Random Access Channel (RACH) Opportunity Allocation

Abstract

Certain aspects of the present disclosure provide techniques for random access channel (RACH) opportunity allocation. A method performed by a user equipment (UE) includes: receiving multiple synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. The method also includes: sending a random access preamble on a first RACH opportunity associated with a first SSB among the multiple SSBs, wherein the first RACH opportunity is one of multiple RACH opportunities associated with the multiple SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the multiple RACH opportunities, and a second SSB among the multiple SSBs is associated with a second number of RACH opportunities among the multiple RACH opportunities, wherein the first number is different from the second number.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 17 / 150,676, filed on January 15, 2021, which claims priority to U.S. Provisional Patent Application No. 62 / 968,535, filed on January 31, 2020. The contents of the above applications are hereby incorporated herein by reference in their entirety. Technical Field

[0003] Aspects of the present disclosure relate to wireless communications and, more particularly, to techniques for random access channel (RACH) opportunity (RO) allocation. Background Art

[0004] Wireless communication systems are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcast, etc. These wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, Advanced LTE (LTE-A) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, among others.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at municipal, national, regional and even global levels. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR aims to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology and carrier aggregation.

[0006] However, as the demand for mobile broadband access continues to increase, further improvements are needed in NR and LTE technologies. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that adopt these technologies. Summary of the invention

[0007] The systems, methods, and devices of the present disclosure each have several aspects, no one of which is solely responsible for its desired attributes. Without limiting the scope of the present disclosure as expressed in the appended claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description of the Invention," one will understand how the features of the present disclosure provide advantages including improved communication between a base station and a user device.

[0008] Certain aspects of the subject matter described in the present disclosure may be implemented in a method for wireless communication by a user equipment (UE). The method generally includes: receiving a plurality of synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. The method also includes: sending a random access preamble on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0009] Certain aspects of the subject matter described in the present disclosure may be implemented in a method for wireless communications by a base station (BS). The method generally includes: transmitting a plurality of synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of the BS. The method also includes: receiving a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0010] Certain aspects of the subject matter of the present disclosure may be implemented in a user equipment (UE). The UE generally includes a memory and a processor. The memory and the processor are configured to: receive a plurality of synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. The memory and the processor are further configured to: send a random access preamble on a first random access channel (RACH) opportunity associated with a first SSB among a plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with a plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0011] Certain aspects of the subject matter described in the present disclosure may be implemented in a base station (BS). The BS generally includes a memory and a processor. The memory and the processor are configured to: send multiple synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of the BS. The memory and the processor are also configured to: receive a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among a plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with a plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0012] Certain aspects of the subject matter described in the present disclosure may be implemented in a user equipment (UE). The UE generally includes a unit for receiving a plurality of synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. The UE also includes a unit for sending a random access preamble on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0013] Certain aspects of the subject matter described in the present disclosure may be implemented in a base station (BS). The BS includes a unit for transmitting a plurality of synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of the BS. The BS also includes a unit for receiving a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number.

[0014] Certain aspects of the subject matter described in the present disclosure may be implemented in a non-transitory computer-readable medium including instructions that, when executed by a user equipment (UE), cause the UE to perform a method for conducting wireless communications. The method generally includes: receiving a plurality of synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. The method also includes: sending a random access preamble on a first random access channel (RACH) opportunity associated with a first SSB of a plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities of the plurality of RACH opportunities, and a second SSB of the plurality of SSBs is associated with a second number of RACH opportunities of the plurality of RACH opportunities, wherein the first number is different from the second number.

[0015] Certain aspects of the subject matter described in the present disclosure may be implemented in a non-transitory computer-readable medium comprising instructions that, when executed by a base station (BS), cause the BS to perform a method for conducting wireless communications. The method generally includes: sending a plurality of synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of the BS. The method also includes: receiving a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB of a plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities of the plurality of RACH opportunities, and a second SSB of the plurality of SSBs is associated with a second number of RACH opportunities of the plurality of RACH opportunities, wherein the first number is different from the second number.

[0016] Aspects of the present disclosure provide units, devices, processors and computer-readable media for executing the methods described herein.

[0017] Aspects of the present disclosure provide units, apparatuses, processors, and computer-readable media for techniques and methods performed, for example, by a BS that are complementary to the operations of a UE described herein.

[0018] To achieve the foregoing and related ends, one or more aspects include features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features represent only a few of the many ways in which the principles of the various aspects may be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order that the manner in which the above-mentioned features of the present disclosure are understood in detail, a more specific description briefly summarized above may be obtained by reference to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the description may admit to other equally effective aspects.

[0020] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0021] Figure 2 is a block diagram conceptually illustrating designs of exemplary base stations (BSs) and user equipment (UEs) in accordance with certain aspects of the present disclosure.

[0022] Figure 3 is an example frame format for New Radio (NR) in accordance with certain aspects of the present disclosure.

[0023] Figure 4 is a timing (or "call flow") diagram illustrating an example four-step RACH procedure in accordance with certain aspects of the present disclosure.

[0024] Figure 5 is a timing diagram illustrating an example two-step RACH procedure in accordance with certain aspects of the present disclosure.

[0025] Figure 6 Exemplary beamformed transmission by a BS and beamformed reception by a UE are illustrated in accordance with certain aspects of the present disclosure.

[0026] Fig. 7A An example of SSB according to certain aspects is shown.

[0027] Figure 7B An example of transmission timing for SSB according to certain aspects is shown.

[0028] Figure 8 The traditional uniform SSB to RO allocation is shown.

[0029] Fig. 9 An exemplary high-speed train scenario is shown in which techniques for RO allocation in accordance with aspects described herein may be used.

[0030] Fig. 10A An example non-uniform RO allocation according to certain aspects herein is shown.

[0031] Fig. 10B Exemplary uniform RO allocations and non-uniform RO allocations according to certain aspects herein are shown.

[0032] Fig.11 is a flow chart illustrating example operations of wireless communications by a UE in accordance with certain aspects of the present disclosure.

[0033] Fig.12 is a flow chart illustrating example operations for wireless communications by a BS in accordance with certain aspects of the present disclosure.

[0034] Fig.13 A communication device according to aspects of the present disclosure is shown that may include various components configured to perform operations of the techniques disclosed herein.

[0035] Fig.14 A communication device according to aspects of the present disclosure is shown that may include various components configured to perform operations of the techniques disclosed herein.

[0036] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. DETAILED DESCRIPTION

[0037] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for RACH opportunity (RO) allocation.

[0038] In certain aspects, one or more base stations (BSs) may be configured to transmit synchronization signal blocks (SSBs) in multiple different transmit beams, such as in a time division multiplexed manner. Such transmissions may include a "synchronization signal (SS) burst set."

[0039] The UE is configured to monitor the SSBs, for example by measuring the SSBs to determine a downlink channel quality (e.g., in some aspects, a corresponding uplink channel quality) (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), or signal to interference plus noise ratio (SINR)) between the UE and the BS for each of a plurality of different transmit beams. Each SSB may be associated with a different SSB index.

