Joint HARQ / ARQ feedback for earlier RLC ARQ retransmission

Abstract

Example embodiments of the present disclosure are directed to a joint feedback for data packets retransmission. A method includes receiving, from a network device, a request for a first retransmission

Description

[0002] Data recovery is one of functions of cellular communication systems from the first generation (1G) and forward. In a wireless communication system, a plurality of data recovery loops at different protocol layers are used to ensure reliable delivery of user data. At a radio protocol layer of 5G New Radio (NR), within a physical (PHY) layer and a medium access control (MAC) layer, hybrid automatic repeat request (HARQ) is used to ensure reliability. In addition, at a radio link control (RLC) layer, automatic repeat request (ARQ) is used to further enhance reliability. RLC ARQ is a technique used to recover packets that may be not recovered by the lower layer HARQ operation, for example, due to a limited maximum number of retransmissions or false-positive acknowledgement errors or inaccurate modulation and coding scheme (MCS) selection. Furthermore, at a packet data convergence protocol (PDCP) layer, there is a retransmission solution specifically designed for reliable data transmission during a handover case. Different data recovery solutions may be studied further in 6G era, for example, considering the requirements of the new emerging applications, for example, extended reality (XR) and others which simultaneously require high reliability and low latency. The retransmissions at the RLC layer may be based on timers and state variables that are associated with the RLC layer and configured to accommodate the retransmission processes at the lower layer, such as HARQ retransmissions, which, however, may incur additional delay. SUMMARY

[0003] In a first aspect of the present disclosure, there is provided a terminal device (110) for data packets retransmission. The terminal device includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device (110) at least to: receive (410, 710), from a network device (120), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (110), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (110); and in response to the receiving of the request (405) for the first retransmission (412) of the second data packet (414), perform (425, 720) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) to the network device (120).

[0004] In a second aspect of the present disclosure, there is provided a network device (120) for data packets retransmission. The network device includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device (120) at least to: transmit (410, 810), to a terminal device (110), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (HO), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (110); and receive (430, 820) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), after transmitting the request (405) for the first retransmission (412) of the second data packet (414).

[0005] In a third aspect of the present disclosure, there is provided a terminal device (110) for data packets retransmission. The terminal device includes means for receiving (410, 710), from a network device (120), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (110), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (110); and means for in response to the receiving of the request (405) for the first retransmission (412) of the second data packet (414), performing (425, 720) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) to the network device (120).

[0006] In a fourth aspect of the present disclosure, there is provided a network device (120) for data packets retransmission. The network device includes means for transmitting (410, 810), to a terminal device (110), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (110), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (HO); and means for receiving (430, 820) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), after transmitting the request (405) for the first retransmission (412) of the second data packet (414).

[0007] In a fifth aspect of the present disclosure, there is provided a terminal device (110 305) for data packets retransmission. The terminal device includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device (HO, 305) at least to: transmit (210, 330, 510), to a network device (120, 310), a joint retransmission feedback (207, 332) requesting, from the network device (120), at least one of: a first retransmission (212, 320) of a first data packet (214) from a first protocol layer (215) of the network device (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the network device (120, 310); and receive (230, 345, 520) at least one of the first retransmission (212, 327) or the second retransmission (216) of the first data packet (214), after the transmission (210, 330, 510) of the joint retransmission feedback (207, 332).

[0008] In a sixth aspect of the present disclosure, there is provided a network device (120 310) for data packets retransmission. The network device includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device (120, 310) at least to: receive (220, 330, 610), from a terminal device (110, 305), a joint retransmission feedback (207, 332) requesting at least one of a first retransmission (212, 327) of a first data packet (214) from a first protocol layer (215) of the network device (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the network device (120, 310); and perform (225, 345, 620), based on the joint retransmission feedback (207, 332), at least one of the first retransmission (212, 327) of the first data packet (214) or the second retransmission (216) of the first data packet (214), to the terminal device (110, 305).

[0009] In a seventh aspect of the present disclosure, there is provided a terminal device (110 305) for data packets retransmission. The terminal device includes means for transmitting (210, 330, 510), to a network device (120, 310), a joint retransmission feedback (207, 332) requesting, from the network device (120), at least one of: a first retransmission (212, 320) of a first data packet (214) from a first protocol layer (215) of the network device (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the network device (120, 310); and means for receiving (230, 345, 520) at least one of the first retransmission (212, 327) or the second retransmission (216) of the first data packet (214), after the transmission (210, 330, 510) of the joint retransmission feedback (207, 332).

[0010] In an eighth aspect of the present disclosure, there is provided a network device (120 310) for data packets retransmission. The network device includes means for receiving (220, 330, 610), from a terminal device (110, 305), a joint retransmission feedback (207, 332) requesting at least one of a first retransmission (212, 327) of a first data packet (214) from a first protocol layer (215) of the network device (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the network device (120, 310); and means for performing (225, 345, 620), based on the joint retransmission feedback (207, 332), at least one of the first retransmission (212, 327) of the first data packet (214) or the second retransmission (216) of the first data packet (214), to the terminal device (110, 305).

[0011] It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure may become easily comprehensible through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Some example embodiments may now be described with reference to the accompanying drawings, where:

[0013] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure may be implemented;

[0014] FIG. 2 is a signaling diagram for joint feedback according to some example embodiments of the present disclosure;

[0015] FIG. 3 is a signaling diagram for joint feedback according to some example embodiments of the present disclosure;

[0016] FIG. 4 is a signaling diagram for joint feedback according to some example embodiments of the present disclosure;

[0017] FIG. 5 illustrates a flowchart of an example method implemented at a first apparatus according to some example embodiments of the present disclosure;

[0018] FIG. 6 illustrates a flowchart of an example method implemented at a second apparatus according to with some example embodiments of the present disclosure;

[0019] FIG. 7 illustrates a flowchart of an example method implemented at a first apparatus according to some example embodiments of the present disclosure;

[0020] FIG. 8 illustrates a flowchart of an example method implemented at a second apparatus according to some example embodiments of the present disclosure;

[0021] FIG. 9 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0022] FIG. 10 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0023] Throughout the drawings, the same or similar reference numerals represent the same or similar element. DETAILED DESCRIPTION

[0024] Principle of the present disclosure may now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein may be implemented in various manners other than the ones described below.

[0025] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0026] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0027] It shall be understood that although the terms “first,” “second,”..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elements may not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0028] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0029] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It may be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0031] As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0032] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0033] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there may of course also be future type communication technologies and systems with which the present disclosure may be embodied. It may not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0034] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may include a base station (BS) or an access point (AP), for example, x NodeB (xNB), such as a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB) and an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture includes a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node includes a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0035] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customerpremises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0036] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain may be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0037] As described above, a plurality of data recovery loops at different protocol layers are used to ensure reliable delivery of user data. For example, HARQ is used at the PHY and MAC layers, and ARQ is used at the RLC layer. In 5G, the RLC layer may be implemented in three modes including a transparent mode (TM), an unacknowledged mode (UM) and an acknowledged mode (AM). The AM mode may support retransmissions. There are mechanisms used by the AM mode to enable retransmissions, some of which may be triggered at a transmitter and others at a receiver. These retransmissions may be based on timers and state variables that are associated with the RLC layer. At the transmitter, a polling mechanism may be used to request a report from the receiver using a poll bit. This approach is based on the assumption that the transmitted data is correctly decoded. If the report from the receiver indicates a packet is missing, the transmitter may initiate a retransmission of the packet.

