WO2025209685A1 - Method for broadcast preamble configuration - Google Patents

Abstract

The present disclosure provides a source node. The source node can receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity. The aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells. The source node can allocate a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration. Each of the multiple target nodes may correspond to a respective cell of the multiple cells. The source node can transmit an indication of the preamble and the aligned PRACH configuration to the terminal device. The terminal device can transmit the preamble to multiple target nodes simultaneously based on the indication.

Description

METHOD FOR BROADCAST PREAMBLE CONFIGURATION

FIELD

[0001] Example embodiments of the present disclosure generally relate to the field of communications, and in particular, to devices, methods, apparatuses and a computer readable storage medium for transmitting a preamble towards two or more target cells at the same time

BACKGROUND

[0002] In communication systems such as New Radio (NR) or Long Term Evolution (LTE) systems, only one random access procedure is allowed per MAC entity at any given time. If a new random access procedure is initiated while another is ongoing, it is up to the implementation of a terminal device such as a user equipment (UE) to decide whether to continue with the ongoing procedure or start a new one. This may cause delays in the random access procedure because the network may not trigger two consecutive Physical Downlink Control Channel (PDCCH) orders.

[0003] Therefore, it would be desirable to have a solution that takes into account at least some of the issues discussed above, as well as other possible issues.

SUMMARY

[0004] In general, example embodiments of the present disclosure relate to determining measurement requirements on higher priority carriers.

[0005] In a first aspect, there is provided a source node. The source node comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the source node to at least: receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; allocate a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and transmit an indication of the preamble and the aligned PRACH configuration to the terminal device. [0006] In a second aspect, there is provided a target node. The target node comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the target node to at least: receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and determine that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

[0007] In a third aspect, there is provided a terminal device. The terminal device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device to at least: receive an indication of a preamble; and transmit the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

[0008] In a fourth aspect, there is provided a method. The method comprises receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device.

[0009] In a fifth aspect, there is provided a method. The method comprises receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

[0010] In a sixth aspect, there is provided a method. The method comprises receiving an indication of a preamble; and transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

[0011] In a seventh aspect, there is provided an apparatus. The apparatus comprises means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; means for allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and means for transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device.

[0012] In an eighth aspect, there is provided an apparatus. The apparatus comprises means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and means for determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

[0013] In an ninth aspect, there is provided an apparatus. The apparatus comprises means for receiving an indication of a preamble; and means for transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

[0014] In a tenth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to any one of the above fourth to sixth aspects.

[0015] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0017] FIG. 1 illustrates an example of a network environment in which example embodiments of the present disclosure can be implemented;

[0018] FIG. 2 illustrates that a terminal device is moving along the cell border of two neighbor cells, according to some embodiments of the present disclosure;

[0019] FIG. 3 illustrates an aligned physical random access channel (PRACH) configuration, according to some embodiments of the present disclosure;

[0020] FIG. 4 illustrates a process flow according to some embodiments of the present disclosure;

[0021] FIG. 5 illustrates a process flow according to some embodiments of the present disclosure;

[0022] FIG. 6 illustrates a flow chart of method according to some embodiments of the present disclosure;

[0023] FIG. 7 illustrates a flow chart of method according to some embodiments of the present disclosure;

[0024] FIG. 8 illustrates a flow chart of method according to some embodiments of the present disclosure;

[0025] FIG. 9 illustrates a simplified block diagram of a device that is suitable for implementing some example embodiments of the present disclosure; and

[0026] FIG. 10 illustrates a block diagram of an example of a computer readable medium in accordance with some example embodiments of the present disclosure.

[0027] Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION [0028] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

[0029] 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.

[0030] 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.

[0031] It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including”, when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/ or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” 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.

[0033] As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuits (such as in analog and/or digital circuits) 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 (e.g., 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 (for example, firmware) for operation, but the software may not be present when it is not needed for operation.

[0034] 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.

