JP4919994B2 - Communication apparatus and communication method - Google Patents

Description

  The present invention relates to a communication device and a communication method.

Conventionally, for example, a base station apparatus (also referred to as a first communication apparatus) and a mobile station apparatus (also referred to as a second communication apparatus) that perform signal transmission / reception in a mobile communication system of CDMA (Code Division Multiple Access) system. ) Performs transmission power control as follows.
The base station apparatus measures a desired wave-to-interference wave and a noise power ratio (received SIR: Signal to Interference plus noise power Ratio) with respect to the received signal from the mobile station apparatus, and transmits based on the difference between the received SIR and the target SIR. Generate power control bits.
The base station apparatus transmits the transmission power control bit to the mobile station apparatus, and the mobile station apparatus controls the transmission power in the own station based on the transmission power control bit.

In Patent Document 1, transmission power information of a mobile station device is determined based on a propagation loss of a radio wave transmission path between the base station device and the mobile station device, and transmitted regardless of power control information from the mobile station device. A technique for controlling power is described.
JP 2006-262502 A

  However, in the conventional technology, the transmission power of a signal transmitted from the mobile station apparatus to the base station apparatus is determined based on either transmission power information determined by the base station apparatus or transmission power information determined by the mobile station apparatus. Therefore, there is a problem that the transmission power of the mobile station device cannot be determined based on the communication environment of both the base station device and the mobile station device.

  The present invention has been made in view of the above circumstances, and an object thereof is to determine the transmission power of the second communication device based on the communication environment of both the first communication device and the second communication device. It is an object of the present invention to provide a communication device and a communication method that can perform communication.

(1) The present invention has been made to solve the above problems, and a communication device according to an aspect of the present invention is a second communication device that communicates with a first communication device, wherein the first communication device is the first communication device. A transmission power control value receiving unit that receives a first transmission power control value from a communication device, and a transmission power that calculates a second transmission power control value based on a propagation loss of a signal transmitted from the first communication device. a control value calculation unit, transmission power the the second transmission power control value by multiplying a weight coefficient corresponding to the first transmission power control value, to determine a third transmission power control value by using the multiplication result A control value determination unit, and a transmission unit that transmits a signal to the first communication device using the third transmission power control value , wherein the transmission power control value determination unit includes the first transmission power. If the fluctuation range within a predetermined time for the control value is greater than the first threshold, The weighting factor is made smaller than when the fluctuation range is smaller than the first threshold value .

(2) In addition, the transmission power control value determination unit of the second communication apparatus according to an aspect of the present invention has a second difference between the first transmission power control value and the second transmission power control value. If it is larger than the threshold, the weighting factor is changed .

(3) In addition, the transmission power control value determination unit of the second communication apparatus according to an aspect of the present invention may be configured such that the fluctuation range of the first transmission power control value is a predetermined number of times greater than or equal to a first threshold. The weight coefficient is changed .

(4) In addition, the transmission power control value determination unit of the second communication device according to an aspect of the present invention changes the weighting factor stepwise .

(5) In addition, the transmission power control value determination unit of the second communication device according to one aspect of the present invention has a variation width within a predetermined time of the first transmission power control value smaller than a third threshold. The weighting factor is returned to the initial value .

(6) In addition, the transmission power control value determination unit of the second communication device according to an aspect of the present invention has a fourth difference between the first transmission power control value and the second transmission power control value. If it is smaller than the threshold, the weighting factor is returned to the initial value .

(7) In addition, the transmission power control value determination unit of the second communication device according to an aspect of the present invention may be configured such that the fluctuation range of the first transmission power control value is a predetermined number of times less than or equal to a fifth threshold. The weighting factor is returned to the initial value .

(8) In addition, the transmission power control value determination unit of the second communication device according to an aspect of the present invention returns the weighting factor to the initial value stepwise over time .

