KR101610050B1 - System of D2D communication based power control and Method for power control using the same - Google Patents

System of D2D communication based power control and Method for power control using the same Download PDF

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KR101610050B1
KR101610050B1 KR1020150065318A KR20150065318A KR101610050B1 KR 101610050 B1 KR101610050 B1 KR 101610050B1 KR 1020150065318 A KR1020150065318 A KR 1020150065318A KR 20150065318 A KR20150065318 A KR 20150065318A KR 101610050 B1 KR101610050 B1 KR 101610050B1
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terminal
sinr
increase
power
rate
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KR20150144269A (en
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신요안
오선애
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숭실대학교산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H04W52/241—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/06—TPC algorithms
    • H04W52/10—Open loop power control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H04W52/242—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters taking into account path loss
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H04W52/243—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters taking into account interferences

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Abstract

The present invention relates to a power control based D2D communication system and a power control method thereof.
According to the power control based D2D communication system and the power control method thereof, in the LTE-Advanced based D2D communication system including a plurality of D2D terminals, the D2D terminal calculates a current signal-to- And a noise ratio (SINR) value to a reference SINR value, and if the current SINR value is smaller than the reference SINR value, an increase rate of the SINR when the current transmission power of the D2D terminal is increased by a unit power, And a controller for increasing the current transmission power of the D2D terminal by the unit power if the rate of increase of the SINR is greater than the rate of increase of the interference.
As described above, according to the present invention, by combining the LTE uplink open loop power control scheme and the interference-based power control scheme, the performance of the cellular terminal is guaranteed to be higher than the target value and the performance of the D2D terminal is improved, Not only can the transmission power be adjusted to reduce unnecessary power consumption.

Description

TECHNICAL FIELD [0001] The present invention relates to a power control based D2D communication system and a power control method thereof,

The present invention relates to a power control based D2D communication system and a power control method thereof, and more particularly, to a power control based D2D communication system and a power control method thereof, which are capable of adaptively adjusting transmission power in order to improve performance of a D2D terminal, To a D2D communication system and a power control method thereof.

Device-to-device communication is based on physical proximity between terminals, and is a technique for directly communicating without the assistance of a base station. Figure 1 shows D2D communication based on proximity between existing cellular communications and terminal dependent on base stations.

As shown in FIG. 1, the D2D terminals UE3 and UE4, which do not communicate with the cellular terminals UE1 and UE2 that are in the cellular communication and do not communicate with the base station eNB, coexist within the coverage of the base station eNB, It is widely used as a solution to the recent problems.

In other words, D2D communication has many advantages in terms of increase of resource efficiency of the network, power consumption of the terminal, and expansion of the cellular communication area, compared to a method of communicating through the existing cellular network infrastructure. In D2D communication, since the radio frequency resources such as the cellular network are space recycled, it is possible to generate several D2D communication links at the same time in the cell, thereby increasing the utilization efficiency and the frequency efficiency of the cellular system. D2D communication based on short distance communication between terminals can reduce the delay in communication and helps to form a link for terminals that can not directly connect to the infrastructure by utilizing D2D relay function. The procedure of cellular-based D2D communication is generally composed of a terminal discovery step of searching for a peripheral terminal capable of D2D communication, a link generating step of forming a radio link with the discovered D2D terminal, and a data transmission step of transmitting traffic between the terminals.

In the hybrid LTE system in which cellular communication and D2D communication coexist, orthogonal resources can not be allocated to each D2D terminal, and the purpose of D2D communication also includes efficient resource use. Therefore, the D2D terminal can be a cellular terminal or another D2D terminal Since the same resources are shared, interference between different systems and interference between D2D terminals becomes inevitable.

Power control technology is often used to mitigate inter-system interference in cellular-based D2D in most cases. In a hybrid LTE system where cellular communication and D2D communication coexist, power control technology is one of the feasible technologies that can improve the performance of D2D and improve the performance of the entire cell by controlling the power of D2D users. Since the SINR (Signal to Interference plus Noise Ratio) at the receiving end becomes larger as the higher power is used at the transmitting end when the D2D communication is performed, when the maximum transmission power is used when one D2D link is used, The capacity is increased and the probability of error occurrence is also lowered. However, as mentioned above, since orthogonal resources can not be allocated to each D2D UE, resources are shared with a cellular UE or another D2D UE. In this case, if the interference to each other is greater than the performance of the entire cells, which can be improved by increasing the transmission power, the network efficiency is lowered and the power control technology becomes less valuable. Therefore, in order to improve the performance of the entire cell, a power control technique for determining transmission power by combining various factors is required.

