KR20110067785A - Access node apparatus for noise reduction caused by optical repeater and method thereof - Google Patents

Abstract

PURPOSE: An access node apparatus and method thereof having a noise elimination function are provided to increase coverage expansion by using a relay without the degradation of transmission speed. CONSTITUTION: A reception antenna(110) receives an electric wave which is radiated from a mobile terminal. A low noise amplifying unit(120) inputs a reverse signal which is radiated from the mobile terminal. The low noise amplifying unit performs low noise amplification of the reverse signal. An attenuation circuit unit(130) inputs a synthesis signal of an external relay. The attenuation circuit unit outputs a power level of the inputted signal.

Description

A connected node device having a noise canceling function due to an optical repeater and a method thereof {ACCESS NODE APPARATUS FOR NOISE REDUCTION CAUSED BY OPTICAL REPEATER AND METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection node device having a noise canceling function due to an optical repeater and a method thereof, and more particularly, to the use of an optical repeater in a mobile communication system in which an optical repeater is introduced to expand coverage at a low cost. The present invention relates to a connection node device and a method for removing unwanted noise generated and preventing a decrease in upload transfer speed caused by unwanted noise.

In mobile networks, various repeaters are used to increase coverage at low cost. In particular, the optical repeater connected to the base station through the optical cable has the advantage that can provide coverage of the size equivalent to the base station at a cost of about 10 to 15% of the base station, and is widely used in many mobile communication networks.

However, while the optical repeater has the advantage of providing high economics and flexibility to enable a variety of networks, it has the disadvantage of generating unnecessary noise in the base station receiver due to the installation of the optical repeater. Unnecessary noise increases with the number of optical repeaters used, and this increase in noise deteriorates the signal-to-noise ratio (S / N) of the signal arriving at the base station receiver, reducing the base station's reception capacity and coverage. Cause. In particular, data services have a greater impact than voice services. This is because the voice service requires only a transmission speed of 13 kbps while the voice service requires a data rate as fast as possible.

In most base station receivers, even if unnecessary noise is generated by the optical repeater, the capacity to provide a service of about 13 kbps to dozens remains. Therefore, even though a certain amount of unnecessary noise occurs in the base station receiver, the user hardly notices a deterioration of the voice service even if the capacity is reduced.

However, in the data service, as the transmission speed is higher, the user can complete the data transmission in a short time. Therefore, in contrast to the voice service, the data service provides the user with the highest transmission speed. Therefore, when providing the data service, the base station gives the user the maximum available capacity remaining. Here, the usable capacity refers to the maximum power that the terminal can radiate toward the base station or the maximum power of the terminal that the base station receiver can accept.

At this time, there is a difference in the amount of power that the base station can receive between the base station where the unnecessary noise is caused by the optical repeater and the base station, so the difference is directly reflected in the quality of service (transmission speed) and uploaded by the user. You can feel the difference in transmission speed.

As such, when an optical repeater is used for the purpose of extending coverage when providing a mobile communication service, unnecessary noise is generated at the base station receiving unit, and such unnecessary noise reduces the reception capacity and the coverage of the base station, thereby degrading service quality. .

The present invention has been proposed to solve the problems of the prior art as described above, the object of which is to remove the noise caused by the repeater in a mobile communication system, such as coverage expansion, economical and flexibility improvement through the use of a repeater without performance degradation It is an object of the present invention to provide a connection node device and a method for ensuring an effect.

Another object of the present invention is to provide a connection node apparatus and a method for preventing a decrease in upload transmission speed by a repeater in a mobile communication system and restoring the transmission speed to a noise-free state to ensure reception capacity and coverage. .

The technical problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to an aspect of the present invention, there is provided a connected node apparatus having a noise canceling function, comprising: a receiving antenna for receiving radio waves radiated from a mobile terminal; A low noise amplifier for performing low noise amplification by receiving the reverse signal radiated from the mobile terminal through the receiving antenna; And an attenuation circuit unit configured to receive a sum signal of an external repeater connected in parallel with the low noise amplifier and the low noise amplifier, to attenuate and output a power level of the input signal.

In addition, the attenuation circuit portion may be configured to adjust the amount of attenuation made of a variable resistor.

