WO2016032184A1 - Method for terminal for selecting resource, and terminal therefor in d2d communication - Google Patents

Abstract

The present invention relates to a method for a terminal for selecting a resource and the terminal therefor in device-to-device (D2D) communication. As such, the present invention, which relates to a method for a terminal for selecting a resource in D2D communication, relates to a method for a terminal for selecting a resource and the terminal for executing the method, the method comprising the steps of: selecting, in an SA message transmission section, a scheduling assignment (SA) transmission resource for transmitting an SA message on the basis of energy measurement result of each wireless resource; selecting, in a data transmission section, a data transmission resource for transmitting data on the basis of energy measurement results for at least a part of a data transmission resource constituting a random transmission resource pattern; and transmitting the SA message and data by means of the selected SA resource and selected data. The present invention relates to a communication method for combining a 5G communication system, which is to support higher data throughput than a beyond 4G system, and IoT technology, and a system therefor. The present invention can be applied, on the basis of 5G communication and IoT-related technologies, to functional services such as smart home, smart building, smart city, smart car or connected car, and to services associated with health care, digital education, retail business, security and safety.

Description

A resource selection method of a terminal in D2D communication and the terminal

The present invention relates to a method for selecting a resource of a terminal in D2D communication and the terminal.

In order to meet the increasing demand for wireless data traffic since the commercialization of 4G communication systems, efforts are being made to develop improved 5G communication systems or pre-5G communication systems. For this reason, a 5G communication system or a pre-5G communication system is called a system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE). In order to achieve high data rates, 5G communication systems are being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Gigabit (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, beamforming, massive array multiple input / output (FD-MIMO), and FD-MIMO are used in 5G communication systems. Array antenna, analog beam-forming, and large scale antenna techniques are discussed. In addition, in order to improve the network of the system, 5G communication systems have advanced small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation The development of such technology is being done. In addition, in 5G systems, Hybrid FSK and QAM Modulation (FQAM) and Slide Window Superposition Coding (SWSC), Advanced Coding Modulation (ACM), and FBMC (Filter Bank Multi Carrier) and NOMA are advanced access technologies. (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

Meanwhile, the Internet is evolving from a human-centered connection network in which humans create and consume information, and an Internet of Things (IoT) network that exchanges and processes information between distributed components such as things. The Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers and the like, is emerging. In order to implement the IoT, technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between things, a machine to machine , M2M), Machine Type Communication (MTC), etc. are being studied. In an IoT environment, intelligent Internet technology (IT) services can be provided that collect and analyze data generated from connected objects to create new value in human life. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliances, advanced medical services, etc. through convergence and complex of existing information technology (IT) technology and various industries. It can be applied to.

Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to machine (M2M), machine type communication (MTC), and the like, are implemented by techniques such as beamforming, MIMO, and array antennas. It is. Application of cloud radio access network (cloud RAN) as the big data processing technology described above may be an example of convergence of 5G technology and IoT technology.

Meanwhile, in 3GPP, standardization work for supporting Proximity Service between terminals has been actively performed. D2D communication technology that can improve the data transmission speed between neighboring terminals and reduce the transmission delay is considered as a suitable technology to support the proximity-based services between terminals. In order for D2D communication technology to effectively support the proximity-based services between terminals, a more effective radio 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 data transmission resource blocks (RBs) configured based on orthogonal frequency division multiplexing (OFDM) to perform D2D communication of terminals. In order to transmit a data signal in such an environment, each terminal should transmit a scheduling assignment (SA) message to neighboring terminals before the data transmission interval. The SA message includes resource pattern for transmission (RPT) information for the UE to use for data transmission, and the RPT is a radio resource of the radio resources to which the UE intends to transmit data among radio resources belonging to the data transmission interval. A subframe (or subframe) index (time side information) and a subchannel (or subchannel, at least one subcarrier) index (frequency side information) pairs may be configured. UEs that want to transmit data transmit their data through radio resources on the time-frequency axis corresponding to the RPT in the SA message they send.

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 section 101 and a data transmission section 103.

The SA transmission section 101 is composed of at least one subframe and is a section in which D2D UEs transmit or receive SA messages. The SA message is transmitted through an SA resource in the SA transmission interval 101, and the UE corresponds to an SA resource block corresponding to an arbitrary subchannel 105 and a subframe 107 among the plurality of SA resource blocks constituting the SA resource. Select to send the SA message.

In this case, the SA message is a message that D2D terminals wanting to transmit data to neighboring terminals, and includes their own identification information, timing advance information, and RPT information for data transmission. It includes. The RPT is a resource pattern composed of one or more data transmission resource blocks, and as shown in FIG. 2, at least one corresponding to a specific subchannel 201 and a subframe 203 among available data transmission resources. It may be composed of resource blocks.

The data transmission section 103 is a section in which the terminals transmit or receive data. In the data transmission interval 103, the transmitting D2D terminals transmit data traffic using resource blocks belonging to the RPT included in the SA message transmitted by the transmitting D2D terminals. Receiving D2D terminals receive data from the terminal that has passed 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 an RPT collision in a data transmission interval, it is necessary to effectively transmit an RPT to be used by them through an SA message exchange and to accurately receive RPT information to be used by another terminal. To this end, communication quality for SA message transmission must be guaranteed to a certain level or more.

Factors that significantly affect communication quality in SA and RPT transmission are interference, in-band emission (IBE) effects, and half-duplex issues. Interference refers to the effect that the reception quality of the signal is deteriorated because signals transmitted by two or more terminals using the same frequency and time resources overlap each other. IBE means that the transmission power of the signal transmitted by the terminal is emitted in a band other than the intended frequency band, thereby interfering with other signals being transmitted in a frequency band not used by the terminal, thereby reducing the reception quality. Half-Duplex means that the UE cannot simultaneously perform signal transmission and reception. Due to the Half-Duplex constraint, a terminal that transmits a signal cannot receive a signal of another terminal, which causes a problem in that the terminal cannot receive a signal of another terminal when the terminal simultaneously transmits a signal with another terminal.

Nevertheless, studies related to the existing D2D communication mainly pointed out the problems caused by the interference, and studied radio resource determination methods to alleviate the interference problem occurring in the D2D communication.

The conventional SA resource selection method for SA transmission may be classified into a random selection technique and an energy sensing based selection technique.

The random selection technique is a technique in which the UE randomly selects one or more resource blocks among SA resources with equal probability and transmits its SA message. In the random selection technique, since the UE has a high probability of selecting different SA resources for each SA transmission interval of each frame, there is an advantage in that collision between two UEs which have repeatedly selected the same SA can be resolved quickly. On the other hand, as all terminals randomly select resources, there may be a problem in that there is a problem that resource blocks that are not used in a specific time interval or SA resources are repeatedly selected by other terminals every cycle.

