CN107018564B - A kind of D2D terminal transmitted power control method in loss covering scene - Google Patents

Abstract

The present invention relates to the D2D terminal transmitted power control methods in a kind of loss covering scene, belong to mobile communication field.This method meet D2D terminal send signal it is jamproof to cell base station under the conditions of, main straight-through link synchronization signal PSSS, auxiliary straight-through link synchronization signal SSSS and the straight-through discovery channel PSDCH of physics are sent using maximum power, but physics leads directly to common control channel PSCCH and the straight-through shared channel PSSCH of physics is then sent using the minimum power for meeting D2D terminal direct connection communicating requirement.Present invention preserves the existing transmitted power control method of SLSS/PSBCH and PSDCH physical channel, guarantee that D2D terminal by other D2D terminal searchings and can interpret relevant information；Not only two D2D terminal normal communication requirements ensure that, but also reduced the interference that D2D leads directly to link pair cell base station；The output of D2D power consumption of terminal is saved, is conducive to improve D2D end-user experience.

Description

A D2D terminal transmission power control method in a lost coverage scenario

technical field

The invention belongs to the field of mobile communication systems, and relates to a method for controlling transmission power of a D2D terminal in a coverage loss scenario.

Background technique

With the continuous development of communication technology, the next generation mobile communication system - International Mobile Telecommunications-Advanced (IMT-Advanced) system adopts carrier aggregation (Carrier Aggregation, CA) technology, enhanced MIMO ( Multiple-Input Multiple-Output, MIMO) antenna technology, Coordinated Multiple Points (Coordinated Multiple Points, CoMP) technology and relay technology, on the basis of the original cellular mobile communication system, further improve the system capacity and improve the data rate of cell edge users and user experience. However, due to the limitations of the base station-centered cell coverage and service provision of the cellular communication system, the IMT-Advanced system still has problems in coverage and capacity. ,D2D) technology has great advantages in saving resources, reducing interference and improving transmission efficiency, but it still needs to be carefully studied and optimized in many aspects.

In the prior art, resource allocation of D2D users mainly adopts resource allocation in a multiplexing mode. The multiplexing mode is further divided into multiplexing downlink resources and multiplexing uplink resources. When the D2D link multiplexes the uplink resource of the cell terminal, the interference in the system is the interference caused by the cellular user transmitter to the received signal of the D2D receiver and the interference of the D2D transmitter to the normal received signal of the base station. When the D2D link reuses the downlink resources of the cell terminal, the interference in the cell includes the interference caused by the D2D transmitter to the CUE of the cell and the interference from the base station transmitter to the signal received by the D2D receiver. D2D user resource allocation generally designs different optimization goals according to actual needs, such as maximizing system throughput, minimizing system interference, minimizing system power, maximizing spectrum utilization, etc. The greater the interference to the cell, the greater the interference.

In the D2D system, the direct link physical channels include direct link synchronization channel (abbreviation: SLSS), physical layer direct common control channel (abbreviation: PSCCH), physical layer direct shared channel (abbreviation: PSSCH), and physical layer direct discovery channel (abbreviation: PSDCH). Therefore, in the D2D system, the research on the interference of D2D terminals to the cell mainly studies the interference from the physical layer of SLSS, PSCCH, PSSCH and PSDCH to the base station of the cell. Therefore, in actual engineering, it is necessary to perform a power analysis on the physical channel power of D2D terminals sending SLSS, PSCCH, PSSCH and PSDCH. control.