[0040] The UE may be configured to perform a RACH procedure with the BS, whereby the UE (randomly) accesses the network via the BS to communicate on the RACH (so named because it refers to a wireless channel (medium) that may be shared by multiple UEs and used by the UE to (randomly) access the network for communication). As part of the RACH procedure, the UE sends a RACH preamble identifying the UE in the RO to the BS. The RO is a designated time / frequency resource that the UE may use as part of the RACH procedure.

[0041] In some aspects, the SSBs and ROs are associated. For example, each SSB may be associated with one or more ROs of a different set. Thus, the UE may send a RACH preamble in a RO associated with an SSB for which the UE has measured sufficient (e.g., highest, above a threshold, etc.) channel quality. By sending the preamble in a RO associated with an SSB, the UE may implicitly convey to the BS which SSB it measures to have sufficient quality, and therefore implicitly convey to the BS which transmit beam (i.e., the beam used to send the SSB) should be used by the BS to communicate with the UE. Thus, the UE and the BS may perform beam establishment.

[0042] In some aspects, the association of SSBs (e.g., SSB indexes) with ROs is based on a mapping rule. In some aspects, the mapping rule is pre-configured at the BS and the UE. In some aspects, the BS configures the UE with the mapping rule (e.g., in system information such as a system information block (SIB), a master information block (MIB), using other signaling, etc.). The mapping rule can be a frequency-first mapping rule, and typically each SSB can be mapped to the same number of ROs, so that each SSB has the same number of associated ROs.

[0043] Certain aspects of the present invention provide enhanced RO allocation, in which the association of ROs with SSBs is uneven or irregular, so that different SSBs can be mapped to different numbers of ROs, and thus different SSBs can have different numbers of associated ROs. This may be useful in certain scenarios, such as high-speed train (HST) scenarios, where certain SSBs are more likely / frequently used by UEs than other SSBs. In particular, by providing more ROs to SSBs that are more likely to be used, there is a lower probability that multiple different UEs attempting to perform RACH using the RO associated with the SSB will fill up the RO associated with the SSB. This results in improved use of communication resources in the network, thereby increasing communication efficiency.

[0044] The following description provides an example of RACH opportunity (RO) allocation in a communication system, and does not limit the scope, applicability or examples set forth in the claims. Without departing from the scope of the present disclosure, the functions and arrangements of the discussed elements may be changed. Various examples may omit, replace or add various programs or components when appropriate. For example, the described method may be performed in an order different from that described, and various steps may be added, omitted or combined. In addition, the features described with respect to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such a device or method that uses other structures, functions or structures and functions in addition to or different from the various aspects of the present disclosure set forth herein to practice. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the claims. The word "exemplary" is used herein to mean "as an example, instance or illustration". Any aspect described herein as "exemplary" is not necessarily to be interpreted as being preferred or advantageous over other aspects.

[0045] Generally, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a specific radio access technology (RAT) and can operate on one or more frequencies. RAT can also be referred to as a radio technology, air interface, etc. Frequency can also be referred to as a carrier, subcarrier, channel, tone, subband, etc. Each frequency can support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs.

[0046] The techniques described herein can be used for various wireless networks and wireless technologies. Although terms commonly associated with 3G, 4G and / or new radio (e.g., 5G NR) wireless technologies are used herein to describe various aspects, various aspects of the present disclosure can be applied to other communication systems based on generations.

[0047] NR access can support various wireless communication services, such as enhanced mobile broadband (eMBB) for wide bandwidth (e.g., 80MHz or higher), millimeter wave (mmW) for high carrier frequencies (e.g., 25GHz or higher), massive machine type communication MTC (mMTC) for non-backward compatible MTC technologies, and / or mission critical ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. In addition, these services can coexist in the same subframe. NR supports beamforming and can dynamically configure beam directions. MIMO transmission with precoding can also be supported. MIMO configuration in DL can support up to 8 transmit antennas, multi-layer DL transmission up to 8 streams, and up to 2 streams per UE. Multi-layer transmission of up to 2 streams per UE can be supported. Aggregation of multiple cells up to 8 serving cells can be supported.

[0048] Figure 1 An exemplary wireless communication network 100 is shown in which various aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a NR system (e.g., a 5G NR network). Figure 1 As shown, the wireless communication network 100 may communicate with a core network 132. The core network 132 may communicate with one or more base stations (BSs) 110 and / or user equipments (UEs) 120 in the wireless communication network 100 via one or more interfaces.

[0049] like Figure 1 As shown, the wireless communication network 100 may include multiple BSs 110a-z (each BS is also individually referred to as BS 110 or collectively referred to as BS 110 in this document) and other network entities. BS 110 can provide communication coverage for a specific geographic area (sometimes referred to as a "cell"), which can be stationary or can move according to the location of the mobile BS 110. In some examples, BS 110 can be interconnected with each other and / or interconnected to one or more other BSs or network nodes (not shown) in the wireless communication network 100 through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transmission network. Figure 1 In the example shown, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells. A network controller 130 may be coupled to a set of BSs 110 and provide coordination and control of these BSs 110 (e.g., via a backhaul).

[0050] BS 110 communicates with UEs 120a-y (each UE is also individually referred to herein as UE 120 or collectively referred to as UE 120) in the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be fixed or mobile. The wireless communication network 100 may also include a relay station (e.g., relay station 110r), also referred to as a relay, etc., which receives transmissions of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and sends transmissions of data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays transmissions between UEs 120 to facilitate communication between devices.

[0051] According to certain aspects, BS 110 and UE 120 may be configured for RO allocation. Figure 1 As shown, BS 110a includes a RACH manager 112. According to aspects of the present disclosure, RACH manager 112 may be configured to perform RACH. Figure 1 As shown, UE 120a includes a RACH manager 122. According to aspects of the present disclosure, RACH manager 122 may be configured to perform RACH.

[0052] Figure 2 BS 110a and UE 120a (eg, Figure 1 00) which may be used to implement various aspects of the present disclosure.

[0053] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. The data may be for a physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel, such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

[0054] The processor 220 may process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a channel state information reference signal (CSI-RS). If applicable, the transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols, and may provide an output symbol stream to a modulator (MOD) 232a-232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may also process (e.g., convert to analog, amplify, filter, and up-convert) an output sample stream to obtain a downlink signal. The downlink signals from modulators 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0055] At UE 120a, antennas 252a-252r may receive downlink signals from BS 110a and may provide received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may also process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all demodulators 254a-254r, perform MIMO detection on the received symbols when applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to a data sink 260, and provide decoding control information to a controller / processor 280.

[0056] On the uplink, at the UE 120a, a transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for reference signals (e.g., a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by a demodulator in a transceiver 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signal from the UE 120a may be received by the antenna 234, processed by the modulator 232, detected by the MIMO detector 236, if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120a. The receive processor 238 may provide decoded data to a data sink 239 and decoded control information to a controller / processor 240 .

