WO2016159680A1

WO2016159680A1 - Machine-to-machine communication method for extending coverage, and apparatus and system for performing same

Info

Publication number: WO2016159680A1
Application number: PCT/KR2016/003318
Authority: WO
Inventors: 오혁준
Original assignee: 오혁준; 송현용
Priority date: 2015-04-02
Filing date: 2016-03-31
Publication date: 2016-10-06

Abstract

A machine-to-machine communication method for extending coverage comprises the steps of: allocating a system bandwidth having a predetermined size for transmission; and transmitting at least one of system information and data excluding a master information block (MIB) using the system bandwidth having the predetermined size, wherein the at least one of system information and data excluding the MIB is transmitted by performing frequency hopping using a periodic hopping pattern. Accordingly, coverage can be extended while maintaining low power.

Description

Method of communication of things for coverage extension, apparatus and system for performing the same

The present invention relates to a method of communication of things, an apparatus and a system for performing the same, and more particularly, to a method of communication of things for coverage expansion, an apparatus and system for performing the same.

There are a large number of IoT communication terminals-for example, Machine Type Communication (MTC) terminals-and low cost of IoT terminals such as MTC terminals at a low price is a key factor in implementing the Internet of Things (IoT). to be.

MTC terminals can be used for various applications, low power consumption is required, and communication for infrequent small burst transmissions is expected.

For M2M applications, telecommunications terminals, such as MTC terminals, such as electricity, water, and gas meters, can be deployed deep within the building and coverage improvements compared to LTE cell coverage defined previously. May be required.

Some machine type communication (MTC) terminals are installed in the basement of a building or in a place that is insulated with metal foil or shielded by a metal window or thin walled building. For these installation reasons, the MTC terminal experiences penetration losses on the air interface than the general LTE terminal.

MTC terminals present in the extreme coverage scenario may have characteristics such as very low data rate, large delay tolerance, and no-mobility, so some messages and / or when communicating using the MTC terminal Channels may not be needed.

Techniques for improving the coverage of the MTC terminal should take into account coverage, power consumption, cell frequency efficiency, impact on standards, manufacturing cost, complexity, and the like.

In the case of current machine type communication (MTC), even a small frequency band width of about 1.4 MHz requires a technology that works well in the existing commercial network regardless of the current bandwidth of the base station. In particular, the current MTC (Machine Type Communication), since the data rate is about 100kbps (fixed bandwidth to 1.4MHz), there is a need for a method that can significantly expand the coverage while maintaining low power in the MTC terminal.

Not all terminals require coverage improvement, and the extent to which coverage improvement is required may vary from terminal to terminal, and the techniques for the coverage improvement should be enabled only for the required terminal.

There is a need for a technique for improving the coverage of an MTC terminal by 20 dB compared to a general Category 1 LTE user equipment (UE) having a minimum data rate.

As the coverage improvement of the MTC terminal increases, the physical channels used must also be improved. In order to improve the coverage of the MTC terminal by about 20 dB, a shared channel (SCH), a broadcast channel (BCH), and physical All uplink physical channels and downlink physical channels, including downlink control channels (eg, Physical Downlink Control Channel (PDCCH)), should be improved.

If a single receive radio frequency (RF) and bandwidth reduction technique as described above is applied to MTC terminals, this single receive RF and bandwidth reduction technique will reduce downlink coverage, and further coverage improvement to compensate for this coverage loss. Skill is required.

Specifically, when a single receive RF chain is applied to the MTC terminal, additional coverage supplementation is required for all downlink channels, and when the maximum bandwidth is reduced, (E) PDCCH (Enhanced) Physical Downlink Coverage supplementation for Control Channel (PHY) and Physical Downlink Shared Channel (PDSCH) is needed.

In addition, such coverage replenishment techniques require low cost MTC techniques to be applied. Allowing cost reduction and extended coverage at the same time can lead to reduced performance of the Long Term Evolution (LTE) system.

On the other hand, MTC terminals need more than 20dB of coverage extension, but since only 1.4MHz bandwidth is used and only one RF chain is limited, data reception performance is greatly reduced compared to conventional mobile communication terminals. none. Therefore, a variety of advanced technologies are required to increase the performance even in such an environment to obtain 20 dB or more of coverage.

In addition, one of the most important roles in the coverage expansion technology is uplink random access channel (ACH) operation. RACH, which is a kind of data request signal transmitted by the terminal to the base station at any time for connection and data transmission of the base station of the terminal, serves as a start of communication initiated by all the terminals, and thus a far-away MTC terminal having an extended coverage of 20 dB or more. There is a need for a method in which a base station can successfully receive an RACH signal transmitted from and successfully transmit a response signal to the corresponding MTC terminal in a long distance.

In this overall operation, if the base station and / or the terminal can distinguish the MTC coverage extension terminal and the general mobile communication terminal in advance, it is possible to greatly increase the efficiency in MTC coverage extension communication. Therefore, a technique for distinguishing an MTC coverage extension terminal from a general terminal is also required in an RACH process in which a terminal attempts initial access.

It is an object of the present invention to provide a method of MTC communication for coverage extension that can extend coverage while maintaining low power, and an apparatus and system for performing the same.

In a downlink thing communication method from a base station to an MTC terminal according to an exemplary embodiment of the present invention, system information, control information, and data excluding a master information block (MIB) using a system bandwidth of a predetermined size at the base station And transmitting at least one of the at least one of the at least one of the at least one of the system information, the control information, and the data except for the master information block (MIB) at the base station. Frequency hopping is performed using a hopping pattern and transmitted to the MTC terminal. The frequency hopping pattern may be generated or determined using at least one of a cell identifier (ID), a terminal identifier (ID), a system frame number (SFN), and a subframe index. The frequency hopping pattern may be transmitted to the MTC terminal using persistent scheduling. A primary synchronization signal (PSS) / secondary synchronization signal (SSS) used for synchronization and a PBCH indicating system information may not perform the frequency hopping. The frequency hopping may only be performed within a particular narrowband set. In the case of the TDD transmission scheme, the specific narrowband set may be set identically for uplink transmission and the downlink transmission. The base station informs the IoT terminal of an available narrowband set using system information including at least one of a MIB and an SIB that are broadcasted to the IoT terminals in the network. The MIB and / or SIB encoding may be encoded with a code indicating a specific number to inform the MTC of the usage information about the available narrowband set.

According to another exemplary embodiment of the present invention, an uplink thing communication method from a MTC terminal to a base station includes at least one of control information, a random access signal, and data using a system bandwidth of a predetermined size in the MTC terminal. And transmitting to the base station, wherein at least one of the control information, a random access signal, and data is performed by performing frequency hopping using a hopping pattern between narrow bands smaller than the system bandwidth. Transmit to base station.

According to another embodiment of the present invention, a downlink thing communication method from a base station for coverage extension to a thing communication terminal uses system bandwidth of a predetermined size. The system information-the system information includes a master information block (MIB) and an SIB ( And at least one of control information and data to the MTC terminal, wherein at least one of the system information, control information and data is repeated to the MTC terminal. send. The repetitive transmission may be transmitted to the MTC using fixed scheduling, but the constant scheduling may be transmitted by fixing the repetitive transmission pattern. Repeated transmission of the MIB (Master Information Block) may be transmitted using one of a method of transmitting the same signal and a method of transmitting the same data but different types of signals. The method of transmitting the same data but having different forms of signals may transmit the same data but with different coding. The MTC terminal may be operated by being divided into a small coverage terminal and a large coverage terminal according to channel conditions.

Machine type communication (MTC) communication method for coverage extension according to another aspect of the present invention for achieving the object of the present invention uses a PRACH signal to distinguish between the MTC coverage extension terminal and the general terminal.

In order to distinguish the MTC coverage extension terminal and the general terminal, it may be classified with a PRACH preamble.

In order to distinguish the MTC coverage extension terminal and the general terminal, the MTC coverage extension terminal may be divided into time and frequency resource positions.

In order to distinguish the MTC coverage extension terminal and the general terminal, the MTC coverage extension terminal may be distinguished with a specific pattern indicating the MTC terminal.

In order to distinguish the MTC coverage extension terminal and the general terminal, the MTC coverage extension terminal may be distinguished with a pattern generated by combining and combining a specific pattern indicating the MTC terminal and the existing PRACH preamble.

A method of distinguishing an MTC coverage extension terminal from a general terminal by using a pattern generated by combining and combining a specific pattern representing an MTC terminal and an existing PRACH preamble is repeatedly transmitted as it is when the existing PRACH preamble is repeated. You can change the code values of the TDM, FDM pattern, or CDM.

In order to distinguish the MTC coverage extension terminal and the general terminal, the MTC coverage improvement terminal and the general terminal may be distinguished by combining a CDM and a repeating transmission pattern.

According to an aspect of the present invention for achieving the above object of the present invention, when performing downlink frequency hopping for the thing communication, the narrowband usage information is transmitted from the thing communication terminal. By using the system information or the downlink control channel, a set of available narrowbands may be informed to MTS terminals in the network.

According to another embodiment of the present invention, a method of communication of things performs multi-subframe scheduling during downlink frequency hopping.

Machine type communication (MTC) communication method for coverage expansion according to another aspect of the present invention for achieving the object of the present invention to efficiently respond to the change caused by the difference in the transmission channel according to the coverage difference It's an adaptive way of doing things. The change in the transport channel or the difference in the transport channel state experienced by the UE is based on the change of the transport channel or the difference in the transport channel state based on the PRACH, the pilot signal in the PUSCH, or the sounding signal received uplink to the base station. I can figure it out. According to the change of the transmission channel or the difference in the state of the transmission channel encountered by the UE, it is possible to adaptively operate the number of repetitive transmissions, frequency hopping patterns, and the like. The number of repetitive transmissions, frequency hopping patterns, etc. may be adaptively applied according to the coverage level of the corresponding UE. For example, the terminals that need to operate in a place such as a distance to the terminal or a basement are inferior to a general channel environment, and thus, the number of repetitive transmissions and the frequency hopping pattern may be differently operated according to the difference of the transmission channel state. The required coverage level can be inferred from the estimated channel state based on the PRACH, the DMRS in the PUSCH, or the sounding signals. That is, since the number of repetitive transmissions required for the IoT terminal on the ground and the IoT terminal in the ground may be greatly different from each other, the number of repetitive transmissions, frequency hopping patterns, etc. may be changed according to the difference in the transmission channel state experienced by the IoT terminal. It can be operated differently.

Although features and elements have been described above in particular in combination, those skilled in the art will appreciate that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be embodied in a computer program, software, firmware or hardware included in a computer-readable medium for execution by a computer or a processor. Examples of computer-readable media include electronic signals (sent over a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard disks and removable disks. Optical media such as, but not limited to, magnetic media, magnetic-optical media, CD-ROM disks, and digital versatile disks (DVDs). The processor associated with the software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer. The processor includes a digital signal processor (DSP), a microprocessor, one or more microprocessors associated with the DSP core, a controller, a microcontroller, application specific integrated circuits (ASICs), a field programmable gate array. (field programmable gate array; FPGA) circuits, integrated circuits (ICs), state machines, and the like.

According to the MTC communication method for coverage extension as described above, and an apparatus and system for performing the same, coverage can be greatly expanded while maintaining low power.

According to the multi-subframe scheduling method during frequency hopping of the M2 terminal as described above, and an apparatus and system for performing the same, coverage can be significantly increased while increasing the data rate and reducing the number of switching of subframes. have.

1 is a schematic block diagram of an MTC terminal according to an embodiment of the present invention.

2 is a schematic block diagram of an MTC communication system according to an embodiment of the present invention.

3 is a conceptual diagram illustrating an example of a resource grid for one downlink slot in an LTE system.

