Determining availability of timing information

Abstract

Example embodiments of the disclosure relate to apparatuses, methods and a computer readable medium for discarding random access resources In a method, a first apparatus receives a command triggering cell switch towards a target cell. The first apparatus determines whether timing information is available in the command and decodes the command based on the determining.

Description

DETERMINING AVAILABILITY OF TIMING INFORMATIONFIELDS

[0001] Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and a computer readable storage medium for determining availability of timing information.BACKGROUND

[0002] In a Layer 1(L1) / Layer 2 (L2)-Triggered Mobility (LTM) procedure, a gNB receives LI measurement report(s) from user equipment (UE), and on their basis the gNB changes UE serving cell by a cell switch command (CSC) signaled via a medium access control (MAC) control element (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) signaling. Then, the UE switches to a target cell according to the cell switch command. The LTM procedure may be used to reduce the mobility latency.

[0003] The MAC CE for signaling the CSC may include a timing advance command (TAC) field to indicate whether timing advance (TA) is valid for the LTM target cell. If the value of this field is set to FFF, this field indicates that no valid timing adjustment is available for the PTAG of the LTM target cell. Otherwise, this field indicates an index value used to control the amount of timing adjustment. Then, the UE may skip a Random Access procedure for this LTM cell switch.SUMMARY

[0004] In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive a command triggering cell switch towards a target cell; determine whether timing information is available in the command; and decode the command based on the determining.

[0005] In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: transmit, to the first apparatus, a command triggering cell switch towards a target cell; and indicate, to the first apparatus, whether timing information is available in the command.

[0006] In a third aspect of the present disclosure, there is provided a method. The method includes: receiving a command triggering cell switch towards a target cell; determining whether timing information is available in the command; and decoding the command based on the determining.

[0007] In a fourth aspect of the present disclosure, there is provided a method. The method includes: transmitting, to the first apparatus, a command triggering cell switch towards a target cell; and indicating, to the first apparatus, whether timing information is available in the command.

[0008] In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus includes means for receiving a command triggering cell switch towards a target cell; means for determining whether timing information is available in the command; and means for decoding the command based on the determining.

[0009] In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus includes means for transmitting, to the first apparatus, a command triggering cell switch towards a target cell; and means for indicating, to the first apparatus, whether timing information is available in the command.

[0010] In a seventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium includes instructions stored thereon for causing an apparatus to perform at least the method according to the third or fourth aspect.

[0011] It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure may become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Some example embodiments may now be described with reference to the accompanying drawings, where:

[0013] FIG. 1 illustrates an example LTM cell switch command MAC CE;

[0014] FIG. 2 illustrates an example communication environment in which example embodiments of the present disclosure may be implemented;

[0015] FIG. 3 illustrates a signaling flow for communications between the first and second apparatuses according to some example embodiments of the present disclosure;

[0016] FIG. 4A illustrates an example LTM cell switch command MAC CE with random access triggered according to some example embodiments of the present disclosure;

[0017] FIG. 4B illustrates an example LTM cell switch command MAC CE without random access triggered according to some example embodiments of the present disclosure;

[0018] FIG. 5 illustrates an example flowchart of determining availability of timing information according to some example embodiments of the present disclosure;

[0019] FIG. 6 illustrates a flowchart of a method implemented at a first apparatus according to some example embodiments of the present disclosure;

[0020] FIG. 7 illustrates a flowchart of a method implemented at a second apparatus according to some example embodiments of the present disclosure;

[0021] FIG. 8 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0022] FIG. 9 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0023] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0024] Principle of the present disclosure may now be described with reference to someexample embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein may be implemented in various manners other than the ones described below.

[0025] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0026] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0027] It may be understood that although the terms “first,” “second,”... , etc. in front of noun(s) 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 and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0028] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0029] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It may be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0031] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0032] 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 cellularnetwork device, or other computing or network device.

