Uplink synchronization loss collision rule for half-duplex devices in non-terrestrial networks

Abstract

The present disclosure relates to an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: Receiving, from a network, a first information to obtain an uplink synchronization Obtaining, in response to the receiving the first information, the uplink synchronization. Performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending, to the network, from transmitting the one or more pending uplink transmissions.

Description

[0001] UPLINK SYNCHRONIZATION LOSS COLLISION RULE FOR HALF¬

[0002] DUPLEX DEVICES IN NON-TERRESTRIAL NETWORKS

[0003] TECHNICAL FIELD

[0004] Various example embodiments described herein relate to the field of wireless communications.

[0005] BACKGROUND

[0006] Wireless communication with half-duplex user devices may pose challenges in non-terrestrial networks (NTN). A round-trip time between a device and a base station may be long and with large variation in NTN, e.g., a differential delay in a cell deployed by a low Earth orbit (LEO) satellite at an altitude of 600 kilometers (km) may exceed 3 milliseconds (ms). Such a large uncertainty may make it difficult for the network to determine whether uplink and downlink transmissions collide in a specific user device. When uplink synchronization is lost, the user device may not be able to perform uplink transmissions, but collision rules may however require the user device to prioritize uplink transmissions over a dynamically scheduled information for restoring uplink synchronization. Enabling a new collision rule to handle situations where uplink synchronization is lost may be beneficial.

[0007] SUMMARY

[0008] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0009] Example embodiments of the present disclosure may enable improving data transmission or reception. This benefit may be achieved by the features of the independent claims. Further example embodiments are provided in the dependent claims, the detailed description, and the drawings.

[0010] According to a first aspect, an apparatus is disclosed. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, may cause the apparatus at least to perform: Receiving, from a network, a first information to obtain an uplink synchronization. Obtaining, in response to the receiving the first information, the uplink synchronization. Performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0011] According to an example embodiment of the first aspect, the apparatus may be caused to perform the refraining from transmitting in response to the one or more pending uplink transmissions at least partially overlapping with the downlink monitoring for the second information.

[0012] According to an example embodiment of the first aspect, the apparatus may be further caused to perform: Receiving, from the network, the second information. Restoring, in response to the receiving the second information, the uplink synchronization. Transmitting, in response to the restoring the uplink synchronization, to the network, the one or more pending uplink transmission.

[0013] According to an example embodiment of the first aspect, the first information and the second information may comprise satellite assistance information.

[0014] According to an example embodiment of the first aspect, the apparatus may be caused to perform the receiving the first information by receiving a system information block, and the receiving the second information by receiving a different version of the system information block.

[0015] According to an example embodiment of the first aspect, the system information block may be a SIB 19.

[0016] According to an example embodiment of the first aspect, the loss of the uplink synchronization may comprise a validity timer, based on the first information, expiring.

[0017] According to an example embodiment of the first aspect, the validity timer may be a validity timer for non-terrestrial network uplink synchronization.

[0018] According to an example embodiment of the first aspect, the first information may comprise a first satellite assistance information and the second information may comprise a second satellite assistance information.

[0019] According to an example embodiment of the first aspect, the first satellite assistance information may comprise a first validity duration and a first epoch time, and the second satellite assistance information may comprise a second validity duration and a second epoch time. According to an example embodiment of the first aspect, the apparatus may be caused to perform the receiving the second information by receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the second information.

[0020] According to an example embodiment of the first aspect, an uplink transmission within the one or more uplink transmissions may be a semi-statically configured uplink transmission or a dynamically scheduled uplink transmission.

