HK1260369A1

HK1260369A1 - Efficient harq feedback

Info

Publication number: HK1260369A1
Application number: HK19120055.9A
Authority: HK
Inventors: Andreas BERGSTRÖM; Niclas Wiberg; Martin HESSLER
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-02-09
Filing date: 2016-06-01
Publication date: 2019-12-20

Description

Efficient HARQ feedback

RELATED APPLICATIONS

This application claims the benefit of provisional patent application serial No. 62/293,148 filed on 9/2016 and provisional patent application serial No. 62/295,722 filed on 16/2/2016, the disclosures of which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to downlink hybrid automatic repeat request (HARQ) feedback in a cellular communication network.

Background

Advanced Antenna Systems (AAS) are areas where technology has significantly advanced in recent years and where rapid technological development is anticipated over the next several years. Therefore, it is naturally assumed that AAS in general and massive Multiple Input Multiple Output (MIMO) transmission and reception in particular will be the cornerstone of future fifth generation (5G) cellular communication systems.

Beamforming has become increasingly popular and capable, and thus, beamforming is naturally used not only for the transmission of data but also for the transmission of control information. This is one motivation behind the (relatively) new control channels in Long Term Evolution (LTE), called enhanced physical downlink control channels (epdcchs). When beamforming is used for the control channel, the cost of transmitting overhead control information may be reduced due to the increased link budget provided by the additional antenna gain. This is a good feature, perhaps to a greater extent than is possible with the current LTE standard, which is also desirable for 5G.

For downlink hybrid automatic repeat request (HARQ) transmissions in LTE today, HARQ feedback is transmitted from a user equipment device (UE) to the network on a Physical Uplink Control Channel (PUCCH) or on a Physical Uplink Shared Channel (PUSCH) depending on whether the UE has scheduled uplink PUSCH transmissions. Thereafter, the network can draw conclusions on an individual HARQ process basis as to whether the last HARQ reception of that process was successful (acknowledgement/negative acknowledgement (ACK/NACK)) or even whether the downlink allocation reception failed (discontinuous transmission (DTX)).

The timing of the HARQ feedback transmitted in LTE is such that: for Frequency Division Duplex (FDD), feedback from one HARQ receiving process is received in the uplink in subframe n +4 if the corresponding downlink transmission for the receiving process of HARQ is in subframe n. Therefore, the delay between downlink transmission and corresponding HARQ feedback is 4 milliseconds (ms) in total. For Time Division Duplexing (TDD), the delay from downlink data transmission to uplink feedback reception may be greater than 4ms (or equivalently 4 subframes) in order to accommodate half-duplex downlink-uplink separation.

For 5G, HARQ feedback will be transmitted as part of Uplink Control Information (UCI) on xPUCCH. As used herein, "xPUCCH" is a term used to refer to a physical uplink control channel in future generation cellular communication networks (e.g., 5G).

The uplink control channel-xPUCCH may be transmitted on one Orthogonal Frequency Division Multiplexing (OFDM) symbol. The channel will provide a limited number of bits (e.g., 1 to 4 information bits) by either: having multiple fixed formats (similar to LTE PUCCH format 1/1a/1b) or having one single format, still allows for a flexible number of information bits. With respect to using a single format for a flexible number of information bits, it may be possible to improve performance with less use of information bits, as this allows unused information bits to be used as short training sequences. Furthermore, similar to LTE, it is assumed that there will be an implicit mapping from Downlink Control Information (DCI) Control Channel Elements (CCEs) to UCI CCEs.

Existing HARQ techniques are not 100% reliable, are inflexible, and consume a large amount of resources. Accordingly, there is a need for improved HARQ techniques, in particular HARQ techniques suitable for future generations of cellular communication networks, such as 5G cellular communication networks.

Disclosure of Invention

Systems and methods for providing efficient downlink hybrid automatic repeat request (HARQ) feedback are disclosed. In some embodiments, a method of operation of a wireless device in a cellular communication system comprises: downlink Control Information (DCI) is received from a radio access node in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The method further comprises transmitting downlink HARQ feedback to the radio access node in subframe T + K. In this way, HARQ feedback can be scheduled directly by the network, which in turn enables efficient HARQ feedback.

In some embodiments, the method further comprises combining the plurality of downlink HARQ feedback flags in a single downlink HARQ feedback transmission. Further, transmitting the HARQ feedback in subframe T + K includes transmitting a single downlink HARQ feedback transmission in subframe T + K. In some embodiments, combining the multiple downlink HARQ feedback flags into a single downlink HARQ feedback transmission comprises jointly encoding the multiple downlink HARQ feedback flags into a codeword for the single downlink HARQ feedback transmission.

In some embodiments, the DCI also includes information indicating which feedback flags are combined in a single downlink HARQ feedback transmission.

In some embodiments, the indication of timing offset K for HARQ is a value of timing offset K for HARQ. In other embodiments, the indication of the timing offset K for HARQ is a value S, where the timing offset K for HARQ is N + S, where N is a predefined value. In other embodiments, the indication of the timing offset K of HARQ is a value S, where the timing offset K of HARQ is N + S, where N is a preconfigured value. In other embodiments, the indication of the timing offset K of HARQ is a value S, where the timing offset K of HARQ is N + S, where N is a predetermined minimum timing offset of HARQ for the wireless device. In other embodiments, the indication of the timing offset K for HARQ is a value X, where the timing offset K for HARQ is a function of the value X.

In some embodiments, the HARQ feedback includes a HARQ feedback flag. The HARQ feedback flag is an Acknowledgement (ACK) if the wireless device successfully received the respective downlink data, a Negative Acknowledgement (NACK) if the wireless device did not successfully receive the respective downlink data, and an indication of DCI failure if the wireless device did not receive the respective DCI.

Embodiments of a wireless device are also disclosed. In some embodiments, a wireless device for a cellular communication system is adapted to receive DCI from a radio access node in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The wireless device is further adapted to transmit downlink HARQ feedback to the radio access node in subframe T + K. In some embodiments, the wireless device is further adapted to perform a method of operation of the wireless device according to any of the embodiments disclosed herein.

In some embodiments, a wireless device for a cellular communication system comprises a transceiver, at least one processor, and a memory storing instructions executable by the at least one processor, whereby the wireless device is operable to receive DCI from a radio access node in a first subframe T through the transceiver. The DCI includes an indication of the timing offset K of the HARQ. The wireless device, through execution of the instructions by the at least one processor, is further operable to transmit downlink HARQ feedback to the radio access node through the transceiver in subframe T + K.

In some embodiments, the wireless device, through execution of the instructions by the at least one processor, is further operable to combine the plurality of downlink HARQ feedback flags in a single downlink HARQ feedback transmission, wherein to transmit the downlink HARQ feedback in subframe T + K, the wireless device is operable to transmit the single downlink HARQ feedback transmission through the transceiver in subframe T + K. Further, in some embodiments, to combine the plurality of downlink HARQ feedback flags in a single downlink HARQ feedback transmission, the wireless device is further operable to jointly encode the plurality of downlink HARQ feedback flags in a codeword for the single downlink HARQ feedback transmission.

In some embodiments, the DCI also includes information indicating which feedback flags are to be combined in a single downlink HARQ feedback transmission.

In some embodiments, the indication of timing offset K for HARQ is a value of timing offset K for HARQ. In other embodiments, the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a predefined value. In other embodiments, the indication of the timing offset K of HARQ is a value S, where the timing offset K of HARQ is N + S, where N is a preconfigured value. In other embodiments, the indication of the timing offset K of HARQ is a value S, where the timing offset K of HARQ is N + S, where N is a predetermined minimum timing offset of HARQ for the wireless device. In other embodiments, the indication of the timing offset K for HARQ is a value X, where the timing offset K for HARQ is a function of the value X.

In some embodiments, the HARQ feedback includes a HARQ feedback flag. The HARQ feedback flag is ACK if the wireless device successfully received the respective downlink data, NACK if the wireless device did not successfully receive the respective downlink data, and an indication of DCI failure if the wireless device did not receive the respective DCI.

In some embodiments, a wireless device for a cellular communication system comprises means for receiving DCI from a radio access node in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The wireless device further comprises means for transmitting downlink HARQ feedback to the radio access node in subframe T + K.

In some embodiments, a wireless device for a cellular communication system comprises: a receiving module operable to receive DCI from a radio access node in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The wireless device further includes: a transmitting module operable to transmit downlink HARQ feedback to the radio access node in subframe T + K.

Embodiments of a method of operation of a radio access node in a cellular communication system are also disclosed. In some embodiments, a method of operation of a radio access node comprises: the DCI is transmitted to the wireless device in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The method further comprises the following steps: downlink HARQ feedback is received from the wireless device in subframe T + K.

In some embodiments, the downlink HARQ feedback in subframe T + K comprises: a single downlink HARQ feedback transmission in subframe T + K, which is a combination of multiple downlink HARQ feedback flags. Further, in some embodiments, a single downlink HARQ feedback transmission represents a joint encoding of multiple downlink HARQ feedback flags.

Embodiments of a radio access node for a cellular communication system are also disclosed. In some embodiments, the radio access node is adapted to transmit DCI to the wireless device in the first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The radio access node is further adapted to receive downlink HARQ feedback from the wireless device in subframe T + K. In some embodiments, the radio access node is further adapted to perform a method of operation of the radio access node according to any of the embodiments described herein.

In some embodiments, a radio access node for a cellular communication system comprises at least one radio unit, at least one processor, and memory storing instructions executable by the at least one processor, whereby the radio access node is operable to transmit DCI to a wireless device in a first subframe T via the at least one radio unit. The DCI includes an indication of the timing offset K of the HARQ. The radio access node is further operable, by execution of the instructions by the at least one processor, to receive downlink HARQ feedback from the wireless device in subframe T + K via the at least one radio unit.

In some embodiments, a radio access node for a cellular communication system comprises means for transmitting DCI to a wireless device in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The radio access node further comprises means for receiving downlink HARQ feedback from the wireless device in subframe T + K.

In some embodiments, a radio access node for a cellular communication system comprises: a transmitting module operable to transmit the DCI to the wireless device in a first subframe T. The DCI includes an indication of the timing offset K of the HARQ. The radio access node further comprises: a receiving module operable to receive downlink HARQ feedback from a wireless device in subframe T + K.

Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the embodiments in association with the accompanying drawing figures.

Drawings

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the disclosure.

Fig. 1 illustrates a cellular communication system according to one embodiment of the present disclosure;

fig. 2 illustrates operation of a wireless device (e.g., a user equipment device (UE)) and a radio access node (or other network node) according to one embodiment of the disclosure;

FIGS. 3A and 3B illustrate examples of embodiments of the present disclosure;

fig. 4 illustrates the operation of a wireless device and a radio access node (or other network node) according to another embodiment of the disclosure;

fig. 5A and 5B illustrate examples of some other embodiments of the present disclosure;

fig. 6 is a flow chart illustrating operation of a wireless device according to some embodiments of the present disclosure;

figures 7A and 7B and figure 8 illustrate problems related to bundled hybrid automatic repeat request (HARQ) feedback in a cellular communication system;

fig. 9 illustrates operations of a wireless device and a network node according to some embodiments of the present disclosure;

fig. 10 is a flow diagram illustrating a polling process performed by a network node according to some embodiments of the present disclosure;

fig. 11 is a flow chart illustrating a UE-side feedback process in accordance with some embodiments of the present disclosure;

fig. 12 is a flow chart illustrating a network side x physical uplink control channel (xPUCCH) detection procedure in accordance with some embodiments of the present disclosure;

fig. 13 is a flow diagram illustrating a network-side HARQ feedback interpretation process according to some embodiments of the present disclosure;

14A-14C, 15A-15C, 16A and 16B, 17A and 17B, and 18A and 18B illustrate examples according to various embodiments of the present disclosure;

fig. 19 and 20 are block diagrams of example embodiments of wireless devices according to some embodiments of the present disclosure; and

fig. 21-23 are block diagrams of example embodiments of base stations according to some embodiments of the present disclosure.

