Determining a processing time of a user equipment

Abstract

According to an example aspect of the present disclosure, there is provided determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

Description

DETERMINING A PROCESSING TIME OF A USER EQUIPMENTFIELD

[0001] Various example embodiments relate in general to determining a processing time of a user equipment, for example in cellular communication networks.BACKGROUND

[0002] User Equipments, UEs, cannot send an acknowledgement or a negative acknowledgement message immediately after receiving a downlink transmission, because UEs need to process the received transmission. Processing time of UEs hence needs to be taken into account at least in cellular communication networks, such as in networks operating according to Long Term Evolution, LTE, and / or 5G radio access technology. 5G radio access technology may also be referred to as New Radio, NR, access technology. Since its inception, LTE has been widely deployed and 3rd Generation Partnership Project, 3 GPP, still develops LTE. Similarly, 3GPP also develops standards for 5G / NR. One of the topics in the 3GPP discussions is related to the processing time and there is a need to provide enhanced methods, apparatuses and computer programs at least related to determining processing times of UEs Such enhancements may also be beneficial in other cellular communication networks as well, such as in 6G networks in the future.SUMMARY

[0003] According to some aspects, there is provided the subject-matter of the independent claims. Some example embodiments are defined in the dependent claims.

[0004] The scope of protection sought for various example embodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments of the invention.

[0005] According to a first aspect of the present invention, there is provided a user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to determine a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and control transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0006] Example embodiments of the first aspect may comprise at least one feature from the following bulleted list or any combination of the following features:• wherein the number of scheduled DMRS antenna ports includes a number of DMRS antenna ports used for the PDSCH transmission and / or a number of DMRS antenna ports used for one or more further PDSCH transmissions coscheduled with the PDSCH transmission (the number of scheduled DMRS antenna ports may equivalently be referred to as the number of scheduled PDSCH layers);• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to determine the processing time based at least on whether the user equipment applies advanced receiver operation for multi-user interference mitigation;• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to determine the processing time based at least on one or more parameter values that are dependent on the number of scheduled DMRS antenna ports;• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to determine the processing time by comparing the number of scheduled DMRS antenna ports to a threshold number of scheduled DMRS antenna ports above which the processing time is increased;• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to determine that the processing time is equal to a first processing time when the number of scheduled DMRS antenna ports is below the threshold number of scheduled DMRS antenna ports or determine that the processing time is equal to a second processing time when thenumber of scheduled DMRS antenna ports is above the threshold number of scheduled DMRS antenna ports;• wherein the first processing time is less than the second processing time;• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to report, to a wireless network node, at least one of: o a threshold number of scheduled DMRS antenna ports above which the processing time is increased; or o one or more processing time values associated with respective numbers of scheduled DMRS antenna ports;• wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to receive, from a wireless network node, downlink control information scheduling the PDSCH transmission, and indicative of at least one of: o a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission; o an indication that the number of scheduled DMRS antenna ports exceeds a threshold number of scheduled DMRS antenna ports; o a value of the processing time; or o one or more parameter values for determining the processing time.

[0007] According to a second aspect of the present invention, there is provided a wireless network node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the wireless network node at least to determine a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and schedule transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0008] Example embodiments of the second aspect may comprise at least one feature from the following bulleted list or any combination of the following features:• wherein the number of scheduled DMRS antenna ports includes a number of DMRS antenna ports used for the PDSCH transmission and / or a number ofDMRS antenna ports used for one or more further PDSCH transmissions coscheduled with the PDSCH transmission (the number of scheduled DMRS antenna ports may equivalently be referred to as the number of scheduled PDSCH layers);• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to determine the processing time based at least on whether the user equipment applies advanced receiver operation for multi-user interference mitigation;• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to determine the processing time by comparing the number of scheduled DMRS antenna ports to a threshold number of scheduled DMRS antenna ports above which the processing time is increased;• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to determine that the processing time is equal to a first processing time when the number of scheduled DMRS antenna ports is below the threshold number of scheduled DMRS antenna ports or determine that the processing time is equal to a second processing time when the number of scheduled DMRS antenna ports is above the threshold number of scheduled DMRS antenna ports;• wherein the first processing time is less than the second processing time;• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to receive, from the user equipment, at least one of: o a threshold number of scheduled DMRS antenna ports above which the processing time is increased; or o one or more processing time values associated with respective numbers of scheduled DMRS antenna ports;• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to transmit, to the user equipment, downlink control information scheduling the PDSCH transmission, and indicative of at least one of: o a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission;o an indication that the number of scheduled DMRS antenna ports exceeds a threshold number of scheduled DMRS antenna ports; o a value of the processing time; or o one or more parameter values for determining the processing time.• wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to determine a scheduling restriction for a candidate PDSCH transmission to be co-scheduled with the PDSCH transmission if the candidate PDSCH transmission has a higher modulation order than a maximum supported modulation order of the user equipment.

[0009] According to a third aspect of the present invention, there is provided a first method, comprising determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time. The first method may be performed by a user equipment.

[0010] According to a fourth aspect of the present invention, there is provided a second method, comprising determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time. The second method may be performed by a wireless network node.