[0035] As used herein, the term “cellular network” refers to a network operating in accordance with any suitable radio access technology defined by standards, such as Long Term Evolution (LTE), LTE- Advanced (LTE-A), new radio 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 of a cellular network may be performed according to any suitable communication protocols, including, but not limited to, the fourth generation (4G), 4.5G, the future fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various cellular networks. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0036] As used herein, the term “network device” refers to any device in a cellular network via which a terminal device accesses a data network and receives services exposed by other network devices of the cellular network. In some examples, a network device may comprise or implement a network function of a 5^th generation communication system (5GS) (e.g., a core network) of a cellular network. In some examples, the network devices may be located at the RAN of the 5GS. The network device may be part of a satellite, a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico node, and so forth, depending on the applied terminology and technology. A gNB may include a centralized unit CU and one or more distributed DUs. Femto and Pico nodes are small base stations with a small coverage area.

[0037] The term “terminal device” refers to a device of a communication system of a cellular network, such as a 5^th generation communication system (5GS) that may be capable of wireless (e.g., radio) communication with a NR-RAN of the 5GS). By way of example rather than limitation, a terminal device may also be referred to as a wireless communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). Examples of a terminal device include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (for example, remote surgery), an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0038] FIG. 1 illustrates an example of a network environment 100 in which example embodiments of the present disclosure can be implemented. The environment 100 may be a part of a communication network and comprise a plurality of terminal devices and network devices, such as a terminal device 110, and network devices 120, 130 and 140. As an example, the terminal device 110 may be implemented as a User Equipment (UE), and the network devices 120, 130 and 140 may be implemented as an eNB, gNB or a base station (BS). The network devices 120 may communicate the terminal device 110 via network environment 100.

[0039] In some embodiments, the terminal device 110 may be communicating with the network device 120 in a source cell associated with the network device 120, as indicated by the bi-directional solid line arrow. Here the network device 120 may be a source node. The terminal device 110 may move closer to the network devices 130 and 140, as indicated by the dotted line arrow. Thus, the terminal device 110 may start a handover procedure to a target cell 1 associated with the network device 130 or a target cell 2 associated with the network device 140. Here the network devices 130 and 140 may be target node 1 and target node 2, respectively.

[0040] In some embodiments, the terminal device 110 may obtain timing advance (TA) from both the network devices 130 and 140 to obtain uplink synchronization with both network devices 130 and 140. The terminal device 110 may not know which target cell it will handover to initially, but if the terminal device 110 can obtain early uplink synchronization with both network devices 130 and 140, the terminal device 110 may start the handover procedure to either target cell 1 or target cell 2 with less delay in the random access procedure. The terminal device 110 may transmit one preamble to both network devices 130 and 140 at the same time. The solution in the present disclosure can reduce the delay of obtaining timing advance (TA) from both the network devices 130 and 140, and can also reduce the interruption time caused by the terminal device 110 transmitting the preamble to multiple network devices.

[0041] Although the terminal device 110 and the network devices 120, 130 and 140 are described in the communication environment 100 of FIG. 1, embodiments of the present disclosure may equally apply to any other suitable communication devices in communication with one another. That is, embodiments of the present disclosure are not limited to the exemplary scenarios of FIG. 1. In this regard, it is noted that although the terminal device is schematically depicted as a mobile phone and the network devices 120, 130 and 140 are schematically depicted as a base station in FIG. 1, it is understood that these depictions are exemplary in nature without suggesting any limitation. In other embodiments, the terminal device 110 and the network devices 120, 130 and 140 may be any other communication devices, for example, any other wireless communication devices.

[0042] It is to be understood that the particular number of various communication devices and the particular number of various communication links as shown in FIG. 1 is for illustration purpose only without suggesting any limitations. The communication environment 100 may include any suitable number of communication devices and any suitable number of communication links for implementing embodiments of the present disclosure. In addition, it should be appreciated that there may be various wireless as well as wireline communications (if needed) among all of the communication devices.

