Patent Description:
<CIT> relates to schemes, methods, systems and the like for beam refinement and collision avoidance. <CIT> relates to random access (RA) procedure in the new radio (NR) access system with beamforming.

<NUM> NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (such as with Internet of Things (IoT)), and other requirements.

In particular, wireless communication may include a random access procedure that allows a user equipment (UE) to initiate or resume communications with a base station. Under certain channel conditions, various messages of the random access procedure may not be received correctly, which may delay or prevent the UE from connecting to the base station. Wireless communication may include a random access procedure. Improvements are presented herein.

However, it will be apparent to those of ordinary skill in the art that these concepts may be practiced without these specific details. In some instances, structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Using a random access channel (RACH) procedure, a user equipment (UE) may be able to initiate or resume communications with a base station based on an exchange of four messages between the UE and the base station. The messages for the RACH procedure may be referred to interchangeably as numbered random access messages (such as random access message <NUM>), numbered RACH messages (such as RACH message <NUM>), or abbreviated as a numbered "Msg" (such as Msg <NUM>). Under some channel conditions, messages transmitted as part of the RACH procedure may not be received correctly. In particular, when high carrier frequencies are utilized, transmissions may be subject to high path loss. Beamforming between a user equipment (UE) and a base station may overcome the path loss experienced at high carrier frequencies. During a RACH procedure, however, beamforming between the UE and the base station may not be established, for example, because the UE has been inactive prior to the RACH procedure.

Various aspects of the present disclosure generally relate to random access procedures and beam refinement. In some particular aspects, a base station may transmit multiple repetitions of a RACH message <NUM>, which may increase the likelihood that the RACH message <NUM> will be successfully received by a UE. Additionally, the base station may transmit the multiple repetitions of the RACH message <NUM> using different beams based on receiving a RACH message <NUM>. The UE may receive the multiple repetitions of the RACH message <NUM> on multiple PDCCH candidates. In some implementations, the UE may soft combine the multiple PDCCH candidates and decode the RACH message <NUM> based on the combination. The UE may measure a received power of one or more of the multiple PDCCH candidates based on the decoded RACH message <NUM>. The UE may select a strongest beam based on a respective measured received power for the multiple PDCCH candidates. In some such implementations, the UE may select a time offset based on the strongest beam and transmit a RACH message <NUM> with the time offset to indicate the strongest beam to the base station. For example, the UE may time shift the RACH message <NUM> by the time offset. The base station may receive the RACH message <NUM> at the time offset and select the refined beam for transmitting the RACH message <NUM> based on the time offset. The refined beam may improve the likelihood of successful reception for the RACH message <NUM>.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some implementations, the described techniques can be used to improve reliability of the RACH procedure, and thus, facilitate access to a wireless network and establish a communication connection between a UE and a base station. For example, the UE may be able to more reliably receive the RACH message <NUM> PDCCH due to the repetition and the use of different beams. In some implementations, because the offset for the RACH message <NUM> indicates the best beam for the RACH message <NUM> PDCCH, the base station may select the best beam for transmission of the RACH message <NUM> such that the reliability of message <NUM> is also improved.

These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, among other examples (collectively referred to as "elements").

Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, among other examples, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more examples, the functions described may be implemented in hardware, software, or any combination thereof. By way of example, and not limitation, such computer-readable media can include a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations <NUM>, UEs <NUM>, an Evolved Packet Core (EPC) <NUM>, and another core network <NUM> (for example, a <NUM> Core (5GC)). The base stations <NUM> may include macrocells (high power cellular base station) or small cells (low power cellular base station).

In an aspect, one or more of the UEs <NUM> may include a UE RACH component <NUM> configured to perform a RACH procedure including receiving a plurality of repeated PDCCH candidates for random access message <NUM>, also referred to as a random access response (RAR). The UE RACH component <NUM> may include a RAR receiving component <NUM> configured to receive a plurality of repeated physical downlink control channel (PDCCH) candidates for a single random access message <NUM> during a random access response window, an offset component <NUM> configured to transmit a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset selected based on a strongest of the plurality of repeated PDCCH candidates. The UE RACH component <NUM> may include a contention resolution component <NUM> configured to receive a random access message <NUM>.

