EQUIPAMENTO DE USUÁRIO E MÉTODO RELACIONADO

Description

1 / 47 USER EQUIPMENT AND RELATED METHOD Separated from order BR 112022015491-7, filed on February 6, 2020. CAMPO

[001] The modalities of this disclosure generally relate to the field of telecommunications and, in particular, to methods, devices, apparatus and computer-readable storage media for random access in a communication system. BACKGROUND

[002] Various wireless communication systems have been developed and are being developed to meet a growing demand for communication services. Before receiving communication service from a wireless communication system, a terminal device must establish a connection to a network.

[003] A random access (RA) procedure refers to a procedure for a terminal device to establish or re-establish a connection with a network device, such as a Next Generation B Node (gNB). Contention-free random access (CFRA) or contention-based random access (CBRA) can be employed to perform the RA procedure. CFRA refers to the use of dedicated RA resources, while CBRA refers to the use of shared RA resources. Once the connection has been established and / or re-established, the network device can allocate resources to a specific terminal device to support further communication with the network device. SUMMARY

[004] In general, example embodiments of the present disclosure provide a solution for random access.

[005] In one aspect, a first device is provided. The Petition 870250068581, dated 04 / 08 / 2025, page 12 / 76 2 / 47 The first device comprises at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to determine whether a contention-free random access resource is allocated from a second device for a first random access type, according to the determination that the contention-free random access resource is allocated, compare a target transport block size corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first random access type, and perform random access to the second device based on a result of the comparison.

[006] In a second aspect, a method is provided. The method comprises determining, on a first device, whether a contention-free random access resource is allocated from a second device for a first random access type; according to a determination that the contention-free random access resource is allocated, comparing a destination transport block size corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first random access type; and performing random access on the second device based on a result of the comparison.

[007] In a third aspect, a first apparatus is provided. The first apparatus comprises means for determining whether a contention-free random access resource is allocated from a second apparatus for a first type of random access; according to a determination that the contention-free random access resource is allocated, comparing a block size Petition 870250068581, dated 04 / 08 / 2025, page 13 / 76 3 / 47 of destination transport corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first type of random access; and perform random access to the second device based on a comparison result.

[008] In a fourth aspect, a computer-readable medium is provided. The computer-readable medium comprises program instructions for making an apparatus perform at least the method according to any of the second aspect above.

[009] It should be understood that the summary section is not intended to identify the main or essential attributes of the features of this disclosure, nor is it intended to be used to limit the scope of this disclosure. Other attributes of this disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[010] Some examples of modalities will now be described with reference to the attached drawings, in which:

[011] Fig. 1 illustrates an example communication system in which example embodiments of the present disclosure can be implemented;

[012] Fig. 2 illustrates a signaling flow for random access according to some example modalities of the present disclosure;

[013] Fig. 3 illustrates a flowchart of a method implemented in a first device according to some example embodiments of the present disclosure;

[014] Fig. 4 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of this disclosure; and Petition 870250068581, dated 04 / 08 / 2025, p. 14 / 76 4 / 47

[015] Fig. 5 illustrates a block diagram of an example computer-readable medium according to some example embodiments of the present disclosure.

[016] Throughout the drawings, the same or similar reference numbers represent the same or similar element. DETAILED DESCRIPTION

[017] The principle of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and assist those skilled in the art in understanding and implementing this disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described in this disclosure can be implemented in several ways different from those described below.

[018] In the description and claims that follow, unless defined otherwise, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by a person skilled in the art to which this disclosure pertains.

[019] References in this disclosure to “a modality”, “an example modality”, “an exemplary modality” and the like, indicate that the modality described may include a particular attribute, structure or feature, but it is not necessary that each modality includes the particular attribute, structure or feature. Furthermore, such phrases do not necessarily refer to the same modality. Additionally, when a particular attribute, structure or feature is described in connection with a modality, it is understood that it is within the competence of a person skilled in the art to affect such attribute, structure or feature in connection with other modalities, whether this is explicitly stated or not. Petition 870250068581, dated 04 / 08 / 2025, p. 15 / 76 5 / 47

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

[021] The terminology used in this disclosure is intended to describe particular modalities only and is not intended to limit the modalities of example. As used in this disclosure, the singular forms a, an and the are intended to include 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 in this disclosure, specify the presence of established attributes, elements and / or components etc., but do not exclude the presence or addition of one or more other attributes, elements, components and / or combinations thereof.

[022] As used in this application, the term circuit set may refer to one, more, or all of the following: (a) hardware-only circuit set implementations (such as analog-only and / or digital-only circuit set implementations) and (b) combinations of hardware and software circuit sets, such as (as applicable): (i) a combination of analog hardware circuit(s) and / or Petition 870250068581, dated 04 / 08 / 2025, page 16 / 76 6 / 47 digital with software / firmware and (ii) any parts of the hardware processor(s) with software (including digital signal processor(s), software and memory(ies) that work together to make a device, such as a mobile phone or server, perform various functions) and (c) a set of hardware circuit(s) and / or processor(s), such as microprocessor(s) or a part of a microprocessor(s), that require software (e.g., firmware) for operation, but the software may not be present when it is not required for operation.

[023] This definition of circuit assembly 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 circuit assembly also covers an implementation of merely a hardware or processor circuit assembly (or multiple processors) or part of a hardware or processor circuit assembly and its accompanying software and / or firmware. The term circuit assembly also covers, for example and if applicable to the particular claim element, a baseband integrated circuit assembly or processor integrated circuit assembly for a mobile device or a similar integrated circuit assembly in a server, a cellular network device or other computing or networking device.

[024] As used in this disclosure, the term “communication network” refers to a network that follows 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), Narrowband Internet of Things (NB-IoT), and so forth. Furthermore, communications between a terminal device and Petition 870250068581, dated 04 / 08 / 2025, page 17 / 76 7 / 47 A network device in the communication network may perform in accordance with any suitable generation communication protocols, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, future fifth-generation (5G) communication protocols and / or any other protocols currently known or to be developed in the future. The embodiments of this disclosure may be applied in various communication systems. Given the rapid development in communications, there will naturally also be future-type communication technologies and systems with which this disclosure may be incorporated. It should not be seen as limiting the scope of this disclosure only to the aforementioned system.

[025] As used in this disclosure, the term network device refers to a node in a communication network via which a terminal device accesses the network and receives services from it. 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, and so forth, depending on the terminology and technology applied.

[026] The term terminal device refers to any end device that is capable of wireless communication. As an example, instead of limitation, a terminal device may 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 is not limited to, a cell phone, a mobile phone, a smartphone, phones of Petition 870250068581, dated 04 / 08 / 2025, p. 18 / 76 8 / 47 Voice over IP (VoIP), cordless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), laptops, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, vehicle-mounted wireless terminal devices, wireless terminals, mobile stations, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, smart devices, wireless equipment on customer premises (CPE), an Internet of Things (IoT) 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 automated processing chain context),A consumer electronic 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.

[027] Fig. 1 shows an example communication system 100 in which example embodiments of the present disclosure can be implemented. The system 100 includes a first device 110 and a second device 120 that can communicate with each other. In this example, the first device 110 is illustrated as a terminal device and the second device 120 is illustrated as a network device serving the terminal device. Thus, the service area of ​​the second device 120 is called cell 102.