[0043] FIG. 2 illustrates a scenario 200 that a terminal device is moving along the cell border of two neighbor cells, according to some embodiments of the present disclosure. As shown, target cell 1 and target cell 2 are two neighbor cells (e.g., the two cells are close to each other and have a cell border), and the terminal device 110 may handover to either of them. Target cell 1 may be associated with target node 1 (network deice 130), and target cell 2 may be associated with target node 2 (network device 140). The network device 130 is broadcasting beams such as synchronization signal blocks (SSBs) in target cell 1, and the network device 140 is broadcasting beams such as synchronization signal blocks (SSBs) in target cell 2. In one example, SSB 1 and SSB 2 are broadcasted in target cell 2 on the cell border of target cell 2, and SSB 3, SSB 4 and SSB 5 are broadcasted in target cell 1 on the cell border of target cell 1. And the terminal device 110 may move along the cell border of the two neighbor cells and may handover to one of the two neighbor cells. For example, the terminal device may move to locations 202, 204 or 206, as shown in FIG. 2.

[0044] FIG. 3 illustrates an aligned physical random access channel (PRACH) configuration 300, according to some embodiments of the present disclosure. A network entity such as Operations and Management (0AM) may broadcast the aligned physical random access channel (PRACH) configuration for multiple cells. The source node (network device 120), target node 1 (network device 130) and target node 2 (network device 140) can all receive the aligned PRACH configuration from the network entity.

[0045] In some embodiments, the aligned PRACH configuration 300 indicates PRACH occasions that overlap in time and frequency for the multiple cells. As shown in FIG. 3, PRACH occasion (RO) 0 for target cell 1 and RO 0 for target cell 2 indicate the same time and frequency (i.e., overlap in time and frequency). Similarly, RO 1 for target cell 1 and RO 1 for target cell 2 indicate the same time and frequency. PRACH occasions can indicate to the network devices to receive the preamble transmitted from the terminal device. For example, the network device 130 can receive the preamble transmitted from the terminal device 110 in RO 0 and RO 1, and the network device 140 can receive the preamble transmitted from the terminal device 110 in RO 0 and RO 1 too. The target cells 1 and 2 may be operating on the same carrier.

[0046] In some embodiments, the aligned PRACH configuration 300 includes a mapping between beams such as SSBs and the PRACH occasions for each of the multiple cells such as target cells 1 and 2. As shown in FIG. 3, the mapping indicates how many SSBs are mapped to each RO. For example, SSB 3 and SSB 4 are mapped to RO 0 for target cell 1, and SSB 4 and 5 are mapped to RO 1 for target cell 1. Similarly, SSB 1 and SSB 2 are mapped to RO 0 for target cell 2, and SSB 1 and 2 are mapped to RO 1 for target cell 2.

[0047] In some embodiments, the mapping indicates that the network device can use the time and frequency resources of a certain RO and use the receive beamforming of the mapped SSBs to receive and decode the preamble transmitted by the terminal device. For example, the network device 130 can use the time and frequency resources of RO 0 and use SSB3 or SSB 4 to receive and decode the preamble transmitted by the terminal device 110. Similarly, the network device 140 can use the time and frequency resources of RO 0 and use SSB1 or SSB 2 to receive and decode the preamble transmitted by the terminal device 110. [0048] In some embodiments, the aligned PRACH configuration 300 includes the mapping between beams such as SSBs and the PRACH occasions for each of the multiple cells. The mapping is arranged in such a way that when the terminal device 110 is on the cell border of target cell 1 and the cell border of target cell 2 at the same time, the neighboring SSBs indicate the same frequency and time space in the radio frames. For example, the terminal device 110 may start moving along the cell border of the two target cells at location 202, and transmit a preamble to network devices 130 and 140 simultaneously at location 202. Because at location 202, as shown in FIG. 2, SSB 3 and SSB 1 are neighboring SSBs which may be the strongest SSBs to the terminal device 110, the network device 130 should decode the preamble using receive beamforming of SSB3, and the network device 140 should decode the preamble using the receive beamforming of SSB1. As shown in FIG. 3, the mapping is arranged such that if the terminal device 110 transmits the preamble at location 202 using the time and frequency resources on the upper part of RO 0, the network device 130 in target cell 1 will indeed use receive beamforming of SSB3 to decode the preamble, and the network device 140 in target cell 2 will indeed use receive beamforming of SSB1 to decode the preamble. Upper part of an RO indicates preambles from index 1 to a value X. And the lower part indicates the preambles from value X to value 64 or another value that is the maximum number of preambles in a RACH occasion.

