Patent Description:
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. Coverage for a random access procedure may be enhanced, for example, by repeating messages. Such enhancements may consume additional resources and may not be appropriate for UEs with good coverage.

<CIT> relates to a communication method and system for converging a fifth generation (<NUM>) communication system for supporting higher data rates beyond a fourth generation (<NUM>) system with a technology for Internet of things (IoT). The communication method and system may be applied to intelligent services based on the <NUM> communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method by a terminal for performing a random access (RA) procedure is provided. The method comprises transmitting a first RA preamble to a base station, initiating to monitor a first RA response (RAR) as a response to the first RA preamble in an RAR window, and based on the terminal failing to receive the first RAR in until end of a retransmission time, transmitting a second RA preamble to the base station.

In a random access procedure, a user equipment (UE) may transmit a first random access message <NUM>. The UE may transmit a second random access message <NUM> in response to determining that a first random access message <NUM> physical downlink control channel (PDCCH) has not been received during a first portion of a first random access response (RAR) window. The second random access message <NUM> may be considered a request for an enhanced coverage random access message <NUM> PDCCH. The UE may monitor for the first message <NUM> PDCCH and a second message <NUM> PDCCH concurrently during a second portion of the first RAR window. A coverage enhanced monitoring procedure for the second message <NUM> PDCCH is different than a monitoring procedure for the first message <NUM> PDCCH. For example, the coverage enhanced monitoring procedure may monitor different PDCCH candidates, soft combine PDCCH candidates, have a different RAR window, have a different downlink control information (DCI) size, or have a different DCI interpretation. The UE may receive and decode a random access message <NUM> PDCCH, the random access message <NUM> PDCCH being one of the first random access message <NUM> PDCCH or the second random access message <NUM> PDCCH. The UE may monitor for a random access message <NUM> PDSCH in response to decoding the random access message <NUM> PDCCH. By concurrently monitoring for the first message <NUM> PDCCH and the second message <NUM> PDCCH, the UE may improve the probability of successfully receiving the message <NUM> PDCCH and a speed of completing a random access procedure.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at a UE. The device may be a processor and/or a modem at a UE or the UE itself. The apparatus transmits a first random access message <NUM>. The apparatus transmits a second random access message <NUM> in response to determining that a first random access message <NUM> physical downlink control channel (PDCCH) has not been received during a first portion of a first random access response (RAR) window. The apparatus monitors for the first random access message <NUM> PDCCH and a second random access message <NUM> PDCCH concurrently during a second portion of the first RAR window. A coverage enhanced monitoring procedure for the second random access message <NUM> PDCCH is different than a monitoring procedure for the first random access message <NUM> PDCCH. The apparatus receives and decodes a random access message <NUM> PDCCH. The random access message <NUM> PDCCH being one of the first random access message <NUM> PDCCH or the second random access message <NUM> PDCCH. The apparatus monitors for a random access message <NUM> PDSCH in response to decoding the random access message <NUM> PDCCH.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at a base station. The device may be a processor and/or a modem at a base station or the base station itself. The apparatus receives, from a UE, a first random access message <NUM>. The apparatus transmits a first random access message <NUM> PDCCH during a first RAR window in response to the first random access message <NUM>. The apparatus receives a second random access message <NUM> during the RAR window. The apparatus transmits a second random access message <NUM> PDCCH in response to the second random access message <NUM> during a second portion of the first RAR window for a coverage enhanced monitoring procedure that is different than a monitoring procedure for the first random access message <NUM> PDCCH. The apparatus transmits a first random access message <NUM> PDSCH based on the first random access message <NUM> PDCCH and a second random access message <NUM> PDSCH based on the second random access message <NUM> PDCCH.

The communication links <NUM> may use multiple-in put and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. Allocation of carriers may be asymmetric with respectto DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL).

The small cell <NUM>', employing NR in an unlicens e d frequency spectrum, may boost coverage to and/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 <CIT> MHz - <NUM>) and <CIT> GHz - <NUM>).

Referring again to <FIG>, in certain aspects, the UE <NUM> may be configured to perform a random access procedure including concurrently monitoring for a first message <NUM> PDCCH and a second message <NUM> PDCCH using an enhanced coverage monitoring procedure. For example, the UE <NUM> may comprise a random access component <NUM> configured to perform a random access procedure including concurrently monitoring for a first message <NUM> PDCCH and a second message <NUM> PDCCH using an enhanced coverage monitoring procedure. The UE <NUM> may transmitting, from a UE, a first random access message <NUM>. The UE <NUM> may transmit, from the UE, a second random access message <NUM> in response to determining that a first random access message <NUM> PDCCH has not been received during a first portion of a first RAR window. The UE <NUM> may monitor for the first random access message <NUM> PDCCH and a second random access message <NUM> PDCCH concurrently during a second portion of the first RAR window, wherein a coverage enhanced monitoring procedure for the second random access message <NUM> PDCCH is different than a monitoring procedure for the first random access message <NUM> PDCCH. The UE <NUM> may receive and decode a random access message <NUM> PDCCH, the random access message <NUM> PDCCH being one of the first random access message <NUM> PDCCH or the second random access message <NUM> PDCCH. The UE <NUM> may monitor for a random access message <NUM> PDSCH in response to decoding the random access message <NUM> PDCCH.