[0011] According to a fifth aspect of the present invention, there is provided a user equipment, comprising means for determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and means for controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0012] According to a sixth aspect of the present invention, there is provided a wireless network node, comprising means for determining a processing time required foracknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and means for scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0013] According to a seventh aspect of the present invention, there is provided a non- transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0014] According to an eighth aspect of the present invention, there is provided a non- transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least perform determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0015] According to a ninth aspect of the present invention, there is provided a computer program comprising instructions which, when the program is executed by an apparatus, cause the apparatus to perform determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time. The first method may be performed by a user equipment.

[0016] According to a tenth aspect of the present invention, there is provided a computer program comprising instructions which, when the program is executed by an apparatus, cause the apparatus to perform determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a userequipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports, and scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 illustrates an example of a network scenario in accordance with at least some example embodiments;

[0018] FIG. 2 illustrates an example apparatus capable of supporting at least some example embodiments;

[0019] FIG. 3 illustrates a flow graph of a first method in accordance with at least some example embodiments;

[0020] FIG. 4 is a flow graph of a second method in accordance with at least some example embodiments.EXAMPLE EMBODIMENTS

[0021] Operation of cellular communication networks may be enhanced by the procedures described herein. More specifically, determination of a processing time of a User Equipment, UE, required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the UE, may be enhanced by taking into account a number of scheduled Demodulation Reference Signal, DMRS, antenna ports. By taking into account the number of scheduled DMRS antenna ports when determining the processing time, it is possible for example to determine that the processing time is increased when the number of scheduled DMRS antenna ports is above a threshold number of scheduled DMRS antenna ports. Hence, timing for acknowledging the PDSCH transmission may be improved and the use of different processing times enabled.

[0022] FIG. 1 illustrates an example of a network scenario in accordance with at least some example embodiments. According to the example network scenario of FIG. 1, there may be a cellular communication system, which comprises UE 110, wireless network node 120 and core network element 130. UE 110 may be connected to wireless network node 120via air interface 115 and wireless network node 120 may be connected to core network 130 via wired interface 125. In some example embodiments, air interface 115 may a beam -based interface.

[0023] UE 110 may comprise, for example, a smartphone, a cellular phone, a Machine-to-Machine, M2M, node, Machine-Type Communications, MTC, node, RedCap UE (Reduced Capability UE) node, an Internet of Things, loT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, any kind of suitable wireless terminal. Wireless network node 120 may be considered as a serving node for UE 110 and one cell of wireless network node 120 may be a serving cell for UE 110.

[0024] Air interface 115 between UE 110 and wireless network node 120 may be configured in accordance with a Radio Access Technology, RAT, which both UE 110 and wireless network node 120 are configured to support. Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which may also be known as fifth generation, 5G, radio access technology and MulteFire. For example in the context of LTE, wireless network node 120 may be referred to as eNB, while wireless network node 120 may be referred to as gNB in the context of NR. In some example embodiments, wireless network node 120 may be referred to as a Transmission and Reception Point, TRP, or control multiple TRPs that may be co-located or non-co-1 ocated.

[0025] In some example embodiments, UE 110 and wireless network node 120 may be configured to operate according to at least one standard defined by the 3rd Generation Partnership Project, 3GPP. In any case, example embodiments of the present disclosure are not restricted to any particular wireless technology. Instead, example embodiments may be exploited in any cellular communication network.

[0026] Wireless network node 120 may be connected, directly or via at least one intermediate node, with core network 130 via interface 125. Core network 130 may be, in turn, coupled via interface 135 with another network (not shown in FIGURE 1), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network. Wireless network node 120 may be connected, directly or via at least one intermediate node, with core network 130 or with another core network.

[0027] DMRSs may be used in cellular communication networks, such as in 3GPP networks. In the context of 3 GPP, a maximum number of DMRS antenna ports in Rel.18may be doubled compared to DMRS antenna ports used in Rel.15. For example, for DMRS type 1 , the maximum number of enhanced DMRS antenna ports in Rel.18 for PDSCH, and / or Physical Uplink Shared Channel, PUSCH, may be 8 DMRS antenna ports for a single symbol DMRS and 16 DMRS antenna ports for a double symbol DMRS. For DMRS type 2, the maximum number of DMRS antenna ports in Rel.18 for PDSCH and / or PUSCH may be 12 DMRS antenna ports for a single symbol DMRS and 16 DMRS antenna ports for a double symbol DMRS. To support the larger number of DMRS antenna ports, Frequency Domain Orthogonal Cover Code, FD-OCC, 4 code may be agreed to be supported in Rel-18 instead of FD-OCC 2 in Rel-15.

