KR20100104677A - Apparatus and method for removing a passive intermodulation distortion of telecommunication system - Google Patents

Abstract

PURPOSE: A device for removing interference of a mobile communication system using PIMD component and a method thereof are provided to apply reverse phage of PIMD(Passive Intermodulation Distortion) occurred by sharing a feeder to a receiving signal, thereby removing PIMD. CONSTITUTION: An interference extraction method uses transmitting signal component extracted from a mobile telecom system to extract interference remove signal corresponding to the frequency component of interference signal. A level detector detects signal level corresponding to the level computer of the interference signal from a receiving signal which will remove the interference signal. A level controller controls level component of the interference remove signal according to a signal level. An interference signal removing means combines the receiving signal and the phase interference remove signal, and removes the interference signal.

Description

Apparatus and method for eliminating interference in mobile communication system {APPARATUS AND METHOD FOR REMOVING A PASSIVE INTERMODULATION DISTORTION OF TELECOMMUNICATION SYSTEM}

The present invention relates to an interference canceling device and a method of a mobile communication system, and more particularly, after a PIMD component generated by mathematically analyzing a PIMD component generated by sharing a feedline in a mobile communication system and detecting a PIMD level, The present invention relates to an interference canceling device and a method for removing a PIMD by applying an inverse phase of a PIMD component to a received signal of a mobile communication system to remove the PMD.

In general, a mobile communication service provider establishes a mobile communication network capable of providing high quality wireless quality anywhere in service coverage. However, even if a plurality of terrestrial optical repeaters or base stations are installed by a mobile communication service provider, some mobile communication networks generate shaded areas where radio waves do not reach. In particular, since the terrestrial optical repeater or the antenna of the base station tends to be installed toward the road, there is a high possibility that the interior of a high-rise building becomes a shadow area of radio waves. This is because the building is high and it is difficult to easily transmit radio waves through the outer wall of the building.

To solve this problem, mobile operators generally install an in-building relay system to solve the shadow area of radio waves in the building. For example, the WCDMA operator builds a WCDMA in-building relay system as shown in FIG. 1A. That is, the WCDMA operator installs an in-building repeater in a building that does not transmit WCDMA radio waves, and then additionally installs a distributor, a feeder, and an omni antenna (or patch antenna) in the in-building repeater to solve the shadow area of the radio wave in the building. . Similarly, a mobile Internet (WIBRO) operator builds a mobile internet (WIBRO) in-building relay system as shown in FIG. 1B. Here, FIG. 1A is a configuration diagram of an embodiment of a WCDMA in-building relay system, and FIG. 1B is a configuration diagram of an embodiment of a WBDMA in-building relay system.

However, a mobile communication service provider generally provides a plurality of mobile communication services (for example, cellular, PCS, WCDMA, WIBRO, TRS, etc.) instead of providing a single mobile communication service. A shaded area occurs for. In order to eliminate such shaded areas, feeders and antennas need to be installed for each service, which requires more installation cost than the installation cost of the in-building repeater required for the mobile communication service in the building.

Accordingly, mobile communication providers that provide at least two mobile communication services have made various efforts to reduce feeder installations and to secure service coverage in shaded buildings. Among them, as a representative method, there is a method of sharing a feed line using a feed line sharer as shown in FIG. 2A. Since the frequency bands of the two mobile communication services are different (ie 2.1 GHz for WCDMA and 1.8 GHz for PCS), the feed line routers that combine the filter characteristics of the corresponding frequency bands can be cut in half for feeder installations. Can be. In this case, however, there should be no IM (Intermodulation) interference. 2A is a diagram illustrating an embodiment of a feeder line sharing method between WCDMA and PCS.

In particular, when the feeder line is shared between the wireless Internet (WIBRO) and WCDMA, serious interference occurs in the WCDMA uplink frequency band. At this time, the harmonic component obtained by subtracting the WiBRO component from the second harmonic component of WCDMA coincides with the WCDMA uplink frequency band (that is, 2.1 kHz x 2.3-2.3 kHz = 1.9 GHz). Here, the main cause of the interference generated in the same frequency band as the WCDMA uplink frequency band is known as Passive Intermodulation Distortion (PIMD). The PIMD generated in the signal band is a component that cannot be removed by a filter.It is a thin oxide layer between conductors, microdischarge due to empty spaces and microcracks between metals, dust and metal particles on metal surfaces. Associated nonlinearities, etc. The PIMD is mainly generated by the structure and characteristics of the RF device, but may be generated by adsorption of impurities on the cable connector contact surface due to environmental factors such as vibration and dust in the building, mechanical rupture, and nonuniformity. Here, FIG. 2B is a diagram illustrating an embodiment of a feeder line sharing method between the WiBRO and the WCDMA.

