WO2021056264A1

WO2021056264A1 - Dai scheme for joint ack/nack feedback in multi-trp/panel transmission

Info

Publication number: WO2021056264A1
Application number: PCT/CN2019/107843
Authority: WO
Inventors: Yi Zhang; Keeth Saliya Jayasinghe LADDU
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-09-25
Filing date: 2019-09-25
Publication date: 2021-04-01
Also published as: CN114503720A

Abstract

In accordance with some embodiments, an apparatus comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs), wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI). The apparatus further transmits at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

Description

DAI SCHEME FOR JOINT ACK/NACK FEEDBACK IN MULTI-TRP/PANEL TRANSMISSION

BACKGROUND: Field:

Certain embodiments may relate to communication systems. For example, some embodiments may relate to multi-transmission receive point (TRP) /panel transmissions.

Description of the Related Art:

Under 3rd Generation Partnership Project (3GPP) , release 16 (Rel-16) work item (WI) includes enhancements on multiple input multiple output (MIMO) . Multi-TRP/panel transmissions are considered an important part of NR deployments due to their benefits to enhanced mobile broadband (eMBB) operations, as well as the capability to improve the reliability of ultra-reliable low-latency communication (URLLC) services. For example, the WI related to MIMO enhancements notes that enhancements on multi-TRP/panel transmission including improved reliability and robustness with both ideal and non-ideal backhaul. These enhancements may include specifying downlink control signaling enhancements for efficient support of non-coherent joint transmission, as well as enhancements on uplink control signaling and/or reference signal (s) for non-coherent joint transmissions.

SUMMARY:

In accordance with some embodiments, a method may include configuring, by a user equipment, a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further include transmitting, by the network entity, at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, an apparatus may include means for configuring a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The apparatus may further include means for transmitting at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, an apparatus may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The at least one memory and the computer program code may be further configured to, with the at least one processor, cause the apparatus to at least transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, a non-transitory computer readable medium may be encoded with instructions that may, when executed in hardware, perform a method. The method may configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, a computer program product may perform a method. The method may configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, an apparatus may include circuitry configured to configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The circuitry may further transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.

In accordance with some embodiments, a method may include receiving, by a user equipment, at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further include detecting, by the user equipment, at least one missing detected PDCCH. The method may further include determining, by the user equipment, at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

In accordance with some embodiments, an apparatus may include means for receiving at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The apparatus may further include means for detecting at least one missing detected PDCCH. The apparatus may further include means for determining at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

In accordance with some embodiments, an apparatus may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least receive at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The at least one memory and the computer program code may be further configured to, with the at least one processor, cause the apparatus to at least detect at least one missing detected PDCCH. The at least one memory and the computer program code may be further configured to, with the at least one processor, cause the apparatus to at least determine at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

In accordance with some embodiments, a non-transitory computer readable medium may be encoded with instructions that may, when executed in hardware, perform a method. The method may receive at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further detect at least one missing detected PDCCH. The method may further determine at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

In accordance with some embodiments, a computer program product may perform a method. The method may receive at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The method may further detect at least one missing detected PDCCH. The method may further determine at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

In accordance with some embodiments, an apparatus may include circuitry configured to receive at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) . The circuitry may further detect at least one missing detected PDCCH. The circuitry may further determine at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.

BRIEF DESCRIPTION OF THE DRAWINGS:

For proper understanding of this disclosure, reference should be made to the accompanying drawings, wherein:

FIG. 1 illustrates an example of PDCCH scheduling transmissions of NR-PDSCH from various TRPs.

FIG. 2 illustrates an example of separate counting for multiple TRP transmissions.

FIG. 3 illustrates an example of no detection ability where burst PDCCH is missing due to being blocked by a TRP.

FIG. 4 illustrates an example of an optimized scheme based on local/joint counting and high layer signaling for reference TRP according to some embodiments.

FIG. 5 illustrates another example of an optimized scheme based on joint counting and high layer signaling for counting order between TRP according to some embodiments.

FIG. 6 illustrates a signaling diagram according to certain embodiments.

FIG. 7 illustrates an example of a method performed by a network entity according to certain embodiments.

FIG. 8 illustrates an example of a method performed by a user equipment according to certain embodiments.

