JPH063895B2 - Scramble processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a scramble processing system, and more particularly to a scramble processing system used in an orthogonal polarization digital wireless communication line provided with a cross polarization interference canceling circuit.

[Conventional technology]

In the microwave and quasi-millimeter wave band digital wireless communication lines, the bipolar type digital multiplexed signal sent from the multiplexing terminal device is first converted into a unipolar signal in the transmission signal processing device provided at the transmitting terminal side. Converted and speed converted to insert parity check bits for wireless section monitoring, additional bits such as frame synchronization signals, and scramble processing to facilitate flattening of the transmission spectrum and reproduction of bit synchronization on the receiving side. After receiving it, it is sent to the modulator of the transmitter. This scrambling process is generally performed by obtaining a modulo 2 sum of a pseudo random code obtained from an m-sequence (longest linear code sequence) code sequence generator using a shift register and a receiving end. On the station side, the same pseudo-random code as on the transmitting terminal side is used for descrambling to restore the original signal. In the conventional digital wireless communication system, the interleaved frequency arrangement is used in which the carrier frequencies of two orthogonal polarizations are arranged such that the carrier frequencies of the respective polarizations are in the middle of the carrier frequencies of the opposite polarizations. 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.

[Problems to be solved by the invention]

In recent years, in order to make the use of frequency bands even more effective,
Co-channel frequency allocation, which uses the same carrier frequency for orthogonal polarization, has attracted attention, and research and development for its practical use are being actively conducted. One of them is the problem of removing cross-polarization interference that occurs between orthogonal polarizations due to rainfall, etc., and various methods have been proposed, but the method proposed in JP-A-55-133156 is digital. It attracts attention as a method suitable for wireless communication systems. This method detects cross-polarization interference by calculating the correlation from the demodulated baseband signals of the two polarizations without using the pilot signal, and the data signal sent in the two orthogonal polarizations is It is based on the premise that they are independent and uncorrelated. This precondition is satisfied when the data signals are normally input to the two polarized waves, and therefore the interference canceller operates normally. However, if the same scrambling process as in the conventional system is performed, the digital multiplexed signals from the V and H polarized wave multiplexing terminal devices are both disconnected, or the input of the multiplexing terminal device is lost. All become "0" (such a condition occurs during line operation, but it becomes a particular problem at the time of a line test at the time of construction), which causes a problem. That is, as will be described in detail later, in the above case, the same code sequence is sent to both V and H polarized waves from the transmission signal processing device that performs the scrambling process, and the reception system including the interference cancellation circuit malfunctions. There is a point. The object of the present invention is to eliminate the above-mentioned problems, and in any case, the same code sequence is not output in the same phase from the V and H polarized wave transmission signal processing devices, and a reception system including an interference cancellation circuit is provided. An object of the present invention is to provide a scramble processing method in which malfunction does not occur.

[Means for solving problems]

The scramble processing method of the present invention is a scramble processing method for an orthogonal polarization digital wireless communication line that transmits different information in two polarizations that are orthogonal to each other. It is configured so that it has no correlation with the polarized waves.

[Action]

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a transmission signal processing device on the transmission terminal side of an orthogonal polarization digital wireless communication line, and FIG. 2 is a configuration example of an interference cancellation and waveform equalization circuit on the reception terminal side. It is a block diagram showing. In FIG. 1, 1v, 1h
Is a code conversion circuit for converting bipolar signals 100v, 100h input from a multiplexing terminal device (not shown) into unipolar signals 101v, 101h, 2v, 2h is the number of "1" or "0" of the unipolar signal Parity counting circuit for determining whether it is an odd number or an even number, 3v, 3h are speed conversion circuits for inserting frame synchronization signals, parity check bits, etc. by stuffing operation, 4v, 4h are speed conversion signals 102v, 102
A scrambling circuit 5v, 5h for scrambling h respectively is a code sequence generator for generating a pseudo-random code (m-sequence linear code) for scrambling, and scrambled modulated input signals 102v, 103h.
Is sent to a modulator of a transmitter (not shown) for each polarization.
The transmission signal processing devices 6v and 6h for V and H polarizations and the transmission signal processing devices for other carrier frequencies are controlled by a common bit clock generator 7 and frame clock generator 8. In the conventional method, the code sequence generators 5v and 5h are all the same, and the same pseudo-random code is used for scrambling the V and H polarizations.