In addition, the attenuation circuit unit may attenuate the input signal by an increased noise value due to the external repeater.

Further, the attenuation circuit unit may be configured to have an attenuation amount of 1/10 or less in comparison with the gain of the low noise amplifier.

Furthermore, by adjusting the attenuation amount of the attenuation circuit portion at intervals within a range of 0 dB to 5 dB to calculate the optimum attenuation with the lowest noise value, and controlling the process of setting the calculated optimal attenuation amount to the attenuation amount of the attenuation circuit portion. The attenuation adjustment unit may further include.

According to an aspect of the present invention, there is provided a method for removing noise of a connected node device, the method comprising: (a) receiving a radio wave emitted from a mobile terminal through a receiving antenna; (B) performing low noise amplification on the reverse signal emitted from the mobile terminal; And (c) receiving a sum signal of a reverse signal received through an external relay device and the low noise amplified reverse signal and attenuating and outputting a power level of the input signal.

Furthermore, step (c) may be performed through a variable resistor configured to adjust the amount of attenuation.

Furthermore, in step (c), the attenuation may be attenuated by the input signal by an increase in noise due to the external relay.

Furthermore, the amount of attenuation in step (c) may be 1/10 or less as compared with the amplification gain in step (b).

Further, the step (c) may include adjusting the attenuation amount step at a predetermined interval within a range of 0 dB to 5 dB; Calculating a noise value each time the attenuation amount step is adjusted and storing the calculated noise value in a memory; Comparing the calculated noise values with each other to select a minimum noise value, and searching for an optimum amount of attenuation used when calculating the selected minimum noise value; And setting the optimum amount of attenuation as the amount of attenuation.

According to the present invention, by removing the noise due to the repeater in the mobile communication system, it is possible to secure the effects of coverage expansion, economical efficiency and flexibility through the use of the repeater without degrading performance.

In addition, according to the present invention, it is possible to prevent the upload transmission speed by the repeater in the mobile communication system and to restore the transmission speed to a noise-free state to secure the reception capacity and the coverage.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the connection node device and method having a noise removing function due to the optical repeater.

1 is a block diagram schematically illustrating a receiver of a connection node device according to an embodiment of the present invention. In one embodiment, the access node device may be a base station or Node B for providing a mobile communication service.

Referring to FIG. 1, a connection node device according to an embodiment includes an antenna 110, a low noise amplifier 120, an attenuation circuit 130, a transceiver 140, an analog-to-digital converter 150, and the like in a receiver. do.

The receiving antenna 110 functions to receive radio waves radiated from the mobile terminal of the user. Although not shown, a reception filter for filtering reverse signals received through the reception antenna 110 according to a detection condition and transmitting them to a band pass filter, and a band pass filter connected to the reception filter to pass only signals of a desired band at a later stage. Etc. may be located.

The low noise amplifier 120 receives a reverse signal radiated from the mobile terminal through the reception antenna 110 and removes and amplifies the noise from the input signal.

The attenuation circuit unit 130 receives the sum signal of the external repeater 200 connected in parallel with the low noise amplifier 120 and the low noise amplifier 120, and attenuates and outputs the power level of the input signal. The attenuation circuit unit 130 described above is used to attenuate the input signal by an increase in the noise value due to the external relay device 200. The attenuation circuit unit 130 may be implemented as a variable resistor to adjust the attenuation amount. In addition, the attenuation circuit unit 130 preferably has an attenuation amount of 1/10 or less as compared with the gain of the low noise amplifier 120.

The transceiver unit 140, the analog-to-digital converter 150, and the like are disposed at the rear end of the attenuation circuit unit 130. The transceiver unit 140 lowers the frequency of the signal received from the attenuation circuit unit 130 to an intermediate frequency (IF) band so that the received signal can be smoothly sampled by the analog-to-digital converter 150 connected to the rear end. do. In addition, the analog-to-digital converter 150 serves to enable baseband processing by digitizing the analog signal by sampling the received signal.