FIG. 9 illustrates an example of a system according to certain embodiments.

DETAILED DESCRIPTION:

During 3GPP radio access network (RAN) work group (WG) 1, two techniques were agreed to support multi-TRP transmissions in NR, specifically, single PDCCH-design and multiple PDCCH-design. Single PDCCH schedules one DPSCH where separate layers are transmitted from separate TRPs, while multiple PDCCHs each schedule a respective PDSCH where each NR-PDSCH is transmitted from a separate TRP. In the multiple PDCCH design, multiple PDCCHs from multiple TRPs may schedule respective multiple PDSCHs. The transmission of multiple PDCCHs may occur independently from two TRPs. Thus, this may be used for both ideal and non-ideal backhauls.

3GPP RAN1 97 meeting resulted in an agreement that joint HARQ-ACK feedback for multiple DCI may be supported, and both type-1 and type-2 HARQ-ACK codebooks may be supported. In particular, for separate ACK/NACK feedback for PDSCHs received from different TRPs, the UE should be able to generate separate ACK/NACK codebooks identified by an index, if the index is configured and applied across all CCs. In addition, joint HARQ-ACK feedback may be supported for PDSCHs received from different TRPs where multiple DCIs are used. When the PUCCH resources are on the different PDCCH monitoring occasions, which are indicated by PDSCH-to-HARQ feedback timing indicator fields of multiple DCIs for different TRPs, both type-1 and type-2 HARQ-ACK codebooks are supported.

Furthermore, for multiple PDCCH-based multiple TRP transmissions, one CORESET in a “PDCCH-config” may correspond with one TRP. Following 3GPP RAN1 96 and RAN1 97, in order to support multiple-PDCCH based multi-TRP/panel transmissions with intra-cell (i.e., same cell ID) one CORESET in a “PDCCH-config” corresponds to one TRP in order to link multiple PDCCH/PDSCH pairs with multiple TRPs.

Additionally, for multi-PDCCH based multi-TRP operations, the maximum number of CORESETs per “PDCCH-config” may be increased to 5. This TRP differentiation may be used for enhanced DAI indication for join ACK/NACK feedback in the event of multiple TRP transmission with multiple DCI.

According to the Rel-15 DAI indicating scheme, a dynamic codebook, such as a type II codebook, may reduce a codebook size relative to semi-static codebooks, and may be an improvement for no errors in the downlink control signaling. However, in the presence of missing detection of downlink control signaling, the NE and UE may interpret codebook sizes differently, and furthermore may further result in a corrupted feedback report for, at least, the missing downlink controls signaling. For example, the UE may be scheduled for downlink transmissions in two subsequent PDCCH monitoring occasions, but missed the first PDCCH, and as a result, the UE may transmit an acknowledgement only for the PDSCH scheduled by the second PDCCH monitoring occasion. In contrast, the NE may attempt to receive acknowledgements for two PDCCH monitoring occasions and mismatch happens. To respond to these errors, the downlink assignment index (DAI) may be used in the downlink DCI. The DAI field may be further split into two parts, a counter DAI (cDAI) and an optional total DAI (tDAI) for carrier aggregations. The counter DAI included in the DCI may indicate the number of current scheduled downlink transmissions, where DCI is sorted in a carrier first, and then time. The total DAI included in the DAI included in the DCI may indicate the total number of downlink transmissions across all carrier up to the current PDCCH monitoring occasion.

As defined in 3GPP technical specification (TS) 38.212 Rel-15, for DCI format 1-0, the downlink assignment index may be 2 bits as defined in subclause 9.1.3 of TS 38.213. And for DCI format 1-1, the number of bits of the downlink assignment index may be 4 bits if more than one serving cell are configured in the DL and the higher layer parameter pdsch-HARQ-ACK-Codebook=dynamic, where the 2 MSB bits are the counter DAI and the 2 LSB bits are the total DAI, and 2 bits if only one serving cell is configured in the DL and the higher layer parameter pdsch-HARQ-ACK-Codebook=dynamic, where the 2 bits are the counter DAI.