Therefore, in the existing in-building relay system, there is an urgent need for a technology capable of eliminating interference (eg, PIMD) generated by applying a feeder line sharing scheme for at least two mobile communication networks.

Therefore, the prior art as described above has a problem in that interference (for example, PMID) is generated by applying a feeder line sharing method for at least two mobile communication networks, and it is an object of the present invention to solve this problem.

Therefore, the present invention mathematically analyzes the PIMD component caused by the sharing of feeder lines in the mobile communication system, artificially generates the PIMD level, and applies the inverse phase of the PIMD component to the received signal of the mobile communication system to remove the PIMD component. It is an object of the present invention to provide an interference cancellation apparatus and a method of a mobile communication system for removing the PIMD.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object, in the interference cancellation apparatus, the interference extraction means for extracting the interference cancellation signal corresponding to the frequency component of the interference signal using the transmission signal components extracted for each mobile communication system ; Level detecting means for detecting a signal level corresponding to a level component of the interference signal in the received signal of the mobile communication system to remove the interference signal; Level control means for controlling a level component of the extracted interference cancellation signal according to the detected signal level; Phase delay means for phase inverting the interference canceling signal from the level control means; And interference signal removing means for removing the interference signal by combining the received signal with the phase-inverted interference canceling signal.

On the other hand, the method of the present invention for achieving the above object, in the interference cancellation method, the extraction step of extracting the interference cancellation signal corresponding to the frequency component of the interference signal using the transmission signal components extracted for each mobile communication system ; Detecting a signal level corresponding to a level component of the interference signal in the received signal of the mobile communication system to remove the interference signal; A control step of controlling a level component of the extracted interference cancellation signal according to the detected signal level; And removing the interference signal by inverting the controlled interference cancellation signal and combining the received signal with the received signal.

As described above, the present invention has an effect of eliminating interference (for example, PIMD) generated by applying a feeder line sharing scheme for at least two mobile communication networks.

In addition, the present invention can eliminate the interference caused by the sharing of the feeder line for at least two mobile communication network, applying the feeder line sharing method to the commercial network to reduce the feeder installation cost for each mobile communication network and ultimately the network This can reduce the cost of construction.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Before describing FIG. 3, the present invention will be described for the case of removing the PIMD generated when the feed line of the WCDMA in-building relay system and the WiBRO in-building relay system are shared. However, the present invention is not limited to the case of removing PIMD generated when sharing feed lines of WCDMA and WBRO, and those skilled in the art will appreciate that the present invention shares feed lines for at least two mobile communication networks. It will be readily appreciated that it may be applied to any interference that is generated.

3 is a diagram illustrating an embodiment of an interference canceling device of a mobile communication system according to the present invention, FIG. 4A is a diagram illustrating an embodiment of characteristics of a nonlinear device, and FIG. 4B is a WCDMA and WBRO feedline sharing. 4C is a graph of the waveform of the PIMD frequency generated due to WCDMA and WBRO feedline sharing.

The interference elimination device (hereinafter referred to as “interference elimination device”) due to the sharing of feeder lines of heterogeneous mobile communication networks according to the present invention of FIG. 3 is due to the sharing of feeder lines of the WCDMA in-building relay system and the WiBRO in-building relay system. After the generated PIMD component is mathematically analyzed and artificially generated and the PIMD level is detected, the PIMD is removed by applying an inverse phase of the PIMD component to the WCDMA received signal. Here, the components of FIG. 3 will be described in detail after mathematically analyzing the PIMD component to be removed with reference to FIGS. 4A and 4B.

In the present invention, in order to mathematically analyze the PIMD component, the characteristics of the nonlinear element are defined as shown in FIG. 4A, and thus the characteristics of the nonlinear element are modeled as in Equation 1 below.

, WCDMA의 수신신호를

, 휴대인터넷(WIBRO)의 송신신호를

로 가정하면, 비선형소자의 입력성분은

가 된다. 비선형소자의 입력성분을 나타내는 신호가 비선형소자를 통과하면, 하기의 [수학식 2]와 같이 나타난다.At this time, the IM component is generated when two input signals of the nonlinear element are assumed. Herein, in order to realistically recognize the IM component, a WCDMA transmission signal is used.

WCDMA receive signal

, The transmission signal of the mobile Internet (WIBRO)

Assume that the input component of the nonlinear element is

Becomes When a signal representing an input component of the nonlinear element passes through the nonlinear element, it is represented by Equation 2 below.