Detailed Description

The embodiments set forth below represent information that enables those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

The radio node: as used herein, a "radio node" is a radio access node or wireless device.

A radio access node: as used herein, a "radio access node" is any node in a radio access network of a cellular communication network, which is operable to wirelessly transmit and/or receive signals. Some examples of radio access nodes include, but are not limited to, base stations, e.g., enhanced or evolved node bs (enbs) in third generation partnership project (3GPP) Long Term Evolution (LTE) networks; high power or macro base stations; low power base stations such as, for example, micro base stations, pico base stations, home enbs, etc.; and a relay node.

The wireless device: as used herein, a "wireless device" is any type of device that accesses, i.e. is served by, a cellular communication network by wirelessly transmitting and/or receiving signals to a radio access node. Some examples of wireless devices include, but are not limited to, user equipment devices (UEs) and Machine Type Communication (MTC) devices in a 3GPP LTE network.

A network node: as used herein, a "network node" is any node that is part of a radio access network or part of the core network of a cellular communication network/system.

Note that the description given herein focuses on 3GPP cellular communication systems, and thus 3GPP LTE terminology or terminology similar to 3GPP LTE terminology is often used. However, the concepts disclosed herein are not limited to 3GPP systems.

Note that in the description herein, the term "cell" may be referred to; however, especially with respect to the fifth generation (5G) concept, beams may be used instead of cells, and it is therefore important to note that the concepts described herein are equally applicable to cells and beams.

Prior to discussing embodiments of the present disclosure, a discussion of some of the problems associated with existing hybrid automatic repeat request (HARQ) solutions is helpful. The current HARQ protocol of LTE is not 100% reliable; therefore, LTE also uses an Acknowledged Mode (AM) of higher layer Radio Link Control (RLC) to ensure reliability. Furthermore, current HARQ protocols are based on many strict timing relationships, such as, for example, the timing operation of each synchronous HARQ, which is very inflexible and causes several problems when, for example, dynamic Time Division Duplex (TDD) operation is used, which is very common for 5G as expected.

Furthermore, the HARQ feedback protocol for 5G is expected to be very fast and in particular much faster than LTE, but still without overusing the x physical uplink control channel (xPUCCH) resources. Therefore, what is desired is a HARQ feedback mechanism that can adapt in a rather dynamic way the feedback delay and xPUCCH resource consumption depending on e.g. the robustness and/or delay requirements of the user plane data service.

The present disclosure provides systems and methods related to downlink HARQ feedback that are particularly suitable for, but not limited to, future generation cellular communication networks, such as 5G networks. In some embodiments, feedback flags from multiple downlink HARQ transmissions are bundled in a single HARQ feedback transmission. In some embodiments, the network uses Downlink Control Information (DCI) to indicate to the UE which feedback flags should be combined in the HARQ feedback transmission and when and how it should be transmitted.

The present disclosure proposes a fast and efficient downlink HARQ feedback mechanism for e.g. 5G xPUCCH. In some embodiments, the mechanism allows a variable number of HARQ feedback flags (acknowledgement/negative acknowledgement (ACK/NACK)) to be included in one HARQ feedback transmission. Two different variants are proposed:

● direct scheduling, where each DCI will directly schedule one uplink feedback of ACK/NACK on xPUCCH.

● it is reported at the request of the network by polling, where the received results are stored in a feedback buffer. The reception result is, for example, ACK, NACK, or, in some embodiments, Discontinuous Transmission (DTX).

As described below, both variants also allow DTX detection, i.e. in case no DCI is heard.

Embodiments of the present disclosure provide a fast and efficient downlink HARQ feedback mechanism for e.g. 5G xPUCCH. It regulates the amount of xPUCCH resources used per UE, but allows very fast feedback. Furthermore, embodiments of the downlink HARQ feedback mechanism disclosed herein may be fully scheduled by the network, such that it may dynamically adapt in terms of resource consumption and feedback delay depending on user plane service requirements. Embodiments of the downlink HARQ feedback mechanism disclosed herein allow for DTX detection.

Embodiments of the present disclosure are implemented in a cellular communication system or network. One non-limiting example of a cellular communication system 10 is illustrated in fig. 1. As shown, the cellular communication system 10 includes: a Radio Access Network (RAN)12, which includes a plurality of radio access nodes, which in this illustrated example are base stations. The base stations 14 are sometimes referred to herein more generally as radio access nodes 14. In 3GPP, the base station 14 may be, for example, an eNB or a low power base station (e.g., a pico base station, a micro base station, a femto base station, or a home base station). The base station 14 provides radio access to wireless devices 18 (such as, for example, UEs) in a corresponding cell 16 of the base station 14. Note that although a cell 16 is shown in the example of fig. 1, in other embodiments, the base station 14 may transmit on multiple beams. In this example, the base station 14 communicates via an X2 connection or more generally through a base station-to-base station connection. In addition, the base stations 14 are connected to a core network 20, the core network 20 including various core network nodes, such as, for example, one or more Mobility Management Entities (MMEs) 22, one or more serving gateways (S-GWs) 24, and one or more packet data network gateways (P-GWs) 26.

HARQ feedback for direct scheduling

In some embodiments, each DCI schedules feedback to be transmitted at a later opportunity given one of the included subframe offsets K. The DCI scheduled at subframe T will then cause feedback at subframe T + K.

In some related embodiments, the configuration of K may be provided, for example, in part, by, for example, a look-up table (which is conveyed via, for example, a higher layer signal or hard-coded in the specification). For example, assuming that the minimum possible K is N, which is the reaction time of the wireless device 18, instead of transmitting K N, K-N +1, K-N +2, etc., the network may instead signal S0, S-1, S-2, etc. in the DCI, and then signal the value N, respectively, after which the wireless device 18 calculates K as K-S + N. Note that, at least in some embodiments, the value of N may be signaled only once (e.g., by higher layer signaling) or may be an attribute of the wireless device 18 that is already known by the network from, for example, an earlier performed RRC connection procedure. The value of S may vary. For example, the value of S may be changed by including the value of S in each respective DCI message, where the value of S may vary from one DCI message to another DCI message.

Fig. 2 illustrates the operation of the wireless device 18 and the radio access node 14 or other network node operating according to, for example, the above embodiments. As shown, the radio access node 14 or some other network node optionally configures, at least in part, an offset K (step 100) that is used to determine the time (T + K) at which the wireless device 18 will transmit HARQ feedback upon receiving a DCI message. Likewise, T is a subframe, or more generally a time at which a DCI message is received, and T + K is a subframe, or more generally a time at which HARQ feedback is to be transmitted. Thus, T is sometimes referred to herein as the current subframe, and K is referred to herein as the timing offset K of HARQ or simply offset K. As described above, such configuration of the offset K may include signaling, e.g., a lookup table, used by the wireless device 18 to determine the value of K, e.g., from an index transmitted in a corresponding DCI message. As another example discussed above, the configuration may be a configuration of a value S for determining the offset K, e.g., from K ═ N + S, where S is included in the corresponding DCI message and N is a predetermined value, such as, for example, a predetermined reaction time of the wireless device 18.

At some point, the wireless device 18 receives a DCI message from the radio access node 14 (step 102), where the DCI message includes an indication of an offset K. The indication of the offset K may be the value of K, or some value that may be used by the wireless device 18 to determine the value of K, for example, i.e., K may be a function of the value X passed by the indication. For example, the indication of the offset K may be the value S, where the offset K ═ N + S, where N may be predefined, e.g. by a standard, or configured by the network, e.g. provided in the configuration of step 100.

In some embodiments, the wireless device 18 receives a single DCI message and causes transmission of HARQ feedback (which includes a single HARQ flag) in step 106 below. However, in other embodiments, the wireless device 18 receives multiple DCI messages including the DCI message of step 102 and potentially additional DCI messages in previous subframes. Thus, if there are multiple DCI messages, these DCI messages may have respective HARQ timing offsets K, which result in respective HARQ feedback being transmitted in the same subframe. Thus, in some embodiments, the wireless device 18 combines multiple HARQ feedback flags to provide HARQ feedback transmitted by the wireless device at subframe T + K (step 104). Note, however, that step 104 is optional. As described below, the manner in which the wireless device 18 combines multiple feedback flags may vary depending on the particular embodiment/implementation. For example, the wireless device 18 may concatenate bit patterns representing multiple HARQ feedback flags or jointly encode multiple HARQ feedback flags in a single codeword. As an alternative to one example of combining HARQ feedback flags, the wireless device 18 may transmit the HARQ feedback flags in a separate Uplink Control Information (UCI) message.

The wireless device 18 transmits downlink HARQ feedback in subframe T + K (step 106). As described herein, in some embodiments, the HARQ feedback is a downlink HARQ flag for a single downlink data transmission scheduled by the DCI message in subframe T. In this case, the downlink HARQ flag is ACK if the wireless device 18 successfully receives the downlink data scheduled by the DCI message in the subframe T, and NACK if the wireless device 18 does not successfully receive the downlink data scheduled by the DCI message in the subframe T.

In some other embodiments, the HARQ feedback comprises downlink HARQ feedback for multiple downlink transmissions. For example, multiple downlink transmissions may be transmitted through subframe T₁、T₂、...、T_MIn the respective DCI message received, wherein the respective HTiming offset K for ARQ₁、K₂、...、K_MSo that the HARQ feedback for all these downlink transmissions occurs in the same subframe, i.e. T₁+K₁＝T₂+K₂＝...＝T_M+K_M. The HARQ feedback may then comprise a plurality of downlink HARQ flags, e.g. mapped to separate physical resources, e.g. Resource Elements (REs) in xPUCCH, e.g. in separate UCI messages. Alternatively, the HARQ feedback may comprise a single combined feedback provided by step 104, which collectively represents the plurality of downlink HARQ flags, e.g. as a result of jointly encoding the plurality of downlink HARQ flags in a single codeword, or as a result of concatenating a plurality of bit patterns representing the plurality of downlink HARQ flags. In some embodiments, the downlink HARQ flags include ACKs and NACKs, depending on whether the wireless device 18 successfully received the respective downlink data transmission (e.g., a data transmission on a Physical Downlink Shared Channel (PDSCH)). Further, in some embodiments, the downlink HARQ flags include DTX, i.e., a flag indicating an error or failure in DCI reception, if the wireless device 18 did not successfully receive the respective DCI message.

The radio access node 14 receives and processes HARQ feedback according to any desired HARQ feedback processing scheme (step 108). For example, if a NACK is received, the radio access node 14 retransmits the downlink data.

In some embodiments, the radio access node 14 is able to detect DCI errors or failures based on HARQ feedback. This is referred to herein as DTX or DCI failure/error. In some embodiments, DTX detection (i.e., DCI failure) may be achieved by either:

● have a different (explicit) mapping of each received DCI to a given set of physical resources/REs on xPUCCH. In other words, multiple separate UCI messages are transmitted simultaneously using different resources. If the network does not receive anything at one particular resource/resource element, it may be interpreted as if the wireless device 18 failed to decode the corresponding DCI.

