WO2018203627A1

WO2018203627A1 - Method for transmitting and receiving signals in wireless communication system and device therefor

Info

Publication number: WO2018203627A1
Application number: PCT/KR2018/004953
Authority: WO
Inventors: 신석민; 박창환; 안준기; 황승계
Original assignee: 엘지전자(주)
Priority date: 2017-05-02
Filing date: 2018-04-27
Publication date: 2018-11-08

Abstract

Disclosed are a method for transmitting and receiving signals in a wireless communication system supporting narrowband-Internet of Things (NB-IoT), and a device therefor. Specifically, a method by which a terminal receives a specific signal can comprise the steps of: attempting detection of the specific signal in a preset resource region, wherein the detection of the specific signal indicates whether to monitor a search region of a control channel; and monitoring the search region when the specific signal is detected. The preset resource region comprise a first resource region and a second resource region. A sequence for the specific signal can be generated by using a first route index-based first sequence and a second route index-based second sequence. The first sequence and the second sequence can be mapped to the first resource region and the second resource region, respectively.

Description

Method for transmitting and receiving signals in a wireless communication system and apparatus therefor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting and receiving system information in a wireless communication system, and more particularly to a specific signal in a wireless communication system supporting a narrowband internet of things (NB-IoT). A method for transmitting and receiving a signal) and an apparatus supporting the same.

Mobile communication systems have been developed to provide voice services while ensuring user activity. However, the mobile communication system has expanded not only voice but also data service.As a result of the explosive increase in traffic, a shortage of resources and users are demanding higher speed services, a more advanced mobile communication system is required. have.

The requirements of the next generation of mobile communication systems will be able to accommodate the explosive data traffic, dramatically increase the data rate per user, greatly increase the number of connected devices, very low end-to-end latency, and high energy efficiency. It should be possible. Dual connectivity, Massive Multiple Input Multiple Output (MIMO), In-band Full Duplex, Non-Orthogonal Multiple Access (NOMA), Super Various technologies such as wideband support and device networking have been studied.

The present specification proposes a method for transmitting and receiving a signal in a wireless communication system supporting a narrowband Internet of Things (NB-IoT).

Specifically, the present specification proposes a method of setting a sequence of a specific signal (eg, a wake up signal or a go-to sleep signal) indicating whether the search region is monitored and a method of mapping the resource region.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In a method of receiving a specific signal from a terminal in a wireless communication system supporting a narrowband Internet of Things (NB-IoT) according to an embodiment of the present invention, detecting the specific signal in a predetermined resource region And detecting the specific signal indicates whether or not to monitor a search space of a control channel. When the specific signal is detected, the search space is detected. It may include the process of monitoring. Here, the preset resource region is composed of a first resource region and a second resource region, the sequence for the particular signal, the first sequence and the second root based on a first root index (root index) The second sequence may be generated by using a second sequence based on an index, and the first sequence and the second sequence may be mapped to the first resource region and the second resource region, respectively.

In the method according to an embodiment of the present invention, a root index pair composed of the first root index and the second root index may include an identifier (cell) of a cell that transmits the specific signal. Identifier).

In addition, in the method according to an embodiment of the present invention, the root index pair may further indicate the number of paging occasions (paging occasion) for the terminal to monitor.

The method according to an embodiment of the present disclosure, wherein the root index pair further indicates a user equipment group for monitoring the search area.

Further, in the method according to an embodiment of the present invention, the search region includes a time unit for a paging occasion, wherein the preset resource region is disposed before the search region. Can be assigned to the specified time unit.

In addition, in the method according to an embodiment of the present disclosure, the preset resource region may be allocated periodically according to a period of the paging opportunity.

Further, in the method according to an embodiment of the present invention, when the specific signal is repeatedly transmitted using the preset resource region as a basic unit, the length of an orthogonal cover code applied to the specific signal is It may be determined based on the number of repetitive transmissions.

In addition, in the method according to an embodiment of the present invention, configuration information related to the repetitive transmission may be transmitted through a system information block for each carrier on which the specific signal is transmitted.

In addition, in the method according to an embodiment of the present invention, the preset resource region is composed of 12 subcarriers, and the first resource region is composed of 0 to 5th subcarriers. The second resource region may include 6th to 11th subcarriers.

In a terminal for receiving a specific signal in a wireless communication system supporting a narrowband Internet of Things (NB-IoT) according to an embodiment of the present invention, the terminal is a radio frequency (RF) for transmitting and receiving a radio signal Frequency) unit and a processor that is functionally connected with the RF unit. The processor attempts to detect the specific signal in a preset resource region, and the detection of the specific signal indicates whether or not to monitor a search space of a control channel. If is detected, the search space may be controlled to monitor the search space. Here, the preset resource region is composed of a first resource region and a second resource region, the sequence for the particular signal, the first sequence and the second root based on a first root index (root index) The second sequence may be generated by using a second sequence based on an index, and the first sequence and the second sequence may be mapped to the first resource region and the second resource region, respectively.

Further, in the terminal according to an embodiment of the present invention, a root index pair composed of the first root index and the second root index may include an identifier (cell) of a cell that transmits the specific signal. Identifier).

In addition, in the terminal according to an embodiment of the present invention, the root index pair may further indicate the number of paging occasions (paging occasion) for the terminal to monitor.

In addition, in the terminal according to an embodiment of the present disclosure, the root index pair may further represent a user equipment group for monitoring the search area.

In addition, in the terminal according to an embodiment of the present invention, the search region includes a time unit for a paging occasion, and the preset resource region is disposed before the search region. Can be assigned to the specified time unit.

Further, in the terminal according to an embodiment of the present invention, the preset resource region is composed of 12 subcarriers, and the first resource region is composed of 0th to 5th subcarriers. The second resource region may include sixth to eleventh subcarriers.

According to an embodiment of the present invention, even when a synchronization signal used in another cell and a wake up signal (or go-to sleep signal) overlap, there is an effect that the influence of interference can be reduced.

In addition, according to an embodiment of the present invention, through the combination of the sequence characteristics of the wake up signal and the index constituting the sequence, it is possible to deliver additional information (eg, cell identifier, paging opportunity indication information, terminal group indication information, etc.) There is.

In addition, according to an embodiment of the present invention, even in an environment with a large carrier frequency offset (CFO), the CFO can be removed using repeated sequence mapping characteristics and / or cover codes.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide embodiments of the present invention and together with the description, describe the technical features of the present invention.

1 illustrates a structure of a radio frame in a wireless communication system to which the present invention can be applied.

2 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which the present invention can be applied.

3 shows a structure of a downlink subframe in a wireless communication system to which the present invention can be applied.

4 shows a structure of an uplink subframe in a wireless communication system to which the present invention can be applied.

5 shows an example of a component carrier and carrier aggregation in a wireless communication system to which the present invention can be applied.

6 is a diagram illustrating division of cells of a system supporting carrier aggregation.

7 shows examples of NPDCCH candidates for Type 1 CSS and Type 1A CSS.

8 shows examples of NPDCCH candidates for Type 2 CSS and Type 2A CSS.

9 shows an example of a region in which a wake up signal is transmitted and a discovery region associated with NPDCCH to which the method proposed in the present specification can be applied.

10 shows an example of a method of setting a sequence of wake up signals to which the method proposed in the present specification can be applied.

11 shows an example of a sequence configuration and mapping scheme of a wake up signal to which the method proposed in the present specification can be applied.

12 shows another example of a sequence configuration and mapping scheme of a wake up signal to which the method proposed in the present specification can be applied.

FIG. 13 is a flowchart illustrating an operation of a terminal receiving a specific signal in a wireless communication system to which the method proposed in this specification can be applied.

14 illustrates a block diagram of a wireless communication device to which the methods proposed herein can be applied.

15 is a block diagram illustrating a communication device according to one embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention.

In this specification, a base station has a meaning as a terminal node of a network that directly communicates with a terminal. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases. That is, it is obvious that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. A 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an evolved-NodeB (eNB), a base transceiver system (BTS), an access point (AP), and the like. . In addition, a 'terminal' may be fixed or mobile, and may include a user equipment (UE), a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), and an AMS ( Advanced Mobile Station (WT), Wireless Terminal (WT), Machine-Type Communication (MTC) Device, Machine-to-Machine (M2M) Device, Device-to-Device (D2D) Device, etc.

Hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In downlink, a transmitter may be part of a base station, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal and a receiver may be part of a base station.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

The following techniques are code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and NOMA It can be used in various radio access systems such as non-orthogonal multiple access. CDMA may be implemented by a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA). UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. LTE-A (advanced) is the evolution of 3GPP LTE.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, which are wireless access systems. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

For clarity, the following description focuses on 3GPP LTE / LTE-A, but the technical features of the present invention are not limited thereto.

시스템 일반System general

3GPP LTE / LTE-A supports a type 1 radio frame structure applicable to frequency division duplex (FDD) and a type 2 radio frame structure applicable to time division duplex (TDD).

In FIG. 1, the size of the radio frame in the time domain is expressed as a multiple of a time unit of T_s = 1 / (15000 * 2048). Downlink and uplink transmission consists of a radio frame having a period of T_f = 307200 * T_s = 10ms.

1A illustrates the structure of a type 1 radio frame. Type 1 radio frames may be applied to both full duplex and half duplex FDD.

A radio frame consists of 10 subframes. One radio frame is composed of 20 slots having a length of T_slot = 15360 * T_s = 0.5ms, and each slot is assigned an index of 0 to 19. One subframe consists of two consecutive slots in the time domain, and subframe i consists of slot 2i and slot 2i + 1. The time taken to transmit 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.

In FDD, uplink transmission and downlink transmission are distinguished in the frequency domain. While there is no restriction on full-duplex FDD, the terminal cannot simultaneously transmit and receive in half-duplex FDD operation.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. Since 3GPP LTE uses OFDMA in downlink, the OFDM symbol is for representing one symbol period. The OFDM symbol may be referred to as one SC-FDMA symbol or symbol period. A resource block is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot.

FIG. 1B illustrates a frame structure type 2. FIG. Type 2 radio frames consist of two half frames each 153600 * T_s = 5 ms in length. Each half frame consists of five subframes of 30720 * T_s = 1ms in length.

In a type 2 frame structure of a TDD system, an uplink-downlink configuration is a rule indicating whether uplink and downlink are allocated (or reserved) for all subframes. Table 1 shows an uplink-downlink configuration.

Referring to Table 1, for each subframe of a radio frame, 'D' represents a subframe for downlink transmission, 'U' represents a subframe for uplink transmission, and 'S' represents a downlink pilot. A special subframe consisting of three fields: a time slot, a guard period (GP), and an uplink pilot time slot (UpPTS).

DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. GP is a section for removing interference caused in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

Each subframe i is composed of slots 2i and slots 2i + 1 each having a length of T_slot = 15360 * T_s = 0.5ms.

The uplink-downlink configuration can be classified into seven types, and the location and / or number of downlink subframes, special subframes, and uplink subframes are different for each configuration.

The time point when the downlink is changed from the uplink or the time point when the uplink is switched to the downlink is called a switching point. Switch-point periodicity refers to a period in which an uplink subframe and a downlink subframe are repeatedly switched in the same manner, and both 5ms or 10ms are supported. In case of having a period of 5ms downlink-uplink switching time, the special subframe S exists every half-frame, and in case of having a period of 5ms downlink-uplink switching time, it exists only in the first half-frame.

In all configurations, subframes 0 and 5 and DwPTS are sections for downlink transmission only. The subframe immediately following the UpPTS and the subframe subframe is always an interval for uplink transmission.

The uplink-downlink configuration may be known to both the base station and the terminal as system information. When the uplink-downlink configuration information is changed, the base station may notify the terminal of the change of the uplink-downlink allocation state of the radio frame by transmitting only an index of the configuration information. In addition, the configuration information is a kind of downlink control information, which may be transmitted through a physical downlink control channel (PDCCH) like other scheduling information, and is commonly transmitted to all terminals in a cell through a broadcast channel as broadcast information. May be

Table 2 shows the configuration of the special subframe (length of DwPTS / GP / UpPTS).

The structure of a radio frame according to the example of FIG. 1 is just one example, and the number of subcarriers included in the radio frame or the number of slots included in the subframe and the number of OFDM symbols included in the slot may vary. Can be.

Referring to FIG. 2, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, one downlink slot includes seven OFDM symbols, and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element on the resource grid is a resource element, and one resource block (RB) includes 12 × 7 resource elements. The number N ^ DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth.

The structure of the uplink slot may be the same as the structure of the downlink slot.

Referring to FIG. 3, up to three OFDM symbols in the first slot in a subframe are control regions to which control channels are allocated, and the remaining OFDM symbols are data regions to which PDSCH (Physical Downlink Shared Channel) is allocated. data region). An example of a downlink control channel used in 3GPP LTE includes a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid-ARQ indicator channel (PHICH), and the like.

The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols (ie, the size of the control region) used for transmission of control channels within the subframe. The PHICH is a response channel for the uplink and carries an ACK (Acknowledgement) / NACK (Not-Acknowledgement) signal for a hybrid automatic repeat request (HARQ). Control information transmitted through the PDCCH is called downlink control information (DCI). The downlink control information includes uplink resource allocation information, downlink resource allocation information or an uplink transmission (Tx) power control command for a certain terminal group.

The PDCCH is a resource allocation and transmission format of DL-SCH (Downlink Shared Channel) (also referred to as a downlink grant), resource allocation information of UL-SCH (Uplink Shared Channel) (also called an uplink grant), and PCH ( Paging information in paging channel, system information in DL-SCH, resource allocation for upper-layer control message such as random access response transmitted in PDSCH, arbitrary terminal It may carry a set of transmission power control commands for the individual terminals in the group, activation of Voice over IP (VoIP), and the like. The plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs. The PDCCH consists of a set of one or a plurality of consecutive CCEs. CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to the state of a radio channel. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of available bits of the PDCCH are determined according to the association between the number of CCEs and the coding rate provided by the CCEs.

The base station determines the PDCCH format according to the DCI to be transmitted to the terminal, and attaches a CRC (Cyclic Redundancy Check) to the control information. The CRC is masked with a unique identifier (referred to as RNTI (Radio Network Temporary Identifier)) according to the owner or purpose of the PDCCH. If the PDCCH for a specific terminal, a unique identifier of the terminal, for example, a C-RNTI (Cell-RNTI) may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, P-RNTI (P-RNTI) may be masked to the CRC. If the system information, more specifically, the PDCCH for the system information block (SIB), the system information identifier and the system information RNTI (SI-RNTI) may be masked to the CRC. In order to indicate a random access response that is a response to the transmission of the random access preamble of the UE, a random access-RNTI (RA-RNTI) may be masked to the CRC.

Enhanced PDCCH (EPDCCH) carries UE-specific signaling. The EPDCCH is located in a physical resource block (PRB) that is UE-specifically configured. In other words, as described above, the PDCCH may be transmitted in up to three OFDM symbols in the first slot in the subframe, but the EPDCCH may be transmitted in a resource region other than the PDCCH. The start time (ie, symbol) of the EPDCCH in the subframe may be configured in the terminal through higher layer signaling (eg, RRC signaling, etc.).

EPDCCH is a transport format associated with the DL-SCH, resource allocation and HARQ information, a transport format associated with the UL-SCH, resource allocation and HARQ information, resource allocation associated with Side-link Shared Channel (SL-SCH) and Physical Sidelink Control Channel (PSCCH) Can carry information, etc. Multiple EPDCCHs may be supported and the UE may monitor a set of EPCCHs.

The EPDCCH may be transmitted using one or more consecutive enhanced CCEs (ECCEs), and the number of ECCEs per single EPDCCH may be determined for each EPDCCH format.

Each ECCE may be composed of a plurality of enhanced resource element groups (EREGs). EREG is used to define the mapping of ECCE to RE. There are 16 EREGs per PRB pair. Except for REs carrying DMRS within each pair of PRBs, all REs are numbered 0 through 15 in order of increasing frequency followed by time increments.

The terminal may monitor the plurality of EPDCCHs. For example, one or two EPDCCH sets in one PRB pair in which the UE monitors EPDCCH transmission may be configured.

By combining different numbers of ECCEs, different coding rates for the EPCCH may be realized. The EPCCH may use localized transmission or distributed transmission, so that the mapping of ECCE to the RE in the PRB may be different.

Referring to FIG. 4, an uplink subframe may be divided into a control region and a data region in the frequency domain. A physical uplink control channel (PUCCH) carrying uplink control information is allocated to the control region. The data region is allocated a Physical Uplink Shared Channel (PUSCH) that carries user data. In order to maintain a single carrier characteristic, one UE does not simultaneously transmit a PUCCH and a PUSCH.

A PUCCH for one UE is allocated a resource block (RB) pair in a subframe. RBs belonging to the RB pair occupy different subcarriers in each of the two slots. This RB pair allocated to the PUCCH is said to be frequency hopping at the slot boundary (slot boundary).

캐리어 병합 일반Carrier Merge General

The communication environment considered in the embodiments of the present invention includes both multi-carrier support environments. That is, the multicarrier system or carrier aggregation (CA) system used in the present invention is one or more having a bandwidth smaller than the target band when configuring the target broadband to support the broadband A system that aggregates and uses a component carrier (CC).

In the present invention, the multi-carrier means the aggregation of carriers (or carrier aggregation), wherein the aggregation of carriers means not only merging between contiguous carriers but also merging between non-contiguous carriers. In addition, the number of component carriers aggregated between downlink and uplink may be set differently. The case where the number of downlink component carriers (hereinafter referred to as 'DL CC') and the number of uplink component carriers (hereinafter referred to as 'UL CC') is the same is called symmetric aggregation. This is called asymmetric aggregation. Such carrier aggregation may be used interchangeably with terms such as carrier aggregation, bandwidth aggregation, spectrum aggregation, and the like.

Carrier aggregation, in which two or more component carriers are combined, aims to support up to 100 MHz bandwidth in an LTE-A system. When combining one or more carriers having a bandwidth smaller than the target band, the bandwidth of the combining carrier may be limited to the bandwidth used by the existing system to maintain backward compatibility with the existing IMT system. For example, the existing 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHz bandwidth, and the 3GPP LTE-advanced system (i.e., LTE-A) supports the above for compatibility with the existing system. Only bandwidths can be used to support bandwidths greater than 20 MHz. In addition, the carrier aggregation system used in the present invention may support carrier aggregation by defining a new bandwidth regardless of the bandwidth used in the existing system.

The LTE-A system uses the concept of a cell to manage radio resources.

The carrier aggregation environment described above may be referred to as a multiple cell environment. A cell is defined as a combination of a downlink resource (DL CC) and an uplink resource (UL CC), but the uplink resource is not an essential element. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources. When a specific UE has only one configured serving cell, it may have one DL CC and one UL CC, but when a specific UE has two or more configured serving cells, as many DLs as the number of cells Has a CC and the number of UL CCs may be the same or less.

Alternatively, the DL CC and the UL CC may be configured on the contrary. That is, when a specific UE has a plurality of configured serving cells, a carrier aggregation environment in which a UL CC has more than the number of DL CCs may be supported. That is, carrier aggregation may be understood as merging two or more cells, each having a different carrier frequency (center frequency of a cell). Here, the term 'cell' should be distinguished from the 'cell' as an area covered by a generally used base station.

Cells used in the LTE-A system include a primary cell (PCell: Primary Cell) and a secondary cell (SCell: Secondary Cell). P cell and S cell may be used as a serving cell. In case of the UE that is in the RRC_CONNECTED state but the carrier aggregation is not configured or does not support the carrier aggregation, there is only one serving cell composed of the PCell. On the other hand, in case of a UE in RRC_CONNECTED state and carrier aggregation is configured, one or more serving cells may exist, and the entire serving cell includes a PCell and one or more SCells.

Serving cells (P cell and S cell) may be configured through an RRC parameter. PhysCellId is a cell's physical layer identifier and has an integer value from 0 to 503. SCellIndex is a short identifier used to identify an SCell and has an integer value from 1 to 7. ServCellIndex is a short identifier used to identify a serving cell (P cell or S cell) and has an integer value from 0 to 7. A value of 0 is applied to the Pcell, and SCellIndex is pre-assigned to apply to the Scell. That is, a cell having the smallest cell ID (or cell index) in ServCellIndex becomes a P cell.

P cell refers to a cell operating on a primary frequency (or primary CC). The UE may be used to perform an initial connection establishment process or to perform a connection re-establishment process, and may also refer to a cell indicated in a handover process. In addition, the P cell refers to a cell serving as a center of control-related communication among serving cells configured in a carrier aggregation environment. That is, the terminal may receive and transmit a PUCCH only in its own Pcell, and may use only the Pcell to acquire system information or change a monitoring procedure. E-UTRAN (Evolved Universal Terrestrial Radio Access) changes only the Pcell for the handover procedure by using an RRC ConnectionReconfigutaion message of a higher layer including mobility control information to a UE supporting a carrier aggregation environment. It may be.

