Layer 1 / layer 2 triggered mobility

Abstract

Apparatuses, methods and computer programs are provided for enhancing layer 1 / layer 2 triggered mobility (LTM) One or more configured grants are allocated to a user equipment to use when accessing a candidate target cell after a cell switch or handover. The user equipment receives an indication which one or more of the one or more configured grants it should use for accessing the candidate target cell.

Description

[0001] LAYER 1 / LAYER 2 TRIGGERED MOBILITY

[0002] TECHNICAL FIELD

[0003] Various example embodiments relate generally to the field of telecommunications and in particular to apparatuses, such as user equipments and network nodes, methods and computer program products for enhancing layer 1 / layer 2 (L1 / L2) triggered mobility (LTM).

[0004] BACKGROUND

[0005] In order to ensure communication continuousness in the wireless communication system, multiple technologies are proposed, such as cell switch. During the cell switch, the terminal device may switch among different cells. Further, technology of layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) may be used for enabling the cell switch. LTM is a procedure in which the next generation node B (gNB) receives layer 1 (LI) and / or layer 3 (L3) measurement report(s) from a UE, and thus the gNB changes the user equipment (UE) serving cell by a cell switch command signalled via a medium access control control element (MAC CE). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through radio resource control (RRC) signalling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure may be used to reduce the mobility latency.

[0006] For a RACH-less LTM cell switch, a mechanism is required to support the initial transmission of the UE to the candidate target cell. This is achieved by using dynamic grants or configured grants.

[0007] BRIEF DESCRIPTION

[0008] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure. LIST OF THE DRAWINGS

[0009] In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which:

[0010] Fig. 1 shows an example of a communication network to which examples disclosed herein may be applied;

[0011] Fig. 2 shows a signalling diagram illustrating an example of lower layer triggered mobility;

[0012] Fig. 3 shows a simplified schematic diagram of RACH-less LTM;

[0013] Fig. 4 shows an example of a method;

[0014] Fig. 5 shows an example of a method;

[0015] Fig. 6 shows an example of a method;

[0016] Fig. 7 shows an example of a method;

[0017] Fig. 8 shows an example of a method;

[0018] Fig. 9 shows an example of a method;

[0019] Fig. 10 shows an example of a method;

[0020] Fig. 11 shows an example of a message flow diagram;

[0021] Fig. 12 shows an example of a message flow diagram;

[0022] Fig. 13 show an example of a message flow diagram;

[0023] Fig. 14 show an example of a message flow diagram;

[0024] Fig. 15 shows an example of an apparatus; and

[0025] Fig. 16 shows a simplified schematic diagram of a communication network in which examples disclosed herein may be applied.

[0026] DESCRIPTION OF EMBODIMENTS

[0027] The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0028] For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0029] Embodiments described may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wide- band-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (M1M0), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0030] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (1AB) node, a low power node, a non-terrestrial network (NTN) or nonground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0031] Moreover, in connection of split radio access network (RAN), the network device, network node or apparatus may refer to a centralised unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an Fl interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0032] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like.

[0033] A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources include e.g. a physical resource block (PRE), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0034] Fig. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0035] The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0036] There may be a plurality of UEs 120, 122 in the system. Each of them may be served by the same or by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so- called sidelink (SL). Such D2D communications may be referred to as machine-to-ma- chine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0037] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface.

[0038] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise e.g. a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise e.g. an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example.

[0039] In 3GPP Rel-18, a new mobility mechanism was introduced, namely lower layer-triggered mobility (LTM), which aims to reduce interruption time during handover.

[0040] The overall procedure for LTM is illustrated in the signalling diagram in Figure 2, with reference to the network components schematically illustrated in Figure 1. Figure 2 is taken from Figure 9.2.3.5.2-1 of TS38.300vl8. As described in TS38.300vl8, 9.2.3.5.2, the procedure for LTM is as follows:

[0041] In Step 1 of Figure 2 the UE, for example the UE 120 sends a Measuremen- tReport message to the gNB 110, which provides access to the source cell 100. The gNB 110 decides to configure LTM and initiates LTM preparation.

[0042] In Step 2 of Figure 2, the gNB 110 transmits an RRCReconfiguration message to the UE 120 including the LTM candidate configurations.

[0043] In Step 3 of Figure 2 the UE 120 stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB 110. In Step 4a of Figure 2, the UE 120 performs DL synchronization with the candidate cell(s) 102 before receiving the cell switch command.

[0044] In Step 4b of Figure 2, when the UE-based TA measurement is configured, the UE 120 acquires the TA value(s) of the candidate cell(s) 102 by measurement. The UE 120 performs early TA acquisition with the candidate cell(s) 102 as requested by the network before receiving the cell switch command as specified in clause 9.2.6. This is done via CFRA triggered by a PDCCH order from the source cell 100, following which the UE 120 sends preamble towards the indicated candidate cell 102. In order to minimize the data interruption of the source cell 100 due to CFRA towards the candidate cell(s) 102, the UE 120 does not receive a random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell 102 is instead indicated in the cell switch command. The UE 120 does not maintain the TA timer for the candidate cell 102 and relies on network implementation to guarantee the TA validity.

[0045] In Step 5 of Figure 2 the UE 120 performs LI measurements on the configured candidate cell(s) 102 and transmits LI measurement reports to the source gNB 110. LI measurement should be performed as long as the RRC reconfiguration (from step 2) is applicable.

[0046] In Step 6 of Figure 2, the gNB 110 decides to execute a cell switch from the source cell 100 to the candidate or target cell 102 and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell 102. The UE 120 then switches to the target cell 102 and applies the configuration indicated by candidate configuration index.

[0047] In Step 7 of Figure 2 the UE 120 performs the random access procedure towards the target cell 102, if the UE 120 does not have a valid TA of the target cell 102 as specified in clause 6.1.3.xy of TS 38.321[6].

[0048] In Step 8 of Figure 2, the UE 120 completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to the gNB 112 providing access to the target cell 102. If the UE 120 has performed a RA procedure in Step 7 of Figure 2 then the UE 120 considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed.

[0049] For RACH-less LTM, the UE 120 considers that the LTM cell switch execution is successfully completed when the UE 120 determines that the network has successfully received its first UL data.

