Discontinuous reception mechanism supporting blind retransmission

Abstract

Example embodiments of the present disclosure relate to discontinuous reception (DRX) mechanisms. According to some example embodiments, a first device receives control information from a second device, the control information indicating a first retransmission scheme to be applied to transmission of data between the first device and the second device, the first retransmission scheme requiring retransmission of data to be performed independently of feedback for a previous transmission of the data. The first device also receives, from the second device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing, and determines, based on the retransmission timing, a timing for monitoring for further control information from the second device for scheduling the retransmission. The solution provides scheduling and transmission flexibility for the retransmission scheme.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and particularly to methods, devices, apparatuses, and computer-readable storage media for discontinuous reception (DRX). BACKGROUND

[0002] As communication systems evolve, new technologies have been proposed. Third Generation Partnership Project (3GPP) Release (Rel) 16 includes work on how Fifth Generation (5G) New Radio (NR) standards support Non-Terrestrial Network (NTN) deployments using satellites and High Altitude Platform Stations (HAPS) to provide connectivity across wide service areas. In many NTN deployment scenarios, the round-trip time (RTT) of signal propagation can be much longer compared to terrestrial networks for NR interfaces. As a result, these longer propagation delays can pose challenges to Discontinuous Reception (DRX) in Hybrid Automatic Repeat Request (HARQ) procedures for retransmission of erroneous packets. It is therefore desirable to improve DRX operation in scenarios with longer RTT delays, such as in NTNs. SUMMARY

[0003] Generally, example embodiments of the present disclosure provide a solution for DRX that can be applied, for example, but not limited to, communication scenarios that support blind retransmissions.

[0004] In a first aspect, a first device is provided. The first device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: receive, from a second device, control information indicating a first retransmission scheme to be applied for transmissions of data between the first device and the second device, the first retransmission scheme requiring retransmission of data to be performed independently of feedback for a previous transmission of the data; receive, from the second device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing; and determine, based on the retransmission timing, a timing for monitoring for further control information from the second device for scheduling the retransmission.

[0005] In a second aspect, a first device is provided. The first device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: receive, from a second device, a first configuration of a first timer for a first retransmission scheme; receive, from the second device, a second configuration of a second timer for a second retransmission scheme different from the first retransmission scheme; and in accordance with a determination that the first retransmission scheme is to be applied for transmissions of data between the first device and the second device, set a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

[0006] In a third aspect, a second device is provided. The second device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to: transmit, to a first device, control information indicating a first retransmission scheme to be applied to transmissions of data between the first device and the second device, the first retransmission scheme requiring retransmission of data to be performed independently of feedback to a previous transmission of the data; and transmit, to the first device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure a timing for the first device to monitor for further control information from the second device for scheduling the retransmission.

[0007] In a fourth aspect, a second device is provided. The second device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to: transmit, to a first device, a first configuration of a first timer of the first device for a first retransmission scheme; transmit, to the first device, a second configuration of a second timer of the first device for a second retransmission scheme different from the first retransmission scheme; and transmit, to the first device, control information indicating that the first retransmission scheme is to be applied to transmissions of data between the first device and the second device, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

[0008] In a fifth aspect, a method is provided. The method comprises: receiving, at a first device and from a second device, control information indicating a first retransmission scheme to be applied to transmissions of data between the first device and the second device, the first retransmission scheme requiring retransmission of data to be performed independently of feedback to a previous transmission of the data; receiving, from the second device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing; and determining a timing for monitoring for further control information from the second device for scheduling the retransmission based on the retransmission timing.

[0009] In a sixth aspect, a method is provided. The method comprises: receiving, at a first device and from a second device, a first configuration of a first timer for a first retransmission scheme; receiving, from the second device, a second configuration of a second timer for a second retransmission scheme different from the first retransmission scheme; and based on a determination that the first retransmission scheme is to be applied to transmissions of data between the first device and the second device, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

[0010] In a seventh aspect, a method is provided. The method comprises: transmitting, at a second device and to a first device, control information indicating a first retransmission scheme to be applied for transmissions of data between the first device and the second device, the first retransmission scheme requiring retransmission of data to be performed independently of feedback for a previous transmission of the data; and transmitting, to the first device and via a physical layer downlink control channel, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure a timing for the first device to monitor for further control information from the second device for scheduling the retransmission.

[0011] In an eighth aspect, a method is provided. The method comprises: transmitting, at a second device and to a first device, a first configuration of a first timer of the first device for a first retransmission scheme; transmitting, to the first device, a second configuration of a second timer of the first device for a second retransmission scheme different from the first retransmission scheme; and transmitting, to the first device, control information indicating that the first retransmission scheme is to be applied for transmissions of data between the first device and the second device, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

[0012] In a ninth aspect, a first apparatus is provided. The first apparatus comprises means for: receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied for transmissions of data between the first apparatus and the second apparatus, the first retransmission scheme requiring retransmission of data to be performed independently of feedback for a previous transmission of the data; receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing; and determining, based on the retransmission timing, a timing for monitoring for further control information from the second apparatus for scheduling the retransmission.

[0013] In a tenth aspect, a first apparatus is provided. The first apparatus comprises means for: receiving, from a second apparatus, a first configuration of a first timer for a first retransmission scheme; receiving, from the second apparatus, a second configuration of a second timer for a second retransmission scheme different from the first retransmission scheme; and based on a determination that the first retransmission scheme is to be applied for transmissions of data between the first apparatus and the second apparatus, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

[0014] In an eleventh aspect, a second apparatus is provided. The second apparatus comprises means for: transmitting, to a first apparatus, control information indicating a first retransmission scheme to be applied for transmissions of data between the first apparatus and the second apparatus, the first retransmission scheme requiring retransmission of data to be performed independently of feedback for a previous transmission of the data; and transmitting, to the first apparatus via a physical layer downlink control channel, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure a timing for the first apparatus to monitor for further control information from the second apparatus for scheduling a retransmission.

[0015] In a twelfth aspect, a second apparatus is provided. The second apparatus comprises means for: transmitting, to a first apparatus, a first configuration of a first timer of the first apparatus for a first retransmission scheme; transmitting, to the first apparatus, a second configuration of a second timer of the first apparatus for a second retransmission scheme different from the first retransmission scheme; and transmitting, to the first apparatus, control information indicating the first retransmission scheme to be applied for transmissions of data between the first apparatus and the second apparatus, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

[0016] In a thirteenth aspect, a computer readable medium is provided. The computer readable medium comprises program instructions for causing an apparatus to perform at least the method according to any of the fifth and eighth aspects above.

[0017] It is to be understood that the Summary is not intended to identify key or essential features of embodiments of the disclosure, nor is it intended to limit the scope of the disclosure. Other aspects of the disclosure will become readily apparent to those skilled in the art by review of the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] Some example embodiments will now be described with reference to the drawings, in which:

[0019] Figure 1 a communication system in which example embodiments of the disclosure can be implemented is illustrated;

[0020] Figure 2 a signalling flow for data retransmission according to some example embodiments of the disclosure is illustrated;

[0021] Figure 3 a signalling flow for data retransmission in downlink (DL) according to some example embodiments of the disclosure is illustrated;

[0022] Figure 4 a signalling flow for data retransmission in uplink (UL) according to some example embodiments of the disclosure is illustrated;

[0023] Figure 5signaling procedure for data retransmission in DL is illustrated, in accordance with some other example embodiments of the disclosure;

[0024] Figure 6 signaling procedure for data retransmission is illustrated, in accordance with some other example embodiments of the disclosure;

[0025] Figure 7 signaling procedure for data retransmission in DL is illustrated, in accordance with some other example embodiments of the disclosure;

[0026] Figure 8 signaling procedure for data retransmission in UL is illustrated, in accordance with some other example embodiments of the disclosure;

[0027] Figure 9 signaling procedure for data retransmission in DL is illustrated, in accordance with some other example embodiments of the disclosure;

[0028] Figure 10 signaling procedure for data retransmission in UL is illustrated, in accordance with some other example embodiments of the disclosure;

[0029] Figure 11 a flow diagram of a method implemented at a first device, in accordance with some example embodiments of the disclosure is illustrated;

[0030] Figure 12 a flow diagram of a method implemented at a first device, in accordance with some other example embodiments of the disclosure is illustrated;

[0031] Figure 13 a flow diagram of a method implemented at a second device, in accordance with some example embodiments of the disclosure is illustrated;

[0032] Figure 14 a flow diagram of a method implemented at a second device, in accordance with some other example embodiments of the disclosure is illustrated;

[0033] Figure 15 a simplified block diagram of a device suitable for implementing example embodiments of the disclosure is illustrated; and

[0034] Figure 16 a block diagram of an example computer-readable medium, in accordance with some example embodiments of the disclosure is illustrated.

[0035] Throughout the drawings, identical or similar reference numerals can represent same or similar elements. DETAILED DESCRIPTION

[0036] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that the embodiments are described for illustrative purposes only and do not represent any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various other ways than described below.

[0037] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0038] Reference throughout this disclosure to “one embodiment”, “an embodiment”, “example embodiment” and so on, means that a described embodiment can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Furthermore, such phrases are not necessarily referring to the same embodiment. Furthermore, where a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described or claimed.

[0039] It should be understood that although the terms “first” and “second” and so on can be used herein to describe various elements, the elements should not be limited by such terms. These terms are only used to distinguish one element from another. 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 the example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed terms.

[0040] 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 will 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.

[0041] As used in this application, the term “circuitry” can refer to one or more or all of the following:

[0042] (a) hardware-only circuitry implementations (such as implementations in only analog and / or digital circuitry) and

[0043] (b) combinations of hardware circuits and software, such as (as applicable):

[0044] (i) combinations of hardware circuits and software / firmware, such as (as applicable):

[0045] (ii) hardware processor(s) with software, including digital signal processor(s), software, and memory(ies) that together form a processing system, which work together to cause an apparatus, such as a mobile phone or server, to perform various functions, and

[0046] (c) hardware circuitry and / or processor(s), such as a microprocessor(s) or a portion of microprocessor(s), that requires software (e.g., firmware) for operation

[0047] for operation, but can not exist when not needed for operation.