[0021] According to a second aspect, an apparatus is provided. The apparatus may comprise: means for receiving, from a network, a first information to obtain an uplink synchronization; means for obtaining, in response to the receiving the first information, the uplink synchronization; and means for performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization, and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0022] According to a third aspect, a method is disclosed. The method may be computer- implemented. The method may comprise: Receiving, from a network, a first information to obtain an uplink synchronization. Obtaining, in response to the receiving the first information, the uplink synchronization. Performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0023] According to a fourth aspect, a computer-readable medium is disclosed. The computer-readable medium may comprise program instructions for causing an apparatus to perform at least the following: Receiving, from a network, a first information to obtain an uplink synchronization. Obtaining, in response to the receiving the first information, the uplink synchronization. Performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions. According to a fifth aspect, a computer program is disclosed. The computer program may comprise instructions for causing an apparatus to perform at least the following: Receiving, from a network, a first information to obtain an uplink synchronization. Obtaining, in response to the receiving the first information, the uplink synchronization. Performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0024] According to a sixth aspect, an apparatus is disclosed. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, may cause the apparatus at least to perform: Receiving, from a network, a first system information comprising a first satellite assistance information and a first indication of a timer. Starting, in response to the receiving the first system information, the timer based on the first satellite assistance information. Performing, in response to the timer expiring, the following: downlink monitoring for receiving a second system information comprising a second satellite assistance information and a second indication of the timer; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0025] According to an example embodiment of the sixth aspect, the apparatus may be caused to perform the refraining from transmitting in response to the one or more pending uplink transmissions at least partially overlapping with the downlink monitoring for the second system information.

[0026] According to an example embodiment of the sixth aspect, the apparatus may be further caused to perform: Receiving, from the network, the second system information. Restarting, in response to the receiving the second system information, the timer based on the second satellite assistance information. Transmitting, in response to the restarting the timer, to the network, the one or more pending uplink transmission.

[0027] According to an example embodiment of the sixth aspect, the timer may be a validity timer.

[0028] According to an example embodiment of the sixth aspect, the validity timer may be a validity timer for non-terrestrial network uplink synchronization. According to an example embodiment of the sixth aspect, the validity timer may be a T430.

[0029] According to an example embodiment of the sixth aspect, the first satellite assistance information may comprise a first validity duration and a first epoch time, and the second satellite assistance information may comprise a second validity duration and a second epoch time.

[0030] According to an example embodiment of the sixth aspect, the apparatus may be caused to perform the receiving the first system information by receiving a system information block, and the receiving the second system information by receiving a different version of the system information block.

[0031] According to an example embodiment of the sixth aspect, the system information block may be a SIB 19.

[0032] According to an example embodiment of the sixth aspect, the apparatus may be caused to perform the receiving the second system information by receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the second information.

[0033] According to an example embodiment of the sixth aspect, an uplink transmission within the one or more uplink transmissions may be a semi-statically configured uplink transmission or a dynamically scheduled uplink transmission.

[0034] According to a seventh aspect, an apparatus is provided. The apparatus may comprise: means for receiving, from a network, a first system information comprising a first satellite assistance information and a first indication of a timer; means for starting, in response to the receiving the first system information, the timer based on the first satellite assistance information; and means for performing, in response to the timer expiring, the following: downlink monitoring for receiving a second system information comprising a second satellite assistance information and a second indication of the timer, and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0035] According to an eighth aspect, a method is disclosed. The method may be computer-implemented. The method may comprise: Receiving, from a network, a first system information comprising a first satellite assistance information and a first indication of a timer. Starting, in response to the receiving the first system information, the timer based on the first satellite assistance information. Performing, in response to the timer expiring, the following: downlink monitoring for receiving a second system information comprising a second satellite assistance information and a second indication of the timer; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0036] According to a ninth aspect, a computer-readable medium is disclosed. The computer-readable medium may comprise program instructions for causing an apparatus to perform at least the following: Receiving, from a network, a first system information comprising a first satellite assistance information and a first indication of a timer. Starting, in response to the receiving the first system information, the timer based on the first satellite assistance information. Performing, in response to the timer expiring, the following: downlink monitoring for receiving a second system information comprising a second satellite assistance information and a second indication of the timer; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0037] According to a tenth aspect, a computer program is disclosed. The computer program may comprise instructions for causing an apparatus to perform at least the following: Receiving, from a network, a first system information comprising a first satellite assistance information and a first indication of a timer. Starting, in response to the receiving the first system information, the timer based on the first satellite assistance information. Performing, in response to the timer expiring, the following: downlink monitoring for receiving a second system information comprising a second satellite assistance information and a second indication of the timer; and refraining, in response to one or more uplink transmissions being pending to the network, from transmitting the one or more pending uplink transmissions.