The S cell may refer to a cell operating on a secondary frequency (or, secondary CC). Only one PCell may be allocated to a specific UE, and one or more SCells may be allocated. The SCell is configurable after the RRC connection is established and can be used to provide additional radio resources. PUCCH does not exist in the remaining cells excluding the P cell, that is, the S cell, among the serving cells configured in the carrier aggregation environment. When the E-UTRAN adds the SCell to the UE supporting the carrier aggregation environment, the E-UTRAN may provide all system information related to the operation of the related cell in the RRC_CONNECTED state through a dedicated signal. The change of the system information may be controlled by the release and addition of the related SCell, and at this time, an RRC connection reconfigutaion message of a higher layer may be used. The E-UTRAN may perform dedicated signaling having different parameters for each terminal, rather than broadcasting in the related SCell.

After the initial security activation process begins, the E-UTRAN may configure a network including one or more Scells in addition to the Pcells initially configured in the connection establishment process. In the carrier aggregation environment, the Pcell and the SCell may operate as respective component carriers. In the following embodiment, the primary component carrier (PCC) may be used in the same sense as the PCell, and the secondary component carrier (SCC) may be used in the same sense as the SCell.

5 (a) shows a single carrier structure used in an LTE system. Component carriers include a DL CC and an UL CC. One component carrier may have a frequency range of 20 MHz.

5 (b) shows a carrier aggregation structure used in the LTE_A system. In the case of FIG. 5B, three component carriers having a frequency size of 20 MHz are combined. Although there are three DL CCs and three UL CCs, the number of DL CCs and UL CCs is not limited. In case of carrier aggregation, the UE may simultaneously monitor three CCs, receive downlink signals / data, and transmit uplink signals / data.

If N DL CCs are managed in a specific cell, the network may allocate M (M ≦ N) DL CCs to the UE. In this case, the UE may monitor only M limited DL CCs and receive a DL signal. In addition, the network may assign L (L ≦ M ≦ N) DL CCs to allocate a main DL CC to the UE, in which case the UE must monitor the L DL CCs. This method can be equally applied to uplink transmission.

The linkage between the carrier frequency (or DL CC) of the downlink resource and the carrier frequency (or UL CC) of the uplink resource may be indicated by a higher layer message or system information such as an RRC message. For example, a combination of DL resources and UL resources may be configured by a linkage defined by SIB2 (System Information Block Type2). Specifically, the linkage may mean a mapping relationship between a DL CC on which a PDCCH carrying a UL grant is transmitted and a UL CC using the UL grant, and a DL CC (or UL CC) and HARQ ACK on which data for HARQ is transmitted. It may mean a mapping relationship between UL CCs (or DL CCs) through which a / NACK signal is transmitted.

Referring to FIG. 6, a configured cell may be configured for each UE as a cell capable of merging carriers based on a measurement report among cells of a base station as shown in FIG. 5. The configured cell may reserve resources for ack / nack transmission in advance for PDSCH transmission. An activated cell is a cell configured to actually transmit PDSCH / PUSCH among configured cells, and performs channel state information (CSI) reporting and sounding reference signal (SRS) transmission for PDSCH / PUSCH transmission. A de-activated cell is a cell that does not transmit PDSCH / PUSCH by a command or timer operation of a base station and may also stop CSI reporting and SRS transmission.

NPBCH and NPDSCH in NB-IoT System

In a wireless communication system supporting NB-IoT, a master information block (MIB) and / or system information block is provided through a narrowband physical broadcast channel (NPBCH) and / or a narrowband physical downlink shared channel (NPDSCH). Block, SIB) may be transmitted.

Hereinafter, the NPBCH and the NPDSCH will be described in detail.

First, the NPBCH will be described.

Scrambling for the NPBCH should be performed with M _bits indicating the number of bits to be transmitted on the NPBCH. In the case of normal CP, M _bit is 1600 and the scrambling sequence is performed in radio frames satisfying n _f mod64 = 0.

Should be initialized to

In addition, modulation on the NPBCH may be performed according to a quadrature phase shift keying (QPSK) scheme.

In addition, with respect to layer mapping and precoding for the NPBCH, the UE may assume that the antenna ports R ₂₀₀₀ and R ₂₀₀₁ are used for transmitting the NPBCH.

In addition, with respect to mapping NPBCH to resource elements, complex-valued symbols for each antenna port.

The block of is transmitted in subframe 0 during 65 consecutive radio frames starting from radio frames that satisfy n _f mod64 = 0. At this time, the block is mapped to resource elements (k, l) in a sequence starting with y (0).

The mapping for resource elements that are not reserved for transmission of a reference signal is performed by first increasing in the order of index k and then increasing in the order of index l. After mapping to a subframe, in the next radio frame

Before continuing to subframe 0 of, the subframe is repeated in subframe 0 of the next seven radio frames. In this case, the first three OFDM symbols of the subframe are not used in the mapping process.

Next, look at the NPDSCH.

The scrambling sequence generator for NPDSCH

Can be initialized to Here, n _s means the first slot of the codeword transmission.

In addition, modulation on the NPDSCH may be performed according to the QPSK scheme.

In addition, layer mapping and precoding for the NPDSCH may be performed according to the same antenna port as the NPBCH.

In addition, with respect to mapping the MPDSCH to resource elements, the NPDSCH may be mapped to one or more subframes.

For each of the antenna ports used for transmission of the physical channel, complex valued symbols

The block of may be mapped to resource elements (k, l) that satisfy all of the following criteria in the current subframe.

-Subframe not used for transmission of NPBCH, NPSS, or NPSS

-Subframe not assumed by UE to not be used for NRS

-Subframe not overlapping with resource elements used in CRS

_-Index l of the first slot of the _subframe is greater than or equal to l _DataStart

The UE does not expect the NPDSCH in the subframe i when it is not the NB-IoT DL subframe except for the transmission of the NPDSCH transmitting the SystemInformationBlockType1-NB in the fifth subframe of the radio frame (subframe # 4).

In case of NPDSCH transmission, in a subframe other than the NB-IoT DL subframe, the NPDSCH transmission is delayed until the next NB-IoT DL subframe.

Synchronization signal for NB-IoT

In the NB-IoT system, the synchronization signal may be classified into a narrowband primary synchronization signal (NPSS) and a narrowband secondary synchronization signal (NSSS). In this case, 504 unique physical layer identifiers may be indicated by the NSSS.

First, the sequence d _l (n) used for NPSS may be generated from a Zadoff-Chu sequence on the frequency domain according to Equation (1).

In Equation 1, the Zadoff-Chu root sequence index u is 5, and S (l) values for different symbol indexes l may be given by Table 3. Table 3 shows the definition of the S (l) value.

The sequence used for NPSS may be mapped to resource element (s) in the following manner.

Specifically, the same antenna port needs to be used for all symbols of the NPSS in the subframe. The terminal cannot assume that the NPSS is transmitted through the same antenna port as any downlink reference signal. In addition, the UE cannot assume that NPSS transmission in a given subframe uses the same antenna port (s) as NPSS in any other subframe.

In this case, the sequence d _l (n) is mapped to the resource element (k, l) in subframe # 5 of every radio frame (i.e., frame), and the sequence d _l (n) is mapped in the order of increasing index k. After that, the index l may be mapped in increasing order. In the case of a resource element overlapping a resource element to which a cell-specific reference signal is transmitted, the corresponding sequence element d (n) is not used for NPSS, but may be counted in a mapping procedure.

Next, the sequence d (n) used for NSSS may be generated from the Zadoff-Chu sequence on the frequency domain according to Equation (2).

In equation (2), the binary sequence b _q (m) is given by Table 4 and the cyclic shift in frame number n _f

Is given by equation (3).

The sequence used for NSSS may be mapped to resource element (s) in the following manner.

Specifically, the same antenna port needs to be used for all symbols of NSSS in a subframe. The UE cannot assume that the NSSS is transmitted through the same antenna port as any downlink reference signal. In addition, the terminal cannot assume that the NSSS transmission in a given subframe uses the same antenna port (s) as the NSSS in any other subframe.

The sequence d (n) is sequentially mapped from d (0) to resource elements (k, l). At this time, the sequence d (n) is the last allocated after that, in the order of increasing the first index k over 12 assigned subcarriers, in subframe # 9 of the radio frame.

The index l may be mapped in increasing order over the symbol. Here, the radio frame corresponds to a radio frame satisfying n _f mod 2 = 0. From here,

The value can be given by Table 5.

In the case of a resource element overlapping a resource element through which a cell specific reference signal is transmitted, the corresponding sequence element d (n) is not used for NSSS, but may be counted in a mapping procedure.

Scheduling for NB-IoT

The MasterInformationBlock-NB (MIB-NB) uses fixed scheduling with a period of 640 ms, and repetitive transmission is performed within 640 ms.

The first transmission of the MIB-NB is scheduled in subframe # 0 of the radio frame where SFN mod 64 = 0 and repetitive transmission is scheduled in subframe # 0 of all other radio frames. The transmission is arranged in eight independently decodable blocks of 80 ms duration.

SystemInformationBlockType1-NB (SIB1-NB) uses fixed scheduling with a period of 2560 ms. SIB1-NB transmission occurs in subframe # 4 of all other frames in 16 consecutive frames. The start frame for the first transmission of the SIB1-NB can be derived from the cell PCID and the number of repetitions in the 2560ms period, and are repeated at the same interval in the 2560ms period. Transmission Block Size (TBS) for SystemInformationBlockType1-NB and repetition within 2560ms are indicated in the schedulingInfoSIB1 field of the MIB-NB.

Table 6 shows an example of the MIB used in the NB-IoT system.

Table 7 shows an example of SIB type 1 used in the NB-IoT system.

Table 8 shows an example of the number of repetitions for the NPDSCH carrying SIB type 1.

Table 9 shows an example of a starting radio frame for the first transmission of the NPDSCH carrying SIB type 1.

Table 10 shows an example of a transport block size (TBS) for NPDSCH carrying SIB type 1.

NB-IoT에서의 하향링크 제어 채널 관련 절차Procedure for Downlink Control Channel in NB-IoT

The procedure related to the narrowband physical downlink control channel (NPDCCH) used in NB-IoT will be described.

The UE needs to monitor NPDCCH candidates (ie, set of NPDCCH candidates) as set by higher layer signaling for control information. Here, the monitoring may mean trying to decode respective NPDCCHs in the set according to all DCI formats monitored. The set of NPDCCH candidates for monitoring may be defined as an NPDCCH search space. In this case, the UE may perform monitoring using an identifier (eg, C-RNTI, P-RNTI, SC-RNTI, G-RNTI) corresponding to the corresponding NPDCCH search region.

