WO2014010858A1

WO2014010858A1 - Device to device communication method and terminal thereof

Info

Publication number: WO2014010858A1
Application number: PCT/KR2013/005833
Authority: WO
Inventors: 박경민; 윤성준
Original assignee: 주식회사 팬택
Priority date: 2012-07-09
Filing date: 2013-07-02
Publication date: 2014-01-16
Also published as: KR20140007226A

Abstract

The present invention relates to: a method for allowing a terminal to communicate with another terminal by using an uplink wireless resource or a part of the uplink wireless resource; and a terminal thereof.

Description

Communication method between terminals and terminal

The present invention relates to a method for a terminal to communicate with another terminal using an uplink radio resource or a part of an uplink radio resource, and a terminal thereof.

User equipment using an uplink radio resource of an existing mobile communication network, for example, Long Term Evolution (LTE) or LTE-Advanced network, to provide more various services to users and to increase communication capacity through more efficient use of bandwidth. Research on D2D communication (Device to Device communication) supporting direct communication between devices is ongoing.

An object of the present invention is to provide a method and apparatus for reducing the complexity of a terminal sensing task compared to the amount of D2D communication resources and performing communication without interference between terminals or between D2D signals.

According to an embodiment of the present invention, there is provided a method in which a terminal communicates with another terminal, the method comprising: recognizing a radio resource available through carrier sensing; And using the available radio resource corresponding to the first D2D pattern consisting of L pattern subunits (L is a natural number of 1 or more) and F (F is a natural number of 1 or more), thereby identifying its existence. It provides a method of communication between terminals of the terminal sharing the terminal index information that can be notified.

Another embodiment of the present invention is a terminal for communicating with other terminals, which recognizes available radio resources through carrier sensing, and L (L is one or more natural numbers) pattern subunits and F (F) The control unit for generating a D2D pattern consisting of patterns of one or more natural numbers; And a transmitter / receiver sharing terminal index information capable of informing its presence using the available radio resource corresponding to the D2D pattern.

When the number F of the patterns and the number L of the pattern subunits are not equal to each other, or the number F of the patterns and the number L of the pattern subunits are the same, but not a prime number or the number F of the patterns and the pattern subunits When only one of the number L of units is a prime number, the number F of the patterns and P, the smallest prime number larger than the number L of the pattern subunits, are set and the following equation is used to form the number P of the pattern subunits and the number P of the patterns. After generating the second pattern satisfying the PL patterns, the PL pattern subunits are removed, and the F patterns are selected to generate the first D2D pattern including the L pattern subunits and the F patterns.

d_ (p, n) = Mod (np, P)

In the above equation, 0 <= p <= P-1 and 0 <= n <= P-1, and d_ (p, n) means the time axis to which the pattern p is mapped in the pattern subunit n.

According to the present invention described above, it is possible to reduce the complexity of the terminal sensing task compared to the amount of D2D communication resources and to perform communication without interference between terminals or between D2D signals.

1 illustrates an example of a wireless communication system in which a terminal communicates with a base station.

FIG. 2 illustrates operation of each terminal required to perform D2D communication for performing distributed communication according to an embodiment.

3 illustrates a D2D pattern for performing UE index sharing using a standardized pattern.

4 illustrates an example of D2D timing mismatch occurring between terminals synchronized to LTE uplink transmission for the same cell.

5 illustrates an example of timing mismatch when each terminal is synchronized with respect to other uplink points.

6 illustrates an example of overlapping phenomenon between D2D patterns due to timing mismatch when the pattern of FIG. 3 is used.

7 illustrates terminals that are not mutually detectable according to a terminal sensing signal transmission resource.

8 illustrates other examples of the terminal sensing signal transmission D2D patterns.

9 shows the time overlap between patterns due to large timing mismatch.

FIG. 10 illustrates a terminal sensing signal D2D pattern considering interference between patterns due to timing mismatch.

FIG. 11 illustrates a D2D pattern supporting overlap in time of up to 'one transmission interval' size between patterns to improve spectral performance or capacity.

12 is a structure of a D2D pattern.

FIG. 13 illustrates a D2D pattern generated by a generalization formula when L = F = M according to a D2D pattern generation method according to another embodiment.

FIG. 14 illustrates an optimal pattern generated by modifying a D2D pattern when L = F = 4 in FIG. 13.

FIG. 15 illustrates a D2D pattern generated according to a method of generating a D2D pattern according to another embodiment after setting F = 3 and L = 4, P = 5, which is the largest prime number greater than 3 and 4. FIG.

16 illustrates frequency hopping of a D2D pattern according to another embodiment.

FIG. 17 is a conceptual diagram of a method of changing a pattern subunit order through reversal, movement scrambling, and the like between pattern subunits of a D2D pattern according to another embodiment.

18 is a conceptual diagram of a method of generating a plurality of patterns on the same frequency according to another embodiment.

19 is a flowchart in which D2D communication (centralized communication) is performed under the control of a base station.

20 is a flowchart in which D2D communication (distributed communication) is performed by terminal-to-device collaboration without control of a base station.

21 is a block diagram illustrating a configuration of a terminal according to another embodiment.

22 is a block diagram showing a configuration of a base station according to another embodiment.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Referring to FIG. 1, a wireless communication system includes a user equipment (UE) 10 and a base station (BS) 20 that performs uplink and downlink communication with the terminal 10.

In the present specification, the terminal 10 is a comprehensive concept of a terminal in wireless communication. In addition, a user station (UE) in WCDMA, LTE, HSPA, etc., as well as a mobile station (MS) and user terminal (UT) in GSM It should be interpreted as a concept including a subscriber station (SS), a wireless device, and the like.

