CN110024323B

CN110024323B - Method for transmitting or receiving downlink control channel in NR and apparatus therefor

Info

Publication number: CN110024323B
Application number: CN201880004512.1A
Authority: CN
Inventors: 朴奎镇; 崔宇辰
Original assignee: KT Corp
Current assignee: KT Corp
Priority date: 2017-01-06
Filing date: 2018-01-05
Publication date: 2022-02-22
Anticipated expiration: 2038-01-05
Also published as: WO2018128440A1; CN110024323A

Abstract

The present embodiments relate to a method and apparatus for transmitting or receiving a downlink control channel in a next generation/5G radio access network. An embodiment provides a method for receiving a downlink control channel by a terminal, the method including the steps of: receiving configuration information related to a Common Search Space (CSS) from a base station; receiving a downlink control channel including information for scheduling Remaining Minimum System Information (RMSI) through a common search space, wherein configuration information is included in a Master Information Block (MIB) received through a physical broadcast channel and is received from a base station.

Description

Method for transmitting or receiving downlink control channel in NR and apparatus therefor

Technical Field

The present disclosure relates to a method and apparatus for transmitting/receiving a downlink control channel in a next generation/5G radio access network (hereinafter, referred to as "radio" or "NR") discussed in the third generation partnership project (3 GPP). More particularly, the present disclosure relates to a method for configuring a Common Search Space (CSS) to transmit cell-specific Downlink Control Information (DCI) to a user equipment through a downlink control channel and to transmit/receive the downlink control channel through the configured CSS.

Background

Recently, 3GPP has approved "research on new radio access technologies", which is a research project for research on next generation/5G radio access technologies. On the basis of the research on the new radio access technology, the radio access network working group 1(RAN WG1) has been discussing frame structures, channel coding and modulation, waveforms, multiple access methods, etc. for New Radios (NR). Compared to Long Term Evolution (LTE)/LTE-advanced, NR needs to be designed not only to provide improved data transmission rates, but also to meet various requirements in specific and specific usage scenarios.

Enhanced mobile broadband (eMBB), large-scale machine type communication (mtc), and ultra-reliable and low-latency communication (URLLC) are proposed as representative usage scenarios for NRs. In order to meet the requirements of various scenarios, it is required to design it as a flexible frame structure compared to LTE/LTE-advanced.

In NR having such various usage scenarios, it is required to configure resources of a downlink control channel in order to transmit/receive scheduling control information based on time/frequency resources of each user equipment, which are different from each other.

In particular, it is necessary to define a method for configuring time and frequency resources of a Common Search Space (CSS) for transmitting cell-specific Downlink Control Information (DCI) through a downlink control channel. In addition, it is necessary to define a method for configuring a parameter set of a downlink control channel including information for scheduling Remaining Minimum System Information (RMSI) transmitted through a common search space.

Disclosure of Invention

Technical problem

An object of the present disclosure is to provide a method of transmitting/receiving a downlink control channel for transmitting/receiving scheduling control information based on time/frequency resources different from each other by each user equipment in NR having such various usage scenarios.

Technical scheme

According to an aspect of the present disclosure, to solve the problems, a method for a user equipment to receive a downlink control channel (PDCCH) is provided. The method comprises the following steps: receiving configuration information on a Common Search Space (CSS) from a base station, and receiving a downlink control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space. Wherein the configuration information is included in a Master Information Block (MIB) received from the base station through a Physical Broadcast Channel (PBCH).

According to another aspect of the present disclosure, there is provided a method for a base station to transmit a downlink control channel (PDCCH). The method comprises the following steps: configuring configuration information on a Common Search Space (CSS), transmitting the configuration information to a user equipment, and transmitting a downlink control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space. Wherein the configuration information is included in a Master Information Block (MIB) transmitted to the user equipment through a Physical Broadcast Channel (PBCH).

According to still another aspect of the present disclosure, there is provided a user equipment for receiving a downlink control channel (PDCCH). The user equipment includes: a receiver configured to receive configuration information on a Common Search Space (CSS) from a base station; and receiving a downlink control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space. Wherein the configuration information on the common search space is included in a Master Information Block (MIB) received from the base station through a Physical Broadcast Channel (PBCH).

According to yet another aspect of the present disclosure, there is provided a base station for transmitting a downlink control channel (PDCCH). The base station includes: a controller configured to configure configuration information regarding a common search space; and a transmitter configured to transmit the configuration information to the user equipment, and transmit a downlink control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space. Wherein the configuration information on the common search space is included in a Master Information Block (MIB) transmitted to the user equipment through a Physical Broadcast Channel (PBCH).