In this case, the terminal may include a) Type1-NPDCCH common search space, b) Type2-NPDCCH common search space, and c) NPDCCH terminal-specific search region (NPDCCH). One or more of the UE-specific search spaces need to be monitored. In this case, the terminal does not need to simultaneously monitor the NPDCCH terminal-specific search region and the Type1-NPDCCH common search region. In addition, the terminal does not need to simultaneously monitor the NPDCCH terminal-specific search region and the Type2-NPDCCH common search region. In addition, the UE does not need to simultaneously monitor the Type1-NPDCCH common search area and the Type2-NPDCCH common search area.

The NPDCCH search region at an aggregation level and a repetition level is defined by a set of NPDCCH candidates. Here, each of the NPDCCH candidates is repeated in R consecutive NB-IoT downlink subframes except for the subframe used for transmission of a system information (SI) message starting at subframe k.

For the NPDCCH terminal-specific discovery region, the aggregation and repetition levels defining the discovery region and the corresponding monitored NPDCCH candidates are determined by substituting the R _MAX value with the parameter al-Repetition-USS set by the higher layer. It is listed as 11.

For the Type1-NPDCCH common search region, the aggregation and repetition levels defining the search region and the corresponding monitored NPDCCH candidates replace the R _MAX value with the parameter al-Repetition-CSS-Paging set by the higher layer. Are listed as:

For the Type2-NPDCCH common search region, the aggregation and repetition levels defining the search region and the corresponding monitored NPDCCH candidates replace the R _MAX value with the parameter npdcch-MaxNumRepetitions-RA set by the higher layer, as shown in Table 13 Listed.

At this time, the position of the starting subframe k is given by k = k _b . Here, k _b denotes a b-th consecutive NB-IoT downlink subframe from subframe k0, where b is ux R and u is 0, 1, ... (R _MAX / R) -1 Means. In addition, the subframe k0 means a subframe satisfying Equation 4.

For the NPDCCH terminal-specific search region, G shown in Equation 4 is given by the higher layer parameter nPDCCH-startSF-UESS,

Is given by the upper layer parameter nPDCCH-startSFoffset-UESS. In addition, in the case of NPDCCH Type2-NPDCCH common search region, G shown in Equation 4 is given by higher layer parameter nPDCCH-startSF-Type2CSS,

Is given by the upper layer parameter nPDCCH-startSFoffset-Type2CSS. In addition, in the case of the Type1-NPDCCH common search region, k is k0 and is determined from the position of the NB-IoT paging opportunity subframe.

When the terminal is set by the upper layer as a PRB for monitoring the NPDCCH terminal-specific light color area, the terminal should monitor the NPDCCH terminal-specific search area in the PRB set by the higher layer. In this case, the terminal does not expect to receive NPSS, NSSS, and NPBCH in the corresponding PRB. On the other hand, if the PRB is not set by the higher layer, the terminal should monitor the NPDCCH terminal-specific search area in the same PRB as the NPSS / NSSS / NPBCH is detected.

When the NB-IoT UE detects an NPDCCH having DCI format N0 (DCI format N0) ending in subframe n, and when transmission of the corresponding NPUSCH format 1 starts in subframe n + k, the UE Does not need to monitor the NPDCCH of any subframe starting in the range from subframe n + 1 to subframe n + k-1.

In addition, when the NB-IoT terminal detects an NPDCCH having DCI format N1 or DCI format N2 ending in subframe n, and transmission of the corresponding NPDSCH starts in subframe n + k. In this case, the UE does not need to monitor the NPDCCH of any subframe starting from the subframe n + 1 to the subframe n + k-1.

In addition, when the NB-IoT UE detects an NPDCCH having DCI format N1 ending in subframe n, and when transmission of the corresponding NPUSCH format 2 starts in subframe n + k, the UE sub-starts from subframe n + 1. It is not necessary to monitor the NPDCCH of any subframe starting in the range up to frame n + k-1.

In addition, when the NB-IoT UE detects an NPDCCH having the DCI format N1 for the "PDCCH order" ending in subframe n, and when transmission of the corresponding NPRACH starts in subframe n + k, the UE Does not need to monitor the NPDCCH of any subframe starting in the range from subframe n + 1 to subframe n + k-1.

In addition, when the NB-IoT UE has NPUSCH transmission ending in subframe n, the UE does not need to monitor the NPDCCH of any subframe starting in the range of subframe n + 1 to subframe n + 3. .

In addition, when the NPDCCH candidate of the NPDCCH discovery region ends in subframe n, and when the UE is configured to monitor the NPDCCH candidate of another NPDCCH discovery region starting before subframe n + 5, the NB-IoT terminal may be configured as an NPDCCH candidate of the NPDCCH discovery region. There is no need to monitor NPDCCH candidates.

With respect to the NPDCCH starting position, the starting OFDM symbol for the _NPDCCH is given by index l _NPDCCHStart , in the first slot of subframe k. At this time, when the upper layer parameter operarionModeInfo indicates '00' or '01', the index l _NPDCCHStart is given by the upper layer parameter eutaControlRegionSize. In contrast, when the upper layer parameter operarionModeInfo indicates '10' or '11', the index l _NPDCCHStart is 0.

하향링크 제어 정보 포맷(DCI format)Downlink Control Information Format (DCI format)

DCI transmits downlink or uplink scheduling information for one cell and one RNTI. Here, RNTI is implicitly encoded in CRC.

As the DCI format related to the NB-IoT, DCI format N0 (DCI format N0), DCI format N1 (DCI format N1), and DCI format N2 (DCI format N2) may be considered.

First, DCI format N0 is used for scheduling NPUSCH in one cell and may transmit the following information.

A flag for distinguishing between format N0 and format N1 (eg 1 bit), where value 0 may indicate format N0 and value 1 may indicate format N1.

Subcarrier indication (eg 6 bits)

Resource assignment (eg 3 bits)

Scheduling delay (eg 2 bits)

Modulation and Coding Scheme (eg 4 bits)

Redundancy version (eg 1 bit)

Repetition number (e.g. 3 bits)

New data indicator (e.g. 1 bit)

DCI subframe repetition number (eg 2 bits)

Next, DCI format N1 is used for the random access procedure initiated by scheduling of one NPDSCH codeword in one cell and NPDCCH order. At this time, the DCI corresponding to the NPDCCH order may be carried by the NPDCCH.

The DCI format N1 may transmit the following information.

The format N1 has a random access procedure initiated by the NPDCCH sequence only when the NPDCCH order indicator is set to '1', the cyclic redundancy check (CRC) of the format N1 is scrambled to C-RNTI, and all other fields are set as follows. Used for

Starting number of NPRACH repetitions (eg 2 bits)

Subcarrier indication of PRACH (eg 6 bits)

*-All other bits of format N1 are set to '1'.

Otherwise, the remaining information is transmitted as follows.

Scheduling delay (eg 3 bits)

Resource assignment (eg 3 bits)

Modulation and Coding Scheme (eg 4 bits)

Repetition number (eg 4 bits)

New data indicator (e.g. 1 bit)

HARQ-ACK resource (eg 4 bits)

DCI subframe repetition number (eg 2 bits)

When the CRC of the format N1 is scrambled to RA-RNTI, the following information (ie, field) among the above information (ie, fields) is reserved.

New data indicator

HARQ-ACK resource

At this time, if the number of information bits of the format N1 is smaller than the number of information bits of the format N0, '0' should be appended until the payload size of the format N1 is equal to the payload size of the format N0.

Next, DCI format N2 is used for paging and direct indication, and may transmit the following information.

A flag (eg 1 bit) for distinguishing paging from direct indication, where value 0 may indicate direct indication and value 1 may indicate paging.

If the value of the flag is 0, DCI format N2 is reserved information bits (reserved information bits for setting the same size as direct indication information (eg, 8 bits), format N2 having a flag value of 1). information bits).

On the other hand, if the value of the flag is 1, the DCI format N2 is used for resource allocation (e.g., 3 bits), modulation and coding scheme (e.g., 4 bits), repetition number (e.g., 4 bits), DCI subframe repetition number ( For example, 3 bits).

NB-NB- IoT의IoT 공통 탐색 영역(Common Search Space, CSS) 디코딩 Common search space (CSS) decoding

In the case of NB-IoT, a total of four CSS types may be considered for the common search area (CSS). Specifically, there may be Type 1 CSS for paging, Type 1A CSS for SC-MCCH, Type 2 CSS for Random Access Response (RAR), and Type 2A CSS for SC-MTCH. In this case, four CSS types may be classified into two types according to a decoding method.

First, a UE monitoring Type 1 CSS and Type 1A CSS receives an R _max value from an upper end and attempts blind decoding (BD) on all candidates that may have from the R _max value. can do.

Table 14 shows an example of CSS candidates for Type 1 / 1A NPDCCH.

For example, when the R _max value is 8, there may be a total of four cases of repetition number (R) that the actual NPDCCH may have, such as 1, 2, 4, and 8. That is, when the R _max value is 8, the number of NPDCCH candidates (that is, the number of NPDCCHs for which the UE attempts BD) may be set to four.

However, as shown in Table 14, when the number of R values for each R _max is limited to a maximum of eight (that is, the number of NPDCCH candidates is limited to a maximum of eight), when the R _max value is 256 or more, the corresponding R Some R values among candidate R values that the _max value may have may be excluded. For example, if the R _max value is 512, {2, 8} is excluded from the R values {1, 2, 4, 8, 16, 32, 64, 128, 256, 512} that are supported by the corresponding Rmax value. Can be.

In this case, the UE may not know in which candidate (s) the NPDCCH is to be transmitted. However, since the start position is always the same, the UE may perform the BD using one buffer.

In this regard, in order to confirm whether the UE properly receives the NPDCCH through the BD, information (for example, 3 bits) indicating a repetition number value of the corresponding NPDCCH may be included in the DCI format.

7 shows examples of NPDCCH candidates for Type 1 CSS and Type 1A CSS.

Referring to FIG. 7, when the R _max value is 8, the base station may be configured to select and transmit one of the NPDCCH candidates 702 to 708. In this case, as described above, the UE may perform BD for cases in which the R values are 1, 2, 4, and 8. In this case, as shown in FIG. 7, the base station may select one of a total of four different NPDCCH candidates and transmit the NPDCCH.