In the energy sensing-based selection technique, 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 this, and then selects an SA selected in the SA transmission interval of the next D2D communication frame. The SA message is transmitted through the resource block. The measured energy of the SA resource is determined by the reception strength of the SA signal transmitted by the UEs occupying the corresponding SA resource block. The fact that the measured energy of the SA resource block is small is different from that of other UEs using the resource block. This may mean that the distance is far. Accordingly, the UE can avoid overlapping with other UEs located in close proximity by selecting an SA resource block having the least detected energy, and improve the probability of avoiding interference that may be received by its SA message. have. However, there is a problem in that when the UE selects only SA resource blocks in which less energy is sensed, interference effects due to IBE may be greatly affected to other terminals using different frequency resources at the same time. In addition, geographically adjacent terminals have a similar energy level measured for each SA resource block, thus increasing the probability of selecting the same resource block and degrading communication performance.

As described above, the conventional D2D communication related studies do not consider the IBE effect and the Half-Duplex problem due to the signal transmission of the terminal. Therefore, when the conventional technology is applied to the actual system, the unexpected IBE and Half-Duplex problems were expected. There is a problem that performance is difficult to achieve. That is, in the conventional SA resource selection technology, since each UE measures the energy of SA resource blocks and selects the SA resource block in which the least energy is detected, the SA signals transmitted by the UE are different in the same time interval due to the IBE effect. It causes a problem that interferes with other terminals using the SA resource block located in the frequency. At this time, if two or more terminals using the same time interval exist in a geographically close location, signals of the corresponding terminals are difficult to decode because interference and IBE effects are very large.

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

3 and 4 are two terminals using the same resources in the channel environment according to the exponential path loss model of the path loss index of 4 and 20 meters (Fig. 3) and 100 meters (Fig. 4), respectively, (Black Point) In the case of transmitting signals with the same transmission power, an area where the SINR of the stronger signal among the signals of the two terminals is guaranteed to be 1.5 dB or more. 5 and 6 illustrate that the four terminals using the same resource are positioned at a distance of 20 meters (FIG. 5) and 100 meters (FIG. 6), respectively, and transmit signals with the same transmission power. The region where the SINR of the strongest signal is guaranteed at least 1.5 dB is shown.

Referring to FIG. 3, it can be seen that the SINR is lowered to 1.5 dB or less in an area of 200 meters or more away from the terminals. On the other hand, in FIG. 4, the SINR is maintained at 1.5 dB or more even in some regions 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 an area in which the SINR of the signal is guaranteed to be 1.5 dB or more is limited to a radius of about 50 meters. When placed 100 meters apart, it can be seen that the area that can guarantee a SINR of 1.5 dB or more is extended to a radius of 200 meters. As a result, as the distance between terminals using the same radio resource in the same time interval increases, interference and IBE effects are greatly reduced, so that the quality of a received signal can be improved, and adjacent terminals use different radio resources. It can be seen that the broadcast reception performance can be improved by doing so.

In order to alleviate IBEs, the following SA transmission resource selection methods have been proposed.

Referring to FIG. 7, in order to improve signal reception performance of terminals, conventionally, a method in which geographically adjacent terminals 701 use different frequency resource blocks belonging to the same time interval has been proposed. That is, in the prior art, a transmitting terminal in an area where a path loss of less than X dB occurs from a signal transmitted by another transmitting terminal, that is, a transmitting terminal adjacent to another transmitting terminal is in the same time interval as the resource transmitted by the other transmitting terminal. Belong to and transmit signals using different resources. This is to minimize the IBE effect that the terminals belonging to the entire network have on average and to improve the reception performance by having adjacent terminals use resources belonging to the same time interval.

In the above conventional technology, due to the Half-Duplex constraint, terminals using the same time interval cannot receive transmission signals of other adjacent transmission terminals. Therefore, when the prior art is applied to the SA transmission interval, the transmission terminal does not receive the SA message transmitted by the other geographically adjacent transmission terminal is a problem that can not perform the coordination of the use of RPT with neighboring transmitting terminals do. Therefore, the probability that neighboring terminals use the same RPT increases, which may lower the average SINR of the data signals transmitted by the terminals.

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

Even if the SA message is efficiently transmitted and received, when two or more terminals to use the same RPT exist in the RPT transmission interval, collisions may occur between data signals transmitted by the terminals. In this case, the SINR quality of the data signal transmitted by two or more terminals due to the collision may be significantly lowered, and the data signal having a low SINR is reduced in decoding range, which causes a problem of deteriorating reception performance of D2D communication.

In order to prevent such signal deterioration, two or more terminals using the same RPT should detect each other's signals, and if it is determined that a collision will occur based on the detection result, the corresponding terminals should be controlled to use different RPTs. . However, in the conventional RPT configuration method shown in FIG. 2, one RPT has at least one data transmission resource block for every subframe, and any terminal may receive a signal from another terminal while transmitting a signal. There is a Half-Duplex constraint that cannot. Therefore, when the conventional RPT configuration method is used, collision detection between the terminals using the same RPT is inevitable, and thus there is a problem that communication performance may be greatly reduced.

In order to prevent the RPT collision problem between terminals in an environment in which the Half-Duplex constraint exists as described above, as shown in FIG. 8, the terminal inserts one or more detection symbols into the RPT and data from other terminals in the detection symbol. Techniques for detecting signals have been proposed. Referring to FIG. 8, in the related art, by observing another signal or energy detected from a resource in use during the discovery symbol interval 801 inserted into the RPT, it is possible to confirm whether another terminal is using the same resource at the same time. have. If the terminal detects another terminal using the same resource as its own 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, since all terminals detecting a collision in the same resource reselect another resource in the next data transmission interval, all the terminals using the same resource stop the occupancy of the used resource and move to another RPT. Phenomenon occurs. As a result, in the next data transmission interval, previously used resources are not occupied by any terminal but become unused. 9 illustrates an example of unused resources that are generated when terminals detecting collisions reselect resources when the corresponding technology is applied. In addition, the prior art has a problem in that the use efficiency of resources is reduced because some of the resources available for data transmission are used as detection symbols to listen to signals of other terminals. In particular, since the collision does not occur much in an environment where the number of terminals is small, the gain due to the insertion of the detection symbol is expected to be low.

Therefore, in the D2D data communication, research on the RPT selection method that can effectively reduce the occurrence of collision of data signals should be conducted.

On the other hand, the D2D receiving terminal should correctly receive the RPT information through the SA message, and can receive data without collision in the radio resource corresponding to the RPT.