In certain aspects, the base station <NUM> may be configured to perform a random access procedure including transmitting a first message <NUM> PDCCH and a second message <NUM> PDCCH using an enhanced coverage procedure. For example, the base station <NUM> may comprise a random access component <NUM> configured to perform a random access procedure including transmitting a first message <NUM> PDCCH and a second message <NUM> PDCCH using an enhanced coverage procedure. The base station <NUM> may receive, from a UE <NUM>, a first random access message <NUM>. The base station <NUM> may transmit a first random access message <NUM> PDCCH during a first RAR window in response to the first random access message <NUM>. The base station <NUM> may receive a second random access message <NUM> during the first RAR window. The base station <NUM> may transmit a second random access message <NUM> PDCCH in response to the second random access message <NUM> during a second portion of the first RAR window for a coverage enhanced monitoring procedure that is different than a monitoring procedure for the first random access message <NUM> PDCCH. The base station <NUM> may transmit a first random access message <NUM> PDSCH based on the first random access message <NUM> PDCCH and a second random access message <NUM> PDSCH based on the second random access message <NUM> PDCCH.

Although the following description may be focused on 5GNR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

The symbols on DL may be cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbols. For slot configuration <NUM>, different numerologies µ <NUM> to <NUM> allow for <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> slots, respectively, per subframe. <FIG> provide an example of slot configuration <NUM> with <NUM> symbols per slot and numerology µ=<NUM> with <NUM> slots per subframe. The slot duration is <NUM>, the subcarrier spacing is <NUM>, and the symbol duration is approximately <NUM>. Within a set of frames, there may be one or more different bandwidth parts (BWPs) (see <FIG>) that are frequency division multiplexed. Each BWP may have a particular numerology.

The RS may include demodulation RS (DM-RS) (indicated asR for one particular configuration, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE.

The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> CCEs), each CCE including six RE groups (REGs), each REG including <NUM> consecutive REs in an OFDM symbol of an RB. A PDCCH within one BWP may be referred to as a control resource set (CORESET). A UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., common search space, UE-specific search space) during PDCCH monitoring occasions on the CORESET, where the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at greater and/or lower frequencies across the channel bandwidth. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block (also referred to as SS block (SSB)).

The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and hybrid automatic repeat request (HARQ) acknowledgment (ACK) (HARQ-ACK) information (ACK / negative ACK (NACK)) feedback.

Each spatial stream may then be provided to a different antenna <NUM> via a separate transmitter <NUM> TX. Each transmitter <NUM> TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE <NUM>, each receiver <NUM> RX receives a signal through its respective antenna <NUM>. Each receiver <NUM> RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor <NUM>.

A UE and base station may perform a four-step random access channel (RACH) procedure for the UE to obtain initial access to the base station. The UE may acquire a cell by reading a synchronization signal block (SSB) and first system information block (SIB1). SIB1 provides initial access related parameters. The UE may sends msg1 on a physical random access channel (PRACH) with power ramping. If no msg2 random access response (RAR) is received within a RAR window based on the msg1, the UE may send the msg1 again with increased power. If the base station detects msg1, the base station sends msg2, which may include two parts: a control part transmitted on the PDCCH, and a data part transmitted on the PDSCH. The PDCCH is scrambled with a random access radio network temporary identifier (RA-RNTI), which is a function of the RACH occasion (RO) that the UE used to send the msg1. Within the PDSCH, there is a media access control (MAC) control element (CE) (MAC-CE) that acknowledges the reception of the msg1 and grants the UE an uplink (UL) grant to send msg3.

The UE may monitor the PDCCH for a downlink control information (DCI) with format 1_0 scrambled with the RA-RNTI corresponding to the RO that the UE used to transmit msg1. If the DCI is detected, the UE may proceed with PDSCH decoding. If a MAC-CE is found in the PDSCH adding to the preamble the UE used to send msg1, the UE may treat the MAC-CE as being for the UE. Accordingly, the UE may follow the UL grant of the MAC-CE to send a UE-ID in a msg3. There may be a collision from multiple UEs if they used the same preamble sequence in the same RO for sending msg1. The UEs may send the msg3 at the same resource. The base station may receive one or more msg3 and perform contention resolution. The base station may send msg4.