(9) A communication method according to an aspect of the present invention is a communication method using a second communication device that communicates with a first communication device, and performs first transmission power control from the first communication device. A transmission power control value reception process for receiving a value, a transmission power control value calculation process for calculating a second transmission power control value based on a propagation loss of a signal transmitted from the first communication apparatus, and the second A transmission power control value determination step of multiplying the transmission power control value of the second transmission power control value by a weighting factor corresponding to the first transmission power control value and determining a third transmission power control value using the multiplication result; A transmission step of transmitting a signal to the first communication apparatus using a transmission power control value, and in the transmission power control value determination step, a fluctuation range within a predetermined time for the first transmission power control value Is greater than the first threshold, the fluctuation range within the predetermined time is The weighting factor is made smaller than when the threshold value is smaller than 1 .

  In the communication apparatus and the communication method of the present invention, the transmission power of the second communication apparatus can be determined based on the communication environments of both the first communication apparatus and the second communication apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A communication system according to an embodiment of the present invention includes a base station device (also referred to as a first communication device) and a mobile station device (also referred to as a second communication device).
The mobile station apparatus controls the transmission power based on the transmission power control information transmitted from the base station apparatus and the propagation loss of the received signal.
Uplink transmission power P, which is power used when transmitting a signal from the mobile station apparatus to the base station apparatus, is calculated by the following equation (1).

P ₀ is set by the base station apparatus with reference transmission power. α is a coefficient (0 <α ≦ 1) set by the base station apparatus. PL is a downlink propagation loss from the base station apparatus to the mobile station apparatus, and is determined by the mobile station apparatus itself from the downlink received signal.
β is a coefficient in the range of 0 <α × β ≦ 1, and the mobile station apparatus determines an optimum value. f (delta_i) is power control by a closed loop, and power is increased or decreased by an arbitrary width by a transmission power control bit transmitted from the base station apparatus.
delta_mcs is transmission power determined by a modulation scheme, a coding rate, a bandwidth, or the like.

When the base station device receives a transmission signal from the mobile station device, and the base station device measures the received power of the received signal and determines that the received power is larger than the received power desired by the base station device, To transmit a transmission power control bit for instructing to lower the transmission power.
When the received power is smaller than the desired reception power, the transmission power control bit for instructing the mobile station device to increase the transmission power is transmitted. The mobile station apparatus receives the transmission power control bit and controls the transmission power in accordance with an instruction from the base station apparatus.

For power control based on propagation loss, the mobile station device performs transmission power control based on downlink propagation loss when the mobile station device receives a signal for measuring propagation loss from the base station device.
For example, the base station apparatus transmits a downlink signal such as a reference signal to the mobile station apparatus, and the transmission power value of the reference signal is notified from the base station apparatus to the mobile station apparatus in advance.
The mobile station apparatus measures the received power of the reference signal from the base station apparatus, and obtains the propagation loss of the downlink received signal from the received power measurement value and the previously transmitted transmission power value.

  For power control based on propagation loss, the mobile station device transmits a reference signal for measuring propagation loss at all times or by transmitting from the base station device at an arbitrary time interval or frequency interval. Propagation loss according to the environment can be obtained, and transmission power control according to changes in the radio wave environment becomes possible.

Since the power can be increased or decreased by the determination of the mobile station apparatus, it is possible to immediately cope with a change in the radio wave environment without waiting for reception of the transmission power control bit from the base station apparatus. However, when the upstream transmission frequency and the downstream reception frequency are different, the radio wave environment is not always the same, so optimal power control cannot be performed only by power control based on the propagation loss of the downstream reception signal. is there.
On the other hand, in the case of control based on the transmission power control bit transmitted from the base station device, since the mobile station device controls after receiving the control signal from the base station device, However, there is a time difference with respect to changes in the radio wave environment.

In addition, by shortening the interval at which the base station device transmits the transmission power control bit, the time difference with respect to changes in the radio wave environment can be shortened, but the amount of user data that can be transmitted decreases because the amount of control bit data increases. As a result, the throughput decreases.
Based on the above, transmission power control based on propagation loss and power control based on transmission power control bits from the base station apparatus are combined to reduce power consumption and reduce delay with respect to changes in the radio wave environment. Control can be realized.

