WO2017213274A1 - Method for terminal communication in mmwave communication system and terminal - Google Patents

Abstract

Disclosed is a terminal for performing an mmWave communication method, comprising the steps of: receiving, from a base station, information notifying two search spaces have been configured to detect a control channel in one mmWave TTI, and receiving an indicator indicating the position of a first search space and a second space for detecting the control channel within the mmWave TTI; performing blind decoding for each of the first search space and the second search space indicated by the indicator; detecting a downlink control channel from the first search space and/or the second search space; and decoding downlink data indicated by the downlink control channel.

Description

Method and terminal of terminal in MMWAVE communication system

The following description relates to a wireless communication system, and more particularly, to a communication method and a terminal of a terminal in an mmWave communication system.

As an example of a wireless communication system to which the present invention may be applied, a 3GPP LTE (3rd Generation Partnership Project Long Term Evolution (LTE)) communication system will be described in brief.

1 is a diagram schematically illustrating an E-UMTS network structure as an example of a wireless communication system. The Evolved Universal Mobile Telecommunications System (E-UMTS) system is an evolution from the existing Universal Mobile Telecommunications System (UMTS), and is being standardized in 3GPP. In general, the E-UMTS is called a Long Term Evolution (LTE) system or an LTE-Advanced (LTE-A) system. For details of technical specifications of UMTS and E-UMTS, refer to Release 7 to Release 13 of "3rd Generation Partnership Project; Technical Specification Group Radio Access Network", respectively.

Referring to FIG. 1, an E-UMTS is located at an end of a user equipment (UE) and a base station (eNode B, eNB, network (E-UTRAN)) and connects an access gateway (AG) connected to an external network. The base station may transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service.

One or more cells exist in one base station. The cell is set to one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz to provide a downlink or uplink transmission service to the terminal. Different cells may be configured to provide different bandwidths. The base station controls data transmission and reception for a plurality of terminals. For downlink (DL) data, the base station transmits downlink scheduling information to inform the corresponding UE of time / frequency domain, encoding, data size, and HARQ (Hybrid Automatic Repeat and reQuest) related information. In addition, the base station transmits uplink scheduling information to the terminal for uplink (UL) data, and informs the time / frequency domain, encoding, data size, HARQ related information, etc. that the terminal can use. An interface for transmitting user traffic or control traffic may be used between base stations. The core network (Core Network, CN) may be composed of a network node for the user registration of the AG and the terminal. The AG manages the mobility of the UE in units of a tracking area (TA) composed of a plurality of cells.

Wireless communication technology has been developed up to LTE-A based on WCDMA, but the needs and expectations of users and operators are continuously increasing. In addition, as other radio access technologies continue to be developed, new technological evolution is required to be competitive in the future. Reduced cost per bit, increased service availability, the use of flexible frequency bands, simple structure and open interface, and adequate power consumption of the terminal are required.

An object of the present invention is to propose a stable communication mechanism between a terminal and a base station in an mmWave communication system using an ultra-high frequency band.

Another object of the present invention is to mmWave base station to stably transmit a downlink control channel to the terminal.

Still another object of the present invention is to implement various methods for ensuring stable reception of a downlink control channel.

Technical objects to be achieved in the present invention are not limited to the above-mentioned matters, and other technical problems not mentioned above are provided to those skilled in the art from the embodiments of the present invention to be described below. May be considered.

In order to solve the above technical problem, the communication method may include receiving information indicating that two search spaces for detecting a control channel are set in one mmWave TTI, and a first search space for detecting the control channel. ) And receiving, from the mmWave base station, an indicator indicating a location within the mmWave TTI of the second search space, performing blind decoding for the first search space and the second search space indicated by the indicator, respectively; Detecting a downlink control channel from at least one of the search space and the second search space, and decoding the downlink data indicated by the downlink control channel.

The indicator may be received every TTI.

The indicator may be received only in the TTI where the settings of the first search space and the second search space are changed by the mmWave base station.

The blind decoding may be performed semi-persistent according to the recently received indicator until a new indicator is received.

The first search space is arranged in n OFDM symbols from the first Orthogonal Frequency Division Multiplexing (OFDM) symbol of the TTI, and the second search space is arranged in m OFDM symbols from the last OFDM symbol of the TTI, where n and m are natural numbers. Can be.

When the indicator indicates the number of search spaces including the first search space and the second search space, the blind decoding may be performed at a predetermined position with respect to the number of search spaces.

The terminal for solving the technical problem includes a transmitter, a receiver, and a processor connected to the transmitter and the receiver to operate, wherein the processor informs that two search spaces for detecting a control channel in one mmWave TTI are set. Control the receiving unit to receive information, control the receiving unit to receive from the mmWave base station an indicator indicating a position within the mmWave TTI of the first search space and the second search space for detecting the control channel, and indicated by the indicator Performing blind decoding on the first search space and the second search space, respectively, detecting a downlink control channel from at least one of the first search space and the second search space, and downlink data indicated by the downlink control channel Decode

According to embodiments of the present invention, the following effects can be expected.

First, even though a sudden channel change occurs in the mmWave communication system, efficient communication between the terminal and the base station is possible.

Secondly, the terminal supporting the mmWave communication system can stably receive the downlink control channel from the mmWave base station.

Third, it is possible to operate adaptively to various channel changes through various methods for stably receiving the control channel, thereby ensuring the reception of the control channel of the terminal.

Effects obtained in the embodiments of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are commonly known in the art to which the present invention pertains from the description of the embodiments of the present invention. Can be clearly derived and understood by those who have In other words, unintended effects of practicing the present invention may also be derived by those skilled in the art from the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are provided to help understand the present disclosure, and provide embodiments of the present disclosure with the detailed description. However, the technical features of the present invention are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute a new embodiment. Reference numerals in each drawing refer to structural elements.

1 schematically illustrates an E-UMTS network structure as an example of a wireless communication system.