● explicitly encodes DTX as a separate code point in the feedback, e.g., let 00-ACK, 01-ACK

DTX、11＝NACK、....

● joint coding of multiple HARQ feedbacks. In this case, when the wireless device 18 prepares xPUCCH transmission, the wireless device 18 combines the feedback flags to be transmitted at a single code point mapped to the codeword transmitted on xPUCCH. For example, if up to four feedback flags may be included in a HARQ feedback transmission, the code point may be calculated as f₁+3f₂+9f₃+27f₄Wherein f is₁...f₄Is a feedback flag encoded as ACK-1, NACK-2 and DTX-0.

DTX means that no transmission is detected for this flag. Note that multiple HARQ feedbacks may be combined in a similar manner without joint coding, e.g., in HARQ transmission, each feedback is represented by several bits (e.g., two bits in the example in the previous point).

An example of the process of fig. 2 is illustrated in fig. 3A and 3B. In the first example shown in fig. 3A, the DCI message and downlink data are both successfully decoded for subframes T, T +1, T +2 and T +3, and HARQ feedback flags, ACK and ACK, respectively, are transmitted in subframe P. These four feedback flags may be jointly encoded or otherwise combined in a single feedback/bit pattern, or may be transmitted in separate physical resources (e.g., in separate UCI messages). In the second example shown in fig. 3A, the DCI message for sub-frames T, T +1, T +2, and T +3 was successfully decoded, the downlink data for sub-frames T, T +2 and T +3 was successfully decoded, and the downlink data for sub-frame T +1 was not successfully decoded, i.e., there was a PDSCH error. The appropriate HARQ feedback flags (ACK, NACK, ACK) are transmitted by the wireless device 18 in subframe P. Again, these four feedback flags may be jointly encoded or otherwise combined in a single feedback/bit pattern, or may be transmitted in separate physical resources (e.g., in separate UCI messages).

In the third example illustrated in fig. 3B, the DCI message for sub-frames T, T +2 and T +3 was successfully decoded, the DCI message for sub-frame T +1 was not successfully decoded, i.e., there is a DCI error in sub-frame T +1, and the downlink data for sub-frames T, T +2 and T +3 was successfully decoded. The wireless device 18 transmits the appropriate HARQ feedback flags (ACK, DTX, ACK) in subframe P. Again, these four feedback flags may be jointly encoded or otherwise combined in a single feedback/bit pattern, or may be transmitted in separate physical resources (e.g., in separate UCI messages). Finally, in the fourth example illustrated in fig. 3B, the scenario is the same as in example 1, except that no wireless device 18 is scheduled in subframe T + 1. In this example, the UE transmits the appropriate HARQ feedback flags (ACK, DTX, ACK) in subframe P. Again, these four feedback flags may be jointly encoded or otherwise combined in a single feedback/bit pattern, or may be transmitted in separate physical resources (e.g., in separate UCI messages).

HARQ feedback through polling

In some embodiments, each DCI message contains an index to a HARQ feedback buffer, where the reception status (ACK (a)/NACK (N) or at least in some embodiments DTX or DCI error (D)) for the indexed reception is stored.

In some related embodiments, the network will explicitly poll the status reports of the HARQ feedback buffers, which will also clear the status of the HARQ feedback buffers. Assuming that the HARQ feedback delay for wireless device 18 is d subframes, the poll received at subframe T will result in feedback at subframe T + d. In some embodiments, the HARQ feedback delay d may be a static delay, e.g., four subframes. In other embodiments, the HARQ feedback delay d may be a configurable delay. In particular, in some embodiments, the above-described polling may also contain explicit details regarding when to transmit feedback in a manner similar to that described above for the configuration of timing offset K for HARQ. That is, in some embodiments, d-K, where K is the timing offset K of the HARQ described above.

In yet further related embodiments, DTX detection (i.e., DCI failure) may be implemented by any of the following:

● have a different mapping of each HARQ feedback buffer entry to a given set of physical resources/resource elements. If the network does not receive anything at a particular resource/resource element, it may be interpreted as if the wireless device 18 failed to decode the corresponding DCI.

● explicitly encodes DTX as a separate code point in the feedback.

example 1 let 00 ═ ACK, 01 ═ DTX, and 11 ═ NACK, respectively.

this would therefore require 3 x2 x 54 code points, which may be coded, for example, by an appropriate block code of at least 6 bits, i.e. 2 x 6 x 64> 54.

An example of the polling process described above is illustrated in fig. 4. As shown, the radio access node 14 transmits and the wireless device 18 receives in a subframe T₁Is a first DCI message on a downlink control channel (step 200), referred to herein as an x physical downlink control channel (xPDCCH). The first DCI message includes: downlink grant indicating at subframe T₁The mid downlink data will be transmitted to the wireless device 18. In addition, the first DCI message includes an index to a location in the HARQ feedback buffer where the respective downlink HARQ flag, e.g., ACK, NACK, or DTX, is to be stored. The radio access node 14 also transmits the downlink grant in the subframe T according to the downlink grant included in the first DCI message₁To the wireless device 18 (step 202). The wireless device 18 is in a position defined by the index included in the first DCI messageA downlink HARQ flag, also referred to herein as a receive state, is stored in a HARQ feedback buffer at step 204. In some embodiments, if the wireless device 18 is in subframe T₁The stored downlink HARQ flag is ACK if the downlink data was successfully received/decoded, or if the wireless device 18 is in subframe T₁If the downlink data is not successfully received/decoded, the stored downlink HARQ flag is NACK. However, as described below, in some embodiments, the storage scheme may be modified. In some embodiments, the HARQ feedback buffer is initialized to DTX at all locations. Thus, if the wireless device 18 fails to receive the first DCI message, the DTX flags are maintained in respective locations in the HARQ feedback buffer.

In the same way, the radio access node 14 transmits and the wireless device 18 receives in the subframe T₂In a second DCI message on a downlink control channel (step 206), referred to herein as xPDCCH. The second DCI message includes a downlink grant indicating that in subframe T₂The mid downlink data will be transmitted to the wireless device 18. In addition, the second DCI message includes an index to a location in the HARQ feedback buffer where the respective downlink HARQ flag, e.g., ACK, NACK, or DTX, is to be stored. The radio access node 14 also transmits the downlink grant in the subframe T according to the downlink grant included in the second DCI message₂To the wireless device 18 (step 208). The wireless device 18 stores a downlink HARQ flag, also referred to herein as a receive state, in a HARQ feedback buffer at a location defined by an index included in the second DCI message (step 210). In some embodiments, if the wireless device 18 is in subframe T₂The stored downlink HARQ flag is an ACK if the downlink data was successfully received/decoded or if the wireless device 18 is in a subframe₂If the downlink data is not successfully received/decoded, the stored downlink HARQ flag is NACK. However, as described below, in some embodiments, the storage scheme may be modified. In some embodiments, the HARQ feedback buffer is initialized to DTX at all locations. This is achieved byLikewise, if the wireless device 18 fails to receive the second DCI message, the DTX flags are maintained in respective locations in the HARQ feedback buffer.

The process continues in this manner until the radio access node 14 transmits and the wireless device 18 receives the data contained in the subframe T_MThe DCI message of the polling indicator in (step 212). In this example, the DCI message also includes a reference frame for subframe T_MAnd a HARQ buffer index for the corresponding downlink HARQ flag. Thus, the radio access node 14 is dependent on the time in the subframe T_MIn the subframe T, the downlink grant included in the DCI message transmitted in_MTo the wireless device 18 (step 214). The wireless device 18 is in subframe T_MStores a downlink HARQ flag, also referred to herein as a receive state, in a HARQ feedback buffer at a location defined by an index included in the transmitted DCI message (step 216). In some embodiments, if the wireless device 18 is in subframe T_MIf the downlink data is successfully received/decoded, the stored downlink HARQ flag is ACK, or if the wireless device 18 is in subframe T_MIf the downlink data is not successfully received/decoded, the stored downlink HARQ flag is NACK. However, in some embodiments, the storage scheme may be modified, as described below. In some embodiments, the HARQ feedback buffer is initialized to DTX in all positions. Thus, if the wireless device 18 is in subframe T_MFails to receive the DCI message, DTX flags are maintained in respective locations in the HARQ feedback buffer.

Upon receiving the polling indicator, the wireless device 18 transmits HARQ feedback, e.g., on xPUCCH (step 218), which represents a HARQ feedback flag stored in the HARQ feedback buffer. In sub-frame T_MHARQ feedback is transmitted in + d, where delay d may be a static delay or a configurable delay, e.g., a configurable HARQ timing offset K in some embodiments. In some embodiments, the plurality of HARQ feedback flags in the HARQ feedback buffer may be transmitted in respective physical resources (e.g., in respective UCI messages). In other embodiments, multiple HARQ feedback flags are combined to provide combined HARQ feedback for the transmission. The combined HARQ feedback may be a concatenation of bit patterns representing multiple HARQ flags. For example, if the HARQ flags are ACK 00 and NACK 01 and there are four locations in the HARQ feedback buffer, the combined HARQ feedback may be 00000001. As another example, the combined HARQ feedback may be a codeword obtained by jointly encoding a plurality of HARQ flags.

The radio access node 14 detects the HARQ feedback (step 220) and interprets the HARQ feedback (222). Once the HARQ feedback is detected and interpreted, the radio access node 14 takes appropriate action(s), e.g. re-transmits the data.

Fig. 5A and 5B illustrate an example of this process, with corresponding flow charts illustrating the operation of the wireless device 18 in fig. 6. Note that in fig. 5A and 5B, the index and the poll in the DCI are separately encoded. They can of course be jointly coded, for example:

00 ═ feedback storing an index of 0

01 ═ feedback storing index 1

Store index 3 feedback 10 ═ store

Store feedback for index 3, then transmit feedback/flush buffer after N subframes

As shown in fig. 5A, in a first example, the wireless device 18 receives a DCI message with a buffer index 00 and, thus, in the HARQ feedback buffer, stores the respective HARQ feedback flags at the buffer location corresponding to index 00. In the next subframe, the wireless device 18 receives the DCI message with the polling buffer index 01 and thus stores the respective HARQ feedback flag in the HARQ feedback buffer at the buffer location corresponding to index 01. Later, the wireless device 18 receives another DCI message with polling buffer indices 02 and 13, respectively, in the subframe and, thus, stores the respective HARQ feedback flags in the HARQ feedback buffer at the buffer locations corresponding to the indices 02 and 13. The network 14, e.g., a radio access node, polls the wireless device 18 for HARQ feedback. In response to being polled by the network, the wireless device 18 transmits HARQ feedback stored in a HARQ feedback buffer in subframe T + d, in this example where the wireless device 18 is polled in subframe T, for example, and the value d may be a static value or a configurable value configured by the network as described above, e.g., a timing offset K for HARQ. Examples 2 and 3 of fig. 5A and 5B are similar to the first example, but where there is a PDSCH error in the second subframe (example 2) and a DCI error in the second subframe (example 3).

