KR20160024335A - Resource selection method of terminal in device-to-device communication and the terminal thereof - Google Patents

Abstract

The present invention relates to a resource selection method of a terminal in device-to-device (D2D) communication and a terminal thereof. The present invention relates to a resource selection method of a terminal in the D2D communication and the terminal performing the method, characterized by comprising the steps of: selecting SA (Scheduling Assignment) transmission resources for transmitting SA messages based on an energy measurement result of each wireless resource in an SA message transmission section; selecting data transmission resources for transmitting data based on the energy measurement result for at least a part of the data transmission resources consisting of an optional transmission resource pattern in a data transmission section; and transmitting each of the SA message and the data through the selected SA resource and the selected data. The present invention is designed to improve data reception performance by reducing cases of using the same RPT by geographically adjacent transmission terminals.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resource selection method for a terminal in a D2D communication,

The present invention relates to a method of selecting resources of a terminal in D2D communication and a terminal thereof.

Recently, in 3GPP, standardization work for support of proximity service based on the inter-terminal has been actively performed. D2D communication technology which can improve data transmission rate between adjacent terminals and reduce transmission delay is considered as a technology suitable for supporting the inter-terminal proximity-based service. In order for D2D communication technology to effectively support inter-terminal proximity-based services, a more effective wireless resource determination method should be developed so that terminals performing D2D communication can achieve high communication performance.

The 3GPP standardization conference considers an environment in which terminals transmit data signals through a data transmission resource block (RB) configured based on OFDM (Orthogonal Frequency Division Multiplexing) in order to perform D2D communication of terminals. In order to transmit a data signal in this environment, each mobile station must transmit a Scheduling Assignment (SA) message to neighboring mobile stations before a data transmission interval. In the SA message, a resource pattern for transmission (RPT) information to be used for data transmission is included in the SA message. The RPT includes information on the radio resources to which the mobile station desires to transmit data among the radio resources belonging to the data transmission period (Frequency side information) pair of a subframe (or subframe) index (time side information) and a subchannel (or subchannel, at least one subcarrier). The UEs to transmit data transmit their data through the radio resources on the time-frequency axis corresponding to the RPT in the SA message sent by them.

Specifically, referring to FIG. 1, a D2D communication frame for D2D communication may have a period of 40 milliseconds (ms). Each frame is composed of an SA transmission period 101 and a data transmission period 103.

The SA transmission interval 101 is composed of at least one subframe, and is a period during which the D2D UEs transmit or receive the SA message. The SA message is transmitted through the SA resource in the SA transmission interval 101. The terminal transmits the SA resource block corresponding to the sub-channel 105 and the sub-frame 107 among the plurality of SA resource blocks constituting the SA resource, And transmits the SA message.

Herein, the SA message is a message transmitted by the D2D terminals desiring to transmit data to neighboring terminals. The SA message includes identification information (ID) information, timing advancing (TA) information, RPT information to be used for data transmission . The RPT is a resource pattern composed of one or more data transmission resource blocks, and as shown in FIG. 2, at least one of the available data transmission resources corresponding to a specific subchannel 201 and the subframe 203 Of resource blocks.

The data transmission interval 103 is a period during which terminals transmit or receive data. In the data transmission interval 103, the transmitting D2D terminals transmit data traffic using the resource blocks belonging to the RPT included in the SA message transmitted by them. The receiving D2D terminals receive data from the terminal that has transmitted the corresponding SA information through the resource blocks included in the RPT in the received SA information.

In order for D2D transmitting terminals to transmit data without colliding with the RPT in the data transmission period, it is necessary to effectively transmit the RPT to be used by the SA message exchange and correctly receive the RPT information to be used by the other terminals. For this, the communication quality for transmission of the SA message must be guaranteed to be a certain level or more.

In the SA and RPT transmission, interference, in-band emission (IBE) effects and half-duplex are the factors that greatly affect the communication quality. Interference refers to the effect of lowering the reception quality of a signal due to overlapping of signals transmitted by two or more terminals using the same frequency and time resources. IBE is an effect that the transmission power of a signal transmitted by a UE is emitted in a band other than an intended frequency band, thereby interfering with other signals transmitted in a frequency band not used by itself, thereby lowering reception quality. Half-Duplex means that the terminal can not simultaneously transmit and receive signals. Due to the Half-Duplex restriction, a terminal transmitting a signal can not receive a signal of another terminal, and this causes a problem that signals of other terminals can not be received when the terminal transmits signals simultaneously with other terminals.

Nonetheless, research related to existing D2D communication mainly pointed out the problem caused by interference and studied the radio resource decision method to mitigate the interference problem in D2D communication.

Conventional SA resource selection methods for SA transmission can be classified into a random selection scheme and an energy detection based selection scheme.

The random selection scheme is a scheme in which the UE randomly selects one or more resource blocks of the SA resources at equal probability and transmits its own SA message. In the random selection scheme, since the mobile station has a high probability of selecting different SA resources for each SA transmission interval of each frame, the collision between the two SAs can be resolved within a short time. On the other hand, as all UEs randomly select a resource, there is a problem that a resource block is not used in a specific time interval, or SA resources are selected by other UEs at every cycle.

In the energy sensing based selection scheme, the UE measures the energy of all SA resource blocks in the SA transmission interval of the D2D communication frame, selects an arbitrary SA resource block based on the energy, And transmits the SA message through the resource block. The measured energy of the SA resource is determined by the reception strength of the SA signal transmitted by the terminals occupying the corresponding SA resource block. The energy measured by the SA resource block is small, May mean that the distance is long. Accordingly, the UE can avoid overlapping use with other UEs located near by selecting the SA resource block having the least amount of detected energy, and improve the probability of avoiding the interference that the SA message can receive have. However, there is a problem in that when the UE selects only the SA resource block in which the energy is lowly detected, the interference caused by the IBE may be significantly affected by other UEs using different frequency resources at the same time. Also, the geographically adjacent UEs have similar energy levels measured for each of the SA resource blocks, so that the probability of selecting the same resource block increases and the communication performance may be degraded.

In the conventional D2D communication studies, since the IBE effect and the Half-Duplex problem due to the signal transmission of the UE are not considered, when the conventional technology is applied to an actual system, the expected IBE and half- There is a problem that performance is difficult to achieve. That is, in the conventional SA resource selection technique, each mobile station measures the energy of the SA resource blocks and selects the SA resource block with the lowest energy, so that the SA signal transmitted by the mobile station is different in the same time interval And causes interference to other terminals using the SA resource block located at the frequency. At this time, if two or more UEs using the same time interval exist in a geographically close position, the interference of the UEs and the IBE effect are very large, so that the signals of the UEs are difficult to decode.

FIGS. 3 to 6 are diagrams for explaining a problem of selecting an SA resource according to the prior art.

FIGS. 3 and 4 show that the two terminals using the same resources in a channel environment following the exponential path loss model with a path loss index of 4 are located at distances of 20 meters (FIG. 3) and 100 meters (FIG. 4) (Black dot) shows a region where the SINR of the stronger signal of the signals of the two terminals is guaranteed to be 1.5 dB or more when the signal is transmitted with the same transmission power. 5 and 6, when four terminals using the same resources are located at distances of 20 meters (FIG. 5) and 100 meters (FIG. 6) respectively and transmit signals at the same transmission power, And the SINR of the strongest signal is guaranteed to be 1.5 dB or more.

