Patent ID: 12238780

DETAILED DESCRIPTION

A user equipment (UE) may transmit a random access channel (RACH) message to a base station as part of a RACH procedure to initiate communication. The base station may respond with a second RACH message (e.g., msg2, msgB) that includes control information on a physical downlink control channel (PDCCH). However, if UE coverage is poor for certain frequencies (e.g., millimeter Wave 5G) or if a signal for the first RACH message is weak, the base station may be limited in how to boost transmission of the second RACH message to improve coverage. The PDCCH may present a power bottleneck for RACH messages. In one or more examples, the base station is only able to use two or three symbols in the PDCCH because the PDCCH is limited to a core set of resources (CORESET) and thus transmit power increases are limited to the two or three symbols.

To increase coverage and to improve reception of the second RACH message, the UE may monitor for the second RACH message in time and frequency resources that are not limited to the two or three symbols in the PDCCH. Receiving the second RACH message across a greater number of symbols (e.g., more than three symbols) improves reception of the RACH message. According to various aspects described herein, the UE may monitor for and receive the second RACH message in time and frequency resources outside the PDCCH, or resources that are an alternative to resources that include the PDCCH (resources in downlink control information (DCI) in the PDCCH). The resources for the UE to monitor for the second RACH message may be based at least in part on the transmission of the first RACH message absent DCI. That is, the resources for the second message are based at least in part on the first RACH message, DCI is not used to schedule the second RACH message, and the second RACH message is not received in DCI. This provides for improved coverage for the second RACH message, because the UE may receive more symbols for the second RACH message when DCI is not used.

In a RACH procedure, data for the second RACH message on a physical downlink shared channel (PDSCH) is scheduled by DCI carried in the PDCCH. Instead of scheduling the data on the PDSCH via the PDCCH, the base station may schedule the PDSCH via system information, such as in remaining minimum system information (RMSI). In other words, the UE may monitor for the second RACH message in resources that are not scheduled via DCI (e.g., resources in the PDSCH). In some aspects, the second RACH message may be scheduled via a remaining minimum system information (RMSI) message or other system information.

Resources that are not scheduled via DCI may include resources in a downlink (DL) data portion of a DL-centric slot. The DL data portion may sometimes be referred to as the payload of the DL-centric slot. The DL data portion may include the communication resources utilized to communicate DL data from a scheduling entity (e.g., UE or BS) to a subordinate entity (e.g., UE). In some examples, the DL data portion may be a PDSCH. The data portion may be considered to be outside the PDCCH. If a UE is to receive a RACH message outside of the PDCCH, in which DCI is absent, the UE may monitor for the RACH message in a set of resource candidates (e.g., symbols, subcarriers) that are located in the data portion, such as in a PDSCH rather than in the PDCCH of the control portion. For example, the UE may monitor for the RACH message in a set of resource candidates, which includes more symbols than the two or three symbols that are available for the RACH message in the control portion. The set of resource candidates may also be scheduled absent DCI, or scheduled by signaling that is not in DCI.

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements”). These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

FIG.1is a diagram illustrating a wireless network100in which aspects of the present disclosure may be practiced. The wireless network100may be an LTE network, a 5G or NR network, and/or the like. The wireless network100may include a number of BSs110(shown as BS110a, BS110b, BS110c, and BS110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a NR BS, a Node B, a gNB, a 5G node B (NB), an access point, a transmit receive point (TRP), and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown inFIG.1, a BS110amay be a macro BS for a macro cell102a, a BS110bmay be a pico BS for a pico cell102b, and a BS110cmay be a femto BS for a femto cell102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB”, “base station”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” may be used interchangeably herein.

In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network100through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network100may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that can relay transmissions for other UEs. In the example shown inFIG.1, a relay station110dmay communicate with macro BS110aand a UE120din order to facilitate communication between BS110aand UE120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network100may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

A network controller130may couple to a set of BSs and may provide coordination and control for these BSs. Network controller130may communicate with the BSs via a backhaul. The BSs may also communicate with one another directly or indirectly, via a wireless or wireline backhaul.

UEs120(e.g.,120a,120b,120c) may be dispersed throughout wireless network100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and/or the like, that may communicate with a base station, another device (e.g., remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE). UE120may be included inside a housing that houses components of UE120, such as processor components, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs120(e.g., shown as UE120aand UE120e) may communicate directly using one or more sidelink channels (e.g., without using a base station110as an intermediary to communicate with one another). For example, UEs120may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol or a vehicle-to-infrastructure (V2I) protocol), and/or a mesh network. In some aspects, UE120may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the base station110.

