WO2015170913A2

WO2015170913A2 - Method and apparatus for transmitting discovery signal for direct d2d communication in wireless communication system

Info

Publication number: WO2015170913A2
Application number: PCT/KR2015/004598
Authority: WO
Inventors: 윤성준
Original assignee: 주식회사 아이티엘
Priority date: 2014-05-09
Filing date: 2015-05-08
Publication date: 2015-11-12
Also published as: WO2015170913A3

Abstract

Provided are a method and an apparatus for transmitting a discovery signal for direct D2D communication in a wireless communication system. A method for transmitting a discovery signal, according to the present description, comprises the steps of: allocating time-frequency resources for D2D discovery signal transmission; generating a D2D discovery signal on the basis of the allocated resources; and transmitting the D2D discovery signal to a D2D receiving device, wherein a cyclic shift value, for DM-RS, comprised in the D2D discovery signal is randomly generated at every periodic transmission of the discovery signal on the basis of a plurality of parameters comprising a parameter which can have a different value at every periodic transmission of the discovery signal.

Description

Method and apparatus for transmitting discovery signal for direct communication between terminals in wireless communication system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting a discovery signal for direct communication between terminals in a wireless communication system.

Device-to-device communication (D2D communication) refers to a communication method of performing direct data transmission and reception between two adjacent terminals without passing through a base station. That is, the two terminals communicate with each other as a source and destination of data.

Although direct communication between terminals may be performed using a communication method using an unlicensed band such as a wireless LAN such as IEEE 802.11 or Bluetooth, such a communication method using the unlicensed band is difficult to provide a planned and controlled service. In particular, performance may be drastically reduced by interference.

Accordingly, there is a need for a direct communication method between terminals for improving performance considering efficient frequency use and interference for service provision.

The present invention provides a method and apparatus for transmitting and receiving a discovery signal for direct communication between terminals in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for configuring a discovery signal in a wireless communication system supporting direct communication between terminals.

Another technical problem of the present invention is to provide a method and apparatus for transmitting a D2D discovery signal with the same slot index value in the periodic transmission of the D2D discovery signal.

Another technical problem of the present invention is to provide an apparatus and method for constructing a D2D discovery signal having different random values.

Another technical problem of the present invention is to provide a method and apparatus for transmitting a D2D discovery signal capable of configuring DM-RS.

According to an aspect of the present invention, there is provided a discovery signal transmission method in a device to device (D2D) transmission terminal for direct communication between terminals in a wireless communication system. The discovery signal transmission method may include allocating a time-frequency resource for transmitting a D2D discovery signal, generating a D2D discovery signal based on the allocated resource, and transmitting the D2D discovery signal to a D2D receiving terminal. In addition, a Cyclic Shift (CS) value for DM-RS included in the D2D discovery signal is based on a plurality of parameters including a parameter that may have a different value for every periodic transmission of the discovery signal. In this case, the transmission may be randomly generated at every periodic transmission of the discovery signal.

According to another aspect of the present invention, a device to device (D2D) transmission terminal for direct communication between terminals in a wireless communication system is provided. The terminal includes a transceiver implemented to transmit a radio signal and a processor selectively connected to the transceiver, wherein the processor allocates a time-frequency resource for transmission of a D2D discovery signal and based on the allocated resource Implemented to generate a D2D discovery signal, the Cyclic Shift (CS) value for the DM-RS included in the D2D discovery signal includes a parameter that may have a different value for every periodic transmission of the discovery signal. It can be implemented to be generated randomly for every periodic transmission of the discovery signal based on a plurality of parameters.

According to the present invention, even if the D2D discovery signal is transmitted with the same slot index value in every periodic transmission of the D2D discovery signal, the D2D discovery signal transmission may be performed to have a different random value for each D2D discovery signal transmission. DM-RS can be set.

1 is a block diagram showing a wireless communication system to which the present invention is applied.

2 is a view for explaining the concept of a cellular network-based terminal-to-terminal direct communication.

3 and 4 schematically show the structure of a radio frame to which the present invention is applied.

5 shows a conceptual diagram of resource allocation when a D2D super-period is not defined.

6 shows a conceptual diagram of resource allocation when a D2D super-period is defined.

7 shows a flow of a method for transmitting a D2D discovery signal according to the present invention.

8 is a flowchart illustrating transmission and reception of a D2D discovery signal according to the present invention.

9 is a block diagram illustrating a structure of a terminal for transmitting a D2D discovery signal according to the present invention.

Hereinafter, some embodiments 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 used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

The present specification describes a communication network, and the work performed in the communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in

In addition, the present disclosure provides a system for efficiently operating a licensed band or inter-system interference, and direct communication between terminals operated or provided in the system environment may support quality of service (QoS), and frequency reuse (frequency) reuse can increase the frequency utilization efficiency and increase the communication distance. In such a direct communication between terminals in a licensed band, that is, in a direct communication between terminals based on cellular communication, a resource of a terminal is allocated at a base station, and the allocated resource may use a cellular uplink channel. In the terminal-to-device direct communication, there is intra-cell communication or inter-cell communication. Direct communication between terminals between cells can be implemented based on cooperative communication between two base stations.