The base station 20 may generally be a station communicating with the terminal 10, and may be a Node-B, an evolved Node-B, an Sector, a Site, or a BTS. It may be called in other terms such as a base transceiver system, an access point, a relay node, and a radio resource head (RRH).

In addition, the base station 20 is meant to encompass all of the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell, radio resource head (RRH) and relay node communication range.

On the other hand, D2D communication refers to a communication between the UE (User Equipments) in the same cell or adjacent cells to establish a D2D link between each other and directly send and receive data through the D2D link without passing through the base station. Hereinafter, the wireless communication system will be described as an LTE communication system by way of example, but the present invention is not limited thereto and may be applied to any wireless communication system.

In order to establish direct communication between terminals, the location information of each terminal (information on which point in the network is connected) must be shared, and the base station or the central control unit communicates directly between the terminals using the location information of each terminal. Let this be done. In the case of D2D communication in which communication is performed without control of a base station or a central control unit, each terminal (a terminal capable of transmitting or receiving) that is a target of D2D communication may provide information about terminals located within a call range capable of D2D communication. It is necessary to determine whether the D2D communication object exists by collecting the information in advance, and when transmitting D2D communication, information on who the other terminal intends to transmit (transmit) should be separately transmitted to the other terminal. In addition, as in the case of performing communication through the base station or the central control unit, the mutual security code may be shared in advance before the D2D communication is performed.

In order for D2D signals transmitted by many terminals without base station control to be transmitted to multiple terminals without collision between each other, the network configures more than a certain level of 'D2D communication resources' and prevents collisions between D2D communication resources. The terminal performs carrier sensing as appropriate. However, when more than a certain level of radio resources are allocated to the D2D communication resources, there is a problem that the operation of the terminal for detecting the allocated D2D communication resources becomes complicated. In order to solve this problem, the network can reduce the complexity of the terminal sensing by configuring D2D communication resources into a plurality of D2D signal patterns and allowing each terminal to perform a sensing operation on the D2D signal pattern.

An embodiment of the present invention provides a D2D pattern for performing communication without interference between terminals or between D2D signals in a D2D communication in which each terminal performs D2D communication resources search and transmission.

In another embodiment of the present invention, UE 0 distinguishes between a D2D pattern being used by other UEs among D2D resource regions preset through carrier sensing and an unused D2D pattern. The UE 0 selects a D2D radio resource corresponding to an unused D2D pattern and shares index information of the UE 0 through the selected D2D resource.

Just as the UE 0 shares its index information, other UEs may share index information of respective UEs through D2D radio resources corresponding to their D2D patterns. For example, UE 0 may receive a signal including the index information of broadcasted UE 1, and by decoding the received signal, UE 0 may recognize the D2D pattern that UE 1 is using.

D2D communication, which supports direct communication between user terminals using uplink radio resources of a wireless communication system, includes centralized communication in which a base station manages scheduling such as resource allocation and distributed communication without base station control. It can be divided into a hybrid type (hybrid type) and the like combined. Hereinafter, an operation of each UE of D2D communication for performing distributed communication with reference to FIG. 2 will be described, and D2D patterns used for UE recognition and UE index sharing will be described with reference to FIGS. 3 to 18, and FIGS. 19 and 20. The centralized communication and the distributed communication for performing D2D communication using the D2D pattern will be described respectively.

2 illustrates an operation of each terminal for performing D2D communication according to distributed communication according to an embodiment. In FIG. 2, each terminal 12, 14, and 16 corresponds to the terminal 10 of FIG. 1.

As shown in (a) of FIG. 2, each of the

terminals

12, 14, and 16 recognizes a radio resource available through carrier sensing.

As shown in (b) of FIG. 2, each of the

terminals

12, 14, and 16 may use the uplink radio resource or a part of the uplink radio resource of the existing mobile communication network to provide terminal index information that may inform its existence. Send it out. In addition, each of the

terminals

12, 14, and 16 may distinguish between the D2D pattern being used by the terminals and the unused D2D pattern in the preset D2D resource region through carrier sensing. In the present specification, a process of transmitting terminal index information for notifying the existence of each terminal 12, 14, 16 and collecting terminal index information of neighboring D2D terminals is called terminal index sharing. That is, each of the

terminals

12, 14, and 16 selects a D2D resource corresponding to an unused D2D pattern, maps index information of each terminal through the selected D2D resource, and shares the mapped signal (broadcasts). do.

As the terminal 12 shares its index information, the

other terminals

14 and 16 may share index information of each terminal through D2D radio resources corresponding to their D2D patterns. For example, the terminal 12 receives a signal including index information of the broadcasted terminal 14 through a D2D radio resource corresponding to its D2D pattern. The terminal 12 may decode the index information of the received terminal 14.

As shown in (c) of FIG. 2, when the terminal 12 has a target to which information transmission is performed among the neighboring

D2D terminals

14 and 16 recognized through the above-described steps, the terminal 12 may be, for example, a terminal ( 14) transmits its own terminal index and information (which may also include control information).

As shown in (d) of FIG. 2, the terminal 14 receiving the control information and / or data receives the closed loop control information and / or N / Ack based on the received signal. Can be delivered to. Meanwhile, the step according to (d) of FIG. 2 may be omitted.

Since UE index sharing should be protected from interference due to a UE performing centralized uplink communication, for example, cellular communication, communication through a separate radio resource should be performed.