[0033] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), the sixth generation (6G) communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there may of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0034] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture includes a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node includes a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0035] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal devicemay also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customerpremises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0036] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain may be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0037] When the LTM procedure is configured by a network, it is possible to activate Transmission Configuration Indicator (TCI) states of one or multiple cells that are different from a current serving cell. For instance, the TCI states of the LTM candidatecells may be activated in advance before any of those cells become a serving cell. This allows the UE to be downlink (DL) synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

[0038] When the LTM procedure is configured by the network, it is possible to initiate uplink (UL) timing advance (TA) acquisition (also referred to as early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTA as the current serving cells or NTA=0, the early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by Physical Downlink Control Channel (PDCCH) order or realized through UE -based TA measurement as configured by radio resource control (RRC) signaling. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC signaling but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs random access channel (RACH)-less LTM upon receiving the cell switch command. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0039] Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE applies the TA value by itself if available. Meanwhile, the UE performs RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

[0040] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it may still follow the PDCCH order, which includes requesting a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it may still follow the UE-based measurement configuration if configuredby the network.

[0041] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UE may not trigger random access procedure if it does not have a valid Physical Uplink Control Channel (PUCCH) resource for triggered Scheduling Requests (SRs). There are some principles that may be applied to LTM. One of the principles is that a security key is maintained upon an LTM cell switch. The other one of the principles is that subsequent LTM is supported.

[0042] LTM supports both intra-gNB-DU and intra-gNB-CU inter-gNB-DU mobility. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. A non-carrier aggregation (CA) scenario and a non-DC scenario where a primary cell (PCell) changes may be supported. A CA scenario where PCell and secondary cell (SCell)(s) change may be supported. A dual connectivity scenario where PCell and master cell group (MCG) SCell(s) change and intra-SN PSCell and SCG SCell(s) change without a master node (MN) involvement may be supported. However, LTM for simultaneous PCell and PSCell change may not be supported. While the UE has stored LTM candidate configurations the UE may also execute any Layer 3 (L3) handover command sent by the network.

[0043] Regarding LTM cell switch command, the network may instruct the UE to perform LTM cell switch procedure by sending the LTM Cell Switch Command MAC CE. If the MAC entity receives an LTM Cell Switch Command MAC CE on a Serving Cell, the MAC entity may indicate to upper layers that the LTM cell switch procedure is triggered and the Target Configuration ID included in the MAC CE. In the case that the MAC reset operation is performed, as requested by upper layers, if Timing Advance Command value (hexa-decimal) is not set as FFF, the MAC entity may process the received Timing Advance Command; the MAC entity may consider the RACH-less LTM cell switch to be ongoing; if the MAC entity is associated with SCG, the MAC entity may indicate to upper layers to skip the Random Access procedure for this LTM cell switch.

[0044] If the Timing Advance measurement is configured as specified in the current communication specification and the UE has successfully measured the Timing Advance for the indicated LTM target, the MAC entity may process the measured Timing Advance and consider the RACH-less LTM cell switch to be ongoing. If the MAC entity is associated with SCG, the MAC entity may indicate to upper layers to skip the Random Access procedure for this LTM cell switch. If TCI state information is included, the MAC entity may consider the SSB corresponding to the indicated TCI state as the one used for configured uplink grant selection for the initial uplink transmission towards the candidate cell for RACH-less LTM cell switch; and the MAC entity may indicate to lower layers the information regarding the TCI state information included in the LTM Cell Switch Command MAC CE.