In the current 3rd Generation Partnership Project (abbreviation: 3GPP), it is described according to the 3GPP technical specification LTE-Advanced Physical Layer Procedure Specification (abbreviation: TS36.213). In order to reduce the impact of D2D terminals on the base station of the cell when they perform direct communication, the transmission power of various physical channels on the direct link sent by D2D terminals is specified, and the specific definitions are as follows:

The transmit power of the physical direct shared channel (PSSCH for short) of the terminal is as follows:

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 0, then the transmission power of the PSSCH in the corresponding frame (abbreviation: P _PSSCH ) is:

P _PSSCH = P _CMAX,PSSCH

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 1, the transmission power of the PSSCH in the corresponding frame is:

P _PSSCH ＝min{P _CMAX,PSSCH ,10log ₁₀ (M _PSSCH )+P _{O_PSSCH,1} +α _PSSCH,1 ·PL}[dBm]

Among them: P _CMAX,PSSCH indicates the maximum transmission PSSCH channel power of D2D terminals, and M _PSSCH indicates the channel power allocated for transmission

The bandwidth of the PSSCH resource; P _{O_PSSCH,1} and α _PSSCH,1 come from the configuration information of the cell base station, and PL indicates the path loss between the terminal and the cell base station.

For the same reason, referring to the description of TS36.213, the transmit power of the physical direct control channel (abbreviation: PSCCH) in the corresponding frame can be obtained as:

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 0, then the transmission power of the PSCCH in the corresponding frame (abbreviation: P _PSCCH ) is:

P _PSCCH = P _CMAX,PSCCH

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 1, the transmission power of the PSCCH in the corresponding frame is:

P _PSCCH ＝min{P _CMAX,PSCCH ,10log ₁₀ (M _PSCCH )+P _{O_PSCCH,1} +α _PSCCH,1 ·PL}[dBm]

Among them: P _CMAX,PSCCH indicates the maximum transmission power of the PSCCH channel for D2D terminals, M _PSCCH indicates the bandwidth allocated for transmitting PSCCH resources; P _{O_PSCCH,1} and αPSCCH, ₁ come from the configuration information of the cell base station, and PL indicates the distance between the terminal and the cell base station road loss between.

For the same reason, referring to the description of TS36.213, the transmit power (abbreviated: P _PSDCH ) of the physical direct discovery channel (referred to as: PSDCH) in the corresponding frame can be obtained as

P _PSDCH ＝min{P _CMAX,PSDCH ,10log ₁₀ (M _PSDCH )+P _{O_PSDCH,1} +α _PSDCH,1 ·PL}

Among them: P _CMAX,PSDCH indicates the maximum transmission PSDCH channel power of the D2D terminal, M _PSDCH indicates the bandwidth allocated for transmitting PSDCH resources; P _{O_PSDCH,1} and α _PSDCH,1 come from the configuration information of the cell base station, and PL indicates the distance between the terminal and the cell base station road loss between.

For the same reason, refer to the description of TS36.213. Since SLSS is composed of two physical channels, namely the primary direct link synchronization channel (abbreviation: PSSS) and the secondary direct link synchronization channel (abbreviation: SSSS), it is allocated in TS36.213 The transmit power of the two synchronous channels is given by:

If the transmission power control information (abbreviation: TPC) carried in the PSCCH direct link assignment is 0, the primary direct link synchronization channel transmission power (abbreviation: P _PSSS ), the secondary direct link synchronization channel transmission power (abbreviation: P PSSS ) _SSSS ), the specific definition is as follows:

P _PSSS ＝P _CMAX,PSBCH

P _SSSS = P _CMAX,SSSS

otherwise,

P _PSSS ＝min{P _CMAX,PSBCH ,10log ₁₀ (M _PSSS )+P _{O_PSSS} +α _PSSS ·PL}[dBm],

P _SSSS ＝min{P _CMAX,SSSS ,10log ₁₀ (M _PSSS )+P _{O_PSSS} +α _PSSS ·PL}[dBm],

Among them: P _CMAX,PSBCH represents the maximum transmission PSBCH channel power of the D2D terminal, P _CMAX,SSSS represents the maximum transmission SSSS channel power of the D2D terminal, M _PSSS represents the bandwidth allocated to transmit PSSS resources; P _{O_PSSS} and α _PSSS come from the configuration information of the cell base station , PL represents the path loss between the terminal and the base station of the cell.

