Resource selection for random access

Abstract

Methods, systems, and devices for wireless communications are described. The described techniques provide for selecting a RO based on downlink quality, access congestion, latency (e.g., time to the next available PRACH opportunity (RO)), beam correspondence, random access in a previous transmission, or a combination of these factors. A user equipment (UE) can detect access congestion of a synchronization signal block (SSB) and select a less congested SSB in RO selection. The UE can detect access congestion by receiving a backoff indicator from a base station, detecting a contention resolution failure, or the number of medium access control (MAC) subheaders in a random access response. In some cases, ROs associated with different SSBs have different latency, and the UE can select the earliest available RO.

Description

[0001] Priority information

[0002] This patent application claims the benefit of priority to U.S. non-provisional application No. 16 / 818,796, filed on March 13, 2020, entitled “RESOURCE SELECTION FOR RANDOM ACCESS,” which is assigned to the assignee of this application and is hereby expressly incorporated herein by reference. Technical Field

[0003] The following relates generally to wireless communications, and more particularly to resource selection for random access. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, etc. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency and power). Examples of such multiple access systems include fourth generation (4G) systems (e.g., long term evolution (LTE) systems, improved LTE (LTE-A) systems or LTE-A Pro systems) and fifth generation (5G) systems (which may be referred to as new radio (NR) systems). These systems may use technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA) or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each base station or network access node simultaneously supporting communication for multiple communication devices (which may be further referred to as user equipment (UE)).

[0005] A wireless device (e.g., user equipment (UE)) may communicate with a base station using a random access channel (RACH) mapped to a physical random access channel (PRACH). The UE may select time and frequency resources (e.g., PRACH opportunities) for sending the PRACH. In some cases, the base station may fail to receive the PRACH. Therefore, techniques for improving the selection of PRACH opportunities for sending the PRACH may be desired. Summary of the invention

[0006] The described technology relates to improved methods, systems, devices and apparatuses for supporting resource selection for random access. In summary, the described technology provides for selecting a random access opportunity (e.g., RO, which may also be referred to as a RACH opportunity) based on downlink quality, access congestion, latency (e.g., time to the next available physical random access channel (PRACH) opportunity (RO)), beam correspondence, random access in a previous transmission, or a combination of these factors. The UE may detect access congestion of a synchronization signal block (SSB) and select a less congested SSB in RO selection (e.g., using a soft preference metric or a hard avoidance metric). The UE may detect access congestion by receiving a backoff indicator from a base station, detecting a contention resolution failure, or the number of medium access control (MAC) subheaders in a random access response. In some cases, ROs associated with different SSBs have different latency, and the UE may select the earliest available RO. In other cases, the UE may select a RO with a beam per link (BPL) associated with a beam having corresponding quality and directivity. Additionally or alternatively, for example, when performing a power ramp-up procedure on a retransmission, the UE may select a RO with a previously selected BPL.

[0007] A method of wireless communication at a UE is described. The method may include: determining to perform a random access procedure with a base station; receiving a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks; determining, for each synchronization signal block in the set of synchronization signal blocks, a received power and a value of one or more additional parameters for random access opportunity selection; and sending a first message of the random access procedure to the base station in a random access opportunity selected from the set of random access opportunities based on the received power and the values ​​of the one or more additional parameters.

[0008] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to perform the following operations: determine to perform a random access procedure with a base station; receive a synchronization signal block set in a synchronization signal block set, wherein each random access opportunity in a random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; for each synchronization signal block in the synchronization signal block set, determine a received power and a value of one or more additional parameters for random access opportunity selection; and send a first message of the random access procedure to the base station in a random access opportunity selected from the random access opportunity set based on the received power and the value of the one or more additional parameters.

[0009] Another apparatus for wireless communication at a UE is described. The apparatus may include means for performing the following operations: determining to perform a random access procedure with a base station; receiving a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks; determining, for each synchronization signal block in the set of synchronization signal blocks, a received power and a value of one or more additional parameters for random access opportunity selection; and sending a first message of the random access procedure to the base station in a random access opportunity selected from the set of random access opportunities based on the received power and the values ​​of the one or more additional parameters.

[0010] A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor to perform the following operations: determine to perform a random access procedure with a base station; receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks; for each synchronization signal block in the set of synchronization signal blocks, determine a received power and a value of one or more additional parameters for random access opportunity selection; and send a first message of the random access procedure to the base station in a random access opportunity selected from the set of random access opportunities based on the received power and the values ​​of the one or more additional parameters.

[0011] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more additional parameters may include operations, features, units, or instructions for performing the following operations: selecting the random access timing corresponding to the synchronization signal block based on the received power and the value of a congestion parameter associated with the synchronization signal block in the synchronization signal block set.

[0012] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access timing based on the received power and the value of the congestion parameter may include operations, features, units, or instructions for performing the following operations: determining the value of the congestion parameter based on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof; and selecting the random access timing based on the received power and the value of the congestion parameter.

[0013] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: determining that the received power that reduces the value of the congestion parameter for the synchronization signal block can be greater than each other received power that reduces the corresponding value of the congestion parameter for each other synchronization signal block in the synchronization signal block set.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: for each synchronization signal block in the set of synchronization signal blocks, identifying a selection probability value based on the values ​​of the received power and the congestion parameter; and selecting the random access opportunity corresponding to the synchronization signal block based on the selection probability value corresponding to the synchronization signal block.

[0015] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: identifying that the value of the congestion parameter associated with at least one synchronization signal block in the synchronization signal block set may have exceeded a threshold value associated with a backoff indication, a number of contention resolution failures, or a combination thereof; and excluding the at least one synchronization signal block from selection by the UE based on the identification.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more additional parameters may include operations, features, units, or instructions for performing the following operations: selecting the random access timing corresponding to the synchronization signal block based on the received power and the value of the timing parameter associated with the random access timing corresponding to the synchronization signal block.

[0017] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: excluding the at least one random access opportunity based on determining that at least one random access opportunity in the random access opportunity set exceeds a delay threshold for the timing parameter.

[0018] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: determining two or more synchronization signal blocks in the synchronization signal block set that are associated with a received power that satisfies a received power threshold; identifying two or more random access opportunities corresponding to the two or more synchronization signal blocks; and selecting the random access opportunity from the two or more random access opportunities based on the random access opportunity that is closest in time, the value of the timing parameter corresponding to the random access opportunity that is closest in time.

[0019] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more additional parameters may include operations, features, units, or instructions for performing the following operations: selecting the random access timing corresponding to the synchronization signal block based on the received power and the value of the beam correspondence parameter associated with the random access timing corresponding to the synchronization signal block.

[0020] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following operations: excluding the at least one synchronization signal block from selection by the UE based on identifying that the UE previously failed to receive a random access response from the base station using a beam pair link associated with at least one synchronization signal block in the set of synchronization signal blocks.

[0021] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the random access opportunity corresponding to the synchronization signal block may include operations, features, units, or instructions for performing the following operations: determining that the value of the beam correspondence parameter for the synchronization signal block corresponding to the random access opportunity exceeds each other value of the beam correspondence parameter for each other synchronization signal block in the set of synchronization signal blocks.

[0022] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more additional parameters may include operations, features, units, or instructions for performing the following operations: selecting the random access timing corresponding to the synchronization signal block based on the received power and the value of the beam pair link history parameter associated with the synchronization signal block in the synchronization signal block set.

[0023] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the beam pair link history parameter indicates that the synchronization signal block may be associated with a beam pair link previously established between the UE and the base station.

[0024] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the beam pair link history parameter indicates that the synchronization signal block may be associated with a beam pair link that may have failed less than a threshold number of times.

[0025] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more additional parameters include a congestion parameter, a latency parameter, a beam correspondence parameter, a beam-pair link history parameter, or a combination thereof.

[0026] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first message of the random access process may include operations, features, units, or instructions for performing the following operations: monitoring message 2 of the four-step random access process or message B of the two-step random access process on a receiving beam, and the receiving beam may be based on the random access timing selected for sending the first message of the random access process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1

[0013] An example of a system for wireless communication supporting resource selection for random access in accordance with aspects of the present disclosure is shown.

[0028] Figure 2 An example of a wireless communication system supporting resource selection for random access in accordance with aspects of the present disclosure is shown.

[0029] Figure 3 An example of a process flow supporting resource selection for random access in accordance with aspects of the present disclosure is shown.

[0030] Figure 4 and 5 A block diagram of an apparatus supporting resource selection for random access in accordance with aspects of the present disclosure is shown.

[0031] Figure 6 A block diagram of a communications manager supporting resource selection for random access in accordance with aspects of the present disclosure is shown.

[0032] Figure 7 A diagram of a system including devices supporting resource selection for random access is shown in accordance with aspects of the present disclosure.

[0033] Figures 8 to 12 A flow chart illustrating a method of supporting resource selection for random access according to aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0034] The UE may communicate with the base station using a random access channel (RACH) mapped to a physical random access channel (PRACH). The UE may select time and frequency resources for sending the PRACH and a RACH preamble index. A PRACH opportunity (RO) (e.g., which may also be referred to as a RACH opportunity) may be defined as a time and frequency resource on which the UE may send a random access message (such as the first message of a random access procedure using a configured PRACH preamble format (e.g., message 1 of a four-step random access procedure or message A of a two-step random access procedure)) in a random access procedure on a corresponding directional beam. Resources for the PRACH opportunity (RO) may be configured via a system information block (SIB) and / or radio resource control (RRC) signaling.