FIG. 2 illustrates a structure of a control plane and a user plane of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard.

3 illustrates physical channels used in a 3GPP system and a general signal transmission method using the same.

4 illustrates a structure of a radio frame used in an LTE / LTE-A system.

5 illustrates a resource grid for a downlink slot.

6 illustrates a structure of a downlink subframe.

7 is a diagram illustrating an EPDCCH and a PDSCH scheduled by an EPDCCH.

8 is a diagram illustrating the influence of communication connection by obstacles in the mmWave communication system.

9 illustrates an example of a change in received power caused by a moving obstacle and a configuration of a transmission time interval (TTI) according to it.

10 illustrates a frame structure according to the first example of the resource structure in the mmWave system.

11 shows a resource grid according to the first example of the resource structure in the mmWave system.

12 illustrates a Stop And Wait (SAW) Hybrid Automatic Repeat reQuest (HAQ) procedure according to a first example and a second example of a resource structure in an mmWave system.

13 illustrates a SAW HARQ procedure according to a third example of a resource structure in an mmWave system.

14 is a diagram illustrating a process in which data decoding fails due to a decoding failure of a terminal of a control channel.

15 illustrates a control channel transmission method according to an embodiment of the present invention.

16 is a diagram illustrating a control channel transmission method according to another exemplary embodiment.

17 is a diagram illustrating a control channel transmission method according to another exemplary embodiment.

18 is a diagram illustrating a control channel transmission method according to another exemplary embodiment.

19 is a flowchart illustrating a process of performing a control channel transmission method according to an exemplary embodiment.

FIG. 20 is a diagram illustrating a process of determining, by the base station, transmission power of a control channel with reference to FIG. 19.

21 is a diagram illustrating a configuration of a terminal and a base station related to the proposed embodiment.

The terms used in the present invention have been selected as widely used general terms as possible in consideration of the functions in the present invention, but this may vary according to the intention or precedent of the person skilled in the art, the emergence of new technologies and the like. In addition, in certain cases, there is also a term arbitrarily selected by the applicant, in which case the meaning will be described in detail in the description of the invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some of the components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps which may obscure the gist of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Throughout the specification, when a part is said to "comprising" (or including) a component, this means that it may further include other components, except to exclude other components unless specifically stated otherwise. do. In addition, the terms "... unit", "... group", "module", etc. described in the specification mean a unit for processing at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as. Also, "a or an", "one", "the", and the like are used differently in the context of describing the present invention (particularly in the context of the following claims). Unless otherwise indicated or clearly contradicted by context, it may be used in the sense including both the singular and the plural.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802.xx system, 3GPP system, 3GPP LTE system and 3GPP2 system. That is, obvious steps or parts which are not described among the embodiments of the present invention may be described with reference to the above documents.

In addition, all terms disclosed in the present document can be described by the above standard document. In particular, embodiments of the present invention may be supported by one or more of the standard documents P802.16e-2004, P802.16e-2005, P802.16.1, P802.16p, and P802.16.1b standard documents of the IEEE 802.16 system. have.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

In addition, specific terms used in the embodiments of the present invention are provided to help the understanding of the present invention, and the use of the specific terms may be changed to other forms without departing from the technical spirit of the present invention.

LTE / LTE-A System General

FIG. 2 is a diagram illustrating a control plane and a user plane structure of a radio interface protocol between a terminal and an E-UTRAN based on the 3GPP radio access network standard. The control plane refers to a path through which control messages used by a user equipment (UE) and a network to manage a call are transmitted. The user plane refers to a path through which data generated at an application layer, for example, voice data or Internet packet data, is transmitted.

The physical layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper layer of the medium access control layer through a trans-antenna port channel. Data moves between the medium access control layer and the physical layer through the transport channel. Data moves between the physical layer at the transmitting side and the physical layer at the receiving side. The physical channel utilizes time and frequency as radio resources. Specifically, the physical channel is modulated in the Orthogonal Frequency Division Multiple Access (OFDMA) scheme in the downlink, and modulated in the Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme in the uplink.

The medium access control (MAC) layer of the second layer provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a functional block inside the MAC. The PDCP (Packet Data Convergence Protocol) layer of the second layer provides unnecessary control for efficiently transmitting IP packets such as IPv4 or IPv6 over a narrow bandwidth air interface. It performs header compression function that reduces information.

The Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only in the control plane. The RRC layer is responsible for controlling logical channels, transport channels, and physical channels in association with configuration, reconfiguration, and release of radio bearers (RBs). RB means a service provided by the second layer for data transmission between the terminal and the network. To this end, the RRC layers of the UE and the network exchange RRC messages with each other. If there is an RRC connected (RRC Connected) between the UE and the RRC layer of the network, the UE is in an RRC connected mode, otherwise it is in an RRC idle mode. The non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management.

One cell constituting an eNB is set to one of bandwidths such as 1.4, 3, 5, 10, 15, and 20 MHz to provide downlink or uplink transmission services to multiple terminals. Different cells may be configured to provide different bandwidths.

The downlink transport channel for transmitting data from the network to the UE includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a downlink shared channel (SCH) for transmitting user traffic or a control message. have. Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal to the network includes a random access channel (RAC) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or a control message. It is located above the transport channel, and the logical channel mapped to the transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and an MTCH (multicast). Traffic Channel).

FIG. 3 is a diagram for explaining physical channels used in a 3GPP LTE / LTE-A system and a general signal transmission method using the same.

The user equipment that is powered on again or enters a new cell while the power is turned off performs an initial cell search operation such as synchronizing with the base station in step S301. To this end, the user equipment receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the base station, synchronizes with the base station, and obtains information such as a cell ID. Thereafter, the user equipment may receive a physical broadcast channel from the base station to obtain broadcast information in a cell. Meanwhile, the user equipment may receive a downlink reference signal (DL RS) in the initial cell search step to check the downlink channel state.

