Apparatus, method and computer program

Abstract

There is provided an apparatus comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity, determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received and providing feedback information relating to the at least one scheduled data transmission to a net- work entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

Description

TITLEApparatus, Method and Computer ProgramTECHNICAL FIELD

[0001] Various embodiments of this disclosure relate generally to methods, apparatus and computer programs, and in particular, but not exclusively, to missed PDCCH feedback to an access node for improved link adaptation and adaptive retransmissions.BACKGROUND

[0002] A communication system can be seen as a facility that enables communication sessions between two or more communication devices, or provides communication devices access to a network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

[0003] A mobile or wireless communication network may operate in accordance with standard(s), such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of mobile or wireless communication network that operate in accordance with 3GPP standards are generally referred to as 4G (4th Generation) networks, 5G (5th Generation) network, 5G-Advanced networks and 6G networks.SUMMARY

[0004] Some embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the various example embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described herein.

[0005] In a first aspect there is provided a method comprising receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity, determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received and providing feedback information relating to the at least onescheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

[0006] The first information may indicate a count of downlink data transmissions from the network entity to be acknowledged by the apparatus and wherein determining that the control channel transmission has not been received comprises determining that the count is non-sequential.

[0007] The first information may comprise downlink control information.

[0008] The feedback information may comprise hybrid automatic repeat request, HARQ, information.

[0009] The indication of the third state may comprise a bit.

[0010] The feedback information may be provided for n slots and may comprise an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

[0011] The feedback information may be provided for one or more transport blocks per slot.

[0012] The feedback information may be provided for one or more component carriers.

[0013] In a second aspect there is provided a method comprising providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus, receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowl-edgement, NACK state.

[0014] The first information may indicate a count of downlink data transmissions from the network entity to be acknowledged by the apparatus.

[0015] The first information may comprise downlink control information.

[0016] The feedback information may comprise hybrid automatic repeat request, HARQ, information.

[0017] The indication of the third state may comprise a bit.

[0018] The feedback information may be provided for n slots and comprises an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

[0019] The feedback information may be provided for n slots and comprises an indication of a number of bits in the feedback information and the method may comprise determining, based on the indication of the number of bits that a control channel transmission scheduling a data transmission in the nth slot has not been received.

[0020]

[0021] The method may comprise receiving the indication of the number of bits in a media access control control element on a physical uplink shared channel.

[0022] The method may comprise receiving the indication of the number of bits on a physical layer.

[0023] The feedback information may be provided for one or more transport blocks per slot.

[0024] The feedback information may be provided for one or more component carriers.

[0025] The feedback information may comprises ⌈log2L⌉ bits, where L is a sum of possible combinations of indications of either the first, second and third state for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

[0026] In a third aspect there is provided a method comprising receiving first information from a network entity, the first information relating to at least one scheduled data transmission in n slots from the network entity, determining, based on the first information, that a control channel transmission scheduling at least one further data transmission has not been received and providing feedback information to the network entity, the feedback information comprising a feedback index, p, corresponding to an indication of a first, acknowledgement, ACK, state, a second non-acknowledgement, NACK, state or a third state indicative that the control channel transmission scheduling the at least one further data transmission has not been received for at least one transport block in each of the 1st to (n-1)th slots and an indication of either the first state or the second state for at least one transport block in the nth slot.

[0027] The index p may represent a unique combination of possible indications of either the first, second and third state for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot

[0028] In a fourth aspect there is provided a method comprising providing first information to a user equipment, the first information relating to at least one scheduled data transmission in n slots from the apparatus, receiving feedback information from the user equipment, the feedback information comprising a feedback index, p, corresponding to an indication of a first, acknowledgement, ACK, state, a second nonacknowledgement, NACK, state or a third state indicative that a control channel transmission scheduling at least one further data transmission has not been received for at least one transport block in each of the 1st to (n-1)th slots and an indication of either the first state or the second state in at least one transport block of the nth slot.

[0029] The index p may represent a unique combination of possible indications of either the first, second and third state for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

[0030] In a fifth aspect there is provided a method comprising receiving first information from a network entity, the first information relating to at least one scheduled data transmission in n slots, receiving the at least one scheduled data transmission from the network entity and providing feedback information relating to the at least one scheduled data transmission to the network entity, wherein the feedback information comprises an indication of the number of the n slots for which the first information has been received.

[0031] The method may comprise providing feedback information relating to the at least one scheduled data transmission in a media access control control element, MAC CE, on a physical uplink shared channel and wherein a field of the MAC CE comprises the indication of the number of bits in the feedback information.

[0032]

[0033] The feedback information may comprise log2L] bits, where L is a sum of possible combinations of indications of either a first, acknowledgement, ACK, state, a second non-acknowledgement, NACK state and a third state indicative that a control channel transmission scheduling a further at least one data transmission has not been received for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

[0034] The first information may comprise a control channel transmission scheduling the at least one data transmission.

[0035] In a sixth aspect there is provided a method comprising providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus in n slots, providing the at least one scheduled data transmission to the user equipment, receiving feedback information relating to the atleast one scheduled data transmission from the user equipment, wherein the feedback information comprises an indication of the number of the n slots for which the first information has been received and determining, based on the indication of the n slots for which information has been received that a control channel transmission scheduling a data transmission in the last one or more consecutive slot of the nth slots has not been received.

