Random Access Procedure

Abstract

To provide a method, a device, and a computer-readable storage medium for a random access procedure, in an example embodiment of the present disclosure.SOLUTION: A method includes, at a terminal device, transmitting a random access request to a network device in a random access procedure, in response to receiving an uplink grant for the terminal device from the network device in the random access procedure, determining whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of the terminal device, and in response to determining that the first size does not match the second size, determining a first portion of the second data unit for subsequent transmission.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to a method, device, and computer-readable storage medium for a random access procedure. [Background technology]

[0002] 5G New Radio (NR) provides multi-beam operation. Support for multi-beam operation in NR includes beam quality measurement, beam quality reporting, beam assignment, and recovery mechanisms when assigned beam quality is not good enough. NR supports multi-beam operation in all phases of radio operation, including initial / random access, paging, data / control transmission, data / control reception, and mobility processing.

[0003] In a multi-beam operation scenario in NR, a user equipment (UE) may switch between a beam assigned with contention-free random access (CFRA) resources and a beam assigned with contention-based random access (CBRA) resources. However, in LTE, the communication network assigns cell-wide CFRA resources to a UE; that is, there is no switching between CFRA and CBRA. Therefore, when a beam switching procedure occurs in NR, the size of a medium access control (MAC) protocol data unit (PDU) allowed in an uplink grant assigned during the random access (RA) procedure, transmitted from a network device (e.g., a gNB), may differ from the size of the MAC PDU retrieved from the UE's Msg3 buffer. Summary of the Invention

[0004] Generally, the exemplary embodiments of the present disclosure provide a method, device, and computer-readable storage medium for a random access procedure.

[0005] In a first aspect, a method is provided that is implemented in a terminal device, the method comprising: transmitting, at the terminal device, a random access request in a random access procedure to a network device; determining, in response to receiving, in the random access procedure, an uplink grant for the terminal device from the network device, whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of the terminal device; and, in response to determining that the first size does not match the second size, determining a first portion of the second data unit for subsequent transmission.

[0006] In a second aspect, a method implemented in a network device is provided, the method comprising: receiving a random access request from a terminal device in a random access procedure; and, in response to receiving the random access request, transmitting an uplink grant for the terminal device indicating a first size of the first data unit to the terminal device, such that the terminal device determines whether a first size of the first data matches a second size of a second data unit stored in a buffer of the terminal device.

[0007] In a third aspect, there is provided a terminal device, the device comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the at least one processor, to cause the device to perform at least the method according to the first aspect.

[0008] In a fourth aspect, there is provided a network device, the device comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the at least one processor, to cause the device to perform at least a method according to the second aspect.

[0009] In a fifth aspect, there is provided an apparatus comprising means for carrying out the steps of the method according to the first aspect.

[0010] In a sixth aspect, there is provided an apparatus comprising means for carrying out the steps of the method according to the second aspect.

[0011] In a seventh aspect, there is provided a computer readable medium having stored thereon a computer program which, when executed by at least one processor of a device, causes the device to perform a method according to the first aspect.

[0012] In an eighth aspect, there is provided a computer readable medium having stored thereon a computer program which, when executed by at least one processor of a device, causes the device to perform a method according to the second aspect.

[0013] It should be understood that this Summary section is not intended to identify key or essential features of the 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 more readily apparent through the following description.

[0014] The above and other objects, features, and advantages of the present disclosure will become more apparent through a more detailed description of several exemplary embodiments of the present disclosure in the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] 1 illustrates an exemplary communication system 100 in which exemplary embodiments of the present disclosure may be implemented. [Figure 2] 2 shows an illustration of an example process 200 of a random access procedure according to some example embodiments of the present disclosure. [Figure 3] 3 illustrates a flowchart of an example method 300 of a random access procedure according to some example embodiments of the present disclosure. [Figure 4] 4 illustrates a flowchart of an example method 400 of a random access procedure according to some example embodiments of the present disclosure. [Figure 5] FIG. 1 is a simplified block diagram of a device suitable for practicing exemplary embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] Throughout the drawings, the same or similar reference numbers represent the same or similar elements.

[0017] The principles of the present disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are set forth for illustrative purposes only, to assist those skilled in the art in understanding and practicing the present disclosure, without implying any limitation on the scope of the present disclosure. The present disclosure described herein can be implemented in various ways other than those described below.

[0018] In the following description and claims, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs, unless defined otherwise.

[0019] As used herein, the term "communications network" refers to a network that conforms to any suitable communications standard or protocol, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), and 5G NR, and that uses any suitable communications technology, including, for example, multiple-input multiple-output (MIMO), OFDM, time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM), Bluetooth, ZigBee, machine-type communications (MTC), eMBB, mMTC, and uRLLC technologies. For purposes of discussion, in some embodiments, an LTE network, an LTE-A network, a 5G NR network, or any combination thereof, will be treated as an example of a communications network.

[0020] As used herein, the term "network device" refers to any suitable device on the network side of a communication network. A network device may include any suitable device in an access network of a communication network, including, for example, a base station (BS), a relay, an access point (AP), a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a Gigabit Node B (gNB), a remote radio module (RRU), a radio header (RH), a remote radio head (RRH), and low-power nodes such as femto and pico. For discussion purposes, in some embodiments, an eNB will be treated as an example of a network device.