PRACH and msg2 PDCCH are two of the bottlenecks in the coverage of millimeter-wave <NUM> systems. For example, PRACH and msg2 PDCCH may be transmitted before beam training is completed. Accordingly, PRACH and msg2 PDCCH may not be correctly received when transmitted. PRACH repetition and/or using different PRACH formats can be helpful in increasing the PRACH coverage. Msg2 PDCCH repetition can be helpful for increasing coverage of msg2. These repetition techniques, however, may increase use of PRACH and control (e.g., PDCCH) resources.

In an aspect, the present disclosure may provide for improved coverage during a random access procedure by applying coverage enhancement of PRACH and msg2 PDCCH for UEs that are likely to benefit from the coverage enhancement. For example, a UE may selectively perform two or more concurrent PDCCH monitoring for msg2 PDCCH on the same slot and/or set of slots with different monitoring procedures. For instance, one of the monitoring procedures may be a coverage-enhanced random access procedure.

The coverage-enhanced random access procedure may involve different grouping of monitoring occasions for blind detection. Multiple concurrent PDCCH monitoring may be associated with the same RA-RNTI or different RA-RNTIs for blind detection. Two concurrent msg2 PDCCH monitoring may include the following two concurrent procedures: <NUM>) regular msg2 PDCCH monitoring associated with regular random access channel (RACH) procedure and <NUM>) msg2 PDCCH monitoring associated with a second-attempt coverage-enhanced RACH procedure, in which the UE initiates a second attempt for the four-step RACH procedure if the msg2 PDCCH (in response to the PRACH) is not received during the corresponding RAR window (or a portion of the RAR window). The second attempt coverage-enhanced RACH procedure follows an alternative four-step RACH procedure which includes one or more of the following: an alternative (e.g. coverage-enhanced) transmission method for PRACH; an alternative (e.g. coverage-enhanced) method for monitoring and reception of msg2 PDCCH; an alternative RAR window; an alternative size of DCI carried by msg2 PDCCH; or an alternative interpretation of the content of DCI carried by msg2 PDCCH. In an aspect, using the second-attempt coverage-enhanced RACH procedure may depend on previous measurements by the UE (e.g. if SSB-based RSRP is less than a certain threshold). In some cases, the second-attempt coverage-enhanced RACH procedure may surpass PDCCH blind detection limits. The UE may drop a subset of concurrent msg2 monitoring procedures (e.g. the UE may only follow msg2 PDCCH monitoring with the coverage-enhanced procedure).

In an aspect, alternative PDCCH monitoring and reception by UE, may include soft combination of multiple PDCCH candidates over multiple monitoring occasions before decoding and blind detection. For example, the base station (e.g., a gNB) repeats msg2 PDCCH over multiple monitoring occasions (e.g. PDCCH candidates with the same index over multiple slots). In the aggregated monitoring occasions for PDCCH repetition, the corresponding PDCCH candidates with the same aggregation level and location (and/or index) are paired together and the receiver performs soft combination of them, before decoding and checking the cyclic redundancy check (CRC). Monitoring occasions may be grouped into groups of k consecutive monitoring occasions and control resource set (CORESET) locations in each group of aggregated slots form one virtual monitoring occasion for the alternative msg2 PDCCH.

<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 include a UE random access component <NUM>. The base station <NUM> may include a BS random access 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.

In a first step of a first RACH procedure, for example, UE <NUM> transmits a first message (Msg <NUM>) <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. The UE <NUM> may transmit the Msg <NUM> on a RACH occasion (RO). 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 <NUM> may select a beam for transmission of the Msg <NUM> based on received synchronization signal blocks (SSBs) transmitted by the base station <NUM>.

In a second step, the base station <NUM> responds to Msg <NUM> by transmitting a second message (Msg <NUM>), which may be referred to as a random access response (RAR) message. The RAR message may include a control portion <NUM> (e.g., PDCCH portion) and a data portion <NUM> (e.g., PDSCH portion). In an aspect, the UE <NUM> monitors the PDCCH during a first RAR window <NUM> based on the first Msg <NUM><NUM> to detect a PDCCH portion <NUM> of the first RAR message as a DCI format 1_0 with a CRC scrambled by a RA-RNTI corresponding to the first Msg <NUM><NUM> and receive the PDSCH portion <NUM> of the RAR message as a transport block in a corresponding PDSCH within the RAR window <NUM>.

In an aspect, to improve coverage of the PRACH and/or the Msg <NUM> PDCCH, an enhanced coverage RACH procedure is used concurrently with the first RACH procedure. For example, the UE <NUM> transmits a second Msg <NUM> on the PRACH in response to determining that the PDCCH portion <NUM> of the first RAR message is not received during a first portion <NUM> of the first RAR window <NUM>. That is, the UE <NUM> may be configured to start a second, concurrent, enhanced coverage RACH procedure when such a procedure may be helpful. For example, the UE <NUM> may transmit the second Msg <NUM><NUM> in response to a measurement by the UE <NUM> (e.g., if SSB-based RSRP is less than a certain threshold). The UE <NUM> may use a coverage-enhanced transmission method for the second Msg <NUM><NUM>. For instance, the UE <NUM> may repeat transmission of the second Msg <NUM><NUM> on different ROs.