Specifically, solving the square term in [Equation 2] is the same as [Equation 3] below.

Specifically, when the third square term is solved in Equation 3, Equation 4 is as follows.

Since most of the intermodulation signals in Equation 2 to Equation 4 are out-of-band signals, there is no influence on the quality of the received signal. However, the seventh term in Equation 4 is exactly the received signal of WCDMA. Becomes the frequency band of. This corresponds to the PIMD component. Here, the seventh term of [Equation 4] is the same as the following [Equation 5].

Specifically, the third-order PIMD frequencies by WCDMA and WIBRO, WCDMA and WIBRO are as shown in Table 1 below, in particular, by the third order by WCDMA and WIBRO. The PIMD frequency is shown in Figure 4c.

division frequency 2f ₁ ―f ₃ (3rd order PIMD frequency) WCDMA transmission signal f ₁ 2130-2170MHz 2160 * 2-2345 = 1975MHz
WCDMA 3rd FA: 2160 MHz
WIBRO 2nd FA: 2345MHz WCDMA Received Signal (f ₂ ) 1940-1980 MHz WIBRO transmission / reception signal (f ₃ ) 2300-2370MHz

In [Table 1], the PIMD component generated in the frequency band of the WCDMA reception signal is in a state obtained by subtracting the bandwidth of the WBRO transmission signal from the bandwidth twice the frequency band of the WCDMA transmission signal. Therefore, as shown in FIG. 4C, PIMD is generated in a wider range than the bandwidth of WCDMA.

Meanwhile, as shown in FIG. 3, the interference canceling apparatus of the present invention includes an interference generator 310, a level detector 320, a level controller 330, and a phase delay unit. delay, 340, and mixer 350 for signal cancellation.

First, the interference extraction unit 310 is a 'WCDMA transmission signal component extracted from the monitoring terminal 301 of the WCDMA equipment' and 'WIBRO transmission signal extracted from the monitoring terminal 302 of the mobile Internet (WIBRO) equipment After mixing the components' using the mixer 311, the amplifier 312 is operated in a nonlinear region to force (artificially) IM components, and the filter 313 is used to extract only the third-order PIMD components. Since the third PIMD component is caused by a distortion component regardless of a passive component or an active component, the interference extractor 310 monitors each of the WCDMA equipment and the WiBRO equipment. 302, only the third-order PIMD component is extracted from the WCDMA transmission signal component and the WBRO transmission signal component. In this case, the third-order PIMD component extracted by the interference extractor 310 may be the same or similar only to the PIMD component generated from the feed line and the frequency component. Therefore, in order to remove the PIMD component from the WCDMA receiver, it is necessary to detect the exact level of the PIMD component and apply it to the third-order PIMD component extracted by the interference extractor 310 (see the level detector 320 to be described later). .

Next, the level detector 320 detects the correct level to be applied to the third order PIMD component extracted by the interference extractor 310 as described above. To this end, the level detector 320 extracts a part of the signal from the feeder liner 303 using the distributor 321. Here, the signal extracted from the feeder liner 303 includes not only pure WCDMA upstream components (i.e., WCDMA received signal components) but also PIMD components by aerial systems in the building (i.e., feeders, distributors, antennas, etc.). That is, the signal extracted from the feed line router 303 may be represented by Equation 6 below. The WCDMA received signal from the feeder liner 303 is applied to the signal cancellation mixer 350 via a WCDMA duplexer 304 and a low noise amplifier LNA 305 which will be described later.

는 WCDMA 상향 성분이고,

는 빌딩 내 공중선계에 의한 PIMD 성분이다. 이때, 레벨 검출부(320)는 필터(322)를 이용하여 WCDMA 상향 성분의 주파수 대역 이외의 신호(즉, PIMD 성분)를 분리하고, 증폭기(323)를 이용해 WCDMA 상향 성분의 주파수 대역 이외의 신호로부터 직류(DC) 성분(즉,

)의 레벨을 검출한다.In Equation 6,

Is the WCDMA upstream component,

Is the PIMD component by the aerial system in the building. At this time, the level detector 320 separates a signal other than the frequency band of the WCDMA upstream component (ie, the PIMD component) using the filter 322, and uses an amplifier 323 from a signal other than the frequency band of the WCDMA upstream component. DC component (i.e.

) Level is detected.

Next, the level control unit 330 is a kind of attenuator, so that the level control unit 330 can maintain an appropriate level of the third-order PIMD component extracted from the interference extraction unit 310 according to the predetermined level detected by the level detection unit 320. In other words, the level control unit 330 also displays the level of the third-order PIMD component (that is, the third-order PIMD component extracted from the interference extraction unit 310) in which only the frequency component of the PIMD component is the same or similar in the WCDMA received signal. By controlling the same or similar to the level component of the PIMD component at, the level component as well as the PIMD component and frequency component of the WCDMA received signal produce the same or similar third-order PIMD component.