[0038] The receiver may also initiate a retransmission using configured timers. Two of the timers associated with the AM mode are the t-Reassembly timer and the t-Status prohibit timer, as specified in the third Generation Partnership Project (3GPP) standard. The t-Reassembly timer is started when a missing packet is detected, and the packet is negative-acknowledged (NACKed) by sending a Status protocol data unit (PDU) when the t-Reassembly timer expires. The t-Status prohibit timer provides a time window after sending a Status PDU. Within this time window, no following Status PDU may be sent from the receiving side of an RLC entity to its peer entity.

[0039] Sequence numbers are used at the RLC layer. With sequence numbering of each data packet, the RLC receiver may determine if a packet is missing, by checking if its reception is out of sequence or not. When a missing packet is detected, the RLC receiver may start the t-Reassembly timer. This timer is configured to accommodate the retransmission processes at the lower layer, such as HARQ retransmissions. Thus, the timer potentially does not expire before the HARQ processes are completed. This t-Reassembly timer may contribute to overall delay attributed to the RLC layer.

[0040] In legacy 5G implementation, for example in downlink communications, when a RLC entity of the AM mode at a UE (also called a UE RLC AM entity) detects a missing packet, it starts the t-Reassembly timer. Below the RLC layer, a gNB may retransmit a packet according to a maximum number of retransmissions after which the gNB gives up the retransmission. The maximum number of retransmissions may be used to consistently set the t-Reassembly timer value in the UE RLC AM entity. The UE RLC AM entity does not know when the maximum number of retransmissions at the MAC layer has been reached. Therefore, the t-Reassembly timer at the RLC incurs additional delay according to the worst-case number of retransmissions and scheduling delays.

[0041] In addition, according to one version of the LTE specification, in the context of HARQ / ARQ interactions, an ARQ process may utilize information obtained from a HARQ process about a transmission status of a transmission block (TB). If a HARQ transmitter detects a failed delivery of a TB, for example, due to maximum retransmission limit being reached, relevant transmitting ARQ entities may be notified, and potential retransmissions and re-segmentation may be initiated.

[0042] It has been proposed to reduce the t-Reassembly timer values to values as short as 1ms to speed up the status report triggering at the receiver. However, this may cause sending STATUS reports with pre-mature negative acknowledgements (NACKs) for some of the SDUs that may still be in the process of being transmitted or being retransmitted by lower layers.

[0043] Example embodiments of the present disclosure propose downlink (DL) and uplink (UL) solutions for a joint feedback. In one aspect, a first apparatus (such as a UE) may transmit, to a second apparatus (such as a gNB), a joint retransmission feedback requesting at least one of a first retransmission (such as an RLC ARQ retransmission) of a first data packet (such as a DL data packet) from a first protocol layer of the second apparatus, or a second retransmission (such as an HARQ retransmission) of the first data packet from a second protocol layer of the second apparatus. The second protocol layer may be lower than the first protocol layer. Based on the joint retransmission feedback received from the first apparatus, the second apparatus performs at least one of the first retransmission of the first data packet or the second retransmission of the first data packet, to the first apparatus.

[0044] In another aspect, the second apparatus transmits, to the first apparatus, a request for a first retransmission of a second data packet (such as a UL data packet) from the first protocol layer of the first apparatus, during a second retransmission of the second data packet from the second protocol layer of the first apparatus. After receiving the request, the first apparatus performs the first retransmission of the second data packet from the first protocol layer of the first apparatus to the second apparatus during the second retransmission of the second data packet from the second protocol layer of the first apparatus.

[0045] In this way, retransmissions from different protocol layers may be requested in parallel, thereby reducing a data packet retransmission delay and improving data recovery efficiency.

[0046] FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure may be implemented.

[0047] In the communication environment 100, a plurality of communication devices, including a first apparatus 110 and a second apparatus 120, may communicate with each other. In some example embodiments, the first apparatus 110 may operate as a terminal device (such as a UE), and the second apparatus 120 may operate as a network device (such as a BS, a gNB and an eNB) serving the first apparatus 110.

[0048] In the following, for the purpose of illustration, some example embodiments are described with the first apparatus 110 operating as a terminal device and the second apparatus 120 operating as a network device. However, in some example embodiments, operations described with respect to a terminal device may be implemented at a network device or other devices, and operations described with respect to a network device may be implemented at a terminal device or other devices.

[0049] In the example embodiments where one of the first apparatus 110 and the second apparatus 120 operates as a terminal device and the other operates a network device, a transmission direction from the network device to the terminal device may be referred to as a downlink (DL), and a transmission direction from the terminal device to the network device may be referred to as an uplink (UL). In the example embodiments where both the first apparatus 110 and the second apparatus 120 operates as terminal devices, a link between the first apparatus 110 and the second apparatus 120 may be referred to as a sidelink (SL).

[0050] Communications in the communication environment 100 may be implemented according to any proper communication protocol(s), including, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0051] It is to be understood that the number and types of apparatuses are shown in FIG. 1 for the purpose of illustration, without suggesting any limitation. The communication environment 100 may include any suitable numbers and types of devices and apparatuses.

[0052] In the environment 100, the first apparatus 110 and the second apparatus 120 may establish a radio bearer for transmitting data packets in RLC AM. The HARQ retransmission and / or RLC ARQ retransmission may be used to ensure reliability of data packet transmission. In some example embodiments, RLC ARQ retransmissions triggered / requested by both the first apparatus 110 and the second apparatus 120 may be enabled when needed. Herein, such an RLC ARQ retransmission will also be referred to as an early RLC retransmission.

[0053] Some example embodiments with respect to the retransmissions triggered / requested by the first apparatus 110 will be described below with reference to FIGS. 2 and 3. Reference is first made to FIG. 2 which is a signaling diagram of communications between the first apparatus 110 and the second apparatus 120 for a joint feedback by the first apparatus 110 according to some example embodiments of the present disclosure. As shown in FIG. 2, in a process 200, the first apparatus 110 transmits (210), to the second apparatus 120, a joint retransmission feedback (207) requesting at least one of a first retransmission (212) of a first data packet (214) from a first protocol layer (215) of the second apparatus 120, or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the second apparatus 120. In the example embodiments where the first apparatus 110 operates as a terminal device and the second apparatus 110 operates as a network device, the first data packet may be a DL data packet.

[0054] The first protocol layer (215) and second protocol layer (217) may be any suitable protocol layer within the first apparatus 110 and the second apparatus 120. In some example embodiments, the second protocol layer may be a lower layer than the first protocol layer. In an example, the first protocol layer may include a RLC layer, and the second protocol layer may include a MAC layer or a PHY layer. Correspondingly, the first retransmission (212) of the first data packet (214) may include a RLC ARQ retransmission of the first data packet (214), and the second retransmission (216) of the first data packet (214) may include a HARQ retransmission of the first data packet (214).