In an aspect, one or more of the base stations <NUM> may include a BS RACH component <NUM> configured to repeat transmissions of random access message <NUM> PDCCH candidates. The BS RACH component <NUM> may include a repetition component <NUM> configured to transmit a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window and a detection component <NUM> configured to receive a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset selected based on a strongest of the plurality of repeated PDCCH candidates. The BS RACH component <NUM> may include a beam selection component <NUM> configured to select a beam for transmitting a random access message <NUM> based on the offset. The BS RACH component <NUM> may include a transmission component (not shown) configured to transmit the random access message <NUM> using the selected beam.

The base stations <NUM> configured for <NUM> LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC <NUM> through first backhaul links <NUM> (for example, an S1 interface). In addition to other functions, the base stations <NUM> may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (for example, handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations <NUM> may communicate directly or indirectly (for example, through the EPC <NUM> or core network <NUM>) with each other over third backhaul links <NUM> (for example, X2 interface). The third backhaul links <NUM> may be wired or wireless.

For example, the small cell 102a may have a coverage area 110a that overlaps the coverage area <NUM> of one or more macro base stations <NUM>. The communication links <NUM> between the base stations <NUM> and the UEs <NUM> may include uplink (UL) (also referred to as reverse link) transmissions from a UE <NUM> to a base station <NUM> or downlink (DL) (also referred to as forward link) transmissions from a base station <NUM> to a UE <NUM>. The communication links <NUM> may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, or transmit diversity. The base stations <NUM> / UEs <NUM> may use spectrum up to Y MHz (for example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, among other examples) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. Allocation of carriers may be asymmetric with respect to DL and UL (for example, more or fewer carriers may be allocated for DL than for UL).

Some UEs <NUM> may communicate with each other using device-to-device (D2D) communication link <NUM>.

The small cell 102a may operate in a licensed or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102a may employ NR and use the same <NUM> unlicensed frequency spectrum as used by the Wi-Fi AP <NUM>. The small cell 102a, employing NR in an unlicensed frequency spectrum, may boost coverage to or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In <NUM> NR two initial operating bands have been identified as frequency range designations FR1 (<NUM> - <NUM>) and FR2 (<NUM> - <NUM>). Although a portion of FR1 is greater than <NUM>, FR1 is often referred to (interchangeably) as a "Sub-<NUM>" band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a "millimeter wave" (mmW) band in documents and articles, despite being different from the extremely high frequency (EHF) band (<NUM> - <NUM>) which is identified by the International Telecommunications Union (ITU) as a "millimeter wave" band.

Communications using the mmW radio frequency band have extremely high path loss and a short range. The mmW base station <NUM> may utilize beamforming <NUM> with the UE <NUM> to compensate for the path loss and short range.

The base station <NUM> may transmit a beamformed signal to the UE <NUM> in one or more transmit directions 182a. The UE <NUM> may receive the beamformed signal from the base station <NUM> in one or more receive directions 182b.

The IP Services <NUM> may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, or other IP services.

The IP Services <NUM> may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, or other IP services.

The base station may include or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. Examples of UEs <NUM> include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (for example, MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs <NUM> may be referred to as IoT devices (for example, parking meter, gas pump, toaster, vehicles, heart monitor, among other examples).

In the examples provided by Figure s 2A, 2C, the <NUM>/NR frame structure is assumed to be TDD, with subframe <NUM> being configured with slot format <NUM> (with mostly DL), where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe <NUM> being configured with slot format <NUM> (with mostly UL). Note that the description presented herein applies also to a <NUM>/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure or different channels.

The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), or UCI.

The controller/processor <NUM> provides RRC layer functionality associated with broadcasting of system information (such as MIB, SIBs), RRC connection control (such as RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The TX processor <NUM> handles mapping to signal constellations based on various modulation schemes (such as binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (such as a pilot) in the time or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The channel estimate may be derived from a reference signal or channel condition feedback transmitted by the UE <NUM>.

The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal.