For a non-coherent joint transmission (NCJT) , the PDSCH may be transmitted from multiple TRP with multiple PDCCH scheduling. The ACK/NACK bits may be jointly returned for ideal backhaul or non-ideal backhaul with small latency. HARQ-ACK bit number of dynamic HARQ-ACK codebook may be determined based on actual PDSCH from carriers as well as PDCCHs missing. However, 3GPP Rel-15 DAI indication schemes are insufficient to correct missing PDCCHs, where PDCCHs may originate from multiple TRPs. An extension scheme may be added to 3GPP Rel-15 independently for each TRP, but not without some disadvantages. For example, such as extension scheme would not provide cross-checking abilities between TRPs for missing PDCCHs. For example, as shown in FIG. 2, cDAI information in PDCCH from TRP2 would be unable to support detection of missing PDCCH from TRP1.

In addition, there is no ability to identify the last several missing PDCCHs. The number of undetected missing PDCCHs would be increased due to an increased number of TRPs. Referring again to FIG. 2, if the second PDCCH from TRP1 is missed by the UE, it may be detected since the UE could receive cDAI information from the received third PDCCH received from TRP1. However, the UE would be unable to detect the missing of the fourth PDCCH from TRP1, as well as the third or fourth PDCCH from TRP2, since they are the last PDCCH and there is no DAI information which may be used for reference. For multiple TRP transmissions, the last PDCCH is from multiple TRP views, increasing the number of PDCCH missing detections.

However, a DAI indication scheme with joint PDCCH counting from multiple TRPs may be used to solve the above-described disadvantages since this includes cross-check capabilities for the detection of missing PDCCHs, as well as only one “last” DCI from joint HARQ-ACK codebook views. The DAI from PDCCH with improved channel quality may also provide missing checks for PDCCH with worse channel quality.

For multiple TRP transmission, one scenario in frequency range 2 (FR2) occurs where PDCCH bursts may be missing from one TRP due to blocking. Due to the limit of granularity caused by 2-bit DAI indications, there is no ability for detecting 4 consecutive missing PDCCHs. As illustrated in FIG. 3, PDCCH scheduling 4 CCs from one TRP may be missed due to blocking, and the UE is unaware there is PDCCH transmissions according to current Rel-15 DAI design schemes. Thus, a special design which exploits the counting information from another TRP may be used to provide the detection ability for burst PDCCH loss.

Under the current 3GPP Rel-15 DAI scheme, 2 bits are used for non-CA cases, while 4 bits are used for CA cases. For multiple TRP transmission, there is not definition on how many bits are used for non-CA cases. PDCCH reliability may be enhanced with smaller DAI bit number, while the detection ability for missing PDCCHs may be enhanced with more DAI bits, such as 4 bits. For joint HARQ-ACK with multiple PDCCH from multiple TRP, the counted PDCCH numbers for indicating DAI may be increased because of multiple TRP. Thus, an enhanced scheme which balances missing PDCCH detection ability with DAI signaling overhead is desired, where the channel quality difference between TRP may be exploited. The high layer signaling may then be used to switch the 2 bits and 4 bits DAI signaling scheme based on channel quality.

Certain embodiments described herein may provide a DAI-enhanced scheme, achieving an improvement between signaling overhead and the ability to detect missing PDCCH with 2-bit DAI for non-CA scenarios. In addition, the PDCCH missing detection ability may be improved for a CA case, or for non-CA with 4-bits, DAI case for joint ACK/NACK feedback with multiple DCI transmissions from multiple TRPs. Certain embodiments are, therefore, directed to improvements in computer-related technology, specifically, enabling DAI indications to guarantee the same understanding of HARQ-ACK codebook size between network entity and user equipment. Certain embodiments may further conserve network resources and reduce power consumption of network entities and/or user equipment located within the network by reducing redundant operations.

FIG. 6 illustrates an example of a signalling diagram according to some embodiments. Network entity (NE) 620 may be similar to NE 910 in FIG. 9, and user equipment (UE) 630 may be similar to UE 920 in FIG. 9. Although only a single UE and a single NE are illustrated, a communications network may contain one or more of each of these entities.

