WO2021022736A1

WO2021022736A1 - Apparatus and method for enhanced physical downlink control channel transmission and reception

Info

Publication number: WO2021022736A1
Application number: PCT/CN2019/122742
Authority: WO
Inventors: Li Guo
Original assignee: Guangdong Oppo Mobile Telecommunications Corp., Ltd.
Priority date: 2019-08-08
Filing date: 2019-12-03
Publication date: 2021-02-11
Also published as: CN113545144B; CN113545144A

Abstract

An apparatus and a method for enhanced physical downlink control channel (PDCCH) transmission and reception. A first downlink control information (DCI) is repeated in PDCCH transmission from a transmitter apparatus through transmitting a first copy of the first DCI in a first PDCCH candidate allocated in a first control resource set (CORESET) and a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET. The first CORESET and the second CORESET are associated with a first search space set. When the repeated first DCI and related configuration of the first DCI is received and obtained by a receiver apparatus, the receiver apparatus obtains the first DCI from the first copy and the second copy of the first DCI using the related configuration of the first DCI.

Description

APPARATUS AND METHOD FOR ENHANCED PHYSICAL DOWNLINK CONTROL CHANNEL TRANSMISSION AND RECEPTION

BACKGROUND OF DISCLOSURE

1. Field of Disclosure

The present disclosure relates to the field of communication systems, and more particularly, to an apparatus and a method for enhanced PDCCH transmission and reception.

2. Description of Related Art

Current design of physical downlink control channel (PDCCH) , as specified in 3rd generation partnership project (3GPP) release 15, may only support transmitting PDCCH from a single transmission reception point (TRP) , and does not address PDCCH reliability.

A TRP with best channel condition may be selected to transmit the PDCCH to a user equipment (UE) . Channel condition between one TRP and the UE can vary dynamically but the configuration of search space for monitoring PDCCH is semi-statically and cannot track the radio channel variation closely. Re-configuring search space for monitoring PDCCH takes time and causes long latency and large signaling overhead.

Therefore, there is a need for an apparatus and a method for enhanced PDCCH transmission.

SUMMARY

An object of the present disclosure is to propose an apparatus and a method for enhanced PDCCH transmission and reception capable of providing enhanced reliability.

In a first aspect of the present disclosure, a method for enhanced PDCCH transmission executable by an apparatus, comprising: repeating transmission of first downlink control information (DCI) by transmitting a first copy of the first DCI in a first PDCCH candidate allocated in a first control resource set (CORESET) and a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET, wherein the first CORESET and the second CORESET are associated with a first search space set.

In a second aspect of the present disclosure, a method for enhanced PDCCH reception executable by an apparatus, comprising: receiving repetition of a first DCI and configuration of the repetition of the first DCI; obtaining a first copy of the first DCI in a first PDCCH candidate allocated in a first CORESET according to the configuration; obtaining a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET according to the configuration, wherein the first CORESET and the second CORESET are associated with a search space set; and obtaining the first DCI from the first copy and the second copy of the first DCI..

In a third aspect of the present disclosure, an apparatus for enhanced PDCCH reception executable by an apparatus comprises a transceiver and a processor. The transceiver receives repetition of a first DCI and configuration of the repetition of the first DCI. The processor obtains a first copy of the first DCI in a first PDCCH candidate allocated in a first CORESET according to the configuration, and a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET according to the configuration. The first CORESET and the second CORESET are associated with a search space set. The processor obtains the first DCI from the first copy and the second copy of the first DCI.

BRIEF DESCRIPTION OF DRAWINGS

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

FIG. 1 illustrates a transmitter block diagram for a downlink (DL) or uplink (UL) transmission.

FIG. 2 illustrates a receiver block diagram for receiving a DL or UL transmission.

FIG. 3 is a block diagram of a user equipment (UE) and a base station for enhanced PDCCH transmission and reception according to an embodiment of the present disclosure.

FIG. 4 is a flowchart illustrating a method for enhanced PDCCH transmission according to an embodiment of the present disclosure.

FIG. 5 is a block diagram illustrating a system for enhanced PDCCH transmission and reception according to an embodiment of the disclosure.

FIG. 6 is a flowchart illustrating a method for enhanced PDCCH transmission according to an embodiment of the present disclosure.

FIG. 7 is a flowchart illustrating a method for enhanced PDCCH reception according to an embodiment of the present disclosure.

FIG. 8 is a flowchart illustrating a method for enhanced PDCCH reception according to an embodiment of the present disclosure.

FIG. 9 is a block diagram of a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

Fifth-generation (5G) wireless systems are generally a multi-beam based system in a frequency range 2 (FR2) ranging from 24.25 GHz to 52.6 GHz, where multiplex transmit (Tx) and receive (Rx) analog beams are employed by a base station (BS) and/or a user equipment (UE) to combat a large path loss in a high frequency band. In a high frequency band system, for example, mmWave systems, the BS and the UE are deployed with large number of antennas, so that a large gain beamforming can be used to defeat the large path loss and signal blockage. Due to the hardware limitation and cost, the BS and the UE might only be equipped with a limited number of transmission and reception units (TXRUs) . Therefore, hybrid beamforming mechanisms can be utilized in both BS and UE. To get the best link quality between the BS and the UE, the BS and the UE need to align analog beam directions for a particular downlink or uplink transmission. For a downlink transmission, the BS and the UE need to find the best pair of a BS Tx beam and a UE Rx beam while for an uplink transmission, the BS and the UE need to find the best pair of the UE Tx beam and the BS Rx beam.