The controller/processor <NUM> is also responsible for error detection using an ACK or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station <NUM>, the controller/processor <NUM> provides RRC layer functionality associated with system information (for example, MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The controller/processor <NUM> is also responsible for error detection using an ACK or NACK protocol to support HARQ operations.

At least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM> may be configured to perform aspects in connection with the UE RACH component <NUM> of <FIG>.

At least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM> may be configured to perform aspects in connection with the BS RACH component <NUM> of <FIG>.

<FIG> is a diagram <NUM> illustrating an example message exchange for a RACH procedure between a base station <NUM> and a UE <NUM> in an access network. The UE <NUM> may be an NR-Light UE and include a UE RACH component <NUM>. The base station <NUM> may include a BS RACH component <NUM>.

Referring additionally to Table <NUM> (below), during operation, UE <NUM> may execute an implementation of an NR RACH procedure <NUM>, according to a <NUM>-step NR RACH message flow, due to the occurrence of one or more RACH trigger events <NUM>. Suitable examples of RACH trigger events <NUM> may include, but are not limited to: (i) the UE <NUM> performing an initial access to transition from an RRC_IDLE state to RRC_CONNECTED ACTIVE state; (ii) the UE <NUM> detecting downlink (DL) data arrival during while in an RRC_IDLE state or RRC_CONNECTED INACTIVE state; (iii) the UE <NUM> determining UL data arrival from higher layers during RRC_IDLE state or RRC_CONNECTED INACTIVE state; (iv) the UE <NUM> performing a handover from another station to the base station <NUM> during the connected mode of operation; and (v) the UE performing a connection re-establishment procedure such as a beam failure recovery procedure.

The NR RACH procedure <NUM> may be associated with a contention based random access procedure, or with a contention free random access procedure. In an implementation, a contention based NR RACH procedure corresponds to the following RACH trigger events <NUM>: an initial access from RRC_IDLE to RRC_CONNECTED ACTIVE; UL data arrival during RRC_IDLE or RRC_CONNECTED INACTIVE; and a connection re-establishment. In an implementation, a contention-free NR RACH procedure corresponds to the following RACH trigger events <NUM>: downlink (DL) data arrival during RRC_IDLE or RRC_CONNECTED INACTIVE; and, a handover during the connected mode of operation.

On the occurrence of any of the above RACH trigger events <NUM>, the execution of the NR RACH procedure <NUM> may include the <NUM>-step NR RACH message flow (see <FIG> and Table <NUM>), where UE <NUM> exchanges messages with one or more base stations <NUM> to gain access to a wireless network and establish a communication connection. The messages may be referred to as random access messages <NUM> to <NUM>, RACH messages <NUM> to <NUM>, or may alternatively be referred to by the PHY channel carrying the message, for example, message <NUM> PUSCH.

At <NUM>, for example, UE <NUM> may transmit a first message (Msg <NUM>), which may be referred to as a random access request message, to one or more base stations <NUM> via a physical channel, such as a physical random access channel (PRACH). For example, Msg <NUM> may include one or more of a RACH preamble and a resource requirement. In an aspect, the RACH preamble may be a relatively long preamble sequence, which may be easier for the base station <NUM> to receive than an OFDM symbol. In an aspect, the UE RACH component <NUM> may select a beam for transmission of the Msg <NUM> based on received synchronization signal blocks (SSBs) transmitted by the base station <NUM>.

At <NUM>, one of more of the base stations <NUM> may respond to Msg <NUM> by transmitting a second message (Msg <NUM>), which may be referred to as a random access response (RAR) message, over a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH). In an aspect, the RAR receiving component <NUM> may receive the RAR message. The RAR receiving component <NUM> may monitor the PDCCH during a RAR window based on the Msg <NUM> to detect a PDCCH portion of the RAR message as a DCI format 1_0 with a CRC scrambled by the corresponding RA-RNTI and receive a PDSCH portion of the RAR message as a transport block in a corresponding PDSCH within the window.