It can be seen from the above formula that in the D2D system, D2D transmits various D2D direct physical channels, and it is required that the D2D terminal will use the maximum power to transmit within the interference limit range of the cell base station.

However, in actual D2D usage scenarios, there is a certain difference in the distance between two D2D communication terminals, and the distance between D2D communication terminals is not fixed. Interference is always there. In addition, the power consumption of D2D direct terminals increases linearly with the transmission power of the physical channel. For D2D terminals with a small distance, if the transmission power is too large, it will also affect the receiving performance of D2D terminals. Therefore, it is necessary to allow D2D terminals to meet the interference range of cell base stations. , the physical layer channel can be used for non-maximum power transmission.

Contents of the invention

In view of this, the purpose of the present invention is to provide a D2D terminal transmission power control method in a coverage loss scenario. Under the condition that the D2D terminal transmission signal interferes with the cell base station, the primary direct link synchronization signal (PSSS for short) ), the Secondary Direct Link Synchronization Signal (SSSS for short) and the Physical Direct Discovery Channel (PSDCH for short) are transmitted at maximum power, but the Physical Direct Common Control Channel (PSCCH for short) and the Physical Direct Shared Channel (PSSCH for short) are The minimum power transmission that meets the requirements of the D2D terminal direct communication reduces the interference of the D2D direct link to the base station of the cell, which is conducive to improving the user experience of the D2D terminal.

To achieve the above object, the present invention provides the following technical solutions:

A method for controlling transmission power of a D2D terminal in a coverage loss scenario, comprising the following steps:

S1: The first D2D terminal first determines the power required to send the PSBCH physical channel, which is recorded as the P _PSBCH value, and then encodes the P _PSBCH , the expected minimum PSCCH and PSSCH signal power values, which are recorded as P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} , into the PSBCH data block middle;

S2: The first D2D terminal sends SLSS and PSBCH on fixed time-frequency resources, wherein the PSBCH physical channel is sent using P _PSBCH power; the second D2D terminal first performs SLSS synchronization on the first D2D terminal, and then measures the PSBCH physical channel power, Denoted as R _PSBCH ; the second D2D terminal calculates the path loss PL _D between the two D2D terminals according to the power of P _PSBCH and R _PSBCH ;

S3: The second D2D terminal analyzes and receives the data block of the PSBCH physical channel sent by the first D2D terminal, and obtains the minimum PSCCH and PSSCH channel power P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} parameters that the first D2D terminal expects to receive;

S4: The second D2D terminal calculates the transmit power of P _PSCCH and P _PSSCH ;

S5: The second D2D terminal sends data on the PSCCH and PSSCH channels by using the P _PSCCH and P _PSSCH transmit power.

Further, the step S4 specifically includes the following steps:

S401: Define the physical channel transmit power of the physical direct common control channel PSCCH as

P _{D2D_PSCCH} ＝10log(M _PSCCH )+P _{PSCCH_RxLevMin} +PL _D

Among them, P _{PSCCH_RxLevMin} represents the minimum power requirement of the D2D terminal to receive the PSCCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and M _PSCCH represents the bandwidth allocated to transmit PSCCH resources.

If the transmission power control information TPC carried in the direct link assignment is 0, the transmission power P _PSCCH of the PSCCH in the corresponding frame is:

P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} }

If the transmission power control information TPC carried in the direct link assignment is 1, the transmission power P _PSCCH of the PSCCH in the corresponding frame is:

P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} ,10log ₁₀ (M _PSCCH )+P _{O_PSCCH,1} +α _PSCCH,1 ·PL _C }[dBm]

Among them, P _CMAX,PSCCH indicates the maximum transmission power of the PSCCH channel of the D2D terminal, M _PSCCH indicates the bandwidth allocated for transmitting PSCCH resources; P _{O_PSCCH,1} and _αPSCCH , ₁ come from the configuration information of the cell base station, and PLC indicates the terminal and the cell base station road loss between.