[0057] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0058] The antennas 252, processors 266, 258, 264, and / or controller / processor 280 at the UE 120a and / or the antennas 234, processors 220, 230, 238, and / or controller / processor 240 at the BS 110a may be used to perform the various techniques and methods described herein. Figure 2 As shown, the controller / processor 240 of the BS 110a has a RACH manager 241 that can be configured to perform RACH according to various aspects described herein. Figure 2 As shown, the controller / processor 280 of the UE 120a has a RACH manager 281 that may be configured to perform RACH in accordance with aspects described herein. Although shown at the controller / processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

[0059] NR can use orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) on uplink and downlink. NR can support half-duplex operation using time division duplex (TDD). OFDM and single carrier frequency division multiplexing (SC-FDM) divide the system bandwidth into multiple orthogonal subcarriers, which are also commonly called tones, segments, etc. Each subcarrier can be modulated with data. Modulation symbols can be sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers can depend on the system bandwidth. The minimum resource allocation called a resource block (RB) can be 12 consecutive subcarriers. The system bandwidth can also be divided into subbands. For example, a subband can cover multiple RBs. NR can support a basic subcarrier spacing (SCS) of 15KHz, and other SCSs can be defined relative to the basic SCS (e.g., 30kHz, 60kHz, 120kHz, 240kHz, etc.).

[0060] Figure 3 300 is a diagram showing an example of a frame format for NR. The transmission timeline of each of the downlink and uplink may be divided into radio frame units. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be divided into 10 subframes, each of which is 1 ms and indexed from 0 to 9. Each subframe may include a variable number of slots (e.g., 1, 2, 4, 8, 16, ... slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols), depending on the SCS. The symbol periods in each slot may be assigned an index. A small slot, which may be referred to as a subslot structure, refers to a transmission time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols). Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission, and the link direction of each subframe may be dynamically switched. The link direction may be based on the slot format. Each slot may include DL / UL data and DL / UL control information.

[0061] Exemplary RACH Power Control Procedure

[0062] The Random Access Channel (RACH) is so named because it refers to a radio channel (medium) that can be shared by multiple UEs and used by UEs to (randomly) access the network for communication. For example, RACH can be used for call establishment and access to the network for data transmission. In some cases, RACH can be used for initial access to the network when the UE switches from Radio Resource Control (RRC) connected idle mode to active mode, or when switching in RRC connected mode. In addition, RACH can be used for downlink (DL) and / or uplink (UL) data arrival when the UE is in RRC idle or RRC inactive mode and when reestablishing a connection with the network.

[0063] Figure 4 4 is a timing (or "call flow") diagram 400 illustrating an exemplary four-step RACH procedure in accordance with certain aspects of the present disclosure. A first message (MSG1) may be sent from UE 120 to BS 110 on a physical random access channel (PRACH). In this case, MSG1 may include only a RACH preamble. BS 110 may respond with a random access response (RAR) message (MSG2), which may include an identifier (ID) of the RACH preamble, a time advance (TA), an uplink grant, a cell radio network temporary identifier (C-RNTI), and a backoff indicator (BI). As shown, MSG2 may include a PDCCH communication including control information for subsequent communications on the PDSCH. In response to MSG2, MSG3 is sent from UE 120 to BS 110 on the PUSCH. MSG3 may include one or more of an RRC connection request, a tracking area update request, a system information request, a positioning fix or positioning signal request, or a scheduling request. BS 110 then responds with MSG 4 which may include a contention resolution message.

[0064] In some cases, to speed up access, a two-step RACH procedure may be supported. As the name implies, the two-step RACH procedure effectively "folds" the four messages of the four-step RACH procedure into two messages.

[0065] Figure 55 is a timing diagram 500 illustrating an exemplary two-step RACH process according to certain aspects of the present disclosure. A first enhancement message (MSGA) may be sent from UE 120 to BS 110. In certain aspects, MSGA includes some or all of the information from MSG1 and MSG3 from the four-step RACH process, effectively combining MSG1 and MSG3. For example, MSGA may include MSG1 and MSG3 multiplexed together, such as using one of time division multiplexing or frequency division multiplexing. In certain aspects, MSGA includes a RACH preamble and a payload for random access. For example, the MSGA payload may include a UE-ID and other signaling information (e.g., a buffer status report (BSR)) or a scheduling request (SR). BS 110 may respond with a random access response (RAR) message (MSGB) that effectively combines the above-mentioned MSG2 and MSG4. For example, MSGB may include an ID of the RACH preamble, a time advance (TA), a backoff indicator, a contention resolution message, an UL / DL grant, and a transmit power control (TPC) command.

[0066] Aspects herein may be applicable to any suitable RACH procedure, such as the discussed four-step and two-step RACH procedures.

[0067] SS Burst Set Configuration Example

[0068] Figure 6 It is shown that the BS (e.g. Figure 1 110a and the second BS 110b) and an exemplary beamforming transmission by a UE (e.g., Figure 11. Beamforming reception performed by UE 120a of the present invention. As shown, each of the first BS 110a and the second BS 110b transmits on multiple transmit beams 605a and 605b, respectively. In addition, UE 120a receives on multiple receive beams 609. In some aspects, receive beam 609 is a pseudo-omnidirectional (PO) beam (e.g., covering a 90-degree angle in three-dimensional space). For example, each of the first BS 110a and the second BS 110b can transmit an SS burst set, wherein each SSB of the SS burst set is transmitted on a corresponding transmit beam during a scheduled time period. For example, the first BS 110a and the second BS 110b can each transmit 64 SSBs in different beams during the SS burst set scheduling time period. Therefore, UE 120a can use the scheduling time period as a search opportunity, and according to various aspects disclosed herein, use one of its receive beams 609 to receive synchronization signals sent during the scheduling time period according to prioritized scheduling. Based on the received synchronization signals, for example, at multiple search opportunities, UE 120a can determine to communicate with BS 110 that sends a particular synchronization signal (e.g., meeting the discussed criteria) in a cell where the synchronization signal is sent using a transmit-receive beam pair on which the synchronization signal is sent by BS 110 and received by UE 120a.

[0069] As discussed, in order for UE 120a to communicate in a wireless communication network (e.g., wireless communication network 100), it communicates with BS 110. In addition, as discussed, UE 120a can determine which BS 110 to communicate with based on the synchronization signal received from the BS. Therefore, BS 110 can send a synchronization signal block (SSB) (e.g., including one or more synchronization signals, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) and a PBCH). In some aspects, BS 110 can support beamforming to spatially beamform the signal and send the signal as different transmit beams in different spatial directions. Therefore, BS 110 may need to perform beam scanning and send SSBs on each beam in order to cover the cell of BS 110.