After the initial cell search, the user equipment receives the physical downlink control channel (PDCCH) and the physical downlink control channel (PDSCH) according to the physical downlink control channel information in step S302. Specific system information can be obtained.

Thereafter, the user equipment may perform a random access procedure such as step S303 to step S306 to complete the access to the base station. To this end, the user equipment transmits a preamble through a physical random access channel (PRACH) (S303), and responds to the preamble through a physical downlink control channel and a corresponding physical downlink shared channel. The message may be received (S304). In case of contention-based random access, contention resolution procedures such as transmission of an additional physical random access channel (S305) and reception of a physical downlink control channel and a corresponding physical downlink shared channel (S306) may be performed. .

The user equipment which has performed the above-described procedure is then subjected to a physical downlink control channel / physical downlink shared channel (S307) and a physical uplink shared channel (PUSCH) as a general uplink / downlink signal transmission procedure. Physical Uplink Control Channel (PUCCH) transmission (S308) may be performed. The control information transmitted from the user equipment to the base station is collectively referred to as uplink control information (UCI). UCI includes Hybrid Automatic Repeat and reQuest Acknowledgment / Negative-ACK (HARQ ACK / NACK), Scheduling Request (SR), Channel State Information (CSI), and the like. In the present specification, HARQ ACK / NACK is simply referred to as HARQ-ACK or ACK / NACK (A / N). HARQ-ACK includes at least one of positive ACK (simply ACK), negative ACK (NACK), DTX, and NACK / DTX. The CSI includes a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indication (RI), and the like. UCI is generally transmitted through PUCCH, but may be transmitted through PUSCH when control information and traffic data should be transmitted at the same time. In addition, the UCI may be aperiodically transmitted through the PUSCH by the request / instruction of the network.

4 is a diagram illustrating a structure of a radio frame used in an LTE / LTE-A system.

Referring to FIG. 4, in a cellular OFDM wireless packet communication system, uplink / downlink data packet transmission is performed in subframe units, and one subframe is defined as a predetermined time interval including a plurality of OFDM symbols. . The 3GPP LTE / LTE-A standard supports a type 1 radio frame structure applicable to frequency division duplex (FDD) and a type 2 radio frame structure applicable to time division duplex (TDD).

4A illustrates the structure of a type 1 radio frame. The downlink radio frame consists of 10 subframes, and one subframe consists of two slots in the time domain. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. One slot includes a plurality of OFDM symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. In the 3GPP LTE system, since OFDMA is used in downlink, an OFDM symbol represents one symbol period. An OFDM symbol may also be referred to as an SC-FDMA symbol or symbol period. A resource block (RB) as a resource allocation unit may include a plurality of consecutive subcarriers in one slot.

The number of OFDM symbols included in one slot may vary depending on the configuration of a cyclic prefix (CP). CPs include extended CPs and normal CPs. For example, when an OFDM symbol is configured by a standard CP, the number of OFDM symbols included in one slot may be seven. When the OFDM symbol is configured by the extended CP, since the length of one OFDM symbol is increased, the number of OFDM symbols included in one slot is smaller than that of the standard CP. In the case of an extended CP, for example, the number of OFDM symbols included in one slot may be six. If the channel state is unstable, such as when the user equipment moves at a high speed, an extended CP may be used to further reduce intersymbol interference.

When a standard CP is used, since one slot includes 7 OFDM symbols, one subframe includes 14 OFDM symbols. In this case, the first up to three OFDM symbols of each subframe may be allocated to a physical downlink control channel (PDCCH), and the remaining OFDM symbols may be allocated to a physical downlink shared channel (PDSCH).

4B illustrates a structure of a type 2 radio frame. Type 2 radio frames consist of two half frames, each half frame comprising four general subframes including two slots, a downlink pilot time slot (DwPTS), a guard period (GP) and It consists of a special subframe including an Uplink Pilot Time Slot (UpPTS).

In the special subframe, DwPTS is used for initial cell search, synchronization or channel estimation at the user equipment. UpPTS is used for channel estimation at base station and synchronization of uplink transmission of user equipment. That is, DwPTS is used for downlink transmission and UpPTS is used for uplink transmission. In particular, UpPTS is used for PRACH preamble or SRS transmission. In addition, the guard period is a period for removing interference caused in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

Regarding the special subframe, the current 3GPP standard document defines a configuration as shown in Table 1 below. In Table 1

In the case of DwPTS and UpPTS, the remaining area is set as a protection interval.

Table 1

On the other hand, the structure of the type 2 radio frame, that is, UL / DL configuration (UL / DL configuration) in the TDD system is shown in Table 2 below.

TABLE 2

In Table 2, D denotes a downlink subframe, U denotes an uplink subframe, and S denotes the special subframe. Table 2 also shows the downlink-uplink switching period in the uplink / downlink subframe configuration in each system.

The structure of the radio frame described above is merely an example, and the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of symbols included in the slot may be variously changed.

5 illustrates a resource grid for a downlink slot.

5, the downlink slot is in the time domain

Contains OFDM symbols and in the frequency domain

Contains resource blocks. Each resource block

Downlink slots in the frequency domain because they include subcarriers

Includes subcarriers 5 illustrates that the downlink slot includes 7 OFDM symbols and the resource block includes 12 subcarriers, but is not necessarily limited thereto. For example, the number of OFDM symbols included in the downlink slot may be modified according to the length of a cyclic prefix (CP).

Each element on the resource grid is called a Resource Element (RE), and one resource element is indicated by one OFDM symbol index and one subcarrier index. One RB

It consists of resource elements. The number of resource blocks included in the downlink slot (

) Depends on the downlink transmission bandwidth set in the cell.

6 illustrates a structure of a downlink subframe.