Referring to FIG. 1, the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data. The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides a communication service for a specific geographic area or frequency area and may be called a site. The site may be divided into a plurality of

regions

15a, 15b, and 15c, which may be called sectors, and the sectors may have different cell IDs.

The UE 12 may be fixed or mobile and may have a mobile station (MS), a mobile terminal (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms. The base station 11 generally refers to a station communicating with the terminal 12, and includes an evolved-nodeb (eNodeB), a base transceiver system (BTS), an access point, an femto base station, a femto eNodeB, and a household It may be called other terms such as a base station (Home eNodeB: HeNodeB), a relay, a remote radio head (RRH), and the like.

Cells

15a, 15b, and 15c should be interpreted in a comprehensive sense indicating some areas covered by the base station 11, and encompass all of the various coverage areas such as megacells, macrocells, microcells, picocells, and femtocells. to be.

Hereinafter, downlink refers to a communication or communication path from the base station 11 to the terminal 12, and uplink refers to a communication or communication path from the terminal 12 to the base station 11. . In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system 10. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used. These modulation techniques demodulate signals received from multiple users of a communication system to increase the capacity of the communication system. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme transmitted using different times or a frequency division duplex (FDD) scheme transmitted using different frequencies.

The layers of the radio interface protocol between the terminal and the base station are based on the lower three layers of the Open System Interconnection (OSI) model, which is well known in the communication system. It may be divided into a second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.

There are several physical channels used in the physical layer. The physical downlink control channel (PDCCH) is a resource allocation and transmission format of a downlink shared channel (DL-SCH), a resource of an uplink shared channel (UL-SCH). Resource allocation of upper layer control messages, such as allocation information, random access response transmitted on a physical downlink shared channel (PDSCH), and transmission power control for individual terminals in any terminal group : TPC) can carry a set of commands. A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs.

Control information of the physical layer mapped to the PDCCH is referred to as downlink control information (hereinafter referred to as DCI). That is, DCI is transmitted through the PDCCH. The DCI may include an uplink or downlink resource allocation field, an uplink transmission power control command field, a control field for paging, a control field for indicating a random access response (RA response), and the like.

FIG. 2 is a diagram for explaining the concept of a cellular network-based terminal-to-terminal direct communication (Device to Device communication, D2D communication).

Referring to FIG. 2, a cellular communication network including a first base station 210, a second base station 220, and a first cluster 230 is configured.

In this case, the first to second terminals 211 and 213 belonging to a cell generated by the first base station 210 communicate with each other through a normal access link (cellular link) through the first base station. Meanwhile, the first terminal 211 belonging to the first base station 210 may perform D2D communication with the fourth terminal 221 belonging to the second base station 220. The D2D link may be performed between devices having the same cell as the serving cell, or may be made between devices having different cells as the serving cell.

In addition, the

terminals

232 and 233 existing in the first cluster 230 perform communication in synchronization with the cluster header 231. In addition, the third terminal 213 belonging to the first base station 210 may perform D2D communication with the second terminal 232 in the first cluster 230.

3 and 4, a radio frame includes 10 subframes. One subframe includes two slots. The time (length) of transmitting one subframe is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

One slot may include a plurality of symbols in the time domain. For example, in the case of a wireless system using Orthogonal Frequency Division Multiple Access (OFDMA) in downlink (DL), the symbol may be an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and an SC in an uplink (UL) In the case of a wireless system using Single Carrier-Frequency Division Multiple Access (FDMA), the symbol may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol. Meanwhile, the representation of the symbol period in the time domain is not limited by the multiple access scheme or the name.

The number of symbols included in one slot may vary depending on the length of a cyclic prefix (CP). For example, one slot may include seven symbols in the case of a normal CP, and one slot may include six symbols in the case of an extended CP.

A resource element (RE) represents the smallest time-frequency unit to which a modulation symbol of a data channel or a modulation symbol of a control channel is mapped. A resource block (RB) is a resource allocation unit and includes time-frequency resources corresponding to 180 kHz on the frequency axis and 1 slot on the time axis. Meanwhile, a resource block pair (PBR) refers to a resource unit including two consecutive slots on the time axis.

In a wireless communication system, it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. The process of restoring a transmission signal by compensating for distortion of a signal caused by a sudden change in channel environment is called channel estimation. In addition, it is also necessary to measure the channel state (channel state) for the cell to which the terminal belongs or other cells. In general, a reference signal (RS) that is known between a terminal and a transmission / reception point is used for channel estimation or channel state measurement.

The reference signal is generally transmitted by generating a signal from a sequence of reference signals. In the reference signal sequence, one or more of various sequences having excellent correlation characteristics may be used. For example, pseudo-noise (PN) such as Constant Amplitude Zero Auto-Correlation (CAZAC) sequences such as Zadoff-Chu (ZC) sequences, m-sequences, Gold sequences, and Kasami sequences. ) May be used as the sequence of the reference signal, and various other sequences having excellent correlation characteristics may be used depending on the system situation. In addition, the reference signal sequence may be used by cyclic extension or truncation to adjust the length of the sequence, and may be various forms such as binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK). May be modulated and mapped to a resource element.