Here, NPDCCH candidate 702 indicates a candidate when R is 1, NPDCCH candidate 704 indicates a candidate when R is 2, NPDCCH candidate 706 indicates a candidate when R is 4, and NPDCCH candidate 708 indicates R The candidate in the case of 8 can be shown.

Next, the UE monitoring the Type 2 CSS and the Type 2A CSS may receive an R _max value from an upper end and attempt a BD for all candidates that may have from the R _max value. At this time, the values shown in Table 15 may be referred to. Table 15 shows CSS candidates for Type 2 / 2A NPDCCH.

For example, when the R _max value is 8, the total number of repetitions R that the actual NPDCCH may have may exist in total of 4 cases, such as 1, 2, 4, and 8.

Referring to Table 15, when the value of R _max is 8 or more, as the number of NPDCCH candidates is fixed to a maximum of 15, the small R value may be excluded. Here, the number of NPDCCH candidates may refer to the number of NPDCCHs to which the UE attempts BD. Specifically, when the R _max value is 8 or more, the UE includes one NPDCCH candidate corresponding to R _max , two NPDCCH candidates corresponding to R _max / 2, four NPDCCH candidates corresponding to R _max / 4, and R BD may be performed on eight NPDCCH candidates corresponding to _max / 8.

In this case, the UE may not know in which candidate (s) the NPDCCH will be transmitted, but may perform BD using different buffers (maximum of four).

In this regard, in order to confirm whether the UE properly receives the NPDCCH through the BD, information (for example, 2 bits) indicating a repetition number value of the corresponding NPDCCH may be included in the DCI format.

8 shows examples of NPDCCH candidates for Type 2 CSS and Type 2A CSS.

Referring to FIG. 8, when the R _max value is 8, the base station may be configured to select and transmit one of the NPDCCH candidates 802 to 830. In this case, as described above, the UE may perform BD for cases where R values are R _max , R _max / 2, R _max / 4, and R _max / 8.

Specifically, NPDCCH candidates 802 to 816 represent eight different candidates when R is 1, NPDCCH candidates 818 to 824 represent four different candidates when R is 2, and

NPDCCH candidates

826 and 828 are R Two different candidates in the case of 4 may be represented, and the NPDCCH candidate 830 may represent one candidate in the case where R is 8.

As described above, the number of candidates (ie, NPDCCH candidates) that can have a maximum may be set differently between Type 1 / 1A CSS and Type 2 / 2A CSS. In addition, the maximum number of buffers to be used may be set differently between the Type 1 / 1A CSS and the Type 2 / 2A CSS. However, the maximum number of buffers may vary depending on the implementation of the terminal.

As we saw earlier, Narrowband (NB) -LTE is a system for supporting low complexity, low power consumption with a system BW corresponding to 1 Physical Resource Block (PRB) of the LTE system. Say

That is, the NB-LTE system may be mainly used as a communication method for supporting a device such as a machine-type communication (MTC) terminal and / or an IoT terminal in a cellular system. That is, the NB-LTE system may be referred to as an NB-IoT system.

In addition, the NB-IoT system does not need to allocate an additional band for the NB-IoT system by using the same OFDM system as the OFDM parameters such as subcarrier spacing used in the existing LTE system. In this case, by assigning 1 PRB of the legacy LTE system band for NB-IoT, there is an advantage that the frequency can be used efficiently.

In the case of downlink, the physical channel of the NB-IoT system is N-Primary Synchronization Signal (N-PSS) / N-Secondary Synchronization Signal (N-SSS), N-Physical Broadcast Channel (N-PBCH), N-PDCCH It may be defined as / N-EPDCCH, N-PDSCH and the like. Here, 'N-' may be used to distinguish it from legacy LTE.

Existing terminals may consume a lot of power to monitor the search space to detect (or view) paging in idle mode. In consideration of this, a method of reducing battery consumption of the terminal may be considered by setting a signal indicating a wake up or go-to sleep of the terminal for a paging occasion. Here, the paging opportunity may mean a time when the paging signal according to the paging period is expected to be transmitted.

In this case, a signal indicating wake up of the terminal may be referred to as a wake up signal (WUS), and a signal indicating go-to sleep may be referred to as a go-to sleep signal. The wake up signal or the go-to sleep signal may be set to be transmitted to a preset resource region (eg, a part of a paging opportunity). In this case, the preset resource region may be periodically set according to a paging opportunity or may be periodically set separately from the paging opportunity.

Through the wake up signal or the go-to sleep signal, the terminal may be configured to wake up or go-to sleep before the paging opportunity.

For convenience of description, the method proposed herein will be described based on the wake up signal. In this case, the setting and method for the wake up signal may be applied to the go-to sleep signal in the same or similar manner.

As mentioned above, when the above wake up signal is used, power consumption of the terminal may be reduced. Specifically, when the wake up signal is not used, the UE needs to monitor CSS for every paging opportunity. However, when the wake up signal is used, the terminal may be configured to monitor the CSS only when the wake up signal is detected in the preset resource region.

In addition, the operation of monitoring the preset resource region in order for the terminal to detect the wake up signal may be less power consumption than the operation of monitoring the CSS described above. That is, the power consumption of the terminal may be reduced than in the case of decoding the above-described CSS.

Specifically, in the case of CSS, the decoding processing time of the terminal is required, but in the case of the wake up signal, since the signal is transmitted in the form of a sequence, the terminal only needs to determine whether it is detected in a specific region. An example of a region where a wake up signal is transmitted and a search region for the NPDCCH may be illustrated in FIG. 9.

9 shows an example of a region in which a wake up signal is transmitted and a discovery region associated with NPDCCH to which the method proposed in the present specification can be applied. 9 is for illustration only and does not limit the scope of the invention.

Referring to FIG. 9, the PO indicates a paging opportunity subframe determined from a higher layer, and in this example, it is assumed that the PO is set to 2560 subframes. In addition, it is assumed that an R _max value of Type 1 CSS is set to 256, and an R _max value (ie, a maximum duration) for the wake up signal is set to 1/8.

As shown in FIG. 9, a resource region (eg, wake up signal duration) for the wake up signal may be located before Type 1 CSS corresponding to each paging opportunity.

In this regard, a value (eg, R _max , maximum duration, etc.) related to repetitive transmission of the above wake up signal may be indicated in the following manner.

For example, a value related to repetitive transmission of the wake up signal may be indicated through a system information block (SIB) as one value for each NB-IoT carrier.

In this case, the list in which the one value is to be included may be generated differently according to the R _max value set for the corresponding paging, or one list may be generated regardless of the R _max value. When the list is generated in this manner, the maximum duration for the actual wake up signal may be indicated by one of the values belonging to the list.

Specifically, if the R _max value set for paging is 1024, one list {1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8} is generated. Suppose that 1/2 is set to a value indicating the maximum duration of the wake up signal through the SIB. In this case, the maximum duration of the actual wake up signal may be 512 (1024 * 1/2). In addition, even if the maximum duration is set, the actual wake up signal may be transmitted at a smaller value (eg, actual duration) rather than always at the maximum value.

In addition, the aforementioned wake up signal may be configured to transmit additional information, in addition to indicating whether or not a specific search area is monitored. Examples described below are divided for convenience of description and may be applied in combination with each other.

For example, cell identification information (eg, cell identifier) may be transmitted through a wake up signal.

For another example, information indicating whether to monitor for only one paging opportunity or multiple paging opportunities may be conveyed via a wake up signal. Specifically, assume that one wake up signal is configured to manage four paging opportunities. In this case, the wake up signal is a signal that wakes up one in four, a signal wakes up two out of four, a signal wakes up three out of four, and a signal wakes up all four. You need to include

For another example, even if one wake up signal indicates one paging opportunity, additional information indicating whether to monitor the corresponding paging opportunity for each terminal group based on the terminal identifier needs to be transmitted through the wake up signal. There may be. Specifically, when two terminal groups (ie, terminal group A and terminal group B) exist based on the terminal identifier, the wake up signal is a signal for monitoring only the terminal group A and a signal for monitoring only the terminal group B. We need to include signals that let us monitor both, and.

Hereinafter, embodiments of the present disclosure look at a specific method of designing a wake up signal that can be used to reduce power consumption of the terminal as described above. In particular, a method of mapping a sequence of a wake up signal to a design and a resource region will be described in order to increase the reliability of detection of the wake up signal and to transfer additional information.

In addition, the embodiments described below are merely divided for convenience of description, and some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

In addition, in some embodiments, the wake up signal is described as being configured based on the NPSS. However, this is only for convenience of description and may be configured based on the NSSS.

In addition, the embodiments described below are not limited to the Zadoff-Chu sequence, and of course, the same or similar may be applied to other sequences supported by the wireless communication system. In addition, the method may be applied not only to the wake up signal, but also to other signals having the same or similar functions.

In addition, the embodiments described below are described based on the existing LTE system, but may be applied to the same or similarly to the NR (New RAT) system. For example, the sequence generation and resource mapping method described herein is described based on a transmission unit (eg, a subframe) in an LTE system, but a transmission unit (eg, a short transmission unit, a subframe) in an NR system. , Slots, etc.) may be equally or similarly applied.

In addition, monitoring the search space in the present specification means that the corresponding CRC is pre-decoded after decoding the N-PDCCH of a specific area according to a DCI format (DCI format) to be received through the search area. It may also refer to a process of checking whether or not it matches (ie, matches) a desired value by scrambling to a specific RNTI value promised.

In addition, in the case of the NB-IoT system, each terminal recognizes a single PRB as a single carrier, and thus, a PRB referred to herein may be interpreted to have the same meaning as a carrier.

In addition, DCI format N0, DCI format N1, and DCI format N2 referred to herein may refer to DCI format N0, DCI format N1, and DCI format N2 described above (eg, defined in the 3GPP standard).

In addition, anchor-type PRBs (or anchor-type carriers or anchor carriers) are N-PSS, N- for initial access from a base station perspective. It may also mean a PRB transmitting an N-PDSCH for an SSS, an N-PBCH, and / or a system information block (N-SIB). In this case, there may be one anchor-type PRB, or there may be multiple anchor-type PRBs.

In addition, in the present specification, when there are one or a plurality of anchor-type PRBs as described above, the specific anchor-type PRB selected by the terminal through initial connection may be an anchor PRB or an anchor carrier. May be referred to. In addition, in this specification, a PRB allocated from a base station to perform a downlink process (or procedure) after initial access may be referred to as an additional PRB (or additional carrier).

제1 실시 예First embodiment

First, the sequence of the wake up signal (or go-to sleep signal) as described above may be configured based on a Zadoff-Chu sequence (ZC sequence).