S402: Define the physical channel transmit power of the physical direct shared channel PSSCH as

P _{D2D_PSSCH} ＝10log(M _PSSCH )+P _{PSSCH_RxLevMin} +PL _D

Among them, P _{PSSCH_RxLevMin} represents the minimum power requirement of the D2D terminal to receive the PSSCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and _MPSSCH represents the bandwidth allocated to transmit PSSCH resources.

If the transmission power control information TPC carried in the direct link assignment is 0, the transmission power P _PSSCH of the PSSCH in the corresponding frame is:

P _PSSCH =min{P _CMAX,PSSCH ,P _{D2D_PSSCH} }

If the transmission power control information TPC carried in the direct link assignment is 1, the transmission power P _PSSCH of the PSSCH in the corresponding frame is:

P _PSSCH ＝min{P _CMAX,PSSCH ,P _{D2D_PSSCH} ,10log ₁₀ (M _PSSCH )+P _{O_PSSCH,1} +α _PSSCH,1 ·PL _C }[dBm]

Among them: P _CMAX,PSSCH indicates the maximum transmission power of the PSSCH channel for D2D terminals, M _PSSCH indicates the bandwidth allocated to transmit PSSCH resources; P _{O_PSSCH ,1} and α _PSSCH,1 come from the configuration information of the cell base station, and PLC indicates the terminal and the cell base station road loss between.

The beneficial effects of the present invention are:

(1) The present invention retains the existing transmission power control methods of SLSS/PSBCH and PSDCH physical channels, ensuring that D2D terminals can be searched by other D2D terminals and interpret relevant information.

(2) The present invention limits the power of the PSCCH and PSSCH physical channels, which can not only ensure the normal communication requirements of two D2D terminals, but also reduce the interference of the D2D direct link to the cell base station.

(3) Since the transmission power of the PSCCH and PSSCH physical channels is reduced in the present invention, the power consumption output of the D2D terminal is saved, which is beneficial to improving the user experience of the D2D terminal.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Figure 1 is a flow chart of determining the transmission power of PSCCH and PSSCH physical channels by D2D terminals;

FIG. 2 is a communication structure diagram between D2D in the D2D system;

FIG. 3 is a flow chart of generating direct physical link transmit power by a D2D terminal.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 1, the present invention specifically comprises the following steps:

S1: The first D2D terminal first determines the power required to send the PSBCH physical channel, which is recorded as the P _PSBCH value, and then encodes the P _PSBCH , the expected minimum PSCCH and PSSCH signal power values, which are recorded as P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} , into the PSBCH data block middle. Steps 1 and 2 in Figure 1.

S2: The first D2D terminal sends SLSS and PSBCH on fixed time-frequency resources, wherein the PSBCH physical channel is sent using P _PSBCH power; the second D2D terminal first performs SLSS synchronization on the first D2D terminal, and then measures the PSBCH physical channel power, It is denoted as R _PSBCH ; the second D2D terminal calculates the path loss PL _D between the two D2D terminals according to the power of P _PSBCH and R _PSBCH . Steps 3 and 4 in Figure 1.

S3: The second D2D terminal analyzes and receives the data block of the PSBCH physical channel sent by the first D2D terminal, and obtains the minimum PSCCH and PSSCH channel power P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} parameters that the first D2D terminal expects to receive. 5 steps as shown in Figure 1.

S4: The second D2D terminal calculates the transmission power of P _PSCCH and P _PSSCH . Step 6 in Figure 1.

S5: The second D2D terminal sends data on the PSCCH and PSSCH channels by using the P _PSCCH and P _PSSCH transmit power. Step 7 in Figure 1.

The specific implementation process of the present invention for controlling the transmission power of the PSCCH and PSSCH physical channels in the D2D terminal, as shown in FIG. 1 , there are a first D2D terminal and a second D2D terminal in the D2D system. Communication between the first D2D terminal and the second D2D terminal can be normal. In an embodiment, it is also supported that the first D2D terminal and the second D2D terminal are within or outside the signal coverage of the base station of the cell.