Advantageous effects

According to some embodiments of the present disclosure, a method for transmitting/receiving scheduling control information based on mutually different time/frequency resources of each user equipment in NR having various usage scenarios may be provided.

Drawings

Fig. 1 is a diagram showing an arrangement of orthogonal frequency division multiple access (OFDM) symbols in the case of using subcarrier intervals different from each other.

Fig. 2 is a diagram showing a conceptual example of a bandwidth part (BWP).

Fig. 3 is a flowchart illustrating a procedure of a user equipment for receiving a downlink control channel according to an embodiment of the present disclosure.

Fig. 4 is a flowchart illustrating a procedure for a base station to transmit a downlink control channel according to an embodiment of the present disclosure.

Fig. 5 is a block diagram illustrating a base station according to an embodiment of the present disclosure.

Fig. 6 is a block diagram illustrating a user equipment according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When reference numerals are added to elements in each drawing, the same elements will be referred to by the same reference numerals if possible, although they are shown in different drawings. In addition, in the following description of the present disclosure, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure unclear.

In the present disclosure, a wireless communication system refers to a system for providing various communication services such as a voice communication service, a packet data service, and the like. A wireless communication system includes a User Equipment (UE) and a Base Station (BS).

UE is a generic term referring to devices used in wireless communications. For example, a UE may refer to, but is not limited to, a UE supporting Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), High Speed Packet Access (HSPA), International Mobile Telecommunications (IMT) -2020(5G or new radio), etc., a Mobile Station (MS) supporting global system for mobile communications (GSM), a User Terminal (UT), a Subscriber Station (SS), a wireless device, etc.

A base station or cell generally refers to a station that communicates with the UE. A base station or cell is a generic term that relates to, but is not limited to: all of the various communication service areas and devices, such as node bs, evolved node bs (enbs), g node bs (gnbs), Low Power Nodes (LPNs), sectors, sites, various types of antennas, Base Transceiver Systems (BTSs), access points, points (e.g., transmission points, reception points, or transmission points), relay nodes, megacells, macrocells, microcells, picocells, femtocells, remote radio terminals (RRHs), Radio Units (RUs), and microcells.

Each of the various cells is controlled by a base station. Thus, base stations can be divided into two categories. 1) A base station may refer to an apparatus that forms and provides a corresponding communication service area, such as a macrocell, a microcell, a picocell, a femtocell, and a small cell, or 2) a base station may refer to a communication service area. In case of 1), a base station may refer to i) a device forming and providing any corresponding communication service area and controlled by the same entity, or ii) a device interacting and cooperating with each other to form and provide a corresponding communication service area. A base station may refer to a point, a transmission/reception point, a transmission point, a reception point, etc., depending on the communication scheme employed by the base station. In case 2), the base station may be a communication service area itself, in which the UE can receive or transmit signals from or to other UEs and neighboring base stations.

In the present disclosure, a cell may also refer to a coverage of a signal transmitted from a transmission/reception point, a component carrier having a coverage of a signal transmitted from a transmission point or a transmission/reception point, or a transmission/reception point itself.

The UE and the base station are two entities that perform transmission/reception for embodying the technology and technical spirit described in this specification. The UE and the BS are general terms and are not limited to specific terms or words.

Here, Uplink (UL) refers to transmission/reception of data to/from the base station by the UE, and Downlink (DL) refers to transmission/reception of data to/from the UE by the base station.

UL transmission and DL transmission may be performed by utilizing: i) a Time Division Duplex (TDD) technique in which transmission is performed through different time slots, ii) a Frequency Division Duplex (FDD) technique in which transmission is performed through different frequencies, or ii) a hybrid technique of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

Further, the related standards of the wireless communication system define configuring UL and DL based on a single carrier or a carrier pair.

The UL and DL transmit control information over one or more control channels, such as a Physical DL Control Channel (PDCCH), a Physical UL Control Channel (PUCCH), and so on. UL and DL transmit data through data channels such as Physical DL Shared Channel (PDSCH), Physical UL Shared Channel (PUSCH), etc.

DL may refer to a communication or communication path from a plurality of transmission/reception points to a UE, and UL may refer to a communication or communication path from a UE to a plurality of transmission/reception points. In DL, a transmitter may be part of a plurality of transmission/reception points, and a receiver may be part of a UE. In the UL, the transmitter may be part of the UE, and the receiver may be part of multiple transmission/reception points.