[0035] The UE can determine the initial beam per link (BPL) between the base station and the UE by measuring the strongest reference signal received power (RSRP) from the synchronization signal block (SSB) and selecting the associated RO on which to send the PRACH. In some examples, the UE can select the RO to use the power ramp-up process to retransmit message 1 of the four-step random access process (for example, if the UE does not receive message 2 during the random access response window), however, if the UE and the base station switch BPLs (for example, due to access congestion or mismatched transmit / receive beams), the power ramp-up may be ineffective. In other examples, the RO configuration mapping may occur in a semi-periodic manner, which may cause latency issues (for example, the base station may instruct the UE to wait for the selection of an appropriate RO in terms of uplink / downlink quality).

[0036] The UE may select a RO based on downlink quality, access congestion, latency (e.g., time to the next available RO), beam correspondence, or random access in a previous PRACH transmission. The UE may detect access congestion of an SSB and select the least congested SSB in RO selection. The UE may detect access congestion by receiving a backoff indicator from a base station. The backoff indicator may indicate that a large number of UEs are concentrated in an area of ​​a cell, and even if the UE implements power ramping, the UE may have better communication success by selecting a different BPL with a less congested path.

[0037] In some cases, ROs associated with different SSBs have different latencies, and the UE may select the earliest available RO. The base station may send the RO configuration to the UE in a semi-periodic manner, and the UE may have to wait (e.g., up to 160ms) to configure the RO. Therefore, the UE may switch to another SSB and associated RO instead of waiting.

[0038] In other cases, the UE may select a RO with a BPL associated with a beam with corresponding quality and directivity. The UE may determine whether there is a mismatch between the transmit beam and the receive beam based on an offline characterization of the spherical coverage or through online detection. After this determination, the UE may select the RO with the minimum path loss with the transmit beam. In another case, when a power ramp-up procedure is performed on a retransmission, the UE may select a RO with a previously selected BPL. Maintaining the previously selected BPL during the power ramp-up procedure may increase the chances of the base station detecting the UE when the base station receives a stronger signal.

[0039] As described herein, the first message of the random access message may be message 1 of the four-step random access procedure or message A of the two-step random access procedure. Where an example is described as being applicable to message 1, such an example may also be applicable to message A, and vice versa. Furthermore, where an example is described as being applicable to message 2 of the four-step random access procedure, such an example may also be applicable to message B of the two-step random access procedure, and vice versa.

[0040] Various aspects of the disclosure are first described in the context of wireless communication systems. In addition, various aspects of the disclosure are illustrated by additional wireless communication systems, examples of RO selection, and process flows. Various aspects of the disclosure are further illustrated by apparatus diagrams, system diagrams, and flow diagrams involving techniques for selecting a RO, and various aspects of the disclosure are described with reference to these diagrams.

[0041] Figure 1 An example of a wireless communication system 100 supporting resource selection for random access according to aspects of the present disclosure is shown. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a long term evolution (LTE) network, an improved LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, or communications with low-cost and low-complexity devices, or any combination thereof.

[0042] Base stations 105 may be dispersed throughout a geographic area to form wireless communication system 100, and may be devices of different forms or capabilities. Base stations 105 and UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which UEs 115 and base stations 105 may establish one or more communication links 125. Coverage area 110 may be an example of a geographic area over which base stations 105 and UEs 115 may support transmission of signals according to one or more radio access technologies.

[0043] UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary, mobile, or both at different times. UEs 115 may be devices of different forms or with different capabilities. Figure 1 Some example UEs 115 are shown in FIG. 1. The UEs 115 described herein can communicate with various types of devices, such as other UEs 115, base stations 105, or network devices (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network devices), such as Figure 1 shown.

[0044] The base stations 105 may communicate with the core network 130, or communicate with each other, or perform both operations. For example, the base stations 105 may interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3 or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105) on the backhaul links 120 (e.g., via X2, Xn or other interfaces), or communicate with each other indirectly (e.g., via the core network 130), or perform both operations. In some examples, the backhaul links 120 may be or include one or more wireless links.

[0045] One or more of the base stations 105 described herein may include or may be referred to by those skilled in the art as a base station transceiver, a radio base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next generation Node B, or a Gigabit Node B (any of which may be referred to as a gNB), a Home Node B, a Home Evolved Node B, or some other appropriate terminology.

[0046] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other appropriate terminology, where a "device" may also be referred to as a unit, a station, a terminal, or a client, among other examples. UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, among other examples, which may be implemented in various items such as appliances, or vehicles, meters, and among other examples.

[0047] The UE 115 described herein is capable of communicating with various types of devices, such as other UEs 115, which may sometimes act as relays, as well as base stations 105 and network devices, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, such as Figure 1 shown.

[0048] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term "carrier" may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion of a radio frequency spectrum band (e.g., a bandwidth portion (BWP)) that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling to coordinate operations for the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers.

[0049] In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be placed according to a channel grid to be discovered by a UE 115. A carrier may operate in a standalone mode, where a UE 115 performs initial acquisition and connection via a carrier, or a carrier may operate in a non-standalone mode, where a different carrier (e.g., of the same or different radio access technology) is used to anchor the connection.

[0050] The communication link 125 shown in the wireless communication system 100 may include an uplink transmission from the UE 115 to the base station 105, or a downlink transmission from the base station 105 to the UE 115. A carrier may carry downlink or uplink communications (e.g., in FDD mode) or may be configured to carry both downlink and uplink communications (e.g., in TDD mode).

[0051] A carrier may be associated with a particular bandwidth of a radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or wireless communication system 100. For example, the carrier bandwidth may be one of a number of determined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)). A device of the wireless communication system 100 (e.g., a base station 105, a UE 115, or both) may have a hardware configuration that supports communication on a particular carrier bandwidth, or may be configurable to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 or a UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate on a portion (e.g., a subband, a BWP) or all of a carrier bandwidth.

[0052] The signal waveform transmitted on the carrier may be composed of multiple subcarriers (e.g., using multicarrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, wherein the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Therefore, the more resource elements received by the UE 115 and the higher the order of the modulation scheme, the higher the data rate for the UE 115 can be. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity for communication with the UE 115.

[0053] One or more digital schemes for a carrier may be supported, where the digital scheme may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs with the same or different digital schemes. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communications for a UE 115 may be limited to the one or more active BWPs.

[0054] The basic time unit (which may be referred to as T s =1 / (Δf max ·N f ) seconds sampling period, where Δf max It can represent the maximum supported subcarrier spacing, and N f The time intervals for the base station 105 or the UE 115 may be expressed as multiples of a maximum supported discrete Fourier transform (DFT) size). The time intervals of the communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0055] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a number of symbol periods (e.g., depending on the length of a cyclic prefix added in front of each symbol period). In some wireless communication systems 100, a time slot may be further divided into a plurality of micro-time slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0056] A subframe, a time slot, a mini-time slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in the form of bursts of shortened TTIs (sTTIs)).

[0057] Physical channels may be multiplexed on a carrier according to various techniques. For example, one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique may be used to multiplex physical control channels and physical data channels on a downlink carrier. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by the number of symbol periods and may extend across the system bandwidth of a carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a group of UEs 115. For example, one or more of the UEs 115 may monitor or search a control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to multiple UEs 115 and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0058] Each base station 105 can provide communication coverage via one or more cells (e.g., macro cells, small cells, hot spots or other types of cells, or any combination thereof). The term "cell" can refer to a logical communication entity used to communicate with the base station 105 (e.g., on a carrier), and can be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID) or other identifier) ​​for distinguishing adjacent cells. In some examples, a cell can also refer to a geographic coverage area 110 or a portion of a geographic coverage area 110 (e.g., a sector) on which a logical communication entity operates. Depending on various factors (such as the capabilities of the base station 105), the range of such a cell can range from a smaller area (e.g., a structure, a subset of a structure) to a larger area. For example, a cell can be or include a building, a subset of a building, or an external space between or overlapping geographic coverage areas 110, as well as other examples.

[0059] A macro cell typically covers a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by a UE 115 with a service subscription to a network provider that supports the macro cell. A small cell may be associated with a lower power base station 105 than a macro cell, and the small cell may operate in the same or different (e.g., licensed, unlicensed) frequency band as the macro cell. A small cell may provide unrestricted access to a UE 115 with a service subscription to a network provider, or may provide restricted access to a UE 115 associated with a small cell (e.g., a UE 115 in a closed subscriber group (CSG), a UE 115 associated with a user in a residence or office). A base station 105 may support one or more cells, and may also support the use of one or more component carriers to communicate on one or more cells.

[0060] In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access to different types of devices.

[0061] In some examples, base stations 105 may be mobile and, therefore, provide communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of base stations 105 provide coverage for respective geographic coverage areas 110 using the same or different radio access technologies.