For a communication between one UE and a BS, the BS and the UE need to determine which Tx and Rx beam are going to be used. When one UE moves, the beams used by the BS and the UE for communication might change. In 3GPP 5G specification, the following functions are defined to support such multi-beam-based operation.

At an operation associated with beam measurement and reporting, in this function, the UE can measure one or multiple Tx beams of the BS and then the UE can select the best Tx beam and report his selection to the BS. By measuring the Tx beams of the BS, the UE can also measure one or more different Rx beams and then select the best Rx beam for one particular Tx beam of the BS. In this function, the gNB can also measure one or multiple Tx beams of the UE and then select the best Tx beam of the UE for an uplink transmission. To support measuring Tx beams of the BS, the BS can transmit multiple reference signal (RS) resources and then configures the UE to measure the RS resources. Then, the UE can report an index of one or more selected RS resources that are selected based on some measure metric, for example, a layer 1 reference signal received power (L1-RSRP) . To support measuring Tx beams of the UE used for an uplink transmission, the BS can configure the UE to transmit one or more uplink RS resources, for example, sounding reference signal (SRS) resources, and then the BS can measure the RS resources. The BS can figure out which Tx beam of the UE is the best for the uplink transmission based on measuring, for example, L1-RSRP of the RS resources.

At an operation associated with beam indication, for a downlink transmission, the BS can indicate the UE of which Tx beam of the BS is used to transmit, so that the UE can use proper Rx beam to receive the downlink transmission. For a physical downlink control channel (PDCCH) transmission, the BS can indicate an identify (ID) of one Tx beam of the BS to the UE. For a physical sidelink discovery channel (PSDCH) transmission, the BS can use downlink control information (DCI) in a PDCCH to indicate the ID of one Tx beam that is used to transmit a corresponding physical downlink shared channel (PDSCH) . For an uplink transmission from the UE, the BS can also indicate the UE of which Tx beam of the UE to be used. For example, for a physical uplink control channel (PUCCH) transmission, the UE uses a Tx beam that is indicated by the BS through a configuration of spatial relation information. For an SRS transmission, the UE uses the Tx beam that is indicated by the BS through the configuration of spatial relation information. For a physical uplink shared channel (PUSCH) transmission, the UE uses a Tx beam that indicated by an information element contained in a scheduling DCI.

At an operation associated with beam switch, this function is used by the BS to switch a Tx beam used for a downlink or uplink transmission. This function is useful when the Tx beam used for transmission currently is out of date due to for example a movement of the UE. When the BS finds a Tx beam currently used for a downlink transmission is not good or the BS finds another Tx beam that is better than the current Tx beam, the BS can send signaling to the UE to inform a change of Tx beam. Similarly, the BS can switch an uplink Tx beam of the UE used to transmit some uplink transmission.

In a communication system, such as a new radio (NR) system, DL signals can include control signaling conveying DCI through a PDCCH, data signals conveying information packet through a PDSCH and some types of reference signals. The DCI can indicate information of how the PDSCH is transmitted, including for example resource allocation and transmission parameters for the PDSCH. The BS can transmit one or more types of reference signals for different purposes, including a demodulation reference symbol (DM-RS) that is transmitted along with the PDSCH and can be used by the UE to demodulate the PDSCH, a channel state information reference signal (CSI-RS) that can be used by the UE to measure BS’s Tx beam or CSI of a downlink channel between the BS and the UE, a phase tracking reference signal (PT-RS) that is also transmitted along with a PDSCH and can be used by the UE to estimate a phase noise caused by imperfection in a radio frequency (RF) part in a transmitter and a receiver and then compensate it when decoding the PDSCH. In NR, DL resource allocation for PDCCH, PDSCH, and reference signals is performed in a unit of orthogonal frequency division multiplexing (OFDM) symbols and a group of physical resource blocks (PRBs) . Each PRB contains a few resource elements (REs) , for example 12 REs, in a frequency domain. A transmission bandwidth (BW) of one downlink transmission consists of frequency resource unit called as resource blocks (RBs) and each RB consists of a few subcarriers or REs, for example, 12 subcarriers or 12 REs.

UL signals transmitted by the UE to the BS can include data signals conveying data packet through a PUSCH, uplink control signals conveying UL control information (UCI) which can be transmitted in the PUSCH or a PUCCH, and UL reference signals. The UCI can carry a schedule request (SR) used by the UE to request an uplink transmission resource, a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback for a PDSCH transmission or a channel state information (CSI) report. The UE can transmit one or more types of uplink reference signals for different purposes, including DM-RS that is transmitted along with a PUSCH transmission and can be used by the BS to demodulate the PUSCH, PT-RS that is also transmitted along with a PUSCH and can be used by the BS to estimate the phase noise caused by imperfection in RF parts and the BS then can compensate it when decoding PUSCH, and SRS signals that are used by the BS to measure one or more UE Tx beams or CSI of the uplink channel between the UE and the BS. Similarly, UL resource allocation for PUSCH, PUCCH, and UL reference signal is also performed in a unit of symbols and a group of PRBs.

A transmission interval for DL or UL channels/signals is referred to as a slot and each slot contains a few, for example 14, symbols in time domain. In a NR system, the duration of one slot can be 1, 0.5, 0.25 or 0.123 millisecond, for the subcarrier spacing 15KHz, 30KHz, 60KHz, and 120 KHz, respectively. NR systems support flexible numerologies and an embodiment can choose proper OFDM subcarrier spacing based on the deployment scenario and service requirement. In the NR system, DL and UL transmission can use different numerologies.

