KR20060013248A - The repeater to cancel for interference of multipath with ttl switching technology - Google Patents

Abstract

The present invention relates to a circuit for removing a signal fed back to a transmitted signal in a repeater relaying the same frequency.

The present invention relates to a base station counter antenna (100), a first duplexer (101), a first forward high power amplifier (102), and a second duplexer (103) in the same frequency repeater for relaying signals between a base station and a mobile station in a wireless communication network. In the problem that the transmission signal radiated through the forward relay (reverse repeater is processed in the same operation) to the mobile station counter antenna 104 is introduced (feedback) to the base station counter antenna, causing oscillation of the repeater. The present invention relates to a technique for removing a signal. In general, the feedback signal is introduced into the antenna opposite the base station through the multipath, and has a large amount of delay information, so that the existing technology (FIG. 2) could not be removed. This problem is constructed by using TTL switching technology, 90-degree phase modulator (I / Q modulator), 90-degree phase detector (I / Q demodulator) to remove all feedback signals through multipath. It is a technology that can proactively cope with changes in the radio wave environment due to the installation of the base station counter antenna or the mobile station counter antenna and changes in the radio wave environment caused by the surrounding environment.

Repeater, Base Station, Mobile Station, Antenna, Isolation, Oscillation, Interference Cancellation, TTL (Transistor-Transistor Logic Circuit)

Description

The repeater to cancel for interference of multipath with TTL Switching Technology}

1 is a schematic configuration diagram of a wireless communication wireless relay device according to the related art.

2 is a block diagram of a wireless communication relay device to which the present invention is applied;

3 is a block diagram of a multiple delayer,

4 shows a TTL switching delay structure;

5 shows the structure of a variable active bandpass filter,

6 shows the principle of the internal filter of the variable active bandpass filter,

7 illustrates the principle of an active band cancellation filter,

8 illustrates filtering a spread communication signal (QPSK, etc.) in an active band cancellation filter,

9 shows a conventional interference elimination relay.

Brief description of symbols for the main parts of the drawings

100, 104, 201, 209, 901 and 909 in each drawing

101, 103, 203, 207, 904, and 906 in each drawing are duplexers

211 and 910 in each drawing are 90 degree phase detector

220, 508, and 915 in each drawing show the 90 degree phase modulator

202, 205, 208, 216, 902, 903, 907 and 908 in each drawing are directional couplers

213, 218, 511, 911, 914 in each drawing are delay circuits

The 90 degree phase modulator in each figure is an I / Q modulator using the 90 degree phase difference of the hybrid coupler.

The 90-degree phase detector in each figure shows the I / Q demodulator using the 90-degree phase difference of the hybrid coupler.

The present invention relates to a method and a circuit for removing interference signals of a repeater for a wireless transmission by applying a TTL switching method, that is, a TTL switching circuit and a 90 degree phase modulator for a device using the same frequency in all communication devices using a radio. Stable interference cancellation circuit (Cancellation) is provided by improving the reliability of phase detection by using a variable active bandpass filter that blocks the inflow of this signal when a phase is detected using a 90 degree phase detector and the like. The present invention relates to a relay apparatus and a method for actively adapting to a propagation environment by removing the interference signal by multipath using TTL switching.

Numerous relay devices are installed and operated in shaded areas with weak or poor radio wave strength due to obstacles such as underground buildings, high-rise buildings, and hills, which are difficult to reach radio base stations. These relays are used with their own problems. Optical repeater is excellent in call quality but high in line maintenance cost, and variable repeater is stable because there is no oscillin phenomenon caused by antenna isolation, which is a problem of general repeater. Another problem that needs to be allocated separately is a problem that wastes frequency resources.

9 shows a part of a configuration diagram of a general bidirectional indirect elimination wireless repeater. As shown, the signal received by the base station counter antenna 901 is passed through the interference signal canceller 902, the error signal extractor 903, the first duplexer 904, the amplifier 905, the second duplexer 906, The signal is transmitted to the mobile station through the reference signal combiner 907 and the reference signal detector 908 through the mobile station counter antenna 909. (The reverse amplification path is also the same as the forward amplification path.)

