JP2001189710A - Method and device for monitoring different polarization interference quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an XPD value (different polarization interference ratio) without detouring (stopping wave) a line in operation about a monitoring method and its device for different polarization interference quantity. SOLUTION: Different polarization interference signals of a plurality of XPD levels and noise are preliminarily inputted to a main system receiving circuit 38, and a C/N-XPD (different polarization interference quantity) characteristic at a time when the bit error rate BER of its demodulation output is a prescribed value (e.g. 1×10-4). When the circuit 38 is operated, a certain received polarization signal CH1-in is branched, one is received and demodulated by the circuit 38 and the other is received and demodulated by an XPD monitor circuit 70 of the same characteristic respectively, noise N where the bit error rate BER of its demodulation output becomes the prescribed value (1×10-4) is also added to the input of the circuit 70, and the operation XPD value of the circuit 38 is estimated from a C/N value and a C/N-XPD characteristic at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for monitoring the amount of interference of different polarizations, and more particularly, to a method and apparatus suitable for a multiplex radio apparatus having a co-channel arrangement using the same frequency as horizontal / vertical polarization. The present invention relates to a method and an apparatus for monitoring a different polarization interference amount.

In this type of radio communication system, since the same frequency is used as horizontal / vertical polarization, interference occurs between cross polarizations. To cancel the interference, the amount of different polarization interference for each channel is known. There is a need.

[0003]

2. Description of the Related Art FIGS. 4 and 5 are diagrams (1) and (2) for explaining the prior art, and FIG. 4 shows a partial configuration of a conventional multiplex radio communication system. 20
0 is wirelessly connected via antennas 35 and 36.
In the transmitting station 100, 31 _{1 to} 31 _n are channel corresponding units of each wireless communication channel (line) CH, 32 is a modulation unit thereof, 33 is a transmission unit, 34 is a multiplexing unit of a radio signal to be transmitted,
In addition the receiving station 200, 37 polarization separating part of the radio signal received, 38 ₁ to 38 DEG _n channel corresponding portion of each radio communication channel CH, 39 is the reception section, 40 is a demodulator.

In transmitting station 100, the signal of CH1 is C
Modulated and amplified by the H corresponding portion 31 ₁ is transmitted from the antenna 35 as a vertical (V) polarization. The CH _{n + 1} signal is modulated and amplified by the CH corresponding unit 31 _{n + 1} and transmitted from the antenna 35 as horizontal (H) polarization. In the receiving station 200, signal polarization separating section 37 in the demultiplexed CH1 (corresponding to V-polarized wave) is received and demodulated by the CH corresponding portion 38 ₁ and CH _n demultiplexed by the polarization separating section 37 _{The +1} signal (corresponding to H polarization) is received and demodulated by the CH corresponding unit 38 _{n + 1} .

[0005] By the way, generally, in a radio channel having a co-channel arrangement, a channel allocated to a radio system is
As shown in the drawing, for example, CH1 to CHn are sequentially added on the V side, and when the channel on the V side ends, the H side is switched to the CH side.
Expansion is performed sequentially from _{n + 1} . At this time, CH1
V polarization and the H polarization of CH _{n + 1} have the same frequency, so that interference occurs between the V and H polarizations.

FIG. 4 additionally shows transmission / reception spectra of V and H polarizations. Now, on the transmitting side, the V polarization VT of CH1 and CH
_{Even if} there is no interference with the _{n + 1} H polarization HT, if the antenna passes through the antenna, the receiving side will not be shown due to the mounting angle error between the transmitting / receiving antennas 35 and 36 and various disturbances in the wireless section. As described above, polarization interference occurs between V and H. For example, CH
The interference polarization HI from CHn _{+ 1} is superimposed on the reception polarization VR of CH1, and the interference polarization VI from CH1 is superimposed on the reception polarization HR of CHn _{+ 1} . That is, each channel CH1,
At CH _{n + 1} , the respective self-polarized signal and the differently-polarized waves lower than this by the XPD value (differential polarization interference amount: D / U value of leakage from the self-polarized signal and the different-polarized signal) And signals are received. Therefore, conventionally, in order to prevent such a deterioration of the degree of discrimination between the V and H polarizations in the antenna, a cross polarization interference compensator (XPIC) described below is provided, and a different polarization signal is provided for each channel. Cancellation of interference components from is performed.