[0021] The network devices may also include any suitable devices in the core network, including, for example, multi-standard radio (MSR) radio equipment such as a multi-standard radio MSRBS, a network controller such as a radio network controller (RNC) or base station controller (BSC), a multi-cell / multicast coordination entity (MCE), a mobile switching center (MSC) and MME, an operation and management (O&M) node, an operation support system (OSS) node, a self-organizing network (SON) node, a positioning node such as an evolved service providing mobile location center (E-SMLC), and / or a mobile data terminal (MDT).

[0022] As used herein, the term "terminal device" refers to a device capable of communicating, configured to communicate, arranged to communicate, and / or operable to communicate with a network device or additional terminal devices in a communications network. Communication may include transmitting and / or receiving wireless signals using electromagnetic signals, radio waves, infrared signals, and / or other types of signals suitable for transmitting information wirelessly. In some embodiments, a terminal device may be configured to transmit and / or receive information without direct human interaction. For example, a terminal device may transmit information to a network device on a predetermined schedule, when triggered by an internal or external event, or in response to a request from the network side.

[0023] Examples of terminal devices include, but are not limited to, user equipment (UE), such as a smartphone, a wireless-enabled tablet computer, a laptop embedded equipment (LEE), a laptop mounted equipment (LME), and / or wireless customer premises equipment (CPE). For discussion purposes, some embodiments are described below with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably in the context of this disclosure.

[0024] As used herein, the term "cell" refers to an area covered by a radio signal transmitted by a network device. Terminal devices within a cell are served by the network device and may access a communications network through the network device.

[0025] As used herein, the term "circuit" means (a) hardware-only circuit implementations (e.g., analog and / or digital-only implementations); (b) combinations of hardware circuitry and software, such as (where applicable): (i) a combination of analog and / or digital hardware circuitry(s) and software / firmware, and (ii) any portion of hardware processor(s) with software (including digital signal processor(s)), software, and memory(s) that cooperate to cause a device, such as a mobile phone or server, to perform various functions; (c) hardware circuit(s) and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but software may be absent if not necessary for operation; It may refer to one or more or all of the above.

[0026] This definition of circuit applies to all uses of the term in this application, including all claims. As a further example, the term "circuit" as used in this application encompasses simply a hardware circuit or processor(s), or a portion of a hardware circuit or processor, as well as its (or their) accompanying software and / or firmware implementations. The term "circuit" also encompasses, for example, a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to certain claim elements.

[0027] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. The term "includes" and variations thereof should be interpreted as open terms meaning "including, but not limited to." The term "based on" should be interpreted as "based at least in part on." The terms "one embodiment" and "an embodiment" should be interpreted as "at least one embodiment." The term "another embodiment" should be interpreted as "at least one other embodiment." Other definitions, both explicit and implicit, may be included below.

[0028] 1 illustrates a communication network 100 in which embodiments of the present disclosure may be implemented. The communication network 100 may conform to any suitable protocol or standard, existing or developed in the future. In some embodiments, the communication network 100 may be an LTE (or LTE-A) network, an NR network, or a combination thereof.

[0029] Communications network 100 comprises network device 110. Network device 110 serves terminal device 120 within cell 111. It will be understood that the number of network devices and terminal devices is shown for illustrative purposes only, without implying any limitation. Communications system 100 may include any suitable number of network devices and terminal devices. Communications between network device 110 and terminal device 120 may utilize any suitable technology, existing or developed in the future.

[0030] The issue of grants of different sizes provided by a communication network for MESSAGE 3 (Msg3) transmission was considered in LTE. Msg3 may carry Layer 2 and Layer 3 messages from a terminal device 120 to a network device 110, such as a radio resource control connection request for initial access or a C-RNTI medium access control (MAC) control element (CE) for random access in connected mode. If an uplink grant provided in a random access response (RAR) to a random access preamble (RAP) of the same group has a different size than the previous uplink grant assigned during the random access procedure (e.g., the first uplink grant), this was considered a very rare case, and therefore the behavior of the terminal device 120 within the random access procedure was not defined. In LTE, a communication network allocates CFRA resources for the entire cell to a terminal device 120. That is, there is no switching between CFRA and CBRA within a single random access procedure.

[0031] 5G New Radio (NR) provides multi-beam operation. Thus, unlike LTE, where CFRA resources are allocated to one cell (e.g., cell 111 shown in FIG. 1 ), because allocating CFRA resources to all beams for all UEs may be too expensive, thereby defeating the purpose of beamforming, in NR, the communication network may allocate CFRA resources to only a subset of beams within cell 111, rather than allocating them to all beams.

[0032] Thus, in the case of multi-beam operation in NR, a user equipment (UE), such as the terminal device 120 shown in FIG. 1, may move within a cell and change beams. The terminal device 120 may switch between a beam with one type of RA resource and some other beams with another type of RA resource, for example, the terminal device may switch between a beam with contention-free random access (CFRA) resources and a beam with contention-based random access (CBRA) resources within the cell 111.

[0033] When the terminal device 120 switches from CFRA to CBRA, there is no problem caused by Msg3, which can only be generated during the first CBRA attempt. In the case of CFRA, the RA procedure is already successful by receiving Msg2 from the gNB (e.g., the network device 110 shown in FIG. 1).

[0034] However, when the terminal device 120 switches from CBRA to CFRA, according to TS 38.321, Msg3 has been generated and should also be sent in CFRA because, although the hybrid automatic repeat request (Hybrid ARQ or HARQ) buffer should be flushed upon completion of the RA procedure, the Msg3 buffer should not be flushed. Furthermore, in the HARQ entity, if an uplink grant is received in RAR and a medium access control (MAC) protocol data unit (PDU) is present in the Msg3 buffer, the MAC PDU may be retrieved from the Msg3 buffer.

