Indication of random access response transmission

Abstract

Systems, methods, apparatus and computer program products for random access procedures are provided. A method may include providing at least one random access channel opportunity (RO) to at least one lower layer. The method may optionally include receiving at least one indication of at least one RO from at least one lower layer. The method may also include starting at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication.

Description

Technical Field

[0001] Certain embodiments may relate to communication systems, such as Long Term Evolution (LTE) or fifth generation (5G) radio access technology or new radio (NR) access technology, or other communication systems. For example, some embodiments may relate to random access procedures in such systems. Background Art

[0002] Examples of mobile or wireless telecommunication systems may include the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), MulteFire, LTE-A Pro and / or fifth generation (5G) radio access technology or new radio (NR) access technology. 5G wireless systems refer to next generation (NG) radio systems and network architectures. 5G is primarily built on new radio (NR), but 5G (or NG) networks may also be built on E-UTRA radio. It is estimated that NR provides bit rates of 10-20Gbit / s or higher and can support at least enhanced mobile broadband (eMBB) and ultra-reliable low latency communications (URLLC) and massive machine type communications (mMTC). NR is expected to provide ultra-wideband and ultra-robust, low latency connectivity and large-scale networking to support the Internet of Things (IoT). As the Internet of Things and machine-to-machine (M2M) communications become more prevalent, the demand for networks that meet the requirements of low power consumption, low data rates and long battery life will continue to grow. It should be noted that in 5G, a node that can provide radio access functions to user equipment (i.e., similar to Node B in UTRAN or eNB in ​​LTE) can be named gNB when built on NR radio and can be named NG-eNB when built on E-UTRA radio. Summary of the invention

[0003] According to some embodiments, a method may include providing at least one random access channel opportunity (RO) to at least one lower layer. The method may optionally include receiving at least one indication of at least one RO from at least one lower layer. The indicated at least one RO may be an RO that has successfully performed a listen-before-talk (LBT). In one embodiment, the method may also include starting at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication.

[0004] According to some embodiments, an apparatus may include a component for providing at least one random access channel opportunity (RO) to at least one lower layer. The apparatus may optionally include a component for receiving at least one indication of at least one RO from at least one lower layer. The at least one RO indicated may be an RO for which a listen-before-talk (LBT) has been successfully performed. In one embodiment, the apparatus may also include a component for starting at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication.

[0005] According to some embodiments, a device may include at least one processor and at least one memory, the at least one memory including computer program code. The at least one memory and the computer program code may be configured to, together with the at least one processor, cause the device to at least provide at least one random access channel opportunity (RO) to at least one lower layer. The at least one memory and the computer program code may optionally be configured to, together with the at least one processor, cause the device to at least receive at least one indication of at least one RO from at least one lower layer. The at least one RO indicated may be an RO that has successfully performed listen-before-talk (LBT). In one embodiment, the at least one memory and the computer program code may also be configured to, together with the at least one processor, cause the device to at least start at least one timer, the at least one timer being configured to monitor at least one control channel based on at least one indication.

[0006] According to some embodiments, a non-transitory computer readable medium may be encoded with instructions that, when executed in hardware, may perform a method. The method may include providing at least one random access channel opportunity (RO) to at least one lower layer. The method may optionally include receiving at least one indication of at least one RO from at least one lower layer. The at least one RO indicated may be an RO that has successfully performed a listen-before-talk (LBT). In one embodiment, the method may also include starting at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication.

[0007] According to some embodiments, a computer program product may perform a method. The method may include providing at least one random access channel opportunity (RO) to at least one lower layer. The method may optionally include receiving at least one indication of at least one RO from at least one lower layer. The at least one RO indicated may be an RO that has successfully performed a listen-before-talk (LBT). In one embodiment, the method may also include starting at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication.

[0008] According to some embodiments, an apparatus may include a circuit system configured to provide at least one random access channel opportunity (RO) to at least one lower layer. The circuit system may also be configured to optionally receive at least one indication of at least one RO from at least one lower layer. The at least one RO indicated may be an RO that has successfully performed a listen-before-talk (LBT). In one embodiment, the circuit system may be configured to start at least one timer, the at least one timer being configured to monitor at least one control channel based on the at least one indication. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a proper understanding of the present disclosure, reference should be made to the accompanying drawings, in which:

[0010] Figure 1 An example of a method performed by a user equipment according to some embodiments is shown.