[0038] Any example embodiment may be combined with one or more other example embodiments. Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings.

[0039] DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help to understand the example embodiments. In the drawings:

[0041] FIG. 1 illustrates an exemplified wireless communication system;

[0042] FIG. 2 illustrates example functionalities of an apparatus according to an example embodiment;

[0043] FIG. 3 illustrates example functionalities of an apparatus according to an example embodiment;

[0044] FIG. 4 illustrates example functionalities of an apparatus according to an example embodiment;

[0045] FIG. 5 illustrates example functionalities of an apparatus according to an example embodiment;

[0046] FIG. 6 illustrates a signaling diagram according to an example embodiment; and

[0047] FIG. 7 illustrates a schematic block diagram of an apparatus according to an example embodiment.

[0048] Like references are used to designate like parts in the accompanying drawings.

[0049] DETAILED DESCRIPTION

[0050] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0051] Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature may not apply to other embodiments. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments / examples to consist of only those features that have been mentioned and such embodiments / examples may contain also features / structures that have not been specifically mentioned. Furthermore, although the numerative terminology, such as “first”, “second”, etc., may be used herein to describe various embodiments, elements, or features, it should be understood that these embodiments, elements, or features should not be limited by this numerative terminology. This numerative terminology is used herein only to distinguish one embodiment, element, or feature from another embodiment, element, or feature. For example, a first information discussed below could be called a second information, and vice versa, without departing from the teachings of the present disclosure.

[0052] In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. The embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WiAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

[0053] FIG. 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in FIG. 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in FIG. 1.

[0054] The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

[0055] The example of FIG. 1 shows a part of an exemplifying radio access network 100.

[0056] FIG. 1 shows user devices 101, 101’ configured to be in a wireless connection on one or more communication channels with a node 102. The node 102 is further connected to a core network 105. In one example, the node 102 may be an access node such as (e / g)NodeB providing or serving devices in a cell. In one example, the node 102 may be a non-3GPP access node. The physical link from a device to a (e / g)NodeB is called uplink or reverse link and the physical link from the (e / g)NodeB to the device is called downlink or forward link. It should be appreciated that (e / g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

[0057] A communications system typically comprises more than one (e / g)NodeB in which case the (e / g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes. The (e / g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e / g)NodeB includes or is coupled to transceivers. From the transceivers of the (e / g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e / g)NodeB is further connected to the core network 105 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), or access and mobility management function (AMF), etc.

[0058] The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station.

[0059] The user device typically refers to a device (e.g. a portable or non-portable computing device) that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and / or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human- to-computer interaction, e.g., to be used in smart power grids and connected vehicles. The user device may also utilize cloud. In some applications, a user device may comprise a user portable device with radio parts (such as a watch, earphones, eyeglasses, other wearable accessories or wearables) and the computation is carried out in the cloud. The device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses.

[0060] Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyberphysical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

[0061] Additionally, although the apparatuses have been depicted as single entities, different units, processors and / or memory units (not all shown in FIG. 1) may be implemented.

[0062] 5G enables using multiple-input multiple-output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and / or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6 GHz, cmWave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (interradio interface operability, such as below 6 GHz-cmWave, below 6 GHz-cmWave- mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput, and mobility.

[0063] The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0064] The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 106, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by “cloud” 107). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

[0065] The technology of Edge cloud may be brought into a radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using the technology of edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes, or hosts. Application of cloud RAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 102) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 104).

[0066] It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be nonexistent. Some other technology advancements probably to be used are Big Data and all- IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well.