[0035] In the above example, if the grant provided in the RAR for the CFRA preamble transmission has a size equal to the size indicated in the previously provided grant in response to the CBRA preamble transmission, the MAC PDU in the Msg3 buffer can be transmitted with the provided grant. However, two different preamble groups, namely, preamble group A and group B, are defined for CBRA. Typically, the terminal device 120 selects a sequence from these two groups based on the size of the uplink packet and the radio conditions. This helps the network device 110 calculate the physical uplink shared channel (PUSCH) resources required for the uplink transmission of the terminal device 120. The preambles in group A are used for small-sized packets or large-sized packets in poor radio conditions. The preambles in group B are used for large-sized packets in good radio conditions. In this example, the network device 110 does not know whether the terminal device 120 attempted CBRA before CFRA or which group's preamble was applied when the CBRA preamble was transmitted. Therefore, it is expected that problems caused by different Msg3 grant sizes will occur frequently in NR.

[0036] Furthermore, given the fact that MAC PDUs in the Msg3 buffer, such as at least the segment of the handover (HO) completion command (RRCReconfigurationComplete), may be multiplexed, it is undesirable to lose such data and delay the completion of the HO procedure (because RLC-level retransmissions would be required). If CFRA is selected for the preamble attempt, the terminal device 120 uses the Msg3 buffer for the first uplink data transmission in the RA procedure. If CFRA is selected for the preamble attempt, the RA procedure is successfully completed upon RAR reception.

[0037] Therefore, with regard to the fact that the size of the MAC PDU indicated in the uplink grant allocated during the RA procedure sent from the network device 110 may differ from the size of the MAC PDU obtained from the Msg3 buffer of the terminal device 120, several approaches have been considered to solve this problem.

[0038] One approach has been proposed that during resource selection for random access for handover, if Msg3 is transmitted in the current random access procedure, the terminal device 120 should not select a random access preamble from among the CFRA preambles, but this approach may waste dedicated resources for CFRA and unnecessarily increase the load among contention-based preambles.

[0039] In a further approach, it has been proposed that the multiplexing and assembly entity may include multiple MAC sub-PDUs from the retrieved MAC PDU in a subsequent uplink transmission. If the size of the uplink grant does not match the previous uplink grant provided in response to the CBRA preamble, the Msg3 buffer may be flushed and a new MAC PDU may be retrieved from the multiplexing and assembly entity. However, this approach may result in data loss.

[0040] As an option to flush Msg3, the MAC may indicate data multiplexed in the MAC PDU, in which case the RLC PDU may be regenerated and remultiplexed. This approach may be suitable for processing data, but may not work for the MAC Control Element (CE).

[0041] The principles and implementations of the present disclosure are described in detail below with reference to Figure 2, which illustrates a process 200 according to an exemplary embodiment of the present disclosure. For discussion purposes, the process 200 is described with reference to Figure 1. The process 200 may include a random access procedure.

[0042] FIG. 2 shows an illustration of an example process 200 of a random access procedure according to some example embodiments of the present disclosure.

[0043] As shown in FIG. 2, when the terminal device 120 performs random access, the terminal device 120 transmits a random access request, i.e., a random access preamble (RAP), to the network device 110 210. In the context of the present disclosure, the RAP is also referred to as "MESSAGE1" or "Msg1." The RAP is a signature code sequence that serves as an identifier of the terminal device 120. Depending on whether the RAP is UE-specific, the random access procedure is classified into a contention-free random access (CFRA) procedure and a contention-based random access (CBRA) procedure. As a result, the terminal device 120 may transmit different random access preambles, i.e., a CFRA preamble or a CBRA preamble, to the network device 110. As described above, in the CBRA procedure, the terminal device 120 may select a CBRA preamble from Group A and Group B. The terminal device 120 may select a sequence from these two groups based on the size of the uplink packet and radio conditions.

[0044] Upon detecting the RAP preamble from the terminal device 120, the network device 110 may respond to the random access request by transmitting a random access response (RAR) (also referred to in the context of this disclosure as “MESSAGE2” or “Msg2”) to the terminal device 120 based on the received RAP preamble 220. The RAR may be scheduled via an actual message on the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH). The RAR may include, for example, a timing advance command (TAC) for UL timing alignment, an uplink grant, and a temporary cell radio network identifier to the terminal device 120.

[0045] In a contention-free random access procedure, i.e., a non-contention-based random access procedure, the terminal device 120 sends a dedicated RAP to the network device 110, and if the terminal device 120 receives the RAP sent by the network device 110, the terminal device 120 determines that the random access procedure is successful.

[0046] In a contention-based random access procedure, after the terminal device 120 receives the RAR, the terminal device 120 may transmit a message (also referred to as "MESSAGE3" or "Msg3") to the network device 110 on the physical uplink shared channel (PUSCH). As mentioned above, Msg3 may carry Layer 2 and Layer 3 messages from the terminal device 120 to the network device 110, such as a radio resource control connection request for initial access or a C-RNTI MAC CE for random access in connected mode. When the terminal device 120 receives the RAR from the network device 110, the terminal device may obtain an uplink grant included in the RAR, which indicates an uplink grant available for the terminal device 120 to transmit its Msg3.