The D2D receiving terminal may acquire the RPT information in an implicit manner or in an explicit manner through the SA message.

An implicit method is a method in which the mapping terminal between the SA resource block and the RPT is predefined in the system so that the receiving terminal acquires the RPT information based on the location of the resource block receiving the SA message. In the case of using the implicit method, since the UE does not necessarily have to include RPT information in the SA message, the UE occupies the portion occupied by the RPT information for other main information. However, there is a disadvantage that inter-terminal synchronization on the mapping relationship between the SA resource block and the RPT is essentially required for the intrinsic method to operate normally. In addition, two or more UEs using the same SA resource block have a problem in that collisions between data signals are inevitably generated when collisions occur between SA signals by using the same RPT during data transmission.

In the external method, the transmitting terminal expresses the RPT information explicitly in the SA message, and the receiving terminal selects the RPT information to be used by the transmitting terminal sending the corresponding SA message using the RPT information explicitly indicated in the received SA message. How to obtain. When the external method is used, synchronization is not required for the mapping relationship between the SA resource and the RPT, and even if two or more terminals use the same SA, the RPT collision between the terminals can be avoided when the RPTs are different from each other. . On the other hand, in the external method, since the RPT information must always be included in the SA message, there is less space for putting other important information in the SA message, and if the decoding of the RPT information in the SA message fails from the point of view of the receiving terminal, the corresponding SA There is a disadvantage in that it is difficult to normally receive data of a transmitting terminal that has transmitted a message.

Even if the receiving terminal correctly receives the RPT information through the SA message, if the pattern of the RPT is not designed correctly, 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. Have However, in an environment in which frequency selective fading exists, a terminal using a channel with a strong fading phenomenon is continuously affected by fading, and thus, a performance difference due to RPT may occur relatively.

In order to solve this disadvantage, conventionally, as shown in FIG. 10, a method of configuring one RPT to have a diagonal pattern on a time-frequency axis has been proposed. The diagonal RPT is configured to increase the subchannel index by one as the subframe index increases by one. Such diagonal RPTs have different subchannels for each subframe, so the performance variation of each RPT due to frequency selective fading is small. However, in this case, the implementation is complicated in that the pass band of the filter must be changed every subframe.

In addition to the RPT illustrated in FIGS. 2 and 10, various types of RPTs may exist, but a more detailed design thereof may be required because data communication performance of D2D terminals may be improved or degraded according to a method of configuring RPTs.

An object of the present invention is to improve data reception performance by reducing the case where geographically adjacent transmitting terminals use the same RPT. In order to achieve the above object, the present invention provides a method and apparatus for selecting adjacent SA resource blocks in different time intervals so that SA messages and RPT information exchange between transmitting terminals can be smoothly performed. The present invention also provides a method and apparatus for identifying an RPT by identifying a different terminal using the same RPT as the terminal and avoiding collision between each other accordingly.

In order to solve the above problems, the resource selection method according to the present invention is a resource selection method of a terminal in device-to-device communication, and energy of each radio resource in a scheduling assignment (SA) message transmission interval. Selecting an SA transmission resource for SA message transmission based on the measurement result; in the data transmission interval, based on an energy measurement result of at least a portion of the data transmission resource constituting an arbitrary transmission resource pattern, performing data transmission Selecting a data transmission resource for the data; and transmitting the SA message and the data through the selected SA resource and the selected data, respectively.

In addition, the terminal according to the present invention is a terminal for performing a resource selection in device to device communication, the communication unit for transmitting and receiving data and the scheduling assignment (SA) message transmission interval, the energy measurement of each radio resource Based on the result, the SA transmission resource for the SA message transmission is selected, and in the data transmission interval, data for data transmission based on an energy measurement result for at least a portion of the data transmission resource constituting an arbitrary transmission resource pattern. And a control unit selecting a transmission resource and controlling to transmit the SA message and the data through the selected SA resource and the selected data, respectively.

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

1 is a diagram showing the structure of a D2D communication frame.

2 is a diagram for explaining an RPT in D2D communication.

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

7 is a view for explaining a SA resource selection method according to the prior art.

8 is a view for explaining a data signal detection method of another terminal in the RPT according to the prior art.

9 is a diagram illustrating a resource unused problem occurring in the data signal detection method according to the prior art.

10 is a view showing the RPT of the diagonal pattern according to the prior art.

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

FIG. 12 is a view showing a structure of a bundle of frames in which a plurality of D2D frames is combined according to the present invention.

13 is a diagram for explaining a method of selecting SA resources according to the present invention.

FIG. 14 illustrates a case in which resource blocks belonging to the set R _γ1 do not exist in an embodiment of the present invention.

FIG. 15 is a diagram illustrating a case in which a resource block belonging to a set R _γ2 does not exist in an embodiment of the present invention.

FIG. 16 illustrates that an SA resource block located on a subframe different from all SA resource blocks included in the set R _γ2 exists among at least one SA resource block included in the set R _γ1 according to an embodiment of the present invention. FIG. 7 illustrates a case in which no resource block located in the same subchannel as at least one of at least one SA resource block included in R _γ2 exists.

FIG. 17 illustrates a resource block located in the same subchannel as at least one of at least one SA resource block included in a set R _γ2 from among at least one SA resource block included in a set R _γ1 according to an embodiment of the present invention; Although present, there is a diagram showing a case in which there is no SA resource block located on a subframe different from all SA resource blocks included in the set R _γ2 .

FIG. 18 is located in the same subchannel as at least one of the at least one SA resource blocks included in the set R _γ2 among the at least one SA resource blocks included in the set R _γ1 in an embodiment of the present invention, and the set R FIG. 4 illustrates a case in which SA resource blocks located on subframes different from all SA resource blocks included in _γ2 do not exist.

19 and 20 illustrate an RPT structure according to the present invention.

21 is a view showing a secondary RPT structure according to the present invention.

22 is a view for explaining an embodiment of increasing the detection unit RPT according to the present invention.

23 is a flowchart illustrating a method of selecting a SA resource block according to the present invention.

24 is a flowchart illustrating a data resource block selection and reselection method 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 two different terminals collide with each other 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 illustrating 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 a distance from a transmitting terminal.

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

31 is a diagram illustrating an average SINR CDF of signals received by terminals.

32 shows an average data rate CDF per terminal.