[028] It should be understood that the number of first and second devices is for illustrative purposes only, without suggesting any limitations. The 100 communication system may include any suitable number of first and second devices. Petition 870250068581, dated 04 / 08 / 2025, page 19 / 76 9 / 47 according to devices adapted to implement modalities of the present disclosure. Although not shown, it will be appreciated that one or more additional devices may be located in cell 102 and served by the second device 120.

[029] Communications in the 100 communication system may be implemented in accordance with any suitable communication protocol, including, but not limited to, first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G) and fifth-generation (5G) cellular communication protocols and the like, wireless local area 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.Furthermore, communication may utilize any suitable 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 Duplexing (FDD), Time Division Duplexing (TDD), Multiple Input Multiple Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform Dispersive OFDM (DFT-s-OFDM), and / or any other technologies currently known or to be developed in the future.

[030] In the 100 communication system, the first device 110 and the second device 120 can communicate data and control information with each other. In the case where the first device 110 is a terminal device and the second device 120 is a network device, a link from the second device 120 to the first device 110 is referred to as a downlink (DL), while a link from the first device 110 to the second device 120 is referred to as an uplink (UL). In DL, the Petition 870250068581, dated 04 / 08 / 2025, page 20 / 76 10 / 47 second device 120 is a transmitting (TX) device (or a transmitter) and the first device 110 is a receiving (RX) device (or a receiver). In UL, the first device 110 is a TX device (or a transmitter) and the second device 120 is an RX device (or a receiver).

[031] Normally, in order to communicate data with the second device 120, the first device 110 can initiate an RA procedure to establish a connection with the second device 120.The RA procedure can be triggered by various events, such as an initial access to the second 120 device from an idle status, a connection re-establishment procedure, arrival of DL or UL data during connected mode when the UL synchronization status is unsynchronized, arrival of UL data during connected mode when there are no physical uplink control channel (PUCCH) resources available for a scheduling request (SR), SR failure, a request for radio resource control (RRC) upon synchronous reconfiguration (e.g., handover), transition from an inactive radio resource control (RRC) state, establishing time alignment for a secondary timing advance group (TAG), a request for other system information (SI), a beam failure recovery (BFR), and so on.In some cases, the first device 110 may have to attempt to transmit an AR preamble several times before the second device 120 can successfully detect the AR preamble.

[032] Contention-free random access (CFRA) or contention-based random access (CBRA) may be employed. CFRA refers to the use of dedicated RA resources, while CBRA refers to the use of shared RA resources. CBRA can lead to a situation where multiple endpoint devices attempt to access the network device through their respective Petition 870250068581, dated 04 / 08 / 2025, p. 21 / 76 11 / 47 RA procedures use the same RA resource and therefore require contention resolution. CFRA is performed based on a specific random access resource assigned by the network device, without contention with other endpoint devices.

[033] An RA resource may, for example, include at least one RA preamble (or an abbreviated preamble) and may possibly include an uplink time-frequency resource for message transmission. Depending on the messages required for exchange between the first device 110 and the second device 120, RA procedures may include slow-type RA, fast-type RA, or similar.

[034] An example of slow-type RA includes a four-step RA (or 4-step RA) in which the first device 110 transmits an RA preamble in a first message (sometimes represented as “MSG1”) to the second device 120, and subsequent steps are then performed depending on whether the RA procedure is contention-based (i.e., CBRA) or contention-free (i.e., CFRA). For example, if a 4-step CBRA is performed, at least three additional messages are exchanged between the first device 110 and the second device 120. If a 4-step CFRA is performed, the first device 110 may transmit an additional message in response to MSG1. Example procedures for 4-step CBRA and 4-step CFRA will be presented below.

[035] An example of fast-type RA includes a two-step RA (or 2-step RA) in which the first device 110 transmits an RA preamble and payload to the second device 120 in a message (sometimes represented as “MSGA”). The second device 120 typically transmits a reply message (sometimes represented as “MSGB”) to MSGA in the contention-based procedure or CFRA. The MSGB may include a Petition 870250068581, dated 04 / 08 / 2025, p. 22 / 76 12 / 47 response(s) for contention resolution, a fallback indication(s), or a rollback indication. As such, the time spent completing 2-step AR is generally less than completing 4-step AR. Fast-type RA has recently been proposed to enable fast access from a first device (e.g., a terminal device) to a second device (e.g., a network device) in certain cases. In some cases, 2-step CFRA is supported for handover.

[036] It was agreed that the first device 110 can select the RA type (e.g., fast RA or slow RA, or 2-step RA or 4-step RA), for example, at the beginning of the random access procedure based on the network configuration. In some implementations, if CFRA features are not configured, a signal quality threshold (such as an RSRP threshold) is used by the first device 110 to select between fast type RA (e.g., 2-step type RA) and slow type RA (e.g., 4-step type RA). In some implementations, if CFRA features for slow type RA are configured, the UE will select slow type RA, and if CFRA features for fast type RA are configured, the UE will select fast type RA. The second network device 120 may not configure CFRA features for both fast type RA and slow type RA simultaneously for a Bandwidth Share (BWP).

[037] In some implementations, for RA in a cell configured with a supplementary uplink (SUL), the second device 120 can explicitly signal which carrier to use (UL or SUL). Otherwise, the first device 110 can select the SUL carrier if and only if the measured DL quality is below a broadcast threshold. The first device 110 can perform carrier selection before selecting between the plurality of RA types. The RSRP threshold for selecting between the RA Petition 870250068581, dated 04 / 08 / 2025, page 23 / 76 The 13 / 47 fast type and the slow type RA can be configured separately for UL and SUL. After carrier selection, uplink transmissions of the RA procedure remain on the selected carrier.

[038] In some implementations where carrier aggregation (CA) is configured, an RA procedure with a fast type RA (e.g., 2-step type RA) can be configured to be performed only in a primary cell (PCell) or in a secondary primary cell (PSCell). For an RA procedure with a slow type RA (e.g., 4-step type RA), the first three steps of the CBRA can always occur in the PCell, while contention resolution (the fourth step) can be cross-scheduled by the PCell. The three steps of a CFRA initiated in the PCell remain in the PCell.The CFRA in a secondary cell (SCell) can only be initiated by the second 120 device to establish the timing advance for a secondary TAG, in which the procedure is initiated by the second 120 device with a Physical Downlink Control Channel (PDCCH) order that is sent in a scheduling cell of an activated SCell of the secondary TAG, the preamble transmission occurs in the indicated SCell and the RAR occurs in the PCell.

[039] During an RA procedure, the first device 110 monitors a response from the second device 120 within a configured window after the RA preamble is transmitted (e.g., in MSG1 in 4-step RA) or after the RA preamble and payload are transmitted (e.g., in MSGA in 2-step RA). For CFRA, upon receiving the response from the second device 120, the first device 110 terminates the RA procedure. For 2-step CBRA, if contention resolution is successful upon receiving the response from the second device 120, the first device 110 terminates the procedure. Petition 870250068581, dated 04 / 08 / 2025, page 24 / 76 14 / 47 RA. Otherwise, the first 110 device may need to switch between slow RA type and fast RA type (e.g., from 2-step RA to 4-step RA) or fallback from one RA type to another RA type (e.g., from fast RA type to slow RA).