Fig. 6 is a flow chart illustrating the operation of the wireless device 18 according to some embodiments of the present disclosure. Note that in some embodiments, the HARQ feedback buffer is initialized so that all locations are set to some default value, which in the example embodiments described herein is DTX. Note that the dashed boxes represent optional steps. As shown, the wireless device 18 first waits for receipt of a DCI message (steps 300 and 302). Upon receiving the DCI message, the wireless device 18 stores the appropriate HARQ flag (ACK or NACK) in the HARQ feedback buffer for the given index (step 304), which is provided, for example, in the DCI message. The process returns to step 300 and may repeat until the wireless device 18 is polled by the network (yes, step 306). Note that in some embodiments, step 306 is optional in that, for example, the wireless device 18 may automatically send feedback upon reaching a final position in the HARQ feedback buffer. This may be considered an implicit poll.

While being polled, the wireless device 18 creates an xPUCCH message based on the status of the HARQ feedback buffer (step 308). For example, in some embodiments, the wireless device 18 combines the downlink HARQ flags stored in the HARQ feedback buffer to provide combined HARQ feedback, i.e., a combined downlink HARQ feedback message. The combined HARQ feedback may be, for example, a concatenation of bit patterns/sequences for each downlink HARQ flag, or as another example, a single codeword resulting from jointly encoding the HARQ flags stored in the HARQ feedback buffer. The xPUCCH message includes, for example, a HARQ feedback flag stored in a HARQ feedback buffer in a coded form. The wireless device 18 clears the HARQ feedback buffer (step 310), e.g., sets all entries to DTX. The wireless device 18 waits d subframes (step 312) and then transmits the created xPUCCH message on the xPUCCH (step 314). Note that the value d (i.e. the HARQ feedback delay) may be a predefined value (e.g. a static value defined by the standard), or a configured value configured by the network, e.g. in a manner similar to the configuration of the timing offset K of HARQ

In some embodiments, the HARQ feedback delay d is a device-specific value, defined, for example, by a processing delay of the wireless device 18. In this case, different wireless devices 18 may have different device-specific delays, the device-specific delay being from the time the wireless device 18 receives the DCI message until the time the wireless device 18 transmits UCI (or more generally, HARQ feedback), more than one wireless device 18 may transmit UCI messages at the same time (i.e., in the same subframe). This presents a problem in that simultaneous transmissions of UCI messages collide. This problem can be solved by any of the following methods:

● use explicit signaling to indicate UCI resources for the wireless device 18 rather than an implicit DCI to UCI mapping. The explicit signaling may be signaling of an indication of the value of d to be used by the wireless device 18, e.g., signaling the HARQ offset timing K, as described above.

● assign wireless devices 18 with different processing delays to different frequency resources.

● schedule wireless devices 18 with different processing delays on different DCI Control Channel Elements (CCEs).

● avoid scheduling a new wireless device 18 that will transmit UCI that conflicts with an already scheduled UCI to be transmitted by another wireless device 18.

Advanced HARQ feedback

The HARQ feedback solution for xPUCCH in 5G as described above may encounter problems when HARQ feedback, e.g. in the form of HARQ feedback reports, is not received due to DCI errors on the downlink and/or due to xPUCCH errors on the uplink.

As shown in fig. 7A and 7B and fig. 8, in these cases the network cannot draw any conclusions about successful and/or unsuccessful reception of PUSCH transmissions that will be covered by the non-received reports. In addition, the network may even conclude erroneously in believing that the unreceived transmission was acknowledged (e.g., NACK → ACK error), which would result in expensive higher layer retransmissions.

Specifically, fig. 7A and 7B illustrate two problems, which are referred to as problem a and problem B. In problem a, a DCI error results in the wireless device 18 not receiving a polling request/indicator in subframe SF # (J). Since no polling indicator is received, the HARQ feedback buffer is not cleared, i.e., all locations in the HARQ feedback buffer are not reset to DTX, and wireless device 18 does not transmit HARQ feedback to the network in subframe SF # (J + 2). Thus, in this example, in subframe SF # (J +1), a NACK is stored in the first location in the HARQ feedback buffer, where the NACK overwrites/conceals an ACK in the HARQ feedback buffer that was not transmitted to the network as a result of a DCI error in subframe SF # (J). In subframe SF # (J +2), a NACK is stored in a second location in the HARQ feedback buffer, where the NACK overwrites/conceals an ACK in the HARQ feedback buffer that was not transmitted to the network as a result of a DCI error in subframe SF # (J). Error in subframe SF # (J). In subframe SF # (J +3), an ACK is stored in a third location in the HARQ feedback buffer, where the ACK overwrites/conceals a NACK in the HARQ feedback buffer that was not transmitted to the network as a result of a DCI error in subframe SF # (J). In subframe SF # (J +4), ACK is stored in the fourth location in the HARQ feedback buffer, where the ACK overwrites/conceals DTX in the HARQ feedback buffer that was not transmitted to the network as a result of DCI error in subframe SF # (J). In problem B, xPUCCH feedback is lost in the uplink, so that xPUCCH is not received in subframe SF # (J + 2).

Note that the network does not know how to distinguish between questions a and B. In both problems a and B, at subframe SF # (J +2), the network will not receive any HARQ feedback for downlink transmissions in subframes SF # (J-3), SF # (J-2), SF # (J-1), and SF # (J), and the network cannot draw any conclusions about these downlink transmissions. At subframe SF # (J +7), the network will retransmit all HARQ processes being negatively acknowledged, i.e. those of buffer indices 0 and 1, which correspond to downlink transmissions of subframes SF # (J +1) and SF # (J + 2). The network will similarly assume that downlink transmissions for subframes SF # (J +3) and SF # (J +4) are acknowledged. This is completely correct, but the network does not know the reception status of subframes SF # (J-3), SF # (J-2), SF # (J-1), and SF # (J), because the corresponding status flags have been overwritten by new status flags.

Fig. 8 illustrates a problem (problem C) resulting in a case where there are a plurality of consecutive DCI errors. In addition to the problem of problem a of fig. 7A, for problem C, a DCI error at subframe SF # (J +1) will cause the entry with index 0 in the HARQ feedback buffer to not be updated. This in turn will cause the network to erroneously assume at subframe SF # (J +7) that the corresponding downlink transmission has been acknowledged, while in fact it should have been indicated as DTX.

As described above, embodiments of the present disclosure enhance the HARQ feedback solution for xPUCCH in 5G. Note that the term xPUCCH is used herein to refer to the uplink control channel, especially in 5G networks. However, the name xPUCCH is only for clarity and ease of discussion, and the actual uplink control channel may be given a different name in 5G. An overview of the present disclosure is summarized in fig. 9, which is described below. Most importantly, the embodiments of the present disclosure:

● ensure that the wireless device 18 does not simply replace the previously received old state (ACK/NACK/DTX) with the new state, but rather uses a more complex procedure (see fig. 11 and corresponding description below); and

● ensure that the network correctly interprets the lack of feedback (DCI error or xPUCCH error) and takes appropriate action in response thereto (see fig. 12 and corresponding description below).

With the enhancements disclosed herein, the above-described HARQ feedback solution is made more robust against control channel errors in the downlink (i.e., DCI errors) and control channel errors in the uplink (i.e., xPUCCH errors). It ensures that expensive DTX/NACK → ACK errors (which would trigger higher layer retransmissions) are mitigated at the expense of some extra HARQ retransmissions (which are not expensive). As an additional reward, it implicitly explains the lack of HARQ feedback as quickly as possible, thus providing the shortest possible HARQ Round Trip Time (RTT).

Details of embodiments of the enhanced HARQ feedback solution are largely provided by the flowcharts of fig. 9-13. The following section of this section provides some more detailed descriptions and possible embodiments for these figures. Further, illustrations of the present disclosure in use are shown in the examples of fig. 14A to 14C, 15A to 15C, 16A and 16B, 17A and 17B, and 18A and 18B.

Note that the following discussion focuses on a polled HARQ feedback solution, as this is the most complex; however, as described below, the enhancement may also be applied to a directly scheduled HARQ feedback solution.

Fig. 9 illustrates an overview/algorithm profile for the overall HARQ feedback process. In particular, fig. 9 illustrates how the individual processes of fig. 10-13, 14A-14C, 15A-15C, and 16A and 16B work together. As shown, the network (e.g., radio access node 14) transmits DCI messages on a control channel (which is referred to as xPDCCH) and also transmits downlink data on a downlink shared channel (which is referred to as xPDSCH). At the UE/wireless device 18, the wireless device 18 performs a UE-side feedback process that results in HARQ feedback being transmitted to the network. On the network side, a network-side HARQ feedback interpretation process (one per HARQ process) is performed to interpret the HARQ feedback from the wireless device 18 and take appropriate action.

FIG. 10 is a flow diagram illustrating a network-side polling process according to some embodiments of the present disclosureAnd (4) a flow chart. In some embodiments, the network side polling procedure is performed by the radio access node 14. The network will ensure that for each xPDSCH transmission, the scheduled HARQ process is associated with a locally unique Buffer Index (BI), which is also indicated in the DCI. The BI is an index to the HARQ feedback buffer at the wireless device 18 that defines where the corresponding HARQ flags within the HARQ feedback buffer will be stored. At the execution of BI_MAXAfter such transmission, a polling bit is set in DCI. Here BI_MAXCorresponding to the size of the HARQ feedback buffer at the wireless device 18. Note that xPDSCH is used herein as the name of PDSCH in a 5G network for clarity and ease of discussion. However, the actual name of the downlink shared channel in a 5G network may be given another name. In some embodiments, BI_MAXA predetermined value is given by, for example, a relevant specification, while in other embodiments it may be statically or semi-statically configured by, for example, higher layer signaling. In other embodiments, it may be dynamically set in the DCI. Note that for the "direct scheduling" case described above, it is obvious that the polling portion may be omitted.

In particular, as shown, the process begins at step 400, and BI is set to 0 (step 402). The radio access node 14 determines whether downlink data transmissions are scheduled for the wireless device 18 (which is referred to as a user) for the current subframe (step 404). If not, the radio access node 14 waits until the next subframe (step 406) and then the process returns to step 404. If a downlink data transmission is scheduled for the wireless device 18 (step 404; yes), the radio access node 14 associates the respective HARQ process for transmission with the current BI (step 408) and includes the BI in a respective DCI message with a downlink grant to be transmitted to the wireless device 18 (step 410). The radio access node 14 determines whether the BI is equal to the BI_MAX(step 412). If not, BI is incremented (step 414) and the process proceeds to step 406. Once the BI reaches the BI_MAX(step 412; yes), the radio access node 14 sets a poll flag/indicator in the DCI message to be transmitted to the wireless device 18 (step 416) and thenThe process returns to step 402.

Fig. 11 illustrates a feedback process on the UE side or wireless device side in accordance with some embodiments of the present disclosure. The process is the same as that of fig. 6, but provides an enhancement to the storing step 304. In general, the feedback procedure involves when the wireless device 18 tries to decode a DCI message indicating at least an xPDSCH transmission-and possibly also the xPDSCH transmission itself. As previously described, the DCI message includes the BI and a poll indicator (which may be in the form of, for example, a poll bit). The wireless device 18 maintains a HARQ feedback buffer in which the reception status (ACK/NACK/DTX) is stored. After each poll, the HARQ feedback buffer is typically cleared, i.e. all entries are reset to DTX. Each entry in the HARQ feedback buffer is indexed with the previously described BI.

In this embodiment, rather than simply replacing the old reception state (also referred to herein as the HARQ flag) with the currently received reception state, the wireless device 18 instead uses an enhanced stored procedure that will allow the network to make a better and more informed explanation of the HARQ feedback later on at reception. This is important in the case with DCI errors, where the HARQ feedback buffer has not been cleared by polling because no polling indicator was received.