[0048] The 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 that includes one or more processors and / or a processor(s) working in combination with a software or firmware application(s) that are an integral part of the hardware, such as an operating system application or the like. For example, if a claim element includes circuitry, and a processor or processor(s) working in combination with software are an integral part of the hardware for that claim element, then a processor running software embodied on a non-transitory medium would be a hardware implementation of that claim element, specifically a processor-based hardware implementation.

[0049] As used herein, the term “communication network” refers to a network that follows any appropriate 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), etc. In addition, communication between terminal devices and network devices in a communication network can be performed according to any appropriate communication protocol of the day, including but not limited to first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) communication protocols, and / or any other protocols that are currently known or developed in the future. Embodiments of the present disclosure can be applied in various communication systems. In view of the rapid development in communications, there will of course also be future communication technology and systems that can implement the present disclosure. It should not be seen as limiting the scope of the present disclosure to the above-described systems only.

[0050] As used herein, the term “network device” refers to a node in a communication network via which terminal devices access the network and receive services therefrom. The network device can refer to a base station (BS) or an access point (AP), such as a NodeB (or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also known as gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, a low-power node (such as a femto, pico), a non-terrestrial network (NTN) or non-ground network device (such as a satellite network device, low earth orbit (LEO) satellite, and geosynchronous earth orbit (GEO) satellite), an airplane network device, and the like, depending on the terminology used and the technology applied.

[0051] The term “terminal device” refers to any terminal device capable of wireless communication. By way of example, and without limitation, a terminal device can 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). A terminal device can include, but is not limited to, a mobile telephone, a cellular telephone, a smart phone, a voice over Internet Protocol (VoIP) telephone, a wireless local loop (WLL) telephone, a tablet, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device, such as a digital camera, a gaming terminal device, a music storage and playback appliance, a vehicular wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a USB dongle, a smart device, a wireless customer-premise equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical appliance or application, such as a remote surgery appliance or application, an industrial appliance or application, such as an industrial or automated processing chain

[0052] Example Environment and Operation

[0053] Figure 1 An example communication system 100 in which example embodiments of the present disclosure can be implemented is shown. In Figure 1 In an example, two types of communication networks are shown, including a non-terrestrial network (NTN) or non-ground network having one or more NTN network devices or non-ground network devices for providing communication coverage, and a terrestrial network (TN) or ground network having one or more terrestrial or ground network devices for providing communication coverage.

[0054] In the NTN network, the first device 110-1 and the second device 120-1 can communicate with each other. In this example, the first device 110-1 is illustrated as a terminal device, and the second device 120-1 is illustrated as an NTN network device serving the terminal device. The service area of the second device 120-1 is referred to as a cell 102-1. In the TN network, the first device 110-2 and the second device 120-2 can communicate with each other. In this example, the first device 110-2 is illustrated as a terminal device, and the second device 120-2 is illustrated as a TN network device serving the terminal device. The service area of the second device 120-2 is referred to as a cell 102-2. For ease of discussion, hereinafter, the first devices 110-1 and 110-2 are collectively or individually referred to as the first device 110, the second devices 120-1 and 120-2 are collectively or individually referred to as the second device 120, and the cells 102-1 and 102-2 are collectively or individually referred to as the cell 102.

[0055] It should be appreciated that the number of first devices and second devices is for illustrative purposes only and is not meant to be limiting. The communication system 100 can include any suitable number of first devices and second devices suitable for implementing embodiments of the present disclosure. Although not shown, it should be appreciated that one or more additional terminal devices can be located in the cell 102 and served by the second device 120.

[0056] Communication in the communication system 100 can be implemented in accordance with any suitable communication protocol(s), including but not limited to cellular communication protocols of first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol that is currently known or developed in the future. Moreover, communication can utilize any suitable wireless communication techniques, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexing (FDD), time division duplexing (TDD), multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other techniques that are currently known or developed in the future.

[0057] In the communication system 100, the first device 110 and the second device 120 can communicate data and control information with each other. In the case where the first device 110 is a terminal device and the second device 120 is a network device, the link from the second device 120 to the first device 110 is called the downlink (DL), while the link from the first device 110 to the second device 120 is called the uplink (UL). In the DL, the second device 120 is a transmission (TX) device (or transmitter) and the first device 110 is a reception (RX) device (or receiver). In the UL, the first device 110 is a TX device (or transmitter) and the second device 120 is an RX device (or receiver).

[0058] In operation, the first device 110 can monitor control information from the second device 120 that schedules assignments (e.g., DL assignments) for transmissions from the second device 120 to the first device 110 or grants (e.g., UL grants) for transmissions from the first device 110 to the second device 120. By reducing the time of monitoring control information from the second device 120 and going into an inactive state, discontinuous reception (DRX) can be applied to support battery saving of the first device 110.

[0059] In some scenarios, the propagation delay between the transmitter and the receiver is relatively large, resulting in a longer round trip time (RTT), especially for NTN. Conventional DRX mechanisms can not be suitable for communications with a longer propagation delay.

[0060] It is well known that any system with a propagation delay larger than the number of available hybrid automatic repeat request (HARQ) processes can suffer from HARQ stalling. The high transmission delay in NTN, especially with GEO satellite network devices, will require the transmitter to maintain a large number of HARQ processes, which can not be practical due to the extreme buffer size requirement of the receiver soft buffer and the large signaling requirement for indicating the number of HARQ processes. Furthermore, retransmission also results in a longer delay time for the packet. However, in both TN networks and NTN networks, HARQ has a valuable gain of providing reliability at a lower cost (compared to automatic repeat request (ARQ)) due to the gain of soft combining and shorter delay (compared to ARQ).

[0061] Therefore, it can be advantageous to allow HARQ enabling and disabling, especially for NTNs. For example, for NTNs, the network device can disable the UL HARQ feedback for DL transmissions at the terminal device, e.g., to support long propagation delays. The enabling / disabling of HARQ feedback can be semi-statically signaled to the terminal device through radio resource control (RRC) signaling. The enabling / disabling of HARQ feedback for DL transmissions can be configured per terminal device and per HARQ process via RRC signaling, but dynamic enabling and disabling of HARQ for a HARQ process is also possible. Furthermore, for NTNs, the network can disable HARQ UL retransmissions at the terminal device. The enabling / disabling of HARQ UL retransmissions can be configured per terminal device, per HARQ process, and per logical channel (LCH).

[0062] If HARQ feedback is disabled, some kind of open-loop / blind retransmission (e.g., retransmission without feedback, or retransmission independent of HARQ feedback) mechanism should be considered. With blind retransmission, the network device can schedule a retransmission at any time, independent of feedback. Since blind retransmission has the advantage of reduced latency, increased reliability, and dynamic scheduling of retransmission resources, blind retransmission is a very promising retransmission scheme, especially for scenarios with large propagation delays.

[0063] In summary, in at least NTNs, possible (re)transmission schemes can include: 1) single transmission only in case of disabled HARQ (i.e., HARQ is disabled for one-shot data transmission and no retransmission), 2) blind retransmission with aggregation factor larger than 1 in case of disabled HARQ (i.e., consecutive multiple transmissions of one transport block set (TBS) without feedback or decoding result based), 3) blind retransmission scheduled with downlink control information in case of disabled HARQ (i.e., multiple transmissions of one TBS on sparse TTIs without feedback or decoding result based, with scheduling flexibility and gain advantages), and 4) retransmission with enabled HARQ, retransmission based on feedback or decoding result, including blind retransmission on top of traditional HARQ.

[0064] Given the existence of multiple types of retransmission schemes, it is not desirable to design a DRX solution by only considering HARQ enabled transmissions. Rather, in designing a DRX solution, disabled HARQ transmissions, such as blind retransmission, should also be considered. One possible DRX solution to support blind retransmission schemes can be to extend the active time of the terminal device by expanding the values set for one or more timers used in DRX. It is desirable to improve the DRX solution taking into account the specific characteristics of blind retransmission in order to balance power consumption (i.e., the effective time of monitoring control information) and flexibility of scheduling and transmission.

[0065] According to various example embodiments of the present disclosure, some improved DRX solutions are provided to accommodate specific features of a given retransmission scheme. Specifically, in some example embodiments of the present disclosure, if a retransmission scheme is applied to the transmission of data between a first device and a second device, a timer for monitoring control information from the second device or for controlling the active / inactive state of the first device is specifically configured by the second device for the first device for the retransmission scheme. In one solution, the timing for entering an active state for monitoring control information from the second device for scheduling data retransmission is dynamically provided by the second device for the first device to provide retransmission timing. In another solution, the value of a timer for DRX used in the retransmission scheme is set based on the configuration of the timer specifically or based on a combination of the configuration of the timer for the retransmission scheme and additional configuration of a different retransmission scheme. These solutions provide scheduling and transmission flexibility for the retransmission scheme. Based on the configuration of the value of the timing or timer configured for the active state, the first device can receive control information from the second device in an optimized power saving and timely manner.

[0066] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0067] DRX based on dynamic retransmission timing

[0068] Reference will now be made to Figure 2 , Figure 2 A signaling flow 200 for data retransmission according to some example embodiments of the present disclosure is shown. For discussion purposes, the signaling flow 200 will be described with reference to Figure 1 . The signaling flow 200 can involve a first device 110 and a second device 120 as shown in Figure 1 . In some example embodiments, the signaling flow 200 can be particularly beneficial in scenarios where the RTT between the first device 110 and the second device 120 can be relatively large. For example, the signaling flow 200 can involve a first device 110-1 and a second device 120-1 in an NTN network as shown in Figure 1 . It should be understood that the signaling flow 200 can also be implemented in any other communication network.

[0069] In the signaling flow 200, the second device 120 sends 205 control information to the first device 110. The control information indicates a retransmission scheme (referred to as “first retransmission scheme” for ease of discussion) to be applied to the transmission of data between the first device 110 and the second device 120. The first retransmission scheme requires the retransmission of data to be performed independently of feedback for a previous transmission of the data. That is, the first retransmission scheme is a blind retransmission scheme. The transmission / retransmission between the first device 110 and the second device 120 can be associated with a HARQ process.