[040] For example, if the 2-step RA procedure is not successfully completed even after transmitting MSGA multiple times (“N”), the first device 110 can switch to 4-step RA. The number of times N can be configured by the second device 120. If the second device 120 has received only the preamble part of the MSGA, it can send a fallback indication to the first device 110 based on the preamble identification. In the case of fallback, the first device 110 can perform the MSG3 transmission and monitor the contention resolution. If the contention resolution is not successful after (re)transmission(s) of MSG3, the first device 110 can revert to MSGA transmission. If the 2-step RA is not successfully completed after multiple MSGA transmissions and no fallback indication can be received from the second device 120, the first device 110 can be configured to switch to 4-step CBRA.

[041] Normally, to perform an RA procedure, a first device can select a preamble for transmission. In the 4-step RA procedure, a first device can select between groups A and B of Random Access Preambles based on a condition of a radio connection with a second device and data available in the buffer or alternatively, based only on the size of a Common Control Channel (CCCH) Service Data Unit (SDU) in the buffer. For example, as specified in 3GPP TS 38.321, a UE can select between groups A and B of Random Access Preambles according to the Petition 870250068581, dated 04 / 08 / 2025, page 25 / 76 15 / 47 specifications in Table 1 as below. Table 1 5.1.2 Random Access Resource Selection The MAC entity must: (. . .) 2> If Msg3 has not yet been transmitted: 3> If Random Access Preambles group B is configured: 4> If the potential size of Msg3 (UL data available for transmission plus MAC header and, when necessary, MAC CEs) is greater than ra-Msg3SizeGroupA and the path loss is less than PCMAX (from the Server Cell performing the Random Access Procedure) preambleReceivedTargetPower - msg3-DeltaPreamble messagePowerOffsetGroupB; or 4> If the Random Access procedure was initiated for the CCCH logical channel and the size of the CCCH SDU plus the MAC subheader is greater than ra-Msg3SizeGroupA: 5> Select group B of Random Access Preambles. 4> otherwise: 5> Select group A of Random Access Preambles. 3> otherwise: 4> Select group A of Random Access Preambles. (. . .)

[042] Based on the specifications above, a threshold for data available in the buffer (e.g., the ra-Msg3SizeGroupA parameter) and a threshold for path loss (e.g., the threshold represented by “PCMAX (of the Server Cell performing the Random Access Procedure) Petition 870250068581, dated 04 / 08 / 2025, p. 26 / 76 16 / 47 preambleReceivedTargetPower - msg3-DeltaPreamble messagePowerOffsetGroupB”) are used to determine the selection between Random Access Preamble Group B and Random Access Preamble Group A. As such, upon detecting a preamble from Random Access Preamble Group B or Random Access Preamble Group A from the UE, the network device can approximately determine the amount of data to be sent and the condition of the radio connection with the UE, based on which the network device can then determine the resources allocated to the UE.

[043] It was recently agreed to introduce a plurality of preamble groups for the fast-type RA, for example, the 2-step RA, and the same selection method used in the 4-step RA (e.g., comparisons based on the thresholds ra-Msg3SizeGroupA and “PCMAX (of the Server Cell performing the Random Access Procedure) preambleReceivedTargetPower - msg3-DeltaPreamble messagePowerOffsetGroupB”) can be applied to select between the preamble groups for the fast-type RA. It is also agreed that a transport block size (TB size) granted in the slow-type RA (e.g., the 4-step RA) should be the same as the TB size configured for the fast-type RA if the first device switches from the fast-type RA to the slow-type RA.

[044] However, there will be problems if the same selection method used in the 4-step RA is always applied in the case where CFRA resources are allocated to the fast RA, as the first device may switch between fast RA and slow RA. In a possible solution, it is proposed to allow the second device to configure, along with the CFRA resource allocation, which preamble group should always be used by the first device if the CBRA Petition 870250068581, dated 04 / 08 / 2025, p. 27 / 76 17 / 47 is triggered for an RA procedure. This solution requires extra signaling by the second device. As an alternative, it could be specified which group to always use in the case where CFRA resources are allocated, but the CBRA is triggered for an RA procedure. For example, a first preamble group is always used, as it is always configured for the first device, or a second preamble group is always used when configured. This workaround limits the flexibility of the second device by using the TB size for the first or second groups to allocate CFRA resources.

[045] According to example embodiments of this disclosure, a solution is provided for performing RA. In this solution, if a CFRA resource is allocated from a second device to a first device for a certain type of RA (for example, a fast type RA), the first device compares a destination transport block size (TB) corresponding to the CFRA resource with a TB size configured for a preamble group available for that type of RA. The first device performs RA for the second device based on the result of the comparison. As such, depending on whether the TB size for the CFRA matches the TB size configured for the available preamble group, the first device can correctly perform preamble group selection or selection between CFRA and CBRA without requiring extra signaling from the second device.The second device is not subject to any strict limitations on resource allocation, as the first device can still perform the selection under different conditions.

[046] The example embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Reference is now made to Fig. 2, which shows a signaling flow 200 according to Petition 870250068581, dated 04 / 08 / 2025, page 28 / 76 18 / 47 some example embodiments of the present disclosure. For discussion purposes, signaling flow 200 will be described with reference to Fig. 1. Signaling flow 200 may involve the first device 110 and the second device 120, as illustrated in Fig. 1.

[047] In signaling flow 200, the first device 110 determines 210 whether a CFRA resource is allocated from the second device 120 for a certain type of RA (sometimes referred to as a “first type of RA” for ease of description in this disclosure).

[048] There may be a plurality of RA types to be used by the first device 110, and different RA types require different message procedures between the first device 110 and the second device 120. RA types may include one or more relatively fast RA types and one or more relatively slow RA types. A fast RA type generally requires fewer messages exchanged between the two devices than a slow RA type. An example of a fast RA type is a so-called 2-step RA, which typically requires two messages exchanged between the first device 110 and the second device 120 to complete the RA. An example of a slow RA type is a so-called 4-step RA, which typically requires up to four messages exchanged between the first device 110 and the second device 120 to complete the CBRA, or fewer messages in the CFRA.

[049] In some example embodiments, the first device 110 may use the information on whether a CFRA resource is allocated to the fast type RA (the 2-step type RA in a specific example) to decide how the RA is performed as described below.

[050] The second device 120 can allocate one or more CFRA resources to one or more types of AR that are potentially selected by the first. Petition 870250068581, dated 04 / 08 / 2025, p. 29 / 76 19 / 47 device 110. Typically, a CFRA resource is assigned by the second device 120 for a specific RA type. When using the CFRA resource, the first device 110 is able to implement CFRA without contention with other devices. A CFRA resource may include a dedicated preamble assigned to the first device 110. In some example embodiments, the CFRA resource may also include a time-frequency resource for transmitting the dedicated preamble. Generally, a preamble is transmitted on a physical random access channel (PRACH), and therefore the time-frequency resource may thus be a PRACH resource. The time-frequency resource may not be specifically allocated via a dynamic resource assignment from the second device 120, but may be implicitly determined, for example, from other configuration information, such as an index of the dedicated RA preamble.If the CFRA resource is allocated for fast-type RA (such as 2-step type RA) that requires a preamble and payload to be transmitted in one message (i.e., MSGA), the CFRA resource may also include a time-frequency resource for payload transmission from the first 110 device. The payload may be transmitted on a shared physical uplink (PUSCH) channel in some instances, and therefore the time-frequency resource may be a PUSCH resource. The payload may include identification of the first 110 device, control information, and / or data.