In an aspect, at <NUM>, the base station <NUM> may repeat the PDCCH portion of the Msg <NUM>. That is, the base station <NUM> may repeat the Msg <NUM> on corresponding PDCCH candidates within a random access search space on consecutive slots. In an aspect, the BS RACH component <NUM> may determine whether to repeat the PDCCH portion of Msg <NUM> based on detection of a coverage enhancement condition. For example, the BS RACH component <NUM> may determine to repeat the Msg <NUM> based on a signal strength of the Msg <NUM>. For instance, the BS RACH component <NUM> may repeat the Msg <NUM> when the signal strength of the Msg <NUM> is less than a threshold. The base station <NUM> may repeat the PDCCH portion of the Msg <NUM> using different refined beams. That is, the base station <NUM> may sweep beams for the PDCCH portion of the Msg <NUM>. In an aspect, each of the different refined beams may be a sub-beam of a beam corresponding to the Msg <NUM>. A sub-beam may refer to a lower level beam in a hierarchical set of beams. For example, a layer <NUM> (L1) beam may cover multiple L2 beams, which may each cover multiple L3 beams. In other words, the refined sub-beam may have a narrower aperture included within a wider aperture of the higher level beam. In an implementation, the beam corresponding to Msg <NUM> is an L2 beam and each of the different refined beams is an L3 beam. The L3 refined beams for the repetitions of the PDCCH portion of the Msg <NUM> may be based on an L2 beam used for the Msg <NUM>. That is, the base station <NUM> may generate different sub-beams corresponding to the L2 beam to attempt to improve reception of the Msg <NUM>.

The UE <NUM> or the RAR receiving component <NUM> may perform blind detection after soft combination of the PDCCH candidates. That is, the UE <NUM> may receive a signal corresponding to each of the PDCCH candidates, soft combine the signals received for each of the PDCCH candidates, and perform blind detection for the DCI on the combined signal. Accordingly, the UE <NUM> may be more likely to successfully detect the Msg <NUM> PDCCH. The RAR receiving component <NUM> may perform a separate reference signal received power (RSRP) measurement on the PDCCH candidates using the successfully decoded Msg <NUM> as a reference signal. The RAR receiving component <NUM> may select a PDCCH candidate and corresponding beam based on the RSRP (for example, the PDCCH candidate having the strongest RSRP).

At <NUM>, the RAR receiving component <NUM> may receive a transport block in a corresponding PDSCH indicated by the PDCCH within the RAR window. The RAR receiving component <NUM> may pass the transport block to higher layers, which may parse the transport block for a random access preamble identity (RAPID) associated with the Msg <NUM>. For example, Msg <NUM> may include one or more of a detected preamble identifier (ID), a timing advance (TA) value, a temporary cell radio network temporary identifier (TC-RNTI), a backoff indicator, an UL grant, and a DL grant. If the higher layers identify the RAPID in the transport block, the higher layers indicate an uplink grant to the RAR receiving component <NUM> at the physical layer. This is referred to as RAR UL grant in the physical layer.

At <NUM>, in response to receiving Msg <NUM>, UE <NUM> or the offset component <NUM> transmits to the base station <NUM> a third message (Msg <NUM>), which may be an RRC connection request or a scheduling request, via a physical uplink channel such as PUSCH based on the RAR UL grant provided in Msg <NUM> of the serving base station <NUM>. In an aspect, where the UE <NUM> has received the repeated Msg <NUM> PDCCH, the UE <NUM> may time shift the resources of the Msg <NUM> by an offset based on the strongest PDCCH candidate. For example, the offset may be a number of symbols or number of slots equal to the slot number of the strongest PDCCH candidate. In another aspect, the UE <NUM> may select a refined beam for the Msg <NUM>. For example, the UE <NUM> may select a beam corresponding to the PDCCH candidate having the strongest RSRP.

At <NUM>, in response to receiving Msg <NUM>, base station <NUM> or the beam selection component <NUM> may transmit a fourth message (Msg <NUM>), which may be referred to as a contention resolution message, to UE <NUM> via a PDCCH and a PDSCH. For example, Msg <NUM> may include a cell radio network temporary identifier (C-RNTI) for UE <NUM> to use in subsequent communications. The base station <NUM> may select a beam based on the offset at which the Msg <NUM> is received. The selected beam may correspond to a sub-beam used to transmit the Msg <NUM> on the PDCCH candidate that the UE <NUM> selected as the strongest. The base station <NUM> may transmit the Msg <NUM> using the selected beam. The contention resolution component <NUM> may receive the Msg <NUM>.