[0050] As seen above, in LTM, early TA acquisition, i.e. TA acquisition before hand- over / cell switch, can be performed in the following ways:

[0051] Firstly, the network can order the UE 120 to perform random access (RA) preamble transmission to a candidate cell 102. The candidate cell 102 uses the received RA preamble to estimate the TA and provides the TA estimate to the source cell 100. When the source cell 100 decides to trigger the cell switch, it provides the estimated TA value along with the cell switch command.

[0052] Secondly, during LTM preparation, the network can configure the UE 120 to perform UE-based TA measurements. UE-based TA measurements may be performed based on the TA of the serving cell 100 and the measured time difference between the candidate cell 102 and the serving cell 100. After being configured, the UE 120 is assumed to obtain a TA measurement before a cell switch command is issued by the gNB 110 providing access to the source cell 100.

[0053] Another purpose served by random access is that the target gNB 112 is notified about the presence of the UE 120 and resources for the UE’s subsequent transmissions are provided to the UE 120.

[0054] Hence, when a RACH-less LTM cell switch is performed, a mechanism is required to support the initial transmission of the UE 120 to the target cell 102. A mechanism that supports this purpose is the provisioning of configured grants, which consist of sets of uplink resources in the candidate / target cell that the UE 120 may use if / when it performs its initial transmission after handover / cell switch to the target cell 102. An alternative to this mechanism is to provide an access notification from the source cell 100 to the target cell 102, so that the target cell 102 can then provide a dynamic grant to the UE 120 for the target cell 102. A similar RACH-less approach has also been proposed for baseline and conditional handover (BHO / CHO) as well to facilitate fast cell switch.

[0055] A drawback of dynamic grants is that the first uplink transmission of the UE 120 may be delayed until the UE 120 receives the dynamic grant, whereas a configured grant is provided to the UE 120 in the handover or cell switch preparation phase. The configured grant is a periodic set of uplink resources in the candidate / target cell 102, which the UE 120 may use if or when it performs its initial transmission after handover or cell switch to the target cell 102.

[0056] A timeline of a RACH-less LTM handover using configured grants is shown schematically in Figure 3, which illustrates the reservation time for the configured grant. For a configured grant, the target cell reserves PUSCH resources in the radio frame with a specific periodicity for the UE. The target cell cannot use the reserved PUSCH resources from the time of the handover request until the time of completion of the handover by the UE. In RACH-less LTM cell switch or handover, the UE needs to use an uplink grant to send the first uplink packet to indicate its arrival in the target cell. In the case of configured grant, this causes a long delay with the reservation of uplink resources. When multiple UEs are prepared for LTM, one or more configured grants for each prepared UE must be configured. This means that the amount of uplink resources reserved at a candidate target cell grows linearly with the number of UEs prepared for an LTM cell switch or handover, which can lead to a high resource waste.

[0057] Accordingly, it is proposed that uplink resources (configured grants) to be used in the candidate target cell are shared among multiple UEs. In this way, one or more configured grants can be used by multiple UEs. The shared resources are provided from the target DU in the target gNB 112 providing access to the candidate target cell 102 to the source DU in the source gNB 110 providing access to the source cell 100 currently serving the UE 120. This minimises the resource reservation overhead at candidate target cells by allowing and coordinating sharing of configured grants among UEs. The shared configured grants can be provided as a list of configured grants, or as a shared pool of resources (illustrated in Figure 12).

[0058] Figure 4 shows an example of a method. The method may be computer-implemented. The method may be performed by a user equipment, for example the UE 120 or the UE 122 shown in Figure 1.

[0059] As shown in Figure 4, the UE 120 in step 401 receives one or more configured grants for the candidate target cell 102 from the source gNB 110, more specifically, the distributed unit (DU) of the source gNB 110. The received one or more configured grants can be used by the UE 120 when accessing the candidate target cell 102 after LTM cell change (cell switch or handover) from the source cell 100 to the candidate target cell 102. In step 402, the UE 120 receives information from the source gNB 110 that the received one or more configured grants are shared uplink resources that can be used by multiple UEs. For instance, the configured grants could be shared between and used by both UEs 120 and 122, as well as any other UEs undergoing LTM cell switch to the candidate target cell 102. In step 403 the UE 120 receives an indication from the source gNB 110 which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell. Each UE 120, 122 may use one of the configured grants that it receives or it may use multiple configured grants. The network indicates to the UE which one(s) of the shared configured grants it should actually use, from those it has received from the network.

[0060] The UE 120 can also receive an indication to refrain from using the indicated one or more of the one or more configured grants to access the candidate target cell 102, until the UE 120 receives an instruction from the source gNB 110. The UE 120 is informed that it should not use the indicated configured grants until the network instructs the UE 120 that it may do so. The indication to refrain from using the indicated one or more of the one or more configured grants can be part of the received information that that the received one or more configured grants are shared uplink resources. As the uplink resources are shared between UEs, a particular UE 120 may not use the configured grants it has been allocated unless these resources have been released by another UE, for example UE 122, and can be re-used.

[0061] The UE 120 can be configured to store the received one or more configured grants.

[0062] The UE 120 can receive a trigger to access the candidate target cell 102 using the indicated one or more of the one or more configured grants. The trigger can be at a MAC level or at an RRC level and triggers the UE 120 to access the candidate target cell 102 using the shared configured grant(s) that it has been allocated. The UE 120 may also receive information about the candidate target cell 102 from the source gNB 110, for example a cell ID of the candidate target cell 102.

[0063] The one or more configured grants can be allocated or provided to the UE as part of either the configuration of the source cell 100 or the candidate target cell 102.

[0064] Figure 5 shows a method. The method may be computer implemented. The method may be performed by a network node, for example the gNB 110 shown in Figure 1, which provides access to the source cell 100. More specifically, the method may be performed by the distributed unit (DU) of the source gNB 110.

[0065] In step 501, the gNB 110 receives one or more configured grants to be used in a candidate target cell 102 from a target network node 112 providing access to the candidate target cell 102. Each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments, for example the UEs 120 and 122 illustrated schematically in Figure 1. The gNB 110 allocates the one or more configured grants to the UE 120 in step 502. The UE 120 is in a source cell served by the gNB 110. In step 503, the gNB 110 indicates to the UE 120 which one or more of the one or more configured grants the UE 120 should use upon accessing the candidate target cell 102 for an LTM cell switch or handover from the source cell 100 to the target cell 102.