[0049] Similarly, the mapping is arranged such that if the terminal device 110 transmits the preamble at location 204 using the time and frequency resources on the upper part of RO 1, the network device 130 in target cell 1 will indeed use receive beamforming of SSB4 to decode the preamble, and the network device 140 in target cell 2 will indeed use receive beamforming of SSB1 to decode the preamble. If the terminal device 110 transmits the preamble at location 206 using the time and frequency resources on the lower part of RO 1, the network device 130 in target cell 1 will indeed use receive beamforming of SSB5 to decode the preamble, and the network device 140 in target cell 2 will indeed use receive beamforming of SSB2 to decode the preamble. As described here, the PRACH configuration for the multiple cells is aligned. The PRACH occasion (e.g., RO 0) for using a neighboring SSB (e.g., SSB 3) for target cell 1 and the PRACH occasion (e.g., RO 0) for using a neighboring SSB (e.g., SSB 1) for target cell 2 overlap in time and frequency. [0050] FIG. 4 illustrates a process flow 400 according to some embodiments of the present disclosure. At block 402, a network entity such as 0AM coordinates to allocate a broadcast PRACH pool that overlaps in frequency and time in multiple cells (e.g., target cells 1 and 2). In some embodiments, the 0AM may coordinate to allocate a broadcast PRACH pool in a phase for configuring the initial PRACH configuration, which may be configured using the coverage map of the multiple cells. In some embodiments, the 0AM may configure the broadcast PRACH pool of the neighbor cells to the radio access network node (e.g., the source node, target nodes 1 and 2) and indicate for which neighbor cells the allocated broadcast PRACH pool is. In some embodiments, each broadcast PRACH pool is linked with multiple neighbor cells. The broadcast PRACH pool or broadcast PRACH configuration may correspond to the aligned PRACH configuration as described above.

[0051] In some embodiments, the source node, target nodes 1 and 2 may all receive the aligned PRACH configuration for multiple cells (e.g., target cells 1 and 2) from the 0AM. The aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells. The aligned PRACH configuration includes a mapping between beams such as SSBs and the PRACH occasions for each of the multiple cells. In some embodiments, a respective one of the beams is used by the terminal device or UE to transmit the preamble to a corresponding one of the multiple target nodes.

[0052] In some embodiments, the mapping is between a set of the beams (e.g., not all the beams) and the PRACH occasions for each of the multiple cells. For example, the mapping of PRACH occasions can be limited to a set of SSBs (e.g., towards cell 1 from cell 2, SSB1, SSB2). The terminal device 110 or UE may be expected to come from only a limited SSBs. The term coming here refers to UE accessing the cell after handover using these beams.

[0053] In some embodiments, the target node 1 may receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity such as 0AM. The aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells. The aligned PRACH configuration includes a mapping between beams such as SSBs and the PRACH occasions for each of the multiple cells. The multiple cells may include a serving cell (target cell 1) of the target node 1 and a neighbor cell (target cell 2) adjacent to the serving cell. The target node 1 may determine that a first beam (e.g., SSB 3) of the beams for the serving cell and a second beam (e.g., SSB 1) of the beams for the neighbor cell are mapped to a same PRACH occasion (e.g., the upper part of RO 0) of the PRACH occasions based on the mapping.

[0054] In some embodiments, the aligned PRACH configuration is different for different combinations of the multiple cells. For example, combination of different neighbor cells may have a separate PRACH pool. Each cell border may be configured with a separate PRACH pool. For example, the 0AM may allocate separate aligned PRACH configuration for target cell 1 and target cell 2 with a cell border, and may allocate another PRACH configuration for other target cells.

[0055] In some embodiments, radio access network (RAN) configuration update can be used to update broadcast PRACH configuration. For example, at blocks 404 and 406, the source node can update the aligned PRACH configuration of target node 1 and target node 2, respectively. In other embodiments, the target node 1 or target node 2 can update the aligned PRACH configuration of the source node. The RAN configuration update can be used to update cell specific broadcast PRACH pool for early TA acquisition.