Referring to FIG. 3, it can be seen that the SINR is lowered to 1.5 dB or less in a region at least 200 meters away from the terminals. On the other hand, in FIG. 4, it can be seen that the SINR is maintained at 1.5 dB or more even in a region 500 meters or more away from the terminals. Similarly, in FIG. 5, when four terminals using the same resource are located adjacent to each other within 20 meters, it can be seen that the area where the SINR of the signal is guaranteed to be 1.5 dB or more is limited to a radius of about 50 meters. In FIG. 6, It can be seen that the area that can guarantee an SINR of 1.5 dB or more is extended to a radius of 200 meters when located 100 meters apart. As a result, it can be seen that as the distance between the terminals using the same radio resource in the same time interval is increased, interference and IBE effect are greatly reduced, and the quality of the received signal is improved, and adjacent terminals use different radio resources It can be seen that the broadcast receiving performance can be improved.

For IBE mitigation, the following SA transmission resource selection scheme has been proposed.

Referring to FIG. 7, in order to improve signal reception performance of UEs, a method has been proposed in which UEs 701, which are adjacent to each other in geographical proximity, use different frequency resource blocks belonging to the same time period. That is, in the prior art, a transmitting terminal located in an area where a path loss of X dB or less occurs from a signal transmitted from another transmitting terminal, i.e., a transmitting terminal adjacent to another transmitting terminal, And transmits signals using resources of different frequencies. This is to minimize the influence of the IBE that the UEs belonging to the entire network receive on average and to improve the reception performance by allowing the neighboring terminals to use resources belonging to the same time interval.

In the above-mentioned prior art, terminals using the same time interval due to the Half-Duplex restriction can not receive transmission signals of adjacent transmission terminals. Therefore, when the conventional technique is applied to the SA transmission period, the transmitting terminals can not coordinate the use of the RPT with neighboring transmitting terminals because they can not receive SA messages transmitted by other transmitting terminals that are geographically close to each other do. Therefore, the probability of the neighboring terminals using the same RPT increases, and the average SINR of the data signal transmitted by the terminals may be lowered.

Therefore, research on radio resource selection method for SA transmission that can mitigate IBE and Half-Duplex problem as well as interference should be performed in D2D communication.

Even if an SA message is efficiently transmitted and received, if there are two or more terminals that want to use the same RPT in an RPT transmission interval, a collision may occur between data signals sent from the terminals. In this case, the SINR quality of the data signal transmitted by the two or more UEs due to the collision can be significantly lowered, and the data signal having a low SINR is reduced in the decoding range, thereby causing a problem of degrading the reception performance of the D2D communication.

In order to prevent the deterioration of the signal quality, two or more terminals using the same RPT should detect signals from each other. If it is determined that a collision occurs based on the detection result, the terminals should control to use different RPT . However, in the conventional RPT configuration method shown in FIG. 2, one RPT has at least one data transmission resource block for all subframes, and while an arbitrary terminal transmits a signal, it receives signals from other terminals There is a Half-Duplex constraint. Therefore, when the conventional RPT configuration method is used, there is a problem that collision detection is inevitable between terminals using the same RPT, and the communication performance may be greatly deteriorated.

In order to prevent the RPT collision problem in the environment where the Half-Duplex constraint exists as described above, conventionally, the terminal inserts one or more detection symbols in the RPT as shown in FIG. 8, A technique for detecting a signal has been proposed. Referring to FIG. 8, in the prior art, by observing another signal or energy detected in a resource being used during a search symbol interval 801 inserted in the RPT, it is possible to check whether the other terminal uses the same resource at the same time have. If the terminal detects another terminal that is using the same resource as itself through the detection symbol, the terminal selects a new resource (new RPT) in the next period and transmits its data signal.

However, in the prior art, all UEs that have detected a collision in the same resource re-select other resources in the next data transmission interval. Therefore, all the UEs that used the same resource stop using occupied resources and move to another RPT A phenomenon occurs. As a result, in the next data transmission period, the resource that is being used is not occupied by any terminal and is in an unused state. FIG. 9 shows an example of unused resources generated by reselecting resources by the UEs that have detected a collision when the technology is applied. In addition, since the prior art uses a part of resources available for data transmission as a detection symbol and listens to a signal of another terminal, there is a problem that resource utilization efficiency is reduced. In particular, since there is not much collision in environments with few terminals, the gain due to detection symbol insertion is expected to be low.

Therefore, in D2D data communication, research on RPT selection method that can effectively reduce collision of data signal should be performed.

Meanwhile, the D2D receiving terminal must be able to correctly receive the RPT information through the SA message and receive the data without collision in the radio resource corresponding to the RPT.

The D2D receiving terminal can obtain the RPT information through an implicit method or an explicit method through the SA message.

The implicit method is a method in which the receiving terminal acquires the RPT information based on the location of the resource block receiving the SA message by predefining the mapping system between the SA resource block and the RPT in the system. If the implicit method is used, the terminal does not have to include the RPT information in the SA message. Therefore, the portion occupied by the RPT information in the SA message can be used for other important information. However, in order for the implicit method to operate normally, there is a disadvantage that inter-terminal synchronization is required for the mapping relationship between the SA resource block and the RPT. Also, two or more UEs using the same SA resource block use the same RPT at the time of data transmission, so that there is a problem that data signals collide with each other when a collision occurs between SA signals.

In the external method, the transmitting terminal explicitly displays the RPT information in the SA message, and the receiving terminal uses the RPT information explicitly displayed in the received SA message to transmit the RPT information to be used by the transmitting terminal that sent the corresponding SA message . In the case of using the external method, synchronization is not required for the mapping relation between the SA resource and the RPT, and even if two or more UEs use the same SA, the RPT conflict between the UEs can be avoided when the RPTs are different from each other . On the other hand, in the external method, since it is necessary to always include the RPT information in the SA message, there is less room for storing other important information in the SA message. If the decoding of the RPT information in the SA message fails, There is a disadvantage that it is difficult to normally receive the data of the transmitting terminal that transmitted the message.

Even if the receiving terminal correctly receives the RPT information through the SA message, if the pattern of the RPT is not correctly designed, the data transmission performance may be degraded.

For example, when one RPT is defined as using all subframes on the same subchannel as shown in FIG. 2, the transmitting terminal can transmit data using only a filter having a constant pass band, I have. However, in an environment in which frequency selective fading exists, a terminal using a channel in which a fading phenomenon occurs strongly has a disadvantage that a performance difference according to RPT may be relatively large because fading is continuously affected.

In order to solve this disadvantage, conventionally, a method has been proposed in which one RPT is configured to have a diagonal pattern on the time-frequency axis as shown in Fig. In the diagonal type RPT, the subchannel index is also incremented by one as the subframe index is incremented by one. The diagonal RPT uses different subchannels for each subframe, which is advantageous in that there is little performance deviation per RPT due to frequency selective fading. In this case, however, there is a disadvantage in that the implementation is complicated in that the pass band of the filter must be changed every frame.

In addition to the RPT examples shown in FIGS. 2 and 10, various types of RPTs may exist. However, since the data communication performance of the D2D terminals may be improved or decreased according to the method of configuring the RPT, a more detailed design is required.

