WO2021088015A1

WO2021088015A1 - Discontinuous reception mechanism supporting blind retransmission

Info

Publication number: WO2021088015A1
Application number: PCT/CN2019/116799
Authority: WO
Inventors: Pingping Wen; Ping Yuan; Wenjian Wang; Chunli Wu; Samuli Turtinen
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2021-05-14
Also published as: CN114556833A

Abstract

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

Description

DISCONTINUOUS RECEPTION MECHANISM SUPPORTING BLIND RETRANSMISSION

FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for discontinuous reception (DRX) .

BACKGROUND

With developments of communication systems, new technologies have been proposed. 3rd Generation Partnership Project (3GPP) release (Rel) -16 includes a study item on how fifth generation (5G) new radio (NR) standards may support non-terrestrial network (NTN) deployments using satellites and high altitude platform stations (HAPS) to provide connectivity across a wide service area. In many NTN deployment scenarios, the round trip time (RTT) for signal propagation may be considerably longer compared to terrestrial networks intended for NR interfaces. As a result, these longer propagation delays may pose a challenge to discontinuous reception (DRX) in hybrid automatic repeat request (HARQ) processes for retransmission of erroneous packets. It is thus desired to improve DRX operations in the scenarios with longer RTT delay, such as in NTN.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for DRX which can be applied to, e.g., but not limited to, a communication scenario supporting blind retransmission.

In a first aspect, there is provided a first device. The first device comprises at least one processor; and at least one memory including computer program code; where 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 and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; receive, from the second device, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing; and determine, based on the retransmission timing, timing for monitoring further control information from the second device for scheduling the retransmission.

In a second aspect, there is provided a first device. The first device comprises at least one processor; and at least one memory including computer program code; where 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 for a first timer for a first retransmission scheme; receive, from the second device, a second configuration for 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 transmission of data between the first and second devices, set a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

In a third aspect, there is provided a second device. The second device comprises at least one processor; and at least one memory including computer program code; where 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 for transmission of data between the first and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent 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 retransmission timing, to configure timing for the first device to monitor further control information from the second device for scheduling the retransmission.

In a fourth aspect, there is provided a second device. The second device comprises at least one processor; and at least one memory including computer program code; where 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 for a first timer of the first device for a first retransmission scheme; transmit, to the first device, a second configuration for 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 for transmission of data between the first and second devices, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

In a fifth aspect, there is provided a method. The method comprises receiving, at a first device and from a second device, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent 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 retransmission timing; and determining, based on the retransmission timing, timing for monitoring further control information from the second device for scheduling the retransmission.

In a sixth aspect, there is provided a method. The method comprises receiving, at a first device and from a second device, a first configuration for a first timer for a first retransmission scheme; receiving, from the second device, a second configuration for 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 transmission of data between the first and second devices, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

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

In an eighth aspect, there is provided a method. The method comprises transmitting, at a second device and to a first device, a first configuration for a first timer of the first device for a first retransmission scheme; transmitting, to the first device, a second configuration for 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 transmission of data between the first and second devices, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

In a ninth aspect, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing; and determining, based on the retransmission timing, timing for entering an active status for monitoring further control information from the second apparatus for scheduling the retransmission.

In a tenth aspect, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, a first configuration for a first timer for a first retransmission scheme; receiving, from the second apparatus, a second configuration for 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 transmission of data between the first and second apparatuses, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

In an eleventh aspect, there is provided a second apparatus. The second apparatus comprises means for transmitting, to a first apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; and transmitting, to the first apparatus, timing information specific to the first retransmission scheme via a physical layer downlink control channel, the timing information indicating retransmission timing, to configure timing for the first apparatus to enter an active status for monitoring further control information from the second apparatus for scheduling the retransmission.

In a twelfth aspect, there is provided a second apparatus. The second apparatus comprises means for transmitting, to a first apparatus, a first configuration for a first timer of the first apparatus for a first retransmission scheme; transmitting, to the first apparatus, a second configuration for 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 that the first retransmission scheme is to be applied for transmission of data between the first and second apparatuses, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.

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

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

Fig. 1 illustrates an example communication system in which example embodiments of the present disclosure may be implemented;

Fig. 2 illustrates a signaling flow for data retransmission according to some example embodiments of the present disclosure;

Fig. 3 illustrates a signaling flow for data retransmission in downlink (DL) according to some example embodiments of the present disclosure;

Fig. 4 illustrates a signaling flow for data retransmission in uplink (UL) according to some example embodiments of the present disclosure;

Fig. 5 illustrates a signaling flow for data retransmission in DL according to some other example embodiments of the present disclosure;

Fig. 6 illustrates a signaling flow for data retransmission according to some other example embodiments of the present disclosure;

Fig. 7 illustrates a signaling flow for data retransmission in DL according to some other example embodiments of the present disclosure;

Fig. 8 illustrates a signaling flow for data retransmission in UL according to some other example embodiments of the present disclosure;

Fig. 9 illustrates a signaling flow for data retransmission in DL according to some further example embodiments of the present disclosure;

Fig. 10 illustrates a signaling flow for data retransmission in UL according to some further example embodiments of the present disclosure;

Fig. 11 illustrates a flowchart of a method implemented at a first device according to some example embodiments of the present disclosure;

Fig. 12 illustrates a flowchart of a method implemented at a first device according to some other example embodiments of the present disclosure;

Fig. 13 illustrates a flowchart of a method implemented at a second device according to some example embodiments of the present disclosure;

Fig. 14 illustrates a flowchart of a method implemented at a second device according to some other example embodiments of the present disclosure;

Fig. 15 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure; and

Fig. 16 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

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

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

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

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

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.

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

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

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

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

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

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology.

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

Example environment and work principle

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

In the NTN network, a first device 110-1 and a 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 a NTN network device serving the terminal device. The serving area of the second device 120-1 is called as a cell 102-1. In the TN network, a first device 110-2 and a 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 serving area of the second device 120-2 is called as a cell 102-2. For convenience of discussion, in the following, the first devices 110-1 and 110-2 are collectively or individually referred to as first devices 110, the second devices 120-1 and 120-2 are collectively or individually referred to as second devices 120, the cells 102-1 and 102-2 are collectively or individually referred to as cells 102.

It is to be understood that the number of first and second devices is only for the purpose of illustration without suggesting any limitations. The communication system 100 may include any suitable number of first and second devices adapted for implementing embodiments of the present disclosure. Although not shown, it would be appreciated that one or more additional terminal devices may be located in the cell 102 and served by the second device 120.

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

In the communication system 100, the first device 110 and the second device 120 can communicate data and control information to each other. In the case that the first device 110 is a terminal device and the second device 120 is a network device, a link from the second device 120 to the first device 110 is referred to as a downlink (DL) , while a link from the first device 110 to the second device 120 is referred to as an uplink (UL) . In DL, the second device 120 is a transmitting (TX) device (or a transmitter) and the first device 110 is a receiving (RX) device (or a receiver) . In UL, the first device 110 is a TX device (or a transmitter) and the second device 120 is a RX device (or a receiver) .