[0011] Figure 2 An example of a system according to some embodiments is shown. DETAILED DESCRIPTION

[0012] It will be readily appreciated that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of some example embodiments of systems, methods, apparatuses, and computer program products for random access procedures, such as when operating in an unlicensed spectrum, is not intended to limit the scope of certain embodiments, but rather is representative of selected example embodiments.

[0013] The features, structures, or characteristics of the example embodiments described throughout this specification may be combined in any suitable manner in one or more example embodiments. For example, the use of the phrases "certain embodiments," "some embodiments," or other similar language throughout this specification refers to the fact that a particular feature, structure, or characteristic described in conjunction with an embodiment may be included in at least one embodiment. Thus, the phrases "certain embodiments," "in some embodiments," "in other embodiments," or other similar language appearing throughout the specification do not necessarily all refer to the same set of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments.

[0014] In addition, if desired, the different functions or steps discussed below may be performed in different orders and / or concurrently with each other. In addition, if desired, one or more of the described functions or steps may be optional or may be combined. Therefore, the following description should be considered as merely an illustration of the principles and teachings of certain example embodiments, rather than a limitation thereof.

[0015] 3GPP RP-181339 includes an update to TR 38.889, where both 4-step and 2-step random access channel (RACH) procedures will be supported for unlicensed NR (NR-U). For the 4-step RACH procedure, the messages in chronological order are named msg1, msg2, msg3, msg4, while for the 2-step RACH procedure, the messages are named msgA and msgB. Specifically, the 2-step RACH procedure includes two steps to complete a complete contention-based random access (CBRA). The 2-step RACH procedure can reduce the impact of listen-before-talk (LBT) by reducing the number of messages. However, to further reduce the impact of LBT failure, additional RACH message opportunities may be introduced for both the 4-step and 2-step RACH procedures, such as in the time domain or frequency domain. In particular, the additional opportunities for the 4-step RACH procedure may be applicable to both msg1 and msg3. NR-U may support contention-free random access (CFRA) and CBRA for both 2-step and 4-step RACH procedures. For the secondary cell (SCell), CFRA may be supported as a baseline, while the special cell (SpCell) supports both CBRA and CFRA. A single RACH process i may be used, and NR-U may not support multiple RACH processes in parallel. As a baseline, the random access response of msg1 may be on the SpCell, while msg3 may assume the use of a predetermined hybrid automatic repeat request (HARQ) identity (ID).

[0016] In the legacy RACH process, counters for preamble transmission and power ramp may be incremented with each attempt. In NR-U, when the preamble is not transmitted due to LBT failure, the power ramp may not be applied. Therefore, an indication may be transmitted from the physical (PHY) layer to the MAC to indicate LBT failure / success. In addition, when the preamble is not transmitted due to LBT failure, the ra-ResponseWindow may not be started. It is assumed that the ra-ContentionResolutionTimer may need to be extended to a larger value to overcome the impact of LBT.

[0017] For a two-step RACH procedure, msgA may be a signal for detecting UEs and payloads, while the second message msgB may be used for contention resolution for CBRA with possible payloads. msgA may include at least information equivalent to that transmitted in msg1 and msg3 of a four-step RACH procedure. Contention resolution in a two-step RACH procedure may be performed by including a UE identifier in the first message, which may be transmitted back in the second message.

[0018] Due to possible LBT failures, some data transmissions may not occur when the channel is busy. Therefore, it may be necessary to provide more opportunities to transmit RACH messages. For example, the MAC may indicate to the lower layer (e.g., the physical layer) multiple RACH opportunities (ROs) for which to attempt preamble transmission, and the preamble transmission may be based on the LBT results.