Hereinafter, transmission and reception of a signal through a channel such as PUCCH, PUSCH, PDCCH, or PDSCH may be described as transmission and reception of PUCCH, PUSCH, PDCCH, or PDSCH.

Meanwhile, the higher layer signaling includes Radio Resource Control (RRC) signaling that transmits RRC information including RRC parameters.

The base station performs DL transmission to the UE. The base station may transmit a physical DL control channel for transmitting: i) DL control information such as scheduling required to receive a DL data channel which is a primary physical channel for unicast transmission; and ii) scheduling grant information for transmission over the UL data channel. Hereinafter, the transmission/reception of signals through each channel may be described in such a manner that the corresponding channel is transmitted/received.

Any of the multiple access techniques may be applied to the wireless communication system and thus do not impose limitations on them. For example, a wireless communication system may employ various multiple-access techniques, such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), CDMA, Orthogonal Frequency Division Multiple Access (OFDMA), non-orthogonal multiple access (NOMA), OFDM-TDMA, OFDM-FDMA, OFDM-CDMA, and so forth. NOMA includes Sparse Code Multiple Access (SCMA), low cost extension (LDS), etc.

At least one embodiment of the present disclosure may be applied to resource allocation in: i) asynchronous wireless communication evolving from GSM, WCDMA and HSPA to LTE/LTE-advanced and IMT-2020, ii) synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB.

In the present disclosure, a Machine Type Communication (MTC) terminal may refer to a terminal supporting low cost (or low complexity), a terminal supporting coverage enhancement, and the like. As another example, an MTC terminal may refer to a terminal defined as a predetermined class for supporting low cost (or low complexity) and/or coverage enhancement.

In other words, MTC terminals may refer to low cost (or low complexity) UE classes/types newly defined in 3GPP release 13 and perform LTE-based MTC-related operations. MTC devices of the present disclosure may refer to a device class/type defined in or before 3GPP release 12, which supports enhanced coverage or supports low power consumption compared to existing LTE coverage, or may refer to a low-cost (or low-complexity) device class/type newly defined in release 13. MTC terminals may refer to further enhanced MTC terminals as defined in release 14.

In this disclosure, a narrowband internet of things (NB-IoT) terminal refers to a terminal that supports radio access for cellular IoT. NB-IoT technology is directed to improved indoor coverage, support for large-scale low-speed terminals, low latency sensitivity, very low terminal cost, low power consumption, and optimized network architecture.

Enhanced mobile broadband (eMBB), large-scale machine type communication (mtc), and ultra-reliable and low-delay communication (URLLC) are proposed as representative usage scenarios of NR that have recently been discussed in 3 GPP.

In the present disclosure, frequencies, frames, subframes, resources, Resource Blocks (RBs), regions, bands, sub-bands, control channels, data channels, synchronization signals, various reference signals, various signals, and various messages associated with NRs may be interpreted as meanings used in the past or now or as various meanings to be used in the future.

NR (New radio)

Recently, 3GPP has approved "research on new radio access technology", which is a research project for research on next generation/5G radio access technology. On the basis of the research of new radio access technologies, a frame structure, channel coding and modulation, waveforms, multiple access methods, etc. of a New Radio (NR) have been discussed.

Compared to Long Term Evolution (LTE)/LTE-advanced, NR needs to be designed not only to provide improved data transmission rates, but also to meet various requirements in specific and specific usage scenarios. In particular, enhanced mobile broadband (eMBB), large-scale machine type communication (mtc), and ultra-reliable and low-latency communication (URLLC) are proposed as representative usage scenarios for NRs. In order to meet the requirements of various scenarios, it is necessary to design it as a flexible frame structure compared to LTE/LTE-advanced.

In particular, eMBB, mtc, URLLC have been considered by 3GPP as a representative usage scenario for NR. Since each usage scenario puts different requirements on data rate, delay, coverage, etc., a method for efficiently multiplexing radio resource units different from each other based on a parameter set (e.g., subcarrier spacing (SCS), subframe, Transmission Time Interval (TTI), etc.) is required as a scheme for efficiently satisfying the requirements according to the usage scenario by a frequency band provided to an arbitrary NR system.

To this end, there have been discussed methods regarding i) multiplexing parameter sets each having a subcarrier spacing (SCS) value different from each other by one NR carrier based on a TDM, FDM, or TDM/FDM technique, and ii) supporting one or more time units when configuring a scheduling unit in a time domain. In this regard, in NR, the definition of a subframe has been given as one type of time domain structure. In addition, as a reference parameter set for defining a corresponding subframe duration, a single subframe duration is defined as 14 OFDM symbols with a normal CP overhead based on a 15kHz subcarrier spacing (SCS), like LTE. Thus, the subframes of NR have a duration of 1 ms. Unlike LTE, since the subframe of NR is an absolute reference duration, a slot and a micro slot may be defined as a time unit used as a basis for actual UL/DL data scheduling. In this case, the number of OFDM symbols forming a slot, the value of y, has been defined as y-14 regardless of the parameter set.