In some embodiments, already stored NACKs in one entry of the HARQ feedback buffer will be maintained even if the current reception corresponding to that buffer entry (i.e. the same BI) is successful and thus will indicate an ACK. However, if the current reception (i.e., the same BI) corresponding to that buffer entry is unsuccessful, the stored ACK will always be overwritten by a NACK for robustness. An example of use is given in example 8 of fig. 16B.

In some other embodiments, the stored value of the previous buffer entry (which has a modulo (BI) by the expression (BI-1) is in the case that the buffer index is not indicated in the previous DCI_MAX+1) its buffer index given) is replaced with DTX. This may happen in the very case of a DCI error for the transmissionAnd (4) generating. Such an implicit DTX flag would, for example, prevent error propagation in terms of the most important NACK → ACK error. An example of use is given in example 9 of fig. 17A and 17B.

Again, it is noted that for the above directly scheduled HARQ feedback solution, the polling part can obviously be omitted, otherwise the rest should be applicable.

As shown in fig. 11, the enhanced storage process is as follows. Upon receiving the DCI message (yes, step 302), the wireless devices 18 determine whether the respective downlink data has been successfully received (step 500). If so, the wireless device 18 determines whether the entry in the HARQ feedback buffer for the BI included in the DCI message is a NACK (step 502). If not, the wireless device 18 stores the ACK in the location/entry in the HARQ feedback buffer indicated by the BI included in the received DCI message (step 504). Conversely, if the entry in the HARQ feedback buffer for the BI included in the received DCI message is a NACK, the wireless device 18 stores or otherwise maintains the NACK in the entry in the HARQ feedback buffer for the BI included in the received DCI message (step 506). In this way, the previous NACK is not concealed or overwritten by an ACK. Returning to step 500, if the wireless device 18 did not successfully receive the downlink data, the wireless device 18 stores a NACK in the HARQ feedback buffer at the location/entry indicated by the BI included in the DCI message (step 506).

Optionally, the process may continue to detect a previous DCI error. In this regard, whether proceeding from step 504 or step 506, the wireless device 18 sets the BI_PREVBI (step 508), and then set up BI_PREV＝(BI_PREV-1) mode (BI)_MAX+1) (step 510). Step 510 indexes BI_PREVSet to be at the possible BI value {0, 1.,. BI_MAXThe previous index in the sequence of. In addition, note that the equations given in step 510 assume that BI is an unsigned integer. If signed integers are used, the equation becomes BI_PREV＝(BI_PREV+BI_MAX) Mold (BI)_MAX+1). The wireless device 18 then communicates the BI_PREVAnd BI_LASTMaking a comparison wherein BI_LASTIs the BI included in the most recent previous successfully received DCI message. Thus, if BI_PREVNot being equal to BI_LASTThis means that there is a previous DCI error. Thus, if BI_PREVNot being equal to BI_LASTThen the wireless device 18 is at BI_PREVThe DTX is stored in the HARQ feedback buffer at the defined location (step 514) and the process returns to step 510. Note that if there are multiple consecutive DCI errors, then the process will detect those DCI errors and store the DTX in the respective HARQ feedback buffer location. Once BI has finished_PREV＝BI_LASTMeaning that there are no more DCI errors, the wireless device 18 will BI_LASTSet to BI (step 516). The process then proceeds to step 306, as described above with reference to fig. 6.

Fig. 12 is a flowchart illustrating a network side xPUCCH detection procedure according to some embodiments of the present disclosure. The process is performed by a network node (e.g., radio access node 14). Here, the network (e.g., radio access node 14) is expecting HARQ feedback on xPUCCH during a given subframe (step 600). HARQ feedback is denoted as { FB (BI) }, BI 0_MAX(step 602). In some embodiments, if the received signal to interference plus noise ratio (SINR) for xPUCCH is above a given threshold T_HIGH(which may be a parameter set by higher layers, for example) (yes, step 604), the HARQ feedback is considered trustworthy (step 606). See any of the examples of fig. 14A to 14C, 15A to 15C, 16A and 16B, 17A and 17B, and 18A and 18B for illustration.

In some embodiments, when the received SINR for xPUCCH is below threshold T_HIGHBut above another threshold T_LOW(which may also be a parameter set by higher layers, for example) (yes at step 608), the received HARQ feedback is considered untrustworthy (step 610). In this case, all considered transmissions are negatively acknowledged (step 612), i.e. HARQ feedback for all BIs in the report is set to NACK. This will lead toSome extra HARQ retransmissions will indeed be spent, but more expensive higher layer retransmissions due to NACK/DTX → ACK errors caused by premature release of the HARQ process under consideration will be avoided. To illustrate this, see examples 10 and 11 in fig. 18A and 18B, respectively.

For both embodiments described above, the network sets BI 0 (step 614), and then the network will continue with each BI covered by the report (i.e., BI 0.. BI)_MAX) HARQ feedback for the particular BI for each HARQ process associated with the BI is processed (steps 616-630). In particular, let { HP (BI) } be all HARQ processes associated with the BI (step 616). Let HP (BI) be the first element of { HP (BI) }, and remove this element from { HP (BI) } (step 618). The network removes the association between the HARQ process HP (BI) and the BI (step 620). The network then processes the HARQ feedback FB (BI) for the HARQ process HP (BI) (step 622). This HARQ feedback process is illustrated in detail in fig. 12. The network determines if { HP (BI) } is empty (step 624). If not, the process returns to step 618. Once { HP (BI) } is empty, BI increments (step 626). At this time, if BI is greater than BI_MAX(step 628), the process ends (step 630); otherwise, the process returns to step 616 and repeats for the new BI.

Returning to step 608, in yet other embodiments, when the received SINR for xPUCCH is below the threshold T_LOWWhen this occurs (no, step 608), the network will conclude that the wireless device 18 has never attempted to transmit any xPUCCH feedback, and therefore that there is a DCI error in the corresponding poll (step 632). Then, the network will implicitly assume that the HARQ feedback for the relevant xPDSCH transmission is DTX (with BI ═ BI)_MAX) Since this may not have been received by the wireless device 18 (step 634). Then, the network sets BI ═ BI_MAX(step 636) and the process proceeds to step 616 for immediate processing of such implicit DTX feedback. To illustrate this, see examples 7, 8, and 9 in fig. 16A, 16B, 17A, and 17B.

Fig. 13 is a flow diagram illustrating a network-side HARQ feedback interpretation process according to some embodiments of the present disclosure. The process is performed by a network node (e.g., radio access node 14). Here, HARQ feedback for a specific BI is given for the relevant HARQ process. Depending on the indicated feedback (ACK/NACK/DTX), the Redundancy Version (RV) to be used by the HARQ process will be updated (NACK) or not updated (DTX) accordingly. Thereafter, a specific HARQ process-to the scheduler-is indicated as being eligible for retransmission (NACK or DTX) or idle (ACK). In the latter case, the HARQ process will be cleared and the New Data Indicator (NDI) toggled.

Specifically, as shown in fig. 13, the process starts (step 700) when the HARQ feedback FB (BI) for the HARQ process HP is to be processed (e.g., in step 622 of fig. 12). If the HARQ Feedback (FB) is DTX (step 702; YES), the network marks/marks the HARQ process HP as requiring retransmission (step 704). In other cases, if the HARQ Feedback (FB) is a NACK (step 706; YES), the network updates the RV for the HARQ process HP (step 708) and marks/marks the HARQ process HP as requiring retransmission (step 704). In other cases, if the HARQ Feedback (FB) is ACK (step 710; yes), the network clears the HARQ process HP and toggles its New Data Indicator (NDI), which is an existing indicator in LTE, to indicate the HARQ process to clear the HARQ buffer because the transmission is not related to the earlier transmission, but is a new transmission (step 712), and marks/marks the HARQ process HP as free/ready for new data (step 714). Note that step 710 is not necessary because if the HARQ feedback is not DTX and not NACK, then in this example it must be an ACK. Accordingly, the process may proceed directly from the "No" branch of step 706 to step 712.

Fig. 14A to 14C, 15A to 15C, 16A and 16B, 17A and 17B, and 18A and 18B illustrate examples that illustrate certain embodiments of aspects of the enhanced HARQ feedback solution described above. These examples are referred to as examples 1 to 11. Example 1 illustrates a scenario where the wireless device 18 successfully receives all DCI messages and downlink data and the network successfully receives an uplink transmission for HARQ feedback.

Example 2 illustrates a scenario with a PDSCH error that results in a NACK for subframe SF # (J-1). In response to the NACK, the network will retransmit the HARQ process from subframe SF # (J-1) using the new RV.

Example 3 illustrates a scenario with multiple PDSCH errors. In response to the NACKs for sub-frames SF # (J-2) and SF # (J-1), the network will retransmit the HARQ processes from sub-frames SF # (J-2) and SF # (J-1) using the new RV.

Example 4 illustrates a scenario with DCI errors for a non-polled DCI message. Here, the network will retransmit the HARQ process from subframe SF # (J-1) without updating the RV.

Example 5 illustrates a scenario with multiple DCI errors on a non-polled DCI message. Here, the network will retransmit the HARQ processes from subframes SF # (K-2) and SF # (J-1) without updating the RV.

Example 6 illustrates a scenario with mixed DCI errors on non-polled DCI messages. Here, the network will retransmit the HARQ processes from subframes SF # (J-3), SF # (J-2), and SF # (J-1), with the first HARQ process being retransmitted with the new RV, but the latter two HARQ processes being retransmitted without updating the RV.

Example 7 illustrates a scenario with a DCI error on a polling DCI message. At subframe SF # (J +2), i.e., the subframe in which the network is expecting the transmission of HARQ feedback, the network will notice the absence of HARQ feedback and recognize that there is a DCI error at subframe SF # (J), and then retransmit it with the same RV. At subframe SF # (J +7), the network will not perform any operation since the HARQ feedback includes all ACKs.

Example 8 illustrates a scenario with a DCI error plus an additional PDSCH error on a polling DCI message. Note that it is helpful to compare this example with problem a of fig. 7A. At subframe SF # (J +2), the network will notice the lack of HARQ feedback and recognize that a DCI error exists at subframe SF # (J). This will implicitly discontinuously transmit the HARQ process transmitted at subframe SF # (J), which is then retransmitted with the same RV. At subframe SF # (J +7), the network will retransmit all HARQ processes that are negatively acknowledged:

for BI ═ 0: HARQ process for retransmission of subframes SF # (J-3) and SF # (J +1)

For BI ═ 1: HARQ process for retransmission of subframes SF # (J-2) and SF # (J +2)

For BI ═ 1: the HARQ processes retransmitting sub-frames SF # (J-1) and SF # (J +3) may note that those HARQ processes of sub-frames SF # (J-3), SF # (J-2), and SF # (J +3) are "unnecessary" because they are all successfully received. In view of the low error rate (-1%) of DCI, the impact of these "unnecessary" retransmissions should be minor compared to the number of PDSCH errors.