Referring to FIG. 6, up to three (4) OFDM symbols located at the front of the first slot of a subframe correspond to a control region to which a control channel is allocated. The remaining OFDM symbols correspond to data regions to which the Physical Downlink Shared Channel (PDSCH) is allocated. Examples of a downlink control channel used in LTE include a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), a Physical Hybrid ARQ Indicator Channel (PHICH), and the like. The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols used for transmission of a control channel within the subframe. The PHICH carries a HARQ ACK / NACK (Hybrid Automatic Repeat request acknowledgment / negative-acknowledgment) signal in response to uplink transmission.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). The DCI includes resource allocation information and other control information for the user device or user device group. For example, the DCI includes uplink / downlink scheduling information, uplink transmission (Tx) power control command, and the like.

The PDCCH includes a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), a paging channel, Resource allocation information of upper-layer control messages such as paging information on PCH), system information on DL-SCH, random access response transmitted on PDSCH, Tx power control command set for individual user devices in a group of user devices, Tx power It carries control commands and activation instruction information of Voice over IP (VoIP). A plurality of PDCCHs may be transmitted in the control region. The user equipment may monitor the plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or a plurality of consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of PDCCH bits are determined according to the number of CCEs. The base station determines the PDCCH format according to the DCI to be transmitted to the user equipment, and adds a cyclic redundancy check (CRC) to the control information. The CRC is masked with an identifier (eg, a radio network temporary identifier (RNTI)) according to the owner or purpose of use of the PDCCH. For example, when the PDCCH is for a specific user equipment, an identifier (eg, cell-RNTI (C-RNTI)) of the corresponding user equipment may be masked to the CRC. If the PDCCH is for a paging message, a paging identifier (eg, paging-RNTI (P-RNTI)) may be masked to the CRC. When the PDCCH is for system information (more specifically, a system information block (SIC)), a system information RNTI (SI-RNTI) may be masked to the CRC. If the PDCCH is for a random access response, a random access-RNTI (RA-RNTI) may be masked to the CRC.

7 is a diagram illustrating an EPDCCH and a PDSCH scheduled by an EPDCCH.

Referring to FIG. 7, an EPDCCH may generally define and use a portion of a PDSCH region for transmitting data, and the UE should perform a blind decoding process for detecting the presence or absence of its own EPDCCH. The EPDCCH performs the same scheduling operation as the legacy legacy PDCCH (ie PDSCH and PUSCH control), but when the number of UEs connected to the same node as the RRH increases, a larger number of EPDCCHs are allocated in the PDSCH region and thus should be performed by the UE. There may be a disadvantage that the complexity may be increased by increasing the number of blind decoding to be performed.

2. mmWave communication system

8 is a diagram illustrating the influence of communication connection by obstacles in the mmWave communication system.

8 (a) shows the conditions for measuring the influence of the communication connection by the obstacle in the mmWave communication system. 8 (b) and 8 (c) are diagrams visualizing and showing the influence of the communication connection measured according to the conditions of FIG. 8 (a), respectively.

In an environment where the UE density is 730 UE / km ² , 2640 MHz bandwidth is maintained for 1000 TTI, and 336 subcarriers per 512 subcarriers are used for data transmission, the influence of obstacles is measured according to the condition of FIG. 8 (a). Consider. 8B is a graph showing the density of obstacles along a path when a person is an obstacle. 8 (c) shows the network throughput as the communication connection is blocked. From (b) and (c) it can be seen that the mmWave communication connection is greatly affected by the density of obstacles located on the communication path.

In addition, when considering the speed of about 14.4 km / h when running and about 4.8 km / h when walking, the difference in power loss between Line of Sight and NLoS is about 15 dB within 5 meters. Based on this, the difference in power loss between LoS and NLoS is about 45dB at a distance of 100m.

When the LoS / NLoS transition time of a person walking at 0.6m / s is about 150ms, the transition time change of an object moving at 10m / s is about 9ms, and in special situations such as a sudden movement of a hand holding a UE or a moving obstacle, It may appear short. These results are shown in Table 3 below.

TABLE 3

	Walking (0.6m / s)	Sprinting (10m / s)	Swift Hand swing (43m / s)
LoS / NLoS Transition	150 ms	9 ms	2.093 ms

From Table 3, it can be seen that the probability of blocking the LoS / NLoS transition and the communication connection to the moving obstacle depends on the movement characteristics of the obstacle and the surrounding environment.

9 illustrates an example of a change in received power caused by a moving obstacle and a configuration of a transmission time interval (TTI) according to it.

The TTI of the mmWave system using the ultra-high frequency band is designed according to the system requirements, which is relatively shorter than the legacy system. This is because the mmWave system has a large performance impact due to LoS / NLoS transition. Accordingly, although a closed-loop system may be configured to increase the transmit power to withstand the LoS / NLoS transition state through feedback, the performance of the mmWave control channel transmitted in the LoS / NLoS transition period may be degraded. Problems may also arise.

10 to 13, various examples of the mmWave TTI will be described. First, Table 4 below shows the requirements for the design of a frame (or TTI) in the mmWave system, and Table 4 below is an example of an implementation of the mmWave system.

Table 4

parameter	value
Coverage	: ≤ 1km
Operation bandwidth
	10 GHz to 60 GHz
Max. Doppler's frequency	250km / h @ 30GHz, 125km / h @ 60GHz
Max. channel delay	0.5us
CP overhead	: ≤7%
Channel Bandwidth	: under 500MHz (Reference)
Peak data rate	X	10 Gbps

Three ways to design TTI in mmWave system according to Table 4 are described, the first example is to limit the memory size, the second example is to limit the processing time of the UE (with the HARQ process maintained) And a third example is how to limit the processing time of the UE (increasing HARQ process).

Frame related parameters according to these three schemes are shown in Table 5 below.