FIG. 2 shows an example of the configuration of a receiving circuit provided with an interference canceling circuit by the correlation method proposed in Japanese Patent Laid-Open No. 55-133156, which cancels cross-polarization interference by utilizing the correlation of demodulated baseband signals. It is a block diagram. In FIG. 2, the detector 9
Detection output of V and H polarized waves detected at v and 9h 104v and 104
h is a discrimination / determination circuit 11v, which passes through waveform equalizers 10v and 10h each formed of a transversal filter.
11h, decoded here to baseband signal
It becomes 105v, 105h and is sent to a reception signal processing device (not shown). The detection outputs 104v and 104h of the respective polarized waves are branched and coupled to the signals of the reverse polarized waves through the interference elimination circuits (configured by transversal filters) 12h and 12v. The waveform equalizing correlators 13v and 13h and the interference control correlators 14v and 14h are the baseband signals 10 of the respective polarizations.
5v, 105h and ± j bits thereof (j is an integer from 1 to n, where n is an integer determined by the number of taps of the transversal filter) The shifted signal is used as a reference signal, and the discrimination determination circuit 11
By obtaining the correlation with the error signals 106v and 106h from v and 11h, the waveform distortion and the cross polarization interference component are detected, and the waveform equalizer and the interference cancellation circuit are controlled so that each error component is minimized. Is configured to. That is, the waveform distortion component included in the error signal 106v of the V-polarized wave discrimination and determination circuit 11v is the V-polarized baseband signal 105v.
And the reference signal shifted by ± j bits thereof are detected by the waveform equalization correlator 13v and equalized by controlling the waveform equalizer 10v. On the other hand, the interference component from the H polarization is detected by the interference control correlator 14v by the baseband signal 105h of the H polarization and the reference signal shifted by ± j bits.
The interference removal circuit 12v is controlled and removed. If the baseband signals 105v and 105h of both polarizations are uncorrelated,
The waveform distortion component and the cross polarization interference component can be separated and detected from the error signal 106v, but when 105v and 105h have the same code sequence and the same phase (within 2n bit shift), the waveform equalizing correlator Since 13v and the interference control correlator 14v have the same reference signal, the waveform distortion component and the cross polarization component cannot be detected separately, and normal operation is not performed.

Such a state is shown in FIG.
It occurs when both v and 100h are disconnected. At this time, the inputs 102v and 102h of the scramble circuits 4v and 4h are both "0".
Or, since it is a series of "1", the scramble circuit 4v,
If the pseudo random code is output from 4h as it is and the pseudo random code generated by the code sequence generators 5v and 5h is the same, the modulated input signals 103v and 103h are the same. In order to prevent such a situation from occurring, V, H
It suffices that the pseudo-random codes generated by the polarization code sequence generators 5v and 5h are not the same but uncorrelated. Even if the bipolar signals 100v and 100h are not disconnected, the same state occurs if the same code sequence is input. Even in the multiplexing terminal equipment that sends out the bipolar signals 100v and 100h, normally, scrambling is performed to facilitate the reproduction of the bit synchronization signal when there is no input signal, and all of the inputs of the multiplexing terminal equipment are When the channel is not used, the same code sequence for scrambling may be sent.

〔Example〕

There are various possible methods for making the pseudo-random codes generated by the code sequence generators 5v and 5h uncorrelated. The code sequence generator has an N-stage shift register as shown in FIG.
= 7) is used, the shift register Si set by the reset signal 107 (frame clock signal)
By changing the state of the initial value input 108 of (i is 1 to 7), the bit phase between the two m-sequence codes is significantly increased (considering the line length difference, the propagation time difference due to fading, and the tap number of the transversal filter). And more than the number of bits so that the malfunction condition does not occur),
(2) A method of changing the location of the feedback tap coupled to the half adder 15 or changing the number of half adders to generate different m-sequence codes, and (3) a method of changing the number N of shift register stages is there. Incidentally, 109 in FIG. 3 is a bit clock signal.