The above-described wake up signal may be transmitted using 11 ZC sequences of length L. That is, to transmit a wake up signal in a resource region (eg, 11 (OFDM) symbols) except the control channel region, 11 ZC sequences of length L may be used.

For example, since a wake up signal must be transmitted within 12 subcarriers, the L value can be 11 or 13, a prime number around 12. This is because, if the length of the ZC sequence is set to a small number, as many root indices as possible can be used to generate the sequence.

When L is 11, the last RE may be set to repeat the value of the previous RE through a cyclic shift. Alternatively, if L is 13, the last RE may be set to drop. In addition, when L is 11, a null value may be input to the last RE, such as NPSS, and a carrier on the opposite end that does not overlap with a null carrier used by NPSS may be set as a null carrier.

In this case, 11 ZC sequences may be set to be transmitted one per symbol (eg, OFDM symbol).

In addition, root indexes of different N ZC sequences may be used. In this case, the selected root index (es) may be repeatedly applied to the remaining 11-N symbols according to a preset rule. Here, N may be one of 1 to 11.

For example, if the length L of the ZC sequence is 11 and different root indices 4 and 7 are used (ie, N = 2), the two root indices may be set to be used alternately. In this case, each root index included in 11 symbols may be '4, 7, 4, 7, 4, 7, 4, 7, 4, 7, 4'. In particular, considering that the length L of the ZC sequence is 11, when one root index is determined as a, the other root index may be set to be 11-a.

Also, a method of improving correlation performance by using a cover code (or fixed cover code) for the 11 OFDM symbols may be considered. For example, [1, 1, -1, -1, 1, -1, -1, 1, -1, 1, 1] or [1, 1, -1, 1, -1, -1, 1, -1, 1, -1, 1] and the like can be used.

In particular, the cover code used for the wake up signal needs to be set to show a low false alarm in terms of cross-correlation with the cover code used in NPSS. This is because the wake up signal may be involved in performance degradation associated with the terminal searching for the NPSS. Here, the false alarm may mean an error of mistaken the wake up signal and the NPSS due to the cover code.

In addition, the above-described wake up signal may be set to indicate only an operation of waking or sleeping the terminal by transmitting only one bit of information, but in consideration of inter cell interference, etc., two or more bits of information wake up. There may be a case where it should be transmitted via the up signal. In this case, additional information may be transmitted through the corresponding signal.

For example, the additional information (or the amount of additional information) may be set through a root index value of the sequence constituting the wake up signal, the number of root indexes, a repetition pattern of the root index, and the like.

In detail, two or more bits of information may be transferred in consideration of a factor for distinguishing a case where one root index is selected and repeatedly transmitted and a case where two root indexes are selected and repeated. In addition, even if the number of root indexes used is equal to N, a method of classifying information according to an arrangement order (for example, corresponding information or mapped pattern) may be considered. In addition, a method of classifying information using different cover codes may be considered.

In addition, since the aforementioned wake up signal needs to cover the cell edge of the corresponding cell, the wake up signal may be set to be repeatedly transmitted. In this case, a signal included in the aforementioned 11 symbols may be considered as a basic unit, that is, a single repetition. In this case, the terminal may expect that the wake up signal is repeatedly transmitted according to a repetition level delivered through higher layer, that is, higher layer signaling (eg, RRC signaling). In this case, the information on the repetition level may be expressed as an R _max value (eg, 2, 4, 8, to 2048).

For example, small repetition levels may be determined for terminal (s) that may be located near the cell center, and large repetition levels may be determined for terminal (s) that may be located at cell boundaries. In other words, the greater the repetition level, the greater the probability of affecting inter-cell interference, and in consideration of this, the amount of information transmitted according to the repetition level may be set differently.

If the repetition level is large, the amount of information transmitted is large. If the repetition level is small, the amount of information transmitted may be relatively small. Specifically, the wake up signal (or go-to sleep signal) for the terminal located at the cell boundary may be set to be transmitted through a large number of repetitions.

In this case, a wake up signal may be transmitted from a neighbor cell (ie, a base station of a neighbor cell, etc.), and the configuration of the wake up signal transmitted from the serving cell of the terminal and the wake up signal transmitted from the neighbor cell may be the same. In this case, it may be difficult for a terminal located at a cell boundary to distinguish which cell the received wake up signal is.

Therefore, in order to reduce the amount of interference affecting the wake up signal of the neighbor cell when the repetition level is large as described above, a method of configuring different wake up signals between neighbor cells may be considered. For example, different wake up signals may mean signals having the same signal design scheme but different information.

To this end, in terms of the design of the wake up signal, information that can distinguish a cell needs to be included in the wake up signal. That is, additional information needs to be transmitted through the wake up signal, and the amount of information transmitted according to the repetition level may be set differently. For example, the greater the repetition level, the greater the amount of information to be delivered.

The above-described method may be applied not only to a large coverage cell (eg, a large cell) but also to a narrow coverage cell (eg, a small cell) or a plurality of complex cells. In addition, the above-described method may be used not only for distinguishing between adjacent cells but also for distinguishing terminals (or terminal groups) in the same cell.

Hereinafter, methods (methods 1 to 3) for differently setting the amount of information delivered for each repetition level will be described in detail. The methods described below are merely divided for convenience of description, and some or all of the configuration of the method may be replaced with, or combined with, the configuration (s) of other methods.

Method 1)

First, in a basic unit, a method of setting a different number of scrambling sequences (for example, R _max / 8) for each repetition level (for example, R _max ) may be considered.

As described above, the number of scrambling sequences may be set to be based on a repetition level value (eg, an R _max value). That is, the number of scrambling sequences may be given according to a preset specific rule or specific formula. In this case, a binary scrambling sequence (eg, M-sequence), a ZC sequence, a Hadamard sequence, a Discrete Fourier Transform (DFT) sequence, or the like may be considered as an available scrambling sequence.

For example, when the repetition level is set to 128, 16 different scrambling sequences may be set to be distinguished based on each cell identifier. When the repetition level is set to eight or less (eg, four or two), the same scrambling sequence may be applied to set the wake up signal to be transmitted.

Method 2)

Next, a method of setting orthogonal cover codes of different lengths according to the repetition level may be considered in the basic unit. That is, the wake up signal may be transmitted by applying an orthogonal cover code of a specific length (eg, R _max ) for each repetition level. At this time, the available cover code may be used Hadamard sequence, DFT sequence and the like.

For example, when the repetition level is 128, the Hadamard sequence of length 128 may be configured to be transmitted over 128 subframes by applying one value for each subframe (or slot). In this case, since there are 128 different sequences that can be represented by the 128-length Hadamard sequence, 128 pieces of information can be delivered at the corresponding repetition level. In particular, when the amount of information to be transmitted is set based on the repetition level value as described above in the method 1 described above, 16 pieces of information may be expressed by presetting 16 of the 128 Hadamard sequences.

Method 3)

Next, within the total repetition level, the root index (or root index combination) does not change for a certain subframe length (i.e. a specific number of iterations), and a value different from the previously used root index for the next specific subframe length. A method of setting to transmit may be considered. Different information may be transmitted through a method of changing and using a root index for each specific subframe length.

For example, in consideration of the coherence time, the root index may be transmitted unchanged for four subframes (ie, 4 ms), and another root index may be selected for the next four subframes to transmit a sequence. Also, different root indices may be used for every subframe.

In this case, UEs may be grouped according to coverage enhancement (CE) levels. In addition, unlike the conventional NPSS, the wake up signal of a section overlapping a valid subframe may be punctured in a narrowband reference signal (NRS) RE.

Although the method described in this embodiment has been described with reference to the case where the number of symbols (ie, OFDM symbols) is 11, the method may be similarly or similarly applied to a wake up signal operating in N symbols. In this case, the length of the sequence may be 12 * N.

제2 실시 예Second embodiment

Next, a gold sequence (based on PN sequence) that can fit (ie, map) into N (or N _symbol ) symbols may be used for the wake up signal.

For example, when N is 11, a gold sequence having a length of 132 (the length of N * 12 subcarriers) may be created so that the same sequence is mapped to every subframe until re-initialization. In this case, when the number of repetitions is N _max , the same gold sequence may be transmitted in N _max subframes under the assumption that the sequence is not reinitialized.

In addition, in order to support low mobility and a large number of repetitions, a method of generating and mapping a gold sequence of 132 * M length (M> 1) to M subframes may be used. In general, since the cross-correlation property is improved as the length is longer, a sequence of 132 * M lengths may have better cross-correlation property than a sequence of 132 lengths. For example, the M value may be set to 4 because the channel change may not be large within four subframes in the NB-IoT system.

At this time, if the number of iterations of N _max, a sequence transmitted over the M sub-frames is repeated N _max / M times may be sent. In this case, N _max may be set based on a single subframe.

Alternatively, when the number of repetitions is N _max , one sequence transmitted over M subframes may be repeated N _max times and transmitted. In this case, N _max may be set based on M subframes.

The initial state of a particular m sequence (eg, the second m sequence) of the two m sequences used in the above-described gold sequence may be set to follow the C _init value. At this time, the C _init value may be a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), a terminal group identifier (N _GID ), or the like. It can consist of a linear or non-linear combination of parameters. Here, the nonlinear combination may be expressed as a product of the aforementioned parameters or the square of the parameters.

In addition, a modulo function or a minimum function may be used for the entire result value or some parameters in order to avoid the problem of overflowing the 31 bit shift register. Alternatively, even when the 31-bit transition register overflows, only LSB (least significant bit) may be used.

For example, c _init can be given by equations (5) and (6).

If the distinction of the terminal group is not applied, N _GID may be omitted in Equations 5 and 6 below.

In addition, when a UE-specific RNTI (or UE group-specific RNTI) is not included in sequence initialization, a c _init value may be set to a common value in one cell. In addition, initialization (or reinitialization) may be performed every N subframes (eg, N = 4) or may be performed in the first subframe of every paging opportunity.

제3 실시 예Third embodiment

Next, an uplink DMRS (Demodulation Reference Signal) based sequence that can fit (ie, map) into N (or N _symbol ) symbols may be used for the wake up signal.

That is, a method of selecting N uplink DMRSs based on a previously promised (or configured) method and configuring the N uplink DMRSs to operate in a sequence of wake up signals by mapping them to consecutive N symbols in one subframe may be considered. have. For example, N may be set to 11.

For example, an uplink DMRS sequence for an uplink DMRS sequence (when the number of subcarriers per resource unit (RU) is greater than 1) in an NB-IoT system may be given by Equation 7.