At this time, the reference signal generated by the reference signal generator 912 is combined with the original signal through the reference signal combiner 907 and radiated. Some of the signals radiated to the mobile station through the mobile station counter antenna 909 are fed back to the base station counter antenna 901. The interference signal introduced again passes through the interference signal canceller 902 and the signal extracted from the reference signal detector 908 passes through the delay circuit with the proper phase and amplification degree through the 90 degree phase modulator 915 of the internal path. It is synthesized with the signal with the delay time and the fed back interference signal. The synthesized feedback part of the interference signal is canceled and the remaining signal is introduced into the 90 degree phase detector 910 through the error signal extractor 903. At this time, the 90-degree phase detector 910 reads phase information using a signal having a predetermined delay time as the signal generated by the reference signal generator 912 passes the delay circuit 911 as a reference signal. Using this information, the 90 degree phase modulator 915 is controlled to adjust the signal directed to the interference signal canceller 902 so as to remove the feedback interference signal introduced through the base station counter antenna 901.

In this case, the first problem is that the signal flowing into the 90-degree phase detector 910 has the original signal and the fed-back interference signal at the same time. The degree phase detector 910 is saturated and thus it is impossible to detect accurate phase information, which makes it impossible to accurately control the 90 degree phase modulator 915. In order to solve this problem was devised as shown in FIG.

The second problem is that the 90 degree phase detector 910 detects phase information on a reference signal input from the reference signal generator 912 and an interference signal fed back, that is, a signal having a delay time between the two signals. However, when multiple feedback paths occur, the phase of the fed back interference signal of one or more other paths may not be detected by the 90 degree phase detector 910, and the phase of one signal may be similarly applied to the 90 degree phase modulator 915. You have no choice but to control it. In this case, interference cancellation for certain specific feedback signals is performed, but not for feedback signals of multiple paths. Due to this problem, the relay devices having the conventional interference cancellation (cancellation) function cause a malfunction when installed in the field.

The third problem is that there is no big problem in the case of implementing only one-way in the configuration of Fig. 9, but in the relay device for bidirectional communication, the band pass filter should be used for the phase detection path due to the problem of separation between transmission and reception. In bidirectional communication, forward reception uses the same line as the reverse transmission. If the interference signal remover 902 and the error signal extractor 903 are in the forward direction, they correspond to the reverse output, so that the reverse output flows through the error signal extractor 903 to the 90 degree phase detector 910 to perform normal operation. I can't. In this case, a band pass filter is inserted between the error signal extractor 903 and the 90 degree phase detector 910 and between the reference signal generator 912 and the 90 degree phase detector 910 to exactly match the delay time with the reference signal path. A bandpass filter must also be inserted.

A fourth problem is that in order to operate Fig. 9, a signal other than a signal to be serviced, that is, a reference signal generated from the reference signal generator 912, must be radiated to the outside through the mobile station counter antenna 909.

The present invention is an apparatus for complementing and improving the above problems.

Interference through indirect path including time delay, amplitude control and phase shift operation by applying TTL switching method to call quality deterioration or oscillation by multipath multipath generated by feedback in wireless repeater using the same frequency A device for removing interference signals by adjusting them to have the same amplitude and opposite phase as a signal, and is an interference cancellation device that enables high quality signal quality.

In order to achieve the object as described above, the present invention provides a wireless relay apparatus for relaying and transmitting the same frequency in a wireless communication network. The signal received through the interference signal canceller 202, the first duplexer 203, the low noise amplifier 204, the error signal extractor 205, the high power amplifier 206, the second duplexer 207, the reference signal detector 208 ), Mobile station counter antenna 209, variable active bandpass filter 210, 90 degree phase detector 211, reference signal multiple delayer 212, reference signal basic delay circuit 213, first duplexer delay correction filter 214, a reference signal generator 215, a TTL switching delay 217, an interference cancellation signal basic delay circuit 218, a phase control line 219, a multipath interference canceller including a 90 degree phase modulator 220 It is characterized by providing a relay device.

Hereinafter, an embodiment of a multipath multi-tracking interference cancellation relay apparatus and method applying a TTL switching scheme according to the present invention will be described with reference to the accompanying drawings.