[051] If the second device 120 allocates 205 the CFRA resource for the first type of RA to the first device 110 and the first device 110 can determine that the CFRA resource is allocated, the first device 110 further compares 220 a TB size corresponding to the allocated CFRA resource with a TB size configured for a group of preambles available for the first type of RA. The TB size corresponding to Petition 870250068581, dated 04 / 08 / 2025, page 30 / 76 The 20 / 47 CFRA resource indicates a payload size that can be transmitted to the second 120 device using the CFRA resource. In 2-step RA, the CFRA resource is allocated for MSGA transmission, and the TB size indicates the payload size transmitted via PUSCH in MSGA.

[052] The first 110 device can be configured by the second 120 device with one or more preamble groups for CBRA with the first type of RA. The first 110 device is allowed to select a preamble from one of the preamble groups for transmission to the second 120 device. In addition to the preambles, the second 120 device can configure a TB size for each of the preamble groups and one or more pre-configured parameters to select each of the preamble groups (such as a threshold for data available in the buffer (represented as ra-MsgASizeGroupA) and parameters related to a path loss threshold (such as PCMAX, preambleReceivedTargetPower, msg3DeltaPreamble, and messagePowerOffsetGroupB parameters).The TB size configured for a preamble group indicates a payload size that can be transmitted to the second 120 device along with a preamble in that preamble group (e.g., in MSGA for 2-step RA). In CBRA, the payload can be transmitted using a PUSCH feature.

[053] In some example embodiments, for a fast type RA, the first device 110 can be configured with Random Access Preambles group A and Random Access Preambles group B. Respective TB sizes can be configured for Random Access Preambles group A and Random Access Preambles group B. It would be desirable that more than two preamble groups for a certain type of RA can also be configured for the first device 110.

[054] To make the description easier, the TB size that is compared with the Petition 870250068581, dated 04 / 08 / 2025, page 31 / 76 The target TB size (21 / 47) is sometimes referred to as the first TB size, and the associated preamble group is sometimes referred to as the first preamble group. By comparing the target TB size with the first TB size, the first device (110) performs a 230 RA for the second device (120) based on a comparison result.

[055] When performing AR, the first device 110 can perform preamble group selection to perform AR or selection between CFRA and CBRA at least based on the comparison result. Some example embodiments related to AR performed based on the comparison result will be described in detail below.

[056] In some example embodiments, the first 110 device selects a preamble group to perform RA based on the result of the comparison. Specifically, if the first 110 device determines that the target TB size matches the first TB size configured for the first preamble group, the first 110 device can perform RA based on the first preamble group. In other words, when a CFRA resource is allocated, the first 110 device can use the preamble group having the TB size matching the target TB size to decide how RA is performed, for example, how CBRA is performed. As used in this disclosure, the term matching means that the two sizes are equal or substantially equal to each other.In one example embodiment, if the first 110 device can be configured with a plurality of preamble groups for the first type of RA, the first 110 device can compare a plurality of TB sizes configured for the plurality of respective preamble groups (including the first TB size) with the target TB size corresponding to the allocated CFRA resource. A. Petition 870250068581, dated 04 / 08 / 2025, p. 32 / 76 22 / 47 comparison can be performed for the plurality of the respective preamble groups one by one. By allowing the first 110 device to select the preamble group with the configured TB size corresponding to the target TB size of the CFRA resource, the first 110 device can easily switch between CFRA and CBRA.

[057] Note that in example embodiments of this disclosure, using the TB sizes configured for the first RA type to be compared with the target TB size does not mean that the first 110 device will always select the first RA type to perform RA. If the first 110 device can choose between the first RA type and one or more other RA types (such as a second RA type), the first 110 device can still follow the RA type selection criteria to determine which RA type is selected to use.

[058] If the first TB size matches the target TB size and the first RA type is used, the first device 110 can perform a CBRA attempt with the first RA type based on the first matching preamble group. In some examples, the first preamble group with the matching TB size might be Random Access Preamble Group A or Random Access Preamble Group B for a 2-step type RA. When performing the CBRA attempt with the first RA type, the first device 110 can select a preamble from the first preamble group and transmit the selected preamble (e.g., in PRACH) and payload of the first TB size (e.g., in PUSCH) to the second device 120.

[059] If the first TB size matches the target TB size and a different RA type (for example, a second RA type) different from the first RA type is used (for example, if the procedure of Petition 870250068581, dated 04 / 08 / 2025, p. 33 / 76 23 / 47 If a 2-step RA attempt fails even after multiple MSGA transmissions (“N” times), the first device 110 can switch to 4-step RA. The first device 110 can determine if a CBRA attempt with the second type of RA can be performed and perform the CBRA attempt with the second type of RA using a preamble group that is configured for the second type of RA and corresponds to the first preamble group for the first type of RA. In some examples, the first preamble group with the corresponding TB size might be Random Access Preamble Group A or Random Access Preamble Group B for a 2-step RA type, and the preamble group that corresponds to the first preamble group for a 2-step RA type might be Random Access Preamble Group A or Random Access Preamble Group B for a 4-step RA, respectively.When attempting a CBRA with the second RA type, the first device 110 can select a preamble from the preamble group that is configured for the second RA type and corresponds to the first preamble group for the first RA type, and transmit the selected preamble (e.g., in PRACH) to the second device 120. Some example modes in which the second RA type is used will be described in more detail below.

[060] In some example embodiments, if the first 110 device determines that the target TB size does not match the TB sizes configured for any other preamble groups, the first 110 device may decide to perform RA based on a predetermined group of preambles (sometimes referred to as a “third preamble group”) that is available for the first type of RA. For example, the first 110 device may be configured with two preamble groups (such as Random Access Preamble Group A and Random Access Preamble Group B). Petition 870250068581, dated 04 / 08 / 2025, p. 34 / 76 Using 24 / 47 Random Access), the first device 110 can first determine if the target TB size matches a TB size configured for Random Access Preamble Group B. If a mismatch is found (i.e., the target TB size does not match the TB size configured for Random Access Preamble Group B), the first device 110 can directly decide to perform RA based on Random Access Preamble Group A. Alternatively, the first device 110 can compare the TB size configured for Random Access Preamble Group A with the target TB size and can use Random Access Preamble Group B to perform RA if a mismatch is found.

[061] Because the TB sizes for the preamble groups can be configured by the second device 120 for the first device 110 before the CFRA resource is allocated to the first device 110, in some example embodiments, the second device 120 can allocate the CFRA resource based on the TB sizes configured for the preamble groups, so that the target TB size of the allocated CFRA can always match a TB size configured for one of the preamble groups.

[062] In some example embodiments, if the CFRA resource is not allocated to the first 110 device and the first 110 device decides to perform RA with the first type of RA, the first 110 device may select the preamble group for CBRA of the first type of RA based on the configured parameters, including the threshold for data available in the buffer (such as ra-MsgASizeGroupA) and parameters related to a threshold for path loss (such as PCMAX, preambleReceivedTargetPower, msg3DeltaPreamble, messagePowerOffsetGroupB), in the same way as the method Petition 870250068581, dated 04 / 08 / 2025, p. 35 / 76 25 / 47 selection specified for the 4-step RA.