In this embodiment, it is first assumed that the first D2D terminal is in the sending state and the second D2D terminal is in the receiving state, and vice versa.

The second D2D terminal controls the physical channel transmission power method, as shown in Figure 3:

Step 1: Before the direct communication between the second D2D terminal and the first D2D terminal, the second D2D terminal first detects the SLSS signal sent by the first D2D terminal, and interprets the PSBCH broadcast channel information on the direct link. Step 1 in Figure 3.

Step 2: Analyze the PSBCH physical channel transmission power of the first terminal according to the system message broadcast by the PSBCH on the direct link, which is denoted as P _PSBCH . Then the second D2D terminal will measure the signal power of the PSBCH sent by the first D2D terminal, which is denoted as R _PSBCH . These two phase differences are the path loss of the PSBCH physical channel transmitted in the air, which is denoted as _PLD =P _PSBCH -R _PSBCH . Steps 2, 3, and 4 in Figure 3.

Further description, according to the definition of the LTE-Advanced radio resource control protocol (abbreviation: TS36.331) in 3GPP, the content of the PSBCH system message is:

Among them, sl_Bandwidth indicates the direct link bandwidth; tdd_ConfigSL indicates whether the direct link adopts TDD or FDD mode; directFrameNumber indicates the frame number carrying the PSBCH data block on the direct link; directSubframeNumber indicates the subframe number carrying the PSBCH data block on the direct link . inCoverage indicates whether the D2D terminal sending the PSBCH is within the coverage of the cell base station. reserved is a reserved field, indicating future expansion, with a total length of 19 bits.

In this embodiment, the 19 bits are divided into three parts, which respectively bear the transmit power of the PSBCH physical layer channel, and the minimum received signal power of the PSCCH and PSSCH.

In this embodiment, the PSBCH code is represented by a total of 7 bits, and the unit is dbm, which is specifically defined as:

psbchSignalPower INTEGER(-60..30)

The minimum PSCCH received signal power P _{PSCCH_rxLevMin} code, a total of 6 bits, the unit is dbm, specifically defined as:

pscch_rxLevMin_Power INTEGER(-70..-22)

The minimum PSSCH received signal power P _{PSSCH_rxLevMin} code, a total of 6 bits, the unit is dbm, specifically defined as:

pssch_rxLevMin_Power INTEGER(-70..-22)

Therefore, in the embodiment of the present invention, the D2D terminal system information block is defined as:

Step 3: The second D2D terminal analyzes the minimum power P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} required by the first D2D terminal to receive the PSCCH and PSSCH physical channels from the PSBCH physical channel. Step 5 in Figure 3.

Step 4: The second D2D terminal calculates the transmit power values of _{PD2D_PSSS} and _{PD2D_SSSS} according to the requirements of 3GPP TS36.213. Step 6 in Figure 3. The specific calculation method is as follows:

If the transmission power control information (abbreviation: TPC) carried in the PSCCH direct link assignment is 0, the primary direct link synchronization channel transmission power (abbreviation: P _PSSS ), the secondary direct link synchronization channel transmission power (abbreviation: P PSSS ) _SSSS ), the specific definition is as follows:

P _{D2D_PSSS} = P _{CMAX, PSBCH}

P _{D2D_SSSS} = P _{CMAX, SSSS}

otherwise,

P _{D2D_PSSS} ＝min{P _CMAX,PSBCH ,10log ₁₀ (M _PSSS )+P _{O_PSSS} +α _PSSS ·PL _C }[dBm],

P _{D2D_SSSS} ＝min{P _CMAX,SSSS ,10log ₁₀ (M _PSSS )+P _{O_PSSS} +α _PSSS ·PL _C }[dBm],

Among them: P _CMAX,PSBCH represents the maximum transmission PSBCH channel power of the D2D terminal, P _CMAX,SSSS represents the maximum transmission SSSS channel power of the D2D terminal, M _PSSS represents the bandwidth allocated to transmit PSSS resources; P _{O_PSSS} and α _PSSS come from the configuration information of the cell base station , _PLC represents the path loss between the terminal and the base station of the cell.