4 is a conceptual diagram illustrating a structure of a downlink subframe in an LTE system.

5 shows a structure of an uplink subframe in an LTE system.

6 is a conceptual diagram illustrating an example of a downlink frame structure according to an embodiment of the present invention.

7 shows an example of a frequency hopping pattern according to another embodiment of the present invention.

FIG. 8 is a conceptual diagram illustrating a case in which a narrow band having a size of 6PRB is arranged to align with an existing legacy PRB mapping according to an embodiment of the present invention.

FIG. 9 is a conceptual diagram illustrating a case where a narrow band having a 5PRB size is arranged to align with an existing legacy PRB mapping according to another embodiment of the present invention.

10 is a conceptual diagram for supporting a downlink narrowband terminal in an existing wideband system according to an embodiment of the present invention.

11 is a conceptual diagram for supporting an uplink narrowband terminal in an existing wideband system according to an embodiment of the present invention.

FIG. 12 is a conceptual diagram illustrating a pattern in which frequency hopping occurs between narrow bands having a 6PRB size using an overall system bandwidth larger than a 1.4 MHz bandwidth according to another embodiment of the present invention.

13 and 14 are multi for PUSCH transmission in accordance with an embodiment of the present invention is a conceptual diagram showing a sub-frame scheduling (Cross-subframe scheduling) by way of example - the sub-frame scheduling (Multi-subframe scheduling) or a cross.

15 is a conceptual diagram illustrating a CRC masking method for a terminal ID in order to reduce overhead according to an embodiment of the present invention.

16 exemplarily shows additional information transmitted using the reserved 10-bit of the LTE MIB.

17 illustrates an example of a data transmission method for a low data rate based IoT sensor application according to another embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

The terminal may be a mobile station (MS), user equipment (UE), user terminal (UT), wireless terminal, access terminal (AT), terminal, fixed or mobile subscriber unit, subscriber station (SS) Subscriber Stations, cellular telephones, wireless devices, wireless communication devices, Wireless Transmit / Receive Units (WTRUs), mobile nodes, mobiles, mobile stations, personal digital assistants (PDAs) ), Smartphone, laptop, netbook, personal computer, wireless sensor, consumer electronics (CE) or other terms. Various embodiments of the terminal may be photographed such as a cellular telephone, a smart phone having a wireless communication function, a personal digital assistant (PDA) having a wireless communication function, a wireless modem, a portable computer having a wireless communication function, or a digital camera having a wireless communication function. Devices, wearable devices with wireless communications capabilities, gaming devices with wireless communications capabilities, music storage and playback appliances with wireless communications capabilities, Internet home appliances with wireless Internet access and browsing, as well as combinations of such functions It may include a portable unit or terminals, but is not limited thereto.

A base station generally refers to a fixed point for communicating with a terminal, and includes a base station, a Node-B, an eNode-B, an advanced base station (ABS), HR-BS, site controller, base transceiver system (BTS), access point (AP), or any other type of interfacing device capable of operating in a wireless environment may be included.

The base station may include other base stations and / or network elements (not shown), such as a base station controller (BSC), radio network controller (RNC), relay nodes, and the like. It can be part. The base station may be configured to transmit and / or receive wireless signals within a particular geographic area, which may be referred to as a cell (not shown).

The cell may also be divided into cell sectors. For example, a cell associated with a base station can be divided into three sectors. Thus, in one embodiment, the base station may include three transceivers, one transceiver for each sector of the cell. In another embodiment, the base station may use multiple-input multiple output (MIMO) technology, and thus may utilize multiple transceivers for each sector of the cell.

The MTC terminal includes a terminal for implementing M2M communication by embedding a sensor and a communication function. For example, the MTC terminal may include a Machine Type Communication (MTC) terminal, a narrowband LTE (Narrow band LTE) terminal, and a Cellular IoT (CIoT) terminal.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

Referring to FIG. 3, a downlink slot includes a plurality of OFDM symbols in the time domain and N _RB resource blocks (RBs) in the frequency domain. The number NRB of resource blocks included in the downlink slot may depend on the downlink transmission bandwidth set in the cell. For example, in an LTE system, the NRB may have any value between 6 and 110 depending on the bandwidth. One resource block may include a plurality of subcarriers in the frequency domain. The structure of the uplink slot may also be the same as that of the downlink slot.

Each element on the resource grid is called a resource element. Resource elements on the resource grid may be identified by an index pair (k, l) in the slot. Here, k (k = 0, ..., N _RB X 2-1) is the subcarrier index in the frequency domain, and l (l = 0, ..., 6) is the OFDM symbol index in the time domain.

In FIG. 3, one resource block includes 7 X 12 resource elements including 7 OFDM symbols in a time domain and 12 subcarriers in a frequency domain, but the number and subcarriers of an OFDM symbol in one resource block are illustrated. The number of is not limited thereto. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of a cyclic prefix (CP), frequency spacing, and the like. For example, the number of OFDM symbols is 7 for a normal CP and the number of OFDM symbols is 6 for an extended CP. The number of subcarriers in one OFDM symbol may be selected and used among 128, 256, 512, 1024, 1536 and 2048. The number of subcarriers in one OFDM symbol may use a number smaller than 128, for example, 64, 32, 16, 8, when using a narrower bandwidth than the present for MTC. Can be adjusted according to the bandwidth.

The bandwidth of the LTE system can be very flexible and can vary from about 1 MHz to 20 MHz. If a narrower band is used for the IoT, the bandwidth of the LTE system can be used even below 1 MHz.

Referring to FIG. 4, one downlink subframe may include two slots in a time domain, and each slot may include seven OFDM symbols in a normal CP. The leading up to 3 OFDM symbols (up to 4 OFDM symbols for 1.4Mhz bandwidth) of the first slot in the subframe are the control regions to which control channels are allocated and the remaining OFDM symbols are the physical downlink shared channel (PDSCH). May be a data area to be allocated.

The PDCCH includes resource allocation and transmission format of downlink-shared channel (DL-SCH), resource allocation information of uplink shared channel (UL-SCH), paging information on PCH, system information on DL-SCH, and random access transmitted on PDSCH. Resource allocation of higher layer control messages such as responses, sets of transmit power control commands for individual UEs in any UE group, activation of voice over internet protocol (VoIP), and the like. A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs. The PDCCH may be transmitted on an aggregation of one or several consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to a state of a radio channel. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of possible bits of the PDCCH may be determined according to the correlation 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 sent to the terminal, and attaches a cyclic redundancy check (CRC) to the control information. In the CRC, a unique radio network temporary identifier (RNTI) is masked according to an owner or a purpose of the PDCCH. If the PDCCH is for a specific terminal, a unique identifier of the terminal, for example, a cell-RNTI (C-RNTI) may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, PRNTI (paging-RNTI) may be masked to the CRC. If the PDCCH is for a system information block (SIB), a system information identifier and a system information-RNTI (SI-RNTI) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE.

5 shows a structure of an uplink subframe in an LTE system.

The uplink subframe may be divided into a control region and a data region in the frequency domain. The control region may be allocated a physical uplink control channel (PUCCH) for transmitting uplink control information. The data region may be allocated a physical uplink shared channel (PUSCH) for transmitting data. When indicated by the higher layer, the terminal may support simultaneous transmission of the PUSCH and the PUCCH.

PUCCH for one UE may be allocated as an RB pair in a subframe. Resource blocks belonging to a resource block pair occupy different subcarriers in each of a first slot and a second slot. The frequency occupied by the resource block belonging to the resource block pair allocated to the PUCCH may be changed based on a slot boundary. This is called that the RB pair allocated to the PUCCH is frequency-hopped at the slot boundary. The terminal may obtain a frequency diversity gain by transmitting uplink control information through different subcarriers over time. m is a location index indicating a logical frequency domain location of a resource block pair allocated to a PUCCH in a subframe.

The uplink control information transmitted on the PUCCH includes a hybrid automatic repeat request (HARQ) acknowledgment (ACK) / non-acknowledgement (NACK), a channel quality indicator (CQI) indicating a downlink channel state, and an uplink radio resource allocation request. (scheduling request) and the like.

The PUSCH may be mapped to the UL-SCH which is a transport channel. The uplink data transmitted on the PUSCH may be a transport block which is a data block for the UL-SCH transmitted during the TTI. The transport block may be user information. Alternatively, the uplink data may be multiplexed data. The multiplexed data may be a multiplexed transport block and control information for the UL-SCH. For example, the control information multiplexed on the data may include a CQI, a precoding matrix indicator (PMI), a HARQ, a rank indicator (RI), and the like. Alternatively, the uplink data may consist of control information only.

As an example of the MTC terminal, the MTC terminal needs more than 20 dB of coverage extension, but only 1,4 MHz bandwidth should be used, and only one reception RF chain may be used, and data reception performance is significantly higher than that of the conventional mobile communication terminal. There is no choice but to fall.

Therefore, there is a need for a variety of advanced technologies that can increase the performance even in this environment to achieve 20dB or more of coverage. These methods include a method of significantly improving signal to noise ratio (SNR) through repeated transmission and a method of securing diversity gain by frequency hopping 1.4 MHz band for the entire system band.

MTC frequency hopping technology

The maximum bandwidth for a single carrier supported by a normal LTE terminal is 20 MHz. One of the technologies that can reduce the cost of the MTC terminal is to reduce the maximum bandwidth supported by the terminal to a bandwidth less than 20MHz (for example, 5Mhz, 3Mhz, 1.4Mhz, 200Khz, etc.). Techniques for reducing the maximum bandwidth that these terminals can support may be applied to downlink and / or uplink, RF components and / or baseband components, data and / or control channels. The frequency location of the reduced bandwidth (data channel and / or control channel) less than 20 MHz may be fixed at the center of the carrier bandwidth, may be fixed at both ends of the carrier band, or It may be fixed only at one end, or may be changed for each MTC terminal in a semi-statically, dynamically, or a predetermined pattern. For MTC communication, the location on the frequency axis of the reduced bandwidth (narrowband) less than 20 MHz used for the data channel and / or control channel may be aligned in RB units. For MTC communications, the location on the frequency axis of the reduced bandwidth smaller than 20 MHz used for the data channel and / or control channel is 6-PRB for 1.4 MHz, so for example, for 10 MHz bandwidth, the total number of PRBs is 50 It is not divided by 6, leaving an extra PRB. For this MTC communication, the position on the frequency axis of the extra PRB of the reduced bandwidth (narrowband) smaller than 20 MHz used for the data channel and / or control channel is left. You can leave the center of the carrier bandwidth, you can leave both ends of the carrier band, or you can leave only one end of the carrier band.

In the case of data transmission in a machine type communication (MTC) terminal, data is transmitted using only the reduced 1.4 MHz bandwidth, but the total system bandwidth actually allocated may be smaller than the 1.4 MHz bandwidth. The overall system bandwidth can be 20 MHz, 10 Hz, 5 MHz or 3 MHz, for example. The reduced 1.4 MHz bandwidth may correspond to, for example, 6 physical resource blocks (PRBs). The reduced 200KHz or 180KHz bandwidth may correspond to 1 RB. In the downlink transmission of data or a control signal from a base station to a terminal, 1 PRB-for example, 180 kHz-can be used.

Meanwhile, in case of legacy LTE data transmission, the downlink does not apply a frequency hopping separately because it has the same effect as a frequency hopping by distributing and allocating resources in the frequency domain through frequency distributed scheduling (FDS) scheduling. Frequency hopping through an uplink physical layer data transmission channel (for example, a PUSCH (Physical Uplink Shared Channel)) is applied to only a link. That is, in case of legacy LTE, frequency hopping is not applied separately for downlink data transmission, and frequency hopping through an uplink physical layer data transmission channel (for example, PUSCH (Physical Uplink Shared Channel)) only for uplink data transmission. Has limited application.