[0028] A processing time required for acknowledging a PDSCH transmission at a UE may be defined, e.g., in 3GPP TS 38.214 section 5.3, as follows:If the first uplink symbol of the PUCCH which carries the HARQ-ACK information, as defined by the assigned HARQ-ACK timing Ki and Koffset, if configured, and the PUCCH resource to be used and including the effect of the timing advance, starts no earlier than at symbol Zy, where Li is defined as the next uplink symbol with its CP starting after Uoafter the end of the last symbol of the PDSCH carrying the TB being acknowledged, then the UE shall provide a valid HARQ-ACK message.- Ni is based on u of Table 5.3-1 and Table 5.3-2 for UE processing capability 1 and 2 respectively, where u corresponds to the one of (JIPDCCH, PDSCH, pup) resulting with the largest TprOc,i, where the PDCCH corresponds to the subcarrier spacing of the PDCCH scheduling the PDSCH, the PDSCH corresponds to the subcarrier spacing of the scheduled PDSCH, and uL corresponds to the subcarrier spacing of the uplink channel with which the HARQ-ACK is assumed to be transmitted regardless of whether or not the PDSCH reception provides a transport block for a HARQ process with disabled HARQ-ACK information as indicated by HARQ-feedbackEnabling-disablingperHARQprocess, if provided, and K is defined in clause 4.1 of [4, TS 38.211],- For operation with shared spectrum channel access in FR1, T is calculated according to [4, TS 38.211], otherwise T,=0.- If the PDSCH DM-RS position l for the additional DM-RS in Table 7.4.1.1.2-3 in clause 7.4.1.1.2 of [4, TS 38.211] is l = 12 then 7\0,o=74 in Table 5.3-1, otherwise Ni,o=13.- If the UE is configured with multiple active component carriers, the first uplink symbol which carries the HARQ-ACK information further includes the effect of timing difference between the component carriers as given in [11, TS 38.133],- For the PDSCH mapping type A as given in clause 7.4.1.1 of [4, TS 38.211]: if the last symbol of PDSCH is on the z-th symbol of the slot where i < 7, then di,i = 7- i, otherwise di,i = 0- If a PUCCH of a larger priority index would overlap with PUCCH / PUSCH of a smaller priority index and the UE is not provided uci-MuxWithDiffPrio for the primary PUCCH group or uci-MuxWithDiffPrioSecondaryPUCCHgroup for the secondary PUCCH group, <7? for the PUCCH of a larger priority is set as reported by the UE; otherwise <7? = 0.- For UE processing capability 1 : If the PDSCH is mapping type B as given in clause 7.4.1.1 of [4, TS 38.211], and- if the number of PDSCH symbols allocated is L > 7, then di,i = 0,- if the number of PDSCH symbols allocated is L > 4 and L < 6, then di,i = 7- L.- if the number of PDSCH symbols allocated is L = 3 then di,i = 3 + min (d,l), where d is the number of overlapping symbols of the scheduling PDCCH and the scheduled PDSCH.- if the number of PDSCH symbols allocated is 2, then di,i = 3+d, where d is the number of overlapping symbols of the scheduling PDCCH and the scheduled PDSCH.- For UE processing capability 2: If the PDSCH is mapping type B as given in clause 7.4.1.1 of [4, TS 38.211],- if the number of PDSCH symbols allocated is L > 7, then di,i = 0,- if the number of PDSCH symbols allocated is L > 3 and L < 6, then di,i is the number of overlapping symbols of the scheduling PDCCH and the scheduled PDSCH,- if the number of PDSCH symbols allocated is 2,- if the scheduling PDCCH was in a 3 -symbol CORESET and the CORESET and the PDSCH had the same starting symbol, then di,i = 3,- otherwise dpi is the number of overlapping symbols of the scheduling PDCCH and the scheduled PDSCH.- For UE processing capability 2 with scheduling limitation when PDSCH = 1, if the scheduled RB allocation exceeds 136 RBs, the UE defaults to capability 1 processing time. The UE may skip decoding a number of PDSCHs with last symbol within 10 symbols before the start of a PDSCH that is scheduled to follow Capability 2, if any of those PDSCHs are scheduled with more than 136 RBs with 30kHz SCS and following Capability 1 processing time.- For a UE that supports capability 2 on a given cell, the processing time according to UE processing capability 2 is applied if the high layer parameter processingType2Enabled in PDSCH-ServingCellConfig is configured for the cell and set to 'enable'.- PDSCH processing capability 2 is not applied to PDSCH scheduled by PDCCH with DCI format 4_0, 4_1, or 4_2.- If this PUCCH resource is overlapping with another PUCCH or PUSCH resource, then HARQ-ACK is multiplexed following the procedure in clause 9.2.5 of [6, TS 38.213], otherwise the HARQ-ACK message is transmitted on PUCCH.- UE is not expected to be scheduled to transmit PUCCH carrying the HARQ-ACK information for PDSCH scheduled by a PDCCH if uplink switching gap is triggered for the PUCCH as defined in clause 6.1.6 and the first uplink symbol of the PUCCH starts earlier than the duration of Tswitch+ Tproc l} from the last symbol of the PDCCH, where Tswitchequals to the switching gap duration.Otherwise the UE may not provide a valid HARQ-ACK corresponding to the scheduled PDSCH. The value of Tproc,i is used both in the case of normal and extended cyclic prefix.For a PDSCH that consists of two PDSCH transmission occasions in time domain in one slot, di,i is calculated based on the first PDSCH transmission occasion in the slot, and as described above.For PDSCH with mapping Type B, if PDSCH is scheduled by a PDCCH reception that includes two PDCCH candidates from two respective search space sets, as described in clause 10.1 of [6, TS 38.213], di,i for PDSCH processing time is determined by considering the PDCCH candidate that results in larger di,i value.Table 5.3-1: PDSCH processing time for PDSCH processing capability 1Table 5.3-2: PDSCH processing time for PDSCH processing capability 2