In another embodiment, the connection node 100 may further include an attenuation adjustment unit 160. The attenuation amount adjusting unit 160 adjusts the attenuation amount of the attenuation circuit unit 130 at a predetermined interval within a range of 0 dB to 5 dB to calculate an optimum attenuation amount having the smallest noise value, and calculates the calculated attenuation amount of the attenuation circuit part 130. Control the process of setting. The attenuation amount adjusting unit 160 can be omitted according to the embodiment.

The relay device 200 is for extending the service range of the access node 100 and is connected to the connection node 100 by wire to receive the traffic of the mobile terminal. The repeater 200 includes an antenna 210 for receiving a radio signal supplied from a mobile terminal and an optical repeater 220 of an output terminal. The optical relay unit 220 provides the reverse signals received through the reception antenna 210 to the receiver of the access node 100 through optical transmission.

The reverse loading of the connection node 100 is a degree in which the capacity of the receiving unit is used in the connection node 100 and is measured in a manner described later and may be provided to a network controller and a mobile terminal such as a radio network controller (RNC), a switch, and the like. . Originally, the reception noise value of the connection node 100 means a value at the standard position P10, but when the level of the signal is very low at that position and a module for level measurement is mounted at the position, the receiver of the connection node 100 is provided. In this case, reception sensitivity may decrease due to an increase in the noise factor (NF). Therefore, the measurement of the reception level is performed at the measurement position P20 where the signal is amplified sufficiently strong, and after the measurement, the amplification ratio between the standard position P10 and the measurement position P20 is subtracted from the measured value and is present at the standard position P10. Calculate the level of the signal. Thereafter, this is converted into a capacity used by the receiving unit of the connection node 100 again.

For example, in the case of a WCDMA mobile communication system, a noise value fluctuation of -95 to -105 dBm / 5 MHz may occur at the reception unit of the access node 100 when there is the most traffic. That is, the reception capacity of the connection node 100 starts at −105 dBm and shows a noise value change of about 10 dB. If the relay 200 is connected to the noise value rise of about 3 dB, the range of noise value change of the connection node 100 becomes -95 to -102 dBm / 5 MHz, so that the available range is reduced to 7 dB so that the reverse capacity is increased. Is reduced.

Therefore, one embodiment attenuates the noise value by 3 dB using the attenuation circuit 130 of 3 dB immediately after the point where the signals of the connection node 100 and the relay device 200 merge. In this case, a noise level of −105 dBm is again sensed by the signal level detector at the measurement position P20 that measures the reception noise value, and a rise in noise by the relay 200 is not detected. The noise range available at the connection node 100 is restored to the original 10 dB. If the attenuation circuit unit 130 has a variable function capable of varying the attenuation amount, the attenuation circuit unit 130 can attenuate the amount of unnecessary noise increased by using a different relay device for each connection node, so that the attenuation circuit unit 130 can appropriately respond to various noise value rises. Can be.

FIG. 2 is a diagram for describing generation of noise in FIG. 1.

All amplifiers always output some level of noise power at the output, even if no input is present. The noise value of an amplifier is defined as the thermal noise (dB) + amplifier noise figure (dB) + gain (dB) ＇level. If two such amplifiers (AMP1, AMP2) are connected in parallel as shown in FIG. 2, the output noise value is increased by 2 times (3dB), and when this is expressed in dB scale, ＇thermal noise (dB) + noise figure of the amplifier (dB) + gain (dB) + 3dB ＇. Since the relay device 200 may also be viewed as a kind of amplifier, when the relay device 200 is connected to the connection node 100, the relay device 200 is connected to the relay device 200 while making a parallel connection with the low noise amplifier 120 and the optical relay 220. Even if the signal of the mobile terminal is not input at all, noise power of ＇thermal noise (dB) + noise figure (dB) + gain (dB)＇ level is output to the output terminal of the relay 200 so that the receiver of the connection node 100 can be output. Is entered.

As shown in FIG. 1, the low noise amplifier 120 is mounted at the receiver input terminal of the connection node 100. When the relay device 200 is installed, the low noise amplifier 120 is viewed from the side of the receiver of the connection node 100. The second and third amplifiers as shown in FIG. 3 have an effect in that the receiver is additionally installed in parallel, and the noise value increases as the number of repeaters 200 used increases. As described above, the increase in noise due to the use of the relay 200 deteriorates the signal-to-noise ratio of the reverse signal of the mobile terminal arriving at the receiver of the connection node 100, thereby reducing the reception capacity and coverage of the connection node 100. Let's do it.