[0070] According to the first retransmission scheme, the transmitter transmits data to the receiver and retransmits the data without waiting for feedback for the previous transmission, which means that the transmitter always performs multiple transmissions of the same data as scheduled regardless of whether the previous transmission is successfully received and detected by the receiver. For example, a medium access control (MAC) entity schedules the same data on the same HARQ process without a new data indicator (NDI) being toggled. Such blind retransmission can help reduce the residual block error rate (BLER), especially in the case that the feedback for HARQ is disabled.

[0071] In some example embodiments, the first retransmission scheme can also require dynamic scheduling. That is, the second device 120, such as a network device, can dynamically schedule the retransmission. If the first retransmission scheme is supported, the second device 120 can schedule the retransmission at any time without waiting for feedback for the previous transmission. In some example embodiments, the scheduling of the retransmission and the retransmission scheme are indicated via different signaling messages. In some other example embodiments, the scheduling of the transmission / retransmission can also be indicated in the control information. For example, for the retransmission from the second device 120 to the first device 110, the control information can indicate an assignment (e.g., a DL assignment) for the retransmission, so that the first device 110 can know when and where to detect the retransmission after receiving the assignment. For the retransmission from the first device 110 to the second device 120, the control information can indicate a grant (e.g., an UL grant) for the retransmission, so that the first device 110 can know when and where to perform the retransmission to the second device after receiving the grant.

[0072] In some example embodiments, the first device 110 receives 210 the control information and thus can not only know the assignment or grant for the transmission of the data, but also know the first retransmission scheme to be applied for the retransmission of the data.

[0073] For the retransmission from the second device 120 to the first device 110 (e.g., DL retransmission) or from the first device 110 to the second device 120 (e.g., UL retransmission), the second device 120 can send control information indicating whether the first retransmission scheme is applied for the subsequent retransmission. In some example embodiments, the control information can be sent via a physical layer downlink control channel (e.g., PDCCH). In this example, the control information can also be referred to as DL control information (i.e., DCI). In some example embodiments, the control information can include an indication for enabling / disabling HARQ feedback to indicate the first retransmission scheme. For example, if the indication indicates that the HARQ feedback is disabled, the first device 110 can determine that the first retransmission scheme is to be applied for the retransmission. Alternatively or additionally, the control information can include an indication for the retransmission scheme, which can be used to explicitly indicate the first retransmission scheme to be applied.

[0074] In case the first retransmission scheme is to be applied for transmissions between the first device 110 and the second device 120, the second device 120 further transmits 215 timing information specific to the first retransmission scheme to the first device 110. The timing information indicates a retransmission timing of the first retransmission scheme. The retransmission timing indicates when a retransmission of data can be expected or a time interval during which no retransmission can be expected. In some example embodiments, the timing information can be transmitted by the second device 120 via a physical layer downlink control channel (e.g., PDCCH). The timing information can also be included in the DCI together with the control information indicating the first retransmission scheme. Alternatively, in some example embodiments, the control information indicating the first retransmission scheme can be transmitted via high layer signaling, while the timing information can be carried in physical layer signaling, such as via a physical layer downlink control channel (e.g., PDCCH). In some example embodiments, the timing information in the DCI can be indicated via different fields, depending on whether the transmission is for DL or UL, which will be described in detail below.

[0075] The first device 110 receives 220 the timing information and determines 225 a timing for monitoring further control information from the second device 120 for scheduling a retransmission based on the indicated retransmission timing.

[0076] The first device 110 can operate in a DRX mode and can transition between an inactive state and an active state for power saving purposes. In the inactive state, the first device 110 does not need to monitor control information from the second device 120. In the active state, the first device 110 will be in the active state for control information monitoring and can thus receive a DL assignment or UL grant for a data (re)transmission. According to example embodiments of the present disclosure, since the second device 120 is in charge of the scheduling of the (re)transmission scheduling, it can more flexibly dynamically inform the appropriate retransmission timing of the first retransmission scheme. Based on the retransmission timing information, the first device 110 can know when to expect further control information from the second device 120 for scheduling a data retransmission. The first device 110 can thus enter the active state at the right time to detect and receive the further control information. In some example embodiments, if there is no other running DRX timer(s) (such as a running inactivity timer) indicating the first device 110 to enter the active state, the first device 110 can stay in the inactive state to save power consumption.

[0077] In some example embodiments, the retransmission timing can comprise a time interval, in which the first device 110 can be in an inactive state. By an explicit indication of the time interval from the second device 120, the first device 110 can determine to start a retransmission timer after the time interval has ended. In DRX, the retransmission timer can be used by the first device 110 to actively start monitoring for control information from the second device 120. The retransmission timer can indicate a maximum duration until a DL retransmission (from the second device 120 to the first device 110) or an UL grant for an UL retransmission (from the first device 110 to the second device 120) is received. In 3GPP-based communication systems, the retransmission timer can also be referred to as drx-RetransmissionTimer, drx-RetransmissionTimerDL or drx-RetransmissionTimerUL. By the indication of the time interval, the start of the retransmission timer can be triggered dynamically. After the retransmission timer has started, the first device 110 can remain in an active state to monitor for further control information from the second device 120 until the retransmission timer has expired or until further control information is detected. For example, the value of the retransmission timer can be set via RRC configuration signaling.

[0078] It should be appreciated that, in addition to the time interval, the timing indication retransmission for entering the active state can be determined for the first device 110 in other ways.

[0079] In some example embodiments, for entering the active state based on the indicated retransmission timing, e.g., by starting the retransmission timer, the first device 110 can set the value of an RTT timer to zero. The RTT timer is a DRX timer that indicates a minimum duration before a DL assignment for a HARQ-based retransmission (in a DL retransmission from the second device 120 to the first device 110) or an UL grant for a HARQ-based retransmission (in an UL retransmission from the first device 110 to the second device 120) is expected. In 3GPP-based communication systems, the RTT timer can also be referred to as drx-HARQ-RTT-TimerDL (in DL (re)transmission) or drx-HARQ-RTT-TimerUL (in UL (re)transmission). In some example embodiments, instead of setting the RTT timer to 0, the RTT timer and the corresponding functionality can be disabled if a first retransmission scheme is configured.

[0080] In some example embodiments, a set of candidate values for retransmission timing for the first retransmission scheme can be configured to the first device 110 from the second device 120 via high layer signaling, such as RRC signaling. The set of candidate values can be indexed with different indices. For example, if there are eight possible candidate values for retransmission timing, such as 10 ms, 15 ms, 20 ms, 25 ms, 30 ms, etc. retransmission intervals, the second device 120 can use a 3-bit indication to indicate all these candidate values, such as 000 for 10 ms, 001 for 15 ms, 010 for 20 ms, and so on. The second device 120 can configure the candidate values and the mapping between the candidate values and the 3-bit indication to the first device 110, e.g., via RRC signaling. To indicate the retransmission timing to be applied, the second device 120 can select one of the candidate values to indicate the retransmission timing in the timing information, and send the timing information to the first device 110, e.g., via physical layer signaling such as PDCCH (e.g., the value 010 indicating 20 ms).

[0081] To configure a set of candidate values to the first device 110 via high layer signaling, in some example embodiments, a conventional information element (IE) of RRC signaling that will not be used in case the first retransmission scheme is applied can be reused to carry the set of candidate values. That is, if a different second retransmission scheme (e.g., a retransmission scheme based on HARQ feedback) is applied, the IE of RRC can have a different meaning. For example, an IE of RRC signaling carrying a list of timing for transmission feedback in case a different retransmission scheme (e.g., a retransmission scheme based on HARQ feedback) is configured can be reused in case the first retransmission scheme is applied to indicate the set of candidate values for retransmission timing. One example of such an IE can be the IE “dl-DataToUL-ACK” in a 3GPP based communication system. As an alternative, a new IE can be defined in RRC signaling to convey the set of candidate values to the first device 110.

[0082] By dynamically indicating the retransmission timing to the first device 110, the second device 120 can control the timer when the first device 110 can start monitoring for further control information in the first retransmission scheme or can start the retransmission timer. The retransmission timing (e.g., a time interval during which no retransmission can be expected and the first device 110 can be in an inactive state) can be determined based on various factors. In some example embodiments, the second device 120 can determine the retransmission timing based on channel conditions between the first device 110 and the second device 120, service requirements on data to be transmitted, load conditions within a service coverage of the second device 120, etc.

[0083] For example, if the data to be transmitted (e.g., data included in a MAC protocol data unit (PDU)) has a high latency requirement, the second device 120 can schedule a subsequent blind retransmission immediately after the previous transmission of the data. Thus, the retransmission timing can include a short retransmission interval, and the first device 110 can enter the active state in time to receive control information for scheduling the subsequent retransmission. If the data has a lower latency requirement and the second device 120 has a high load, the second device 120 will schedule a blind retransmission a long time after the previous transmission. As another example, the second device 120 can obtain the channel-dependent time in the current channel conditions and can determine the likely duration of the subsequent retransmission. The second device 120 can thus inform the first device 110 of the timing for starting the retransmission timer.

[0084] DRX solutions based on dynamic retransmission timing have been discussed above. To better understand such solutions, some examples of DRX operation supporting (re)transmissions from the second device 120 to the first device 110 (e.g., DL (re)transmissions) and (re)transmissions from the first device 110 to the second device 120 (e.g., UL (re)transmissions) will be described with reference to Figure 3 and Figure 4

[0085] DL (re)transmissions in DRX based on dynamic retransmission timing

[0086] Figure 3 A signaling flow 300 in DL (re)transmissions between the first device 110 and the second device 120 is illustrated in accordance with some example embodiments of the present disclosure. In the example of FIG. 3, the first device 110 operates in DRX mode and the dynamic retransmission timing is controlled by the second device 120. Figure 3

[0087] In the signaling flow 300, the second device 120 sends 305 a DCI to the first device 110, e.g., via a physical layer DL control channel. In addition to indicating a DL assignment for a transmission of current data, the DCI can also indicate that a first retransmission scheme is to be applied. In some example embodiments, the control information indicating that the first retransmission scheme is to be applied is sent by the second device 120 to the first device 110 in a separate signaling. The first device 110 monitors and receives 310 the DCI from the second device 120. Since the first retransmission scheme is indicated in the DCI or another received message, the first device 110 can determine that the second device 120 will later schedule a blind retransmission of the data regardless of the feedback for the previous transmission. If the first retransmission scheme is to be applied, the DCI can also include timing information indicating the retransmission timing, such as a retransmission interval (denoted as “K1”).