[0029] The processing time may be dependent on the DMRS position and UE processing capability (either 1 or 2). UE processing capability 2 may be applied for PDSCH mapping type B when a UE indicated the capability UE processing capability 2. Hence, theUE may support faster processing than capability 1 UE for low latency service (e.g. Ultra Reliable Low Latency Communication, URLLC). Additional Downlink Control Information, DCI, of co-scheduled UE(s) may be provided for improving channel estimation and demodulation performance, e.g., for a UE utilizing an advanced receiver such as Enhanced Minimum Mean-Squared Error Interference Rejection Combining, E-MMSE- IRC, Reduced Complexity Maximum Likelihood, R-ML, etc.Table 1 Example of DCI information related to co-scheduled UEs

[0030] At least one challenge is that UE’s PDSCH processing capability should take into account all of the DMRS configurations, number of co-scheduled UEs / layers, use of an advanced receiver, etc. Support for larger number of DMRS antenna ports introduces more processing complexity in a receiver of a UE. Even with the same number of DMRS antenna ports larger than 4 ports, Rel-18 DMRS may use a single symbol while Rel-15 may use two symbols. In addition, support for an advanced receiver of a UE may introduce more processing complexity in the receiver of the UE. In some example embodiments, an advanced receiver may refer to receiver operation requiring additional complexity due to multi-user interference mitigation, and this complexity increase may depend on a total number of PDSCH layers, wherein the total number of PDSCH layers may be equivalent to a total number of DMRS antenna ports. Alternatively, or in addition, UE 110 may determine the processing time based at least on whether UE applies receiver operation for multi-user interference mitigation.

[0031] There is a need to avoid ambiguities when different processing capabilities and different processing times (e.g., different N1 values as in Table 5.3-1 of section 5.3 in 3GPP TS 38.214) are applicable. Embodiments of the present disclosure therefore provide enhancements for determining a processing time of a UE, such as UE 110 of FIG. 1.

[0032] In some example embodiments, UE 110 may transmit a capability report to wireless network node 120. For example, UE 110 may report if it supports a processing capability with certain conditions. Alternatively, or in addition, UE 110 may report which processing time values and / or tables are applied for different conditions. The conditions may comprise at least one of the following:• what processing capability: capability 1, capability 2 or a new capability;• downlink DMRS configurations: Rel-15 (i.e. type-1 or type-2) or Rel-18 (i.e. e-typel or e-type2);• total number of downlink DMRS antenna ports: e.g. up to 4,8,12,16, or 24, etc.;• whether an advanced UE receiver is applied or not. UE processing time parameters may be in the form of either or all of Nl, or new delay parameter d3 or Tad\anced processing according to the type of delay defined. Processing time parameter T advanced processing may be referred to as T3 as well;• a threshold number of scheduled DMRS antenna ports above which the processing time is increased; or• one or more processing time values associated with respective numbers of scheduled DMRS antenna ports.

[0033] In some example embodiments, UE 110 may report a maximum modulation order up to which co-scheduled UEs (e.g., 64-QAM) may be supported in receive processing with an advanced receiver. If the maximum modulation order is not reported, UE 110 may be assumed to support up to a maximum modulation order defined in the specification, e.g., in a 3 GPP specification.

[0034] In some example embodiments, wireless network node 120 may, with the consideration of a receiving capability of UE 110, perform at least one of the following actions:• ensure that the scheduled number of DMRS antenna ports is within a capability of UE 110;• configure UE 110, when UE 110 supports different parameter values (Nl, or new delay parameter d3 or Tadvanced_processing), and indicate a number of co-scheduled DMRS antenna ports by DCI. In such a case, UE 110 may apply a corresponding processing time or processing delay;• configure UE 110, when UE 110 does not support additional processing delay, and indicate a number of co-scheduled DMRS antenna ports via DCI. In such a case, UE 110 may apply either a simple or advanced UE receiver algorithm fulfilling the latency requirements;• decide not to provide co-scheduled UE information when the number of DMRS antenna ports is beyond the capability of UE 110 for a given processing time;• impose a scheduling restriction for co-scheduled UE(s) when candidate co-scheduled UE(s) have a higher modulation order than the reported maximum supported modulation order of an advanced receiver of UE 110.

[0035] In some example embodiments, UE 110 may receive, from wireless network node 120, DCI scheduling the PDSCH transmission, and indicative of at least one of• a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission;• an indication that the number of scheduled DMRS antenna ports exceeds a threshold number of scheduled DMRS antenna ports;• a value of the processing time; or• one or more parameter values for determining the processing time.

[0036] An example list of possible conditions of interest is illustrated in Table 2.Table 2 An example list of possible conditions of interest

[0037] Condition 1 may be supported by 3 GPP Rel-15. Conditions 2 and 3 may be similar cases, wherein an advanced UE receiver is used, but support processing capability 1, not other processing capabilities. With the assumption of a larger processing delay, a new table of N1 may be introduced for UE 110 with an advanced receiver.