In operation, the first device 110 may monitor control information from the second device 120 scheduling an assignment for transmission from the second device 120 to the first device 110 (for example, an DL assignment) or scheduling an grant for transmission from the first device 110 to the second device 120 (for example, an UL grant) . Discontinuous reception (DRX) can be applied to supports battery saving of the first device 110 by reducing the time for monitoring control information from the second device 120 and entering into an inactive status.

In some scenarios, a propagation delay between a transmitter and a receiver is relatively large, resulting in a long round-trip-time (RTT) , especially for the NTN. The traditional DRX mechanism may not be suitable for communication with a long propagation delay.

As known, any system that has a propagation delay larger than the number of available hybrid automatic repeat request (HARQ) processes may suffer from HARQ stalling. High transmission delays in the NTN (especially with GEO satellite network devices) will require the transmitter to maintain a large number of HARQ processes, which may not be impractical due to the extreme buffer size requirement for the receiver’s soft buffer and large signalling requirement on indicating the HARQ process number. Additionally, the retransmission will also cause long latency for a packet. However, in both TN and NTN networks, HARQ has valuable gains to provide reliability with lower cost (as compared with automatic repeat request (ARQ) ) by the gain of soft combining and shorter latency (as compared with ARQ) .

Therefore, allowing HARQ enabling and disabling may be advantageous, especially for NTN. For example, for NTN, the network device could disable UL HARQ feedback for DL transmission at the terminal device, e.g. to support long propagation delays. Enabling/disabling of HARQ feedback may be signalled semi-statically to the terminal device by radio resource control (RRC) signalling. The enabling/disabling of HARQ feedback for DL transmission may be configurable per terminal device and per HARQ process via RRC signalling, but dynamic enabling and disabling of HARQ for a HARQ process is also possible. Further, for NTN, the network may disable HARQ UL retransmission at the terminal device. The enabling/disabling of HARQ UL retransmission may be configurable per terminal device, per HARQ process, and per logical channel (LCH) .

If HARQ feedback is disabled, some open loop/blind retransmission (for example, retransmission without feedback, or retransmission independent of HARQ feedback) mechanism should be considered. With the blind retransmission, the network device can schedule a retransmission at any time independent of the feedback. Since the blind retransmission has the merit of reducing latency and improving the reliability as well as dynamically scheduling the resources for retransmission, it is a type of retransmission scheme which is very promising, especially for scenarios with large propagation delay.

In summary, in at least NTN, the possible (re) transmission schemes may include: 1) single transmission only with HARQ disabled (i.e., HARQ disabled with one-shot data transmission and no retransmission) , 2) blind retransmission with an aggregation factor larger than one in case HARQ is disabled (i.e., continuous multiple transmissions for one transport block set (TBS) which is not based on feedback or the decoding result) , 3) blind retransmission with downlink control information scheduling in case HARQ is disabled (i.e., multiple transmissions for one TBS on sparse TTIs which are not based on feedback or the decoding result, with benefit of scheduling flexibility and gain) , and 4) HARQ-enabled retransmission with retransmission based on feedback or the decoding result, including blind retransmission on top of the legacy HARQ.

Considering that there are types of retransmission schemes, it is not desirable to design a DRX solution by only considering HARQ-enabled transmission. Instead, HARQ-disabled transmission such as blind retransmission should also be considered when designing a DRX solution. One possible DRX solution to support the blind retransmission scheme may be to extend active time of the terminal device by enlarging the value set for one or more timers used in DRX. It is desired to improve the DRX solution by considering the specific features of blind retransmission, so as to balance the power consumption (i.e., the active time for monitoring control information) and flexibility in scheduling and transmission.

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

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

Dynamic retransmission timing-based DRX

Reference is now made to Fig. 2, which shows a signaling flow 200 for data retransmission according to some example embodiments of the present disclosure. For the purpose of discussion, the signaling flow 200 will be described with reference to Fig. 1. The signaling flow 200 may involve a first device 110 and a second device 120 as illustrated in Fig. 1. In some example embodiments, the signaling flow 200 may be particularly beneficial in the scenario where a RTT between the first and

second devices

110, 120 may be relatively large. For example, the signaling flow 200 may involve the first device 110-1 and the second device 120-1 in the NTN network as illustrated in Fig. 1. It would be appreciated that the signaling flow 200 may also be implemented in any other communication networks.

In the signaling flow 200, the second device 120 transmits 205 control information to the first device 110. The control information indicates a retransmission scheme to be applied for transmission of data between the first and second devices 110, 120 (referred to as a “first retransmission scheme” for convenience of discussion) . The first retransmission scheme requires a retransmission of the data to be performed independent of feedback to a previous transmission of the data. That is, the first retransmission scheme is a blind retransmission scheme. The transmission/retransmission between the first and

second devices

110, 120 may be associated with a HARQ process.

According to the first retransmission scheme, a transmitter transmits data to a receiver and retransmits the data without waiting for feedback to the previous transmission, which means that no matter whether a previous transmission is successfully received and detected by the receiver, the transmitter always performs multiple transmissions of the same data as scheduled. For example, a medium access control (MAC) entity schedules the same data on the same HARQ process without the new data indicator (NDI) being toggled. Such blind retransmission may be useful to lower the residual block error rate (BLER) , particularly in case the feedback for HARQ is disabled.

In some example embodiments, the first retransmission scheme may further require dynamic scheduling. That is, the second device 120, such as a network device, may schedule the retransmission dynamically. If the first retransmission scheme is supported, the second device 120 may schedule a retransmission at any time without waiting for the feedback to 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 may also be indicated in the control information. For example, for a retransmission from the second device 120 to the first device 110, the control information may indicate an assignment for the retransmission (for example, a DL assignment) such that the first device 110 can know when and where to detect the retransmission upon receipt of the assignment. For a retransmission from the first device 110 to the second device 120, the control information may indicate a grant for the retransmission (for example, an UL grant) such that the first device 110 can know when and where to perform the retransmission to the second device upon receipt of the grant.

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

For either the retransmission from the second device 120 to the first device 110 (for example, DL retransmission) or from the first device 110 to the second device 120 (for example, UL retransmission) , the second device 120 can transmit the control information to indicate whether the first retransmission scheme is applied for the following retransmission. In some example embodiments, the control information may be transmitted via a physical layer downlink control channel, for example, PDCCH. In this example, the control information may also be referred to as DL control information (i.e., DCI) . In some example embodiments, the control information may include an indication for enabling/disabling HARQ feedback to indicate the first retransmission scheme. For example, if this indication indicates that the HARQ feedback is disabled, the first device 110 may determine that the first retransmission scheme is to be applied for the retransmission. Alternatively, or in addition, the control information may include an indication for a retransmission scheme, which may be used to explicitly indicate the first retransmission scheme that is to be applied.