[0062] The wireless communication system 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timing, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timing, and in some examples, transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

[0063] Some UEs 115 (e.g., MTC or IoT devices) may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents the information to a human interacting with the application. Some UEs 115 may be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0064] Some UEs 115 may be configured to employ an operating mode that reduces power consumption, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception rather than transmission and reception simultaneously). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for UE 115 include entering a power-saving deep sleep mode when not participating in active communications, when operating on a limited bandwidth (e.g., according to narrowband communications), or a combination of these techniques. For example, some UEs 115 may be configured to operate using a narrowband protocol type that is associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of a carrier, or outside a carrier.

[0065] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. UE115 can be designed to support ultra-reliable, low-latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication can include private communication or group communication, and can be supported by one or more mission-critical services (such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData). Support for mission-critical functions can include prioritization of services, and mission-critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency can be used interchangeably in this article.

[0066] In some examples, UE 115 may be able to communicate directly with other UE 115 on a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communication may be within a geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, wherein each UE 115 transmits to each other UE 115 in the group. In some examples, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving the base station 105.

[0067] In some systems, the D2D communication link 135 can be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, the vehicles can communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these items. The vehicle can use signals to send information related to traffic conditions, signal scheduling, weather, safety, emergency situations, or any other information related to the V2X system. In some examples, the vehicle in the V2X system can communicate with roadside infrastructure (such as a roadside unit), or communicate with the network via one or more network nodes (e.g., base station 105) using vehicle-to-network (V2N) communication, or both operations.

[0068] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connection, and other access, routing or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function unit (AMF)) for managing access and mobility and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function unit (UPF)) for routing packets to an external network or interconnecting to an external network. The control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management for UE115 served by a base station 105 associated with the core network 130. User IP packets may be transmitted through a user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to a network operator IP service 150. Operator IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0069] Some of the network devices (e.g., base stations 105) may include subcomponents such as access network entities 140, which may be examples of access node controllers (ANCs). Each access network entity 140 may communicate with the UE 115 through one or more other access network transport entities 145 (which may be referred to as radio heads, smart radio heads, or transmit / receive points (TRPs)). Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or merged into a single network device (e.g., base station 105).

[0070] The wireless communication system 100 may operate using one or more frequency bands, for example, in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Typically, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, but the waves may be sufficient to penetrate structures for macro cells to provide service to UEs 115 located indoors. Transmissions using UHF waves may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to transmissions using smaller frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0071] The wireless communication system 100 may also operate in a super high frequency (SHF) region using a frequency band from 3 GHz to 30 GHz (also referred to as a centimeter band) or in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) (also referred to as a millimeter band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communications between UE 115 and base station 105, and the EHF antenna of the corresponding device may be even smaller and more closely spaced than the UHF antenna. In some examples, this may facilitate the use of antenna arrays within the device. However, the propagation of EHF transmissions may suffer from even greater atmospheric attenuation and shorter distances than SHF or UHF transmissions. The technology disclosed herein may be employed across transmissions using one or more different frequency regions, and the designated use of frequency bands across these frequency regions may differ according to countries or regulatory agencies.

[0072] The wireless communication system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 can employ license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (such as the 5 GHz industrial, scientific, and medical (ISM) band). When operating in an unlicensed radio frequency spectrum band, devices (such as base stations 105 and UEs 115) can employ carrier sensing for conflict detection and avoidance. In some examples, operations in unlicensed bands can be based on a carrier aggregation configuration in combination with component carriers operating in a licensed band (e.g., LAA). Operations in the unlicensed spectrum can include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, as well as other examples.

[0073] The base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or UE 115 may be located within one or more antenna arrays or antenna panels (which may support MIMO operations or transmit or receive beamforming). For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, the antennas or antenna arrays associated with the base station 105 may be located at different geographical locations. The base station 105 may have an antenna array having a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals sent via the antenna ports.

[0074] The base station 105 or UE 115 can use MIMO communication to exploit multipath signal propagation and improve spectral efficiency by sending or receiving multiple signals via different spatial layers. Such a technology may be referred to as spatial multiplexing. For example, a transmitting device may send multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO) (where multiple spatial layers are sent to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are sent to multiple devices).

[0075] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., a base station 105, a UE 115) to form or direct an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array so that some signals propagating in a specific orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals transmitted via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each of the antenna elements may be defined by a set of beamforming weights associated with a specific orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0076] As part of the beamforming operation, the base station 105 or the UE 115 may use beam scanning techniques. For example, the base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communications with the UE 115. The base station 105 may send some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) multiple times in different directions. For example, the base station 105 may send signals based on different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used (e.g., by a transmitting device (such as the base station 105) or by a receiving device (such as the UE 115)) to identify a beam direction for subsequent transmission or reception by the base station 105.

[0077] Base station 105 may transmit some signals (e.g., data signals associated with a particular receiving device (e.g., UE 115)) in a single beam direction (e.g., a direction associated with the receiving device). In some examples, the beam direction associated with transmission along the single beam direction may be determined based on signals transmitted in one or more beam directions. For example, UE 115 may receive one or more of the signals transmitted by base station 105 in different directions and may report to base station 105 an indication of the signal received by UE 115 having the highest signal quality or otherwise acceptable signal quality.

[0078] In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) may be performed using multiple beam directions, and the device may generate a combined beam for transmission (e.g., from the base station 105 to the UE 115) using a combination of digital precoding or radio frequency beamforming. The UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. The base station 105 may send reference signals (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)) that may or may not be precoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type of codebook, a linear combination type of codebook, a port selection type of codebook). Although these techniques are described with reference to signals sent by base station 105 in one or more directions, UE 115 may employ similar techniques to send signals multiple times in different directions (e.g., to identify a beam direction for subsequent transmission or reception by UE 115) or to send signals in a single direction (e.g., to send data to a receiving device).

[0079] When receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from the base station 105, the receiving device (e.g., UE 115) can try multiple reception configurations (e.g., directional listening). For example, the receiving device can try multiple reception directions by receiving via different antenna subarrays, by processing the received signals according to different antenna subarrays, by receiving according to different reception beamforming weight sets applied to the signals received at multiple antenna elements of the antenna array (e.g., different directional listening weight sets), or by processing the received signals according to different reception beamforming weight sets applied to the signals received at multiple antenna elements of the antenna array (any of the above operations may be referred to as "listening" according to different reception configurations or reception directions). In some examples, the receiving device can use a single reception configuration to receive along a single beam direction (e.g., when receiving a data signal). A single receive configuration may be aligned on a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0080] The wireless communication system 100 may be a packet-based network operated according to a layered protocol stack. In the user plane, the communication at the bearer or packet data convergence protocol (PDCP) layer may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly to transmit on a logical channel. The medium access control (MAC) layer may perform priority handling and multiplexing of logical channels to transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide the establishment, configuration, and maintenance of an RRC connection (which supports radio bearers for user plane data) between a UE 115 and a base station 105 or a core network 130. At the physical layer, transport channels may be mapped to physical channels.

[0081] UE 115 and base station 105 can support retransmission of data to increase the possibility that the data is successfully received. Hybrid automatic repeat request (HARQ) feedback is a technology for increasing the possibility that data is correctly received on communication link 125. HARQ can include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC) and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve the throughput at the MAC layer under poor radio conditions (e.g., low signal and noise conditions). In some examples, the device can support the same time slot HARQ feedback, wherein the device can provide HARQ feedback for data received in the previous symbol in the time slot in a specific time slot. In other cases, the device can provide HARQ feedback in subsequent time slots or according to some other time interval.

[0082] UE 115 may seek to acquire time and frequency synchronization with base station 105 (e.g., cell) and detect the physical layer cell ID (PCI) of the cell. UE 115 may monitor SSBs from base station 105 when UE 115 is powered on, during mobility in connected mode, during idle mode mobility (e.g., cell selection or reselection), during inter-RAT mobility, or otherwise during a random access process. For example, UE 115 may tune to the frequency of the cell and then attempt to receive and decode one or more of the SSBs that may be sent by a base station (e.g., cell). In some examples, one or more beamforming techniques may be used to beam scan the SSBs. Each SSB may include a primary synchronization signal (PSS) (e.g., in the first symbol period of the SSB), a secondary synchronization signal (SSS) (e.g., in the third symbol period of the SSB), a physical broadcast channel (PBCH) (e.g., in the second, third, and fourth symbols of the SSB), and a demodulation reference signal (DMRS) for the PBCH. UE 115 may use NR synchronization signals (e.g., PSS and SSS) and PBCH to derive information for UE 115 to access a cell.

[0083] In some examples, UE 115 performing a random access procedure may include: UE 115 (e.g., from base station 105) receiving a random access configuration. In some examples, the random access configuration may indicate time and frequency resources for ROs (the term RO may be used interchangeably with RACH opportunities or PRACH opportunities herein) for the UE to use to send a random access preamble. In some examples, the random access configuration may indicate how many ROs are allocated in the frequency domain and / or how many ROs are allocated in the time domain.