[0038] The number of DMRS symbols may be different in case of conditions 2 and 3, but the number of DMRS symbols may also be relative to the number of DMRS antenna ports scheduled. The processing delay may increase according to the number of DMRS antenna ports (or PDSCH layers) scheduled and hence, the number of scheduled DMRS antenna ports should be taken into account.

[0039] UE 110 may determine a processing time required for acknowledging a PDSCH transmission at UE 110 based at least on the number of scheduled DMRS antenna ports, and control transmission of acknowledgment information, such as HARQ feedback information (ACK or NACK), for the PDSCH transmission in accordance with the determined processing time, for instance by controlling that the acknowledgement information are transmitted no earlier than the processing time after the last symbol carrying the PDSCH transmission. The number of scheduled DMRS antenna ports may include a number of DMRS antenna ports used for the PDSCH transmission and / or a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission. The number of scheduled DMRS antenna ports may be less than, or equal to, a maximum number of DMRS antenna ports as defined by a DMRS configuration, wherein the DMRS configuration may be provided by wireless network node120. For example, the maximum number of DMRS antenna ports may be 16 and the number of scheduled DMRS antenna ports may be 12.

[0040] In some example embodiments, UE 110 may hence determine the processing time by comparing the number of scheduled DMRS antenna ports to a threshold number of scheduled DMRS antenna ports above which the processing time is increased. For example, UE 110 may determine that the processing time is equal to a first processing time when the number of scheduled DMRS antenna ports is below the threshold number of scheduled DMRS antenna ports. Alternatively, UE 110 may determine that the processing time is equal to a second processing time when the number of scheduled DMRS antenna ports is above the threshold number of scheduled DMRS antenna ports. The first processing time may be less than the second processing time.

[0041] In case of lower processing delays, UE 110 may indicate a UE capability that the maximum number of DMRS antenna ports may be used without increasing the processing time as specified in 3 GPP Release 15. Wireless network node 120 may apply the larger processing time only when the number of DMRS antenna ports is beyond the capability of UE 110. As a first option, different processing time values may be applied for single and double symbol DMRSs. Applying different processing time values for single and double symbol DMRSs may be a simple option, especially with an assumption of larger number of DMRS antenna ports for double symbol DMRS. In such a case, UE 110 may indicate if it requires larger processing time for single or double symbol DMRS scheduled. Otherwise, wireless network node 120 may assume the same processing time as for the legacy, i.e. Rel-15. As a second option, UE 110 may indicate the required processing time according to the number of DMRS antenna ports scheduled. For example, UE 110 may indicate that “processing time N1 is defined by a first table for L<=4, by a second table for 4<L<=8”, etc., wherein “L” is the number of DMRS antenna ports scheduled or allocated. To determine the processing time N1 for each PDSCH scheduling, wireless network node 120 may indicate either the total number of DMRS antenna ports scheduled, which table to be used for Nl, and / or if advanced N1 value is to be applied or not.

[0042] In some example embodiments, wireless network node 120 may ensure that no more than the capability of UE 110 is scheduled. As a first option, wireless network node 120 may configure the number of DMRS antenna ports to be lower than the capability of UE 110. In such a case, the processing time might not be increased. As a second option, wirelessnetwork node 120 may provide the co-scheduled UE information when UE processing capability is fulfilled with respect to UE capability, but not otherwise. For example, if the number of scheduled DMRS antenna ports is beyond the capability of UE 110, wireless network node 120 may not provide the co-scheduled UE information, e.g. by indicating Bit field 7 “Others” in Table 1, for prioritizing the system capacity or latency instead of the performance ofUE 110.

[0043] Conditions 4 and 5 may be similar as conditions 2 and 3, and applicable when PDSCH mapping type B is used. If UE 110 supports capability 2 but PDSCH mapping type A is used, the situation would be identical to conditions 2 and 3. Hence, it may be assumed that PDSCH mapping type B is scheduled for UE 110.

[0044] The actions described in connection with conditions 2 and 3 may be applicable to processing capability 2 similarly. As another option, it may be restricted that for processing capability 2, when UE 110 cannot fulfil the latency requirement. For example, wireless network node 120 may configure UE 110 not supporting processing capability 2 or wireless network node 120 may configure, if wireless network node 120 supports additional delay for advanced UE receiver or not. If not supported, UE 110 may use any receiver implementation fulfilling processing time specified for processing capability 2 without increasing processing time.

[0045] In case of condition 6, the maximum number of DMRS antenna ports may be the same as 3GPP Rel-15 double symbol DMRS. For Rel-15 double symbol DMRS, due to one symbol delay of DMRS reception, DMRS channel estimation time may be reduced by 1 symbol. Hence, the processing time N1 may be reduced by 1 symbol length compared to 3GPP Rel-15. The N1 table may be reused, as in Table 5.3-1 of section 5.3 in 3GPP TS 38.214.

[0046] In case of condition 7, the maximum number of DMRS antenna ports may be double compared to 3GPP Rel-15. Hence, UE 110 may require additional processing delay due to larger number of ports to be assumed. As one of solution, UE 110 may indicate if additional processing delay is necessary and for what conditions (e.g. if the number of DMRS antenna ports L is beyond threshold). The actions described in connection with conditions 2 and 3 may be performed.