[0067] 5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling, coverage in areas with no terrestrial coverage, and for disaster scenarios where the terrestrial network is not functional. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway / maritime / aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). Each satellite 103 in the mega-constellation may cover several satellite- enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node 102 or by a gNB located on-ground (known as the transparent architecture) or in a satellite (known as the regenerative architecture).

[0068] It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e / g)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e / g)NodeBs or may be a Home(e / g)NodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e / g)NodeBs of FIG. 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e / g)NodeBs are required to provide such a network structure.

[0069] For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e / g)NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e / g)NodeBs, includes, in addition to Home (e / g)NodeBs (H(e / g)NodeBs), a home node B gateway, or HNB-GW (not shown in FIG. 1). A HNB Gateway (HNB-GW), which is typically installed within an operator's network may aggregate traffic from a large number of HNBs back to a core network.

[0070] In 5G and 6G non-terrestrial networks, and beyond, it is envisaged that prioritizing downlink monitoring when uplink synchronization is lost may enable preventing uplink and downlink collisions. With half-duplex (HD) reduced capability (Redcap) devices, which may be understood as devices that cannot receive and transmit simultaneously, a differential delay caused by a round-trip time in a non-terrestrial network may complicate the network’s ability to determine whether uplink and downlink transmissions will collide in a specific user device. The user device is responsible for pre-compensating uplink transmissions by setting its timing advance based on a current position of the user device and also a satellite position and a feeder link delay, which are comprised in a satellite assistance information, provided to the user device by the network via, e.g., a SIB19 as specified in 3GPP TS 38.331, or SIB31 that is used for Internet of Things (loT) as specified in 3GPP TS 36.331, or another SIB. An apparatus configured to receive information to obtain uplink synchronization may be configured to perform downlink monitoring and to refrain from transmitting pending uplink transmissions while uplink synchronization is lost, e.g., as described below with FIG. 2 to 6.

[0071] FIG. 2 illustrates example functionalities of an apparatus configured to prioritize downlink monitoring when uplink synchronization is lost. The apparatus may be a user device.

[0072] Referring to FIG. 2, a first information to obtain an uplink synchronization is received in operation 201, from a network. In an example embodiment, the first information may comprise satellite assistance information. In an example embodiment, the receiving the first information may comprise receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the first information. In an example embodiment, the receiving the first information may comprise receiving a system information block such as, e.g., a SIB 19. The SIB 19 may comprise satellite assistance information such as, e.g., Ephemeris data, common timing advance parameters, koffset, validity duration for uplink synchronization epoch time, cell reference location, and / or cell stop time.

[0073] Referring to FIG. 2, the uplink synchronization is obtained in operation 202, in response to the receiving the first information. It is resolved in operation 203 whether the uplink synchronization is lost. The uplink synchronization being lost may be understood such as the first information not being valid (anymore) for uplink transmissions, or as validity information comprised in the first information having expired. In an example embodiment, the loss of the uplink synchronization may comprise a validity timer, based on the first information, having expired. In an example embodiment, the validity timer is a validity timer for non-terrestrial network uplink synchronization. In an example embodiment, the validity timer is a T430, as specified in 3GPP TS 38.331. In an example embodiment, the first information may comprise a first satellite assistance information. In an example embodiment, the first satellite assistance information may comprise a first validity duration and a first epoch time. In an example embodiment, the timer T430 may be started based on the first validity duration and the first epoch time comprised in the SIB 19. A validity duration may be understood as a maximum time duration during which the apparatus may apply a satellite assistance information without having acquired a new satellite assistance information, and may be indicated in seconds (s) such as, e.g., 5 s, 10 s, etc. Referring to FIG. 2, if the uplink synchronization is lost (operation 203: yes), downlink monitoring for a second information to restore the uplink synchronization is performed in operation 204. In an example embodiment, the second information may comprise satellite assistance information. It is resolved in operation 205 whether there are one or more uplink transmissions pending to the network. A pending uplink transmission may be understood as a scheduled uplink transmission or a configured uplink transmission. In an example embodiment, an uplink transmission within the one or more uplink transmissions may be a semi-statically configured uplink transmission or a dynamically scheduled uplink transmission. If the one or more uplink transmissions are pending, the process is refrained in operation 206 from transmitting the pending one or more uplink transmissions, to the network. In an example embodiment, the refraining from transmitting the one or more pending uplink transmission is performed in response to the one or more pending uplink transmissions at least partially overlapping with the downlink monitoring for the second information, i.e., when there is a collision between downlink and uplink occurrences. In an example embodiment, the process in operations 204 to 206 may be understood as the apparatus ignoring any uplink scheduling for uplink transmissions while the uplink synchronization is lost and simultaneously downlink monitoring for the second information to restore the uplink synchronization. If there are no uplink transmissions pending (operation 205: no), the process continues by downlink monitoring in operation 204. If the uplink synchronization is not lost (operation 203 : no), the process continues in operation 207 by keeping configured collision handling rules, for example to prioritize an uplink transmission when the uplink transmission collides in time with a downlink monitoring occasion. In other words, the example defines the UE prioritizes to monitor downlink for the second information even when there is a pending (dynamic of semi-static) scheduled uplink transmission colliding with the downlink monitoring occasion.