FIG. 1 illustrates a transmitter block diagram for a DL or UL transmission. An embodiment of the transmitter block illustrated in FIG. 1 is for illustration only. Other embodiments could be used without departing from the scope of the present disclosure. Information bits 001 can be first encoded by an encoder 002 such as a low density parity check (LDPC) encoder or polar encoder, and then modulated by a modulator 003. The modulation can be, for example, binary phase-shift keying (BPSK) , quadrature amplitude modulation (QAM) 4, QAM 16, QAM 64, or QAM 256. Then a serial to parallel (S/P) converter 004 can generate parallel multiple modulation symbols that are subsequently inputted to a RE mapper and precoder 005. The RE mapper and precoder 005 can map the modulation symbols to selected REs and then apply some precoder on the modulation symbols on the BW resource assigned to a DL or UL transmission. Then in 006, the modulation symbols are applied with an inverse fast fourier transform (IFFT) and an output thereof is then serialized by a parallel to serial (P/S) converter 007. Then the signals are sent to a Tx unit 008 including for example a digital-to-analog (D/A) convertor, a radio frequency convertor, a filter, a power amplified, and Tx antenna elements, and transmitted out.

FIG. 2 illustrates a receiver block diagram for receiving a DL or UL transmission. An embodiment of the receiver block illustrated in FIG. 2 is for illustration only. Other embodiments could be used without departing from the scope of the present disclosure. Received signals 011 are first passed through a Rx unit 012 including for example Rx antenna elements, a low noise power amplifier, radio frequency converters, and filters. And an output thereof is passed through a P/S 013 and then applied an FFT 014. After converting into a frequency domain, useful signals are extracted by a RE demapping 015 according to a resource allocation for the DL or UL transmission. Subsequently, a demod 016 demodulates data symbols with a channel estimation that is calculated based on DM-RS and then a decoder 017 such as LDPC decoder or polar decoder, decodes the demodulated data to output information bits 018.

In NR 3GPP specification release 15, a UE can be configured with one CORESET, in which a set of time-frequency resource for PDCCH transmission is configured. For one CORESET, the UE can be configured with: a CORESET ID, PDCCH DM-RS scrambling init value, number of OFDM symbols used by that CORESET that defines the time-domain resource for that CORESET and the set of resource blocks that defines the frequency domain resource for that CORESET. The gNB can also configure an antenna quasi co-location (QCL) for the CORESET through higher layer parameter transmission configuration indicator (TCI) -state, which can be used by the UE to monitor the DM-RS for the PDCCH. For monitoring PDCCH, the gNB can configure a search space set for the UE. In one search space set, the gNB can configure the time and frequency location where the UE shall monitor PDCCH transmission. In the configuration of search space set, the gNB can also configure the number of PDCCH candidates and the candidate DCI formats that the UE shall be requested to expect. Through the configuration of one search space set, the gNB can provide the following information to the UE for monitoring PDCCH:

● The index (es) of slots where the PDCCH would be transmitted;

● The time-frequency resources within one slot, in which the PDCCH would be transmitted;

● The number of PDCCH candidates for each CCE aggregation level; and

● The DCI formats that can be transmitted in that PDCCH, for example DCI format 0_0 and DCI format 0_1, or DCI format 1_0 and DCI format 1_1.

FIG. 3 illustrates that, in some embodiments, a user equipment (UE) 10 and a base station 20 for enhanced PDCCH transmission and reception according to an embodiment of the present disclosure are provided. The UE 10 may include a processor 11, a memory 12, and a transceiver 13. The base station 20 may include a processor 21, a memory 22 and a transceiver 23. The

processor

11 or 21 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of radio interface protocol may be implemented in the

processor

11 or 21. The

memory

12 or 22 is operatively coupled with the

processor

11 or 21 and stores a variety of information to operate the

processor

11 or 21. The

transceiver

13 or 23 is operatively coupled with the

processor

11 or 21, and the

transceiver

13 or 23 transmits and/or receives a radio signal.

The

processor

11 or 21 may include an application-specific integrated circuit (ASIC) , other chipsets, logic circuit and/or data processing devices. The

memory

12 or 22 may include a read-only memory (ROM) , a random access memory (RAM) , a flash memory, a memory card, a storage medium and/or other storage devices. The

transceiver

13 or 23 may include baseband circuitry and radio frequency (RF) circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the

memory

12 or 22 and executed by the

processor

11 or 21. The

memory

12 or 22 can be implemented within the

processor

11 or 21 or external to the

processor

11 or 21, in which those can be communicatively coupled to the

processor

11 or 21 via various means are known in the art.

With reference to FIG. 4, in some embodiments, the processor 21 is configured to perform a method 600 for enhance PDCCH transmission. The processor 21 receives configuration of a particular DCI format and configuration of DCI repetition (block 601) . The processor 21 obtains a first DCI for transmission through PDCCH (block 602) and determines a DCI format of the first DCI (block 603) . The processor 21 performs repeated transmission of first DCI through the transceiver 23 (block 604) when the DCI format of the first DCI conforms to the particular DCI format. The processor 21 transmits the first DCI without DCI repetition through the transceiver 23 (block 605) when the DCI format of the first DCI does not conform to the particular DCI format. In the block 604, the processor 21 repeats transmission of first DCI through the transceiver 23 by transmitting a first copy of the first DCI in a first PDCCH candidate allocated in a first CORESET and a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET. The first CORESET and the second CORESET are associated with a first search space set.