[0019] Once the random access preamble is transmitted, and regardless of the possible occurrence of measurement gaps, the MAC entity may start a timer and monitor control channel transmissions. For example, as specified in 3GPP NR Release 15, if a contention-free random access preamble for a beam failure recovery request is transmitted, the MAC entity may start the ra-ResponseWindow configured in BeamFailureRecoveryConfig at the first physical downlink control channel (PDCCH) timing from the end of the random access preamble transmission, and while the ra-ResponseWindow is running, monitor the PDCCH transmission on the search space indicated by the recoverySearchSpaceId of the SpCell identified by the cell radio network temporary identifier (C-RNTI). In another example, the MAC entity may start the ra-ResponseWindow configured in RACH-ConfigCommon at the first PDCCH timing from the end of the random access preamble transmission, and while the ra-ResponseWindow is running, monitor the PDCCH of the SpCell to obtain a random access response identified by a random access radio network identifier (RA-RNTI). If notification of a PDCCH transmission received on the search space is received from lower layers on the serving cell where the preamble was transmitted, if the PDCCH transmission is addressed to the C-RNTI, and if a contention-free random access preamble for a beam failure recovery request is transmitted by the MAC entity, the MAC entity may consider the random access procedure to be successfully completed. Otherwise, if a downlink assignment has been received on the PDCCH for the RA-RNTI and the received transport block (TB) is successfully decoded, and if the random access response includes a MAC subprotocol data unit (subPDU) with a backoff indicator, the MAC entity may set PREAMBLE_BACKOFF to the value of the backoff indicator (BI) field of the MAC subPDU, multiplied by the SCALING_FACTOR_BI, using Table 7.2-1. Otherwise, the MAC entity may set PREAMBLE_BACKOFF to 0ms. Finally, if the random access response contains a MAC subPDU with a random access preamble identifier corresponding to the transmitted PREAMBLE_INDEX, the MAC entity may consider the random access response reception to be successful.

[0020] When the MAC layer indicates multiple transmission opportunities to the PHY layer to attempt preamble transmission by indicating multiple ROs with preambles in either or both of the frequency domain and the time domain, the RAR window start for each RO may be different, especially when the RO is in the time domain. In addition, even in the frequency domain, different ROs may be associated with different RA-RNTIs. For the Release-15 scheme, the MAC layer can select just one RO and preamble for the PHY layer to transmit, where the MAC layer knows which RA-RNTI and RAR window start time to use. However, when multiple transmission opportunities are provided to the PHY layer, this may not be possible for the MAC. In addition, a PHY layer that only provides an LBT failure / success indication is not feasible because there may be multiple LBT success opportunities, for example, in the frequency domain, but where the PHY layer only transmits one preamble. In this case, for example, it may be impossible to know the correct RA-RNTI to monitor or the correct time position to start the RAR window.

[0021] Similarly, for 2-step RACH, different ROs may be linked to at least one different physical uplink shared channel (PUSCH) resource for msg A. The starting point for msgB monitoring may vary depending on the RO and PUSCH selected by the PHY layer.

[0022] Certain embodiments described herein may enable the MAC layer to begin correctly monitoring the RAR window for random access response message reception and / or the msgB window for msgB message reception (which may be specified by a contention resolution timer). For example, monitoring may begin at the first PDCCH timing from the end of the actual RA preamble / PUSCH transmission. In addition, certain embodiments may monitor the correct RNTI, such as RA-RNTI or C-RNTI, so that responses to preamble transmissions can be correctly monitored. In addition, this may also allow the use of an appropriate length for the RAR window. In addition, since the RO indicates whether the CBRA / CFRA preamble is actually monitored, certain embodiments may enable correct processing of the received RAR. Therefore, certain embodiments relate to improvements in computer-related technologies, specifically, by saving network resources and reducing power consumption of network entities and / or user equipment located within the network.

[0023] Some embodiments described herein may include transmitting a low layer indication to the MAC layer, with at least one indication of at least one RO, where the RA preamble is actually transmitted by the low layer. In one embodiment, the low layer may be a PHY layer, and therefore, the RA preamble may be transmitted by the PHY layer. As a result, the MAC layer may start at least one RAR window at the first PDCCH opportunity from the end of the actual RA preamble transmission and may utilize the correct search space. In certain embodiments, for a 2-step RACH process, at least one monitoring window of msgB may start at the correct time, such as the first PDCCH opportunity after a PUSCH transmission linked to the selected RO and / or PUSCH. In one embodiment, the MAC layer may monitor at least one correct RNTI, such as a RA-RNTI and / or C-RNTI, as a response to the preamble transmission. In one embodiment, the MAC layer may monitor at least one random access response using an appropriate length of the RAR window. The MAC layer may properly handle the received RAR because at least one RO will indicate whether a CBRA and / or CFRA preamble was transmitted.