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

The present invention is directed to device-to-device (D2D) communication that performs direct communication between adjacent terminals. Terminals are controlled by an infrastructure consisting of a centralized access point such as a base station or an access point (AP) or select a radio resource to be used by a distributed method and use a corresponding radio resource to connect with neighboring terminals. Perform D2D communication. Since D2D communication can accommodate locally occurring wireless data traffic without relaying infrastructure, there is an advantage that it can solve the problem of overload of traffic concentrated in the base station or AP. For this reason, standardization organizations such as 3GPP and IEEE are pushing for 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. The present invention provides a method for a terminal to identify available radio resource candidate groups and occupied radio resources of an adjacent terminal based on energy received for each SA transmission radio resource block, and the terminal through radio resource blocks identified in the radio resource identification step. 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 the next data transmission interval based on a collision detection result. It consists of. The SA resource selection method and the data resource RPT selection method proposed by the present invention enable UEs that can give strong interference and IBE effect to each other to select different resources, thereby enabling D2D SA signal reception in a wider area than the prior art. In addition, by allowing the terminals using the same RPT to sense each other, it is possible to reduce signal collision and improve communication performance compared to the prior art.

Embodiments according to the present invention are described in connection with a transmitting device and a receiving device. The transmitting device and the receiving device are referred to as a system, subscriber unit, subscriber station, mobile station, mobile, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, user device, or user equipment (UE). Can be. The transmitting device and the receiving device may be cellular telephones, personal digital assistants (PDAs), handheld devices with wireless connection capabilities, computing devices or other processing devices connected to a wireless modem.

It is to be noted that the technical terms used herein are merely used to describe particular embodiments and are not intended to limit the spirit of the present invention. In addition, technical terms used herein should be interpreted as meanings generally understood by those of ordinary skill in the art to which the present invention belongs, unless specifically defined otherwise in the present specification, and excessively comprehensive It should not be construed in meaning or in excessively reduced sense.

Also, the singular forms used herein include the plural forms unless the context clearly indicates otherwise. In this specification, "configured." Or "includes." And the like should not be construed as including all of the various elements or steps described in the specification.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, first, a transmission resource selection method for selecting an SA transport block without collision between terminals in an SA transmission interval will be described.

<SA transmission interval structure>

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

As shown in FIG. 1, the D2D frame according to the present invention includes an SA transmission section 101 and a data transmission section 103.

Referring to FIG. 11, an SA resource included in an SA transmission interval 1101 is divided into a plurality of SA resource blocks divided based on OFDM. One SA transmission interval 1101 is _composed of N _f subchannels 1103 and N _tSA subframes 1105, and one SA resource block includes one subchannel 1103 and one subframe 1105. ), One SA transmission interval 1101 is composed of a total of N _f × N _tSA SA resource blocks.

The present invention aims to minimize the effects of interference and IBE occurring between neighboring terminals by allowing the D2D transmitting terminals located at short distances to use SA resource blocks located at different times. In order to achieve this goal, in the present invention, as illustrated in FIG. 11, the SA transmission interval 1101 includes a plurality of subframes 1105. In an embodiment, when the SA transmission interval 1105 cannot physically have multiple subframes, as shown in FIG. 12, the plurality of D2D frames 1201, 1203, and 1205 without changing the frame structure of the existing physical channel are illustrated. A Frame of Bunch of Frames (BoF) 1207 logically combined may be used. The BoF 1207 structure is a structure in which N _BoFs of a plurality of D2D frames 1201, 1203, and 1205 are combined to logically reconstruct as one large frame. 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 may transmit the SA message only in the SA transmission intervals 1209, 1211, and 1213 without transmitting a signal in the data transmission interval during N _BoF D2D frames.

Hereinafter, a method in which the UE selects an SA resource block in the SA transmission interval of the D2D frame defined as described above in the present invention will be described in detail.

<SA resource block selection>

In the present invention, the UEs to send the SA message select a SA resource block that is expected to occur relatively less interference or IBE effect based on the energy measured in the SA resource blocks to select the reception area of the SA message and data signal. We propose an extension technique.

In the present invention, each terminal measures energy for all SA resource blocks belonging to a certain SA transmission interval 1101. In an embodiment, when the terminal initially enters the network, the terminal may measure energy for SA resource blocks in a D2D frame that is first started after joining the network. For example, referring to FIG. 13, in an environment in which N _f × N _tSA SA resource blocks are available, the UE measures energy for all SA resource blocks.

UEs not intending to transmit data in the next D2D frame may measure energy for all resource blocks in every SA resource interval until data transmission is required. According to the above embodiments, whenever all resource block energy in the new SA resource interval is measured, the UE may store the measured energy value itself or an average value of energy measured in the recent N SA resource intervals.

UEs that want to transmit data in the next D2D frame are SA resource blocks belonging to the SA transmission section 1101 of the next D2D frame based on the energy measured for transmitting the SA message in the SA transmission section 1101 of the next D2D frame. Select one or more SA resource blocks.

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

When considering only the energy measured in the SA resource interval immediately before the SA message transmission, 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, the SA resource block is adaptively adapted accordingly. Can be selected. However, when a large number of UEs repeat the transmission and non-transmission of SA messages in a short period, the energy value measured in the previous SA transmission interval and the energy value in the SA transmission interval when transmitting the actual SA message are different each time. Therefore, there is a drawback that the SA resource selection based on accurate energy sensing may not be achieved. In the method of considering the average value of the N SA resource block energies, a relatively accurate energy sensing based SA resource selection may be made even in a channel environment or an environment in which the number of SA transmitting terminals is frequently changed. However, in this case, when the energy of the resource block changes based on a specific period, there is a disadvantage that the change cannot be reflected immediately. Accordingly, the UE may select only the SA resources block by considering only the energy measured in the SA transmission interval immediately before the SA message transmission according to the network state or averaging the energy measured in the recent N SA transmission intervals.

Based on the energy measurement result, as illustrated in FIG. 13, the terminal determines a set R _{γ 1} 1301 of the resource blocks whose measured energy is equal to or less than the first threshold y1 (or lower x ₁ %). The UE measures energy for each of the SA resource blocks r _{nf and ntSA} located in the n _tSA subframe of the n _f th subchannel _, and the measured energy is less than or equal to the threshold 1 (γ1) (or lower x ₁ %). _Obtain a set R _γ1 of resource blocks. In FIG. 13, R _γ1 = (r _1,2 , r _{1, NtSA} , r _2,1 , r _2,2 , r _4,1 , r _{Nr, 1} }. Here, the first threshold value may be preset in the terminal by a standard, or may be determined by the base station according to network conditions and inform the terminals.

The SA resource blocks belonging to the set R _γ1 1301 may be resource blocks that allow a SA message transmitted through one of the corresponding SA resource blocks to be received at a receiving terminal according to an interference below an threshold value and an IBE effect. The UE transmits an SA message using one of SA resource blocks belonging to the set R _γ1 1301, so that a relatively small amount of interference and IBE effects on other SA messages whose SA messages are transmitted in the same time interval. You can let

Next, the UE based on the energy measurement result, as shown in FIG. 13, the set R _{γ 2} of the resource blocks r _{nf, ntSA} where the measured energy is greater than or equal to the second threshold _{γ 2} (or higher x ₂ %). Determine 1303. In FIG. 13, R _γ2 = {r _2,3 , r _4,2 , r _{4, NtSA} }. Here, the second threshold value may be preset in the terminal by a standard, or may be determined by the base station according to network conditions and inform the terminals.

