KR101567966B1 - Access node apparatus for noise reduction caused by optical repeater and method thereof - Google Patents

Abstract

A connection node apparatus and a method thereof having a noise canceling function due to an optical repeater are disclosed. The receiving node of the access node device for providing a mobile communication service includes a receiving antenna for receiving radio waves radiated from the mobile terminal and a reverse signal radiated from the mobile terminal through the receiving antenna to perform low noise amplification And an attenuation circuit for receiving the sum signal of the low-noise amplifier and the external repeater connected in parallel with the low-noise amplifier, and attenuating and outputting the power level of the input signal. According to such a configuration, it is possible to eliminate the noise caused by the use of the repeater in the mobile communication system, thereby preventing the decrease of the upload transmission rate and the reception capacity.

Optical repeater, base station, attenuator

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an access node device having a noise removing function due to an optical repeater,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an access node device and a method thereof for removing noise due to an optical repeater, and more particularly, The present invention relates to an access node device and a method for eliminating unnecessary noise generated and preventing a decrease in upload transmission rate caused by unnecessary noise.

In mobile communication networks, various repeaters are used to increase coverage at low cost. In particular, an optical repeater connected to a base station via an optical cable has a merit of providing coverage equal to that of a base station at a cost of 10 to 15% of the base station, and is widely used in a plurality of mobile communication networks.

However, the optical repeater has the advantage of providing high flexibility and flexibility to allow various networks to be constructed, and has the disadvantage of generating unnecessary noise in the base station receiver due to the installation of the optical repeater. The unnecessary noise increases according to the number of optical repeaters used. The increase of the noise increases the signal-to-noise ratio (S / N) of the signal arriving at the base station receiver, thereby reducing the reception capacity and coverage of the base station. It causes. In particular, data services have a greater impact than voice services. This is because the voice service requires only the transmission speed of 13 kbps in order to transmit a human voice, whereas the data service requires the maximum transmission speed.

Even if unnecessary noise is generated by the optical repeater in the base station receiving part, the capacity for providing services of about 13 kbps remains for several tens of persons. Therefore, even if the capacity is decreased due to a certain amount of unnecessary noise occurring in the base station receiving unit, the user hardly senses the quality degradation of the voice service.

However, in a data service, the higher the transmission rate, the faster the user can complete the data transmission in a short period of time. Therefore, the data service, in contrast to the voice service, provides the highest possible transmission rate to the user. Therefore, when the data service is provided, the base station gives the user the maximum remaining available capacity. Here, the available capacity refers to the maximum value of the power that the terminal can radiate toward the base station or the maximum value of the terminal power that can be received by the base station receiving unit.

In this case, since there is a difference in the amount of power that can be received by the base station between the base station in which unnecessary noise is present by the optical repeater and the base station in which there is no unnecessary noise, the difference is directly reflected in the quality of service The difference in transmission speed can be sensed.

As described above, when an optical repeater is used for the purpose of expanding coverage in providing a mobile communication service, unnecessary noise is generated in the base station receiving unit, and such unnecessary noise reduces the reception capacity and coverage of the base station and degrades the service quality .

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a mobile communication system in which noises due to a repeater are removed, thereby improving coverage, And to provide an access node apparatus and method therefor.

It is another object of the present invention to provide an access node apparatus and method for preventing a decrease in upload transmission speed by a repeater in a mobile communication system and securing a reception capacity and coverage by restoring a transmission rate to a state free of noise .

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not to be construed as limiting the invention as defined by the appended art. It will be possible.

A connection node apparatus having a noise canceling function according to the present invention includes: a receiving antenna for receiving radio waves radiated from a mobile terminal; A low noise amplifier for receiving a reverse signal emitted from the mobile terminal through the reception antenna and performing low noise amplification; And an attenuation circuit for receiving the sum signal of the low-noise amplifier and the external repeater connected in parallel with the low-noise amplifier, and attenuating and outputting the power level of the input signal.

Furthermore, the attenuation circuit unit may be constituted by a variable resistor to adjust the amount of attenuation.

Furthermore, the attenuation circuit portion may attenuate the input signal by an amount of noise that increases due to the external relay device.

Furthermore, the attenuation circuit unit may be configured to have an attenuation of 1/10 or less as compared with the gain of the low-noise amplifier.