[0088] ​​In some example embodiments, a newly defined field in the DCI can be used to indicate the retransmission timing. In some other example embodiments, in a DL (re)transmission, if a first retransmission scheme is to be applied, one or more fields of a physical layer DL control channel (e.g., DCI) used in other retransmission schemes (referred to as second retransmission schemes) that require feedback can not need to carry the corresponding parameters for the second retransmission schemes, as these parameters are needed in case of feedback disabling. Such fields in the physical layer DL control channel can be reused to indicate the timing information for the first retransmission scheme.

[0089] The second retransmission scheme is different from the first retransmission scheme. An example of the second retransmission scheme is a HARQ enabled retransmission scheme that requires feedback, such as a conventional HARQ enabled retransmission scheme. If the second retransmission scheme that requires feedback is configured, an example of the field to be reused to indicate the retransmission timing for the first retransmission scheme can be a field used to indicate a feedback timing indicator. Thus, this reused field in the DCI can indicate the feedback timing indicator in case the second retransmission scheme is configured, and can indicate the timing information in case the first retransmission scheme is configured.

[0090] In a 3GPP based communication system, the field indicating the feedback timing indicator can be the field “PDSCH-to-HARQ_feedback timing indicator”, where PDSCH refers to physical downlink shared channel. The meaning of the “PDSCH-to-HARQ_feedback timing indicator” field can be redefined when the first retransmission scheme is configured. The mapping between the candidate values of the retransmission timing and the index to be indicated in the field “PDSCH-to-HARQ_feedback timing indicator” can be configured by RRC signaling, e.g., in the information element (IE) “dl-DataToUL-ACK”. By reusing the existing field(s), the signaling efficiency can be improved, and the impact on the communication standard due to the introduction of the retransmission timing will be minimized.

[0091] When the first device 110 receives the control information and the timing information indicating the first retransmission scheme, the first device 110 can extract the retransmission timing indicated by the timing information, such as "K1". In some example embodiments, if the DCI also indicates that a new transmission of new data is scheduled for the first retransmission scheme, the first device 110 can start or restart an inactivity timer, such as the drx_inactivityTimer in 3GPP-based communication systems. The inactivity timer indicates a duration of time after the reception of the control information from the second device 120 that is used to schedule a new transmission between the first device 110 and the second device 120. In other words, the inactivity timer can indicate a duration of time after a PDCCH occasion during which the PDCCH indicates a new UL or DL transmission for the MAC entity.

[0092] In general, the received DCI can indicate a DL assignment of a current transmission. According to the DL assignment, the second device transmits 315 DL data and the first device receives 320 the DL data.

[0093] Based on the retransmission timing indicated in the received timing information, the first device 110 determines a timing for monitoring further control information from the second device 120 for scheduling a retransmission of data. During a time interval before the determined timing, the first device 110 can be in an inactive state and not monitor for DCI from the second device 120 for power saving. After the reception of the DL data at 320, for example, after the end of the last symbol of the DL data reception, the first device 110 can be in an inactive state for a time interval indicated by "K1". The time interval "K1" can be started at the end of the DL data reception. As Figure 3 As shown, after the indicated timer interval "K1" from the reception of the DL data, the first device 110 starts 325 a retransmission timer for DL retransmission, such as the drx- RetransmissionTimerDL. For example, the retransmission timer can be started in the first symbol after the timing interval K1 indicated in the DCI.

[0094] In some example embodiments, before starting the retransmission timer, the first device 110 can set the value of the RTT timer for the DL (re)transmission, such as the drx-HARQ-RTT- TimerDL, to zero and then start the RTT timer (no time elapses since the value is zero). The first device 110 can alternatively disable the RTT timer before the retransmission timer is to be started.

[0095] After the retransmission timer is started, the first device 110 will enter the active state and can monitor and receive from the second device 120 additional control information for scheduling the retransmission. The first device 110 will remain in the active state until the retransmission timer expires or until additional control information is detected. In Figure 3 In the example shown, the second device 120 decides to schedule a retransmission of DL data for the first device 110 and sends 330 to the first device 110 additional DCI indicating the scheduling of the retransmission of the DL data. For example, the DCI can indicate a DL assignment of the current retransmission to be scheduled. The retransmission timer at the first device 110 has not expired and, thus, the first device 110 successfully monitors and receives 335 the additional DCI.

[0096] In some example embodiments, the additional DCI can also indicate that the first retransmission scheme is to be applied and further include timing information indicating the retransmission timing, such as a retransmission gap denoted as "K2". The retransmission gap "K2" can be the same or different from the retransmission gap "K1". The second device 120 can determine the retransmission gap "K2" according to various factors as described above when sending the additional DCI.

[0097] According to the DL assignment indicated in the additional DCI, the second device 120 sends 340 the retransmission of the DL data and the first device 110 receives 345 the retransmission of the DL data. After receiving the retransmission of the DL data, the first device 110 can stop the previously started retransmission timer, if the retransmission timer is still running. The first device 110 can then enter the inactive state for the time interval "K2". After the time interval "K2" has elapsed from the reception of the retransmission of the DL data, the first device 110 restarts the retransmission timer.

[0098] UL (re)transmission in DRX based on dynamic retransmission timing

[0099] Figure 4 A signaling flow 400 in UL (re)transmission between a first device 110 and a second device 120 according to some example embodiments of the present disclosure is shown. In Figure 4 In the example shown, the first device 110 operates in DRX mode and the dynamic retransmission timing is controlled by the second device 120.

[0100] In the signaling flow 400, the second device 120 sends 405 to the first device 110 a DCI, e.g., via a physical layer DL control channel. The DCI and its transmission can be similar to those discussed above with reference to Figure 2 and Figure 3 In the example shown, the first device 110 operates in DRX mode and the dynamic retransmission timing is controlled by the second device 120. Figure 3 Figure 4 ​The DCI in the UL (re)transmission differs in that the DCI includes an UL grant for the first device 110 to transmit its UL data (which can be a new transmission or a retransmission). The retransmission timing indicated in the DCI, such as the retransmission interval, is denoted as "T1".

[0101] The DCI for the UL (re)transmission can not have a field as in the DCI for the DL (re)transmission that can be reused to indicate the retransmission timing (such as the "PDSCH-to-HARQ_feedback timing indicator" indicating the feedback timing indicator). Therefore, the timing information can be included in a newly defined field in the DCI. Furthermore, the RRC signaling for the UL (re)transmission can not have an IE indicating a list of timing for feedback transmission (such as the IE "dl-DataToUL-ACK") that can be reused to configure a set of candidate values to the first device 110, and therefore, a new IE in the RRC signaling can be used to indicate the candidate values for the retransmission timing.

[0102] The first device 110 receives 410 the DCI. The operation of the first device 110 after receiving the DCI can be similar to those discussed above with reference to Figure 2 and Figure 3 The first device 110 transmits 415 the UL data and the second device 120 receives 420 the UL data according to the UL grant indicated in the DCI.

[0103] Similar to in the DL (re)transmission, the first device 110 can be in an inactive state duration interval "T1" after the transmission of the UL data (e.g., after the end of the last symbol of the transmission). As Figure 4 indicated, after the indicated time interval "T1" from the end of the UL data transmission by the first device 110, the first device 110 starts 425 a retransmission timer for the UL retransmission, such as the drx-RetransmissionTimerUL. For example, the retransmission timer can be started in the first symbol after the timing interval T1 indicated in the DCI. The second device 120 transmits 430 additional DCI and the first device 110 receives 435 the additional DCI.

[0104] If the additional DCI still indicates the first retransmission scheme to be applied (or, the additional DCI does not indicate a change to the retransmission scheme) and the timing information for the first retransmission scheme, the first device 110 and the second device 120 can perform similar operations as at 415, 420, and 425. Specifically, the first device 110 transmits 440 a retransmission of the UL data and the second device 120 receives 445 the retransmission of the UL data according to the UL of the grant indicated in the additional DCI. After the retransmission of the UL data, the first device 110 restarts 450 the retransmission timer after the timer interval “T2” indicated in the additional DCI. Other operations at the first device 110 and the second device 120 can be similar to those discussed with reference to Figure 2 and Figure 3 .

[0105] Example of DCI loss in DRX based on dynamic retransmission timing

[0106] Figure 5 FIGURE 5 illustrates a signaling flow 500 in a DL (re)transmission between a first device 110 and a second device 120, in accordance with some example embodiments of the present disclosure. Figure 5 Examples are used to show how DRX is performed in a DRX solution based on dynamic retransmission timing in case of DCI loss.

[0107] In the signaling flow 500, the operations of the first device 110 and the second device 120 at 505, 510, 515, 520, and 525 are similar to the operations of the first device 110 and the second device 120 at 305, 310, 315, 320, and 325 in the signaling flow 300. In the example of FIGURE 5, the second device 120 transmits 530 an additional DCI indicating the first retransmission scheme and an additional retransmission timing (denoted by “K2”), but the first device 110 fails to receive the additional DCI transmitted at 530 to trigger the restart of the new retransmission timer. If the retransmission timer started at 525 is still running, the first device 110 is still in the active state and thus can receive a further DCI (e.g., the DCI transmitted by the second device 120 at 540) later and can restart the retransmission timer again, as shown in the example of FIGURE 5. Figure 5 Figure 3

[0108] However, if the retransmission timer started at 525 has already expired, the first device 110 is in the DRX state and thus can not receive the further DCI (e.g., the DCI transmitted by the second device 120 at 540) and can not restart the retransmission timer, as shown in the example of FIGURE 6. Figure 5 ​​As shown, the DCI arrives at the first device 110 after the retransmission timer (started at 525) expires, then the first device 110 will not receive the retransmission of the DL data sent 535 by the second device 120 and will not acquire the indication of the start of the retransmission triggering. Thus, even if the second device 120 continues to schedule further retransmissions and sends 540 a third DCI indicating the first retransmission scheme and a third retransmission timing (denoted by “K3”), the first device 110 will miss the detection of the third DCI and the retransmission of the DL data sent 545 by the second device 120 scheduled in the third DCI. However, even this unexpected situation will not impact the performance of blind retransmission with soft combining, because the first device 110 cannot perform soft combining on the subsequent DL data of the blind retransmission, because the first device 110 did not receive the transmission of the DL data of the blind retransmission at 535 when the further DCI sent at 530 was missed. For this situation, the retransmission for reliability can rely on the ordinary HARQ.