[0047] As described above, terminal device 120 may transmit preambles from different groups based on the size of the uplink packet and radio conditions, and network device 110 may allocate a corresponding uplink grant for terminal device 120 to transmit Msg3. In this case, the uplink grant for transmitting Msg3 included in the RAR may match the uplink grant in the Msg3 buffer of terminal device 120.

[0048] 2, terminal device 120 determines 230 whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of terminal device 120. The first data unit and the second data unit may be referred to as a MAC PDU. The buffer may be referred to as an Msg3 buffer of terminal device 120.

[0049] In some embodiments, to determine whether the first size matches the second size, terminal device 120 may determine the second size based on an Msg3 transmitted from an Msg3 buffer of terminal device 120. The terminal device may further determine the first size from an uplink grant transmitted from network device 110. Terminal device 120 may compare the first size with the second size to determine whether the first size does not match the second size.

[0050] In some exemplary embodiments, Msg3 may indicate at least one Medium Access Control Element (MAC CE), which may comprise at least one of a C-RNTI MAC CE, a buffer status report BSR, and a power headroom report PHR.

[0051] In general, a BSR is a type of MAC CE from a UE (e.g., terminal device 120) to a gNB (e.g., network device 110) that conveys information about the amount of data in the UE's buffer to be transmitted.

[0052] BSR may refer to various types of BSR. For example, BSR may include regular BSR, periodic BSR, and padding BSR. A regular BSR is transmitted when new data arrives in a buffer and the priority of the new data is higher than that already waiting in the buffer. A periodic BSR is transmitted at a predefined period. The gNB may preconfigure the periodicity for the UE through an RRC message (e.g., RRCConnectionReconfiguration). Furthermore, when the number of padding bits in a data message is greater than the size of the padding BSR, a padding BSR is transmitted so that the BSR can be transmitted using the padding bit space. If a full BSR cannot fit into the available padding bits, the padding BSR may be configured as a shortened BSR. In this case, the BSR is shortened and only the highest priority data is reported by the terminal device 120 to the network device 110.

[0053] In general, the PHR may indicate the amount of transmit power remaining in the UE.

[0054] As shown in FIG. 2, if the terminal device 120 determines that the first size does not match the second size, the terminal device 120 determines 240 a first portion of the second data unit for subsequent transmission.

[0055] In some example embodiments, the subsequent transmission may comprise at least one of a transmission associated with an uplink grant provided in a random access response (RAR) and a transmission associated with a further uplink grant different from the uplink grant.

[0056] In some demonstrative embodiments, terminal device 120 may determine whether the second size matches the first size. If terminal device 120 determines that the second size does not match the first size, terminal device 120 may discard some portions of the second data unit for subsequent transmission or may not consider some portions of the second data unit for subsequent transmission.

[0057] In some demonstrative embodiments, terminal device 120 may discard the shortened BSR from the second data unit.

[0058] Alternatively or additionally, terminal device 120 may discard the padding BSR from the second data unit.

[0059] Alternatively or additionally, terminal device 120 may discard the PHR from the second data unit.

[0060] Alternatively or additionally, the terminal device 120 may adjust the size of the shortened BSR. For example, the shortened BSR is adjusted to fit the available size, i.e., the number of reported logical channel groups (LCGs) is changed. Naturally, the bitmap may reflect the addition / deletion of reported LCGs. Adjusting the size of the shortened BSR may be limited to cases of reducing the size. It should be understood that for UE implementations, deleting information may be easier than creating additional information. In this way, up-to-date BSR information may be provided.

[0061] Alternatively or additionally, terminal device 120 may discard regular / periodic BSRs and / or PHRs. Furthermore, regular / periodic BSRs and / or PHRs cannot be canceled until after they have been included in a grant scheduled by the C-RNTI or CS-RNTI. This approach is intended to provide the most up-to-date information available regarding the buffer status and power headroom of terminal device 120, since the BSR / PHRs are generated anew for subsequent transmissions.

[0062] In some demonstrative embodiments, if the terminal device determines that the second size does not match the first size, the terminal device 120 may determine whether the random access procedure completed successfully by receiving the uplink grant. If the terminal device 120 determines that the random access procedure is considered to have completed successfully, the terminal device may discard the C-RNTI medium access control MAC control element MAC CE from the second data unit.

[0063] In some exemplary embodiments, if terminal device 120 determines that the second size does not match the first size, terminal device 120 may determine whether a contention-free random access preamble was transmitted. If terminal device 120 determines that a contention-free random access preamble was transmitted, terminal device 120 may discard the C-RNTI medium access control MAC control element MAC CE from the second data unit.

[0064] In some demonstrative embodiments, the terminal device 120 determining whether the random access procedure has completed successfully may comprise determining that the uplink grant and / or the RAR is addressed to at least one of a Cell Radio Network Temporary Identifier C-RNTI and a Random Access Radio Network Temporary Identifier RA-RNTI.

[0065] In the CFRA procedure, the terminal device 120 sends a dedicated RAP to the network device 110, and if the terminal device 120 receives the RAR sent by the network device 110, the terminal device 120 determines that the random access is successful. Therefore, the case described here may relate to the random access procedure during which the terminal device 120 switches from the CBRA procedure to the CFRA procedure. That is, there is no need to send a C-RNTI MAC CE to the network device 110.

[0066] This solution avoids unnecessary transmission overhead because the terminal device 120 is already identified from the transmitted CFRA preamble. Furthermore, this solution avoids any other type of MAC PDU being transmitted by the terminal device 120 because the network device 110 does not expect to receive a C-RNTI MAC CE in response to the CFRA preamble transmission.