Table 5

Parameter	LTE (Normal CP)	1st proposal	2nd proposal	3rd proposal
Subcarrier-spacing	15 kHz	104.25 kHz
OFDM symbol period	66.67us	9.59us
Guard Interval / Cyclic Prefix	4.7us	0.5us
OFDM symbol duration	71.14us	10.09us
Efficiency in terms of energy	94.1%	95%
Occupied BW	90 MHz (5 CCs)	427.008 MHz
Guard-band	10 MHz (5 CCs)	47.445 MHz
Total System BW	100 MHz	474.453 MHz
No. of available subcarriers	6,000 (5 CCs)	4096
Number of OFDM symbol per TTI	14 symbols	22	76	22 (assume)
TTI duration	1 ms	222us	767us	222us
HARQ process number	8	8	8	24
UE processing time	2.3 ms	0.666 ms	2.3 ms	2.3 ms
Total soft buffer size	NSB = 35,982,720	NSB	NSB X 3.45	NSB X 3
Max. TB size	299,856	NTB ≤ 2,998,580	NTB X 3.45	NTB

10 shows a frame structure according to a first example of a resource structure in an mmWave system, FIG. 11 shows a resource grid according to a first example of a resource structure in an mmWave system, and FIG. 12 shows a resource structure in an mmWave system. A Stop And Wait (SAW) HARQ (Hybrid Automatic Repeat reQuest) procedure according to a first example and a second example is shown.

First, FIG. 10 illustrates a frame structure according to the first scheme described above, that is, a method of limiting a memory size (buffer size limitation).

It is assumed that a single codeword (CW) is assumed and the number of HARQ processes is maintained at the same number as that of the conventional LTE system. Meanwhile, in the first embodiment, the memory size (buffer size) is configured to be the same as the maximum buffer size of the conventional LTE as shown in Table 5. When the system coverage is 1 km or less and the round trip time (RTT) is 6.67 us, the processing time of the UE is determined as in Equation 1 below.

[Equation 1]

As shown in Table 5, the TTI is determined to be 222us, which is the last 22 OFDM symbols. A time base resource structure and a resource grid according to the first scheme are shown in FIGS. 10 and 11, respectively, and the HARQ process according to the first scheme is illustrated as in FIG. 12.

Table 6 below shows a code bit size based on the buffer size of LTE in the first proposal, and Table 7 shows parameters defining the TTI of the first proposal described above.

Table 6

Parameter	Value	Remarks
Max soft buffer	35,982,720	Described in the TS 36.306 standard.
Max HARQ process No.	8	Described in the TS 36.212 standard.
coded bit per a TB	4,497,840	in SCW case

TABLE 7

Parameter	Value	Remarks
RE per OFDM symbol	4,096	Full subcarrier
Layer
	8	Max 8 layer assumption
Modulation
	8	256 QAM support Assumptions
overhead (%)	25	Apply overhead when calculating LTE link budgetLTE Peak data rate: overhead of RE required for transmission on 8 layer 42 REs: 12RE (PDCCH), 6RE (CRS), 24 (DMRS) Overhead = 42/168 = 25%
No. of OFDM symbol per TTI	22 symbols	In SCW case
One TTI	222us

Furthermore, Table 8 below shows parameters related to a maximum transport block (TB) size according to the first proposal.

Table 8

Parameter	Value	Remarks
Max. TB size per (a TB per CC)	299,856	In MCW case of LTE-A (TS 36.213)
Max. coded bit per a TB	449,784	In MCW case of LTE-A (TS 36.213)
Supported coding rate range	≥ 0.67	In LTE, used as reference
Max. code bit size (Alt. 1-B)	4,497,840	In SCW case
Supported coding rate range	≥ 0.67	Same code-rate range definition as LTE
Max. TB size for Alt. 1-B	≤ 2,998,580	In SCW case

On the other hand, in the case of the second eye, unlike the first eye described above, the method of limiting the processing time of the UE. For example, the second proposal is to limit the processing time of the MAC or PHY layer of the UE.

Assuming a single CW, the number of HARQ processes remains 8, the same as the LTE system, and the assumption that the system coverage is less than 1km and the RTT is 6.67us is the same as the first proposal described above. On the other hand, the second proposal assumes that the processing time of the UE is 2.3ms.

In the second case, the TTI is determined as 767.6us, which is the last 76 OFDM symbols, and the HARQ process of the second eye is shown in FIG. 12. On the other hand, in the HARQ process of the second eye, there is a difference that one TTI is composed of 767.6 us, so that the final TB size is also increased by about 3.45 times compared to the first eye.

13 illustrates a SAW HARQ procedure according to a third example of a resource structure in an mmWave system.

Similar to the second scheme, the third scheme also limits the processing time of the UE. Unlike the second scheme, the third scheme increases the number of HARQ processes. Assuming a single CW, assuming that the system coverage is less than 1km, the RTT is 6.67 us, the processing time of the UE is 2.3ms and one TTI is 222us which is 22 OFDM symbols.

In this case, it can be seen from FIG. 13 that the OFDM symbol length itself of one TTI is the same as the third eye and the first eye, but in the third eye, the number of HARQ processes is increased to 24.

The link budget based on the mmWave frame structure described above may be shown in Table 9 below. As shown in Table 9, it is assumed that in the mmWave system, the service coverage is reduced to less than 1 km, while the wavelength is shortened due to the increase in the center frequency, so that it is easy to increase the signal to noise ratio (SNR) using a massive antenna. . Therefore, the mmWave system can provide higher SNR performance than the conventional LTE, and it is assumed that the maximum modulation scheme is increased from 64 quadrature amplitude modulation (QAM) to 256 QAM. Based on these assumptions, it is possible to meet the basic system requirements while achieving a high data rate of 10 Gbps.

Table 9

Parameters	LTE-A (5CC)	LTE-HF (△ f = 120kHz)	HF (△ f = 104.25 kHz)
Transmission Time Interval (ms)	1 ms	0.125 ms	0.22 ms
No. of OFDM symbol in a TTI	14	14	22
Transmission BW (Occupied BW)	100 MHz (90 MHz)	400 MHz (360 MHz)	474.4 MHz (427 MHz)
Overhead	20%	20%	20%
Maximum modulation order	6 (64QAM)	8 (256QAM)	8 (256QAM)
Maximum number of layer	8	8	8
Peak data rate	3.2 Gbps	17.2 Gbps	20.8 Gpbs
Parameters	LTE-A (5CC)	LTE-HF (△ f = 120kHz)	HF (△ f = 104.25 kHz)

3. Control channel transmission and reception method in mmWave system

14 is a diagram illustrating a process in which data decoding fails due to a decoding failure of a terminal of a control channel.

