KR102333372B1 - Method and apparatus for wireless communication considering d2d signal - Google Patents

Abstract

The present invention relates to a method for performing UL HARQ by a terminal in a wireless communication system supporting D2D communication, comprising the steps of: receiving D2D configuration information including information on a monitoring interval for monitoring a D2D signal; Receiving an uplink grant from a base station, generating the PUSCH based on the uplink grant and transmitting it to the base station, and PHICH indicating HARQ ACK/NACK information for the PUSCH transmission from the base station and receiving the D2D signal received in the monitoring period without receiving the PHICH when the transmitted timing and the monitoring period overlap.

Description

Wireless communication method and apparatus considering D2D signal {METHOD AND APPARATUS FOR WIRELESS COMMUNICATION CONSIDERING D2D SIGNAL}

The present invention relates to wireless communication, and more particularly, to a wireless communication method and apparatus in consideration of a Device to Device (D2D) signal.

In long term evolution (LTE) of the 3rd generation partnership project (3GPP), an effort is being made to satisfy the need for public safety by allowing support of a proximity service (ProSe). Meanwhile, as a discovery technology and broadcast communication are added to a proximity-based service, a technology providing compatibility is required in an LTE system. A representative of proximity-based application technology is device-to-device (D2D) communication. D2D communication is a communication method that has been possible since the days of analog radios, and has a very long history.

However, D2D communication in a wireless communication system is differentiated from the existing communication between terminals. D2D communication in a wireless communication system refers to communication in which data is directly exchanged between terminals without going through an infrastructure (eg, a base station) of the wireless communication system. That is, the two terminals perform communication while becoming a source and a destination of data, respectively. D2D communication provides the advantage that limited radio resources can be efficiently used, the load of the wireless communication system can be reduced, and communication can be performed without a network.

Although D2D communication may be performed using a communication method using an unlicensed band such as wireless LAN or Bluetooth, the communication method using such an unlicensed band has a disadvantage in that it is difficult to provide a planned and controlled service. In particular, performance may be drastically reduced due to interference. On the other hand, direct communication between terminals operated or provided in an environment in which interference between licensed bands or systems is controlled can support Quality of Service (QoS), and frequency use efficiency can be increased through frequency reuse, and communication The possible distance can be increased.

In D2D communication in the licensed band, that is, cellular communication-based D2D communication, a resource for D2D communication may be allocated through a base station, and cellular uplink spectrum or uplink subframes may be used as the allocated resource.

Meanwhile, D2D discovery and communication can be operated independently of cellular communication, and in some cases, a D2D signal from another terminal when a WAN (Wide Area Network) signal is transmitted through a DL spectrum from a base station for a D2D terminal. may be transmitted. In this case, the terminal having a single transceiver chain may have a problem that it is impossible to transmit or receive signals through several frequency bands at the same time. Therefore, it is necessary to determine which signal is to be processed with priority, and in this case, there is a need to define the handling of the remaining signals of lower priority as well.

An object of the present invention is to provide a wireless communication method and apparatus in consideration of a D2D signal.

Another technical object of the present invention is to provide a method and apparatus for preventing collision of a D2D signal and a WAN signal.

Another technical object of the present invention is to provide a method and apparatus for determining which signal is to be prioritized when a WAN signal of a D2D signal collides.

Another technical object of the present invention is to provide a method and apparatus for determining a processing procedure for a lower priority signal when a D2D signal and a WAN signal collide.

Another technical object of the present invention is to provide a method and apparatus for defining a PHICH processing procedure when reception of a D2D signal and reception of a physical HARQ indicator channel (PHICH) occur simultaneously.

Another technical object of the present invention is to provide a method and apparatus for defining a UL HARQ operation when a D2D monitoring period and a PHICH reception timing overlap.

According to an aspect of the present invention, there is provided a method of performing an Uplink (UL) Hybrid Automatic Repeat Request (HARQ) by a terminal in a wireless communication system supporting D2D (Device to Device) communication. The method includes the steps of receiving D2D configuration information including information on a monitoring interval for monitoring a D2D signal, receiving an uplink grant indicating transmission of a PUSCH from a base station, based on the uplink grant generating the PUSCH and transmitting it to the base station, and when the timing at which the PHICH indicating HARQ ACK/NACK information for the PUSCH transmission is transmitted from the base station overlaps the monitoring period, the PHICH is not received, and receiving the D2D signal received in the monitoring section.

Also, in the present invention, the method may further include determining that the HARQ ACK/NACK information for the PUSCH transmission indicates ACK.

Alternatively, in the present invention, the method may further include determining that the HARQ ACK/NACK information for the PUSCH transmission indicates NACK.

According to the present invention, it is possible to define the overall operation of the terminal and the base station according to the priority in a situation where the D2D signal and the WAN signal collide, and the influence on the WAN performance can be minimized even when the terminal performs D2D communication. have.

In addition, according to the present invention, from the terminal point of view, D2D discovery and D2D communication can be supported through limited terminal capabilities (eg, based on a single transceiver chain), and various physical channels carrying signals received from the WAN (e.g. For example, by providing a method of receiving and processing PHICH), WAN performance can be corrected.

In addition, according to the present invention, by more effectively controlling PHICH reception in a D2D environment, an uplink (UL) HARQ operation can be efficiently implemented and unnecessary consumption of radio resources in the network can be reduced.

The UE may transmit/receive D2D signals according to priorities, and overall efficiency of D2D discovery and D2D communication may be guaranteed.