The present invention aims at improving data reception performance by reducing the case where geographically adjacent transmitting terminals use the same RPT. In order to achieve this object, the present invention provides a method and apparatus for neighboring terminals to select SA resource blocks of different time intervals so that the exchange of SA messages and RPT information between transmitting terminals can be performed smoothly. In addition, the present invention provides a method and apparatus for identifying a different terminal using the same RPT as the terminal itself, and selecting an RPT by avoiding conflicts therebetween.

In order to solve the above problems, a method of selecting a resource according to the present invention is a method of selecting a resource of a terminal in Device to Device communication. In a Scheduling Assignment (SA) message transmission interval, Selecting an SA transmission resource for transmission of an SA message on the basis of a measurement result; and transmitting data transmission based on energy measurement results of at least a part of data transmission resources constituting an arbitrary transmission resource pattern in a data transmission period Selecting a data transmission resource for the selected SA resource and transmitting the SA message and the data through the selected SA resource and the selected data, respectively.

In addition, a terminal according to the present invention may include a communication unit for transmitting and receiving data and a scheduling assignment (SA) message transmission interval to a terminal that performs resource selection in device to device communication, Based on the result of the measurement, selects an SA transmission resource for transmission of the SA message and, based on the energy measurement result of at least a part of the data transmission resources constituting the arbitrary transmission resource pattern, Selecting a transmission resource, and transmitting the SA message and the data through the selected SA resource and the selected data, respectively.

The resource selection method and apparatus according to the present invention increases SA message and data transmission / reception performance by allowing terminals to exchange SA messages efficiently and prevent a plurality of terminals from selecting the same RPT in an SA message transmission interval.

1 is a diagram showing a structure of a D2D communication frame.
2 is a diagram for explaining the RPT in the D2D communication.
FIGS. 3 to 6 are diagrams for explaining a problem of selecting an SA resource according to the prior art.
7 is a diagram for explaining a method of selecting an SA resource according to the prior art.
8 is a diagram for explaining a data signal detection method of another terminal in the RPT according to the related art.
9 is a diagram illustrating a problem of resource unused in a data signal detection method according to the related art.
10 is a view showing RPT of a diagonal pattern according to the prior art.
11 is a diagram illustrating a structure of an SA transmission interval according to the present invention.
12 is a view showing a Bunch of Frames structure in which a plurality of D2D frames are combined according to the present invention.
13 is a diagram for explaining a method of selecting an SA resource according to the present invention.
FIG. 14 is a diagram illustrating a case where a resource block belonging to the set R? ₁ does not exist in an embodiment of the present invention.
15 is a diagram illustrating a case where a resource block belonging to the set R? ₂ does not exist in an embodiment of the present invention.
16 shows that, among the at least one SA resource blocks included in the set R? ₁ , all the SA resource blocks included in the set R? ₂ and the SA resource blocks located on the different subframes exist, And there is no resource block located in the same sub-channel as at least one of the at least one SA resource blocks included in R? ₂ .
17 is among the at least one SA resource block in the set of R _γ1 In one embodiment of the invention, the set R _γ2 at least one of the SA resource blocks of resource blocks located in the same sub-channel with at least one included in the And there is no SA resource block located on another subframe other than all SA resource blocks included in the set R? ₂ .
18 is located in the same sub-channel and at least one of from among the at least one SA resource block in the set of R _γ1 In one embodiment of the invention, at least one of the SA resource block in the set of R _γ2, set R and there is no SA resource block located on another subframe other than all SA resource blocks included in? ₂ .
19 and 20 are views showing an RPT structure according to the present invention.
21 is a diagram showing a sub-RPT structure according to the present invention.
22 is a view for explaining an embodiment for increasing the detection unit RPT according to the present invention.
23 is a flowchart illustrating an SA resource block selection method according to the present invention.
24 is a flowchart illustrating a method of selecting and reselecting a data resource block according to the present invention.
25 is a flowchart illustrating a resource selection method for D2D communication according to the present invention.
26 is a diagram illustrating an operation according to the present invention when a collision occurs between two different terminals using the same RPT.
27 is a diagram illustrating an operation according to the present invention when a collision occurs in a data transmission interval due to a Half-Duplex constraint.
28 is a diagram showing a case where both the SA selection method and the RPT selection method of the present invention are applied.
29 is a diagram illustrating the number of SA message decoding times of receiving terminals according to the distance from the transmitting terminal.
30 is a diagram showing an SINR CDF of a data signal received by each terminal in a data transmission interval.
31 is a graph showing an average SINR CDF of a signal received by MSs;
32 is a diagram showing an average data rate CDF per terminal.
33 is a block diagram showing a configuration of a terminal according to the present invention.

The present invention targets D2D (Device-to-Device) communication for performing direct communication between neighboring terminals. Terminals are controlled from an infrastructure consisting of a centralized access point such as a base station and an access point (AP), or they select a radio resource to be used by a distributed method, D2D communication. Since D2D communication can accommodate geographically generated wireless data traffic without relaying the infrastructure, it can solve the overload problem of traffic concentrated in base station or AP. For this reason, standardization organizations such as 3GPP and IEEE are promoting the standardization of D2D communication based on LTE-advanced or Wi-Fi.

The present invention is applicable to a wireless communication terminal device capable of performing D2D communication. A method for identifying an available radio resource candidate group and an occupied radio resource of an adjacent mobile station based on energy received for each SA transmission radio resource block, the method comprising the steps of: A method of selecting a SA transmission radio resource block to be used, a method of detecting a collision in radio resource blocks selected by a terminal in a current data transmission interval, and a method of reselecting an RPT to be used in a next data transmission interval based on a collision detection result . The SA resource selection and data resource RPT selection methods proposed by the present invention allow the UEs capable of strong interfering and IBE effects to mutually select different resources so that the D2D SA signal can be received in a wider area than the prior art , It is possible for the terminals using the same RPT to detect each other, thereby reducing signal collision and improving communication performance compared to the prior art.

Embodiments according to the present invention are described in connection with a transmitting apparatus and a receiving apparatus. A transmitting device and a receiving device may be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent, . The transmitting and receiving devices may be a cellular telephone, a personal digital assistant (PDA), a handheld device having wireless connection capability, a computing device or other processing device connected to a wireless modem.

It is noted that the technical terms used herein are used only to describe specific embodiments and are not intended to limit the scope of the present invention. It is also to be understood that the technical terms used herein are to be interpreted in a sense that is generally understood by those skilled in the art to which the present invention belongs, It should not be construed as a meaning or an overly reduced meaning.

Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In this specification, "comprises" Or "include." Should not be construed to encompass the various components or steps that are described in the specification.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention of the user, the operator, or the custom. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, a transmission resource selection method for selecting an SA transmission block without inter-terminal collision in an SA transmission interval will be described.

≪ SA Transmission Period Structure >

11 is a diagram illustrating a structure of an SA transmission interval according to the present invention.

The D2D frame according to the present invention includes an SA transmission interval 101 and a data transmission interval 103 as shown in FIG.

Referring to FIG. 11, an SA resource included in the SA transmission period 1101 is divided into a plurality of SA resource blocks divided on the basis of OFDM. One SA transmission period 1101 includes N _f sub-channels 1103 and N _t SA sub-frames 1105. One SA resource block includes one sub-channel 1103 and one sub-frame 1105 , One SA transmission period 1101 is composed of a total of N _f x N _t SA SA resource blocks.