In step 601, NE 620 may determine whether at least one carrier aggregation is configured. For example, upon determining that no CA is configured, NE 620 may be configured to configure

bit number

2 or 4 for DAI according to, for example, channel quality. In various embodiments, NE 620 may be configured to configure 4-bit DAI for at least one cell edge user in response to at least one missing PDCCH detection ability of NE 620 exceeding at least one performance threshold. Additionally or alternatively, UE 630 may be configured to configure 2-bit DAI for at least one cell center user in response to at least one probability of PDCCH missing falling below at least one predetermined threshold.

In step 603, NE 620 may determine whether at least one DAI bit number is configured. For example, the at least one DAI bit number may be configured as at least one fixed predetermined value. For example, at least one tDAI is required for each of the at least one DAI bit number, the at least one DAI bit number may be configured with at least one 4 bits. In step 605, NE 620 may determine DAI with modulus 4 operation, for example, according to cDAI and/or tDAI. In certain embodiments, upon NE 620 determining that no DAI bit number is configured, or that DAI bit number is configured as 2 bits, NE 620 may determine DAI with modulus 4 operation based upon global or local counting with configured order for PDCCH in the same PDCCH monitoring occasion from different TRPs. For example, each PDCCH may only include 2 bits for indicating PDCCH counting index, i.e., cDAI.

In some embodiments, NE 620 may configured at least one reference TRP index associating with higher-layer signalling. For example, NE 620 may select at least one reference TRP with channel quality exceeding at least one predetermined threshold configured to improve detection of missing PDCCH by NE 620. NE 620 may determine channel quality based upon at least one L3-RSRP measurement result. For each PDCCH from at least one different TRP in at least one PDCCH monitoring occasion, at least one PDCCH from the at least one TRP is deferred for counting. For example, DAI may be determined, in part, based on at least one cumulative PDCCH number, wherein the actual index may be related with a counting sequence. Thus, a PDCCH received from a TRP associated with a lower channel quality may be counted before a TRP associated with a higher channel quality. In some embodiments, local counting may be used for a first TRP with a lower channel quality, and global counting may be used for a second TRP with a higher channel quality.

As illustrated in FIG. 4, TRP2 may be a reference TRP based upon channel quality exceeding at least one predetermined threshold. In various embodiments, within at least one PDCCH monitoring occasion, at least one PDCCH from TRP2 may be counted after the at least one PDCCH is received from TRP1. For example, if PDCCH with cDAI=7 is missing, UE 630 may not know whether there is an actual PDCCH transmission since it is the last PDCCH. In response, when PDCCH with cDAI=7 comes from reference TRP with channel condition exceeding at least one predetermined threshold, this may lower the probability for PDCCH missing below at least one predetermined threshold.

In certain embodiments, NE 620 may count at least one PDCCH. For example, at least one local index may be used for DAI with TRP-specific separate PDCCH counting for at least one other TRP, for example, at least one TRP other than the reference TRP. Additionally or alternatively, the global index may be configured to for DAI with joint PDCCH counting for reference TRP. As a result, this may provide missing detection ability exceeding at least one predetermined threshold configured to assist of DAI of reference TRP. Furthermore, as illustrated in FIG. 4, when UE 630 does not receive PDCCH with cDAI=6/3 but receives PDCCH with cDAI=5 and cDAI=7, UE 630 may be configured to know that PDCCH with cDAI=6/3 is missing, and that there is no problem for determining at least one HARQ-ACK codebook size.

In some embodiments, at least one DAI indication bit may be determined based upon at least one counter DAI with modulo operation for 4 on account of 2-bit indication. In some embodiments, NE 620 may configure, for UE 630, at least one counting order for PDCCH in at least one PDCCH monitoring occasion from at least one different TRP associated with at least one higher-lever signaling. In some embodiments, local counting may be used for a first TRP with a lower channel quality, and global counting may be used for a second TRP with a higher channel quality.

For example, PDCCH from at least one TRP with channel quality above at least one predetermined threshold may be counted later than at least one PDCCH from at least one TRP with a channel quality below the at least one predetermined quality in order to better detect at least one missing PDCCH

In certain embodiments, channel quality may be determined based on at least one L3-RSRP measurement result. For at least one PDCCH from at least one different CORESET group, the counting order may be sorted according to at least one channel quality, for example, PDCCH from TRP with improved channel may be deferred for counting. For example, DAI may be determined, in part, based on at least one cumulative PDCCH number, wherein the actual index may be related with a counting sequence. Thus, a PDCCH received from a TRP associated with a lower channel quality may be counted before a TRP associated with a higher channel quality. In some embodiments, local counting may be used for a first TRP with a lower channel quality, and global counting may be used for a second TRP with a higher channel quality. For PDCCH from the same CORESET group, the counting order may be sorted according to at least one CORESET index, for example, at least one PDCCH from CORESET with at least one larger index may be placed behind for counting.