[0045] The LTM Cell Switch Command MAC CE may be identified by MAC subheader with extended logical channel identifier (eLCID). FIG. 1 illustrates an example LTM cell switch command MAC CE. As shown in FIG. 1, the LTM Cell Switch Command MAC CE has a variable size with following fields:- R 102: Reserved bit, set to 0;- Target Configuration identifier (ID) 106: This field indicates the index of candidate target configuration to apply for LTM cell switch, corresponding to Itm-Candidateld minus 1 as specified in the current communication specification. The length of the field is 3 bits;- Timing Advance Command 108: This field indicates whether the TA is valid for the LTM target cell (i.e. the SpCell corresponding to the target configuration indicated by Target Configuration ID field). If the value of this field is set to FFF, this field indicates that no valid timing adjustment is available for the PTAG of the LTM target cell; Otherwise, this field indicates the index value TA used to control the amount of timing adjustment that the MAC entity has to apply in the current communication specification, and that the UE may skip the Random Access procedure for this LTM cell switch. The length of the field is 12 bits;- TCI state ID 110: This field indicates and activates the TCI state for the LTM target cell (i.e. the SpCell of the target configuration indicated by the Target Configuration ID field). The TCI state is identified by TCI-Stateldm Itm-DL-OrJointTCI- StateToAddModList as specified in the current communication specification. If the value of unifiedTCI-StateType in the configuration indicated by Target ConfigurationID field is joint, this field is for joint TCI state, otherwise, this field is for downlink TCI state. The length of the field is 7 bits;- UL TCI state ID 112: This field indicates and activates the uplink TCI state for the LTM target cell (i.e. the SpCell of the target configuration indicated by the Target Configuration ID field). The most significant bits of UL TCI state ID are considered as reserved bits and the remainder 6 bits indicate the TCI-UL-Stateldm Itm-UL-TCI- StatesToAddModList as specified in the current communication specification. This field is included if the value of unifiedTCI-StateType in the configuration indicated by Target Configuration ID field is separate. The length of the field is 8 bits;- C 114: This field indicates the presence of the contention-free Random Access Resources fields. If the value of this field is set to 1, the following fields are present, including Random Access Preamble index field, S / U field, SS / PBCH index field and PRACH Mask index field. If the value of this field is set to 0, Random Access Preamble index field, SS / PBCH index field and PRACH Mask index field are absent, and S / U field is considered as Reserved field.- S / U 116: This field indicates which UL carrier to transmit the PRACH of the contention-free Random Access Resources. If the value of this field is set to 1, SUL is used; otherwise, NUL is used. The length of the field is 1 bit;- Random Access Preamble index 118: This field indicates the Random Access Preamble index of the contention-free Random Access Resources. The length of the field is 6 bits;- synchronization signal (SS) / physical broadcast channel (PBCH) index 120: This field indicates the SS / PBCH that may be used to determine the RACH occasion for the PRACH transmission of the contention-free Random Access Resources. The length of the field is 6 bits;- PRACH Mask index 122: This field indicates the RACH occasion(s) associated with the SS / PBCH indicated by "SS / PBCH index" for the PRACH transmission of the contention-free Random Access Resources, referring to the rach-ConfigDedicated (if not provided otherwise to the rach-ConfigCommon) in the UL BWP configuration of firstActiveUplinkBWP-Id as specified in the current communication specification. The length of the field is 4 bits.

[0046] As discussed above, currently, a network (NW) cannot issue a UE to perform Random Access based LTM while the UE is configured with UE based timingmeasurement. Furthermore, the TAC field is always present in the LTM CSC MAC CE regardless of whether a RA procedure is used for the LTM cell switch. The UE based TA measurement may not be very reliable as the time when the UE performs the TA measurement is left up to UE implementation. Therefore, there is a need to enable such NW behaviour (enforcing RA based LTM). Moreover, since the UE is generally operating in a cell edge, a size of the LTM CSC MAC CE for triggering cell switch or handover needs to be optimized.

[0047] Example embodiments of the present disclosure provides a solution for determining availability of timing information for cell switch. In the solution, a first apparatus (for example, a terminal device) receives, from a second apparatus (for example, a network device), a command triggering cell switch towards a target cell. The first apparatus determines whether timing information is available in the command and then decodes the command based the determining. For example, if it is determined that the timing information is not present in the command, the first apparatus may decode the command without considering a field or bit related to the timing information.

[0048] In this way, a size of the command triggering cell switch may be optimized for some use cases. For example, if a RA procedure is used for the cell switch, the timing information may not be encoded in the command, thereby reducing the size of the command. Thus, the resource efficiency may be improved, and network capacity may be enhanced.