The present invention has a goal of minimizing interference and IBE effects between adjacent terminals by allowing D2D transmitting terminals located in close proximity to use SA resource blocks located at different times. In order to achieve such a goal, in the present invention, as shown in FIG. 11, an SA transmission period 1101 is composed of a plurality of subframes 1105. In one embodiment, when the SA transmission period 1105 can not physically have a plurality of subframes, a plurality of D2D frames 1201, 1203, and 1205 may be transmitted without changing the frame structure of an existing physical channel, A Bunch of Frames (hereinafter referred to as a " BoF ") structure 1207 may be used. The BoF 1207 structure is a structure in which a plurality of D2D frames 1201, 1203, and 1205 are logically reconstructed as one large frame by combining N _BoF pieces. SA transmission interval in BoF (1207) structure may be of a type that combines the N single _BoF SA transmission interval constituting _BoF N of sub-frames, respectively (1209, 1211, 1213) logically. When the BoF 1207 structure is applied, the UE can transmit SA messages only in the SA transmission periods 1209, 1211, and 1213 without transmitting signals during the data transmission period during the N _BoF D2D frames.

Hereinafter, a method for selecting an SA resource block by the UE in the SA transmission period of the D2D frame defined as described above will be described in detail.

<SA resource block selection>

In the present invention, by selecting SA resource blocks that are expected to cause relatively few interference or IBE effects based on the energy measured in SA resource blocks, the SA message and the receivable area of the data signal We propose an extension method.

In the present invention, each UE measures energy for all SA resource blocks belonging to an arbitrary SA transmission period 1101. In one embodiment, if the terminal initially enters the network, the terminal may measure the energy for the SA resource blocks in the D2D frame that is first started since joining the network. For example, referring to FIG. 13, the UE measures energy for all SA resource blocks in an environment where N _f × N _t SA SA resource blocks are available.

UEs that do not intend to transmit data in the next D2D frame can measure energy for all resource blocks in every SA resource segment until data transmission is required. The UEs may store the measured energy value itself or store the average value of the energy measured in the last N SA resource intervals each time every resource block energy in a new SA resource interval is measured according to the above embodiments.

The UEs attempting to transmit data in the next D2D frame transmit the SA resource blocks in the SA transmission period 1101 of the next D2D frame based on the measured energy to transmit the SA message in the SA transmission period 1101 of the next D2D frame. Select one or more SA resource blocks.

The UE can select the SA resource block considering only the energy measured in the last SA transmission interval immediately before the transmission of the SA message. Alternatively, the UE can select the SA resource block by averaging the measured energy in the last N SA transmission intervals.

In the case of considering only the energy measured in the SA resource interval immediately before transmission of the SA message, since the UE operates based on the latest information on the energy of the resource blocks, when the energy of the SA resource block changes, adaptively, Can be selected. However, when a large number of UEs repeat transmission and non-transmission of an SA message in a short period, the energy value measured in the previous SA transmission interval and the energy value in the SA transmission interval when the actual SA message is transmitted Therefore, there is a disadvantage in that selection of SA resources based on accurate energy detection may not be achieved. The method of considering the average value of N SA resource block energies can make a SA resource selection based on a relatively accurate energy detection even in an environment where channel environment or SA transmission terminal number frequently changes. However, in this case, when the energy of the resource block changes from a specific period, the change can not be immediately reflected. Therefore, the UE can select only the energy measured in the SA transmission interval immediately before transmission of the SA message according to the network status, or select the SA resource block by averaging the measured energy in the N transmission intervals.

Station determines that the set R _γ1 (1301) of a, the measured energy of the first threshold (y1) or less (or lower x _1% of) resource blocks as shown in Figure 13, based on the energy measurement result. The UE (a or sub x _1%) measured for each energy with respect to the SA resource block r _{nf, ntSA} located in n _tSA th subframe of the n _f th sub-channel and the measured energy threshold value 1 (γ1) or less The set of resource blocks R? ₁ is obtained. In Fig. 13, R? ₁ = {r _{1 , 2} , r _{1 , NtSA} , r _{2 , 1} , r _{2 , 2} , r _4,1 , r _{Nr , 1} }. Here, the first threshold may be preset in the terminal according to the standard, or may be determined by the base station according to the network conditions and informed to the terminals.

The SA resource blocks belonging to the set R? ₁ 1301 may be resource blocks that enable the SA message transmitted through one of the corresponding SA resource blocks to be received at the receiving terminal according to the interference below the threshold value and the IBE effect. The UE transmits an SA message using one of the SA resource blocks belonging to the set R? ₁ 1301 so that the SA transmits a relatively small amount of interference and IBE effect to other SA messages transmitted in the same time interval .

Next, based on the energy measurement result, the terminal _calculates the set of resource blocks r _{nf , n t SA} (which is higher x ₂ %) whose measured energy is equal to or higher than the second threshold value ₂ (1303). In Fig. 13, R? ₂ = {r _{2 , 3} , r _{4 , 2} , r _{4 , NtSA} }. Here, the second threshold may be preset in the terminal according to the standard, or may be determined by the base station according to the network conditions and informed to the terminals.

The SA resource blocks belonging to the set R? ₂ 1303 may be resource blocks that allow the SA message transmitted through one of the resource blocks to be received at the receiving terminal according to the IBE effect and the interference exceeding the threshold value. If the UE transmits an SA message using one of the SA resource blocks belonging to the set R? ₂ (1303), the UE may cause a large interference and IBE influence on the SA message of the other UE occupying the same resource block .

The UE can select an SA resource block to be used for transmission of the SA message based on the set R? ₁ 1301 and the set R? ₂ 1303. In various embodiments of the invention, the terminal on at least one the frequencies of the at least one SA resource block in the set of R _γ1 (1301) the at least one SA from among the resource blocks, a set R _γ2 (1303) contained in the And selects an SA resource block that does not overlap in time with all SA resource blocks included in the set R? ₂ (1303). That is, the UE is located in the same sub-channel as at least one of the at least one SA resource blocks included in the set R? ₂ 1303 among at least one SA resource block included in the set R? ₁ 1301, and selects an SA resource block located on a different subframe from all the SA resource blocks included in? ₂ 1303.

For this, the UE determines whether there is an SA resource block belonging to the same subchannel as at least one of the at least one SA resource blocks included in the set R? ₂ 1303 for the SA resource blocks belonging to R? ₁ 1301 . If the at least one SA SA resource blocks that belong to the same sub-channel with at least one of the resource blocks in the set of R _γ2 (1303) exist, the terminal is intended that all matter contained in the SA set in the resource block R _γ2 (1303) It is determined whether or not an SA resource block located in a subframe other than the SA resource blocks exists. If all of the SA resource blocks included in the set R? ₂ 1303 and the SA resource blocks located in another subframe among the corresponding SA resource blocks exist, the terminal selects these SA resource blocks as a final selection candidate group 1305. In FIG. 13, the final selection candidate group 1305 is {r _{2 , 1} , r _{4 , 1} }.