The SA resource blocks belonging to the set R _γ2 1303 may be resource blocks that allow a SA message transmitted through one of the corresponding resource blocks to be received at a receiving terminal according to interference or an IBE effect above a threshold value. When the terminal transmits an SA message using one of SA resource blocks belonging to the set R _γ2 1303, the terminal may cause a large interference and an IBE effect on the SA message of another terminal occupying the same resource block. .

The UE may select an SA resource block to be used for SA message transmission based on the set R _γ1 1301 and the set R _γ2 1303. According to various embodiments of the present disclosure, the terminal may be configured on a frequency and at least one of at least one SA resource block included in the set R _γ2 1303 among at least one SA resource block included in the set R _γ1 1301. An SA resource block that is the same and does not overlap in time with all SA resource blocks included in the set R _{γ 2} 1303 is selected. That is, the terminal is located in the same subchannel as at least one of the at least one SA resource blocks included in the set R _γ2 1303 among the at least one SA resource blocks included in the set R _γ1 1301. All SA resource blocks included in _γ2 1303 are selected, and the SA resource blocks located on different subframes are selected.

To this end, the UE determines whether there is an SA resource block belonging to the same subchannel as at least one of at least one SA resource block included in the set R _γ 2 1303 for the SA resource blocks belonging to the R _{γ 1} 1301. Determine whether or not. 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 there is an SA resource block located in a subframe different from the SA resource blocks. If there are SA resource blocks located in a subframe different from all SA resource blocks included in the set R _γ2 1303 among the corresponding SA resource blocks, the UE selects these SA resource blocks as the 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 terminal from the final selection candidate group 1305. According to various embodiments of the present disclosure, the terminal may select an SA resource block using any one of a random selection method and a priority based selection method. The random selection method is a method of randomly selecting one or more SA resource blocks among SA resource blocks belonging to the final selection candidate group. The priority-based selection method is a method of selecting a final SA resource block according to a priority that the UE has in itself. According to various embodiments of the present disclosure, when the terminal is controlled by the base station, the terminal selects an SA resource block among all candidate group resource blocks, and when operating in a distributed manner, one of resource blocks belonging to a limited frequency or time domain. Select. This mitigates possible collisions for SA resource blocks selected by high priority terminals (terminals controlled by the base station) by limiting the range of selectable SA resource blocks for low priority terminals (distributively operating terminals). To do this. In this case, the information on the scope of the limited SA resource blocks may be included in the system information message and transmitted from the base station, or may be predefined in the system and may be embedded in the terminal. In FIG. 13, the terminal may finally select one of {r _2,1 , r _4,1 } as the final selection candidate group 1305, or select one according to priority to use as the final SA resource block.

● When there is no resource block belonging to the set R _γ1

According to various embodiments of the present disclosure, when there is no resource block in which the measured energy is equal to or less than the first threshold value γ 1 (R _{γ 1} = Ф), the UE is not included in the set R _{γ 2} 1401. Among the resource blocks that are not present, one of the SA resource blocks 1403 belonging to a subframe that is not identical in time to the SA resource blocks belonging to the set R _γ2 1401 is arbitrarily selected. Through this, the UE can expand its SA signal reach by avoiding the same-time SA resource occupancy with other UEs that can give and receive relatively many IBE effects 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 If there is no resource block belonging to a subframe not overlapping with the UE, the UE is located in the same subframe as the SA resource block having the lowest measured energy among SA resource blocks belonging to R _γ2 1401 and is located in another subchannel. Select an 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).

● When there is no resource block belonging to the set R _γ2

According to various embodiments of the present disclosure, as shown in FIG. 15, if there is no resource block whose measured energy is greater than or equal to the second threshold value γ 2 (R _{γ 2} = Ф), the UE may arbitrarily select an SA resource block. . In this case, the terminal selects one SA resource block among SA resource blocks belonging to the set R _γ1 1501.

According to an embodiment, the terminal may select an SA resource block having the lowest measured energy or select an SA resource block belonging to a subframe having the lowest measured energy. When selecting the SA resource block having the lowest measured energy, the UE selects one SA resource block having the lowest energy among SA resource blocks belonging to the set R _γ1 1501. When selecting the SA resource block belonging to the subframe with the lowest measured energy, the UE obtains the average energy of the SA resource blocks for each subframe, and the SA belongs to the set R _γ1 simultaneously while belonging to the lowest subframe. Randomly select 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 When there is no resource block located in the same subchannel as at least one of the resource blocks In various embodiments of the present invention, at least one SA resource blocks included in the set R _{γ 1} 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 not located in the same subframe may 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 There is no SA resource block located on a subframe different from all SA resource blocks.

According to various embodiments of the present disclosure, as illustrated in FIG. 17, among at least one SA resource blocks included in the set R _{γ 1} 1701, one of the at least one SA resource blocks included in the set R _{γ 2} 1703 may be used. If there is a resource block located in the same subchannel as at least one, but there is no SA resource block located on a subframe different from all SA resource blocks included in the set R _γ2 1703, the terminal is set R _γ2 ( Any one of the resource blocks 1705 of the set R _γ1 1701 located in the subframe having the smallest number of SA resource blocks included in 1703 may be arbitrarily selected.

● 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 there is no SA resource block located on another subframe

According to various embodiments of the present disclosure, as illustrated in FIG. 18, at least one SA resource block included in the set R _γ2 1803 among the at least one SA resource blocks included in the set R _γ1 1801. 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) Any one of the resource blocks 1805 of the set R _γ1 1801 located in the subframe having the smallest number of SA resource blocks can be arbitrarily selected.

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

When the UE transmits the SA message through a specific SA resource block in the reselection process, a problem due to the Half-Duplex constraint occurs. Accordingly, when reselecting an SA resource block, the UE measures energy for the remaining SA resource blocks except for SA resource blocks belonging to the subframe in which the SA message is currently transmitted, and reselects one of them through the operation of the present invention. do. Alternatively, the UE may prevent the Half-Duplex constraint and extend the reselectable SA resource block candidate group to all SA resource blocks by not transmitting an SA message in a frame period immediately before performing the SA reselection.