Hereinafter, the uplink reference signal will be described.

The uplink reference signal may be divided into a demodulation reference signal (DMRS) and a sounding reference signal (SRS). DMRS is a reference signal used for channel estimation for demodulation of a received signal. DMRS may be combined with transmission of PUSCH or PUCCH. The SRS is a reference signal transmitted by the terminal to the base station for uplink scheduling. The base station estimates an uplink channel based on the received sounding reference signal and uses the estimated uplink channel for uplink scheduling. SRS is not combined with transmission of PUSCH or PUCCH. The same kind of base sequence can be used for DMRS and SRS. Meanwhile, precoding applied to DMRS in uplink multi-antenna transmission may be the same as precoding applied to PUSCH. Cyclic shift separation is a primary scheme for multiplexing DMRS. In the 3GPP LTE-A system, the SRS may not be precoded and may also be an antenna specified reference signal.

The PUSCH DMRS sequence r ^(λ) _PUSCH (·) according to the layer λ∈ {0, 1, ..., ν-1} may be defined by Equation 1.

Equation 1

In Equation 1, m = 0, 1, and n = 0, 1, ..., M _sc ^RS -1. In addition, M _sc ^RS = M _sc ^PUSCH . Here, M _sc ^RS is the number of subcarriers for the uplink reference signal, M _SC ^PUSCH is the number of subcarriers for the PUSCH. Orthogonal sequence w ^(λ) (m) may be determined according to Table 2 described below.

Cyclic shift (CS) α ^λ = 2πn _{cs, λ} / 12 in slot n _S , where n _cs may be defined by Equation 2.

Equation 2

In Equation 2, n ⁽¹⁾ _DMRS may be determined according to a cyclicShift parameter provided by a higher layer. Table 1 shows an example of n ⁽¹⁾ _DMRS determined according to the cyclicShift parameter.

Table 1

cyclicShift	n	⁽¹⁾ _DMRS
0	0
One	2
2	3
3	4
4	6
5	8
6	9
7	10

In Equation 2, n ⁽²⁾ _{DMRS, λ} may be determined by a DMRS cyclic shift field in an uplink-related DCI format for a transport block according to a corresponding PUSCH transmission. Table 2 shows an example of n ⁽²⁾ _{DMRS, λ} determined according to the DMRS cyclic shift field.

TABLE 2

n _PN (n _s ) may be defined by Equation 3.

Equation 3

c (i) is a binary pseudo-random sequence and may have a value of 0 or 1 for each i. In addition, c (i) may be applied on a cell-specific basis. The pseudo random sequence c (i) may be initialized with c _init at the start of each radio frame. c _init is not set if N _ID ^csh_DMRS is set from a higher layer or from a PUSCH transmission corresponding to retransmission of a transport block based on a random access response grant or a random access procedure.

Has a value of, otherwise

Has the value of.

The vector of the reference signal may be precoded by Equation 4.

Equation 4

In Equation 4, P is the number of antenna ports used for PUSCH transmission. W is a precoding matrix. P = 1, W = 1, ν = 1 for PUSCH transmission using a single antenna port. Also, P = 2 or 4 for spatial multiplexing.

DMRS sequence for each antenna port used for PUSCH transmission

Is multiplied by an amplitude scaling factor β _PUSCH and

Are mapped in order. The set of physical resource blocks used for mapping is the same as the set of physical resource blocks used for corresponding PUSCH transmission. Within the subframe, the DMRS sequence may first be mapped to a resource element in an increasing direction in the frequency domain and in a direction in which the slot number increases. The DMRS sequence may be mapped to a fourth SC-FDMA symbol (SC-FDMA symbol index 3) in the case of a normal CP and a third SC-FDMA symbol (SC-FDMA symbol index 2) in the case of an extended CP.

Recently, a method for performing D2D communication between devices outside network coverage for the purpose of public safety has been studied. For example, the fifth terminal 231 may transmit a D2D synchronization signal (D2DSS) as shown in FIG. 2.

The purpose and coverage of applying D2D communication are as shown in Table 3 below.

TABLE 3

	Area within network coverage	Out of network coverage area
Discovery	Non public safety & public safety requirements	Public safety only
Direct Communication	At least public safety requirements	Public safety only

The D2D UE may find out whether there is another D2D UE capable of communicating with itself within or outside the network coverage. This operation is also called D2D discovery. For D2D discovery, the D2D UE transmits a discovery signal to another D2D UE, and the other UE can find the D2D UE using the discovery signal. In the present invention, a terminal for transmitting a D2D discovery signal is defined as a D2D transmitting terminal (Tx UE) and a terminal for receiving a D2D discovery signal is called a D2D receiving terminal (Rx UE).

In the D2D communication, the UE may transmit a randomly selected discovery resource for each discovery period. For example, the discovery period and the amount of discovery resources within the network coverage may be set by the base station eNodeB. In addition to network coverage, it may be set based on a period and an offset set in a transmitting terminal and fixed from a pre-configured or configured nominal transmission probability ( The discovery resource may be transmitted based on a fixed or adaptive transmission probability.