Thus, a slot may be formed of 14 symbols. All symbols may be used for DL transmission or UL transmission, or symbols may be used in a configuration of DL part + gap + UL part, depending on the transmission direction of the corresponding slot.

Further, a micro slot formed of fewer symbols than the slot has been defined in the parameter set (or SCS), and thus, a short time domain scheduling interval may be set for micro slot based UL/DL data transmission or reception. In addition, the long-time domain scheduling interval may be set for UL/DL data transmission or reception through slot aggregation.

In particular, in the case of transmitting or receiving delay critical data, such as URLLC, when scheduling is performed based on slot units based on 0.5ms (7 symbols) or 1ms (14 symbols) defined in a frame structure based on a parameter set having a small SCS value (e.g., 15kHz), it may be difficult to satisfy the delay requirement. For this reason, a minislot formed of fewer OFDM symbols than a slot may be defined, and thus scheduling of delay-critical data, such as URLLC, may be performed on a microslot basis.

Further, a method of scheduling data according to delay requirements based on time slots (or micro-slots) defined for each parameter set by multiplexing the parameter sets each having an SCS value different from each other in one NR carrier using the TDM or FDM technique as described above has been discussed. For example, as shown in fig. 1, in the case of the SCS of 60kHz, since the length of a symbol is shortened by about one-fourth of the length of the symbol of the SCS of 15kHz, in both cases, when one slot is formed of seven OFDM symbols, the slot length of the SCS based on 15kHz is 0.5ms, and the slot length of the SCS based on 60kHz is shortened to about 0.125 ms.

In this regard, discussion is underway regarding a method of satisfying each requirement of URLLC and eMBB by defining different SCS or different TTI length in NR.

Wider bandwidth operation

Typical LTE systems support scalable bandwidth operation of LTE Component Carriers (CCs). That is, when one LTE CC is configured according to a frequency deployment scenario, an LTE service provider may configure the LTE CC with a bandwidth divided from a frequency range of 1.4MHz to 20 MHz. Therefore, the LTE UE has a transmission/reception capability for supporting a 20MHz bandwidth for one LTE CC.

However, NR is designed to support NR UEs having transmission/reception capabilities for different bandwidths from each other in one NR CC. To this end, one or more bandwidth parts (BWPs) divided from the NR CC may be configured as shown in fig. 2. In addition, there is a need to support flexible wider bandwidth operation to enable configuring and activating mutually different bandwidth portions for each UE.

Referring to fig. 2, N bandwidth parts may be defined by dividing the entire bandwidth of one NR CC into one or more parts, and each UE may activate and use one or more bandwidth parts of the N bandwidth parts.

Thus, the NR CC may be divided into one or more bandwidth parts. Thus, each UE may be configured with one or more bandwidth portions. One or more bandwidth parts of the bandwidth parts configured for the UE may be activated and UL/DL radio signals and radio channels may be transmitted/received for the UE using the one or more activated bandwidth parts.

In addition, in the case where a plurality of parameter sets are supported in the NR CC, different parameter sets from each other may be configured for each bandwidth part for transmission/reception of UL/DL radio signals and radio channels.

As described above, in order to support the URLLC service in NR, it is necessary to support a short scheduling unit (or, TTI (transmission time interval)) capable of satisfying a delay boundary in the time domain. In contrast, in the case of eMBB or mtc, to define the scheduling unit in the time domain, using a slightly longer time interval resource allocation unit may be more effective in terms of control overhead and coverage than that of URLLC.

Therefore, as a method for simultaneously satisfying various NR usage scenarios, a mixed parameter set technique may be employed to support, by one NR carrier, a parameter set of a subcarrier spacing (e.g., a larger subcarrier spacing such as 60kHz, 120kHz, etc.) that easily defines a short interval resource allocation unit suitable for URLLC, and a subcarrier spacing (e.g., 15kHz for eMBB or 3.75kHz for mtc) suitable for eMBB and mtc.

As another example, in an NR carrier operating with a specific set of parameters, time domain scheduling units, such as subframes, slots, or minislots, each having a different length from each other, may be simultaneously supported.