On the other hand, the effects of the body, obstacles, etc. on the connection in the mmWave system can be expressed as a stochastic value, but it is not known exactly when and how to degrade the communication connection. If the communication connection becomes unstable at the time of transmitting the control channel in mmWave communication and the reception performance is deteriorated, decoding failure of the control channel may occur. As shown in FIG. 14A, when a control channel is erroneously decoded, a corresponding data channel may be erroneously decoded.

On the contrary, even if an indicator for each of a plurality of data is included in one search space to secure transmission diversity for data, if the decoding of the control channel itself fails, the decoding of the corresponding data channel fails. The problem arises.

Therefore, the following describes a method for robustly and stably transmitting / receiving a control channel in the mmWave system. The first embodiment of FIGS. 15 to 17 and the second embodiment of FIGS. 18 to 20 will be described.

15 to 17 are diagrams illustrating a control channel transmission method according to an exemplary embodiment. According to a first embodiment, a search space in which a control channel is located in a mmWave TTI (or subframe) is configured differently from a conventional communication system.

The location of the search space according to the proposed embodiment may be configured as shown in FIGS. 15 (a), 15 (b) and 15 (c). The location of the search space according to the embodiment proposed in the mmWave system may be known to the UE by a separate channel indicating the location of the control channel, such as a physical control format indicator channel (PCFICH) in the LTE / LTE-A system.

The control channel proposed in the mmWave system may be arranged in the first n OFDM symbols and the last m OFDM symbols in the mmWave TTI (or subframe), as shown in FIG. 15 (b). May be the same or different). FIG. 15 (b) shows a resource structure in which a control channel of the mmWave system is arranged in the first three OFDM symbols and the last two OFDM symbols in the mmWave TTI.

Meanwhile, the position of the control channel and the position of the search space configured in a manner different from the conventional communication system may be indicated by the 'PCFICH' shown in FIG. 15 (a). In other words, when the position of 'control channel 1' and 'control channel 2' is indicated by 'PCFICH' in FIG. 15 (a), the UE decodes data of 'control channel 1' and 'control channel 2' separately. The channel can be decoded. Accordingly, the UE can obtain a decoding opportunity for 'control channel 2' in addition to the general 'control channel 1', so that the control channel can be stably decoded even in a bad communication environment. Meanwhile, the channel of mmWave TTI described above as 'PCFICH' is merely an example for convenience of description, and a separate channel may be defined to indicate the position of a control channel defined in the mmWave system.

FIG. 15C illustrates an example of setting a control format indicator (CFI) indicating a position of a control channel defined in the mmWave system. As shown in FIG. 15 (c), the CFI values '1', '2', and '3' representing the first three OFDM symbols of FIG. 15 (b) to indicate the position of the control channel within the mmWave TTI. In addition, it additionally includes '4' and '5' values representing the last two OFDM symbols. The UE can recognize that the control channel is located in the last two OFDM symbols in the mmWave TTI by recognizing the codewords for the values '4' and '5' included in the CFI. Accordingly, the UE may additionally detect 'control channel 2' by performing blind decoding on the search space located in the last two OFDM symbols.

Meanwhile, the position of the control channel in the mmWave TTI corresponding to '4' and '5' in the CFI may be a position other than the last OFDM symbol, and is illustrated in FIGS. 15 (a) and 15 (b). Is just an example. As such, the position of the new control channel may be any position within the mmWave TTI and may be preset in the mmWave RRC layer.

According to the embodiment proposed above, it is possible to indicate a new search space through the mmWave CFI, it is possible to easily allocate a new control channel defined in the mmWave system. In addition, transmission diversity for a control channel defined in the mmWave system can be obtained, so that the decoding probability for the control channel within one TTI can also be increased.

Meanwhile, as described above, it may be known to the UE in advance by the mmWave system that two search spaces are set at heterogeneous positions within the mmWave TTI. For example, information indicating that a new search space (control channel 2 described above) is set up in addition to the conventional search space may be carried in the mmWave System Information Block (SIB) and known to the UE. Accordingly, the UE, recognizing that two or more search spaces are set in different locations, transmits a reference signal (RS) or a preamble in uplink in an RRC-connected state and receives the received signal. One mmWave base station sets up a search space for the PDCCH in the mmWave TTI. As described above, the diversity of the control information can be obtained as the search spaces are set at different positions.

FIG. 16 is a modified embodiment of the embodiment shown in FIG. 15. In the embodiment proposed in FIG. 15, the UE could know the search space of the control channel defined in the mmWave system through a channel indicating the position of the control channel, such as the PCFICH of the LTE system. In contrast, in the embodiment of FIG. 16, the UE may determine the search space location of the control channel from a channel serving as a PBCH (Physical Broadcast Channel) of the LTE system.

According to the embodiment proposed in FIG. 16, the position of the mmWave control channel is broadcast to the UE semi-persistent. In other words, when the information indicating the position of the mmWave control channel is broadcast once in the mmWave PBCH, as shown in FIG. 16, the UE continues to transmit the new control channel 'control channel 2' without additional signaling to the corresponding position in the mmWave TTI. (E.g., the last two OFDM symbols). On the other hand, if new information is broadcasted that sets the position of the mmWave control channel in a particular mmWave TTI that follows (eg, the information that the control channel is no longer defined in the last two OFDM symbols), the UE no longer has a 'control channel'. No blind decoding to detect 2 'is performed within the mmWave TTI.