Step 5: The second D2D terminal calculates the transmit power value of _{PD2D_PDSCH} according to the requirements of 3GPP TS36.213. Step 7 in Figure 3. The specific calculation method is as follows:

P _{D2D_PSDCH} ＝min{P _CMAX,PSDCH ,10log ₁₀ (M _PSDCH )+P _{O_PSDCH,1} +α _PSDCH,1 ·PL _C }

Among them: P _CMAX,PSDCH indicates the maximum transmission PSDCH channel power of the D2D terminal, M _PSDCH indicates the bandwidth allocated for transmitting PSDCH resources; _{P O_PSDCH,1} and α _PSDCH,1 come from the configuration information of the cell base station, and PLC indicates the terminal and the cell base station road loss between.

Step 6: Calculate the P _PSCCH transmit power value according to the present invention, as in Fig. 2, 8 steps, wherein the calculation P _PSCCH is specifically as follows:

P _{D2D_PSCCH} ＝10log(M _PSCCH )+P _{PSCCH_RxLevMin} +PL _D

Among them, P _{PSCCH_rxLevMin} represents the minimum power requirement of the D2D terminal to receive the PSCCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and M _PSCCH represents the bandwidth allocated to transmit PSCCH resources.

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 0, then the transmission power of the PSCCH in the corresponding frame (abbreviation: P _PSCCH ) is:

P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} }

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 1, the transmission power of the PSCCH in the corresponding frame is:

P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} ,10log ₁₀ (M _PSCCH )+P _{O_PSCCH,1} +α _PSCCH,1 ·PL _C }[dBm]

Among them: P _CMAX,PSCCH indicates the maximum transmission PSCCH channel power of the D2D terminal, M _PSCCH indicates the bandwidth allocated for transmitting PSCCH resources; P _{O_PSCCH,1} and _αPSCCH , ₁ come from the configuration information of the cell base station, and PLC indicates the terminal and the cell base station road loss between.

Step 7: Calculate the P _PSSCH transmit power value according to the present invention, as shown in Fig. 3, step 9, wherein the calculation of P _{PSSCH is} specifically as follows:

P _{D2D_PSSCH} ＝10log(M _PSSCH )+P _{PSSCH_RxLevMin} +PL _D

Among them, P _{PSSCH_RxLevMin} represents the minimum power requirement of the D2D terminal to receive the PSSCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and _MPSSCH represents the bandwidth allocated to transmit PSSCH resources.

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 0, then the transmission power of the PSSCH in the corresponding frame (abbreviation: P _PSSCH ) is:

P _PSSCH =min{P _CMAX,PSSCH ,P _{D2D_PSSCH} }

If the transmission power control information (abbreviation: TPC) carried in the direct link assignment is 1, the transmission power of the PSSCH in the corresponding frame is:

P _PSSCH ＝min{P _CMAX,PSSCH ,P _{D2D_PSSCH} ,10log ₁₀ (M _PSSCH )+P _{O_PSSCH,1} +α _PSSCH,1 ·PL _C }[dBm]

Among them: P _CMAX,PSSCH indicates the maximum transmission power of the PSSCH channel for D2D terminals, M _PSSCH indicates the bandwidth allocated to transmit PSSCH resources; P _{O_PSSCH ,1} and α _PSSCH,1 come from the configuration information of the cell base station, and PLC indicates the terminal and the cell base station road loss between.