[0067] In some example embodiments, other MAC CEs multiplexed in the obtained MAC PDU may be indicated to the multiplexing and assembly entity to be included in a subsequent uplink transmission. In this way, loss of control information during Msg3 reconstruction may be avoided, since the other multiplexed MAC CEs may be included in the subsequent transmission.

[0068] 2, the terminal device 120 transmits at least a portion of the first portion of the second data unit to the network device in the first data unit 250. The remaining portion of the first portion may be transmitted in a subsequent transmission.

[0069] Throughout the above embodiments, for each uplink grant, the HARQ entity of the terminal device 120 must identify the HARQ process associated with that grant. For each identified HARQ process: If the received grant is not addressed to a temporary C-RNTI on the PDCCH and the New Data Indicator (NDI) provided in the associated HARQ information has been switched compared to its value at the time of the previous transmission of this Transport Block (TB) of this HARQ process, or If an uplink grant is received on the PDCCH for C-RNTI and the HARQ buffer of the identified process is empty, or If an uplink grant is received in a random access response, or If the uplink grant is part of a bundle of configured grants and can be used for initial transmission according to clause 6.1.2.3 of TS 38.214 [7], and no MAC PDU has been obtained for this bundle, If a MAC PDU is present in the Msg3 buffer and an uplink grant is received in the random access response, If the uplink grant size does not match the size of the MAC PDU in the Msg3 buffer, instructing the multiplexing and assembly entity to include MAC sub-PDUs from the MAC PDU in the Msg3 buffer, except for the MAC sub-PDU containing the shortened BSR MAC CE, in subsequent uplink transmission(s), if any; Obtaining MAC PDUs to be transmitted from the multiplexing and assembly entity and storing them in the Msg3 buffer; If the uplink grant size is equal to the size of the MAC PDU in the Msg3 buffer, Get the MAC PDU to send from the Msg3 buffer, If there is no MAC PDU in the Msg3 buffer and an uplink grant is received in the random access response, Obtain the MAC PDU to transmit from the multiplexing and assembly entity (if any).

[0070] Alternatively or additionally, throughout the above embodiments, for each uplink grant, the HARQ entity of terminal device 120 must identify the HARQ process associated with that grant. For each identified HARQ process, If the received grant is not addressed to a temporary C-RNTI on the PDCCH and the New Data Indicator (NDI) provided in the associated HARQ information has been switched compared to its value at the time of the previous transmission of this Transport Block (TB) of this HARQ process, or If an uplink grant is received on the PDCCH for C-RNTI and the HARQ buffer of the identified process is empty, or If an uplink grant is received in a random access response, or If the uplink grant is part of a bundle of configured grants and can be used for initial transmission according to clause 6.1.2.3 of TS 38.214 [7], and no MAC PDU has been obtained for this bundle, If there is a MAC PDU in the Msg3 buffer and an uplink grant is received in a random access response scheduled by a PDCCH addressed to the RA-RNTI or C-RNTI, If the uplink grant size does not match the size of the MAC PDU in the Msg3 buffer, and If the random access procedure is successfully completed with this random access response, instructing the multiplexing and assembly entity to include MAC sub-PDUs from the MAC PDUs in the Msg3 buffer, except for MAC sub-PDUs containing a shortened BSR MAC CE or C-RNTI MAC CE, in subsequent uplink transmission(s), if any; Obtaining MAC PDUs to be transmitted from the multiplexing and assembly entity and storing them in the Msg3 buffer; If the uplink grant size is equal to the size of the MAC PDU in the Msg3 buffer, Get the MAC PDU to send from the Msg3 buffer, If there is no MAC PDU in the Msg3 buffer and an uplink grant is received in the random access response, Obtain the MAC PDU to transmit from the multiplexing and assembly entity (if any).

[0071] Thus, according to an embodiment of the present invention, the problem caused by a mismatch between the uplink grant indicated in the RAR and the MAC PDU in the Msg3 buffer can be resolved by reconstructing the MAC CE of the MAC PDU.

[0072] Further details of an exemplary embodiment according to the present disclosure are described with reference to FIGS.

[0073] 3 shows a flowchart of an example method 300 of a random access procedure according to some example embodiments of the present disclosure. Method 300 may be implemented in terminal device 120 shown in FIG. 2. For discussion purposes, method 300 will be described with reference to FIG. 2.

[0074] At 310, the terminal device 120 sends a random access request to the network device in a random access procedure.

[0075] In some exemplary embodiments, terminal device 120 may transmit one of a contention-free random access preamble and a contention-based random access preamble.

[0076] At 320, when the terminal device 120 receives an uplink grant for the terminal device 120 from the network device 110 in the random access procedure, the terminal device 120 determines whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of the terminal device.

[0077] In some example embodiments, the second data unit may comprise at least one of a C-RNTI, a BSR, and a PHR, or a MAC CE.

[0078] In some demonstrative embodiments, the BSR may comprise at least one of a shortened BSR, a padded BSR, a regular BSR, and a periodic BSR.

[0079] At 330, if the terminal device 120 determines that the first size does not match the second size, the terminal device 120 determines a first portion of the second data unit for subsequent transmission based at least on the first size.

[0080] In some demonstrative embodiments, terminal device 120 may determine whether the second size matches the first size. If the second size does not match the first size, the terminal device may perform at least one of discarding a shortened buffer status report BSR from the second data unit, discarding a padding buffer status report BSR from the second data unit, discarding a regular BSR from the second data unit, discarding a periodic BSR from the second data unit, discarding a power headroom report PHR from the second data unit, and adjusting the size of the shortened BSR.