[0024] In some embodiments, when all leading attempts for the provided RO fail LBT, at least one LBT failure indication may be indicated only from the lower layer to the MAC layer. Based on the at least one LBT failure indication, the MAC layer does not start the RAR window. Additionally and / or alternatively, the LBT failure indication is not provided to the MAC layer from the lower layer or may not include at least one indication for at least one RO, wherein the MAC layer may be configured to interpret the lack of at least one indication for at least one RO as the occurrence of LBT failure for all ROs.

[0025] In some embodiments, at least one RO selected by the PHY layer may be signaled to the MAC layer, and the MAC layer may be configured to determine at least one RAR window start point and / or end point. For example, at least one RAR window start point may be the earliest possible start point among all start points of at least one signaled RO, and / or at least one RAR window end point may be the latest possible end point among all end points of at least one signaled RO. In addition, in one embodiment, at least one RNTI to be monitored by the MAC layer may include all possible RNTIs from at least one signaled RO.

[0026] In some embodiments, at least one RO selected by the PHY layer may belong to at least one LBT subband of the operating service cell bandwidth and / or carrier. The LBT subband may include, for example, a carrier of a 20MHz portion, and a carrier may include multiple such LBT subbands. In some embodiments, when the MAC layer indicates multiple transmission opportunities to the PHY layer by using a preamble to indicate multiple ROs to attempt preamble transmission, the ROs may belong to different LBT subbands. In certain embodiments, at least one LBT subband of the RO selected by the PHY layer may be signaled to the MAC layer. As a result, the MAC layer may start at least one RAR window at the first PDCCH opportunity from the end of the actual RA preamble transmission, and may utilize the correct search space associated with the LBT subband indicated by the PHY layer. In some embodiments, the RAR window starts and / or monitors within the LBT subband indicated by the PHY layer. Therefore, in some embodiments, the indication from the PHY layer to the MAC may include the RO information or the LBT subband information of the transmitted random access preamble or both the RO information and the LBT subband information.

[0027] In some embodiments, if no signaling from the PHY layer is received, the MAC layer can be configured to use at least one RAR window to assume that at least one RO has been used. For example, in this case, the starting point can be the earliest possible starting point of all possible ROs, and the ending point can be the latest possible ending point of all possible ROs. In addition, the at least one RNTI that the MAC layer can be configured to monitor can be associated with at least one or all RNTIs from at least one signaled RO.

[0028] In some embodiments, the MAC layer may communicate at least one priority order to the PHY layer for at least one selected RO, for example, to configure the PHY layer to select at least one CFRA RO over at least one CBRA RO when both have successful LBT.

[0029] In some embodiments, the lower layer may indicate to the MAC layer all ROs for which LBT has been successfully performed within at least one given time slot, and the MAC layer may select one RO from all ROs to transmit at least one preamble.

[0030] Figure 1 An example flow chart of a method according to one embodiment is shown. In some embodiments, Figure 1 The method may be performed by a network entity or node associated with a communication system (such as 5G or NR). According to one embodiment, Figure 1 The method may be performed by, for example, a mobile station, a mobile device, a UE, an IoT device, a terminal, etc. Additionally or alternatively, Figure 1The method may be performed by a base station, an access node, an evolved Node B (eNB) or a next generation Node B (gNB), a next generation radio access network (NG RAN), a serving gateway, a server and / or any other access node or a combination thereof. For example, in one embodiment, one or more steps of the method may be performed by a MAC layer or MAC entity of a UE, such as discussed below. Figure 2 UE 210 shown in .

[0031] like Figure 1 As shown in the example of , in step 101, the method may include providing at least one random access channel opportunity (RO) (also referred to as physical random access channel opportunity / PRACH opportunity) to at least one physical layer. In step 103, the method may include, optionally, receiving at least one indication of at least one RO from at least one physical layer. According to certain embodiments, the reception 103 of at least one indication may be optional, because in some embodiments, the indication may not be transmitted by the PHY. In one embodiment, when at least one indication is received, the at least one indicated RO is an RO for which LBT has been successfully performed. In addition, in one embodiment, the indicated at least RO is where the random access preamble is transmitted.

[0032] According to certain embodiments, in step 105, the method may further include starting at least one timer configured to monitor at least one control channel, such as a PDCCH, based on the received at least one indication. In some embodiments, the method may further optionally include, in step 107, transmitting at least one random access preamble (RAP) on one RO of the indicated at least one RO.