In case the first retransmission scheme is to be applied for transmission between the first and

second devices

110, 120, the second device 120 also transmits 215 timing information specific to the first retransmission scheme to the first device 110. The timing information indicates retransmission timing for the first retransmission scheme. The retransmission timing indicates when a retransmission of the data can be expected or a time interval during which retransmission cannot be expected. In some example embodiments, the timing information may be transmitted by the second device 120 via a physical layer downlink control channel, for example, PDCCH. The timing information may also be included in DCI together with the control information indicating the first retransmission scheme. Alternatively, in some example embodiments, the control information indicating the first retransmission scheme may be sent via higher layer signaling, while the timing information may be carried in physical layer signaling, such as via a physical layer downlink control channel (for example, PDCCH) . In some example embodiments, the timing information in DCI may be indicated via different fields, depend on whether the transmission is for DL or UL, which will be described in detail below.

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

The first device 110 may operate in a DRX mode and can transition between an inactive status and an active status for purpose of power saving. In the inactive status, the first device 110 is not required to monitor control information from the second device 120. In the active status, the first device 110 will be active for control information monitoring and thus may receive the DL assignment or UL grant for data (re) transmission. According to the example embodiments of the present disclosure, as the second device 120 is responsible for scheduling of (re) transmission scheduling, it can dynamically inform suitable retransmission timing for the first retransmission scheme with more flexibility. The first device 110 may know, based on the retransmission timing information, when the further control information scheduling a retransmission of data can be expected from the second device 120. Accordingly, the first device 110 can enter into the active status at the right time to detect and receive the further control information. In some example embodiments, the first device 110 may stay in the inactive status to save the power consumption if there is no other running DRX timer (s) (such as a running inactivity timer) indicating the first device 110 to enter the active status.

In some example embodiments, the retransmission timing may include a time interval during which the first device 110 can be in an inactive status. With the explicit indication of the time interval from the second device 120, the first device 110 may determine to start a retransmission timer upon ending of the time interval. In DRX, a retransmission timer may be used by the first device 110 to actively start monitoring of control information from the second device 120. The retransmission timer may 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 the 3GPP-based communication system, the retransmission timer may also be referred to as drx-RetransmissionTimer, drx-RetransmissionTimerDL, or drx-RetransmissionTimerUL. Through the indication of the time interval, the start of the retransmission timer can be dynamically triggered. After the retransmission timer is started, the first device 110 may keep in the active status for monitoring the further control information from the second device 120 until expiry of the retransmission timer or until detection of the further control information. The value of the retransmission timer may be set, for example, via RRC configuration signalling.

It would be appreciated that except for the time interval, the retransmission timing may be indicated in other manners for the first device 110 to determine timing to enter the active status.

In some example embodiments, in order to enter the active status based on the indicated retransmission timing, for example, by starting the retransmission timer, the first device 110 may set a value of a RTT timer to be zero. The RTT timer is a DRX timer that indicates a minimum duration before a DL assignment for HARQ-based retransmission (in DL retransmission from the second device 120 to the first device 110) or an UL grant for HARQ-based retransmission (in UL retransmission from the first device 110 to the second device 120) is expected. In the 3GPP-based communication system, the RTT timer may 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 be 0, the RTT timer and the corresponding function may be disabled if the first retransmission scheme is configured.

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

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

Through dynamically indicating the retransmission timing to the first device 110, the second device 120 may control the timer when the first device 110 can start monitoring the further control information in the first retransmission scheme or can start the retransmission timer. The retransmission timing (for example, the time interval during which no retransmission can be expected and the first device 110 can be in an inactive status) may be determined based on various factors. In some example embodiments, the second device 120 may determine the retransmission timing based on a channel condition between the first and

second devices

110, 120, a service requirement on the data to be transmitted, a load condition in serving coverage of the second device 120, and/or the like.

For example, if the data to be transmitted (for example, data included in a MAC protocol data unit (PDU) ) is with a high latency requirement, the second device 120 may schedule a following blind retransmission closely after a previous transmission of the data. Thus, the retransmission timing may include a short retransmission interval, and the first device 110 may enter the active status timely to receive control information scheduling the following retransmission. If the data is with a lower latency requirement and the second device 120 is with high load, the second device 120 will schedule the blind retransmission a long time after a previous transmission. As another example, the second device 120 may obtain the channel correlation time in the current channel condition and can determine a possible time duration for the following retransmission. The second device 120 may thus inform the first device 110 with a timing to start the retransmission timer.

The dynamic retransmission timing-based DRX solution has been discussed above. To better understand such solution, some examples of DRX operation supporting the (re) transmission from the second device 120 to the first device 110 (for example, DL (re) transmission) and from the first device 110 to the second device 120 (for example, UL (re) transmission) will be described with reference to Fig. 3 and Fig. 4 respectively.

DL (re) transmission in dynamic retransmission timing-based DRX

Fig. 3 illustrates a signaling flow 300 in DL (re) transmission between the first and

second devices

110, 120 according to some example embodiments of the present disclosure. In the example of Fig. 3, the first device 110 operates in a DRX mode and dynamic retransmission timing is controlled by the second device 120.

In the signaling flow 300, the second device 120 transmits 305 DCI to the first device 110, for example, via a physical layer DL control channel. In addition to indicate a DL assignment for a current transmission of data, the DCI may further indicate that the 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 transmitted by the second device 120 to the first device 110 in 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 may determine that the second device 120 will schedule a blind retransmission of the data later regardless of feedback to the previous transmission. If the first retransmission scheme is to be applied, the DCI may further include timing information indicating retransmission timing, such as a retransmission interval (represented as “K1” ) .

In some example embodiments, a new defined field in DCI may be used to indicate the retransmission timing. In some other example embodiments, in the DL (re) transmission, if the first retransmission scheme is to be applied, one or more fields of the physical layer DL control channel (for example, DCI) used in other retransmission schemes (referred to as a second retransmission scheme) requiring feedback may not be needed to carry corresponding parameters for the second retransmission scheme as those parameters are required in the feedback-disabled case. Such field in the physical layer DL control channel may be reused for indicating the timing information for the first retransmission scheme.

The second retransmission scheme is different from the first retransmission scheme. An example of the second retransmission scheme is a HARQ-enabled retransmission scheme with feedback required, such as the legacy HARQ-enabled retransmission scheme. An example of the field to be reused to indicate retransmission timing for the first retransmission scheme may be a field that was used to indicate a feedback timing indicator if the second retransmission scheme requiring feedback is configured. Therefore, this reused field in DCI may indicate a feedback timing indicator if a second retransmission scheme is configured and indicate the timing information if the first retransmission scheme is configured.

In the 3GPP-based communication system, the field indicating the feedback timing indicator may be a field “PDSCH-to-HARQ_feedback timing indicator, ” where PDSCH refers to a physical downlink shared channel. The meaning of the field “PDSCH-to-HARQ_feedback timing indicator” may be redefined when the first retransmission scheme is configured. The mapping between the candidate values for retransmission timing and the indices to be indicated in the field “PDSCH-to-HARQ_feedback timing indicator” may 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 communication standards by introducing the retransmission timing will be minimized.

When the first device 110 receives the control information indicating the first retransmission scheme and the timing information, the first device 110 may 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 may start or restart an inactivity timer, such as drx_inactivityTimer in the 3GPP-based communication system. The inactivity timer indicates a duration after receipt of control information from the second device 120 scheduling a new transmission between the first and

second devices

110, 120. In other words, the inactivity timer may indicate a duration after the PDCCH occasion in which a PDCCH indicates a new UL or DL transmission for the MAC entity.