As illustrated in FIG. 5, within a PDCCH monitoring occasion, PDCCH from TRP2 may be counted after the PDCCH from TRP1 since PDCCH from TRP2 may have a better channel condition. For example, if at least one PDCCH with cDAI=7 is missing, UE 630 may not know whether there is at least one actual PDCCH transmission since it is the last PDCCH. When at least one PDCCH cDAI=7 comes from TRP with a channel condition exceeding at least one predetermined threshold, there may be lower probability of at least one PDCCH missing.

In some embodiments, NE 620 may be configured for global counting of at least one PDCCH. For example, at least one global index may be configured for DAI based on joint counting, which may provide an improved ability to cross check between TRPs and detecting of missing PDCCHs. As shown in FIG. 5, when UE 630 does not receive at least one PDCCH with cDAI=6, but receives at least one PDCCH with cDAI=7, UE 630 may be aware that PDCCH with cDAI=6 may be missing, and/or there may be an improved ability to determine HARQ-ACK codebook size. NE 620 may determine at least one DAI bit according to at least one cDAI based on joint counting with modulo operation for 4.

In step 607, NE 620 may configure a plurality of PDCCHs associated with a plurality of TRPs, wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one DAI.

In step 609, NE 620 may transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme to UE 630. For example, NE 620 may transmit multiple PDCCH from different TRP/CC.

In step 611, upon receiving the at least one PDCCH with DAI according to the at least one proposed counting scheme, UE 630 may detect at least one missing PDCCH, for example, based upon at least one DAI bit.

In step 613, UE 630 may determine at least one HARQ-ACK codebook size. For example, for ACK/NACK bits corresponding to missing PDCCH scheduled PDSCH, UE 630 may set NACK directly.

FIG. 7 illustrates an example of a method performed by a network entity, such as network entity 910 in FIG. 9. In step 701, the network entity may determine whether at least one carrier aggregation is configured. For example, upon determining that no CA is configured, the network entity may be configured to configure

bit number

2 or 4 for DAI according to, for example, channel quality. In various embodiments, the network entity may be configured to configure 4-bit DAI for at least one cell edge user in response to at least one missing PDCCH detection ability of the network entity exceeding at least one performance threshold. Additionally or alternatively, a user equipment, such as UE 920 in FIG. 9, may be configured to configure 2-bit DAI for at least one cell center user in response to at least one probability of PDCCH missing falling below at least one predetermined threshold.

In step 703, the network entity may determine whether at least one DAI bit number is configured. In step 705, the network entity may determine at least one DAI with modulus 4 operation, for example, according to cDAI. In certain embodiments, upon the network entity determining that no DAI bit number is configured, or that DAI bit number is configured as 2 bits, the network entity may determine DAI with modulus 4 operation based upon global counting with configured order for PDCCH in the same PDCCH monitoring occasion from a different TRP. For example, each PDCCH may only include 2 bits for indicating PDCCH counting index, i.e., cDAI.

In some embodiments, the network entity may configured at least one reference TRP index associating with higher-layer signalling. For example, the network entity may select at least one reference TRP with channel quality exceeding at least one predetermined threshold configured to improve detection of missing PDCCH by the network entity. The network entity may determine channel quality based upon at least one L3-RSRP measurement result. For each PDCCH from at least one different TRP in at least one PDCCH monitoring occasion, at least one PDCCH from the at least one TRP is deferred for counting. For example, DAI may be determined, in part, based on at least one cumulative PDCCH number, wherein the actual index may be related with a counting sequence. Thus, a PDCCH received from a TRP associated with a lower channel quality may be counted before a TRP associated with a higher channel quality. In some embodiments, local counting may be used for a first TRP with a lower channel quality, and global counting may be used for a second TRP with a higher channel quality.