[0047] In case of condition 8, the actions described in connection with conditions 2 and 3 may be performed. In case of condition 9, the actions described in connection with conditions 2, 3 and 7 may be performed. In case of conditions 10 and 11, the actions described in connection with conditions 4 and 5 may be applied though the advanced receiver is not used for conditions 10 and 11, instead a larger number of DMRS antenna ports due to Rel-18 DMRS configuration may be supported. In case of conditions 12 and 13, the actions described in connection with conditions 4 and 5, and 8 and 9, may apply.

[0048] The processing delay time may be introduced in various ways. The delay component d3 may be added either inside the parentheses, in which case the additional processing time would be an integer number of symbols, or it may be summed to the equation similar to Text. In such a case, the additional processing time would be an integer number of samples.

[0049] According to UE’s capability, at least one of Nl, d3 or Tadvanced_processingmay be used for introducing a delay, possibly depending on a type of the delay. That is, UE 110 may determine the processing time based at least on one or more parameter values (Nl, d3, T3) that are dependent on the number of scheduled DMRS antenna ports. Parameter value Nl may be a numerology (subcarrier spacing) dependent parameter. Parameter value d3 is counted as number of symbols. Parameter value T3 may be a certain time value independent from the numerology. Different parameters may be used according to UE’s implementation.

[0050] If the delay is different from different Orthogonal Frequency Division Multiplexed, OFDM, numerology (p) or symbol length, a new delay parameter may be reflected to Nl value as specified in the above examples. If the delay is defined in terms of OFDM symbol units, a new delay parameter d3 may be introduced.

[0051] If the delay has no relation with numerology or the number of OFDM symbols, and it is rather determined as a value according to the total number of scheduled DMRS antenna ports or the number of scheduled DMRS antenna ports to decode, the delay may be included as form of Tadvanced_processing Or Text2-

[0052] In some example embodiments, if the first uplink symbol of the PUCCH which carries the HARQ-ACK information, as defined by the assigned Hybrid Automatic Repeat Request, HARQ,- Acknowledgement, ACK, timing Ki and Koffset, if configured, and the PUCCH resource to be used and including the effect of the timing advance, starts no earlierthan at symbol Li, where Li may be defined as the next uplink symbol with its Cyclic Prefix, CP, starting after Tproc l=+ d1+ d2+ d3)(2048 + 144) • / c2-fi• Tc+ Textafter the end of the last symbol of the PDSCH carrying the Transmission Block, TB, being acknowledged, then the UE shall provide a valid HARQ-ACK message.- If the UE indicates a support for advancedMIMO-ReceiverCapability, and- if the UE is configured with advancedMIMO-ReceiverOperation, and- if the UE is scheduled with a larger number of DMRS antenna ports than threshold, or alternatively, the UE is co-scheduled with other UEs, or alternatively the UE is co-scheduled with a larger number of DMRS antenna ports than a threshold,- then d3 = M, where M is a non-zero value defined in the specification or provided by the UE in the UE capability indication,- otherwise d3 = 0.

[0053] The additional processing time may be assigned with more value steps than 0 or M depending on how many ports are scheduled, e.g., 0 for 1 DMRS port, Ml for 2 DMRS ports, M2 for 3 and 4 DMRS ports, etc.

[0054] Alternatively, Tproc lmay be calculated as follows: Tproc=+ dl+

[0055] Wireless network node 120 may determine the processing time required for acknowledging a PDSCH transmission at UE 110 similarly, based at least on the number of scheduled DMRS antenna ports, and schedule transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time, for instance by controlling that the acknowledgement information are scheduled no earlier than the processing time after the last symbol carrying the PDSCH transmission. In some example embodiments, wireless network node 120 may determine a scheduling restriction for a candidate PDSCH transmission to be co-scheduled with the PDSCH transmission if the candidate PDSCH transmission has a higher modulation order than a maximum supported modulation order of the user equipment.

[0056] FIG. 2 illustrates an example apparatus capable of supporting at least some example embodiments. Illustrated is device 200, which may comprise, for example, UE 110or wireless network node 120, or a control device configured to control the functioning thereof, possibly when installed therein. Comprised in device 200 is processor 210, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 210 may comprise, in general, a control device. Processor 210 may comprise more than one processor. Processor 210 may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. Processor 210 may comprise at least one Qualcomm Snapdragon and / or Intel Atom processor. Processor 210 may comprise at least one application-specific integrated circuit, ASIC. Processor 210 may comprise at least one field-programmable gate array, FPGA. Processor 210 may be means for performing method steps in device 200. Processor 210 may be configured, at least in part by computer instructions, to perform actions.