[0056] In some embodiments, at block 408, the source node can determine to allocate the preamble from cell specific broadcast PRACH pool. In some embodiment, the source node 120 can determined to allocate a preamble for the terminal device or UE 110 to transmit to multiple target nodes 130 and 140 simultaneously based on the aligned PRACH configuration. Each of the multiple target nodes may correspond to a respective cell of the multiple cells (e.g., target cells 1 and 2). In some embodiments, at block 410, the source node can provide RRC reconfiguration, measurement configuration, broadcast PRACH configuration and preamble allocation for early TA to the terminal device or UE 110.

[0057] In some embodiments, the source node 120 can transmit an indication of the preamble and the aligned PRACH configuration to the terminal device 110. In some embodiments, the source node 120 can transmit the aligned PRACH configuration or the mapping separately to the terminal device 110. In some embodiments, the source node 120 can determine a PRACH occasion of the PRACH occasions in the aligned PRACH configuration for the terminal device to transmit the preamble. In some embodiments, the source node 120 can obtain measurements of the beams from the terminal device, determine a PRACH occasion of the PRACH occasions for the terminal device to transmit the preamble based on the measurements; and allocate the preamble for the terminal device to transmit to the multiple target nodes in the PRACH occasion. In some embodiments, the source node 120 can configure the terminal device 110 with multiple aligned PRACH configurations.

[0058] In some embodiments, at block 412, the terminal device or UE 110 may notify the source node 120 that the RRC reconfiguration is complete. The terminal device or UE 110 can receive the broadcast PRACH configuration. In one embodiment, the terminal device can receive the information of which candidate cells this broadcast PRACH pool is linked to and a separate SSB to RO mapping for each candidate cell. In one embodiment, the PRACH configuration can be configured with low layer triggered mobility (LTM) configuration. In another embodiment, the PRACH configuration can be configured with RACHless handover (HO) configuration. In another embodiment, the PRACH configuration can be configured for PSCell addition procedure. In another embodiment, the PRACH configuration can be configured for Scell addition procedure.

[0059] FIG. 5 illustrates a process flow 500 according to some embodiments of the present disclosure. At block 502, an event is triggered for the UE to handover to either target cell 1 or 2. At block 504, the UE transmits measurement report to the source node. For example, the measurement report may include beam 2 of target cell 1 and beam 4 of target cell 2 to the source node. At block 506, early TA acquisition may be triggered. At block 508, the source node may indicate to target nodes 1 and 2 over which beam the UE is transmitting the preamble. In some embodiments, the source node may indicate the respective one of the beams to the corresponding one of the multiple target nodes. For example, the source node may indicate to target node 1 that over beam 2 of target cell 1 the UE is transmitting the preamble to target node 1, and may indicate to target node 2 that over beam 4 of target cell 2 the UE is transmitting the same preamble to target node 2.

[0060] In some embodiments, at block 510, the source node indicate or transmit the PRACH occasion and/or an identity (ID) of the aligned PRACH configuration to the terminal device. The source node can transmit one or more identities of the SSBs to the terminal device. The multiple cells may include two cells (e.g., target cells 1 and 2) and the source node can transmit a pair of SSBs for the two cells to the terminal device. In some embodiments, the source node can use UE measurements to determine the PRACH occasion that overlaps for both cells, and the source node can indicate the broadcast PRACH configuration identity and PRACH occasion to the UE. The exact PRACH occasion to be used can be indicated to the UE with an SSB mask and a preamble. In other embodiments, the source node can indicate the preamble transmission to the UE along with the candidate PSCells.

[0061] In some embodiments, at block 512, the terminal device or UE 110 can determine a PRACH occasion of the PRACH occasions for the terminal device to transmit the preamble. The terminal device or UE 110 can determine the PRACH occasion based on one or more of the following: an identity of the preamble; the indication of the aligned PRACH configuration; an identity of the aligned PRACH configuration; or a pair of the beams.