Generally, the received DCI may indicate a DL assignment for a current transmission. The second device transmits 315 and the first device receives 320 DL data according to the DL assignment.

Based on the retransmission timing indicated in the received timing information, the first device 110 determines timing for monitoring further control information from the second device 120 for scheduling a retransmission of data. In a time interval before the determined timing, the first device 110 may be in an inactive status and will not monitor DCI from the second device 120 in order to achieve power saving. The first device 110 may be in the inactive status for a time interval indicated by “K1” after receipt of DL data at 320, for example, after the end of the last symbol of DL data reception. The time interval “K1” may start from the end of DL data reception. As shown in Fig. 3, after the indicated timer interval “K1” from the receipt of the DL data, the first device 110 starts 325 a retransmission timer for DL retransmission, such as drx-RetransmissionTimerDL. The retransmission timer may be started, for example, in the first symbol after the timing interval K1 indicated in the DCI.

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

After the retransmission timer is started, the first device 110 will enter the active status and can monitor and receive further control information from the second device 120 scheduling a retransmission. The first device 110 will keep in the active status until expiry of the retransmission timer or until detection of the further control information. In the example shown in Fig. 3, the second device 120 decides to schedule a retransmission of the DL data for the first device 110 and transmits 330 further DCI to the first device 110, which DCI indicates scheduling of the retransmission of the DL data. For example, the DCI may indicate a DL assignment for the current retransmission to be scheduled. The retransmission timer at the first device 110 does not expire and thus the first device 110 monitors and receives 335 the further DCI successfully.

In some example embodiments, the further DCI may also indicate that the first retransmission scheme is to be applied and further include timing information indicating retransmission timing (such as a retransmission interval represented as “K2” ) . The retransmission interval “K2” may be the same or different from that retransmission interval “K1. ” The second device 120 may determine the retransmission interval “K2” depending on various factors as discussed above when transmitting the further DCI.

The second device 120 transmits 340 and the first device 110 receives 345 a retransmission of the DL data according to the DL assignment indicated in the further DCI. Upon receipt of the retransmission of the DL data, the first device 110 may stop the retransmission timer started previously if the retransmission timer is still running. The first device 110 may then enter an inactive status for the time interval “K2. ” After the time interval “K2” lapsed from the receipt of the retransmission of the DL data, the first device 110 restarts the retransmission timer.

UL (re) transmission in dynamic retransmission timing-based DRX

Fig. 4 illustrates a signaling flow 400 in UL (re) transmission between the first and

second devices

110, 120 according to some example embodiments of the present disclosure. In the example of Fig. 4, the first device 110 operates in a DRX mode and dynamic retransmission timing is controlled by the second device 120.

In the signaling flow 400, the second device 120 transmits 405 DCI to the first device 110, for example, via a physical layer DL control channel. The DCI and its transmission may be similar to those discussed above with reference to Figs. 2 and 3. The difference between DCI in Fig. 3 and that in Fig. 4 is that in UL (re) transmission, the DCI include an UL grant for the first device 110 to transmit its UL data (which may be a new transmission or a retransmission) . The retransmission timing, such as a retransmission interval indicated in the DCI, is represented as “T1. ”

The DCI for UL (re) transmission may not have a field (such as “PDSCH-to-HARQ_feedback timing indicator” indicating the feedback timing indicator) that can be reused for indicating the retransmission timing as in the DCI for the DL (re) transmission. Thus, the timing information may be included in a new defined field in DCI. Further, the RRC signaling for UL (re) transmission may not have the IE indicating a list of timings for transmission of feedback (such as the IE “dl-DataToUL-ACK” ) that can be reused to configure the set of candidate values to the first device 110, and therefore, a new IE in the RRC signaling may be used to indicate the candidate values for the retransmission timing.

The first device 110 receives 410 the DCI. The operations of the first device 110 upon receipt of the DCI may be similar to those discussed above with reference to Figs. 2 and 3. The first device 110 transmits 415 and the second device 120 receives 420 UL data according to the UL granted indicated in the DCI.

Similar to in the DL (re) transmission, the first device 110 may be in an inactive status after the transmission of the UL data (for example, after the end of the last symbol of the transmission) for the time interval “T1. ” As shown in Fig. 4, 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 UL retransmission, such as drx-RetransmissionTimerUL. The retransmission timer may be started, for example, in the first symbol after the timing interval T1 indicated in the DCI. The second device 120 transmits 430 further DCI and the first device 110 receives 435 the further DCI.

If the further DCI still indicates the first retransmission scheme (or, the further DCI does not indicate a change to the retransmission scheme) to be applied and the timing information for the first retransmission scheme, the first and

second devices

110 and 120 may perform similar operations as at 415, 420, and 425. Specifically, the first device 110 transmits 440 and the second device 120 receives 445 a retransmission of UL data according to the UL granted indicated in the further DCI. After the retransmission of the UL data, the first device 110 restarts 450 the retransmission timer after a timer interval “T2” indicated in the further DCI. Other operations at the first and

second devices

110, 120 may be similar to those discussed with reference to Fig. 2 and Fig. 3.

Example of DCI missing in dynamic retransmission timing-based DRX

Fig. 5 illustrates a signaling flow 500 in DL (re) transmission between the first and

second devices

110, 120 according to some example embodiments of the present disclosure. The example of Fig. 5 is used to show how the DRX is performed in the dynamic retransmission timing-based DRX solution if DCI is missed.

In the signaling flow 500, operations of the first and

second devices

110, 120 at 505, 510, 515, 520, and 525 are similar to the operations of the first and

second devices

110, 120 at 305, 310, 315, 320, and 325 in the signaling flow 300. In the example of Fig. 5, the second device 120 transmits 530 further DCI indicating the first retransmission scheme and further retransmission timing (represented by “K2” ) but the first device 110 fails to receive the further DCI transmitted at 530 to trigger restart of a new retransmission timer. If the retransmission timer started at 525 is still running, the first device 110 is still in the active status and thus can possibly receive another DCI (e.g., the DCI sent by the second device 120 at 540) later and may restart the retransmission timer again, as in the example of Fig. 3.

However, if a DCI arrives at the first device 110 after the retransmission timer (which is started at 525 expires, as shown in Fig. 5, the first device 110 will not receive a retransmission of DL data transmitted 535 by the second device 120 and will not obtain the indication to trigger start of the retransmission. Thus, even if the second device 120 continues scheduling a further retransmission and transmits 540 a third DCI indicating the first retransmission scheme and third retransmission timing (represented by “K3” ) , the first device 110 will miss detection of the third DCI as well as a retransmission of DL data transmitted 545 by the second device 120 as scheduled in the third DCI. However, even such unexpected case happens, it will not have impact on the performance of blind retransmission with soft combining because the first device 110 cannot perform the soft combining for the following DL data on blind retransmission since the first device 110 doesn’t receive the transmission of the DL data on blind retransmission at 535 when the further DCI transmitted at 530 is missed. For this case, the retransmission for the reliability can depend on the normal HARQ.