In other words, in order to perform D2D communication, (a) the terminal should identify the location of the radio resource to which the D2D signal transmitted by another terminal is mapped without the BS's instruction, and (b) recognize the UE and the D2D information that transmitted the D2D signal. do. In order for each UE to perform D2D transmission, the UE should recognize the available D2D radio resource and transmit D2D information and its identity information using this radio resource.

In order to perform the above operation, (a) the system divides a radio resource that can be used for D2D communication into a finite number of D2D resource blocks (b) and each terminal determines whether to use each resource block. (C) If the resource block is in use, it determines whether the necessary information is loaded. (D) If the resource block is not used, D2D communication is performed by using the resource block.

When configuring the D2D resource block used in the above-described operation, a multiplexing method for supporting D2D communication to multiple terminals should be considered, and various such as FDM / TDM (frequency domain (division) multiplexing / time domain (division) multiplexing) Multiplexing of schemes can be considered.

It is desirable to be designed for low power communication so as not to cause problems in the existing network operation of D2D communication, and to be designed to have as much coverage as possible to provide useful services. If these two conditions are to be met, it is not suitable to design the D2D signal by Orthogonal Frequency Division Multiple Access (OFDMA), which causes a problem of Peak to Average Power Ratio (PAPR), and also the single carrier frequency of SC-FDMA. Even when designing in a division multiple access scheme, as few as possible, for example, two to four subcarriers may be used or designed as a single-tone.

In consideration of the above factors, when designing a D2D pattern composed of D2D resource blocks, a plurality of D2D patterns may be designed in an FDM scheme in the same time interval.

When a plurality of D2D patterns are designed in FDM format on the same band, each terminal cannot receive D2D signals of other terminals received in the same time zone when transmitting the D2D signal. In the present invention, the same band refers to a radio resource or a set of resources located close to frequencies so that the RF circuit of the UE cannot simultaneously transmit and receive. In the D2D communication of LTE, communication is performed using the LTE uplink band, which means that a plurality of terminals perform D2D communication on the same band when operating in an LTE uplink single carrier environment. Therefore, each terminal transmitting the D2D signal cannot recognize the D2D signal of another terminal in the time domain for transmitting the signal. Therefore, for terminals determined to be able to share information through D2D communication, it is necessary to support terminal detection signal classification through TDM. When designing a TDM type D2D pattern, the D2D pattern should be designed in a narrow band, which limits the amount of radio resources available for D2D communication. Therefore, it is necessary to design a D2D pattern in which TDM and FDM are properly mixed.

Referring to FIG. 3, nine radio resources are allocated to the D2D UE index sharing in the D2D pattern 300. As described with reference to (a) and (b) of FIG. 2, each of the

terminals

12, 14, and 16 selects available radio resources among them through carrier sensing and uses the same for transmitting the terminal index. One radio resource shown in FIG. 3 may be one resource element in an LTE subframe or a bundle of resource elements in time-frequency.

Instead of performing carrier sensing on each of the nine radio resources shown in FIG. 3 and selecting one of the radio resources, a smaller number of D2D patterns 300 are formed using the nine radio resources, and each pattern Through carrier sensing, a resource pattern to be used for the UE index transmission may be selected.

The advantage of this method is that each terminal detects and selects resources to be used for D2D communication. The method selects a resource pattern and selects a resource pattern through all the radio resources included in the pattern according to the amount of radio resources to be transmitted. Alternatively, some may be used to perform D2D communication.

In performing LTE uplink transmission, each terminal 12, 14, and 16 sets a separate TA (Timing Alignment) value for synchronization, and a TA value suitable for an uplink propagation delay. Through the configuration, the uplink transmission of each of the

terminals

12, 14, and 16 reaches the same time at the receiving end.

D2D communication will operate without a separate synchronization signal. Each terminal 12, 14 and 16 performs D2D signal transmission in synchronization with LTE uplink transmission. At this time, since there is no synchronization between the D2D signals of the

terminals

12, 14, and 16, there is a timing misalignment between the D2D signals transmitted by the

terminals

12, 14, and 16. This results in overlapping between patterns.

FIG. 4 illustrates an example of D2D timing mismatch occurring between UEs synchronized to LTE uplink transmission with respect to the same cell. FIG. 5 illustrates timing mismatch when each UE is synchronized with respect to other uplink points. It is an example. 6 illustrates an example of overlapping phenomenon between D2D patterns due to timing mismatch when the pattern of FIG. 3 is used.

As shown in FIG. 4, since the D2D signals of the

terminals

12, 14, and 16 which are synchronized with respect to uplink of LTE or other cellular communication are not synchronized, each terminal 12, 14, and 16 transmits. Timing mismatch occurs between the D2D signals.

As shown in FIG. 5, D2D communication between other uplink points, for example, the base stations 20 of FIG. 1 and the

terminals

12, 14, and 16 synchronized with respect to the RRH 22 connected by the optical cable to the base station 20. If this is done, this timing mismatch can be a serious problem. In a synchronization network with the same subframe index between adjacent points, timing mismatch may occur in a range of 1 symbol duration or less. In particular, when the above operation is performed in an asynchronous network that is not synchronized with subframes, timing mismatch between D2D terminals may be larger than several subframes.

4 and 5, when timing mismatch occurs, D2D signal reception performance is reduced due to interference, and when generating UE sensing signal using SC-FDMA like the existing LTE uplink transmission, SC-FDMA is applied to OFDMA. Compared to the intersymbol interference, the performance of terminal detection may be further degraded. In addition, when a D2D signal received in a section in which a D2D signal is to be transmitted due to a large timing misalignment, a more severe performance degradation may occur in which the D2D signal of the corresponding UE cannot be detected.