The base station <NUM> responds to the second Msg <NUM><NUM> by transmitting a second control portion <NUM> (e.g., PDCCH portion) of a second Msg <NUM>. The base station <NUM> may transmit the second PDCCH portion <NUM> of the second Msg <NUM> using a coverage-enhanced transmission technique. For example, the base station <NUM> repeats the transmission of the second PDCCH portion <NUM> as one or more repetitions <NUM>. In an implementation, 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 <NUM> may determine whether to repeat the PDCCH portion of Msg <NUM> based on the second Msg <NUM><NUM>. For example, the UE <NUM> may indicate a request for coverage enhancement based on one or a combination of: time resources of the Msg <NUM>, format of the Msg <NUM>, or a sequence of the Msg <NUM>. For example, a subset of the available PRACH sequences may be associated with coverage enhancement.

For example, the BS <NUM> may determine that a preamble of the second Msg <NUM><NUM> follows a pattern to request coverage enhancement. In an implementation, the base station <NUM> may repeat the PDCCH portion of the Msg <NUM> using different refined beams. 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 an implementation, the beam corresponding to Msg <NUM> is an L2 beam and each of the different refined beams is an L3 beam.

As another example, the second PDCCH portion <NUM> utilizes an alternative size of the DCI or an alternative interpretation of the content of the DCI. In an aspect, the base station <NUM> may transmit the second PDCCH portion <NUM> and any repetitions <NUM> during the second portion <NUM> of the first RAR window <NUM>. In some implementations, a second RAR window <NUM> for the second PDCCH portion <NUM> and any repetitions <NUM> may be defined based on the second Msg <NUM><NUM>. The second RAR window <NUM> may overlap the second portion <NUM> of the RAR window <NUM>.

The UE <NUM> concurrently monitors for the PDCCH portion <NUM> of the first Msg <NUM> and monitor for the second PDCCH portion <NUM> of a second Msg <NUM> during the second portion <NUM> of the RAR window <NUM>. The UE <NUM> monitors for the second PDCCH portion <NUM> using a coverage-enhanced monitoring procedure. For example, the UE <NUM> performs soft combining on PDCCH candidates for two or more repetitions of the second PDCCH portion <NUM>. The UE <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. As another example, the UE monitors for an alternative size of DCI. As another example, the UE applies an alternative interpretation to content of a DCI received according to the coverage-enhanced monitoring procedure.

The base station <NUM> transmits a first data portion <NUM> (e.g., PDSCH portion) of the Msg <NUM> and a second data potion <NUM> (e.g., PDSCH portion) of the Msg <NUM>. Because the UE <NUM> may successfully decode either the first PDCCH portion <NUM> or the second PDCCH portion <NUM>, transmitting both PDSCH portions <NUM>, <NUM> may allow the UE <NUM> to receive the complete Msg2 based on either PDCCH portion <NUM>, <NUM>.

The UE <NUM> may receive a transport block in a corresponding PDSCH indicated by a successfully decoded one of the first PDCCH portion <NUM> or the second PDCCH portion <NUM>. The UE <NUM> may decode transport block and 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 UE <NUM> identifies a RAPID corresponding to either the first Msg <NUM><NUM> or the second Msg <NUM><NUM> in the transport block, the UE <NUM> may identify a corresponding UL grant for Msg <NUM>. This is referred to as RAR UL grant in the physical layer.

In response to receiving Msg <NUM>, UE <NUM> transmits to the base station <NUM> a third message (Msg <NUM>) <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 a selected serving base station <NUM>.

In response to receiving Msg <NUM><NUM>, base station <NUM> may transmit a fourth message (Msg <NUM>) <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.

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 one Msg <NUM> of the colliding 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 resource diagram <NUM> illustrating resources for receiving the PDCCH portion of a Msg <NUM> using a coverage-enhanced reception procedure (e.g., for the second PDCCH portion <NUM> and repetitions <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 repeat msg2 PDCCH over multiple monitoring occasions (e.g., PDCCH candidates with the same index over multiple slots). For example, the base station <NUM> may transmit a repetition of the Msg <NUM> on PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM> in each slot <NUM>, <NUM>, <NUM>, and <NUM>, for example, 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> 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 perform an enhanced monitoring procedure on the PDCCH candidates <NUM>, <NUM>, <NUM>, and <NUM>. For example, the UE <NUM> may perform soft combination of the signals corresponding to the plurality of repeated PDCCH candidates. In the aggregated monitoring occasions for PDCCH repetition, the corresponding PDCCH candidates with the same aggregation level and location (and/or index) may be grouped together. For example, monitoring occasions may be grouped to groups of k consecutive monitoring occasions and CORESET locations in each group of aggregated slots may form one virtual monitoring occasion for the alternative Msg <NUM> PDCCH. The receiver may perform soft combination on all monitoring occasions within the virtual monitoring occasion before decoding and checking CRC. 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.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., the UE <NUM>; the apparatus <NUM>; the cellular baseband processor <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 TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>). One or more of the illustrated operations may be omitted, transposed, or contemporaneous. Optional aspects are illustrated with a dashed line. The method may allow a UE to concurrently perform two monitoring procedures for a random access message <NUM> PDCCH, thereby allowing the UE to improve coverage of the message <NUM> PDCCH.