[0074] FIG. 3 illustrates further example functionalities of an apparatus configured to prioritize downlink monitoring when uplink synchronization is lost. The apparatus may be a user device.

[0075] Referring to FIG. 3, the process continues from operation 204 in FIG. 2. The second information is received in operation 301, from the network. In an example embodiment, the receiving the second information may comprise receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the second information. In an example embodiment, the receiving the first information may comprise receiving a system information block, and the receiving the second information may comprise receiving a different version of the system information block. In an example embodiment, the system information block may be a SIB 19.

[0076] Referring to FIG. 3, the uplink synchronization is restored in operation 302 in response to the receiving the second information. In an example embodiment, the restoring the uplink synchronization may comprise restarting the validity timer, based on the second information. In an example embodiment, the second information may comprise a second satellite assistance information. In an example embodiment, the second satellite assistance information may comprise a second validity duration and a second epoch time. The process then reverts in operation 303 to the configured collision handling rules. The one or more pending uplink transmissions are transmitted in operation 304.

[0077] FIG. 4 illustrates example functionalities of an apparatus configured to prioritize downlink monitoring when a timer based on satellite assistance information expires. The apparatus may be a user device. The network may not be aware of the timer value of the user device, because the network may not know when each user device acquires the satellite assistance information. Therefore, the network may not know why the specific user device is not transmitting according to a dynamic uplink scheduling and why the user device will not transmit using any semi-static configured uplink resources. Based on the user device’s reported timing advance (TA) the network may be able to deduct that the user device is receiving the satellite assistance information instead. Additionally, the network may be able to detect whenever the user device applies new satellite assistance information, since the modeling of common TA may cause a “TA jump” when applying new satellite assistance information. This would be indicative of the user device reading the new satellite assistance information, and since the network knows the timer, there is a period of time (validity time / duration) during which the network may assume that the user device will not lose uplink time synchronization. The apparatus may therefore benefit from a new collision rule to handle a scenario when uplink synchronization is lost due to timer expiry by enabling the satellite assistance information to be reacquired as fast as possible. Referring to FIG. 4, a first system information comprising a first satellite assistance information and a first indication of a timer received in operation 401, from a network. In an example embodiment, the receiving the first system information may comprise receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the first information. In an example embodiment, the receiving the first system information may comprise receiving a first system information block such as, e.g., a SIB19. In an example embodiment, the first satellite assistance information may comprise a first validity duration and a first epoch time. In an example embodiment, the timer is a validity timer. In an example embodiment, the validity timer is a validity timer for non-terrestrial network uplink synchronization. In an example embodiment, the validity timer is a T430.