[0055] By way of example, after the first apparatus 110 decodes the first data packet (214) received from the second apparatus 120, the first apparatus 110 may trigger an RLC ARQ retransmission though a joint retransmission feedback requesting from the second apparatus 120 at least one of an HARQ retransmission or an RLC ARQ retransmission. In this way, a feedback design may be provided for an HARQ and ARQ common feedback.

[0056] In some example embodiments, the joint retransmission feedback (207) may be carried in uplink control information (UCI). For example, the first apparatus 110 may use a physical uplink control channel (PUCCH) to carry the joint retransmission feedback (207). Alternatively, or in addition, the joint retransmission feedback (207) may be carried in a medium access control control element (MAC CE).

[0057] The joint retransmission feedback (207) may be implemented in any suitable form. In some example embodiments, the joint retransmission feedback (207) may be indicated in a plurality of bits. In one example, at least one first bit-value combination of the plurality of bits may be used to indicate a first request for the first retransmission (212) of the first data packet (214), and at least one second bit-value combination (which is different from the first bit-value combination) of the plurality of bits may be used to indicate a second request for the second retransmission (216) of the first data packet (214). In some example embodiments, the joint retransmission feedback (207) may correspond to a process of the second retransmission (216) of the first data packet (214). For example, instead of one bit feedback for each HARQ process, the first apparatus 110 may use a 2-bit “xy” feedback for the joint retransmission feedback. Two bits feedback may be carried over a MAC CE (assuming a MAC CE is used for carrying only a HARQ feedback as well). In an example, one or more code points of “xy” may request an HARQ retransmission, and one or more other code points of “xy” may request an ARQ retransmission. In another example, one of the 2 bits, e.g. the bit “x”, may request the HARQ retransmission, and the other of the 2 bits, e.g. the bit “y”, may request the ARQ retransmission.

[0058] In some example embodiments, the joint retransmission feedback (207) may include separate information to request the first retransmission (212) of the first data packet (214) and the second retransmission (216) of the first data packet (214), for example, including a first request for the first retransmission (212) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214). The first request may be indicated by a request for a change of a MCS for transmission of the first data packet (214) to indicate to the transmitter for changing the MCS. The second request may be indicated by a feedback for a transmission of the first data packet (214) from the second protocol layer (217) of the second apparatus 120.

[0059] For example, in the example embodiments where the joint retransmission feedback (207) is carried in UCI, additional UCI information in addition to a regular HARQ feedback may be needed to indicate the request of changing the MCS. In an example, the first apparatus 110 may use a PUCCH to carry 2 bits information for one HARQ process, including one bit for a regular HARQ feedback, and another bit utilized to indicate the request to change a MCS, which may be considered as a “super NACK”. A DL grant may be determined by the second apparatus 120 based on such a NACK feedback indicating whether a new MCS is to be used or not. For example, if a new MCS is indicated, the second apparatus 120 may determine a DL grant for the ARQ retransmission.

[0060] In some example embodiments, a first request for the first retransmission (212) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214) may be indicated by the joint retransmission feedback (207) in an alternative way. For example, at least one bit is used to indicate either the first request or the second request included in the joint retransmission feedback (207). In some example embodiments, the first apparatus 110 may transmit to the second apparatus 120, an indication whether the at least one bit indicates the first request or the second request.

[0061] For example, a bitmap indication may be used specifically for an ARQ operation per HARQ process. There may be a dedicated 1-bit indication per HARQ process but specifically marked for “ARQ”. By way of example, a PUCCH or a MAC CE may be used to carry the 1 bit per HARQ process, while the way in which the feedback is triggered may carry the information on whether the feedback is for HARQ or for ARQ. In this way, fewer bits per HARQ process may be allowed through a specific feedback format to indicate the feedback is about ARQ, not HARQ.

[0062] The indication whether the 1 bit is used to indicate “HARQ” or “ARQ” may be implemented in any suitable way. In an example, this indication may be accomplished by a specific acknowledgement (ACK) format. For example, the UCI or MAC CE may be related only to ARQ. If the first apparatus 110 requests the ARQ transmission, the first apparatus 110 may use the UCI or MAC CE to carry this request. Alternatively, or in addition, the indication may be accomplished by PUCCH resources. For example, if the first apparatus 110 requests the ARQ transmission, the first apparatus 110 may use specific PUCCH resources to carry this request. Alternatively, or in addition, the indication may be accomplished by a scheduling request (SR) that indicates an ARQ retransmission.

[0063] Some example implementations of the joint retransmission feedback based on MAC CE formats will be described below. In these examples, MAC CE formats for a HARQ process use Abstract Syntax Notation One (ASN. 1) and NR-style bit position formats.

[0064] In one example, a MAC CE may have 1 bit for each HARQ process, e.g. using 16 HARQ processes. ASN. 1 example 1 for a MAC CE with 1 bit for each HARQ process HARQ-Feedback ::= SEQUENCE { ackNackBitmap SEQUENCE (SIZE(1 ..maxHARQ)) OF BOOLEAN, } maxHARQ INTEGER ::= 16 — Maximum number of HARQ processes

[0065] Table 1 shows example bit positions for a MAC CE with 1 bit for each HARQ process. Table 1 HARQ Bit position 1 2 3 4 5 6 7 8 1 Octet 1 Pi P2 P3 P4 Ps P6 P7 Ps 2 Octet2 P9 Pio Ph P12 P13 P14 P15 P16

[0066] In this example, Pi may indicate an HARQ retransmission for a process i, e.g. 1=NACK, O=ACK.

[0067] In another example, a MAC CE may have 2 bits for each HARQ process, e.g. using 16 HARQ processes. In this example, the first apparatus 110 may request for HARQ retransmission and / or RLC ARQ retransmission using the 2 bits. ASN. 1 example 2 for a MAC CE with 2 bits for each HARQ process HARQ-Feedback ::= SEQUENCE{ ackNackBitmap SEQUENCE (SIZE( 1..maxHARQ)) OF HARQ-Status, HARQ-Status: := SEQUENCE { harqBitmap SEQUENCE (SIZE( 1..maxHARQ)) OF BOOLEAN, arqBitmap SEQUENCE (SIZE(L.maxHARQ)) OF BOOLEAN, maxHARQ INTEGER ::= 16 — Maximum number of HARQ processes

[0068] Table 2 shows example bit positions for a MAC CE with 2 bits for each HARQ process. Table 2 HARQ Bit position 1 2 3 4 5 6 7 8 1 Octet 1 Pi,i Pi,2 P2,i P2,2 P33 P3,2 P4,l P4,2 2 Octet2 P54 ?5,2 P6.i P6,2 P74 P?,2 P8,l Pg,2 3 Octet3 P93 P9,2 P10.1 P10,2 Pi 1,1 Pl 1.2 P12,l P12,2 4 Octet4 P13,l P13.2 Pi 4.1 P14,2 P15.1 P15,2 P16,l Pl 6.2

[0069] In this example, Pi,i may indicate an HARQ retransmission and Pi,2 may indicate an ARQ retransmission for the process i. For example, 1=NACK, 0=ACK.