As illustrated in FIG. 4, TRP2 may be a reference TRP based upon channel quality exceeding at least one predetermined threshold. In various embodiments, within at least one PDCCH monitoring occasion, at least one PDCCH from TRP2 may be counted after the at least one PDCCH is received from TRP1 For example, if PDCCH with cDAI=7 is missing, the UE may not know whether there is an actual PDCCH transmission since it is the last PDCCH. In response, when PDCCH with cDAI=7 comes from reference TRP with channel condition exceeding at least one predetermined threshold, this may lower the probability for PDCCH missing below at least one predetermined threshold.

In certain embodiments, the NE may count at least one PDCCH. For example, at least one local index may be used for DAI with TRP-specific separate PDCCH counting for at least one other TRP, for example, at least one TRP other than the reference TRP. Additionally or alternatively, the global index may be configured to for DAI with joint PDCCH counting for reference TRP. As a result, this may provide missing detection ability exceeding at least one predetermined threshold configured to assist of DAI of reference TRP. Furthermore, as illustrated in FIG. 4, when the UE does not receive PDCCH with cDAI=6/3 but receives PDCCH with cDAI=5 and cDAI=7, the UE may be configured to know that PDCCH with cDAI=6/3 is missing, and that there is no problem for determining at least one HARQ-ACK codebook size.

In some embodiments, at least one DAI indication bit may be determined based upon at least one counter DAI with modulo operation for 4 on account of 2-bit indication. In some embodiments, the NE may configure, for the UE, at least one counting order for PDCCH in at least one PDCCH monitoring occasion from at least one different TRP associated with at least one higher-lever signaling.

As illustrated in FIG. 5, within a PDCCH monitoring occasion, PDCCH from TRP2 may be counted after the PDCCH from TRP1 since PDCCH from TRP2 may have a better channel condition. For example, if at least one PDCCH with cDAI=7 is missing, the UE may not know whether there is at least one actual PDCCH transmission since it is the last PDCCH. When at least one PDCCH cDAI=7 comes from TRP with a channel condition exceeding at least one predetermined threshold, there may be lower probability of at least one PDCCH missing.

In some embodiments, the NE may be configured for global counting of at least one PDCCH. For example, at least one global index may be configured for DAI based on joint counting, which may provide an improved ability to cross check between TRPs and detecting of missing PDCCHs. As shown in FIG. 5, when the UE does not receive at least one PDCCH with cDAI=6, but receives at least one PDCCH with cDAI=7, the UE may be aware that PDCCH with cDAI=6 may be missing, and/or there may be an improved ability to determine HARQ-ACK codebook size. The NE may determine at least one DAI bit according to at least one cDAI based on joint counting with modulo operation for 4.

In step 707, the NE may configure a plurality of PDCCHs associated with a plurality of TRPs, wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one DAI.

In step 709, the NE may transmit at least one PDCCH with DAI according to at least one proposed counting scheme to the UE. For example, the NE may transmit multiple PDCCH from different TRP/CC.

FIG. 8 illustrates an example of a method performed by user equipment, such as user equipment 920 in FIG. 9. In step 801, the UE may receive at least one PDCCH associated with at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one DCI field comprising at least one DAI from a NE, such as NE 910 in FIG. 9. For example, the UE may receive multiple PDCCH from different TRP/CC.

In step 803, upon receiving the at least one PDCCH with DAI according to the at least one proposed counting scheme, the UE may detect at least one missing PDCCH, for example, based upon at least one DAI bit. In step 805, the UE may determine at least one HARQ-ACK codebook size. For example, for ACK/NACK bits corresponding to missing PDCCH scheduled PDSCH, the UE may set NACK directly.

FIG. 9 illustrates an example of a system according to certain example embodiments. In one example embodiment, a system may include multiple devices, such as, for example, network entity 910 and/or user equipment 920.

Network entity 910 may be one or more of a base station, such as a mmWave antenna, an evolved node B (eNB) or 5G or New Radio node B (gNB) , a serving gateway, a server, and/or any other access node or combination thereof. Furthermore, network entity 910 and/or user equipment 920 may be one or more of a citizens broadband radio service device (CBSD) .