Step 8: The second D2D terminal uses the calculated power values of P _PSSS , P _SSSS , P _PSDCH , P _PSCCH , and P _PSSCH to transmit physical signals correspondingly. 10 steps as shown in Figure 3.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (1)

1. A D2D terminal transmission power control method in a lost coverage scenario, characterized in that: the method comprises the following steps: S1: The first D2D terminal first determines the power required to send the physical direct link broadcast channel PSBCH, denoted as P _PSBCH , and then P _PSBCH , the physical layer direct common control channel PSCCH and the physical layer direct shared channel PSSCH expect to receive the smallest signal Power values, recorded as P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} , and encoded into the PSBCH data block; S2: The first D2D terminal sends the direct link synchronization channel SLSS and PSBCH on fixed time-frequency resources, wherein the PSBCH physical channel is sent with P _PSBCH power; the second D2D terminal first performs SLSS synchronization on the first D2D terminal, and then measures PSBCH physical channel power, denoted as R _PSBCH ; the second D2D terminal calculates the path loss PL _D between the two D2D terminals according to the power of P _PSBCH and R _PSBCH ; S3: The second D2D terminal analyzes and receives the data block of the PSBCH physical channel sent by the first D2D terminal, and obtains the minimum PSCCH and PSSCH channel power P _{PSCCH_rxLevMin} and P _{PSSCH_rxLevMin} parameters that the first D2D terminal expects to receive; S4: The second D2D terminal calculates the transmission power of P _PSCCH and P _PSSCH ; S5: The second D2D terminal sends data on the PSCCH and PSSCH channels by using the P _PSCCH and P _PSSCH transmission power; Described step S4 specifically comprises: S401: Define the physical channel transmit power of the physical direct common control channel PSCCH as P _{D2D_PSCCH} ＝10log(M _PSCCH )+P _{PSCCH_RxLevMin} +PL _D Among them, P _{PSCCH_RxLevMin} represents the minimum power requirement for the D2D terminal to receive the PSCCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and M _PSCCH represents the bandwidth allocated to transmit PSCCH resources; If the transmission power control information TPC carried in the direct link assignment is 0, the transmission power P _PSCCH of the PSCCH in the corresponding frame is: P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} } If the transmission power control information TPC carried in the direct link assignment is 1, the transmission power P _PSCCH of the PSCCH in the corresponding frame is: P _PSCCH ＝min{P _CMAX,PSCCH ,P _{D2D_PSCCH} ,10log ₁₀ (M _PSCCH )+P _{O_PSCCH,1} +α _PSCCH,1 ·PL _C }[dBm] Among them, P _CMAX,PSCCH represents the maximum transmission power of the D2D terminal PSCCH channel, M _PSCCH represents the bandwidth allocated to transmit PSCCH resources; P _{O_PSCCH,1} and _αPSCCH , ₁ come from the configuration information of the cell base station, PLC represents the terminal and the cell base station road loss between S402: Define the physical channel transmit power of the physical direct shared channel PSSCH as P _{D2D_PSSCH} ＝10log(M _PSSCH )+P _{PSSCH_RxLevMin} +PL _D Among them, P _{PSSCH_RxLevMin} represents the minimum power requirement for the D2D terminal to receive the PSSCH physical channel, PL _D represents the wireless transmission path loss between two D2D terminals, and M _PSSCH represents the bandwidth allocated to transmit PSSCH resources; If the transmission power control information TPC carried in the direct link assignment is 0, the transmission power P _PSSCH of the PSSCH in the corresponding frame is: P _PSSCH =min{P _CMAX,PSSCH ,P _{D2D_PSSCH} } If the transmission power control information TPC carried in the direct link assignment is 1, the transmission power P _PSSCH of the PSSCH in the corresponding frame is: P _PSSCH ＝min{P _CMAX,PSSCH ,P _{D2D_PSSCH} ,10log ₁₀ (M _PSSCH )+P _{O_PSSCH,1} +α _PSSCH,1 ·PL _C }[dBm] Among them: P _CMAX,PSSCH represents the maximum transmission power of the D2D terminal PSSCH channel, M _PSSCH represents the bandwidth allocated to transmit PSSCH resources; P _{O_PSSCH ,1} and α _PSSCH,1 come from the configuration information of the cell base station, PLC represents the terminal and the cell base station road loss between.