At <NUM>, the UE transmits a first random access message <NUM>. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. The UE transmits the first random access message <NUM> to the base station. For example, the random access component <NUM> may select a first random access preamble for transmission on the PRACH. The random access component <NUM> may provide the first random access preamble to the transmission component <NUM> for transmission.

At <NUM>, the UE transmits from the UE, a second random access message <NUM>. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. The UE transmits the second random access message <NUM> in response to determining that a first random access message <NUM> PDCCH has not been received during a first portion of a first RAR window. In some aspects, the UE determines whether the first random access message <NUM> PDCCH (e.g., PDCCH portion <NUM>) has been received during the first portion of the RAR window. The UE may indicate to the random access component <NUM> when the PDCCH portion has not been received during the first portion of the RAR window. The UE may select a second random access preamble for transmission on the PRACH for the second message <NUM>. The second random access preamble may be the same or different than the first random access preamble.

In some aspects, for example at <NUM>, the UE may utilize a coverage enhanced transmission method for transmitting the second random access message <NUM>. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. In some aspects, the coverage enhanced transmission method may include using different beam and/or multiple repetitions. In some aspects, the UE may transmit the second random access message <NUM> over different beams. For example, at <NUM>, the random access component <NUM> may repeat transmission of the second message <NUM>. Each transmission may be on a different beam.

At <NUM>, the UE monitors for the first random access message <NUM> PDCCH and a second random access message <NUM> PDCCH concurrently during a second portion of the first RAR window. For example, <NUM> may be performed by monitor component <NUM> of apparatus <NUM>. In some aspects, a coverage enhanced monitoring procedure for the second random access message <NUM> PDCCH is different than a monitoring procedure for the first random access message <NUM> PDCCH. For example, the monitoring component <NUM> may monitor for the first message <NUM> PDCCH using a standard monitoring procedure (e.g., blind decoding each PDCCH candidate within the RAR window). The monitoring component <NUM> monitors for the second message <NUM> PDCCH using a coverage enhanced monitoring procedure. For example, at <NUM>, for the coverage enhanced monitoring procedure, the monitoring component <NUM> includes soft combine multiple PDCCH candidates over multiple monitoring occasions before decoding the second random access message <NUM>. For instance, the monitoring component <NUM> may add the log likelihood ratios (LLRs) for received signals of the PDCCH candidates together before performing a decoding procedure on the combined signals. As another example, at <NUM>, the monitoring component <NUM> monitors for an alternative size of DCI for the second random access message <NUM> PDCCH. The alternative size may be based on a different configuration of the DCI format for a second random access message <NUM> PDCCH. Similarly, at <NUM>, the monitoring component <NUM> determines an alternative interpretation of a DCI for the second random access message <NUM> PDCCH. The alternative interpretation may be based on a different configuration of the DCI format for the second random access message <NUM> PDCCH. In some cases, concurrently monitoring for the first random access message <NUM> PDCCH and the second random access message <NUM> PDCCH may use more PDCCH candidates and/or blind detection operations than a defined limit. In such cases, the monitoring component <NUM>, at <NUM>, may drop a subset of concurrent PDCCH candidates for the monitoring procedure for the first random access message <NUM> PDCCH. That is, the monitoring component <NUM> may allocate processing resources to the coverage enhanced monitoring procedure, which may be more likely to detect a random access message <NUM> PDCCH.

At <NUM>, the UE receives and decodes a random access message <NUM> PDCCH. For example, <NUM> may be performed by decoding component <NUM> of apparatus <NUM>. In some aspects, the random access message <NUM> PDCCH may be one of the first random access message <NUM> PDCCH or the second random access message <NUM> PDCCH. For example, the decoding component <NUM> receives and decodes the random access message <NUM> first PDSCH portion or PDSCH portion. For instance, the decoding component <NUM> may successfully decode the PDCCH portion to obtain a DCI that includes time and frequency domain resources for the PDSCH portion. Accordingly, the decoding component <NUM> may instruct the reception component <NUM> to receive the signals for the PDSCH portion on the indicated resources.

At <NUM>, the UE monitors for a random access message <NUM> PDSCH. For example, <NUM> may be performed by PDSCH component <NUM> of apparatus <NUM>. The UE monitors for the random access message <NUM> PDSCH, in response to decoding the random access message <NUM> PDCCH. For example, the PDSCH component <NUM> receives the signals for the PDSCH portion indicated by the successfully decoded message <NUM> PDCCH.