However, in case of LTE downlink, FDS scheduling can be used only when the entire bandwidth is wide. When the bandwidth is limited to 1.4 MHz or 200 KHz or 180 KHz, frequency hopping of the entire (data channel and / or control channel) is performed. Method is required.

In the case of LTE downlink data transmission in MTC communication according to an embodiment of the present invention, by using the hopping pattern using the total system bandwidth larger than 1.4MHz bandwidth using the hopping pattern to the frequency hopping (Frequency hopping) to transmit data Can be. The hopping pattern may be periodic or aperiodic. That is, the hopping pattern may not be periodic when data transmission is completed before the period is repeated.

First, an uplink data transmission method in an MTC terminal during machine type communication (MTC) communication according to an embodiment of the present invention will be described.

The MTC terminal transmits data using the total system bandwidth larger than the 1.4 MHz bandwidth, but performs frequency hopping of the 1.4 MHz band using a periodic hopping pattern such as TSTD (Time Switched Transmit Diversity). Data can be transferred. The hopping pattern may be periodic or aperiodic. That is, the hopping pattern may not be periodic when data transmission is completed before the period is repeated.

In the case of downlink transmission of MTC communication, unlike the existing LTE system, the data may be transmitted to the terminal through frequency hopping through the downlink physical layer data transmission channel PDSCH. In addition, in case of uplink transmission of MTC communication, the data may be transmitted to a base station by frequency hopping through an uplink physical layer data transmission channel (for example, a physical uplink shared channel (PUSCH)).

In addition, even when transmitting system information such as a System Information Block (SIB), paging signal, and the like except for a master information block (MIB), frequency hopping may be performed using an overall system bandwidth larger than 1.4 MHz bandwidth.

Specifically, in case of LTE downlink transmission in MTC communication, in addition to data, system information-for example, SIB (System Information Block)-, control information-for example, PDCCH, (E) PDCCH- the entire system larger than 1.4MHz bandwidth Bandwidth can be used to transmit by frequency hopping.

Specifically, in case of LTE uplink transmission in MTC communication, in addition to data, frequency hopping using control system-for example, PUCCH-and a random access signal (for example, PRACH) using a total system bandwidth larger than 1.4 MHz bandwidth Can transmit

Primary Synchronization Signal (PSS) / Secondary Synchronization Signal (SSS) used for synchronization and PBCH indicating system information may not perform frequency hopping.

One frame may consist of ten subframes having a length of 1ms. Each frame may be identified by a system frame number (SFN). SFN can be used to control various transmission periods that may have periods longer than one frame, such as paging and sleep-mode periods or channel status reporting periods.

6 shows an example in which PBCH, PCFICH, PDCCH, and PDSCH are mapped to a downlink frame.

In the LTE system, a PDCCH is allocated to transmit a downlink control signal for controlling a terminal. The region where the PDCCHs of the plurality of terminals are mapped may be referred to as a PDCCH region or a control region.

The PCFICH carries information on the number of OFDM symbols used for the allocation of the PDCCH in the subframe. Information on the number of OFDM symbols to which the PDCCH is allocated is called a control format indicator (CFI). All terminals in the cell must search the area to which the PDCCH is allocated, and thus CIF can be set to a cell-specific value. In general, the control region to which the PDCCH is allocated is allocated to the foremost OFDM symbols of the downlink subframe, and the PDCCH may be allocated to up to three OFDM symbols.

For example, CIF is set to 3, so that the PDCCH is allocated within the three OFDM symbols in the previous subframe. The UE detects its own PDCCH in the control region and may detect its PDSCH through the PDCCH detected in the control region. In the MTC system, in order to efficiently use resources, the PCFICH may not be transmitted every TTI, but a fixed control format indicator (CFI) may be used or only a specific TTI may be used.

If a fixed CFI is used, the value may be promised or transmitted through MIB or SIB.

In addition to the existing PDCCH, an e-PDCCH (enhanced PDCCH) may be introduced as a new control channel. The e-PDCCH may be allocated to the data region instead of the existing control region to which the PDCCH is allocated. As the e-PDCCH is defined, it is possible to transmit a control signal for each UE, and solve a problem that the existing PDCCH region may be insufficient.

6, in the case of MTC communication according to an embodiment of the present invention, a hopping pattern (FH1A, FH2A, FH3A, ... or FH1B, FH2B, FH3B,... Frequency hopping in the 1.4 MHz band using ..) to downlink data, system information (e.g., System Information Block), control information (e.g., PDCCH, e-PDCCH). Through the MTC terminal can be transmitted. In this case, the hopping pattern for the SIB may be implicitly / explicitly obtained by using information included in the MIB and a cell ID obtained during synchronization.

In the case of downlink transmission of MTC communication according to an embodiment of the present invention, the data may be transmitted by frequency hopping through the downlink physical layer data transmission channel PDSCH, unlike the existing LTE. In addition, in the case of uplink transmission of MTC communication according to an embodiment of the present invention, the data may be transmitted by frequency hopping through an uplink physical layer data transmission channel (for example, (PUSCH (Physical Uplink Shared Channel)). In addition, in case of downlink transmission of MTC communication according to an embodiment of the present invention, even when transmitting system information such as a system information block (SIB) except for a master information block (MIB), the bandwidth is larger than 1.4 MHz. Frequency hopping may be performed using the entire system bandwidth.In addition, in the case of uplink transmission of MTC communication according to an embodiment of the present invention, control information (for example, PUCCH) and a random access signal (for example, Even when transmitting PRACH), etc., frequency hopping may be performed using the entire system bandwidth larger than the 1.4 MHz bandwidth.

The MTC terminal may perform communication with a base station using a narrow band. The narrow band is a minimum band used for transmitting information, signals, and data between the MTC terminal and the base station and may be used in units of PRBs or subcarriers.

In MTC communication, frequency hopping between subcarriers within a narrow band may be performed, or inter-band narrow frequency hopping may be performed in units of narrow bands.

Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), and Physical Broadcasting Channel (PBCH) may be divided and transmitted in a plurality of narrow bands of units smaller than 1.4 MHz, resulting in units smaller than 1.4 MHz. By dividing and transmitting in a plurality of narrow bands, the transmission can be extended in the time domain as compared with the case of transmitting through one 1.4 MHz bandwidth. In this case, dividing the existing PSS, SSS, and PBCH into several narrow bands having smaller units than 1.4 MHz may take more time than transmitting the entire PS 1.4 bandwidth without dividing into several. That is, instead of transmitting several PRBs as one with a bandwidth of 1.4 MHz or dividing into narrow bands smaller than 1.4 MHz, the time may be longer. For example, in order to transmit existing 6-PRB data divided into 1-PRB, data must be transmitted for 6 TTIs.

A narrow band according to an embodiment of the present invention may be defined in units of PRBs. For example, the narrow band may continuously define the position of the PRB, but may use adjacent bands based on the center 72 subcarriers. It may or may not be symmetric about the center. It can be set to extend left and right even if it is not symmetrical or not symmetrical from the center until PRB which is not defined as narrow band. The narrowband may be assigned from the low frequency or the high frequency, and may be assigned in the left direction and the right direction with the center as the starting point. Alternatively, the narrowband may be ordered in the form of a circular loop in a clockwise or counterclockwise direction starting from the left or the right with respect to the center.

The narrowband defined within the range of 72 subcarriers excluding the center DC is defined as the central band, and the narrowest band on the left side of the middle band is the lowest narrowband and the rightmost band on the center narrowband. The narrowband in can be defined as the highest narrowband. When the UE needs to monitor the cell's PSS / SSS / PBCH, the UE can retune the frequency of the central 72 subcarriers (excluding the system DC).

The offset may be set to align or link the uplink narrowband with the legacy PUCCH and / or PRACH. In particular, the position of the uplink narrowband may be determined by the legacy PUCCH and / or PRACH + offset.

In order to support the low-cost MTC terminal, a part of the system bandwidth for communication between the MTC terminal and the base station may be set instead of using the entire system bandwidth for the communication between the MTC terminal and the base station. When setting part of this system bandwidth, that is, narrowband, the narrowband may be defined as a set of contiguous physical resource blocks (PRBs).

In the case of the TDD transmission scheme, a narrow band set should be set identically for uplink transmission and downlink transmission. That is, in the case of the TDD transmission scheme, the uplink transmission and the downlink transmission should be set to have the same set of subcarriers.

In order to simultaneously support a plurality of MTC terminals in a base station, a plurality of narrow bands may be set. As described above, when a plurality of narrowbands are set to simultaneously support a plurality of MTC terminals, the narrowbands may be set so as not to overlap between narrowbands in order to reduce interference between MTC terminals. In order to set the narrow band so as not to overlap as described above, the narrow band may be set as a function of the system bandwidth. In reality, in the presence of a large number of terminals, it may be difficult to determine a set of narrow bands so that they do not completely overlap 100% between each narrow band. Some improvement can be made. Therefore, even if a narrow set of overlapping bands is defined, the frequency hopping pattern can be determined not to overlap.

Regarding the downlink narrow band, the downlink narrow band that is completely overlapped within the center 72 subcarriers (excluding the system DC) range may be defined as a center narrow band. In the central narrowband, a broadcasting signal that all MTC terminals should receive may be transmitted. The central narrowband may be used for frequency hopping between narrowbands. The central narrowband may be used for frequency hopping in downlink or uplink data transmission. For example, frequency hopping may be performed using the central narrow band in downlink PDSCH and / or PDCCH transmission. Hereinafter, with reference to FIGS. 10 and 11 will be described in detail.

In addition to the central narrow band, when the system bandwidth per cell is 3MHz or more, a plurality of non-overlapped downlink narrow bands may be specified for the system bandwidth.

A non-overlapped downlink narrowband of 3 MHz may be defined for one cell.

The number of usable narrowbands and the number of subbands can be determined based on the system bandwidth of the cell.

The number of narrow bands that can be set can be determined based on the system bandwidth of the cell. The total bandwidth used by the narrow band (the number of narrow bands x the bandwidth of one narrow band) may be 1/2 or less of the system bandwidth. As a result, some PRBs in the system may not be included in any narrowband established. Some of the bands not used exclusively for the MTC can be separated from the narrow band of the MTC. It is possible to transmit messages, signals and data of a specific downlink or uplink using an edge of the system bandwidth or a central narrowband.

Other narrowbands may overlap with the central narrowband at least for system bandwidth. For example, in order to solve the shortage of the frequency band, when the system bandwidth is 3 MHz, other narrow bands may be implemented to overlap with the central narrow band. In other words, it is possible to operate a narrow band set overlapping. A narrowband not adjacent to the central narrowband may have a size of 6PRB.

In Figure 7, the horizontal axis is the time axis, the vertical axis is the frequency axis, and ■ may be data or system information, paging, etc. for MTC communication. In FIG. 7, □ may be 6 PRBs (ie, 1.4 MHz), or may be 1 PRB.

When hopping the frequency, the hopping may be performed in 1.4MHz units, or in 200Khz units, or by splitting the 1.4MHz bandwidth to hop within the entire 1.4MHz.

FIG. 7 illustrates an example of a frequency hopping pattern when data and / or system information and a paging signal are transmitted between a base station and an MTC terminal through downlink or uplink. The frequency hopping pattern is illustrated in FIG. 13. Without limitation, various hopping patterns may be used.

In the case of frequency hopping such as data and / or system information and paging for MTC communication, various hopping patterns are possible without being limited to the frequency hopping pattern of FIG. 13.