According to the embodiments of the present disclosure, in NR considering these various usage scenarios, a method for configuring resources of a DL control channel for transmitting/receiving scheduling control information based on different time domain scheduling units from one UE to another for each UE and a method for monitoring the DL control channel by the UE are discussed.

In particular, a method for configuring a Common Search Space (CSS) for transmitting cell-specific DL Control Information (DCI) through a DL control channel is provided.

It is to be noted that the method of configuring the CSS according to an embodiment of the present disclosure may be interpreted as a method of configuring a control resource set (CORESET) in which the CSS is configured.

In addition, the cell-specific DCI included in the PDCCH transmitted through the CSS configured in the CORESET may include: i) scheduling control information on Remaining Minimum System Information (RMSI), ii) cell-specific Transmit Power Control (TPC) -related configuration information, iii) scheduling control information on a paging message, iv) scheduling control information on a Random Access Response (RAR).

Hereinafter, for convenience of description and easy understanding, a method related to CSS configuration is discussed, but the method may be construed as a method of configuring CORESET.

The embodiments described below may be applied to all UEs, base stations, and core network entities (MMEs) using various mobile communication technologies. For example, the embodiments of the present disclosure may be applied not only to a mobile communication UE adopting a long term evolution technology but also to a next generation mobile communication (5G mobile communication, new-RAT) UE, a base station, and an Access and Mobility Function (AMF). For convenience of description, in a 5G radio network in which CUs are separated from DUs, a base station may represent an eNB of LTE/E-UTRAN, or at least one of a Central Unit (CU), an allocation unit (DU), and an object in which the CU and DU are implemented as one logical object, or a gNB.

In addition, the parameter set in the present disclosure represents parameter characteristics and values of data transmission/reception. The parameter set may be determined according to a value of subcarrier spacing (hereinafter, referred to as SCS or subcarrier spacing). That is, the subcarrier spacing may be used to determine whether each parameter set is different from another, and thus a different parameter set may mean that the subcarrier spacing at which the parameter sets are determined is different.

The slot length in the present disclosure may be expressed as the number of OFDM symbols forming a slot or the time occupied by a slot. For example, in case of using a parameter set based on 15kHz SCS, the length of one symbol may be represented as 14 orthogonal frequency division multiple symbols, or as 1 ms.

In addition, the Remaining Minimum System Information (RMSI) is a part of system information, i.e., System Information Block (SIB)1, and may be transmitted to the UE. Thus, the remaining minimum system information may be referred to as SIB 1. System information transmitted to the UE through SIBs other than the SIB1 may be referred to as Other System Information (OSI).

Fig. 3 is a flowchart illustrating a procedure for a UE to receive a DL control channel according to an embodiment of the present disclosure.

Referring to fig. 3, a UE may receive configuration information on a Common Search Space (CSS) from a base station at step S300.

At this time, configuration information on the common search space may be included in a Master Information Block (MIB) received through a Physical Broadcast Channel (PBCH). That is, the base station may broadcast the master information block to UEs located in the cell through the PBCH. At this time, the base station may include configuration information regarding the common search space in the master information block.

An example of information included in such configuration information may be subcarrier spacing (SCS) information regarding DL control channels transmitted to the UE through a common search space.

As described above, a plurality of parameter sets may be configured in the NR CC/cell, and the parameter sets for transmitting the PDCCH may be different. Accordingly, parameter set configuration information on the PDCCH may be included in configuration information on the common search space. As described above, the parameter set may be different according to the subcarrier spacing value, and thus the subcarrier spacing information may be included in the configuration information on the common search space.

Another example of information included in such configuration information may be time resource allocation information and frequency resource allocation information regarding a common search space.

At this time, the time resource allocation information may be information on a period of the common search space. The period may be defined as: i) a fixed value regardless of subcarrier spacing value or slot length, or ii) a function of subcarrier spacing value, or may be set by subcarrier spacing value and slot length used for transmitting PSS/SSS or PBCH.

At this time, the frequency resources allocated by the frequency resource allocation information may be allocated with one or more consecutive Physical Resource Blocks (PRBs). That is, the frequency resource allocation information may include information on a set of consecutive PRBs forming a common search space.

In addition, at step S310, the UE may receive a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through a common search space.

The UE may receive the DL control channel through the common search space based on the configuration information on the common search space received in step S300.

The DL control channel received through the common search space may include cell-specific DCI common to all UEs located in the cell. At this time, an example of information included in the cell-specific DCI may be information for scheduling Remaining Minimum System Information (RMSI), i.e., control information on RMSI.