[0070] In yet another example, a MAC CE may have 1 bit to indicate the HARQ retransmission and the RCL ARQ retransmission separately, e.g. using 16 HARQ processes. Each of the HARQ retransmission and the RCL ARQ retransmission may have its own Logical Channel identifier (LCID). In this example, the first apparatus 110 may request either the HARQ retransmission or the RCL ARQ retransmission by using one bit and transmit an indication whether the one bit indicates the HARQ retransmission or the RCL ARQ retransmission. ASN. 1 example 3 for a MAC CE for HARQ and a MAC CE for ARQ separately HARQ-Feedback ::= SEQUENCE { ackNackBitmap SEQUENCE (SIZE(1 ..maxHARQ)) OF BOOLEAN, } maxHARQ INTEGER ::= 16 — Maximum number of HARQ processes ARQ-Feedback ::= SEQUENCE { ackNackBitmap SEQUENCE (SIZE(1. maxHARQ)) OF BOOLEAN, } maxHARQ INTEGER ::= 16 — Maximum number of HARQ processes

[0071] Table 3 shows example bit positions for a MAC CE with 1 bit for an HARQ feedback. Table 3 HARQ Bit position 1 2 3 4 5 6 7 8 1 Octet 1 Pi P2 P3 P4 P5 P6 P7 P8 2 Octet2 P9 Pio Pn P12 P13 P14 P15 P16

[0072] In this example, Pi may indicate an HARQ retransmission for the process i, e.g. 1=NACK, 0=ACK.

[0073] Table 4 shows example bit positions for a MAC CE with 1 bit for an ARQ feedback. The bit positions for the ARQ feedback and the HARQ feedback may have the same structure, but have different meaning due to different LCIDs. Table 4 ARQ Bit position 1 2 3 4 5 6 7 8 1 Octet 1 Pi P2 P3 P4 P5 P6 P7 P8 2 Octet2 P9 Pio Pn Pi2 P13 P14 P15 P16

[0074] In this example, Pi may indicate an ARQ retransmission for the process i, e.g. 1=NACK, 0=ACK.

[0075] Still with reference to FIG. 2, after the second apparatus 120 receives (220) the joint retransmission feedback (207) from the first apparatus 110, the second apparatus 120 performs (225) at least one of the first retransmission (212) of the first data packet (214) or the second retransmission (216) of the first data packet (214), to the first apparatus 110, based on the joint retransmission feedback (207). Correspondingly, the first apparatus 110 receives (230) at least one of the first retransmission (212) or the second retransmission (216) of the first data packet (214).

[0076] For example, in the example embodiments where the first retransmission is a RLC ARQ retransmission and the second retransmission is an HARQ retransmission, the second apparatus 120 may determine, based on the detected feedback, whether an HARQ retransmission or an RLC ARQ retransmission is needed if the reception is not successful at the first apparatus 110. In an example, the second apparatus 120 may ignore the value of an HARQ feedback if the RLC ARQ retransmission is requested.

[0077] In some example embodiments, in the case that the first apparatus 110 operates as a terminal device and the second apparatus 120 operates as a network device, in the transmission of downlink data, the second apparatus 120 may already support an earlier RLC ARQ retransmission even without waiting for the feedback from the first apparatus 110. In this case, the second apparatus 120 may determine to change to the RLC ARQ retransmission instead of the HARQ retransmission and perform the RLC ARQ retransmission by itself without waiting for the feedback from the first apparatus 110.

[0078] In some example embodiments, as shown in FIG. 2, before the first apparatus 110 transmits (220) the joint retransmission feedback (207) to the second apparatus 120, the first apparatus 110 may receive (204), from the second apparatus 120, a prior configuration (203) indicating whether a joint feedback (205) is applied for transmissions of the first protocol layer (215) and the second protocol layer (217) of the second apparatus 120. Correspondingly, based on the configuration (204) indicating that the joint feedback (205) is applied, the first apparatus 110 may transmit the joint retransmission feedback (207). Thus, the transmission (210) of the joint retransmission feedback (207) may indicate that the prior configuration of the joint feedback (205, 317) is applied by the first apparatus (110, 305).

[0079] For example, the joint retransmission feedback may be carried in the UCI. In this example, depending on whether early RLC ARQ retransmission is configured or not, or a joint HARQ / ARQ feedback enabled or not, the content of the UCI, such as a UCI bit sequence, may be determined in different ways. If only HARQ-ACK / NACK bits are transmitted, the UCI bit sequence may be ao, ai, ...aN-i, where N is the number of HARQ processes and ax is a HARQ feedback corresponding to an HARQ process with an HARQ process identifier (HPID) x. If both HARQ-ACK / NACK bits and RLC ARQ retransmission request bits are transmitted, the combined UCI bit sequence is ao, bo, ai, bi, ...aN-i, bx-i, where by is used to indicate the request for the RLC ARQ retransmission for the data carried with an HARQ process with HP ID y.

[0080] In some example embodiments, the configuration (203) may be carried in radio resource control (RRC) signaling. For example, the second apparatus 120 may flexibly configure whether joint HARQ / ARQ feedback is applied or not with RRC signaling.

[0081] In some example embodiments, the configuration (203) may be associated with a quality of service (QoS) flow, a data radio bearer (DRB), a signaling radio bearer (SRB), a logical channel (LCH), a logical channel group (LCG), a PDU set, and / or an QoS identifier. For example, the second apparatus 120 may configure early RLC ARQ retransmission for a certain QoS flow, DRB, LCH, PDU set and / or 5G QoS Identifier.

[0082] In some example embodiments, as shown in FIG. 2, the first apparatus 110 may determine (206) to trigger the joint retransmission feedback (207), based on at least one condition having been satisfied. In some example embodiments, the at least one condition may include a condition that a remaining delay budget for the first data packet (214) is smaller than or equal to a threshold. For example, the first apparatus 110 may determine that the remaining packet delay budget (PDB) or PDU set delay budget (PSDB) may be smaller than a configured threshold, for example, when packet arrival information is known at the first apparatus 110 via e.g. burst arrival time (BAT) carried over Time Sensitive Communication Assistance Information (TSCAI). In this case, the first apparatus 110 may determine to trigger the joint retransmission feedback.

[0083] Alternatively, or in addition, the at least one condition may include a condition that a change of a MCS is required for a transmission of the first data packet (214). For example, by detecting the required number of HARQ retransmissions or decoding an outcome after HARQ combining, the first apparatus 110 may determine that the current MCS selection is too aggressive. Then, the first apparatus 110 may determine to trigger the joint retransmission feedback.