[0049] It is to be noted that although the issue is originating from the LTM cell switch, the proposed solution herein may be applied in general for different types of cell switch. In the following, some example embodiments will be described using the LTM cell switch as an example while the example embodiments herein can be applied in general for other types of cell switch.

[0050] FIG. 2 illustrates an example communication environment 200 in which example embodiments of the present disclosure may be implemented.

[0051] As shown in FIG. 2, the communication environment 200 includes a first apparatus 210 which may operate as a terminal device, and a second apparatus 220 which may operate as a network device. The second apparatus 220 provides at least one cell, for example, including a cell 222 and a cell 224, which may serve the first apparatus 210.

[0052] In the following, for the purpose of illustration, some example embodiments may be described with the first apparatus 210 operating as a terminal device (for example, a UE) and the second apparatus 220 operating as a network device (for example, a gNB). However, in some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other device.

[0053] In some example embodiments, if the first apparatus 210 is a terminal device and the second apparatus 220 is a network device, a link from the second apparatus 220 to the first apparatus 210 is referred to as a downlink (DL), and a link from the first apparatus 210 to the second apparatus 220 is referred to as an uplink (UL). In DL, the second apparatus 220 is a transmitting (TX) device (or a transmitter) and the first apparatus 210 is a receiving (RX) device (or a receiver). In UL, the first apparatus 210 is a TX device (or a transmitter) and the second apparatus 220 is a RX device (or a receiver).

[0054] Communications in the communication environment 200 may be implemented according to any proper communication protocol(s), including, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourth generation (4G), the fifth generation (5G), the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0055] It is to be understood that the number and types of apparatuses are shown in FIG. 1 for the purpose of illustration without suggesting any limitation. For example, the communication environment 200 may include any suitable number of terminal devices and network devices. One of the network devices may provide any number of cells.

[0056] In the communication environment 200, when the first apparatus 210 is moving, cell switch may be performed for the first apparatus 210. For example, the first apparatus 210 may move towards the cell 224. In this case, the cell 224 may be referred to as a target cell 224. The cell switch may be triggered by a command from the second apparatus 220. After the cell switch is completed, the target cell 222 may become a new serving cell for the first apparatus 210.

[0057] In some example embodiments, the command triggering the cell switch (also referred to as a cell switch command or CSC) may contain timing information for the cell switch. In an example, if a RA procedure is triggered for the cell, the timing information may not be present in the command. In this example, after the first apparatus 210 receives this command, the first apparatus 210 may decode the command to obtain other information than the timing information.

[0058] Some example implementations of the present disclosure will be described in detail below with reference to FIGS. 3 to 5.

[0059] FIG. 3 illustrates a signaling flow 300 for communication between the first apparatus 210 and the second apparatus 220 according to some example embodiments of the present disclosure.

[0060] As shown in FIG. 3, the second apparatus 220 transmits (310), to the first apparatus 210, a command (for example, an LTM cell switch command) triggering cell switch towards a target cell (for example, the cell 224). Correspondingly, the first apparatus 210 receives (320) this command from the second apparatus 220. The command may be transmitted in a MAC CE (for example, an LTM cell switch command MAC CE).

[0061] The first apparatus 210 determines (340) whether timing information is available in the command. For example, in the case that the cell switch command is transmitted (310) in the MAC CE, the first apparatus 210 may determine whether the timing information is encoded in the MAC CE.

[0062] The timing information may include information related to timing advance command (TAC). For example, the timing information includes bits or fields related to the TAC in the MAC CE that carries the cell switch command. Some example embodiments in this regard will be described with reference to FIG. 4A which illustrates an example LTM cell switch command MAC CE according to some example embodimentsof the present disclosure.

[0063] In some example embodiments, the timing information may include a TAC field (for example, timing advance command fields 402 and 404). Alternatively, or in addition, the timing information may include at least one octet (for example, Oct 4 406 and Oct 5 408) containing the TAC field (for example, the timing advance command fields 402 and 404). Alternatively, or in addition, the timing information may include an octet (for example, Oct 5 408) containing only TAC information bits (for example, the timing advance command field 404), or an octet (for example, Oct 4 406) containing a portion of TAC information bits (for example, the timing advance command field 402) and other information bits (for example, R fields 410). In some example embodiments, the timing information may include a part of an octet (for example, Oct 4 406) containing TAC information bits (for example, the timing advance command field 402) and some other information bits (for example, one or more R fields of the R fields 410).