In this disclosure, the methods of transmission of PDCCH for enhanced reliability are proposed. In the present disclosure, a ‘beam’ can correspond to an RS resource, which can be a CSI-RS resource, an SRS resource, a synchronization signal/physical broadcast channel (SS/PBCH) block or any other type of RS.

In one embodiment, a UE, such as UE 10, can be configured with a search space set and the search space set is associated with two or more control resource sets. The PDCCH candidates in those different control resource sets associated with the same search space are associated. A gNB, such as the BS 20, can repeat the transmission of a DCI in those linked PDCCH candidates in different CORESETs configured in the same search space. At the UE side, during the PDCCH detection, the UE can be preset with information that one same DCI is repeated in linked PDCCH candidates in those different CORESETs configured in that search space. The technical merit of that proposal is transmit diversity on DCI transmission can be supported in multi-TRP system. We can allocate different CORESETs associated with the same search space to different TRPs in the multi-TRP system. Those TRPs can send the same copy of one DCI in different CORESETs and the UE can combine the signals received from multiple TRPs. When one the link between one TRP and the UE is blocked, the UE can still detect the PDCCH successfully based on the signals received from another TRP.

FIG. 5 illustrates an example of a system for enhanced PDCCH transmission and reception according to an embodiment of the disclosure.

As shown in FIG. 5, a multi-TRP system 100 has two TRPs, TRP-A 101 and TRP-B 102. The TRP-A 101 and TRP-B 102 may be separate base stations, where each of the TRP-A 101 and TRP-B 102 is an embodiment of the BS 20. Alternatively, the TRP-A 101 and TRP-B 102 may be separate radio units that share a common base station, where the common base station is an embodiment of the BS 20. A UE 103 is an embodiment of the UE 10. The base stations may be further connected to a physical core network and/or a core network slice instance of a telecommunication operator. An example of the UE 103 may include the UE 10. DCI X 140 is an example of the first DCI.

In an embodiment of the disclosure, the system 100 may configure a search space set 120 for the UE 103 to monitor PDCCH transmission from both the TRP-A 101 and the TRP-B 102. The system 100 may configure two CORESETs, CORESET-1 121 and CORESET-2 122, for the UE 103. The system 100 may be a BS or a group of BSs capable of NR transmission. Those two CORESETs are associated with a search space set 120 for the UE 103 to monitor PDCCH. The TRP-A 101 and TRP-B 102 can transmit the same DCI X 140 in both

CORESETs

121 and 122 configured in the search space set 120. From the UE perspective, the UE 103 may be preset with information that the same DCI X is repeated, that is transmitted in two copies of the DCI X 140, in a PDCCH candidate 131 in CORESET 121 and a PDCCH candidate 132 in CORESET 122, which are linked through higher layer configuration. The UE 103 may decode

PDCCH candidates

131 and 132 separately and claim successful DCI decoding if a DCI format of the DCI X 140 is decoded correctly from either PDCCH candidates. The UE 103 may also combine the received signals from both

PDCCH candidates

131 and 132 and then try to decode a DCI format of the DCI X 140 based on the combined signals.

In a first method, a UE, such as the UE 103, may be configured with a first CORESET and a second CORESET, such as the

CORESETs

121 and 122. For each of the CORESETs, the following parameters can be configured to the UE:

● A CORESET index p that is used to identify the CORESET;

● A DM-RS scrambling sequence initialization value that is used to generate the reference signal sequence for DM-RS for the CORESET;

● The number of symbols contained in the CORESET, which defines the length of time-domain resources allocated to the CORESET;

● Frequency domain resource allocation for the CORESET, which is a set of resource blocks allocated to the CORESET in a frequency domain;

● A method of mapping control channel element (CCE) to REG (resource element group) ; and

● The quasi-co-location (QCL) configuration for the CORESET.

Each CORESET may be configured with one transmission configuration indicator (TCI) -state that configures one or more reference signal resources that provide reference for various quasi co-location types for the DM-RS of the CORESET.

The UE can be configured with a first search space set. Both the first CORESET and the second CORESET are associated with the first search space set. For the first search space set, the UE can be configured with one or more of the followings:

● An identifier (ID) for the first search space set that is used to identify the first search space set;

● An association between the first search space set and the first CORESET and the second CORESET;

● The PDCCH monitoring configurations, which includes: PDCCH monitoring periodicity of k _s slots and a PDCCH monitoring offset of o _s slots; a PDCCH monitoring pattern within a slot, indicating first symbol (s) of the CORESET within a slot for PDCCH monitoring; a duration of T _s＜k _s slots; and the number of PDCCH candidates

per CCE aggregation level L, where L may be 1, 2, 4, 8 and/or 16;

● The DCI formats that the UE shall use to monitor PDCCH candidates in the first search space set; and

● Applicability of the PDCCH monitoring configurations.

Regarding DCI formats, for example, the UE may be configured to monitor DCI format 0_0 and DCI format 0_1 in the first search space set. Alternatively, for example, the UE can be configured to monitor DCI format 1_0 and DCI format 1_0 in the first search space set. At least one of the DCI formats may be defined as the particular DCI format. The configuration for DCI repetition may include at least a portion of all of the configurations.

Regarding the applicability of the PDCCH monitoring configurations, the UE may be preset with information that the PDCCH monitoring configurations and DCI format configuration configured in the first search space set be applied to both the first CORESET and the second CORESET which are associated with the first search space set. The configuration for DCI repetition may include at least a portion of all of the configurations. The UE may obtain the configuration for DCI repetition through explicit or implicit signaling from the BS.