In Equation 7,

Is specified according to the number of subcarriers per RU,

May mean a cyclic shift value. If the number of subcarriers per RU is 12,

Is determined by Table 16, and the u value may be determined as shown in Equation 8.

In this case, methods of selecting uplink DMRS to be transmitted in 11 consecutive symbols may be the same as Method 1 to Method 4 described below. The following method is described by exemplifying the case where the number of subcarriers per RU is 12.

Method 1)

First, a method of selecting 11 uplink DMRS sequences to be mapped to each symbol according to a predetermined method may be considered.

In method 1, the initialization for the pre-promised method includes a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group. And a combination (eg, a non-linear combination) of an identifier (N _GID ), and a symbol index. Alternatively, the previously promised method may include a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group identifier (N _GID ). , And symbol index may be used.

Method 2)

Next, when 11 out of 30 uplink DMRS sequences are arbitrarily selected and arranged in consecutive symbols, N uplink DMRS sequence sets having a good cross-correlation property are set to N, and one of A method of selecting and applying a set may be considered.

In this case, a predetermined method may be used to select one uplink DMRS sequence set having one of N symbols. At this time, N may be set to at least 504, considering the case of distinguishing only the cell identifier.

In method 2, the initialization for the method promised in advance may include a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group identifier ( N _GID ), and a combination of symbol indexes (eg, non-linear combinations). Alternatively, the previously promised method may include a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group identifier (N _GID ). , And symbol index may be used.

Method 3)

Next, consider a method of generating a random sequence of length L according to a predetermined method, reading the K bits by cutting the K pieces from the front, and applying the modulo function to the K bit values to use the u values in Table 16 above. Can be. In this case, L may be at least 352 (32 * 11) or more. Here, 32 is the smallest 2 ^ n value greater than 30, and 11 is a value considering 11 symbols.

In the method 3, the initialization for the pre-promised method includes a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group identifier. (N _GID ), and a combination of symbol indexes (eg, non-linear combinations). Alternatively, the previously promised method may include a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), and a terminal group identifier (N _GID ). , And symbol index may be used.

For example, when K is 5, the sequence for the wake up signal may be set through the method of FIG. 10.

10 shows an example of a method of setting a sequence of wake up signals to which the method proposed in the present specification can be applied. 10 is merely for convenience of description and does not limit the scope of the invention.

Referring to FIG. 10, it is assumed that a wake up signal is transmitted using a random sequence of length L as in the method 3 described above. In this case, the sequence mapped to 11 symbols may be determined by a binary value for elements of a random sequence of length L.

For convenience of description, when the sequence of length L is set to [0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 쪋] Assume

At this time, the 5-bit value for the first symbol (1 ^st OFDM symbol) becomes '01011' and becomes 11. In this case, even if the modulo function mod 30 set to 30 with respect to 11 is 11, the DMRS sequence corresponding to u = 11 in Table 16 may be mapped to the first symbol.

Similarly, the 5-bit value for the 2 ^nd OFDM symbol is '10110', which is 22. In this case, since a modulo function set to 30 with respect to 22 is applied to 22, the DMRS sequence corresponding to u = 22 of Table 16 may be mapped to the second symbol.

In addition, the 5-bit value for the third symbol (3 ^rd OFDM symbol) becomes '11111' and becomes 31. In this case, since the modulo function set to 30 for 31 is 1, the DMRS sequence corresponding to u = 1 in Table 16 may be mapped to the third symbol.

Method 4)

Next, a method of selecting an uplink DMRS sequence to be mapped to the first symbol according to a predetermined method may be considered.

In this case, the ten uplink DMRS sequences to be mapped from the second symbol to the eleventh symbol include a cyclic shift α and / or a value for the initially selected uplink DMRS sequence value.

Can be created by changing the value. In this case, the cyclic shift α and / or

The value may be set to increase at predetermined intervals (ie, certain equal intervals) or randomly selected intervals as the symbol index increases.

In method 4, the initialization for the pre-promised method and / or the randomly selected interval may include a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity. (N), a terminal group identifier (N _GID ), and a symbol index or the like combination (eg, non-linear combination). Alternatively, the predetermined method and / or the randomly selected interval may include a cell identifier N ^ Ncell_ID, a frame number n _f , a slot number n _s , a wake up signal or a period of paging opportunity N, It may be determined using a terminal group identifier (N _GID ), a symbol index, and the like.

In addition, the above-described methods are

While the method mainly selects a value, a method in which the cyclic shift α of Equation 7 is selected differently for each symbol may be additionally considered. In addition, cyclic shift (α) and

The values all combine a cell identifier (N ^ Ncell_ID), a frame number (n _f ), a slot number (n _s ), a wake up signal or a period of paging opportunity (N), a terminal group identifier (N _GID ), and a symbol index. May be considered.

제4 실시 예Fourth embodiment

In addition, after splitting the resource region allocated to the wake up signal into K pieces, a method of generating different K sequences based on NSSS and mapping them to each region may be considered. Here, the resource region allocated to the wake up signal may be divided into a TDM scheme and / or an FDM scheme.

In the present embodiment, it is assumed that the resource region allocated to the wake up signal is 1 resource block (RB). This is only a resource region considering the NB-IoT system in the LTE system, and the method described in this embodiment may be equally or similarly applied to the resource region considering the NB-IoT system in the NR system.

At this time, the K value is preferably a positive integer greater than 2, it is assumed in the present embodiment that K = 2. In addition, as described above, although one RB may be divided into a TDM scheme and / or an FDM scheme, it will be described on the assumption that one RB is divided using the FDM scheme for convenience of description.

11 shows an example of a sequence configuration and mapping scheme of a wake up signal to which the method proposed in the present specification can be applied. 11 is merely for convenience of description and does not limit the scope of the present invention.

Referring to FIG. 11, it is assumed that a wake up signal is based on an NSSS scheme and is transmitted using a Zadoff-Chu sequence. In this case, the resource region 1102 means a control channel region (eg, a PDCCH region), the resource region 1104 means a first wake up signal region (eg, a first resource region), and the resource region 1106 is a second wake up. It may mean a signal area (eg, a second resource area).

First, when 1 RB is divided into two resource regions (that is, resource regions 1104 and 1106) through the FDM scheme, a method of transmitting a wake up signal by generating two different sequences based on NSSS may be considered. . In this case, the length of the generated sequence may be about twice the length of each resource region (that is, the number of symbols constituting each resource region) shown in FIG. 11. Thus, when the actual sequence is mapped, the sequence can be set to map by drilling the back (or front) of each sequence.

Alternatively, when 1 RB is divided into two resource regions through the FDM scheme, a method of generating two sequences set in consideration of the length of each resource region and transmitting a wake up signal may be considered.

For example, when generating a sequence based on the first NSSS, a decimal X value smaller than 66 (6 * 11) may be set, and an X length ZC sequence may be generated and used. In this case, the related scrambling sequence may also be set to be generated according to the X length. At this time, the X value may be 61, and for the remaining five REs, a value mapped from the first RE to the fifth RE may be additionally used.

In this case, the wake up signal not only indicates whether to monitor the above-described CSS (ie, the search area for the NPDCCH), but also additional information may be transmitted according to a combination of indexes used to generate two sequences. . Here, the additional information may correspond to the cell identification information described above, information indicating a paging opportunity to perform monitoring, information on the terminal group, and the like.

That is, the additional information may be delivered using a combination of a root index used to generate a ZC sequence mapped to the resource region 1104 and a root index used to generate a ZC sequence mapped to the resource region 1106. In this case, the ZC sequence mapped to the resource region 1104 is referred to as a first sequence, the ZC sequence mapped to the resource region 1106 is referred to as a second sequence, and each root index is a first first root index and a second root index. May be referred to.

For example, when the first sequence is generated using the root index 4 and the second sequence is generated using the root index 5, the terminal that receives the wake up signal receives an indication of the root index pair (4, 5). It can be judged that. At this time, if the root index pair (4, 5) indicates the monitoring performance of two of the four paging opportunities, the terminal can perform monitoring only for the two paging opportunities of the four paging opportunities. .

In this case, the mapping relationship between root index pairs and the additional information needs to be set in advance on higher layer signaling, physical layer signaling, or system.

In addition, the method described in the present embodiment may be applied in combination with the method for delivering additional information based on the repetition level described in the above-described first embodiment. That is, when a sequence is mapped to a resource region (ie, 1 RB) according to the method described in this embodiment, additional information may be set to be transmitted according to the degree of repeating transmission using this as a basic unit.

In the case of using the method proposed in this embodiment, since the correlation value is small when NSSS and subframes used in other cells overlap, there is an advantage that the influence of inter-cell interference can be reduced.

제5 실시 예Fifth Embodiment

In addition, after splitting the resource region allocated to the wake up signal into K pieces, a method of generating K sequences of length L into 11 sets of K lengths and mapping the regions to each region may be considered. Here, the resource region allocated to the wake up signal may be divided into a TDM scheme and / or an FDM scheme.

Also in this embodiment, it is assumed that the resource region allocated to the wake up signal is 1 RB. This is only a resource region considering the NB-IoT system in the LTE system, and the method described in this embodiment may be equally or similarly applied to the resource region considering the NB-IoT system in the NR system.

As described above, when 1 RB is divided into two resource regions based on the frequency domain, a ZC sequence of length 6 may be generated into two sets of 11 pieces each so that each set is mapped to each resource region. . In this case, the available length 6 ZC sequence may be a length 6 computer generated ZC sequence used for uplink DMRS of the NB-IoT system. Alternatively, the available length 6 ZC sequence may correspond to a sequence set to use only 6 REs through puncturing after generating a ZC sequence larger than 6.

In this case, 11 ZC sequences may be generated using 1 to 11 different root indices.

Alternatively, as shown in FIG. 12, a method of generating five and six ZC sequences using two root index pairs may be considered. That is, six ZC sequences (first sequence) of length 11 generated using the first root index pair are mapped to the resource region, and ZC sequences (second sequence) of length 11 generated using the second root index pair are mapped. Five may be mapped to resource zones.

12 shows another example of a sequence configuration and mapping scheme of a wake up signal to which the method proposed in the present specification can be applied. 12 is merely for convenience of description and does not limit the scope of the invention.

Referring to FIG. 12, it is assumed that a wake up signal is transmitted using a Zadoff-Chu sequence and is transmitted through two divided resource regions.

In this case, the resource region 1202 means a control channel region (eg, a PDCCH region), the

resource regions

1204 and 1206 mean a resource region for the first root index pair, and the

resource regions

1208 and 1210 represent a second root. It may mean a resource region for an index pair.