[0084] In some wireless communication systems, UE 115 may determine whether to utilize a two-step random access procedure or a four-step random access procedure. If a two-step RACH is performed, the UE may send a preamble (e.g., a RACH preamble) and a payload (e.g., a RACH payload), which may be collectively referred to as message A (MsgA), before receiving a random access response (RAR) from the base station. If a four-step RACH is performed, the UE may send a RACH preamble, referred to as message 1 (Msg1), before receiving a RAR (e.g., in the first two steps of the four-step random access procedure). The UE may then send message 3 (Msg3), which may be an example of an uplink data payload, and may receive message 4 (Msg4) in response from the base station. The UE may use the random access procedure to obtain uplink synchronization with the base station and obtain resources for sending a random access payload (such as an RRC connection request). In some cases, when UE 115 (e.g., a high-capability UE) has the ability to utilize multiple antennas, higher transmit / receive bandwidth, etc., UE 115 may utilize a four-step random access procedure because it may be more robust than a two-step random access procedure.

[0085] A wireless device operating in a licensed or unlicensed spectrum within an NR network may participate in a two-step random access procedure or a four-step random access procedure to establish an initial connection or re-establish a connection with a base station 105. The two-step random access procedure may reduce the time required for the UE 115 and the base station 105 to establish a connection compared to the four-step random access procedure. For example, when the UE 115 is performing a listen-before-talk (LBT) procedure associated with the random access procedure, the two-step random access procedure may reduce the delay in establishing a connection due to the reduced number of LBT procedures associated with the two-step random access procedure. In some cases, for example, if the signal quality is poor, the four-step RACH procedure may increase the chance that the UE 115 can successfully establish a communication link 125 with the base station 105.

[0086] In some examples, UE 115 may select a RO based on downlink quality, access congestion, latency (e.g., time to the next available RO), beam correspondence, random access in previous transmission, or a combination of these factors. UE 115 may detect access congestion of an SSB and select a less congested SSB in RO selection (e.g., using a soft preference metric or a hard avoidance metric). UE 115 may detect access congestion by receiving a backoff indicator from a base station, detecting contention resolution failure, or the number of MAC subheaders in a random access response. In some cases, ROs associated with different SSBs have different latency, and UE 115 may select the earliest available RO. In other cases, UE 115 may select a RO with a BPL associated with a beam having corresponding quality and directivity. Additionally or alternatively, for example, when a power ramp-up process is performed on a retransmission, UE 115 may select a RO with a previously selected BPL.

[0087] Figure 2 An example of a wireless communication system 200 that supports resource selection for random access according to aspects of the present disclosure is shown. In some examples, the wireless communication system 200 can implement aspects of the wireless communication system 100. The wireless communication system 200 can include a base station 105-a and a UE 115-a, which can be respectively as described herein with reference to Figure 1 Examples of corresponding base stations 105 and UEs 115 are described in detail. In some cases, UE 115-a and base station 105-a can communicate on resources (e.g., channels, beams, beam pair links (BPLs), PRACHs, etc.) of communication link 205. In addition, communication on communication link 205 can be performed via a communication protocol as described herein. Figure 1 The beamforming transmission described is performed.

[0088] The base station 105-a may provide network coverage for the geographic area 110-a. The base station 105-a and the UE 115-a may communicate using beamforming or directional transmissions as well as non-beamforming transmissions. For example, in downlink communications, the base station 105-a may send a downlink transmission to the UE 115-a using a beamformed downlink transmission beam 210, which may be one of a plurality of downlink transmission beams used by the base station 105-a, such as downlink transmission beams 210-a, 210-b, 210-c, and 210-d. The UE 115-a may send an uplink transmission to the base station 105-a using a beamformed uplink transmission beam 215, which may be one of a plurality of uplink transmission beams used by the UE 115-a, such as uplink transmission beams 215-a, 215-b, 215-c, and 215-d.

[0089] In some cases, the base station 105-a may transmit the SSB via the downlink transmission beam 210. The uplink transmission beam 215 of the UE 115-a may be linked to the downlink transmission beam 210. In some cases, each corresponding transmit beam pair may be referred to as a BPL, and the UE 115-a and the base station 105-a may configure the BPLs, and may perform switching between the configured BPLs based on channel conditions. In some cases, beamforming transmissions may switch BPLs relatively quickly, for example, when the UE 115-a moves quickly relative to the base station 105-a (e.g., when the UE 115-a is on, inside, or part of a car, train, or other vehicle), or when temporary interference sources may affect the transmission beam (e.g., the user of the UE 115-a may move their hand so that the antenna panel at the UE 115-a is blocked, or a vehicle or machine may move into the beam path of the transmission beam). UE 115-a can monitor the downlink transmission beam 210 from the base station 105-a to determine the best BPL on which to communicate with UE 115a, where the BPL includes the downlink transmission beam 210 and the uplink transmission beam 215 that follow the same path (for example, the BPL may include the downlink transmission beam 210-c from the base station 105-a and the uplink transmission beam 215-c from the UE 115-a). The best BPL can be the BPL with the highest received power or quality (for example, the highest reference signal received quality (RSRQ), received signal strength indicator (RSSI), reference signal received power (RSRP), signal to interference plus noise ratio (SINR), or signal to noise ratio (SNR), etc.) compared to other BPLs.

[0090] The UE 115-a may select a RO 220 (such as RO 220-a, 220-b, 220-c, and 220-d) to transmit the PRACH on the communication link 205 in the BPL between the UE 115-a and the base station 105-a. The selected RO 220 (e.g., RO 220-c) may be associated with an SSB or other reference signal transmitted by the base station 105-a. The UE 115-a may select the RO 220-c based on measuring the strongest signal strength or quality (e.g., RSRP) from the downlink transmission beam 210-c. For example, the UE 115-a may measure and determine that the strongest signal from the SSB is from the downlink transmission beam 210-c, and then select the corresponding RO 220-c in the uplink transmission beam 215-c on which the PRACH is to be transmitted.

[0091] In some examples, base station 105-a may fail to receive PRACH from UE 115-a due to access congestion (e.g., low signal-to-noise ratio (SNR), high interference from other UEs, signal collisions from other UEs attempting to access ROs associated with the same SSB, etc.). In contention-based random access, preambles and ROs of PRACH transmissions from multiple UEs may collide. Access congestion may occur when multiple UEs in close proximity in the coverage area of ​​a base station attempt to access ROs associated with the same SSB.

[0092] UE 115-a may detect access congestion and select an RO with a less congested SSB. UE 115-a may detect access congestion by receiving a backoff indicator from base station 105-a. Base station 105-a may detect multiple UEs causing access congestion and send a backoff indicator (e.g., a beam-specific indicator) to UE 115-a indicating that UE 115-a should wait for an amount of time before attempting to access the congested SSB. In some examples, UE 115-a may detect access congestion by a failure or multiple failures of contention resolution (e.g., based on matching or exceeding a threshold number of failures) or by the number of MAC subheaders with a random access preamble identifier (RAPID) and a random access response (RAR).

[0093] In some cases, UE 115-a may select a RO associated with a less congested SSB through a soft preference approach. For example, UE 115-a may derive a congestion metric (e.g., a congestion parameter) based on a backoff indicator, the number of contention resolution failures, or the number of MAC subreports. UE 115-a may determine the probability of selecting a RO using a congestion metric or other selection metric related to a RO selection metric (e.g., based on RSRP). UE 115-a may determine (e.g., based on the beam selected by UE 115-a) a threshold (e.g., a received power threshold (such as an RSRP threshold) or a received quality threshold (such as RSRQ)) and select a RO that meets the threshold. In some examples, a base station (such as base station 105-a or another base station 105) may have configured UE 115-a with a threshold, and UE 115-a may identify such a threshold for selecting a RO.

[0094] In other cases, UE 115-a may select a RO associated with a less congested SSB through a hard avoidance approach. UE 115-a may determine a threshold based on a backoff indicator, a number of contention resolution failures, or a number of MAC subheaders. When an SSB exceeds a threshold, UE 115-a may avoid the SSB and the associated RO.

[0095] In some examples, the base station 105-a may transmit the SSB according to a periodicity different from the RO configuration period (e.g., up to 20 ms) of the RO 220 associated with the corresponding SSB. For example, the RO and SSB association mapping may be repeated up to every 160 ms, and the base station 105-a may instruct the UE 115-a to wait for a suitable RO 220 to be available in terms of uplink and downlink quality. The UE 115-a may use latency information (e.g., timing parameters) of the SSB when selecting the RO 220. For example, the UE 115-a may not select a RO 220 corresponding to an SSB that is available outside a threshold amount of time. The UE 115-a may switch BPL to receive another SSB that corresponds to a RO 220 that the UE 115-a may access sooner. The UE 115-a may select the earliest available RO 220 based on a RO selection metric, which may be a function of the RO latency or RSRP (e.g., an associated reference signal within a threshold (such as a dB threshold)).