1 shows a wireless communication system to which the present invention is applied.
2 shows an example of the structure of a MAC entity at the terminal end.
3 is a diagram for explaining the concept of cellular network-based D2D communication applied to the present invention.
4 shows an example of a DL subframe in which a UE cannot receive a PHICH.
5 shows an example of a measurement gap in a WAN system;
6 illustrates a UL HARQ operation according to an example of the present invention.
7 illustrates a UL HARQ operation according to another example of the present invention.
8 and 9 show UL HARQ operations in consideration of carrier aggregation.
10 is a flowchart illustrating a method of performing UL HARQ when a D2D monitoring period and a PHICH reception timing overlap according to the present invention.
11 is a flowchart illustrating an operation of a terminal according to the present invention.
12 is an example showing a block diagram of a terminal according to the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the embodiments of the present specification, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted. Hereinafter, the simultaneous occurrence of transmission or reception of signals includes occurrence on a time axis in which transmission or reception of signals overlaps.

1 shows a wireless communication system to which the present invention is applied.

Referring to FIG. 1 , a 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 11 (evolved-NodeB, eNB). Each base station 11 provides a communication service for a specific cell (cell) (15a, 15b, 15c). A cell may again be divided into a plurality of areas (referred to as sectors).

The terminal 12 (User Equipment, UE) may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a PDA. (personal digital assistant), wireless modem (wireless modem), may be called other terms such as a handheld device (handheld device). The base station 11 may be referred to by other terms such as a base station (BS), a base transceiver system (BTS), an access point, a femto base station, a home nodeB, and a relay. A cell is meant to encompass various coverage areas such as megacells, macrocells, microcells, picocells, and femtocells.

Hereinafter, downlink (DL) means communication from the base station 11 to the terminal 12 , and uplink (UL) means communication from the terminal 12 to the base station 11 . In the downlink, the transmitter may be a part of the base station 11 , and the receiver may be a part of the terminal 12 . In the uplink, the transmitter may be a part of the terminal 12 , and the receiver may be a part of the base station 11 . There is no limitation on the multiple access method applied to the wireless communication system. 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 , various multiple access schemes such as OFDM-CDMA can be used. For uplink transmission and downlink transmission, a time division duplex (TDD) scheme transmitted using different times may be used, or a frequency division duplex (FDD) scheme transmitted using different frequencies may be used.

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 widely known in communication systems. 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.

The physical layer is connected to a media access control (MAC) layer, which is an upper layer, through a transport channel. Data is transferred between the MAC layer and the physical layer through a transport channel. Transport channels are classified according to how data is transmitted through the air interface. In addition, data is transmitted through physical channels between different physical layers (ie, between the physical layers of the terminal and the base station). The physical channel may be modulated in an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time and frequency and a space generated by a plurality of antennas as radio resources.

Several physical channels may be used in the physical layer, and the physical channels may be mapped to the radio frame and transmitted. As a downlink physical channel, PDCCH (Physical Downlink Control Channel)/EPDCCH (Enhanced PDCCH) is HARQ (Hybrid Automatic Repeat) related to resource allocation of a Paging Channel (PCH) and a Downlink Shared Channel (DL-SCH) to the UE and DL-SCH Request) information. The PDCCH/EPDCCH may carry an uplink grant informing the UE of resource allocation for uplink transmission. There is a difference between the PDCCH and the EPDCCH in a mapped resource region. A DL-SCH is mapped to a Physical Downlink Shared Channel (PDSCH). A Physical Control Format Indicator Channel (PCFICH) informs the UE of the number of OFDM symbols used for the PDCCH, and is transmitted in every subframe. A Physical Hybrid ARQ Indicator Channel (PHICH) is a downlink channel and carries a Hybrid Automatic Repeat reQuest (HARQ) Acknowledgment (ACK)/Non-acknowledgement (NACK) signal that is a response of uplink transmission. The HARQ ACK/NACK signal may be referred to as a HARQ-ACK signal.

As an uplink physical channel, a Physical Random Access Channel (PRACH) carries a random access preamble. PUCCH (Physical Upnlink Control Channel) includes HARQ-ACK, which is a response of downlink transmission, channel status information (CSI) indicating a downlink channel state, for example, CQI (Channel Quality Indicator), PMI (precoding matrix index), It carries uplink control information such as a precoding type indicator (PTI) and a rank indicator (RI). A Physical Uplink Shared Channel (PUSCH) carries an Uplink Shared Channel (UL-SCH).

Meanwhile, there is an automatic repeat request (ARQ) among techniques for increasing the reliability of wireless communication. ARQ is to retransmit the data signal from the transmitter when the receiver fails to receive the data signal. In addition, there is also a hybrid automatic repeat request (HARQ) combining FEC (Forward Error Correction) and ARQ. A receiver using HARQ basically attempts error correction on a received data signal and determines whether to retransmit using an error detection code. The error detection code may use CRC (Cyclic Redundancy Check). If an error in the data signal is not detected through the CRC detection process, the receiver determines that decoding of the data signal is successful. In this case, the receiver transmits an acknowledgment (ACK) signal to the transmitter. When an error of the data signal is detected through the CRC detection process, the receiver determines that decoding of the data signal has failed. In this case, the receiver sends a Not-Acknowledgment (NACK) signal to the transmitter. The transmitter may retransmit the data signal when the NACK signal is received.

In uplink (UL) HARQ, when the base station transmits a PDCCH including a UL grant for the terminal's PUSCH transmission, the terminal transmits UL data through the PUSCH at a predetermined timing, and the base station transmits HARQ ACK/NACK for this at a predetermined timing It refers to a process of repeating the process of transmitting through the PHICH for a certain period until the terminal receives an ACK signal from the base station.

The MAC layer can control the HARQ process, and transport blocks provided as a physical channel on a transport channel of a MAC SDU (Service Data Unit) belonging to a mapping between a logical channel and a transport channel and a logical channel , TB) can be multiplexed or demultiplexed. The MAC layer provides services to the RLC layer through logical channels. The logical channel can be divided into a control channel for transmitting control domain information and a traffic channel for transmitting user domain information. For example, as services provided from the MAC layer to a higher layer, there is data transfer or radio resource allocation.

2 shows an example of the structure of a MAC entity at the terminal to which the present invention is applied.