When the terminal 12 and the terminal 14 select their own patterns among the patterns of FIG. 3 to perform D2D communication in the communication environment shown in FIGS. 4 and 5, timing mismatches as shown in FIG. 6 may occur. . Since the radio resources used by the terminal 12 and the terminal 14 for D2D communication are arranged on different subbands, when the timing mismatch described above occurs, the terminal 12 and the terminal 14 transmit their D2D signals. It is not possible to receive the D2D signal transmitted by the other terminal during. In other words, in this situation, the terminal 12 and the terminal 14 operate like a half duplex TDD scheme.

When overlapping between patterns occurs due to timing mismatch as shown in FIG. 6, when D2D communication is performed between four terminals as shown in FIG. 7, a specific terminal may not recognize the presence of another counterpart terminal having overlapping patterns. It is very likely.

In order to solve this problem by the above-described TDM / FDM scheme, a plurality of D2D patterns divided in both frequency domain and time domain can be designed and each of these D2D patterns can be utilized as a resource block. According to this method, a plurality of D2D patterns are repeated at regular intervals, and each terminal determines whether the patterns can be used for each pattern through carrier sensing. If there is a D2D pattern that is determined not to be used as a result of carrier sensing, the D2D signal is transmitted using the D2D pattern. In this case, the number of D2D terminals that can be simultaneously connected is determined according to the number of D2D patterns that are set. In this case, a system operating with contention-based access may support a smooth access of the UE only when a large number of D2D patterns are defined.

In order to prevent D2D signal sensing performance degradation due to 'time overlap between patterns' due to timing mismatch shown in FIG. 6, the terminal sensing signal transmission pattern as shown in FIG. 8 may be used.

Referring to FIG. 8, three D2D patterns having a length of 3 in a band available for D2D communication may be designed to be divided in both time / frequency domains. The D2D pattern illustrated in (c) of FIG. 8 is an optimal pattern in which overlapping of patterns occurs only in a time domain corresponding to at most one transmission interval unit regardless of timing mismatch.

8A is an arbitrary pattern in which three D2D patterns are divided in both time / frequency domains in a band usable for D2D communication.

FIG. 8B is a D2D pattern to which a Latin square pattern is applied. In this D2D pattern, time-base overlap between the patterns occurs irregularly, so that randomization gain can be obtained.

In designing the patterns shown in FIGS. 8A and 8B, if timing mismatch does not occur, D2D reception performance deterioration due to 'unrecognition' does not occur, and even if timing mismatch occurs, no interference problem occurs. . However, if a timing mismatch occurs above a certain level, there is still a problem that an 'unrecognized' area occurs, and this pattern has a disadvantage in that the efficiency of D2D communication is greatly reduced.

FIG. 8C is an optimized pattern in which overlap between patterns does not exceed the size of one transmission section unit when overlapping between patterns occurs.

9 shows the time overlap between patterns due to large timing mismatch. In FIG. 9, TMA means timing mismatch.

Referring to FIG. 9, there is more than a certain level of timing misalignment between the terminal 12 and the terminal 14. In this case, the D2D signal transmitted by the terminal 12 and the D2D signal transmitted by the terminal 14 overlap in all transmission intervals, and the terminal 12 and the terminal 14 do not receive the counterpart D2D signal. The timing mismatch problem shown in FIG. 9 occurs because the time difference between the D2D patterns is the same in each D2D pattern.

9 (a) and 9 (b) are examples of a situation in which an overlap between patterns occurs due to timing mismatch between terminals when the patterns of FIGS. 8A and 8B are used.

FIG. 10 illustrates a terminal sensing signal D2D pattern considering interference between patterns due to timing mismatch. In this case, the minimum unit in which the D2D signal can be transmitted in the D2D pattern is called a 'transmission interval unit', and the entire unit in which the D2D signal is transmitted is called a 'pattern unit'.

As shown in FIG. 10, the D2D pattern considering the interference between patterns due to timing mismatch needs to be set such that a time difference between transmissions is different. In the case of using the pattern of FIG. 10, even if a timing mismatch occurs at a predetermined level or more, as shown in FIG. 10B, if an overlap occurs in a time of the maximum 'one transmission interval' size between the patterns, and the length of the D2D pattern is long enough The effects of the overlap can be overcome. However, when the D2D pattern is designed as shown in FIG. 10, the number of radio resources used for the D2D pattern design is further increased, which may cause spectral efficiency and reduced capacity.

Referring to FIG. 11, as in FIG. 10, an overlap of a maximum 'one transmission interval' size occurs between D2D patterns regardless of the magnitude of timing mismatch, while the number of radio resources required to define a D2D pattern of the same length is reduced. . For example, in FIG. 11, the pattern subunit L = 3, the pattern number F = 3, and the number of transmission section units M = 5 constituting one pattern subunit.

12 is a structure of a D2D pattern.

Referring to FIG. 12, the D2D pattern performs one transmission in a pattern subunit 1230 consisting of M transmission interval units 1220 in one pattern unit 1210 and performs a total of L transmissions. Configured to perform. In the 'pattern subunit 1230', different F D2D patterns may be generated. In FIG. 12, the number of pattern subunits 1230 is three, that is, L = 3. In this case, the transmission interval unit 1220 may be one resource element on the LTE subframe or a bundle of two or more resource elements, for example, 4 * 4 resource elements as shown in the lower part of FIG. 12. Can be.