[0096] In some examples, for random access, UE 115-b may measure downlink transmissions from base station 105-a and select RO to send PRACH on uplink transmissions based on the downlink. However, this relies on the transmit and receive beams of UE 115-a being corresponding. A beam (e.g., uplink transmission beam 215-c) may include a main lobe and a side lobe. Uplink transmission beam 215-c and downlink transmission beam 210-c may form a BPL. The main lobes and side lobes in beams 215-c and 210-c may be aligned or may not be aligned. For example, a user of UE 115-a may move their hands so that the antenna panel at UE 115-a is blocked, for example, because the number of antenna arrays placed on UE 115-a is limited, sometimes the best reception of SSB may be through the side lobes. When the side lobes of beams 215-c and 210-c are not aligned, the side lobes may not correspond in directionality, and there may be a discontinuity between the uplink and downlink quality. Additionally or alternatively, the maximum permitted exposure (MPE) may result in an asymmetry between downlink and uplink quality. UE 115-a may measure high quality downlink transmissions on a downlink beam, however, the corresponding uplink beam may have severe limitations in uplink quality because transmissions in that uplink beam may result in higher exposure to humans than transmissions on other antenna arrays or beams.

[0097] UE 115-a may select a RO having a BPL associated with a beam correspondence (e.g., a beam correspondence parameter). UE 115-a may determine whether there is a mismatch between uplink and downlink beams based on offline characterization or online detection of spherical coverage (e.g., failure to receive a RAR with a correct RAPID after power ramp-up, or failure to receive a response after sending message 1 of a four-step random access procedure or message A of a two-step random access procedure may indicate a directional difference in the beams). UE 115-a may determine the corresponding RO and associated beam that implement the soft preference or hard avoidance metric described herein. UE 115-a may switch the RO and associated SSB in a PRACH retransmission after determining the corresponding BPL.

[0098] In some examples, UE 115-a may not increase power ramping when a different BPL is selected for retransmission of a random access channel (RACH) preamble (e.g., such as message 1 of a four-step random access procedure). If UE 115-a selects a different BPL, the PRACH receive power at base station 105-a may remain constant. UE 115-a may prioritize a previously selected BPL (e.g., a BPL history parameter) or SSB when retransmitting PRACH. Maintaining the previously selected BPL may allow UE 115-a to power ramp up and obtain successful communication with base station 105-a. When UE 115-a power ramps up on a previously selected BPL, the SNR may increase, the path loss may decrease, and the likelihood of being heard by base station 105-a may be higher. If UE 115-a were to switch to a stronger BPL, base station 105-a may not detect the retransmission of PRACH because there may be no power increase from the same BPL. The UE 115-a may determine to maintain a previously selected BPL by implementing the hysteresis, soft preference, or hard avoidance metrics described herein.

[0099] In some examples, if a threshold number of retransmissions fails or a threshold amount of power (e.g., a configured or preconfigured value in dB) is consumed after a power ramp up on a previously selected BPL, the UE 115-a can switch to another BPL. If the associated SSB is less congested or the SSB associated with the previously selected BPL is supported by the sidelobe coverage of the beam, the UE 115-a can switch to another BPL.

[0100] Figure 3 An example of a process flow 300 for supporting resource selection for random access according to aspects of the present disclosure is shown. In some examples, the process flow 300 can implement aspects of the wireless communication system 100. The process flow 300 can include a base station 105-b and a UE 115-b, which can be respectively as described herein with reference to Figure 1 The corresponding base station 105 and UE 115 described herein are respectively as referred to in Figure 2 Examples of corresponding base stations 105-a and UEs 115-a are described.

[0101] At 305, UE 115-b may determine to perform a random access procedure (e.g., a PRACH or RACH procedure) with a base station. In some examples, the random access procedure may be a four-step random access procedure. In other examples, the random access procedure may be a four-step random access procedure. In yet another example, the random access procedure may be another type of random access procedure that performs at least process flow 300 as part of the random access procedure.

[0102] At 310, UE 115-b may receive multiple SSBs in an SSB set from base station 105-b, wherein each random access opportunity (e.g., RO) in a random access opportunity set (e.g., an RO set, which may include multiple ROs) corresponds to at least one SSB in the SSB set.

[0103] At 315, UE 115-b may determine, for each of a plurality of SSBs, a receive power and values ​​of one or more additional parameters for random access timing selection. The one or more additional parameters may include a congestion parameter, a delay parameter, a beam correspondence parameter, or a BPL history parameter. Determination by UE 115-b of the receive power and values ​​of one or more additional parameters for random access timing selection for each SSB may improve selection of an RO for sending a first message (e.g., message 1 or message A) of a random access procedure (e.g., a four-step or two-step random access procedure), improve reliability, and reduce latency. For UE 115-b, including for a chip (e.g., a processor and / or memory) of UE 115-b, such determination may increase reliability, reduce processing power, reduce signaling overhead, improve network efficiency, and other benefits.

[0104] In some examples, the one or more additional parameters include a congestion parameter for the SSB. The UE 115-b may select a random access opportunity corresponding to the SSB based on the received power and the value of the congestion parameter associated with the SSB in the plurality of SSBs. The UE 115-b may determine the value of the congestion parameter based on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof. In some cases, the UE 115-b may determine that the received power reduced by the value of the congestion parameter for the SSB is greater than each other received power reduced by the corresponding value of the congestion parameter for each other SSB in the plurality of SSBs. In other cases, the UE 115-b may identify a selection probability value for each SSB in the plurality of SSBs based on the received power and the value of the congestion parameter, and may select a random access opportunity corresponding to the SSB based on the selection probability value corresponding to the SSB.

[0105] UE 115-b may identify that a value of a congestion parameter associated with one or more SSBs among a plurality of SSBs has exceeded a threshold associated with a backoff indication, a number of contention resolution failures, or a combination thereof. UE 115-b may exclude one or more SSBs from selection by UE 115-b based on the identification. Specific implementations of the subject matter described herein may be implemented to achieve one or more potential advantages. UE 115-b selects an RO corresponding to an SSB among a plurality of SSBs based on received power and a value of a congestion parameter associated with the SSB, which may improve selection of an RO for transmitting a PRACH, increase reliability, and reduce latency. For a chip (e.g., a processor and / or memory) of UE 115-b, such selection may increase reliability, reduce processing power, reduce signaling overhead, improve network efficiency, and other benefits.

[0106] In some examples, the one or more additional parameters include a timing parameter. The UE 115-b may select a random access opportunity corresponding to the SSB based on the received power and the value of the timing parameter associated with the random access opportunity corresponding to the SSB. The UE 115-b may exclude the at least one random access opportunity in the random access opportunity set based on determining that at least one random access opportunity exceeds the delay threshold for the timing parameter. In some cases, the UE 115-b may determine two or more SSBs associated with the received power that satisfies the received power threshold among the multiple SSBs, and identify two or more random access opportunities corresponding to the two or more SSBs. The UE 115-b may select a random access opportunity from the two or more random access opportunities based on the random access opportunity that is closest in time, and the value of the timing parameter corresponds to the random access opportunity that is closest in time. The UE 115-b selects the random access opportunity corresponding to the SSB based on the received power and the value of the timing parameter associated with the random access opportunity corresponding to the SSB, which can improve the selection of the RO for sending the PRACH, increase reliability and reduce latency. For the chips (e.g., processor and / or memory) of UE 115-b, such selection may increase reliability, reduce processing power, reduce signaling overhead, improve network efficiency, among other benefits.

[0107] In some examples, the one or more additional parameters include a beam correspondence parameter. The UE 115-b may select a random access opportunity corresponding to the SSB based on the received power and the value of the beam correspondence parameter associated with the random access opportunity corresponding to the SSB. The UE 115-b may exclude one or more of the multiple SSBs from the UE's selection based on identifying that the UE 115-b previously failed to receive a random access response from the base station using the BPL associated with one or more of the multiple SSBs. In some cases, the UE 115-b may determine that the value of the beam correspondence parameter for the SSB corresponding to the random access opportunity exceeds each other value of the beam correspondence parameter for each other SSB in the multiple SSBs. The UE 115-b may make a selection based on the received power and the value of the beam correspondence parameter associated with the random access opportunity corresponding to the SSB. Selecting a random access opportunity corresponding to the SSB may improve the selection of an RO for transmitting the PRACH, and increase reliability and reduce latency. For the chips (e.g., processor and / or memory) of UE 115-b, such selection may increase reliability, reduce processing power, reduce signaling overhead, improve network efficiency, among other benefits.

[0108] In some examples, one or more additional parameters include a BPL history parameter for an SSB. UE 115-b may select a random access opportunity corresponding to the SSB based on the received power and the value of the BPL history parameter associated with the SSB in a plurality of SSBs. In some cases, the BPL history parameter indicates that the SSB is associated with a BPL previously established between UE 115-b and base station 105-b. In other cases, the BPL history parameter indicates that the SSB is associated with a BPL that has failed less than a threshold number of times. UE 115-b may select a random access opportunity corresponding to the SSB based on the received power and the value of the BPL history parameter associated with the SSB in a plurality of SSBs. Selecting a random access opportunity corresponding to an SSB may improve the selection of an RO for sending a PRACH, increase reliability and reduce latency. For a chip (e.g., a processor and / or memory) of UE 115-b, such a selection may increase reliability, reduce processing power, reduce signaling overhead, improve network efficiency, and other benefits.