Fig. 4 is a flowchart illustrating a procedure for a base station to transmit a DL control channel according to an embodiment of the present disclosure.

Referring to fig. 4, a base station may configure configuration information on a Common Search Space (CSS) at step S400.

At this time, the time resource allocation information may be information on a period of the common search space. The period may be defined as: i) a fixed value regardless of the subcarrier spacing value or the slot length, or ii) a function of the subcarrier spacing value, or may be set by the subcarrier spacing value and the slot length used for transmitting the PSS/SSS or the PBCH.

At this time, the frequency resources allocated by the frequency resource allocation information may be allocated with one or more consecutive Physical Resource Blocks (PRBs). The frequency resource allocation information may include information on a set of consecutive PRBs forming a common search space.

In addition, the base station may transmit configuration information regarding a Common Search Space (CSS) to the UE at step S410.

At this time, configuration information regarding the common search space may be included in a Master Information Block (MIB) received through a Physical Broadcast Channel (PBCH), as described above with reference to fig. 3. That is, when broadcasting a master information block to UEs located in a cell through PBCH, a base station may include configuration information on a common search space in the master information block.

In addition, the base station may transmit a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space at step S420.

The base station may transmit the DL control channel through the common search space based on the configuration information on the common search space configured in step S400.

The DL control channel received through the common search space may include cell-specific DCI common to all UEs located in the cell, as described above with reference to fig. 3. At this time, an example of information included in the cell-specific DCI may be information for scheduling Remaining Minimum System Information (RMSI), i.e., control information on RMSI.

Hereinafter, the above-described method for the UE and the BS to configure the DL control channel will be discussed in detail according to various embodiments.

Some of the embodiments described below may be configured alone or in any combination.

Example 1 CSS period settings

According to embodiment 1, a method for configuring resources on a time domain axis for CSS or sets configured with CSS may be provided. Specifically, the configuration information on the time interval resources of the NR Component Carriers (CCs)/CSSs in the cell may be information on a period for configuring the CSS.

As described above, in NR, it is required to support a plurality of parameter sets based on SCS different from each other. Therefore, in NR, data scheduling may be performed based on a frame structure based on SCS different from each other and a corresponding slot length according to a frequency band or usage scenario of an NR cell.

As such, in NR based on a plurality of parameter sets, the period of the CSS can be set at a fixed period regardless of the SCS value and the corresponding slot length. For example, in NR, CSS may be defined to be configured based on units of subframes (i.e., units of 1 ms).

As another example for setting the CSS period, the CSS period may be set as a function of the SCS value. That is, the CSS period may be different according to the SCS value used in the NR cell. At this time, the CSS period may be defined as a function of the SCS value, or a function of the slot length set in the NR cell.

For example, the CSS may be configured based on a unit of a slot defined in a cell. In case that multiple SCS are supported in the NR cell, the CSS may be configured based on the SCS through which the PSS/SSS or PBCH is transmitted and the corresponding slot length. As another example, one or more separate CSSs may be configured according to each SCS and slot length.

As yet another example, the base station or the network may set the period of the CSS and transmit the set period to the UE through cell-specific signaling (such as MIB or SIB).

For example, configuration information related to the CSS period may be included in the MIB transmitted through the PBCH. The configuration information related to CSS period may be: i) configuration of a slot unit based on the CSS-based transmission parameter set and a corresponding slot length, ii) configuration information of a slot unit based on a radio frame or subframe, iii) information on one or more slot indexes or one or more subframe indexes used to configure the CSS in the radio frame based on the unit of one or more radio frames.

Example 2CSS sub-band configuration

According to embodiment 2, a method for configuring resources on a time domain axis for CSS or sets configured with CSS may be provided. Specifically, the allocation information of the frequency interval resources of the CSS in the NR Component Carrier (CC)/cell may be subband-related allocation information or bandwidth-portion-related allocation information of a set of consecutive Physical Resource Blocks (PRBs) configured with the CSS.

As described above, in case of the subframe or slot based unit configuration CSS, a method for defining a set of PRBs (i.e., one or more subbands) for configuring the CSS in a subframe or slot is as follows.

A set of PRBs may be defined in the form of a function of i) each or ii) two or more factors, such as the physical cell id (pci), subframe or slot index of the cell, system bandwidth (number of PRBs) or SCS value of the cell.

As another example, the base station may set whether or which of the factors are applied, and then transmit the set result to the UE through cell-specific RRC signaling (such as MIB or SIB). The UE may then configure one or more subbands for the CSS based on signaling from the base station.