In one configuration, the apparatus <NUM> may be a modem chip and include just the cellular baseband processor <NUM>, and in another configuration, the apparatus <NUM> may be the entire UE (e.g., see <NUM> of <FIG>) and include the aforediscussed additional modules of the apparatus <NUM>.

The communication manager <NUM> includes a random access component <NUM> that is configured to transmit a first random access message, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit, from the UE, a second random access message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to utilize a coverage enhanced transmission method for transmitting the second random access message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to repeat transmission of the second message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a monitoring component <NUM> that is configured to monitor for the first random access message <NUM> PDCCH and a second random access message <NUM> PDCCH concurrently during a second portion of the first RAR window, e.g., as described in connection with <NUM> of <FIG>. The monitoring component <NUM> may be configured to soft combine multiple PDCCH candidates over multiple monitoring occasions before decoding the second random access message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The monitoring component <NUM> may be configured to monitor for an alternative size of DCI for the second random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The monitoring component <NUM> may be configured to determine an alternative interpretation of a DCI for the second random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The monitoring component <NUM> may be configured to drop a subset of concurrent PDCCH candidates for the monitoring procedure for the first random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a decoding component <NUM> that is configured to receive and decode a random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a PDSCH component <NUM> that is configured to monitor for a random access message <NUM> PDSCH, e.g., as described in connection with <NUM> of <FIG>.

In one configuration, the apparatus <NUM>, and in particular the cellular baseband processor <NUM>, includes means for transmitting, from the UE, a first random access message <NUM>. The apparatus includes means for transmitting, from the UE, a second random access message <NUM> in response to determining that a first random access message <NUM> PDCCH has not been received during a first portion of a first RAR window. The apparatus includes means for monitoring for the first random access message <NUM> PDCCH and a second random access message <NUM> PDCCH concurrently during a second portion of the first RAR window. A coverage enhanced monitoring procedure for the second random access message <NUM> PDCCH is different than a monitoring procedure for the first random access message <NUM> PDCCH. The apparatus includes means for receiving and decoding a random access message <NUM> PDCCH, the random access message <NUM> PDCCH being one of the first random access message <NUM> PDCCH or the second random access message <NUM> PDCCH. The apparatus includes means for monitoring for a random access message <NUM> PDSCH in response to decoding the random access message <NUM> PDCCH. The means for transmitting the second random access message <NUM> is configured to utilize a coverage enhanced transmission method. The means for transmitting the second random access message <NUM> is configured to repeat a transmission of the second random access message <NUM>. The apparatus further includes means for soft combining multiple PDCCH candidates over multiple monitoring occasions before decoding the second random access message <NUM> PDCCH. The apparatus further includes means for monitoring for an alternative size of DCI for the second random access message <NUM> PDCCH. The apparatus further includes means for determining an alternative interpretation of a DCI for the second random access message <NUM> PDCCH. The apparatus further includes means for dropping a subset of concurrent PDCCH candidates for the monitoring procedure for the first random access message <NUM> PDCCH. The aforementioned means may be one or more of the aforementioned components of the apparatus <NUM> configured to perform the functions recited by the aforementioned means. As described supra, the apparatus <NUM> may include the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM>.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a base station or a component of a base station (e.g., the base station <NUM>/<NUM>; the apparatus <NUM>; the baseband unit <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 TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>). One or more of the illustrated operations may be omitted, transposed, or contemporaneous. Optional aspects are illustrated with a dashed line. The method may allow a base station to allow a base station to transmit a message <NUM> PDCCH for two concurrent monitoring procedures, thereby enhancing coverage of the message <NUM> PDCCH.

In some aspects, for example at <NUM>, the base station may transmit a configuration indicating a coverage enhanced monitoring procedure. For example, <NUM> may be performed by configuration component <NUM> of apparatus <NUM>. The base station may transmit the configuration indicating the coverage enhanced monitoring procedure to the UE. For example, the configuration may indicate a duration of a first portion of a RAR window before a UE may transmit a second random access message <NUM>, a repetition pattern for second random access message <NUM> PDCCH, a duration of a second RAR window, an alternative DCI size, or an alternative DCI interpretation. The base station may transmit the configuration indicating the coverage enhanced monitoring procedure as system information or an RRC configuration message.

At <NUM>, the base station receives, from a UE, a first random access message <NUM>. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. In some aspects, the base station may receive signals for a PRACH during an RO. The base station may provide the PRACH to the random access component <NUM> to decode. The random access component <NUM> may determine a PRACH preamble transmitted by a UE and determine a RAR window based on the RO.