The terminal selects an SA resource block to be used by the final selection candidate group 1305. [ In various embodiments of the present invention, the terminal may select an SA resource block using either an arbitrary selection method or a priority-based selection method. The random selection method is a method of randomly selecting one or more SA resource blocks among the SA resource blocks belonging to the final selection candidate group. The priority based selection method is a method of selecting the final SA resource block according to the priority that the UE has in itself. In various embodiments of the present invention, when a terminal is controlled by a base station, the terminal selects an SA resource block among all candidate resource blocks, and in a distributed operation, the terminal selects one of resource blocks belonging to a limited frequency or time domain . This limits the range of selectable SA resource blocks that can be selected by a low priority terminal (a terminal that operates in a distributed manner), thereby alleviating conflicts that can occur with respect to the selected SA resource block by a terminal having a high priority (terminal controlled by the base station) . At this time, information on the range of the limited SA resource blocks may be included in the system information message and transmitted from the base station, or may be defined in the system and embedded in the terminal. In FIG. 13, the terminal can select any one of {r _{2 , 1} , r _{4 , 1} } as the final selection candidate group 1305 or select any one of them as a priority SA resource block.

If there is no resource block belonging to the set R _γ1

In various embodiments of the present invention, when there is no resource block (R? ₁ =?) Where the measured energy is equal to or less than the first threshold? 1 as shown in FIG. 14, the terminal is not included in the set R? ₂ 1401 And arbitrarily selects one of the SA resource blocks belonging to the set R? ₂ 1401 and the SA resource blocks 1403 belonging to the subframe not identical in time. Accordingly, the UE can expand its SA signal reaching range by avoiding occupation of the same time SA resources with other terminals that can receive and transmit a relatively large IBE effect with the UE.

In one embodiment, if located in any sub-frame SA resource blocks belonging to the R _γ2 1401, i.e., resource blocks belonging to the set R _γ2 of the 1401 does not contain a resource block, a set of R _γ2 1401 , The UE belongs to the same subframe as the SA resource block having the lowest measured energy among the SA resource blocks belonging to R? ₂ (1401) and is located in the other subchannel Select the SA resource block. Or the terminal may select the SA resource blocks are located in the most subchannels SA resource blocks belonging to the SA resource blocks are located at the lower frame portion R _γ2 (1401) belonging to the R _γ2 (1401).

If there is no resource block belonging to the set R _γ2

In various embodiments of the present invention, as shown in FIG. 15, if there is no resource block with the measured energy equal to or greater than the second threshold value? 2 (R? ₂ =?), The terminal may arbitrarily select an SA resource block . In this case, the UE selects one of the SA resource blocks belonging to the set R? ₁ (1501).

In one embodiment, the terminal may select an SA resource block with the lowest measured energy, or may select an SA resource block belonging to the sub-frame with the lowest measured energy. When selecting the SA resource block having the lowest measured energy, the UE selects one of the SA resource blocks having the lowest energy among the SA resource blocks belonging to the set R? ₁ (1501). If the measured energy is selected SA resource blocks that belong to the sub-frame the minimum, a terminal SA that obtain the average energy of each sub-frame-by-frame SA resource block, while the energy is part of the lower sub-frame belongs at the same time in the set R _γ1 And arbitrarily selects one of the resource blocks.

● set R _γ1 at least one of the SA resource blocks in a, set R located on all SA resource block and the other sub-frame included in the _γ2 SA resource block of at least one SA included in the present one, a set R _γ2 contained in If resource blocks are resource blocks located in the same sub-channel with at least one that does not exist among in various embodiments of the invention, the at least one SA resource blocks included in the set R _γ1 (1601) as shown in Fig. 16 among them, a set R when _γ2 (1603) the at least one SA resource blocks are resource blocks located in the same sub-channel and at least one is not present during contained in the terminal is all the SA resource blocks included in the set R _γ2 (1603) One of the resource blocks 1605 that are not located in the same subframe as the resource blocks 1605 can be arbitrarily selected.

● set R _γ1 at least one of the SA resource blocks from, at least one of the SA resource blocks of resource blocks located in the same sub-channel with at least one in the set of R _γ2 included in the present one, included in the set R _γ2 If there is no SA resource block located on all sub-frames other than all SA resource blocks

In various embodiments of the present invention, among at least one SA resource blocks included in the set R? ₁ 1701 as shown in FIG. 17, among the at least one SA resource blocks included in the set R? ₂ 1703 If there is a resource block located in the same subchannel as at least one but no SA resource blocks located on subframes other than all SA resource blocks included in the set R? ₂ (1703), the terminal sets R? ₂ 1703 may select any of the resource blocks 1705 of the set R? ₁ 1701 located in the sub-frame having the smallest number of SA resource blocks.

● set R _γ1 at least one of the SA resource blocks in a, set R _γ2 at least one SA located among the resource blocks in the same sub-channel with at least one, all the SA resource blocks included in the set R _γ2 included in included in the If the SA resource block located on another subframe does not exist

In various embodiments of the invention, a, set R _γ1 (1801) the at least one SA at least one of the SA resource blocks included in among the resource blocks, a set R _γ2 (1803) contained in as shown in FIG. 18 If one is located in the same sub-channel with at least one resource block that is not located in the same sub-frame to all the SA resource blocks included in the set R _γ2 (1803) does not exist, the mobile station in the set of R _γ2 (1803) One of the resource blocks 1805 of the set R? ₁ 1801 located in the sub-frame having the smallest number of SA resource blocks may be arbitrarily selected.

When the UEs have mobility, the energy level of each SA resource block measured through the above procedure may be dynamically changed. In a case where a plurality of terminals reselect an SA resource block every cycle, the operation of the present invention is difficult to stabilize due to the energy level changing dynamically for each SA resource block. In order to prevent such a problem, the present invention defines an SA resource reselection period (T1) having a time longer than one frame period, and after the terminal has terminated T1, the SA resource block Reselect. T1 may be a value arbitrarily determined by the terminal at the beginning of data transmission. Alternatively, T1 may be a value varying according to the average energy change rate of the SA resource blocks (= | current period average energy / previous period average energy -1 |) and may be a value shortened every frame period by a value corresponding to the determined change rate.

In the reselection process, when the UE is transmitting an SA message through a specific SA resource block, a problem according to the Half-Duplex constraint occurs. Therefore, when the SA resource block is reselected, the UE measures energy for the remaining SA resource blocks except the SA resource blocks belonging to the subframe in which the SA message is currently being transmitted, and the UE reselects one of the SA resource blocks through the operation procedure of the invention do. Alternatively, the UE does not transmit the SA message in the immediately preceding frame period to perform the SA reselection, thereby preventing the Half-Duplex constraint and extending the re-selectable SA resource block candidate to all the SA resource blocks.

Hereinafter, an RPT configuration method and an RPT selection method for transmitting data without collision between terminals in a data transmission interval will be described.

<RPT structure>

19 is a view showing an RPT structure according to the present invention.

Referring to FIG. 19, the entire data transmission period has a time length of N _{tDATA partial} frames and has a frequency bandwidth of N _f sub-channels. In an embodiment of the present invention, the data transmission interval is N _RPT may be of a different RPT (1901), each of the RPT (1901) is configured to include at least one data resource blocks located on any of the sub-channel, and any sub-frame. N To the resource blocks constituting the _RPT of RPT (1901), resource blocks located in the same sub-channels are assigned so that a data transmission interval unit not to overlap each other on the time axis as shown in Fig. Herein, each RPT 1901 includes, for each subchannel, ( N _tDATA / N _RPT ) resource blocks located in consecutive subframes on the time axis or N _tDATA / N _RPT ) resource blocks.