FIG. 5 shows a configuration of a conventional demodulation unit 40. In the figure, reference numerals 51 and 52 require (constant) each received signal (IF signal) input from the own-polarized wave and the different-polarized wave receiver.
(AGC circuit) that amplifies the signal to an amplitude level of 54, 54 is a local oscillation circuit (LO), 55 and 56 are mixers for detection (MIX), 57 and 58 are A / D converters (A / D), 6
1 is a signal processing unit for performing digital demodulation processing of the main signal, 6
2 is an FEC operation unit for performing error detection and correction of the demodulated signal,
A signal processing unit (XPIC) 63 generates a signal for cross-polarization interference compensation.

The signal is converted into an intermediate frequency signal by a receiving section 39,
The CH1 main signal (received polarization V
R system) is gain-adjusted (with constant amplitude) by the AGC circuit 51.
The signal is further detected by a mixer 56, and detected by an A / D converter 57.
It is converted to a digital signal. Also, demodulation of this CH1
The part 40 includes CH_{n + 1}To the intermediate frequency signal by the receiver 39
Converted CH_{n + 1}Signal (received polarization HR system)
The signal is gain-adjusted by the AGC circuit 52
(With constant amplitude), and further detected by the mixer 56.
The digital signal is converted by the D converter 58. Signal processing
The unit 61 demodulates the main signal of CH1 by digital processing.
In both cases, at this time, the cross polarization
Included in CH1 main signal demodulated signal due to interference compensation signal
CH_{n + 1}Cancels HI component of interference polarization
I do. Further, the output signal is erroneous in the FEC operation unit 62.
A terminal device (not shown) that performs detection and necessary error correction.
Is output to

Now, in such a communication system, a line deterioration state (for example, XP
D value) must be measured, but in the past, the state of line deterioration was measured by the following means. That is, after the operating system is stopped (or detoured), first, only the CH1 V-polarized signal is transmitted from the transmitting station 100, and the level of the self-polarized signal is input at the input of the receiving unit 39 of the receiving station 200. Is measured using a spectrum analyzer or the like.
Only the H _{n + 1} H-polarized signal is transmitted, and the level of the differently-polarized signal (H-polarized signal) is measured at the input of the receiving unit 39 of the receiving station 200 using a spectrum analyzer or the like. And
The XPD value is calculated using these measurement results, and the state of the line deterioration is acquired.

[0010]

However, in the conventional measurement of the line degradation state (XPD value), the level of both the own polarization and the different polarization is directly measured at the input of the receiving section 39 of the receiving station 200. Therefore, there are the following problems. That is, since the self-polarized signal including the leakage of the differently-polarized signal is input to the receiving unit 39 during operation, even if these signals having the same frequency are measured with a spectrum analyzer, the respective levels are not changed. It cannot be measured individually, but only one of the higher levels (usually the self-polarized signal has a higher level) can be measured. Therefore, XPD
In order to measure the value, the operating system is temporarily stopped (or bypassed) so that the different polarization signal is not buried in the own polarization signal, and the transmission station 100 transmits only the different polarization signal. To measure the level of the different polarization signal, and it is difficult to measure the line degradation state (XPD value) without stopping (or bypassing) the operation system.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object the purpose of the present invention is to provide a circuit degradation state (XPD value) without affecting the main signal system even during line operation.
It is an object of the present invention to provide a method and apparatus for monitoring the amount of interference of different polarizations, which enables measurement of the amount of interference.

[0012]

The above-mentioned problem is solved, for example, by referring to FIG.
Is solved. That is, in the method of monitoring the amount of different polarization interference according to the present invention (1), different polarization interference signals of a plurality of XPD levels are input to the input of the main signal receiving circuit 38 in advance, and noise is input to the demodulator 40. In addition, the C / N-XPD (different polarization interference amount) characteristic when the bit error rate BER of the demodulated output becomes a predetermined value (for example, 1 × 10 ⁻⁴ ) is measured, and the main signal system reception is performed. In the operation of the circuit 38, the output of the receiving unit 39 of a certain received polarization split signal CH1-in is branched, and one of the branched signals is divided into the demodulation unit 40 of the main signal receiving circuit 38 and the other (preferably having the same configuration as this). The demodulation is performed by the XPD monitor circuit 70A, and the bit error rate BER of the demodulated output is input to the input of the XPD monitor circuit 70A.
Is added to the predetermined value (1 × 10 ⁻⁴ ), and the XPD value of the main signal receiving circuit 38 is estimated from the C / N value at that time and the C / N-XPD characteristic. Things.