For the first search space, in a given slot n, the UE can be preset with information that PDCCH candidates in the first CORESET and the second CORESET that starts with the same first symbol in slot n are linked for DCI transmission. The UE can be preset with information that same DCI are transmitted in the linked PDCCH candidates. Particularly for the first search space associated with the first CORESET and the second CORESET, in a given slot

for an active DL bandwidth part (BWP) , for the first CORESET and the second CORESET that has same first symbol, the PDCCH candidate

in the first CORESET configured for aggregation level L and the PDCCH candidate

in the second CORESET for aggregation level L are linked for PDCCH detection and monitoring. The UE may be preset with information that the DCI format carried in the CCEs in the first CORESET for PDCCH candidate

and the DCI format carried in the CCRs in the second CORESET for PDCCH candidate

convey the same content of DCI, such as the DCI X 140.

An example of a gNB 500 transmitting a DCI 501 with DCI repetition in the PDCCH of the first search space is shown in FIG. 6. Embodiments of gNB 500 may include one or more of the TRP 101, and TRP 102 in the system 100. DCI 501, such as DCI X 140, is first attached with CRC bits at stage 502 that can be used by a receiver UE, such as UE 103, to detect PDCCH transmission error. Then the CRC is scrambled at stage 503. The UE’s RNTI 531 is used to scramble the CRC part of that DCI 501. Then the DCI 501 is encoded at stage 504, for example, through polar encoding. After encoding, the gNB 500 can perform rate matching on coded bits of DCI 501 separately for resources in the first CORESET and the second CORESET. As shown in FIG. 6, the rate matching is performed on coded bits of DCI 501 at stage 511 for the resources in the first CORESET and the rate matching is performed on coded bits of DCI 501 at stage 521 for the resources in the second CORESET. Then the output bits of the rate matching are scrambled with the sequence configured in each CORESET at

stages

512 and 522. The output bits of the scrambling are modulated to QPSK symbols at

stages

513 and 523. Finally, the gNB 500 may map the modulated symbols and corresponding DM-RS signals to resources in the first CORESET at stage 514 and map the modulated symbols and corresponding DM-RS signals to resources in the second CORESET at stage 524.

In the first method, the linked PDCCH candidate for sending repeated DCI in those two CORESETs have the same starting symbol and also the same aggregation level. The advantage of the first method is the simplicity of the configuration and implementation of the UE side. However, one disadvantage of the first method is the limited flexibility. In the first method, the DCI repetition sent by different TRPs have to be sent with the same CCE aggregation level. In some scenarios, different TRPs might use different aggregation level for sending the same DCI due to different channel quality and condition between the TRPs and the UE.

In a second method, a UE can be configured with a first CORESET and a second CORESET. For each of the CORESETs, the following parameters can be configured to the UE:

● A CORESET index p that is used to identify one CORESET;

● Frequency domain resource allocation for the CORESET, which defines a set of resource blocks;

● The method of mapping CCE to REG (resource element group) ; and

● The QCL configuration for the CORESET, where each CORESET can be configured with one TCI-state that configures one or more reference signal resources that provide reference for various quasi co-location types for the DM-RS of CORESET.

With reference to FIG. 7, in some embodiments, the processor 11 is configured to perform a method 610 for enhance PDCCH reception. The processor 11 obtains configuration of the repetition of the first DCI, for example, through the transceiver 13 (block 611) . The configuration of the repetition of the first DCI includes configuration of the particular DCI format. The processor 11 receives PDCCH transmission which includes repetition of the first DCI through the transceiver 13 (block 612) and determines a DCI format of the first DCI (block 613) . The processor 11 obtains the first DCI from the first copy and the second copy of the first DCI when the DCI format of the first DCI conforms to the particular DCI format (block 614) . The processor 11 obtains the first DCI without DCI repetition when the DCI format of the first DCI does not conform to the particular DCI format (block 615) .

With reference to FIG. 8, the processor 11 is configured to perform a method 620 including blocks 621 to 624 which reveal more details of the block 614. The processor 11 obtains the first copy of the first DCI in the first PDCCH candidate allocated in the first control resource set (CORESET) according to the configuration (block 622) , and obtains the second copy of the first DCI in the second PDCCH candidate allocated in the second CORESET according to the configuration (block 623) . The first CORESET and the second CORESET are associated with the first search space set. The processor 11 receives repetition of the first DCI (block 624) and obtains the first DCI from the first copy and the second copy of the first DCI (block 625) .

The UE can be configured with a first search space set and both the first CORESET and the second CORESET are associated with the first search space set. In the configuration of the first search space set, separately for the PDCCH monitoring in the first CORESET and in the second CORESET, the UE can be configured with (1) PDCCH monitoring pattern in one slot, i.e., the first symbol (s) of the CORESETs within a slot; (2) the number of PDCCH candidates for one aggregation level of the CORESETs. The UE can also be configured with the link between a PDCCH candidate in the first CORESET and a PDCCH candidate in the second CORESET for monitoring PDCCH repetition. In an embodiment of the invention, for the first search space set, the UE can be configured with one or more of the followings:

● The ID for the first search space set that is used to identify the first search space set;

● The slot location for monitoring PDDCH, which may be indicated by a PDCCH monitoring periodicity of k _s slots and a PDCCH monitoring offset of o _s slots;

● a duration of T _s＜k _s slots indicating a number of slots in which the first search space set exists; and

● association between the first CORESET and the second CORESET within a slot.