[0064] In some example embodiments, as shown in FIG. 3, the second apparatus 220 indicate (330) whether the timing information is available in the command. Based on such indication (either explicit or implicit), the first apparatus 210 may determine (340) of the availability of the timing information in the command.

[0065] In some example embodiments, such an indication may be carried in the command. In an example, the command may contain contention free random access (CFRA) resource information to indicate that the timing information is absent in the command. In the case that the command is transmitted (310) in the MAC CE, the second apparatus 220 may indicate (330) whether the timing information is encoded in the MAC CE. Accordingly, based on a determination whether the CFRA resource information is present in the command, the first apparatus 210 may determine whether the timing information is timing information is available in the command.

[0066] In an example, if the CFRA resource information is present in the command, the first apparatus 210 may determine that the timing information is absent in the command. For example, if the CFRA resource information is present in the LTM CSC MAC CE (which may be determined based on a C field 412), the first apparatus 210 may determine that the TAC field 402 or 404 is not encoded (or not present) in the MAC CE.

[0067] In some example embodiments, if the CFRA resource information is absent inthe command, the first apparatus 210 may determine whether random access (RA) is or is to be triggered for the cell switch. If it is determined that the random access is or is to be triggered, the first apparatus 210 may determine that the timing information is absent in the command.

[0068] For example, if the CFRA resource information is not present in the LTM CSC MAC CE (which may be determined based on the C field 412), the first apparatus 210 may further determine whether Random Access is triggered for the LTM cell switch. If the Random Access is triggered for the LTM cell switch, the first apparatus 210 may determine that the TAC field (for example, the TAC field 402 or 404) is not encoded.

[0069] In this way, in the case that TAC value is something else than FFF while RA procedure is triggered, an error may be avoided by discarding the TAC fields or TAC information bits. Furthermore, signaling overhead for the command may be reduced.

[0070] The RA may be triggered by the network (for example, the second apparatus 220) or by the first apparatus 210 itself. In some example embodiments, the second apparatus 220 may trigger random access (RA) to indicate (330) that the timing information is absent in the command. In some example embodiments, at least one field and / or at least one bit in the MAC CE carrying the cell switch command may be used to trigger the RA. Some example embodiments in this regard will be described with reference to FIGS. 4A and 4B.

[0071] For example, a RA field 414 in FIG. 4A or a RA field 416 in FIG. 4B may indicate whether a Random Access procedure is to be initiated for the current LTM cell switch. If a value of this field is set to 1, the Random Access procedure may be triggered. In this case, the TAC field is absent in this LTM CSC MAC CE, as shown in FIG. 4B. If the value of this field is set to 0, the TAC fields 402 and 404 are present in this LTM CSC MAC CE, as shown in FIG. 4A.

[0072] Based the determining (340) whether timing information is available in the command, the first apparatus 210 decodes (350) the command. For example, if the first apparatus 210 determines (340) that the timing information is present in the command, the first apparatus 210 may decode (350) the timing information. If the first apparatus 210 determines (340) that the timing information is absent in the command, the first apparatus 210 may decode (350) the rest information in the command.

[0073] FIG. 5 shows an example process 500 of decoding the cell switch command atthe first apparatus 210 according to some example embodiments of the present disclosure. In this example, the cell switch is implemented as LTM cell switch.

[0074] As shown in FIG. 5, At block 510, the first apparatus 210 receives one or more LTM configurations for at least one cell including CFRA resources for at least one of the at least one cell (for example, the cell 222 and the cell 224). The configuration(s) may be transmitted via higher signaling such as RRC signaling.

[0075] At block 520, the first apparatus 210 receives a command triggering an LTM cell switch event towards a target cell (for example, the cell 224) of the at least one cell. The command for triggering the LTM cell switch event may be received in an MAC CE.