Therefore, in order to improve the decrease in the upload speed of the data service caused by the noise of the relay 200 input to the receiver of the connection node 100, variable attenuation is possible at an appropriate position inside the receiver of the connection node 100. By installing the attenuation circuit unit 130, unnecessary noise is reduced and the upload speed is prevented from being lowered due to the installation of the relay device 200. The proper position of the attenuation circuit unit 130 is after the point where the low noise amplifier 120 of the connection node 100 and the output signal of the optical relay unit 220 meet.

FIG. 3 is a diagram for explaining a high speed upload effect according to the noise removing function of FIG. 1. FIG. 3 illustrates a reason why a difference in reception capacity between a normal connection node and an access node having unwanted noise occurs in a mobile communication system occurs. have.

Taking a WCDMA mobile communication system as an example, the amount of power of a mobile terminal that a receiver of a connected node can accept is in the range of 10 dB from -105 dBm to -95 dBm, which is the maximum thermal noise level. Among them, the maximum amount of power that can be allocated to a data service is usually 6dB, ranging from -105dBm to -99dBm, although there are some differences. The reason is that the remaining 4dB range is a unique area of the voice call unconditionally allocated to the voice call. This is a specification of WCDMA that always attempts to ensure the minimum available voice call capacity. The manufacturer's recommended range of available receive power levels for data services in WCDMA is 6 to 7 dB.

In FIG. 3, the first case C10 is a connection node without unnecessary noise, and the second case C20 is a connection node in which unnecessary noise is increased by 3 dB and the available range of the data service is reduced to 3 dB. C30) is a connection node in which noise is increased by 6 dB and data service cannot be provided. In the real field, the effects of unnecessary noise from the repeater can be seen as a large reduction in transmission rates, as small as a few percent and as many as tens of percent. For example, even when a payload of a mobile terminal supporting a maximum speed of 2 Mbps is about 1100 kbps, only a transmission rate of 20 to 400 kbps can be obtained in a connection node having a receiver unnecessary noise of about 5 dB.

When using the relay 200, in order to prevent a phenomenon that the upload transmission speed of the data service is degraded as shown in the second or third case (C20, C30) due to the relay 200, one embodiment of FIG. As an example, by providing a variable attenuation value to remove the unwanted noise caused by the relay 200, it is possible to secure a normal upload transmission speed such as the first case (C10).

In this case, it will be necessary to consider whether the use of the attenuation circuit unit 130 does not affect the reception capacity (receive sensitivity) of the connection node 100. This is because when the attenuation circuit 130 is used, not only the noise but also the signal of the normal traffic received by radiating from the mobile terminal is equally reduced. The reception capacity is determined by the input stage noise index of the receiver for receiving and processing the radio signal and the signal-to-noise ratio required by the demodulation circuit (not shown) of the receiver.

Since the exemplary embodiment does not change the demodulation circuit, only the change in the noise figure of the receiver input terminal needs to be checked in order to confirm the change in the reception capacity of the connection node 100. The detailed confirmation process is as follows. As described with reference to FIG. 2, the low noise amplifier 120 and the optical relay 220 may be viewed in a form in which two amplifiers AMP1 and AMP2 are connected in parallel.

If the attenuation circuit unit 130 is used in front of an amplifier, the noise figure of the entire amplifier is increased by the amount of attenuation. However, when the attenuation circuit unit 130 is used at the rear end of the amplifier, the fluctuation value of the noise figure of the entire amplifier is smaller than the gain of the amplifier without reflecting the amount of attenuation of the attenuation circuit unit 130 as it is. Equations 1 to 3 illustrate the principle that the amount of change in the noise figure is reduced by the gain of the amplifier when the attenuation circuit unit 130 is mounted at the rear of the amplifier.

When the attenuation circuit unit 130 having the characteristics of Equation 2 is added to the low noise amplifier 120 having the characteristics of Equation 1, the noise figure is calculated as in Equation 3.