The technology that is the background of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2014-0080298 (published on June 30, 20130).

SUMMARY OF THE INVENTION The present invention provides a power control based D2D communication system and a power control method thereof that adaptively adjust transmission power to improve performance of a D2D terminal while assuring performance of a cellular terminal.

According to an aspect of the present invention, there is provided an LTE-Advanced based D2D communication system including a plurality of D2D terminals, wherein the D2D includes a current signal to interference and noise ratio (SINR) of the D2D terminal, And a control unit for comparing an increase rate of the SINR when the current transmission power of the D2D terminal is increased by the unit power and a rate of increase of the interference power of the CELLULINK terminal when the current SINR value is smaller than the reference SINR value. And a controller for increasing a current transmission power of the D2D terminal by the unit power if the rate of increase of the SINR is greater than the rate of increase of the interference.

The operation unit calculates an increase rate of the SINR

Figure 112015044842259-pat00001
) And the rate of increase of the interference
Figure 112015044842259-pat00002
Respectively.

Here, SINR D (t-1) is an SINR value according to the current transmission power of the D2D terminal, and? SINR D is an increase amount of SINR when the current transmission power of the D2D terminal is increased by a unit power

Figure 112015044842259-pat00003
), I D (t-1) is the interference magnitude for the neighboring cellular communication according to the current transmission power of the D2D terminal, ΔI D is the neighboring cellular communication when the current transmission power of the D2D terminal is increased by the unit power Increased amount of interference (
Figure 112015044842259-pat00004
).

The calculation unit may calculate an SINR value (SINR D (t)) when the current transmission power of the D2D terminal is increased by a unit power through the following equation.

Figure 112015044842259-pat00005

Where P DTx (t) is the magnitude of the D2D transmit power increased by the unit power, L D2D is the propagation path loss between the D2D terminals, N is the noise power, and P DTx (t-1) is the current transmit power of the D2D terminal , L C2D represents the propagation path loss between the D2D terminal and the cellular terminal.

The operation unit can calculate the interference magnitude I D (t) for the neighboring cellular communication when the current transmit power of the D2D terminal is increased by the unit power through the following equation.

Figure 112015044842259-pat00006

Here, L D2e represents the propagation path loss between the D2D terminal and the base station (eNB).

Wherein the control unit compares the rate of increase of the SINR with the rate of increase of the interference through N iterations if the rate of increase of the SINR is equal to or less than the rate of increase of the interference and if the rate of increase of the SINR is less than the rate of increase of the interference It is possible to control to maintain the current transmission power of the D2D terminal when the transmission power is continuously the same or smaller.

The base station can determine the transmission power level of the cellular terminal through the following equation corresponding to the interference magnitude (I D ) for the cellular communication according to the transmission power of the D2D terminal.

Figure 112015044842259-pat00007

Here, P CTx is transmit power, P max is the minimum guaranteed power, P 0 is a predetermined parameter maximum available power, P min of the cellular terminal is that the cellular terminal to the base station and the cellular communication in the cellular terminal, M The number of allocated resource blocks,

Figure 112015044842259-pat00008
L C2e represents the propagation path loss between the D2D terminal and the base station (eNB).

The P min can be obtained by the following equation.

Figure 112015044842259-pat00009

here,

Figure 112015044842259-pat00010
Represents a reference SINR value.

According to another embodiment of the present invention, in a power control method of a D2D communication system based on an LTE-Advanced including a plurality of D2D terminals, the D2D terminal calculates a value of a current signal-to-interference- Comparing the increase rate of the SINR and the increase rate of the interference to the cellular terminal when the current transmission power of the D2D terminal is increased by the unit power when the current SINR value is smaller than the reference SINR value, And increasing the current transmission power of the D2D terminal by the unit power if the rate of increase of the SINR is greater than the rate of increase of the interference.