[0081] In some demonstrative embodiments, terminal device 120 may determine whether the second size matches the first size. If the second size does not match the first size, terminal device 120 may determine whether the random access procedure completed successfully by receiving the uplink grant. If terminal device 120 determines that the random access procedure is considered to have completed successfully, terminal device 120 may discard the C-RNTI medium access control MAC control element MAC CE from the second data unit.

[0082] In some demonstrative embodiments, terminal device 120 may determine whether the second size matches the first size. If the second size does not match the first size, terminal device 120 may determine whether a contention-free random access preamble was transmitted. If terminal device 120 determines that a contention-free random access preamble was transmitted, the terminal device may discard the C-RNTI medium access control MAC control element MAC CE from the second data unit.

[0083] In some demonstrative embodiments, the terminal device 120 determining whether the random access procedure has completed successfully may comprise determining that the uplink grant is addressed to at least one of a Cell Radio Network Temporary Identifier C-RNTI and a Random Access Radio Network Temporary Identifier RA-RNTI.

[0084] In some demonstrative embodiments, the subsequent transmission may comprise at least one of a transmission associated with the uplink grant and a transmission associated with a further uplink grant that is different from the uplink grant.

[0085] In some demonstrative embodiments, terminal device 120 may further transmit at least a portion of the first portion of the second data unit to the network device in the first data unit.

[0086] 4 shows a flowchart of an example method 400 of a random access procedure according to some example embodiments of the present disclosure. Method 400 may be implemented in network device 110 shown in FIG. 2. For discussion purposes, method 400 will be described with reference to FIG. 2.

[0087] At 410, the network device 110 receives a random access request from the terminal device 120 in a random access procedure.

[0088] In some exemplary embodiments, the network device 110 may receive one of a contention-free random access preamble and a contention-based random access preamble.

[0089] At 420, network device 110 transmits an uplink grant for the terminal device to terminal device 120 indicating the first size of the first data unit, so that the terminal device determines whether the first size of the first data matches the second size of the second data unit stored in a buffer of the terminal device.

[0090] In some example embodiments, the second data unit may comprise at least one of a C-RNTI, a BSR, and a PHR, or a MAC CE.

[0091] In some demonstrative embodiments, the BSR may comprise at least one of a shortened BSR, a padded BSR, a regular BSR, and a periodic BSR.

[0092] In some demonstrative embodiments, the network device 110 may further receive at least a portion of the first portion of the second data unit from the terminal device in the first data unit.

[0093] In some demonstrative embodiments, an apparatus capable of performing method 300 (e.g., terminal device 120) may comprise means for performing each step of method 300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0094] In some demonstrative embodiments, an apparatus comprises: means, at a terminal device, for transmitting a random access request to a network device in a random access procedure; means for determining, in response to receiving an uplink grant for the terminal device from the network device in the random access procedure, whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of the terminal device; and means for determining, in response to determining that the first size does not match the second size, a first portion of the second data unit for subsequent transmission.

[0095] In some exemplary embodiments, the means for transmitting the random access request may comprise means for transmitting one of a contention-free random access preamble and a contention-based random access preamble.

[0096] In some example embodiments, the second data unit may comprise at least one of a C-RNTI, a BSR, and a PHR, or a MAC CE.

[0097] In some demonstrative embodiments, the BSR may comprise at least one of a shortened BSR, a padded BSR, a regular BSR, and a periodic BSR.

[0098] In some demonstrative embodiments, the means for determining the first portion may comprise means for performing at least one of: discarding a shortened buffer status report BSR from the second data unit; discarding a padding buffer status report BSR from the second data unit; discarding a regular BSR from the second data unit; discarding a periodic BSR from the second data unit; discarding a power headroom report PHR from the second data unit; and adjusting a size of the shortened BSR in response to determining that the second size does not match the first size.

[0099] In some demonstrative embodiments, the means for determining the first portion may comprise means for determining whether the random access procedure completed successfully by receiving the uplink grant in response to determining that the second size does not match the first size, and means for discarding the C-RNTI medium access control MAC control element MAC CE from the second data unit in response to determining that the random access procedure is considered to have completed successfully.

[0100] In some demonstrative embodiments, the means for determining whether the random access procedure has completed successfully may comprise means for determining that the uplink grant is addressed to at least one of a Cell Radio Network Temporary Identifier C-RNTI and a Random Access Radio Network Temporary Identifier RA-RNTI.

[0101] In some demonstrative embodiments, the subsequent transmission may comprise at least one of a transmission associated with the uplink grant and a transmission associated with a further uplink grant that is different from the uplink grant.

[0102] In some demonstrative embodiments, the apparatus may further comprise means for transmitting at least a portion of the first portion of the second data unit to the network device in the first data unit.

[0103] In some demonstrative embodiments, an apparatus capable of performing method 400 (e.g., network device 110) may comprise means for performing each step of method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module.

[0104] In some demonstrative embodiments, an apparatus comprises means for receiving a random access request from a terminal device in a random access procedure; and means for, in response to receiving the random access request, transmitting an uplink grant for the terminal device indicating a first size of the first data unit to the terminal device, such that the terminal device determines whether a first size of the first data matches a second size of a second data unit stored in a buffer of the terminal device.