[063] In some example embodiments, such as the selection of preamble groups is generally required when CBRA is triggered, in the case of the CFRA resource being determined to be allocated, before the comparison of TB sizes, the first 110 device can determine whether transmission over the allocated CFRA resource is available. In the case where transmission on the allocated CFRA resource is available, the first 110 device can perform CFRA with the first type of RA using the allocated CFRA resource. In the case where transmission on the allocated CFRA resource is not available, the first 110 device determines that CBRA should be performed and thus can initiate the comparison of TB sizes to determine which preamble group is used for CBRA. The availability of transmission on the allocated CFRA resource may depend on the availability of a beam associated with the CFRA resource.The availability of a beam may be subject to, for example, the received reference signal power (RSRP) of the beam being above a configured RSRP threshold. If no beam is available for the CFRA resource, the first 110 device may determine that the allocated CFRA resource cannot be used for transmission.

[064] In some example embodiments, the selection of the preamble group and the corresponding TB size are determined before the start of the first CBRA attempt. Thus, before comparing the TB sizes, the first device 110 can determine if a previous CBRA attempt has been performed. If no previous CBRA attempt has been performed, the first device 110 can start comparing the TB sizes to determine which preamble group is used for the CBRA.

[065] Note that in the example modes related to the selection of the preamble group, the first RA attempt of the first device 110 Petition 870250068581, dated 04 / 08 / 2025, page 36 / 76 26 / 47 may be CFRA using the allocated CFRA resource or CBRA as described above. The scope of this disclosure is not limited in this respect.

[066] As an example, selection between preamble groups according to some example embodiments of this disclosure can be performed in a medium access control (MAC) entity of the first device 110. The operations related to selection between preamble groups can be summarized in Table 2 below. Table 2 5.1.2a Random Access Resource Selection for 2-Step Random Access The MAC entity must: (. . .) 1> If MSGA has not yet been transmitted: 2> If the Random Access Preambles for 2-Step RA group B is configured: 3> If contention-free 2-step Random Access Resources are explicitly provided by the RRC: 4> If the transport block size associated with the contention-free 2-step Random Access Resources matches the transport block size of the MSGA associated with group B of 2-step Random Access Resource Preambles: 5> Select group B of Random Access Preambles. 4> otherwise: 5> Select group A of Random Access Preambles. 3> Otherwise, if the potential MSGA payload size (UL data available for transmission plus MAC header and, where necessary, MAC CEs) is greater than [ra-MsgASizeGroupA] and the path loss is less than Petition 870250068581, dated 04 / 08 / 2025, page 37 / 76 27 / 47 PCMAX (from the Server Cell performing the Random Access Procedure) - [preambleReceivedTargetPower] - [msgA-DeltaPreamble] [messagePowerOffsetGroupB]; or 3> If the Random Access procedure was initiated for the CCCH logical channel and the size of the CCCH SDU plus the MAC subheader is greater than [ra-MsgASizeGroupA]: 4> Select group B of Random Access Preambles. 3> otherwise: 4> Select group A of Random Access Preambles. 2> otherwise: 3> Select group A of Random Access Preambles. 1> Otherwise (i.e., MSGA is being relayed): 2> Select the same group of Random Access Preambles that was used for the Random Access Preamble transmission attempt corresponding to the first MSGA transmission. (. . .)

[067] As mentioned above, the first 110 device can determine the selection of a second different RA type to perform RA. The result of the comparison between the target TB size and the first TB size configured for the first group of preambles for the first RA type can still be used to guide how the first 110 device performs a CBRA attempt with the second RA type. In some example embodiments, the first 110 device can determine to perform RA with the second RA type by detecting a trigger to switch from the first RA type to the second RA type. A trigger to switch from the first RA type to the second RA type can be, for example, multiple RA attempts (CFRA or CBRA). Petition 870250068581, dated 04 / 08 / 2025, page 38 / 76 28 / 47 or both) with the first type of AR reaching a predetermined limit. For example, before selecting the second type of AR, the first device 110 may have performed several CFRA attempts or several CBRA attempts with the first type of AR. As an example, for a fast AR, such as 2-step AR, if the first device 110 transmits MSGA (including a preamble and payload) to the second device 120 a maximum of N times and does not receive a response from the second device 120, the first device 110 may switch from 2-step AR to another type of AR, such as 4-step AR. It would be appreciated if other triggers for switching from the first type of AR to the second type of AR were also possible.

[068] In some example embodiments, if a switching trigger from the first RA type to the second RA type is detected, the first device 110 can determine whether a preamble group (sometimes referred to as a “second preamble group” for ease of description) for the second RA type is available to the first device 110 (e.g., configured by the second device 120 for the first device 110). Depending on the availability of the second preamble group, the first device 110 can decide how the RA proceeds.

[069] The first type of RA can be a fast RA type, such as a 2-step RA type, and the second type of RA can be a slow RA type, such as a 4-step RA type. There can be a plurality of preamble groups for the second type of RA, and the second device 120 can configure one or more of the plurality of preamble groups for the first device 110. In the example where the second type of RA requires that the preamble and payload be transmitted in separate messages (MSG1 and MSG3), the allowed TB size for payload transmission is Petition 870250068581, dated 04 / 08 / 2025, p. 39 / 76 29 / 47 dynamically configured by the second device 120. In particular, the second device 120 allocates a resource for payload transmission in a concession after successfully decoding the preamble from the first device 110. Thus, from the side of the first device 110, the allowed TB size for payload transmission in the second type of RA cannot be predicted.

[070] The second group of preambles for the second type of RA can be determined as corresponding to the first group of preambles for the first type of RA. That is, the first group of preambles for the first type of RA with the TB size corresponding to the target TB size can be used by the first device 110 to determine which group of preambles for the second type of RA is selected when performing CBRA with the second type of RA. There may be correspondence between groups of preambles for the respective first and second types of RA, which may be known by both the first and second devices 110, 120. For example, the Random Access Preambles group A for the fast type of RA may correspond to the Random Access Preambles group a for the slow type of RA, and the Random Access Preambles group B for the fast type of RA may correspond to the Random Access Preambles group B.In some example scenarios, when performing RA based on a certain group of preambles for the second type of RA, the second device 120 can allocate to the first device 110 a resource corresponding to the same TB size as that configured for the corresponding group of preambles for the first type of RA. For example, if a first TB size is configured for a first group of preambles for the first type of RA previously, upon receiving a preamble selected from a second group of preambles of the second type of RA, the second... Petition 870250068581, dated 04 / 08 / 2025, page 40 / 76 Device 120 (30 / 47) can allocate a resource that can be used to transmit the first TB size to the first device (110).

[071] In some example embodiments, if the second group of preambles is available, the first device 110 may perform an additional CBRA attempt with the second type of RA based on the second group of preambles, for example, by sending a selected preamble from the second group of preambles. If the second group of preambles is unavailable, the first device 110 may determine that the RA for the second device 120 fails. That is, the first device 110 is not allowed to switch to the second type of RA in this case. For example, in such a case, a Random Access problem may be indicated by the MAC entity of the first device 110 to higher layers, such as the RRC layer.