As described above, according to the present invention, combining the LTE uplink open loop power control scheme with the interference-based power control scheme can improve the performance of D2D while ensuring the communication performance of the cellular.

That is, the performance of the cellular terminal is guaranteed to be equal to or higher than the target value, and the performance of the D2D terminal can be improved, so that the transmission power can be adjusted to maximize the performance of the entire communication network, and the unnecessary power consumption can be reduced.

Figure 1 is an illustration of D2D communication according to the prior art.
FIG. 2 is a diagram illustrating an uplink resource sharing interference scenario according to an embodiment of the present invention. Referring to FIG.
3 is a configuration diagram of a D2D terminal for performing D2D communication according to an embodiment of the present invention.
4 is a flowchart illustrating a power control method of a D2D terminal according to an embodiment of the present invention.
FIG. 5 is a graph illustrating changes in transmission power and SINR according to an embodiment of the present invention. Referring to FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

Hereinafter, an interference scenario occurring in the D2D communication will be described with reference to FIG.

2 is a diagram illustrating an uplink resource sharing interference scenario according to an embodiment of the present invention.

2, the eNB (base station) is in cellular communication with the cellular terminals UE1, UE2 and UE3, and the D2D transmitting terminal (D2D Tx: D2D transmitter) and the D2D receiving terminal D2D Rx: D2D receiver) performs D2D communication.

At this time, interference (1) may occur in the D2D receiving terminal (D2D Rx) performing the D2D communication while the cellular terminals UE1, UE2, and UE3 transmit signals to the base station (eNB). That is, the interference (1) indicates the interference caused by the signal of the cellular communication in the process of the D2D receiving terminal (D2D Rx) receiving the signal from the D2D transmitting terminal (D2D Tx).

In addition, it is possible to cause the D2D transmitting terminal (Tx D2D) the interference (2) to the base station (eNB) to the cellular communication in the process of transmitting a signal to the receiving terminal D2D (D2D R x). The interference 2 indicates an interference caused by the signal of the D2D transmitting terminal in the process of receiving signals from the cellular terminals UE1, UE2, and UE3 by the base station eNB.

Therefore, according to the embodiment of the present invention, the power of the cellular terminal and the D2D terminal are reduced to reduce the occurrence of the interference (1, 2) as in the above case and to increase the efficiency of the cellular communication and the D2D communication, Control technology.

 That is, according to the embodiment of the present invention, the D2D transmission power is increased to increase the accuracy of the D2D communication from the interference from the cellular terminal, and at the same time, the minimum power of the cellular terminal is set so that the interference does not occur in the signal transmitted to the base station by the cellular terminal And provide technology to guarantee.

Hereinafter, a D2D communication system according to an embodiment of the present invention will be described with reference to FIG.

3 is a configuration diagram of a D2D terminal for performing D2D communication according to an embodiment of the present invention.

The D2D terminal 100 according to the embodiment of the present invention corresponds to the D2D transmitting terminal D2D Tx in FIG. 2 and includes a comparing unit 110, an operation unit 120, and a control unit 130.

The comparison unit 110 calculates the current signal-to-interference plus noise ratio (SINR) value of the D2D terminal 100 and compares the current signal-to-interference plus noise ratio (SINR) with a reference SINR value.

Here, the reference SINR value (

Figure 112015044842259-pat00011
Is a SINR value that should be minimally ensured for the D2D terminal 100 and the cellular terminal to communicate with each other. At this time, if the D2D terminal 100 exceeds the reference SINR value, it can be considered that sufficient normal D2D communication is possible.

When the current SINR value is smaller than the reference SINR value, the calculation unit 120 calculates an increase rate of the SINR and an increase rate of the interference to the cellular terminal when the current transmission power of the D2D terminal 100 is increased by the unit power.

That is, when the constant power is increased at the current transmission power of the D2D terminal 100, the operation unit 120 calculates the SINR increase rate and the interference increase rate for the cellular terminal, respectively.

The control unit 130 compares the rate of increase of the SINR with the rate of increase of the interference, and increases the current transmission power of the D2D terminal by the unit power if the SINR increase rate is greater than the rate of increase of the interference.