In other words, according to the embodiment according to the scheme described with reference to FIG. 15, for every TTI, the base station indicates to the UE the position where the mmWave control channel is allocated through a channel such as PCFICH. On the other hand, according to the embodiment described with reference to FIG. 16, when the location to which the mmWave control channel is allocated by the base station through the same channel as the PBCH is instructed to the UE once, the mmWave control channel is semi-halted until a new indication is received. It is permanently assigned to the location and transmitted.

FIG. 17 illustrates an embodiment in which the embodiments described with reference to FIGS. 15 and 16 are combined. Unlike the embodiments described with reference to FIG. 16, only information on the number of control channels defined in the mmWave system may be defined in the same channel as the PBCH of the mmWave system. If the control channel of the mmWave system and the position of the PCFICH corresponding thereto is preset by the RRC layer, the UE blindly decodes the new control channel through the preset PCFICH even if only the position of the control channel is indicated in the PBCH as shown in FIG. can do.

Referring to FIG. 17 (b), the PCFICH is pre-set to the first OFDM symbol and the last OFDM symbol in the TTI, and the position of the control channel is the first two OFDM symbols (control channel 1) and the last three symbols. It may be preset to an OFDM symbol (control channel 2). In this case, when two UEs (ie, '01' bits) are received from the PBCH as a value for the number of control channels, the UE decodes the positions of the two preset PCFICHs to decode the search space for the control channel 1 and the control channel 2. After that, the control channel 1 and the control channel 2 may be detected by performing blind decoding on the corresponding search space.

18 to 20 are diagrams illustrating a control channel transmission method according to another exemplary embodiment. 15 to 17 have been described with reference to an embodiment of improving transmission diversity of a control channel. 18 to 20 illustrate a second embodiment in which the overhead of the control channel is maintained within the TTI, but the decoding reliability of the control channel is improved.

In the embodiments described with reference to FIGS. 18 through 20, an mmWave control channel enabler is defined. The mmWave control channel enabler is information indicating the transmission status of the mmWave control channel, and a position in the control channel is fixedly assigned. The UE can grasp information on the transmission performance of the entire control channel by decoding the mmWave control channel enabler received from the base station.

Specifically, as shown in FIG. 18A, the mmWave control channel enabler is allocated to a predetermined region in the mmWave control channel. UEs located within mmWave base station coverage know in advance where such control channel enablers are located. Alternatively, as shown in FIG. 18B, the mmWave control channel enabler may be distributed in the control channel.

Meanwhile, the mmWave control channel enabler is transmitted with a code previously promised between the base station and the UE, and the UE determines only whether it is decoded after receiving the mmWave control channel enabler. In other words, the mmWave control channel enabler is transmitted only to determine whether the UE is decoded by the UE so as to represent the transmission status over the control channel, rather than to obtain specific information.

The UE checks the power and link stability of the downlink control channel by receiving and decoding the mmWave control channel enabler. Subsequently, the UE transmits ACKnowledgement / Negative ACKnowledgement (ACK / NACK) for the mmWave control channel enabler to the base station. The ACK / NACK for the mmWave control channel enabler may be transmitted to the base station together with the ACK / NACK for the data in the corresponding TTI. That is, since the ACK / NACK for each of the enabler and the data are transmitted only once per TTI, the overhead of uplink signaling can be reduced by the UE transmitting both ACK / NACKs during uplink transmission.

19 is a flowchart illustrating a signaling process according to the introduction of the mmWave control channel enabler described above.

First, the mmWave base station transmits an mmWave control channel enabler in a control channel in a subframe (or TTI) to the UE. Upon receiving the enabler, the UE decodes the enabler and transmits ACK / NACK for the enabler and ACK / NACK for the data together to the base station in uplink. Subsequently, the base station receiving the ACK / NACK for the mmWave control channel enabler transmits a new downlink control channel to the UE by adjusting the transmission power. For example, if the UE successfully decodes the enabler (when an ACK is received), the transmission state of the previous downlink control channel transmission is determined to be good, so that the base station maintains or relatively transmits the next downlink control channel transmission power. Transmit uplink by a small value. On the other hand, if the UE fails to decode the enabler (when a NACK is received), the base station may transmit the next downlink control channel transmit power by adjusting a relatively large value.

FIG. 20 exemplarily illustrates the process described with reference to FIG. 19. 20 shows that the PCFICH may be used instead of the mmWave control channel enabler. That is, the PCFICH may be implemented to replace the role of the mmWave control channel enabler.

If the base station receives an ACK for the Enabler / PCFICH and an ACK for data (that is, receives an '11' bit), the base station knows that both the mmWave control channel and the mmWave data channel have good transmission. Can be. Therefore, the base station may use the same transmission power as the next downlink transmission. On the other hand, when the NACK for the enabler / PCFICH is received ('01'), the base station can know that the transmission state of the control channel is not good. If the transmission state of the control channel is not good, the decoding of the data channel is likely to fail as the decoding of the control channel fails, so that the base station considers that the correct decoding of the data channel has failed even if an ACK for the data channel is received. . Subsequently, the base station increases and transmits the transmission power for the control channel during the next downlink transmission.

On the contrary, when the ACK for the enabler / PCFICH and the NACK for the data are received ('10'), the base station retransmits only the data channel because the control channel itself is well transmitted but the decoding of the data channel fails. When the NACK for the Enabler / PCFICH and the NACK for the data are received ('00'), the base station determines that the transmission state of the data channel and the control channel are both poor and transmit power of the control channel in the next downlink transmission. Send it up. Finally, when the base station fails to receive the ACK / NACK of the response to the enabler / PCFICH and the response to the data, because the uplink transmission from the UE is poor, the base station can not determine whether the downlink transmission was successful . Therefore, the base station increases and transmits the transmission power of the control channel during the next downlink transmission.