[0109] DRX based on transmission scheme specific timer configuration

[0110] According to some other example embodiments of the present disclosure, to improve the DRX solution in the first retransmission scheme, the second device 120 can configure different timers (or timer values) specifically for different retransmission schemes, and then the first device 110 can select the appropriate timer (or timer value) based on the configured retransmission scheme. Figure 6 A signaling flow 600 for data retransmission according to these example embodiments is shown. For the purpose of discussion, the signaling flow 600 will be described with reference to the first device 110 and the second device 120 as shown in Figure 1 The signaling flow 600 can involve the first device 110 and the second device 120 as shown in Figure 1 In some example embodiments, the signaling flow 600 can be particularly beneficial in scenarios where the RTT between the first device 110 and the second device 120 can be relatively large. For example, the signaling flow 600 can involve the first device 110-1 and the second device 120-1 in an NTN network as shown in Figure 1 It should be appreciated that the signaling flow 600 can also be implemented in any other communication network.

[0111] In the signaling procedure 600, the second device 120 transmits 605 a first configuration of a first timer for a first retransmission scheme and the first device 110 receives 610 the first configuration of the first timer for the first retransmission scheme. The second device 120 also transmits 615 a second configuration of a second timer for a second retransmission scheme and the first device 110 receives 620 the second configuration of the second timer for the second retransmission scheme. As previously discussed, the second retransmission scheme is different from the second retransmission scheme. For example, the second retransmission scheme can be a HARQ enabled retransmission scheme that requires feedback, such as a conventional HARQ enabled retransmission scheme, while the first retransmission scheme can be a HARQ disabled retransmission scheme.

[0112] According to some example embodiments of the present disclosure, instead of using the same configuration for all retransmission schemes, different configurations can be specifically configured for some timers used in DRX. That is, the first configuration of the first timer can be different from the second configuration of the second timer. In some example embodiments, the first configuration and the second configuration can be transmitted to the first device 110 via higher layer signaling, such as RRC signaling, for example in a DRX_Config IE for configuring DRX related parameters. In some example embodiments, a new parameter can be introduced in the DRX_Config IE to indicate the first configuration (a parameter indicating the second retransmission scheme can already be included in the DRX_Config IE).

[0113] The first device 110 can be scheduled by the second device 120 with different (re)transmission schemes as described above. The first device 110 can use control information to indicate which retransmission scheme is used. Specifically, the second device 120 transmits 625 control information and the first device 110 receives 630 the control information, the control information indicating that the first retransmission scheme is to be applied to the transmission of data between the first device 110 and the second device 120. The control information indicating the first transmission scheme can be transmitted in a similar manner as discussed above with reference to the signaling procedure 500. Figure 2

[0114] The first configuration or both the first configuration and the second configuration can be used to determine a first value of the first timer used in the first retransmission scheme. In some example embodiments, based on a determination that the first retransmission scheme is to be applied to the transmission of data between the first device and the second device, the first device 110 sets 635 the first value for the first timer based on the first configuration or based on both the first configuration and the second configuration.

[0115] ​The second configuration can indicate a second value of a second timer. The first configuration is used to determine a first value for the first timer. In some example embodiments, the first configuration can directly indicate the first value for the first timer. In this case, the first device 110 can directly set the first value for the first timer based on the first configuration. In some example embodiments, the first configuration can indicate a scaling factor for the first timer. The first device 110 can determine the first value for the first timer based on the scaling factor and the second value. For example, the first value can be determined based on a product of the scaling factor and the second value or based on a sum of the scaling factor and the second value. The first value can be determined in any other way based on the scaling factor and the second value.

[0116] According to the reference Figure 6 In accordance with the example embodiments discussed, the second device 120 can specifically design the timer for the first retransmission scheme that does not require feedback for the transmission, e.g., by lengthening the timer or shortening another timer in order to balance power consumption and scheduling / transmission flexibility. In addition, by transmitting the first configuration and the second configuration via higher layer signaling instead of physical layer signaling such as DCI, the signaling overhead between the first device 110 and the second device 120 can be reduced.

[0117] In some example embodiments, the second device 120 can configure the inactivity timer for DRX via the first configuration and the second configuration for the first retransmission scheme and the second retransmission scheme, respectively. The value of the inactivity timer for the first retransmission scheme can be specifically determined by the first device based on the first configuration or based on both the first configuration and the second configuration. In some other example embodiments, the second device 120 can configure the RTT timer for DRX via the first configuration and the second configuration for the first retransmission scheme and the second retransmission scheme, respectively, and the value of the RTT timer for the first retransmission scheme can be specifically determined by the first device 110 based on the first configuration or based on both the first configuration and the second configuration.

[0118] DL and UL (re)transmissions based on specific inactivity timer configurations

[0119] Figure 7 and Figure 8 Figures 7 and 8 illustrate signaling flows 700 and 800 in DL (re)transmissions and UL (re)transmissions, respectively, in which the value of the inactivity timer for the first retransmission scheme is specifically configured.

[0120] In the signaling procedures 700 and 800, a first configuration of a first timer (i.e., a first inactivity timer) for the first retransmission scheme and a second configuration of a second timer (i.e., a second inactivity timer) for the second retransmission scheme have been sent by the second device 120 to the first device 110. In a 3GPP-based communication system, the first or second inactivity timer can also be referred to as drx_inactivityTimer.

[0121] The first value of the first timer indicates a time duration after receiving control information from the second device 120 for scheduling a new transmission between the first device 110 and the second device 120 for the first retransmission scheme. The second value of the second timer (referred to as “second value” for ease of discussion) indicates a time duration after receiving control information from the second device 120 for scheduling a new transmission between the first device 110 and the second device 120 for the second retransmission scheme. The second configuration can indicate the second value of the second timer. The first configuration is used to determine the first value for the first timer and can directly indicate the first value or indicate a scaling factor for determining the first timer, as described above.

[0122] If the first configuration of the first timer is sent in RRC signaling, a new parameter can be included in the DRX-Config IE to indicate the configuration. The DRX-Config IE introducing a new parameter to indicate the first value of the first timer can be as follows. In this example, the first configuration of the inactivity timer for blind retransmission and the second configuration of the inactivity timer for HARQ-based retransmission are shown as drx-InactivityTimer_blindretransmission and drx-InactivityTimer, respectively.

[0123] DRX-Config information element

[0124]

[0125]

[0126] Similarly, the first configuration can indicate a scaling factor, and a new parameter can also be added in the DRX-Config IE to indicate the scaling factor. It should be understood that the first configuration listed in the above-mentioned IE is for illustrative purposes only and does not represent any limitation on the scope of the present disclosure.

[0127] Reference is first made to Figure 7In operation of DRX, the second device 120 transmits 705 DCI and the first device 110 receives 710 the DCI, which indicates that the first retransmission scheme is to be applied. However, it should be appreciated that in some example embodiments, the first retransmission scheme can be configured via other signaling (e.g., RRC). In this example, the DCI indicates the first retransmission scheme to be applied. The DCI can also indicate a new transmission of DL data. Upon receiving the DCI, the first device 110 starts 715 a first timer (i.e., an inactivity timer) with a first value in response to determining that the first retransmission scheme is to be applied. The first timer started here is used to monitor for DL (re)transmissions. The first value of the first timer is determined based on the received first configuration or a combination of the first and second configurations.

[0128] In some example embodiments, the first value can be configured to be larger than the second value. In this way, the first timer is extended and the first device 110 can have an extended duration to remain in the active state. The first device 110 can remain in the active state until the first timer expires. In some example embodiments where the inactivity timer is specifically configured, such as drx-HARQ-RTT-TimerDL, an RTT timer will not be started because the first retransmission scheme does not require feedback for (re)transmissions. In some example embodiments, if no specific configuration is provided for starting a retransmission timer, a retransmission timer such as drx-RetransmissionTimerDL will not be triggered.

[0129] As scheduled in the DCI transmitted at 705, the second device 120 transmits 720 DL data and the first device 110 receives 725 the DL data. With the first device 110 remaining in the active state, the second device 120 decides to schedule a retransmission of the DL data and transmits 730 additional DCI to the first device 110. Since the first timer is still running and the first device 110 is still in the active state, the first device 110 receives 735 the DCI. As scheduled in the additional DCI transmitted at 730, the second device 120 transmits 740 a retransmission of the DL data and the first device 110 receives 745 the retransmission of the DL data. Thus, the extended value of the first timer allows the first device 110 to receive the subsequent DCI and DL data.

[0130] In some example embodiments, the first device 110 can remain in the active state to monitor for further control information until the first timer expires or until further control information from the second device 120 is detected that schedules a new transmission. In case further control information scheduling a new transmission (a first transmission of new data) is detected from the second device 120, the first device 110 can restart the further timer (i.e. the further inactivity timer). If the further control information also indicates the first retransmission scheme to be applied for retransmissions of the new data, the value of the further timer can be set similar as discussed above.