If the increase rate of the SINR is equal to or less than the increase rate of the interference, the rate of increase of the SINR is compared with the rate of increase of the interference through the N iterative execution. If the increase rate of the SINR is continuously equal to or less than the rate of increase of the interference, The current transmission power of the mobile station 100 can be controlled.

4 is a flowchart illustrating a power control method of a D2D terminal according to an embodiment of the present invention.

First, the D2D terminal 100 transmits an initial power value

Figure 112015044842259-pat00012
(S410).

The D2D terminal 100 can initialize the power using Equation 1, which is an LTE uplink open loop power control technique.

Figure 112015044842259-pat00013

The parameters used in Equation (1) are described as parameters of the LTE uplink open loop power control scheme as follows,

Figure 112015044842259-pat00014
The closer to 1, the larger the propagation path loss, and the 0 means that the loss is not compensated.

Figure 112015044842259-pat00015

In addition, not only the D2D terminal 100 but also the cellular terminal performing cellular communication can set the initial power using Equation (1).

Next, the D2D terminal 100 calculates the current signal-to-interference-plus-noise ratio (SINR) value of the D2D terminal using the following Equation 2 (S420).

Figure 112015044842259-pat00016

Here, S denotes the intensity of the signal, N denotes the noise, and I denotes the interference. If the value of the SINR is large, it means that the intensity of the signal is stronger than the noise and interference of the signal.

Then, the D2D terminal 100 compares the calculated current signal-to-interference-plus-noise ratio (SINR) with the reference SINR value (S430).

First, to describe the embodiment of the present invention, the reference SINR value is set to 10 dB, but it can be easily changed and set by the user later.

If the current SINR value is smaller than the reference SINR value, the D2D terminal 100 calculates an increase rate of the SINR and an increase rate of the interference to the cellular terminal when the current transmission power of the D2D terminal 100 is increased by the unit power (S440 ).

When the current SINR value is approximated to the reference SINR value or when the rate of increase of the SINR of the D2D terminal 100 is larger than the rate of increase of the interference, The SINR increase rate and the interference increase rate can be calculated by reducing the size of the fixed power constantly.

The D2D terminal 100 determines the rate of increase of SINR (

Figure 112015044842259-pat00017
) And the rate of increase of interference
Figure 112015044842259-pat00018
Respectively.

Here, SINR D (t-1) is an SINR value according to the current transmission power of the D2D terminal 100, and? SINR D is an increase amount of the SINR when the current transmission power of the D2D terminal 100 is increased by a unit power

Figure 112015044842259-pat00019
), I D (t-1) is the interference size for the neighboring cellular communication in case of the current transmission power of the D2D terminal 100, and ΔI D is the interference power of the D2D terminal 100 when the current transmission power of the D2D terminal 100 is increased by the unit power The amount of increase in interference to the surrounding cellular communication of
Figure 112015044842259-pat00020
).

Then, the D2D terminal 100 calculates the SINR value (SINR D (t)) when the current transmission power is increased by the unit power by the following equation (3).

Figure 112015044842259-pat00021

Here, P DTx (t) is the magnitude of the transmission power of the D2D terminal 100 increased by the unit power, L D2D is the propagation path loss between the D2D terminals, N is the noise power, P DTx (t- 100, L C2D represents the propagation path loss between the D2D terminal 100 and the cellular terminal.

Further, the D2D terminal 100 calculates the interference magnitude I D (t) for the neighboring cellular communication when the current transmit power is increased by the unit power by the following equation (4).

Figure 112015044842259-pat00022

Here, L D2e represents the propagation path loss between the D2D terminal 100 and the base station eNB.

Next, the D2D terminal 100 compares the rate of increase of SINR with the rate of increase of interference (S450).

If it is determined in step S450 that the rate of increase of the SINR of the D2D terminal 100 is greater than the rate of increase of the interference, the D2D terminal 100 increases the current transmission power by the unit power (S460).

That is, the increase rate of the SINR is greater than the increase rate of the interference, which means that the increase in communication efficiency is greater than the interference to the base station. Therefore, in order to increase the communication efficiency of the overall D2D system, the D2D terminal 100 .