4. Device Configuration

21 is a diagram illustrating a configuration of a terminal and a base station according to an embodiment of the present invention. In FIG. 21, the terminal 100 and the base station 200 may include radio frequency (RF) units 110 and 210, processors 120 and 220, and memories 130 and 230, respectively. In FIG. 21, only a 1: 1 communication environment between the terminal 100 and the base station 200 is illustrated, but a communication environment may be established between a plurality of terminals and a plurality of base stations. In addition, the base station 200 illustrated in FIG. 21 may be applied to both the macro cell base station and the small cell base station.

Each RF unit 110, 210 may include a transmitter 112, 212 and a receiver 114, 214, respectively. The transmitting unit 112 and the receiving unit 114 of the terminal 100 are configured to transmit and receive signals with the base station 200 and other terminals, and the processor 120 is functionally connected with the transmitting unit 112 and the receiving unit 114. In connection, the transmitter 112 and the receiver 114 may be configured to control a process of transmitting and receiving signals with other devices. In addition, the processor 120 performs various processes on the signal to be transmitted and transmits the signal to the transmitter 112, and performs the process on the signal received by the receiver 114.

If necessary, the processor 120 may store information included in the exchanged message in the memory 130. With such a structure, the terminal 100 can perform the method of various embodiments of the present invention described above.

The transmitter 212 and the receiver 214 of the base station 200 are configured to transmit and receive signals with other base stations and terminals, and the processor 220 is functionally connected to the transmitter 212 and the receiver 214 to transmit the signal. 212 and the receiver 214 may be configured to control the process of transmitting and receiving signals with other devices. In addition, the processor 220 may perform various processing on the signal to be transmitted, transmit the signal to the transmitter 212, and may perform processing on the signal received by the receiver 214. If necessary, the processor 220 may store information included in the exchanged message in the memory 230. With such a structure, the base station 200 may perform the method of the various embodiments described above.

Processors 120 and 220 of the terminal 100 and the base station 200 respectively instruct (eg, control, coordinate, manage, etc.) the operation in the terminal 100 and the base station 200. Respective processors 120 and 220 may be connected to memories 130 and 230 that store program codes and data. The memories 130 and 230 are coupled to the processors 120 and 220 to store operating systems, applications, and general files.

The processor 120 or 220 of the present invention may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, or the like. The processors 120 and 220 may be implemented by hardware or firmware, software, or a combination thereof.

When implementing an embodiment of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), and programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the processors 120 and 220.

Meanwhile, the above-described method may be written as a program executable on a computer, and may be implemented in a general-purpose digital computer which operates the program using a computer readable medium. In addition, the structure of the data used in the above-described method can be recorded on the computer-readable medium through various means. Program storage devices that may be used to describe storage devices that include executable computer code for performing the various methods of the present invention should not be understood to include transient objects, such as carrier waves or signals. do. The computer readable medium includes a storage medium such as a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (eg, a CD-ROM, a DVD, etc.).

It will be understood by those skilled in the art that embodiments of the present invention can be implemented in a modified form without departing from the essential characteristics of the above description. Therefore, the disclosed methods should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the detailed description of the invention, and all differences within the equivalent scope should be construed as being included in the scope of the present invention.

The control channel transmission and reception method in the mmWave system as described above can be applied to various wireless communication systems including not only 3GPP systems but also IEEE 802.16x and 802.11x systems.

Claims (12)

1. In the communication method of the terminal supporting the mmWave communication system,

   Receiving information indicating that two search spaces for detecting a control channel are set within one mmWave Transmission Time Interval (TTI);

   Receiving an indicator from an mmWave base station indicating a position in the mmWave TTI of a first search space and a second search space for detecting the control channel;

   Performing blind decoding on the first search space and the second search space respectively indicated by the indicator;

   Detecting a downlink control channel from at least one of the first search space and the second search space; And

   Decoding downlink data indicated by the downlink control channel.
2. The method of claim 1,

   Wherein the indicator is received every TTI.
3. The method of claim 1,

   And the indicator is received only by a TTI in which the settings of the first search space and the second search space are changed by the mmWave base station.
4. The method of claim 3,

   The blind decoding is performed semi-persistent according to a recently received indicator until a new indicator is received.
5. The method of claim 1,

   The first search space is disposed in n OFDM symbols from the first Orthogonal Frequency Division Multiplexing (OFDM) symbol of the TTI, and the second search space is disposed in m OFDM symbols from the last OFDM symbol of the TTI, and n and m are natural numbers.
6. The method of claim 1,

   And when the indicator indicates the number of search spaces including the first search space and the second search space, the blind decoding is performed at a preset position for the number of search spaces.
7. In the terminal supporting the mmWave communication system,

   A transmitter;

   Receiver; And

   A processor operating in connection with the transmitter and the receiver,

   The processor,

   Control the receiver to receive information indicating that two search spaces for detecting the control channel are set in one mmWave TTI,

   Control the receiving unit to receive, from a mmWave base station, an indicator indicating a position within the mmWave TTI of a first search space and a second search space for detecting the control channel,

   Perform blind decoding on the first search space and the second search space respectively indicated by the indicator,

   Detecting a downlink control channel from at least one of the first search space and the second search space;

   And decoding downlink data indicated by the downlink control channel.
8. The method of claim 7, wherein

   The indicator is received every TTI terminal.
9. The method of claim 7, wherein

   The indicator is received by the mmWave base station only in the TTI that the settings of the first search space and the second search space is changed, the terminal.
10. The method of claim 9,

    The processor is to perform the blind decoding in accordance with a recently received indicator until the new indicator is received, the terminal.
11. The method of claim 7, wherein

    Wherein the first search space is disposed in n OFDM symbols from the first OFDM symbol of the TTI, and the second search space is disposed in m OFDM symbols from the last OFDM symbol of the TTI, wherein n and m are natural numbers Phosphorus, terminal.
12. The method of claim 7, wherein

    When the indicator indicates the number of search spaces including the first search space and the second search space, the processor performs the blind decoding at a preset position with respect to the number of search spaces. .

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