DRX based on transmission scheme-specific timer configuration

According to some further example embodiments of the present disclosure, to improve the DRX solution in the first retransmission scheme, the second device 120 can specifically configure different timers (or timer values) for different retransmission schemes, and then the first device 110 can choose a proper timer (or timer value) to use based on which retransmission scheme is configured. Fig. 6 shows a signaling flow 600 for data retransmission according to these example embodiments. For the purpose of discussion, the signaling flow 600 will be described with reference to Fig. 1. The signaling flow 600 may involve a first device 110 and a second device 120 as illustrated in Fig. 1. In some example embodiments, the signaling flow 600 may be particularly beneficial in the scenario where a RTT between the first and

second devices

110, 120 may be relatively large. For example, the signaling flow 600 may involve the first device 110-1 and the second device 120-1 in the NTN network as illustrated in Fig. 1. It would be appreciated that the signaling flow 600 may also be implemented in any other communication networks.

In the signaling flow 600, the second device 120 transmits 605 and the first device 110 receives 610 a first configuration for a first timer for the first retransmission scheme. The second device 120 also transmits 615 and the first device 110 receives 620 a second configuration for a second timer for the second retransmission scheme. As mentioned previously, the second retransmission scheme is different from the second retransmission scheme. For example, the second retransmission scheme may be a HARQ-enabled retransmission scheme with feedback required, such as the legacy HARQ-enabled retransmission scheme while the first retransmission scheme may be a HARQ-disabled retransmission scheme.

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

The first device 110 can schedule the same first device 110 with different (re) transmission schemes as mentioned above. The first device 110 may use control information to indicate which retransmission scheme is used. Specifically, the second device 120 transmits 625 and the first device 110 receives 630 control information indicating that the first retransmission scheme is to be applied for transmission of data between the first and

second devices

110, 120. The control information indicating the first transmission scheme may be transmitted in a similar way as discussed above with reference to Fig. 2.

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

The second configuration may indicate a second value for the second timer. The first configuration is used to determine the first value for the first timer. In some example embodiments, the first configuration may directly indicate the first value for the first timer. In this case, the first device 110 may directly set the first value for the first timer based on the first configuration. In some example embodiments, the first configuration may indicate a scaling factor for the first timer. The first device 110 may determine the first value for the first timer based on the scaling factor and the second value. For example, the first value may 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 may be determined based on the scaling factor and the second value in any other manners.

According to the example embodiments as discussed with reference to Fig. 6, the second device 120 can specifically design the timer for the first retransmission scheme which does not require feedback to a transmission, for example, by extending a timer or shortening another timer so as to balance the power consumption and the scheduling/transmission flexibility. In addition, by transmitting the first and second configuration via higher layer signalling instead of a physical layer signalling such as DCI, the signalling overhead between the first device 110 and the second device 120 can be reduced.

In some example embodiments, the second device 120 may configure an inactivity timer for DRX for the first retransmission scheme and the second retransmission scheme respectively via a first configuration and a second configuration. A value of the inactivity timer for the first retransmission scheme may 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 may configure a RTT timer for DRX for the first retransmission scheme and the second retransmission scheme respectively via a first configuration and a second configuration, and a value of the RTT timer for the first retransmission scheme may be specifically determined based on the first configuration or based on both the first configuration and the second configuration by the first device 110.

DL and UL (re) transmission based on specific inactivity timer configuration

Fig. 7 and Fig. 8 illustrates signaling flows 700 and 800 in DL (re) transmission and UL (re) transmission where a value of an inactivity timer for the first retransmission scheme is specifically configured, respectively.

In the signaling flows 700 and 800, the first configuration for the first timer (i.e., a first inactivity timer) for the first retransmission scheme and the second configuration for the second timer (i.e., a second inactivity timer) for the second retransmission scheme have been transmitted by the second device 120 to the first device 110. The first or second inactivity timer may also be referred to as drx_inactivityTimer in the 3GPP-based communication system.

The first value of the first timer indicates a duration after receipt of control information from the second device 120 scheduling a new transmission between the first and

second devices

110, 120 for the first retransmission scheme. The second value of the second timer indicates (referred to as a “second value” for convenience of discussion) a duration after receipt of control information from the second device 120 scheduling a new transmission between the first and

second devices

110, 120 for the second retransmission scheme. The second configuration may indicate the second value for the second timer. The first configuration is used to determine the first value for the first timer, and may indicate the first value directly or indicate a scaling factor for determining the first timer, as mentioned above.

If the first configuration for the first timer is transmitted in RRC signaling, a new parameter may be included in DRX-Config IE to indicate this configuration. The DRX-Config IE with the new parameter introduced to indicate the first value for the first timer may be as follows. In this example, the first configuration for the inactivity timer for blind retransmission and the second configuration for the inactivity timer for HARQ-based retransmission are shown as drx-InactivityTimer_blindretransmission and drx-InactivityTimer respectively.

DRX-Config information element

Similarly, the first configuration may indicate a scaling factor, and the DRX-Config IE may also be added with a new parameter to indicate the scaling factor. It would be appreciated that the first configuration listed in the above IE is merely for purpose of illustration without suggesting any limitation to the scope of the present disclosure.

Reference is first made to Fig. 7. In operations of DRX, the second device 120 transmits 705 and the first device 110 receives 710 DCI indicating that the first retransmission scheme is to be applied. However, it should be appreciated that in some example embodiments, the first retransmission scheme may be configured via other signaling, e.g., RRC. In this example, the DCI indicates the first retransmission scheme to be applied. The DCI may also indicate a new transmission of DL data. Upon receipt of the DCI, the first device 110 starts 715 the first timer (i.e., the inactivity timer) with the first value in response to determining that the first retransmission scheme is to be applied. The first timer started here is for monitoring 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.

In some example embodiments, the first value may be configured to be larger than the second value. As such, the first timer is extended and the first device 110 may have an extended duration to stay in the active status. The first device 110 may keep in the active status until expiry of the first timer. In some example embodiments where the inactivity timer is specifically configured, the RTT timer such as drx-HARQ-RTT-TimerDL will not be started as no feedback to (re) transmission is required for the first retransmission scheme. In some example embodiments, the retransmission timer such as drx-RetransmissionTimerDL will not be triggered if no specific configuration for the start of the retransmission timer is provided.

The second device 120 transmits 720 and the first device 110 receives 725 DL data as scheduled in the DCI transmitted at 705. With the first device 110 staying in the active status, the second device 120 decides to schedule a retransmission of the DL data and transmits 730 further DCI to the first device 110. Since the first timer is still running and the first device 110 is still in the active status, the first device 110 receives 735 the DCI. The second device 120 transmits 740 and the first device 110 receives 745 a retransmission of DL data as scheduled in the further DCI transmitted at 730. Accordingly, the extended value for the first timer allows the first device 110 to receive following DCI and DL data.

In some example embodiments, the first device 110 may keep in the active status for monitoring further control information until expiry of the first timer or until detection of further control information from the second device 120 for scheduling a new transmission. In the case where further control information for scheduling a new transmission (the first transmission of new data) is detected from the second device 120, the first device 110 may restart a further timer (i.e., a further inactivity timer) . If the further control information also indicates the first retransmission scheme to be applied for a retransmission of the new data, a value of the further timer may be set similarly as discussed above.