[0036] In a seventh aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus at least to perform a method according to the first, second, third, fourth, fifth or sixth aspect.

[0037] In an eighth aspect there is provided a method comprising means for performing the method according to the first, second, third, fourth, fifth or sixth aspect.

[0038] In a ninth aspect there is provided a non-transitory computer readable medium comprising instructions wherein the instructions when executed by at least one processor of an apparatus cause the apparatus to perform the method according to the first, second, third, fourth, fifth or sixth aspect.

[0039] In a tenth aspect there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the method according to the first, second, third, fourth, fifth or sixth aspect.

[0040] Some embodiments of the invention are defined in the dependent claims.

[0041] In the above, many different aspects have been described. As previously noted, it should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above (or otherwise in this disclosure).

[0042] Various other aspects are also described in the following detailed description and in the claims.BRIEF DESCRIPTION OF THE FIGURES

[0043] Some embodiments will be described, by way of non-limiting and illustrative example only, with reference to the figures, in which:

[0044] Fig. 1 shows an example of a communication network to which examples disclosed herein may be applied;

[0045] Fig. 2 shows a signalling flow against time between a gNB and a UE;

[0046] Fig. 3 shows a flowchart of a method according to an example;

[0047] Fig. 4 shows a flowchart of a method according to an example;

[0048] Fig. 5 shows a signalling flow against time between a gNB and a UE;

[0049] Fig. 6 shows a table of bits required for feedback and a table of bits required for optimised feedback;

[0050] Fig. 7 shows a table of bits required for feedback and a table of bits required for optimised feedback

[0051] Fig. 8 shows a flowchart of a method according to an example;

[0052] Fig. 9 shows a flowchart of a method according to an example;

[0053] Fig. 10 shows a table of possible combinations for c-DAI=2, #TBs per slot = 2;

[0054] Fig. 11 shows a flowchart of a method according to an example;

[0055] Fig. 12 shows a flowchart of a method according to an example;

[0056] Fig. 13 shows an example of an apparatus.DETAILED DESCRIPTION

[0057] The following embodiments are provided by way of non-limiting and illustrative example. Although the specification may refer to “an”, “one”, or “some” embodiments) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it intended such feature, structure, or characteristic may be applied in connection with other embodiments (whether or not explicitly described).

[0058] It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0059] For the purposes of this disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of this disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0060] As used herein, the term “or” refers to a non-exclusive “or” unless otherwise indicated (e.g., use of “or else” or “or in the alternative”).

[0061] As used herein, unless stated explicitly, performing a respective feature, step, or functionality “in response to A” does not indicate that the respective feature,step, or functionality is performed immediately after “A” occurs as one or more intervening features, steps, or functionalities may be performed (at least in part) between an occurrence of the respective feature, step, or function and “A”. Analogously, performing a respective feature, step, or functionality “based on A” does not indicate that the respective feature, step, or functionality is performed solely based on “A” as the respective feature, step, or functionality may be further based on one or more other features, steps, or functionalities in addition to “A”.

[0062] Embodiments described herein may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0063] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the network and / or which is configured to control radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or nonground network device, such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0064] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralised unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an F1interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0065] The term “terminal device” refers to any end device that may be configured to perform wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like.

[0066] A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources may include, e.g., a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0067] Fig. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 configured to provide one or more cells, such as cell 100, and a network node 112 configured to provide one or moreother cells, such as cell 102. Each cell may, for example, be a macro cell, a micro cell, femto, or a pico cell. The cell may define a coverage area or a service area of the corresponding access node.

[0068] The network node (110, 112) may be configured to provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node (110, 112) to the UE 120 and uplink (UL) communication from the UE 120 to the network node (110, 112). Examples of uplink channels may comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels may comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0069] There may be a plurality of UEs (120, 122) in the system. Each of the plurality of UEs may be served by the same or by different network nodes (110, 112). UE may be configured with dual connectivity (DC), wherein the UE, for example UE 120, may be connected to multiple network nodes (110, 112). The UEs (120, 122) may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or ve-hicle-to-vehicle (V2V), for example.

[0070] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications, for example, refer to such an interface as an X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called an Xn interface.

[0071] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise a plurality of entities (e.g. a mobility management entity (MME) and a gateway node). The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5GC may, for example, comprise an access and mobility management function (AMF) and a user plane function / gateway (UPF) and otherfunctions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may, for example, support packet routing and forwarding, packet inspection and quality of service (QoS) handling.

[0072] ARQ (automatic repeat request) is a feedback mechanism where a receiver sends a retransmission request if an error is detected in received data. Hybrid ARQ (HARQ) is a radio protocol that uses a hybrid of forward error correction (FEC) and ARQ at MAC layer to provide feedback information. FEC involves adding redundancy bits to the original data to allow error detection and correction at the receiver.

[0073] In NR, a UE indicates success or failure of decoding of a received DL packet on PDSCH by sending feedback information, i.e., HARQ acknowledgment (ACK) / negative acknowledgement (NACK). The HARQ mechanism for PUSCH transmission is slightly different and there is no explicit feedback of the uplink (UL) PUSCH packet.

[0074] In the DL HARQ framework, a HARQ process number is indicated in DL control information (DCI) send on the PDCCH as part of the DL assignment. A data transmission on PDSCH in terms of transport blocks (TB) is associated with the HARQ process number. After a decoding attempt the UE will calculate and verify the checksum for the correctness of the received transport block. If an error is detected at the UE, it will indicate a negative acknowledgement (NACK), else ACK on PUCCH (or PUSCH).