Referring to FIG. 2 , the MAC entity may perform functions such as logical channel prioritization, multiplexing/de-multiplexing, HARQ, and random access control. Specifically, the MAC entity may perform mapping between logical channels and transport channels, and is delivered from one or different logical channels to a physical channel on a transport channel (to be delivered to the physical layer on) The transport channels) may perform multiplexing of MAC SDUs onto transport blocks (TB). The MAC entity may perform demultiplexing of MAC SDUs from one or different logical channels to transport blocks TB delivered from the physical layer on the transport channels. The MAC entity may perform scheduling information reporting. The MAC entity may perform error correction through HARQ. In this case, the part performing error correction through the HARQ may be referred to as a HARQ entity. In addition, the MAC entity may perform priority handling between terminals through dynamic scheduling, and the MAC entity may perform priority handling between logical channels of one terminal. The MAC entity may perform logical channel prioritization and may perform transport format selection.

The MAC entity receives and processes data transmission service, HARQ feedback signaling, scheduling request signaling, measurement (e.g., channel quality indication (CQI)), etc. from the physical layer, which is a lower layer. have.

On the other hand, recently, using the transmission/reception technology of the wireless communication system in the frequency band or other bands of the wireless communication system, but without going through an infrastructure (eg, a base station), it supports D2D communication that directly exchanges user data between terminals. measures are being considered. D2D communication enables wireless communication to be used in areas other than the limited wireless communication infrastructure and can reduce the network load of the wireless communication system. In addition, D2D communication provides advantages such as being able to transmit disaster information to terminals even when base stations do not operate smoothly in situations such as war or disaster.

A terminal transmitting a signal based on D2D communication is defined as a transmitting terminal (Tx UE), and a terminal receiving a signal based on D2D communication is defined as a receiving terminal (Rx UE). The transmitting terminal may transmit a discovery signal, a D2D control signal, or a D2D data signal, and the receiving terminal may receive a discovery signal, a D2D control signal, or a D2D data signal. The roles of the transmitting terminal and the receiving terminal may be changed. Meanwhile, a signal transmitted by the transmitting terminal may be received by two or more receiving terminals. In addition, signals transmitted by two or more transmitting terminals may be selectively received by one receiving terminal. The D2D signal may be transmitted through an uplink resource. Accordingly, the D2D signal may be mapped on the uplink subframe and transmitted from the transmitting terminal to the receiving terminal, and the receiving terminal may receive the D2D signal on the uplink subframe.

3 is a diagram for explaining the concept of cellular network-based D2D communication applied to the present invention.

Referring to FIG. 3 , a cellular communication network including a first base station 310 , a second base station 320 , and a first cluster 330 is configured. The first terminal 311 and the second terminal 312 belonging to the cell provided by the first base station 310 perform communication through a normal access link (cellular link) through the first base station 310 . This is an In-coverage-single-cell D2D communication scenario. Meanwhile, the first terminal 311 belonging to the first base station 310 may perform D2D communication with the fourth terminal 321 belonging to the second base station 320 . This is an In-coverage-multi-cell D2D communication scenario. Also, the fifth terminal 331 belonging to the outside of the network coverage may create one cluster 330 together with the sixth terminal 332 and the seventh terminal 333 and perform D2D communication with them. This is an out-of-coverage D2D communication scenario. Here, the fifth terminal 350 may operate as a cluster head (CH) of the first cluster. The cluster head is a terminal (or unit) that can be referenced for at least synchronization purposes, and refers to a terminal in charge of allocating resources from time to time according to different purposes. The cluster header may include an Independent Synchronization Source (ISS) for synchronization of an out-of-coverage terminal. Also, the third terminal 313 may perform inter-terminal communication with the sixth terminal 332 , which is a partial-coverage D2D communication scenario.

D2D communication includes direct communication for transmitting and receiving D2D control information and/or user data, and a D2D discovery procedure and a D2D synchronization procedure may be performed to support the D2D communication. D2D communication can be used for various purposes. For example, D2D communication within network coverage and D2D communication outside network coverage may be used for public safety. D2D communication outside of network coverage may be used only for public safety.

In order to perform D2D data transmission/reception through D2D communication, D2D control information must be transmitted/received between terminals. The D2D control information may be referred to as a scheduling assignment (SA) or a D2D SA. The D2D Rx UE may perform D2D data reception based on the SA. The SA is, for example, NDI (New Data indicator), target ID (Target Identification), RV indicator (Redundancy Version indicator), MCS indication (Modulation and Coding Scheme Indication), transmission resource pattern (Resource Pattern for Transmission, RPT) It may include at least one of an instruction and a power control instruction.

Here, the NDI informs whether the current transmission is a repetition of data, that is, a retransmission or a new one. The receiver may combine the same data based on NDI. The target ID indicates IDs for terminals to which the corresponding data MAC PDU is intended to be delivered. According to the ID value, the data MAC PDU may be transmitted in a groupcast or broadcast method, or even in a unicast method according to the configuration thereof. The RV indicator indicates a redundancy version by specifying different starting points in a circular buffer for reading the encoded buffer. Based on the RV indicator, the transmitting terminal may choose various redundancy versions for repeated transmission of the same packet. The MCS indication indicates an MCS level for D2D communication. However, the MCS for D2D communication (e.g. SA or Data) may be fixed to QPSK. The transmission resource pattern indication indicates to which time/frequency physical resource the corresponding D2D data is allocated and transmitted. The power control instruction will be a command for the terminal receiving the corresponding information to control the appropriate amount of power for the corresponding D2D transmission.

From the perspective of the Tx terminal, the Tx terminal may operate resource allocation for D2D communication in two modes.