[0070] Fig. 7A An example of an SSB 700 is shown in accordance with certain aspects. Fig. 7AThe X-axis in the diagram of represents time (e.g., symbol), and the Y-axis represents frequency (e.g., tone). As shown, SSB 700 includes PSS 702, SSS 704, PBCH 706, and PBCH 707 multiplexed in the time domain and allocated to a specific frequency range. In some aspects, PSS 702 and SSS 704 are allocated to the same frequency range. In addition, in some aspects, PBCH 706 and PBCH 707 are allocated to the same frequency range. In some aspects, PSS 702 and SSS 704 are allocated to a portion (e.g., half) of the frequency range of PBCH 706 and PBCH 707. Although shown in a specific order and a specific duration and frequency allocation in SSB 700, it should be noted that the order, duration, and frequency allocation of PSS 702, SSS 704, PBCH 706, and PBCH 707 may be different. In addition, SSB 700 may include more or fewer reference signals or more or less PBCHs. Furthermore, in certain aspects, for each of PBCH 706 and PBCH 707, certain portions (e.g., frequency ranges, tones, resource elements (REs)) are allocated for transmission of reference sequences, such as in demodulation reference signals (DMRS) 710. In certain aspects, the allocation may be similar to Fig. 7A Different than shown.

[0071] In certain aspects, multiple SSBs may be allocated to a resource set to transmit multiple SSBs (such a resource set for transmitting multiple SSBs may be referred to herein as an SS burst set). Multiple SSBs may be allocated to periodic resources (e.g., every 20 ms) and transmitted by a BS in a cell (e.g., Figure 1 110) periodically transmits. For example, an SS burst set may include L SSBs (e.g., 4, 8, or 64). In some aspects, the number L of SSBs included in the SS burst set is based on the frequency band used for transmission. For example, for frequency transmissions below 6 GHz, L may be equal to 4 or 8 (e.g., 0-3 GHz L=4, 3-6 GHz L=8). In another example, for transmissions above 6 GHz, L may be equal to 64. For example, the transmissions of BS 110 in a cell may be beamformed so that each transmission covers only a portion of the cell. Therefore, different SSBs in an SS burst set may be sent in different directions on different transmit beams in order to cover the cell. The number L of SSBs in an SS burst set may represent the maximum allowed number of SSBs that may be transmitted within the SS burst set. In other words, BS 110 has flexibility in which SSBs are actually sent. For example, a BS 110 operating in a frequency band above 6 GHz may have the opportunity to transmit up to 64 SSBs in an SS burst set, but BS 110 may transmit less than the allotted possible 64 SSBs.

[0072] Figure 7B 1 shows an example of transmission timing of SSBs according to certain aspects. As shown, SS burst sets 725 can be periodically transmitted every X milliseconds (e.g., X=20). In addition, SS burst sets 725 can have a duration of Y milliseconds (e.g., Y<5), wherein all SSBs 730 in SS burst sets 725 are transmitted within duration Y. Figure 7B As shown, each SSB 730 includes a PSS, an SSS, and a PBCH. SSB 730 may correspond, for example, to SSB 700. SS burst set 725 includes up to L SSBs 730, each SSB having a corresponding SSB index (e.g., 0 to L-1) indicating its position within the SS burst set, for example, indicating the physical transmission order of SSB 730 in time. Although SSBs 730 are shown as being allocated contiguously in time in SS burst set 725, it should be noted that SSBs 730 may not be allocated contiguously. For example, there may be a separation in time (e.g., having the same or different durations) between SSBs 730 in SS burst set 725. The time allocation of SSBs 730 may correspond to a specific pattern, which may be specific to BS 110 and UEs (e.g., Figure 1 UE 120) is known.

[0073] Exemplary RO Allocation

[0074] As discussed, the allocation of SSBs to ROs typically allocates an equal number of ROs to each different SSB transmitted by the BS, such as each different SSB in an SS burst set. Figure 8 A conventional uniform SSB to RO allocation is shown. In particular, as shown in brackets, each RO is associated with an SSB (e.g., SSB 1, SSB 2, ..., SSB N). As shown, the allocation of SSBs to ROs is a frequency-first mapping, meaning that ROs are first allocated to SSBs in frequency and then in time. Specifically, as shown, ROs are allocated to SSB 1 across multiple frequencies in a first time period, and then ROs are allocated to SSB 2 across multiple frequencies in a second time period, and so on.

[0075] Certain aspects of the present disclosure provide for uneven or irregular allocation of SSBs to ROs, as discussed, such that different SSBs may be mapped to different numbers of ROs, such that different SSBs may have different numbers of associated ROs. This may be useful in certain scenarios, such as high speed train (HST) scenarios, where certain SSBs are more likely / frequently used by UEs than other SSBs. In particular, by providing more ROs to SSBs that are more likely to be used, there is less chance that multiple different UEs attempting to perform RACH using the RO associated with the SSB will fill up the RO associated with the SSB.

[0076] Fig. 9 An exemplary high-speed train scenario is shown in which techniques for RO allocation according to various aspects described herein may be used. As shown, a train 902 may pass from the coverage area or tracking area of ​​a first BS (BS1) to the coverage area or tracking area of ​​a second BS (BS2). There may be a large number of UEs (e.g., hundreds) in idle / inactive mode (e.g., in a radio resource control (RRC) idle state or an RRC inactive state) on the train 902. Based on the train 902 passing from the tracking area of ​​BS1 to the tracking area of ​​BS2, the UEs in the train 902 may each start a RACH process in order to update the tracking area of ​​the UE / perform a notification area (RNA) update based on the radio access network. As shown, such UEs align with the SSB N of BS1 and the SSB 1 of BS 2 when passing between the tracking areas. Therefore, a large number of UEs may attempt to use the RO associated with the SSB N of BS 1 and / or the SSB 1 of BS 2 for performing RACH, which may overload the RO, meaning that there are not enough resources for the UE to perform RACH, or there may be conflicts when using the RO. The techniques herein may help alleviate such issues by allocating more ROs to SSB N of BS 1 and / or SSB 1 of BS 2 compared to other SSBs of BS 1 and / or BS 2 to ensure that more ROs associated with SSBs that UEs more frequently use for RACH are available to perform RACH.

[0077] In some aspects, the association of SSBs with ROs can be weighted for a given BS 110. For example, in some aspects, a weighting parameter can be assigned to each SSB of the BS 110, where the weighting parameter can vary between different SSBs. It should be noted that the same weighting parameter can be assigned to multiple SSBs. In some aspects, the higher the weight of the weighting parameter assigned to the SSB, the higher the number of ROs associated with the SSB.

[0078] For example, there may be a set of ROs that can be assigned to the SSBs of BS 110. For simplicity and illustration only, assume that BS 110 has 4 SSBs and a total of 20 ROs. The weighting parameters for the 4 SSBs (SSB1, SSB2, SSB3, and SSB4) may be, for example, 2, 4, 3, and 1, respectively. Thus, the least number of ROs may be assigned to SSB4, followed by SSB1, SSB3, and then SSB2. In one example, the weighting parameters may be used as a simple averaging function, where the number of ROs for a given SSB is the weighting parameter for that SSB divided by the sum of all weighting parameters and then multiplied by the total number of ROs. In such an example, the number of ROs assigned to SSB1, SSB2, SSB3, and SSB4 may be 4, 8, 6, and 2, respectively. It should be noted that other functions for using weighting parameters to assign ROs to SSBs may also be used.