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 interval has a time length of N _tDATA subframes and a frequency bandwidth of N _f subchannels. In an embodiment of the present invention, the data transmission interval is N _RPTs 191 may be configured with each RPT 1901, and each RPT 1901 may include at least one data resource block located on any subchannel and any subframe. N _As resource blocks constituting the RPT RPTs 1901, resource blocks located on the same subchannel are allocated not to overlap each other on the time axis in units of one data transmission interval as shown in FIG. 20. Here, each of the RPTs 1901 is for each subchannel ( N _tDATA / N _RPT ) resource blocks located in consecutive subframes on a time axis or ( N _tDATA / N located in discrete subframes). _RPT ) may be composed of resource blocks.

In an embodiment of the present invention, each RPT 1901 is divided into M _sub-RPTs 1901, 1905, 1907, and each sub RPT 1901, 1905, 1907 is N _tDATA / ( M × N _RPT ) consecutive It consists of subframes that are or discontinuous. According to an embodiment of the present disclosure, the terminal may allocate at least some of the M sub-RPTs 1901, 1905, and 1907 to the detection sub-RPTs 1403, and assign the rest to the transmission sub-RPTs 1905 and 1907. The UE may detect the neighboring signal in the detection unit RPT 1901 and transmit data or perform RPT reselection in the transmission units RPT 1905 and 1907 according to the detection result.

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

<RTP Selection> The UE performing data transmission selects an SA resource block according to the SA resource block selection method according to an embodiment of the present invention and then minimizes the same RPT duplication selection problem with other UEs through the RPT and the sub-RPTs to thereby RPT. To select.

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

<Reselect RPT>

After the UE transmits the SA message, it transmits data through some of the data resource blocks belonging to the RPT selected by the UE. At this time, the terminal for the RPT and the sub own are M unit RPT from and they transmit data m ₁ of sub-RPT (transmission portion RPT) (2101) of data belonging to the selected RPT according to the RPT structure, as shown in Figure 21 Select ( M - m ₁ ) sub-RPTs (detection part RPT) 2103 not to be transmitted. The UE may set m ₁ to a level equal to or similar to M if it has a high priority in performing its communication or if a high QoS level is required. As a result, the UE can reduce the probability of detecting the future use of RPT duplication, and as a result, the RPT reselection does not occur frequently, thereby reducing the overhead incurred by reselecting the RPT.

The terminal selecting the RPT transmits the selected RPT information and the sub-RPT information through the current SA transmission interval to the neighboring terminals in the SA message. The terminal transmits its own data through a resource block belonging to a secondary RPT 2101 to transmit data, and receives data signals from other terminals through the remaining secondary RPTs 2103. If the energy of the signal received from any detection unit RPT 2103 is greater than or equal to the threshold γ ₁ (or higher x%), the UE may know that there is another UE using the same RPT as its own. have.

When the UE transmitting data recognizes that the same RPT is being used as the other UE, the UE reselects the RPT different from the currently used RPT according to the probability P. FIG. In more detail, the terminal may randomly generate a number between 0 and 1 and may perform RPT reselection when the randomly generated number is smaller than P.

In this case, the probability P may be predefined in the system, and the terminal may be calculated by an empirical method. As an example of the empirical method, when a terminal first recognizes that it is using the same RPT as another terminal, the UE reselects the RPT with a probability of P = 1 (that is, always reselects the RPT), and the reselection is performed every cycle. If repeated, P may be reduced by 0.2. Through this method, the present invention can provide an opportunity for stable use of one RPT to terminals that have continuously changed the data RPT for a long period of time.

In various embodiments of the present disclosure, the terminal may arbitrarily select one of the available RPTs. Alternatively, the terminal may select RPTs having a measured energy less than or equal to the threshold γ ₂ (or lower y%) as a reselectable RPT candidate group, and may arbitrarily select any one of the selected RPT candidate groups. Alternatively, the terminal may select the RPT with the lowest measured energy.

If the terminal does not recognize another terminal using the same RPT as its own, or if the terminal recognizes another terminal as described above but the randomly generated number corresponds to the probability (1- P ), the next RPT being used is next. It is also used in the data transmission section.

According to various embodiments of the present disclosure, the terminal may variably determine the number of transmitter RPT 2101 and detector RPT 2103. If the UE continuously transmits data using only m ₁ transmission RPTs 2101 among the M sub-RPTs, a problem may occur that the efficiency of using data transmission resources may be reduced. In order to solve this problem, according to an embodiment of the present invention, if it is determined that another terminal does not use the RPT currently being used or the terminal continues to use the RPT currently being used according to the probability, the terminal is shown in FIG. 21. As shown in FIG. _{2, the} number of transmission units RPT 1201 used to transmit data is increased by _two m2 . Through the above process, the terminal which does not use the same RPT as the other terminal can finally use all the sub-RPTs in the RPT selected by the user for data transmission as shown in FIG. I can guarantee it.

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

23 is a flowchart illustrating a method of selecting a SA resource block according to the present invention.

Referring to FIG. 23, a terminal first measures energy of SA resource blocks (2301). A newly participating terminal in the network measures the energy for all SA resource blocks belonging to the SA transmission interval of the first frame starting after the participation. Thereafter, the UE measures energy levels of all SA resource blocks in the SA transmission interval of each frame.

If there is data to be transmitted later (2303), the terminal selects an SA resource block to use based on the measured energy. In more detail, the UE may have a set R _{γ 1} of SA resource blocks whose measured energy is less than or equal to a preset first threshold γ 1 (or lower x ₁ %) and the measured energy is greater than or equal to a preset second threshold γ 2 (or A set R _{γ 2} of SA resource blocks (upper ₂ %) is determined (2305). The first threshold value and the second threshold value may be preset in the terminal by a standard, or determined by the base station according to network conditions, and inform the terminals. In the following embodiments, it will be described as determining the SA resource block that is less than the first threshold value and more than the second threshold value, but according to the implementation, the idea of the present invention may be applied even if it is less than the first threshold value or more than the second threshold value. Can be.

The terminal selects an SA resource block based on the determined set R _γ1 and the set R _γ2 . The UE is identical in frequency to at least one of the at least one SA blocks included in the set R _γ2 among the at least one SA resource blocks included in the determined set R _γ1 , and all SA resource blocks included in the set R _γ2 . Select a SA resource block that does not overlap with each other.

Specifically, first, the terminal determines whether an SA resource block included in the set R _γ1 exists (2307). If there is no SA resource block included in the set R _γ1 , the UE randomly selects one of all SA resource blocks (2309). In an embodiment, the terminal may select the SA resource block having the lowest measured energy based on the measured energy.