Fig. 8 illustrates a signaling flow 800 in UL (re) transmission between the first and

second devices

110, 120 where a value of an inactivity timer for the first retransmission scheme is specifically configured. In the example of Fig. 8, the first device 110 operates in a DRX mode. In the signaling flow 800,

operations

805, 810, 815, 820, 825, 830, 835, 840, 845 are similar to

operations

705, 710, 715, 720, 725, 730, 735, 740, 745 in the signaling flow 700. The differences are that the first device 110 starts the first timer for UL (re) transmission, and the first device 110 transmits UL data for the second device 120 to receive at 820, 825 and 840, 845.

DL and UL (re) transmission based on specific RTT timer configuration

Fig. 9 and Fig. 10 illustrates signaling flows 900 and 1000 in DL (re) transmission and UL (re) transmission where a value of a RTT timer for the first retransmission scheme is specifically configured, respectively.

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

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

The first configuration for a RTT timer may be transmitted in RRC signaling, and a new parameter may be included in DRX-Config IE to indicate this configuration. The DRX-Config IE with the new parameter introduced to indicate the first value for the first timer or the scaling factor in a similar way for the configuration for an inactivity timer as discussed above.

In the example embodiments where the RTT timer for the first retransmission scheme is specifically configured, during DRX, other DRX timers such as an inactivity timer and a retransmission timer may also be enabled. As compared with the second transmission scheme, the RTT timer is optimized.

In the signaling flow 900, the second device 120 transmits 905 and the first device 110 receives 910 a control signaling (e.g., a DCI) indicating 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 may also indicate that a new transmission of new data is scheduled for the first retransmission scheme, the first device 110 may start or restart an inactivity timer, such as drx_inactivityTimer in the 3GPP-based communication system. The second device 120 transmits 915 and the first device 110 receives 920 the DL data according to the DL assignment indicated in the DCI.

After the receipt of the DL data, the first device 110 starts 925 the first timer (i.e., the RTT timer for DL (re) transmission) . In some example embodiments, the first value may be configured to be smaller than the second value. As during the RTT timer, the first device 110 is not forced to be in the active status. Whether the first device 110 is active during running of the RTT timer may further depend on whether other timers still require the first device 110 to stay active. By configuring the RTT timer with a smaller value, the first device 110 may have a higher probability to monitor and successfully receive further DCI from the second device 120. The first timer started here is for monitoring 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.

After receipt of the DL data, the first device 110 may further stops a retransmission timer (such as drx-RetransmissionTimerDL) if any. Depending on the first value, the first timer (i.e., the RTT timer) expires 930. In some example embodiments, upon expiry of the RTT timer, the first device 110 may restart a retransmission timer (such as drx-RetransmissionTimerDL) . The first device 110 may then be in an active status and receives 940 further DCI transmitted 935 from the second device 120. The further DCI also indicates the first retransmission scheme. Thus, after the first device receives 950 a retransmission of DL data transmitted 945 from the second device 120, the second device 120 restarts 955 a RTT timer.

Fig. 10 illustrates a signaling flow 1000 in UL (re) transmission between the first and

second devices

110, 120 where a value of a RTT timer for the first retransmission scheme is specifically configured. In the example of Fig. 10, the first device 110 operates in a DRX mode. In the signaling flow 1000,

operations

1005, 1010, 1015, 1020, 1025, 1030, 1035, 1040, 1045 are similar to

operations

905, 910, 915, 920, 925, 930, 935, 940, 945 in the signaling flow 900. The differences are that the first device 110 transmits UL data for the second device 120 to receive and the first device 110 starts the first timer for UL (re) transmission (such as drx-HARQ-RTT-TimerUL) at 1015, 1020, 1025 and 1045, 1050, and 1055.

Example methods implemented at respective devices

Fig. 11 shows a flowchart of an example method 1100 implemented at a first device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1100 will be described from the perspective of the first device 110 with reference to Fig. 1.

At block 1110, the first device 110 receives, from a second device 120, control information indicating a first retransmission scheme to be applied for transmission of data between the first and

second devices

110, 120, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data. At block 1120, the first device 110 receives, from the second device 120, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing. At block 1130, the first device 110 determines, based on the retransmission timing, timing for monitoring further control information from the second device 120 for scheduling the retransmission.

The method 1100 proposes the DRX configuration for blind retransmission with dynamic timing for entering an active status. With this solution, the second device 120 can schedule the retransmission with flexibility and the first device 110 can not only receive the control information timely but also optimize the power saving through the indication of possible retransmission timing from the second device 120.

In some example embodiments, the timing information received at block 1120 may indicate a time interval during which the first device may be in an inactive status, and at block 1130, the first device 110 may determine to start a retransmission timer and enter the active status upon ending of the time interval. 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 may keep in the active status for monitoring the further control information until expiry of the retransmission timer or until detection of the further control information.

In some example embodiments, in accordance with receipt of the control information indicating the first retransmission scheme to be applied, the first device 110 may set a value of a RTT timer to be zero. As an alternative, in accordance with receipt of the control information indicating the first retransmission scheme to be applied, the first device 110 may disable the RTT timer. The RTT timer indicates a minimum duration before a DL assignment or an UL grant for HARQ-based retransmission is expected.

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

In some embodiments, a set of candidate values indicate a list of timings for transmission of feedback may be sent to the first device if a second retransmission scheme is configured, which can simplify the configured parameters needed. In some example embodiments, the first device 110 may 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 may be carried to the first device by reusing a signaling which is used to indicate the list of timings for transmission of feedback for a second retransmission scheme. The timing information received at block 1120 may indicate one of the candidate values, for example, via a physical layer downlink control channel.

Fig. 12 shows a flowchart of an example method 1200 implemented at a first device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of the first device 110 with reference to Fig. 1.

At block 1210, the first device 110 receives, from a second device 120, a first configuration for a first timer for a first retransmission scheme. At block 1220, the first device 110 receives, from the second device 120, a second configuration for a second timer for a second retransmission scheme different from the first retransmission scheme. At block 1230, the first device 110 sets, in accordance with a determination that the first retransmission scheme is to be applied for transmission of data between the first and

second devices

110, 120, a first value for the first timer based on the first configuration or both the first configuration and the second configuration. The first retransmission scheme may require a retransmission of the data to be performed independent of feedback to a previous transmission of the data.

This method also gives the solution of DRX supporting blind retransmission based on a retransmission scheme-specific timer configuration. With this solution, the first device 110 may only choose a proper timer specific to a retransmission scheme (which may be an extended timer (such as an inactivity timer) or a shorten timer (such as a RTT timer) ) based on configuration of the retransmission scheme (e.g., a blind retransmission scheme) so as to achieve the power saving.

In some example embodiments, the first value of the first timer may indicate a duration after receipt of control information from the second device 120 scheduling a new transmission between the first and

second devices

110, 120 for the first retransmission scheme; that is, the first timer is an inactivity timer for the first retransmission scheme. The second timer may indicate the duration after receipt of control information from the second device 120 scheduling a new transmission between the first and

second devices

110, 120 for the second retransmission scheme; that is, the second timer is an inactivity timer for the second retransmission scheme. In these example embodiments, the first device 110 may start the first timer after receipt of the control information and then keep in an active status until expiry of the first timer or until detection of further control information from the second device for scheduling a new transmission.