[0078] Referring to FIG. 4, the timer based on the first satellite assistance information is started in operation 402, in response to the receiving the first system information. It is resolved in operation 403 whether the timer has expired. The timer expiring may be understood as the timer exceeding a validity duration set as a timer value. When the timer expires, the uplink synchronization is lost. In an example embodiment, the starting the timer based on the first satellite assistance information may comprise setting the first validity duration as the timer value at the first epoch time. If the timer has expired (operation 403: yes), downlink monitoring for a second system information comprising a second satellite assistance information and a second indication of the timer is performed in operation 404. In an example embodiment, the second satellite assistance information may comprise a second validity duration and a second epoch time. It is resolved in operation 405 whether there are one or more uplink transmissions pending. In an example embodiment, an uplink transmission within the one or more uplink transmissions may be a semi-statically configured uplink transmission or a dynamically scheduled uplink transmission. If the one or more uplink transmissions are pending, the process is refrained in operation 406 from transmitting the pending one or more uplink transmissions, to the network. In an example embodiment, the refraining from transmitting the one or more pending uplink transmission is performed in response to the one or more pending uplink transmissions at least partially overlapping with the downlink monitoring for the second system information, i.e., when there is a collision between downlink and uplink occurrences. In an example embodiment, the process in operations 404 to 406 may be understood as the apparatus ignoring any uplink scheduling for uplink transmissions while the timer is expired and simultaneously downlink monitoring for the second system information. If there are no uplink transmissions pending (operation 405: no), the process continues by downlink monitoring in operation 404. If the timer has not expired (operation 403: no), the process continues in operation 407 by keeping configured collision handling rules, i.e., to prioritize an uplink transmission when the uplink transmission collides in time with a downlink monitoring occasion.

[0079] FIG. 5 illustrates further example functionalities of an apparatus configured to prioritize downlink monitoring when the timer is expired. The apparatus may be a user device.

[0080] Referring to FIG. 5, the process continues from operation 404 in FIG. 4. The second system information is received in operation 501, from the network. In an example embodiment, the receiving the second system information may comprise receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the second information. In an example embodiment, the receiving the first system information may comprise receiving a system information block, and the receiving the second system information may comprise receiving a different version of the system information block. In an example embodiment, the different version may comprise a different epoch time and a different satellite assistance information (ephemeris, common TA). In an example embodiment, the system information block may be a SIB 19.

[0081] Referring to FIG. 5, the timer is restarted in operation 502 based on the second satellite assistance information, in response to the receiving the second system information. In an example embodiment, the second satellite assistance information may comprise a second validity duration and a second epoch time. In an example embodiment, the restarting the timer based on the second satellite assistance information may comprise setting the second validity duration as the timer value at the second epoch time. The process then reverts in operation 503 to the configured collision handling rules. The one or more pending uplink transmissions are transmitted in operation 504.

[0082] FIG. 6 illustrates a signaling diagram according to an example of information exchange in a communication network configured to enable prioritizing downlink monitoring when a validity timer has expired. The term “UE” is used for a user device configured to prioritize downlink monitoring. The term “NW” is used for one or more network elements such as an access node configured to transmit system information indicating a validity timer. The access node may be, e.g., a gNB or a distributed access node, comprising for example a centralized unit (CU) and a distributed unit (DU) enabling RAN real time functions being carried out at the RAN side (in the DU) and non-real time functions being carried out in a centralized manner (in the CU). The term “message” is used for, e.g., a downlink control information (DCI), a medium access control (MAC) control element (CE), or an information element.

[0083] Referring to FIG. 6, the NW transmits message 6-1 to the UE scheduling message 6-2 carrying the first information. In an example embodiment, message 6-1 may be a downlink control information (DCI) on a physical downlink control channel (PDCCH) scheduling a physical downlink shared channel (PDSCH) carrying the first system information (message 6-2). In an example embodiment, the first system information may be a SIB 19. The first system information comprises a first satellite assistance information and a first indication of a validity timer. The UE starts in block 6-3 the validity timer based on the first satellite assistance information. In an example embodiment, the first satellite assistance information may comprise a first validity duration and a first epoch time. After some time has passed, e.g., the first validity duration or less, depending on, e.g., round-trip time, the validity timer expires in block 6-4. The UE then, in response to the validity timer expiring, performs in block 6-5 the following steps: The UE downlink monitors in block 6-5a for a second system information comprising a second satellite assistance information and a second indication of the timer. In an example embodiment, the second system information may be a SIB 19. The UE refrains in block 6-5b, in response to one or more uplink transmissions being pending, from transmitting the one or more pending uplink transmissions to the NW. In an example embodiment, the blocks 6-5a and 6-5b are at least partially overlapping, i.e., there is a collision between uplink and downlink occurrences.