[0079] In some aspects, different weighting parameters may be applied to SSBs of different BSs, such as BSs with different deployment scenarios (e.g., HST). For example, the weighting parameters applied to the SSBs of the BS may be based on one or more of the deployment scenario of the BS, the purpose of the random access procedure (e.g., tracking area / RNA update), etc. In some aspects, an SSB (SSB index) may generally be associated with different sets of corresponding weight parameters, each set corresponding to a different deployment scenario or other factors. Based on the deployment scenario of the BS or other factors, the set to be used is determined, for example, by the BS or the UE.

[0080] In certain aspects, BS 110 provides information indicative of the weighting parameters to UE 120. In certain aspects, BS 110 provides the information via system information (eg, broadcast), such as in one or more system information blocks or master information blocks.

[0081] In some aspects, UE 120 may autonomously determine the weighting parameters. For example, UE 120 may be configured with a rule, such as a predetermined rule, for selecting weighting parameters for SSBs of BS 110. In some aspects, the BS configures UE 120 with the rule, such as via radio resource control (RRC) signaling when the UE is in connected mode. In some aspects, the rule is configured at manufacturing time. In some aspects, the rule may be updated, such as using an over-the-air update. In some aspects, the rule may be one or more of the weighting parameters selected based on an identified deployment scenario, based on a total number of indexes of the SSBs, based on an index of the SSBs, and the like.

[0082] In some aspects, the actual allocation of ROs to SSBs can be done in a frequency-first mapping manner as described. In some aspects, higher weighted SSBs can be mapped first, meaning that the SSBs are mapped to the ROs in order of weight. In some aspects, the SSBs are mapped to the ROs in order of index.

[0083] For example, Fig. 10A An example non-uniform RO allocation according to certain aspects herein is shown.

[0084] In some aspects, all UEs in the coverage area or tracking area of ​​the BS use the same RO pool. For example, all UEs in the cell of the BS 110 associate the same multiple ROs with the same multiple SSBs.

[0085] In some aspects, different sets of UEs may use different RO to SSB mappings. For example, UEs referred to as legacy UEs that do not support non-uniform RO allocation as discussed herein may continue to use the traditional uniform RO allocation discussed herein. In some such aspects, a first plurality of ROs may be used for traditional uniform RO allocation as discussed herein, while a second plurality of ROs may be used for non-uniform RO allocation for a given BS 110 as discussed herein. For example, a first set of UEs (e.g., legacy UEs) may map the SSBs of the BS to a first plurality of ROs using conventional uniform RO allocation as discussed herein, while a second set of UEs (e.g., non-legacy UEs) may map the SSBs of the BS to a different second plurality of ROs using non-uniform RO allocation as discussed herein. In some aspects, the first plurality of ROs and the second plurality of ROs are adjacent in one or more of time or frequency. In some aspects, the first plurality of ROs and the second plurality of ROs are non-adjacent in both time and frequency.

[0086] In certain aspects, the second set of UEs is configured to map to both the first and second plurality of ROs, e.g., using conventional uniform RO allocations, while the first set of UEs is configured to map only to the first plurality of ROs, e.g., using conventional uniform RO allocations.

[0087] Fig. 10B An exemplary uniform RO allocation and a non-uniform RO allocation according to certain aspects of the present disclosure are shown. In particular, a first plurality of ROs are shown as conventional RACH resources, and a second plurality of ROs are shown as additional RACH resources. Although the first plurality and the second plurality of ROs are shown as being adjacent in frequency / time, they may be different than discussed. Fig. 10B In the illustrated example, in certain aspects, ROs of a first set are assigned to SSBs based on a uniform RO assignment, while SSBs potentially having higher weighting parameters are assigned additional ROs from a second plurality of ROs.

[0088] Fig.111 is a flow chart illustrating example operations 1100 for wireless communication according to certain aspects of the present disclosure. Operations 1100 may be performed, for example, by a UE (e.g., UE 120a in wireless communication network 100). Operations 1100 may be complementary operations to operations 1200 performed by a UE to a BS. Operations 1100 may be implemented as a process on one or more processors (e.g., Figure 2 In addition, the software components executed and run on the controller / processor 280 of the system can be transmitted through one or more antennas (e.g., Figure 2 The antenna 252 of the UE implements the UE to send and receive signals in operation 1100. In some aspects, the UE's transmission and / or reception of signals can be implemented via a bus interface of one or more processors (e.g., controller / processor 280) to obtain and / or output signals.

[0089] Operations 1100 may begin at 1105 by receiving a plurality of synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS. Operations 1100 may continue at 1110 by sending a random access preamble on a first random access channel (RACH) opportunity associated with a first SSB of the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of the plurality of RACH opportunities and a second SSB of the plurality of SSBs is associated with a second number of the plurality of RACH opportunities, wherein the first number is different than the second number.

[0090] In certain aspects of the operation 1100, each of the plurality of SSBs is associated with a corresponding weight parameter, wherein a number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

[0091] In certain aspects of the operations 1100, the relatively larger the weight parameter for a given SSB, the relatively larger the number of RACH opportunities in the plurality of RACH opportunities with which the given SSB is associated.

[0092] In certain aspects of operation 1100, each of the plurality of SSBs is associated with a corresponding set of weight parameters, each weight parameter in the corresponding set of weight parameters being associated with a different deployment scenario, wherein a number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on a corresponding weight parameter of the corresponding set of weight parameters associated with the deployment scenario of the BS.

[0093] In certain aspects of operation 1100, operation 1100 also includes receiving, from the BS, an indication of a corresponding weight parameter for each of the plurality of SSBs.

[0094] In certain aspects of operation 1100, the indication is received as part of system information broadcast by the BS.

[0095] In certain aspects of the operations 1100, the operations 1100 also include selecting, at the UE, a corresponding weight parameter for each of the plurality of SSBs.

[0096] In certain aspects of operation 1100, the selecting is performed based on rules configured at the UE.

[0097] In certain aspects of operation 1100, the selecting is performed based on one or more of an identified deployment scenario of the BS, a total number of the plurality of SSBs, or an index of the plurality of SSBs.

[0098] In certain aspects of operation 1100, all UEs in a cell of the BS associate multiple RACH opportunities with multiple SSBs.

[0099] In certain aspects of the operation 1100, a first set of UEs in a cell of the BS associates a plurality of RACH opportunities with a plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the first plurality of RACH opportunities.

[0100] In certain aspects of the operations 1100, the plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

[0101] In certain aspects of the operations 1100, the plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

[0102] In certain aspects of the operation 1100, the first set of UEs in the cell also associates a second plurality of RACH opportunities with the plurality of SSBs.

