Contention resolution for non-terrestrial networks

Abstract

The embodiment of the invention relates to a device, method and equipment for contention resolution of NTN and a computer readable storage medium. The method comprises: determining whether an event has occurred, the event comprising: a transmission of a message associated with a random access procedure has been performed after a previous transmission of the message, or an uplink grant associated with the message has been received after the previous transmission; and determining a contention resolution failure based on the determination of the event upon expiration of a timer for monitoring a downlink control channel between the second device and the first device. In this manner, the problem of false declaration contention resolution failure upon expiration of a contention resolution timer may be solved, and network blind scheduling of MSG3 retransmission may be implemented.

Description

[0001] This divisional application is a divisional application of Chinese patent application NO.202180104001.9, filed on November 8, 2021, with the invention name “Content Resolution for Non-terrestrial Networks”. Technical Field

[0002] Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to apparatus, methods, devices, and computer-readable storage media for contention resolution of non-terrestrial networks (NTNs). Background Art

[0003] The 3rd Generation Partnership Project (3GPP) has launched New Radio (NR) on NTN WI in Release 17. To avoid wasted power consumption of the User Equipment (UE), the timer for Physical Downlink Control Channel (PDCCH) monitoring may not be started immediately after uplink (UL) transmission initiation because the round trip time (RTT) may be long for NTN. Summary of the invention

[0004] In general, example embodiments of the present disclosure provide a solution for contention resolution for NTNs.

[0005] In a first aspect, a first device is provided. The first device comprises: at least one processor; and at least one memory, the at least one memory comprising computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to at least: determine whether an event has occurred, the event comprising: transmission of a message associated with a random access procedure has been performed after a previous transmission of the message, or an uplink grant associated with the message has been received after the previous transmission; and determine contention resolution failure based on the determination of the event when a timer for monitoring a downlink control channel between a second device and the first device expires.

[0006] In a second aspect, a method is provided. The method includes determining whether an event has occurred, the event including: transmission of a message associated with a random access procedure has been performed after a previous transmission of the message, or an uplink grant associated with the message has been received after the previous transmission; and determining a contention resolution failure based on the determination of the event when a timer for monitoring a downlink control channel between a second device and a first device expires.

[0007] In a third aspect, a device is provided, comprising: a device for determining whether an event has occurred, the event comprising: transmission of the message having been performed after a previous transmission of the message associated with a random access procedure, or an uplink grant associated with the message having been received after the previous transmission; and a device for determining a contention resolution failure based on the determination of the event when a timer for monitoring a downlink control channel between a second device and a first device expires.

[0008] In a fourth aspect, there is provided a computer readable medium having stored thereon a computer program which, when executed by at least one processor of an apparatus, causes the apparatus to perform the method according to the second aspect.

[0009] Other features and advantages of the embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The embodiments of the present disclosure are presented by way of example and their advantages are explained in more detail below with reference to the accompanying drawings, in which

[0011] Figure 1 An example environment is shown in which example embodiments of the present disclosure may be implemented;

[0012] Figure 2 shows a time diagram illustrating a process for contention resolution for NTN according to some example embodiments of the present disclosure;

[0013] Figure 3 A flowchart illustrating an example method for contention resolution for NTN according to some example embodiments of the present disclosure;

[0014] Figure 4 shows a simplified block diagram of an apparatus suitable for implementing an example embodiment of the present disclosure; and

[0015] Figure 5 A block diagram of an example computer-readable medium is shown according to some embodiments of the present disclosure.

[0016] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0017] The principle of the present disclosure will now be described with reference to some example embodiments. It will be understood that these embodiments are described only for illustrative purposes and are helpful for those skilled in the art to understand and implement the present disclosure, without implying any limitation on the scope of the present disclosure. The disclosure described herein can be realized in various ways except for the following described methods.

[0018] 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 skill in the art to which this disclosure belongs.

[0019] References to "one embodiment," "an embodiment," "an example embodiment," and the like in this disclosure indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment may include the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, it should be considered that it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0020] It should be understood that although the terms "first" and "second" etc. may be used herein to describe various elements. However, these elements should not be limited to these terms. These terms are only used to distinguish the functions of the various elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

[0021] The terms used herein are used only for the purpose of describing specific embodiments and are not intended to be limiting of the exemplary embodiments. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "said" are intended to include the plural forms as well. It should also be understood that when used herein, the terms "comprises", "comprising", "has", "having", "includes", and / or "including" specify the presence of declared features, elements, and / or parts, etc., but do not exclude the presence or addition of one or more other features, elements, parts, and / or combinations thereof.