[0066] The gNB 110 can also provide an indication to the UE 120 to refrain from using the indicated one or more of the one or more configured grants until the UE 120 receives an instruction from the gNB 110. Since the configured grant(s) are shared between multiple UEs, the UE 120 is not able to use those configured grant(s) allocated to it until they have been released by another UE and can be re-used by the UE 120. It can also be indicated to the UE 120 by the gNB 110 that each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments.

[0067] The gNB 110 can receive an indication from the target gNB 112 that at least one of the one or more configured grants has been released by the UE 120 and can therefore be allocated to another user equipment, for example the UE 122. Once the UE 120 has undergone cell switch to the target cell 102, the one or more configured grants the UE 120 used to access the target cell 102 can be re-used by another UE after it has been released by the UE 120.

[0068] The gNB 110 can allocate the one or more configured grants to the UE 120 based on a measurement report received from the UE 120. The one or more configured grants can be provided to the user equipment either as part of the source cell configuration or as part of the candidate target cell configuration.

[0069] Figure 16 schematically shows the gNBs 110 and 112 illustrated in Figure 1 in more detail. Each gNB 110, 112 has a central unit (CU) and a distributed unit (DU) connected to each other over an Fl interface. The DU 131 and the CU 132 of the source gNB 110 are connected to each other via the Fl interface, likewise the DU 141 and CU 142 of the target gNB 112. The Fl interface in each gNB 110, 112 can be split into user plane and control plane functionalities (not shown here). The CU 132 of the source gNB 110 is connected to the CU 142 of the target gNB 112 via the Xn-C interface and both CUs 132, 142 in the gNBs 110 and 112, respectively, are connected to the core network 116 via an NG interface.

[0070] However, it should be noted that the CUs 132, 142 may not necessarily be colocated with the DUs 131 and 141, respectively. The CUs 132, 142 could also be one combined unit connected to both source and target DUs 131 and 141 (Intra CU LTM). Both options, inter-CU and intra-CU LTM are considered here. In the description with reference to the method in Figure 6 only the reference CU 132 will be used. However, the method in Figure 6 can apply to both inter-CU and intra-CU LTM. The difference between these two options will be shown in more detail in the signalling diagrams of Figures 11, 12, 13 and 14.

[0071] Figure 6 shows a method, which may be computer implemented. The method can be performed by the central unit CU 132. The central unit may be part of the source gNB 110 or have its functionality shared by the source gNB 110 and the target gNB 112. In step 601 the CU 132 determines that a lower layer (L1 / L2) triggered mobility procedure is to take place for the UE 120 changing from the source cell 100 to the candidate target cell 102. This could be a cell switch or handover, for example. In step 602 the CU 132 receives one or more configured grants for the UE 120 to use for accessing the candidate target cell 102 when it changes from the source cell 100 to the target cell 102. The CU 132 then allocates one or more of the one or more configured grants that it has received to the user equipment 120 in step 603. In step 604 the CU 132 indicates to the UE 120 that the configured grants it has been allocated are shared uplink resources, meaning that they can be used by multiple user equipments. For example, the configured grants allocated to the UE 120 may also be used by the UE 122.

[0072] The CU 132 can also send an indication that the configured grants should be reserved for the UE 120 to use for accessing the candidate target cell 102. The CU 132 can also indicate to the UE 120 which one or more of the configured grant(s) allocated to the UE 120 it should use for accessing the target cell, and may also send information to the UE 120 that it should not use those configured grant(s) allocated to it until it receives an indication to do so by the network.

[0073] If the CU 132 receives an indication from the target gNB 112 that the UE 120 has successfully accessed the candidate target cell, the CU 132 can be configured to send an indication to the source DU 131 of the source gNB 110 that one or more of the one or more configured grants allocated to the UE 120 has been freed and can be allocated to a second user equipment, for example the UE 122. Then the CU 132 can indicate to the target gNB 112 that it can re-use the configured grant(s) allocated to the UE120 for the second UE 122. This be related to step 604 of Figure 6.

[0074] The cell change from the source cell 100 to the candidate target cell 102 can be a cell switch or a handover, for example. The CU 132 can determine that a lower layer, that is Layer 1 / Layer 2, mobility procedure is to take place for handover or cell switch of the UE 120 from the source cell 100 to the target cell 102 based on receiving a measurement report from the UE 120.

[0075] Figure 7 shows a method, which may be computer implemented. The method can be performed by the source DU 131 of the source gNB 110. In step 701 the source DU 131 receives one or more configured grants for the UE 120 to use when accessing the candidate target cell 102. The DU 131 sends a cell switch command to the UE 120 in step 702 that it should execute a change, for example a cell switch or handover, from the source cell 100 to the candidate target cell 102. In step 703 the DU 131 indicates in the cell switch command which one or more of the one or more configured grants the UE 120 should use for accessing the candidate target cell. The configured grants are shared uplink resources that can be used by multiple UEs, for example UE 120, UE 122 and any other UEs in the network. The configured grant(s) can be allocated to the UE 120 based on a Layer 1 measurement report from the UE 120.

[0076] The DU 131 can receive a Layer 1 measurement report from the UE 120 and trigger the sending of the cell switch command based on the received Layer 1 measurement report.

[0077] The target gNB 112 can be informed by the source DU 131 that one or more configured grants are allocated to the user equipment for accessing the target cell 102. When the UE 120 has accessed the candidate target cell 102, the source DU 131 can indicate to a second target network node (DU2 shown in Figure 11) providing access to a second candidate target cell that the one or more configured grants allocated to the UE 120 are released and can be re-used by a second user equipment, for example UE 122. The source DU 131 can then allocate the one or more configured grants to the second UE 122 when the one or more configured grants allocated to the UE 120 have been released. An indication can be received at the DU 131 from the CU 132 that the one or more configured grants can be allocated to the second UE 122.

[0078] Figure 8 shows a method, which may be computer implemented. The method can be performed by the UE 120. In step 801, the UE 120 receives a cell switch command indicating that it should execute a change (cell switch or handover) from the source cell 100, which is the serving cell, to the candidate target cell 102. In the cell switch command, the UE 120 receives an indication in step 802 informing it which one or more of one or more configured grants allocated to the UE 120 it should use for accessing the candidate target cell 102. The configured grants are shared uplink resources that multiple UEs can use.