That is, six ZC sequences are generated by the first root index pair and five ZC sequences are generated by the second root index pair. For example, an X sequence of length 12 may be generated by the first root index pair (a, b), and a Y sequence of length 12 may be generated by the second root index pair (c, d).

Here, the X sequence may be generated based on an A sequence of length 6 generated by the root index a and a B sequence of length 6 generated by the root index b. Also, the Y sequence may be generated based on the C sequence of length 6 generated by the root index c and the D sequence of length 6 generated by the root index d.

In this case, ZC sequences of length 11 may be mapped to 11 symbols in the order of [X, Y, X, Y, X, Y, X, Y, X, Y, X].

Alternatively, unlike the one shown in FIG. 12, the root index pair may also consist of root indices of two sequences arranged consecutively on the time axis. For example, the root index of the sequence mapped to the resource region 1204 and the root index of the sequence mapped to the resource region 1208 may be set as a first root index pair, and the root index and the resource region of the sequence mapped to the resource region 1206 may be set. The root index of the sequence mapped to 1210 may be set as a second root index pair.

In this case, the wake up signal not only indicates whether to monitor the above-described CSS (ie, the search region for the NPDCCH), but additional information may be transmitted according to two root index pairs. For example, two root index pairs may be selected based on a cell identifier, an index of a time unit (eg, a subframe index), and the like. Alternatively, a combination of two root index pairs may be selected at random or a preset rule according to information to be additionally delivered through a wake up signal.

In addition, each ZC sequence generated based on the root index pair may be configured to be repeatedly mapped or alternately mapped.

In addition, in the method described in the present embodiment, a cover code may be additionally used to improve performance.

In the case of using the method proposed in the present embodiment, even when the carrier frequency offset (CFO) is large, since the CFO can be provided using repeated mapping characteristics and / or cover codes, the reliability of receiving a wake up signal from the terminal increases. can do.

FIG. 13 is a flowchart illustrating an operation of a terminal receiving a specific signal in a wireless communication system to which the method proposed in this specification can be applied. 13 is merely for convenience of description and does not limit the scope of the present invention.

Referring to FIG. 13, it is assumed that the terminal is set to perform the method proposed in the above-described embodiments of the present specification (for example, the first embodiment and the fourth embodiment). In addition, the specific signal in FIG. 13 may mean the above-described wake up signal (or go-to sleep signal). That is, the specific signal may indicate whether to monitor the search area (CSS) of the control channel (eg, NPDCCH).

First, the terminal may attempt to detect a specific signal in a preset resource region (S1305).

In this case, the preset resource region may be allocated (or set) through the above-described method. For example, the search region may include a time unit (eg, subframe, slot, etc.) for a paging opportunity, and the preset resource region may be allocated to a time unit disposed before the search region. In particular, the preset resource region may be allocated periodically according to a period of paging opportunity (ie, paging period).

In addition, the preset resource region may include a first resource region and a second resource region. Here, the first resource region and the second resource region may be set according to the above-described methods (eg, the method in the fourth embodiment or the fifth embodiment).

Thereafter, when a specific signal is detected, the terminal may monitor the search area (S1310).

In this case, a sequence for a specific signal may be set and mapped through the above-described method (eg, the method in the fourth embodiment).

For example, a Zadoff-Chu sequence for a particular signal may be generated using a first sequence based on the first root index and a second sequence based on the second root index. In this case, each of the first sequence and the second sequence may be mapped to the first resource region and the second resource region.

In this case, the root index pair composed of the first root index and the second root index may be set to deliver additional information as described above. For example, the root index pair may indicate an identifier of a cell transmitting a specific signal, the number of paging opportunities to monitor, the number of terminal groups to monitor, and the like.

In addition, when a specific signal is repeatedly transmitted using a preset resource region as a basic unit, the length of an orthogonal cover code applied to the specific signal, as in the above-described method (for example, the method in the first embodiment). May be determined based on the number of repetitive transmissions. In this case, configuration information (eg, information indicating a maximum duration) related to repetitive transmission may be transmitted through SIB for each carrier on which a specific signal is transmitted.

Through this operation, since the terminal does not wake up to monitor all the search areas, there is an effect that the battery power consumption of the terminal can be reduced.

General apparatus to which the present invention can be applied

Referring to FIG. 14, a wireless communication system includes a base station 1410 and a plurality of terminals 1420 located in an area of a base station 1410.

The base station 1410 includes a processor 1411, a memory 1412, and an RF unit 1413. The processor 1411 implements the functions, processes, and / or methods proposed in FIGS. 1 to 13. Layers of the air interface protocol may be implemented by the processor 1411. The memory 1412 is connected to the processor 1411 and stores various information for driving the processor 1411. The RF unit 1413 is connected to the processor 1411 and transmits and / or receives a radio signal.

The terminal 1420 includes a processor 1421, a memory 1422, and an RF unit 1423.

The processor 1421 implements the functions, processes, and / or methods proposed in FIGS. 1 to 13. Layers of the air interface protocol may be implemented by the processor 1421. The memory 1422 is connected to the processor 1421 and stores various information for driving the processor 1421. The RF unit 1423 is connected to the processor 1421 and transmits and / or receives a radio signal.

The

memories

1412 and 1422 may be inside or outside the

processors

1411 and 1421, and may be connected to the

processors

1411 and 1421 through various well-known means. In addition, the base station 1410 and / or the terminal 1420 may have a single antenna or multiple antennas.

In particular, FIG. 15 illustrates the terminal of FIG. 14 in more detail.

Referring to FIG. 15, a terminal may include a processor (or a digital signal processor (DSP) 1510, an RF module (or an RF unit) 1535, and a power management module 1505). ), Antenna 1540, battery 1555, display 1515, keypad 1520, memory 1530, SIM card Subscriber Identification Module card) 1525 (this configuration is optional), speaker 1545, and microphone 1550. The terminal may also include a single antenna or multiple antennas. Can be.

The processor 1510 implements the functions, processes, and / or methods proposed in FIGS. 1 to 13. The layer of the air interface protocol may be implemented by the processor 1510.

The memory 1530 is connected to the processor 1510 and stores information related to the operation of the processor 1510. The memory 1530 may be inside or outside the processor 1510 and may be connected to the processor 1510 by various well-known means.

A user enters command information, such as a telephone number, for example by pressing (or touching) a button on keypad 1520 or by voice activation using microphone 1550. The processor 1510 receives the command information, processes the telephone number, and performs a proper function. Operational data may be extracted from the SIM card 1525 or the memory 1530. In addition, the processor 1510 may display command information or driving information on the display 1515 for the user to recognize and for convenience.

The RF module 1535 is connected to the processor 1510 to transmit and / or receive an RF signal. The processor 1510 transmits command information to the RF module 1535 to transmit a radio signal constituting voice communication data, for example, to initiate communication. The RF module 1535 is composed of a receiver and a transmitter for receiving and transmitting a radio signal. The antenna 1540 functions to transmit and receive wireless signals. Upon receiving the wireless signal, the RF module 1535 may forward the signal and convert the signal to baseband for processing by the processor 1510. The processed signal may be converted into audible or readable information output through the speaker 1545.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, it is also possible to configure the embodiments of the present invention by combining some components and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that the embodiments can be combined to form a new claim by combining claims which are not expressly cited in the claims or by post-application correction.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), and FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in memory and driven by the processor. The memory may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

In the wireless communication system supporting the NB-IoT of the present invention, a method for transmitting and receiving a signal has been described with reference to an example applied to a 3GPP LTE / LTE-A system. In addition to the 3GPP LTE / LTE-A system, a NR (New RAT) system is provided. It is possible to apply to various wireless communication systems such as.

Claims

In a method for receiving a specific signal from a terminal in a wireless communication system supporting a narrowband Internet of Things (NB-IoT),

Attempting to detect the specific signal in a preset resource region, and detecting the specific signal indicates whether or not to monitor a search space of a control channel;

Monitoring the search space when the specific signal is detected;

The preset resource region includes a first resource region and a second resource region.

The sequence for the particular signal is generated using a first sequence based on a first root index and a second sequence based on a second root index,

And wherein the first sequence and the second sequence are mapped to the first resource region and the second resource region, respectively.
The method of claim 1,

And a root index pair composed of the first root index and the second root index indicates an identifier of a cell transmitting the specific signal.
The method of claim 2,

The root index pair, characterized in that the terminal further indicates the number of paging occasion (paging occasion) to perform the monitoring.
The method of claim 2,

The root index pair, characterized in that further indicating a user equipment group (User Equipment group) to perform monitoring for the search area.
The method of claim 1,

The search area includes a time unit for a paging occasion,

The preset resource region is allocated to a time unit disposed before the search region.
The method of claim 5,

The predetermined resource region is periodically allocated according to the period of the paging opportunity.
The method of claim 1,

When the specific signal is repeatedly transmitted based on the preset resource region, the length of an orthogonal cover code applied to the specific signal is determined based on the number of repetitive transmissions. How to.
The method of claim 7, wherein

The configuration information related to the repetitive transmission is transmitted through a system information block for each carrier on which the specific signal is transmitted.
The method of claim 1,

The preset resource region is composed of 12 subcarriers,

The first resource region is composed of 0 to 5 th subcarriers,

And the second resource zone is comprised of sixth to eleventh subcarriers.
In a terminal for receiving a specific signal in a wireless communication system supporting a narrowband Internet of Things (NB-IoT),

RF (Radio Frequency) unit for transmitting and receiving radio signals,

A processor functionally connected with the RF unit,

The processor,

Attempt to detect the specific signal in a predetermined resource region, the detection of the specific signal indicates whether or not to monitor the search space of the control channel (control channel),

When the specific signal is detected, control to monitor the search space,

The preset resource region includes a first resource region and a second resource region.

The sequence for the particular signal is generated using a first sequence based on a first root index and a second sequence based on a second root index,

And the first sequence and the second sequence are mapped to the first resource region and the second resource region, respectively.
The method of claim 10,

And a root index pair composed of the first root index and the second root index indicates an identifier of a cell transmitting the specific signal.
The method of claim 11,

The root index pair, characterized in that the terminal further indicates the number of paging occasion (paging occasion) to perform the monitoring.
The method of claim 11,

The root index pair further comprises a user equipment group for performing monitoring of the search area.
The method of claim 10,

The search area includes a time unit for a paging occasion,

The preset resource region is assigned to a time unit disposed before the search region.
The method of claim 10,

The preset resource region is composed of 12 subcarriers,

The first resource region is composed of 0 th to 5 th subcarriers,

The second resource region is characterized in that consisting of the sixth to eleventh subcarriers.