[0105] In some exemplary embodiments, the means for receiving the random access request may comprise means for receiving one of a contention-free random access preamble and a contention-based random access preamble.

[0106] In some example embodiments, the second data unit may comprise at least one of a C-RNTI, a BSR, and a PHR, or a MAC CE.

[0107] In some demonstrative embodiments, the BSR may comprise at least one of a shortened BSR, a padded BSR, a regular BSR, and a periodic BSR.

[0108] In some demonstrative embodiments, the apparatus further comprises means for receiving at least a portion of the first portion of the second data unit from the terminal device in the first data unit.

[0109] 5 is a simplified block diagram of a device 500 suitable for implementing exemplary embodiments of the present disclosure. Device 500 may be considered a further exemplary implementation of terminal device 120 shown in FIG. 1. Thus, device 500 may be implemented in terminal device 120 or as at least a portion of terminal device 120.

[0110] As shown, device 500 includes a processor 510, a memory 520 coupled to processor 510, a suitable transmitter (TX) and receiver (RX) 540 coupled to processor 510, and a communication interface coupled to TX / RX 540. Memory 520 stores at least a portion of a program 530. TX / RX 540 is for bidirectional communication. TX / RX 540 has at least one antenna to facilitate communication, although in practice, access nodes referred to in this application may have multiple antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a mobility management entity (MME) / serving gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a relay node (RN), or a Uu interface for communication between an eNB and a terminal device.

[0111] The program 530 is assumed to include program instructions that, when executed by the associated processor 510, enable the device 500 to operate in accordance with exemplary embodiments of the present disclosure, as discussed herein with reference to FIGS. 2-4. The exemplary embodiments of the present disclosure may be implemented by computer software executable by the processor 510 of the device 500, by hardware, or by a combination of software and hardware. The processor 510 may be configured to implement various exemplary embodiments of the present disclosure. Furthermore, the combination of the processor 510 and the memory 520 may form a processing means 550 adapted to implement various exemplary embodiments of the present disclosure.

[0112] The memory 520 may be of any type suitable for a local technical network and may be implemented using any suitable data storage technology, including, by way of non-limiting example, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed and removable memory, etc. Although only one memory 520 is shown in the device 500, several physically separate memory modules may be present in the device 500. The processor 510 may be of any type suitable for a local technical network and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 500 may have multiple processors, such as application-specific integrated circuit chips configured to time-synchronize clocks that synchronize the main processors.

[0113] 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 that 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 graphical representation, it will be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing device, or some combination thereof.

[0114] 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, e.g., included in program modules, that execute on a target real or virtual processor device to perform the processes or methods described above with reference to any of Figures 2-5. Typically, program modules include routines, programs, libraries, objects, classes, components, or data structures that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or divided among program modules as desired in various embodiments. The machine-executable instructions of the program modules may be executed in local or distributed devices. In a distributed device, program modules may be located in both local and remote storage media.

[0115] Program code for carrying out the 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, a special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the implementation of the functions / acts specified in the flowcharts and / or block diagrams. The program code may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0116] In the context of the present disclosure, computer program code or associated data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals and computer-readable media.

[0117] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The 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 of the foregoing. More specific examples of the computer-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0118] Additionally, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order shown, or as requiring all of the operations illustrated, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Similarly, while the above discussion includes details of several specific implementations, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be unique 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.

[0119] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined by 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

1. A terminal device, means for transmitting a random access request to a network device in a random access procedure; means for receiving an uplink grant for the terminal device from the network device during the random access procedure; means for determining whether the random access procedure has been successfully completed by receiving the uplink grant; means for determining whether the size indicated in the uplink grant matches the size of a Medium Access Control Protocol Data Unit (MAC PDU) stored in a buffer of the terminal device; means for instructing a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission if the random access procedure is successfully completed upon receipt of the uplink grant and if the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer; means for discarding a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU in the subsequent uplink transmission; A terminal device comprising:

2. The means for transmitting a random access request includes: a contention-free random access preamble; a contention-based random access preamble; 2. The terminal device of claim 1, comprising: means for transmitting one of:

3. The MAC PDU comprises: C-RNTI MAC CE and Buffer Status Report (BSR) MAC CE; Power Headroom Report (PHR) MAC CE and 3. The terminal device according to claim 1, further comprising at least one of:

4. the MAC PDUs stored in the buffer were generated during a contention-based random access attempt; the random access procedure includes switching from the contention-based random access attempt to a contention-free random access procedure; The terminal device of claim 1 , wherein the random access request is a contention-free random access preamble for the contention-free random access procedure.

5. The terminal device of claim 4 , wherein the switching from the contention-based random access attempt to the contention-free random access procedure corresponds to a beam change in multi-beam operation supported by a recovery mechanism.

6. 1. A network device, comprising: means for receiving a random access request from a terminal device in a random access procedure; means for transmitting an uplink grant to the terminal device in response to receiving the random access request so that the terminal device can determine that the random access procedure has been completed successfully, the uplink grant indicating a size, and means for the terminal device to determine whether the size indicated in the uplink grant matches the size of a medium access control protocol data unit (MAC PDU) stored in a buffer of the terminal device and to instruct a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission; means for receiving the subsequent uplink transmission from the terminal device; Equipped with If the terminal device determines that the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer of the terminal device, the subsequent uplink transmission includes a medium access control sub-protocol data unit from the MAC PDU from the buffer of the terminal device, but does not include a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU stored in the buffer of the terminal device; If the terminal device determines that the size indicated in the uplink grant matches the size of the MAC PDU stored in a buffer of the terminal device, the subsequent uplink transmission includes the MAC PDU from the buffer of the terminal device.