[0084] Referring to FIG. 6, the NW transmits message 6-6 to the UE scheduling message 6-7 carrying the second information. In an example embodiment, message 6-6 may be a downlink control information (DCI) on a physical downlink control channel (PDCCH) scheduling a physical downlink shared channel (PDSCH) carrying the second system information (message 6-7). The UE starts in block 6-8 the validity timer based on the second satellite assistance information. In an example embodiment, this may be understood as the UE reverting to configured collision handling rules, such as, e.g., prioritizing uplink transmissions over downlink monitoring. The UE transmits (message 6-9) the one or more pending uplink transmissions to the NW.

[0085] FIG. 7 illustrates an example embodiment of an apparatus 700, which may be an apparatus such as, or comprised in, a user device. The apparatus 700 may correspond to any of the user devices 101, 101’ of FIG. 1. The apparatus may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, user equipment (UE), vehicle, or any electric device. Although the apparatus 700 is illustrated as a single device, it is appreciated that, wherever applicable, functions of the apparatus 700 may be distributed to a plurality of devices.

[0086] The apparatus 700 may comprise at least one processor 702. The at least one processor 702 may comprise, for example, one or more of various processing devices or processor circuitry, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like.

[0087] The apparatus 700 may further comprise at least one memory 704. The at least one memory 704 may be configured to store, for example, computer program code or the like, for example operating system software and application software. The at least one memory 704 may comprise one or more volatile memory devices, one or more nonvolatile memory devices, and / or a combination thereof. For example, the at least one memory 704 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0088] The apparatus 700 may further comprise a communication interface 708 configured to enable the apparatus 700 to transmit and / or receive information to / from other devices. In one example, the apparatus 700 may use the communication interface 708 to transmit or receive signaling information and data in accordance with at least one data communication or cellular communication protocol. The communication interface 708 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connections may be also implemented as separate communication interfaces, which may be coupled or configured to be coupled to one or more of a plurality of antennas. The communication interface 708 may comprise a receiver, a transmitter, or a transceiver.

[0089] Referring to FIG. 7, when the apparatus 700 is configured to implement some functionality, some component and / or components of the apparatus 700, such as for example the at least one processor 702 and / or the at least one memory 704, may be configured to implement this functionality. Furthermore, when the at least one processor 702 is configured to implement some functionality, this functionality may be implemented using program code 706 comprised, for example, in the at least one memory 704.

[0090] The functionality described herein may be performed, at least in part, by one or more computer program product components such as for example software components. According to an example embodiment, the apparatus 700 may comprise a processor or processor circuitry, such as for example a microcontroller, configured by the program code when executed to execute the embodiments of the operations and functionality described. The program code 706 is provided as an example of instructions which, when executed by the at least one processor 702, cause performance of apparatus. Alternatively, or additionally, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), application-specific Integrated Circuits (ASICs), application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs).

[0091] The apparatus 700 may be configured to perform or cause performance of any aspect of the method(s) described herein. Further, a computer program may comprise instructions for causing, when executed, an apparatus to perform any aspect of the method(s) described herein. The computer program may be stored on a computer- readable medium. Further, the apparatus 700 may comprise means for performing any aspect of the method(s) described herein. In one example, the means may comprise the at least one processor 702, the at least one memory 704 including the program code 706, (instructions) configured to, when executed by the at least one processor 702, cause the apparatus 700 to perform the method(s). In general, computer program instructions may be executed on means providing generic processing functions. The method(s) may be thus computer-implemented, for example, algorithm(s) executable by the generic processing functions, an example of which is the at least one processor 702. The means may comprise transmission and / or reception means, for example one or more radio transmitters or receivers, which may be coupled or be configured to be coupled to one or more antennas, or transmitter(s) or receiver(s) of a wired communication interface.