In some example scenarios, a collision between two or more UEs <NUM> requesting access can occur. For instance, two or more UEs <NUM> may send Msg <NUM> having a same RACH preamble because the number of RACH preambles may be limited and may be randomly selected by each UE <NUM> in a contention-based NR RACH procedure. As such, each colliding UE <NUM> that selects the same RACH preamble will receive the same temporary C-RNTI and the same UL grant, and thus each UE <NUM> may send a similar Msg <NUM>. In this case, base station <NUM> may resolve the collision in one or more ways. In a first scenario, a respective Msg <NUM> from each colliding UE <NUM> may interfere with the other Msg <NUM>, so base station <NUM> may not send Msg <NUM>. Then each UE <NUM> will retransmit Msg <NUM> with a different RACH preamble. In a second scenario, base station <NUM> may successfully decode only one Msg <NUM> and send an ACK message to the UE <NUM> corresponding to the successfully decoded Msg <NUM>. In a third scenario, base station <NUM> may successfully decode the Msg <NUM> from each colliding UE <NUM>, and then send a Msg <NUM> having a contention resolution identifier (such as an identifier tied to one of the UEs) to each of the colliding UEs. Each colliding UE <NUM> receives the Msg <NUM>, decodes the Msg <NUM>, and determines if the UE <NUM> is the correct UE by successfully matching or identifying the contention resolution identifier. Such a problem may not occur in a contention-free NR RACH procedure, as in that case, base station <NUM> may inform UE <NUM> of which RACH preamble to use.

<FIG> is a diagram <NUM> illustrating example resources for repetition of a random access message <NUM>. The resources <NUM> may be located within consecutive slots <NUM>, <NUM>, <NUM>, and <NUM>, which may be during a RAR window. The base station <NUM> may transmit a repetition of the Msg <NUM> on PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> of the Msg <NUM> in each slot <NUM>, <NUM>, <NUM>, and <NUM> using a different refined beam. The PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> may be located within a random access search space portion of the control resource set (CORESET) <NUM>. That is, each PDCCH candidate <NUM>, <NUM>, <NUM>, and <NUM> may include the same data, but be transmitted with different beamforming parameters. For example, the base station <NUM> or the repetition component <NUM> may utilize different L3 refined beams to transmit each repetition of the Msg <NUM> on the PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> in a respective slot <NUM>, <NUM>, <NUM>, and <NUM>. The L3 refined beams may be based on an L2 beam used for the Msg <NUM>. That is, the base station <NUM> may generate different sub-beams of the L2 beam to attempt to improve reception of the Msg <NUM>.

In an aspect, the UE <NUM> may determine which of the received PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> is the strongest. For example, the UE <NUM> may perform soft combination of the signals corresponding to the plurality of repeated PDCCH candidates. The UE <NUM> may perform blind detection of the DCI format 1_0 on the combined signal after the soft combination. Accordingly, the likelihood of successful detection may be increased by the soft combination. The UE <NUM> may then determine a RSRP for each PDCCH candidate <NUM>, <NUM>, <NUM>, and <NUM> individually based on the Msg <NUM>. That is, the UE <NUM> may use the decoded Msg <NUM> as a reference signal and compare each PDCCH candidate <NUM>, <NUM>, <NUM>, and <NUM> to the reference signal to determine a respective RSRP for each PDCCH candidate <NUM>, <NUM>, <NUM>, and <NUM>. Accordingly, the RSRP may indicate a quality of each PDCCH candidate <NUM>, <NUM>, <NUM>, and <NUM>.

In an aspect, the base station <NUM> may determine whether to transmit the repeated random access Msg <NUM> for a particular UE <NUM> based on a request from the UE <NUM>. For example, the UE <NUM> may indicate a request for coverage enhancement or beam enhancement based on one or a combination of: time resources of the PRACH Msg <NUM>, format of the PRACH Msg <NUM>, or a sequence of the PRACH Msg <NUM>. For example, a subset of the available PRACH sequences may be associated with coverage enhancement.