When the power is initially applied, the signal input through the base station counter antenna 201 is input to the first duplexer 203 through the interference signal canceller 202. At this time, there is no interference signal among the signals input to the interference signal canceller 202. The signal input to the first duplexer 203 is input to the error signal extractor 205 via the low noise amplifier 204 after the filter. The dual source signal is input to the high output amplifier 206 and the sampled signal is input to the 90 degree phase detector 212 via the variable active band cancellation filter 211. The signal input to the high output amplifier 206 is input to the reference signal detector 208 via the second duplexer 207. One of the signals input to the reference signal detector 208 is radiated to the service area through the mobile station counter antenna 209, and the other is input to the reference signal coupler 216.

The signal input to the reference signal coupler 216 is branched to the variable active bandpass filter 215 and the 90 degree phase controller 220. The signal branched to the variable active bandpass filter 215 passes through the bandpass filter according to the configuration of FIG. 5.

The variable active bandpass filter 215 is input to the first divider 501 and branches into pass 1 and pass 2.

The signal branched to pass 1 is changed to a specific frequency by the first mixer 502 and passes through a filter having the characteristics as shown in 601 of FIG. 6. This signal is restored through the second mixer 504 back to the original frequency. The restored signal is changed back to a specific frequency through the third mixer 505, and the signal is passed through a filter having the characteristics as shown in 602 of FIG. 6 to be restored to the original frequency by the fourth mixer 507. FIG. The final reconstructed signal at this time has the same filter characteristics as 603 of FIG. 6. Through this operation, the desired bandwidth can be canceled.

The signal input to pass 2 passes through a delay circuit 511 to match the delay times of pass 1 and pass 2, and passes through the amplifier 512 to match the output of pass 1 to the combiner of pass 1 and pass 2. The signal is synthesized. In this case, the synthesized signal has the characteristics of the band erasing filter by removing the signal of pass 1 by maintaining the amplitude equal to the 180 degree phase difference through the 90 degree phase modulator 403 according to the characteristic shown in FIG.

Conditions for cancellation should be the same amplitude and 180 degrees out of phase. In Fig. 6, the condition where the delay signal 701 due to the characteristic 603 of the delay filter coincides with the delay time 702 caused by the delay circuit 511 is the highest in the center. (If the delay time is the same, the phases are considered to be coincident). At this time, the phase of the center is to have a phase of 180 degrees through the 90 degree phase modulator 508. The operation at this time cannot be set to have a phase of 180 degrees because it is disturbed by the delay filter characteristic 603 at the highest point where the delay time occurs most even when the 90 degree phase modulator 508 is operated. Through this operation, the most attenuation characteristic occurs at the center where the phases are most coincident (180 degrees), and the attenuation characteristic does not occur at the highest point where the delay time varies the most. By using these characteristics, the characteristics of the BSF may be implemented as shown in 703 of FIG. 7. As shown in FIG. 8, the spread signal, for example, the CDMA signal, has a shape similar to that of a general carrier signal, that is, a non-spread signal, because the characteristic of 801 is attenuated at the center as in the characteristic of 802.

The signal passing through the variable active band cancellation filter 215 is input to the first duplexer correction filter 214 and passes through the basic delay circuit 213 and has a plurality of delay signals in the multiple delay circuit 212. Input to 211 is used as a reference signal. The multiple delay circuit is configured as shown in FIG. 3 and may have a plurality of delay signals such as delay signals 301, 302, and 303.

 The other of the signals branched from the reference signal coupler 216 is input to the 90 degree phase modulator 220. The 90 degree phase modulator 220 adjusts the phase and amplitude of the interference canceling (cancell) signal inputted through the phase control line 219 to the phase information detected by the 90 degree phase detector 211. After passing through the TTL switching delay circuit 217 through the TTL switching delay circuit 217 is input to the interference signal canceller 202 is radiated through the mobile station counter antenna 209 fed back to the base station counter antenna 201 and synthesized with the input interference signal interference signal Remove it. At this time, the TTL switching delay circuit tracks the fed back interference signal and passes only a signal whose delay time is similar to the fed back interference signal.

In this case, the TTL switching delay circuit may be illustrated in FIG. 4. In FIG. 4, the first input signal passes through the first mixer 402 and is converted into a specific frequency. If the circuit that can have a delay time like D1, D2 ... is for high frequency, there is no need to use a mixer. The signal converted to a specific frequency passes through the delay circuits D1, D2, D3, D4, and D5. At this time, the delay time can be selected using a control line such as 401. Delay time can be controlled by TTL method, so if only 1Bit is operated, only delay circuit D1 will pass and the rest of D2, D3, D4, D5 will be switched to pass below it. Through this TTL operation, up to 32ns can be realized by combining 1ns, 2ns, 4ns, 8ns, and 16ns. If more delays of 10ns, 20ns, 40ns, 80ns, and 160ns are configured, up to 320ns in 10ns units can be implemented. Can be operated.