[0092] As used in this application, the term ‘circuitry’ refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of circuits and soft-ware (and / or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s) / software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (T) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of ‘circuitry’ applies to all uses of this term in this application. As a further example, as used in this application, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile device or a similar integrated circuit in a sensor, a cellular network device, or another network device.

[0093] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter 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 embodiments of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

[0094] It will be understood that the benefits and advantages described above may relate to one example embodiment or may relate to several example embodiments. The example embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items. The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the example embodiments described above may be combined with aspects of any of the other example embodiments described to form further example embodiments without losing the effect sought.

[0095] It will be understood that the above description is given by way of example embodiments only and that various modifications may be made by those skilled in the art. The above specification, example embodiments and data provide a complete description of the structure and use of exemplary embodiments. Although various example embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed example embodiments without departing from scope of this specification.

Claims

24CLAIMS1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, from a network, a first information to obtain an uplink synchronization; obtaining, in response to the receiving the first information, the uplink synchronization; and performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending, to the network, from transmitting the one or more pending uplink transmissions.

2. An apparatus according to claim 1, wherein the apparatus is caused to perform the refraining from transmitting in response to the one or more pending uplink transmissions at least partially overlapping with the downlink monitoring.

3. An apparatus according to claim 1 or 2, wherein the apparatus is further caused to perform: receiving, from the network, the second information; restoring, in response to the receiving the second information, the uplink synchronization; and transmitting, in response to the restoring the uplink synchronization, to the network, the one or more pending uplink transmission.

4. An apparatus according to any of the preceding claims, wherein the first information and the second information comprise satellite assistance information.

5. An apparatus according to any of the preceding claims, wherein the apparatus is caused to perform the receiving the first information by receiving a system informationblock, and the receiving the second information by receiving a different version of the system information block.

6. An apparatus according to claim 5, wherein the system information block is a SIB 19.

7. An apparatus according to any of the preceding claims, wherein the loss of the uplink synchronization comprises a validity timer, based on the first information, expiring.

8. An apparatus according to claim 7, wherein the validity timer is a validity timer for non-terrestrial network uplink synchronization.

9. An apparatus according to any of claims 7 to 8, wherein the first information comprises a first satellite assistance information and the second information comprises a second satellite assistance information.

10. An apparatus according to claim 9, wherein the first satellite assistance information comprises a first validity duration and a first epoch time, and the second satellite assistance information comprises a second validity duration and a second epoch time.

11. An apparatus according to any of the preceding claims, wherein the apparatus is caused to perform the receiving the second information by receiving a downlink control information on a physical downlink control channel scheduling a physical downlink shared channel carrying the second information.

12. An apparatus according to any of the preceding claims, wherein an uplink transmission within the one or more uplink transmissions is a semi-statically configured uplink transmission or a dynamically scheduled uplink transmission.

13. A method comprising: receiving, from a network, a first information to obtain an uplink synchronization; obtaining, in response to the receiving the first information, the uplink synchronization; andperforming, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending, to the network, from transmitting the one or more pending uplink transmissions.

14. A computer-readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving, from a network, a first information to obtain an uplink synchronization; obtaining, in response to the receiving the first information, the uplink synchronization; and performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending, to the network, from transmitting the one or more pending uplink transmissions.

15. A computer program comprising instructions for causing an apparatus to perform at least the following: receiving, from a network, a first information to obtain an uplink synchronization; obtaining, in response to the receiving the first information, the uplink synchronization; and performing, in response to a loss of the uplink synchronization, the following: downlink monitoring for receiving a second information to restore the uplink synchronization; and refraining, in response to one or more uplink transmissions being pending, to the network, from transmitting the one or more pending uplink transmissions.

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