Next, the phase delay unit 340 inverts the phase by delaying a third order PIMD component having the same or similar PIMD component, frequency component, and level component of the WCDMA reception signal described above by 180 °, and thereby canceling the signal for the mixer 350. Is applied. That is, the phase delay unit 340 applies the reverse phase of the third order PIMD component to the signal cancellation mixer 350. At this time, the signal cancellation mixer 350 converts the phase-inverted third-order PIMD component from the feeder liner 303 described above at the rear end of the low noise amplifier 305 (the PIMD by the pure WCDMA upstream component and the aerial system in the building). Component) to cancel (remove) the PIMD component by the aerial system.

The interference cancellation method of the mobile communication system according to the present invention will be briefly described, not shown in the drawings, in place of the description of the interference cancellation apparatus of FIG. The interference canceling apparatus of the present invention first extracts a signal for canceling interference from a frequency component of the interference signal by using a transmission signal component extracted for each mobile communication system. Then, the interference elimination apparatus detects a signal level corresponding to the level component of the interference signal from the received signal for the transmission signal of the mobile communication system to remove the interference signal, and controls the level component of the interference cancellation signal according to the signal level do. Then, the interference elimination apparatus phase-reverses the interference elimination signal and combines with the received signal to remove the interference signal.

Meanwhile, the aerial system (feeder, distributor, antenna) in the building may be configured in various forms. The PIMD component by the building's aerial system due to feeder line sharing is mainly generated in the Wilkinson distributors used in connector contacts and generally in distributors 306-309. Here, the Wilkinson distributor has a poor PIMD suppression function due to the internal resistance component. That is, in FIG. 3, PIMD components of various phases are generated in the distributors 306 to 309 disposed at various distances from the signal source. This feature allows the interference cancellation device of the present invention to remove only the main component of the PIMD.

In the present invention, the "U-junction" or "T-junction" dispenser having excellent PIMD suppression function is used instead of the Wilkins dispenser.

At this time, in the present invention, the "U-junction" or "T-junction" distributor may be replaced with respect to the distributors 306 to 309, but only the distributor 306 used for the feeder first stage is "U-junction" or "T-. Replacing a "junction" splitter can have the same or similar effect as replacing all splitters. This is because the maximum PIMD component is generated in the distributor 306 used at the feeder first stage.

Therefore, in the present invention, when the distributor 306 used at the feeder stage is replaced by the "U-junction" or "T-junction" distributor in the Wilkins distributor, the main component of the PIMD level is generated in the second distributor. This is simplified and the feeder losses to the first distributor and distributor losses are reduced, effectively eliminating the PIMD component.

On the other hand, the interference cancellation apparatus of the present invention can not only remove the PIMD generated in the heterogeneous mobile communication network, but also remove the IM component generated by using a plurality of FAs in the same service.

5A is an exemplary diagram illustrating an IM component occurring between FAs in the same service.

For example, in the case of cellular service, since multiple FAs are used, IM components between FAs may occur in a reception frequency band. Specifically, it is shown in [Table 2] below.

division frequency IMD Cellular transmission 869∼894MHz 869 * 2-889 = 844MHz
Cellular reception 824-849 MHz

In Table 2, IM components occurring between FAs in the same cellular service can be identified.

There may be a method of separating transmission and reception in order to remove this IM component. Figure 5b is a configuration diagram of an embodiment of a transmission and reception separation scheme. The transmission / reception scheme of FIG. 5B essentially separates the feed line and the antenna of the transmission output stage, thereby fundamentally preventing IM components generated due to non-linearity of the transmission amplifier from being rejected into the reception band. This is a relatively simple method, but the construction cost of the feeder and antenna increases, and in reality the installation space of the antenna can not be afforded can be limited in the application place for minimizing the impact of IM. Although the transmission / reception scheme of FIG. 5B may be partially applied to the base station and the terrestrial optical repeater, it may be difficult to apply if a large number of feeders are used in a building.

Alternatively, there is a method of dividing the output applied to the feeder into a plurality of ports to reduce the shadow area in the building (ie, output separation). 5C is a diagram illustrating an embodiment of an output separation scheme. This can be done realistically, but the design itself is complex and difficult to operate and manage.

Thus, the interference cancellation apparatus of the present invention as described above can be applied even within the same service as shown in FIG. 5D.

