KR100905536B1 - Interfere Cancellation Repeater Including Dividing Function for Cancellation Window and Method thereof - Google Patents

Abstract

The present invention relates to an oscillation elimination repeater including a feedback elimination window splitting function and a method thereof.

To this end, the present invention, the repeater for eliminating the oscillation due to the feedback signal, the radio signal received through the receiving antenna by moving the feedback cancellation window, where the radio signal may include its own padback and inter-device feedback signal A window setting unit searching for a feedback signal in the present and allocating a feedback removing window (Xtot) to a feedback signal region exceeding a predetermined threshold value among the found feedback signals; And a feedback signal removing unit removing the feedback signal from the received wireless signal based on the feedback removing window assigned by the window setting unit.

According to the present invention, it is possible to detect and cancel the feedback signal effectively according to the feedback signal type by searching for the feedback signal and removing feedback feedback.

Oscillation, elimination, repeater, feedback, window, split

Description

Interference Cancellation Repeater Including Dividing Function for Cancellation Window and Method

The present invention relates to an oscillation elimination repeater including a feedback elimination window splitting function and a method thereof. More specifically, the present invention relates to an oscillation elimination repeater for detecting and removing feedback signals by searching for feedback signals and dividing the feedback elimination window based on the found feedback signals.

With the development of communication technology, mobile communication system has been developed and popularized, and the service business using it is expanding. Such a mobile communication system can provide a unidirectional or bidirectional communication service from a predetermined transmission medium to a reception medium in a jurisdiction. However, such a mobile communication system has difficulty in providing a communication service when a predetermined communication shadow area is formed, such as a location of a transmission medium and a reception medium, for example, a mountain area, a dense area of a large building, or a basement.

In order to prevent the degradation of the communication service due to the formation of the communication shadow area, a radio frequency (RF) repeater that amplifies and transmits a signal received from a transmission medium has been developed and introduced. Therefore, a wireless repeater is a device for providing a high quality of service by amplifying a signal between a transmission medium and a reception medium, and reaching radio waves in a shaded area that is far away from each other or is hidden in a building. .

1 is a view schematically showing a configuration of a conventional wireless repeater.

Referring to FIG. 1, a wireless repeater includes a reception antenna for communication with a transmission medium, a transmission antenna for communication with a reception medium, and an amplifier for amplifying a signal applied from the reception antenna to a predetermined level and outputting the signal to the transmission antenna. It is composed. When the wireless repeater configured as described above does not sufficiently secure the separation distance between antennas, a feedback loop is formed in which an amplified signal amplified and output through the amplifier is applied to the input of the wireless repeater. Oscillation is repeatedly amplified.

In more detail, the signal transmitted from the base station system to the repeater is input to the repeater receiving antenna, and the signal is amplified by a gain G by an amplifier and radiated by the transmitting antenna. Here, some of the signals radiated by the transmitting antenna are input back to the receiving antenna via the surrounding reflector and the like, and a feedback loop is amplified by the repeater gain G. The path loss of the feedback signal from the transmitting antenna to the receiving antenna is called isolation. If the isolation is not secured by a certain value compared to the repeater gain G, oscillation by the feedback loop occurs.

Therefore, the conventional co-band amplified wireless repeater was forced to lower the repeater gain due to the above-mentioned oscillation phenomenon, and was used only at low power in limited places such as the basement of the building to avoid the oscillation phenomenon.

FIG. 2 is a diagram schematically illustrating a configuration of an interference cancellation system repeater (ICS) that detects / removes a feedback signal that causes oscillation.

The feedback signal removing unit of the oscillation eliminating repeater is composed of a feedback signal detector for detecting the feedback signal using the correlation value of the received signal and a feedback signal removing filter for tracking the characteristics of the feedback signal that changes over time in real time. Eliminate the reflected signal. Since the hardware of the feedback signal cancellation filter that can be implemented is limited, the delay time of the removable feedback signal, that is, the distance of the feedback signal, is limited. For example, in the case of a WCDMA system, the cancellation window size, that is, delay time according to the removable feedback signal distance, is shown in Table 1. Table 1 shows the relationship between time delay and distance in a WCDMA system.

Generally, feedback signal level is hardly affected by path loss after 2 ~ 3km path, so feedback cancellation window size is designed considering this.