[0084] Alternatively, or in addition, the at least one condition may include a condition that a number of requests for the second retransmission (216) of the first data packet (214) from the lower second protocol layer (217) of the second apparatus (120, 310) is larger than or equal to a threshold number. For example, if the number of HARQ retransmissions reaches a threshold, the first apparatus 110 may determine to trigger the joint retransmission feedback.

[0085] An example process of a joint feedback by the first apparatus 110 will be described below with reference to FIG. 3 which shows a signaling flow 300 of UE requested early RLC ARQ retransmission for PDSCH according to some example embodiments of the present disclosure. In this example, a UE 305 is an example of the first apparatus 110, and a gNB 310 is an example of the second apparatus 120.

[0086] As shown in FIG. 3, in Step 315, the gNB 310 may configure (316) whether joint operation of HARQ / ARQ feedback (317) supported or not. In Step 320, the gNB 310 may transmit PDCCH including DCI for both DL resource allocation for PDSCH and also UL resource allocation for carrying HARQ / ARQ feedback. In Step 325, the UE 305 may decode received PDSCH and determining whether to trigger RLC ARQ retransmission (327). In Step 330, assuming decision of RLC ARQ retransmission is positive, the UE 305 may transmit the combined HARQ / ARQ feedback (332) to the gNB 310. In Step 335, based on the received feedback, the gNB 310 may determine the RLC ARQ retransmission (327) is requested by the UE 305. In Step 340, the gNB 310 may prepare data for the RLC ARQ retransmission (327). In Step 345, the gNB 310 may transmit PDCCH and PDSCH carrying the retransmitted RLC data (327) to the UE 305.

[0087] In this way, an earlier RLC retransmission may be enabled when needed. Further, a more reliable HARQ feedback may be provided if it is sent over a MAC CE.

[0088] In addition to the first apparatus 110, the second apparatus 120 may trigger or request retransmissions. For example, in the example embodiments where the first apparatus 110 operates as a terminal device and the second apparatus 110 operates as a network device, the second apparatus 120 may trigger an earlier RLC retransmission for UL data. Some example embodiments with respect to the retransmissions triggered / requested by the second apparatus 120 will be described below with reference to FIG. 4.

[0089] FIG. 4 is a signaling diagram of communications between the first apparatus 110 and the second apparatus 120 for a feedback by the second apparatus 120 for transmissions of the first apparatus 110 according to some example embodiments of the present disclosure.

[0090] As shown in FIG. 4, in a process 400, the second apparatus 120 transmits (410), to a first apparatus 110, a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the first apparatus 110, during a second retransmission (416) of the second data packet (414) from a lower second protocol layer (417) of the first apparatus 110.

[0091] In some example embodiments, the first retransmission (412) of the second data packet (414) may include RLC ARQ retransmission of the second data packet (414), and the second retransmission (416) of the first data packet may include a HARQ retransmission of the second data packet (414). In the example embodiments where the first apparatus 110 operates as a terminal device and the second apparatus 110 operates as a network device, the second data packet may be a UL data packet. For example, after the second apparatus 120 decodes the second data packet (414) received from the first apparatus 110, the second apparatus 120 may trigger an RLC ARQ retransmission by transmitting a request for the RLC ARQ retransmission, during the HARQ process.

[0092] After the first apparatus 110 receives the request, the first apparatus 110 performs (425) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the first apparatus 110 to the second apparatus 120. Correspondingly, the second apparatus 120 receives (430) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414).

[0093] In some example embodiments, the request (405) may be indicated in downlink control information (DCI) The DCI may be used for scheduling transmission from the first apparatus 110 to the second apparatus 120.

[0094] In some example embodiments, the request (405) may be indicated in one or more fields. In some example embodiments, the request (405) may be indicated by a value of a field or indicated by a combination of a plurality of fields.

[0095] In some example embodiments, the second apparatus 120 may determine to trigger the first retransmission (e.g. an RLC ARQ retransmission) of the second data packet in an explicit way and / or implicit way. In an example, the request (405) may be indicated in at least one bit, and the at least one bit may be dedicated as an explicit indication. For example, a new field including at least one bit may be used to indicate the request for the first retransmission of the second data packet.

[0096] In an example, one dedicated bit may be carried in a physical downlink control channel (PDCCH) / DCI to indicate whether a UL grant is used to request a RLC retransmission of the RLC PDU(s) of the HARQ process. Any type of UL grants are applicable, which may include both a dynamic grant and a semi-static grant (e.g. UL configured grant (CG)). The one dedicated bit may be used as an RLC retransmission request flag and included in DCI for UL scheduling. The RLC ARQ retransmission request flag may have 0 or 1 bit. For example, the RLC ARQ retransmission request flag is 0 bit if the early RLC retransmission is not configured, and 1 bit if the early RLC retransmission is configured. In the case that the RLC ARQ retransmission request flag is 1 bit, a value “0” of this flag may indicate that an RLC ARQ retransmission is not requested with the DCI, and a value “1” of this flag may indicate that an RLC ARQ retransmission is requested with the DCI.

[0097] In some other example embodiments, the at least one bit may be repurposed for indicating the request (405). For example, existing field(s) (e.g. by setting a specific value) or a combination of a plurality of fields (e.g. by setting specific values) may be reused to indicate the request (405). For example, if DCI includes an indication of a new MCS, but a New Data Indicator (NDI) is not toggled, the request (405) may be indicated. With such combination, the first apparatus 110 may infer that the second apparatus 120 is requesting the first retransmission (e.g. the RLC ARQ retransmission) of the second data packet.

[0098] In some example embodiments, as shown in FIG. 4, the second apparatus 120 may transmit (402), to the first apparatus 110, a configuration (403) indicating whether the request (405) for the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the first apparatus 110 is applied during the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the first apparatus 110. Correspondingly, the first apparatus 110 may receive (404) the configuration (403) from the second apparatus (120).

[0099] In some example embodiments, the configuration (403) may be carried in RRC signaling. In some example embodiments, the configuration (403) may be associated with a QoS flow, a DRB, a SRB, a LCH, a LCG and / or an QoS identifier.

[0100] In some example embodiments as shown in FIG. 4, the second apparatus 120 may determine (406) to trigger the request (405) for the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), based on at least one condition having been satisfied. In one example, the at least one condition may include a condition that a remaining delay budget for the second data packet (414) is smaller than or equal to a threshold. Alternatively, or in addition, the at least one condition may include a condition that a change of a MCS is required for transmission of the second data packet (414). Alternatively, or in addition, the at least one condition may include a condition that a number of requests (405) for the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the first apparatus 110 is larger than or equal to a threshold number. The threshold(s) herein may be predefined or configured by the network.

[0101] It is to be understood that the embodiments and / or implementations as described with respect to the retransmission triggered by the first apparatus 110 may also be appliable for the retransmission triggered by the second apparatus 120, and the details thereof will not be repeated.

[0102] FIG. 5 shows a flowchart of an example method 500 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0103] At block 510, the first apparatus (110) transmits (210, 330, 510), to a second apparatus (120, 310), a joint retransmission feedback (207, 332) requesting, from the second apparatus (120), at least one of a first retransmission (212, 320) of a first data packet (214) from a first protocol layer (215) of the second apparatus (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the second apparatus (120, 310).