[0075] A parameter k1 (PDSCH-to-HARQ_feedback timing indication on a DCI and configured with a set of dl-DataToUL-ACK values over RRC) is defined, kl specifies when the UE has to transmit a HARQ acknowledgement for the corresponding PDSCH transport block. In TDD, UL transmission occasions are limited in time due to the DL and UL transmissions alternating with each other, and the DL and UL transmission occasions are typically pre-determined with a tdd-UL-DL-Configuration RRC information element. Hence, multiple DL transport blocks and code block groups (CBGs) received in multiple slots and possibly multiple carriers (serving cells) are to be acknowledged jointly as a single HARQ-ACK message in a single UL transmission by multiplexing the feedback information. The HARQ codebook format specifies how to multiplex and interpret the feedback information to the single HARQ-ACK message at the UE and the gNB, respectively.

[0076] CBG refers to a mechanism where the property of a larger TB being segmented into several code blocks, each encoded separately, is exploited in the HARQoperation. The code blocks of a TB are grouped into code block groups, and each CBG can be separately acknowledged as either correctly or incorrectly received. Thus the retransmission of a TB that doesn’t decode correctly can avoid resending the CBGs that were already decoding correctly and only retransmit the CBGs that contained code blocks that failed to decode.

[0077] When the UE is scheduled to receive a PDSCH by a gNB, a corresponding HARQ-ACK bit (or bits in case of CBG transmission or multi-codeword MIMO transmission) is incorporated into the HARQ-ACK message that is subsequently transmitted, whereas no HARQ-ACK bit / bits are to be added to the HARQ-ACK message for a PDSCH that the gNB did not schedule. For example, if a slot N and N+2 each carry a PDSCH to a UE, but there is no PDSCH in slot N+1, then the HARQ-ACK message the UE sends back to the network will not have any bits for the slot N+1. This approach may cause a problem if the gNB did try to schedule a PDSCH in slot N+1, but the PDCCH scheduling the PDSCH was lost (PDCCH DTX), and the UE is not able to distinguish whether PDSCH was not received because PDCCH was not transmitted, or was transmitted but not decoded correctly. A Downlink Assignment Index (DAI) may be used to solve this issue.

[0078] A counter Downlink Assignment Indicator (C-DAI) in DCI indicates the number of DL transmissions that are pending to be acknowledged. The C-DAI is used by the UE to determine if there is any missed PDCCH. For a PDCCH that the UE has not decoded successfully corresponding to a PDSCH transmission, the UE sets a NACK as the corresponding HARQ feedback bit. Note that we will denote such a missed PDCCH as discontinuous transmission (DTX) in this document.

[0079] The HARQ framework in 3GPP allocates one bit to indicate ACK / NACK for each codeword (or CBG if CBG-based HARQ feedback is configured) per carrier per scheduled slot (in principle per scheduled PDSCH, but in practice there is either 1 or 0 PDSCHs per slot with 1 PDSCH consisting of 2 codewords if scheduled number of MIMO layers was >4). The DAI value in DCI on PDCCH indicates total count of DL assignments sent so far for which the UE should report ACK / NACK, e.g., if DAI is 3 then UE sends ACK / NACK for DL assignments (assuming no wrap-around) received in most recent 3 slots that have not been acknowledged. The counter DAI may prevent ACK / NACK bundling errors in the feedback bits.

[0080] Fig. 2 shows an example of DL assignments in 4 slots, each specifying a HARQ process id, hx, DAI value, dx, and / cl, where each / c1xvalue is pointing the HARQ A / N report of the scheduled PDSCH to the same slot “Bundled HARQ A / N report”. TheHARQ acknowledgement for four slots is sent in one UL slot containing a bundled report for all 4 DL transmissions

[0081] If a DL DCI reception is missed at the UE (PDCCH DTX), then the DAI in the next DL DCI may indicate this problem. The UE sends NACK for the DCIs which are not received when it sees that a DCI was missed from the DAI value of the next DCI it receives correctly. The UE cannot use this method to determine if the last DCI is missed.

[0082] Upon receiving the HARQ acknowledgement for DL transmission including DTX cases, the gNB does not have a way of knowing whether the received NACK is due to unsuccessful PDSCH decoding or PDCCH DTX. Assuming that the NACK is received for PDSCH decoding failure, the gNB may schedule an adaptive retransmission of the packets using the next redundancy version (RV). The gNB may schedule retransmission with reserved modulation and coding scheme (MCS) but the UE may not be able to decode the retransmitted packet in case of DTX because it has not received the initial transmission DCI of the same packet.

[0083] If a gNB assumes that NACK refers to a failed PDSCH the gNB may schedule an adaptive HARQ retransmission with the next Redundancy Version (RV) in sequence for the corresponding packet. However, if the UE did not receive the DCI corresponding to the initial transmission, then the UE cannot decode the adaptive retransmission using reserved MCS, because it does not contain the transport block size (TBS) information and it never received this in the earlier transmission attempt because it was the PDCCH that failed, not the PDSCH. This may result in many wasted retransmissions. Similarly, even if the gNB schedules the retransmission with explicit indication of the TBS, it would typically use a non-self decodable RV automatically leading to the need for yet another retransmission before the TB has any chances of being correctly decodable.