In some example embodiments, the first timer may indicate a minimum duration before a DL assignment or an UL grant for a retransmission is expected for the first retransmission scheme; that is, the first timer is a RTT timer for the first retransmission scheme. The second timer may indicate a minimum duration before a DL assignment or an UL grant for a retransmission is expected for the second retransmission scheme; that is, the first timer is a RTT timer for the second retransmission scheme. The first device 110 may start the first timer after receipt of transmission of the data from the second device 120 if DL (re) transmission is performed. In the case where UL (re) transmission is performed, the first device 110 may start the first timer after transmission of the data to the second device 120.

In some example embodiments, in accordance with a determination that the first configuration indicates the first value for the first timer, the first device 110 may set directly 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 may set the first value for the first timer based on the scaling factor and the second value for the second retransmission scheme, for example, by determining the first value based on their product or their sum.

Fig. 13 shows a flowchart of an example method 1300 implemented at a second device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of the second device 120 with reference to Fig. 1.

At block 1310, the second device 120 transmits, to a first device 110, control information indicating a first retransmission scheme to be applied for transmission of data between the first and

second devices

110, 120. The first retransmission scheme requires a retransmission of the data to be performed independent of feedback to a previous transmission of the data. At block 1320, the second device 120 transmits, to the first device 110, timing information specific to the first retransmission scheme. The timing information indicates retransmission timing, to configure timing for the first device 110 to enter an active status for monitoring further control information from the second device 120 for scheduling the retransmission. In some example embodiments, the second device 120 may transmit the timing information via a physical layer DL control channel.

In some example embodiments, the retransmission timing may include a time interval during which the first device 110 is in an inactive status and ending of which triggers start of a retransmission timer at the first device 110. The retransmission timer may indicate a maximum duration until a DL retransmission or an UL grant for an UL retransmission is received by the first device 110.

Fig. 14 shows a flowchart of an example method 1400 implemented at a second device in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of the second device 120 with reference to Fig. 1.

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

second devices

110, 120.

The first configuration or a combination of the first configuration and the second configuration may be used by the first device 110 to calculate a first value of the first timer for the first retransmission scheme. By transmitting a different first configuration and/or a different second configuration to the first device 110, the second device 120 may control the value of the first timer for the first retransmission scheme. Typically, the first and

second devices

110, 120 may apply the same method based on the first configuration or a combination of the first configuration and the second configuration to determine the first value of the first timer.

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

Example apparatuses

In some example embodiments, a first apparatus capable of performing any of the method 1100 (for example, the first device 110) may comprise means for performing the respective operations of the method 1100. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first device 110.

In some example embodiments, the first apparatus comprises means for receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing; and determining, based on the retransmission timing, timing for monitoring further control information from the second apparatus for scheduling the retransmission.

In some example embodiments, the retransmission timing includes a time interval during which the first apparatus may be in inactive status, and the means for determining the timing comprises means for determining to start a retransmission timer and enter an active status upon ending 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 keeping in the active status for monitoring the further control information until expiry of the retransmission timer or until detection of the further control information.

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

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.

In some example embodiments, the means for receiving the timing information comprises means for detecting a field of the physical layer downlink control channel. The field may indicate a feedback timing indicator if a second retransmission scheme is configured and indicate the timing information if the first retransmission scheme is configured. That is, the field may have different meanings for different retransmission schemes. Alternatively, the field may be dedicatedly used to indicate the timing information for the first retransmission scheme.

In some example embodiments, the control information may indicate the retransmission scheme implicitly or explicitly. For example the control information may include an indication for enabling/disabling hybrid automatic repeat request feedback and/or an indication for a retransmission scheme, to indicate the first retransmission scheme.

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

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

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 computer program code configured to, with the at least one processor, cause the performance of the first apparatus.

In some example embodiments, a first apparatus capable of performing any of the method 1200 (for example, the first device 110) may comprise means for performing the respective operations of the method 1200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first device 110.

In some example embodiments, the first apparatus comprises means for receiving from a second apparatus, a first configuration for a first timer for a first retransmission scheme; receiving, from the second apparatus, a second configuration for 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 transmission of data between the first and second apparatuses, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.

In some example embodiments, the first retransmission scheme requires a retransmission of the data to be performed independent of feedback to a previous transmission of the data.

In some example embodiments, the first value of the first timer indicates a duration after receipt of control information from the second apparatus scheduling a new transmission between the first and second apparatuses for the first retransmission scheme, and the second timer indicates the duration for the second retransmission scheme. The first apparatus further comprises means for starting the first timer after receipt of the control information, and keeping in an active status until expiry of the first timer or until detection of further control information from the second device for scheduling a new transmission.

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

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

In some example embodiments, the first apparatus further comprises means for performing other steps in some example embodiments 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 computer program code configured to, with the at least one processor, cause the performance of the first apparatus.

In some example embodiments, a second apparatus capable of performing any of the method 1300 (for example, the second device 120) may comprise means for performing the respective operations of the method 1300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second device 120.

In some example embodiments, the second apparatus comprises means for transmitting, to a first apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent 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 retransmission timing, to configure timing for the first apparatus to monitor further control information from the second apparatus for scheduling the retransmission.

In some example embodiments, the retransmission timing includes a time interval during which the first apparatus is in an inactive status and ending of which triggers start of a retransmission timer at the first apparatus, the retransmission timer indicating a maximum duration until a downlink retransmission or an uplink grant for an uplink retransmission is received by the first apparatus.

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.

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

In some example embodiments, a second apparatus capable of performing any of the method 1400 (for example, the second device 120) may comprise means for performing the respective operations of the method 1400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120.

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

In some example embodiments, the first configuration indicates the first value for the first timer. In some example embodiments, the first configuration indicates a scaling factor for the first timer, the second configuration indicates a second value for the second timer, and the first value being determined based on the scaling factor and the second value.

In some example embodiments, the second apparatus further comprises means for performing other operations in some example embodiments of the method 1400. 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 computer program code configured to, with the at least one processor, cause the performance of the second apparatus.

Example device and computer readable medium

Fig. 15 is a simplified block diagram of a device 1500 that is suitable for implementing example embodiments of the present disclosure. The device 1500 may be provided to implement the communication device, for example the first device 110 or the second device 120 as shown in Fig. 1. As shown, the device 1500 includes one or more processors 1510, one or more memories 1520 coupled to the processor 1510, and one or more communication modules 1540 coupled to the processor 1510.

The communication module 1540 is for bidirectional communications. The communication module 1540 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 1510 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 1520 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1524, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1522 and other volatile memories that will not last in the power-down duration.

A computer program 1530 includes computer executable instructions that are executed by the associated processor 1510. The program 1530 may be stored in the memory, e.g., ROM 1524. The processor 1510 may perform any suitable actions and processing by loading the program 1530 into the RAM 1522.