[0076] At block 530, the first apparatus 210 determines if a random access procedure is triggered for the LTM cell switch, based on the command. For example, the command may contain an indication (for example, the RA field 416 in FIG. 4B) to trigger the random access procedure.

[0077] At block 540, the first apparatus 210 determines whether the timing information is available in the command, based on the determining for the random access procedure (at block 530). For example, if it is determined the random access procedure is triggered or is to be triggered, the first apparatus 210 may determine that the timing information is absent. Otherwise, the first apparatus 210 may determine that the timing information is present.

[0078] At block 550, the first apparatus 210 decodes the LTM cell switch based on the determining at block 540.

[0079] An example implementation of the LTM Cell Switch Command MAC CE will be discussed below by taking 3GPP TS 38.321 vl8.0.0 as an example.Example Methods, Device and Medium

[0080] FIG. 6 shows a flowchart of an example method 600 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 may be described from the perspective of the first apparatus 210 in FIG. 2.

[0081] At block 610, the first apparatus 210 receives a command triggering cell switch towards a target cell. At block 620, the first apparatus 210 determines whether timinginformation is available in the command. At block 630, the first apparatus 210 decodes the command based on the determining.

[0082] In some example embodiments, based on CFRA resource information being present in the command, the first apparatus 210 may determine that the timing information is absent in the command.

[0083] In some example embodiments, based on CFRA resource information being absent in the command, the first apparatus 210 may determine whether random access is or is to be triggered for the cell switch. Based on determining that the random access is or is to be triggered, the first apparatus 210 may determine that the timing information is absent in the command.

[0084] In some example embodiments, the command may be received in a MAC CE. The first apparatus 210 may determine whether the timing information is encoded in the MAC CE.

[0085] In some example embodiments, the timing information may include at least one of a TAC field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

[0086] FIG. 7 shows a flowchart of an example method 700 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 700 may be described from the perspective of the second apparatus 220 in FIG. 2.

[0087] At block 710, the second apparatus 220 transmits, to the first apparatus 220, a command triggering cell switch towards a target cell. At block 720, the second apparatus 220 indicates, to the first apparatus 220, whether timing information is available in the command.

[0088] In some example embodiments, the command may contain CFRA resource information to indicate that the timing information is absent in the command.

[0089] In some example embodiments, the second apparatus 220 may trigger random access for the cell switch, to indicate that the timing information is absent in the command.

[0090] In some example embodiments, the command may be transmitted in a MAC CE.The second apparatus 220 may indicate, to the first apparatus 210, whether the timing information is encoded in the MAC CE.

[0091] In some example embodiments, the timing information may include at least one of: a TAC field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

[0092] All operations and features related to the first apparatus 210 and the second apparatus 220 as described above with reference to FIGS. 2 to 5 are likewise applicable to the methods 600 and 700 and have similar effects. For the purpose of simplification, the details will be omitted.

[0093] FIG. 8 is a simplified block diagram of a device 800 that is suitable for implementing example embodiments of the present disclosure. The device 800 may be provided to implement a communication device, for example, the first apparatus 210 or the second apparatus 220 as shown in FIG. 2. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processor 810, and one or more communication modules 840 coupled to the processor 810.

[0094] The communication module 840 is for bidirectional communications. The communication module 840 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 840 may include at least one antenna.

[0095] The processor 810 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0096] The memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 824, an electrically programmable read onlymemory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 822 and other volatile memories that may not last in the power-down duration.

[0097] A computer program 830 includes computer executable instructions that are executed by the associated processor 810. The instructions of the program 830 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 830 may be stored in the memory, e.g., the ROM 824. The processor 810 may perform any suitable actions and processing by loading the program 830 into the RAM 822.

[0098] The example embodiments of the present disclosure may be implemented by means of the program 830 so that the device 800 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 7. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0099] In some example embodiments, the program 830 may be tangibly contained in a computer readable medium which may be included in the device 800 (such as in the memory 820) or other storage devices that are accessible by the device 800. The device 800 may load the program 830 from the computer readable medium to the RAM 822 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The 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., RAM vs. ROM).