Furthermore, by controlling the attenuation amount of the attenuation circuit part at a constant interval within the range of 0 dB to 5 dB, the optimum attenuation amount with the smallest noise value is calculated, and the calculated optimum attenuation amount is set as the attenuation amount of the attenuation circuit part And may further include an attenuation amount adjusting unit.

A noise removing method of a connected node device according to the present invention is a noise removing method in a receiving node unit for providing a mobile communication service, the method comprising: (a) receiving a radio wave radiated from a mobile terminal through a receiving antenna; (B) performing low noise amplification on the reverse signal emitted from the mobile terminal; And a step (c) of receiving a sum signal of the reverse signal received through the external relay device and the sum signal of the low noise amplified reverse signal to attenuate and output the power level of the input signal.

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

Further, in the step (c), the input signal may be attenuated by a noise value increased due to the external relay device.

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

Further, the step (c) may include adjusting an attenuation step at regular intervals within a range of 0 dB to 5 dB; Calculating a noise value every time the attenuation amount 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 optimal attenuation amount used when calculating the selected minimum noise value; And using the optimal attenuation amount as an attenuation amount.

According to the present invention, it is possible to eliminate noise due to a repeater in a mobile communication system, thereby ensuring coverage expansion, economical efficiency and flexibility improvement by using a repeater without degrading performance.

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

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a connection node apparatus and a method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

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

1, the access node device of the embodiment includes an antenna 110, a low-noise amplifier 120, an attenuation circuit 130, a transceiver 140, an analog-to-digital converter 150, do.

The receiving antenna 110 functions to receive a radio wave radiated from a user's mobile terminal. A reception filter for filtering the reverse signals received through the reception antenna 110 according to a detection condition and transmitting the filtered signals to a band-pass filter, a band-pass filter connected to the reception filter, Etc. may be located.

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

The attenuation circuit 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 the power level of the input signal. The attenuation circuit unit 130 is provided to attenuate the input signal by a noise value increased due to the external relay apparatus 200, and may be realized by a variable resistor so that attenuation can be controlled. In addition, the attenuation circuit unit 130 preferably has an attenuation of 1/10 or less as compared to the gain of the low-noise amplification unit 120.

At the rear end of the attenuation circuit unit 130, a transceiver unit 140, an analog-to-digital conversion unit 150, and the like are disposed. The transceiver unit 140 lowers the frequency of the signal received from the attenuation circuit unit 130 to an intermediate frequency (IF) band and smoothly samples the received signal in the analog-to-digital conversion unit 150 connected to the downstream do. In addition, the analog-to-digital converter 150 serves to digitize the analog signal by sampling the received signal to enable baseband processing.

In another embodiment, the access node 100 may further include an attenuation adjustment unit 160. [ The attenuation amount adjustment unit 160 adjusts the attenuation amount of the attenuation circuit unit 130 within a range of 0 dB to 5 dB to calculate the optimum attenuation amount with the smallest noise value and outputs the calculated optimum attenuation amount to the attenuation amount of the attenuation circuit unit 130 As shown in FIG. The attenuation amount adjustment unit 160 may be omitted according to the embodiment.

The relay apparatus 200 is for widening the service range of the access node 100 and is connected to the access node 100 by wire to receive traffic of the mobile node. The repeater 200 includes an antenna 210 for receiving a radio signal supplied from a mobile terminal and a light-weighted portion 220 at an output terminal. The light-weighted unit 220 provides the reverse signals received through the receiving antenna 210 to the receiving unit of the access node 100 through optical transmission.

The reverse loading of the access node 100 may be measured by a method to be described later and may be provided to a network controller such as an RNC (Radio Network Controller), an exchange, and the mobile terminal, . The reception noise value of the original access node 100 is a value at the standard position P10 but when the level of the signal is very low at the corresponding position and the module for level measurement is mounted at the corresponding position, The noise factor (NF) may increase and the reception sensitivity may be lowered. Therefore, the measurement of the reception level is made at the measurement position P20 where the signal is amplified and sufficiently strong, and the amplification rate between the standard position P10 and the measurement position P20 after measurement is subtracted from the measured value, The level of the signal to be measured is calculated. Thereafter, it is converted into the capacity used by the receiver of the access node 100.