[0022] As used in this application, the term "circuitry" may refer to one, more, or all of the following:

[0023] (a) hardware circuit implementations only (such as implementations in analog and / or digital circuitry only), and

[0024] (b) a combination of hardware circuitry and software such as (where applicable):

[0025] (i) a combination of analog and / or digital hardware circuitry and software / firmware, and

[0026] (ii) any portion of a hardware processor with software (including a digital signal processor), software and memory that work together to enable a device such as a mobile phone or server to perform various functions, and

[0027] (c) Hardware circuits and / or processors, such as a microprocessor or portion of a microprocessor, that require software (e.g., firmware) to operate, but the software may not be present when not required for operation.

[0028] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors), or a hardware circuit or processor and a portion of its (or their) accompanying software and / or firmware. For example, and where applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit of a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0029] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as a fifth generation (5G) system, long term evolution (LTE), advanced LTE (LTE-A), wideband code division multiple access (WCDMA), high speed packet access (HSPA), narrowband Internet of Things (NB-IoT), etc. In addition, the communication between the terminal device and the network device in the communication network can be performed according to any suitable communication protocol of any generation, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) new radio (NR) communication protocol and / or any other protocol currently known or developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there will certainly be future types of communication technologies and systems that can embody the present disclosure. It should not be considered that the scope of the present disclosure is limited to the aforementioned system.

[0030] 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 from the network. A network device may refer to a base station (BS) or an access point (AP), such as a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR next-generation NodeB (gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a repeater, a low-power node, such as a femto node, a micro node, etc., depending on the terminology and technology applied. The RAN separation architecture includes a gNB-CU (centralized unit, hosting RRC, SDAP and PDCP) that controls multiple gNB-DUs (distributed units, hosting RLC, MAC and PHY). A relay node may correspond to the DU portion of an IAB node.

[0031] The term "terminal device" refers to any terminal device that can perform wireless communication. As an example and not limitation, the terminal device may also be referred to as a communication device, a 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 is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device (such as a digital camera), a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded equipment (LEE), a laptop mounted equipment (LME), a USB dongle, a smart device, a wireless customer terminal equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., a robot and / or other wireless device operating in the context of an industrial and / or automated processing chain), a consumer electronic device, a device running on a commercial and / or industrial wireless network, etc. The terminal device may also correspond to the mobile terminal (MT) part of an integrated access and backhaul (IAB) node (also called a relay node).In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0032] Although in various example embodiments, the functions described herein may be performed in fixed and / or wireless network nodes, in other example embodiments, the functions may be implemented in a user equipment device (such as a cell phone or a tablet computer or a laptop computer or a desktop computer or a mobile IoT device or a fixed IoT device). The user equipment device may, for example, be equipped with corresponding capabilities as described in conjunction with fixed and / or wireless network nodes as appropriate. The user equipment device may be a user equipment and / or a control device configured to control the user equipment when installed in the user equipment, such as a chipset or a processor. Examples of such functions include boot server functions and / or home subscriber servers, which may be implemented in a user equipment device by providing the user equipment device with software configured to cause the user equipment device to execute from the perspective of these functions / nodes.

[0033] Figure 1 1 shows an example communication network 100 in which embodiments of the present disclosure may be implemented. Figure 1 As shown, the communication network 100 may include a terminal device 110 (hereinafter may also be referred to as UE 110 or first device 110). The communication network 100 may also include a network device 120 (hereinafter may also be referred to as gNB 120 or second device 120). In the case where the communication network 100 refers to NTN, the network device 120 or a segment of the network device 120 may be considered to be located in a satellite. The network device 120 may manage a cell 102. The terminal device 110 and the network device 120 may communicate with each other within the coverage area of ​​the cell 102.

[0034] will understand, Figure 1 The number of network devices and terminal devices shown is for illustration purposes only and does not imply any limitation. Communication network 100 may include any suitable number of network devices and terminal devices.

[0035] Currently, it has been agreed to introduce the RTT between the UE and the gNB (UE-gNB RTT) into the activation of multiple timers of the NTN, so that the UE only needs to start monitoring the PDCCH after the RTT.

[0036] Furthermore, it has been agreed that for Message 3 (MSG3) transmitted on the NTN, the ra-ContentionResolutionTimer is started and restarted at each Hybrid Automatic Repeat Request (HARQ) retransmission, both occurring in the first symbol after the end of MSG3 transmission plus the UE-gNB RTT estimated by the UE.