As shown in FIG. 7, frequency hopping may be performed to transmit data and / or system information and paging using the total system bandwidth larger than the 1.4 MHz bandwidth. In this case, a transmission diversity effect may be obtained. There is an effect to improve.

FIG. 8 is a conceptual diagram illustrating a case in which a narrow band having a size of 6PRB is arranged to align with an existing legacy PRB mapping according to an embodiment of the present invention. Referring to FIG. 8, a narrow band has a size of 6 PRBs. The center frequency of the narrow band may be arranged to match the center frequency of the system bandwidth, and the narrow band may be aligned with the existing legacy PRB mapping. Alternatively, the center frequency of the narrow band does not coincide with the center frequency of the system bandwidth as shown in FIG. 5, and the narrow band may be arranged to align with the existing legacy PRB mapping. .

Referring to FIG. 9, the narrow band has a size of 5 PRBs, and the center frequency of the narrow band corresponds to the center frequency of the system bandwidth. Narrow bands can be arranged to align with existing legacy PRB mapping. The center frequency of the narrow band does not coincide with the center frequency of the system bandwidth, and may be arranged such that the narrow band is aligned with the existing legacy PRB mapping.

A narrow band according to embodiments of the present invention may have a size smaller than 6 PRBs, for example, 5 PRBs, 4 PRBs, 3 PRBs, and a size larger than 6 PRBs, for example. It may have 7 PRBs, 8 PRBs, 9 PRBs or 12 PRBs that are twice the size, 18 PRBs that are three times the size. Narrow band size may be fixedly used in one of a plurality of sizes selectively, or may be adaptively used depending on the situation. For example, if the narrowband size is made smaller, the number of narrowbands increases, so that a plurality of MTC terminals may be supported or more hoppable bands may be provided in frequency hopping. Increasing the narrow band size can increase the transmission data rate.

10 is a conceptual diagram for supporting a downlink narrowband terminal in an existing wideband system according to an embodiment of the present invention. FIG. 10 illustrates one subframe, eg, 1 ms, of a downlink frequency of a legacy legacy terminal. By operating in the re-tuning method as described above, not only the frequency diversity gain can be obtained, but also the entire system band can be efficiently utilized, and a plurality of MTC terminals can be operated.

Each cell may be implemented to support an existing legacy terminal and an MTC terminal according to an embodiment of the present invention.

Referring to FIG. 10, in case of a downlink frequency of a legacy legacy terminal, PSS / SSS, MIB, and SIB are located in a center 6PRB, and in the case of an MTC terminal according to an embodiment of the present invention, a narrow band ) May be set to be aligned with the center 6PRB (including PSS / SSS, MIB, and SIB) of the downlink frequency of the legacy legacy terminal, or may be retuned to work with an offset. have.

In the case of the MTC terminal according to an embodiment of the present invention, the downlink narrow band (narrow band) may be re-tuned to a new frequency different from the center 6PRB frequency position. Specifically, the location of the new downlink narrowband region may be set to the downlink center frequency + offset of the legacy terminal. In the case of an MTC terminal according to an embodiment of the present invention, the downlink narrow band region may include a narrow band control channel based on an E-PDCCH, for example, the downlink narrow band ( N-band region may include E-PDCCH and PDSCH. In the case of an MTC terminal according to an embodiment of the present invention, the downlink narrow band region is illustrated as one narrow band region in FIG. 10 but may be configured as a plurality of narrow band regions.

FIG. 11 illustrates one subframe of an uplink frequency of a legacy legacy terminal, for example, 1 ms. By operating in the re-tuning method as described above, not only the frequency diversity gain can be obtained, but also the entire system band can be efficiently utilized, and a plurality of MTC terminals can be operated.

Referring to FIG. 11, in case of an uplink frequency of a legacy legacy terminal, a PUSCH is located in a center 6PRB, and in the case of an MTC terminal according to an embodiment of the present invention, a narrow band is a legacy legacy terminal. The offset may be set to be aligned with the center 6PRB (including PUSCH) of the uplink frequency or re-tuned to work with the uplink frequency.

In the case of an MTC terminal according to an embodiment of the present invention, the uplink narrow band may be retuned to a new frequency different from the center 6PRB frequency position. Specifically, the position of the new uplink narrowband region may be set to an uplink center frequency + offset of the legacy terminal. In the case of an MTC terminal according to an embodiment of the present invention, the uplink narrow band region may include, for example, a PUSCH and a PUCCH. In the case of an MTC terminal according to an embodiment of the present invention, the uplink narrow band region may be set to one narrow band region or may be set to a plurality of narrow band regions. The uplink narrowband region may be set in 1-RB units or sub-carrier units.

FIG. 12 is a conceptual diagram illustrating a pattern in which frequency hopping occurs between narrow bands having a size of 6PRB using an overall system bandwidth greater than a 1.4 MHz bandwidth according to another embodiment of the present invention.

A plurality of narrowbands to be used may be preset, a PRB index may be allocated to each narrowband, and the location of the narrowband to be used by the MTC terminal may be informed using the PRB index.

Referring to FIG. 12, the narrow bands NB1, NB2, ..., NB8 have sizes of 6 PRBs, and eight narrow bands NB1, NB2, ..., NB8 We have PRB indexes 0-5, 6-11, ..., 42-47 for each. For example, eight narrow bands NB1, NB2, NB3, NB4, NB5, NB6, NB7, and NB8 are NB6, NB5, NB8, NB7, NB1, It has NB2, NB4, NB3 hopping pattern.

As information for frequency hopping, user information may be used for frequency hopping in uplink, and system information may be used for frequency hopping in downlink.

When the base station transmits data and / or system information in a frequency hopping manner, a technique for preventing a collision is required. Specifically, in order to prevent collision of data and / or system information, paging, etc. by base station and terminal, the frequency hopping pattern may directly or indirectly form a base station ID and / or a terminal ID. It can be generated or determined by using, and control information or resources can be allocated by using a base station ID (or cell ID) and / or a terminal ID directly or indirectly.

Each hopping pattern is generated as a function of base station ID in order to prevent collision between hopping patterns between base stations and hopping patterns by directly or indirectly utilizing terminal IDs to prevent hopping patterns between multiple MTC terminals in the same base station. Create The hopping pattern is a pattern that determines which frequency band (PRB unit or narrow band unit) is to be transmitted for each time unit performing hopping in a two-dimensional pattern of time and frequency. Therefore, in order to prevent hopping patterns of different base stations from each other, the hopping frequency bands used at the same time must be different according to the base station IDs. A method of generating a specific sequence to refer to a hopping frequency band for each time unit for performing hopping. This sequence is orthogonal or quasi-orthogonal to minimize the possibility of collision of the hopping pattern. In the same way, the terminal ID is used to minimize the possibility of collision of the hopping pattern between the terminals in the same base station. Even if some collisions of the hopping patterns occur, data may be restored by gains due to repetitive transmission, and thus only the mutually orthogonal hopping patterns are not used.

In the case of downlink, a frequency hopping pattern may be determined or generated with a base station ID (or cell ID) and / or SFN. SFN is an important parameter exchanged between the base station and the terminal for time synchronization. The base station may change the start, stop, end and period of hopping patterns, hopping frequency band sets, and hopping time units using or using the SFN. . The hopping time unit can be operated smaller than the frame unit as a slot or subframe unit.

The base station ID may include a Cell ID. The terminal ID may include, for example, an International Mobile Subscriber Identity (IMSI), a Temporary Mobile Subscriber Identity (TMSI), a Globally Unique Temporary Identifier (GURI), or a Radio Network Temporary Identifier (RNTI).

A method of generating a hopping pattern by indirectly using a base station ID and / or a terminal ID includes generating the first specific sequence with the corresponding base station ID and / or the terminal IDs first, and then generating the generated first specific sequence. The final hopping pattern is defined and used through the secondary deformation. Secondary modifications may include combinations with other hopping patterns, different precoding applications depending on frequency or time, scrambling or cyclic shifts.

In addition, IMSI is a very important information for security, so when the IMSI is used, the method of generating a hopping pattern by allowing the UE to determine the hopping pattern on its own without directly exchanging IMSI is also indirectly used to generate the hopping pattern. Belongs.

The entity that actually generates the hopping pattern and transmits the signal may be a base station in downlink and an uplink in terminal.

Information about the hopping pattern may be exchanged as control information (signaling) between the base station and the terminal.

Alternatively, in order to reduce overhead caused by exchanging information about the frequency hopping pattern between the base station and the terminal, the mutual IDs are known to each other so that the information about the hopping pattern itself may not be exchanged. Accordingly, by adding the frequency hopping information through MIB, SIB, or PDCCH / EPDCCH, only the frequency hopping may be notified to reduce the overhead caused by exchanging information about the frequency hopping pattern.

Referring to FIG. 15, when the base station transmits UE data to the MTC terminal during downlink transmission of the MTC communication of the present invention, the terminal data is not transmitted by adding the UE ID to the terminal data. After transmitting only to the terminal, the MTC terminal multiplies its terminal ID. If the terminal ID is correct, CRC error does not occur when CRC masking, and if the terminal ID is incorrect, CRC error is generated when CRC masking, thereby reducing overhead by not transmitting the terminal ID. That is, in the case of MTC communication according to an embodiment of the present invention, for example, when the CRC masking method described above is applied to a broadcast channel, the MTC is partially used by using resources of a broadcast channel carrying information common to all terminals. Important information that should be given differently for each terminal may be urgently delivered. In addition, in the case of uplink, instead of transmitting all the N bits of data as in legacy LTE, the UE provides only limited resource allocation information by using data of bits smaller than N. By enabling transmission within a resource, MTC communication is possible while reducing overhead.

MTC system information (MIB) transmission technology

Currently, in the case of Machine Type Communication (MTC), system information for MTC communication such as MTC-Master Information Block (MTC-MIB) / MTC-System Information Block (MTC-SIB) is separately transmitted.

The Master Information Block (MIB) is transmitted every 40 ms through the PBCH at a transmission time interval (TTI), which consists of four OFDM symbols located on 72 center subcarriers in each corresponding frame. Mapped.

There is a reserved 10-bit unused bit in the general LTE MIB, it is possible to send additional information (or parameters) for MTC communication using the 10-bit. Since the MIB can transmit only a few bits in a limited amount, very important parameters must be included.

Referring to FIG. 16, additional information transmitted using the reserved 10-bit may be, for example,

Whether the base station supports the MTC terminal (1 bit) (1001)

Supports Coverage extension (CE) devices (1 bit) (1003)

Time Frequency Position (2 to 3 bits) of MTC-SIB1 (1005)

Whether a repetition level of MTC-SIB1 is included (1007)

Transport block size (2 bits) of MTC-SIB1 (1009)

Control Format Indicator (CFI) (2 bits) (1011)

-Number of repetitive transmissions for performance (1013)

-Starting point position or PCFICH position information of the MTC PDCCH (1015)

It may include.

Here, the CFI indicates the number of OFDM symbols used to transmit control channels (PDCCH, PHICH) in each subframe, and the PCFICH indicates the size of the control region as the number of OFDM symbols. Tell me directly or indirectly if this starts.

In addition, additional information transmitted using the reserved 10-bit of the MIB for MTC communication is

Whether frequency hopping is on or off (1021)

Information about the repetition pattern (1023)

Whether to use persistent scheduling to send the location of a resource (1025)

Resource location information (1027) for persistent scheduling

And the like.