[0033] According to some embodiments, based on at least one indication of at least one RO received from at least one lower layer (eg, PHY), the method may include starting at least one RAR window at a first PDCCH opportunity.

[0034] In some embodiments, if at least one notification of at least one PRACH opportunity (i.e., RO) has been received from at least one lower layer and if at least one contention-free random access preamble for a beam failure recovery request is transmitted, a medium access control (MAC) entity may start at least one random access response window (e.g., ra-ResponseWindow) at the first PDCCH opportunity following the PRACH opportunity indicated by the end of the RAP transmission (e.g., which may be configured in BeamFailureRecoveryConfig).

[0035] In one embodiment, the first physical downlink control channel (PDCCH) opportunity is the first physical downlink control channel (PDCCH) after at least one RO indicated by at least one physical layer.

[0036] According to some embodiments, based on at least one indication received from the PHY layer, the method may include starting to monitor a random access radio network temporary identifier (RA-RNTI) or a cell radio network temporary identifier (C-RNTI) for a response to at least one RAP transmission. In one example, the cell radio network temporary identifier (C-RNTI) may be monitored in the event that a contention-free random access preamble for beam failure is transmitted. According to one embodiment, the method may also include receiving a random access response and correctly processing the received random access response assuming that at least one RO indicates whether a CBRA or CFRA preamble is actually transmitted.

[0037] In some embodiments, the method may further include determining a RAR window start point and an end point. For example, the start point may be determined as the earliest possible start point among all start points of the at least one RO included in the at least one indication, and the end point may be determined as the latest possible end point among all end points of the at least one RO included in the at least one indication. In an example embodiment, the method may include monitoring all possible RNTIs from the at least one RO included in the at least one indication.

[0038] According to certain embodiments, if at least one indication for at least one RO is not received from at least one PHY layer, then at least one random access preamble transmission has failed. For example, in one embodiment, when at least one indication for at least one RO is not received from at least one PHY layer, then the MAC entity may consider that the preamble transmissions for all ROs have failed and do not start the RAR window.

[0039] In some embodiments, if at least one indication of at least one RO is not received from at least one physical layer, the method may include determining a start point and an end point of the RAR window and / or monitoring all possible RNTIs from at least one RO provided to at least one physical layer. For example, in this example, the start point may be determined as the earliest possible start point of all start points of at least one RO provided to the PHY layer, and the end point may be determined as the latest possible end point of all end points of at least one RO provided to the PHY layer.

[0040] In one embodiment, the method may further include providing, to at least one PHY layer, a priority order for a plurality of ROs provided to the at least one PHY layer. According to some embodiments, the method may include receiving, from at least one PHY layer, an indication of at least one RO that successfully performed LBT within a given time slot, and selecting which of the at least one RO that successfully performed LBT to signal to the RAP.

[0041] Additionally or alternatively, the method may include monitoring at least one PDCCH transmission on at least one search space while a random access response window (e.g., ra-ResponseWindow) is running, for example, as indicated by a recovery search space identifier (e.g., recoverySearchSpaceId) of at least one SpCell identified by at least one C-RNTI.

[0042] In certain embodiments, if at least one notification of a PRACH opportunity has been received from at least one lower layer (e.g., a PHY layer), the MAC entity may start a RA response window (e.g., ra-ResponseWindow) configured in RACH-ConfigCommon at the first PDCCH opportunity after the PRACH opportunity indicated by the end of the RAP transmission. Additionally or alternatively, while the ra-ResponseWindow is running, the MAC entity may monitor the PDCCH of the SpCell to obtain at least one random access response identified by the RA-RNTI corresponding to the indicated PRACH opportunity. Otherwise, in some embodiments, the MAC entity may perform at least one RAP selection process.

[0043] Figure 2 An example of a system according to some embodiments is shown. In one embodiment, the system may include multiple devices, such as, for example, a user equipment 210 and a network entity 220. The UE 210 may include one or more of the following: a mobile station, a mobile device, a mobile phone, a smart phone, a personal digital assistant (PDA), a tablet, an IoT device, a portable media player, a digital camera, a pocket camera, a video game console, a navigation unit (such as a global positioning system (GPS) device), a desktop or laptop computer, a single location device (such as a sensor or a smart meter), or any combination thereof.