[0079] Figure 9 shows a method, which may be computer implemented. The method can be performed by the target DU 141 in the target gNB 112, which provides access to the target cell 102. In step 901 the target DU 141 provides one or more configured grants for the UE 120 to use for accessing the candidate target cell 102 served by the gNB 112 when executing a change (a cell switch or handover, for example) from the source cell 100 to the candidate target cell 102. The target DU 141 can provide the configured grant(s) to the CU 132, which can then allocate them to the UE 120. The one or more configured grants are shared uplink resources that can be used by multiple UEs. In step 902 the DU 141 receives a transmission from the UE 120 and in step 903 the DU 141 may use this information in the transmission to decode a first uplink transmission of the UE 120. The information in the transmission can be an ID of the UE 120, for example. Alternatively, the DU 141 can blindly decode the first uplink transmission of the UE 120 using the IDs of the UEs that share the grant until either successful decoding takes place or all the IDs are used.

[0080] The target DU 141 can send a confirmation to the gNB 110 providing access to the source cell 100 that the one or more configured grants have been used by the UE 120 to successfully access the candidate target cell 102 and can therefore be released and used by a second UE 122. The DU 141 can then receive a confirmation from the source network node that the one or more configured grants have been released.

[0081] It can be indicated by the source gNB 110 that one or more configured grants are allocated to the UE 120 and this indication can be received by the target DU 141 from the gNB 110.

[0082] Figure 10 shows a method, which may be computer implemented. The method can be performed by the UE 120. In step 1001 the UE 120 uses one or more configured grants that have been provided to it for accessing the candidate target cell 102 when executing a cell change from the source cell 100 to the candidate target cell 102. The one or more configured grants are shared uplink resources that can be used by multiple user equipments. In step 1002, the UE 120 sends a transmission to the target gNB 112 including information for the gNB 112 to use for decoding a first uplink transmission of the UE 120. The cell change can be a cell switch or a handover from the source cell 100 to the candidate target cell 102 using a lower layer (Layer 1 / Layer 2) triggered mobility procedure (LTM). The cell switch or handover can be RACH-less.

[0083] Before handover preparation, the UE 120 may indicate to the network that it supports the handling of shared configured grants. In other words, the UE can indicate that it supports reception of a configured grant with an indication that it is shared (for example in the RRC message). This indication can indicate the UE capability for the shared UL grant procedure.

[0084] Embodiments will now be described in more detail with reference to message flow (signalling) diagrams. Figure 11 shows an intra-gNB mobility scenario.

[0085] The steps of Figure 11 are described in detail below:

[0086] Step 1: UE 120 provides a Layer 3 measurement report to the CU 132.

[0087] Step 2: The CU 132 determines LTM handover preparation and allocation of a shared configure grant / PUSCH that can be used by multiple UEs will be allocated to UE 120.

[0088] Step 3: The CU 132 sends a UE Context Setup Request for UE 120 to the candidate target DU, DU 141, with an indication to provide a shared configured grant.

[0089] Step 4: The DU sends a UE Context Setup Response for UE 120 to the CU 132 including a shared configured grant.

[0090] Step 5: UE Context Setup message exchange for UE 120 between the CU 132 and DU 2 (the distributed unit of the second target gNB), similar to steps 3-4.

[0091] Step 6: The CU 132 sends a UE Context Modification Request for UE 120 to the source DU 131, which includes information aboutthe shared configured grants provided by the candidate target DUs 141 and DU 2.

[0092] - the information about the shared configured grants may optionally be configured grant indices and associated candidate target cell IDs.

[0093] Step 7: The source DU 131 sends a UE Context Modification Response for UE 120 to the CU 132.

[0094] Step 8: The CU 132 generates the RRC Reconfiguration of the UE 120, including one or more shared configured grants.

[0095] Step 9: The CU 132 sends the RRC Reconfiguration to UE 120, which includes one or more shared configured grants.

[0096] Step 10: After receiving the RRC Reconfiguration message, in the case of a cell switch, the UE 120 can use any of the shared configured grants only after receiving a corresponding indication from the source DU 131. Step 12: The second UE 122 sends a Layer 3 measurement report to the CU

[0097] 132.

[0098] Step 13: The CU 132 determines LTM handover preparation and allocation of a shared configured grants / PUSCH that can be used by multiple UEs and that will be allocated to the UE 122.

[0099] Step 14: The CU 132 sends a UE Context Setup Request for UE 122, indicating that shared the shared configured grant previously provided to the UE 120 be reused.

[0100] Steps 15-16: After receiving the UE Context Setup Request, the target DU 141 does not allocate a new configured grant for UE 122 and sends a UE Context Setup Response to the CU 132.

[0101] Step 17: The CU 132 sends a UE Context Modification Request for UE 120 to the source DU 131, which includes information aboutthe shared configured grants provided by the candidate target DUs 141 and DU2.

[0102] In one embodiment, the information about the shared configured grants is configured grant indices and associated candidate target cell IDs.

[0103] Step 18: The source DU 131 sends a UE Context Modification Response for UE 120 to the CU 132.

[0104] Steps 19-20: The CU 132 generates and sends the RRC Reconfiguration message to UE 122, which includes a first shared configured grant CGI, which was previously provided to UE 120, where this is also sent with an indication that it is a shared configured grant; i.e., a configured grant that can be shared between and used by multiple UEs.

[0105] Step 21: After receiving the RRC Reconfiguration message, in the case of a cell switch, UE 122 can only use (any of) the shared configured grants after receiving a corresponding indication that it is allowed to do so from the source DU 131.

[0106] Step 21: UE 122 sends the RRC Reconfiguration complete message to the CU 132.

[0107] Steps 23-24: After receiving a (Layer 1) measurement report from UE 120, the source DU 131 may trigger the UE 120 to perform early TA acquisition for the target cell 102 and / or another target cell (shown as cell 2 in Figure 11). Steps 25-26 (Optional):

[0108] Steps 25-26: After receiving a (Layer 1) measurement report from the UE 120, the source DU 131 may decide to allocate shared the shared configured grant CGI for the target cell 102 to UE 120.