TABLE 1

Delay time Use One 1.67 3.33 4 6 8 Chip 3.84 6.4 12.8 15.38 23.04 30.72 Distance (Km) Round-trip 0.3 0.5 One 1.2 1.8 2.4 One-way 0.15 0.25 0.5 0.6 0.9 1.2

3 is a diagram illustrating a method of setting / operating a feedback removing window in a conventional oscillation removing repeater. In general, it operates as a structure to remove the feedback signal existing in the window to the Xtot (usec) based on the system delay time of the equipment. That is, although the feedback signal up to Xtot (usec) is included in the range of the feedback cancellation window, the feedback signal can be removed. Feedback signals over Xtot (usec) cannot be removed. For example, according to Table 1, when designing Xtot as 8usec, feedback signal of 2.4km path can be eliminated. In general, the feedback signal detection searches the entire Xtot window by connecting unit windows having a size of Xstep in a sequential or parallel manner, which can be represented by Equation 1.

Equation 1 indicates that the total window size (Xtot) that can be removed can be expressed as the sum of M unit windows (Xstep).

However, since the oscillation elimination repeater is a kind of RF repeater, there is a possibility that a phenomenon of exchanging signals with other RF repeaters in the vicinity occurs. As such, when a feedback loop is formed by signal transmission and reception between devices, since a delay time of the device itself is included in the feedback path, a feedback signal is formed outside the feedback cancellation window area Xtot.

4A and 4B illustrate a case where a feedback loop is formed between the oscillation removing repeater equipments.

가 기지국과 DU 간의 거리

보다 상대적으로 작다면, RU에서 DU로 신호가 재입력되는 신호 레벨의 경로 손실이 작아 장비간 피드백 신호를 무시할 수 없게 된다. 또한, 안테나의 전/후방비를 고려한다 하더라도 거리에 따른 경로 손실의 영향이 상대적으로 작아지는 환경에서는 장비간 피드백 루프가 형성되며, 장비간 신호는 피드백제거 윈도우 영역 밖에 위치하여 발진의 원인이 된다.When operating the oscillation eliminating repeater cascade as shown in Figure 4a, the repeater of the front end is called a DU (Donor Unit), the repeater of the rear end is called a RU (Remote Unit). Distance between DU and RU

Distance between base station and DU

If it is relatively small, the path loss of the signal level at which the signal is re-input from the RU to the DU is small so that the inter-device feedback signal cannot be ignored. Also, even when considering the front / rear ratio of the antenna, the feedback loop is formed between the devices in the environment where the effect of the path loss with the distance is relatively small, and the signal between the devices is located outside the feedback cancellation window area, which causes the oscillation. .

Even in the case of the non-connected type as illustrated in FIG. 4B, the same equipment-to-device feedback loop as described in FIG. 4A may be formed under environmental conditions in which a large number of oscillation elimination repeaters are located in the periphery.

If the feedback signal is formed outside the feedback cancellation window area, the isolation of the actual system should be degraded. However, since the isolation measurement is generally measured using the feedback signal removal amount of the equipment, the isolation measurement value is also incorrect in the above example. In addition, the formation of feedback loops between equipment that cannot be eliminated can cause equipment degradation and oscillation.

It is an object of the present invention to provide an oscillation elimination repeater and a method including a feedback elimination window splitting function capable of eliminating oscillations caused by feedback signals between equipments.

delete

According to one aspect of the invention there is provided a repeater for eliminating oscillation by a feedback signal. The repeater, which eliminates oscillations caused by the feedback signal, searches for the feedback signal in a wireless signal received through the receiving antenna by moving the feedback cancellation window, where the wireless signal may include its own feedback and a relay feedback signal. A window setting unit for allocating a feedback removing window Xtot to a feedback signal region exceeding a predetermined threshold value among the found feedback signals; And a feedback signal removing unit removing the feedback signal from the received wireless signal based on the feedback removing window assigned by the window setting unit.
According to another aspect of the invention there is provided a method for eliminating oscillation by a feedback signal in a repeater. The oscillation cancellation method searches for a feedback signal in a wireless signal received through a reception antenna by moving a feedback cancellation window, where the wireless signal may include its own padback and inter-device feedback signal, and the searched feedback signal. A window setting step of allocating a feedback removing window (Xtot) to a feedback signal region exceeding a predetermined threshold value; And extracting and removing a feedback signal from the received wireless signal based on the feedback cancellation window assigned in the window setting step.