In this case, persistent scheduling may improve performance by reducing overhead (or by allocating resources), for example, by minimizing (or allocating resources) control signals for scheduling when transmitting a specific pattern (repetitive pattern or frequency hopping pattern). It can be effective. In this case, the fixed scheduling is, for example, a method of fixing a specific pattern and transmitting it periodically or aperiodically, a method of notifying the pattern first and continuing to transmit the pattern, and a set of several patterns ( and a method of transmitting a pattern selected from the set of patterns periodically or aperiodically in advance. The frequency hopping on / off (1021), the information about the repetition pattern (1023) is a specific frequency hopping pattern group or a specific repeating pattern group to be used by the base station using the MIB or SIB You can also send

Information sent to the MIB can also be sent in the SIB. Therefore, transmission of bits related to persistent scheduling may be performed in SIB. However, important information with high priority may be transmitted through the MIB. Alternatively, information necessary for decoding the SIB may be transmitted through the MIB.

Information on whether 1025 uses persistent scheduling may not be transmitted through a MIB, SIB, or a specific channel. That is, instead of transmitting 1025 information on whether to use persistent scheduling through a MIB, SIB, or a specific channel, by simply using persistent scheduling that transmits a fixed location of a resource. It is possible to reduce signaling overhead and to enable stable communication. At this time, a frequency hopping pattern, a repetitive transmission pattern, and the like can also be used in a permanent manner. That is, according to an embodiment of the present invention, by applying a fixed scheduling (persistent scheduling) to the repetitive transmission pattern, frequency hopping pattern in the MTC, as well as the location of the resource (resource) fixed as in the existing LTE, repeated transmission pattern, frequency hopping The transmission pattern itself, such as a pattern, can also be fixed to reduce overhead.

Here, since the existing MIB is system information, only the information common to all MTC terminals is included. However, in an embodiment of the present invention, the MTC terminal receives such system information, and has a system function by defining a specific function in the standard that receives an additional terminal ID such as RNTI, GUTI, IMSI, TMSI of the MTC terminal as input. In addition, different parameters may be set for each terminal. That is, the base station may transmit the system information (MIB or SIB) including the direct ID information of the specific MTC terminal. For example, by adding the terminal ID such as RNTI, GUTI, IMSI, TMSI of the terminal to the system information in the same manner as above for the DRX (Discontinuous Reception) Cycle parameter and transmitting using the reserved 10-bit of the MIB. Different parameters can be set for each terminal. Specifically, the DRX cycle may be determined by substituting the IMSI value of the MTC terminal itself in the SFN (System Frame Number) transmitted from the base station to the MIB and SIB1.

As another example, the MTC terminal may be configured to recognize a system frame number (SFN) by receiving the MIB and SIB1 from the base station, and set the DRX cycle parameter by applying the IMSI value of the MTC terminal to the SFN. have.

Since the DRX cycle is determined as described above, its frequency hopping pattern or repetitive transmission pattern may be determined in the same manner as described above.

MTC system information (MIB) repetitive transmission technology

Currently, in the case of machine type communication (MTC), system information for MTC communication such as MTC-MIB / MTC-SIB is separately transmitted.

In the case of an MTC terminal, the MIB system information is preferably transmitted repeatedly to improve performance.

In the case of MTC terminal, the coverage extension is required more than 20dB, but only bandwidth of 1,4MHz should be used, and if one receiving RF chain is used, the data reception performance is inevitably deteriorated compared to the conventional mobile communication terminal. Therefore, there is a need for a variety of advanced technologies that can increase the performance even in this environment to achieve 20dB or more of coverage. These methods include a method for greatly improving SNR through repetitive transmission and a method for securing diversity gain by frequency hopping the 1.4 MHz band for the entire system band.

However, this repetitive transmission has a problem of increasing power consumption, so the number of repetitive transmissions should be minimized whenever possible. Therefore, it should be used with additional performance improvement techniques such as frequency hopping and beamforming.

However, in the case of the MIB, the band of 1,4 MHz is fixed to the center frequency of each frame as described above, and thus it is impossible to use the frequency hopping technique. Therefore, we have to rely on repetitive transmission.

In the case of MIB, repeated transmission includes a method of transmitting the same signal and a method of transmitting the same data but having different forms of signals, for example, different coding. In the case of repetitive transmission of MIB, data, and control information, the same information is transmitted but different signal types, for example, different codings, can result in a precoding diversity effect. For example, in the case of repetitive transmission of MIB, data, and control information, the same information is transmitted, but the coding is differently transmitted to 1, 1, 1, 1, .. once, 1, -1, Can be sent in the form 1, -1, ...

If HARQ technique is applied to this repetitive transmission, it is possible to increase performance as well. However, since MIB is one-way communication rather than bidirectional communication, HARQ is also impossible.

The repetition transmission method for the MIB may be selected from the following three repetition methods.

In the first method, the base station repeatedly transmits the MIB at a predetermined period (for example, 40 m).

In the second method, the base station dynamically determines whether to repeatedly transmit the MIB every predetermined period (for example, 40 ms).

In a third method, the base station repeatedly transmits the MIB according to the pattern. Here, the pattern may be composed of predefined periods. For example, the pattern may consist of a plurality of 40 ms or predefined time intervals.

Iterative transmission technology of system information or data other than MIB

Repeated transmission of system information or data other than the MIB includes a method of transmitting the same signal and a method of transmitting the same data but different signals.

The repetition transmission method for system information or data other than the MIB may be selected from the following three repetition methods.

In the first method, the base station repeatedly transmits system information or data other than the MIB at a predetermined period (for example, 40 m).

In the second method, the base station dynamically determines whether to repeatedly transmit system information or data other than the MIB every predetermined period (for example, 40 ms).

In a third method, the base station repeatedly transmits system information or data other than the MIB according to the pattern. Here, the pattern may be composed of predefined periods. For example, the pattern may consist of a plurality of 40 ms or predefined time intervals.

In addition, the MTC communication may not only repeatedly transmit the MIB but also perform bundling that repetitions or aggregates and transmits control information including virtually all data or system information, for example, a system information block (SIB).

TTI bundling is also a kind of repetition technique. The only difference is that in case of TTI bundling, repetitive transmission is performed on consecutive subframes. Coverage expansion can be achieved by using the TTI bundling technique for all data or system information. Bundling is a kind of repetitive transmission, but it is different from general repetitive transmission. In applying HARQ, it is possible to send data of the next TTI only when ACK is received. However, when NACK is received, it is not possible to send new data until it is properly received. In situations where the bandwidth is so narrow that even a lot of data needs to be sent repeatedly, this operation can take too much time to send data, which can also affect internal buffer control. Therefore, bundling technology is to bundle and send data corresponding to several TTIs to be sent at once.

MTC repetitive transmission technology according to another embodiment of the present invention

The MTC repetitive transmission technique according to another embodiment of the present invention may perform repetitive transmission in downlink. Hereinafter, the downlink will be described as an example.

The MTC repetitive transmission technique according to another embodiment of the present invention can adaptively adjust the constraints upon frequency hopping according to channel conditions and / or data characteristics / personality.

The MTC repetitive transmission technique according to another embodiment of the present invention adaptively adjusts a hopping bandwidth, a prohibition band, a prohibition time / pause time, and a hopping period pattern during frequency hopping according to channel conditions and / or data characteristics / personality. Or variable. That is, the frequency hopping pattern can be changed according to the channel situation (confirmed in the standard conference), and specifically, the MTC terminal is divided into small and large coverage terminals for coverage extension according to the channel situation. can do.

The further the distance from the base station, the weaker the signal strength, the more difficult communication is. One of the purposes of MTC communication is to extend the communication range by 20 dB, and to enable MTC communication even in a place where the strength of radio waves is 20 dB smaller than the existing LTE. As the intensity of the radio wave decreases, the SNR may be lowered, and communication may not be possible because the SNR may not be met. However, the intensity of the radio wave does not fall only when it is far away from the base station, but in the case of an underground terminal, a metal-closed space such as an iron gate, underwater, etc., as in the case of the IoT terminal used as a sensor, the strength of the radio wave is close even if the distance from the base station is close. Will fall significantly.

When the strength of the radio wave is weak, it is difficult for the base station to successfully receive the RACH transmitted by the MTC terminal. Basically, when the RACH is successfully received, the MTC terminal can register with a desired base station. Therefore, in order to cope with such 20dB propagation loss, a method for improving SNR of 20dB or more is required. One of the methods is the aforementioned repetition transmission technique. However, if a lot of repetition transmissions are performed, the data rate decreases and the transmission time takes a long time, so it is not good for power consumption and also takes up resources. Therefore, the number of repetition transmissions is reduced as much as possible. There is a need.

If you are close to the base station or if the loss of propagation strength is not as high as 20 dB, you do not need to operate this repetition transmission technique. Therefore, the MTC terminal is largely small and large coverage terminals according to a loss amount of a predetermined propagation intensity (for example, 10 dB, 12 dB, 13 dB, 14 dB, 15 dB, etc.) (or according to the SNR). By dividing into branches and operating with optimized parameters in each case, the data rate is reduced by reducing the number of repetition transmissions when the strength of the radio wave does not drop significantly or when the loss of the radio wave intensity does not become as large as 20 dB. As a result, it is possible to reduce negative effects due to increased transmission time, increased power consumption, and reduced transmission efficiency.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust the frequency hopping pattern according to channel conditions and / or data characteristics / personality.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust or vary the frequency hopping range according to channel conditions and / or data characteristics / personality.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust the frequency hopping bandwidth according to channel conditions and / or data characteristics / personality. Frequency hopping patterns may be used by selectively selecting specific bands depending on channel conditions and / or data characteristics / personality. If the channel state of a particular frequency band is not good, the frequency band can be implemented not to be used. When the channel state of a specific frequency band is good, the frequency hopping may be implemented using only the frequency band.

A guard band or a prohibition period (or idle period) may be adaptively adjusted according to channel conditions and / or data characteristics / personality. That is, the frequency hopping pattern may be used by designating a specific band as a prohibition band according to the channel state or by designating a specific time as the prohibition time according to the channel state.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust the frequency hopping period according to channel conditions and / or data characteristics / personality.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust the length of the frequency hopping pattern according to channel conditions and / or data characteristics / personality.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust the frequency hopping pattern repetition number according to channel conditions and / or data characteristics / personality.

If the channel condition is excellent, frequency hopping may not be performed. In this case, information on whether frequency hopping is used or not may be transmitted from the base station to the MTC terminal.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively change the hopping pattern according to the importance of the data and the characteristics / nature of the data. For example, important data such as MIB, SIB, control information, 119 emergency data is more important than general data, in this case, the diversity gain is increased by increasing the number (or frequency) of hopping pattern repetition, thereby reducing the reception error. It can improve performance. Alternatively, it may be difficult to inform the hopping pattern of such important data, so that frequency hopping may be implemented.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively change the hopping pattern according to the amount of data. Frequency hopping may be slow when there is a lot of transmission data.

The frequency hopping bandwidth may be 6PRB, 5PRB, 4PRB, 3PRB, 2PRB, or 1PRB depending on the amount of transmitted data.

As described above, the prohibition time, the prohibition band, the prohibition bandwidth, the frequency hopping start time, the frequency hopping end time, and the like may inform the MTC terminal from the base station.

MTC repetitive transmission technology according to another embodiment of the present invention can be applied to paging, SIB, RAR.

The MTC repetitive transmission technique according to another embodiment of the present invention can be implemented to use a predefined frequency band without using frequency hopping for the PSS, SSS, or PBCH that the MTC terminal first receives.

The MTC repetitive transmission technique according to another embodiment of the present invention may adaptively adjust a position at which frequency hopping starts according to the type of MTC terminal. In the MTC repetitive transmission technique according to another embodiment of the present invention, the position at which frequency hopping is started for each MTC terminal may be adjusted differently.

The MTC repetitive transmission technique according to another embodiment of the present invention may be applied to uplink.