[0084] The UE may choose to report ACK (as the UE knows asking for retransmissions will not help when the gNB is assuming that the UE has the TBS size determined from the first DCI that was never received) for not decoded RV=2 re-transmission with reserved MCS when the initial transmission DCI is not received by the UE. Due to the missing initial transmission DCI, the UE is not able to decode RV=2 re-transmission, but instead of reporting NACK for the re-transmission, it may report ACK to the gNB which forces discarding of the MAC TB and recovery through higher layer mechanisms. This leads the gNB to consider the MAC TB as having been received successfully by the UE, while the UE has not actually received the packet. In this case, the packet delay may increase waiting for higher layer recovery.

[0085] Adjustments for outer loop link adaptation (OLLA) update based on received bundled HARQ ACK / NACK / DTX has been proposed. In this proposal, if PUCCH DTX is detected then it is assumed to be due to PDCCH DTX. “Step up” or “step down” values are applied in response to Ack / Nack or DTX to adjust the target PDCCH block error rate (BLER) within 1% target. However, this is only applicable for the case that all the DCIs that would have resulted with their respective PDSCHs status to be reported in the same HARQ-ACK message to have been missed, in which case there is no HARQ-ACK message to transmit (from the UE’s perspective corresponds to the case that it was not scheduled with any data).

[0086] Another problem observed is that gNB detects multiple DTX in the beginning of the call when UE does not respond for UL grants for around 40-50 ms due to the UE not listening to PDCCH while performing the RRC reconfiguration processing. In this case, PDCCH channel quality indicator (CQI) offset drops significantly and does not recover till the end of the call. This affects the PDCCH link adaptation (LA) and may cause multiple retransmissions.

[0087] In the methods discussed, PDCCH DTX determination is based on PUCCH DTX detection. Assumption of DTX when UE is not responding. The handling of DTX is left to the implementation individually at UE and gNB. This may lead to misinterpretation of a HARQ ACK received at gNB if UE sends an ACK for closing the retransmission procedure early. In another case, if gNB is not aware of DTX then it may attempt adaptive retransmission which may delay delivery of the packet.

[0088] The gNB may perform PDSCH link adaptation in response to the NACK assuming PDSCH decoding failure, while the problem may have been with the PDCCH. This may lead to conservative DL MCS allocation in future. This may result is an unnecessary downgrade to the MCS, leading to sub-optimal performance. In addition, PDCCH link adaptation is not performed because PDCCH reception is considered to be successful. This may result in an incorrect update to the PDCCH OLLA. This error may be quite expensive for PDCCH given the large difference in cost between successful PDCCH reception versus incorrect reception due to the stringent target BLER for PDCCH, typically 1%.

[0089] The following aims to address the issue of sub-optimal PDCCH and PDSCH LA by differentiating between the PDCCH DTX and the PDSCH decoding failure in an unambiguous manner in the HARQ-ACK codebook sent from the UE to the gNB. An increase in overhead of feedback bits due to additional information is reduced.

[0090] Fig. 3 shows a flowchart of a method according to an example. The method may be performed at an apparatus. The apparatus may be, comprise or be comprised in a user equipment.

[0091] At 301, the method comprises receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity.

[0092] At 302, the method comprises determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received.

[0093] At 303, the method comprises providing feedback information relating to the at least one scheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

[0094] Fig. 4 shows a flowchart of a method according to an example. The method may be performed at an apparatus. The apparatus may be, comprise or be comprised in a network entity. The network entity may be an access node, such as a gNB.

[0095] At 401, the method comprises providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the network apparatus.

[0096] At 402, the method comprises receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowl-edgement, NACK state.

[0097] Methods as described with reference to Figs. 3 and 4 may address the problem of ambiguous feedback in case of PDCCH DTX, by including a further status (i.e. the third state) in addition to HARQ ACK / NACK in HARQ feedback to indicate DTX. This removes the ambiguity between PDSCH decoding failure and PDCCH DTX in the feedback information and allows gNB to handle it appropriately.

[0098] By indicating DTX explicitly in the feedback message, a gNB can perform PDCCH link adaptation appropriately. Penalizing the transmission on PDSCH by performing unnecessary link adaptation due to false interpretation of NACK will not occur. The use of adaptive retransmission using reserved MCS may be possible by being able to distinguish between DTX and NACK. The feedback overhead is optimized to reducethe total feedback bits.

[0099] The first information may comprise DCI. The feedback information may comprise HARQ information The feedback information may be provided for one or more TBs per slot. The feedback information may be provided for one or more component carriers and / or CBGs.

[0100] The first information (e.g., DCI) may indicate a count of downlink data transmissions from the network entity to be acknowledged by the apparatus (e.g., DAI). Determining that the control channel transmission has not been received may comprise determining that the count is non-sequential.

[0101] Fig. 5 shows an example of the use of three states for HARQ feed-back{ACK, NACK, DTX}.

[0102] In Fig. 5, DCI at t2and t3are not received by the UE, but DAI in d4contains the counter that indicates that a total of four DL DCI are transmitted for which HARQ feedback is to be bundled. In this case, as per current specification, UE will feed back 4 bits as ADDN where D represents the status DTX, assuming that the packet received for HARQ process h is successfully decoded but decoding of the PDSCH packet for HARQ process h4has failed.