According to the present invention, it is possible to provide an oscillation elimination repeater and a method including a feedback elimination window splitting function capable of eliminating oscillations caused by feedback signals between equipments.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

5 is a view showing the configuration of the oscillation removing repeater according to an embodiment of the present invention.

The oscillation removing repeater (hereinafter, referred to as a "relay") according to an embodiment of the present invention includes a receiving antenna 100, an A / D converter 200, a feedback signal removing unit 300, a window setting unit 400, A D / A converter 500, an amplifier 600, and a transmission antenna 700 are included. In addition, the feedback signal remover 300 includes a feedback signal remover filter 310 and a feedback signal detector 320, and the window setting unit 400 controls the window divider 410 and the feedback signal searcher 420. Include.

The repeater is configured to support a bidirectional link, that is, a forward link and a reverse link. The forward link receives a signal from the base station to the receiving antenna 100 and transmits the signal of the base station to the shaded area where the signal of the base station does not reach through the transmitting antenna 700, the reverse link transmits a signal provided from the terminal It receives the antenna 700, and transmits it to the base station through the receiving antenna 100.

The following description will be given based on the forward link, and the reverse link may be considered to be the reverse of the forward link.

를 수신하는 안테나이며, 일반적으로 원수신신호

에는 여러 기지국의 신호가 포함되어 있다. 또한, 본 발명의 실시예의 수신안테나(100)는 당해 중계기의 송신안테나(700)로부터 무선 채널을 통해 수신되는 자체 피드백 신호

및 주변의 다른 중계기의 송신안테나로부터 무선 채널을 통해 수신되는 장비간 피드백 신호

도 함께 수신한다. 즉, 수신안테나(100)로 수신되는 총 입력신호

는 원수신신호

와 자체 피드백 신호

및 장비간 피드백 신호

의 합이다. 여기서 총입력신호는 아날로그 신호이다. The receiving antenna 100 receives the win signal from the base station

Is an antenna that receives the signal

Contains signals from several base stations. In addition, the receiving antenna 100 of the embodiment of the present invention is a self-feedback signal received via a wireless channel from the transmitting antenna 700 of the repeater

And equipment-to-device feedback signals received through a wireless channel from a transmitting antenna of another repeater

Also receives with. That is, the total input signal received by the receiving antenna 100

Is the incoming signal

And self feedback signal

Signal between equipment and equipment

Sum of The total input signal is an analog signal.

를 디지털 신호로 변환하며, 이때 생성된 디지털 신호를

로 나타낼 수 있다. 여기서 n은 칩인덱스이다. The A / D converter 200 is a total input signal which is an analog signal received by the receiving antenna 100.

Is converted into a digital signal, and the generated digital signal

It can be represented as. Where n is the chip index.

에서 피드백 신호를 제거한다. The feedback signal remover 300 includes a feedback signal remover filter 310 and a feedback signal detector 320, and total input signals in unit window units.

Remove the feedback signal from.

와 이전에 생성된 피드백이 제거된 신호와의 상관관계를 이용하여 상관도를 계산하고, 계산된 상관도를 통해 변화하는 피드백 신호의 시간 지연, 진폭 및 위상을 추정한다. 상관도를 계산하는 범위가 피드백제거 윈도우의 크기이며, 본 발명의 실시예의 피드백 신호 검출부는 윈도우 설정부에 의해 정해진 피드백 윈도우에 대한 피드백 신호를 검출한다. The feedback signal detector 320 is a total input signal in units of a unit feedback window (Xstep).

The correlation is calculated using the correlation with the signal from which the previously generated feedback is removed, and the estimated time delay, amplitude, and phase of the feedback signal varying from the calculated correlation. The range for calculating the correlation is the size of the feedback cancellation window, and the feedback signal detector of the embodiment of the present invention detects the feedback signal for the feedback window determined by the window setting unit.

에서 피드백신호 제거필터(310)로부터 검출된 피드백 신호를 빼주어, 피드백 신호가 제거된 출력 신호

를 생성한다. The feedback signal rejection filter 310 generates an anti-phase signal of the feedback signal using the time delay, amplitude, and phase estimated by the feedback signal detector 320, and applies the generated anti-phase signal to the total input signal to input the total input signal. Remove the feedback signal from the signal. That is, using the subtractor, the total input signal

The output signal from which the feedback signal is removed by subtracting the feedback signal detected from the feedback signal removal filter 310 at

Create

The window setting unit 400 includes a window dividing unit 410 and a feedback signal searching unit 420, and divides and sets a feedback removing window by identifying characteristics of the feedback signal.