[0062] The UE can measure the target cell SSBs, in some cases simultaneously, to determine the PRACH occasion to use. The UE can transmit the preamble in the PRACH occasion that indicates the correct beam for each target cells, e.g., beam 2 of cell 1 and beam 4 of cell 2.

[0063] At block 514, the terminal device or UE 110 can transmit the preamble to target nodes 1 and 2 at the same time using the determined PRACH occasion and the correct beams. At blocks 516 and 518, target nodes 1 and 2 can estimate TA for the UE respectively. At block 520, the UE can perform RACHless handover to either one of the two target cells. UE can also use this procedure for early TA acquisition procedure or TCI state activation.

[0064] FIG. 6 illustrates a flowchart of method 600 according to some embodiments of the present disclosure. At block 602, the method comprises receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells. At block 604, the method comprises allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells. At block 606, the method comprises transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device. The method 600 may be implemented by the source node or network device 120.

[0065] In some embodiments, an apparatus capable of performing the method 600 (for example, the network device 120) may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0066] In some embodiments, the apparatus comprises means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; means for allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and means for transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device.

[0067] FIG. 7 illustrates a flowchart of method 700 according to some embodiments of the present disclosure. At block 702, the method comprises receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell. At block 704, the method comprises determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping. The method 700 may be implemented by the target node (e.g., the network device 130 or 140).

[0068] In some embodiments, an apparatus capable of performing the method 700 (for example, the network device 130 or 140) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0069] In some embodiments, the apparatus comprises means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and means for determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

[0070] FIG. 8 illustrates a flowchart of method 800 according to some embodiments of the present disclosure. At block 802, the method comprises receiving an indication of a preamble. At block 804, the method comprises transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells. The method 800 may be implemented by the terminal device 110.

[0071] In some embodiments, an apparatus capable of performing the method 800 (for example, the terminal device 110) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0072] In some embodiments, the apparatus comprises means for receiving an indication of a preamble; and means for transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

[0073] FIG. 9 illustrates a simplified block diagram of a device 900 that is suitable for implementing some example embodiments of the present disclosure. The device 900 may be provided to implement a communication device, for example, the terminal device 110 and the network device 120, 130 and 140 as shown in FIG. 1. As shown, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processor 910, and one or more communication modules 940 coupled to the processor 910.

[0074] The communication module 940 is for bidirectional communications. The communication module 940 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

[0075] The processor 910 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 300 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.

[0076] The memory 920 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) 924, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 922 and other volatile memories that will not last in the power-down duration.

[0077] A computer program 930 includes computer executable instructions that are executed by the associated processor 910. The program 930 may be stored in the ROM 924. The processor 910 may perform any suitable actions and processing by loading the program 930 into the RAM 922.

[0078] The embodiments of the present disclosure may be implemented by means of the program 930 so that the device 900 may perform any process of the disclosure as discussed with reference to FIGs 4-8. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0079] In some example embodiments, the program 930 may be tangibly contained in a computer readable medium which may be included in the device 900 (such as in the memory 920) or other storage devices that are accessible by the device 900. The device 900 may load the program 930 from the computer readable medium to the RAM 922 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

[0080] FIG. 10 illustrates a block diagram of an example of a computer readable medium 1000 in accordance with some example embodiments of the present disclosure. The computer readable medium 1000 has the program 930 stored thereon. It is noted that although the computer readable medium 1000 is depicted in form of CD or DVD in FIG. 10, the computer readable medium 1000 may be in any other form suitable for carry or hold the program 930.

[0081] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0082] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods or processes 400-800 as described above with reference to FIGs 4-8. 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.

[0083] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0084] In the context of the present disclosure, the computer program codes 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. [0085] 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 readonly memory (EPROM or Flash memory), an optical fiber, a portable compact disc readonly memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. 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).

[0086] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0087] Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A source node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the source node to at least: receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; allocate a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and transmit an indication of the preamble and the aligned PRACH configuration to the terminal device.

2. The source node of claim 1, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, wherein a respective one of the beams is used by the terminal device to transmit the preamble to a corresponding one of the multiple target nodes.

3. The source node of claim 2, wherein the source node is further caused to transmit the mapping separately to the terminal device.