For example, assuming a WCDMA mobile communication system, the noise level fluctuation may occur at a level of -95 to -105 dBm / 5 MHz when the traffic is highest and when the traffic is highest in the receiving part of the access node 100. That is, the reception capacity of the access node 100 starts to change from -105 dBm to a noise level of about 10 dB. If the noise value increases by about 3 dB due to the relay device 200 being connected thereto, the noise value change range of the access node 100 becomes -95 to -102 dBm / 5 MHz. Therefore, the available range is reduced to 7 dB, .

Therefore, in one embodiment, the noise value is attenuated by 3 dB by using the attenuation circuit unit 130 of 3 dB immediately after the point where the signals of the connection node 100 and the relay apparatus 200 are combined. In this case, a noise level of -105 dBm is again detected in the signal level sensor of the measurement position P20 for measuring the reception noise value, and no noise rise by the relay device 200 is detected. The available noise range at the access node 100 is restored to the original 10 dB. If the attenuation circuit unit 130 has a variable function capable of varying the amount of attenuation, it is possible to attenuate the increased amount of unnecessary noise by using different relay apparatuses for each connection node, .

FIG. 2 is a view for explaining noise generation in FIG. 1; FIG.

All amplifiers always output a certain level of noise power at the output stage, even if no input is provided. The noise value of the amplifier is defined as the 'thermal noise (dB) + noise figure of the amplifier (dB) + gain (dB)'. As shown in FIG. 2, when two such amplifiers AMP1 and AMP2 are connected in parallel, the noise value output is doubled (3dB). When expressed in dB scale, the noise figure of the amplifier + (dB) + gain (dB) + 3dB '. When the relay apparatus 200 is connected to the connection node 100, the relay apparatus 200 can be connected to the relay apparatus 200 in parallel connection with the low-noise amplification section 120 and the light- The noise power of the level of 'thermal noise (dB) + noise figure of the amplifier (dB) + gain (dB)' is output to the output terminal of the relay apparatus 200 even if no signal of the mobile terminal is inputted, .

As shown in FIG. 1, the low noise amplifier 120 is installed at the input of the receiver of the connection node 100. When the relay device 200 is installed, the low noise amplifier 120, The second and third amplifiers such as the first and second amplifiers are installed in parallel in the receiving section. The noise value increases as the number of relay apparatuses 200 used increases. As described above, the noise increase due to the use of the relay apparatus 200 deteriorates the signal-to-noise ratio of the reverse signal of the mobile terminal arriving at the receiver of the access node 100, thereby reducing the reception capacity and coverage of the access node 100 .

Accordingly, in order to improve the upload speed of the data service caused by the noise of the relay apparatus 200 input to the receiver of the access node 100, it is possible to perform variable attenuation in a proper position inside the receiver of the access node 100 The attenuation circuit unit 130 is provided to reduce unnecessary noise and to prevent the upload speed from being lowered due to the installation of the relay apparatus 200. [ The appropriate position of the attenuation circuit unit 130 is after the point at which the output signal of the light weight meter unit 220 meets the low noise amplifier unit 120 of the connection node 100. [

FIG. 3 is a diagram for explaining a high-speed upload effect according to the noise removing function of FIG. 1, illustrating a reason for a difference in reception capacity that can be accepted by a normal access node and an access node where unnecessary noise occurs in the mobile communication system have.

Taking the WCDMA mobile communication system as an example, the amount of power of the mobile terminal that can be received by the receiving unit of the access node is in the range of 10 dB from -105 dBm to -95 dBm, which is the maximum thermal noise level. Of these, the maximum amount of power that can be allocated to the data service is in the range of -6 dB, usually -105 dBm to -99 dBm, although there are some differences in some cases. The reason is that the remaining 4 dB range is a unique area of a voice call unconditionally assigned to a voice call. This is a standard of WCDMA to always secure a minimum voice call capacity. The manufacturer's available receive power level range recommendation for WCDMA data services is 6 to 7 dB.