5d is another embodiment of the interference canceling apparatus of the mobile communication system according to the present invention.

As shown in FIG. 5D, the interference cancellation apparatus extracts a third order IM component by amplifying a transmission signal component in a nonlinear band in one monitoring port and extracts a level of a PIMD component outside the reception band in the same service. After adjusting the level of the third-order IM component, the phase inversion is performed to remove the PIMD component from the cellular reception band (see FIG. 3 above).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1A is a diagram illustrating an embodiment of a WCDMA in-building relay system;

Figure 1b is a configuration diagram of an embodiment of a mobile Internet (WIBRO) in-building relay system,

2A is a diagram illustrating an embodiment of a feeder line sharing method between WCDMA and PCS;

Figure 2b is a configuration diagram of an embodiment of a feeder line sharing method between the mobile Internet (WIBRO) and WCDMA,

3 is a block diagram of an embodiment of an interference cancellation apparatus of a mobile communication system according to the present invention;

4A is an exemplary view illustrating the characteristics of a nonlinear device;

4b is a graph of the 3rd order PIMD frequency caused by WCDMA and WiBRO feedline sharing,

4C is a graph of the waveform of the PIMD frequency resulting from WCDMA and WiBRO feedline sharing,

5A is a diagram illustrating an IM component occurring between FAs in the same service.

5b is a configuration diagram of an embodiment of a transmission and reception separation scheme;

5c is a diagram illustrating an embodiment of an output separation scheme;

5d is another embodiment of the interference canceling apparatus of the mobile communication system according to the present invention.

* Explanation of symbols for the main parts of the drawings

310: interference generator

320: level detector 330: level controller

340: phase delay 350: signal canceller mixer

Claims (11)

In the interference cancellation device, Interference extracting means for extracting an interference canceling signal corresponding to a frequency component of the interference signal by using the transmission signal components extracted for each mobile communication system; Level detecting means for detecting a signal level corresponding to a level component of the interference signal in the received signal of the mobile communication system to remove the interference signal; Level control means for controlling a level component of the extracted interference cancellation signal according to the detected signal level; Phase delay means for phase inverting the interference canceling signal from the level control means; And Interference signal removing means for removing the interference signal by combining the received signal and the phase inverted interference cancellation signal Interference cancellation device comprising a. The method of claim 1, The interference extraction means, And an interference canceling device extracting an interference canceling signal corresponding to a frequency component of the interference signal by mixing transmission signal components extracted for each mobile communication system and amplifying them in a nonlinear region. The method of claim 2, The level detecting means, An interference canceling device for detecting a signal level of the DC component by separating the portion corresponding to the interference signal from the received signal extracted through the feed line. The method of claim 3, wherein The level detecting means, An interference canceling device that extracts a received signal from a feeder router of an aerial system using a splitter. The method of claim 3, wherein The interference cancellation device, And an "U-junction" or "T-junction" distributor as the first stage distributor of the feeder. The method of claim 2, The phase delay means, And an interference canceling device for retarding the phase of the interference canceling signal from the level control means by 180 °. 7. The method according to any one of claims 1 to 6, The interference signal is, The feed line is shared by the mobile communication system and the other mobile communication system, and the difference between the second harmonic component of the transmission signal of the mobile communication system and the harmonic component of the transmission signal of the other mobile communication system is upward of the mobile communication system. The interference cancellation device, characterized in that the signal containing a passive intermodulation distortion (PIMD) component included in the frequency band. In the interference cancellation method, An extraction step of extracting an interference canceling signal corresponding to a frequency component of the interference signal using the transmission signal components extracted for each mobile communication system; Detecting a signal level corresponding to a level component of the interference signal in the received signal of the mobile communication system to remove the interference signal; A control step of controlling a level component of the extracted interference cancellation signal according to the detected signal level; And A phase inverting the controlled interference cancellation signal and removing the interference signal by combining with the received signal Interference cancellation method comprising a. The method of claim 8, The extraction step, And a method for extracting an interference cancellation signal corresponding to a frequency component of the interference signal by mixing transmission signal components extracted for each mobile communication system and amplifying them in a nonlinear region. The method of claim 9, The detecting step, An interference cancellation method for detecting a signal level of a DC component by separating a portion corresponding to an interference signal from a received signal extracted through a feed line. The method according to any one of claims 8 to 10, The interference signal is, The feed line is shared by the mobile communication system and the other mobile communication system, and the difference between the second harmonic component of the transmission signal of the mobile communication system and the harmonic component of the transmission signal of the other mobile communication system is upward of the mobile communication system. And a signal including a passive intermodulation distortion (PIMD) component generated in a frequency band.

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