The example embodiments of the present disclosure may be implemented by means of the program 1530 so that the device 1500 may perform any process of the disclosure as discussed with reference to Figs. 2 to 14. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 1530 may be tangibly contained in a computer readable medium which may be included in the device 1500 (such as in the memory 1520) or other storage devices that are accessible by the device 1500. The device 1500 may load the program 1530 from the computer readable medium to the RAM 1522 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. Fig. 16 shows an example of the computer readable medium 1600 in form of CD or DVD. The computer readable medium has the program 1530 stored thereon.

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

The present disclosure also provides at least one computer program product 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, being executed in a device on a target real or virtual processor, to carry out any of the methods as described above with reference to Figs. 2 to 14. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

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

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

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

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

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

Claims

A first device, 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 and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data;

receive, from the second device, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing; and

determine, based on the retransmission timing, timing for monitoring further control information from the second device for scheduling the retransmission.
The device of claim 1, wherein the retransmission timing includes a time interval during which the first device is in an inactive status, and 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 determine the timing by:

determining to start a retransmission timer and enter an active status upon ending 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

keeping in the active status for monitoring the further control information until expiry of the retransmission timer or until detection of the further control information.
The device of claim 1 or claim 2, 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 receipt of the control information indicating the first retransmission scheme to be applied,

set a value of a round-trip time timer to be 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 hybrid automatic repeat request-based retransmission is expected.
The device of any of claims 1 to 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.
The device of claim 4, 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:

detecting a field of the physical layer downlink control channel, the field indicating a feedback timing indicator if a second retransmission scheme is configured and the timing information if the first retransmission scheme is configured, or the field indicating the timing information for the first retransmission scheme only.
The device of any of claims 1 to 5, wherein the control information includes an indication for enabling/disabling hybrid automatic repeat request feedback and/or an indication for a retransmission scheme, to indicate the first retransmission scheme.
The device of any of claims 1 to 6, 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:

receive a set of candidate values for retransmission timing for the first retransmission scheme from the second device via higher layer signaling, and

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 indicating one of the candidate values via a physical layer downlink control channel.
The device of claim 7, wherein the set of candidate values indicate a list of timings for transmission of feedback if a second retransmission scheme is configured.
A first device, 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, a first configuration for a first timer for a first retransmission scheme;

receive, from the second device, a second configuration for 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 transmission of data between the first and second devices, set a first value for the first timer based on the first configuration or both the first configuration and the second configuration.
The device of claim 9, wherein the first retransmission scheme requires a retransmission of the data to be performed independent of feedback to a previous transmission of the data.
The device of claim 9 or claim 10, wherein the first value of the first timer indicates a duration after receipt of control information from the second device scheduling a new transmission between the first and second devices for the first retransmission scheme, and the second timer indicates the duration for the second retransmission scheme; and

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:

start the first timer after receipt of the control information, and

keep in an active status until expiry of the first timer or until detection of further control information from the second device for scheduling a new transmission.
The device of claim 9 or claim 10, wherein the first timer indicates a minimum duration before a downlink assignment or an uplink grant for a retransmission is expected for the first retransmission scheme, and the second timer indicates the minimum duration for the second retransmission scheme, and

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:

start the first timer after receipt of transmission of the data from the second device; or

start the first timer after transmission of the data to the second device.
The device of any of claims 9 to 12, 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 set the first value for the first timer by:

in accordance with a determination that the first configuration indicates the first value for the first timer, setting the first value for the first timer; and

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, setting the first value for the first timer based on the scaling factor and the second value.
A second device, 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 second device to:

transmit, to a first device, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent 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 retransmission timing, to configure timing for the first device to monitor further control information from the second device for scheduling the retransmission.
The device of claim 14, wherein the retransmission timing includes a time interval during which the first device is in an inactive status and ending of which triggers 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.
The device of claim 14 or claim 15, 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 the timing information via a physical layer downlink control channel.
A second device, 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 second device to:

transmit, to a first device, a first configuration for a first timer of the first device for a first retransmission scheme;

transmit, to the first device, a second configuration for 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 for transmission of data between the first and second devices, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.
The device of claim 17, wherein the first configuration indicates the first value for the first timer, or

wherein the first configuration indicates a scaling factor for the first timer, the second configuration indicates a second value for the second timer, and the first value being determined based on the scaling factor and the second value.
A method comprising:

receiving, at a first device and from a second device, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent 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 retransmission timing; and

determining, based on the retransmission timing, timing for monitoring further control information from the second device for scheduling the retransmission.
The method of claim 19, wherein the retransmission timing includes a time interval during which the first device is in an inactive status, and wherein determining the timing comprises:

determining to start a retransmission timer and enter an active status upon ending 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

keeping in the active status for monitoring the further control information until expiry of the retransmission timer or until detection of the further control information.
The method of claim 19 or claim 20, wherein receiving the timing information comprises:

receiving the timing information via a physical layer downlink control channel.
A method comprising:

receiving, at a first device and from a second device, a first configuration for a first timer for a first retransmission scheme;

receiving, from the second device, a second configuration for 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 transmission of data between the first and second devices, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.
A method comprising:

transmitting, at a second device and to a first device, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second devices, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; and

transmitting, to the first device, timing information specific to the first retransmission scheme via a physical layer downlink control channel, the timing information indicating retransmission timing, to configure timing for the first device to monitor further control information from the second device for scheduling the retransmission.
A method comprising:

transmitting, at a second device and to a first device, a first configuration for a first timer of the first device for a first retransmission scheme;

transmitting, to the first device, a second configuration for 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 transmission of data between the first and second devices, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.
A first apparatus comprising means for:

receiving, from a second apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data;

receiving, from the second apparatus, timing information specific to the first retransmission scheme, the timing information indicating retransmission timing; and

determining, based on the retransmission timing, timing for monitoring further control information from the second apparatus for scheduling the retransmission.
A first apparatus comprising means for:

receiving, from a second apparatus, a first configuration for a first timer for a first retransmission scheme;

receiving, from the second apparatus, a second configuration for 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 transmission of data between the first and second apparatuses, setting a first value for the first timer based on the first configuration or both the first configuration and the second configuration.
A second apparatus comprising means for

transmitting, to a first apparatus, control information indicating a first retransmission scheme to be applied for transmission of data between the first and second apparatuses, the first retransmission scheme requiring a retransmission of the data to be performed independent of feedback to a previous transmission of the data; and

transmitting, to the first apparatus, timing information specific to the first retransmission scheme via a physical layer downlink control channel, the timing information indicating retransmission timing, to configure timing for the first apparatus to monitor further control information from the second apparatus for scheduling the retransmission.
A second apparatus comprising means for

transmitting, to a first apparatus, a first configuration for a first timer of the first apparatus for a first retransmission scheme;

transmitting, to the first apparatus, a second configuration for 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 that the first retransmission scheme is to be applied for transmission of data between the first and second apparatuses, wherein the first configuration or a combination of the first configuration and the second configuration determines a first value for the first timer.
A computer readable medium comprising program instructions for causing an apparatus to perform at least the method of claims 19-21, the method of claim 22, the method of claim 23, or the method of claim 24.