[072] As a specific example, the first device 110 can be configured with Random Access Preamble Groups A and B for the fast RA type and only Random Access Preamble Group A for the slow RA type. If the first device 110 performed a CBRA attempt with the fast RA type based on its Random Access Preamble Group B according to the TB size comparison as described above, this means that the TB size used is the TB size (equal to the target TB size) configured for the Random Access Preamble Group B of the first RA type.In this case, the first device 110 is not allowed to switch to the slow RA type because transmitting a preamble from the Random Access Preambles group A available for the slow RA type to the second device 120 could trigger the second device 120 to allocate a resource with a TB size different from the TB size configured for the Random Access Preambles group B of the first RA type. Petition 870250068581, dated 04 / 08 / 2025, p. 41 / 76 31 / 47

[073] In some example embodiments, the first device 110 can only determine whether Random Access Preamble group B for slow RA type is available because Random Access Preamble group A for slow RA type is always configured for the first device 110.

[074] As an example, the determination of the switching between the first and second RA types according to some example embodiments of the present disclosure can be performed on a MAC entity of the first device 110. The corresponding operations can be summarized in statements in Table 3 as below. Table 3 5.1.4a MSGB reception and contention resolution for 2-step random access Once the MSGA is transmitted, regardless of the possible occurrence of a measurement gap, the MAC entity must: (...) 1> If msgB -ResponseWindow times out and the Random Access Response Reception was not considered successful based on the descriptions above: 2> increment PREAMBLE_TRANSMISSION_COUNTER by 1; 2> if PREAMBLE_TRANSMISSION_COUNTE R = preambleTransMax + 1: 3> Indicate a Random Access problem to the upper layers; 3> If this Random Access procedure was triggered for an SI request: 4> Consider this Random Access procedure completed unsuccessfully. 2> If the Random Access procedure is not completed: 3> Select a random pullback time according to a Petition 870250068581, dated 04 / 08 / 2025, page 42 / 76 32 / 47 uniform distribution between 0 and the PREAMBLE_BACKOFF; 3> if msgATransMax is configured and PREAMBLE_TRANSMISSION_COUNTER = msgATransMax +1: 4> Set the RA_TYPE to 4-stepRA; 4> If the Msg3 buffer is empty: 5> Obtain the PDU MAC to transmit from the MSGA buffer and store it in the Msg3 buffer; 4> If contention-free two-step Random Access Resources were explicitly provided by the RRC: 5> if the Random Access Preambles B group for 2-step RA is configured; and 5> if the Random Access Preambles group was not selected in this Random Access procedure; and 5> If the transport block size associated with the contention-free 2-step Random Access Resources matches the transport block size of the MSGA associated with the 2-step Random Access Resource Preambles B group: 6> If the Random Access Preambles B group for 4-step RA is configured: 7> Select the Random Access Preambles group B. 6> otherwise: 7> This indicates a Random Access problem to the upper layers. 5> otherwise: 6> Select group A of Random Access Preambles. 4> Flush the HARQ buffer used for MAC PDU transmission into the MSGA buffer. 4> Perform the Access Resource selection procedure Petition 870250068581, dated 04 / 08 / 2025, page 43 / 76 33 / 47 Random, as specified in subclause 5.1.2. 3> otherwise: 4> Perform the Random Access Resource selection procedure for 2-step random access (see subclause 5.1.2a) after the fallback time. The MAC entity can stop msgB-ResponseWindow once the reception of the Random Access Response is considered successful.

[075] As mentioned above, in some example embodiments, a result of the comparison of TB sizes can be used for selection between CFRA and CBRA, for example, when CFRA can be performed. In such example embodiments, if the first device 110 has made a CBRA attempt based on the first group of preambles for the first type of RA (due to the unavailability of a beam with an allocated CFRA resource) and the CBRA attempt fails, and if the beam with the allocated CFRA resource becomes available for transmission, the first device 110 can decide to compare the target TB size corresponding to the allocated CFRA resource with the first TB size configured for the first group of preambles in 230 in the signaling stream 200.If the target TB size does not match the size of the first TB, the first 110 device may not perform a CFRA attempt using the CFRA feature because the size of the buffered blocks on the first 110 device does not match the target TB size, even if the corresponding CFRA feature could be used based on beam availability (the beam could be a Synchronization Signal Block (SSB) beam or a Channel State Information Reference Signal (CSI-RS) beam). The first 110 device may be restricted to CBRA in the subsequent RA procedure. The first 110 device may instead continue to perform an attempt. Petition 870250068581, dated 04 / 08 / 2025, p. 44 / 76 34 / 47 additional CBRA with the first RA type based on the first preamble group and the first TB size, for example, when transmitting a selected preamble from the first preamble group and payload of the first TB size to the second device 120.

[076] The first preamble group in this case can be selected for use according to the selection methods based on the preconfigured parameters, instead of based on comparing the TB sizes configured for the available preamble groups with the target TB size. The first preamble group can be one of the Random Access Preamble Group A and Random Access Preamble Group B for the first RA type.For example, for the fast AR type, the potential payload size in MSGA (UL data available for transmission plus MAC header and, when necessary, MAC CEs) is greater than ra-MsgASizeGroupA and the path loss is less than PCMAX (from the Server Cell executing the Random Access Procedure) preambleReceivedTargetPower - msgA-DeltaPreamble messagePowerOffsetGroupB, or if the random access procedure was initiated for the CCCH logical channel and the CCCH SDU size plus the MAC subheader is greater than ra-MsgASizeGroupA, the Random Access Preamble Group B is selected. Otherwise, Random Access Preamble Group A is selected.

[077] Fig. 3 shows a flowchart of an exemplary method 300 implemented on a first device according to some exemplary embodiments of the present disclosure. For discussion purposes, method 300 will be described from the perspective of the first device 110 with reference to Fig. 1.

[078] In block 310, the first device 110 determines whether a resource Petition 870250068581, dated 04 / 08 / 2025, page 45 / 76 35 / 47 of contention-free random access is allocated from a second device to a first random access type. According to a determination of which contention-free random access resource is allocated, in block 320, the first device compares a destination transport block size corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first random access type. In block 330, the first device performs random access to the second device based on a result of the comparison.

[079] In some example embodiments, performing random access comprises, according to the determination that the destination transport block size corresponds to the first transport block size, performing random access based on the first group of preambles.

[080] In some example embodiments, performing random access based on the first preamble group comprises: according to a determination that the first random access type is used, performing a contention-based random access attempt with the first random access type when transmitting a preamble selected from the first preamble group and payload of the first transport block size.

[081] In some example embodiments, performing random access based on the first group of preambles comprises: according to a switching trigger from the first type of random access to a second type of random access, selecting a second group of preambles for the second type of random access corresponding to the first group of preambles; and according to a selection of the second group of Petition 870250068581, dated 04 / 08 / 2025, page 46 / 76 36 / 47 preambles, perform an additional contention-based random access attempt with the second type of random access when transmitting a preamble selected from the second group of preambles.

[082] In some example embodiments, selecting the second preamble group comprises: according to a switching trigger from the first random access type to a second random access type, determining whether the second preamble group is available to the first device; and according to the determination that the second preamble group is available, selecting the second preamble group. In some example embodiments, the method further comprises, according to a determination that the second preamble group is unavailable, determining that random access fails, without performing a contention-based random access attempt with the second random access type.

[083] In some example embodiments, the second type of random access is a type of slow random access. In some example embodiments, the second type of random access is a type of four-step random access.

[084] In some example embodiments, comparing the destination transport block size with the first transport block size comprises: determining whether transmission on the contention-free random access resource is available and, based on a determination that transmission on the contention-free random access resource is unavailable, comparing the destination transport block size with the first transport block size.