[0037] Due to the introduction of UE-gNB RTT, after MSG3 retransmission, the contention resolution timer started by the previous MSG3 transmission (retransmission) may expire before it is restarted after RTT, which may cause an unexpected declaration of contention resolution failure. The UE may then perform a retry through preamble transmission or declare RA failure if the maximum number of attempts is reached. In this case, the UE may stop monitoring the PDCCH after the contention resolution timer expires, and thus information transmitted from the gNB before another contention resolution timer is started may be lost.

[0038] The solution of the present disclosure proposes a contention resolution failure determination mechanism. In the solution, the UE can determine whether an event has occurred, the event including that the transmission of the message associated with the random access procedure has been performed after the previous transmission of the message, or that an uplink grant associated with the message has been received after the previous transmission. Then, the UE can determine the contention resolution failure based on the determination of the event at the time point when the timer for monitoring the downlink control channel between the second device and the first device expires. In this way, the problem of falsely declaring a contention resolution failure when the contention resolution timer expires can be solved, and network blind scheduling of MSG3 retransmission can be achieved.

[0039] The following will refer to Figure 2 Detailed description of the principles and implementations of the present disclosure, the figure shows a time diagram illustrating a process 200 for contention resolution of NTN according to some example embodiments of the present disclosure. For the purpose of discussion, reference will be made to Figure 1 Describe process 200. Process 200 may involve UE 110 and gNB 120.

[0040] Reference now Figure 2 . At time point T1, UE 110 may transmit MSG3 during the random access process. The transmission of MSG3 at T1 may be an initial transmission or a retransmission of MSG3. As mentioned above, due to the introduction of UE-gNB RTT 210, a contention resolution timer may be started after UE-gNB RTT 210 (i.e., at time point T2). During the duration 220 of the contention resolution timer, UE 110 may monitor the PDCCH for a UL grant from gNB 120. The UL grant may be associated with the MSG3 retransmission.

[0041] The contention resolution timer will expire at time point T5. Before the contention resolution timer expires, UE 110 may determine whether an uplink grant is received after the transmission of MSG3 (i.e., after time point T1), or whether another transmission of MSG3 is performed. In some example embodiments, another transmission of MSG3 may be referred to as a retransmission of MSG3.

[0042] If an uplink grant is received after transmitting MSG3 (e.g., at time point T3), or another transmission of MSG3 is performed, for example, at time point T4, UE 110 can determine that no contention resolution failure has occurred at the time point when the timer expires (i.e., at time point T5), and therefore UE 110 can keep monitoring the PDCCH after the contention resolution timer expires.

[0043] In some example embodiments, if an uplink grant is received after transmission of MSG3 or a retransmission of MSG3 is performed, UE 110 may keep monitoring the PDCCH after expiration of the contention resolution timer. In some example embodiments, UE 110 may monitor the PDCCH during estimated UE-gNB RTT 230 even if the contention resolution timer is not running. In some other example embodiments, UE 110 may monitor the PDCCH only when the contention resolution timer is started or restarted after the UE-gNB RTT.

[0044] In some example embodiments, a new timer may be introduced for potential blind scheduling, which is started upon receipt of a PDCCH for a MSG3 retransmission or after a MSG3 retransmission. UE 110 may also monitor the PDCCH during the duration of the new timer. Unlike the contention resolution timer, expiration of the new timer may not result in a declaration of contention resolution failure. UE 110 may stop monitoring the PDCCH upon expiration of the new timer. With the new timer, the contention resolution timer may be stopped upon receipt of a PDCCH for a MSG3 retransmission or a MSG3 transmission without affecting blind scheduling by gNB 120.

[0045] It should be appreciated that the new timer may be associated with other behaviors for PDCCH monitoring at UE 110 in addition to or after receiving a PDCCH for MSG3 retransmission.

[0046] In some example embodiments, an example representing the possible impact of the proposed mechanism on the specification may be as follows.

[0047] Table 1: Possible impact on the specification

[0048]

[0049] In some example embodiments, another example representing the possible impact of the proposed mechanism on the specification may be as follows.

[0050] Table 2: Possible impact on the specification

[0051]

[0052] In some example embodiments, another example representing the possible impact of the proposed mechanism on the specification may be as follows.

[0053] Table 3: Possible impact on specifications

[0054]

[0055]

[0056] By using the solution of the present disclosure, the problem of falsely declaring contention resolution failure when the contention resolution timer expires can be solved, and network blind scheduling of MSG3 retransmission can be implemented.