[0057] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0058] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0059] Device 200 may comprise memory 220. Memory 220 may comprise randomaccess memory and / or permanent memory. Memory 220 may comprise at least one RAM chip. Memory 220 may comprise solid-state, magnetic, optical and / or holographic memory, for example. Memory 220 may be at least in part accessible to processor 210. Memory 220 may be at least in part comprised in processor 210. Memory 220 may be means for storing information. Memory 220 may comprise computer instructions that processor 210 is configured to execute. When computer instructions configured to cause processor 210 to perform certain actions are stored in memory 220, and device 200 overall is configured to run under the direction of processor 210 using computer instructions from memory 220, processor 210 and / or its at least one processing core may be considered to be configured to perform said certain actions. Memory 220 may be at least in part comprised in processor 210. Memory 220 may be at least in part external to device 200 but accessible to device 200.

[0060] Device 200 may comprise a transmitter 230. Device 200 may comprise a receiver 240. Transmitter 230 and receiver 240 may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter 230 may comprise more than one transmitter. Receiver 240 may comprise more than one receiver. Transmitter 230 and / or receiver 240 may be configured to operate in accordance with Global System for Mobile communication, GSM, Wideband Code Division Multiple Access, WCDMA, Long Term Evolution, LTE, and / or 5G / NR standards, for example.

[0061] Device 200 may comprise a Near-Field Communication, NFC, transceiver 250. NFC transceiver 250 may support at least one NFC technology, such as Bluetooth, Wibree or similar technologies.

[0062] Device 200 may comprise User Interface, UI, 260. UI 260 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 200 to vibrate, a speaker and a microphone. A user may be able to operate device 200 via UI 260, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory 220 or on a cloud accessible via transmitter 230 and receiver 240, or via NFC transceiver 250, and / or to play games.

[0063] Device 200 may comprise or be arranged to accept a user identity module 270. User identity module 270 may comprise, for example, a Subscriber Identity Module, SIM,card installable in device 200. A user identity module 270 may comprise information identifying a subscription of a user of device 200. A user identity module 270 may comprise cryptographic information usable to verify the identity of a user of device 200 and / or to facilitate encryption of communicated information and billing of the user of device 200 for communication effected via device 200.

[0064] Processor 210 may be furnished with a transmitter arranged to output information from processor 210, via electrical leads internal to device 200, to other devices comprised in device 200. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 220 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor 210 may comprise a receiver arranged to receive information in processor 210, via electrical leads internal to device 200, from other devices comprised in device 200. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 240 for processing in processor 210. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

[0065] Device 200 may comprise further devices not illustrated in FIG. 2. For example, where device 200 comprises a smartphone, it may comprise at least one digital camera. Some devices 200 may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the frontfacing camera for video telephony. Device 200 may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device 200. In some example embodiments, device 200 lacks at least one device described above. For example, some devices 200 may lack a NFC transceiver 250 and / or user identity module 270.

[0066] Processor 210, memory 220, transmitter 230, receiver 240, NFC transceiver 250, UI 260 and / or user identity module 270 may be interconnected by electrical leads internal to device 200 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 200, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the example embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the example embodiments.

[0067] FIG. 3 is a flow graph of a first method in accordance with at least some example embodiments. The phases of the illustrated first method may be performed by UE 110 or by a control device configured to control the functioning thereof, possibly when installed therein.

[0068] The first method may comprise, at step 310, determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports. The first method may also comprise, at step 320, controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0069] FIG. 4 is a flow graph of a second method in accordance with at least some example embodiments. The phases of the illustrated method may be performed by wireless network node 120 or by a control device configured to control the functioning thereof, possibly when installed therein.

[0070] The second method may comprise, at step 410, determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports. The second method may also comprise, at step 420, scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

[0071] It is to be understood that the example embodiments disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular example embodiments only and is not intended to be limiting.

[0072] Reference throughout this specification to one example embodiment or an example embodiment means that a particular feature, structure, or characteristic described in connection with the example embodiment is included in at least one example embodiment. Thus, appearances of the phrases “in one example embodiment” or “in an example embodiment” in various places throughout this specification are not necessarily all referringto the same example embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0073] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various example embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such example embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations.

[0074] In an example embodiment, an apparatus, such as, for example, UE 110 or wireless network node 120, may comprise means for carrying out the example embodiments described above and any combination thereof.

[0075] In an example embodiment, a computer program may be configured to cause a method in accordance with the example embodiments described above and any combination thereof. In an example embodiment, a computer program product, embodied on a non-transitory computer readable medium, may be configured to control a processor to perform a process comprising the example embodiments described above and any combination thereof.

[0076] In an example embodiment, an apparatus, such as, for example, UE 110 or wireless network node 120, may comprise 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 at least to perform the example embodiments described above and any combination thereof.

[0077] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of example embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the disclosure can be practicedwithout one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

[0078] While the forgoing examples are illustrative of the principles of the example embodiments in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the disclosure. Accordingly, it is not intended that the disclosure be limited, except as by the claims set forth below.