[0109] At 320, UE 115-b may send a first message of a random access procedure (e.g., including at least a random access preamble) to base station 105-b in a random access opportunity selected from a set of random access opportunities based on received power and values ​​of one or more additional parameters. In some examples, the first message of the random access procedure includes message 1 of a four-step random access procedure or message A of a two-step random access procedure.

[0110] At 325, the UE 115-b may monitor message 2 of the four-step random access procedure or message B of the two-step random access procedure on a receive beam that is based on the random access opportunity selected for sending the first message of the random access procedure.

[0111] Figure 4 A block diagram 400 of a device 405 supporting resource selection for random access according to aspects of the present disclosure is shown. The device 405 may be an example of aspects of a UE 115 as described herein. The device 405 may include a receiver 410, a communication manager 415, and a transmitter 420. The device 405 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0112] The receiver 410 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to resource selection for random access, etc.). The information may be communicated to other components of the device 405. The receiver 410 may be a reference Figure 7Examples of aspects of transceiver 720 are described. Receiver 410 may utilize a single antenna or a collection of antennas.

[0113] The communication manager 415 may perform the following operations: determine to perform a random access procedure with a base station; receive a synchronization signal block set in a synchronization signal block set, wherein each random access opportunity in the random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; for each synchronization signal block in the synchronization signal block set, determine a received power and a value of one or more additional parameters for random access opportunity selection; and send a first message of a random access procedure to the base station in a random access opportunity selected from the random access opportunity set based on the received power and the value of one or more additional parameters. The communication manager 415 may be an example of aspects of the communication manager 710 described herein.

[0114] The communication manager 415 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 415 or its subcomponents may be performed by a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0115] The communication manager 415 or its subcomponents may be physically located at various locations, including being distributed so that portions of the functions are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 415 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 415 or its subcomponents may be combined with one or more other hardware components (including, but not limited to, input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof).

[0116] The transmitter 420 can transmit signals generated by other components of the device 405. In some examples, the transmitter 420 can be co-located with the receiver 410 in a transceiver module. For example, the transmitter 420 can be a reference Figure 7 Examples of aspects of transceiver 720 are described. Transmitter 420 may utilize a single antenna or a collection of antennas.

[0117] Figure 5A block diagram 500 of a device 505 supporting resource selection for random access according to aspects of the present disclosure is shown. The device 505 may be an example of aspects of the device 405 or UE 115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 540. The device 505 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0118] The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to resource selection for random access, etc.). The information may be communicated to other components of the device 505. The receiver 510 may be a reference Figure 7 Examples of aspects of the transceiver 720 are described. The receiver 510 may utilize a single antenna or a collection of antennas.

[0119] Communications manager 515 may be an example of aspects of communications manager 415 as described herein. Communications manager 515 may include random access component 520, SSB receiver 525, SSB parameter component 530, and message transmitter 535. Communications manager 515 may be an example of aspects of communications manager 710 as described herein.

[0120] The random access component 520 may determine to perform a random access procedure with a base station.

[0121] The SSB receiver 525 may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in the set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks.

[0122] The SSB parameter component 530 can determine, for each synchronization signal block in the set of synchronization signal blocks, received power and values ​​of one or more additional parameters for random access opportunity selection.

[0123] The message transmitter 535 may transmit a first message of the random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the values ​​of one or more additional parameters.

[0124] The transmitter 540 can transmit signals generated by other components of the device 505. In some examples, the transmitter 540 can be co-located with the receiver 510 in a transceiver module. For example, the transmitter 540 can be a reference Figure 7 Examples of aspects of transceiver 720 are described. Transmitter 540 may utilize a single antenna or a collection of antennas.

[0125] Figure 6A block diagram 600 of a communication manager 605 supporting resource selection for random access in accordance with aspects of the present disclosure is shown. The communication manager 605 can be an example of aspects of the communication manager 415, the communication manager 515, or the communication manager 710 described herein. The communication manager 1005 can include a random access component 610, an SSB receiver 615, an SSB parameter component 620, and a message transmitter 625. Each of these components can communicate with each other directly or indirectly (e.g., via one or more buses).

[0126] The random access component 610 may determine to perform a random access procedure with a base station.

[0127] In some examples, the random access component 610 can monitor message 2 of the four-step random access procedure or message B of the two-step random access procedure on a receive beam that is based on the random access opportunity selected for sending the first message of the random access procedure.

[0128] The SSB receiver 615 may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in the set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks.

[0129] The SSB parameter component 620 can determine, for each synchronization signal block in the set of synchronization signal blocks, received power and values ​​of one or more additional parameters for random access opportunity selection.

[0130] In some examples, the SSB parameter component 620 can select a random access opportunity corresponding to a synchronization signal block based on the received power and the value of a congestion parameter associated with the synchronization signal block in the synchronization signal block set.

[0131] In some examples, SSB parameter component 620 can determine the value of the congestion parameter based on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof.

[0132] In some examples, the SSB parameter component 620 can select a random access opportunity based on the values ​​of the received power and congestion parameters.

[0133] In some examples, the SSB parameter component 620 can determine that the received power that reduces the value of the congestion parameter for the synchronization signal block is greater than each other received power that reduces the corresponding value of the congestion parameter for each other synchronization signal block in the set of synchronization signal blocks.

[0134] In some examples, the SSB parameter component 620 can identify a selection probability value for each synchronization signal block in the set of synchronization signal blocks based on the values ​​of the received power and congestion parameters.

[0135] In some examples, the SSB parameter component 620 can select a random access opportunity corresponding to the synchronization signal block based on a selection probability value corresponding to the synchronization signal block.

[0136] In some examples, the SSB parameter component 620 can identify that a value of a congestion parameter associated with at least one synchronization signal block in a set of synchronization signal blocks has exceeded a threshold value associated with a backoff indication, a number of contention resolution failures, or a combination thereof.

[0137] In some examples, the SSB parameter component 620 can exclude at least one synchronization signal block from selection by the UE based on the identification.

[0138] In some examples, the SSB parameter component 620 can select a random access opportunity corresponding to a synchronization signal block based on a received power and a value of a timing parameter associated with the random access opportunity corresponding to the synchronization signal block.

[0139] In some examples, the SSB parameter component 620 can exclude at least one random access opportunity based on determining that at least one random access opportunity in the set of random access opportunities exceeds a delay threshold for a timing parameter.

[0140] In some examples, the SSB parameter component 620 can determine two or more synchronization signal blocks in the synchronization signal block set that are associated with a received power that satisfies a received power threshold.

[0141] In some examples, the SSB parameter component 620 can identify two or more random access opportunities corresponding to two or more synchronization signal blocks.

[0142] In some examples, the SSB parameter component 620 can select a random access opportunity from two or more random access opportunities based on a random access opportunity that is closest in time, and the value of the timing parameter corresponds to the random access opportunity that is closest in time.

[0143] In some examples, the SSB parameter component 620 can select a random access opportunity corresponding to a synchronization signal block based on the received power and the value of a beam correspondence parameter associated with the random access opportunity corresponding to the synchronization signal block.

[0144] In some examples, the SSB parameter component 620 can exclude at least one synchronization signal block from selection by the UE based on identifying that the UE previously failed to receive a random access response from a base station using a BPL associated with at least one synchronization signal block in the set of synchronization signal blocks.

[0145] In some examples, the SSB parameter component 620 can determine that the value of the beam correspondence parameter for the synchronization signal block corresponding to the random access opportunity exceeds every other value of the beam correspondence parameter for each other synchronization signal block in the synchronization signal block set.

[0146] In some examples, the SSB parameter component 620 can select a random access opportunity corresponding to a synchronization signal block based on the received power and the value of a congestion parameter associated with the synchronization signal block in the synchronization signal block set.

[0147] In some cases, the BPL history parameter indicates that the synchronization signal block is associated with a BPL previously established between the UE and the base station.

[0148] In some cases, the BPL history parameter indicates that the sync signal block is associated with a BPL that has failed less than a threshold number of times.

[0149] In some cases, the one or more additional parameters include a congestion parameter, a latency parameter, a beam correspondence parameter, a BPL parameter, or a combination thereof.

[0150] The message transmitter 625 may transmit a first message of the random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the values ​​of one or more additional parameters.

[0151] Figure 7 A diagram of a system 700 including a device 705 supporting resource selection for random access according to aspects of the present disclosure is shown. The device 705 may be an example of or include a component of a device 405, a device 505, or a UE 115 as described herein. The device 705 may include components for two-way voice and data communications, including components for sending and receiving communications, including a communication manager 710, an I / O controller 715, a transceiver 720, an antenna 725, a memory 730, and a processor 740. These components may communicate electronically via one or more buses (e.g., a bus 745).

[0152] The communication manager 710 can perform the following operations: determine to perform a random access process with a base station; receive a synchronization signal block set in a synchronization signal block set, wherein each random access opportunity in the random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; for each synchronization signal block in the synchronization signal block set, determine a receiving power and a value of one or more additional parameters for random access opportunity selection; and send a first message of the random access process to the base station in a random access opportunity selected from the random access opportunity set based on the receiving power and the value of one or more additional parameters.