[0057] Figure 3 A flow chart of an example method 300 for contention resolution for NTN according to some example embodiments of the present disclosure is shown. Figure 1 The method 300 is implemented at the first device 110 shown. For the purpose of discussion, reference will be made to Figure 1 Method 300 is described.

[0058] At 310, the first device determines whether an event has occurred, the event including having performed transmission of a message associated with a random access procedure after a previous transmission of the message, or having received an uplink grant associated with the message after a previous transmission.

[0059] At 320, the first device determines a contention resolution failure based on a determination of the event when a timer for monitoring a downlink control channel between the second device and the first device expires.

[0060] In some example embodiments, if the first device determines that the event has occurred, the first device may determine that no contention resolution failure has occurred at the point in time when the timer expires.

[0061] In some example embodiments, the first device may keep monitoring the downlink control channel after the timer expires.

[0062] In some example embodiments, if the first device determines that the message has been retransmitted, the first device may keep monitoring the downlink control channel during the round trip time between the first device and the second device before another timer for monitoring the downlink control channel is started.

[0063] In some example implementations, the first device may maintain monitoring the downlink control channel based on another timer associated with one of the receipt of an uplink grant or the retransmission of a message.

[0064] In some example embodiments, the first device may start another timer associated with one of the receipt of an uplink grant or the retransmission of a message, while terminating the timer, and maintain monitoring the downlink control channel for the duration of the other timer.

[0065] In some example embodiments, the message is message 3 of the random access procedure.

[0066] In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

[0067] In some example embodiments, a device capable of performing method 300 (e.g., implemented at UE 110) may include means for performing the respective steps of method 300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit system or a software module.

[0068] In some example embodiments, the apparatus includes: means for determining whether an event has occurred, the event comprising: transmission of a message associated with a random access procedure having been performed after a previous transmission of the message, or an uplink grant associated with the message having been received after the previous transmission; and means for determining a contention resolution failure based on a determination of the event when a timer for monitoring a downlink control channel between a second device and a first device expires.

[0069] Figure 4 400 is a simplified block diagram of an apparatus 400 suitable for implementing an embodiment of the present disclosure. The apparatus 400 may be provided to implement a communication apparatus, such as Figure 1 UE 110 is shown in FIG. As shown in the figure, apparatus 400 includes one or more processors 410, one or more memories 440 coupled to processor 410, and a communication module 440 coupled to processor 410.

[0070] The communication module 440 is used for two-way communication. The communication module 440 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface may represent any interface required to communicate with other network elements. In some example embodiments, the communication module 440 may include at least one antenna.

[0071] Processor 410 may be of any type suitable for use in a local area technology network and may include one or more of the following: as non-limiting examples, a general purpose computer, a special purpose computer, a microprocessor, a digital reference signal processor (DSP), and a processor based on a multi-core processor architecture. Device 400 may have multiple processors, such as application specific integrated circuit chips that are time controlled by a clock that synchronizes a main processor.

[0072] The memory 420 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 424, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic storage devices and / or optical storage devices. Examples of volatile memories include, but are not limited to, random access memory (RAM) 422 and other volatile memories that will not be maintained during a power outage.

[0073] Computer program 430 includes computer executable instructions that are executed by associated processor 410. Program 430 may be stored in ROM 420. Processor 410 may perform any suitable actions and processes by loading program 430 into RAM 420.

[0074] The embodiments of the present disclosure can be implemented with the help of program 430, so that the device 400 can execute the Figures 2 to 3 Any process of the present disclosure discussed. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0075] In some embodiments, the program 430 may be tangibly embodied in a computer-readable medium that may be included in the device 400 (such as in the memory 420) or in other storage devices accessible by the device 400. The device 400 may load the program 430 from the computer-readable medium to the RAM 422 for execution. The computer-readable medium may include any type of tangible non-volatile storage device, such as a ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Figure 5 An example of a computer readable medium 500 is shown in the form of a CD or DVD. The computer readable medium has a program 430 stored thereon.

[0076] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using some other graphical representations, it will be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware, or a controller or other computing device, or a combination thereof, as non-limiting examples.

[0077] The present disclosure also provides at least one computer program product, which is tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as those included in a program module, which are executed in a device on a target real processor or a virtual processor to implement the above-referenced Figure 3 The method 300 is described. In general, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or split between program modules as needed. Machine executable instructions for program modules can be executed in local devices or distributed devices. In distributed devices, program modules can be located in both local storage media and remote storage media.

[0078] The program code for implementing the method 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, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, causes the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0079] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable an apparatus, device or processor to perform various processes and operations as described above. Examples of carriers include reference signals, computer readable media, etc.

