JPH0449299B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention eliminates different polarization signals that interfere with a main polarization signal in a wireless communication system that performs communication using a plurality of polarization signals. This invention relates to a different polarization signal removal control method.

Prior Art and Problems In wireless communication systems, due to congestion in frequency allocation, systems using multiple polarized signals have been adopted. For example, a method in which the transmission frequency and the reception frequency have the same polarization frequency and a method in which different polarization frequencies are known are known, and the latter method is called an interleaving method. Furthermore, as shown in FIG. 1, a method is known in which transmission and reception use different polarizations and frequencies. That is, channels CH ₁ , CH ₂ , CH ₃ ,
..., CH ₁ ′, CH ₂ ′, CH ₃ ′, ... are arranged, transmit channel CH ₁ of vertical polarization V T,
Channel CH ₁ ′ of horizontal polarization H is designated as reception R, channel CH ₂ of vertical polarization V adjacent to that channel is designated as transmission T, channel CH ₂ ′ of horizontal polarization H is designated as reception R, and adjacent to that channel. Channel CH ₃ ' of vertical polarization V is received R, and channel CH ₃ of horizontal polarization H is received.
is the transmission T, and if the interval between those frequencies is narrow, then
Interference becomes a problem due to interference between transmitter and receiver, where the transmitted signal wraps around the received signal, and due to reception of signals with different polarization frequencies.

FIG. 2 shows the main parts of a transmitter/receiver that communicates using a plurality of polarized signals, including transmitting sections TH ₁ , TH ₂ , TH ₃ , ... that transmit using horizontally polarized waves H,
Transmitting units TV ₁ , TV ₂ , which transmit using vertically polarized waves V;
TV ₃ , . . . are receivers RH ₁ , RH ₂ , RH ₃ , .
...and receivers RV ₁ , RV ₂ , which receive the vertically polarized wave V,
RV ₃ , . . . are each coupled to the receiving antenna ANT2 via a circulator CIR.

For example, the transmission signal Tv of the vertically polarized wave V of channel CH ₁ in FIG.
There is interference caused by this transmission signal Tv transmitted from ANT1 leaking into the reception signal Rh of channel CH ₁ ' as shown by the dotted line Rv. This is called antenna side-to-side interference (SS interference). Also, the channel CH ₂ ' in Figure 1
When the reception frequencies of different polarizations are adjacent to each other, as in CH ₃ ', the receiving antenna ANT2 receives the reception signal Rh of the horizontal polarization H and the reception signal Rv of the vertical polarization V, which is a different polarization. ′ is received and this received signal
Rv′ interferes with the received signal Rh, resulting in so-called XPD interference.

The aforementioned SS interference and XPD interference can be reduced by narrowing the transmit spectrum or the filter band in the receiving section, but narrowing the filter bandwidth will result in a reduction in transmit power. Transmission characteristics such as amplitude characteristics and delay characteristics deteriorate. Therefore, it was not possible to narrow the band of the filter. Therefore, when the frequency interval is narrow, interference cannot be reduced. Also, transmitting antenna ANT1 and receiving antenna
It is possible to reduce SS interference by changing the arrangement with ANT2, or to reduce XPD interference by antennas between transmitting and receiving antennas during spatial propagation, but there are limits both physically and methodically. In particular, 64QAM (64
When using the quadrature amplitude modulation method, the spectrum spreads, so the SS interference will be
30dB, and XPD interference is about 20dB. in this way
If SS interference and XPD interference are large, it becomes difficult to set up an actual wireless line with narrow frequency intervals.

Purpose of the Invention The present invention aims to reduce SS interference and XPD interference when communicating using a plurality of polarized signals.

Composition of the Invention The present invention provides an adjusting means for adjusting the amplitude and phase of a different polarization signal that interferes with a main polarization signal in a wireless communication system that performs communication using a plurality of polarization signals; a synthesizing means for synthesizing the different polarization signal adjusted by the adjusting means and the main polarization signal; extracting the different polarization signal from the signal synthesized by the synthesizing means; The adjustment means is controlled so that the level is minimized,
It is possible to automatically reduce interference due to different polarizations. Examples will be described in detail below.

Embodiment of the Invention FIG. 3 is a block diagram of main parts of an embodiment of the present invention, in which 1 is a receiving antenna, 2 is a variable attenuator, 3 is a variable phase shifter, 4 is a combiner, 5 is a band filter, 6
is control interference. Also, 2', 3', within the dashed line
5' and 6' are a variable attenuator, a variable phase shifter, a bandpass filter, and a control circuit. The horizontally polarized H component received by the receiving antenna 1 is directly applied to the combiner 4, and the vertically polarized V component is applied to the combiner 4 via the variable attenuator 2 and variable transfer device 3. In this case, the received signal of horizontal polarization H is the main polarization signal,
The received signal of the vertically polarized wave V becomes a different polarized signal.

The band filter 5 has a band for extracting a different polarization signal, and the control circuit 6 controls the variable attenuator 2 and the variable phase shifter 3 so that the level of the signal extracted by the band filter 5 is minimized. It outputs a control signal to control the This control circuit 6
For example, as shown in FIG. 5, there is a detection section 61 that detects the signal extracted by the bandpass filter 5, a control section 62, and a variable attenuator 2 and a variable phase shifter controlled by the section 62. 3, and a phase shifter drive section 64. The phase shifter drive section 64 is controlled while the detection output signal level of the detector 61 is monitored by the control section 62. The amount of phase shift of the variable phase shifter 3 is controlled through the attenuator driver 63, and the amount of phase shift is set such that the detected output signal level is the lowest. The amount of attenuation in step 2 is controlled to the amount at which the detected output signal level is the lowest.