In the embodiment of the present invention, each RPT 1901 is divided into M _sub-RPTs 1903, 1905 and 1907, and each sub-RPT 1903, 1905, and 1907 is divided into N _tDATA / ( M x N _RPT ) Or non-contiguous subframes. In an embodiment of the present invention, the terminal may allocate at least some of the M sub-RPTs 1903, 1905, and 1907 to the detector RPT 1903 and the remainder to the transmitters RPT 1905 and 1907. The terminal detects a peripheral signal in the detection unit RPT 1903, and can transmit data or perform RPT reselection in the transmission units RPT (1905, 1907) according to the detection result.

Hereinafter, the RPT selection method according to the present invention will be described in detail.

&Lt; RPT Selection > The terminal performing data transmission selects an SA resource block according to the SA resource block selection method according to an embodiment of the present invention, minimizes the same RPT redundancy selection problem with another terminal through the RPT and the sub- .

To this end, a terminal to transmit data selects an RPT that it intends to use to transmit data resources. The terminal may select the RPT using an implicit method or an extrinsic method. When using the implicit method, the UE can determine the RPT based on the mapping relationship between the SA resource block and the RPT defined in the system. If the external method is used, the UE can arbitrarily select one of the RPTs not used by the other UEs based on the RPT information of the other UEs included in the SA message received in the previous SA transmission period. At this time, the terminal can select an RPT in which the lowest energy is measured on average, among RPTs not used by other terminals. If RPT is selected with the lowest energy measured on average, the probability that a UE uses a data resource block that overlaps with another UE may be reduced, thereby improving communication performance. The terminal selecting the RPT transmits the selected RPT information to the neighboring terminals by including the selected RPT information in the SA message through the current SA transmission interval.

<RPT reselection>

After the terminal transmits the SA message, it transmits data through some of the data resource blocks belonging to the RPT selected by the terminal. At this time, as shown in FIG. 21, the terminal generates m ₁ sub-RPTs (transmission units RPT) 2101 for transmitting data of its own among the M sub-RPTs belonging to the RPT selected by itself according to the RPT and sub- ( M - m ₁ ) number of sub-RPTs (detection unit RPT) 2103 that are not to be transmitted. The terminal can set m ₁ to be equal to or higher than M, if it has a high priority in performing communication, or if a high QoS level is required. Thus, the UE can reduce the probability of detecting duplicate use of the RPT in the future, and consequently the RPT reselection does not occur frequently, thereby reducing the overhead incurred by reselecting the RPT.

The terminal selecting the RPT transmits the RPT information and the sub-RPT information selected by the terminal to the neighboring terminals through the SA transmission interval. The terminal transmits its data through a resource block belonging to a secondary RPT 2101 to which data is to be transmitted and receives data signals from other terminals through the remaining secondary RPTs 2103. If the energy of the signal received at the arbitrary detection unit RPT 2103 is equal to or greater than the threshold value gamma ₁ (or x x%), the mobile station knows that there is another mobile station using the same RPT have.

When it is recognized that the terminal transmitting the data is using the same RPT as another terminal, the terminal reselects the RPT different from the currently used RPT according to the probability P. Specifically, the terminal generates a random number between 0 and 1, and performs RPT reselection when the randomly generated number is smaller than P.

Here, the probability P may be predefined in the system, and the terminal may calculate it in an empirical manner. As an example of an empirical method, when the terminal first recognizes that it is using the same RPT as another terminal, it reselects the RPT at a probability of P = 1 (i.e., always reselects the RPT) If it is repeated, P can be decreased by 0.2. Through this method, the present invention can provide an opportunity to stably use one RPT to terminals that have continuously changed data RPT over a long period of time.

In various embodiments of the invention, the terminal may arbitrarily select one of the available RPTs. Alternatively, the terminal may select RPTs whose RPM candidates are re-selectable and whose measured energy is equal to or lower than the threshold value? ₂ (or lower y%), and may arbitrarily select one of the selected RPT candidate groups. Alternatively, the terminal can select the RPT with the lowest measured energy.

If the terminal if the failed or whether the other terminal is using the same RPT and their, corresponding to the way number is the probability (1- P) a randomly generated but that the other terminal, as is currently being used, and then the RPT It is also used in the data transmission section.

In various embodiments of the invention, the terminal may variably determine the number of transmitters RPT 2101 and detectors RPT 2103. There may arise a problem that the use efficiency of data transmission resources may be lowered if the mobile station continuously transmits data using m ₁ transmission RPTs 2101 out of M sub-RPTs. In order to solve such a problem, according to an embodiment of the present invention, when the RPT currently being used by the terminal is judged not to be used by another terminal or the RPT currently being used by the terminal is continuously used according to the probability, The transmission unit RPT 1201 used for transmitting data is increased by m ₂ as shown in FIG. As shown in FIG. 22, the terminal that does not use the same RPT as the other terminal through the above process can use all the sub-RPTs in the RPT selected by itself in the last time, Can be guaranteed.

Hereinafter, a resource selection method of a terminal according to the present invention will be described.

23 is a flowchart illustrating an SA resource block selection method according to the present invention.

Referring to FIG. 23, the UE measures energy of SA resource blocks (2301). The UE newly participating in the network measures the energy of all the SA resource blocks belonging to the SA transmission interval of the frame that is started first after the participation. The UE then measures the energy level of all SA resource blocks in the SA transmission interval of each frame.

If there is data to be transmitted thereafter (2303), the UE selects an SA resource block to be used based on the measured energy. Specifically, the MS measured energy is a predetermined first threshold value (γ1) or less (or lower x _1% of) the second threshold value (γ2), the measured energy and a set of R _γ1 of the SA resource block group is set greater than (or determines the set R x _γ2 of upper _2% of) resource blocks SA 2305. The first threshold value and the second threshold value may be preset in the terminal according to the standard, or may be determined by the base station according to the network conditions and informed to the terminals. In the following embodiments, it is described that the SA resource blocks that are equal to or less than the first threshold value and equal to or greater than the second threshold value are determined, but depending on the implementation, the idea of the present invention is applied even when the threshold value is less than the first threshold value or exceeds the second threshold value .

The UE selects an SA resource block based on the determined set R? ₁ and the set R? ₂ . Terminal of at least one SA resource blocks from, the same on at least one the frequencies of the at least one SA block in the set of R _γ2, all SA resource blocks included in the set R _γ2 included in the determined set of R _γ1 And selects an SA resource block that does not overlap in time with the SA resource block.

Specifically, the UE determines whether there is an SA resource block included in the set R? ₁ (2307). If there is no SA resource block included in the set R? ₁ , the UE arbitrarily selects one of all SA resource blocks (2309). In one embodiment, the terminal may select the SA resource block with the lowest measured energy based on the measured energy.

If there is an SA resource block included in the set R? ₁ , the UE determines whether an SA resource block included in the set R? ₂ exists (2311). If there is no SA resource block included in the set R? ₂ , the UE arbitrarily selects one of the SA resource blocks included in the set R? ₁ (2313). In one embodiment, the terminal may select the SA resource block with the lowest measured energy among the SA resource blocks included in the set R? ₁ , based on the measured energy.

If there is an SA resource block included in the set R? ₂ , the UE _selects the at least one of the at least one SA resource blocks included in the set R? ₂ among the at least one SA resource blocks included in the set R? It is determined whether there is an SA resource block located on the network (2315). That is, the UE determines whether there is a subchannel including at least one SA resource block included in the set R? ₁ and at least one SA resource block included in the set R? ₂ .