[085] In some example modalities, performing random access comprises according to the determination that the size of Petition 870250068581, dated 04 / 08 / 2025, page 47 / 76 37 / 47 destination transport block does not match the first transport block size, perform random access based on a third group of preambles available for the first type of random access.

[086] In some example embodiments, the third group of preambles comprises a Random Access Preambles group A and a Random Access Preambles group B for the first type of random access.

[087] In some example embodiments, comparing the destination transport block size with the first transport block size comprises: according to a determination that a previous contention-based random access attempt using a preamble selected from the first group of preambles fails, determining whether transmission on the contention-free random access resource is available and according to transmission on the contention-free random access resource being available, comparing the destination transport block size with the first transport block size.

[088] In some example embodiments, comparing the destination transport block size with the first transport block size comprises determining whether a contention-based random access attempt prior to the second device is performed and according to the determination that the contention-based random access attempt prior to the second device was not performed, comparing the destination transport block size with the size of the first transport block.

[089] In some example embodiments, performing random access comprises: based on a determination that the destination transport block size does not match the first transport block size, preventing an access attempt from being performed. Petition 870250068581, dated 04 / 08 / 2025, page 48 / 76 38 / 47 random, free from containment.

[090] In some example embodiments, performing random access comprises: according to a determination that the destination transport block size does not match the size of the first transport block, performing a random access attempt based on additional contention with the first type of random access based on the first group of preambles and the first transport block size.

[091] In some example embodiments, the first group of preambles comprises one from the Random Access Preambles group A and the Random Access Preambles group B for the first type of random access.

[092] In some example embodiments, the first random access type is a fast random access type. In some example embodiments, the first random access type is a two-step random access type.

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

[094] In some example embodiments, a first apparatus capable of performing any of the 300 methods (for example, the first device 110) may comprise means for performing the respective steps of the 300 method. The means may be implemented in any suitable form. For example, the means may be implemented in a set of circuits or a software module. The first apparatus may be implemented as or included in the first device 110.

[095] In some exemplary embodiments, the first apparatus comprises means for determining whether a free random access resource Petition 870250068581, dated 04 / 08 / 2025, page 49 / 76 39 / 47 contention is allocated from a second device to a first random access type; according to a determination that the contention-free random access resource is allocated, compare a target transport block size corresponding to the contention-free random access resource with a first transport block size configured for a first group of preambles available for the first random access type; and perform random access to the second device based on a result of the comparison.

[096] In some example embodiments, the means for performing random access comprise means for, according to the determination that the destination transport block size corresponds to the first transport block size, performing random access based on the first group of preambles.

[097] In some example embodiments, the means for performing random access based on the first preamble group comprise: means for, according to a determination that the first type of random access is used, performing a contention-based random access attempt with the first type of access when transmitting a preamble selected from the first preamble group and payload of the first transport block size.

[098] In some example embodiments, the means for performing random access based on the first group of preambles comprise: means for, according to a switching trigger from the first type of random access to a second type of random access, selecting a second group of preambles for the second type of random access corresponding to the first group of preambles; and according to a selection of the second group of preambles, performing another access attempt. Petition 870250068581, dated 04 / 08 / 2025, page 50 / 76 40 / 47 random contention-based with the second type of random access when transmitting a preamble selected from the second group of preambles.

[099] In some example embodiments, the means for selecting the second group of preambles comprise: means for, according to a switching trigger from the first random access type to a second random access type, determining whether the second group of preambles is available to the first device; and according to the determination that the second group of preambles is available, selecting the second group of preambles. In some example embodiments, the method further comprises, according to a determination that the second group of preambles is unavailable, determining that random access fails, without performing a contention-based random access attempt with the second random access type.

[100] In some example embodiments, the second type of random access is a type of slow random access. In some example embodiments, the second type of random access is a type of four-step random access.

[101] In some example embodiments, the means for comparing the destination transport block size with the first transport block size comprise: means for determining whether transmission on the contention-free random access resource is available and means for, in accordance with the determination that transmission on the contention-free random access resource is unavailable, comparing the destination transport block size with the first transport block size.

[102] In some example embodiments, comparing the destination transport block size with the first transport block size comprises determining whether a random access attempt based on Petition 870250068581, dated 04 / 08 / 2025, page 51 / 76 41 / 47 contention prior to the second device is performed and according to the determination that the random access attempt based on prior contention was not performed, compare the target transport block size with the size of the first transport block.

[103] In some example embodiments, the means for performing random access comprise means for, in accordance with a determination that the destination transport block size does not correspond with the first transport block size, performing random access based on a third group of preambles available for the first type of random access.

[104] In some example embodiments, the third group of preambles comprises one from the Random Access Preambles group A and the Random Access Preambles group B for the first type of random access.

[105] In some example embodiments, the means for comparing the destination transport block size with the first transport block size comprise: means for, based on a determination that a previous contention-based random access attempt using a preamble selected from the first group of preambles fails, determining whether transmission on the contention-free random access resource is available and based on transmission on the contention-free random access resource being available, comparing the destination transport block size with the first transport block size.

[106] In some example embodiments, the means for performing random access comprise: means for, in accordance with a determination that the size of the destination transport block does not match the size of the first transport block, preventing an access attempt Petition 870250068581, dated 04 / 08 / 2025, page 52 / 76 42 / 47 random, contention-free role is played.

[107] In some example embodiments, the means for performing random access comprise: means for, in accordance with a determination that the destination transport block size does not match the first transport block size, performing an additional contention-based random access attempt with the first type of random access based on the first group of preambles and the first transport block size.

[108] In some example embodiments, the first group of preambles comprises one from a group of Random Access Preambles A and group of Random Access Preambles B for the first type of random access.

[109] In some example embodiments, the first random access type is a fast random access type. In some example embodiments, the first random access type is a two-step random access type.

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

[111] In some example embodiments, the first apparatus further comprises means for performing other steps in some example embodiments of method 300. In some example embodiments, the means comprise at least one processor; and at least one memory including computer program code, to at least one memory and computer program code configured to, with the at least one processor, cause the performance of the first apparatus.

[112] Fig. 4 is a simplified block diagram of a 400 device. Petition 870250068581, dated 04 / 08 / 2025, page 53 / 76 43 / 47 which is suitable for implementing embodiments of the present disclosure. Device 400 can be provided to implement the communication device, for example, the first device 110 or the second device 120 as shown in Fig. 1. As shown, device 400 includes one or more processors 410, one or more memories 420 coupled to the processor 410 and one or more communication modules 440 coupled to the processor 410.

[113] The 440 communication module is for bidirectional communications. The 440 communication module has at least one antenna to facilitate communication. The communication interface can represent any interface necessary for communication with other network elements.

[114] The 410 processor may be of any type suitable for 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 multi-core processor architecture, as non-limiting examples. The 400 device may have multiple processors, such as an application-specific integrated circuit chip that is subordinated in time to a clock that synchronizes with the main processor.

[115] Memory 420 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, a read-only memory (ROM) 424, an electrically programmable read-only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disc (DVD), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, a random access memory (RAM) 422 and other volatile memories that will not withstand the duration of a power-off.

[116] A computer program 430 includes executable instructions of Petition 870250068581, dated 04 / 08 / 2025, page 54 / 76 44 / 47 computer operations are executed by the associated processor 410. Program 430 can be stored in memory, for example, ROM 424. Processor 410 can perform any appropriate actions and processing by loading program 430 into RAM 422.