If the SA resource block included in the set R _γ1 exists, the UE determines whether the SA resource block included in the set R _γ2 exists (2311). If there is no SA resource block included in the set R _γ2 , the UE randomly selects one of the SA resource blocks included in the set R _γ1 (2313). According to an embodiment, the terminal may select the SA resource block having the lowest measured energy among SA resource blocks included in the set R _γ1 based on the measured energy.

If there is an SA resource block included in the set R _γ2 , the UE may have the same frequency as at least one of the at least one SA resource blocks included in the set R _γ2 among the at least one SA resource blocks included in the set R _γ1 . It is determined whether there is an SA resource block located on the block (2315). That is, the terminal determines whether there is a subchannel including at least one SA resource block included in the set R _γ1 and at least one SA resource block included in the set R _γ2 .

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 Among the at least one SA resource block, it is determined whether there is an SA resource block located at a time that is not the same as all SA resource blocks included in the set R _γ2 (2317). That is, the terminal determines whether there is a subframe including only at least one SA resource block included in the set R _γ1 .

Among the at least one SA resource blocks included in the set R _γ1 , if there is an SA resource block located at a time that is not the same as all SA resource blocks included in the set R _{γ 2} , the terminal randomly selects one of the corresponding SA resource blocks. Select (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 block included in the set R _γ2 among the at least one SA resource blocks included in the set R _γ1 , the terminal is configured. Among the at least one SA resource blocks included in R _γ1 , it is determined whether there is an SA resource block located at a time that is not the same as all SA resource blocks included in the set R _{γ 2} (2321). That is, the terminal determines whether there is a subframe including only at least one SA resource block included in the set R _γ1 .

Among the at least one SA resource blocks included in the set R _γ1 , if there is an SA resource block located at a time that is not the same as all SA resource blocks included in the set R _{γ 2} , the terminal randomly selects one of the corresponding SA resource blocks. Select (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 _γ1 located in the subframe having the smallest number of SA resource blocks is randomly selected (2325).

Thereafter, the terminal transmits an SA message through the selected SA resource block (2327). In the SA message, information about the RPT to be used for data transmission by the terminal may be explicitly or implicitly included.

24 is a flowchart illustrating a data resource block selection and reselection method according to the present invention.

Referring to FIG. 24, a terminal first selects an RPT to use for data transmission (2401). The terminal having data to be transmitted selects an RPT for resource blocks to be used by the terminal in the data transmission interval. The terminal selects ₁ transmission subRPT m ₁ to actually transmit data among the M sub-RPTs belonging to the selected RPT and detection sub-RPTs ( M - m ₂ ) to detect peripheral signals (2403).

Thereafter, the UE includes the RPT information used by the UE in the SA message and transmits the same 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 about the transmitter RPT and the detector RPT. According to various embodiments of the present disclosure, the terminal may select an SA resource block using the embodiment of FIG. 23 and transmit an SA message through the selected resource block.

In the data transmission interval, the terminal transmits data through the transmission sub-RPT and senses the energy of the received signal through the remaining detection sub-RPT (2407). The terminal determines whether the energy sensed by the RPT that it is using is greater than or equal to a preset threshold γ (2409).

If the detected energy is greater than or equal to the threshold, the terminal performs RPT reselection. In detail, the terminal generates an arbitrary variable x within the range [0, 1] (2411). If x is less than or equal to the predefined probability P (2413), the UE returns to step 2401 to reselect an RPT to use. In this case, the UE may arbitrarily select one of the available RPTs or select the RPT having the lowest measured energy.

On the other hand, if the detected energy is less than the threshold γ or if the detected energy is greater than the threshold γ but x is greater than the predefined probability P , the terminal transmits data using the RPT currently being used (2415). In this case, in various embodiments of the present disclosure, the terminal may change m ₂ of the detection sub-RPTs to the transmission sub-RPT (2417). The terminal repeats the above RPT selection and reselection until the data transmission is completed (2419). In various embodiments of the present disclosure, RPT selection and reselection may be performed at every D2D communication frame or at a predetermined D2D communication frame interval. According to various embodiments of the present disclosure, if the number of detection unit RPTs becomes 0 due to repetition of the above process before data transmission is completed, the terminal may transmit data through all subRPTs belonging to the selected RPT. .

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

Referring to FIG. 25, a terminal first measures energy of SA resource blocks (2501). A newly participating terminal in the network measures the energy for all SA resource blocks belonging to the SA transmission interval of the first frame starting after the participation. Thereafter, the UE measures energy levels of all SA resource blocks in the SA transmission interval of each frame.

If there is data to be transmitted after * 118 (2503), the UE selects an SA resource block to use based on the measured energy. In more detail, the UE may have a set R _{γ 1} of SA resource blocks whose measured energy is less than or equal to a preset first threshold γ 1 (or lower x ₁ %) and the measured energy is greater than or equal to a preset second threshold γ 2 (or A set R _{γ 2} of SA resource blocks (upper ₂ %) is determined (2505). The first threshold value and the second threshold value may be preset in the terminal by a standard, or determined by the base station according to network conditions, and inform the terminals. In the following embodiments, it will be described as determining the SA resource block that is less than the first threshold value and more than the second threshold value, but according to the implementation, the idea of the present invention may be applied even if it is less than the first threshold value or more than the second threshold value. Can be.

The terminal selects an SA resource block based on the determined set R _γ1 and the set R _γ2 . The UE is identical in frequency to at least one of the at least one SA blocks included in the set R _γ2 among the at least one SA resource blocks included in the determined set R _γ1 , and all SA resource blocks included in the set R _γ2 . And select the SA resource block that does not overlap in time (2507). A specific embodiment 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 use for data transmission (2509). The terminal may arbitrarily select an RPT to use for data transmission. When the mapping relationship between the SA resource block and the RPT is set in advance, the terminal may select an RPT corresponding to the selected SA resource block.

In operation 2511, the UE selects one transmission subRPT m ₁ to actually transmit data and one detection subRPT ( M - m ₂ ) to detect a peripheral signal among M sub-RPTs belonging to the selected RPT.

Thereafter, the UE includes the RPT information used by the UE in the SA message and transmits it to neighboring terminals in the SA transmission interval (2513). The SA message may include information about the RPT, either explicitly or implicitly. The SA message may include information about the transmitter RPT and the detector RPT.

In the data transmission interval, the terminal transmits data through the transmission sub-RPT and senses the energy of the received signal through the remaining detection sub-RPT (2515). The terminal determines whether the energy sensed by the RPT that it is using is greater than or equal to the preset threshold γ (2517).

If the detected energy is greater than or equal to the threshold value, the UE probabilistically performs RPT reselection (2519). A specific embodiment of the UE reselecting the RPT is as described above.

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

According to the above-described embodiments of the present invention, the UEs decode SA messages transmitted in different time slots to obtain RPT information used by different UEs, and thus, select different RPTs to prevent collision of transmission resources. do.