[0153] I / O controller 715 can manage input and output signals for device 705. I / O controller 715 can also manage peripheral devices that are not integrated into device 705. In some cases, I / O controller 715 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 715 can utilize an application such as iOS. ANDROID , MS-DOS 、MS-WINDOWS , OS / 2 ,UNIX 、LINUX , or another known operating system. In other cases, I / O controller 715 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 715 may be implemented as part of a processor. In some cases, a user may interact with device 705 via I / O controller 715 or via hardware components controlled by I / O controller 715.

[0154] The transceiver 720 may communicate bidirectionally via one or more antennas, wired or wireless links as described herein. For example, the transceiver 720 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 720 may also include a modem for modulating packets and providing the modulated packets to an antenna for transmission, and demodulating packets received from an antenna.

[0155] In some cases, a wireless device may include a single antenna 725. However, in some cases, the device may have more than one antenna 725 that are capable of sending or receiving multiple wireless transmissions simultaneously.

[0156] The memory 730 may include RAM and ROM. The memory 730 may store computer-readable, computer-executable code 735, which includes instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 730 may also contain, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0157] The processor 740 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 740 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 740. The processor 740 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 730) to cause the device 705 to perform various functions (e.g., functions or tasks supporting resource selection for random access).

[0158] The code 735 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 735 may be stored in a non-transitory computer-readable medium (e.g., system memory or other types of memory). In some cases, the code 735 may not be directly executable by the processor 740, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0159] Figure 8 A flow chart illustrating a method 800 for supporting resource selection for random access according to aspects of the present disclosure is shown. The operations of the method 800 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 800 may be implemented by a UE 115 or a component thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0160] At 805, the UE may determine to perform a random access procedure with the base station. The operations of 805 may be performed according to the methods described herein. In some examples, aspects of the operations of 805 may be performed as described with reference to Figures 4 to 7 The random access component described is performed.

[0161] At 810, the UE may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks. The operations of 810 may be performed according to the methods described herein. In some examples, aspects of the operations of 810 may be performed as described with reference to Figures 4 to 7 The SSB receiver described is implemented as follows.

[0162] At 815, the UE may determine, for each synchronization signal block in the set of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection. The operations of 815 may be performed according to the methods described herein. In some examples, aspects of the operations of 815 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0163] At 820, the UE may send a first message of a random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on received power and values ​​of one or more additional parameters. The operations of 820 may be performed according to the methods described herein. In some examples, aspects of the operations of 820 may be performed as described with reference to Figures 4 to 7 Describes the message transmitter to perform.

[0164] Fig. 9 A flow chart illustrating a method 900 for supporting resource selection for random access according to aspects of the present disclosure is shown. The operations of the method 900 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 900 may be implemented by a UE 115 or a component thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0165] At 905, the UE may determine to perform a random access procedure with the base station. The operations of 905 may be performed according to the methods described herein. In some examples, aspects of the operations of 905 may be as described with reference to Figures 4 to 7 The random access component described is performed.

[0166] At 910, the UE may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks. The operations of 910 may be performed according to the methods described herein. In some examples, aspects of the operations of 910 may be performed as described with reference to Figures 4 to 7 The SSB receiver described is implemented as follows.

[0167] At 915, the UE may determine, for each synchronization signal block in the set of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection. The operations of 915 may be performed according to the methods described herein. In some examples, aspects of the operations of 915 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0168] At 920, the UE may select a random access opportunity corresponding to a synchronization signal block based on the received power and the value of the congestion parameter associated with the synchronization signal block in the synchronization signal block set. The operations of 920 may be performed according to the methods described herein. In some examples, aspects of the operations of 920 may be performed as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0169] At 925, the UE may send a first message of a random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the value of one or more additional parameters. The operations of 925 may be performed according to the methods described herein. In some examples, aspects of the operations of 925 may be as described with reference to Figures 4 to 7 Describes the message transmitter to perform.

[0170] Fig.10 A flow chart illustrating a method 1000 for supporting resource selection for random access according to aspects of the present disclosure is shown. The operations of the method 1000 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1000 may be implemented by a UE 115 or a component thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0171] At 1005, the UE may determine to perform a random access procedure with the base station. The operations of 1005 may be performed according to the methods described herein. In some examples, aspects of the operations of 1005 may be as described with reference to Figures 4 to 7 The random access component described is performed.

[0172] At 1010, the UE may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks. The operations of 1010 may be performed according to the methods described herein. In some examples, aspects of the operations of 1010 may be performed as described with reference to Figures 4 to 7 The SSB receiver described is implemented as follows.

[0173] At 1015, the UE may determine, for each synchronization signal block in the set of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection. The operations of 1015 may be performed according to the methods described herein. In some examples, aspects of the operations of 1015 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0174] At 1020, the UE may select a random access opportunity corresponding to the synchronization signal block based on the received power and the value of the timing parameter associated with the random access opportunity corresponding to the synchronization signal block. The operations of 1020 may be performed according to the methods described herein. In some examples, aspects of the operations of 1020 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0175] At 1025, the UE may send a first message of a random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the value of one or more additional parameters. The operations of 1025 may be performed according to the methods described herein. In some examples, aspects of the operations of 1025 may be as described with reference to Figures 4 to 7 Describes the message transmitter to perform.

[0176] Fig.11 A flow chart illustrating a method 1100 for supporting resource selection for random access according to aspects of the present disclosure is shown. The operations of the method 1100 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1100 may be implemented by a UE 115 or a component thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0177] At 1105, the UE may determine to perform a random access procedure with the base station. The operations of 1105 may be performed according to the methods described herein. In some examples, aspects of the operations of 1105 may be as described with reference to Figures 4 to 7 The random access component described is performed.

[0178] At 1110, the UE may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks. The operations of 1110 may be performed according to the methods described herein. In some examples, aspects of the operations of 1110 may be performed as described with reference to Figures 4 to 7 The SSB receiver described is implemented as follows.

[0179] At 1115, the UE may determine, for each synchronization signal block in the set of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection. The operations of 1115 may be performed according to the methods described herein. In some examples, aspects of the operations of 1115 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0180] At 1120, the UE may select a random access opportunity corresponding to the synchronization signal block based on the received power and the value of the beam correspondence parameter associated with the random access opportunity corresponding to the synchronization signal block. The operations of 1120 may be performed according to the methods described herein. In some examples, aspects of the operations of 1120 may be performed as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0181] At 1125, the UE may send a first message of a random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the value of the one or more additional parameters. The operations of 1125 may be performed according to the methods described herein. In some examples, aspects of the operations of 1125 may be as described with reference to Figures 4 to 7 Describes the message transmitter to perform.

[0182] Fig.12 A flow chart illustrating a method 1200 for supporting resource selection for random access according to aspects of the present disclosure is shown. The operations of the method 1200 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1200 may be implemented by a UE 115 or a component thereof as described with reference to Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0183] At 1205, the UE may determine to perform a random access procedure with the base station. The operations of 1205 may be performed according to the methods described herein. In some examples, aspects of the operations of 1205 may be as described with reference to Figures 4 to 7 The random access component described is performed.

[0184] At 1210, the UE may receive a set of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in a set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks. The operations of 1210 may be performed according to the methods described herein. In some examples, aspects of the operations of 1210 may be performed as described with reference to Figures 4 to 7 The SSB receiver described is implemented as follows.

[0185] At 1215, the UE may determine, for each synchronization signal block in the set of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection. The operations of 1215 may be performed according to the methods described herein. In some examples, aspects of the operations of 1215 may be as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0186] At 1220, the UE may select a random access opportunity corresponding to a synchronization signal block based on the received power and the value of the beam pair link history parameter associated with the synchronization signal block in the synchronization signal block set. The operation of 1220 may be performed according to the methods described herein. In some examples, aspects of the operation of 1220 may be performed as described with reference to Figures 4 to 7 The SSB parameter components described are implemented.

[0187] At 1225, the UE may send a first message of a random access procedure to the base station in a random access opportunity selected from a set of random access opportunities based on the received power and the value of the one or more additional parameters. The operations of 1225 may be performed according to the methods described herein. In some examples, aspects of the operations of 1225 may be as described with reference to Figures 4 to 7 Describes the message transmitter to perform.

[0188] It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0189] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0190] The information and signals described herein may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0191] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed using a general purpose processor, DSP, ASIC, CPU, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0192] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or sent through a computer-readable medium as one or more instructions or codes. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented in software executed by a processor, hardware, firmware, hard wiring, or any combination of these. Features that implement the functions may also be physically located at various locations, including being distributed so that parts of the functions are implemented at different physical locations.

[0193] Computer readable medium includes both non-transitory computer storage medium and communication medium, and communication medium includes any medium that promotes the transmission of computer program from one place to another place.Non-transitory storage medium can be any available medium that can be accessed by general-purpose computer or special-purpose computer.By way of example and not limitation, non-transitory computer readable medium can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, disk storage or other magnetic storage device, or can be used for carrying or storing desired program code unit and any other non-transitory medium that can be accessed by general-purpose or special-purpose computer or general-purpose or special-purpose processor in the form of instruction or data structure.In addition, any connection is appropriately referred to as computer readable medium.For example, if software is to send from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of computer readable medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0194] As used herein (including in the claims), "or" as used in a list of items (e.g., a list of items ending with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an example step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0195] In the accompanying drawings, similar components or features may have the same reference numeral. In addition, various components of the same type may be distinguished by following the reference numeral with a dash and a second reference numeral, the second reference numeral being used to distinguish between similar components. If only the first reference numeral is used in the specification, the description applies to any of the similar components having the same first reference numeral, without regard to the second reference numeral or other subsequent reference numerals.