[0103] An increase in feedback overhead may be overcome by avoiding unnecessary retransmissions, use of adaptive retransmissions, and improved link adaptation.

[0104] The unambiguous feedback allows the gNB to determine if the reception error is in the PDCCH or PDSCH to enable better retransmission decisions and update of PDSCH and PDCCH LA as needed. If the gNB gets the information of failure caused by PDCCH DTX, then link adaptation for PDCCH may be performed to adapt to the current channel conditions for PDCCH. Also, an adaptive retransmission can be made using the RV next to a transmission earlier than DTXed one (or as a new transmission), not the DTXed transmission.

[0105] The indication of the third state may comprise a bit.

[0106] For example, to support reporting of DTX, the number of HARQ ACK / NACK status states is increased to allow the three states to report DTX for the scheduling DCI as well as ACK / NACK for each scheduled TB. If ACK / NACK information can be fed back using only 1 bit (1 / 0), adding one more state for DTX (missing the scheduling DCI) may increase the HARQ feedback overhead, for example where there is one scheduling DCI per one scheduled PDSCH.

[0107] One approach for HARQ status indication would be to use 2 bits for HARQ ACK / NACK / DTX feedback for every transport block in each slot that is to be acknowledged. For example, if DAI counter is 2 and DTX indication bit is allowed, then HARQ feedback information can be any of the values shown on the left side table shown in Fig. 6. This requires a total of 4 bits, where 2 bits per HARQ process are used to indicate one of the 3 possible states. In this example, ACK is indicated by 01, NACK by 00, DTX by 10

[0108] The feedback information may be provided for n slots and comprise an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

[0109] For example, detecting DTX at the UE for the last HARQ based on DAI would not be possible, and so those states corresponding to D as the status for the last HARQ transmission can be removed. The reduced number of states (6) can be supported using 3 bits instead of 4 as shown in the right hand side table on Fig. 6.

[0110] The feedback information may comprise log2L] bits, where L is a sum of possible combinations of indications of either the first, second and third state for the 1st to n-1th slots and possible combinations of indications of either the first or second state of the nth slot.

[0111] The following algorithm may be used to optimize the reduction of feedback bits that includes ACK, NACK and DTX.

[0112] The sum of all possible combinations, L, of ACK / NACK(s) and DTX(s) for a component carrier isL = Zr=o1Zdie2)i2^^S:=

[0113] where, dtis a set containing the I slots for conveying DTX. If j e dhthen the y-th slat conveys DTX, where j e {1,.., n - 1}.T>i = jdt: di is a possible combination of I slots where DTX is to be conveyed? Note that hD(| = = 0,..,n - l, 'where n is the number of slots in which DL data scheduled is to be acknowledged, kt e {1, 2 [,3, 4]} is the number of TBs in the ithslot.

[0114] The number of feedback bits required from the total possible combinations of HARQ ACK / NACK / DTX may be determined as Nbits= [log2L],

[0115] UE may indicate the Nbitsas per the scheduling information available at the UE, i.e., the number of slots that are to be acknowledged n and the number of TBs per scheduled slot. The feedback combinations described above can may be separatedinto two parts: A / N combinations for all the slots / TBs and feedback with DTX in slots other than nth slot. In other words, an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

[0116] The optimization for other values of counter DAI may be obtained based on total size of the feedback table and maximum number of feedback indices required to report each HARQ status combination. For one TB in 1 slot (DAI=1), the HARQ feedback states can be {A, N}, hence 1 bit is sufficient. Non-reception of feedback is sufficient to determine PDCCH DTX.

[0117] For DAI =3 and 1 TB in each slot, the naive approach would use 6 bits, i.e., 2 bits for each HARQ ACK / NACK / DTX as shown in the left hand side table of Fig. 9. In the optimized approach, since the total HARQ feedback states are 27, this can be handled using 5 bits. A further reduction of states is possible by removing D for last HARQ transmission, the total states are 18, but still 5 bits are needed as shown in the right hand side table in Fig. 7.

[0118] For 4 transport blocks, we can reduce the number of bits to 7 by noting that the total HARQ states are 81 which can be handled using 7 bits (no need of 8 bits). Further reduction of states by removing D for last HARQ transmission, the total states become 54, which means only 6 bits are needed.

[0119] Fig. 8 shows a flowchart of a method according to an example. The apparatus may be, comprise or be comprised in a user equipment.

[0120] In 801, the method comprises receiving first information from a network entity, the first information relating to at least one scheduled data transmission in n slots from the network entity.

[0121] In 802, the method comprises determining, based on the first information, that a control channel transmission scheduling at least one further data transmission has not been received.

[0122] In 803, the method comprises providing feedback information to the network entity, the feedback information comprising a feedback index, p, corresponding to an indication of a first, acknowledgement, ACK, state, a second non-acknowledgement, NACK, state or a third state indicative that the control channel transmission scheduling the at least one further data transmission has not been received for at least one transport block in each of the 1st to (n-1)th slots and an indication of either the first state or the second state for at least one transport block in the nth slot.

[0123] Fig. 9 shows a flowchart of a method according to an example. The apparatus may be, comprise or be comprised in a network entity.

[0124] In 901, the method comprises providing first information to a user equipment network entity, the first information relating to at least one scheduled data transmission in n slots from the apparatus.