For example, the base station may cause the UE to set whether the UE will apply CSS subband hopping on a subframe or slot basis by cell-specific RRC signaling (e.g., MIB or SIB).

One or more CSS subbands defined on a per subframe or slot unit basis may be the same or frequency hopped depending on a corresponding subframe or slot index.

The base station or the network may directly configure frequency resource allocation information for configuring the CSS and then transmit the configured information to the UE through cell-specific RRC signaling (such as MIB or SIB).

For example, frequency resource allocation information for configuring the CSS may be included in the MIB transmitted through the PBCH. At this time, the frequency resource allocation information may be bandwidth part allocation information for configuring CSS or PRB allocation information in a corresponding bandwidth part.

Alternatively, the frequency resources used to configure the CSS may be limited to the frequency band over which SS blocks are transmitted in the corresponding NR CC/cell. For example, the CSS may be configured by a bandwidth through which PSS/SSS or PBCH transmission is performed. Specifically, the CSS may be configured by the same PRB as the PRB through which the PSS/SSS or PBCH transmission is performed. Alternatively, the CSS may be configured by a bandwidth part including the PSS/SSS or PBCH.

Embodiment 3 Transmission parameter set configuration for PDCCH

According to embodiment 3, a method for configuring a transmission parameter set of a DL control channel including cell-specific DCI transmitted through CSS or CORESET configured with CSS may be provided.

As described above, in the case where a plurality of parameter sets are supported in the NR cell, each individual CSS may be configured for each parameter set. In addition, only CSS may be defined based on a reference parameter set (i.e., a single parameter set) for PSS/SSS or PBCH transmission.

Meanwhile, after configuring the transmission parameter set of the CSS, the base station or the network may transmit the configured result to the UE through cell-specific RRC signaling (such as MIB or SIB).

For example, configuration information related to a transmission parameter set of the CSS (e.g., configuration information related to a length of the SCS or Cyclic Prefix (CP), etc.) may be included in the MIB transmitted through the PBCH.

In addition, in NR, as a method of configuring CSS for a UE, it may be defined that CSS configuration is to be performed using a plurality of CSSs classified by purpose/use or using CSS configured CORESET.

Specifically, separate CSSs may be defined by purpose/use, such as i) a CSS for transmitting a PDCCH including scheduling control information of RMSI, ii) a CSS for transmitting a PDCCH including scheduling control information about other system information (i.e., system information other than MIB or RMSI transmitted through PBCH), iii) a CSS for transmitting scheduling control information about Random Access Response (RAR), iv) a CSS for transmitting scheduling control information about paging messages, v) a CSS for fallback operation for UE-specific search spaces (USS) configured per UE, or vi) a CSS for transmitting multicast/broadcast control information such as TPC commands or the like. It is noted that one or more of the above CSSs may be shared for a variety of specific purposes/uses.

Thus, where multiple CSSs are defined, each CSS configuration may be hierarchical. That is, each of the CSS configuration information discussed in embodiments 1, 2, and 3 above may be sequentially performed through MIB, RMSI, and the like.

For example, CSS configuration-related information of RMSI may be transmitted through MIB transmitted through PBCH, and thereafter CSS configuration-related information for other system information or CSS configuration-related information for paging, RAR, etc. may be transmitted through RMSI. All cases where a plurality of CSSs are defined according to purpose/use and each CSS configuration is hierarchical may be included within the scope of the embodiments discussed above.

Referring to fig. 5, the base station includes a controller 510, a transmitter 520, and a receiver 530.

The controller 510 is configured to control the overall operation of the base station 500 for transmitting the DL control channel in order to perform the above-described embodiments.

In particular, the controller may configure configuration information regarding a Common Search Space (CSS).

As described above, a plurality of parameter sets may be configured in the NR cell, and the parameter sets for transmitting the PDCCH may be different from each other. Accordingly, parameter set configuration information on the PDCCH may be included in configuration information on the common search space. As described above, the parameter set may be different according to the subcarrier spacing value, and thus the subcarrier spacing information may be included in the configuration information on the common search space.

At this time, the frequency resources allocated by the frequency resource allocation information may be allocated with one or more consecutive Physical Resource Blocks (PRBs). The frequency resource allocation information may include information on a set of consecutive PRBs configuring a common search space.

The transmitter 520 and the receiver 530 are configured to transmit and receive signals, messages and data, respectively, to and from the UE, which are required to perform some embodiments as described above.

Specifically, the transmitter 520 is configured to transmit configuration information on a common search space to the UE, and transmit a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space.

At this time, configuration information regarding the common search space may be included in a Master Information Block (MIB) transmitted through a Physical Broadcast Channel (PBCH), and may be transmitted to the UE, as described above with reference to fig. 4.