[0044] The network entity 220 may be one or more of: a base station, an eNB or gNB, a NG RAN, a serving gateway, a server and / or any other access node or a combination thereof.

[0045] One or more of these devices may include at least one processor, indicated as 211 and 221, respectively. At least one memory may be provided in one or more of the devices indicated as 212 and 222. The memory may be fixed or removable. The memory may include computer program instructions or computer code contained therein. The processors 211 and 221 and the memories 212 and 222, or a subset thereof, may be configured to provide corresponding Figure 1 Although not shown, the device may also include positioning hardware, such as a global positioning system (GPS) or micro-electromechanical system (MEMS) hardware, which can be used to determine the location of the device. Other sensors are also permitted and may be included to determine location, altitude, direction, etc., such as a barometer, compass, etc.

[0046] like Figure 2 As shown, transceivers 213 and 223 may be provided, and one or more devices may also include at least one antenna, shown as 214 and 224, respectively. The device may have many antennas, such as an antenna array configured for multiple-input multiple-output (MIMO) communication, or multiple antennas for multiple radio access technologies. For example, other configurations of these devices may be provided.

[0047] The transceivers 213 and 223 may be transmitters, receivers, or both transmitters and receivers, or may be configured as units or devices for transmission and reception.

[0048] Processors 211 and 221 may be embodied by any computing or data processing device, such as a central processing unit (CPU), an application specific integrated circuit (ASIC), or the like. The processor may be implemented as a single controller, or multiple controllers or processors.

[0049] Memories 212 and 222 may independently be any suitable storage device, such as a non-concurrent computer readable medium. A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memory may be combined on a single integrated circuit as a processor, or may be separate from one or more processors. In addition, the computer program instructions stored in the memory and processable by the processor may be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language. The memory may be removable or non-removable.

[0050] The memory and the computer program instructions may be configured together with a processor for a particular device to cause a hardware device (such as user device 210) to perform any of the above embodiments, steps, methods or processes, such as in combination with, for example, Figure 1Thus, in some embodiments, a non-transitory computer-readable medium may be encoded with computer instructions that, when executed in hardware, perform a process such as one or more of the processes, methods, or steps described herein. Alternatively, some embodiments may be implemented entirely in hardware.

[0051] In some embodiments, the apparatus may include a Figure 1 As shown in or in combination with the above Figure 1 The circuit system of any process or function discussed. For example, the circuit system can be a pure hardware circuit implementation, such as an analog and / or digital circuit system. In another example, the circuit system can be a combination of hardware circuits and software, such as a combination of (multiple) analog and / or digital hardware circuits with software or firmware, and / or any part of (multiple) hardware processors (including (multiple) digital signal processors) with software, software and at least one memory, which work together to enable the device to perform various processes or functions. In yet another example, the circuit system can be (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a part of (multiple) microprocessors, which include software, such as firmware for operation. When the operation of the hardware does not require software, the software in the circuit system may not exist.

[0052] Therefore, certain example embodiments provide several technical improvements, enhancements and / or advantages. For example, the example embodiments enable the MAC layer or entity to correctly start RAR window / random access response message monitoring, for example, at the first PDCCH opportunity from the end of the actual RA preamble / PUSCH transmission using the correct search space. In addition, the example embodiments enable the MAC layer or entity to use the appropriate length of the RAR window to monitor the correct RNTI (e.g., RA-RNTI or C-RNTI) in response to the preamble transmission, and correctly process the received RAR assuming that the RO will inform whether the CBRA / CFRA preamble was actually transmitted. Therefore, the use of certain example embodiments results in improved functionality of communication networks and nodes thereof (including, for example, UEs, base stations, eNBs, or gNBs).

[0053] In some example embodiments, the functionality of any method, process, signaling diagram, algorithm, or flow chart described herein may be implemented by software and / or computer program code or code portions stored in a memory or other computer-readable or tangible medium, and executed by a processor.

[0054] Those of ordinary skill in the art will readily appreciate that certain embodiments discussed above may be practiced with steps in different orders and / or with hardware elements in configurations different from those disclosed. Therefore, certain modifications, variations, and alternative configurations will be clear to those skilled in the art while still being within the spirit and scope of the present invention. Therefore, in order to determine the limits and scope of the present invention, reference should be made to the appended claims.