4. The source node of claim 2 or 3, wherein the beams include synchronization signal blocks (SSBs).

5. The source node of any of claims 2-4, wherein the mapping includes a mapping between a set of the beams and the PRACH occasions for each of the multiple cells.

6. The source node of any of claims 2-5, wherein the source node is further caused to indicate the respective one of the beams to the corresponding one of the multiple target nodes.

7. The source node of any of claims 1-6, wherein the aligned PRACH configuration is different for different combinations of the multiple cells.

8. The source node of any of claims 1-7, wherein the source node being caused to allocate the preamble includes being caused to determine a PRACH occasion of the PRACH occasions for the terminal device to transmit the preamble.

9. The source node of any of claims 2-7, wherein the source node being caused to allocate the preamble includes being caused to: obtain measurements of the beams from the terminal device; determine a PRACH occasion of the PRACH occasions for the terminal device to transmit the preamble based on the measurements; and allocate the preamble for the terminal device to transmit to the multiple target nodes in the PRACH occasion.

10. The source node of claim 8, wherein the source node is further caused to indicate the PRACH occasion and/or an identification of the aligned PRACH configuration to the terminal device.

11. The source node of claim 1, wherein the source node is further caused to update the aligned PRACH configuration of the multiple target nodes.

12. The source node of claim 1, wherein the source node is further caused to configure the terminal device with multiple aligned PRACH configurations.

13. The source node of claim 4, wherein the source node is further caused to transmit one or more identifications of the SSBs to the terminal device.

14. The source node of claim 4, wherein the multiple cells include two cells, and the source node is further caused to transmit a pair of SSBs for the two cells to the terminal device.

15. A target node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the target node to at least: receive an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and determine that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

16. The target node of claim 15, wherein a respective one of the beams is used by a terminal device to transmit a preamble to a corresponding one of the multiple target nodes.

17. The target node of claim 15 or 16, wherein the target node is further caused to update the aligned PRACH configuration of a source node.

18. A terminal device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device to at least: receive an indication of a preamble; and transmit the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

19. The terminal device of claim 18, wherein the terminal device is further configured to receive an aligned physical random access channel (PRACH) configuration for multiple cells from a source node, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells

20. The terminal device of claim 19, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, wherein the terminal device being caused to transmit the preamble includes being caused to transmit the preamble using a respective one of the beams to a corresponding one of the multiple target nodes.

21. The terminal device of claim 20, wherein the terminal device is further caused to determine a PRACH occasion of the PRACH occasions for the terminal device to transmit the preamble.

22. The terminal device of claim 21, wherein the terminal device being caused to determine the PRACH occasion includes being caused to determine the PRACH occasion based on one or more of the following: an identification of the preamble; the indication of the aligned PRACH configuration; an identification of the aligned PRACH configuration; or a pair of the beams.

23. A method comprising: receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device.

24. A method comprising: receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

25. A method comprising: receiving an indication of a preamble; and transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

26. An apparatus comprising: means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells; means for allocating a preamble for a terminal device to transmit to multiple target nodes simultaneously based on the aligned PRACH configuration, each of the multiple target nodes corresponding to a respective cell of the multiple cells, and means for transmitting an indication of the preamble and the aligned PRACH configuration to the terminal device.

27. An apparatus comprising: means for receiving an aligned physical random access channel (PRACH) configuration for multiple cells from a network entity, wherein the aligned PRACH configuration indicates PRACH occasions that overlap in time and frequency for the multiple cells, wherein the aligned PRACH configuration includes a mapping between beams and the PRACH occasions for each of the multiple cells, and wherein the multiple cells include a serving cell of the target node and a neighbor cell adjacent to the serving cell; and means for determining that a first beam of the beams for the serving cell and a second beam of the beams for the neighbor cell are mapped to a same PRACH occasion of the PRACH occasions based on the mapping.

28. An apparatus comprising: means for receiving an indication of a preamble; and means for transmitting the preamble to multiple target nodes simultaneously based on the indication, each of the multiple target nodes corresponding to a respective cell of the multiple cells.

29. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method of any of claims 23 - 25.