<FIG> is a diagram illustrating an example portion of a RAR window <NUM> for repetition of a random access message <NUM>. For instance, the RAR window <NUM> may include a first portion <NUM> for a legacy procedure without PDCCH repetition for Msg <NUM> and a second portion <NUM> for a RACH procedure using PDCCH repetition with soft combination over a number of consecutive slots. In an aspect, the base station <NUM> may transmit a management information block (MIB) or remaining minimum system information (RMSI) indicating the portion of the RAR window <NUM> configured for PDCCH repetition. For example, a bit field that defines a length of the RAR window <NUM> may be extended to define the second portion <NUM>. In another aspect, the base station <NUM> may transmit a MIB or RMSI indicating a number of the plurality of repeated PDCCH candidates, for example, <NUM> consecutive slots.

<FIG> is a flowchart of an example method <NUM> for transmitting a random access message <NUM> during a RACH procedure. The method <NUM> may be performed by a UE (such as the UE <NUM>, which may include the memory <NUM> and which may be the entire UE <NUM> or a component of the UE <NUM> such as the UE RACH component <NUM>, TX processor <NUM>, the RX processor <NUM>, or the controller/processor <NUM>). The method <NUM> may be performed by the UE RACH component <NUM> in communication with the BS RACH component <NUM> of the base station <NUM>.

At block <NUM>, the method <NUM> may include receiving a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window. In an aspect, for example, the UE <NUM>, the RX processor <NUM> or the controller/processor <NUM> may execute the UE RACH component <NUM> or the RAR receiving component <NUM> to receive the plurality of repeated PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> for a single random access message <NUM> during a RAR window <NUM>. For example, the RAR receiving component <NUM> may perform soft combination of the plurality of repeated PDCCH candidates and perform blind detection of downlink control information after the soft combination of the plurality of repeated PDCCH candidates. The RAR receiving component <NUM> may perform a separate RSRP measurement for each of the plurality of repeated PDCCH candidates. The RAR receiving component <NUM> may determine the strongest of the plurality of repeated PDCCH candidates based on the measurements. Accordingly, the UE <NUM>, the RX processor <NUM>, or the controller/processor <NUM> executing the UE RACH component <NUM> or the RAR receiving component <NUM> may provide means for receiving a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window.

At block <NUM>, the method <NUM> may include transmitting a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset based on a strongest of the plurality of repeated PDCCH candidates. In an aspect, for example, the UE <NUM>, the controller/processor <NUM>, or the TX processor <NUM> may execute the UE RACH component <NUM> or the offset component <NUM> to transmit a random access message <NUM> on resources indicated by the random access message <NUM> time shifted by the offset based on the strongest of the plurality of repeated PDCCH candidates. In an aspect, the offset component <NUM> may select an uplink beam for the random access message <NUM> based on the strongest of the plurality of repeated PDCCH candidates. Accordingly, the UE <NUM>, the TX processor <NUM>, or the controller/processor <NUM> executing the UE RACH component <NUM> or the offset component <NUM> may provide means for transmitting a random access message <NUM> on resources indicated by the random access message <NUM> time shifted by an offset based on a strongest of the plurality of repeated PDCCH candidates.

At block <NUM>, the method <NUM> may include receiving a random access message <NUM> that is transmitted using a beam selected by the base station based on the offset. In an aspect, for example, the UE <NUM>, the RX processor <NUM>, or the controller/processor <NUM> may execute the UE RACH component <NUM> or the contention resolution component <NUM> to receive a random access message <NUM> that is transmitted using a beam selected based on the offset. Accordingly, the UE <NUM>, the RX processor <NUM>, or the controller/processor <NUM> executing the UE RACH component <NUM> or the contention resolution component <NUM> may provide means for receiving a random access message <NUM> that is transmitted using a beam selected by the base station based on the offset.