[0104] At block 520, the first apparatus (110) receives (230, 345, 520) at least one of the first retransmission (212, 327) or the second retransmission (216) of the first data packet (214), after the transmission (210, 330, 510) of the joint retransmission feedback (207, 332).

[0105] In some example embodiments, the first apparatus (110, 305) may receive (204, 315), from the second apparatus (120, 310), a prior configuration (203, 316) indicating whether a joint feedback (205, 317) is applied for transmissions of at least one of the first protocol layer (215) or the second protocol layer (217) of the second apparatus (120, 310). The transmission (210, 330, 510) of the joint retransmission feedback (207, 332) may indicate that the prior configuration of the joint feedback (205, 317) is applied by the first apparatus (110, 305).

[0106] In some example embodiments, the configuration (203, 316) may be carried in radio resource control (RRC) signaling.

[0107] In some example embodiments, the configuration (203, 316) may be associated with at least one of: a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set, or an QoS identifier.

[0108] In some example embodiments, the joint retransmission feedback (207, 332) may be indicated in a plurality of bits.

[0109] In some example embodiments, at least one first bit-value combination of the plurality of bits may be used to indicate a first request for the first retransmission (212, 327) of the first data packet (214), and at least one second bit-value combination of the plurality of bits may be used to indicate a second request for the second retransmission (216) of the first data packet (214). The first bit-value combination may be different from the second bit-value combination.

[0110] In some example embodiments, the joint retransmission feedback (207, 332) may include a first request for the first retransmission (212, 327) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214). The first request may be indicated by a request for a change of a modulation and coding scheme (MCS) for a transmission of the first data packet (214), and the second request may be indicated by a feedback for a transmission of the first data packet (214) from the second protocol layer (217) of the second apparatus (120, 310). The second protocol layer may be a lower layer than the first protocol layer.

[0111] In some example embodiments, the joint retransmission feedback (207, 332) may include a first request for the first retransmission (212, 327) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214). At least one bit may be used to indicate either the first request or the second request.

[0112] In some example embodiments, the first apparatus (110, 305) may transmit, to the second apparatus (120, 310), an indication whether the at least one bit indicates the first request or the second request. In some example embodiments, the first apparatus (110, 305) may determine (206, 325) to trigger the joint retransmission feedback (207, 332), based on at least one condition having been satisfied. The at least one condition may include at least one of a condition that a remaining delay budget for the first data packet (214) is smaller than or equal to a threshold, a condition that a change of a modulation and coding scheme (MCS) is required for transmission of the first data packet (214), or a condition that a number of requests for the second retransmission (216) of the first data packet (214) from the second protocol layer (217) of the second apparatus (120, 310) is larger than or equal to a threshold number.

[0113] In some example embodiments, the joint retransmission feedback (207, 332) may correspond to a process of the second retransmission (216) of the first data packet (214). In some example embodiments, the joint retransmission feedback (207, 332) is carried in at least one of uplink control information (UCI) or a medium access control control element (MAC CE).

[0114] In some example embodiments, the first retransmission (212, 327) of the first data packet (214) may include radio link control (RLC) automatic repeat request (ARQ) retransmission (327) of the first data packet (214), and the second retransmission (216) of the first data packet (214) may include a hybrid automatic repeat request (HARQ) retransmission of the first data packet (214).

[0115] FIG. 6 shows a flowchart of an example method 600 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0116] At block 610, the second apparatus (120) receives (220, 330, 610), from a first apparatus (110, 305), a joint retransmission feedback (207, 332) requesting at least one of a first retransmission (212, 327) of a first data packet (214) from a first protocol layer (215) of the second apparatus (120, 310), or a second retransmission (216) of the first data packet (214) from a second protocol layer (217) of the second apparatus (120, 310).

[0117] At block 620, the second apparatus (120) performs (225, 345, 620), based on the joint retransmission feedback (207, 332), at least one of the first retransmission (212, 327) of the first data packet (214) or the second retransmission (216) of the first data packet (214), to the first apparatus (110, 305).

[0118] In some example embodiments, the second apparatus (120, 310) may transmit (202, 315), to the first apparatus (110, 305), a prior configuration (203, 316) indicating whether a joint feedback (205, 317) is applied for transmissions of at least one of the first protocol layer (215) or the second protocol layer (217) of the second apparatus (120, 310).

[0119] In some example embodiments, the configuration (203, 316) may be carried in radio resource control (RRC) signaling.

[0120] In some example embodiments, the configuration (203, 316) may be associated with at least one of: a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set, or an QoS identifier.

[0121] In some example embodiments, the joint retransmission feedback (207, 332) may be indicated in a plurality of bits.

[0122] In some example embodiments, at least one first bit-value combination of the plurality of bits may be used to indicate a first request for the first retransmission (212, 327) of the first data packet (214), and at least one second bit-value combination of the plurality of bits may be used to indicate a second request for the second retransmission (216) of the first data packet (214). The first bit-value combination may be different from the second bit-value combination.

[0123] In some example embodiments, the joint retransmission feedback (207, 332) may include a first request for the first retransmission (212, 327) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214). The first request may be indicated by a request for a change of a modulation and coding scheme (MCS) for transmission of the first data packet (214), and the second request may be indicated by feedback for transmission of the first data packet (214) from the second protocol layer (217) of the second apparatus (120, 310). The second protocol layer may be a lower layer than the first protocol layer.

[0124] In some example embodiments, the joint retransmission feedback (207, 332) may include a first request for the first retransmission (212, 327) of the first data packet (214) and a second request for the second retransmission (216) of the first data packet (214). At least one bit may be used to indicate either the first request or the second request.

[0125] In some example embodiments, the second apparatus (120, 310) may receive, from the first apparatus (110, 305), an indication whether the at least one bit indicates the first request or the second request.

[0126] In some example embodiments, the joint retransmission feedback (207, 332) may correspond to a process of the second retransmission (216) of the first data packet (214). In some example embodiments, the joint retransmission feedback (207, 332) may be carried in at least one of uplink control information (UCI) or a medium access control control element (MAC CE).

[0127] In some example embodiments, the first retransmission (212, 327) of the first data packet (214) may include radio link control (RLC) automatic repeat request (ARQ) retransmission (327) of the first data packet (214), and the second retransmission (216) of the first data packet (214) may include a hybrid automatic repeat request (HARQ) retransmission of the first data packet (214).

[0128] FIG. 7 shows a flowchart of an example method 700 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0129] At block 710, the first apparatus (110) receives (410, 710), from a second apparatus (120), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the first apparatus (HO), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the first apparatus (110).

[0130] At block 720, in response to the receiving of the request (405) for the first retransmission (412) of the second data packet (414), the first apparatus (110) performs (425, 720) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the first apparatus (110) to the second apparatus (120).

[0131] In some example embodiments, the request (405) may be indicated in downlink control information (DCI). The DCI may be used for scheduling transmission from the first apparatus (110) to the second apparatus (120).