Mode 1 is a case in which a base station or a relay node (hereinafter referred to as a base station may include a relay node) schedules specific resource(s) for D2D communication. That is, in mode 1, a specific resource(s) used for transmitting D2D data and D2D control information of a Tx terminal is designated by a base station or a relay node. On the other hand, mode 2 is a case in which the terminal directly selects specific resource(s) from the resource pool. That is, in mode 2, the Tx terminal directly selects specific resource(s) for transmitting D2D data and D2D control information.

The D2D communication capable terminal supports at least mode 1 for in-coverage D2D communication. The D2D communication capable terminal supports at least mode 2 for out-of-coverage or edge-of-coverage D2D communication.

In the case of mode 1, the location of the resource(s) for transmission of D2D control information and the location of the resource(s) for transmission of D2D data are given by the base station. That is, for D2D SA and data transmission, the same grant is given to the UE by transmitting (E)PDCCH from the base station in a DCI message format having the same size as DCI format 0. In mode 2, transmission of D2D control information (eg SA) ) for the resource pool (resource pool) can be pre-configured (pre-configured) and / or semi-statically (semi-statically) allocated (allocated). In this case, the Tx terminal may select a resource for D2D control information from the resource pool for transmission of D2D control information.

D2D discovery is performed on D2D discovery resources. For example, the D2D UE may transmit a discovery signal through a randomly selected discovery resource (hereinafter referred to as a D2D discovery resource) within each discovery period. For example, the discovery period and discovery resource within the network coverage may be configured by the base station. Outside of network coverage, a discovery resource may be selected based on a period and an offset set in the transmitting terminal, and from a pre-configured or configured nominal transmission probability A discovery resource may be selected based on a fixed or adaptive transmission probability. One D2D discovery resource may consist of n contiguous PRBs and one subframe in frequency. In this case, frequency hopping between slots in the subframe is not performed. The n may be, for example, 2 or 3. A set of D2D resources may be used for repeated transmission of a MAC PDU (Medium Access Control Protocol Data Unit) (hereinafter, a discovery MAC PDU) carrying a discovery signal within the discovery period. There may be a plurality of D2D discovery resource sets in one discovery period, and D2D discovery resources in one D2D discovery resource set may be adjacent or non-adjacent to each other in the time axis, and frequency hopping (inter-subframe frequency hopping) may be performed in the frequency axis. can be placed on the basis of From the viewpoint of the receiving terminal, it is possible to monitor the discovery signal in the resource pool for D2D reception.

Meanwhile, D2D discovery may be divided into type 1 and type 2B according to a discovery section. Type 1 indicates the periodicity of resources allocated for D2D discovery signal transmission in a cell. Type 2B indicates the spatiality of resources for reception of a D2D discovery signal from a cell. Multiple discovery intervals of various lengths may be used. In Type 2B, the network may configure a specific resource for transmission of the D2D discovery signal.

On the other hand, D2D discovery and communication can be operated independently of WAN (Wide Area Network) communication, and in some cases, when the WAN signal is transmitted from the base station through the DL spectrum for the D2D terminal, the D2D signal is transmitted from another terminal. may be WAN (Wide Area Network) refers to a network that provides voice/data traffic to mobile terminals by configuring wide coverage in the existing cellular network, such as WCDMA, LTE, WiMax, etc. This may be the case. Such radio access networks are commonly referred to as WANs. Since a terminal having a single transceiver chain cannot transmit or receive signals through multiple frequency bands at the same time, when a D2D signal is transmitted from another terminal at the time when a WAN signal is transmitted through a DL spectrum from a base station It should be defined which signal is to be processed with priority, and in this case, the handling of the remaining signals of lower priority should also be defined.

Specifically, in the present invention, in the D2D terminal, the D2D (Rx) resource pool for receiving the D2D signal and the PHICH reception timing carrying the HARQ-ACK signal overlap in the time axis.

When a D2D (Rx) resource pool is set at the reception timing of (WAN) PHICH corresponding to PUSCH transmission in the D2D terminal having a single transceiver chain (eg, type 1/2 D2D discovery), the D2D signal (ex. D2D discovery, SA or D2D data), and may not receive PHICH. In particular, this is because, when the corresponding D2D signal is a type 1/2 discovery Tx/Rx signal, a mode 2 SA Tx/Rx signal, etc., it may have a higher priority than a DL signal (ex. PHICH) on the WAN DL spectrum.

4 shows an example of a DL subframe in which a terminal to which the present invention is applied does not receive a PHICH. 4 assumes that uplink transmission and downlink transmission are based on a Frequency Division Duplex (FDD) scheme.

Referring to FIG. 4 , UL subframes #n+7 to #n+10 are set as a D2D Rx resource pool, that is, a monitoring period for a D2D signal (hereinafter may be referred to as a D2D monitoring period), and the UE is a UL subframe An initial UL grant indicating PUSCH transmission in n+4 was received from the base station (or network) in DL subframe n. Here, the D2D monitoring section may include a Tx/Rx resource set/resource pool for D2D discovery or D2D communication. The UE transmits an initial PUSCH to the base station in UL subframe #n+4 based on the UL grant, and the base station generates a HARQ ACK/NACK signal indicating whether the PUSCH has been successfully received, and a DL subframe #n+8 is transmitted to the terminal. This UL HARQ supports synchronized HARQ in the WAN system. That is, the timing at which the initial UL grant is transmitted from the base station, UL data is transmitted from the terminal, and the HARQ ACK/NACK signal is again indicated by the base station are all determined.

However, as described above, since the UL subframes #n+7 to #n+10 are set as the D2D monitoring period, and the UE needs to receive (or blind decode) the D2D signal, the UE is in the DL subframe #n+8. PHICH reception cannot be expected. If it is original, the UE acquires HARQ ACK/NACK information based on the PHICH received from the physical layer of UL subframe #n+8 based on the synchronization UL HARQ timing, and transmits the HARQ ACK/NACK information to the upper layer (ex MAC layer), but since the PHICH was not received in UL subframe #n+8, the UL HARQ procedure cannot be properly performed. This is similar to the case where a measurement gap is configured in the terminal.