Meanwhile, as described above, in addition to a method of generating a pattern according to a schedule rule, a method of directly finding an optimal pattern may be used. The optimal pattern is pattern overlapping once per L transmission interval units, which is a performance indicator, while pattern overlap occurs only in a time interval corresponding to the size of one transmission interval unit 1210 regardless of the timing mismatch size. And a D2D pattern generating patterns satisfying the conditions of F pattern generation using only a minimum of radio resources. The generation of this optimal pattern can be generated through very complex design tasks or with generalized formulas only for specific L and F values.

For example, only if L and F have the same value, and if L and F are prime numbers or specific values other than prime numbers, the time axis to which the pattern f is mapped in each pattern subunit n is d_ (f , n), the pattern can be generated with L = F = M by setting d_ (f, n) = Mod (nf, M).

FIG. 13 illustrates a D2D pattern generated by a generalized formula when L = F = M according to a D2D pattern generation method according to another embodiment of the present invention.

Referring to FIG. 13, when the time axis d_ (f, n) to which the pattern f is mapped in each subunit is set to d_ (f, n) = Mod (nf, M), L = F = { 3,5}, as shown in (a) and (c) of FIG. 13, overlapping of patterns occurs only in a time section corresponding to one transmission section unit size, thereby generating an optimal pattern. On the other hand, when L and F are not prime numbers and L = F = {4,6}, as shown in FIGS. 13B and 13D, patterns overlap between time intervals corresponding to two transmission interval units. This occurs, making it impossible to generate an optimal pattern.

If L and F are not prime numbers and L = F = 4, the optimal pattern cannot be generated by the above-described constant rule or generalized formula, and thus a part of the pattern needs to be modified to directly generate the optimal pattern as shown in FIG. There is.

The following embodiments provide a D2D pattern that guarantees higher spectral performance by complementing the D2D pattern shown in FIG. 11. In addition, the following embodiments show a sub-optimal performance that shows the same performance as the optimal pattern for various system parameters under various communication environments through a formalized technique, instead of generating an optimal pattern through confirmation according to a case as shown in FIG. 14. Provides a method for generating and transmitting a suboptimum pattern.

As described above with reference to FIG. 13, for L and F having the same value, L = F = M and a method of generating a pattern according to the formula d_ (f, n) = Mod (nf, M) is arbitrary. Has the disadvantage that free pattern design for F and L is impossible. In the above formula, d_ (f, n) means the time axis to which the pattern f is mapped in the pattern subunit n.

As such, when the number of patterns F and the number L of pattern subunits are not equal to each other, or the number of patterns F and L is not the same even if they are not a prime number or if only one of F and L is a prime number, a new D2D pattern generation method may be applied. Can be. Equation d_ (p, n) = Mod (np, P) (0 <= p <= P-1) may be used to generate the new D2D pattern. In the above equation, 0 <= p <= P-1 and 0 <= n <= P-1, and d_ (p, n) means a time axis to which the pattern p is mapped in the pattern subunit n.

In other words, P, the smallest prime number larger than the number F of patterns and the number L of pattern subunits, is set in one of the above-described cases, and the above-described equation d_ (p, n) = Mod (np, P) is used. After the pattern satisfying the number P of the pattern subunits and the number P of the patterns is generated, the PL pattern subunits are removed and the F patterns are selected to generate a D2D pattern composed of L pattern subunits and F patterns. Can be.

For example, in the case of F = 7 and L = 14, the smallest prime number larger than F = 7 and L = 14 is set to P = 17, and P = L` = M` = F` using the set P. Set it. Create a D2D pattern that satisfies the number 17 of the pattern subunits (L` = 17) and the 17 patterns (F` = 17), and remove the three pattern subunits so that L = 14 and F = 7. Seven of the seventeen patterns are selected.

In the above example, a portion consisting of 14 pattern subunits is removed by removing some of the 17 pattern subunits constituting the pattern, and 7 patterns are selected to determine the final pattern. The operation of selecting the pattern and the pattern subunit may be performed so as not to cause an overlap in timing mismatch of the timing mismatch, or the operation may be performed at random. For example, when there is no timing mismatch, the first pattern subunit, in which overlap between transmission units occurs, may be removed, and both end pattern subunits may be sequentially removed. In addition, after removing the pattern subunit, the final pattern may be selected by preferentially erasing the patterns causing overlap between the patterns for the small timing mismatch.

FIG. 15 illustrates a pattern generated according to a D2D pattern generation method according to another embodiment after setting F = 3 and L = 4 to P = 5, which is the largest prime number greater than 3 and 4. FIG.

As shown in FIG. 15, when F = 3 and L = 4, the first largest number of time overlaps per unit of transmission period after generating a pattern after setting P = 5, which is the largest prime number greater than 3 and 4, is generated. Since the pattern subunit (first pattern subunit) is removed and three patterns of five patterns are selected, three D2D patterns having a length of four can be generated. As a result, a D2D pattern is generated in which timing mismatch is zero and no overlap between patterns occurs.

As described with reference to FIG. 15, when the pattern subunit is removed to adjust the size of the pattern, timing mismatch is fixed by using a method of preferentially removing the first pattern subunit and then removing both ends of the pattern subunit. Under less than one environment can generate patterns that do not overlap between patterns.

A method of generating a D2D pattern according to another exemplary embodiment described with reference to FIGS. 14 and 15 is expressed by the following equation.

The transmission time unit used by the f-th pattern in the l-th pattern subunit may be expressed as follows.