For the first CORESET, the UE can be configured with:

● PDCCH monitoring pattern within a slot, indicating first symbol (s) of the first CORESET within a slot for PDCCH monitoring; and

● A number of PDCCH candidates for each CCE aggregation level L for the first CORESET, which may be for example, 1, 2, 4, 8, or 16.

For the second CORESET, the UE may be configured with:

● PDCCH monitoring pattern within a slot, indicating first symbol (s) of the second CORESET within a slot for PDCCH monitoring; and

● A number of PDCCH candidates for each CCE aggregation level L for the second CORESET, which may be for example, 1, 2, 4, 8, or 16.

For the first search space set, the UE may be further configured with the association between the first CORESET and the second CORESET within a slot. For example, the association between the first CORESET and the second CORESET represents that the PDCCH monitoring indicated by first symbol a of the first CORESET is associated with the PDCCH monitoring indicated by first symbol b of the second CORESET. The configuration for DCI repetition may include at least a portion of all of the configurations.

In an embodiment of the invention, one first symbol is indicated for the first CORESET and one first symbol is indicated for the second CORESET within a slot. PDCCH monitoring in the first CORESET and PDCCH monitoring in the second CORESET in the same slot may be thus associated using the first symbols. The configuration for DCI repetition may include at least a portion of all of the configurations.

In an embodiment of the invention, more than one first symbols may be configured for the first CORESET within a slot, and one or more than one first symbols may be configured for the second CORESET within a slot. Each first symbol of the second CORESET may be associated with one first symbol of the first CORESET within the same slot. The UE may be preset with information that the PDCCH monitoring in the first CORESET and the second CORESET are linked through the associated first symbols. The configuration for DCI repetition may include at least a portion of all of the configurations.

In an embodiment of the invention, one or more starting symbol locations for the first CORESET within a slot are configured, and one or more starting symbol locations for the second CORESET within a slot are configured. Within one slot, the association between one PDCCH monitoring occasion of the first CORESET and one PDCCH monitoring occasion of the second CORESET may be configured based on the one or more starting symbol locations. The configuration for DCI repetition may include at least a portion of all of the configurations.

For example, two PDCCH monitoring occasions for the first CORESET within one slot and one PDCCH monitoring occasion for the second CORESET within one slot may be configured. The first PDCCH monitoring occasion of the second CORESET may be cross associated with the second PDCCH monitoring occasion of the first CORESET. This association between the PDCCH monitoring occasions of the first CORESET and the second CORESET may be used by the gNB to transmit repeated DCI and used by the UE to determine where the repeated DCI are transmitted.

In an embodiment of the invention, the first symbol (s) for the first CORESET within a slot is configured through a bitmap a0 a1 …aN in which each bit indicates one starting symbol for PDCCH monitoring occasion of the first CORESET. And the first symbol (s) for the second CORESET within a slot is configured through another bitmap b0 b1 …bN in which each bit indicates one starting symbol for PDCCH monitoring occasion of the second CORESET. The UE may be configured with a third bitmap c0 c1 …cN that is used to indicate the association between the PDCCH monitoring of the second CORESET and the PDCCH monitoring of the first CORESET.

An example is given with N = 13. For the first CORESET, a0 a1 … aN =10000001000000 and b0 b1 … bN =01000000000000. Two PDCCH monitoring within one slot are configured for the first CORESET and one PDCCH monitoring within one slot are configured for the second CORESET. The UE may also be configured with c0 c1 … cN =10 which indicates that the PDCCH monitoring of the second CORESET is associated with the PDCCH monitoring of the first CORESET within one slot.

The UE may be configured with the link between PDCCH candidates in PDCCH monitoring of the first CORESET and the second CORESET. The UE may be preset with information that the same DCI is repeated in the linked PDCCH candidates in the associated PDCCH monitoring occasions in the first CORESET and the second CORESET. The gNB may repeat one DCI transmission in two linked PDCCH candidates of the first CORESET and the second CORESET. And the UE may be preset with information that one same DCI may be repeated in the linked PDCCH candidates of the first CORESET and the second CORESET. The configuration for DCI repetition may include at least a portion of all of the configurations.

In a first example, the UE may be preset with information that the PDCCH candidates in the first CORESET and the second CORESET are linked for the same CCE aggregation level. The UE may be preset with information that one PDCCH candidate in the first CORESET for CCE aggregation level L is linked with one PDCCH candidate in the second CORESET for CCE aggregation level L, where L may be 1, 2, 4, 8, or 16. In an example with a CCE aggregation level L, the number of PDCCH candidates in the first CORESET is set to be

and the number of PDCCH candidates in the second CORESET is set to be

Then for CCE aggregation level L, PDCCH candidate m _s in the second CORESET of the first search space set is linked with PDCCH candidate m _s in the first CORESET of the first search space set, where

The

is a function which outputs the minimum among the inputs

and

In another example, the UE may be preset with information that, for CCE aggregation level L, PDCCH candidate m _s in the second CORESET of the first search space set is linked with PDCCH candidate

in the first CORESET of the first search space set, where

The

is a function of m _s+Δ modulo

The Δ is a PDCCH candidate index offset that may take values for example, 0, 1, -1, 2, -2, 3, -3, or other integers. The configuration for DCI repetition may include at least a portion of all of the configurations.