[0079] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY

[0080] At least some example embodiments find industrial application in cellular communication networks.ACRONYMS LIST3GPP 3rd Generation Partnership ProjectACK AcknowledgementBS Base StationCP Cyclic PrefixDCI Downlink Control InformationDMRS Demodulation Reference SignalE-MMSE-IRC Enhanced Minimum Mean-Squared Error Interference RejectionCombiningFD-OCC Frequency Domain Orthogonal Cover CodeGSM Global System for Mobile communicationHARQ Hybrid Automatic Repeat Request loT Internet of ThingsLTE Long-Term EvolutionM2M Machine-to-MachineNACK Negative AcknowledgmentNR New RadioOFDM Orthogonal Frequency Division MultiplexedPDCCH Physical Downlink Control ChannelPDSCH Physical Downlink Shared ChannelPUCCH Physical Uplink Control ChannelPUSCH Physical Uplink Shared ChannelR-ML Reduced Complexity Maximum LikelihoodRAT Radio Access TechnologyRRC Radio Resource ControlTB Transmission BlockTRP Transmission and Reception PointUE User EquipmentUI User InterfaceWCDMA Wideband Code Division Multiple AccessWiMAX Worldwide Interoperability for Microwave AccessWLAN Wireless Local Area NetworkREFERENCE SIGNS LIST

Claims

CLAIMS:

1. A user equipment, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to:- determine a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports; and- control transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

2. The user equipment according to claim 1, wherein the number of scheduled DMRS antenna ports includes a number of DMRS antenna ports used for the PDSCH transmission and / or a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission.

3. The user equipment according to claim 1 or claim 2, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:- determine the processing time based at least on whether the user equipment applies advanced receiver operation for multi-user interference mitigation.

4. The user equipment according to any of the preceding claims, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:- determine the processing time based at least on one or more parameter values that are dependent on the number of scheduled DMRS antenna ports.

5. The user equipment according to any of the preceding claims, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:determine the processing time by comparing the number of scheduled DMRS antenna ports to a threshold number of scheduled DMRS antenna ports above which the processing time is increased.

6. The user equipment according to claim 5, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:- determine that the processing time is equal to a first processing time when the number of scheduled DMRS antenna ports is below the threshold number of scheduled DMRS antenna ports; or- determine that the processing time is equal to a second processing time when the number of scheduled DMRS antenna ports is above the threshold number of scheduled DMRS antenna ports.

7. The user equipment according to claim 6, wherein the first processing time is less than the second processing time.

8. The user equipment according to any of the preceding claims, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:- report, to a wireless network node, at least one of: o a threshold number of scheduled DMRS antenna ports above which the processing time is increased; or o one or more processing time values associated with respective numbers of scheduled DMRS antenna ports.

9. The user equipment according to any of the preceding claims, wherein the stored instructions further cause, when executed by the at least one processor, the user equipment at least to:- receive, from a wireless network node, downlink control information scheduling the PDSCH transmission, and indicative of at least one of: o a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission;o an indication that the number of scheduled DMRS antenna ports exceeds a threshold number of scheduled DMRS antenna ports; o a value of the processing time; or o one or more parameter values for determining the processing time.

10. A wireless network node, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the wireless network node at least to:- determine a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports; and- schedule transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

11. The wireless network node according to claim 10, wherein the number of scheduled DMRS antenna ports includes a number of DMRS antenna ports used for the PDSCH transmission and / or a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission.

12. The wireless network node according to claim 10 or claim 11, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to:- determine the processing time based at least on whether the user equipment applies advanced receiver operation for multi-user interference mitigation.

13. The wireless network node according to any of claims 10 to 12, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to: determine the processing time by comparing the number of scheduled DMRS antenna ports to a threshold number of scheduled DMRS antenna ports above which the processing time is increased.

14. The wireless network node according to claim 13, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to:- determine that the processing time is equal to a first processing time when the number of scheduled DMRS antenna ports is below the threshold number of scheduled DMRS antenna ports; or- determine that the processing time is equal to a second processing time when the number of scheduled DMRS antenna ports is above the threshold number of scheduled DMRS antenna ports.

15. The wireless network node according to claim 14, wherein the first processing time is less than the second processing time.

16. The wireless network node according to any of claims 10 to 15, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to:- receive, from the user equipment, at least one of: o a threshold number of scheduled DMRS antenna ports above which the processing time is increased; or o one or more processing time values associated with respective numbers of scheduled DMRS antenna ports.

17. The wireless network node according to any of claims 10 to 16, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to:- transmit, to the user equipment, downlink control information scheduling the PDSCH transmission, and indicative of at least one of: o a number of DMRS antenna ports used for one or more further PDSCH transmissions co-scheduled with the PDSCH transmission; o an indication that the number of scheduled DMRS antenna ports exceeds a threshold number of scheduled DMRS antenna ports; o a value of the processing time; or o one or more parameter values for determining the processing time.

18. The wireless network node according to any of claims 10 to 17, wherein the stored instructions further cause, when executed by the at least one processor, the wireless network node at least to:- determine a scheduling restriction for a candidate PDSCH transmission to be coscheduled with the PDSCH transmission if the candidate PDSCH transmission has a higher modulation order than a maximum supported modulation order of the user equipment.

19. A method, comprising:- determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at the user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports; and- controlling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

20. A method, comprising:- determining a processing time required for acknowledging a Physical Downlink Shared Channel, PDSCH, transmission at a user equipment based at least on a number of scheduled Demodulation Reference Signal, DMRS, antenna ports; and- scheduling transmission of acknowledgment information for the PDSCH transmission in accordance with the determined processing time.

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