In FIG. 1, C / N-XPD (different polarization interference amount) characteristic data is obtained by inputting different polarization interference signals of a plurality of XPD levels to a main signal receiving circuit 38 in advance, and
When noise is added at the input of 0 and the bit error rate BER of the demodulated output becomes a predetermined value (for example, 1 × 10 ⁻⁴ ), C /
The N-XPD characteristic is shown, and the curve on the right side of the figure shows the case where the cross polarization interference compensation function (XPIC) is turned off.

The XPD monitor circuit 70 of this embodiment
Since A has the same configuration (same demodulation characteristics) as the demodulation unit 40 of the main signal receiving circuit 38, if no noise N is added, the demodulation effects (characteristics) occurring in both circuits may be considered to be substantially the same. Therefore, the operation of the XPD monitor circuit 70A will be described here.

Now, when the XPD monitor circuit 70A operates at a certain unknown XPD = large (different polarization interference = small),
When relatively large noise N is added, for example, BER = 1 × 10 ^{−4 at} point a in the figure. The XPD monitor circuit 70
When A is operating with another unknown XPD = small (different polarization interference = large), when relatively small noise N is added, for example, BER = 1 × 10 ^{−4 at} point b in FIG. Becomes Therefore, a plurality of different polarization interference signals of a plurality of XPD levels (that is, using the XPD value as a parameter) are input to the main signal receiving circuit 38 in advance, and the demodulated output is combined with the noise (C / N) added at that time. The C / N-XPD characteristic when the bit error rate BER of the above becomes a predetermined value (for example, 1 × 10 ⁻⁴ ) is measured.

During the operation of the main signal receiving circuit 38, when the XPD monitor circuit 70A (that is, the main signal receiving circuit 38) is operating at a certain unknown XPD value, a certain noise is generated. For example, if BER = 1 × 10 ⁻⁴ at point e in the figure when N is added, the above C / N−
From the XPD (XPIC-OFF) characteristic, the operation XP at that time
D value can be known. The C / N value at this time may be measured directly, or may be obtained from the amplitude of the received carrier CA and the magnitude of the added noise N. The above C /
The use of the noise N axis instead of the C / N axis of the N-XPD characteristic to provide the N-XPD characteristic is included in the present invention.

At this time, in the operating main signal receiving circuit 38, the cross-polarization interference compensation function (XPIC) is turned on.
The C / N-XPD curve (XPI in the figure)
C-ON) has been improved (shifted) to a position where BER = 1 × 10 ⁻⁴ when the operating XPD value becomes smaller (the amount of different polarization interference becomes larger).

Thus, according to the present invention (1), even when the main signal system receiving circuit 38 is in operation, there is no influence on the main signal system signal processing and there is no need to bypass the main circuit. , The operation XPD value can be measured.

The above-mentioned problem can be solved, for example, by the structure shown in FIG. That is, the wireless device of the present invention (2) is a wireless device that extracts and receives and demodulates mutually cross-polarized signals from cross-polarized waves of the same frequency. Noise adding means 71 for adding noise to the split signal and changing the C / N ratio;
Demodulation means 70A for demodulating the noise-added signal;
BER for calculating a bit error rate of the demodulated data
It comprises a calculating means 76 and an estimating means 90 for estimating the state of line degradation from the relationship between the C / N ratio and the bit error rate.

In the wireless device of the present invention (3), in a wireless device for extracting and receiving and demodulating mutually crossed polarized signals from cross polarized waves of the same frequency, a branching means for branching the signal before demodulation. Noise adding means for adding noise to the branched signal to change the C / N ratio, demodulating means for demodulating the signal to which the noise is added, and calculating a bit error rate of the demodulated data. BER calculation means for performing
Noise level control means for controlling a noise level added by the noise addition means so that the bit error rate calculated by the ER calculation means becomes a predetermined value; and C / N when the bit error rate becomes the predetermined value. Storage means for storing the relationship between the ratio and the line degradation state; and line degradation for outputting the line degradation state corresponding to the C / N ratio when the BER calculated by the BER calculation means reaches the predetermined value. And a situation estimating means.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the same reference numerals indicate the same or corresponding parts throughout the drawings.