[0103] Fig.12 1 is a flow chart illustrating example operations 1200 for wireless communication according to certain aspects of the present disclosure. Operations 1200 may be performed, for example, by a BS (e.g., BS 110a in wireless communication network 100). Operations 1200 may be complementary operations to operations 1100 performed by the BS for a UE. Operations 1200 may be implemented as a process on one or more processors (e.g., Figure 2 In addition, the software components executed and run on the controller / processor 240 of the system can be transmitted through one or more antennas (e.g., Figure 2 The antenna 234 of the BS implements the BS to send and receive signals in operation 1200. The BS's transmission and / or reception of signals can be implemented via a bus interface of one or more processors (e.g., controller / processor 240) to obtain and / or output signals.

[0104] Operation 1200 may begin at 1205 by transmitting a plurality of synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of a BS. Operation 1200 may continue at 1210 by receiving a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB of the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities of the plurality of RACH opportunities, and a second SSB of the plurality of SSBs is associated with a second number of RACH opportunities of the plurality of RACH opportunities, wherein the first number is different from the second number.

[0105] In certain aspects of the operation 1200, each of the plurality of SSBs is associated with a corresponding weight parameter, wherein a number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

[0106] In certain aspects of the operations 1200, the relatively larger the weight parameter for a given SSB, the relatively larger the number of RACH opportunities in the plurality of RACH opportunities with which the given SSB is associated.

[0107] In certain aspects of operation 1200, each of the plurality of SSBs is associated with a corresponding set of weight parameters, each weight parameter in the corresponding set of weight parameters being associated with a different deployment scenario, wherein a number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on a corresponding weight parameter of the corresponding set of weight parameters associated with the deployment scenario of the BS.

[0108] In certain aspects of operation 1200, operation 1200 also includes sending an indication of a corresponding weight parameter for each of the plurality of SSBs to the UE.

[0109] In certain aspects of operation 1200, the indication is sent as part of system information broadcast by the BS.

[0110] In certain aspects of operation 1200, all UEs in a cell of the BS associate multiple RACH opportunities with multiple SSBs.

[0111] In certain aspects of the operation 1200, a first set of UEs in a cell of the BS associates a plurality of RACH opportunities with a plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the first plurality of RACH opportunities.

[0112] In certain aspects of the operations 1200, the plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

[0113] In certain aspects of the operations 1200, the plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

[0114] In certain aspects of the operation 1200, the first set of UEs in the cell also associates a second plurality of RACH opportunities with the plurality of SSBs.

[0115] Fig.13 A communication device 1300 is shown that may include various components (eg, corresponding to functional unit components) configured to perform operations of the techniques disclosed herein, such as Fig.11 . The communication device 1300 includes a processing system 1302 coupled to a transceiver 1308 (e.g., a transmitter and / or a receiver). The transceiver 1308 is configured to transmit and receive signals, such as the various signals described herein, for the communication device 1300 via an antenna 1310. The processing system 1302 may be configured to perform processing functions for the communication device 1300, including processing signals received and / or transmitted by the communication device 1300.

[0116] The processing system 1302 includes a processor 1304 coupled to a computer readable medium / memory 1312 via a bus 1306. In some aspects, the computer readable medium / memory 1312 is configured to store instructions (e.g., computer executable code) that, when executed by the processor 1304, cause the processor 1304 to perform Fig.11 1304. The processor 1304 may be configured to perform the operations shown, or other operations for performing the various techniques for RO allocation discussed herein. In some aspects, the computer-readable medium / memory 1312 stores code 1314 for receiving; code 1316 for sending, etc. In some aspects, the processor 1304 has circuits configured to implement the code stored in the computer-readable medium / memory 1312. The processor 1304 includes circuits 1318 for receiving; circuits 1320 for sending, etc.

[0117] Fig.14 A communication device 1400 is shown that may include various components (eg, corresponding to functional unit components) configured to perform operations of the techniques disclosed herein, such as Fig.12. The communication device 1400 includes a processing system 1402 coupled to a transceiver 1408 (e.g., a transmitter and / or a receiver). The transceiver 1408 is configured to transmit and receive signals, such as the various signals described herein, for the communication device 1400 via an antenna 1410. The processing system 1402 may be configured to perform processing functions for the communication device 1400, including processing signals received and / or transmitted by the communication device 1400.

[0118] The processing system 1402 includes a processor 1404 coupled to a computer readable medium / memory 1412 via a bus 1406. In some aspects, the computer readable medium / memory 1412 is configured to store instructions (e.g., computer executable code) that, when executed by the processor 1404, cause the processor 1404 to perform Fig.12 1404. The processor 1404 may be configured to perform the operations shown, or other operations for performing the various techniques for RO allocation discussed herein. In some aspects, the computer-readable medium / memory 1412 stores code 1414 for transmitting; code 1416 for receiving, etc. In some aspects, the processor 1404 has circuits configured to implement the code stored in the computer-readable medium / memory 1412. The processor 1404 includes circuits 1418 for transmitting; circuits 1420 for receiving, etc.

[0119] Exemplary Embodiments

[0120] Embodiment 1: A method for wireless communication by a user equipment (UE), the method comprising: receiving multiple synchronization signal blocks (SSBs) from a base station (BS), each SSB being associated with a different transmit beam of the BS; and sending a random access preamble code on a first random access channel (RACH) opportunity associated with a first SSB among the multiple SSBs, wherein the first RACH opportunity is one of multiple RACH opportunities associated with the multiple SSBs, wherein the first RACH opportunity is selected based on a measurement of the multiple SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the multiple RACH opportunities, and a second SSB among the multiple SSBs is associated with a second number of RACH opportunities among the multiple RACH opportunities, wherein the first number is different from the second number.

[0121] Embodiment 2: The method of embodiment 1, wherein each of the plurality of SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

[0122] Embodiment 3: The method described in Embodiment 2, wherein the larger the weight parameter of a given SSB is, the larger the number of RACH opportunities with which the given SSB is associated among multiple RACH opportunities is.

[0123] Embodiment 4: The method described in any one of Embodiments 2-3, wherein each of a plurality of SSBs is associated with a corresponding weight parameter set, each weight parameter in the corresponding weight parameter set is associated with a different deployment scenario, and wherein the number of RACH opportunities with which a given SSB among a plurality of RACH opportunities is associated is based on the corresponding weight parameters of the corresponding weight parameter set associated with the deployment scenario of the BS.

[0124] Embodiment 5: The method described in any one of Embodiments 2-4 further includes receiving an indication of a corresponding weight parameter of each of a plurality of SSBs from a BS.

[0125] Embodiment 6: The method of embodiment 5, wherein the indication is received as part of system information broadcast by the BS.

[0126] Embodiment 7: The method described in any one of Embodiments 2-4 further includes selecting a corresponding weight parameter for each of a plurality of SSBs at the UE.

[0127] Embodiment 8: The method of embodiment 7, wherein the selection is performed based on rules configured at the UE.

[0128] Embodiment 9: The method described in any one of Embodiments 7-8, wherein the selection is performed based on one or more of an identified deployment scenario of the BS, a total number of multiple SSBs, or an index of multiple SSBs.