3, the first case (C10) is an access node without unnecessary noise, the second case (C20) is an access node in which the range of available data service is reduced to 3dB by a noise increase of 3dB, and a third case C30) is an access node in which noise is increased by 6 dB and data service can not be provided. In an actual field, the influence of the occurrence of unnecessary noise due to the repeater may be as small as several percent and as large as a few tens of percent. For example, even if the payload of a mobile terminal supporting a maximum speed of 2Mbps is about 1100kbps, a transmission speed of 20-400kbps can be obtained only in an access node having a receiver noise level of about 5dB.

In order to prevent the transmission rate of the data service from lowering as shown in the second or third cases C20 and C30 due to the relay apparatus 200 when the relay apparatus 200 is used, By way of example, a normal attenuation rate, such as the first case C10, may be secured by removing the unnecessary noise due to the repeater 200 by giving a variable attenuation value.

In this case, it will be necessary to consider whether the use of the attenuation circuit unit 130 affects the reception capacity (reception sensitivity) of the access node 100. [ When the attenuation circuit unit 130 is used, not only the noise but also the signal of the normal traffic radiated from the mobile terminal is also reduced. The reception capacity is determined by the input stage noise figure of the receiver for receiving and processing the radio signal and the signal-to-noise ratio required by the demodulation circuit (not shown) at the final stage of the receiver.

In one embodiment, since no change is made to the demodulation circuit unit, only the change of the noise figure value at the input of the receiving unit may be confirmed in order to confirm the change of the receiving capacity of the connection node 100. [ The detailed procedure is as follows. As shown in FIG. 2, the low-noise amplifying unit 120 and the light amplifying unit 220 can be viewed as two amplifiers AMP1 and AMP2 connected in parallel.

If the attenuation circuit 130 is used in front of a certain 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 downstream stage of the amplifier, the noise figure value change of the entire amplifier becomes smaller by the gain of the amplifier than the attenuation amount of the attenuation circuit unit 130. Equations (1) to (3) explain the principle in which the variation of the noise figure value is reduced by the gain of the amplifier when the attenuation circuit unit 130 is mounted at the rear end of the amplifier.

When the attenuation circuit unit 130 having the characteristic of Equation (2) is added to the low-noise amplifier unit 120 having the characteristics as in Equation (1), the noise figure value is calculated as 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, and F is the noise factor of the amplifier.

Loss = -LF (dB),

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

In Equation (2), Loss is the attenuation amount of the attenuation circuit unit 130, Noise Figure is the noise figure value of the attenuation circuit unit 130, and L is the noise factor of the attenuation circuit unit 130.

When the attenuation circuit unit 130 is added to the downstream of the low-noise amplifying unit 120, the noise factor of the entire circuit is represented by Equation (3), and the total noise figure value using 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 amplification unit 120, F ₂ is the noise factor, g ₁ of attenuation circuit 130 is a gain of the low noise amplifier 120, And L is the attenuation amount of the attenuation circuit unit 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 variation of the noise figure value of the low noise amplification unit 120 is calculated as follows. In the case where the gain of the low-noise amplifier 120 is 24 dB and the noise figure is 2 dB, F = 1.585 since NF = 2 dB in Equation (1). Since G = 24 dB, g = 252.2. When the attenuation amount Loss of the attenuation circuit unit 130 connected to the rear end of the low noise amplifier unit 120 is -3 dB and the noise figure is 3 dB, L = 1.995 since LF = 3 dB in Equation 2. Applying this to equation (3) and equation (4) the overall noise factor (F _{total) is' F total = 1.585+ (1.995-1)} /252.5 = 1.59 ' , and the overall noise figure value (NF _total) is' NF _total = 10 * log (1.59) = 2.01 dB '.

That is, the increase of the noise figure by the attenuation circuit unit 130 is less affected by the gain of the low-noise amplifier unit 120. [ If the 3 dB attenuation circuit unit 130 added to the rear end of the low noise amplifying unit 120 is added, the change in the noise figure is 0.01 dB, which is the noise figure of the low noise amplifying unit 120 in the receiving unit 100 So that the reception capacity of the access node 100 does not decrease.

Since the noise increase due to the use of the optical repeater in WCDMA is generally less than 5dB at maximum, the attenuation of the attenuation circuit 130 used to suppress the noise increase can be seen as a maximum of 5dB. At this time, the total noise of the low-noise amplifier 120 in the connection node 100 is 2.02 dB, which is 0.02 dB, which is very small. Therefore, unnecessary noise due to the repeater 200 can be effectively reduced without changing the receiving capacity .