The feedback signal search unit 420 sequentially connects the unit window search function to search for a window having a size of about N * Xtot. 6 is a diagram illustrating an operation of the feedback signal search unit 420.

Referring to FIG. 6, the feedback elimination window Xtot, which is a range for calculating correlation, is sequentially moved, and the feedback signal is searched in units of the unit window Xstep in the feedback elimination window Xtot. That is, the feedback removing window Xtot is sequentially moved to (N * Xtot), and the feedback signal is searched in units of a unit window (Xstep) within each feedback removing window. because of this. Even without adding a search hardware resource, the feedback signal can be detected by N times or more than the existing window using only the sequential window search function. Here, the feedback elimination window Xtot is the size of the feedback elimination window defined by the limitation of the hardware resource.

The window dividing unit 410 divides the entire feedback removing window Xtot to allocate a feedback removing window to a feedback signal region exceeding a predetermined threshold value among the feedback signals searched by the feedback signal searching unit 420. In addition, each divided window is divided into a unit window (Xstep). The entire window Xtot is divided as in Equation 2.

을 만족한다.only Is a natural number and indicates how many unit windows the kth split window is composed of.

To satisfy.

7 shows an example in which the feedback removing window is divided. Referring to FIG. 7, a feedback signal region exceeding a predetermined boundary among the feedback signals searched by the feedback signal searcher 420 forms three groups. In addition, each divided window is divided into a unit window (Xstep).

,

,

는 각각 3, 3, 2로 설정되어 있다. In other words, the K value by the feedback elimination window division is set to three. Also,

,

,

Are set to 3, 3, and 2, respectively.

The oscillation elimination repeater according to the embodiment of the present invention includes a window setting unit 400 to search for a feedback signal in an area N * Xtot which is N times the size Xtot of the feedback elimination window. Thereafter, the size Xtot of the entire feedback cancellation window is divided according to the searched feedback signal. Through this, it is possible to effectively remove the feedback signal by setting the feedback cancellation window in a large portion of the feedback signal. In particular, the feedback signal between the oscillation elimination repeater equipment occurring outside the region of the feedback elimination window can be effectively eliminated.

를 아날로그 신호 형태인

로 변환한다.The D / A converter 500 is a signal from which the feedback signal is removed by the feedback signal removing unit 300.

To form an analog signal

Convert to

를 이득 G 만큼 증폭시킨다. 이때. 증폭부(600)에서 증폭된 신호는

로 나타낼 수 있다. The amplifier 600 is an analog output signal converted by the D / A converter 500

Amplifies by gain G. At this time. The signal amplified by the amplifier 600

It can be represented as.

를 다른 단말기로 송신하는 안테나이다. The transmission antenna 700 amplified by the amplifier 600

Is an antenna for transmitting to another terminal.

8 is a flowchart illustrating an operation of an oscillation elimination repeater including a feedback elimination window splitting function according to an exemplary embodiment of the present invention.

를 수신(S101)하고, 총입력신호

를 디지털 신호로 변환한다(S103). 여기서, 총 입력신호

는 원수신신호

와 자체 피드백 신호

및 장비간 피드백 신호

의 합이다. First, the total input signal from the receiving antenna 100

Receive (S101), the total input signal

Is converted into a digital signal (S103). Where the total input signal

Is the incoming signal

And self feedback signal

Signal between equipment and equipment

Sum of

Subsequently, the window setting step P1 is performed, and in the window setting step, the feedback signal search S105 is performed and the feedback removing window is divided S107.

In the feedback signal search step (S105), the unit window search function is sequentially further connected to search for a window of size N * Xtot to detect a feedback signal in the range of N * Xtot. In the feedback elimination window dividing step S107, the entire feedback elimination window Xtot is divided to allocate a feedback elimination window to a feedback signal region exceeding a predetermined threshold value among the feedback signals searched in the feedback signal searching step S105. In addition, each divided window is divided into a unit window (Xstep).

Thereafter, based on the divided window, a feedback signal is detected in each unit window (S109), and the detected feedback signal is removed (S111).

The output signal from which the feedback signal is removed is converted into an analog signal (S113), and the analog output signal is amplified (S115). The amplified signal is transmitted to another terminal (S117).