[0131] Figure 8 Fig. 7 illustrates a signaling flow 700 in UL (re)transmissions between the first device 110 and the second device 120, wherein the value of the inactivity timer for the first retransmission scheme is configured by the second device 120. In the example of Fig. 7, the first device 110 operates in DRX mode. In the signaling flow 700, the operations 705, 710, 715, 720, 725, 730, 735, 740, 745 are similar to the operations 605, 610, 615, 620, 625, 630, 635, 640, 645 in the signaling flow 600. The difference is that at 720, 725 and 740, 745, the first device 110 starts the first timer for UL (re)transmissions, and the first device 110 transmits UL data for the second device 120 to receive. Figure 8

[0132] DL and UL (re)transmissions based on a specific RTT timer configuration

[0133] Figure 9 and Figure 10 Figs. 9 and 10 illustrate signaling flows 900 and 1000 in DL (re)transmissions and UL (re)transmissions, respectively, wherein the value of the RTT timer for the first retransmission scheme is configured specifically.

[0134] In the signaling flows 900 and 1000, a first configuration of a first timer (i.e. a first RTT timer) for the first retransmission scheme and a second configuration of a second timer (i.e. a second RTT timer) for the second retransmission scheme have been sent by the second device 120 to the first device 110. In a 3GPP-based communication system, the first RTT timer or the second RTT timer can also be referred to as drx-HARQ-RTT-Timer, more specifically as drx-HARQ-RTT-TimerDL for DL (re)transmissions or as drx-HARQ-RTT-TimerUL for UL (re)transmissions.

[0135] ​In DL (re)transmissions, the first value of the first timer indicates a minimum time duration before a DL assignment for retransmission is expected for the first retransmission scheme; similarly, the second value of the second timer indicates a minimum time duration before a DL assignment for retransmission is expected for the second retransmission scheme. In UL (re)transmissions, the first value of the first timer indicates a minimum time duration before an UL grant for retransmission is expected for the first retransmission scheme; similarly, the second value of the second timer indicates a minimum time duration before an UL grant for retransmission is expected for the second retransmission scheme.

[0136] The first configuration of the RTT timer can be signaled in RRC signaling and a new parameter can be included in the DRX-Config IE to indicate the configuration. In a similar manner as the configuration for the inactivity timer, the DRX-Config IE introduces a new parameter to indicate the first value or scaling factor of the first timer, as described above.

[0137] In example embodiments where the RTT timer for the first retransmission scheme is specifically configured, other DRX timers such as the inactivity timer and the retransmission timer can also be enabled during DRX. The RTT timer is optimized compared to the second transmission scheme.

[0138] In the signaling flow 900, the second device 120 transmits 905 control signaling (e.g., DCI) and the first device 110 receives 910 the control signaling, which indicates that the first retransmission scheme is to be applied. The DCI indicates the first retransmission scheme to be applied. In some example embodiments, the DCI can also indicate a new transmission of new data scheduled for the first retransmission scheme, and the first device 110 can start or restart an inactivity timer such as the drx_inactivityTimer in 3GPP-based communication systems. According to the DL assignment indicated in the DCI, the second device 120 transmits 915 DL data and the first device 110 receives 920 the DL data.

[0139] Upon receiving DL data, the first device 110 starts a first timer 925 (i.e., an RTT timer for DL ​​(re)transmission). In some example embodiments, the first value can be configured to be less than a second value. For example, the first device 110 is not forced to be active during the RTT timer period. Whether the first device 110 is active during the RTT timer's operation can also depend on whether other timers still require the first device 110 to remain active. By configuring the RTT timer to a smaller value, the first device 110 can have a higher probability of successfully monitoring and receiving additional DCI from the second device 120. The first timer started here is used to monitor DL ​​(re)transmission. The first value of the first timer is determined based on the received first configuration or a combination of the first and second configurations.

[0140] Upon receiving DL data, if applicable, the first device 110 may further stop the retransmission timer (such as drx-RetransmissionTimerDL). Depending on the first value, the first timer (i.e., the RTT timer) expires at 930. In some example embodiments, after the RTT timer expires, the first device 110 may restart the retransmission timer (such as drx-RetransmissionTimerDL). The first device 110 may then be active and receive an additional DCI at 940 sent from the second device 120 at 935. The additional DCI also indicates the first retransmission scheme. Therefore, after the first device receives a retransmission of DL data at 950 sent from the second device 120 at 945, the second device 120 restarts the RTT timer at 955.

[0141] Figure 10 The diagram illustrates a signaling flow 1000 in a UL (re)transmission between a first device 110 and a second device 120, wherein the value of the RTT timer for the first retransmission scheme is specifically configured. Figure 10 In the example, the first device 110 operates in DRX mode. In signaling flow 1000, operations 1005, 1010, 1015, 1020, 1025, 1030, 1035, 1040, and 1045 are similar to operations 905, 910, 915, 920, 925, 930, 935, 940, and 945 in signaling flow 900. The difference is that in 1015, 1020, 1025 and 1045, 1050 and 1055, the first device 110 sends UL data for the second device 120 to receive, and the first device 110 starts a first timer (such as drx-HARQ-RTT-TimerUL) for UL (re)transmission.

[0142] Example methods implemented at the corresponding devices

[0143] Figure 11 A flowchart illustrating an example method 1100 implemented at a first device according to some example embodiments of the present disclosure is shown. For the purpose of discussion, reference will be made to Figure 1 The method 1100 is described from the perspective of the first device 110.

[0144] At block 1110, the first device 110 receives control information from the second device 120, the control information indicating a first retransmission scheme to be applied to transmissions of data between the first device 110 and the second device 120, the first retransmission scheme requiring retransmission of data to be performed independently of feedback to previous transmissions of data. At block 1120, the first device 110 receives timing information specific to the first retransmission scheme from the second device 120, the timing information indicating a retransmission timing. At block 1130, the first device 110 determines a timing for monitoring for further control information from the second device 120 to schedule a retransmission based on the retransmission timing.

[0145] The method 1100 proposes a DRX configuration for blind retransmission with dynamic timing for entering the active state. With this solution, the second device 120 can flexibly schedule retransmissions and the first device 110 can not only receive the control information in time but also optimize energy saving by being indicated the possible retransmission timing from the second device 120.

[0146] In some example embodiments, the timing information received at block 1120 can indicate a time interval during which the first device can be in the inactive state and at block 1130, the first device 110 can determine to start a retransmission timer at the end of the time interval and enter the active state. The retransmission timer indicates a maximum duration until a DL retransmission or an UL grant for an UL retransmission is received. After the first retransmission timer is started, the first device 110 can remain in the active state for monitoring for further control information until the retransmission timer expires or until further control information is detected.

[0147] In some example embodiments, the first device 110 can set a value of an RTT timer to zero according to the reception of the control information indicating the first retransmission scheme to be applied. As an alternative, the first device 110 can disable the RTT timer according to the reception of the control information indicating the first retransmission scheme to be applied. The RTT timer indicates a minimum duration until a DL assignment or an UL grant expected for a HARQ-based retransmission.

[0148] In some example embodiments, the timing information can be received via a physical layer DL control channel. For example, to receive the timing information, the first device 110 can detect a field of the physical layer DL control channel. If the second retransmission scheme is configured, the field can be a field indicating a feedback timing indicator, and if the first retransmission scheme is configured, the field indicates the timing information. In this way, when the first retransmission scheme is configured, an existing field in the control information can be reused, as the feedback timing indicator is not needed in the first retransmission scheme. As an alternative, a dedicated new field can be defined in the control information to indicate only the timing information for the first retransmission scheme.

[0149] In some embodiments, if the second retransmission scheme is configured, a set of candidate values indicating a list of timings for transmission of feedback can be sent to the first device, which can simplify the required configuration parameters. In some example embodiments, the first device 110 can receive a set of candidate values for retransmission timing for the first retransmission scheme from the second device 120 via higher layer signaling. In some embodiments, the set of candidate values for retransmission timing for the first retransmission scheme can be carried to the first device by reusing the signaling used to indicate the list of timings for transmission of feedback for the second retransmission scheme. The timing information received at block 1120 can indicate one of the candidate values, e.g., via a physical layer downlink control channel.

[0150] Figure 12 A flowchart illustrating an example method 1200 implemented at a first device in accordance with some example embodiments of the present disclosure is shown. For discussion purposes, reference will be made to the first device 110 and the second device 120 of FIG. 1. Figure 1 The method 1200 is described from the perspective of the first device 110.

[0151] At block 1210, the first device 110 receives a first configuration of a first timer for a first retransmission scheme from the second device 120. At block 1220, the first device 110 receives a second configuration of a second timer for a second retransmission scheme different from the first retransmission scheme from the second device 120. At block 1230, the first device 110 sets a first value for the first timer based on the first configuration or both the first configuration and the second configuration in accordance with a determination that the first retransmission scheme is to be applied to transmission of data between the first device 110 and the second device 120. The first retransmission scheme can require retransmission of data to be performed independent of feedback for a previous transmission of the data.

[0152] The method also gives a solution of DRX with support of blind retransmission based on retransmission scheme specific timer configuration. With this solution, the first device 110 can select an appropriate timer specific to the retransmission scheme (which can be an extended timer such as an inactivity timer or a shortened timer such as an RTT timer) based only on the configuration of the retransmission scheme (e.g., a blind retransmission scheme) in order to achieve power saving.

[0153] In some example embodiments, the first value of the first timer can indicate a duration after receiving control information from the second device 120 for scheduling a new transmission between the first device 110 and the second device 120 for the first retransmission scheme; i.e., the first timer is an inactivity timer for the first retransmission scheme. The second timer can indicate a duration after receiving control information from the second device 120 for scheduling a new transmission between the first device 110 and the second device 120 for the second retransmission scheme; i.e., the second timer is an inactivity timer for the second retransmission scheme. In these example embodiments, the first device 110 can start the first timer upon receiving the control information and then remain in an active state until the first timer expires or until detecting further control information from the second device for scheduling a new transmission.

[0154] In some example embodiments, the first timer can indicate a minimum duration before a DL assignment or UL grant for a retransmission is expected for the first retransmission scheme; i.e., the first timer is an RTT timer for the first retransmission scheme. The second timer can indicate a minimum duration before a DL assignment or UL grant for a retransmission is expected for the second retransmission scheme; i.e., the first timer is an RTT timer for the second retransmission scheme. If a DL (re)transmission is performed, the first device 110 can start the first timer upon receiving a transmission of data from the second device 120. In case of a UL (re)transmission is performed, the first device 110 can start the first timer upon transmission of data to the second device 120.