[Equation 1]

Time unit = mod ((f + o) x (l + s), P)

Where o is the number of patterns that have an index that takes precedence over pattern f when F patterns are selected from the original pattern group, and s is the number in front of the first pattern subunit when generating a pattern of length L in the original pattern group. The number of pattern subunits removed. o and s may be different values for each f and l, and may have the same value for all f and l depending on the pattern generation method.

For example, o = 0 for all f since the fourth and fifth patterns are removed in FIG. 15, and s = 1 for all transmission pattern subunits since the first pattern subunit is removed from the original pattern group. According to the above equation, the transmission time unit used by the pattern f in each pattern subunit can be expressed as follows.

[Equation 2]

Time unit = (mod ((f + o) x (l + s), P), L + mod ((f + o) x (l + s), P), 2L + mod ((f + o) x (l + s), P),... }

In addition, the resources (k, s) to which the pattern f is mapped with respect to the pattern f can be expressed as follows.

[Equation 3]

k (f) = f + F0 + o

s (f) = (mod (f x l, Mp), L + mod (f x l, Mp), 2L + mod (f x l, Mp),... }

Here, k and l may be indexes of subcarriers and symbols, and may be indexes of a bundle of subcarriers or a bundle of symbols.

When k is an index of a set of subcarriers, k (f) may be expressed by one of the following two equations.

[Equation 4]

k (f) = fN + F0 + o, fN + F0 + o + o1, ..., fN + F0 + o + (N-1)

k (f) = fN + F0 + o + i, fN + F0 + o + i +1, ..., fN + F0 + o + j

I and j are parameters used to set a guard subcarrier between patterns.

In addition, when l is an index of a bundle of symbols, s (f) may be expressed as follows.

[Equation 5]

s (f) = {Jxmod ((f + o) x (l + s), P) + a, Jxmod ((f + o) x (l + s), P) + a + 1, .... , Jxmod ((f + o) x (l + s), P) + b, L + Jxmod ((f + o) x (l + s), P) + a, L + Jxmod ((f + o) x (l + s), P) + a + 1, ...., Jxmod ((f + o) x (l + s), P) + b,... .}

In the D2D pattern generated by the D2D pattern generation method according to another embodiment described above with reference to FIG. 15, overlap between D2D patterns does not occur in all pattern subunits except for a specific pattern subunit. Therefore, as shown in FIG. 16, even if frequency hopping is freely performed on the patterns, overlap between D2D patterns does not occur.

15 and 16, it can be seen that the transmission section units of the second pattern subunit are frequency hopping. When performing frequency hopping, the frequency domain factor may change in the above-described equations. That is, the position of the frequency domain of the radio resource to which the pattern f is mapped may be changed as follows.

[Equation 6]

k (f, l) = q (l) + F0 + o

k (f, l) = q (l) N + F0 + o, q (l) N + F0 + o + 1, ..., q (l) N + F0 + o + (N-1)

k (f, l) = q (l) N + F0 + o + i, q (l) N + F0 + o + i +1, ..., q (l) N + F0 + o + j

Where q (l) is a factor for the frequency hopping pattern corresponding to transmission interval unit l.

In the above-described embodiment, the time axis difference between patterns increases as the pattern subunit index increases, but the present invention is not limited thereto.

Referring to FIG. 17, after designing each pattern subunit such that the differences in the time axis between the patterns are different, the pattern subunit order through reversing, shifting, scrambling, and the like between the pattern subunits. You can create a variety of patterns by changing the way.

In the original D2D pattern shown in (a) of FIG. 17, as shown in (b) of FIG. 17, inversion between the pattern subunits in which the pattern subunits are arranged in reverse order as a whole is performed, or (c) of FIG. As shown in FIG. 17, the pattern subunits of the pattern subunits may be shifted to move between the pattern subunits, or the pattern subunits may be shuffled as shown in FIG. Scrambling may also be performed.

The inversion, movement, and scrambling between the pattern subunits of the D2D pattern described with reference to FIG. 17 may be applied to any D2D pattern described with reference to FIGS. 9, 10, and 14 as well as the D2D pattern described with reference to FIG. 15. .

Meanwhile, in the above embodiments, a case where each D2D pattern is defined in a different subcarrier has been described, but the present invention is not limited thereto.

Referring to FIG. 18, a D2D pattern according to another embodiment may be a D2D pattern including F 'patterns smaller than F by performing frequency overlap on the remaining portions on the same frequency in F patterns.

As shown in (a) and (b) of FIG. 18, the number F of the patterns and the number L of the pattern subunits are not the same or the number F of the patterns and the number L of the pattern subunits are the same. Even if it is not a prime number or if only one of the number F of the patterns and the number L of the pattern subunits is a prime number, the smallest prime number P larger than the number F of the patterns and the number L of the pattern subunits is set and the equation d_ (p, n) = Mod (np, P) is used to generate a pattern that satisfies the number P of pattern subunits and the number P of patterns, then the PL pattern subunits are removed and the F patterns are selected and L patterns The D2D pattern composed of pattern subunits and F patterns may be generated.

When designing the D2D pattern, select the smallest prime number larger than F and L as P, generate a D2D pattern consisting of P patterns of length P, remove the first pattern subunit, and select four patterns to select the D2D pattern. Create

Thereafter, as shown in FIGS. 18C and 18D, frequency overlap may be performed on the remaining portions on the same frequency. As illustrated in (c) of FIG. 18, frequency overlap may be performed for two frequencies. In addition, as illustrated in FIG. 18D, frequency overlap may be performed at one frequency.