[0129] Embodiment 10: The method of any one of Embodiments 1-9, wherein all UEs in a cell of the BS associate multiple RACH opportunities with multiple SSBs.

[0130] Embodiment 11: The method described in any one of Embodiments 1-9, wherein a first set of UEs in a cell of the BS associates multiple RACH opportunities with multiple SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with multiple SSBs instead of the first plurality of RACH opportunities.

[0131] Embodiment 12: The method of embodiment 11, wherein the plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

[0132] Embodiment 13: The method of embodiment 11, wherein the plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

[0133] Embodiment 14: The method described in Embodiment 12 or 13, wherein the first set of UEs in the cell further associates a second plurality of RACH opportunities with a plurality of SSBs.

[0134] Embodiment 15: A method for wireless communication by a base station (BS), the method comprising: sending multiple synchronization signal blocks (SSBs), each SSB being associated with a different transmit beam of the BS; and receiving a random access preamble from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among the multiple SSBs, wherein the first RACH opportunity is one of multiple RACH opportunities associated with the multiple SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the multiple RACH opportunities, and a second SSB among the multiple SSBs is associated with a second number of RACH opportunities among the multiple RACH opportunities, wherein the first number is different from the second number.

[0135] Embodiment 16: The method of embodiment 15, wherein each of the plurality of SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB in the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

[0136] Embodiment 17: The method described in Embodiment 16, wherein the larger the weight parameter of a given SSB is, the larger the number of RACH opportunities with which the given SSB is associated among multiple RACH opportunities is.

[0137] Embodiment 18: The method of any one of Embodiments 16-17, wherein each of a plurality of SSBs is associated with a corresponding weight parameter set, each weight parameter in the corresponding weight parameter set is associated with a different deployment scenario, and wherein the number of RACH opportunities with which a given SSB among a plurality of RACH opportunities is associated is based on the corresponding weight parameters of the corresponding weight parameter set associated with the deployment scenario of the BS.

[0138] Embodiment 19: The method described in any one of Embodiments 16-18 further includes sending an indication of a corresponding weight parameter of each of a plurality of SSBs to a UE.

[0139] Embodiment 20: The method of Embodiment 19, wherein the indication is sent as part of system information broadcast by the BS.

[0140] Embodiment 21, the method described in any one of Embodiments 15-20, wherein all UEs in the cell of the BS associate multiple RACH opportunities with multiple SSBs.

[0141] Embodiment 22: The method described in any one of Embodiments 15-20, wherein a first set of UEs in a cell of the BS associates multiple RACH opportunities with multiple SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with multiple SSBs instead of the first plurality of RACH opportunities.

[0142] Embodiment 23: The method of Embodiment 22, wherein the plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

[0143] Embodiment 24: The method of Embodiment 22, wherein the plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

[0144] Embodiment 25: The method of Embodiment 23 or 24, wherein the first set of UEs in the cell also associates a second plurality of RACH opportunities with a plurality of SSBs.

[0145] The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement wireless technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement wireless technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement wireless technologies such as NR (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology under development.

[0146] In 3GPP, the term "cell" can refer to the coverage area of ​​a Node B (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and BS, next-generation Node B (gNB or gNodeB), access point (AP), distributed unit (DU), carrier or transmit receive point (TRP) can be used interchangeably. BSs can provide communication coverage for macro cells, pico cells, femto cells and / or other types of cells. Macro cells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access to UEs with service subscriptions. Pico cells can cover relatively small geographic areas and can allow unrestricted access to UEs with service subscriptions. Femto cells can cover relatively small geographic areas (e.g., homes) and can allow UEs associated with femto cells (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.) to have restricted access. BSs for macro cells can be referred to as macro BSs. BSs for pico cells can be referred to as pico BSs. BSs for femto cells can be referred to as femto BSs or home BSs.

[0147] UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a customer premises equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a home appliance, a medical device or medical equipment, a biometric sensor / device, a wearable device (e.g., a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring, a smart bracelet, etc.)), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing device, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. For example, a wireless node can provide connectivity to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, which can be narrowband IoT (NB-IoT) devices.

[0148] In some examples, access to the air interface can be scheduled. The scheduling entity (e.g., BS) allocates resources for communication between some or all devices and equipment within its service area or cell. The scheduling entity can be responsible for scheduling, allocating, reconfiguring and releasing resources for one or more subordinate entities. That is, for scheduled communications, the subordinate entity utilizes the resources allocated by the scheduling entity. The base station is not the only entity that can act as a scheduling entity. In some examples, the UE can act as a scheduling entity and can schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs can use the resources scheduled by the UE for wireless communication. In some examples, the UE can be used as a scheduling entity in a peer-to-peer (P2P) network and / or a mesh network. In the mesh network example, in addition to communicating with the scheduling entity, the UEs can also communicate directly with each other.

[0149] The method disclosed herein includes one or more steps or actions for implementing the method. Without departing from the scope of the claims, the method steps and / or actions can be interchangeable with each other. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0150] As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other ordering of a, b, and c).

[0151] As used herein, the term "determine" includes a variety of actions. For example, "determine" may include computing, calculating, processing, deriving, investigating, searching (e.g., searching in a table, database, or other data structure), determining, etc. In addition, "determine" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. In addition, "determine" may include solving, selecting, choosing, establishing, etc.

[0152] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the various aspects shown herein, but to conform to the full scope consistent with the language of the claims, wherein, unless otherwise specified, the elements mentioned in the singular are not intended to represent "one and only one", but "one or more". Unless otherwise explicitly stated, the term "some" refers to one or more. All structural and functional equivalents of the elements throughout the various aspects described in this disclosure are known or will be known to those of ordinary skill in the art, are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The claims are not interpreted according to 35 U.S.C. § 112 (f), unless the element is explicitly stated using the phrase "unit for...", or in the case of a method claim, the phrase "step for..." is used to state the element.

[0153] The various operations of the above method can be performed by any suitable unit capable of performing the corresponding function. The unit may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs) or processors. Generally, in the case of the operations shown in the figure, these operations may have corresponding corresponding functional components with similar numbers.

[0154] A general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof for performing the functions described herein may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the present disclosure. A general purpose processor may be a microprocessor, but in an alternative example, the processor may be any commercially available 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).

[0155] If implemented in hardware, an exemplary hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link various circuits together, including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In a user terminal (see Figure 1 ), a user interface (e.g., keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits known in the art, such as timing sources, peripherals, voltage regulators, power management circuits, etc., and therefore will not be described further. The processor may be implemented with one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can execute software. Those skilled in the art will recognize how to best implement the described functionality for the processing system depending on the specific application and the overall design constraints imposed on the entire system.