[0109] Step 27: The source DU 131 may inform the target DU 141 that the shared configured grant CGI is allocated to UE 120. This option is provided so that the target DU 141 can be informed in a timely way about the allocation of the shared configured grant to the UE 120 and use the ID of the UE 120 or any other necessary information such as the key of the UE 120 to decode the first transmission of the UE 120 to the target DU 141.

[0110] Steps 28-29: After receiving a (Layer 1) measurement report from the UE 120, the source DU 131 decides to trigger a cell switch to the target cell 102 for UE 120. If not already decided in Step 26, the source DU 131 decides to allocate the shared configured grant CGI for accessing the target cell 102 to the UE 120.

[0111] Steps 30-31: The source DU 131 sends an indication to the second target DU DU 2 via the CU 132 that a second shared configured grant CG2 has been released by UE 120 (since the switch to candidate cell 120 has been decided for the UE 120). DU 2 maintains the shared configured grant CG 2 if it is currently shared by other UEs, otherwise it may release it.

[0112] Step 32: The source DU 131 sends a cell switch command to UE 1, including an indication to use shared configured grant CG 1.

[0113] Step 33: The source DU does not allocate shared configured grant CG 1 to another UE until it receives a confirmation from the target DU 141 that the configured grant CGI has been released by UE 120.

[0114] Step 34: UE 120 sends an RRC reconfiguration complete message to the target DU 141 using the shared configured grant CG 1.

[0115] If the target DU 141 has received an indication of allocation of the shared configured grant CGI to UE 120 (Step 27) or the shared configured grant CG 1 is currently shared only by UE 120, then in Step 35 the target DU 141 decodes the first UL message on the shared configured grant CG 1 using the ID of UE 120, e.g., the C-RNT1 of UE 120. Otherwise, if no indication of allocation of the shared configured grant CG 1 to UE 120 has been received and the shared CG 1 is currently shared by more than one UE, then in Step 36, the target DU 141 blindly decodes the first UL message on the shared configured grant CG 1 using the IDs, e.g., C-RNTls, of the UEs that share the grant until successful decoding or until all IDs have been used.

[0116] Step 37: After successful decoding of the UL transmission of UE 120, the target DU 141 sends an access success message to the CU 132.

[0117] Step 38: The CU 132 sends an indication to the source DU 131 that the shared configured grant CG 1 has been freed. The indication may be implicit, e.g., by sending UE context release command, or explicit.

[0118] Step 39: The source DU 131 can consider the shared configured grant CG 1 for allocation to another UE, e.g., UE 122.

[0119] Step 40: The cell switch of UE 120 is completed.

[0120] Figure 12 is a message flow diagram showing an embodiment in detail. Instead of providing a specific shared configured grant for each UE in the UE context setup response, the target DU 141 may provide a shared pool of PUSCH resources to the CU 132. The shared pool may then be managed by the CU 132 and the source DU 131 as shown in Figure 12.

[0121] In the following, only the relevant steps that differ from those described in Figure 11 will be described.

[0122] Step 3: The CU 132 sends a UE Context Setup Request for the UE 120 to the candidate target DU 141 with an indication to provide a shared PUSCH pool.

[0123] Step 4: The DU 141 sends a UE Context Setup Response for the UE 120 to the CU 132 including a shared PUSCH pool.

[0124] Step 5: There is a UE Context Setup message exchange for UE 120 between CU 132 and the second target DU DU 2, similar to steps 3-4.

[0125] Step 6: The CU 132 determines a list of configured grants with their corresponding IDs in shared pool 1 and similarly in shared pool 2. As an example, candidate target cell 102 has shared pool 1 including configured grants CG 1, 2, 3; candidate target cell cell 2 has shared pool 2 including configured grants CG 1, 2, 3.

[0126] A shared pool configuration is composed of configured grant configurations. The main difference between a shared pool and a list of configured grants provided to the UE is that:

[0127] - the pool is allocated by the target node.

[0128] - the exact configured grant to be used is determined by the source node

[0129] - the UE behavior for the shared pool and other configured grants are different. o The UE cannot use the configured grant resources in the shared pool unless the network indicates to the UE that it may do so.

[0130] - The same configured grant resources may be provided to multiple UEs at the control of the same source node, which may initiate a cell switch to the target node.

[0131] Step 7: The CU 132 sends a UE context modification request to the source DU, providing a list of CGs in the shared pools, where the list of CGs of each shared pool may contain a subset of the CGs determined in Step 6, e.g., cell 102 (- shared pool 1) - CG 1, 2; cell 2 (- shared pool 2) - CG 2, 3

[0132] Steps 9-10: The CU 132 provides the CGs in the shared pools in the same way as in Figure 2, i.e., one or more configured grants associated with a candidate target cell.

[0133] Step 31: The source DU 131 indicates to the target DU 141 via the CU 132 that the UE 120 will release shared pool 1 of the second candidate target cell cell 2, since it will perform a switch to the candidate target cell 102.

[0134] Figure 13 is a message flow diagram showing an embodiment where source and target gNBs each have their own CUs, as shown in Figure 15 (inter-gNB LTM). The distributed DU-CU architecture is not shown here. The main difference compared to the intra-gNB case shown in Figure 11 is that the target DU 141 of the target gNB 112 determines whether it will provide a shared configured grant and, if so, provides the shared configured grant in the handover request acknowledgment. The decision as to whether the target DU 142 provides a shared configured grant to the UE 120 for accessing the candidate target cell 102 is determined based on load in the candidate target cell 102.

[0135] The embodiments described herein can be applied to RACH-less conditional LTM and RACH-less conditional handover. In these cases, the indication to a UE to use a shared configured grant may be provided along with an indication to perform early timing advance (TA) acquisition, and the UE autonomously decides to execute cell switch or handover, based on an event configured by the network. Alternatively, the UE 120 may be provided with a separate message, for example MAC-CE. If a UE has not received an indication to use a shared configured grant when the cell switch or handover is triggered, the UE 120 performs RACH-based cell switch / handover. An example of RACH-less conditional handover (CHO) is shown in the signalling diagram of Figure 14.

[0136] Figure 15 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods as disclosed herein, and any of the embodiments thereof. In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods as disclosed herein, and any of the embodiments thereof.

[0137] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0138] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may be at least in part external to apparatus 10 but accessible to apparatus 10.