[0196] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations, and do not represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples." For the purpose of providing an understanding of the described techniques, the detailed description includes specific details. However, these techniques may be implemented without these specific details. In some cases, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0197] To enable those skilled in the art to implement or use the present disclosure, the description herein is provided. It will be apparent to those skilled in the art that various modifications to the present disclosure will be apparent, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: Determining to perform a random access process with a base station; receiving a plurality of synchronization signal blocks in a synchronization signal block set, wherein each random access opportunity in the random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; determining, for each synchronization signal block of the plurality of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection, wherein the one or more additional parameters include a congestion parameter for the synchronization signal block; determining a value of the congestion parameter based at least in part on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof; selecting a random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the congestion parameter for the synchronization signal block; and A first message of the random access procedure is sent to the base station in the random access opportunity selected from the set of random access opportunities based at least in part on the received power and the values ​​of the one or more additional parameters.

2. The method according to claim 1, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: Determine that the received power reduced by the value of the congestion parameter for the synchronization signal block is greater than each other received power reduced by a corresponding value of the congestion parameter for each other synchronization signal block in the plurality of synchronization signal blocks.

3. The method according to claim 1, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: identifying, for each synchronization signal block in the plurality of synchronization signal blocks, a selection probability value based at least in part on the received power and a value of the congestion parameter; and The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the selection probability value corresponding to the synchronization signal block.

4. The method according to claim 1, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: identifying that a value of the congestion parameter associated with at least one of the plurality of synchronization signal blocks has exceeded a threshold value associated with a backoff indication, a number of contention resolution failures, or a combination thereof; and The at least one synchronization signal block is excluded from selection by the UE based at least in part on the identifying.

5. The method according to claim 1, wherein: The one or more additional parameters include a timing parameter, the method further comprising: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of the timing parameter associated with the random access opportunity corresponding to the synchronization signal block.

6. The method according to claim 5, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: At least one random access opportunity in the set of random access opportunities is excluded based at least in part on determining that the at least one random access opportunity exceeds a delay threshold for the timing parameter.

7. The method according to claim 5, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: Determining two or more synchronization signal blocks of the plurality of synchronization signal blocks that are associated with a received power that satisfies a received power threshold; identifying two or more random access opportunities corresponding to the two or more synchronization signal blocks; and The random access opportunity is selected from the two or more random access opportunities based at least in part on the random access opportunity that is closest in time, the value of the timing parameter corresponding to the random access opportunity that is closest in time.

8. The method according to claim 1, wherein: The one or more additional parameters include a beam correspondence parameter, and the method further includes: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of the beam correspondence parameter associated with the random access opportunity corresponding to the synchronization signal block.

9. The method according to claim 8, further comprising: The at least one synchronization signal block is excluded from selection by the UE based at least in part on identifying that the UE previously failed to receive a random access response from the base station using a beam pair link associated with at least one synchronization signal block of the plurality of synchronization signal blocks.

10. The method according to claim 8, wherein: Selecting the random access opportunity corresponding to the synchronization signal block includes: Determine that the value of the beam correspondence parameter for the synchronization signal block corresponding to the random access opportunity exceeds every other value of the beam correspondence parameter for each other synchronization signal block in the plurality of synchronization signal blocks.

11. The method according to claim 1, wherein: The one or more additional parameters include a beam pair link history parameter for the synchronization signal block, the method further comprising: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of a beam pair link history parameter associated with a synchronization signal block in the plurality of synchronization signal blocks.

12. The method according to claim 11, wherein: The beam pair link history parameter indicates that the synchronization signal block is associated with a beam pair link previously established between the UE and the base station.

13. The method according to claim 11, wherein: The beam pair link history parameter indicates that the synchronization signal block is associated with a beam pair link that has failed less than a threshold number of times.

14. The method according to claim 1, wherein: The one or more additional parameters include a congestion parameter, a delay parameter, a beam correspondence parameter, a beam pair link history parameter, or a combination thereof.

15. The method according to claim 1, wherein: The first message of the random access procedure includes message 1 of a four-step random access procedure or message A of a two-step random access procedure, and the method further includes: Message 2 of the four-step random access procedure or message B of the two-step random access procedure is monitored on a receive beam based at least in part on the random access opportunity selected for sending the first message of the random access procedure.

16. An apparatus for wireless communication at a user equipment (UE), comprising: processor, a memory coupled to the processor; as well as Instructions, which are stored in the memory and can be executed by the processor to cause the device to perform the following operations: Determining to perform a random access process with a base station; receiving a plurality of synchronization signal blocks in a synchronization signal block set, wherein each random access opportunity in the random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; determining, for each synchronization signal block of the plurality of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection, wherein the one or more additional parameters include a congestion parameter for the synchronization signal block; determining a value of the congestion parameter based at least in part on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof; selecting a random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the congestion parameter for the synchronization signal block; and A first message of the random access procedure is sent to the base station in the random access opportunity selected from the set of random access opportunities based at least in part on the received power and the values ​​of the one or more additional parameters.

17. The device according to claim 16, wherein: The one or more additional parameters include a timing parameter, and the instructions are further executable by the processor to cause the apparatus to: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of the timing parameter associated with the random access opportunity corresponding to the synchronization signal block.

18. The device according to claim 16, wherein: The one or more additional parameters include beam correspondence parameters, and the instructions may also be executed by the processor to cause the apparatus to perform the following operations: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of the beam correspondence parameter associated with the random access opportunity corresponding to the synchronization signal block.

19. The device according to claim 16, wherein: The one or more additional parameters include a beam pair link history parameter for the synchronization signal block, and the instructions are further executable by the processor to cause the apparatus to perform the following operations: The random access opportunity corresponding to the synchronization signal block is selected based at least in part on the received power and a value of a beam pair link history parameter associated with a synchronization signal block in the plurality of synchronization signal blocks.

20. The device according to claim 16, wherein: The one or more additional parameters include a congestion parameter, a delay parameter, a beam correspondence parameter, a beam pair link history parameter, or a combination thereof.

21. The device according to claim 16, wherein: The first message of the random access procedure includes message 1 of a four-step random access procedure or message A of a two-step random access procedure, and the instructions can also be executed by the processor to cause the apparatus to perform the following operations: Message 2 of the four-step random access procedure or message B of the two-step random access procedure is monitored on a receive beam based at least in part on the random access opportunity selected for sending the first message of the random access procedure.

22. An apparatus for wireless communication at a user equipment (UE), comprising: A unit for determining to perform a random access procedure with a base station; means for receiving a plurality of synchronization signal blocks in a set of synchronization signal blocks, wherein each random access opportunity in the set of random access opportunities corresponds to at least one synchronization signal block in the set of synchronization signal blocks; means for determining, for each synchronization signal block of the plurality of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection, wherein the one or more additional parameters include a congestion parameter for the synchronization signal block; means for determining a value of the congestion parameter based at least in part on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof; means for selecting a random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the congestion parameter for the synchronization signal block; and means for sending a first message of the random access procedure to the base station in the random access opportunity selected from the set of random access opportunities based at least in part on the received power and the values ​​of the one or more additional parameters.

23. The device according to claim 22, wherein: The one or more additional parameters include a timing parameter, the apparatus further comprising: Means for selecting the random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the timing parameter associated with the random access opportunity corresponding to the synchronization signal block.

24. The device according to claim 22, wherein: The one or more additional parameters include a beam correspondence parameter, and the apparatus further includes: means for selecting the random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the beam correspondence parameter associated with the random access opportunity corresponding to the synchronization signal block.

25. The device according to claim 22, wherein: The one or more additional parameters include a beam pair link history parameter for the synchronization signal block, the apparatus further comprising: Means for selecting the random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the congestion parameter associated with a synchronization signal block in the plurality of synchronization signal blocks.

26. A non-transitory computer readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to: Determining to perform a random access process with a base station; Receive multiple synchronization signal blocks in a synchronization signal block set, wherein: Each random access opportunity in the random access opportunity set corresponds to at least one synchronization signal block in the synchronization signal block set; determining, for each synchronization signal block of the plurality of synchronization signal blocks, a received power and values ​​of one or more additional parameters for random access opportunity selection, wherein the one or more additional parameters include a congestion parameter for the synchronization signal block; determining a value of the congestion parameter based at least in part on a backoff indication, a number of contention resolution failures, a number of medium access control subheaders, or a combination thereof; selecting a random access opportunity corresponding to the synchronization signal block based at least in part on the received power and a value of the congestion parameter for the synchronization signal block; and A first message of the random access procedure is sent to the base station in the random access opportunity selected from the set of random access opportunities based at least in part on the received power and the values ​​of the one or more additional parameters.

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