In such transmission power control, it is conceivable that the increase / decrease in power control desired by the mobile station apparatus and the increase / decrease in power control desired by the base station apparatus are in opposite directions. When the uplink and downlink transmission frequencies are different, the radio wave environment is not exactly the same, so that the increase / decrease in power control desired by the mobile station apparatus and the increase / decrease in power control desired by the base station apparatus may be reversed.
In addition, the mobile station apparatus wants to increase power from the downlink propagation loss, but the base station apparatus wants to reduce the power of the mobile station apparatus in consideration of the influence on other terminals or other cells. The increase / decrease of the power control is reversed.

  In such a case, the transmission power of the mobile station apparatus cannot be controlled without considering the transmission power instruction from the base station apparatus. Therefore, the transmission power control based on the transmission power control bits is made smaller in the transmission power control weight based on the downlink propagation loss, thereby reducing the gap between the control desired by the base station apparatus and the control desired by the mobile station apparatus. can do.

(First embodiment)
Next, a communication system according to the first embodiment of the present invention will be described. This communication system includes a base station device and a mobile station device.

  FIG. 1 is a schematic block diagram showing a configuration of a mobile station apparatus 100 according to the first embodiment of the present invention. The mobile station apparatus 100 includes an antenna 10, a radio transmission unit 11 (also referred to as a transmission unit), a transmission power control unit 12 (also referred to as a transmission power control value determination unit), a transmission power control bit extraction unit 13, and a radio reception unit 21 ( And a transmission loss control unit 22 (also referred to as a transmission power control value calculation unit).

The transmission power control bit extraction unit 13 extracts transmission power control bits from the received signal (data). The propagation loss calculator 22 obtains the propagation loss from the difference between the received power of the received signal and the information of the transmission power control bit transmitted by the base station apparatus.
The transmission power control unit 12 generates a transmission power control signal from the transmission power control bit information extracted by the transmission power control bit extraction unit 13 and the propagation loss information obtained by the propagation loss calculation unit 22. The wireless transmission unit 11 transmits data with the transmission power instructed by the transmission power control signal from the transmission power control unit 12.
For example, the following equation (2) is used as a method for determining the transmission power in the transmission power control unit 12.

P is transmission power when transmitting a signal from the mobile station apparatus 100 to the base station apparatus. P ₀ is determined by the base station apparatus with reference transmission power, and the setting value is transmitted using, for example, a control channel from the base station apparatus. PL is a downlink propagation loss, and is determined by the mobile station device 100 itself using a downlink received signal.

α is determined by the base station apparatus with a coefficient (0 <α ≦ 1), and the setting value is transmitted to the mobile station apparatus 100 using, for example, a control channel from the base station apparatus.
β is a coefficient of 0 ≦ β, and the mobile station device 100 determines an optimum value. f (delta_i) is power control by a closed loop, and power is increased or decreased by an arbitrary width by a transmission power control bit transmitted from the base station apparatus.
This transmission power control bit is transmitted to the mobile station apparatus 100 using, for example, a control channel from the base station apparatus.
delta_mcs is transmission power determined by a modulation scheme, a coding rate, a bandwidth, or the like.

FIG. 2 is a flowchart showing processing of the mobile station apparatus 100 according to the first embodiment of the present invention.
First, the mobile station device 100 receives transmission power control information from the base station device (step S01).
Then, the mobile station device 100 obtains a transmission power fluctuation range from the transmission power control bits included in the transmission power control information received in step S01 (step S02).
And the mobile station apparatus 100 sets transmission power with the transmission power control bit contained in the transmission power control information received by step S01 (step S03).

Then, the mobile station device 100 determines whether or not the variation range of the transmission power obtained in step S02 is larger than the threshold (step S04).
If the fluctuation range of the transmission power is larger than the threshold, the mobile station apparatus 100 determines “Yes” in step S04, corrects the propagation loss, and performs transmission power control based on the corrected propagation loss (step S05). .
On the other hand, when the fluctuation range of the transmission power is less than or equal to the threshold, the mobile station device 100 determines “No” in step S04, and performs transmission power control based on the propagation loss (step S06).

  In FIG. 2, steps S01 to S03 indicate power control using a transmission power control signal from the base station apparatus. Steps S04 to S06 indicate transmission power control based on propagation loss.