[0155] In some example embodiments, in accordance with a determination that the first configuration indicates a first value for the first timer, the first device 110 can directly set the first value for the first timer based on the first configuration. In accordance with a determination that the first configuration indicates a scaling factor for the first timer and the second configuration indicates a second value for the second timer, the first device 110 can set the first value for the first timer based on the scaling factor and the second value for the second retransmission scheme, e.g., by determining the first value based on a product of them or a sum of them.

[0156] Figure 13 A flowchart of an example method 1300 implemented at a second device is shown in accordance with some example embodiments of the present disclosure. For purposes of discussion, reference will be made to the system 1000 of FIG. 10. Figure 1 The method 1300 is described from the perspective of the second device 120.

[0157] At block 1310, the second device 120 sends control information to the first device 110, the control information indicating a first retransmission scheme to be applied to transmissions of data between the first device 110 and the second device 120. The first retransmission scheme requires retransmission of data to be performed independently of feedback to a previous transmission of the data. At block 1320, the second device 120 sends timing information specific to the first retransmission scheme to the first device 110. The timing information indicates a retransmission timing to configure timing for the first device 110 to enter an active state to monitor for further control information from the second device 120 scheduling a retransmission. In some example embodiments, the second device 120 can send the timing information via a physical layer DL control channel.

[0158] In some example embodiments, the retransmission timing can include a time interval during which the first device 110 is in an inactive state and an end of which triggers a start of a retransmission timer at the first device 110. The retransmission timer can indicate a maximum duration until the first device 110 receives a DL retransmission or a UL grant for a UL retransmission.

[0159] Figure 14 A flowchart illustrating an example method 1400 implemented at a second device according to some example embodiments of the present disclosure is shown. For purposes of discussion, the method 1400 will be described with reference to the first device 110 and the second device 120 of FIG. 1. Figure 1 The method 1400 is described from the perspective of the second device 120.

[0160] At block 1410, the second device 120 sends a first configuration of a first timer of the first device 110 for a first retransmission scheme to the first device 110. At block 1420, the second device 120 sends a second configuration of a second timer of the first device 110 for a second retransmission scheme different from the first retransmission scheme to the first device 110. At block 1430, the second device 120 sends control information to the first device 110. The control information indicates that the first retransmission scheme is to be applied to transmissions of data between the first device 110 and the second device 120.

[0161] The first configuration or the combination of the first configuration and the second configuration can be used by the first device 110 to compute a first value of the first timer for the first retransmission scheme. By sending a different first configuration and / or a different second configuration to the first device 110, the second device 120 can control the value of the first timer for the first retransmission scheme. Typically, the first device 110 and the second device 120 can apply the same method to determine the first value of the first timer based on the first configuration or the combination of the first configuration and the second configuration.

[0162] In some example embodiments, the first configuration indicates a first value of the first timer. In some example embodiments, the first configuration indicates a scaling factor of the first timer and the second configuration indicates a second value of the second timer. In this case, the first value can be determined based on the scaling factor and the second value.

[0163] Example apparatus

[0164] In some example embodiments, a first apparatus capable of performing any of the methods 1100 (e.g., the first device 110) can include means for performing the corresponding operations of the methods 1100. The means can be implemented in any suitable form. For example, the means can be implemented in circuitry or software modules. The first apparatus can be implemented as or included in the first device 110.

[0165] In some example embodiments, the first apparatus includes means for receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied to transmissions of data between the first apparatus and the second apparatus, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback for a previous transmission of the data; receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing; and determining, based on the retransmission timing, a timing for monitoring for further control information from the second apparatus to schedule the retransmission.

[0166] In some example embodiments, the retransmission timing comprises a time interval during which the first apparatus can be in an inactive state, and the means for determining the timing comprises means for determining to start a retransmission timer and enter an active state after an end of the time interval, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received; and remaining in the active state to monitor for the further control information until the retransmission timer expires or until the further control information is detected.

[0167] In some example embodiments, the first apparatus further comprises means for setting a value of a round-trip time timer to zero in accordance with the reception of the control information indicating the first retransmission scheme to be applied, or means for disabling a round-trip time timer in accordance with the reception of the control information indicating the first retransmission scheme to be applied. The round-trip time timer indicates a minimum duration before a downlink assignment or an uplink grant expected for a hybrid automatic repeat request based retransmission.

[0168] In some example embodiments, the means for receiving the timing information comprises means for receiving the timing information via a physical layer downlink control channel.

[0169] In some example embodiments, the means for receiving timing information comprises means for detecting a field of a physical layer downlink control channel. In case the second retransmission scheme is configured, then the field can indicate a feedback timing indicator, and in case the first retransmission scheme is configured, then the field can indicate the timing information. That is, the field can have different meanings for different retransmission schemes. Alternatively, the field can be dedicated to indicate the timing information of the first retransmission scheme.

[0170] In some example embodiments, the control information can implicitly or explicitly indicate the retransmission scheme. For example, the control information can comprise an indication to enable / disable hybrid automatic repeat request feedback and / or an indication for the retransmission scheme to indicate the first retransmission scheme.

[0171] In some example embodiments, the first apparatus further comprises means for receiving, from the second apparatus via higher layer signaling, a set of candidate values for retransmission timing of the first retransmission scheme. The means for receiving timing information comprises means for receiving, via the physical layer downlink control channel, timing information indicating one of the candidate values.

[0172] In some example embodiments, the set of candidate values received by the first apparatus can instead indicate a list of timings for transmission of feedback if the second retransmission scheme is configured.

[0173] In some example embodiments, the first apparatus further comprises means for performing other operations in some example embodiments of the method 1100. In some example embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the performance of the first apparatus.

[0174] In some example embodiments, a first apparatus (e.g., the first device 110) capable of performing any of the methods 1200 can include means for performing the corresponding operations of the methods 1200. The means can be implemented in any suitable manner. For example, the means can be implemented in circuitry or a software module. The first apparatus can be implemented as or included in the first device 110.

[0175] In some example embodiments, the first apparatus comprises means for receiving, from the second apparatus, a first configuration of a first timer for the first retransmission scheme; receiving, from the second apparatus, a second configuration of a second timer for a second retransmission scheme different from the first retransmission scheme; and based on a determination that the first retransmission scheme is to be applied to transmission of data between the first apparatus and the second apparatus, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

[0176] In some example embodiments, the first retransmission scheme requires retransmission of data to be performed independently of feedback for the previous transmission of the data.

[0177] In some example embodiments, the first value of the first timer indicates a time duration after receiving control information from the second device, the control information being used to schedule a new transmission between the first device and the second device for the first retransmission scheme, and the second timer indicates a time duration for the second retransmission scheme. The first device further comprises means for starting the first timer after receiving the control information and remaining in an active state until the first timer expires or until detecting further control information from the second device for scheduling the new transmission.

[0178] In some example embodiments, the first timer indicates a minimum time duration for the first retransmission scheme before a downlink assignment or an uplink grant for retransmission is expected, and the second timer indicates a minimum time duration for the second retransmission scheme. The first device further comprises means for starting the first timer after receiving a transmission of data from the second device; or means for starting the first timer after transmission of the data to the second device.

[0179] In some example embodiments, the means for setting the first value for the first timer comprises means for setting the first value of the first timer in accordance with a determination that the first configuration indicates the first value of the first timer; and setting the first value of the first timer based on a scaling factor indicated by the first configuration and a second value of the second timer indicated by the second configuration in accordance with a determination that the first configuration indicates the scaling factor and the second configuration indicates the second value of the second timer.

[0180] In some example embodiments, the first device further comprises means for performing other steps of the method 1200. In some example embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the performance of the first device.

[0181] In some example embodiments, a second device (e.g., the second device 120) capable of performing any of the methods 1300 can include means for performing the corresponding operations of the methods 1300. The means can be implemented in any suitable form. For example, the means can be implemented in circuitry or software modules. The second device can be implemented as or included in the second device 120.

[0182] In some example embodiments, the second apparatus comprises means for transmitting, to the first apparatus, control information indicating a first retransmission scheme to be applied to transmissions of data between the first apparatus and the second apparatus, the first retransmission scheme requiring retransmission of data to be performed independently of feedback to a previous transmission of the data; and transmitting, to the first apparatus, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure a timing for the first apparatus to monitor for further control information from the second apparatus scheduling the retransmission.

[0183] In some example embodiments, the retransmission timing comprises a time interval in which the first apparatus is in an inactive state and an end of which triggers a start of a retransmission timer at the first apparatus, the retransmission timer indicating a maximum duration until the first apparatus receives a downlink retransmission or an uplink grant of an uplink retransmission.

[0184] In some example embodiments, the means for transmitting the timing information comprises means for transmitting the timing information via a physical layer downlink control channel.

[0185] In some example embodiments, the second apparatus further comprises means for performing other operations of the method 1300 in some example embodiments. In some example embodiments, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the performance of the second apparatus.

[0186] In some example embodiments, a second apparatus (e.g., the second device 120) capable of performing any of the methods 1400 can include means for performing the corresponding operations of the methods 1400. The means can be implemented in any suitable form. For example, the means can be implemented in circuitry or software modules. The second apparatus can be implemented as or included in the second device 120.

[0187] In some example embodiments, the second apparatus comprises means for transmitting, to the first apparatus, a first configuration of a first timer of the first apparatus for a first retransmission scheme; transmitting, to the first apparatus, a second configuration of a second timer of the first apparatus for a second retransmission scheme different from the first retransmission scheme; and transmitting, to the first apparatus, control information indicating the first retransmission scheme to be applied to transmissions of data between the first apparatus and the second apparatus, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value of the first timer.

[0188] In some example embodiments, the first configuration indicates a first value of the first timer. In some example embodiments, the first configuration indicates a scaling factor of the first timer, the second configuration indicates a second value of the second timer, and the first value is determined based on the scaling factor and the second value.