User equipment 920 may include one or more of a mobile device, such as a mobile phone, smart phone, personal digital assistant (PDA) , tablet, or portable media player, digital camera, pocket video camera, video game console, navigation unit, such as a global positioning system (GPS) device, desktop or laptop computer, single-location device, such as a sensor or smart meter, or any combination thereof.

One or more of these devices may include at least one processor, respectively indicated as 911 and 921.

Processors

911 and 921 may be embodied by any computational or data processing device, such as a central processing unit (CPU) , application specific integrated circuit (ASIC) , or comparable device. The processors may be implemented as a single controller, or a plurality of controllers or processors.

At least one memory may be provided in one or more of devices indicated at 912 and 922. The memory may be fixed or removable. The memory may include computer program instructions or computer code contained therein.

Memories

912 and 922 may independently be any suitable storage device, such as a non-transitory computer-readable medium. A hard disk drive (HDD) , random access memory (RAM) , flash memory, or other suitable memory may be used. The memories may be combined on a single integrated circuit as the processor, or may be separate from the one or more processors. Furthermore, the computer program instructions stored in the memory and which may be processed by the processors may be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language. Memory may be removable or non-removable.

Processors

911 and 921 and

memories

912 and 922 or a subset thereof, may be configured to provide means corresponding to the various blocks of FIGS. 1-8. Although not shown, the devices may also include positioning hardware, such as GPS or micro electrical mechanical system (MEMS) hardware, which may be used to determine a location of the device. Other sensors are also permitted and may be included to determine location, elevation, orientation, and so forth, such as barometers, compasses, and the like.

As shown in FIG. 9,

transceivers

913 and 923 may be provided, and one or more devices may also include at least one antenna, respectively illustrated as 914 and 924. The device may have many antennas, such as an array of antennas configured for multiple input multiple output (MIMO) communications, or multiple antennas for multiple radio access technologies. Other configurations of these devices, for example, may be provided.

Transceivers

913 and 923 may be a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that may be configured both for transmission and reception.

The memory and the computer program instructions may be configured, with the processor for the particular device, to cause a hardware apparatus such as user equipment to perform any of the processes described below (see, for example, FIGS. 1-8) . Therefore, in certain example embodiments, a non-transitory computer-readable medium may be encoded with computer instructions that, when executed in hardware, perform a process such as one of the processes described herein. Alternatively, certain example embodiments may be performed entirely in hardware.

In certain example embodiments, an apparatus may include circuitry configured to perform any of the processes or functions illustrated in FIGS. 1-8. For example, circuitry may be hardware-only circuit implementations, such as analog and/or digital circuitry. In another example, circuitry may be a combination of hardware circuits and software, such as a combination of analog and/or digital hardware circuit (s) with software or firmware, and/or any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and at least one memory that work together to cause an apparatus to perform various processes or functions. In yet another example, circuitry may be hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that include software, such as firmware for operation. Software in circuitry may not be present when it is not needed for the operation of the hardware.

The features, structures, or characteristics of certain embodiments described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, the usage of the phrases “certain embodiments, ” “some embodiments, ” “other embodiments, ” or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. Thus, appearance of the phrases “in certain embodiments, ” “in some embodiments, ” “in other embodiments, ” or other similar language, throughout this specification does not necessarily refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. The above embodiments may be applied to any communication network or wireless system. While many of the above embodiments refer to LTE or LTE-A, other embodiments may be used for 3GPP fifth generation (5G) technology, fourth generation (4G) technology, New Radio (NR) technology, and/or any wireless land access network (WLAN) .

Partial Glossary

3GPP 3rd Generation Partnership Project

5G 5th Generation Wireless System

ACK Acknowledgement

CA Carrier Aggregation

CC Component Carrier

cDAI Counter Dynamic Assignment Index

CORESET Control Resource Set

DAI Dynamic Assignment Index

DCI Dynamic Control Indicator

eMBB Enhanced Mobile Broadband

eNB evolved Node B

E-UTRAN Evolved Universal Mobile Telecommunications SystemTerrestrial Radio Access Network

gNB Next Generation Node B

HARQ Hybrid Automatic Repeat Request

LTE Long Term Evolution

MAC Medium Access Control

MIMO Multiple Input Multiple Output

NACK Non Acknowledgement

NCJT Non-Coherent Joint Transmission

NE Network Entity

NR New Radio

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PUSCH Physical Uplink Control Channel