4 is a flowchart illustrating a noise removal method of a connection node apparatus according to an exemplary embodiment of the present invention.

The access node 100 receives the radio wave radiated from the mobile terminal through the receive 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 on the received reverse signal (S120).

The low noise amplified reverse signal while passing through the low noise amplifying unit 120 and the reverse signal received through the external relay apparatus 200 are combined at the front end of the attenuation circuit unit 130 at step S130, Receives the signal, attenuates the power level of the input signal, and outputs the attenuated signal (S140).

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

The attenuation amount in step S140 is preferably 1/10 or less as compared with the amplification gain in step S120. It is possible to limit the increase of the noise figure to a negligible level by restricting the use of only a considerably small amount of attenuation (about 1/10 of the level) compared to the gain of the low noise amplifier 120. This increase in noise due to the repeater 200 can be several dB, which makes this application possible.

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

First, the attenuation amount adjustment unit 160 of the access node 100 adjusts the attenuation amount step at a constant interval within the range of 0 dB to 5 dB (S141), calculates the noise value every time the attenuation amount step is adjusted, In the internal memory (S142).

Thereafter, the attenuation amount adjustment unit 160 selects the minimum noise value by comparing the noise values calculated in step S142 with each other, searches for the optimal attenuation amount used when calculating the minimum noise value selected in the memory (S143) The attenuation amount is set as the attenuation amount of the attenuation circuit unit 130 (S144).

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

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 is applicable to a mobile communication system.

According to the access node apparatus and method of the present invention, it is possible to secure the effect of expansion of coverage, economical efficiency and flexibility through use of a repeater in a mobile communication system, and also eliminates noise caused by a repeater, And reduction in the reception capacity can be prevented.

1 is a block diagram schematically illustrating a receiving unit of a connection node apparatus according to an embodiment of the present invention.

FIG. 2 is a view for explaining noise generation in FIG. 1; FIG.

3 is a diagram for explaining a high-speed upload effect according to the noise removing function of FIG.

4 is a flowchart illustrating a noise removal method of a connection node apparatus according to an exemplary embodiment of the present invention.

Figure 5 is a flow chart detailing the steps of Figure 4;

Claims (10)

A connection node apparatus for providing a mobile communication service, A receiving antenna for receiving a reverse signal emitted from a mobile terminal; A low noise amplifier for receiving the reverse signal and performing low noise amplification; And An attenuating unit that receives a sum signal of a low-noise amplified reverse signal from the low-noise amplifying unit and a sum signal of an inverse signal received from an external relay apparatus connected in parallel with the low-noise amplifying unit to attenuate a power level of the summation signal to attenuate noise A connection node apparatus having a noise removing function including a circuit section. The method according to claim 1, Wherein the attenuation circuit unit is configured as a variable resistor to adjust the amount of attenuation. The method according to claim 1, Wherein the attenuation circuit unit attenuates the input signal by an amount of noise that increases due to the external relay apparatus. The method according to claim 1, Wherein the attenuation circuit unit has an attenuation of 1/10 or less as compared to a gain of the low-noise amplifying unit. The method according to claim 1, An attenuation amount adjustment unit that adjusts the attenuation amount of the attenuation circuit unit at a predetermined interval within a range of 0 dB to 5 dB to calculate an optimum attenuation amount with the smallest noise value and sets the calculated optimal attenuation amount as the attenuation amount of the attenuation circuit unit; Further comprising a noise removal function. A method for noise reduction in an access node device receiving section for providing a mobile communication service, (A) receiving a reverse signal emitted from a mobile terminal via a receive antenna; Performing (b) low noise amplification on the reverse signal; And (C) receiving a sum signal of the reverse signal received through an external relay device and the sum signal of the low noise amplified reverse signal to attenuate noise by attenuating a power level of the sum signal, . delete delete delete The method of claim 6, wherein the step (c) Adjusting the attenuation step at regular intervals within the range of 0 dB to 5 dB; Calculating a noise value every time the attenuation amount 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 optimal attenuation amount used when calculating the selected minimum noise value; And And using the optimal attenuation amount as an attenuation amount.

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