The method <NUM> may further include determining a coverage enhancement condition and transmitting a physical random access message <NUM> that indicates a request for the plurality of repeated PDCCH candidates based on time resources of the physical random access message <NUM>, a format of the physical random access message <NUM>, a sequence of the physical random access message <NUM>, or any combination thereof.

The method <NUM> may further include determining a coverage enhancement condition and transmitting a physical random access message <NUM> that indicates a request for the plurality of repeated PDCCH candidates during a portion of the random access response window configured for PDCCH repetition (such as the second portion <NUM>). The method <NUM> may further include further receiving a management information block or remaining minimum system information indicating the portion of the random access response window configured for PDCCH repetition. The method <NUM> may further include receiving a management information block or remaining minimum system information indicating a number of the plurality of repeated PDCCH candidates.

<FIG> is a flowchart of an example method <NUM> for transmitting a random access message <NUM> during a RACH procedure. The method <NUM> may be performed by a base station (such as the base station <NUM>, which may include the memory <NUM> and which may be the entire base station <NUM> or a component of the base station <NUM> such as the BS RACH component <NUM>, TX processor <NUM>, the RX processor <NUM>, or the controller/processor <NUM>). The method <NUM> may be performed by the BS RACH component <NUM> in communication with the UE RACH component <NUM> of the UE <NUM>.

At block <NUM>, the method <NUM> may include transmitting a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window. In an aspect, for example, the base station <NUM>, the TX processor <NUM>, or the controller/processor <NUM> may execute the BS RACH component <NUM> or the repetition component <NUM> to transmit a plurality of repeated PDCCH candidates for a single random access message <NUM> during a RAR window <NUM>. Accordingly, the base station <NUM>, the TX processor <NUM>, or the controller/processor <NUM> executing the BS RACH component <NUM> or the repetition component <NUM> may provide means for transmitting a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window.

At block <NUM>, the method <NUM> may include receiving a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> may be time shifted by an offset that indicates a strongest of the plurality of repeated PDCCH candidates. In an aspect, for example, the base station <NUM>, the RX processor <NUM>, or the controller/processor <NUM> may execute the BS RACH component <NUM> or the detection component <NUM> to receive a random access message <NUM> on resources indicated by the random access message <NUM>. Accordingly, the base station <NUM>, the RX processor <NUM>, or the controller/processor <NUM> executing the BS RACH component <NUM> or the detection component <NUM> may provide means receiving a random access message <NUM> on resources indicated by the random access message <NUM>.

At block <NUM>, the method <NUM> may include selecting a beam for transmitting a random access message <NUM> based on the offset. In an aspect, for example, the base station <NUM>, the TX processor <NUM>, or the controller/processor <NUM> may execute the BS RACH component <NUM> or the beam selection component <NUM> to select the beam for transmitting a random access message <NUM> based on the offset. The beam selection component <NUM> may determine the offset at which the random access message <NUM> is received and select a refined beam corresponding to the offset. Accordingly, the base station <NUM>, the RX processor <NUM>, or the controller/processor <NUM> executing the BS RACH component <NUM> or the beam selection component <NUM> may provide means selecting a beam for transmitting a random access message <NUM> based on the offset.

At block <NUM>, the method <NUM> may include transmitting the random access message <NUM> using the selected beam. In an aspect, for example, the base station <NUM>, the TX processor <NUM>, or the controller/processor <NUM> may execute the BS RACH component <NUM> to transmit the random access message <NUM> using the selected beam. Accordingly, the base station <NUM>, the TX processor <NUM>, or the controller/processor <NUM> executing the BS RACH component <NUM> may provide means for transmitting the random access message <NUM> using the selected beam.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication. The apparatus <NUM> may be a UE or a UE may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as method <NUM> of <FIG>. In some aspects, the apparatus <NUM> may include one or more components of the UE described above in connection with <FIG>.

The reception component <NUM> may provide received communications to one or more other components of the apparatus <NUM>, such as the communication manager <NUM>. In some aspects, the reception component <NUM> may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components.

In some aspects, the communication manager <NUM> may generate communications and may transmit the generated communications to the transmission component <NUM> for transmission to the apparatus <NUM>. In some aspects, the transmission component <NUM> may be collocated with the reception component <NUM> in a transceiver.