Example 9A illustrates a scenario where there are multiple DCI errors. It may be beneficial to compare this example with problem C of fig. 8. At subframe SF # (J +2), the network will notice the lack of HARQ feedback and recognize that a DCI error exists at subframe SF # (J). This will implicitly discontinue transmission of the HARQ process transmitted at subframe SF # (J); therefore, the HARQ process for subframe SF # (J) will be retransmitted. The network also detects "jumps" in the BI sequence, i.e., BI 1 is preceded by BI 2 instead of BI 0, thus concluding that BI 0 may be lost. In other words, the network detects a DCI error among DCI errors for a subframe corresponding to a lost BI ═ 0. Therefore, this entry in the HARQ feedback buffer is set to DTX. Further, at subframe SF # (J +7), the network marks the "new" transmission from subframe SF # (J +1) and the "old" transmission from subframe SF # (J-3) as DTX, so both will be retransmitted. Other "new" transmissions at subframes SF # (J +2), SF # (J +3), and SF # (J +4) will be acknowledged, and old transmissions from subframes SF # (J-2) and SF # (J-1) will also be acknowledged.

Example 9B illustrates another scenario with multiple DCI errors. At subframe SF # (J +2), the network will notice the lack of HARQ feedback and recognize that a DCI error exists at subframe SF # (J). This will implicitly discontinue transmission of the HARQ process transmitted at subframe SF # (J); therefore, the HARQ process for subframe SF # (J) will be retransmitted. The network also detects "hops" in the BI sequence (i.e., BI 1 and BI 2 are preceded by BI 2 instead of BI 0), thus concluding that BI 0 and BI 1 may be lost. In other words, the network detects a DCI error among DCI errors for subframes corresponding to lost BI ═ 0 and BI ═ 1. Therefore, those entries in the HARQ feedback buffer are set to DTX. Furthermore, at subframe SF # (J +7), the network marks "new" transmissions from subframes SF # (J +1) and SF # (J +2) and "old" transmissions from subframes SF # (J-3) and SF # (J-2) as DTX, so both will be retransmitted. Other "new" transmissions at subframes SF # (J +3) and SF # (J +4) will be acknowledged, and old transmissions from subframe SF # (J-1) will also be acknowledged.

Example 10 illustrates a case where all downlink data is successfully received but there is an xPUCCH error (i.e., xPUCCH transmission is lost, or in other words, not received by the network). At subframe SF # (J +2), the network will notice the absence of HARQ feedback and recognize the presence of xPUCCH error. This will implicitly negate the acknowledgement of all HARQ processes that are expected to be reported, i.e., those from subframes SF # (J-3), SF # (J-2), SF # (J-1), and SF # (J). At subframe SF # (J +7), the network will not perform any operation since all downlink transmissions are acknowledged.

Example 11 illustrates a scenario where xPUCCH feedback is lost and there is an additional PDSCH error. It may be beneficial to compare this example with problem B of fig. 7B. At subframe SF # (J +2), the network will notice the absence of HARQ feedback and recognize the presence of xPUCCH error. This will implicitly negate the acknowledgement of all HARQ processes that are expected to be reported, i.e., those from subframes SF # (J-3), SF # (J-2), SF # (J-1), and SF # (J). It may be noted that those HARQ processes of subframes SF # (J-3) and SF # (J-2) are "unnecessary" because these downlink transmissions are successfully received. Therefore, it is important to keep xPUCCH errors fairly low. Furthermore, at subframe SF # (J +7), the network will retransmit all HARQ processes that are negatively acknowledged:

● for BI ═ 0: the HARQ process that retransmitted subframe SF # (J +1) (subframe SF # (J-3) has been negatively acknowledged).

● for BI ═ 1: the HARQ process that retransmits subframe SF # (J +2) (subframe SF # (J-2) has been negatively acknowledged).

Example Wireless device and radio Access node implementations

Fig. 19 is a schematic block diagram of a wireless device 18 (e.g., a UE) in accordance with some embodiments of the present disclosure. As shown, the wireless device 18 includes one or more processors 28 (e.g., a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), and/or the like), a memory 30, and one or more transceivers 32, each transceiver 32 including one or more transmitters 34 and one or more receivers 36 coupled to one or more antennas 38. In some embodiments, the functionality of the wireless device 18 described above may be implemented in whole or in part in software that is stored, for example, in the memory 30 and executed by the processor(s) 28.

In some embodiments, there is provided a computer program comprising instructions which, when executed by at least one processor, cause the at least one processor to perform the functions of the wireless device 18 according to any of the embodiments described herein. In some embodiments, a carrier containing the computer program product described above is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium, e.g., a non-transitory computer readable medium such as a memory.

Fig. 20 is a schematic block diagram of a wireless device 18 according to some other embodiments of the present disclosure. Wireless device 18 includes one or more modules 40, each of the one or more modules 40 being implemented in software. Module(s) 40 provide the functionality of wireless device 18 described herein. For example, module(s) 40 may include a receiving module 40-1 operable to receive a DCI message from a network, where the DCI message may include an indication of a timing offset K for HARQ, a HARQ feedback buffer index, and/or a poll indicator, depending on the embodiment, as described above with respect to various embodiments of the present disclosure. As another example, module(s) 40 may include a transmitting module 40-2 operable to transmit HARQ feedback according to any embodiment described herein. As yet another example, module(s) 40 may include a storage module 40-3 operable to store HARQ feedback in a HARQ feedback buffer as described above with respect to some embodiments of the present disclosure.

Fig. 21 is a schematic block diagram of a base station 14 (or more generally a radio access node 14) according to some embodiments of the present disclosure. The discussion is equally applicable to other types of radio access nodes. Further, other types of network nodes may have similar architectures (particularly with respect to including processor(s), memory, and network interfaces). As shown, the base station 14 includes a baseband unit 42, the baseband unit 42 including one or more processors 44 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 46, and a network interface 48, and one or more radio units 50, each radio unit 50 including a transmitter 52 and one or more receivers 54 coupled to one or more antennas 56. In some embodiments, the functionality of the base station 14, or more generally the functionality of the radio access node described above, or more generally the functionality of the network node, may be implemented in whole or in part in software, for example stored in the memory 46 and executed by the processor(s) 44.

Fig. 22 is a schematic block diagram illustrating a virtualization embodiment of a base station 14 in accordance with some embodiments of the present disclosure. The discussion is equally applicable to other types of radio access nodes. In addition, other types of network nodes may have similar virtualization architectures.

As used herein, a "virtualized" network node (e.g., a virtualized base station or a virtualized radio access node) is an implementation of a network node in which at least a portion of the functionality of the network is implemented as a virtual component, e.g., by a virtual machine running on physical processing node(s) in the network(s). As shown, in this example, the base station 14 includes a baseband unit 42, as described above, the baseband unit 42 including one or more processors 48 (e.g., CPUs, ASICs, FPGAs, and or), memory 46, and a network interface 48, and one or more radio units 50, each radio unit 50 including one or more transmitters 52 and one or more receivers 54 coupled to one or more antennas 56. The baseband unit 42 is connected to the radio unit(s) 50 via, for example, an optical cable or the like. The baseband unit 42 is connected via a network interface 48 to one or more processing nodes 58 that are coupled to or included as part of a network(s) 60. Each processing node 58 includes one or more processors 62 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 64, and a network interface 66.

In this example, the functionality 68 of the base station 14 described herein is implemented at one or more processing nodes 58 or distributed across the baseband unit 42 and one or more processing nodes 58 in any desired manner. In some particular embodiments, some or all of the functionality 68 of the base station 14 described herein is implemented as virtual components executed by one or more virtual machines implemented in the virtual environment(s) hosted by the processing node(s) 58. As will be understood by those of ordinary skill in the art, additional signaling or communication between the processing node(s) 58 and the baseband unit 42 is used in order to implement at least some of the desired functions 68. Note that in some embodiments, baseband unit 42 may not be included, in which case radio unit(s) 50 communicate directly with processing node(s) 58 through appropriate network interface(s).

Thus, with respect to embodiments of direct scheduling, in some embodiments, processing node(s) 58 may be operative to indicate or otherwise cause transmission of DCI to wireless device 18 via radio unit(s) 50 including an indication of HARQ feedback timing offset K. As another example, some or all of the network-side polling procedure of fig. 10 may be performed by processing node 58, and/or some or all of the network-side xPUCCH detection procedure of fig. 12 may be performed by processing node(s) 58 based on downlink HARQ feedback received from wireless device 18 via radio unit(s) 50.

In some embodiments, a computer program is provided comprising instructions which, when executed by at least one processor, cause the at least one processor to perform the functions of a network (e.g. in the form of a network node or a radio access node) according to any of the embodiments described herein. In some embodiments, a carrier containing the computer program product described above is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium, e.g., a non-transitory computer readable medium such as a memory.

Fig. 23 is a schematic block diagram of a base station 14 (or more generally a radio access node 14) according to some other embodiments of the present disclosure. The base station 14 includes one or more modules 70, each of which is implemented in software. Module(s) 70 provide the functionality of base station 14 as described herein. Module(s) 70 may include, for example, a transmitting module 70-1 operable to transmit DCI messages and downlink data according to any embodiment described herein, and a receiving module 70-2 operable to receive and process HARQ feedback according to any embodiment described herein. Note that other types of radio access nodes may be of similar architecture as shown in fig. 23 for the base station 14.

Example embodiments

While not limited to any particular embodiment, some example embodiments of the disclosure are described below.

● example 1: a method of operation of a wireless device (18) in a cellular communication system (10), comprising:

receiving (102) downlink control information in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

o transmitting (106) HARQ feedback in subframe T + K.

● example 2: the method of embodiment 1, wherein transmitting (106) the HARQ feedback comprises: o combining multiple downlink HARQ feedback flags in a single downlink HARQ transmission; and

o transmitting a single downlink HARQ transmission in subframe T + K.

● example 3: the method of embodiment 2 wherein combining the plurality of HARQ feedback flags comprises jointly encoding the plurality of HARQ feedback flags in a codeword for the single downlink HARQ transmission.

● example 4: the method of embodiment 2 or embodiment 3, wherein the downlink control information further includes information indicating which feedback flags are to be combined in a single downlink HARQ transmission.

● example 5: the method as in any one of embodiments 1-4, wherein the indication of the timing offset, K, for HARQ is a value of the timing offset, K, for HARQ.

● · example 6: the method as in any one of embodiments 1-4, wherein the indication of the timing offset K for HARQ is a value S, wherein the timing offset K for HARQ is N + S, where N is a predefined or preconfigured value.

● example 7: the method as in any one of embodiments 1-6 further comprising detecting a downlink control information failure.

● example 8: a wireless device (18) adapted to operate according to any of embodiments 1-7.

● example 9: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

an o-transceiver (32);

o at least one processor (28); and

o a memory (30) storing instructions executable by the at least one processor (28), whereby the wireless device (18) is operable to:

receiving, by a transceiver (32), downlink control information in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

transmitting, by the transceiver, the HARQ feedback in subframe T + K.

● example 10: the wireless device (18) of embodiment 9, to transmit the HARQ feedback, the wireless device (18) further operable to:

o combining multiple downlink HARQ feedback flags in a single downlink HARQ transmission;

and

o transmitting a single downlink HARQ transmission in subframe T + K.

● example 11: the wireless device (18) of embodiment 10, wherein to combine the plurality of HARQ feedback flags, the wireless device (18) is further operable to jointly encode the plurality of HARQ feedback flags in a codeword for a single downlink HARQ transmission.

● example 12: the wireless device (18) of embodiment 10 or embodiment 11, wherein the downlink control information further comprises information indicating which feedback flags are to be combined in a single downlink HARQ transmission.

● example 13: the wireless device (18) of any of embodiments 9-12, wherein the indication of the timing offset K for HARQ is a value for the timing offset K for HARQ.

● example 14: the wireless device (18) of any of embodiments 9-12, wherein the indication of the timing offset K for HARQ is a value S, wherein the timing offset K for HARQ is N + S, where N is a predefined or preconfigured value.