The time axis duration of the discovery resource is 1 ms or more (it may consist of a plurality of 1 ms according to the size of the MAC PDU (Medium Access Control Protocol Data Unit), and may be composed of consecutive D2D subframes). It is used for single transmission of the discovery MAC PDU given by. A time division duplex (TDD) specific subframe may be defined separately. The PDU is a unit of data processed by each layer, and the discovery MAC PDU is a unit of data processing a discovery resource in the MAC layer.

Repetitive transmission (both neighboring and non-adjacent) of a discovery MAC PDU given by the terminal may be performed within one discovery period. For example, the terminal may perform random selection only on the first resource in the discovery resource set that may be used for repeated transmission of the discovery MAC PDU, and may be determined in association with the selection of the first resource for other resources. The terminal may perform random selection for each resource in the discovery resource set. The maximum value of repeated discovery of MAC PDUs may also be defined.

5 and 6 are schematic conceptual diagrams of resource allocation for D2D discovery according to the present invention. 5 shows a conceptual diagram of resource allocation when a D2D super-period is not defined, and FIG. 6 shows a conceptual diagram of resource allocation when a D2D super-period is defined.

Referring to FIG. 5, a resource region in which a D2D discovery signal exists may be defined as a discovery resource. One discovery resource may include one or two subframes. The discovery resource is present in the D2D discovery resource pool, and the D2D discovery resource pool may be transmitted in one discovery period. The discovery resource pool may exist at the location where the discovery cycle begins, as shown in FIG. 5. FIG. 5 illustrates an example in which UE1, UE2, and UE3 perform D2D communication using one discovery resource in the discovery resource pool.

Also, referring to FIG. 6, one D2D discovery super-period may include a plurality of D2D discovery periods. Even within one D2D discovery super-cycle, there may be a discovery cycle including discovery resources and a discovery cycle not including discovery resources.

5 and 6, the parameters used in the present invention may be defined as follows, respectively.

T _{D2D_DS} represents a period of D2D discovery and may have a value of, for example, 160ms, 320ms, 640ms, 1280ms, 2560ms, 5120ms, and the like. _{D2D_DS} indicates an offset of the D2D discovery signal and may have a value between 0 and T _{D2D_DS} -1. D _{D2D_DS} represents a duration or length on a time axis of a D2D discovery resource pool (also referred to as a discovery resource pool or discovery resource region), for example, 16 ms or 32 ms. , 64ms, and so on. p represents the transmission probability of the D2D discovery signal, and may have a value of 0.25, 0.5, 0.75, 1.0, and the like. d _{D2D_DS} indicates a period (or length) on a time axis of a D2D discovery resource, and may have a value of 1 ms or 2 ms, for example.

As described above, the time axis period (or length) of the discovery resource is 1 ms or more (it may be composed of a plurality of 1 ms depending on the size of the MAC PDU, and may be composed of consecutive D2D subframes). It is used for single transmission of a given discovery MAC PDU. A time division duplex (TDD) specific subframe may be defined separately.

N _{D2D_DS} indicates the number of D2D discovery resource iterations, that is, the number of times a discovery signal is transmitted in one D2D discovery resource pool. For example, N _{D2D_DS} may have a value of 1 to 4. As described above, repetitive transmission (both neighboring and non-adjacent) of a discovery MAC PDU given by the terminal may be performed within one discovery period. For example, the terminal may perform random selection only on the first resource in the discovery resource set that may be used for repeated transmission of the discovery MAC PDU, and may be determined in association with the selection of the first resource for other resources. The terminal may perform random selection for each resource in the discovery resource set. The maximum value of repeated discovery of MAC PDUs may also be defined.

n _{D2D_DS} indicates an index for D2D discovery resource repetition. n _{D2D_DS} applies only to independent iterations and has a value of n _{D2D_DS} = 0 for non-independent iterations. n _{D2D_DS} may have a value of 0, 1, ..., N _{D2D_DS} -1. N ^D2D_DS _RB represents the number of resource blocks (RBs) used in one D2D discovery resource pool. For example, 44 RBs may exist within 10 MHz of BW (= 50 RBs).

N _{D2D_DS_period} indicates the number of D2D discovery periods in one D2D discovery super-cycle when there is a D2D discovery super-period. _{D2D_DS_period} n denotes an index (index) value of the N _{D2D_DS_period,} and has a value from 0 to N -1 _{D2D_DS_period.}

Referring to Equation 2, n _cs may be determined by three values. One of them can be obtained through DCI, one can be obtained through high layer signaling, and the other can be generated through pseudorandom sequence by PCID (or VCID) and slot number as shown in Equation 3. have. At this time, the pseudorandom sequence may be initialized at the start of each radio frame.