A method of generating a plurality of patterns on the same frequency according to another embodiment described with reference to FIG. 18 may be applied to any D2D pattern described with reference to FIGS. 9, 10, 14, etc. as well as the D2D pattern described with reference to FIG. 15. Applicable

After the terminal index sharing is performed between the terminals using the radio resources according to the D2D pattern described with reference to FIGS. 3 to 18, each terminal 12, 14, and 16 may have a radio resource to be transmitted through D2D communication. In this case, information transmission may be performed through a D2D link using a radio resource defined by the D2D pattern described with reference to FIGS. 3 to 18 or by using a separate radio resource.

19 and 20 are diagrams illustrating overall D2D communication including a step in which terminals are allocated resources for use in D2D communication after terminal index sharing between terminals described with reference to FIG. 2 is performed.

19 is a flowchart in which D2D communication (centralized communication) is performed under the control of a central processing unit or a base station.

Each terminal 12, 14, and 16 recognizes available radio resources through carrier sensing (S1910).

Next, each terminal 12, 14, 16 selects a part of an uplink radio resource or an uplink radio resource of the existing mobile communication network for sharing the terminal index (S1920). In operation S1920, one of the D2D patterns of the D2D patterns of FIGS. 3 and 5, 8, 9, 10, 11, 13, and 18 may be generated.

For example, as described with reference to FIG. 15, if the number F of the patterns and the number L of the pattern subunits are not equal to each other, or the number L of the pattern subunits and the number L of the pattern subunits are the same, If not, or if only one of the number F of the patterns and the number L of the pattern subunits is a prime number, the smallest prime number P larger than the number F of the patterns and the number L of the pattern subunits is set and the equation d_ (p, n) = Mod (np, P) is used to generate a pattern that satisfies the number P of the pattern subunits and the number P of the patterns, and then the PL pattern subunits are removed and the F patterns are selected to form L pattern subunits. And the D2D pattern consisting of the F patterns may be generated.

In operation S1920, the pattern f may be generated in each pattern subunit by Equation 2 or the pattern f may be mapped to the resource (k, s) by one of Equations 3 to 6.

Next, each of the

terminals

12, 14, and 16 transmits the terminal index information for notifying of its existence using the D2D radio resource corresponding to the D2D pattern generated in step S1920, and receives the terminal index information of the neighboring D2D terminals. The terminal index sharing process is performed (S1930).

Each terminal 12, 14, and 16 reports information on a D2D terminal located in its vicinity, for example, a searched terminal index, to the base station 20 through the LTE uplink (S1940).

The base station 20 determines the combination of the D2D network that can be connected between the terminals through this information. When the terminal intends to perform D2D communication, it reports to the base station 20 through the LTE uplink which information (type and / or size) to which terminal to transmit.

The base station 20 allocates a radio resource to be used for transmitting D2D information to a terminal requesting D2D transmission in consideration of D2D connection and LTE uplink scheduling between terminals (S1960). In step S1960, the base station 20 is an indicator for performing a D2D reception for the terminal to perform the D2D reception (information about the terminal performing the D2D transmission and / or radio resources used for D2D communication and / or D2D Control information including an indicator indicating that the reception should be performed).

The specific terminal 12 to perform the D2D transmission performs the D2D transmission with the terminal 14 that is the target of the D2D transmission (S1970).

Referring to FIG. 20, each terminal 12, 14, 16 recognizes a radio resource that it can use through operations such as carrier sensing (S2010).

Next, each terminal 12, 14, 16 selects a part of an uplink radio resource or an uplink radio resource of the existing mobile communication network for sharing the terminal index (S2020). In operation S1920, it means generating one of the D2D patterns of FIGS. 3 and 5, 8, 9, 10, 11, 13 and 18.

In other words, in operation S2020, each terminal 12, 14, and 16 may generate a pattern f in each pattern subunit by Equation 2 or assign the pattern f to a resource (k, s) by one of Equations 3 to 6. Can be mapped.

Next, each of the

terminals

12, 14, and 16 transmits the terminal index information for notifying its existence using the D2D radio resource corresponding to the D2D pattern generated in step S2020 and collects the terminal index information of the neighboring D2D terminals. The terminal index sharing process is performed (S2030).

Next, the first terminal 12 to perform D2D transmission transmits a signal including D2D information transmission, for example, terminal index information, to the second terminal 14 through a radio resource (S2040). If the terminal index sharing process (S2030) uses a signal that is broadcast casting, the terminal index transmission process (S2040) has a difference of using a dedicated signal.

If it is determined that the D2D reception is possible, the second terminal 14 having received the terminal index transmits a response to the first terminal 12 (S2050).

Thereafter, the first terminal 12 performs D2D communication with the second terminal 14 (S2070).

The centralized D2D communication described with reference to FIG. 19 or the distributed communication described with reference to FIG. 20 and a combination thereof may be referred to as spectral efficiency for data transmission and low D2D control overhead. There are other advantages, and an appropriate method may be used according to the type of service of D2D communication and the network configuration.

Referring to FIG. 21, the terminal 2100 includes a controller 2110 and a transceiver 2120.

The controller 2110 recognizes a radio resource available through carrier sensing and selects a part of an uplink radio resource or an uplink radio resource of an existing mobile communication network to share a terminal index. One of the D2D patterns of the 8, 9, 10, 11, 13 to 18 may be generated.

The transmitter / receiver 2120 transmits terminal index information for notifying its presence using D2D radio resources corresponding to the D2D pattern generated in operation S1920 and performs a terminal index sharing process for receiving terminal index information of neighboring D2D terminals. Perform.