[0100] FIG. 9 shows an example of the computer readable medium 900 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 900 has the program 830 stored thereon.

[0101] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented infirmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0102] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non- transitory computer readable medium. The computer program product includes computerexecutable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0103] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0104] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0105] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0106] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

[0107] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

[0108] Various example embodiments of the techniques have been described. In addition to or as an alternative to the above, the following examples are described. The features described in any of the following examples may be utilized with any of the other examples described herein.

[0109] In an aspect, a first apparatus includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus (210) at least to: receive (320, 510, 610) a command triggering cell switch towards a target cell (224); determine (340, 540, 620) whether timing information is available in the command; and decode (350, 550, 630) the command based on the determining (340, 540, 620).

[0110] In some example embodiments, the at least one memory and the at least one processor cause the first apparatus (210) to: based on contention free random access (CFRA) resource information being present in the command, determine (340, 540, 620) that the timing information is absent in the command.

[0111] In some example embodiments, the at least one memory and the at least one processor cause the first apparatus (210) to: based on contention free random access (CFRA) resource information being absent in the command, determine whether random access is or is to be triggered for the cell switch; and based on determining that the random access is or is to be triggered, determine (340, 540, 620) that the timing information is absent in the command.

[0112] In some example embodiments, the command is received in a medium access control (MAC) control element (CE), and the at least one memory and the at least one processor cause the first apparatus (210) to: determine (340, 540, 620) whether the timing information is encoded in the MAC CE.

[0113] In some example embodiments, the timing information includes at least one of: a timing advance command (TAC) field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

[0114] In an aspect, a second apparatus (220) includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: transmit (310, 710), to the first apparatus (210), a command triggering cell switch towards a target cell (224); and indicate (330, 720), to the first apparatus (210), whether timing information is available in the command.

[0115] In some example embodiments, the command contains contention free random access (CFRA) resource information to indicate that the timing information is absent inthe command.

[0116] In some example embodiments, the at least one memory and the at least one processor cause the first apparatus (210) to: trigger random access for the cell switch, to indicate that the timing information is absent in the command.

[0117] In some example embodiments, the command is transmitted in a medium access control (MAC) control element (CE), and the at least one memory and the at least one processor cause the second apparatus (220) to: indicate (330, 720), to the first apparatus (210), whether the timing information is encoded in the MAC CE.

[0118] In some example embodiments, the timing information includes at least one of: a timing advance command (TAC) field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

[0119] In an aspect, a first apparatus (210) includes means for receiving (320, 510, 610) a command triggering cell switch towards a target cell (224); means for determining (340, 540, 620) whether timing information is available in the command; and means for decoding (350, 550, 630) the command based on the determining (340, 540, 620).

[0120] In some example embodiments, the means for determining includes: means for based on contention free random access (CFRA) resource information being present in the command, determining (340, 540, 620) that the timing information is absent in the command.

[0121] In some example embodiments, the means for determining includes: means for based on contention free random access (CFRA) resource information being absent in the command, determining whether random access is or is to be triggered for the cell switch; and means for based on determining that the random access is or is to be triggered, determining (340, 540, 620) that the timing information is absent in the command.

[0122] In some example embodiments, the command is received in a medium access control (MAC) control element (CE), and means for determining (340, 540, 620) whether the timing information is encoded in the MAC CE.

[0123] In some example embodiments, the timing information includes at least one of: a timing advance command (TAC) field (402, 404), at least one octet (406, 408) containingthe TAC field (402, 404), an octet containing (408) only TAC information bits (404), or an octet (406) containing a portion of TAC information bits (402) and other information bits (410).

[0124] In an aspect, a second apparatus includes means for transmitting (310, 710), to the first apparatus (210), a command triggering cell switch towards a target cell (224); and means for indicating (330, 720), to the first apparatus (210), whether timing information is available in the command.