[0156] If implemented in software, the function may be stored on a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Whether referred to as software, firmware, middleware, microcode, hardware description language or other, software should be broadly interpreted as instructions, data or a combination thereof. Computer-readable media include computer storage media and communication media, which include any media that facilitates the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a machine-readable storage medium. The computer-readable storage medium may be coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. In an alternative example, the storage medium may be integrated into the processor. As an example, the machine-readable medium may include a transmission line, a carrier modulated by data and / or a computer-readable storage medium on which instructions are stored and separated from a wireless node, all of which may be accessed by the processor through a bus interface. Alternatively or in addition, the machine-readable medium or any part thereof may be integrated into the processor, such as a case where a cache and / or a general register file may be provided. Examples of machine-readable storage media may include, for example, RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. Machine-readable media may be embodied in a computer program product.

[0157] A software module may include a single instruction or many instructions, and may be distributed across several different code segments, between different programs, and across multiple storage media. A computer-readable medium may include multiple software modules. A software module includes instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a sending module and a receiving module. Each software module may reside in a single storage device or be distributed in multiple storage devices. For example, when a triggering event occurs, a software module may be loaded from a hard drive into a RAM. During the execution of a software module, a processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When the function of a software module is mentioned below, it should be understood that such a function is implemented by the processor when executing instructions from the software module.

[0158] In addition, any connection may be properly termed a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless and microwave are included in the definition of the medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Optical disks, where magnetic disks typically reproduce data magnetically, and optical disks use lasers to reproduce data optically. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transitory computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of computer-readable media.

[0159] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, such as for performing the operations described herein and Fig.11 and / or Fig.12 The operations shown in the instructions.

[0160] In addition, it should be understood that the modules and / or other appropriate units for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by the user terminal and / or base station when applicable. For example, such a device can be coupled to a server to facilitate the transfer of the unit for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage unit (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk), so that the user terminal and / or base station can obtain the various methods when the storage unit is coupled or provided to the device. In addition, any other suitable technology for providing the methods and techniques described herein to the device can be used.

[0161] It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment UE, the method comprising: receiving a plurality of synchronization signal blocks SSB from a base station BS, each SSB being associated with a different transmit beam of said BS; as well as A random access preamble is sent on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number, and wherein each of the plurality of SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB among the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

2. The method according to claim 1, further comprising: An indication of the corresponding weight parameter for each of the plurality of SSBs is received from the BS.

3. The method according to claim 1, further comprising: The corresponding weight parameter is selected at the UE for each of the plurality of SSBs.

4. The method according to claim 3, wherein: The selection is performed based on rules configured at the UE.

5. The method according to claim 3, wherein: The selecting is performed based on one or more of: an identified deployment scenario of the BS, a total number of the plurality of SSBs, or an index of the plurality of SSBs.

6. The method according to claim 1, wherein: All UEs in a cell of the BS associate the multiple RACH opportunities with the multiple SSBs.

7. The method according to claim 1, wherein: A first set of UEs in the cell of the BS associates the plurality of RACH opportunities with the plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the plurality of RACH opportunities.

8. The method according to claim 7, wherein: The plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

9. The method according to claim 7, wherein: The plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

10. A method for wireless communication by a base station BS, the method comprising: Sending a plurality of synchronization signal blocks SSB, each SSB being associated with a different transmit beam of the BS; as well as A random access preamble is received from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among the multiple SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the multiple SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the multiple RACH opportunities, and a second SSB among the multiple SSBs is associated with a second number of RACH opportunities among the multiple RACH opportunities, wherein the first number is different from the second number, and wherein each of the multiple SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB among the multiple RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

11. The method according to claim 10, further comprising: An indication of the corresponding weight parameter for each of the plurality of SSBs is sent to the UE.

12. The method according to claim 10, wherein: All UEs in a cell of the BS associate the multiple RACH opportunities with the multiple SSBs.

13. The method according to claim 10, wherein: A first set of UEs in the cell of the BS associates the plurality of RACH opportunities with the plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the plurality of RACH opportunities.

14. The method according to claim 13, wherein: The plurality of RACH opportunities and the second plurality of RACH opportunities are not adjacent to each other in frequency or time.

15. The method according to claim 13, wherein: The plurality of RACH opportunities and the second plurality of RACH opportunities are adjacent to each other in frequency or time.

16. A user equipment UE, comprising: Memory; as well as a processor coupled to the memory, wherein the memory and processor are configured to: receiving a plurality of synchronization signal blocks SSB from a base station BS, each SSB being associated with a different transmit beam of said BS; as well as A random access preamble is sent on a first random access channel (RACH) opportunity associated with a first SSB among the plurality of SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the plurality of SSBs, wherein the first RACH opportunity is selected based on a measurement of the plurality of SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the plurality of RACH opportunities, and a second SSB among the plurality of SSBs is associated with a second number of RACH opportunities among the plurality of RACH opportunities, wherein the first number is different from the second number, and wherein each of the plurality of SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB among the plurality of RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

17. The UE according to claim 16, wherein: The memory and processor are further configured to receive, from the BS, an indication of the corresponding weight parameter for each of the plurality of SSBs.

18. The UE according to claim 16, wherein: The memory and processor are configured to select, at the UE, the corresponding weight parameter for each of the plurality of SSBs.

19. The UE according to claim 18, wherein: The selection is performed based on rules configured at the UE.

20. The UE according to claim 18, wherein: The selecting is performed based on one or more of: an identified deployment scenario of the BS, a total number of the plurality of SSBs, or an index of the plurality of SSBs.

21. The UE according to claim 16, wherein: All UEs in a cell of the BS associate the multiple RACH opportunities with the multiple SSBs.

22. The UE according to claim 16, wherein: A first set of UEs in the cell of the BS associates the plurality of RACH opportunities with the plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the plurality of RACH opportunities.

23. A base station BS, comprising: Memory; as well as a processor coupled to the memory, wherein the memory and processor are configured to: sending a plurality of synchronization signal blocks SSB, each SSB being associated with a different transmit beam of the BS; and A random access preamble is received from a user equipment (UE) on a first random access channel (RACH) opportunity associated with a first SSB among the multiple SSBs, wherein the first RACH opportunity is one of a plurality of RACH opportunities associated with the multiple SSBs, wherein the first SSB is associated with a first number of RACH opportunities among the multiple RACH opportunities, and a second SSB among the multiple SSBs is associated with a second number of RACH opportunities among the multiple RACH opportunities, wherein the first number is different from the second number, and wherein each of the multiple SSBs is associated with a corresponding weight parameter, wherein the number of RACH opportunities with which a given SSB among the multiple RACH opportunities is associated is based on the corresponding weight parameter of the given SSB.

24. The BS according to claim 23, wherein: The memory and processor are also configured to send an indication of the corresponding weight parameter for each of the plurality of SSBs to the UE.

25. The BS according to claim 23, wherein: All UEs in a cell of the BS associate the multiple RACH opportunities with the multiple SSBs.

26. The BS according to claim 23, wherein: A first set of UEs in the cell of the BS associates the plurality of RACH opportunities with the plurality of SSBs, and a second set of UEs in the cell of the BS associates a second plurality of RACH opportunities with the plurality of SSBs instead of the plurality of RACH opportunities.

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