At <NUM>, the base station transmits a first random access message <NUM> PDCCH during a first RAR window. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. The base station transmits a first random access message <NUM> PDCCH during a first RAR window in response to the first random access message <NUM>. The base station transmits the first random access message <NUM> PDCCH (e.g., first PDCCH portion <NUM>) during the first RAR window in response to the first Msg <NUM>. The base station may schedule the first PDCCH portion during a monitoring occasion of the first RAR window according to a first monitoring procedure.

At <NUM>, the base station receives a second random access message <NUM>. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. In some aspects, the base station receives the second random access message <NUM>, from the UE, in response to the UE determining that the first random access message <NUM> PDCCH has not been received, by the UE, during a first portion of the first RAR window. In some aspects, for example at <NUM>, the base station may utilize a coverage enhanced caption method. For example, <NUM> may be performed by the random access component <NUM>. The random access component <NUM> may be configured to utilize a coverage enhanced caption method. For example, second random access message <NUM> may be repeated and the random access component <NUM> may combine multiple ROs to detect the second random access message <NUM>.

At <NUM>, the base station transmits a second random access message <NUM> PDCCH. For example, <NUM> may be performed by random access component <NUM> of apparatus <NUM>. The base station transmits the second random access message <NUM> PDCCH in response to the second random access message <NUM> during a second portion of the first RAR window for a coverage enhanced monitoring procedure. The coverage enhanced monitoring procedure is different than a monitoring procedure for the first random access message <NUM> PDCCH. In some aspects, for example, the base station may include a coverage enhancement component <NUM> that determines whether to transmit the second random access message <NUM> according to the coverage enhanced monitoring procedure. For example, the coverage enhancement component <NUM> may receive the PRACH preamble for the second random access message <NUM> and determine whether the second random access message <NUM> is a request for enhanced coverage. For instance, the coverage enhancement component <NUM> may determine that enhanced coverage is requested when the PRACH preamble is repeated following a pattern specified in the enhanced coverage configuration. The coverage enhancement component <NUM> may provide a signal to the random access component <NUM> indicating that the second random access message <NUM> has requested enhanced coverage. The random access component <NUM> may then transmit the second random access message <NUM> PDCCH according to the coverage enhanced monitoring procedure.

In some aspects, for example at <NUM>, the base station may transmit the second random access message <NUM> on a different grouping of monitoring occasions than the first random access message <NUM> PDCCH. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. In some aspects, for example at <NUM>, the base station may transmit the second random access message <NUM> PDCCH using a different RA-RNTI than the first random access message <NUM> PDCCH. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. In some aspects, for example at <NUM>, the base station repeats the second random access message <NUM> PDCCH over multiple monitoring occasions. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. In some aspects, for example at <NUM>, the base station may transmit the second random access message <NUM> PDCCH on corresponding PDCCH candidates with a same aggregation level and location within the multiple monitoring occasion. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. In some aspects, for example at <NUM>, the base station transmits an alternative size of DCI for the second random access message <NUM> PDCCH. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. The second random access message <NUM> PDCCH has an alternative interpretation compared to the first random access message <NUM> PDCCH.

At <NUM>, the base station transmits a first random access message <NUM> PDSCH based on the first random access message <NUM> PDCCH and a second random access message <NUM> PDSCH based on the second random access message <NUM> PDCCH. For example, <NUM> may be performed by PDSCH component <NUM> of apparatus <NUM>. For example, the PDSCH component <NUM> may transmit the first random access message <NUM> PDSCH (e.g., first Msg <NUM> PDSCH portion <NUM>) based on the first random access message <NUM> PDCCH (e.g., first Msg <NUM> PDCCH portion <NUM>) and a second random access message <NUM> PDSCH (e.g., second Msg <NUM> PDSCH portion <NUM>) based on the second random access message <NUM> PDCCH (e.g., second Msg <NUM> PDCCH portion <NUM>). The PDSCH component <NUM> may receive an indication of the PDSCH resources from the random access component <NUM>, which transmitted the indication in the DCI. The PDSCH component <NUM> may generate a RAR message including an UL grant for the Msg <NUM>.

The apparatus <NUM> is a BS and includes a baseband unit <NUM>. The baseband unit <NUM> may communicate through a cellular RF transceiver <NUM> with the UE <NUM>. The baseband unit <NUM> may include a computer-readable medium / memory. The baseband unit <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory. The software, when executed by the baseband unit <NUM>, causes the baseband unit <NUM> to perform the various functions described supra. The computer-readable medium / memory may also be used for storing data that is manipulated by the baseband unit <NUM> when executing software. The baseband unit <NUM> further includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>. The components within the communication manager <NUM> may be stored in the computer-readable medium / memory and/or configured as hardware within the baseband unit <NUM>. The baseband unit <NUM> may be a component of the BS <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>.