  FIG. 3 is a graph showing an example of the relationship between time and propagation loss (PL) according to the first embodiment of the present invention. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates propagation loss (PL).

  Here, a case will be described in which transmission power control bits transmitted from the base station apparatus to mobile station apparatus 100 are transmitted at time T intervals. Also, a case will be described in which the power control bit is 2 bits and the transmission power fluctuation range by the power control bit is −4 dB, −1 dB, +1 dB, and +4 dB.

  In FIG. 3, the propagation loss (PL) decreases linearly from p2 to p1 from time 0 to time 3T. Further, after time 3T, the propagation loss (PL) decreases linearly from p1 to p0.

FIG. 4 is a graph showing an example of the relationship between time and transmission power (P) by a conventional mobile station apparatus. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates transmission power (P).
Here, since the propagation loss (PL) required by the mobile station apparatus has decreased, the mobile station apparatus attempts to reduce the transmission power.
At time T, the transmission power of the mobile station apparatus is sufficiently small with respect to the transmission power a1 (transmission power target) requested from the base station apparatus to the mobile station apparatus. The base station apparatus instructs to increase the transmission power.
The base station apparatus instructs the transmission power to be increased by the transmission power control bit until it is determined that the transmission power target has been reached.

  In this way, even if the target of transmission power is larger than the transmission power at that time, the mobile station device attempts to lower the transmission power because the propagation loss (PL) is reduced. It takes extra time to reach the target power.

  FIG. 5 is a graph illustrating an example of a relationship between time and transmission power (P) by the mobile station apparatus 100 according to the first embodiment of the present invention. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates transmission power (P).

Here, the initial weight coefficients α and β are set to α = 1 and β = 1. Then, when the fluctuation range of the transmission power by the transmission power control bit is 4 dB or more, β is set to 0.5.
Since the transmission power of mobile station apparatus 100 is sufficiently small with respect to the transmission power target (transmission power (P) = b1) at time T, it is instructed to increase +4 dB power to mobile station apparatus 100 by the transmission power control bit. .
From time 0 to T, the mobile station apparatus 100 controls transmission power in conjunction with fluctuations in propagation loss (PL) by setting α = 1 and β = 1. In response to the transmission power control bit from the base station apparatus at time T, the mobile station apparatus 100 increases the transmission power by 4 dB.

Here, the mobile station apparatus 100 sets the weighting coefficient β to 0.5 because the fluctuation range of the transmission power according to the power control instruction from the base station apparatus is 4 dB or more, and the propagation loss from time T to time 2T. The fluctuation range of transmission power due to (PL) is reduced.
Even at time 2T, since the transmission power of the mobile station device 100 is still sufficiently small with respect to the target of the transmission power, the base station device instructs to increase 4 dB power. The mobile station apparatus 100 receives the transmission power control bit, increases the transmission power by 4 dB, and continuously sets the value of the weight coefficient β to 0.5 until time 3T.

Since the transmission power target is slightly smaller at time 3T, the base station apparatus instructs the mobile station apparatus 100 to increase the transmission power by 1 dB. Here, since the fluctuation range of the transmission power due to the transmission power control bit is 4 dB or less, the mobile station apparatus 100 sets the value of the weighting coefficient β to 1.0 and sets it.
Thereafter, the weighting coefficient β is set to 1.0 until the fluctuation width by the transmission power control bit becomes 4 dB or more, and transmission power is controlled in conjunction with the propagation loss (PL).

  In this way, by changing the setting value of the weighting factor β according to the control power width of the transmission power by the transmission power control bit, the fluctuation range of the transmission power control by the measured value of the downlink propagation loss can be changed, and the uplink and downlink Even when the increase / decrease direction of the transmission power control is different between the base station apparatus and the mobile station apparatus 100 due to the difference in the radio wave environment, optimal transmission power control can be performed.

