...Waveform fixtures, llv, llh...Identification judgment circuit. 12v, 12h...interference removal circuit, 13v
, 13h... waveform equalization correlator, 14v, 14h...
Interference control correlator, F...Flip frog.

Claims (1)

[Claims] 1. In a multiphase multilevel digital wireless communication system that uses two mutually orthogonal polarizations, the transmitting side can arbitrarily transmit at least one series of baseband signals from at least one of the n series of baseband signal sets. The demodulated baseband signal is delayed by 20 seconds to make the relationship between the mutually orthogonal multiphase multilevel digital modulation signals uncorrelated, and on the receiving side, a delay circuit is provided complementary to the delay applied to the demodulated baseband signal on the transmitting side by forming n sequences as a set. A digital wireless communication system characterized in that the phase relationship of each of the n series of baseband signals that are orthogonal to each other is corrected.