If it is determined in step S450 that the rate of increase of the SINR is equal to or smaller than the rate of increase of the interference, the D2D terminal 100 controls the current transmission power to be maintained (S470).

That is, when the value of the SINR is increased due to the increase of the transmission power, the rate of increase of the interference is larger. Therefore, the D2D terminal 100 maintains the current transmission power without increasing the transmission power.

Here, according to the embodiment of the present invention, if the increase rate of the SINR is equal to or less than the increase rate of the interference as a result of the comparison in step S450, the increase rate of the SINR and the increase rate of the interference can be compared by repeating N times. That is, since the D2D communication environment may vary from time to time, the D2D terminal 100 repeatedly performs the comparison. If the rate of increase of the SINR is equal to or less than the rate of increase of the interference for N times, the D2D terminal 100 maintains the current transmission power . Here, the number of repetition N can be variously changed depending on the communication environment or the terminal type.

If the value of the current signal-to-interference-plus-noise ratio (SINR) of the current signal-to-interference-plus-noise ratio (SINR) of the D2D terminal 100 calculated in step S430 is greater than or equal to the reference SINR value The D2D terminal 100 controls to maintain the current transmission power as in step S470.

As the transmission power of the D2D terminal 100 is changed through steps S410 through S470, the base station eNB can control the transmission power of the cellular terminal to minimize the interference received from the D2D terminal.

That is, the base station located in the vicinity of the D2D terminal determines the transmission power magnitude of the cellular terminal through the following Equation (5) corresponding to the interference magnitude (I D ) for the cellular communication according to the transmission power of the D2D terminal .

Figure 112015044842259-pat00023

Where P CTx is the transmission power of the cellular terminal, P max is the maximum available power of the cellular terminal, P min is the minimum guaranteed power for cellular communication with the base station, P 0 is a predetermined parameter, The number of resource blocks,

Figure 112015044842259-pat00024
L C2e represents the propagation path loss between the D2D terminal and the base station (eNB).

Accordingly, the base station can control the power by applying Equation (5) so that the cellular terminal maintains the minimum transmission power required to guarantee the reference SINR value.

P min in the equation (5) may be obtained by the following Equation 6.

Figure 112015044842259-pat00025

here,

Figure 112015044842259-pat00026
Denotes a reference SINR value, and a target SINR (
Figure 112015044842259-pat00027
), The transmission power of the cellular terminal must always satisfy Equation (6).

The base station controls the transmission power of the cellular terminal through Equation (5) in the range satisfying Equation (6), so that power to be maintained at a minimum can be guaranteed.

That is, the D2D terminal 100 can control the minimum power of the cellular terminal and control the power to have a high SINR value within a range in which interference is minimized.

Hereinafter, a power control method of a D2D system according to an embodiment of the present invention will be described in which a single cellular user and a D2D link in an environment sharing uplink resources in a single cell environment will be described.

5 is a graph showing changes in transmission power and SINR according to an embodiment of the present invention

The power control method of the D2D system according to the embodiment of the present invention is applied to an environment where one cellular user and one D2D link share an uplink resource in a single cell environment.

5, a circle line represents a D2D UE and a triangle represents a cellular UE. FIG. 5A is a graph illustrating a transmission power increase of the D2D UE according to an embodiment of the present invention. Is a graph showing a change in the SINR value of the D2D terminal according to an embodiment of the present invention.

According to the embodiment of the present invention, the reference SINR value is set to 10dB, the minimum SINR value of the cellular terminal is maintained at 10dB or more, and the SINR value of the D2D terminal is 10dB or less.

Referring to FIGS. 5A and 5B, a conventional cellular UE communicates with a transmission power of 15 dBm and an SINR value of 15 dB, and the D2D terminal D2D UE communicates with a base station Accordingly, it can be seen that the D2D terminal continues to increase the transmission power when the SINR increase rate is high by comparing the SINR increase rate and the interference increase rate when the unit power is increased.

At this time, the D2D terminal increases the transmission power so that the SINR value continues to increase. If the D2D terminal repeats 15 times or more, it becomes close to the reference SINR value of 10dB.

As the SINR value of the D2D terminal increases, the interference to the cellular terminal also increases. Therefore, in (b), the SINR value of the cellular terminal decreases as the SINR value of the D2D terminal increases. It is found that the minimum target value for communicating with the cellular terminal reaches 10 dB, and the SINR value is maintained constant in both the D2D terminal and the cellular terminal.