  In the first embodiment of the present invention, the radio reception unit 21 receives transmission power control information (also referred to as a first transmission power control value) from the base station apparatus, and the propagation loss of the signal transmitted from the base station apparatus Based on this, the transmission loss control unit 22 calculates the transmission power control value (second transmission power control value), multiplies the second transmission power control value by the weighting factor β, and the multiplication result and the first transmission power control. The transmission power control unit 12 determines a third transmission power control value using the value, and the radio transmission unit 11 transmits a signal to the base station apparatus using the third transmission power control value. 12, the following processing may be performed.

For example, the transmission power control unit 12 may change the weighting coefficient β when the fluctuation width within a predetermined time for the first transmission power control value is larger than the first threshold.
In addition, the transmission power control unit 12 may change the weighting factor β when the difference between the first transmission power control value and the second transmission power control value is larger than the second threshold value.

In addition, the transmission power control unit 12 may change the weighting factor β when the fluctuation range of the first transmission power control value reaches a predetermined number of times greater than or equal to the first threshold value.
Further, the transmission power control unit 12 may change the weighting factor β step by step.

Further, the transmission power control unit 12 may return the weighting coefficient β to the initial value when the fluctuation width within a predetermined time for the first transmission power control value is smaller than the third threshold value.
Further, the transmission power control unit 12 may return the weighting factor β to the initial value when the difference between the first transmission power control value and the second transmission power control value is smaller than the fourth threshold value. .

Further, the transmission power control unit 12 may return the weighting coefficient β to the initial value when the fluctuation range of the first transmission power control value reaches a predetermined number of times below the fifth threshold value.
Further, the transmission power control unit 12 may return the weighting coefficient β to the initial value stepwise as time elapses.

For example, in the above example, the value of the weighting factor β is 1.0 and 0.5. For example, when the fluctuation range of the transmission power due to the transmission power control bit is continuously larger than the threshold value, The value may be changed stepwise from 1.0 → 0.7 → 0.5.
Also, when it becomes smaller than the threshold value, it may be returned in steps such as 0.5 → 0.7 → 1.0 instead of returning from 0.5 to 1.0.

In the above example, the value of the weighting factor β is changed when the transmission power fluctuation range due to the transmission power control bit becomes larger than the threshold value. However, when the fluctuation width becomes larger than the threshold value continuously several times. The value of the weight coefficient β may be changed.
Further, the value of the weighting coefficient β is changed when the fluctuation width becomes smaller than the threshold value, but when the fluctuation width becomes smaller than the threshold value for a plurality of times continuously, the value of the weighting coefficient β is returned to the initial value. You may do it.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This communication system includes a base station device and a mobile station device. Since the configurations of the base station apparatus and the mobile station apparatus are the same as those in the first embodiment, description thereof will be omitted, and only differences from the first embodiment will be described below.

  The mobile station apparatus by 2nd Embodiment determines transmission power using the following formula | equation (3).

  Here, β is an arbitrary coefficient, and the mobile station apparatus sets an optimum value. For example, when α = 1 and β = 0 at the initial stage, when the fluctuation range of the transmission power due to the transmission power control bit becomes larger than a certain threshold, the transmission power due to propagation loss (PL) is set by setting β = 0.5. , And when the fluctuation width becomes smaller than the threshold value, β = 0 is returned.

  In this way, by changing the setting value of the weighting factor β according to the control power width of the transmission power by the transmission power control bit, the fluctuation range of the transmission power control by the measured value of the downlink propagation loss can be changed, and the uplink and downlink Even when the increase / decrease direction of the transmission power control is different between the base station apparatus and the mobile station apparatus due to the difference in the radio wave environment, the optimum transmission power control can be performed.

In the above example, the value of the weighting factor β is set to 0 and 0.5. However, for example, when the fluctuation range of the transmission power due to the transmission power control bit is continuously larger than the threshold value, the value of the weighting factor β is changed from 0 to The value may be changed stepwise, such as 0.4 → 0.3 → 0.2 or 0 → 0.1 → 0.2 → 0.3.
Also, when the value becomes smaller than the threshold value, the value of the weighting coefficient β may be returned in stages such as 0.5 → 0.3 → 0 instead of returning from 0.5 to 0.