[0132] In some example embodiments, the request (405) may be indicated in at least one bit, and the at least one bit is dedicated or repurposed for indicating the request (405).

[0133] In some example embodiments, the request (405) may be indicated in one or more fields.

[0134] In some example embodiments, the request (405) may be indicated by a value of a field or indicated by a combination of a plurality of fields.

[0135] In some example embodiments, the first apparatus (110) may receive (404), from the second apparatus (120), a configuration (403) indicating whether the request (405) for the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the first apparatus (110) is applied during the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the first apparatus (HO).

[0136] In some example embodiments, the configuration (403) may be carried in radio resource control (RRC) signaling.

[0137] In some example embodiments, the configuration (403) may be associated with at least one of a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set or an QoS identifier.

[0138] In some example embodiments, the first retransmission (412) of the second data packet (414) may include radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet (414), and the second retransmission (416) of the first data packet may include a hybrid automatic repeat request (HARQ) retransmission of the second data packet (414).

[0139] In some example embodiments, the second protocol layer may be a lower layer than the first protocol layer.

[0140] FIG. 8 shows a flowchart of an example method 800 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0141] At block 810, the second apparatus (120) transmits (410, 810), to a first apparatus (HO), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the first apparatus (HO), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the first apparatus (110).

[0142] At block 820, the second apparatus (120) receives (430, 820) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), after transmitting the request (405) for the first retransmission (412) of the second data packet (414).

[0143] In some example embodiments, the request (405) may be indicated in downlink control information (DCI), the DCI used for scheduling transmission from the first apparatus (110) to the second apparatus (120).

[0144] In some example embodiments, the request (405) is indicated in at least one bit, and the at least one bit is dedicated or repurposed for indicating the request (405).

[0145] In some example embodiments, the request (405) may be indicated in one or more fields.

[0146] In some example embodiments, the request (405) may be indicated by a value of a field or indicated by a combination of a plurality of fields.

[0147] In some example embodiments, the second apparatus (120) may transmit (402), to the first apparatus (110), a configuration (403) indicating whether the request (405) for the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the first apparatus (110) is applied during the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the first apparatus (HO).

[0148] In some example embodiments, the configuration (403) may be carried in radio resource control (RRC) signaling.

[0149] In some example embodiments, the configuration (403) may be associated with at least one of: a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set, or an QoS identifier.

[0150] In some example embodiments, the second apparatus (120) may determine (406) to trigger the request (405) for the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), based on at least one condition having been satisfied. The at least one condition may include at least one of a condition that a remaining delay budget for the second data packet (414) is smaller than or equal to a threshold, a condition that a change of a modulation and coding scheme (MCS) is required for transmission of the second data packet (414), or a condition that a number of requests (405) for the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the first apparatus (110) is larger than or equal to a threshold number.

[0151] In some example embodiments, the first retransmission (412) of the second data packet (414) may include radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet (414), and the second retransmission (416) of the second data packet may include a hybrid automatic repeat request (HARQ) retransmission of the second data packet (414).

[0152] In some example embodiments, the second protocol layer may be a lower layer than the first protocol layer.

[0153] In some example embodiments, the first apparatus 110 and the second apparatus 120 may include means for performing the respective operations of the methods 500 to 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0154] FIG. 9 is a simplified block diagram of a device 900 that is suitable for implementing example embodiments of the present disclosure. The device 900 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1. As shown, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processor 910, and one or more communication modules 940 coupled to the processor 910.

[0155] The communication module 940 is for bidirectional communications. The communication module 940 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 940 may include at least one antenna.

[0156] The processor 910 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 900 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0157] The memory 920 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 924, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 922 and other volatile memories that will not last in the power-down duration.

[0158] A computer program 930 includes computer executable instructions that are executed by the associated processor 910. The instructions of the program 930 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 930 may be stored in the memory, e.g., the ROM 924. The processor 910 may perform any suitable actions and processing by loading the program 930 into the RAM 922.

[0159] The example embodiments of the present disclosure may be implemented by means of the program 930 so that the device 900 may perform any process of the disclosure as discussed with reference to FIG. 1 to FIG. 8. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0160] In some example embodiments, the program 930 may be tangibly contained in a computer readable medium which may be included in the device 900 (such as in the memory 920) or other storage devices that are accessible by the device 900. The device 900 may load the program 930 from the computer readable medium to the RAM 922 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e g., RAM vs. ROM).

[0161] FIG. 10 shows an example of the computer readable medium 1000 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1000 has the program 930 stored thereon.

[0162] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0163] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computerexecutable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0164] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0165] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0166] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0167] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

[0168] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0169] Various example embodiments of the techniques have been described. In addition to or as an alternative to the above, the following examples are described. The features described in any of the following examples may be utilized with any of the other examples described herein.

[0170] Example 1. A terminal device (110) for data packets retransmission including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device (110) at least to: receive (410, 710), from a network device (120), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (110), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (HO); and in response to the receiving of the request (405) for the first retransmission (412) of the second data packet (414), perform (425, 720) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) to the network device (120).

[0171] Example 2. The terminal device (110) of example 1, where the request (405) is indicated via one or more of: in downlink control information (DCI), the DCI used for scheduling transmission from the terminal device (110) to the network device (120); in at least one bit, the at least one bit dedicated or repurposed for indicating the request (405); in one or more fields; or by a value of a field or indicated by a combination of a plurality of fields.

[0172] Example 3. The terminal device (110) of any of examples 1 to 2, where the instructions that, when executed by the at least one processor, cause the terminal device (110) to: receive (404), from the network device (120), a configuration (403) indicating whether the request (405) for the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) is applied during the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the terminal device (HO).

[0173] Example 4. The terminal device (110) of example 3, where the configuration (403) is carried in radio resource control (RRC) signaling.

[0174] Example 5. The terminal device (110) of example 3 or 4, where the configuration (403) is associated with at least one of: a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set, or a QoS identifier.

[0175] Example 6. The terminal device (110) of any of examples 1 to 5, where the first retransmission (412) of the second data packet (414) includes radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet (414), and the second retransmission (416) of the first data packet includes a hybrid automatic repeat request (HARQ) retransmission of the second data packet (414).

[0176] Example 7. The terminal device (110) of any of examples 1 to 6, where the second protocol layer is a lower layer than the first protocol layer.

[0177] Example 8. A network device (120) for data packets retransmission including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device (120) at least to: transmit (410, 810), to a terminal device (110), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (HO), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (110); and receive (430, 820) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), after transmitting the request (405) for the first retransmission (412) of the second data packet (414).

[0178] Example 9. The network device (120) of example 8, where the request (405) is indicated via one or more of: in downlink control information (DCI), the DCI used for scheduling transmission from the terminal device (110) to the network device (120); in at least one bit, the at least one bit dedicated or repurposed for indicating the request (405); in one or more fields; or by a value of a field or indicated by a combination of a plurality of fields.

[0179] Example 10. The network device (120) of any of examples 8 to 9, where the instructions that, when executed by the at least one processor, cause the network device (120) to: transmit (402), to the terminal device (HO), a configuration (403) indicating whether the request (405) for the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) is applied during the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the terminal device (110).