[117] The example embodiments of the present disclosure can be implemented by means of program 430 so that device 400 can perform any process of the disclosure, as discussed with reference to Figs. 2 to 3. The example embodiments of the present disclosure can also be implemented by hardware or by a combination of software and hardware.

[118] In some example embodiments, program 430 may be tangibly contained in a computer-readable medium that may be included in device 400 (such as memory 420) or other storage devices that are accessible by device 400. Device 400 may load program 430 from the computer-readable medium into RAM 422 for execution. The computer-readable medium may include any type of tangible non-volatile storage, such as ROM, EPROM, flash memory, a hard disk, CD, DVD, and the like. Fig. 5 shows an example of computer-readable medium 500 in the form of a CD or DVD. The computer-readable medium has program 430 stored on it.

[119] Generally, various embodiments of the present disclosure can 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 that can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and Petition 870250068581, dated 04 / 08 / 2025, page 55 / 76 45 / 47 described as block diagrams, flowcharts or using some other pictorial representations, it should be understood that the block, apparatus, system, technique or method described in this disclosure 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.

[120] The present disclosure also provides at least one computer program product tangibly stored on a non-transient, computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, executed on a device on a real or virtual target processor, to accomplish any of the methods as described above with reference to Figs. 2 to 3. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform specific tasks or implement specific abstract data types. The functionality of program modules can be combined or divided among program modules as desired in various embodiments. The machine-executable instructions for program modules can be executed on a local or distributed device.In a distributed device, program modules can be located on either local or remote storage media.

[121] The program code for carrying out the methods of this disclosure may be written in any combination of one or more programming languages. Such program codes may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, so that Petition 870250068581, dated 04 / 08 / 2025, pages 56 / 76 46 / 47 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 can be executed entirely on one machine, partially on the machine as a standalone software package, partially on the machine and partially on a remote machine, or entirely on the remote machine or server.

[122] In the context of this disclosure, 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 carrier include a signal, computer-readable media and the like.

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

[124] Additionally, although the 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 any order. Petition 870250068581, dated 04 / 08 / 2025, pp. 57 / 76 47 / 47 sequential, or that all the illustrated operations be performed, to achieve the desired results. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are contained in the discussions above, they should not be interpreted as limitations on the scope of this disclosure, but rather as descriptions of attributes that may be specific to particular modalities. Certain attributes that are described in the context of separate modalities may also be implemented in combination in a single modality. Conversely, several attributes that are described in the context of a single modality may also be implemented in multiple modalities separately or in any suitable subcombination.

[125] Although the present disclosure has been described in languages ​​specific to structural features and / or methodological acts, it should be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific attributes or acts described above. Instead, the specific attributes and acts described above are disclosed as example forms of implementation of the claims. Petition 870250068581, dated 04 / 08 / 2025, pp. 58 / 76

Claims

1 / 5 CLAIMS 1. User equipment characterized in that it comprises: at least one processor; and at least one instruction-storing memory which, when executed by at least one processor, causes the user equipment to perform: the selection of a preamble group from a plurality of preamble groups for a random access message, in the case where at least one resource for a two-step contention-free random access type has been configured, wherein the selection is based on whether a first transport block size configured for the at least one resource matches a second transport block size associated with the preamble group.

2. User equipment according to claim 1, characterized in that the instructions additionally cause the user equipment to select the group of preambles for contention-based random access.

3. User equipment according to claim 1 or 2, characterized in that the user equipment further comprises: a transceiver for transmitting the random access message.

4. User equipment according to claim 3, characterized in that the instructions additionally cause the transceiver to transmit the random access message as part of a two-step contention-based random access using a preamble from the preamble group. Petition 870250068581, dated 04 / 08 / 2025, p. 59 / 76 2 / 5 5. User equipment according to claim 3, characterized in that the instructions additionally cause the transceiver to transmit the random access message as part of a four-step contention-based random access using a preamble from the preamble group.

6. User equipment, according to any one of claims 1 to 5, characterized in that at least one feature comprises at least one dedicated random access feature.

7. User equipment, according to any one of claims 1 to 6, characterized in that at least one feature comprises at least one PUSH feature.

8. User equipment according to any one of claims 1 to 7, characterized in that the instructions additionally cause the user equipment to select a first group of preambles as the preamble group if the first transport block size matches the second transport block size.

9. User equipment according to any one of claims 1 to 8, characterized in that the instructions additionally cause the user equipment to select a second group of preambles from among the plurality of groups of preambles if the first transport block size does not match the second transport block size.

10. User equipment according to claim 4, characterized in that the instructions additionally cause the user equipment to switch to four-step contention-based random access in a case where two-step contention-based random access is not successfully completed after transmitting the random access message.

11. User equipment according to claim 10, characterized in that the instructions cause the user equipment to switch to four-step contention-based random access after performing a number of random access attempts.

12. User equipment according to claim 11, characterized in that the number of random access attempts comprises a number of two-step contention-free random access attempts.

13. User equipment according to claim 11 or 12, characterized in that the number of random access attempts comprises a number of random access attempts based on two-step contention.

14. User equipment, according to any one of claims 10 to 13, characterized in that the instructions cause the user equipment to perform a random access attempt, after switching to four-step contention-based random access, based on the selected preamble group.

15. Method performed by a user device characterized in that the method comprises: selecting a group of preambles from a plurality of groups of preambles for a random access message, in the case where at least one resource for a two-step contention-free random access type has been configured, wherein the selection is based on whether a first transport block size configured for the at least one resource corresponds to a second transport block size associated with the group of preambles.

16. Method according to claim 15, characterized in that the method further comprises selecting the group of preambles for a contention-based random access.

17. Method according to claim 15 or 16, characterized in that the method further comprises transmitting the random access message.

18. Method, according to claim 17, characterized in that the transmission comprises transmitting the random access message as part of a two-step contention-based random access using a preamble from the selected group of preambles.

19. Method, according to claim 17, characterized in that the transmission comprises transmitting the random access message as part of a four-step random access using a preamble from the selected group of preambles.

20. A method according to any one of claims 15 to 19, characterized in that at least one resource comprises at least one dedicated random access resource.

21. A method, according to any one of claims 15 to 20, characterized in that at least one feature comprises at least one PUSCH feature.

22. A method according to any one of claims 15 to 21, characterized in that the method further comprises selecting a first group of preambles as the selected group of preambles if the first transport block size matches the second transport block size.

23. Method according to any one of claims 15 to 22, Petition 870250068581, dated 04 / 08 / 2025, pp. 62 / 76 5 / 5 characterized in that the method further comprises selecting a second group of preambles from among the plurality of groups of preambles if the first transport block size does not match the second transport block size.

24. A method according to claim 18, characterized in that the method further comprises switching to a four-step contention-based random access if the two-step contention-based random access is not successfully completed after transmitting the random access message.

25. Method according to claim 24, characterized in that switching occurs after performing a number of random access attempts.

26. Method according to claim 25, characterized in that the number of random access attempts comprises a number of two-step containment-free random access attempts.

27. A method according to claim 24 or 25, characterized in that the number of random access attempts comprises a number of random access attempts based on two-step contention.

28. A method according to any one of claims 24 to 27, characterized in that the method further comprises performing a random access attempt after switching to four-step contention-based random access based on the selected preamble group. Petition 870250068581, dated 04 / 08 / 2025, pp. 63 / 76

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