In order to transmit the D2D discovery signal, it may be considered to use a Cyclic Shift (CS) value that is randomly determined for every transmission of the D2D discovery signal. In this case, a parameter value indicated through DCI or a parameter value indicated by higher layer signaling (n ⁽¹⁾ _DMRS ) may use one fixed value or may use a pre-defined value. Can be used. On the other hand, the CS value needs to be configured such that the CS (Cyclic Shift) value can be randomly determined every transmission of the D2D discovery signal through a value generated through the pseudorandom sequence shown in Equation 2.

However, as shown in Equation 3, if the value generated through the pseudorandom sequence is made in a situation in which periodic transmission of the D2D discovery signal has the same slot index value, a random value is not used for every transmission of the D2D discovery signal. There is a problem that the same value is used. This is because the pseudorandom sequence is generated by slot information and is initialized at the start of each radio frame. Therefore, in order to prevent such a phenomenon, even if the D2D discovery signal is transmitted in a situation having the same slot index value, it is necessary to configure to have a different random value for each transmission of each D2D discovery signal.

Hereinafter, a resource allocation method for the D2D discovery signal will be described. One embodiment of the present invention is a resource allocation method for a D2D discovery signal when a D2D super-period is not defined, and another embodiment of the present invention is a D2D discovery signal when a D2D super-period is defined Resource allocation method for.

Embodiments of the present invention provide for a D2D discovery signal configured to have a different random value for each transmission of each D2D discovery signal even if every periodic transmission of the discovery signal has the same slot index value. It provides a resource allocation scheme.

Hereinafter, a first embodiment will be described.

The first embodiment is a resource allocation method using a system frame number (SFN) without defining a D2D super-period, that is, a parameter that may have a different value for every periodic transmission of a discovery signal. A system frame number (SFN) is used, and by generating the CS value for the DM-RS included in the discovery signal by the parameters including this parameter, different random CS values are applied to each periodic transmission of the discovery signal. Can be.

방법 1) PCID(또는 VCID) 대신 SSID(Synchronization Source ID)를 사용하여 수학식 3을 변형Method 1) Equation 3 is modified by using a Synchronization Source ID (SSID) instead of a PCID (or VCID).

In Equation 3, the SSID, which is a parameter for the D2D synchronization source ID, may be used instead of the PCID (or VCID). However, the SSID may be an ID based on PCID (or VCID) in network coverage in-coverage or at edge-of-cell-coverage, and out-coverage of network coverage. In this case, the ID may be based on an independent synchronization source (ISS) ID.

1)One) 방법 1-1Method 1-1

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 5 instead of Equation 3.

Equation 5

In Equation 3, n _PN (n _s ) is generated by slot (n _s ) information. In Equation 5, n _PN (n _f , n _s ) is determined by SFN (n _f ) and slot (n _s ) information. Can be generated by The pseudorandom sequence c (i) of Equation 5 may be initialized by SSID information rather than PCID (or VCID) information, and the initialization period of the pseudorandom sequence is set to 10240 ms, which is the maximum value of SFN, and when SFN = 0. It can be initialized at the beginning of this radio frame. The constant 160 in Equation 5 is a value obtained by multiplying 8 by 20, which is the number of slots constituting one radio frame. C (i) of Equation 5 may be initialized to Equation 6 or Equation 7.

Equation 6

Equation 7

In Equations 6 and 7, N ^SS _ID denotes an SSID.

2)2) 방법 1-2Method 1-2

N ⁽¹⁾ _DMRS and n ⁽²⁾ for determining a _cs value of n in equation (2) for determining a _cs value of n in equation (2) _DMRS, can all be a fixed value with respect to _λ. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 8 instead of Equation 3.

Equation 8

In Equation 8, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 8 may be initialized by SSID information rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. C (i) of Equation 8 may be initialized to Equation 9 or Equation 10.

Equation 9

Equation 10

In Equations 9 and 10, N ^SS _ID represents an SSID. S may be determined according to the number of bits of the SSID, that is, the range of the N ^SS _ID value. For example, if the N ^SS _ID has a value between 0 and 503, it may be set to S = 10.

3)3) 방법 1-3Method 1-3

In Equation 2, a predefined value may be used according to the SFN (n _f ) value for at least one of n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ,} which determine the n _cs value. After subtracting Δ _{D2D_DS} (D2D discovery offset) / 10 'from n _f and _dividing by' T _{D2D_DS} (D2D discovery period) / 10 ',

At 0

Has the value of. This value can be associated with n ⁽¹⁾ _DMRS and / or n ⁽²⁾ _{DMRS, λ} . For example, when T _{D2D_DS} is 2560 ms, for n _f value

May have four values: 0, 1, 2, and 3. Substituting the values of 0, 1, 2, and 3 into λ can be linked to the case where n ⁽²⁾ _{DMRS and λ} are 0, 6, 3, and 9, respectively. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

As another example, for a value of n _f when T _{D2D_DS} is 1280 ms

May have 8 values of 0, 1, 2, 3, 4, 5, 6, and 7. Substituting this in the DMRS cyclic shift value in Table 2 can be linked to the case where n ⁽²⁾ _{DMRS, λ} values are 0, 6, 3, 4, 2, 8, 10, 9, respectively. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 11 instead of Equation 3.