If the at least one SA resource blocks from, at least one of the SA resource blocks of resource blocks located in the same sub-channel with at least one in the set of R _γ2 is in the set of R _γ1 exists, the UE is in the set of R _γ1 (2317) whether there is an SA resource block located in a time that is not the same as all SA resource blocks included in the set R? ₂ among at least one SA resource block. That is, the UE determines whether there is a subframe including only at least one SA resource block included in the set R? ₁ .

If there is an SA resource block located in a time that is not the same as all SA resource blocks included in the set R? ₂ among at least one SA resource blocks included in the set R? ₁ , the terminal arbitrarily selects one of the corresponding SA resource blocks (2319).

On the other hand, if there is no SA resource block located on the same frequency as at least one of the at least one SA resource blocks included in the set R? ₂ among the at least one SA resource blocks included in the set R? ₁ , (2321) whether there is an SA resource block located in a time that is not the same as all SA resource blocks included in the set R? ₂ among at least one SA resource blocks included in R? ₁ . That is, the UE determines whether there is a subframe including only at least one SA resource block included in the set R? ₁ .

If there is an SA resource block located in a time that is not the same as all SA resource blocks included in the set R? ₂ among at least one SA resource blocks included in the set R? ₁ , the terminal arbitrarily selects one of the corresponding SA resource blocks (2323).

On the other hand, if among the at least one SA resource block in the set of R _γ1, the SA resource blocks located in time is not the same as all the SA resource blocks included in the set R _γ2 exists, the mobile station included in the set R _γ2 One of the SA resource blocks of the set R? ₁ located in the sub-frame having the smallest number of SA resource blocks is arbitrarily selected (2325).

Thereafter, the terminal transmits an SA message through the selected SA resource block (2327). The SA message may include information about the RPT that the terminal will use for data transmission, either explicitly or implicitly.

24 is a flowchart illustrating a method of selecting and reselecting a data resource block according to the present invention.

Referring to FIG. 24, the terminal selects an RPT to be used for data transmission (2401). A terminal having data to be transmitted selects an RPT for resource blocks to be used in a data transmission period. Terminal M of sub-RPT actually transfer part detection unit to detect the RPT RPT m ₁ and one peripheral signal to transmit data of belonging in a selected RPT - selects (M m ₂₎ dog 2403.

After that, the terminal transmits the SA message including the RPT information to be used by itself to the neighboring terminals in the SA transmission interval (2405). The SA message may include information about the RPT, either explicitly or implicitly. The SA message may include information on the transmission unit RPT and the detection unit RPT. In various embodiments of the present invention, the terminal may select an SA resource block using the embodiment according to FIG. 23 and transmit the SA message through the selected resource block.

In the data transmission period, the terminal transmits data through the transmission unit RPT and senses the energy of the received signal through the detection unit RPT (2407). The UE determines whether the energy detected in the RPT being used by the UE is equal to or greater than a predetermined threshold value gamma (2409).

If the detected energy is above the threshold value, the terminal performs RPT reselection. Specifically, the terminal generates an arbitrary variable x within the range [0, 1] (2411). If x is less than or equal to the predetermined probability P (step 2413), the terminal returns to step 2401 and reselects the RPT to use. At this time, the terminal can arbitrarily select one of the available RPTs or select the RPT having the lowest measured energy.

On the other hand, if the sensed energy is smaller than the threshold value? Or the sensed energy is equal to or greater than the threshold value? But x is larger than the predetermined probability P , the terminal transmits data using the currently used RPT (2415). At this time, in various embodiments of the present invention, the terminal can change m ₂ of the detectors RPT to the transmitter RPT (2417). The terminal repeats the above-described RPT selection and reselection until the data transmission is completed (2419). In various embodiments of the present invention, RPT selection and reselection may be performed at every D2D communication frame or at predetermined D2D communication frame intervals. In the various embodiments of the present invention, if the number of detectors RPT is 0 due to the repetition of the process before data transmission is completed, the terminal can transmit data through all the RPTs belonging to the RPT selected by the terminal .

25 is a flowchart illustrating a resource selection method for D2D communication according to the present invention.

Referring to FIG. 25, the UE measures energy for SA resource blocks (2501). The UE newly participating in the network measures the energy of all the SA resource blocks belonging to the SA transmission interval of the frame that is started first after the participation. The UE then measures the energy level of all SA resource blocks in the SA transmission interval of each frame.

If there is data to be transmitted thereafter (2503), the UE selects an SA resource block to be used based on the measured energy. Specifically, the MS measured energy is a predetermined first threshold value (γ1) or less (or lower x _1% of) the second threshold value (γ2), the measured energy and a set of R _γ1 of the SA resource block group is set greater than (or determines the set R x _γ2 of upper _2% of) resource blocks SA (2505). The first threshold value and the second threshold value may be preset in the terminal according to the standard, or may be determined by the base station according to the network conditions and informed to the terminals. In the following embodiments, it is described that the SA resource blocks that are equal to or less than the first threshold value and equal to or greater than the second threshold value are determined, but depending on the implementation, the idea of the present invention is applied even when the threshold value is less than the first threshold value or exceeds the second threshold value .

The UE selects an SA resource block based on the determined set R? ₁ and the set R? ₂ . Terminal of at least one SA resource blocks from, the same on at least one the frequencies of the at least one SA block in the set of R _γ2, all SA resource blocks included in the set R _γ2 included in the determined set of R _γ1 And selects an SA resource block that does not overlap in time with the resource block (2507). A concrete example in which the terminal selects a resource block is as described above.

If the SA resource block is selected, the terminal selects an RPT to be used for data transmission (2509). The terminal can arbitrarily select an RPT to be used for data transmission. If the mapping relationship between the SA resource block and the RPT is set in advance, the terminal can select the RPT corresponding to the selected SA resource block.

In addition, the terminal M of sub-RPT actually transfer part detection unit to detect the RPT RPT m ₁ and one peripheral signal to transmit data of belonging in a selected RPT - selects (M m ₂₎ dog 2511.

Then, the terminal transmits the SA message including the RPT information to be used by itself to the neighboring terminals in the SA transmission interval (step 2513). The SA message may include information about the RPT, either explicitly or implicitly. The SA message may include information on the transmission unit RPT and the detection unit RPT.

In the data transmission period, the terminal transmits data through the transmission unit RPT and senses the energy of the received signal through the detection unit RPT (2515). The terminal determines whether the energy detected by the RPT in use is equal to or greater than a preset threshold value gamma (2517).

If the detected energy is equal to or greater than the threshold value, the UE performs RPT reselection probabilistically (2519). The specific embodiment in which the terminal reselects the RPT is as described above.

Thereafter, the terminal performs data transmission until the data transmission is completed using the selected RPT (2521).

According to the embodiment of the present invention, the UEs decode the SA message transmitted in different time slots to acquire the RPT information used by the other UEs, select different RPTs based on the obtained RP message, do.

According to the embodiment of the present invention, as shown in FIG. 26, even if two different mobile stations have the same RPT, the mobile station arbitrarily reselects the RPT in the next reselection interval to avoid collision . In addition, as shown in FIG. 27, when terminals transmit an SA message through a SA resource selection selected arbitrarily every cycle, a collision may occur in a data transmission interval using the same RPT due to a Half-Duplex constraint . According to the embodiment of the present invention, the UEs can detect the RPT collision and reselect the RPT through the RPT selection method of the present invention to avoid collision in the data transmission period.