How to inform narrowband information during frequency hopping

In the frequency hopping for MTC communication, the frequency hopping may be performed only within the specific narrowband set by limiting to a specific narrowband set.

When LTE downlink frequency hopping for MTC communication, narrowband usage information such as the specific narrowband set may be informed in the following manner.

First, the base station informs the MTC terminal of an available narrowband set by using system information such as MIB or SIB that is broadcasted to all MTC terminals in the network repeatedly in the network. The terminal may be used in common. Alternatively, MIB and / or SIB encoding may be encoded with a code indicating a specific number to inform MTC terminal of available narrowband set usage information. By multiplying the MIB and / or SIB data by a specific code representing each narrowband set and encoding (or encoding the specific code), the available narrowband set usage information may be informed to the MTC terminal.

Meaning that the MIB and / or SIB data is multiplied by a specific code representing each narrowband set to be encoded and transmitted, for example, when the base station operates a total of 10 narrowband sets. Instead of sending the set in bits, MIB and / or SIB data is multiplied by a specific code representing each narrowband set. Specifically, the MIB and / or SIB data is multiplied with a code representing a specific narrowband set, and the MTC terminal multiplies the received MIB and / or SIB data by changing 10 codes, thereby successfully decoding the double CRC error. By knowing what the code of the case is, we can see which narrowband set has been set.

For example, when the base station operates the number of cases of a total of 10 narrowband sets, the narrowband set may be directly informed to the MTC terminal through the MIB and / or SIB or 10 types in advance. It is also possible to tell the MTC terminal to use RBs several times and RBs as narrowband sets directly without setting a narrowband set of. Resource location of the PDSCH transmitting the SIB may be informed by the PDCCH. If a narrowband set is used, it is necessary to know which narrowband set to use to receive PDCCH or PDSCH. Therefore, the narrowband to which the SIB is predetermined is to be sent or the narrowband to be sent to the SIB should be informed via the MIB. Since PDSCH transmitting SIB is frequency hopping, when the information of the narrow set is put into the SIB, since the narrow band set of PDSCH transmitting SIB is not known, decoding at the MTC terminal is not possible. It needs to be fixed in a band set. Alternatively, the MIB may inform only the narrowband set of the PDSCH for the SIB and the narrowband set to be used for the actual data transmission through the SIB. Alternatively, in order to set a narrowband set differently for each MTC terminal, narrowband set information may be transmitted using a PDCCH. In this case, a narrowband set should be previously determined for a PDCCH commonly used by the entire MTC terminal.

In addition, the terminal ID such as RNTI, IMSI, GUTI, etc. may be substituted into a predetermined equation to determine a narrowband set or a frequency hopping pattern allocated to the MTC terminal itself. That is, the system information and the terminal ID may be used together to determine the narrowband set or the frequency hopping pattern allocated to each MTC terminal in the network.

Secondly, by using a downlink control channel (for example, PDCCH) delivered to a specific group of users, a common set of available narrowbands is notified to a specific group of users, and the user terminal of the specific group may be commonly used.

In addition, the terminal ID such as RNTI, IMSI, TMSI, or GUTI may be substituted into a predetermined equation to determine a narrowband set or frequency hopping pattern allocated to the MTC terminal itself. That is, the downlink control channel transmitted to a specific group of users and the terminal ID may be used together to determine a narrowband set or a frequency hopping pattern allocated to each MTC terminal in the network.

Third, a downlink control channel delivered to a specific user, for example, a UE-specific EPDCCH, may be used to inform a specific user of a narrowband set available to a specific user terminal.

Fourth, in determining the available narrowband set by the three methods described above, the cell ID, the system frame number (SFN), the subframe index (Subframe) as well as the terminal ID such as RNTI, IMSI, TMSI, or GUTI are used. index, and slot index (Slot index) can be further utilized to determine the available narrowband set or frequency hopping pattern.

Specifically, a narrowband set assigned to each independent MTC terminal in a network by substituting a system frame number (SFN) transmitted from the base station as system information such as MIB and SIB1 and an IMSI value of the MTC terminal itself in a predetermined equation. Alternatively, the frequency hopping pattern can be determined. In the same way, independent scheduling for each MTC terminal can be made by adjusting each subfrane / slot multi-subframe scheduling information by additionally utilizing subframe index and slot index as well as SFN and terminal ID. Allow information to be determined.

In the same way, in addition to SFN and UE ID, subframe index and slot index can be used to control each subfrane / slot multi-subframe scheduling information for the corresponding slot or subframe. Independent scheduling information may be determined for each terminal.

This maximizes system efficiency by minimizing overhead by delivering only information common to all users or a specific group to the actual communication, and allowing the remaining steps to be determined by themselves without the actual communication step.

Fifth, the frequency hopping period may be informed to the MTC terminal, and when the frequency hopping period is completed, the narrowband set available in the control information (MIB, SIB, PDCCH or EPDCCH) may be informed and the narrowband set may be used until the next frequency hopping period.

Operating method according to difference of coverage enhanced

The coverage enhanced level can be divided into a plurality of stages. For example, the extent to which coverage can be extended can be managed in two stages.

All channels within the MTC terminal may be set to the same coverage enhanced level. A coverage level is configured for all channels in an MTC terminal (A single CE level is configured for all channels in a UE). One Coverage Enhanced level may consist of a set of repetition times for at least PDSCH, PUSCH and / or MPDCCH (One CE level can be configured with a set of repetition numbers at least for PDSCH, PUSCH & MPDCCH ).

Which mode of mode 1 or mode 2 is used may be known for all channels in the MTC terminal (Which modes is used is known for all channels in a UE).

Here, mode 1 describes the case where the repetition agrees with no repetitions and the low number of repetitions (Mode 1 describes behaviors for no repetitions and small number of repetitions). (Mode 2 describes behaviors agreed for large number of repetitions). Here, the information repeatedly transmitted here may be system information MIB, system information other than MIB, or data.

The mapping of each coverage enhanced level to the mode may be indicated by RRC or signal.

In addition, the HARQ process number can be adaptively adjusted according to each coverage enhanced level. For example, it may be adjusted so that the HARQ process number decreases as the coverage gets further (or covers farther). The HARQ process number can be up to two, three, or four.

Receiving technology in MTC terminal

The MTC terminal may receive only one when multiple information is received at the same time.

However, if there is important information such as paging (data arrival notification signal), system information, etc. among simultaneous data, it can be implemented to set the priority.

When the MTC terminal receives a plurality of pieces of information at the same time according to an embodiment of the present invention, the method of determining the priority may be implemented to receive and decode the priorities in order of MIB-> SIB-> Paging-> Data.

MTC UE uplink random access technology

In relation to coverage improvement, an RACH process in an MTC terminal is important.

Currently, in the case of machine type communication (MTC), since the data rate is about 100 kbps (fixed bandwidth at 1.4 MHz), there is a need for a method capable of greatly expanding coverage while maintaining low power in an MTC terminal.

RACH process in MTC terminal for coverage improvement In this regard, when repetition transmission is performed on a signal (eg, PRACH preamble) transmitted from a terminal to a base station for performance improvement,

1) periodic repetition transmission,

2) dynamic repetition transmission or

3) It is possible to transmit repetition fixedly.

In the case of periodic repetition, a signal (for example, PRACH preamble) may be repeatedly transmitted from the MTC terminal according to a predefined period.

In the case of dynamic repetitive transmission, the MTC terminal may be configured to dynamically determine whether to transmit a signal (for example, PRACH preamble) at every repetition period. Herein, parameters related to repetitive transmission such as repetition and / or repetition period may be determined by the base station or the network, or may be determined by the MTC terminal or may use a preset value.

The signal (eg, PRACH preamble) may be repeatedly transmitted according to a repetition pattern composed of a specific number of consecutive periods.

The base station determines the existence of the MTC terminal (or MTC coverage extension terminal) with the PRACH preamble sent by the MTC terminal. That is, the PRACH preamble set is made separately for the MTC terminal, and the base station may distinguish between the MTC terminal (or MTC coverage extension terminal) and the general terminal (or general MTC terminal) due to the difference in the PRACH preamble.

The PRACH preamble of the existing LTE can be used as it is, but the code set and resource information to be used as the MTC-SIB can be informed. It is possible to divide and manage the PRACH code set into several. Accordingly, the base station can determine the CE level based on whether the terminal transmitting the PRACH to the set and the resource is the MTC terminal and the number of repetitive transmissions or the resource information.

The PRACH preamble is a kind of code and may use a Zadoff chu code. Alternatively, the PRACH preamble is not binary code but may be multiplied by a binary code to create a new code.

In particular, with respect to the RACH process in the MTC terminal for coverage improvement, a method of distinguishing an MTC coverage extension terminal from a general terminal using a PRACH signal is required.

The method for distinguishing MTC coverage improvement terminal from a general terminal without transmitting or receiving separate control signals is as follows.

The base station can maximize efficiency by dividing the MTC terminal and a general LTE / LTE-A terminal (Legacy terminal), and by operating a small coverage (large coverage) terminal and a laser coverage (larger coverage) terminal within the MTC terminal. .

1) A method of classifying a PRACH preamble (ie code division: CDM) is a method in which a base station defines and operates a set of dedicated PRACH preambles for a separate MTC terminal.

2) How to divide time and frequency resource location (FDM, TDM)

3) 방법 A method of distinguishing a pattern generated by combining and combining a specific one pattern indicating the MTC terminal and the existing PRACH preamble (similar to the CDM, but the difference is to apply one more code to the existing code)

In particular, in the case of a method of distinguishing with a specific pattern referring to the MTC terminal of 3), it may be implemented by adding a new pattern to an existing PRACH preamble code code.

For example, in the case of a method of distinguishing with a specific pattern referring to the MTC terminal of 3), the existing PRACH preamble is used as it is, but when the existing PRACH preamble is repeated, the TDM or FDM pattern is not repeatedly sent as it is. Alternatively, the MTC coverage improvement terminal and the general terminal can be distinguished by implementing a code value of the CDM. Specifically, 100110 is repeatedly sent. According to the index of the repetition pattern (for example, 0 to 5 can be assigned depending on the type of the repetition pattern), 100110 is sent as it is, and then inverted to send 011001. As a result, the MTC coverage improvement terminal can be distinguished from the general terminal. Generalizing this results in the form of c_i_code (existing PRACH preamble code) + new_code or c_i_code (existing PRACH preamble code) x new_code (in case of CDM). In the case of CDM, a new PRACH preamble code is created by combining new codes with existing PRACH preambles in various ways, or an entirely new MTC dedicated preamble set. The end result is yet another PRACH preamble in the CDM.

Alternatively, resource allocation patterns such as TDM / FDM can be changed based on this new_code. TDM and FDM can be sent by periodically changing the code itself, or can be divided into TDM, FDM pattern itself. As a result, the code is changed differently according to the repetitive transmission pattern. Instead, the change pattern has a unique specific pattern representing the MTC CE terminal. Specifically, one specific pattern indicating the MTC terminal includes a CRC pattern currently being used in the downlink control channel, and in the downlink control channel, the CRC output may be XORed with the C-RNTI. Therefore, this can be seen as a code change based on ID such as C-RNTI. In addition to these IDs, it is also possible to define a new code and to XOR, multiply or add the new code and the existing code. Since it is repeated several times anyway, when the same code is repeated several times, the same code transmitted repeatedly each time in a repetition such as reversing the sign of the code when it is transmitted evenly or oddly You can change it periodically in certain ways. The resource allocation pattern is a method of periodically changing a time and frequency position of a transmitted resource with a certain pattern when repeatedly transmitting a code that is repeatedly transmitted many times. In addition, when the PRACH code is assigned to a specific time and frequency location, there is also a method for recognizing the MTC CE terminal.