According to an embodiment of the present invention, as shown in FIG. 26, even if two different UEs collide with each other using the same RPT, the UE may avoid collision by arbitrarily reselecting the RPT in the next reselection period. Can be. In addition, as shown in FIG. 27, when UEs transmit SA messages through a randomly selected SA resource selection every cycle, due to Half-Duplex constraints, UEs may collide in a data transmission interval using the same RPT. . According to an 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 the collision in the data transmission interval.

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

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

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

29 shows the SA message decoding times of transmitting terminals according to the distance between terminals. In the proposed scheme of FIG. 29, it is confirmed that adjacent transmission terminals transmit SA signals through different time intervals, thereby decoding about 2.8 times as many SA signals as the prior art in an area within 1000 meters where communication is mainly performed. Can be. Neighboring transmission terminals can improve signal reception performance of 8.5 dB in the data transmission interval compared to the prior art by acquiring RPT information of other neighboring transmission terminals and avoiding the use of the same RPT.

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

31 shows a CDF of the average SINR per terminal that the terminal experiences in the data transmission interval. The proposed technique can prevent collisions between transmitted data signals by detecting the use of the same RPT by the UEs and selecting different RPTs. Therefore, the SINR of the data signal can be improved, and based on this, the average data rate per terminal can be improved by about 20% compared to the prior art as shown in FIG. 32.

33 is a block diagram showing the 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 controller 3303.

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

The controller 3303 may control each component of the terminal 3300 including the communication unit 3301 for the resource selection operation and the D2D transmission and reception according to the present invention. The detailed operation of the controller 3303 has been described above.

Those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential features of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

3300: terminal

3301: communication unit

3303: control unit

Claims (20)

1. As a method of selecting resources of a terminal in device to device communication,

   Selecting a SA transmission resource for SA message transmission 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 portion of the data transmission resource constituting an arbitrary transmission resource pattern in the data transmission interval; 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,

   Determining a first set of at least one radio resource for which the measured energy is less than or equal to a first threshold value;

   Determining a second set of at least one radio resource whose measured energy is greater than or equal to a second threshold; And

   At least one radio resource included in the first set is identical in frequency to at least one of the radio resources included in the second set, and is not identical in time to at least one of the radio resources included in the second set. And selecting a radio resource as the SA transmission resource.
3. The method of claim 2, wherein selecting the SA transmission resource comprises:

   And randomly selecting one of the radio resources included in the SA message transmission interval if there is no radio resource included in the first set.
4. The method of claim 2, wherein selecting the SA transmission resource comprises:

   And randomly selecting one of at least one radio resource included in the first set if there is no radio resource included in the second set.
5. The method of claim 2, wherein selecting the SA transmission resource comprises:

   Among the at least one radio resource included in the first set, if there is no radio resource identical 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 selecting a radio resource that is not identical in time to at least one of the radio resources included in the second set.
6. The method of claim 2, wherein selecting the SA transmission resource comprises:

   Among the at least one radio resource included in the first set, there is no radio resource that is identical in frequency to at least one of the radio resources included in the second set, and at least one of the radio resources included in the second set. If a radio resource that is not identical in time does not exist, selecting a radio resource located in a time where the number of radio resources included in the second set is lowest among at least one radio resource included in the first set; Resource selection method characterized in that.
7. The method of claim 2, wherein selecting the SA transmission resource comprises:

   Of the at least one radio resource included in the first set, among the at least one radio resource included in the first set, if there is no radio resource that is not identical in time to all of the radio resources included in the second set, And selecting a radio resource located in time having the smallest number of radio resources included in the second set.
8. The method of claim 1, wherein selecting the data transmission resource comprises:

   Selecting at least some radio resources for performing the energy measurement among the data transmission resources constituting the arbitrary transmission resource pattern; And

   And performing the energy measurement on the at least some radio resources.
9. The method of claim 1,

   And if the measured energy is greater than or equal to a third threshold, probably reselecting the data transmission resource.
10. The method of claim 9, wherein the reselecting comprises:

    Reducing the number of at least some radio resources for performing the energy measurement.
11. A terminal for performing resource selection in device to device communication,

    Communication unit for transmitting and receiving data; And

    In the Scheduling Assignment (SA) message transmission interval, the SA transmission resource for SA message transmission is selected based on the energy measurement result of each radio resource, and in the data transmission interval, data constituting an arbitrary transmission resource pattern. A control unit for selecting a data transmission resource for data transmission and controlling to transmit the SA message and the data through the selected SA resource and the selected data based on an energy measurement result of at least a portion of the transmission resource; Terminal, characterized in that.
12. The method of claim 11, wherein the control unit,

    Determine a first set of at least one radio resource whose measured energy is less than or equal to a first threshold, determine a second set of at least one radio resource whose measured energy is greater than or equal to a second threshold, Among the at least one radio resource included in the first set, a radio resource that is identical in frequency to at least one of the radio resources included in the second set and is not identical in time to at least one of the radio resources included in the second set. UE is selected as the SA transmission resource.
13. The method of claim 12, wherein the control unit,

    If there is no radio resource included in the first set, the terminal, characterized in that to randomly select one of the radio resources included in the SA message transmission interval.
14. The method of claim 12, wherein the control unit,

    And if there is no radio resource included in the second set, one of at least one radio resource included in the first set.
15. The method of claim 12, wherein the control unit,

    Among the at least one radio resource included in the first set, if there is no radio resource identical 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 selecting a radio resource that is not identical in time to at least one of the radio resources included in the second set.
16. The method of claim 12, wherein the control unit,

    Among the at least one radio resource included in the first set, there is no radio resource that is identical in frequency to at least one of the radio resources included in the second set, and at least one of the radio resources included in the second set. If there is no radio resource that is not identical in time, among the at least one radio resource included in the first set, a radio resource located in time having the smallest number of radio resources included in the second set is selected. Terminal.
17. The method of claim 12, wherein the control unit,

    Of the at least one radio resource included in the first set, among the at least one radio resource included in the first set, if there is no radio resource that is not identical in time to all of the radio resources included in the second set, And selecting a radio resource located in time having the smallest number of radio resources included in the second set.
18. The method of claim 11, wherein the control unit,

    And selecting at least some radio resources for performing the energy measurement from among the data transmission resources constituting the arbitrary transmission resource pattern, and performing the energy measurement on the at least some radio resources.
19. The method of claim 11, wherein the control unit,

    And when the measured energy is equal to or greater than a third threshold value, probably reselects the data transmission resource.
20. The method of claim 19, wherein the control unit,

    And reducing the number of at least some radio resources for performing the energy measurement.

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