Gain = G (dB), G = 10 * log (g), g (mW),

Noise Figure = NF (dB), NF = 10 * log (F)

In Equation 1, Gain is the gain of the amplifier, Noise Figure is the noise figure of the amplifier, F is the noise factor of the amplifier.

Loss = -LF (dB),

Noise Figure = LF (dB), LF = 10 * log (L)

In Equation 2, Loss is an attenuation amount of the attenuation circuit unit 130, Noise Figure is a noise index value of the attenuation circuit unit 130, L is a noise factor of the attenuation circuit unit 130.

When the attenuation circuit unit 130 is added to the rear end of the low noise amplifier 120, the noise factor of the entire circuit is expressed by Equation 3, and the total noise index value using the same is expressed by Equation 4.

F _total = F ₁ + (F ₂ -1) / g ₁ = F ₁ + (L-1) / g ₁

In Equation 3, F _total is the total noise factor, F ₁ is the noise factor of the low noise amplifier 120, F ₂ is the noise factor of the attenuation circuit 130, g ₁ is the gain of the low noise amplifier 120, L is the amount of attenuation of the attenuation circuit section 130.

NF _total = 10 * log (F _total )

For example, when the attenuation circuit unit 130 having an attenuation amount of 3 dB is added, the change in the noise figure of the low noise amplifier 120 is calculated as follows. When the gain of the low noise amplifier 120 is 24dB and the noise figure is 2dB, in Equation 1, NF = 2dB, so F = 1.585. Since G = 24dB, g = 252.2. When the attenuation amount Loss of the attenuation circuit unit 130 connected to the rear end of the low noise amplifier 120 is -3dB and the noise figure is 3dB, in Equation 2, since LF = 3dB, L = 1.995. Applying this to Equations 3 and 4, the total noise factor (F _total ) is ＇F _total = 1.585+ (1.995-1) /252.5 = 1.59＇, and the total noise figure (NF _total ) is ＇NF _total = 10 * log (1.59) = 2.01 dB ＇.

That is, the influence of the noise index increase by the attenuation circuit unit 130 is reduced as much as the gain of the low noise amplifier 120. As a result, when a 3dB attenuation circuit 130 is added to the rear end of the low noise amplifier 120, the noise figure is changed by 0.01 dB and thus the noise figure of the low noise amplifier 120 in the connection node 100 receiver is changed. Is hardly changed, and therefore, the reception capacity of the connection node 100 does not decrease.

Since the noise increase due to the use of the optical repeater in the WCDMA is generally less than 5dB, the attenuation amount of the attenuation circuit 130 to be used for suppressing the noise increase may also be viewed as a maximum of 5dB. At this time, since the total noise of the low noise amplifier 120 in the connection node 100 is 2.02 dB and the amount of change is 0.02 dB, it is very insignificant, effectively reducing unnecessary noise caused by the relay 200 without changing the receiving capacity. Can be.

4 is a flowchart illustrating a noise removing method of a connection node device according to an embodiment of the present invention.

The connection node 100 receives radio waves radiated from the mobile terminal through the reception antenna 110 (S110). The low noise amplifier 120 receives the reverse signal received from the mobile terminal from the antenna 110 and performs low noise amplification thereto (S120).

While passing through the low noise amplifier 120, the low noise amplified reverse signal and the reverse signal received through the external relay 200 are merged at the front end of the attenuation circuit 130 (S130), and the attenuation circuit 130 is summed. The signal is input and attenuated and outputs the power level of the input signal (S140).

As described above, the attenuation amount adjustment may be performed through the attenuation circuit unit 130 composed of a variable resistor, and the attenuation circuit unit 130 may effectively attenuate the input signal by an increased noise value due to the external relay device 200. to be. The noise value for determining the attenuation amount of the attenuation circuit 130 may be measured directly in the field. Alternatively, a variable amount of attenuation may be derived and used by using the noise data of the connection node 100 receiver reported to the central control server (not shown) managing the connection node 100. When a plurality of relay devices 200 are used, the amount of noise increases as the number of relay devices 200 increases. One embodiment may automatically cope with an increase in the quantity of the relay apparatus 200 by setting an attenuation amount corresponding to the increased noise amount.