Also, as shown in FIG. 28, even when both the SA selection method and the RPT selection method of the present invention are applied, the UEs can improve the decoding performance of the SA message by transmitting SA messages in different time slots, When the RPT collision is detected and another RPT is reselected, the neighboring terminal can resolve the collision phenomenon by acquiring the reselected RPT information through the SA.

FIG. 29 is a diagram illustrating an average SINR CDF of a signal received by the UEs as a performance evaluation of a resource selection method according to an embodiment of the present invention. FIG.

In the performance evaluation of FIG. 29, LTE environment and simulation parameters defined in 3GPP TR 36.843 are used, and a method of selecting SA resources, a method of selecting SA resources according to the prior art, and the proposed technique of the present invention are compared and analyzed.

FIG. 29 shows the number of SA message decoding times of transmitting terminals according to the distance between the terminals. 29, it is confirmed that adjacent transmitting terminals transmit SA signals through different time intervals, and therefore, it is possible to decode about 2.8 times as much SA signals as in the prior art in an area of less than 1000 meters where communication is mainly performed . Adjacent transmitting terminals acquire the RPT information of neighboring transmitting terminals and avoid using the same RPT based on the RPT information, thereby improving the signal receiving performance in the data transmission interval by 8.5 dB compared to the prior art.

30 shows an SINR CDF of a data signal received by each terminal in a data transmission interval.

31 shows the CDF of the average SINR per UE experienced by the UE in a data transmission interval. The proposed technology can prevent collision between data signals transmitted by detecting the use of the same RPT by the UEs and selecting different RPTs with different probabilities. Accordingly, it is possible to improve the SINR of the data signal, and based on this, the average data rate per UE can be improved by about 20% as compared with the prior art as shown in FIG.

33 is a block diagram showing a configuration of a terminal according to the present invention.

Referring to FIG. 33, the terminal 3300 according to the present invention includes a communication unit 3301 and a control unit 3303.

The communication unit 3301 can transmit data to or receive data from other terminals. To this end, the communication unit 3301 may include at least one communication module and an antenna.

The control unit 3303 can control each component of the terminal 3300 including the communication unit 3301 for resource selection operation and D2D transmission / reception according to the present invention. The specific operation of the control unit 3303 is as described above.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

3300: terminal 3301:
3303:

Claims (20)

As a resource selection method of a terminal in device to device communication,
Selecting an SA transmission resource for transmission of an SA message based on an energy measurement result of each radio resource in a Scheduling Assignment (SA) message transmission interval;
Selecting a data transmission resource for data transmission based on an energy measurement result of at least a part of data transmission resources constituting an arbitrary transmission resource pattern in a data transmission period; And
And transmitting the SA message and the data through the selected SA resource and the selected data, respectively. 2. The method of claim 1, wherein selecting the SA transmission resource comprises:
Determining a first set of at least one radio resource for which the measured energy is below a first threshold;
Determining a second set of at least one radio resource for which the measured energy is equal to or greater than a second threshold; And
Wherein the first set of radio resources is identical in frequency with at least one of the radio resources included in the second set among at least one radio resources included in the first set and is not equal in time to at least one of the radio resources included in the second set Selecting a radio resource as the SA transmission resource. 3. The method of claim 2, wherein selecting the SA transmission resource comprises:
And selecting one of the radio resources included in the SA message transmission interval if the radio resource included in the first set does not exist. 3. The method of claim 2, wherein selecting the SA transmission resource comprises:
And optionally selecting one of the at least one radio resources included in the first set if the radio resource contained in the second set does not exist. 3. The method of claim 2, wherein selecting the SA transmission resource comprises:
If there is no radio resource having the same frequency in at least one of the radio resources included in the second set among the at least one radio resources included in the first set, And selecting radio resources that are not identical in time with at least one of the radio resources included in the second set. 3. The method of claim 2, wherein selecting the SA transmission resource comprises:
Wherein at least one of the radio resources included in the second set does not exist in the second set and the same radio resource does not exist in at least one of the radio resources included in the second set, Selecting radio resources located at a time when the number of radio resources included in the second set is the smallest among at least one radio resources included in the first set, The resource selection method comprising: 3. The method of claim 2, wherein selecting the SA transmission resource comprises:
If there is no radio resource that is not identical in time with all of the radio resources included in the second set among the at least one radio resources included in the first set, And selecting a radio resource located in a time when the number of radio resources included in the second set is the smallest. 2. The method of claim 1, wherein selecting the data transmission resource comprises:
Selecting at least some radio resources for performing the energy measurement from the data transmission resources constituting the arbitrary transmission resource pattern; And
And performing the energy measurement on the at least a portion of the radio resource. The method according to claim 1,
And reselecting the data transmission resource stochastically if the measured energy is greater than or equal to a third threshold value. 10. The method of claim 9,
And reducing the number of at least some radio resources to perform the energy measurement. To a terminal that performs resource selection in device to device communication,
A communication unit for transmitting and receiving data; And
In a Scheduling Assignment (SA) message transmission interval, an SA transmission resource for transmission of an SA message is selected based on the energy measurement result of each radio resource, and in the data transmission period, data constituting an arbitrary transmission resource pattern Selecting a data transmission resource for data transmission based on an energy measurement result of at least a part of transmission resources, and transmitting the SA message and the data through the selected SA resource and the selected data, respectively To the terminal. 12. The apparatus according to claim 11,
Determining a first set of at least one radio resource for which the measured energy is equal to or less than a first threshold and determining a second set for at least one radio resource for which the measured energy is equal to or greater than a second threshold, A set of radio resources that is equal in frequency to at least one of the radio resources included in the second set among at least one radio resource included in the first set and which is not identical in time with at least one of the radio resources included in the second set, As the SA transmission resource. 13. The apparatus according to claim 12,
And selects one of the radio resources included in the SA message transmission interval if the radio resource included in the first set does not exist. 13. The apparatus according to claim 12,
And selects one of the at least one radio resources included in the first set if the radio resource contained in the second set does not exist. 13. The apparatus according to claim 12,
If there is no radio resource having the same frequency in at least one of the radio resources included in the second set among the at least one radio resources included in the first set, And selecting a radio resource that is not identical to at least one of the radio resources included in the second set in time. 13. The apparatus according to claim 12,
Wherein at least one of the radio resources included in the second set does not exist in the second set and the same radio resource does not exist in at least one of the radio resources included in the second set, And selects radio resources located at a time when the number of radio resources included in the second set is the smallest among at least one radio resources included in the first set, Terminal. 13. The apparatus according to claim 12,
If there is no radio resource that is not identical in time with all of the radio resources included in the second set among the at least one radio resources included in the first set, And selects a radio resource located in a time when the number of radio resources included in the second set is the smallest. 12. The apparatus according to claim 11,
Selects at least some radio resources for performing the energy measurement among the data transmission resources constituting the arbitrary transmission resource pattern, and performs the energy measurement at the at least some radio resources. 12. The apparatus according to claim 11,
And reselects the data transmission resource probabilistically if the measured energy is equal to or greater than a third threshold value. 20. The apparatus of claim 19,
And reduces the number of at least some radio resources for performing the energy measurement.

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