In an embodiment of the invention, the first CORESET may be configured as the primary CORESET in the first search space set. However, the second CORESET may be configured as secondary CORESET in the first search space set, which is used to provide DCI repetition for the DCI transmission in the first CORESET. The number of PDCCH monitoring occasions of the second CORESET within a slot shall not be greater than the number of PDCCH monitoring occasions of the first CORESET. The number of PDCCH candidates of the second CORESET shall not be greater than the number of PDCCH candidates of the first CORESET.

In a second example, one PDCCH candidate of the first CORESET for aggregation level L1 may be linked with one PDCCH candidate of the second CORESET for aggregation level L2. Here the CCE aggregation level L1 and the CCE aggregation level L2 may be same or different. The advantage of this example is different TRPs have flexibility to use different CCE aggregation level for transmitting the same DCI. The path loss between transmission paths from the UE to different TRPs are generally different, therefore the TRPs may use different CCE level to transmit the same DCI to that UE. The configuration for DCI repetition may include at least a portion of all of the configurations.

In a third example, in the configuration of the first search space set, the UE is configured with

PDCCH candidates in the first CORESET for CCE aggregation level L1 and the UE is configured with

PDCCH candidates in the second CORESET for CCE aggregation level L2. In the configuration of the first search space set for the UE, one PDCCH candidate of CCE aggregation level L1 of the first CORESET is linked with one PDCCH candidate of CCE aggregation level L2 of the second CORESET, which is configured to the UE. Then the UE may be preset with information that PDCCH candidate m _s of CCE aggregation level L2 in the second CORESET is linked with the PDCCH candidate m _s of CCE aggregation level L1 in the first CORESET in the first search space set. In another example, the UE may be preset with information that PDCCH candidate m _s of CCE aggregation level L2 in the second CORESET is linked with the PDCCH candidate

of CCE aggregation level L1 in the first CORESET in the first search space set. The configuration for DCI repetition may include at least a portion of all of the configurations.

Table 1 illustrates a computer executable program example for configuring search space set associated with two CORESETs for DCI repetition according to the disclosure.

Table 1

In one method, a UE may be requested to be preset with information that only one particular DCI format may be repeated in the first CORESET and the second CORESET associated with the first search space set. This method is beneficial for reducing UE implementation complexity. Another technical motivation for this method is DCI repetition is generally useful for ultra-reliable low-latency communication (URLLC) service, and the PDSCH transmission carrying URLLC service may be scheduled by the particular DCI format. Therefore, it is sufficient for the UE to only monitor the particular DCI format for DCI repetition.

In the configuration of the first search space set, the UE may be configured with a higher layer parameter that indicates the DCI formats without DCI repetition that the UE shall expect to decode in the PDCCH candidates in the first CORESET, and the UE may also be configured with another higher layer parameter that indicates the DCI format (s) with DCI repetition that the UE may expect to decode in linked PDCCH candidates in both the first CORESET and the second CORESET.

A multi-TRP system according to an embodiment of the invention may repeat the transmission of one same DCI from multiple TRPs to a single UE. Transmit diversity of PDCCH from multiple TRP is achieved and thus the reliability of PDCCH transmission is boosted. One important use case for multi-TRP system according to an embodiment of the invention is URLLC services that impose ultra-tight requirements on the performance of both PDCCH and PDSCH channels.

FIG. 9 is a block diagram of a system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. For example, each of the UE 10 and the UE 103 may be realized as the system 700. FIG. 9 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, an application circuitry 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other at least as illustrated.

The application circuitry 730 may include a circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

The baseband circuitry 720 may include a circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the user equipment, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitry, the baseband circuitry, and/or the application circuitry. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC) , an electronic circuit, a processor (shared, dedicated, or group) , and/or a memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the application circuitry, and/or the memory/storage may be implemented together on a system on a chip (SOC) .

The memory/storage 740 may be used to load and store data and/or instructions, for example, for system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) ) , and/or non-volatile memory, such as flash memory. In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, system may have more or less components, and/or different architectures. Where appropriate, methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

In the embodiment of the present disclosure, an apparatus and a method for enhanced PDCCH transmission capable of providing high reliability are provided. The embodiment of the present disclosure is a combination of techniques/processes that may be adopted in 3GPP specification to create an end product.

A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized with other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated in another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms.

The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments can be integrated in one processing unit, physically independent, or integrated in one processing unit with two or more than two units.

If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method for enhanced physical downlink control channel (PDCCH) transmission executable by an apparatus, comprising: repeating transmission of first downlink control information (DCI) by transmitting a first copy of the first DCI in a first PDCCH candidate allocated in a first control resource set (CORESET) and a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET, wherein the first CORESET and the second CORESET are associated with a first search space set.
The method of claim 1, further comprising:

receiving configuration of a particular DCI format;

determining a DCI format of the first DCI; and

performing the repeating transmission of first DCI when the DCI format of the first DCI conforms to the particular DCI format.
The method of claim 1, further comprising being configured with a first association between the first copy and the second copy of the first DCI, wherein the first association represents that the first copy in a first control channel element (CCE) aggregation level for detecting the first PDCCH candidate in the first CORESET transmitted from a first transmission reception point (TRP) is associated with the second copy in a second CCE aggregation level for detecting the second PDCCH candidate in the second CORESET transmitted from a second TRP.
The method of any one of claims 1 and 3, further comprising being configured with a second association between the first PDCCH candidate and the second PDCCH candidate, wherein the second association represents that the first PDCCH candidate in a first CCE aggregation level L ₁ is associated with the second PDCCH candidate in a second CCE aggregation level L ₂, and the L ₁ is identical to the L ₂.
The method of claim 4, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the first PDCCH candidate is indexed as PDCCH candidatem _s in the CCE aggregation level L ₁ in the first CORESET, the second association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate m _s of CCE aggregation level L ₁ in the first CORESET, the
is a function of m _s+Δ modulo
and the Δ is a PDCCH candidate index offset.
The method of claim 4, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the first PDCCH candidate is indexed as PDCCH candidate