The amount of attenuation at step S140 is preferably 1/10 or less as compared to the gain at step S120. This is because limiting the use of only a small amount of attenuation significantly smaller than the gain of the low noise amplifier 120 (up to 1/10 level) can keep the increase of the noise figure at a minimal level. Since the noise increase due to the relay 200 is several dB level, such an application may be enabled.

In another embodiment, step S140 may be subdivided as shown in FIG. 5.

First, the attenuation amount adjusting unit 160 of the connection node 100 adjusts the attenuation amount step at a predetermined interval within a range of 0 dB to 5 dB (S141), and calculates a noise value every time the attenuation amount step is adjusted to obtain a noise value. It registers in the internal memory (S142).

Thereafter, the attenuation amount adjusting unit 160 compares the noise values calculated in step S142 with each other, selects the minimum noise value, searches for the optimum amount of attenuation used when calculating the selected minimum noise value in the memory (S143), and then searches for the optimum value. The attenuation amount is set to the attenuation amount of the attenuation circuit unit 130 (S144).

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

The present invention can be usefully applied to a mobile communication system.

According to the connected node device and the method of the present invention, while using the repeater in the mobile communication system to secure the effect of coverage expansion, economic efficiency and flexibility, while removing the noise generated by the repeater, the upload transmission rate due to noise generation And a reduction in reception capacity.

1 is a block diagram schematically illustrating a receiver of a connection node device according to an embodiment of the present invention.

FIG. 2 is a diagram for describing noise generation of FIG. 1.

FIG. 3 is a diagram for describing a fast upload effect according to the noise removing function of FIG. 1.

4 is a flowchart illustrating a noise removing method of a connection node device according to an embodiment of the present invention.

FIG. 5 is a flowchart of a part of the steps of FIG. 4.

Claims (10)

In the receiving unit of the connected node device for providing a mobile communication service, A receiving antenna for receiving radio waves radiated from the mobile terminal; A low noise amplifier for performing low noise amplification by receiving the reverse signal radiated from the mobile terminal through the receiving antenna; And Connection node device having a noise removing function including an attenuation circuit unit for receiving the sum signal of the external repeater connected in parallel with the low noise amplifier and the low noise amplifier, attenuating the power level of the input signal; . The method of claim 1, The attenuation circuit unit is a connection node device having a noise removing function, characterized in that the variable resistor is configured to adjust the amount of attenuation. The method of claim 1, And the attenuation circuit unit attenuates an input signal by an increase in noise value due to the external relay device. The method of claim 1, And the attenuation circuit section has attenuation amount of 1/10 or less in comparison with the gain of the low noise amplifier section. The method of claim 1, An attenuation amount adjusting unit controlling the process of adjusting the attenuation amount of the attenuation circuit part at a predetermined interval within a range of 0 dB to 5 dB to calculate an optimum amount of attenuation with the lowest noise value and setting the calculated optimum attenuation amount to the attenuation amount of the attenuation circuit part. Connection node device having a noise removal function further comprising. A noise removing method in a connection node device receiving unit providing a mobile communication service, Receiving a radio wave radiated from a mobile terminal through a receiving antenna (a); (B) performing low noise amplification on the reverse signal emitted from the mobile terminal; And And a step (c) of attenuating and outputting a power level of the input signal by receiving a sum signal of the reverse signal and the low noise amplified reverse signal received through an external relay device. The method of claim 6, Step (c) is the noise removing method of the connection node device, characterized in that made through a variable resistor configured to adjust the amount of attenuation. The method of claim 6, And in the step (c), attenuate the input signal by the noise value which is increased by the external relay device. The method of claim 6, The attenuation amount of step (c) is less than 1/10 of the amplification gain of the step (b) of the noise removal method of the connected node device. The method of claim 6, wherein step (c) comprises: Adjusting the attenuation amount steps at regular intervals within the range of 0 dB to 5 dB; Calculating a noise value each time the attenuation amount step is adjusted and storing the calculated noise value in a memory; Comparing the calculated noise values with each other to select a minimum noise value, and searching for an optimum amount of attenuation used when calculating the selected minimum noise value; And And setting the optimum amount of attenuation as an amount of attenuation and using the noise.

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