In the case of centralized communication as shown in FIG. 19, the transceiver 2120 reports information about a D2D UE located near itself, for example, a searched UE index, to the base station through LTE uplink or as shown in FIG. 20. As described above, in the case of distributed communication, the D2D reception is transmitted to a terminal to perform D2D reception and a response is received from the terminal.

The transceiver 2120 performs a D2D transmission with a terminal, which is a target of D2D transmission.

Referring to FIG. 22, the base station 2200 includes a transceiver 2200 and a controller 2220.

The transceiver 2210 receives information required for D2D communication from each terminal and transmits control information to each terminal. As illustrated in FIG. 19, the transmitter / receiver 2210 receives information about a D2D terminal located in its vicinity, for example, a searched terminal index through LTE uplink, from a specific terminal to perform D2D transmission in the case of centralized communication. do.

The controller 2220 allocates a radio resource to be used for transmitting D2D information to a terminal requesting D2D transmission in consideration of D2D connection and LTE uplink scheduling between terminals. The controller 2220 may instruct the terminal to perform the D2D reception to perform the D2D reception by transmitting an indicator indicating to perform the D2D reception.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics 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.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority under Patent Application No. 10-2012-0074757, filed with South Korea on July 9, 2012, pursuant to Section 119 (a) (35 USC § 119 (a)). All content is incorporated by reference in this patent application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims

In a method in which a terminal communicates with another terminal,

Recognizing a radio resource available through carrier sensing; And

Sharing the terminal index information for indicating the presence of the user by using the available radio resource corresponding to the first device-to-device (D2D) pattern including L pattern subunits and F patterns. ,

The L and F is a natural number of one or more, the method of communication between terminals of the terminal, characterized in that for generating the first D2D pattern overlap between each pattern does not exceed one transmission interval unit size.
The method of claim 1,

When the number F of the patterns and the number L of the pattern subunits are not equal to each other, or the number F of the patterns and the number L of the pattern subunits are the same, but not a prime number or the number F of the patterns and the pattern subunits If only one of the number L of units is prime,

P, which is the smallest minority among the number F of the patterns and the number L larger than the number L of the pattern subunits, is set, and the following equation is used to generate a second D2D pattern satisfying the number P of the pattern subunits and the number P of the patterns. And then the PL pattern subunits are removed and the F patterns are selected to generate a first D2D pattern composed of the L pattern subunits and the F patterns.

d_ (p, n) = Mod (np, P)

In the above equation, 0 <= p <= P-1 and 0 <= n <= P-1, and d_ (p, n) means a time axis to which the pattern p is mapped in the pattern subunit n.
The method of claim 2,

The removing of the P-L pattern subunits is characterized in that when there is no timing mismatch, the first pattern subunit, which overlaps between transmission units, is removed and both end pattern subunits are sequentially removed.
The method of claim 2,

The transmission period units included in at least one pattern subunit of the L pattern subunits are frequency hopping.
The method of claim 2,

The L pattern subunits of the terminal, characterized in that the pattern subunit order is reversed through reversing, shifting, scrambling between the pattern subunits.
The method of claim 1,

The first D2D pattern is a D2D pattern composed of F 'patterns (F' is one or more natural numbers) smaller than F by performing frequency overlap on the remaining portions of the F patterns on the same frequency. The terminal to terminal method of the terminal.
As a terminal to communicate with other terminals,

A controller for recognizing a radio resource available through carrier sensing and generating a first device-to-device (D2D) pattern composed of L pattern subunits and F patterns; And

And a transmitter / receiver configured to share terminal index information capable of informing its presence using the available radio resource corresponding to the first D2D pattern.

The L and F is a natural number of one or more, the terminal for performing the terminal-to-device communication for generating a first D2D pattern overlap between each pattern does not exceed the size of one transmission interval unit.
The method of claim 7, wherein

When the number F of the patterns and the number L of the pattern subunits are not equal to each other, or the number F of the patterns and the number L of the pattern subunits are the same, but not a prime number or the number F of the patterns and the pattern subunits If only one of the number L of units is prime,

The control unit is a second D2D satisfying the number P of the pattern subunits and the number P of patterns by setting the smallest prime number P among the number F of the patterns and the number greater than the number L of the pattern subunits. After the pattern is generated, PL pattern subunits are removed and F patterns are selected to generate the first D2D pattern including L pattern subunits and F patterns. Terminal.

d_ (p, n) = Mod (np, P)

In the above equation, 0 <= p <= P-1 and 0 <= n <= P-1, and d_ (p, n) means a time axis to which the pattern p is mapped in the pattern subunit n.
The method of claim 8,

In the removal of the PL pattern subunits, when there is no timing mismatch, a terminal performing inter-terminal communication, which removes a first pattern subunit in which overlap between transmission units occurs and sequentially removes both end pattern subunits. .
The method of claim 8,

The first D2D pattern is a terminal for performing terminal-to-terminal communication, characterized in that the frequency unit is a frequency hopping of the transmission interval units included in at least one pattern subunit of the L pattern subunits.
The method of claim 8,

The L pattern subunits in the first D2D pattern are terminals that perform inter-terminal communication, characterized in that the pattern subunit order is changed through reversing, shifting, and scrambling between the pattern subunits. .
The method of claim 8,

The first D2D pattern is a D2D pattern composed of F 'patterns (F' is one or more natural numbers) smaller than F by performing frequency overlap on the remaining portions of the F patterns on the same frequency. Terminal for performing terminal-to-terminal communication.