● example 15: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

o means for receiving downlink control information in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

o means for transmitting HARQ feedback in subframe T + K.

● example 16: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

a reception module (40-1) operable to receive downlink control information in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

a transmitting module (40-2) operable to transmit HARQ feedback in subframe T + K.

● example 17: a method of operation of a wireless device (18) in a cellular communication system (10), comprising:

receiving (302) a downlink control information message comprising a hybrid automatic repeat request, HARQ, feedback buffer index; and

storing (304) a downlink HARQ feedback flag in a location within the HARQ feedback buffer corresponding to the HARQ feedback buffer index.

● example 18: the method of embodiment 17, further comprising the step of repeating the receiving (302) and storing (304) for one or more additional downlink control information messages.

● example 19: the method of embodiment 18, further comprising:

o receiving (306, yes) a polling request from the network node; and

o upon receiving the polling request:

creating (308) an uplink control message comprising a downlink HARQ feedback flag stored in a downlink HARQ feedback buffer; and

an uplink control message is transmitted (314).

● example 20: the method of embodiment 19, wherein creating the uplink control message comprises jointly encoding the downlink HARQ feedback flags in a codeword for the uplink control message.

● example 21: the method of embodiment 19 or 20, wherein transmitting the uplink control message comprises: the uplink control message is transmitted in subframe T + N, where subframe T is the subframe where the polling request is received and N is the offset of the HARQ feedback.

● example 22: the method of embodiment 21, wherein the offset N of the HARQ feedback is predefined or preconfigured.

● example 23: the method of embodiment 21 wherein the offset N of the HARQ feedback is a function of the index received in the poll request or downlink control information message received in subframe T.

● example 24: the method as in any one of embodiments 17-23, further comprising detecting a downlink control information failure.

● example 25: a wireless device (18) adapted to operate in accordance with any of embodiments 17-24.

● example 26: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

an o-transceiver (32);

o at least one processor (28); and

a memory (30) storing instructions executable by the at least one processor (28), whereby the wireless device (18) is operable to:

receiving, by a transceiver (32), a downlink control information message comprising a hybrid automatic repeat request, HARQ, feedback buffer index; and

the downlink HARQ feedback flag is stored in a location within the HARQ feedback buffer corresponding to the HARQ feedback buffer index.

● example 27: the wireless device (18) of embodiment 26, wherein the wireless device (18) is further operable to repeat the steps of receiving and storing for one or more additional downlink control information messages.

● example 28: the wireless device (18) of embodiment 27, wherein the wireless device (18) is further operable to:

o receiving a polling request from a network node through a transceiver (32); and

o upon receiving the polling request:

creating an uplink control message including a downlink HARQ feedback flag stored in a downlink HARQ feedback buffer; and

an uplink control message is transmitted.

● example 29: the wireless device (18) of embodiment 28, wherein to create the uplink control message, the wireless device (18) is further operable to jointly encode a downlink HARQ feedback flag in a codeword for the uplink control message.

● example 30: the wireless device (18) of embodiment 28 or 29, wherein the wireless device (18) is further operable to transmit the uplink control message in subframe T + N, wherein subframe T is the subframe in which the polling request is received and N is the offset for HARQ feedback.

● example 31: the wireless device (18) of embodiment 30, wherein the offset N of the HARQ feedback is predefined or preconfigured.

● example 31: the wireless device (18) of embodiment 30, wherein the offset N of the HARQ feedback is a function of an index received in a poll request or downlink control information message received in subframe T.

● example 32: the wireless device (18) of any of embodiments 26-31 wherein the wireless device (18) is further operable to detect a downlink control information failure.

● example 33: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

means for receiving a downlink control information message comprising a hybrid automatic repeat request, HARQ, feedback buffer index; and

means for storing a downlink HARQ feedback flag in a location within the HARQ feedback buffer corresponding to the HARQ feedback buffer index.

● example 34: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

a reception module (40-1) operable to receive a downlink control information message comprising a hybrid automatic repeat request, HARQ, feedback buffer index; and

a storage module (40-3) operable to store a downlink HARQ feedback flag in a location within the HARQ feedback buffer corresponding to the HARQ feedback buffer index.

● example 35 a: a method of operation of a wireless device (18) in a cellular communication system (10), comprising:

o receiving a message including a hybrid automatic repeat request, HARQ, feedback buffer index;

o determining that reception of data for a current subframe is successful, wherein the current subframe is a subframe in which the message is received;

o determining that a negative acknowledgement, NACK, flag is stored in a HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the message; and

upon determining that the NACK flag is stored in the HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to the HARQ feedback buffer index included in the message, maintaining the NACK flag in the HARQ feedback buffer of the wireless device (18) at the buffer location corresponding to the HARQ feedback buffer index included in the message even if the reception of the data for the current subframe is successful.

● example 35: a method of operation of a wireless device (18) in a cellular communication system (10), comprising:

o receiving a downlink control information, DCI, message including a hybrid automatic repeat request, HARQ, feedback buffer index;

o determining that reception of data for a current subframe is successful, wherein the current subframe is a subframe in which the DCI message is received;

o determining that a negative acknowledgement, NACK, flag is stored in a HARQ feedback buffer of a wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the DCI message; and

upon determining that the NACK flag is stored in the HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to the HARQ feedback buffer index included in the DCI message, maintaining the NACK flag in the HARQ feedback buffer of the wireless device (18) at the buffer location corresponding to the HARQ feedback buffer index included in the DCI message even if the reception of data for the current subframe is successful.

● example 36: the method of embodiment 35, further comprising sending the HARQ feedback stored in the HARQ feedback buffer to the network node.

● example 37: the method of embodiment 35, further comprising: for a current subframe, it is determined whether a plurality of DCI errors have occurred in a plurality of consecutive subframes prior to the current subframe.

● example 38: the method of embodiment 37, further comprising: upon determining that multiple DCI errors have occurred in multiple consecutive subframes, a discontinuous transmission DTX flag is stored in the HARQ feedback buffer at a location corresponding to the HARQ feedback buffer index immediately preceding the HARQ feedback buffer index included in the DCI message.

● example 39: a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of embodiments 35-39.

● example 40: a carrier containing the computer program of embodiment 39, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

● example 41: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

an o-transceiver (32);

o at least one processor (28); and

receiving, by a transceiver (32), a downlink control information, DCI, message comprising a hybrid automatic repeat request, HARQ, feedback buffer index;

determining that reception of data of a current subframe is successful, wherein the current subframe is a subframe in which a DCI message is received;

determining that a negative acknowledgement, NACK, flag is stored in a HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the DCI message; and

upon determining that a NACK flag is stored in a HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the DCI message, maintaining the NACK flag in the HARQ feedback buffer of the wireless device (18) at the buffer location corresponding to the HARQ feedback buffer index included in the DCI message even if the reception of data for the current subframe is successful.

● example 42: the wireless device (18) of embodiment 41, wherein the wireless device (18) is further operable to send the HARQ feedback stored in the HARQ feedback buffer to the network node.

● example 43: the wireless device (18) of embodiment 41 wherein the wireless device (18) is further operable to determine, for the current subframe, whether a plurality of DCI errors have occurred in a plurality of consecutive subframes prior to the current subframe.

● example 44: the wireless device (18) of embodiment 41, wherein the wireless device (18) is further operable to, upon determining that multiple DCI errors have occurred in multiple consecutive subframes, store a discontinuous transmission, DTX, flag in the HARQ feedback buffer at a location corresponding to the HARQ feedback buffer index immediately preceding the HARQ feedback buffer index included in the DCI message.

● example 45: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

o means for receiving a downlink control information, DCI, message comprising a hybrid automatic repeat request, HARQ, feedback buffer index;

means for determining that reception of data of a current subframe is successful, wherein the current subframe is a subframe in which a DCI message is received;

means for determining that a negative acknowledgement, NACK, flag is stored in a HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the DCI message; and

means for maintaining a NACK flag in a HARQ feedback buffer of a wireless device (18) at a buffer position corresponding to a HARQ feedback buffer index included in the DCI message, even if reception of data for a current subframe is successful, upon determining that the NACK flag is stored in the HARQ feedback buffer of the wireless device (18) at a buffer position corresponding to the HARQ feedback buffer index included in the DCI message.

● example 46: a wireless device (18) operable in a cellular communication system (10), the wireless device (18) comprising:

a reception module (40-1) operable to receive a downlink control information, DCI, message comprising a hybrid automatic repeat request, HARQ, feedback buffer index;

a first determination module (40) operable to determine that reception of data for a current subframe is successful, wherein the current subframe is a subframe in which a DCI message is received;

o a second determination module (40) operable to determine that a negative acknowledgement, NACK, flag is stored in a HARQ feedback buffer of the wireless device (18) at a buffer location corresponding to a HARQ feedback buffer index included in the DCI message; and

an o-flag storage module (40-3) operable, upon determining that a NACK flag is stored in a HARQ feedback buffer of a wireless device (18) at a buffer position corresponding to a HARQ feedback buffer index included in the DCI message, to maintain the NACK flag in the HARQ feedback buffer of the wireless device (18) at the buffer position corresponding to the HARQ feedback buffer index included in the DCI message even if the reception of data for the current subframe is successful.

● example 47 a: a method of operation of a radio access node (14) in a cellular communication system (10), comprising:

o determining whether the quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a higher threshold but greater than a lower threshold; and

upon determining that the quality of the uplink control channel is less than the upper threshold but greater than the lower threshold, setting each of the plurality of flags to a negative acknowledgement, NACK, flag, wherein the flag has been received from the wireless device (18).

● example 47: a method of operation of a radio access node (14) in a cellular communication system (10), comprising:

o determining whether the quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a predefined upper threshold but greater than a predefined lower threshold; and

o upon determining that the quality of the uplink control channel is less than the predefined upper threshold but greater than the predefined lower threshold, setting each of a plurality of bundled HARQ feedback flags that have been received from the wireless device (18) over the uplink control channel in the past as a negative acknowledgement, NACK, flag.

● example 48: the method of embodiment 47, wherein the plurality of bundled HARQ feedback flags have a corresponding index of BI ═ 1_MAXIn which BI_MAXIs a predefined value greater than 1, and the method further comprises:

o determining whether the quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a predefined lower threshold; and

o upon determining that the quality of the uplink control channel is less than the predefined lower threshold, transmitting one of the plurality of bundled HARQ feedback flags that would have been received from the wireless device (18) over the uplink control channel in the past and that corresponds to the index BI_MAXThe one bundled HARQ feedback flag of (1) is set to a discontinuous transmission DTX flag indicating DCI error.

● example 49: a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of embodiments 47-48.

● example 50: a carrier containing the computer program of embodiment 49, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

● example 51: a radio access node (14) for a cellular communication system (10), the radio access node (14) comprising:

an o-radio unit (50);

o at least one processor (44); and

o a memory (46) storing instructions executable by the at least one processor (44), whereby the radio access node (14) is operable to:

determining whether a quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a predefined upper threshold but greater than a predefined lower threshold; and

upon determining that the quality of the uplink control channel is less than a predefined upper threshold but greater than a predefined lower threshold, each of a plurality of bundled HARQ feedback flags that have been received from the wireless device (18) over the uplink control channel in the past is set to a negative acknowledgement, NACK, flag.