[0055] Partial Glossary

[0056] 3GPP Third Generation Partnership Project

[0057] 5G 5th Generation Wireless System

[0058] CBRA Contention-based random access

[0059] CE Coverage Enhancement

[0060] CFRA Contention-free random access

[0061] CN Core Network

[0062] COT Channel Occupancy Time

[0063] C-RNTI Cell Radio Network Temporary Identifier

[0064] DCI Downlink Control Information

[0065] DL Downlink

[0066] DRS Discovery Reference Signal

[0067] eMTC Enhanced Machine Type Communication

[0068] eNB Evolved Node B

[0069] E-UTRAN Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network

[0070] gNB Next Generation Node B

[0071] LBT Listen before you speak

[0072] LTE Long Term Evolution

[0073] MAC Media Access Control

[0074] MIMO Multiple Input Multiple Output

[0075] MME Mobility Management Entity

[0076] NE Network Entity

[0077] NR New Radio (5G)

[0078] NR-U New Radio - Unlicensed

[0079] PBCH Physical Broadcast Channel

[0080] PDCCH Physical Downlink Control Channel

[0081] PDU Protocol Data Unit

[0082] PHY Physical Layer

[0083] PRACH Physical Random Access Channel

[0084] PUSCH Physical Uplink Shared Channel

[0085] RA Random Access

[0086] RACH Random Access Channel

[0087] RAN Radio Access Network

[0088] RAR Random Access Response

[0089] RA-RNTI Random Access Radio Network Temporary Identifier

[0090] RMSI Remaining Minimum System Information

[0091] RO Random access channel opportunity

[0092] SRS Sounding Reference Signal

[0093] SS Sync Signal

[0094] TB Transfer Block

[0095] UE User Equipment

Claims

1. A method for communication, comprising: Providing at least one random access channel opportunity RO to at least one lower layer; receiving at least one indication of at least one RO from the at least one lower layer; as well as starting at least one random access response window at a first control channel opportunity based on the at least one indication; wherein the at least one indicated RO has successfully performed listen-before-talk, and at least one random access preamble has been transmitted on one of the at least one indicated ROs; Wherein when the at least one indication is not received from the at least one lower layer, the method further comprises: determining that the at least one random access preamble transmission has failed; as well as Determine a start point and an end point of a random access response window, wherein the start point is determined as the earliest possible start point among all start points of the at least one RO provided to the lower layer, and the end point is determined as the latest possible end point among all end points of the at least one RO provided to the at least one lower layer.

2. The method according to claim 1, wherein the at least one random access response window is started if at least one contention-free random access preamble for a beam failure recovery request is transmitted.

3. The method according to claim 1, wherein the first control channel opportunity is a first physical downlink control channel (PDCCH) opportunity after the at least one RO indicated by the at least one lower layer.

4. The method of claim 1 , wherein starting the at least one random access response window comprises: determining a random access response window start point and an end point, wherein the start point is determined as an earliest possible start point among all start points of the at least one RO included in the at least one indication, and the end point is determined as a latest possible end point among all end points of the at least one RO included in the at least one indication; as well as All possible radio network temporary identifiers are monitored from the at least one RO included in the at least one indication.

5. The method according to claim 1, further comprising: While the random access response window is running, at least one PDCCH transmission is monitored on at least one search space, the at least one search space being indicated by a search space identifier of at least one special cell, the at least one special cell being identified by at least one cell radio network temporary identifier C-RNTI.

6. The method according to claim 5, further comprising: The random access procedure is deemed to be successfully completed if a notification of reception of at least one downlink control channel transmission on the at least one search space is received from the at least one lower layer on the serving cell on which the preamble is transmitted, if the at least one downlink control channel transmission is addressed to the at least one C-RNTI, and if a contention-free random access preamble for a beam failure recovery request is transmitted.

7. The method according to claim 1, further comprising: Based on the at least one indication, start monitoring at least one of a random access radio network temporary identifier RA-RNTI or a C-RNTI corresponding to the at least one RO indicated by the at least one lower layer for a response to the at least one random access preamble transmission.

8. The method of claim 7, wherein the C-RNTI is monitored in at least one of the following cases: when a contention-free random access preamble for beam failure is transmitted, or when msgA for a 2-step random access channel is transmitted.

9. The method according to claim 1, further comprising: receiving a random access response; as well as The received random access response is processed given that the at least one RO indicates whether a contention-based random access preamble or a contention-free random access preamble is actually transmitted.