[0125] In 902, the method comprises receiving feedback information from the user equipment, the feedback information comprising a feedback index, p, corresponding to an indication of a first, acknowledgement, ACK, state, a second non-acknowledgement, NACK, state or a third state indicative that a control channel transmission scheduling at least one further data transmission has not been received for at least one transport block in each of the 1st to (n-1)th slots and an indication of either the first state or the second state in at least one transport block in either the first or second state of the nth slot.

[0126] The index p may represent a unique combination of possible indications of either the first, second and third state for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

[0127] The algorithm for determination of the feedback index based on ACK / NACK / DTX is as follows, taking ACK to be 1 and NACK to be 0.

[0128] The bit-field for the feedback is denoted by the binary vectorb = [b1;..., v6its]. We assume b s the most significant bit (MSB) and bNblts\s the least significant bit (LSB). The feedback bit-field is initialised to zero-vector, i.e., b = [0,..., 0], i.e. all NACK. The feedback index is initialized to p = 0.

[0129] UE sets the A / N feedback to each slot / TB following the rules given below.

[0130] For indices corresponding only to A / N without DTX. For 2^ies kiwith combinations of A / N Ntb= teskt bits are required to acknowledge all the scheduled slots / TBs corresponding to the first 2^skiindices. The feedback index p increments from 0 toand the binary equivalent of it is interpreted as A / N combinations from Nbits- Ntbto Nbitsposition of b = [bi bNblts].

[0131] For indices corresponding to A / N with DTX For d^i Xde-Dt 2^ies\dkicombinations, add DTX cases

[0132] For Z = l,..n - l

[0133] Get Dt= (n combinations for placing the DTX (DTX slot pattern determination is given in the next slide)

[0134] For a DTX slot combination, d e Dt, arrange the remaining slots consecutively and generate the numbers from 0 to £deI);2^les\dkl- 1 and the binary equivalent of it is interpreted as A / N combinations from Nbits- ^iedktto Nbitsposition of b = [bi,...,bWwts]

[0135] The feedback index is incremented from p + 1 to p + Z ' < IE'D12^iES\d kiwith each A / N combination determined above.

[0136] Note that Dtcombinations of DTX positions are assumed to be predefined in a specific order in the algorithm above so that there is same interpretation of the feedback index at the UE and the gNB. The pattern for setting DTX slots is determined as given below:

[0137] The combination of I DTX slots within {1,..., n - 1} slots are ordered following the lexicographic ordering property in the increasing sequence of their elements The total ways of selecting position of I DTX slots from n - 1 slots is (n-l)l[i!(n- 1-!)!]For I = 1,..., n - 1Create (1distinct combinations of selecting slot positions to DTXin lexicographic orderThe positioning of I DTX slots for a selected combination is listed as Dt= {s,, s2,..., £(} where s1;s2,..., e S\n are the DTX slot numbers and S-L < s2< ••• < slIncrement the feedback index p from p + 1 to p+ £deI);2^les\dklfor each selected combination Dt

[0138] For handling feedback of multiple transport blocks per slot and multiple such slots with the optimized number of feedback bits, we need to generalize the approach of determining feedback table, i.e., interpretation of feedback index to multiple slots and TBs and / or carriers. The total number of slots to be acknowledged is determined based on counter DAI for a carrier.

[0139] The number of TBs per slot for MIMO scheduling can be {1,2 [,3,4]} as per 6G proposals. Note that the DAI counter does not increase with the number of TBs per slot and ACK / NACK for each TB is fed back. PDCCH DTX determined for a slot applies to all TBs transmitted in that slot. If the UE misses last k DCIs (which cannot be determined by the UE due to lack of any further DAI), then there will be no feedback from those k slots for any TB. A few examples of ACK / NACK feedback with DTX information is given in Error! Reference source not found, with calculation of total combinations of feedback and required number of bits#TB n c C-DAI T-DAI HARQ A / N A / N (2 bits) (2 bits)bits needed1 1 1 1 1 A / N 12 1 1 1 1 AA / AN / NA / NN 23 1 1 1 1 8 combinations of 3 A / N 34 1 1 1 1 16 combinations of 4 A / N 4{1,1} 2 1 2 2 AA / AN / NA / NN / DA / DN 3{2,2} 2 1 2 2 16 combinations of 4 A / N +st 5 4 combinations of D on 1 DCIand A / N for 2ndDCI{3,2} 2 1 2 2 32 combinations of 5 A / N +st 6 4 combinations of D on 1 DCIand A / N for 2ndDCITable 1Fig. 10 shows the pattern for defining value of HARQ feedback for the case of DCI in 2 slots (n = 2) and 2 TBs in each slotThe first 16 combinations are for ACK / NACKfor4 TBs (24) filled in the increasing order. The next 4 combinations are for DTX in the first slot, followed by the ACK / NACK in last DCI slot for 2 TBs (22)L= = 24+ 22= 20The number of feedback bits required is [log220] = 5An example of selecting combination of I = 3 slots from n - 1 = 5 slots • The total ways of selecting position of I = 3 DTX slots from n - 1 = 5 slots is• The combinations generated in the ascending lexicographic order are [{1,2,3}, {1,2,4}, {1,2,5}, {1,3,4}, {1,3,5}, {1,4,5}, {2,3,4}, {2,3,5}, {2,4,5}, {3,4,5}] indi- eating the slot positions that are being set to DTXA complete table of feedback index vs ACK / NACK / DTX in each slot for n = 3,, = 1 V i e 5 is shown in Error! Reference source not found..(slot position)1 2 3feedback Interpreted DTX slot A / N Index Binary string A / N I position(DJ ) combinations 0 0 0 0 N N N1 0 0 1 N N A2 0 1 0 N A N3 0 1 1 N A A4 1 0 0 A N N5 1 0 1 A N A6 1 1 0 A A N7 1 1 1 A A A8 0 0 0 D N N 1 1 N N 9 0 0 1 D N A 1 1 N A 10 0 1 0 D A N 1 1 A N 11 0 1 1 D A N 1 1 A N 12 0 0 0 N D N 1 2 N N 13 0 0 1 N D A 1 2 N A 14 0 1 0 A D N 1 2 A N 15 0 1 1 A D A 1 2 A A 16 0 0 0 D D A 2 1 2 N17 0 0 1 D D A 2 1 2 A Table 2