The base station may transmit the DL control channel through the common search space based on the configuration information on the common search space.

As described above, the DL control channel received through the common search space may include cell-specific DCI common to all UEs located in a cell. At this time, an example of information included in the cell-specific DCI may be information for scheduling Remaining Minimum System Information (RMSI), i.e., control information on RMSI.

Fig. 6 is a block diagram illustrating a UE according to an embodiment of the present disclosure.

Referring to fig. 6, the UE includes a receiver 610, a controller 620, and a transmitter 630.

The receiver 610 is configured to receive DL control information, data, and messages from a base station through a corresponding channel.

In particular, the receiver 610 may be configured to receive configuration information regarding a Common Search Space (CSS).

At this time, configuration information on the common search space may be included in a Master Information Block (MIB) received through a Physical Broadcast Channel (PBCH). That is, when broadcasting a master information block to UEs located in a cell through PBCH, a base station may include configuration information on a common search space in the master information block.

At this time, the time resource allocation information may be information on a period of the common search space. The period may be defined as: i) a fixed value regardless of the subcarrier spacing value or slot length, or ii) a function of the subcarrier spacing value, or may be set by the subcarrier spacing value or slot length used to transmit the PSS/SSS or PBCH.

The receiver 610 may be configured to receive a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through a common search space.

The controller is configured to control the overall operation of the UE for receiving the DL control channel in order to perform the above-described embodiments.

The standardized specifications or standard documents related to the above-described embodiments constitute a part of the present disclosure. Accordingly, it is to be understood that incorporation of the contents of the standardized specifications and a portion of the standard documents into the detailed description and claims is within the scope of the present disclosure.

Although the preferred embodiments of the present disclosure have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Thus, exemplary aspects of the disclosure have been described for non-limiting purposes but to describe embodiments, and thus the scope of the disclosure should not be limited to such embodiments. The scope of the present disclosure should be construed based on the following claims, and all technical concepts within the scope of equivalents thereof should be construed as being included in the scope of the present disclosure.

Cross Reference to Related Applications

If applicable, the present application claims priority under 35 U.S.C. 119(a) of patent application No. 10-2017 § 0002589, filed on 30.5.2017, 2018, patent application No. 10-2017 § 0066632, filed on 4.1.2018, patent application No. 10-2018 § 0001157, filed on 4.1.2018, which are incorporated herein by reference in their entirety. In addition, the non-provisional application claims priority in countries other than the united states for the same reason based on korean patent application, which is incorporated herein by reference in its entirety.

Claims

1. A method for a user equipment to receive a Downlink (DL) control channel (PDCCH), the method comprising:

receiving configuration information on a Common Search Space (CSS) from a base station; and

receiving a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space,

wherein the configuration information is included in a Master Information Block (MIB) received from the base station through a Physical Broadcast Channel (PBCH),

wherein the configuration information includes time resource allocation information and frequency resource allocation information regarding the common search space,

wherein the frequency resource allocation information includes allocation information related to a bandwidth part configured with a set of consecutive Physical Resource Blocks (PRBs) configured with CSS, and

wherein the bandwidth part is one of a plurality of bandwidth parts configured in a component carrier, and each bandwidth part is configured with a different subcarrier spacing (SCS).

2. The method of claim 1, wherein the configuration information comprises subcarrier spacing (SCS) information regarding the DL control channel.

3. The method of claim 1, wherein the time resource allocation information is information on a periodicity of the common search space.

4. A method for a base station to transmit a Downlink (DL) control channel (PDCCH), the method comprising:

configuring configuration information regarding a Common Search Space (CSS);

sending the configuration information to user equipment; and

transmitting a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space,

wherein the configuration information is included in a Master Information Block (MIB) transmitted to the user equipment through a Physical Broadcast Channel (PBCH),

5. The method of claim 4, wherein the configuration information comprises subcarrier spacing (SCS) information for the DL control channel.

6. The method of claim 4, wherein the time resource allocation information is information on a periodicity of the common search space.

7. A user equipment for receiving a Downlink (DL) control channel (PDCCH), comprising:

a receiver configured to receive configuration information on a common search space from a base station and receive a DL control channel (PDCCH) including information for scheduling Remaining Minimum System Information (RMSI) through the common search space,

8. The user equipment of claim 7, wherein the configuration information comprises subcarrier spacing (SCS) information for the DL control channel.

9. The user equipment of claim 7, wherein the time resource allocation information is information on a periodicity of the common search space.