Equation 11

In Equation 11, n _PN (n _s ) may be generated by slot (n _s ) information, as in Equation 3. C (i) of Equation 11 may be generated by SSID information rather than PCID (or VCID) information. The pseudorandom sequence may be initialized at the beginning of each radio frame. c (i) may be initialized to Equation 12 or Equation 13.

Equation 12

Equation 13

In Equations 12 and 13, N ^SS _ID represents an SSID.

방법 2) PCID(또는 VCID)를 사용하지 않고 수학식 3을 변형Method 2) Equation 3 is modified without using PCID (or VCID)

4) Method 2-1

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 14 instead of Equation 3.

Equation 14

In Equation 3, n _PN (n _s ) is generated by slot (n _s ) information. In Equation 14, n _PN (n _f , n _s ) is determined by SFN (n _f ) and slot (n _s ) information. Can be generated by The pseudorandom sequence c (i) of Equation 14 may be initialized by SSID information rather than PCID (or VCID) information, and the initialization period of the pseudorandom sequence is set to 10240 ms, which is the maximum value of SFN, and when SFN = 0. It can be initialized at the beginning of this radio frame. In Equation 14, the constant 160 is a value obtained by multiplying 8 by 20, which is the number of slots constituting one radio frame. c (i) may be initialized as c _init = △ _ss or c _init = 1.

5)5) 방법 2-2Method 2-2

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 15 instead of Equation 3.

Equation 15

In Equation 15, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 15 may be initialized by SFN (n _f ) rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. C (i) of Equation 15 is c _init = n _f -2 ⁵ + Δ _ss or c _init = n _f. Can be initialized to

6)6) 방법 2-3Method 2-3

At 0

May have four values: 0, 1, 2, and 3. Substituting the values of 0, 1, 2, and 3 into λ may have four values of 0, 1, 2, and 3. Assuming that the DMRS cyclic shift value is 0 and substituting the values of 0, 1, 2, and 3 into λ, n ⁽²⁾ _{DMRS and λ} values can be linked to 0, 6, 3, and 9, respectively. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

As another example, for a value of n _f when T _{D2D_DS} is 1280 ms

N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 16 instead of Equation 3.

Equation 16

In Equation 16, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 11 may be initialized by SSID information rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. c (i) may be initialized as c _init = △ _ss or c _init = 1.

Hereinafter, a second embodiment will be described.

The second embodiment may define a D2D super-period and have a resource allocation method using n _{D2D_DS_period} (index of D2D discovery period), that is, have a different value for every periodic transmission of a discovery signal. The parameter n _{D2D_DS_period} , which is an index corresponding to the index of the period of the discovery signal, is used as a parameter, and by generating the CS value for the DM-RS included in the discovery signal by the parameters including this parameter, Different random CS values may be applied to each transmission.

Method 1) Equation 3 is modified by using a Synchronization Source ID (SSID) instead of a PCID (or VCID).

1)One) 방법 1-1Method 1-1

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 17 instead of Equation 3.

Equation 17

In Equation 3, n _PN (n _s ) is generated by slot (n _s ) information, but in Equation 17, n _PN (n _{D2D_DS_period,} n _s ) is n _{D2D_DS_period} (index of D2D discovery period) and slot (n _s ) information. The pseudorandom sequence c (i) of Equation 5 may be initialized by SSID information rather than PCID (or VCID) information, and the pseudorandom sequence may be initialized at the start of each D2D super-period. have. In Equation 17, the constant 160 is a value obtained by multiplying 8 by 20, which is the number of slots constituting one radio frame. C (i) of Equation 17 may be initialized to

Equation

18 or 19.

Equation 18

Equation 19

In

Equations

18 and 19, N ^SS _ID represents an SSID.

2)2) 방법 1-2Method 1-2

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 20 instead of Equation 3.

Equation 20

In Equation 20, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 8 may be initialized by SSID information rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. C (i) of Equation 20 may be initialized to Equation 21 or 22.

Equation 21

Equation 22

In Equation 21 and Equation 22, N ^SS _ID represents an SSID. S may be determined according to the number of bits of the SSID, that is, a range of N ^SS _ID values. For example, if the N ^SS _ID has a value between 0 and 503, it may be set to S = 10.

3) 방법 1-33) Method 1-3

In Equation 2, a predefined value may be used according to the value of n _{D2D_DS_period} (index of D2D discovery period) for at least one of n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ,} which determine an n _cs value. n _{D2D_DS_period} (index of D2D discovery period) may have a value from 0 to N _{D2D_DS_period} (number of D2D discovery periods included in one D2D super-cycle) -1, which is n ⁽¹⁾ _DMRS and / or n ⁽²⁾ can be associated with _{DMRS, λ} . For example, when n _{D2D_DS_period} has four values of 0, 1, 2, and 3, substituting the values of 0, 1, 2, and 3 into λ results in n ⁽²⁾ _{DMRS and λ} being 0 and 6, respectively. , 3, 9 can be linked. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

As another example, when n _{D2D_DS_period} has 8 values of 0, 1, 2, 3, 4, 5, 6, and 7, and substituting it for the DMRS cyclic shift in Table 2, the value of n ⁽²⁾ _{DMRS, λ} is Can be linked to the case of 0, 6, 3, 4, 2, 8, 10, 9 respectively. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 23 instead of Equation 3.