The 90-degree phase detector 211 detects phase information on an interference signal whose phase information coincides with a delay time of a reference signal (a signal generated in the shape of 803 in FIG. 8). At this time, even if a large number of reference signals are out of phase, only interference information having the same phase information, that is, phase information matching the interference signal input from the variable active band cancellation filter 210 is detected. Using this feature, the reference signal multi-delay circuit 212 is determined in advance using a calculated value considering the external environment of the installation site, and the TTL switching delay circuit 217 for canceling interference is removed using the measured phase information. The control operation is performed such that a value coinciding with the reference signal passed through the reference signal multiple delay circuit 212 is removed by the interference signal canceller 202. This operation tracks the feedback interference signal introduced into the base station counter antenna 201 through the multipath.

The signal input through the base station counter antenna 201 is input by combining the original signal to be serviced with the unwanted interference signal fed back. The difference between the two signals is that the delayed time information of the fed back interference signal and the original signal is different from each other. The input interference signal and the original signal detect only the feedback signal at the 90 degree phase detector 211. In this case, the reference signal inputted to the 90 degree phase detector 211 passes through the variable active band cancellation filter 215. It has the same shape as 803 of the first variable active band cancellation filter 210 to make the same shape and input to the 90-degree phase detector. In this case, since the output signal is used as the reference signal by using the band erasure filtering without using a separate reference signal, when the first variable type active band erasing filter 210 is not used, the noise is increased and phase information cannot be read accurately. . The operating characteristics of the first variable active band elimination filter 210 are the same as those of the second variable active band elimination filter 215, and after filtering the output signal using the second variable active band elimination filter 215. In a system that does not use as a reference signal, that is, a system using a separate reference signal, the variable active bandpass filter can detect more accurate information in the 90 degree phase detector 211.

FIG. 10 illustrates a method of measuring the amount of interference cancellation using a general mixer to determine whether the above-described operations operate properly and how much and how much to control.

The signal extracted by the error signal extractor 205 of FIG. 2 and the signal extracted by the reference signal detector 208 are searched by the TTL switching delay unit 1002 to match the delay time of the fed back interference signal. The detector 1001 checks how many feedback interference signals exist and how much power is input to determine the degree of separation between the base station counter antenna and the mobile station counter antenna, and the TTL switching delay unit 217 of FIG. 2. Commands were also given to increase the amount of interference cancellation.

Through the complex operation of the analog interference cancellation technique and the digital interference suppression technique, a function to remove all signals with delay information through multipath has been implemented.

The present invention is a technique for removing a multipath signal by applying a TTL switching scheme to more effectively remove an interference signal having a myriad of time information in an outdoor environment, thereby effectively eliminating an interference device in a flexible propagation environment. It can be configured, and it does not need a separate reference signal, so there is no need of a separate device for generating radio signals or reference signals, and it can reduce manufacturing costs.The 90-degree phase detector operates through a variable active bandpass filter You can extend the range.

Claims (5)

Multipath Interference Rejection Technology of the Same Frequency Wireless Repeater Step of configuring the interference canceller of the relay device: Using the output signal in the configuration of the relay device as a reference signal: Applying to the interference canceller controlling the delay time through the TTL switching scheme for the implementation: Implementing a variable active bandpass filter of the repeater: Detecting an interference signal in the configuration of the relay device: The method according to claim 1, wherein the phase information is detected using a 90 degree phase detector in the same manner as using two reference signals after filtering with a variable active bandpass filter using an output signal of a repeater without a reference signal. Configuration The method and configuration of claim 1, wherein the delay time is varied according to a TTL signal in the configuration of the TTL switching delay circuit. The method and configuration of claim 1, wherein in the configuration of the variable active bandpass filter, a delay characteristic synthesized by connecting two filters in series is used and the band cancellation width is varied. 10. The method and configuration of claim 1, wherein the number of interference signals, power, and delay time are detected by using a part of the output signal as a reference signal of a 90 degree phase detector in the configuration as shown in FIG.

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