In the above, the case where the oscillation elimination repeater always performs the window setting step P1 has been described. However, the position of the feedback signal is generally not a parameter whose value changes frequently with time, and most of the position of the feedback signal is defined according to the surrounding installation environment. In other words, the position of the feedback removal window is a semi-static parameter that does not need to be updated frequently. Therefore, the window setting step P1 may be performed only once when the device is powered on or may be performed at regular intervals.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a view schematically showing a configuration of a conventional wireless repeater.

2 is a diagram schematically illustrating a configuration of an oscillation elimination repeater for detecting / removing a feedback signal that causes oscillation.

3 is a diagram illustrating a method of setting / operating a feedback removing window in a conventional oscillation removing repeater.

 4A and 4B illustrate a case where a feedback loop is formed between the oscillation removing repeater equipments.

5 is a view showing the configuration of the oscillation removing repeater according to an embodiment of the present invention.

6 is a diagram illustrating an operation of the feedback signal search unit 420.

7 shows an example in which the feedback removing window is divided.

8 is a flowchart illustrating an operation of an oscillation elimination repeater including a feedback elimination window splitting function according to an exemplary embodiment of the present invention.

Claims (11)

In the repeater to remove the oscillation by the feedback signal, Moves the feedback cancellation window to search for a feedback signal from a wireless signal received through the receiving antenna, where the wireless signal can include its own feedback and a relay feedback signal, and exceeds a predetermined threshold of the found feedback signals. A window setting unit for allocating a feedback removing window Xtot to the feedback signal region; And A feedback signal removing unit for removing a feedback signal from the received wireless signal based on the feedback removing window allocated by the window setting unit; Repeater included. The method of claim 1, The window setting unit A feedback signal search unit that receives the received wireless signal and sequentially moves a feedback cancellation window Xtot to search for a feedback signal; And A window partitioner configured to allocate a feedback cancellation window to a feedback signal region exceeding a predetermined threshold value among the searched feedback signals to set a divided feedback removal window, and to divide the divided feedback removal window into a unit window (Xstep). Repeater included. The method of claim 2, The feedback signal search unit, The feedback elimination window Xtot is sequentially moved, and a feedback signal is searched in units of a unit window Xstep in the feedback elimination window Xtot, The feedback removal window Xtot

(Where M is a natural number) Repeater. The method of claim 3, The window divider The feedback removal window (Xtot)

(here,

Is a natural number and indicates how many unit windows the kth divided window is composed of.

Divided into Repeater. The method of claim 4, wherein The feedback signal removing unit Feedback for estimating the time delay, amplitude, and phase of a feedback signal by using a correlation between the received wireless signal and a signal from which previously generated feedback is removed at a position of a unit window (Xstep) divided by the window divider. A signal detector; And A feedback signal removal filter generating an antiphase signal of the feedback signal estimated by the feedback signal detection unit, and removing the feedback signal from the received wireless signal using the generated antiphase signal; Repeater. The method of claim 5, The amplification unit further amplifies a signal from which the feedback signal is removed by the feedback signal removing filter by a predetermined gain. Repeater. In the method for removing the oscillation by the feedback signal in the repeater, Moves the feedback removal window to search for a feedback signal from a wireless signal received through the receiving antenna, where the wireless signal can include its own padback and inter-device feedback signals, and detects a certain threshold of the found feedback signals. A window setting step of allocating a feedback removing window Xtot to the over feedback signal region; And Detecting and removing a feedback signal from the received wireless signal based on the feedback cancellation window assigned in the window setting step. How to get rid of rashes. The method of claim 7, wherein The window setting step, A feedback signal searching step of receiving the received wireless signal and sequentially moving a feedback removing window Xtot to search for a feedback signal; And A window splitting step of allocating a feedback removing window to a feedback signal region exceeding a predetermined threshold value among the searched feedback signals to set a divided feedback removing window, and dividing the divided feedback removing window into a unit window (Xstep); doing How to get rid of rashes. The method of claim 8, The feedback signal search step, The feedback elimination window Xtot is sequentially moved, and a feedback signal is searched in units of a unit window Xstep in the feedback elimination window Xtot, The feedback removal window Xtot

(Where M is a natural number) How to get rid of rashes. The method of claim 9, The window partitioning step The feedback removal window (Xtot)

(here,

Is a natural number and indicates how many unit windows the kth divided window is composed of.

Divided into How to get rid of rashes. The method of claim 10, Amplifying the signal from which the feedback signal is removed by a preset gain. How to get rid of rashes.

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