[0139] The instructions 15 may be comprised in a computer readable medium or a non-transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM).

[0140] For example, the apparatus 10 is a terminal device, such as the UE 120 of Figure 1. As another example, the apparatus is comprised in such a terminal device or UE 120, e.g. as a chipset configured to control the terminal device or UE 120. The apparatus 10 may be caused or configured to perform at least the method of Figures 4 to 10 and / or any one or more of the embodiments described.

[0141] As another example, the apparatus 10 is a network node, e.g. the gNB 110 schematically shown in Figure 1. In another embodiment, the apparatus is comprised in such a network node or gNB 110 or 112, e.g. as a chipset configured to control the network node. The apparatus 10 may be caused or configured to perform at least the method of Figures 4 to 10 and / or any one or more of the embodiments described.

[0142] The apparatus may comprise one or more entities of any of protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity or a PHY entity. In some embodiments, the entity is configured to perform at least the method of Figures 4 to 10, and / or any one or more of the embodiments described.

[0143] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non- cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0144] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0145] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C.

[0146] Following is a list of some aspects of the invention. According to a first aspect, there is provided a user equipment, comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the user equipment at least to receive from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell, receive information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments, and receive an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

[0147] Various embodiments of the first aspect may optionally comprise at least one feature from the following bulleted list:

[0148] • The user equipment is further configured to receive an indication to refrain from using said indicated one or more of the one or more configured grants to access the candidate target cell until the user equipment receives an instruction from the source node.

[0149] • The indication to refrain from using said indicated one or more of the one or more configured grants is part of the received information that that the received one or more configured grants are shared uplink resources.

[0150] • The user equipment is further configured to store the received one or more configured grants.

[0151] • The user equipment is further configured to receive a trigger to access the candidate target cell using the indicated said one or more of the one or more configured grants.

[0152] • The trigger is a MAC level trigger. The trigger is an RRC level trigger.

[0153] The user equipment is further configured to receive information about the candidate target cell from the source network node.

[0154] • The information about the candidate target cell information is a Cell ID of the candidate target cell.

[0155] • The source network node is a distributed unit, DU of a gNodeB.

[0156] • The one or more configured grants are provided to the UE as part of a candidate target cell configuration.

[0157] • The one or more configured grants are provided to the UE as part of a source cell configuration.

[0158] According to a second aspect, there is provided a network node, comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the network node at least to receive one or more configured grants to be used in a candidate target cell from a target network node providing access to the candidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments, allocate the one or more configured grants to a user equipment in a source cell served by the network node, and indicate to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

[0159] Various embodiments of the second aspect may comprise at least one feature from the following bulleted list: • The network node is further configured to provide an indication to the user equipment to refrain from using the indicated one or more of the one or more configured grants until the user equipment receives an instruction from network node.

[0160] • The network node is further configured to indicate to the user equipment that each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments.

[0161] • The network node is further configured to receive an indication from the target network node that at least one of the one or more configured grants has been released by the user equipment and can therefore be allocated to another user equipment.

[0162] • The network node is configured to receive a measurement report from the user equipment and allocates the one or more configured grants to the user equipment based on the received measurement report.

[0163] • The one or more configured grants are provided to the user equipment as part of the candidate target cell configuration.

[0164] • The one or more configured grants are provided to the user equipment as part of the source cell configuration.

[0165] • The network node is a distributed unit of a gNodeB.

[0166] According to a third aspect, there is provided user equipment, comprising means for receiving from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell, means for receiving information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments, and means for receiving an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

[0167] Various embodiments of the third aspect may comprise at least one feature from the bulleted list under the first aspect.

[0168] According to a fourth aspect, there is network node, comprising means for receiving one or more configured grants to be used in a candidate target cell from a target network node providing access to the candidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments, means for allocating the one or more configured grants to a user equipment in a source cell served by the network node, and means for indicating to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

[0169] Various embodiments of the fourth aspect may comprise at least one feature from the bulleted list under the second aspect.

[0170] According to a fifth aspect, there is provided method for a user equipment, comprising receiving from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell, receiving information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments, and receiving an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

[0171] Various embodiments of the fifth aspect may comprise at least one feature from the bulleted list under the first aspect.

[0172] According to a sixth aspect there is provided a method for a network node, comprising receiving one or more configured grants to be used in a candidate target cell from a target network node, providing access to the candidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments, allocating the one or more configured grants to a user equipment in a source cell served by the network node, and indicating to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

[0173] Various embodiments of the sixth aspect may comprise at least one feature from the bulleted list under the second aspect.

[0174] According to a seventh aspect there is provided a computer program product comprising program instructions which, when executed by an apparatus, cause the apparatus to carry out the method according to the fifth aspect or according to the sixth aspect.

[0175] According to an eighth aspect, there is provided an apparatus for a network node, the apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the apparatus at least to determine that a lower layer triggered mobility procedure is to take place for a user equipment executing a change from a source cell served by the network node to a candidate target cell served by a target network node, receive one or more configured grants for the user equipment to use for accessing the candidate target cell, allocate one or more of the one or more configured grants to the user equipment, and indicate to the user equipment that the one or more configured grants are shared uplink resources that can be used by multiple user equipments.

[0176] Various embodiments of the eighth aspect may comprise at least one feature from the following bulleted list:

[0177] • The apparatus is further configured to send an indication to the target network node that the one or more configured grants should be reserved for said user equipment for accessing the candidate target cell;

[0178] • The apparatus is further configured to indicate to the user equipment which one or more of the allocated one or more configured grants the user equipment should use. • The apparatus is further configured to send information to the user equipment that it should refrain from using the one or more of the one or more configured grants until it receives an indication to do so by the network.

[0179] • The apparatus is further configured to send an indication to a distributed unit of the network node that the one or more of the one or more configured grants has been freed and can be allocated to a second user equipment if the apparatus receives an indication from the target network node that the user equipment has successfully accessed the candidate target cell.

[0180] • The apparatus is further configured to send an indication to the target network node that it can re-use the one or more of the one or more configured grants allocated to the user equipment for the second user equipment.

[0181] • The apparatus is configured to determine that a lower layer triggered mobility procedure is to take place for handover or cell switch of a user equipment from the source cell to the candidate target cell based on receiving a measurement report from the user equipment.

[0182] • The apparatus is a central unit of a gNodeB.