[0125] In some example embodiments, the command contains contention free random access (CFRA) resource information to indicate that the timing information is absent in the command.

[0126] In some example embodiments, the first apparatus further includes: means for triggering random access for the cell switch, to indicate that the timing information is absent in the command.

[0127] In some example embodiments, the command is transmitted in a medium access control (MAC) control element (CE), and the means for indication includes means for indicating (330, 720), to the first apparatus (210), whether the timing information is encoded in the MAC CE.

[0128] In some example embodiments, the timing information includes at least one of a timing advance command (TAC) field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

[0129] In an aspect, a method includes: receiving (320, 510, 610) a command triggering cell switch towards a target cell (224); determining (340, 540, 620) whether timing information is available in the command; and decoding (350, 550, 630) the command based on the determining (340, 540, 620).

[0130] In an aspect, a method includes: transmitting (310, 710), to the first apparatus (210), a command triggering cell switch towards a target cell (224); and indicating (330, 720), to the first apparatus (210), whether timing information is available in the command.

[0131] In an aspect, a computer readable medium includes instructions stored thereon for causing an apparatus at least to perform the steps or operations as described above.

Claims

WHAT IS CLAIMED IS:

1. A first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive a command triggering cell switch towards a target cell; determine whether timing information is available in the command; and decode the command based on the determining.

2. The first apparatus of claim 1, wherein the at least one memory and the at least one processor cause the first apparatus to: based on contention free random access (CFRA) resource information being present in the command, determine that the timing information is absent in the command.

3. The first apparatus of claim 1, wherein the at least one memory and the at least one processor cause the first apparatus to: based on contention free random access (CFRA) resource information being absent in the command, determine whether random access is or is to be triggered for the cell switch; and based on determining that the random access is or is to be triggered, determine that the timing information is absent in the command.

4. The first apparatus of any of claims 1 to 3, wherein the command is received in a medium access control (MAC) control element (CE), and wherein the at least one memory and the at least one processor cause the first apparatus to: determine whether the timing information is encoded in the MAC CE.

5. The first apparatus of claim 4, wherein the timing information comprises at least one of: a timing advance command (TAC) field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

6. A second apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: transmit, to the first apparatus, a command triggering cell switch towards a target cell; and indicate, to the first apparatus, whether timing information is available in the command.

7. The second apparatus of claim 6, wherein the command contains contention free random access (CFRA) resource information to indicate that the timing information is absent in the command.

8. The second apparatus of claim 6, wherein the at least one memory and the at least one processor cause the second apparatus to: trigger random access for the cell switch, to indicate that the timing information is absent in the command.

9. The second apparatus of any of claims 6-8, wherein the command is transmitted in a medium access control (MAC) control element (CE), andwherein the at least one memory and the at least one processor cause the second apparatus to: indicate, to the first apparatus, whether the timing information is encoded in the MAC CE.

10. The second apparatus of claim 9, wherein the timing information comprises at least one of: a timing advance command (TAC) field, at least one octet containing the TAC field, an octet containing only TAC information bits, or an octet containing a portion of TAC information bits and other information bits.

11. A first apparatus comprising: means for receiving a command triggering cell switch towards a target cell; means for determining whether timing information is available in the command; and means for decoding the command based on the determining.

12. The first apparatus of claim 11, wherein the means for determining comprises: means for based on contention free random access (CFRA) resource information being present in the command, determining that the timing information is absent in the command.

13. The first apparatus of claim 11, wherein the means for determining comprises: means for based on contention free random access (CFRA) resource information being absent in the command, determining whether random access is or is to be triggered for the cell switch; and means for based on determining that the random access is or is to be triggered, determining that the timing information is absent in the command.

14. The first apparatus of any of claims 11-13, wherein the command is received in a medium access control (MAC) control element (CE), and wherein for determining comprises: means for determining whether the timing information is encoded in the MAC CE.

15. A second apparatus comprising: means for transmitting, to the first apparatus, a command triggering cell switch towards a target cell; and means for indicating, to the first apparatus, whether timing information is available in the command.

Images