The communication manager <NUM> includes a configuration component <NUM> that may transmit a configuration indicating a coverage enhanced monitoring procedure, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a random access component <NUM> that receive, from a UE, a first random access message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit a first random access message <NUM> PDCCH during a first RAR window, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to receive a second random access message <NUM>, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to utilize a coverage enhanced caption method, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit a second random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit the second random access message <NUM> on a different grouping of monitoring occasions than the first random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit the second random access message <NUM> PDCCH using a different RA-RNTI than the first random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to repeat the second random access message <NUM> PDCCH over multiple monitoring occasions, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit the second random access message <NUM> PDCCH on corresponding PDCCH candidates with a same aggregation level and location within the multiple monitoring occasion, e.g., as described in connection with <NUM> of <FIG>. The random access component <NUM> may be configured to transmit an alternative size of DCI for the second random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a PDSCH component <NUM> that may transmit a first random access message <NUM> PDSCH based on the first random access message <NUM> PDCCH and a second random access message <NUM> PDSCH based on the second random access message <NUM> PDCCH, e.g., as described in connection with <NUM> of <FIG>. The communication manager <NUM> further includes a coverage enhancement component <NUM> that determines whether to transmit the second random access message <NUM> according to the coverage enhanced monitoring procedure, e.g., as described in connection with <NUM> of <FIG>. The coverage enhancement component <NUM> may be configured to receive the PRACH preamble for the second random access message <NUM> and determine whether the second random access message <NUM> is a request for enhanced coverage, e.g., as described in connection with <NUM> of <FIG>. The coverage enhancement component <NUM> may be configured to determine that enhanced coverage is requested when the PRACH preamble is repeated following a pattern specified in the enhanced coverage configuration, e.g., as described in connection with <NUM> of <FIG>. The coverage enhancement component <NUM> may be configured to indicate that the second random access message <NUM> has requested enhanced coverage, e.g., as described in connection with <NUM> of <FIG>.

In one configuration, the apparatus <NUM>, and in particular the baseband unit <NUM>, includes means for receiving, from a UE, a first random access message <NUM>. The apparatus includes means for transmitting a first random access message <NUM> PDCCH during a first RAR window in response to the first random access message <NUM>. The apparatus includes means for receiving a second random access message <NUM> during the RAR window. The apparatus includes means for transmitting a second random access message <NUM> PDCCH in response to the second random access message <NUM> during a second portion of the first RAR window for a coverage enhanced monitoring procedure that is different than a monitoring procedure for the first random access message <NUM> PDCCH. The apparatus includes means for transmitting a first random access message <NUM> PDSCH based on the first random access message <NUM> PDCCH and a second random access message <NUM> PDSCH based on the second random access message <NUM> PDCCH. The means for receiving the second random access message <NUM> is configured to utilize a coverage enhanced reception method. The means for transmitting the second random access message <NUM> PDCCH is configured to transmit on a different grouping of monitoring occasions than the first random access message <NUM> PDCCH. The means for transmitting the second random access message <NUM> PDCCH is configured to transmit the second random access message <NUM> PDCCH using a different random access radio network temporary identifier (RA-RNTI) than the first random access message <NUM> PDCCH. The means for transmitting the second random access message <NUM> PDCCH is configured to repeat the second random access message <NUM> PDCCH over multiple monitoring occasions. The means for transmitting the second random access message <NUM> PDCCH is configured to transmit the second random access message <NUM> PDCCH on corresponding PDCCH candidates with a same aggregation level and location within the multiple monitoring occasion. The means for transmitting the second random access message <NUM> PDCCH is configured to transmit an alternative size of DCI for the second random access message <NUM> PDCCH. The aforementioned means may be one or more of the aforementioned components of the apparatus <NUM> configured to perform the functions recited by the aforementioned means. As described supra, the apparatus <NUM> may include the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM>.

Claim 1:
A method (<NUM>) of wireless communication at a user equipment, UE, comprising:
transmitting (<NUM>), from the UE, a first random access message <NUM>;
transmitting (<NUM>), from the UE, a second random access message <NUM> in response to determining that a first random access message <NUM> control portion has not been received during a first portion of a first random access response, RAR, window;
monitoring (<NUM>) for the first random access message <NUM> control portion and a second random access message <NUM> control portion concurrently during a second portion of the first RAR window, wherein a coverage enhanced monitoring procedure for the second random access message <NUM> control portion is different than a monitoring procedure for the first random access message <NUM> control portion, wherein the coverage enhanced monitoring procedure includes soft combining multiple control portion candidates over multiple monitoring occasions before decoding the second random access message <NUM> control portion or monitoring for an alternative size of downlink control information, DCI, for the second random access message <NUM> control portion or determining an alternative interpretation of a DCI for the second random access message <NUM> control portion;
receiving and decoding (<NUM>) a random access message <NUM> control portion, the random access message <NUM> control portion being one of the first random access message <NUM> control portion or the second random access message <NUM> control portion; and
monitoring (<NUM>) for a random access message <NUM> data portion in response to decoding the random access message <NUM> control portion.