in the CCE aggregation level L ₁ in the first CORESET, the second association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate
of CCE aggregation level L ₁ in the first CORESET, the
is a function of (m _s+Δ) modulo
and the Δ is a PDCCH candidate index offset.
The method of any one of claims 1, 3, and 4, further comprising being configured with a third association between the first PDCCH candidate and the second PDCCH candidate, wherein the third association represents that the first PDCCH candidate in a first control channel element (CCE) aggregation level L ₁ is associated with the second PDCCH candidate in a second CCE aggregation level L ₂, and the L ₁ is different from the L ₂.
The method of claim 7, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the third PDCCH candidate is indexed as PDCCH candidatem _s in the CCE aggregation level L ₁ in the first CORESET, the third association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate m _s of CCE aggregation level L ₁ in the first CORESET, the
is a function of m _s+Δ modulo
and the Δ is a PDCCH candidate index offset.
The method of claim 7, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the first PDCCH candidate is indexed as PDCCH candidate

in the CCE aggregation level L ₁ in the first CORESET, the third association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate
of CCE aggregation level L ₁ in the first CORESET, the
is a function of (m _s+Δ) modulo
and the Δ is a PDCCH candidate index offset.
The method of any one of claims 1, 3, 4, and 7, further comprising being configured with a fourth association between the first CORESET and the second CORESET, wherein the fourth association represents that a first symbol of the first CORESET is associated with a first symbol of the second CORESET.
A method for enhanced physical downlink control channel (PDCCH) reception executable by an apparatus, comprising: receiving repetition of a first downlink control information (DCI) and configuration of the repetition of the first DCI;

obtaining a first copy of the first DCI in a first PDCCH candidate allocated in a first control resource set (CORESET) according to the configuration;

obtaining a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET according to the configuration, wherein the first CORESET and the second CORESET are associated with a first search space set; and

obtaining the first DCI from the first copy and the second copy of the first DCI.
The method of claim 11, further comprising:

receiving configuration of a particular DCI format;

determining a DCI format of the first DCI; and

obtaining the first DCI from the first copy and the second copy of the first DCI when the DCI format of the first DCI conforms to the particular DCI format.
The method of claim 11, further comprising being configured with a first association between the first copy and the second copy of the first DCI, wherein the first association represents that the first copy in a first control channel element (CCE) aggregation level for detecting the first PDCCH candidate in the first CORESET transmitted from a first transmission reception point (TRP) is associated with the second copy in a second CCE aggregation level for detecting the second PDCCH candidate in the second CORESET transmitted from a second TRP.
The method of any one of claims 11 and 13, further comprising being configured with a second association between the first PDCCH candidate and the second PDCCH candidate, wherein the second association represents that the first PDCCH candidate in a first CCE aggregation level L ₁ is associated with the second PDCCH candidate in a second CCE aggregation level L ₂, and the L ₁ is identical to the L ₂.
The method of claim 14, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the first PDCCH candidate is indexed as PDCCH candidate

in the CCE aggregation level L ₁ in the first CORESET, the second association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate
of CCE aggregation level L ₁ in the first CORESET, the
is a function of (m _s+Δ) modulo
and the Δ is a PDCCH candidate index offset.
The method of any one of claims 11, 13, and 14, further comprising being configured with a third association between the first PDCCH candidate and the second PDCCH candidate, wherein the third association represents that the first PDCCH candidate in a first control channel element (CCE) aggregation level L ₁ is associated with the second PDCCH candidate in a second CCE aggregation level L ₂, and the L ₁ is different from the L ₂.
The method of claim 16, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the third PDCCH candidate is indexed as PDCCH candidatem _s in the CCE aggregation level L ₁ in the first CORESET, the third association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate m _s of CCE aggregation level L ₁ in the first CORESET, the
is a function of m _s+Δ modulo
and the Δ is a PDCCH candidate index offset.
The method of claim 16, wherein the second PDCCH candidate is indexed as PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET, the first PDCCH candidate is indexed as PDCCH candidate

in the CCE aggregation level L ₁ in the first CORESET, the third association represents that PDCCH candidate m _s in the CCE aggregation level L ₂ in the second CORESET is linked with the PDCCH candidate
of CCE aggregation level L ₁ in the first CORESET, the
is a function of (m _s+Δ) modulo
and the Δ is a PDCCH candidate index offset.
The method of any one of claims 11, 13, 14, and 16, further comprising being configured with a fourth association between the first CORESET and the second CORESET, wherein the fourth association represents that a first symbol of the first CORESET is associated with a first symbol of the second CORESET.
An apparatus for enhanced physical downlink control channel (PDCCH) reception executable by an apparatus, comprising:

a transceiver configured for receiving repetition of a first downlink control information (DCI) and configuration of the repetition of the first DCI; and

a processor configured for obtaining a first copy of the first DCI in a first PDCCH candidate allocated in a first control resource set (CORESET) according to the configuration, and obtaining a second copy of the first DCI in a second PDCCH candidate allocated in a second CORESET according to the configuration, wherein the first CORESET and the second CORESET are associated with a first search space set;

wherein the processor obtains the first DCI from the first copy and the second copy of the first DCI.