5 shows an example of a measurement gap in a WAN system to which the present invention is applied.

In general, the UE performs measurement to determine the presence or absence of neighboring cells and signal strength. In this case, neighboring cells existing in the intra-frequency transmit signals through the same frequency band as the current serving cell. Accordingly, it is possible to measure neighboring cells while performing transmission/reception with the serving cell. However, since neighboring cells existing in the inter-frequency transmit signals through a frequency band different from that of the serving cell, the UE temporarily suspends transmission/reception with the current serving cell during the measurement gap and restarts the RF (Radio Frequency) chain. By tuning (retuning), a signal for a frequency band identified as a possibility that neighboring cells exist is received. If the UE does not have more than one (receive) RF chain, it performs a measurement operation existing in the inter-frequency by using the periodic measurement gap.

The measurement gap is divided into a first gap pattern repeating at a period of 40 ms and having a length of 6 ms and a second gap pattern repeating at a period of 80 ms and having a length of 6 ms, as shown in Table 1 below. In general, any one of the two patterns may be set in the terminal by the network.

Gap Pattern Id MeasurementGap Length ( MGL , ms ) Measurement Gap Repetition Period
( MGRP , ms ) Minimum available time for inter-frequency and inter-RAT measurements during 480ms period
( Tinter1 , ms ) Measurement Purpose 0 6 40 60 Inter-Frequency E-UTRAN FDD and TDD, UTRAN FDD, GERAN, LCR TDD, HRPD, CDMA2000 1x One 6 80 30 Inter-Frequency E-UTRAN FDD and TDD, UTRAN FDD, GERAN, LCR TDD, HRPD, CDMA2000 1x

A trade-off exists between the first pattern and the second pattern. The first pattern affects WAN transmission/reception through the serving cell instead of having a short period. On the other hand, the second pattern has less influence on WAN transmission/reception through the serving cell instead of having a longer period than the first pattern.

The terminal does not transmit any data to the base station during the measurement gap. Also, the UE does not expect to tune the (receive) RF chain to the WAN carrier frequency during the measurement gap. That is, the UE cannot receive the WAN signal in the D2D monitoring period in that it cannot receive the WAN signal even during the measurement gap.

As described above, if the WAN signal transmitted according to the predetermined timing is not received by the terminal due to the section or gap in which the WAN signal (ex. PHICH) cannot be received (or the reception of the WAN signal is not expected), the handling is a problem do.

In the present invention, it is assumed that the WAN signal includes a PHICH carrying HARQ-ACK, and a method of handling the corresponding UL HARQ procedure is proposed.

6 illustrates a UL HARQ operation according to an example of the present invention.

Referring to FIG. 6 , when the PHICH reception timing overlaps the D2D monitoring period, the UE may determine that the corresponding PHICH indicates ACK. That is, although the terminal did not receive the PHICH, it may be assumed that the base station successfully received the PUSCH transmitted in UL subframe #n+4.

As an example (alt 1-1), the UE has configured or enabled D2D discovery (type 1/2B) or D2D communication (mode 1/2), and DL related to PHICH reception due to previous PUSCH transmission When the subframe (ex. DL subframe #n+8) overlaps with the D2D monitoring period (Tx/Rx resource set/resource pool for D2D discovery or D2D communication), the UE receives PHICH on the corresponding DL subframe. Without expectation, an ACK signal for a transport block (TB) associated with the PUSCH is transmitted to a higher layer (MAC layer). This may be performed in the physical (PHY) layer of the terminal.

In this case, the PHICH reception timing overlaps with the D2D monitoring period, so even if the PHICH is not received, it is considered that the ACK is always indicated for the TB, and the ACK information is transmitted from the PHY layer to the upper layer (MAC layer). am. In fact, since there is a high probability that the base station will mainly successfully receive (ie, ACK) for PUSCH transmission, the physical layer of the terminal always delivers the ACK to a higher layer to process the UL HARQ procedure. Of course, there may be a case in which NACK is actually included in the corresponding PHICH, but in this case, it may be covered based on the ARQ operation of the RLC layer.

As another example (alt 1-2), D2D discovery (type 1/2B) or D2D communication (mode 1/2) is configured or enabled, and a DL subframe related to PHICH reception due to previous PUSCH transmission (ex. DL subframe #n+8) overlapped with the D2D monitoring period (Tx/Rx resource set/resource pool for D2D discovery or D2D communication), and the MAC PDU for PUSCH transmission is Msg3 buffer If it is not obtained from , "HARQ_FEEDBACK", which is a variable state related to the HARQ process (in MAC) of the corresponding terminal, is set to ACK. This may be performed in the MAC layer (or MAC entity) of the terminal. Here, the Msg3 buffer is a buffer for transmitting Msg3, and a MAC PDU is generated in the Msg3 buffer according to a received UL grant (in PDSCH) based on a random access response (RAR) (by PDCCH) in the random access procedure. can be That is, this embodiment indicates that the MAC PDU for PUSCH transmission is not a MAC PDU generated in the random access procedure.

This is a method in which the MAC layer becomes a subject to process the HARQ procedure. Even when there is no ACK/NACK signal transmitted from the PHY layer, the HARQ procedure can be processed through the operation of the proposed MAC layer.

7 illustrates a UL HARQ operation according to another example of the present invention.

Referring to FIG. 7 , when the PHICH reception timing overlaps the D2D monitoring period, the UE may determine that the corresponding PHICH indicates NACK. That is, although the UE did not receive the PHICH, it may be assumed that the base station did not successfully receive the PUSCH transmitted in UL subframe #n+4.