7. The means for receiving a random access request includes: a contention-free random access preamble; a contention-based random access preamble; The network device of claim 6, comprising means for receiving one of:

8. The MAC PDU comprises: C-RNTI MAC CE and Buffer Status Report (BSR) MAC CE; Power Headroom Report (PHR) MAC CE and At least one of 8. The network device according to claim 6 or 7.

9. Resources for contention-free random access are allocated to a subset of beams in a cell of the network device, and the terminal device is capable of switching between a beam to which resources are allocated for contention-based random access and a beam to which resources are allocated for contention-free random access; The network device of claim 6 , wherein the random access request is a preamble for contention-free random access.

10. 1. A method performed by a terminal device, comprising: sending a random access request to a network device in a random access procedure; receiving an uplink grant for the terminal device from the network device during the random access procedure; determining whether the random access procedure has been successfully completed by receiving the uplink grant; determining whether a size indicated in the uplink grant matches a size of a medium access control protocol data unit (MAC PDU) stored in a buffer of the terminal device; instructing a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission if the random access procedure is successfully completed upon receipt of the uplink grant and if the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer; discarding a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU in the subsequent uplink transmission; A method comprising:

11. transmitting the random access request a contention-free random access preamble; a contention-based random access preamble; The method of claim 10, comprising transmitting one of:

12. The MAC PDU comprises: C-RNTI MAC CE and Buffer Status Report (BSR) MAC CE; Power Headroom Report (PHR) MAC CE and 12. The method according to claim 10 or 11, comprising at least one of:

13. the MAC PDUs stored in the buffer were generated during a contention-based random access attempt; the random access procedure includes switching from the contention-based random access attempt to a contention-free random access procedure; The method of claim 10 , wherein the random access request is a contention-free random access preamble for the contention-free random access procedure.

14. 14. The method of claim 13, wherein the switching from the contention-based random access attempt to the contention-free random access procedure corresponds to a beam change in multi-beam operation supported by a recovery mechanism.

15. 1. A method performed by a network device, comprising: receiving a random access request from a terminal device in a random access procedure; In response to receiving the random access request, sending an uplink grant to the terminal device so that the terminal device can determine that the random access procedure has been completed successfully, the uplink grant indicating a size, the terminal device determining whether the size indicated in the uplink grant matches the size of a medium access control protocol data unit (MAC PDU) stored in a buffer of the terminal device, and instructing a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission; receiving the subsequent uplink transmission from the terminal device; Equipped with If the terminal device determines that the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer of the terminal device, the subsequent uplink transmission includes a medium access control sub-protocol data unit from the MAC PDU from the buffer of the terminal device, but does not include a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU stored in the buffer of the terminal device; If the terminal device determines that the size indicated in the uplink grant matches the size of the MAC PDU stored in a buffer of the terminal device, the subsequent uplink transmission includes the MAC PDU from the buffer of the terminal device.

16. The means for receiving a random access request includes: a contention-free random access preamble; a contention-based random access preamble; 16. The method of claim 15, comprising receiving one of:

17. The MAC PDU comprises: C-RNTI MAC CE and Buffer Status Report (BSR) MAC CE; Power Headroom Report (PHR) MAC CE and 17. The method of claim 15 or 16, comprising at least one of:

18. Resources for contention-free random access are allocated to a subset of beams in a cell, and the terminal device is capable of switching between a beam to which resources are allocated for contention-based random access and a beam to which resources are allocated for contention-free random access; The method of claim 15 , wherein the random access request is a preamble for contention-free random access.

19. A program that, when executed by at least one processor, causes a terminal device to: sending a random access request to a network device in a random access procedure; receiving an uplink grant for the terminal device from the network device during the random access procedure; determining whether the random access procedure has been successfully completed by receiving the uplink grant; determining whether a size indicated in the uplink grant matches a size of a medium access control protocol data unit (MAC PDU) stored in a buffer of the terminal device; instructing a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission if the random access procedure is successfully completed upon receipt of the uplink grant and if the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer; discarding a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU in the subsequent uplink transmission; A program comprising instructions for executing at least the above.

20. A program that, when executed by at least one processor, causes a network device to: receiving a random access request from a terminal device in a random access procedure; In response to receiving the random access request, sending an uplink grant to the terminal device so that the terminal device can determine that the random access procedure has been completed successfully, the uplink grant indicating a size, the terminal device determining whether the size indicated in the uplink grant matches the size of a medium access control protocol data unit (MAC PDU) stored in a buffer of the terminal device, and instructing a multiplexing and assembly entity to include a medium access control sub-protocol data unit from the MAC PDU in a subsequent uplink transmission; receiving the subsequent uplink transmission from the terminal device; and instructions for executing at least If the terminal device determines that the size indicated in the uplink grant does not match the size of the MAC PDU stored in the buffer of the terminal device, the subsequent uplink transmission includes a medium access control sub-protocol data unit from the MAC PDU from the buffer of the terminal device, but does not include a Cell Radio Network Temporary Identifier (C-RNTI) Medium Access Control Element (MAC CE) from the MAC PDU stored in the buffer of the terminal device; If the terminal device determines that the size indicated in the uplink grant matches the size of the MAC PDU stored in a buffer of the terminal device, the subsequent uplink transmission includes the MAC PDU from the buffer of the terminal device.

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