As the SINR value fluctuates, the transmission power value also changes. When the SINR value of the D2D terminal increases to an approximate value of the reference SINR value, the transmission power of the D2D terminal increases. At this time, the cellular terminal increases the power to maintain the minimum reference SINR value in response to the large interference from the D2D terminal, and accordingly the D2D terminal also increases the transmission power. Then, the D2D terminal and the cellular terminal maintain a constant SINR value through 25 power changes, and the transmission power is maintained at 10 dBm for the D2D terminal and 22 dBm for the cellular terminal.

 That is, it can be seen that the performance of the cellular terminal is guaranteed and the performance of the D2D terminal can be greatly improved without using the maximum transmission power of the D2D terminal.

As described above, according to the embodiment of the present invention, the performance of D2D can be improved while ensuring communication performance of cellular by combining LTE uplink open loop power control scheme and interference perception power control scheme.

That is, the performance of the cellular terminal is guaranteed to be equal to or higher than the target value, and the performance of the D2D terminal can be improved, so that the transmission power can be adjusted to maximize the performance of the entire communication network, and the unnecessary power consumption can be reduced.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: D2D terminal 110:
120: operation unit 130:

Claims (14)

In an LTE-Advanced based D2D communication system including a plurality of D2D terminals,
The D2D terminal,
A comparison unit for calculating a current signal-to-interference-plus-noise ratio (SINR) value of the D2D terminal and comparing the current signal-to-
An operation unit for calculating an increase rate of SINR and an increase rate of interference to the cellular terminal when the current SINR value is smaller than the reference SINR value, when the current transmission power of the D2D terminal is increased by a unit power, and
And a controller for increasing the current transmission power of the D2D terminal by the unit power if the rate of increase of the SINR is greater than the rate of increase of the interference. The method according to claim 1,
The operation unit,
The increase rate of the SINR
Figure 112015044842259-pat00028
) And the rate of increase of the interference
Figure 112015044842259-pat00029
), Respectively: < RTI ID = 0.0 > D2D &
Here, SINR D (t-1) is an SINR value according to the current transmission power of the D2D terminal, and? SINR D is an increase amount of SINR when the current transmission power of the D2D terminal is increased by a unit power
Figure 112015044842259-pat00030
), I D (t-1) is the interference magnitude for the neighboring cellular communication according to the current transmission power of the D2D terminal, ΔI D is the neighboring cellular communication when the current transmission power of the D2D terminal is increased by the unit power Increased amount of interference (
Figure 112015044842259-pat00031
). 3. The method of claim 2,
The operation unit,
A D2D communication system for calculating an SINR value (SINR D (t)) when the current transmission power of the D2D terminal is increased by a unit power through the following equation:
Figure 112016012074331-pat00032

Where P DTx (t) is the magnitude of the transmission power of the D2D terminal increased by the unit power, L D2D is the propagation path loss between the D2D terminals, N is the noise power, and P DTx (t- The transmission power, L C2D , represents the propagation path loss between the D2D terminal and the cellular terminal. Claim 4 has been abandoned due to the setting registration fee. The method of claim 3,
The operation unit,
D2D communication system for calculating an interference magnitude (I D (t)) for a neighboring cellular communication when the current transmit power of the D2D terminal is increased by a unit power through the following equation:
Figure 112015044842259-pat00033

Here, L D2e represents the propagation path loss between the D2D terminal and the base station (eNB). The method according to claim 1,
Wherein,
If the rate of increase of the SINR is equal to or less than the rate of increase of the interference, the rate of increase of the SINR is compared with the rate of increase of the interference through N iterations, and if the rate of increase of the SINR is continuously equal to And controls the D2D terminal to maintain the current transmission power of the D2D terminal. Claim 6 has been abandoned due to the setting registration fee. 5. The method of claim 4,
The base station comprises:
A D2D communication system for determining a transmission power level of the cellular terminal according to an interference magnitude (I D ) for the cellular communication according to a transmission power of the D2D terminal,
Figure 112016012074331-pat00034