Equation 23

In Equation 23, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 23 may be initialized by SSID information rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. c (i) may be initialized to (24) or (25).

Equation 24

Equation 25

In Equation 24 and Equation 25, N ^SS _ID represents an SSID.

Method 2) Set n _PN without using PCID (or VCID)

4) Method 2-1

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 24 instead of Equation 3.

Equation 26

In Equation 3, n _PN (n _s ) is generated by slot (n _s ) information, but in Equation 24, n _PN (n _{D2D_DS_period,} n _s ) is n _{D2D_DS_period} (index of D2D discovery period) and slot (n _s ) information. The pseudorandom sequence c (i) of Equation 26 may be initialized using fixed c _init instead of using PCID (or VCID) information, and may be initialized at the beginning of every D2D super-period. have.

The constant 160 in Equation 24 is a value obtained by multiplying 8 by 20, which is the number of slots constituting one radio frame. c (i) may be initialized as c _init = △ _ss or c _init = 1.

5)5) 방법 2-2Method 2-2

In Equation 2, a fixed value may be used for both n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ} , which determine the n _cs value. For example, n ⁽¹⁾ _DMRS = 0, n ⁽²⁾ _{DMRS, λ} = 0 can be set. N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 25 instead of Equation 3.

Equation 27

In Equation 27, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 25 may be initialized by fixed n _{D2D_DS_period} (index of D2D discovery period) rather than PCID (or VCID) information, where the pseudorandom sequence is initialized at the start of each radio frame. Can be.

C (i) of Equation 27 may be initialized to Equation 28 or Equation 29.

Equation 28

Equation 29

6) 방법 2-36) Method 2-3

In Equation 2, a predefined value may be used according to the value of n _{D2D_DS_period} (index of D2D discovery period) for at least one of n ⁽¹⁾ _DMRS and n ⁽²⁾ _{DMRS, λ,} which determine an n _cs value. n _{D2D_DS_period} (index of D2D discovery period) may have a value from 0 to N _{D2D_DS_period} (number of D2D discovery periods included in one D2D super-cycle) -1, which is n ⁽¹⁾ _DMRS and / or n ⁽²⁾ can be associated with _{DMRS, λ} . For example, when n _{D2D_DS_period} has four values of 0, 1, 2, and 3, substituting the values of 0, 1, 2, and 3 into λ of Table 2 results in n ⁽²⁾ _{DMRS and λ} , respectively. 0, 6, 3, 9 can be linked. At this time, n ⁽¹⁾ _DMRS may be fixed to zero.

N _PN used to generate the D2D discovery signal sequence of Equation 2 may be set by Equation 30 instead of Equation 3.

Equation 30

In Equation 30, n _PN (n _s ) may be generated by slot (n _s ) information as in Equation 3. C (i) of Equation 30 may be initialized by a fixed C _init value rather than PCID (or VCID) information. In this case, the pseudorandom sequence may be initialized at the start of each radio frame. c (i) may be initialized as c _init = △ _ss or c _init = 1.

Referring to FIG. 7, the D2D transmitting terminal allocates a resource for transmitting a D2D discovery signal (S710). In the resource allocation for the D2D discovery signal transmission, the CS value for the DM-RS included in the D2D discovery signal may be according to the method of Equations 5 to 30. That is, n _{D2D_DS_period, which} is a parameter corresponding to a system frame number (SFN) or an index of the period of the discovery signal, may be used as a parameter that may have a different value for every periodic transmission of the discovery signal, and includes this parameter. By generating the CS value for the DM-RS included in the discovery signal by the parameters, different random CS values may be applied to every periodic transmission of the discovery signal.

When a resource for D2D discovery signal transmission is allocated, a D2D discovery signal is generated based on the resource allocation information (S730), and the generated D2D discovery signal is transmitted to the D2D receiving terminal (S750).

Referring to FIG. 8, first, a D2D transmitting terminal allocates a resource for transmitting a D2D discovery signal (S810). In the resource allocation for the D2D discovery signal transmission, the CS value for the DM-RS included in the D2D discovery signal may be according to the method of Equations 5 to 30. That is, n _{D2D_DS_period, which} is a parameter corresponding to a system frame number (SFN) or an index of the period of the discovery signal, may be used as a parameter that may have a different value for every periodic transmission of the discovery signal, and includes this parameter. By generating the CS value for the DM-RS included in the discovery signal by the parameters, different random CS values may be applied to every periodic transmission of the discovery signal.

When a resource for D2D discovery signal transmission is allocated, a D2D discovery signal is generated based on the resource allocation information (S820), and the generated D2D discovery signal is transmitted to the D2D receiving terminal (S830).

The D2D receiving terminal receives the D2D discovery signal transmitted from the D2D transmitting terminal (S840).

The D2D receiving terminal may perform discovery of the D2D transmitting terminal (S850). The process of performing discovery of the D2D transmitting terminal may include selecting a D2D terminal to perform communication through a process such as RE demapping of a signal allocated to a time-frequency resource space.