In Figure 4a, if the frequency interval between channels (1) and (2) is narrow as shown by Δf, each channel
The received signals of the same polarization in (1) and (2) overlap each other as shown by diagonal lines, and this overlapping portion causes interference. This overlap is
This can be eliminated to some extent by using a bandpass filter, but as mentioned above, there is a limit to narrowing the band of the filter because it causes deterioration of the transmission characteristics. Furthermore, if vertically polarized waves are received by a horizontally polarized antenna, the received power of the vertically polarized signal will be approximately 20 dB lower than the received power of the horizontally polarized signal. That is,
As shown in b, the vertically polarized signal component of the adjacent channel (2) is about 20 dB lower than the received signal power of the horizontally polarized channel (1). On the contrary, as shown in c, the vertically polarized wave V channel (2)
The horizontally polarized signal component of the adjacent channel (1) is about 20 dB lower than the received signal power of .

As mentioned above, with respect to the horizontally polarized signal of channel (1), the vertically polarized signal component of the adjacent channel (2) overlaps with the shaded part shown in b in Fig. 4. It will interfere. By removing this shaded portion, interference can be eliminated. Therefore, the level and phase of the vertically polarized signal of channel (2) are adjusted to cancel the vertically polarized signal component contained in the horizontally polarized signal of channel (1). For example, if the received level of the vertically polarized signal of channel (2) shown in c is attenuated by about 20 dB,
The reception level of the horizontally polarized signal of channel (1) is also approximately
It is attenuated by 20 dB, as shown by the solid line d.
The signal phase of channels (1) and (2) shown by the solid line in d is
By inverting the signal by 180 degrees and combining it with the received signals of channels (1) and (2) shown in b, the vertically polarized signal component can be canceled. In that case, as shown in d, since the component of the horizontal polarization signal of channel (1) shown by the solid line is also included, it will affect the horizontal polarization signal of channel (1), which is the main signal, shown by the dotted line. However, the extent of this is extremely small, and the effect of canceling out the interference caused by the vertically polarized signal component of the adjacent channel (2) is greater, and the effect on the main signal, which is the horizontally polarized signal, is ignored. As much as possible.

The level and phase of the polarized signal components of the adjacent channels as described above are adjusted by the variable attenuator 2 and variable phase shifter 3 shown in FIG. The attenuation amount of the variable attenuator 2 and the phase shift amount of the variable phase shifter 3 are automatically controlled so as to minimize the level of the vertically polarized signal component caused by fading. Even in the case where the reception level of the main polarization signal decreases, interference due to the different polarization signal can be reduced as described above.

If different polarized signals exist on both sides of the polarized signal as the main signal and cause interference, add the configuration shown by the dashed line and use the band filters 5 and 5' to filter out the interference frequency signals on both sides of the main signal. The components are extracted and the variable attenuators 2, 2' and the variable phase shifters 3, 3' are controlled so that the respective levels are minimized.

Although the above embodiment shows the case where the main signal is horizontal polarization, it can be similarly applied to the case where the main signal is vertical polarization. The amount of attenuation and the amount of phase shift are adjusted and combined with the vertically polarized signal of the main signal, thereby canceling out the horizontally polarized signal component included in the vertically polarized signal of the main signal.

Effects of the Invention As explained above, the present invention provides a variable attenuator 2 that adjusts the amplitude and phase of a different polarization signal such as a vertically polarized signal that interferes with a main polarized signal such as a horizontally polarized signal. and a variable phase shifter 3, and a synthesizing means such as a synthesizer 4 for synthesizing the different polarization signal adjusted by the adjusting means and the main polarization signal. extracting the different polarization signal from the signal using a band filter 5 or the like;
The adjustment means is controlled so that the level of the different polarization signal is minimized, and as a result, the interfering different polarization signal can be canceled out, so when the frequency interval between adjacent channels is narrow, Also, there is an advantage that interference caused by different polarization signals can be easily reduced. Therefore, SS interference and XPD interference can be reduced without deteriorating the transmission characteristics by keeping the filter band the same as before.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the arrangement of transmitting and receiving channels using horizontally polarized waves H and vertically polarized waves V, Fig. 2 is a block diagram of the main parts of a transmitting and receiving device using multiple polarized signals, and Fig. 3
The figure is a block diagram of the main part of the embodiment of the present invention, Fig. 4a
-d are explanatory diagrams of interference and interference removal, and FIG. 5 is a block diagram of the main part of the control circuit. ANT1 is a transmitting antenna, ANT2 is a receiving antenna, TH ₁ , TH ₂ , TH ₃ , ..., TV ₁ , TV ₂ ,
TV ₃ , ... is the transmitter, RH ₁ , RH ₂ , RH ₃ , ...,
RV ₁ , RV ₂ , RV ₃ , ... are receiving parts, CIR is a circulator, 1 is a receiving antenna, 2 is a variable attenuator,
3 is a variable phase shifter, 4 is a synthesizer, 5 is a bandpass filter, and 6 is a control circuit.

Claims (1)

[Claims] 1. In a wireless communication system that performs communication using a plurality of polarized signals each having a different center frequency, the main polarized signal has a center frequency different from that of the main polarized signal, and the main polarized signal adjusting means for adjusting the amplitude and phase of a different polarization signal that interferes with the main polarization signal; a combining means for combining the different polarization signal adjusted by the adjusting means with the main polarization signal; comprising: a bandpass filter that extracts the different polarization signal from the combined signal; and a control means that controls the adjustment means based on the different polarization signal extracted by the bandpass filter; A different polarization signal removal control method, characterized in that the adjustment means is controlled so that the level of the different polarization signal extracted by the bandpass filter is minimized.