REL Release

tDAI Total Dynamic Assignment Index

TRP Transmission Receive Point

UE User Equipment

UL Uplink

WI Work Item

Claims

An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

configure a plurality of physical downlink control channels (PDCCHs) associated with a plurality of transmission receive points (TRPs) , wherein each TRP corresponds with each PDCCH, and wherein each PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) ; and

transmit at least one PDCCH associated with the at least one DAI according to at least one local DAI counting scheme and/or at least one global DAI counting scheme.
The apparatus according to claim 1, wherein the at least one local DAI counting scheme is configured to count each of a plurality of PDCCHs on a plurality of TRPs separately, and the at least one global DAI counting scheme is configured to count multiple PDCCHs on multiple TRPs as a single count.
The apparatus according to any of claims 1 and 2, wherein the at least one global DAI counting scheme takes into account channel qualities between TRPs and the user equipment.
The apparatus according to any of claims 1-3, wherein the global counting scheme is configured to start counting in the order from a PDCCH on a TRP with the worst channel quality to a PDCCH on a TRP with the best channel quality.
The apparatus according to any of claims 1-4, wherein the at least one reference TRP is associated with at least one channel quality exceeding at least one channel quality of at least one other TRP.
The apparatus according to any of claims 1-5, wherein one global PDCCH index is used in DAI of the reference TRP to provide checking ability for the missing PDCCH from other TRP.
The apparatus according to any of claims 1-6, wherein upon the apparatus determining that DAI bit number is configured as 4 bits, or that no CA is configured, the apparatus further determines DAI with modulus 4 operation based on 3-dimension counting with order of first TRP, followed by component carrier, followed by at least one PDCCH monitoring occasion index.
The apparatus according to any of claims 1-7, wherein upon the apparatus determining that DAI bit number of 4 bits is not configured, or that DAI bit number of 2 bits is configured, the apparatus further determines DAI with modulus 4 operation based upon global counting with configured order for the at least one PDCCH monitoring occasion from a different TRP.
The apparatus according to any of claims 1-8, wherein the at least one global DAI counting scheme is configured to count based on at least one 2-bit indication, and the at least one local DAI counting scheme is configured to count based on at least one 2-bit indication.
The apparatus according to any of claims 1-9, wherein upon determining that no CA is configured, the apparatus further configures bit number 2 or 4 for DAI according to channel quality.
The apparatus according to any of claims 1-10, wherein the apparatus further determines whether at least one dynamic assignment index (DAI) bit number is configured.
An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:

receive at least one physical downlink control channel (PDCCH) associated with at least one dynamic assignment index (DAI) according to at least one local DAI counting scheme and/or at least one global DAI counting scheme, wherein the received PDCCH comprises at least one downlink control information (DCI) field comprising at least one downlink assignment index (DAI) ;

detect at least one missing detected PDCCH; and

determine at least one hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook size.
The apparatus according to claim 12, wherein the at least one local DAI counting scheme is configured to count each of a plurality of PDCCHs on a plurality of TRPs separately, and the at least one global DAI counting scheme is configured to count multiple PDCCHs on multiple TRPs as a single count.
The apparatus according to any of claims 12 and 13, wherein the at least one global DAI counting scheme takes into account channel qualities between TRPs and the user equipment.
The apparatus according to any of claims 12-14, wherein the global counting scheme is configured to start counting in the order from a PDCCH on a TRP with the worst channel quality to a PDCCH on a TRP with the best channel quality.
The apparatus according to any of claims 12-15, wherein the at least one reference TRP is associated with at least one channel quality exceeding at least one channel quality of at least one other TRP.
The apparatus according to any of claims 12-16, wherein one global PDCCH index is used in DAI of the reference TRP to provide checking ability for the missing PDCCH from other TRP.
A method according to any of claims 1-17.
A non-transitory computer-readable medium encoding instructions that, when executed in hardware, perform a process according to any of claims 1-17.
An apparatus comprising means for performing a process according to any of claims 1-17.
An apparatus comprising circuitry configured to cause the apparatus to perform a process according to any of claims 1-17.
A computer program product encoded with instructions for performing a process according to any of claims 1-17.