9 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

Referring to FIG. 9, the terminal 900 includes a transceiver 910, a processor 930, and a memory 950. The memory 950 is connected to the processor 930 and stores various information for driving the processor 930. The transceiver 910 is connected to the processor 930 to transmit and / or receive a radio signal. For example, the transceiver 905 may transmit a D2D discovery signal to another terminal or may receive a D2D discovery signal from another terminal.

Processor 930 implements the proposed functions, processes, and / or methods.

Specifically, when the terminal is used as a terminal for D2D transmission, the processor 930 allocates resources for D2D discovery signal transmission. The processor may include a resource allocation unit. Also as an example, the processor 930 is a cyclic shift for the DM-RS included in the D2D discovery signal based on a plurality of parameters including a parameter that may have a different value for every periodic transmission of the discovery signal. (CS, Cyclic Shift) can be randomly generated for every periodic transmission of the discovery signal. In this case, the processor may include a sequence generator. Here, one of the plurality of parameters may be a SSID (Synchronization Source Identity) which is a parameter for a D2D synchronization source ID. Alternatively, a fixed parameter value may be applied to one or more of the parameters included in the plurality of parameters for every periodic transmission of the discovery signal.

Accordingly, the processor 930 may apply or use a CS value for the DM-RS included in the D2D discovery signal in resource allocation for the D2D discovery signal transmission based on the method of Equation 5 to Equation 30.

As an example, the processor 930 uses a system frame number (SFN) or a parameter corresponding to an index of the period of the discovery signal as nD2D_DS_period as a parameter that may have a different value for every periodic transmission of the discovery signal. By generating the CS value for the DM-RS included in the discovery signal by the parameters including this parameter, different random CS values may be applied to every periodic transmission of the discovery signal.

When the terminal is a terminal for D2D transmission, the processor 930 generates a D2D discovery signal based on resource allocation information for the allocated D2D discovery signal transmission, and performs discovery of the D2D transmitting terminal. The process of performing the discovery of the D2D transmitting terminal by the processor 930 may include selecting a D2D terminal to perform communication through a process such as RE demapping of a signal allocated to a time-frequency resource space. .

The memory 950 may store information about parameters for transmitting the D2D discovery signal according to the present specification and provide information on the parameters for transmitting the D2D discovery signal to the processor 930 according to a request of the processor 930. Can be.

In the exemplary apparatus described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

According to the present invention, even if the periodic transmission of each D2D discovery signal is transmitted in a situation having the same slot index value, the DM for transmitting the D2D discovery signal to have a different random value for the transmission of each D2D discovery signal -RS can be set.

Claims

In a method for transmitting a discovery signal in a device to device (D2D) transmission terminal for direct communication between terminals in a wireless communication system,

Allocating time-frequency resources for transmission of the D2D discovery signal;

Generating a D2D discovery signal based on the allocated resources; And

Transmitting the D2D discovery signal to a D2D receiving terminal;

The Cyclic Shift (CS) value for the DM-RS included in the D2D discovery signal is based on a plurality of parameters including a parameter that may have a different value for every periodic transmission of the discovery signal. The discovery signal transmission method, characterized in that randomly generated for every periodic transmission of.
The method of claim 1,

The parameter that can have a different value for each periodic transmission of the discovery signal is a discovery signal transmission method, characterized in that the system frame number (SFN).
The method of claim 1,

The parameter that may have a different value for every periodic transmission of the discovery signal is a parameter corresponding to the index for the period of the discovery signal.
The method of claim 1,

One of the parameters included in the plurality of parameters is a discovery signal transmission method characterized in that the Synchronization Source Identity (SSID) which is a parameter for the D2D synchronization source ID (Identity).
The method of claim 1,

And a fixed parameter value is applied to at least one of the parameters included in the plurality of parameters at every periodic transmission of the discovery signal.
A device to device (D2D) transmission terminal for direct communication between terminals in a wireless communication system,

A transceiver implemented for transmitting a wireless signal; And

Including a processor that is selectively connected to the transceiver,

The processor is configured to allocate a time-frequency resource for the transmission of the D2D discovery signal and to generate a D2D discovery signal based on the allocated resource,

The Cyclic Shift (CS) value for the DM-RS included in the D2D discovery signal is based on a plurality of parameters including a parameter that may have a different value for every periodic transmission of the discovery signal. The terminal characterized in that it is randomly generated for every periodic transmission of the.
The method of claim 6,

The parameter that can have a different value for each periodic transmission of the discovery signal is a terminal characterized in that the system frame number (SFN).
The method of claim 6,

The parameter that may have a different value for each periodic transmission of the discovery signal is a parameter corresponding to the index for the period of the discovery signal.
The method of claim 6,

One of the parameters included in the plurality of parameters is a terminal characterized in that the Synchronization Source Identity (SSID) which is a parameter for the D2D synchronization source ID (Identity).
The method of claim 6,

The terminal characterized in that a fixed parameter value is applied to one or more of the parameters included in the plurality of parameters for every periodic transmission of the discovery signal.