10. The method according to claim 1, wherein: When the at least one indication is not received from the at least one lower layer, the method further comprises: All possible radio network temporary identifiers are monitored from the at least one RO provided to the at least one lower layer.

11. The method according to any one of claims 1 to 10, wherein providing the at least one RO to the at least one lower layer further comprises: The priority order of the at least one RO is provided to the at least one lower layer.

12. An apparatus for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: Providing at least one random access channel opportunity RO to at least one lower layer; receiving at least one indication of at least one RO from the at least one lower layer; and starting at least one random access response window at a first control channel opportunity based on the at least one indication; wherein the at least one indicated RO has successfully performed listen-before-talk, and at least one random access preamble has been transmitted on one of the at least one indicated ROs; wherein when the at least one indication is not received from the at least one lower layer, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: determining that the at least one random access preamble transmission has failed; as well as Determine a start point and an end point of a random access response window, wherein the start point is determined as the earliest possible start point among all start points of the at least one RO provided to the lower layer, and the end point is determined as the latest possible end point among all end points of the at least one RO provided to the at least one lower layer.

13. The apparatus of claim 12, wherein the at least one random access response window is started if at least one contention-free random access preamble for a beam failure recovery request is transmitted.

14. The apparatus according to claim 12, wherein the first control channel opportunity is a first physical downlink control channel (PDCCH) opportunity after the at least one RO indicated by the at least one lower layer.

15. The apparatus of claim 12, wherein when starting the at least one random access response window, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: determining a random access response window start point and an end point, wherein the start point is determined as the earliest possible start point of all start points of the at least one RO included in the at least one indication, and the end point is determined as the latest possible end point of all end points of the at least one RO included in the at least one indication; and All possible radio network temporary identifiers are monitored from the at least one RO included in the at least one indication.

16. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: While the random access response window is running, at least one PDCCH transmission is monitored on at least one search space, the at least one search space being indicated by a search space identifier of at least one special cell, the at least one special cell being identified by at least one cell radio network temporary identifier C-RNTI.

17. The apparatus of claim 16, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: The random access procedure is deemed to be successfully completed if a notification of reception of at least one downlink control channel transmission on the at least one search space is received from the at least one lower layer on the serving cell on which the preamble is transmitted, if the at least one downlink control channel transmission is addressed to the at least one C-RNTI, and if a contention-free random access preamble for a beam failure recovery request is transmitted.

18. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: Based on the at least one indication, start monitoring at least one of a random access radio network temporary identifier RA-RNTI or a C-RNTI corresponding to the at least one RO indicated by the at least one lower layer for a response to the at least one random access preamble transmission.

19. The apparatus of claim 18, wherein the C-RNTI is monitored in at least one of the following cases: when a contention-free random access preamble for beam failure is transmitted, or when msgA for a 2-step random access channel is transmitted.

20. The apparatus of claim 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: receiving a random access response; and The received random access response is processed given that the at least one RO indicates whether a contention-based random access preamble or a contention-free random access preamble is actually transmitted.

21. The device according to claim 12, wherein: When the at least one indication is not received from the at least one lower layer, the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: All possible radio network temporary identifiers are monitored from the at least one RO provided to the at least one lower layer.

22. The apparatus according to any one of claims 12 to 21, wherein when providing the at least one RO to the at least one lower layer, the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: The priority order of the at least one RO is provided to the at least one lower layer.

23. A computer readable medium for communication, comprising computer program instructions stored thereon, the computer program instructions being configured to perform at least the following: Providing at least one random access channel opportunity RO to at least one lower layer; receiving at least one indication of at least one RO from the at least one lower layer; and starting at least one random access response window at a first control channel opportunity based on the at least one indication; wherein the at least one indicated RO has successfully performed listen-before-talk, and at least one random access preamble has been transmitted on one of the at least one indicated ROs; Wherein when the at least one indication is not received from the at least one lower layer, the computer program instructions are further configured to perform at least the following: determining that the at least one random access preamble transmission has failed; and Determine a start point and an end point of a random access response window, wherein the start point is determined as the earliest possible start point among all start points of the at least one RO provided to the lower layer, and the end point is determined as the latest possible end point among all end points of the at least one RO provided to the at least one lower layer.

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