In an actual orthogonal polarization digital wireless communication line, a protection line is provided outside the working line, and a non-bit error synchronous switching system is used for switching the line from the working line to the protection line. This synchronization switching is performed after the normal scrambling process on the transmitting terminal side, that is, after the scrambling circuits 4v and 4h in FIG. Therefore, in the case where protection lines are provided for a large number of V and H polarization working lines, in order to arbitrarily switch the V and H polarization working lines to each protection line, there is no need for scrambling processing. As the correlative pseudo-random code, as shown in FIG. 4 (a), A1, A2 ... Ak corresponding to the working lines V1, V2 ... Vk,
Working lines H1, H2 ... B1, B2 corresponding to Hk ...
Bk, C corresponding to the protection line SP1, and the protection line SP2
(2k + 2) types corresponding to D are required. On the other hand, synchronous switching is performed by the scramble circuits 4v and 4h shown in FIG.
If it is carried out before, the two types of uncorrelated pseudo-random code may be A and B as shown in FIG. 4 (b).
Further, in the multi-carrier system for transmitting a plurality of wireless carriers by one wireless device, which has recently received a lot of attention, with the carrier arrangement of FIG. 5 (a) using both V and H polarized waves as a backup line, the working line V1 .. Vk and H1 ..... If any carrier of Hk is switched to be connected to any carrier of V and H polarized waves of the protection line SP, the types of pseudo-random codes required for scrambling processing are shown in the figure ( 8k +
2) Types are required (pseudo-random code A11, A12, A13, A14 corresponding to the four carriers of the working line V1 ... Pseudo-random code Ak corresponding to the four carriers of the working line Vk
1, Ak2, Ak3, Ak4 and pseudo-random code B11, B12, B13, B14 corresponding to the four carriers of the working line H1, ... Pseudo-random code B corresponding to the four carriers of the working line Hk.
8 types of k1, Bk2, Bk3, Bk4 and two types of pseudo-random codes C and D corresponding to the protection line SP). On the other hand, in order not to increase the types of pseudo-random codes, the synchronous switching is performed before the scramble circuit of each carrier as described above, or the switching range is somewhat limited.
As shown in FIG. 5 (b), the working lines V1 ... Vk and H1 ...
If the numbers 1 to 4 assigned to the respective carriers of Hk are switched so as to correspond to the numbers 1 to 4 assigned to the 4 carriers of the protection line SP, the pseudo random code may be of two types. The method of FIG. 5 (b) can simultaneously rescue each carrier of V and H polarized waves which are orthogonal to each other on the adjacent two frequencies by the protection line at the same time, and is considered to be an effective method from the viewpoint of fading recovery.

In the above description, the case has been described in which the transmission signal processing device for V and H polarizations operates with the common bit and frame clocks as shown in FIG. 1, but with the independent clocks instead of the common clocks. However, if the pseudo random code for scrambling of the V and H polarizations is the same, the same malfunction may occur on the receiving side. In this case, of the three methods for making the signal of the code sequence generator uncorrelated, the method (1) of shifting the phase cannot be applied. Further, FIG. 2 shows an example in which the interference canceling circuit is provided in the base band, but it may be provided in the IF band and the same applies when quadrature modulation is used.

〔The invention's effect〕

As described in detail above, according to the scramble processing method of the present invention, in the orthogonal polarization digital wireless communication line equipped with the cross polarization interference cancellation circuit by the correlation method, V, H
Even when the input signals of both polarizations are disconnected at the same time, or even when signals of the same code sequence are input, there is no fear of causing a malfunction on the receiving end side, and there is an effect that normal operation is guaranteed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a transmission signal processing device on the transmission terminal side of an orthogonal polarization digital wireless communication line to which the present invention is applied, and FIG. 2 is interference cancellation and waveform equalization on the reception terminal side. FIG. 3 is a block diagram showing a circuit configuration example, FIG. 3 is a block diagram of an embodiment of a code sequence generator for generating a pseudo-random code, and FIGS. 4 (a) and 4 (b) are orthogonal polarization digital wireless communication lines. FIGS. 5 (a) and 5 (b) are explanatory diagrams showing an example of arrangement of the pseudo-random codes for each carrier, and FIGS. 5 (a) and 5 (b) are illustrations showing an example of arrangement of the pseudo-random codes in the case of the multi-carrier system. 1v, 1h ... code conversion circuit, 2v, 2h ... parity counting circuit, 3v, 3h ... speed conversion circuit, 4v, 4h ...
... Scramble circuit, 5v, 5h ... Code sequence generator,
6v, 6h ... Transmission signal processing device, 7 ... Bit clock generator, 8 ... Frame clock generator, 9v, 9h
…… Detector, 10v, 10h …… Waveform equalizer, 11v, 11h …… Identification judgment circuit, 12v, 12h …… Interference removal circuit, 13v, 13h …… Waveform equalization correlator, 14v, 14h …… Interference Control correlator, 15 ... Half adder.

Claims (1)

[Claims] 1. A scramble processing method for an orthogonal polarization digital wireless communication line for transmitting different information in two polarizations orthogonal to each other, wherein a pseudo-random code for performing scrambling is applied to the two polarizations orthogonal to each other. The scramble processing method is characterized in that they are set so as to have no correlation with each other.