As an example (alt 2-1), the UE has configured or enabled D2D discovery (type 1/2B) or D2D communication (mode 1/2), and DL related to PHICH reception due to previous PUSCH transmission When the subframe (ex. DL subframe #n+8) overlaps with the D2D monitoring period (Tx/Rx resource set/resource pool for D2D discovery or D2D communication), the UE receives PHICH on the corresponding DL subframe. Without expectation, a NACK signal for a transport block (TB) associated with the PUSCH is transmitted to a higher layer (MAC layer). This may be performed in the physical (PHY) layer of the terminal.

As another example (alt 2-2), D2D discovery (type 1/2B) or D2D communication (mode 1/2) is configured or enabled, and a DL subframe related to PHICH reception due to previous PUSCH transmission (ex. DL subframe #n+8) overlapped with the D2D monitoring period (Tx/Rx resource set/resource pool for D2D discovery or D2D communication), and the MAC PDU for PUSCH transmission is Msg3 buffer If it is not obtained from , the HARQ entity instructs/performs non-adaptive retransmission for the corresponding PUSCH at a predetermined timing. This may be performed in the MAC layer (or MAC entity) of the terminal. Here, the non-adaptive retransmission may mean performing retransmission of the corresponding PUSCH based on the same format as the previous transmission (eg, the same MAC level, transmission power, etc.).

In this case, the non-adaptive retransmission may be instructed/performed in the MAC layer without a separate instruction from the physical layer, and even if the actual base station indicates ACK through the PHICH, the UE performs PUSCH retransmission. This assumes that the base station fails to receive the previous PUSCH transmission and indicates NACK through the PHICH, and performs PUSCH retransmission to prevent unnecessary packet loss in the upper layer (RLC layer), and to emphasize more stability or It is suitable for conservative system operation.

Meanwhile, the above-described operations according to the present invention may be applied in a multi-carrier environment, specifically, in a carrier aggregation (CA) environment.

8 and 9 show UL HARQ operations in consideration of carrier aggregation.

As shown in FIGS. 8 and 9 , if the D2D terminal operates in half duplex on a plurality of carriers based on TDD, as described above, the PHICH reception and the D2D transmission overlap on the time axis, and thus the PHICH may not be received. (according to the half duplex rule). In this case, the UE determines that the corresponding PHICH indicates ACK (FIG. 8), and may perform UL HARQ operation based on this (FIG. 8). Alternatively, the UE may determine that the corresponding PHICH indicates NACK (FIG. 9), and may perform UL HARQ operation based on this (FIG. 9).

10 is a flowchart illustrating a method of performing UL HARQ when a D2D monitoring period and a PHICH reception timing overlap according to the present invention.

Referring to FIG. 10, the base station and the D2D terminals perform a D2D setup procedure (S1000). In this case, among the D2D terminals, the Tx terminal and the Rx terminal may receive D2D configuration information from the base station. Here, the Tx terminal and the Rx terminal are relative concepts for D2D communication. The D2D configuration information may be transmitted through a system information block (SIB) or may be transmitted through radio resource control (RRC) signaling. The Tx terminal and the Rx terminal may determine/detect a D2D monitoring period based on the D2D configuration information.

The Rx terminal receives a UL grant from the base station (S1010). The UL grant may be received through PDCCH/EPDCCH. The UL grant indicates PUSCH transmission at the first timing. The Rx terminal transmits the PUSCH to the base station at the first timing based on the UL grant (S1020).

The Tx terminal may transmit a D2D signal based on the D2D configuration information (S1030). Here, the D2D signal includes a D2D discovery signal and a D2D communication signal. The D2D communication signal includes SA and D2D data.

The base station transmits a PHICH indicating HARQ ACK/NACK for the PUSCH to the Rx terminal at a second timing based on whether the PUSCH has been successfully received (S1040).

When the D2D monitoring period overlaps with the second timing for PHICH reception, the Rx UE expects to receive the D2D signal and does not expect to receive the PHICH. That is, the Rx terminal does not receive the PHICH, but determines the HARQ ACK/NACK for the PUSCH according to a predetermined criterion, and performs a UL HARQ operation based on this (S1050).

For example, when the D2D monitoring period and the second timing overlap, it may be determined that the corresponding PHICH indicates ACK. In this case, the physical layer of the terminal does not expect to receive the PHICH on the DL subframe of the second timing, and may deliver the ACK signal for the transport block (TB) related to the PUSCH to the upper layer (MAC layer) (alt) 1-1). Alternatively, the MAC layer (or MAC entity) of the terminal may set "HARQ_FEEDBACK", a variable state related to the terminal's HARQ process, to ACK if the MAC PDU for the corresponding PUSCH transmission is not obtained from the Msg3 buffer. There is (alt 1-2).

As another example, when the D2D monitoring period and the second timing overlap, it may be determined that the corresponding PHICH indicates NACK. In this case, the physical layer of the terminal does not expect to receive the PHICH on the DL subframe of the second timing, and may deliver the NACK signal for the transport block (TB) associated with the PUSCH to the upper layer (MAC layer) (alt) 2-1). Alternatively, if the MAC layer (or MAC entity) of the UE has not obtained the MAC PDU for the corresponding PUSCH transmission from the Msg3 buffer, the non-adaptive retransmission of the PUSCH at a predetermined timing through the HARQ entity. Instruct/execute (alt 2-2).

11 is a flowchart illustrating an operation of a terminal according to the present invention. In FIG. 11 , the terminal may correspond to the Rx terminal in FIG. 10 .

Referring to FIG. 11 , the terminal receives D2D configuration information (S1100). The terminal may receive the D2D configuration information from the base station, or may receive the D2D configuration information through another D2D terminal. The UE may detect the D2D monitoring period based on the D2D configuration information.

The terminal receives a UL grant indicating PUSCH transmission from the base station (S1110). The UL grant indicates the PUSCH transmission at a first timing.

The terminal transmits the PUSCH to the base station at the first timing based on the UL grant (S1120). A PHICH carrying (or indicating) HARQ ACK/NACK for the PUSCH may be transmitted from the base station at a second timing.