The communication manager <NUM> may receive a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window; transmit a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset selected based on a strongest of the plurality of repeated PDCCH candidates. The communication manager <NUM> may receive a random access message <NUM> that is transmitted using a beam selected based on the offset. In some aspects, the communication manager <NUM> may include a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>.

In some aspects, the communication manager <NUM> may include a set of components, such as a RAR receiving component <NUM>, an offset component <NUM>, a contention resolution component <NUM> or a combination thereof. Alternatively, the set of components may be separate and distinct from the communication manager <NUM>. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The RAR receiving component <NUM> may receive a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window. The offset component <NUM> may transmit a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset selected based on a strongest of the plurality of repeated PDCCH candidates. The contention resolution component <NUM> may receive a random access message <NUM> that is transmitted using a beam selected based on the offset.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication. The apparatus <NUM> may be a base station or a base station may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as method <NUM> of <FIG>. In some aspects, the apparatus <NUM> may include one or more components of the base station described above in connection with <FIG>.

The reception component <NUM> may provide received communications to one or more other components of the apparatus <NUM>, such as the communication manager <NUM>. In some aspects, the reception component <NUM> may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components. In some aspects, the reception component <NUM> may include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller/processor, a memory, or a combination thereof, of the base station described above in connection with <FIG>.

In some aspects, the communication manager <NUM> may generate communications and may transmit the generated communications to the transmission component <NUM> for transmission to the apparatus <NUM>. In some aspects, the transmission component <NUM> may include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller/processor, a memory, or a combination thereof, of the base station described above in connection with <FIG>. In some aspects, the transmission component <NUM> may be collocated with the reception component <NUM> in a transceiver.

The communication manager <NUM> may transmit a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window; receive a random access message <NUM> on resources indicated by the random access message <NUM>. The resources for the random access message <NUM> are time shifted by an offset selected based on a strongest of the plurality of repeated PDCCH candidates. The communication manager <NUM> may select a beam based on the offset; and transmit a random access message <NUM> using the selected beam. In some aspects, the communication manager <NUM> may include a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the base station described above in connection with <FIG>.

In some aspects, the communication manager <NUM> may include a set of components, such as a repetition component <NUM>, a detection component <NUM>, a beam selection component <NUM>, or a combination thereof. Alternatively, the set of components may be separate and distinct from the communication manager <NUM>. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the base station described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The repetition component <NUM> may transmit a plurality of repeated PDCCH candidates for a single random access message <NUM> during a random access response window. The detection component <NUM> may receive a random access message <NUM> on resources indicated by the random access message <NUM>. The beam selection component <NUM> may select a beam based on the offset receive the random access message <NUM> for a number of repetitions, each repetition using a different refined beam. The transmission component <NUM> may transmit a random access message <NUM> using the selected beam.

The specific order or hierarchy of blocks in the processes / flowcharts disclosed is an illustration of example approaches. Based upon design preferences, the specific order or hierarchy of blocks in the processes / flowcharts may be rearranged.

Claim 1:
A method (<NUM>) of wireless communication by a user equipment, UE, the method (<NUM>) comprising:
receiving (<NUM>), from a base station, a plurality of repeated physical downlink control channel, PDCCH, candidates for a single random access message <NUM> during a random access response window, RAR, wherein the RAR window includes a first portion for a legacy procedure without PDCCH repetition for message <NUM>, and a second portion configured for a random access procedure using PDCCH repetition with soft combination over a number of consecutive slots, and wherein each respective repeated PDCCH candidate of the plurality of repeated PDCCH candidates is located within a respective random access search space portion of a control resource set, CORESET, of a respective slot of the number of consecutive slots during the RAR window;
transmitting (<NUM>) a random access message <NUM> on resources indicated by the random access message <NUM>, wherein the resources for the random access message <NUM> are time shifted by an offset based on a strongest of the plurality of repeated PDCCH candidates; and
receiving (<NUM>) a random access message <NUM> that is transmitted using a beam selected by the base station based on the offset.