[0140] If the UE misses the PDCCH in the last one or more consecutive slots from among the slots map to the same UL slot for sending acknowledgments, the UE cannot determine that it missed the PDCCH because it does not get this information as part of the counter DAI. The gNB thus cannot determine whether or not and how many of the last few PDCCHs were missed based on the ACK / NACK feedback. However, the number of feedback bits may be conveyed by the UE, which can then be used to detect PDCCH DTX at the gNB for the last one or more consecutive slots, e.g., in the cases mentioned below.

[0141] The length of the feedback bits may be used to derive the number of scheduled slots whose DCIs the UE has successfully received. For example, a method as described with reference to Fig. 4, when the feedback information is provided for n slots comprises an indication of a number of bits in the feedback information may comprise determining, based on the indication of the number of bits that a control channel transmission scheduling a data transmission in the nth slot has not been received.

[0142] For example, the UE indicates the number of feedback bits, and the gNB detects the mismatch between the feedback size and the total DL TBs that it expects to be acknowledged. The mismatch is most likely due to PDCCH DTX of the last (or last consecutive) DL assignments that map on to the same UL slot for A / N. Even otherwise,the gNB L1 receiver may perform hypothesis testing to determine the number of bits transmitted by the UE, which can then allow the gNB to determine the DTX status of the last one or more DL grants that the UE may have missed.

[0143] The indication of the number of bits may be received on a physical layer.

[0144] When HARQ feedback is transmitted on PHY layer, PUCCH or PUSCH, by puncturing or multiplexing, it is decoded by L1 receiver at the gNB based on the information provided by MAC Layer 2 (L2).

[0145] L2 sends a decode request for feedback bits according to the scheduled n slots, but UE will create feedback bits only for the received <n slots, excluding the possibly one or more slots whose PDCCH the UE did not receive. Based on hypothesis testing, the gNB receiver can determine the number of bits transmitted by the UE and the corresponding bit fields. Using this information, the gNB can then determine whether or not the last one or more PDCCH messages were missed by the UE.

[0146] The indication of the number of bits may be received in a media access control control element on a physical uplink shared channel.

[0147] Fig. 11 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus. The apparatus may comprise, be, or be comprised in a UE.

[0148] In 1101, the method comprises receiving first information from a network entity, the first information relating to at least one scheduled data transmission in n slots.

[0149] In 1102, the method comprises receiving the at least one scheduled data transmission from the network entity. In 1103, the method comprises providing feedback information relating to the at least one scheduled data transmission to the network entity, wherein the feedback information comprises an indication of the number of the n slots for which the first information has been received.

[0150] Fig. 12 shows a flowchart of a method according to an example embodiment.

[0151] At 1201, the method comprises providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus in n slots.

[0152] At 1202, the method comprises providing the at least one scheduled data transmission to the user equipment.

[0153] At 1203, the method comprises receiving feedback information relating to the at least one scheduled data transmission from the user equipment, wherein the feedback information comprises an indication of the number of the n slots for which thefirst information has been received.

[0154] At 1204, the method comprises determining, based on the indication of the n slots for which information has been received that a control channel transmission scheduling a data transmission in the last one or more consecutive slot of the nth slots has not been received.

[0155] A method as described with reference to Fig. 11 may comprise providing feedback information relating to the at least one scheduled data transmission in a media access control control element, MAC CE, on a physical uplink shared channel and wherein a field of the MAC CE comprises the indication of the number of bits in the feedback information. If HARQ feedback is transmitted as MAC-CE (MAC Control Element) on PUSCH, the UE may indicate the length of the feedback bits as dynamic size information.

[0156] The feedback information may comprises ⌈log2L⌉ bits, where L is a sum of possible combinations of indications of either a first, acknowledgement, ACK, state, a second non-acknowledgement, NACK state and a third state indicative that a control channel transmission scheduling a further at least one data transmission has not been received for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

[0157] In both above cases, if there is a mismatch between transmitted slots and feedback information, the gNB may determine which grants are not received (DTXed) at the UE.

[0158] Methods as described with reference to Figs. 3 to 12 may be applied to all types of HARQ codebook (CB), e.g., Type-1, Type-2 CB etc. A similar solution may also be applied for carrier aggregation (CA).

[0159] Fig. 13 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof). In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof).

[0160] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods inaccordance with embodiments described herein.

[0161] As used herein, 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 / fi rmware 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 user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessors), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, 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.

[0162] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may, for example, be at least in part external to apparatus 10 but accessible to apparatus 10.