[0183] According to an ninth aspect, there is provided an apparatus for a network node, the apparatus comprising means for determining that a lower layer triggered mobility procedure is to take place for a user equipment executing a change from a source cell served by the network node to a candidate target cell served by a target network node, means for receiving one or more configured grants for the user equipment to use for accessing the candidate target cell, means for allocating one or more configured grants to the user equipment for accessing the candidate target cell, and means for indicating to the user equipment that the one or more configured grants are shared uplink resources that can be used by multiple user equipments. Various embodiments of the ninth aspect may comprise at least one feature from the bulleted list under the eighth aspect.

[0184] According to a tenth aspect, there is provided a method, comprising determining that a lower layer triggered mobility procedure is to take place for a user equipment executing a change from a source cell served by a source network node to a candidate target cell served by a target network node, receiving one or more configured grants for the user equipment to use for accessing the candidate target cell, allocating one or more of the one or more configured grants to the user equipment for accessing the candidate target cell, and indicating to the user equipment that the one or more configured grants are shared uplink resources that can be used by multiple user equipments.

[0185] Various embodiments of the tenth aspect may comprise at least one feature from the bulleted list under the eighth aspect.

[0186] According to an eleventh aspect there is provided a computer program product comprising program instructions which, when executed by an apparatus, cause the apparatus to carry out the method according to the tenth aspect.

[0187] According to a twelfth aspect there is provided an apparatus for a network node, the apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the apparatus at least to, receive one or more configured grants for a user equipment to use when accessing a candidate target cell, send a cell switch command to the user equipment that the user equipment should execute a change from a source cell to the candidate target cell, and indicate in the cell switch command which one or more of the one or more configured grants the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0188] Various embodiments of the twelfth aspect may comprise at least one feature from the following bulleted list: • The one or more configured grants are allocated to the user equipment based on a Layer 1 measurement report received from the user equipment.

[0189] • The apparatus is further configured to trigger sending of the cell switch command based on a Layer 1 measurement report received from the user equipment.

[0190] • The apparatus is further configured to inform a target network node providing access to the candidate target cell that the one or more configured grants are allocated to the user equipment.

[0191] • The apparatus is further configured to indicate to a second target network node providing access to a second candidate target cell that the one or more configured grants allocated to the user equipment are released and can be reused by a second user equipment when the user equipment has accessed the candidate target cell.

[0192] • The apparatus is configured to allocate the one or more configured grants to the second user equipment when the configured grants have been released.

[0193] • The apparatus is configured to receive an indication from a central unit of the network node that the one or more configured grants can be allocated to the second user equipment.

[0194] • The apparatus is a distributed unit of a gNodeB providing access to the source cell.

[0195] According to a thirteenth aspect, there is provided a user equipment, the user equipment comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the user equipment at least to receive a cell switch command that the user equipment should execute a change from a source cell to a candidate target cell and receive an indication in the cell switch command which one or more of one or more configured grants allocated to the user equipment the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0196] According to a fourteenth aspect, there is provided an apparatus for a network node, the apparatus comprising means for receiving one or more configured grants for a user equipment to use when accessing a candidate target cell, means for sending a cell switch command to the user equipment that the user equipment should execute a change from a source cell to the candidate target cell, and means for indicating in the cell switch command which one or more of the one or more configured grants the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0197] Various embodiments of the fourteenth aspect may comprise at least one feature from the bulleted list under the twelfth aspect.

[0198] According to a fifteenth aspect there is provided a user equipment, comprising, means for receiving a cell switch command that the user equipment should execute a change from a source cell to a candidate target cell, and means for receiving an indication in the cell switch command which one or more of one or more configured grants allocated to the user equipment the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0199] According to a sixteenth aspect there is provided a method, comprising receiving one or more configured grants for a user equipment to use when accessing a candidate target cell, sending a cell switch command to the user equipment that the user equipment should execute a change from a source cell to the candidate target cell, and indicating in the cell switch command which one or more of the one or more configured grants the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0200] Various embodiments of the sixteenth aspect may comprise at least one feature from the bulleted list under the twelfth aspect.

[0201] According to a seventeenth aspect there is provided a method, comprising receiving a cell switch command that a user equipment should execute a change from a source cell to a candidate target cell, and receiving an indication in the cell switch command which one or more of one or more configured grants allocated to the user equipment the user equipment should use for accessing the candidate target cell, wherein the configured grants are shared uplink resources that can be used by multiple user equipments.

[0202] According to an eighteenth aspect there is provided a computer program product comprising program instructions which, when executed by an apparatus, cause the apparatus to carry out the method according to the sixteenth aspect or the seventeenth aspect.

[0203] According to a nineteenth aspect, there is provided an apparatus for a network node, the apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the apparatus at least to provide one or more configured grants for a user equipment to use for accessing a candidate target cell served by the network node when executing a change from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, receive a transmission from the user equipment, and use information in the transmission to decode a first uplink transmission of the user equipment. Various embodiments of the nineteenth aspect may comprise at least one feature from the following bulleted list:

[0204] • The information is an ID of the user equipment.

[0205] • The apparatus is further configured to send a confirmation to a source network node providing access to the source cell that the one or more configured grants have been used by the user equipment to successfully access the candidate target cell and can therefore be released and used by a second user equipment.

[0206] • The apparatus is further configured to receive a confirmation from the source network node that the one or more configured grants have been released.

[0207] • The apparatus is further configured to receive an indication from a source network node providing access to the source cell that one or more configured grants are allocated to a user equipment.

[0208] • The apparatus is a distributed unit of a target network node providing access to the candidate target cell.

[0209] According to a twentieth aspect, there is provided a user equipment, comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the user equipment at least to use one or more configured grants provided to the user equipment for accessing a candidate target cell served by a network node when executing a change from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, and send a transmission to the network node including information for the network node to use for decoding a first uplink transmission of the user equipment.

[0210] Various embodiments of the twentieth aspect may comprise at least one feature from the following bulleted list: • The change is a cell switch or a handover from the source cell to the candidate target cell using a lower layer triggered mobility procedure.

[0211] • The the cell switch or handover is RACH-less.