The above example is a method for distinguishing an MTC coverage improvement terminal from a general terminal by combining a CDM and a repeating transmission pattern. That is, as one of methods for recycling the PRACH code used in the existing LTE, the MTC terminal may combine the repeated transmission pattern with the existing PRACH code because the PRACH needs to be repeatedly transmitted several times. That is, the MTC coverage improvement terminal and the general terminal can be distinguished by simply modifying and using the existing PRACH preamble code in a specific pattern for each repeated transmission. In order to distinguish between the MTC coverage improvement terminal and the general terminal, the modification can be easily made without any collision with any existing code.

Another method is a method of combining a specific code representing the MTC terminal of the above 3) and the existing PRACH preamble code. Currently, LTE finds out what its own PDCCH is through blind decoding in case of PDCCH. At this time, the method used is a method of transmitting a new CRC generated by XORing its ID (C-RNTI in the case of LTE) with the CRC and transmitting it to the DPCCH. Therefore, the receiver can easily identify whether it is its own PDCCH through blind CRC check. This way, if you use any code that is fundamentally transformed into any other code (e.g. XOR) with certain other code, you will be able to easily determine whether it is modified or not. Using this concept is method 3). That is, one specific code indicating the MTC terminal is determined, and the specific code is combined / modified with the existing PRACH code. In case of LTE, since the existing PRACH code is not a binary code, it cannot be simply transformed by XOR, and it must be modified by other methods such as multiplication.

The RAR message and the paging message may be applied to three reception modes as follows for the MTC terminal having low complexity and the MTC terminal operating in the cell extension mode.

1) Option 1

The RAR message and the paging message are received by the PDSCH scheduled by the M-PDCCH, that is, by the PDSCH whose schedule information is transmitted by the M-PDCCH.

2) Option 2

The RAR message and the paging message are received in the DCI of the M-PDCCH.

3) Option 3

Receive RAR message and paging message to M-PDCCH-less PDCSH.

Receiving a single MAC RAR within a narrow band may support using the DCI of the M-PDCCH of Option 2.

Receiving multiple MAC RARs within a narrow band may support the use of a PDSCH scheduled by M-PDCCH of Option 1.

When the number of MAC RARs is smaller than a specific reference value or the size of the MAC RAR is smaller than a specific reference value, a part of the MAC RAR may be received by the DCI of the M-PDCCH and the remaining part of the MAC RAR may be included in the PDSCH.

On the contrary, when the number of MAC RAR is larger than a specific reference value or when the size of the MAC RAR is larger than a specific reference value, the MTC terminal is received by the MTC terminal using PDSCH or PDSCH scheduled with M-PDCCH without using DCI of M-PDCCH. You may.

The base station may indicate whether to support the reception mode of the RAR or paging message in the SIB. For example, if the base station indicates that it only supports option 1, then option 1 may be used for the single MAC RAR as well, which is received by the PDSCH scheduled by the M-PDCCH.

The MTC terminals of the present invention can be used in various applications, low power consumption is required, and can be applied when communication for infrequent small burst transmissions is used. For example, MTC terminals may be applied to wearable devices for smart metering for power metering, implementation of health-related applications, and the like.

1 is a schematic block diagram of an MTC terminal according to an embodiment of the present invention, Figure 2 is a schematic block diagram of an MTC communication system according to an embodiment of the present invention.

1 and 2, the MTC terminal 100 includes a transceiver 120, a processor 110, and an antenna 130, and according to the embodiments of the present invention as described above with the base station 120. MTC communication including MTC frequency hopping, MTC system information (MIB) transmission, and MTC UE uplink random access is performed.

The transceiver 120 receives data and control signals (downlink data presence message, etc.) from the base station 120 through the antenna 130 through the downlink (152), and the uplink (to the base station 120) Data and control signals (downlink data transmission request messages, etc.) are transmitted via uplink 154.

The processor 110 may control the transceiver 100 to determine when to transmit a control signal (downlink data transmission request message, etc.).

Processor 110 may be a general purpose processor, special purpose processor, conventional processor, digital signal processor (DSP), microprocessor, one or more microprocessors associated with a DSP core, controller, microcontroller, application specific integrated circuit specific integrated circuits (ASICs), field programmable gate array (FPGA) circuits, integrated circuits (ICs), state machines, and the like. The processor 110 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the terminal to operate in a wireless environment. The processor 110 may be coupled to the transceiver 120.

Although FIG. 2 shows processor 110 and transceiver 120 as separate components, processor 110 and transceiver 120 may be integrated together in an electronic package or chip.

For example, in one embodiment, antenna 130 may be an antenna configured to transmit and / or receive RF signals. In another embodiment, antenna 130 may be, for example, a emitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, antenna 130 may be configured to transmit and receive both RF and optical signals. Antenna 130 may be configured to transmit and / or receive any combination of wireless signals. The transceiver 120 may be configured to modulate the signals to be transmitted by the antenna 130 and to demodulate the signals received by the antenna 130.

The base station can be one or more over an air interface that can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Communicate with the terminal.

The MTC communication system can be a multiple access system and can employ channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and the like. For example, a base station and an MTC terminal of a RAN may be configured such as a Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can set up an air interface using wideband CDMA (WCDMA). Radio technology can be implemented. WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA +). HSPA may include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed Uplink Packet Access (ULSPA). In another embodiment, the base station and the MTC terminals are Evolved UTRA (Evolved UTRA) that can configure the air interface using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A); Radio technology such as E-UTRA).

In other embodiments, the base station and the MTC terminal may include IEEE 802.16 (i.e., worldwide interoperability for microwave access (WiMAX), CDMA2000, CDMA2000 1X, CDMA 2000 Evolution-Data Optimized (EV-DO), interim standard 2000 (IS). -2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data Rate for GSM Evolution (Enhanced) Radio technologies such as Data rates for GSM Evolution (EDGE) and GSM / EDGE RAN (GERAN) can be implemented.

The base station of FIG. 2 may be, for example, a wireless router, HNB, HeNB, or AP and may utilize any suitable RAT that facilitates wireless access in a localized area, such as a place of business, home, vehicle, campus, etc. Can be. In one embodiment, the base station and MTC terminals may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base stations and terminals may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, the base station and MTC terminals may utilize a cellular-based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to configure the picocell or femtocell. The base station can directly access the Internet. Thus, the base station may not be required to access the Internet through the core network.

Multi-subframe scheduling method during frequency hopping

It is possible to add necessary information for using multi-subframe channel estimation. In order to enable multi-sub frame channel estimation, the power level or coding scheme of RS signals, which are a kind of pilot signal between successive multi-sub frames, should not be changed, and the cell-specific reference signal (CRS) may be a power level or Although the coding method cannot be changed, a reference signal (RS) signal transmitted by a terminal such as a UE-specific reference signal (URS) / demodulation reference signal (DMRS) is a power level or subframe per subframe in the existing LTE / LTE-A standard. Coding schemes may change. Therefore, when multi-subframe scheduling is performed, the power level or coding scheme of the UE spedicific RSs is not changed in the multi-subframe.

For LTE Rel 13 UE supporting enhanced coverage, multi-subframe scheduling may be supported when unicast PDSCH transmission is scheduled by EPDCCH (PDCCH for MTC communication).

In addition, for LTE Rel 13 Low complexity MTC UE supporting normal coverage, multi-subframe scheduling may be supported when unicast PDSCH transmission is scheduled by EPDCCH (PDCCH for MTC communication). .

Multi-subframe scheduling (Multi-subframe scheduling) or cross-subframe scheduling (Cross-subframe scheduling) is one of the PDSCH (or PUSCH) UE burst can be scheduled within the existing one subframe of, and for the UE burst The scheduling information is a scheduling method deviating from the method determined by one PDCCH / EPDCCH control information corresponding thereto, and a specific UE burst may be scheduled over several subframes by one PDCCH / EPDCCH control information. That is, one PDCCH / EPDCCH control information for a specific UE in a specific subframe in a conventional method in which scheduling information of a PDSCH burst for a corresponding UE in a corresponding subframe is determined as one PDCCH / EPDCCH control information for a specific UE in a specific subframe. As a result, a PDSCH burst for a specific UE may be allocated through several subframes.

13 and 14, if the PUSCH transmission according to an embodiment of the present invention a multi-is a conceptual diagram showing a sub-frame scheduling (Cross-subframe scheduling) by way of example - the sub-frame scheduling (Multi-subframe scheduling) or a cross.

As shown in Figures 13 and 14, multiple PUSCH transmissions (or multiple PDSCH transmissions) in a single downlink control information (DCI) format by using multi-sub frame scheduling or cross-sub frame scheduling. Can be scheduled to significantly reduce the downlink control overhead (control overhead)

In addition, it can be seen that the uplink data rate is increased by 2.33 times in the PUSCH transmission of FIG. 14 compared to the PUSCH transmission in FIG. 13. Such multi-sub frame scheduling or cross-sub frame scheduling can also be applied to downlink PDSCH transmission.

To be used for R12 MTC communicate; (Coverage Enhancement CE) purposes and, EPDCCH for coverage enhancement multi-subframe scheduling (Cross-subframe scheduling) is a coverage improvement sub-frame scheduling (Multi-subframe scheduling) or cross In the case of repetition transmission, since the decoding time of a large amount of control information is increased at the terminal side, a delay is caused in starting the related PDSCH, and when the EPDCCH repetitive transmission is used in the MTC terminal supporting the coverage enhancement, the multi-subframe is used. scheduling (Multi-subframe scheduling) or cross-scheduling the sub-frame (cross-subframe scheduling) is required.

Multi-subframe scheduling (Multi-subframe scheduling) or cross-case of the sub-frame scheduling (Cross-subframe scheduling) can significantly reduce the down-link control overhead (control overhead), which may increase the data rate, power consumption, The number of subframe swaging can be reduced.

Hereinafter, a multi-sub frame scheduling method in frequency hopping will be described.

1) In the network, common multi-subframe scheduling information is informed by using system information such as MIB or SIB broadcasted to all MTC terminals in the network repeatedly, and all MTC terminals in the network can be used in common.

In addition, it is possible to uniquely determine the multi-subframe scheduling information allocated to the MTC terminal itself by substituting a predetermined equation using a terminal ID such as RNTI, IMSI, or GUTI. That is, the system information and the terminal ID can be used together to determine the multi-subframe scheduling information allocated to each MTC terminal in the network.

2) By using the downlink control channel delivered to the user of a specific group, for example, PDCCH-informs the user of the multi-subframe scheduling information common to the user of the specific group, and can be used by the user terminal of the specific group in common .

In addition, by using a terminal ID such as RNTI, IMSI, TMSI, or GUTI, the multi-subframe scheduling information allocated to the MTC terminal itself may be uniquely determined. That is, the common downlink multi-subframe scheduling information transmitted to a specific group of users and the terminal ID may be used together to determine the multi-subframe scheduling information allocated to each MTC terminal in the network.

3) By using a downlink control channel delivered to a specific user, for example, UE-specific EPDCCH, the multi-subframe scheduling information can be informed to a specific user, and the specific user terminal can be used.

4) In addition to the step of determining the multi-subframe scheduling information by the above three methods, by using the system frame number (SFN), subframe index (slot), slot index (slot index) additionally subframe scheduling can be determined.

Specifically, SFN (System Frame Number) transmitted from the base station to the system information such as MIB and SIB1 and the ID value of the MTC terminal itself by substituting the formula for determining the predetermined multi-subframe scheduling information independently for each MTC terminal in the network. You can choose to assign multi-subframe scheduling to itself. In the same way, independent scheduling for each MTC terminal can be made by adjusting each subfrane / slot multi-subframe scheduling information by additionally utilizing subframe index and slot index as well as SFN and terminal ID. Allow information to be determined. In this way, only the information common to all users or a specific group is transmitted to the actual communication, and the remaining steps can be determined without any waste of frequency resources by transmitting separate signaling, that is, without waste of frequency resources, thereby allowing the MTC terminal to determine itself. Minimize resource waste to maximize system efficiency.