[0163] The instructions 15 may be comprised in a computer readable medium or a non-transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM).

[0164] For example, the apparatus 10 is a terminal device, such as a UE. As another example, the apparatus is comprised in such a terminal device, e.g. as a chipset configured to control the terminal device. The apparatus 10 may be caused or configured or comprise means to perform at least the method of Figs. 3, 8 and / or 11 and / or any one or more of the embodiments described herein.

[0165] As another example, the apparatus 10 is a network entity. In another embodiment, the apparatus is comprised in such a network entity, e.g. as a chipset configured to control the network entity. The apparatus 10 may be caused or configuredor comprise means to perform at least the method of Figs. 4, 9 and / or 12 and / or any one or more of the embodiments described herein.

[0166] The apparatus may comprise one or more entities of any of protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity or a PHY entity. In some embodiments, the entity is configured to perform at least the method of Figs. 4, 9 and 11, and / or any one or more of the embodiments described.

[0167] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0168] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0169] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods (or portion(s) thereof) as disclosed herein, and any of the embodiments (or respective portion(s) thereof). As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means forperforming C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C.

[0170] Even though this disclosure has been described above with reference to non-limiting and illustrative examples according to the accompanying figures, it is clear that the scope of this disclosure is not restricted thereto - but can be modified in many different ways. As technology advances, it will become apparent to a person skilled in art as to how the disclosure can be further implemented and / or modified in various ways. Further, it is clear to a person skilled in the art that the embodiments described herein may, but are not required to, be combined in various ways with other embodiments described herein.

Claims

CLAIMS1. An apparatus comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity;determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received; and providing feedback information relating to the at least one scheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second nonacknowledgement, NACK state.

2. The apparatus according to claim 1, wherein the first information indicates a count of downlink data transmissions from the network entity to be acknowledged by the apparatus and wherein determining that the control channel transmission has not been received comprises determining that the count is nonsequential.

3. The apparatus according to claim 1 or claim 2, wherein the first information comprises downlink control information.

4. The apparatus according to any of claims 1 to 3, wherein the feedback information comprises hybrid automatic repeat request, HARQ, information.

5. The apparatus according to any of claims 1 to 4, wherein the indication of the third state comprises a bit.

6. The apparatus according to any one of claims 1 to 5, wherein the feedback information is provided for n slots and comprises an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

7. The apparatus according to claim 6, wherein the feedback information is provided for one or more transport blocks per slot.

8. The apparatus according to claim 6 or claim 7, wherein the feedback information is provided for one or more component carriers.

9. An apparatus comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus;receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

10. The apparatus according to claim 9, wherein the first information indicates a count of downlink data transmissions from the network entity to be acknowledged by the apparatus.

11. The apparatus according to claim 9 or claim 10, wherein the first information comprises downlink control information.

12. The apparatus according to any of claims 9 to 11, wherein the feedback information comprises hybrid automatic repeat request, HARQ, information.

13. The apparatus according to any of claims 9 to 12, wherein the indication of the third state comprises a bit.

14. The apparatus according to any one of claims 9 to 13, wherein the feedback information is provided for n slots and comprises an indication of either the first, second and third state for the 1st to (n-1)th slots and an indication of either the first or second state of the nth slot.

15. The apparatus according to any one of claims 9 to 14, wherein the feedback information is provided for n slots and comprises an indication of a number of bits in the feedback information; andthe apparatus is caused to perform determining, based on the indication of the number of bits that a control channel transmission scheduling a data transmission in the nth slot has not been received.

16. The apparatus according to claim 15, wherein the apparatus is caused to perform re- ceiving the indication of the number of bits in a media access control control element on a physical uplink shared channel.

17. The apparatus according to claim 15, wherein the apparatus is caused to perform receiving the indication of the number of bits on a physical layer.

18. The apparatus according to claim 14, wherein the feedback information is provided for one or more transport blocks per slot.

19. The apparatus according to claim 14 or claim 18, wherein the feedback information is provided for one or more component carriers.

20. The apparatus according to any of claims 9 to 19, wherein the feedback information comprises ⌈log2L⌉ bits, where L is a sum of possible combinations of indications of either the first, second and third state for the 1st to (n-1)th slots and possible combinations of indications of either the first or second state of the nth slot.

21. A method comprising:receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity;determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received; andproviding feedback information relating to the at least one scheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

22. A method comprising, at an apparatus:providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus;receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

23. An apparatus comprising means for:receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity;determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received; andproviding feedback information relating to the at least one scheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

24. An apparatus comprising means for:providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus;receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises athird state other than a first, acknowledgement, ACK, state or a second nonacknowledgement, NACK state.

25. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform:receiving first information from a network entity, the first information relating to at least one scheduled data transmission from the network entity;determining, based on the first information, that a control channel transmission scheduling a further at least one data transmission has not been received; and providing feedback information relating to the at least one scheduled data transmission to a network entity, the feedback information comprising an indication that the control channel transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second nonacknowledgement, NACK state.

26. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform:providing first information to a user equipment, the first information relating to at least one scheduled data transmission from the apparatus;receiving feedback information relating to the at least one scheduled data transmission from the user equipment, the feedback information comprising an indication that a control channel transmission scheduling a further at least one data transmission has not been received, wherein the indication comprises a third state other than a first, acknowledgement, ACK, state or a second non-acknowledgement, NACK state.

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