In addition, it is possible to control the transmission power of the mobile station apparatus by combining the first embodiment and the second embodiment, and by making it compatible with both transmission power control methods, It can cope with various radio wave environments.
Although the transmission power control method of the mobile station apparatus has been described in the first embodiment and the second embodiment, the base station apparatus can also cope with the same transmission power control method.

  In the embodiment described above, a program for realizing the functions of the respective units of the base station apparatus and the mobile station apparatus is recorded on a computer-readable recording medium, and the program recorded on the recording medium is stored in the computer system. The base station apparatus and the mobile station apparatus may be controlled by reading and executing. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, it is also assumed that a server that holds a program for a certain time, such as a volatile memory inside a computer system that serves as a server or client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

It is a schematic block diagram which shows the structure of the mobile station apparatus 100 by the 1st Embodiment of this invention. It is a flowchart which shows the process of the mobile station apparatus 100 by the 1st Embodiment of this invention. It is a graph which shows an example of the relationship between the time by the 1st Embodiment of this invention, and propagation loss (PL). It is a graph which shows an example of the relationship between the time by the mobile station apparatus of a prior art, and transmission power (P). It is a graph which shows an example of the relationship between the time by the mobile station apparatus 100 of the 1st Embodiment of this invention, and transmission power (P).

Explanation of symbols

10 ... Antenna,
11 ... wireless transmission unit,
12: Transmission power control unit,
13: Transmission power control bit extraction unit,
21: Wireless receiver,
22 ... propagation loss calculation unit,
100: Mobile station apparatus

Claims (9)

A second communication device for communicating with the first communication device,
A transmission power control value receiving unit for receiving a first transmission power control value from the first communication device;
A transmission power control value calculation unit that calculates a second transmission power control value based on a propagation loss of a signal transmitted from the first communication device;
A weighting factor corresponding to the first transmission power control value by multiplying said second transmission power control value, the transmission power control value determining unit for determining a third transmission power control value by using the multiplication result,
A transmitter that transmits a signal to the first communication device using the third transmission power control value;
Equipped with a,
The transmission power control value determination unit, when the variation width within a predetermined time for the first transmission power control value is larger than a first threshold, than when the variation width within a predetermined time is smaller than the first threshold, The second communication apparatus, wherein the weighting factor is reduced .   The transmission power control value determination unit changes the weighting factor when a difference between the first transmission power control value and the second transmission power control value is larger than a second threshold. The second communication device according to claim 1.   The transmission power control value determination unit changes the weighting factor when the fluctuation range of the first transmission power control value reaches a predetermined number of times greater than or equal to a first threshold value. The second communication device. 4. The second communication device according to claim 2, wherein the transmission power control value determining unit changes the weighting factor in a stepwise manner. 5. The transmission power control value determination unit returns the weighting factor to an initial value when a fluctuation range within a predetermined time for the first transmission power control value is smaller than a third threshold. The second communication device according to any one of items 4 to 4 . The transmission power control value determination unit returns the weighting factor to an initial value when a difference between the first transmission power control value and the second transmission power control value is smaller than a fourth threshold value. The second communication device according to any one of claims 2 to 4 . The transmission power control value determination unit is configured to return the weighting factor to an initial value when a fluctuation range of the first transmission power control value reaches a predetermined number of times below a fifth threshold value. The second communication device according to any one of items 4 to 4 . The transmission power control value determining unit, the second communication device according to any one of claims 5 to 7, characterized in that back stepwise to the initial value of the weighting factor as time elapses. A communication method using a second communication device that communicates with a first communication device,
A transmission power control value receiving process for receiving a first transmission power control value from the first communication device;
A transmission power control value calculation step of calculating a second transmission power control value based on a propagation loss of a signal transmitted from the first communication device;
A weighting factor corresponding to the first transmission power control value by multiplying said second transmission power control value, and a third transmission power control value determining process of determining the transmission power control value by using the multiplication result,
A transmission process of transmitting a signal to the first communication device using the third transmission power control value;
I have a,
In the transmission power control value determination process, when the fluctuation width within a predetermined time for the first transmission power control value is larger than the first threshold, the fluctuation width within the predetermined time is smaller than the first threshold. A communication method characterized by reducing the weighting factor .

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