FIG. 2 is a diagram showing a partial configuration of a multiplex radio apparatus according to the embodiment, which is suitably applied to, for example, the receiving station 200 side of the multiplex radio communication system of FIG.
In the figure, reference numeral 70 denotes X for monitoring the amount of interference of different polarizations.
PD monitor, 71 is a noise adding circuit that can add variable level noise, 72 is a mixer (MIX), 73 is an A / D converter (A / D), 74 is a signal processing unit, 75 is an FEC operation unit, and 76 Is a BER operation unit. Channel corresponding unit 38 ₁
May be the same as that described with reference to FIG.

However, the demodulation section 40 supplies the main signal of the CH1 (reception polarization VR) to the main signal receiving circuit and the XPD monitor 7.
A hybrid (HYB) 53 for two distributions to 0 and 0 is provided. Preferably, the mixer 72, the A / D converter 73, the signal processing unit 74,
Each configuration (particularly, circuit characteristics, etc.) of the FEC operation unit 75 is C
This is the same as the mixer 55, the A / D converter 57, the signal processing unit 61, and the FEC operation unit 62 in the main signal processing system of H1. Further, the C / N ratio of the main signal receiving circuit 40 is determined in advance.
The noise adding circuit 71, BE when measuring the XPD characteristic;
The R measurement unit 76 is common. If the characteristics are substantially the same, there is no requirement that the circuit configuration be the same.

Therefore, if no noise is added, CH
The same demodulation characteristic (BER) can be obtained by the main signal system 1 and the XPD monitor 70. When noise is added, XP
In the D monitor 70, noise is added to the current XPD value, the reception state deteriorates, and the BER value increases. In this state, when a bit error exists in one received frame, the FEC operation unit 75 outputs, for example, a pulse (error pulse) signal according to the number of bit errors.
The BER measuring unit 76 counts the pulse output from the FEC calculating unit 75 per unit time and calculates a bit error rate BER per unit time.

Although not shown, noise is added to the noise adding circuit 71 of the XPD monitor 70, and the BE at that time is added.
The output of the R measurement unit 76 is monitored, and noise is added until the bit error rate becomes constant. At this time, demodulation is performed based on the C / N-XPD characteristics of the demodulation unit 40 measured in advance. An XPD estimating unit 90 for estimating the operation XPD of the unit 40 is further provided.

With this configuration, the signal is branched by the hybrid 53 and input to the XPD monitor 70. In this state, the XPD estimating means 90 receives the signal of the operating XPD monitor 70 at a certain unknown XPD value. When the BER reaches a predetermined value (for example, 1 × 10 ^-4 ), C /
By measuring the N value and referring to the C / N-XPD characteristic measured in advance for the main signal system circuit,
The XPD (D / U) value corresponding to the / N value can be estimated.

FIG. 3 shows C / N-XPD according to the embodiment.
FIG. 3A illustrates the C / N-BER characteristic. In the figure, generally, bit error hardly occurs when C / N is large (noise N is small), but bit error occurs when C / N is small (noise N is large). can get. At this time,
C / N and B when BER is in the range of 1 × 10 ⁻³ to 1 × 10 ⁻⁵
The relationship with ER is clear (unique), and for example, 1 × 10 ⁻⁴ is adopted here.

FIG. 3B shows that the BER is a predetermined value (for example, 1 ×
^10-4 ) shows the C / N-XPD characteristic at the time when it becomes ^10-4 ).
In the figure, the XPD monitor circuit 70 (ie, main signal receiving circuit) has an unknown XPD = large (different polarization interference =
When operating at (small), when relatively large noise N is added, for example, BER = 1 × 10 ^{−4 at} point a in the figure.
When the XPD monitor circuit 70 is operating with another unknown XPD = small (different polarization interference = large), when a relatively small noise N is added, for example, BER = 1 at point b in FIG.
× 10 ^-4 .