Thereafter, the D2D monitoring period for detecting a D2D signal transmitted from another D2D terminal may overlap the second timing. In this case, the terminal expects to receive the D2D signal and does not expect to receive the PHICH. That is, the UE does not receive the PHICH, but determines the HARQ ACK/NACK for the PUSCH according to a predetermined criterion, and performs a UL HARQ operation based on this (S1130).

For example, when the D2D monitoring period and the second timing overlap, it may be determined that the corresponding PHICH indicates ACK. In this case, the physical layer of the terminal does not expect to receive the PHICH on the DL subframe of the second timing, and may deliver the ACK signal for the transport block (TB) related to the PUSCH to the upper layer (MAC layer) (alt) 1-1). Alternatively, the MAC layer (or MAC entity) of the terminal may set "HARQ_FEEDBACK", a variable state related to the terminal's HARQ process, to ACK if the MAC PDU for the corresponding PUSCH transmission is not obtained from the Msg3 buffer. There is (alt 1-2).

As another example, when the D2D monitoring period and the second timing overlap, it may be determined that the corresponding PHICH indicates NACK. In this case, the physical layer of the terminal does not expect to receive the PHICH on the DL subframe of the second timing, and may deliver the NACK signal for the transport block (TB) associated with the PUSCH to the upper layer (MAC layer) (alt) 2-1). Alternatively, if the MAC layer (or MAC entity) of the UE has not obtained the MAC PDU for the corresponding PUSCH transmission from the Msg3 buffer, the non-adaptive retransmission of the PUSCH at a predetermined timing through the HARQ entity. Instruct/execute (alt 2-2).

12 is an example showing a block diagram of a terminal according to the present invention.

Referring to FIG. 12 , the terminal 1200 includes a terminal receiving unit 1205 , a terminal processor 1210 , and a terminal transmitting unit 1220 . The terminal may further include a memory (not shown). The memory is connected to the terminal processor 1210 and stores various information for driving the terminal processor 1210 . In the above-described embodiments, the operation of the terminal 1200 may be implemented under the control of the terminal processor 1210 . The terminal processor 1210 specifically includes a data processing unit 1211 , a collision determination unit 1212 , and a HARQ processing unit 1213 .

The terminal receiving unit 1205 receives D2D configuration information from the base station 1250 .

The terminal receiving unit 1205 may receive a D2D signal transmitted from another D2D terminal. Also, the terminal receiving unit 1205 may receive the UL grant and the PHICH transmitted from the base station 1250 .

The data processing unit 1211 generates a PUSCH based on the UL grant, and transmits the generated PUSCH to the base station at a first timing through the terminal transmission unit 1220 .

The HARQ processor 1213 may determine that the HARQ ACK/NACK signal for the PUSCH can be transmitted from the base station at a second timing, and control the terminal receiver 1205 . The terminal receiving unit 1205 may receive the HARQ ACK/NACK signal through the PHICH.

The collision determination unit 1212 may detect a D2D monitoring section based on the D2D setting information. The collision determination unit 1212 determines whether the second timing at which the PHICH is transmitted from the base station 1250 and the D2D monitoring period overlap each other on the time axis. When the second timing and the D2D monitoring interval overlap, the collision determination unit 1212 controls the terminal receiving unit 1205 to receive preferentially a D2D signal in the D2D monitoring interval. That is, in this case, the collision determination unit 1212 expects the reception of the D2D signal and does not expect the reception of the PHICH.

When the second timing and the D2D monitoring period overlap and the terminal receiving unit 1205 does not receive the PHICH, the HARQ processing unit 1213 determines HARQ ACK/NACK for the PUSCH according to a predetermined criterion, and based on this UL HARQ operation is performed.

For example, when the D2D monitoring period and the second timing overlap, the HARQ processing unit 1213 may determine that the corresponding PHICH indicates ACK. In this case, the HARQ processing unit 1213 may control the physical layer to deliver the ACK signal for the transport block (TB) associated with the PUSCH to a higher layer (MAC layer) (alt 1-1). Alternatively, if the HARQ processing unit 1213 does not obtain a MAC PDU for the corresponding PUSCH transmission from the Msg3 buffer, the MAC layer (or MAC entity) (alt 1-2).

As another example, when the D2D monitoring period and the second timing overlap, the HARQ processing unit 1213 may determine that the corresponding PHICH indicates NACK. In this case, the HARQ processing unit 1213 may control the physical layer to deliver the NACK signal for the transport block (TB) associated with the PUSCH to a higher layer (MAC layer) (alt 2-1). Alternatively, if the MAC PDU for the corresponding PUSCH transmission is not obtained from the Msg3 buffer, the HARQ processing unit 1213 indicates/performs non-adaptive retransmission of the corresponding PUSCH at a predetermined timing through the HARQ entity. It can control the MAC layer (or MAC entity).

The base station 1250 includes a base station transmitter 1255 , a base station processor 1260 , and a base station receiver 1270 . The base station 1250 may further include a memory (not shown). The memory is connected to the base station processor 1260 and stores various information for driving the base station processor 1260 . In the above-described embodiments, the operation of the base station 1250 may be implemented under the control of the base station processor 1260 . The base station processor 1260 specifically includes an RRC connection determining unit 1261 , a D2D resource allocating unit 1262 , a D2D mode setting unit 1263 , a scheduling unit 1264 , and an HARQ processing unit 1265 .

The base station transmitter 1255 transmits D2D configuration information to the terminal 1200 . The base station transmitter 1255 transmits the UL grant to the terminal 1200 . The base station transmitter 1255 transmits the PHICH to the terminal 1200 .

The base station receiver 1270 receives the PUSCH from the terminal 1200 .

The RRC connection determining unit 1261 may determine whether the terminal 1200 is in an idle mode or an RRC connected mode.