Second, only the scheduling information can be sent to the MTC terminal by operating the frequency hopping period and the multi-subframe scheduling.

Third, the start point and end point of the subframe using the same scheduling as control information (for example, PDCCH) can be informed by using semi-static scheduling.

Fourth, two or more of a repetition period, a multi-subframe scheduling period, and a frequency hopping pattern period can be operated to coincide.

Fifth, two patterns and periods different from one of three patterns and periods than the frequency hopping pattern and period, repetition period and frequency, and multi-subframe scheduling information are separately transmitted through PBCH, PDCCCH, EPDCCH, etc. By establishing and using a predetermined relationship between the two, it is possible to maximize the system efficiency by reducing the control information to be transmitted. The simplest form is a method used to coincide with the fourth method.

The above methods can reduce the size of control information to be transmitted in common. If there is information that can be shared between different patterns, the overhead can be reduced compared to sending separately. In particular, in the case of the third method, persistent scheduling is a method currently used for LTE VoIP, and since voice has a real time characteristic, data must be constantly transmitted every subframe. To do this, it is complicated to load scheduling information in each subframe every time in PDCCH / EPDCCH. Therefore, if scheduling is performed only once in PDCCH / EPDCCH, the same scheduling information continues from the next subframe. As a technique of reusing this, in case of MTC terminal, it is not voice but data, but the amount of data is small, so only the duration for performing persistent scheduling is determined and informed.

Repetitive transmission information, scheduling information, frequency hopping information sharing between uplink and downlink of MTC terminal

In case of an MTC UE for coverage improvement, the repetition level, scheduling information, and frequency hopping pattern for repetitive transmission are DL / DL (UL). ) Can share with each other.

Here, repetitive transmission may include a case of repetitive transmission of MIB, SIB, PDCCH, (E) PDCCH, PUSCH, PUCCH, PBCH, PRACH preamble, paging, or random access response (RAR).

The repetition level means the number of repetitions and the like during repetitive transmission.

In addition, in case of an MTC terminal for coverage improvement, information about a repetition period, a repetition number, a repetition pattern, and information on whether to use bundling during repetitive transmission may be shared in downlink / uplink. Here, bundling is a technique for repetition or gathering and transmitting SIB, PDCCH, (E) PDCCH, PUSCH, PUCCH, PBCH, and PRACH.

In addition, in case of an MTC terminal for coverage improvement, resource location information on whether to use persistent scheduling and persistent scheduling may be shared in downlink / uplink.

In addition, in case of MTC terminal for coverage improvement, whether to use multi-subframe scheduling, whether to use multi-subframe scheduling, the period of multi-subframe scheduling, and the number of multi-subframes are also shared in downlink / uplink You may.

In addition, in case of an MTC terminal for coverage improvement, frequency hopping period and narrowband usage information during frequency hopping may also be shared in downlink / uplink. For example, the narrowband usage information may include an available narrowband set and narrowband size information. The narrow band may have a size smaller than 6 PRBs, eg, 5 PRBs, 4 PRBs, 3 PRBs, and may be larger than 6 PRBs, eg, 7 PRBs, 8 PRBs, 9 PRBs. It may have a PRB or 12 PRBs that are twice the size and 18 PRBs that are three times the size. Narrow band size may be fixedly used in one of a plurality of sizes selectively, or may be adaptively used depending on the situation. For example, if the narrowband size is made smaller, the number of narrowbands increases, so that a plurality of MTC terminals may be supported or more hoppable bands may be provided in frequency hopping. Increasing the narrow band size can increase the transmission data rate.

The method of sharing in downlink (DL) / uplink (UL) includes a repetition level, scheduling information, and frequency hopping pattern of downlink based on downlink in uplink. Can be used as is. Or uplink information (repletion level) by inputting downlink information (repletion level, scheduling information, frequency hopping pattern, etc.) according to a predetermined rule in uplink. ), Scheduling information, frequency hopping pattern, and the like.

Alternatively, the repetition level, scheduling information, and frequency hopping pattern of the uplink may be used as it is based on the uplink in the downlink. Alternatively, the downlink information (repletion level) is input by inputting uplink information (repletion level, scheduling information, frequency hopping pattern, etc.) according to a predetermined rule in downlink. ), Scheduling information, frequency hopping pattern, and the like.

In the case of random access response (RAR) transmission, the MTC terminal can know the repetition level of the random access response (RAR) transmission from the repetition level of the most recent PRACH.

In case of a Random Access Response (RAR) transmission, the MTC terminal can know from which subframe the RAR transmission starts from the most recent PRACH resource set.

For Random Access Response (RAR) transmission, the MTC terminal can know from which frequency resource (s) the RAR transmission occurs from the most recent PRACH resource set.

17 illustrates an example of a data transmission method for a low data rate based IoT sensor application according to another embodiment of the present invention. FIG. 17 shows an example of a data transmission method when applied to an IoT sensor by dividing 1RB into 12 again within a 200KHz (eg, 1 RB) data rate of a GSM system. Since the data transmission method of FIG. 17 uses a low data rate of about 1/6 of the MTC data rate, the data transmission method may be mainly applied to a low speed IoT sensor rather than an image data transmission purpose.

Referring to FIG. 17, in the data transmission method for a low-speed data rate based IoT sensor application according to another embodiment of the present invention, a pilot and data are transmitted from a transmitter as shown in FIG. 17. Alternately arrange and transmit, and after the last data 1102-N, the pilot 1101-N can be added and transmitted. Here, the pilot 1101-N may be generated by copying a pilot 1101-0. When the receiver decodes data 1002-1 and decodes data using both pilot 1000-0 and pilot 1001-1 to decode data 1002-1 using only pilot 1001-0 (or pilot 1001-1). Compared with the restoration, the performance can be improved. In addition, the receiver decodes the data 1002-2 by using both the pilot 1000-1 and the pilot 1001-2 to decode the data using only the pilot 1001-1 (or the pilot 1001-2). Compared with this, the performance can be improved. In addition, when the receiver decodes data 1002-N, only the pilot 1001- (N-1) (or pilot 1001-N) is decoded by decoding the data using both pilot 1000- (N-1) and pilot 1001-N. The performance can be improved as compared with the case of decoding data. If a preamble (RS) or reference signal (RS) exists before the 1101-0 pilot, the 1101-0 pilot may be omitted.

In the case of the PRACH preamble, it is possible to transmit using a smaller bandwidth than the subcarrier space. Reducing the bandwidth has the effect of increasing the SNR. When the bandwidth is reduced, the data rate is reduced, but since the data is not transmitted since it is a preamble, there is no side effect due to the reduction of the data rate.

In the MTC, instead of using the PUCCH, when the PUSCH is scheduled, the UCI information that the PUCCH needs to send may be transmitted as the PUSCH instead of the PUCCH. Alternatively, in the MTC, instead of using the PUCCH, the UCI information transmitted by the PUCCH may be transmitted through the PRACH preamble. Alternatively, the MTC may operate without transmitting some of the UCI information that the PUCCH should send instead of using the PUCCH.

If MTC communication has to operate in a bandwidth smaller than 6PRB, 6 PRB data can be divided and transmitted over several TTI. For example, if only 3PRB can be operated within the bandwidth to be operated, 6PRB signals may be divided and transmitted twice. When using 1 PRB (180kHz, about 200kHz), it can be divided into 6 times.

Existing LTE uses TDD / FDD type of Full Deuplex. In other words, the existing LTE can be transmitted and received at the same time, but in this case, since both the transceiver is operating, the power consumption is increased and the complexity is increased. If the data rate does not need to be fast like MTC, the half duplex scheme can be applied to reduce power consumption and complexity by only one transmission or reception at a time.

According to an embodiment of the present invention, a method for performing random access between a MTC terminal and a base station is provided.

1) performing synchronization with the MTC terminal at the base station;

2) transmitting system information from the base station to the MTC terminal.

The random access may use a Physical Random Access Channel (PRACH) signal to distinguish a coverage extension MTC terminal from a general MTC terminal. In order to distinguish the coverage extension MTC terminal and the general MTC terminal, it may be classified with a PRACH preamble.

The method of performing the random access may include performing a random access procedure by using the received system information in the terminal.

1) performing synchronization with the base station in the MTC terminal;

2) receiving system information from the base station at the MTC terminal.

The MTC terminal may transmit a random access preamble to the base station. The base station may receive a random access preamble and transmit a random access response (RAR) message to the MTC.

The MTC terminal may transmit an RRC connection request message in response to the random access response message. The RRC connection request message may include a terminal ID. The base station may recognize or identify the MTC terminal based on the terminal ID and prepare for resource allocation.

The base station may transmit an RRC connection setup message to the MTC terminal.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims

In the downlink thing communication method from the base station to the thing communication terminal,

Transmitting, by the base station, at least one of system information, control information, and data except for a master information block (MIB) using a system bandwidth of a predetermined size to the MTC terminal,

The base station performs frequency hopping using at least one of system information, control information and data except for the master information block (MIB) using a frequency hopping pattern between narrow bands smaller than the system bandwidth. The thing communication method, characterized in that for transmitting to the thing communication terminal.
The method of claim 1, wherein the frequency hopping pattern is generated using at least one of a cell identifier (ID), a terminal identifier (ID), a system frame number (SFN), and a subframe index. And determining the thing.
The method of claim 1, wherein the frequency hopping pattern is transmitted to the MTC terminal using persistent scheduling.
The method of claim 1, wherein the primary synchronization signal (PSS) / secondary synchronization signal (PSS) used for synchronization and the PBCH indicating system information do not perform the frequency hopping.
2. The method of claim 1 wherein the frequency hopping is performed only within a specific narrowband set.
The method of claim 5, wherein in the case of the TDD transmission scheme, the specific narrowband set is identically configured for uplink transmission and downlink transmission.
The apparatus of claim 1, wherein the BS communicates an available narrowband set using system information including at least one of a MIB and an SIB that are broadcast to a MTC terminal in a network. Inform the terminal or encode the MIB and / or SIB encoding into a code indicating a specific number to inform the MTC of the usage information about the available narrowband set. Thing communication method.
In the uplink thing communication method from the MTC terminal to the base station,

Transmitting at least one of control information, a random access signal, and data to the base station using a system bandwidth of a predetermined size in the MTC terminal,

At least one of the control information, the random access signal and the data is transmitted to the base station by performing frequency hopping using a hopping pattern between narrow bands smaller than the system bandwidth to the base station Way.
In the downlink thing communication method from the base station for coverage expansion to the MTC terminal,

System information using a system bandwidth of a predetermined size, the system information including at least one of a master information block (MIB) and a system information block (SIB); transmitting at least one of control information and data to the MTC terminal Including the steps of:

And transmitting at least one of the system information, control information, and data to the MTC terminal repeatedly.
10. The method of claim 9, wherein the repetitive transmission is transmitted to the MTC terminal using persistent scheduling, and the constant scheduling transmits by periodically fixing the repetitive transmission pattern. The communication method of things.
10. The method of claim 9, wherein the repetitive transmission of the MIB (Master Information Block) is transmitted using one of a method of transmitting the same signal and a method of transmitting the same data but different types of signals. The communication method of things.
The method of claim 11, wherein the transmitting of the same data but having a different signal type transmits the same data but codes differently.
10. The method of claim 9, wherein the MTC terminal is divided into a small coverage terminal and a large coverage terminal according to a channel condition.