[0080] The computer readable medium may be a computer readable reference signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or means, or any suitable combination of the foregoing. More specific examples of computer readable storage media would include: an electrical connection with one or more wires, a portable computer disk, 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0081] In addition, although the operation is described in a specific order, this should not be understood as needing to perform such operation in the specific order shown or in a continuous order or needing to perform all the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be understood as limitations on the scope of the present disclosure, but rather descriptions of features that may be specific to a particular embodiment. Some features described in the context of a separate embodiment also may be realized in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment also may be realized in multiple embodiments individually or in any suitable subcombination.

[0082] Although the disclosure has been described in language specific to structural features and / or method actions, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as example forms of implementing the claims.

Claims

1. A first device, comprising: at least one processor; as well as at least one memory, the at least one memory comprising computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to at least: determining whether a physical downlink control channel (PDCCH) addressed to a temporary cell radio network temporary identifier indicating an uplink grant for a retransmission of a message between a second device and the first device has been received after a random access contention resolution timer for monitoring the PDCCH has been started, wherein the PDCCH is message 3 of a random access procedure; as well as When the random access contention resolution timer expires, based on a determination that the uplink grant for the retransmission of the message 3 has not been received after the random access contention resolution timer was started, the temporary cell radio network temporary identifier is discarded and contention resolution is deemed unsuccessful.

2. The first apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to: Based on a determination that the uplink grant for the retransmission of the message 3 has been received after the random access contention resolution timer is started, it is determined that no contention resolution failure has occurred when the random access contention resolution timer expires.

3. The first apparatus of claim 2, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to: The PDCCH is kept being monitored after the random access contention resolution timer expires.

4. The first apparatus of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first apparatus to: starting another timer associated with receipt of the uplink grant while terminating the random access contention resolution timer; and The PDCCH is kept monitored for the duration of the further timer.

5. The first device of claim 1, wherein the first device comprises a terminal device and the second device comprises a network device.

6. The first device according to any one of claims 1 to 5, wherein the random access contention resolution timer is started in the first symbol after the end of the transmission of the message 3 plus the round trip time RTT between the first device and the second device.

7. The first device according to any one of claims 1 to 6, wherein the message 3 is transmitted over a non-terrestrial network NTN.

8. A method comprising: determining, by the first device, whether the PDCCH has been received after a random access contention resolution timer for monitoring a physical downlink control channel PDCCH addressed to a temporary cell radio network temporary identifier indicating an uplink grant for retransmission of a message between a second device and the first device is started, wherein the PDCCH is message 3 of a random access procedure; as well as When the random access contention resolution timer expires, based on a determination that the uplink grant for the retransmission of the message 3 has not been received after the random access contention resolution timer was started, the temporary cell radio network temporary identifier is discarded and contention resolution is deemed unsuccessful.

9. The method of claim 8, wherein the method comprises: Based on a determination that the uplink grant for the retransmission of the message 3 has been received after the random access contention resolution timer is started, it is determined that no contention resolution failure has occurred when the random access contention resolution timer expires.

10. The method of claim 9, wherein the method comprises: The PDCCH is kept being monitored after the random access contention resolution timer expires.

11. The method of claim 8, wherein the method comprises starting another timer associated with receipt of the uplink grant while terminating the random access contention resolution timer; and The PDCCH is kept monitored for the duration of the further timer.

12. The method of claim 8, wherein the first device comprises a terminal device and the second device comprises a network device.

13. The method according to any one of claims 8 to 12, wherein the random access contention resolution timer is started in the first symbol after the end of the transmission of the message 3 plus the round trip time (RTT) between the first device and the second device.

14. The method according to any one of claims 8 to 13, wherein the message 3 is transmitted over a non-terrestrial network NTN.

15. An apparatus comprising: means for determining, by the first device, whether the PDCCH has been received after a random access contention resolution timer for monitoring a physical downlink control channel (PDCCH) addressed to a temporary cell radio network temporary identifier indicating an uplink grant for retransmission of a message between a second device and the first device is started, wherein the PDCCH is message 3 of a random access procedure; as well as When the random access contention resolution timer expires, based on a determination that the uplink grant for the retransmission of the message 3 has not been received after the random access contention resolution timer was started, the temporary cell radio network temporary identifier is discarded and contention resolution is deemed unsuccessful.

16. A non-transitory computer-readable medium comprising program instructions for causing a device to at least perform the method of any one of claims 8 to 14.

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