Here, P CTx is transmit power, P max is the minimum guaranteed power, P 0 is a predetermined parameter maximum available power, P min of the cellular terminal is that the cellular terminal to the base station and the cellular communication in the cellular terminal, M The number of allocated resource blocks,
Figure 112016012074331-pat00035
L C2e represents the propagation path loss between the cellular terminal and the base station (eNB). Claim 7 has been abandoned due to the setting registration fee. The method according to claim 6,
The P min is obtained from the following equation:
Figure 112015044842259-pat00036

here,
Figure 112015044842259-pat00037
Represents a reference SINR value. A power control method of a D2D communication system based on an LTE-Advanced including a plurality of D2D terminals,
The D2D terminal calculates a current signal-to-interference-plus-noise ratio (SINR) value of the D2D terminal and compares the current signal-to-interference and noise ratio (SINR) with a reference SINR value;
Calculating an increase rate of SINR and an increase rate of interference with a cellular terminal when the current SINR value is smaller than the reference SINR value when the current transmission power of the D2D terminal is increased by a unit power,
And increasing the current transmission power of the D2D terminal by the unit power if the rate of increase of the SINR is greater than the rate of increase of the interference. 9. The method of claim 8,
The step of calculating the rate of increase of the SINR and the rate of increase of the interference,
The increase rate of the SINR
Figure 112015044842259-pat00038
) And the rate of increase of the interference
Figure 112015044842259-pat00039
) Of the D2D communication system,
Here, SINR D (t-1) is an SINR value according to the current transmission power of the D2D terminal, and? SINR D is an increase amount of SINR when the current transmission power of the D2D terminal is increased by a unit power
Figure 112015044842259-pat00040
), I D (t-1) is the interference magnitude for the neighboring cellular communication according to the current transmission power of the D2D terminal, ΔI D is the neighboring cellular communication when the current transmission power of the D2D terminal is increased by the unit power Increased amount of interference (
Figure 112015044842259-pat00041
). 10. The method of claim 9,
The step of calculating the rate of increase of the SINR and the rate of increase of the interference,
(SINR D (t)) when the current transmission power of the D2D terminal is increased by a unit power through the following equation: < EMI ID =
Figure 112016012074331-pat00042

Where P DTx (t) is the magnitude of the transmission power of the D2D terminal increased by the unit power, L D2D is the propagation path loss between the D2D terminals, N is the noise power, and P DTx (t- The transmission power, L C2D , represents the propagation path loss between the D2D terminal and the cellular terminal. Claim 11 has been abandoned due to the set registration fee. 11. The method of claim 10,
The step of calculating the rate of increase of the SINR and the rate of increase of the interference,
Calculating a interference magnitude (I D (t)) for a neighboring cellular communication when the current transmit power of the D2D terminal is increased by a unit power through the following equation:
Figure 112015044842259-pat00043

Here, L D2e represents the propagation path loss between the D2D terminal and the base station (eNB). 9. The method of claim 8,
Wherein the step of increasing by the unit power comprises:
If the rate of increase of the SINR is equal to or less than the rate of increase of the interference, the rate of increase of the SINR is compared with the rate of increase of the interference through N iterations, and if the rate of increase of the SINR is continuously equal to And controls the D2D terminal to maintain the current transmission power of the D2D terminal. Claim 13 has been abandoned due to the set registration fee. 12. The method of claim 11,
The base station comprises:
Determining a transmission power level of the cellular terminal through the following equation corresponding to the interference magnitude (I D ) for the cellular communication according to the transmission power of the D2D terminal:
Figure 112016012074331-pat00044

Here, P CTx is transmit power, P max is the minimum guaranteed power, P 0 is a predetermined parameter maximum available power, P min of the cellular terminal is that the cellular terminal to the base station and the cellular communication in the cellular terminal, M The number of allocated resource blocks,
Figure 112016012074331-pat00045
L C2e represents the propagation path loss between the cellular terminal and the base station (eNB). Claim 14 has been abandoned due to the setting registration fee. 14. The method of claim 13,
The power control method of a D2D communication system, wherein the P min is obtained through the following equation:
Figure 112015044842259-pat00046

here,
Figure 112015044842259-pat00047
Represents a reference SINR value.
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