Therefore, a plurality of XPD-level different polarization interference signals (that is, the XPD values are used as parameters) are input to the main signal receiving circuit 38 in advance, and the noise (C
/ N) when the bit error rate BER of the demodulated output becomes a predetermined value (for example, 1 × 10 ⁻⁴ ) by the combination with C / N).
-Measure XPD characteristics. During the operation of the main signal receiving circuit 38, the XPD monitor circuit 70
If the main signal receiving circuit 38 is operating with an unknown XPD value, and BER = 1 × 10 ⁻⁴ at a point e in the figure when a certain noise N is added, The operating XPD value at that time can be known from the C / N-XPD (XPIC-OFF) characteristic. At this time, since the cross-polarization interference compensation function (XPIC) is ON in the operating main signal receiving circuit 38, the C / C
The N-XPD curve (XPIC-ON in the figure) is the operating XPD
BE becomes smaller when the value becomes smaller (the amount of cross polarization interference becomes larger).
It is improved (shifted) to a position where R = 1 × 10 ⁻⁴ .

Although the preferred embodiment of the present invention has been described, it goes without saying that various changes in the configuration, control, and combinations thereof can be made without departing from the spirit of the present invention. . For example, the method of measuring the bit error rate and the like do not prevent replacement with other known means.

[0031]

As described above, according to the present invention, even when the main signal system receiving circuit is in operation, it does not affect the main signal system signal processing and does not need to bypass the main signal line. It is possible to measure the XPD value, which greatly contributes to the improvement of channel addition and maintenance in a multiplex wireless communication system with co-channel arrangement.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram showing a partial configuration of a multiplex radio apparatus according to an embodiment.

FIG. 3 is a diagram illustrating C / N-XPD characteristics in the embodiment.

FIG. 4 is (1) illustrating a conventional technique.

FIG. 5 is a diagram (2) illustrating a conventional technique.

[Explanation of symbols]

31 _{1 to} 31 _n channel corresponding section 32 Modulating section 33 transmitting section 34 multiplexing section 35, 36 antenna 37 polarization splitting section 38 _{1 to} 38 _n channel corresponding section 39 receiving section 40 demodulating section 51, 52 amplifier (AGC circuit) 54 Local oscillation circuit (LO) 55, 56, 72 Mixer (MIX) 61, 74 Signal processing unit 62, 75 FEC operation unit 63 Signal processing unit (XPIC) 70 XPD monitor 71 Noise adding circuit 76 BER operation unit 100 Transmission station 200 Reception Station

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (3)

[Claims] 1. A C / N-XPD (heteropolarization) when a bit error rate of a demodulated output thereof is input to a main signal receiving circuit in advance by inputting a plurality of XPD levels of different polarization interference signals and noise to a predetermined value. (Wave interference amount) characteristics are measured in advance, and when the main signal receiving circuit is operated, a received polarization split signal is branched and one of the signals is demodulated by the main signal receiving circuit and the other is demodulated by the XPD monitor circuit. At the same time, noise is added to the input of the XPD monitor circuit until the bit error rate of the demodulated output reaches the predetermined value, and the C / N value at that time and the C / N-X
A method for monitoring the amount of interference of different polarization interference, comprising estimating an XPD value of the main signal receiving circuit from PD characteristics. 2. A radio apparatus for extracting and receiving and demodulating polarization signals crossing each other from cross polarizations of the same frequency, wherein: a branching means for branching the signal before demodulation; Noise adding means for changing the C / N ratio, demodulating means for demodulating the signal to which the noise is added, and BER for calculating the bit error rate of the demodulated data.
A wireless device comprising: a calculating unit; and an estimating unit that estimates a channel degradation state from a relationship between the C / N ratio and the bit error rate. 3. A radio apparatus for extracting and receiving and demodulating polarization signals crossing each other from cross polarizations of the same frequency, wherein: a branching means for branching the signal before demodulation; Noise adding means for changing the C / N ratio, demodulating means for demodulating the signal to which the noise is added, and BER for calculating the bit error rate of the demodulated data.
Calculation means; noise level control means for controlling the noise level added by the noise addition means so that the bit error rate calculated by the BER calculation means becomes a predetermined value; and the bit error rate becomes the predetermined value. C / in case
Storage means for storing a relationship between the N ratio and the line degradation state; and a line for outputting a line deterioration state corresponding to the C / N ratio when the BER calculated by the BER calculation means reaches the predetermined value. A wireless device comprising: a deterioration state estimating unit.