● example 52: the radio access node (14) of embodiment 51, wherein the plurality of bundled HARQ feedback flags have a corresponding index of BI {1_MAXIn which BI_MAXIs a predefined value greater than 1, and the radio access node (14) is further operable to:

● example 53: a radio access node (14) for a cellular communication system (10), the radio access node (14) comprising:

means for determining whether a quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a predefined upper threshold but greater than a predefined lower threshold; and

means for setting each of a plurality of bundled HARQ feedback flags that have been received in the past from the wireless device (18) over the uplink control channel to a negative acknowledgement, NACK, flag upon determining that the quality of the uplink control channel is less than a predefined upper threshold but greater than a predefined lower threshold.

● example 54: a radio access node (14) for a cellular communication system (10), the radio access node (14) comprising:

a determination module operable to determine whether a quality of an uplink control channel from the wireless device (18) to the radio access node (14) is less than a predefined upper threshold but greater than a predefined lower threshold; and

an o-flag setting module operable to set each of a plurality of bundled HARQ feedback flags that have been received in the past from the wireless device (18) over the uplink control channel to a negative acknowledgement, NACK, flag upon determining that the quality of the uplink control channel is less than a predefined upper threshold but greater than a predefined lower threshold.

The following abbreviations are used throughout this disclosure.

3GPP third Generation partnership project

5G fifth Generation

AAS advanced antenna System

ACK acknowledgement

AM confirmation mode

ASIC specific integrated circuit

BI buffer index

CCE control channel elements

CPU central processing unit

DCI downlink control information

DTX discontinuous transmission

eNB enhanced or evolved node B

ePDCCH enhanced physical downlink control channel

FDD frequency division Duplex

FPGA field programmable Gate array

HARQ hybrid automatic repeat request

LTE Long term evolution

MIMO multiple input multiple output

MME mobility management entity

Ms

MTC machine type communication

NACK negative acknowledgement

NDI New data indicator

OFDM orthogonal frequency division multiplexing

PDCCH physical Downlink control channel

PDSCH physical Downlink shared channel

P-GW packet data network gateway

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

RAN radio Access network

RLC radio link control

RTT round trip time

RV redundancy version

S-GW service gateway

SINR Signal to interference plus noise ratio

TB test bed

TDD time division duplexing

UCI uplink control information

UE user Equipment

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

1. A method of operation of a wireless device (18) in a cellular communication system (10), comprising:

receiving (102) downlink control information from a radio access node (14) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

transmitting (106) downlink HARQ feedback to the radio access node (14) in subframe T + K.

2. The method of claim 1, further comprising:

combining (104) a plurality of downlink HARQ feedback flags in a single downlink HARQ feedback transmission;

wherein transmitting (106) HARQ feedback in the subframe T + K comprises transmitting (106) the single downlink HARQ feedback transmission in the subframe T + K.

3. The method of claim 2 wherein combining (104) the plurality of downlink HARQ feedback flags in the single downlink HARQ feedback transmission comprises jointly encoding (104) the plurality of downlink HARQ feedback flags in a codeword for the single downlink HARQ feedback transmission.

4. The method of claim 2 or 3, wherein:

the downlink control information further includes information indicating which feedback flags are to be combined in the single downlink HARQ feedback transmission.

5. The method of any of claims 1 to 4, wherein the indication of the timing offset K of HARQ is a value of the timing offset K for HARQ.

6. The method of any one of claims 1 to 4, wherein the indication of the timing offset of HARQ, K, is a value of S, wherein the timing offset of HARQ, K ═ N + S, where N is a predefined value.

7. The method of any of claims 1-4, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a preconfigured value.

8. The method of any of claims 1-4, wherein the indication of the timing offset of HARQ, K, is a value of S, wherein the timing offset of HARQ, K-N + S, where N is a predetermined minimum HARQ timing offset for the wireless device (18).

9. The method of any of claims 1 to 4, wherein the indication of the timing offset K of HARQ is a value X, wherein the timing offset K of HARQ is a function of the value X.

10. The method of any of claims 1-9, wherein the HARQ feedback comprises a HARQ feedback flag, the HARQ feedback flag being an acknowledgement if the wireless device (18) successfully received the respective downlink data, whether the HARQ feedback flag is acknowledged if the wireless device (18) did not successfully receive the respective downlink data, and an indication of a downlink control information failure if the wireless device (18) did not receive the respective downlink control information.

11. A wireless device (18) for a cellular communication system (10), the wireless device (18) being adapted to:

receiving downlink control information from a radio access node (14) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

12. The wireless device (18) of claim 11, further adapted to operate in accordance with the method of any one of claims 2 to 10.

13. A wireless device (18) for a cellular communication system (10), comprising:

a transceiver (32);

at least one processor (28); and

receiving, by the transceiver (32), downlink control information from a radio access node (14) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

transmitting downlink HARQ feedback to the radio access node (14) by the transceiver (32) in subframe T + K.

14. The wireless device (18) of claim 13, wherein, by execution of the instructions by the at least one processor (28), the wireless device (18) is further operable to:

combining a plurality of downlink HARQ feedback flags in a single downlink HARQ feedback transmission;

wherein, to transmit the downlink HARQ feedback in the subframe T + K, the wireless device (18) is operable to transmit the single downlink HARQ feedback transmission in the subframe T + K by the transceiver (32).

15. The wireless device (18) of claim 14, wherein to combine the plurality of downlink HARQ feedback flags in the single downlink HARQ feedback transmission, the wireless device (18) is further operable to jointly encode the plurality of downlink HARQ feedback flags in a codeword for the single downlink HARQ feedback transmission.

16. The wireless device (18) of claim 14 or 15, wherein:

17. The wireless device (18) of any of claims 13-16, wherein the indication of the timing offset, K, of the HARQ is a value of the timing offset, K, for the HARQ.

18. The wireless device (18) of any of claims 13-16, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a predefined value.

19. The wireless device (18) of any of claims 13-16, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a preconfigured value.

20. The wireless device (18) of any of claims 13-16, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a predetermined minimum timing offset of HARQ for the wireless device (18).

21. The wireless device (18) of any of claims 13-16, wherein the indication of the timing offset, K, of HARQ is a value, X, wherein the timing offset, K, of HARQ is a function of the value, X.

22. The wireless device (18) of any of claims 13-21, wherein the HARQ feedback comprises a HARQ feedback flag, the HARQ feedback flag being an acknowledgement if the wireless device (18) successfully received the respective downlink data, whether the HARQ feedback flag is acknowledged if the wireless device (18) did not successfully receive the respective downlink data, and an indication that the downlink control information failed if the wireless device (18) did not receive the respective downlink control information.

23. A wireless device (18) for a cellular communication system (10), comprising:

means for receiving downlink control information from a radio access node (14) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

means for transmitting downlink HARQ feedback to the radio access node (14) in subframe T + K.

24. A wireless device (18) for a cellular communication system (10), comprising:

a receiving module (40-1) operable to receive downlink control information from a radio access node (14) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

a transmitting module (40-2) operable to transmit downlink HARQ feedback to the radio access node (14) in subframe T + K.

25. A method of operation of a radio access node (14) in a cellular communication system (10), comprising:

transmitting (102) downlink control information to a wireless device (18) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

receiving (106) downlink HARQ feedback from the wireless device (18) in subframe T + K.

26. The method of claim 25, wherein:

the downlink HARQ feedback in the subframe T + K comprises a single downlink HARQ feedback transmission in the subframe T + K that is a combination of multiple downlink HARQ feedback flags.

27. The method of claim 26, wherein the single downlink HARQ feedback transmission represents a joint encoding of the plurality of downlink HARQ feedback flags.

28. The method of claim 26 or 27, wherein:

29. The method of any one of claims 25 to 28, wherein the indication of the timing offset K for HARQ is a value of timing offset K for HARQ.

30. The method of any one of claims 25 to 28, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a predefined value.

31. The method of any one of claims 25 to 28, wherein the indication of the timing offset K for HARQ is a value S, wherein the timing offset K for HARQ is N + S, where N is a preconfigured value.

32. The method of any one of claims 25 to 28, wherein the indication of the timing offset of HARQ, K, is a value, S, wherein the timing offset of HARQ, K ═ N + S, where N is the predetermined minimum HARQ timing offset of the wireless device (18).

33. The method of any one of claims 25 to 28, wherein the indication of the timing offset, K, of HARQ is a value, X, wherein the timing offset, K, of HARQ is a function of the value, X.

34. The method of any of claims 25 to 33, wherein the HARQ feedback comprises a HARQ feedback flag, the HARQ feedback flag being an acknowledgement if the wireless device (18) successfully received the respective downlink data, whether the HARQ feedback flag is acknowledged if the wireless device (18) did not successfully receive the respective downlink data, and an indication of a downlink control information failure if the wireless device (18) did not receive the respective downlink control information.

35. A radio access node (14) for a cellular communication system (10), the radio access node (14) being adapted to:

transmitting downlink control information to a wireless device (18) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

receiving downlink HARQ feedback from the wireless device (18) in subframe T + K.

36. The radio access node (14) of claim 35, further adapted to operate in accordance with the method of any of claims 25 to 34.

37. A radio access node (14) for a cellular communication system (10), comprising:

at least one radio unit (50);

at least one processor (44); and

a memory (46) storing instructions executable by at least one processor (44), whereby the radio access node (14) is operable to:

transmitting, by the at least one radio unit (50), downlink control information to a wireless device (18) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset k of a hybrid automatic repeat request, HARQ; and

receiving, by the at least one radio unit (50), downlink HARQ feedback from the wireless device (18) in subframe T + K.

38. The radio access node (14) of claim 37, wherein:

39. The radio access node (14) of claim 38, wherein the single downlink HARQ feedback transmission represents a joint encoding of the plurality of downlink HARQ feedback flags.

40. The radio access node (14) of claim 37 or 38, wherein:

41. The radio access node (14) of any of claims 37-40, wherein the indication of the timing offset K of HARQ is a value of the timing offset K for HARQ.

42. The radio access node (14) of any of claims 37-40, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a predefined value.

43. The radio access node (14) of any of claims 37-40, wherein the indication of the timing offset K of HARQ is a value S, wherein the timing offset K of HARQ is N + S, where N is a preconfigured value.

44. The radio access node (14) of any of claims 37-40, wherein the indication of the timing offset of HARQ, K, is a value of S, wherein the timing offset of HARQ, K-N + S, where N is a predetermined minimum HARQ timing offset for the wireless device (18).

45. The radio access node (14) of any of claims 37-40, wherein the indication of the timing offset, K, of HARQ is a value, X, wherein the timing offset, K, of HARQ is a function of the value, X.

46. The radio access node (14) of any of claims 37-45, wherein the HARQ feedback includes a HARQ feedback flag that is acknowledged if the wireless device (18) successfully received the respective downlink data, acknowledged if the wireless device (18) did not successfully receive the respective downlink data, and indicative of a downlink control information failure if the wireless device (18) did not receive the respective downlink control information.

47. A radio access node (14) for a cellular communication system (10), comprising:

means for transmitting downlink control information to a wireless device (18) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

means for receiving downlink HARQ feedback from the wireless device (18) in subframe T + K.

48. A radio access node (14) for a cellular communication system (10), comprising:

a transmitting module (70-1) operable to transmit downlink control information to a wireless device (18) in a first subframe T, wherein the downlink control information comprises an indication of a timing offset K of a hybrid automatic repeat request, HARQ; and

a receiving module (70-2) operable to receive downlink HARQ feedback from the wireless device (18) in subframe T + K.