[0212] According to a twenty first aspect, there is provided an apparatus for a network node, the apparatus comprising means for providing one or more configured grants for a user equipment to use for accessing a candidate target cell served by the network node when executing a cell switch from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, means for receiving a transmission from the user equipment, and means for using information in said transmission to decode a first uplink transmission of the user equipment.

[0213] Various embodiments of the twenty first aspect may comprise at least one feature from the bulleted list under the nineteenth aspect.

[0214] According to a twenty second aspect there is provided a user equipment, comprising means for using one or more configured grants allocated to the user equipment for accessing a candidate target cell served by a network node when executing a change from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, and means for sending a transmission to the network node including information for the network node to use for decoding a first uplink transmission of the user equipment.

[0215] Various embodiments of the twenty second aspect may comprise at least one feature from the bulleted list under the twentieth aspect.

[0216] According to a twenty third aspect there is provided a method performed at an apparatus for a network node, the method comprising, providing one or more configured grants for a user equipment to use for accessing a candidate target cell served by the network node when executing a change from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, receiving a transmission from the user equipment, and using information in the transmission to decode a first uplink transmission of the user equipment.

[0217] Various embodiments of the twenty third aspect may comprise at least one feature from the bulleted list under the nineteenth aspect.

[0218] According to a twenty fourth aspect there is provided a method performed at a user equipment, the method comprising using one or more configured grants allocated to the user equipment for accessing a candidate target cell served by a network node when executing a change from a source cell to the candidate target cell, wherein the one or more configured grants are shared uplink resources that can be used by multiple user equipments, and sending a transmission to the network node including information for the network node to use for decoding a first uplink transmission of the user equipment.

[0219] Various embodiments of the twenty fourth aspect may comprise at least one feature from the bulleted list under the twentieth aspect.

[0220] According to a twenty fifth aspect, there is provided a computer program product comprising program instructions which, when executed by an apparatus, cause the apparatus to carry out the method according to the twenty third aspect or the twenty fourth aspect.

[0221] In this way, fast access of the UE to the target cell can be enabled by using configured grants that are shared between multiple UEs. Resource reservation overhead is minimized at candidate target cells by allowing and coordinating sharing of configured grants among UEs. For indicating allocation of the grant to the UE, signalling overhead is minimized compared to allocating the uplink grant in the CSC MAC-CE

[0222] Although the invention has been described above with reference to examples according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodi- ments in various ways.

Claims

CLAIMS1. A user equipment, comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the user equipment at least to: receive from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell; receive information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments; and receive an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

2. The user equipment according to claim 1, wherein the user equipment is further configured to receive an indication to refrain from using said indicated one or more of the one or more configured grants to access the candidate target cell until the user equipment receives an instruction from the source node.

3. The user equipment according to claim 2, wherein the indication to refrain from using said indicated one or more of the one or more configured grants is part of the received information that that the received one or more configured grants are shared uplink resources.

4. The user equipment according to claim 1, wherein the user equipment is further configured to store the received one or more configured grants.

385. The user equipment according to any of claims 1 to 4, wherein the user equipment is further configured to receive a trigger to access the candidate target cell using the indicated said one or more of the one or more configured grants.

6. The user equipment according to claim 5, wherein the trigger is a MAC level trigger.

7. The user equipment according to claim 5, wherein the trigger is an RRC level trigger.

8. The user equipment according to any of claims 1 to 7, wherein the user equipment is further configured to receive information about the candidate target cell from the source network node.

9. The user equipment according to claim 8, wherein the information is a Cell ID of the target cell.

10. The user equipment according to any of claims 1 to 9, wherein the source network node is a distributed unit, DU of a gNodeB.

11. The user equipment according to any of claims 1 to 10, wherein the one or more configured grants are provided to the UE as part of a candidate target cell configuration.

12. The user equipment according to any of claims 1 to 10, wherein the one or more configured grants are provided to the UE as part of a source cell configuration.

13. A network node, comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code being configured, with the at least one processor, to cause the network node at least to: receive one or more configured grants to be used in a candidate target cell from a target network node providing access to the candidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments; allocate the one or more configured grants to a user equipment in a source cell served by the network node; and indicate to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

14. The network node according to claim 13, wherein the network node is further configured to provide an indication to the user equipment to refrain from using the indicated one or more of the one or more configured grants until the user equipment receives an instruction from network node.

15. The network node according to claim 13 or claim 14, wherein the network node is further configured to indicate to the user equipment that each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments.

16. The network node according to any of claims 13 to 15, wherein the network node is further configured to receive an indication from the target network node that at least one of the one or more configured grants has been released by the user equipment and can therefore be allocated to another user equipment.

17. The network node according to any of claims 1 to 4, wherein the network node is configured to receive a measurement report from the user equipment and allocates the one or more configured grants to the user equipment based on the received measurement report.

18. The network node according to any of claims 13 to 17, wherein the one or more configured grants are provided to the user equipment as part of the candidate target cell configuration.

19. The network node according to any of claims 13 to 17, wherein the one or more configured grants are provided to the user equipment as part of the source cell configuration.

20. The network node according to any of claims 13 to 19, wherein the network node is a distributed unit of a gNodeB.

21. A user equipment, comprising: means for receiving from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell; means for receiving information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments; and means for receiving an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

22. A network node, comprising: means for receiving one or more configured grants to be used in a candidate target cell from a target network node providing access to thecandidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments; means for allocating the one or more configured grants to a user equipment in a source cell served by the network node; and means for indicating to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

23. A method for a user equipment, the method comprising: receiving from a source network node one or more configured grants for a candidate target cell, wherein the received one or more configured grants are to be used by the user equipment when accessing the candidate target cell; receiving information from the source network node that the received one or more configured grants are shared uplink resources that can be used by multiple user equipments; and receiving an indication from the source network node which one or more of the received one or more configured grants the user equipment should use when accessing the candidate target cell.

24. A method for a network node, the method comprising: receiving one or more configured grants to be used in a candidate target cell from a target network node providing access to the candidate target cell, wherein each of the one or more configured grants is a shared uplink resource that can be used by multiple user equipments; allocating the one or more configured grants to a user equipment in a source cell served by the network node; and indicating to the user equipment which one or more of the one or more configured grants the user equipment should use upon accessing the candidate target cell.

5. A computer program product, comprising program instructions which, when the program is executed by an apparatus, cause the apparatus to carry out the method according to claim 23 or claim 24.43

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