The HARQ processing unit 1265 determines whether the base station reception unit 1270 has successfully received the PUSCH, and generates HARQ ACK/NACK information. The base station transmitter 1255 may transmit the HARQ ACK/NACK information to the terminal through the PHICH.

The D2D mode setting unit 1263 may set the D2D mode of the terminal 1200 .

The D2D resource allocator 1262 may generate information on a resource pool for D2D communication based on whether the terminal 1200 is in an idle mode or an RRC connected mode. Also, the D2D resource allocator 1262 generates D2D configuration information. The D2D configuration information may include information (monitoring resource information) about the D2D monitoring period. The D2D configuration information may include information on a D2D resource pool for D2D mode 2. The monitoring resource information includes only information on a period for monitoring D2D signals of D2D terminals connected to a network of a single operator, or in a period for monitoring D2D signals of D2D terminals connected to a network of a single operator It may include information about the period for monitoring D2D signals of D2D terminals connected to networks of other operators and information about the period.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (18)

In the device communication method for device-to-device (D2D) communication,
determining a monitoring period for the D2D communication;
determining a subframe associated with receiving a hybrid automatic repeat request (HARQ) feedback; and
Including; determining whether the determined monitoring interval and the determined subframe overlap in time;
and setting a state variable related to the HARQ feedback reception to an acknowledgment (ACK) when the monitoring period and the subframe overlap.
The method of claim 1, wherein the step of setting a state variable related to the reception of the HARQ feedback to an acknowledgment (ACK) comprises:
Communication method, characterized in that it is applied when the monitoring period and the subframe overlap in time, and a Media Access Control Protocol Data Unit (MAC PDU) is not derived from the message 3 buffer.
The method of claim 2, wherein the message 3 buffer,
When the device transmits a preamble to the base station in a random access procedure and receives a random access response (RAR) in response to the preamble transmission, included in the RAR A communication method, characterized in that it is a buffer in which information on message 3 is stored based on an uplink grant.
4. The method of claim 3, wherein when the device receives the RAR,
the device generates a MAC PDU for message 3 transmission in the message 3 buffer based on the uplink grant;
The MAC PDU for transmitting the message 3 is derived from the message 3 buffer.
The method of claim 2, wherein when the monitoring period and the subframe overlap in time,
When the MAC PDU is derived from the message 3 buffer based on the random access procedure, the state variable related to the reception of the HARQ feedback is a Physical Hybrid-ARQ Indicator Channel (PHICH) in the feedback information indicated through Communication method, characterized in that it is set based on the.
3. The method of claim 2,
Setting the state variable related to the HARQ feedback reception to the acknowledgment (ACK) comprises:
The communication method, characterized in that, by the MAC entity of the device, the ACK is set as an ACK without checking the ACK information of the HARQ feedback reception scheduled to be received in the subframe.
7. The method of claim 6,
The subframe related to HARQ feedback reception is a subframe for receiving HARQ feedback through a Physical Hybrid-ARQ Indicator Channel (PHICH).
The method of claim 1, wherein the step of setting a state variable related to the reception of the HARQ feedback to the acknowledgment (ACK) comprises:
Communication method characterized in that it is applied when monitoring for the D2D communication has priority over receiving the HARQ feedback.
The method of claim 1, wherein the step of setting a state variable related to the reception of the HARQ feedback to the acknowledgment (ACK) comprises:
The communication method, characterized in that the data transmission related to the reception of the HARQ feedback is considered to be successful.
In a device for device-to-device (D2D) communication,
processor; and
a memory in which instructions are stored; including,
The processor is
determining a monitoring period for the D2D communication,
Determining a subframe related to hybrid automatic repeat request (HARQ) feedback reception,
It is determined whether the determined subframe overlaps with the monitoring period in time,
When the monitoring period and the subframe overlap in time, a state variable related to the HARQ feedback reception is set to an acknowledgment (ACK).
The method of claim 10, wherein when the state variable related to the reception of the HARQ feedback is set to the acknowledgment (ACK),
Applied when the monitoring period and the subframe overlap in time, and the Media Access Control Protocol Data Unit (MAC PDU) is not derived from the message 3 buffer, the apparatus.
12. The method of claim 11, wherein the message 3 buffer,
When the device transmits a preamble to a base station in a random access procedure and receives a random access response (RAR) in response thereto, an uplink grant included in the RAR Device, characterized in that the buffer in which information on message 3 is stored based on (Uplink Grant).
13. The method of claim 12, wherein when the device receives the RAR,
the device generates a MAC PDU for message 3 transmission in the message 3 buffer based on the uplink grant;
The MAC PDU for transmitting the message 3 is derived from the message 3 buffer.
The method of claim 11, wherein when the monitoring period and the subframe overlap in time,
When the MAC PDU is derived from the message 3 buffer based on the random access procedure, the state variable related to the reception of the HARQ feedback is a Physical Hybrid-ARQ Indicator Channel (PHICH) in the feedback information indicated through Device characterized in that it is set based on.
12. The method of claim 11, wherein when the state variable related to the reception of the HARQ feedback is set to the acknowledgment (ACK),
The apparatus of claim 1, wherein the state variable related to the HARQ feedback reception is set to ACK without checking the ACK information of the HARQ feedback reception scheduled to be received in the subframe by the MAC entity of the device.
16. The method of claim 15,
The subframe related to the HARQ feedback reception is a subframe for receiving the HARQ feedback through a Physical Hybrid-ARQ Indicator Channel (PHICH).
The method of claim 10, wherein when the state variable related to the reception of the HARQ feedback is set to the acknowledgment (ACK),
The device, characterized in that it is applied when the D2D communication monitoring has priority over the HARQ feedback reception.
The method of claim 10, wherein when the state variable related to the reception of the HARQ feedback is set to the acknowledgment (ACK),
The apparatus of claim 1, wherein data transmission related to receiving the HARQ feedback is considered successful.

Images