[0189] In some example embodiments, the second device further includes components for performing other operations of method 1400 in some example embodiments. In some example embodiments, the components include at least one processor; and at least one memory, including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause performance of the second device.

[0190] Example devices and computer-readable media

[0191] Figure 15 This is a simplified block diagram of a device 1500 suitable for implementing an example embodiment of the present disclosure. Device 1500 can be provided to implement a communication device, such as... Figure 1 The first device 110 or the second device 120 shown. As shown, device 1500 includes one or more processors 1510, one or more memories 1520 coupled to processor 1510, and one or more communication modules 1540 coupled to processor 1510.

[0192] Communication module 1540 is used for bidirectional communication. Communication module 1540 has at least one antenna to facilitate communication. The communication interface can represent any interface necessary for communication with other network elements.

[0193] Processor 1510 can be of any type suitable for a local technology network, and by way of non-limiting example, can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Device 1500 can have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock synchronized with the main processor.

[0194] Memory 1520 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 1524, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disk (DVD), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1522 and other volatile memories that do not persist during power outages.

[0195] The computer program 1530 includes computer executable instructions that are executed by the associated processor 1510. The program 1530 can be stored in the memory (e.g., ROM 1524). The processor 1510 can perform any suitable action and processing by loading the program 1530 into the RAM 1522.

[0196] Example embodiments of the present disclosure can be implemented with the aid of the program 1530, such that the apparatus 1500 can perform any of the processes of the present disclosure as discussed above with reference to Figures 2 to 14 Example embodiments of the present disclosure can also be implemented by hardware or by a combination of software and hardware.

[0197] In some example embodiments, the program 1530 can be tangibly embodied in a computer-readable medium, which can be included in the apparatus 1500 (such as in the memory 1520) or in another storage device accessible by the apparatus 1500. The apparatus 1500 can load the program 1530 from the computer-readable medium into the RAM 1522 for execution. The computer-readable medium can include any type of tangible non-transitory memory, such as ROM, EPROM, flash memory, a hard disk, a CD-ROM, a DVD, and the like. Figure 16 An example of a computer-readable medium 1600 in the form of a CD or DVD is shown. The computer-readable medium has the program 1530 stored thereon.

[0198] In general, the various embodiments of the present disclosure can be implemented using hardware or special-purpose circuits, software, logic or any combination thereof. Some aspects can be implemented using hardware, while other aspects can be implemented using software or firmware that is executed by a controller, microprocessor or other computing device. Although the various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein can be implemented using hardware, software, firmware, special-purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0199] The present disclosure also provides at least one computer program product that is tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as those included in program modules, executed by devices on a target real or virtual processor to perform the processes as described above with reference to Figures 1 to 14Any of the methods described. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules can be combined or split between program modules as desired in various embodiments. Machine executable instructions for a program module can be executed within a local or distributed device. In a distributed device, program modules can be located in both local and remote memory storage media.

[0200] Program code for carrying out methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / operations specified in the flowcharts and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, as a stand-alone software package, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0201] In the context of the present disclosure, computer program code or related data can be embodied by any suitable carrier wave, including a signal, carrier wave, light, radio frequency (RF), sound, or other transmission media by which a device, apparatus, or processor can process a various processes and operations described herein. Examples of a carrier wave include a signal, carrier wave, light, radio frequency (RF), sound, or other transmission media by which information is conveyed from one place to another.

[0202] The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable medium can include, but is not limited to, 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 one or more of 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.

[0203] Moreover, while operations can be described as being in a specific order, this should not be understood as requiring that such operations be performed in the specific order, or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Likewise, while various specific implementations are described, these should not be construed as being limiting of the scope of the disclosure, but rather as being descriptive of features that can be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0204] Although the disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device for communication, comprising: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to: receive, from a second device, control information indicating a first retransmission scheme to be applied for transmission of data between the first device and the second device, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback on a previous transmission of the data; receive, from the second device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing, wherein the retransmission timing comprises a time interval during which the first device is in an inactive state; and determine, based on the retransmission timing, a timing for monitoring for further control information from the second device for scheduling the retransmission by: determining to start a retransmission timer after the end of the time interval and enter an active state, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received, and staying in the active state for monitoring for the further control information until the retransmission timer expires or until the further control information is detected, receive, from the second device, the retransmission of the data and the further control information including a retransmission interval; based on the retransmission interval, the reception of the retransmission of the data and determining that the retransmission timer has not expired, stop the retransmission timer and cause the first device to enter the inactive state; based on determining that the retransmission interval has elapsed since the reception of the retransmission of the data, restart the retransmission timer.

2. The device of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, further cause the first device to, in accordance with the reception of the control information indicating the first retransmission scheme to be applied: set a value of a round trip time timer to zero, or disable the round trip time timer, wherein the round trip time timer indicates a minimum duration before a downlink assignment or an uplink grant for a hybrid automatic repeat request based retransmission is expected.

3. The device of claim 1 or 2, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to receive the timing information by: receiving the timing information via a physical layer downlink control channel.

4. The device of claim 3, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to receive the timing information by: receiving the timing information via a physical layer downlink control channel. detecting a field of the physical layer downlink control channel, the field indicating a feedback timing indicator in case a second retransmission scheme is configured and the timing information in case the first retransmission scheme is configured, or the field indicating only the timing information for the first retransmission scheme.

5. The device of claim 1 or 2, wherein the control information comprises an indication to enable / disable hybrid automatic repeat request feedback and / or an indication for a retransmission scheme to indicate the first retransmission scheme.

6. The device of claim 1 or 2, wherein the at least one memory and the computer program code are configured, with the at least one processor, further to cause the first device to: receive, from the second device via higher layer signaling, a set of candidate values for retransmission timing for the first retransmission scheme, and wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the first device to receive the timing information by receiving, via a physical layer downlink control channel, the timing information indicating one of the candidate values.

7. The device of claim 6, wherein the set of candidate values indicates a list of timing for transmission feedback in case a second retransmission scheme is configured.

8. A second device for communication, comprising: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the second device to: send, to a first device, control information indicating a first retransmission scheme to be applied to transmissions of data between the first device and the second device, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback for a previous transmission of the data; and send, to the first device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure timing for the first device to monitor for further control information from the second device scheduling the retransmission, wherein the retransmission timing comprises a time interval during which the first device is in an inactive state and an end of the time interval triggers a start of a retransmission timer at the first device, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received by the first device; send, to the first device, the retransmission of the data and the further control information containing a retransmission interval, such that in response to the first device receiving the retransmission of the data and the further control information and the retransmission interval having elapsed from the reception of the retransmission of the data, the retransmission timer is restarted.

9. The device of claim 8, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the second device to send the timing information via a physical layer downlink control channel.

10. A method for communication, comprising: receiving, at a first device and from a second device, control information indicating a first retransmission scheme to be applied to transmission of data between the first device and the second device, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback to a previous transmission of the data; receiving, from the second device, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing, wherein the retransmission timing comprises a time interval during which the first device is in an inactive state; and determining a timing for monitoring, by the first device, for further control information from the second device to schedule the retransmission based on the retransmission timing, wherein determining the timing comprises: determining to start a retransmission timer after an end of the time interval and enter an active state, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received, and staying in the active state for monitoring the further control information until the retransmission timer expires or until the further control information is detected; and receiving, from the second device, the retransmission of the data and the further control information including a retransmission interval; stopping the retransmission timer and causing the first device to enter the inactive state based on the retransmission interval, the reception of the retransmission of the data, and determining that the retransmission timer has not expired; restarting the retransmission timer based on determining that the retransmission interval has elapsed since the reception of the retransmission of the data.

11. The method of claim 10, wherein receiving the timing information comprises: receiving the timing information via a physical layer downlink control channel.

12. A method for communication, comprising: sending, at a second device and to a first device, control information indicating a first retransmission scheme to be applied to transmission of data between the first device and the second device, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback to a previous transmission of the data; and sending, to the first device via a physical layer downlink control channel, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing to configure a timing for the first device to monitor, from the second device, for further control information to schedule the retransmission, wherein the retransmission timing comprises a time interval during which the first device is in an inactive state and an end of the time interval triggers a start of a retransmission timer at the first device, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received by the first device. ​ transmitting, to the first device, the retransmission of the data and the further control information including a retransmission interval, such that, in response to the first device receiving the retransmission of the data and the further control information and having elapsed the retransmission interval from the reception of the retransmission of the data, the retransmission timer is restarted.

13. A first apparatus for communication, comprising means for: receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied to transmissions of data between the first apparatus and the second apparatus, the first retransmission scheme requiring a retransmission of the data to be performed independently of feedback on a previous transmission of the data; receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating a retransmission timing, wherein the retransmission timing comprises a time interval during which the first apparatus is in an inactive state; and determining, based on the retransmission timing, a timing for monitoring, by the first apparatus, for further control information from the second apparatus scheduling the retransmission: determining to start a retransmission timer and enter an active state after the end of the time interval, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received; and staying in the active state for monitoring for the further control information until the retransmission timer expires or until the further control information is detected, receiving, from the second apparatus, the retransmission of the data and the further control information including a retransmission interval; stopping the retransmission timer and causing the first apparatus to enter the inactive state based on the retransmission interval, the reception of the retransmission of the data, and determining that the retransmission timer has not expired; restarting the retransmission timer based on determining that the retransmission interval has elapsed from the reception of the retransmission of the data.

14. A second apparatus for communication, comprising means for: transmitting control information to a first device, the control information indicating a first retransmission scheme to be applied to transmission of data between the first device and a second device, the first retransmission scheme requiring retransmission of the data to be performed independently of feedback for a previous transmission of the data; and transmitting, to the first device, the retransmission of the data and the further control information including a retransmission interval, such that, in response to the first device receiving the retransmission of the data and the further control information and having elapsed the retransmission interval from the reception of the retransmission of the data, the retransmission timer is restarted. transmitting, to the first device, the retransmission of the data and the further control information including a retransmission interval, such that, in response to the first device receiving the retransmission of the data and the further control information and having elapsed the retransmission interval from the reception of the retransmission of the data, the retransmission timer is restarted.

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