[0180] Example 11. The network device (120) of example 10, where the configuration (403) is carried in radio resource control (RRC) signaling.

[0181] Example 12. The network device (120) of example 10 or 11, where the configuration (403) is associated with at least one of: a quality of service (QoS) flow, a data radio bearer, a signalling radio bearer, a logical channel, a logical channel group, a protocol data unit (PDU) set, or a QoS identifier.

[0182] Example 13. The network device (120) of any of examples 8 to 12, where the instructions that, when executed by the at least one processor, cause the network device (120) to: determine (406) to trigger the request (405) for the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), based on at least one condition having been satisfied, the at least one condition including at least one of: a condition that a remaining delay budget for the second data packet (414) is smaller than or equal to a threshold, a condition that a change of a modulation and coding scheme (MCS) is required for transmission of the second data packet (414), or a condition that a number of requests (405) for the second retransmission (416) of the second data packet (414) from the lower second protocol layer (417) of the terminal device (110) is larger than or equal to a threshold number.

[0183] Example 14. The network device (120) of any of examples 8 to 13, where the first retransmission (412) of the second data packet (414) includes radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet (414), and the second retransmission (416) of the second data packet includes a hybrid automatic repeat request (HARQ) retransmission of the second data packet (414).

[0184] Example 15. The network device (120) of any of examples 8 to 14, where the second protocol layer is a lower layer than the first protocol layer.

[0185] Example 16. A terminal device (110) for data packets retransmission including: means for receiving (410, 710), from a network device (120), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (110), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (HO); and means for in response to the receiving of the request (405) for the first retransmission (412) of the second data packet (414), performing (425, 720) the first retransmission (412) of the second data packet (414) from the first protocol layer (415) of the terminal device (110) to the network device (120).

[0186] Example 17. A network device (120) for data packets retransmission including: means for transmitting (410, 810), to a terminal device (HO), a request (405) for a first retransmission (412) of a second data packet (414) from a first protocol layer (415) of the terminal device (HO), during a second retransmission (416) of the second data packet (414) from a second protocol layer (417) of the terminal device (HO); and means for receiving (430, 820) the first retransmission (412) of the second data packet (414) during the second retransmission (416) of the second data packet (414), after transmitting the request (405) for the first retransmission (412) of the second data packet (414).

Claims

1. A terminal device for data packets retransmission, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to:receive, from a network device, a request for a first retransmission of a second data packet from a first protocol layer of the terminal device, during a second retransmission of the second data packet from a second protocol layer of the terminal device; andin response to the receiving of the request for the first retransmission of the second data packet, perform the first retransmission of the second data packet from the first protocol layer of the terminal device to the network device.

2. The terminal device of claim 1, wherein the request is indicated via one or more of:in downlink control information (DCI), the DCI used for scheduling transmission from the terminal device to the network device;in at least one bit, the at least one bit dedicated or repurposed for indicating the request;in one or more fields; orby a value of a field or indicated by a combination of a plurality of fields.

3. The terminal device of any of claims 1 to 2, wherein the instructions that, when executed by the at least one processor, cause the terminal device to:receive, from the network device, a configuration indicating whether the request for the first retransmission of the second data packet from the first protocol layer of the terminal device is applied during the second retransmission of the second data packet from the lower second protocol layer of the terminal device.

4. The terminal device of claim 3, wherein the configuration is carried in radio resource control (RRC) signaling.

5. The terminal device of claim 3 or 4, wherein the configuration is associated with at least one of:a quality of service (QoS) flow,a data radio bearer,a signalling radio bearer,a logical channel,a logical channel group,a protocol data unit (PDU) set ora QoS identifier.

6. The terminal device of any of claims 1 to 5, wherein the first retransmission of the second data packet comprises radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet, and the second retransmission of the first data packet comprises a hybrid automatic repeat request (HARQ) retransmission of the second data packet.

7. The terminal device of any of claims 1 to 6, wherein the second protocol layer is a lower layer than the first protocol layer.

8. A network device for data packets retransmission, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to:transmit, to a terminal device, a request for a first retransmission of a second data packet from a first protocol layer of the terminal device, during a second retransmission of the second data packet from a second protocol layer of the terminal device; andreceive the first retransmission of the second data packet during the second retransmission of the second data packet, after transmitting the request for the first retransmission of the second data packet.

9. The network device of claim 8, wherein the request is indicated via one or more of:in downlink control information (DCI), the DCI used for scheduling transmission from the terminal device to the network device;in at least one bit, the at least one bit dedicated or repurposed for indicating the request;in one or more fields; orby a value of a field or indicated by a combination of a plurality of fields.

10. The network device of any of claims 8 to 9, wherein the instructions that, when executed by the at least one processor, cause the network device to:transmit, to the terminal device, a configuration indicating whether the request forthe first retransmission of the second data packet from the first protocol layer of the terminal device is applied during the second retransmission of the second data packet from the lower second protocol layer of the terminal device.

11. The network device of claim 10, wherein the configuration is carried in radio resource control (RRC) signaling.

12. The network device of claim 10 or 11, wherein the configuration is associated with at least one of:a quality of service (QoS) flow,a data radio bearer,a signalling radio bearer,a logical channel,a logical channel group,a protocol data unit (PDU) set, ora QoS identifier.

13. The network device of any of claims 8 to 12, wherein the instructions that, when executed by the at least one processor, cause the network device to:determine to trigger the request for the first retransmission of the second data packet during the second retransmission of the second data packet, based on at least one condition having been satisfied, the at least one condition comprising at least one of:a condition that a remaining delay budget for the second data packet is smaller than or equal to a threshold,a condition that a change of a modulation and coding scheme (MCS) is required for transmission of the second data packet, ora condition that a number of requests for the second retransmission of the second data packet from the lower second protocol layer of the terminal device is larger than or equal to a threshold number.

14. The network device of any of claims 8 to 13, wherein the first retransmission of the second data packet comprises radio link control (RLC) automatic repeat request (ARQ) retransmission of the second data packet, and the second retransmission of the second data packet comprises a hybrid automatic repeat request (HARQ) retransmission of the second data packet.

15. The network device of any of claims 8 to 14, wherein the second protocol layer is a lower layer than the first protocol layer.

16. A terminal device for data packets retransmission, comprising:means for receiving, from a network device, a request for a first retransmission of a second data packet from a first protocol layer of the terminal device, during a second retransmission of the second data packet from a second protocol layer of the terminal device; andmeans for in response to the receiving of the request for the first retransmission of the second data packet, performing the first retransmission of the second data packet from the first protocol layer of the terminal device to the network device.

17. A network device for data packets retransmission, comprising:means for transmitting, to a terminal device, a request for a first retransmission of a second data packet from a first protocol layer of the terminal device, during a second retransmission of the second data packet from a second protocol layer of the terminal device; andmeans for receiving the first retransmission of the second data packet during the second retransmission of the second data packet, after transmitting the request for the first retransmission of the second data packet.

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