The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5G NR two initial operating bands have been identified as frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). It should be understood that although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “Sub-6 GHz” 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” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz-300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” (mmWave) band.

The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHz-24.25 GHz). Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR4a or FR4-1 (52.6 GHz-71 GHz), FR4 (52.6 GHz-114.25 GHz), and FR5 (114.25 GHz-300 GHz). Each of these higher frequency bands falls within the EHF band.

With the above aspects in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, FR4, FR4-a or FR4-1, and/or FR5, or may be within the EHF band.

As shown inFIG.1, the UE120may include a communication manager140. As described in more detail elsewhere herein, the communication manager140may transmit a first RACH message to a base station and monitor for a second RACH message from the base station in a set of resource candidates that are outside of a PDCCH based at least in part on the transmitted first RACH message. Additionally, or alternatively, the communication manager140may perform one or more other operations described herein.

Similarly, the base station110may include a communication manager150. As described in more detail elsewhere herein, the communication manager150may receive a first RACH message from a UE and transmit a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message. Additionally, or alternatively, the communication manager150may perform one or more other operations described herein.

As indicated above,FIG.1is provided merely as an example. Other examples may differ from what is described with regard toFIG.1.

FIG.2shows a block diagram of a design200of base station110and UE120, which may be one of the base stations and one of the UEs inFIG.1. Base station110may be equipped with T antennas234athrough234t, and UE120may be equipped with R antennas252athrough252r, where in general T≥1 and R≥1.

At base station110, a transmit processor220may receive data from a data source212for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. Transmit processor220may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor220may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS)) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor230may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs)232athrough232t. Each modulator232may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream. Each modulator232may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators232athrough232tmay be transmitted via T antennas234athrough234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE120, antennas252athrough252rmay receive the downlink signals from base station110and/or other base stations and may provide received signals to demodulators (DEMODs)254athrough254r, respectively. Each demodulator254may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator254may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector256may obtain received symbols from all R demodulators254athrough254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor258may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE120to a data sink260, and provide decoded control information and system information to a controller/processor280. A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), and/or the like. In some aspects, one or more components of UE120may be included in a housing.

On the uplink, at UE120, a transmit processor264may receive and process data from a data source262and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor280. Transmit processor264may also generate reference symbols for one or more reference signals. The symbols from transmit processor264may be precoded by a TX MIMO processor266if applicable, further processed by modulators254athrough254r(e.g., for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to base station110. At base station110, the uplink signals from UE120and other UEs may be received by antennas234, processed by demodulators232, detected by a MIMO detector236if applicable, and further processed by a receive processor238to obtain decoded data and control information sent by UE120. Receive processor238may provide the decoded data to a data sink239and the decoded control information to controller/processor240. Base station110may include communication unit244and communicate to network controller130via communication unit244. Network controller130may include communication unit294, controller/processor290, and memory292.

Controller/processor240of base station110, controller/processor280of UE120, and/or any other component(s) ofFIG.2may perform one or more techniques associated with a RACH message without a PDCCH, as described in more detail elsewhere herein. For example, controller/processor240of base station110, controller/processor280of UE120, and/or any other component(s) ofFIG.2may perform or direct operations of, for example, process800ofFIG.8, process900ofFIG.9, and/or other processes as described herein. Memories242and282may store data and program codes for base station110and UE120, respectively. A scheduler246may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE120may include means for transmitting a first RACH message to a base station, means for monitoring for a second RACH message from the base station in a set of resource candidates that are outside of a PDCCH based at least in part on the transmitted first RACH message, means for monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information, and/or the like. Additionally, or alternatively, UE120may include means for performing one or more other operations described herein. In some aspects, such means may include communication manager140. Additionally, or alternatively, such means may include one or more components of UE120described in connection withFIG.2.

In some aspects, base station110may include means for receiving a first RACH message from a UE, means for transmitting a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message, and/or the like. Additionally, or alternatively, base station110may include means for performing one or more other operations described herein. In some aspects, such means may include the communication manager150. In some aspects, such means may include one or more components of base station110described in connection withFIG.2.

As indicated above,FIG.2is provided merely as an example. Other examples may differ from what is described with regard toFIG.2.

FIG.3is a diagram300showing an example of a downlink (DL)-centric slot or wireless communication structure, in accordance with various aspects of the present disclosure. The DL-centric slot may include a control portion302. Control portion302may exist in the initial or beginning portion of the DL-centric slot. Control portion302may include various scheduling information and/or control information corresponding to various portions of the DL-centric slot. In some configurations, control portion302may be a PDCCH, as indicated inFIG.3. In some aspects, control portion302may include legacy PDCCH information, shortened PDCCH (sPDCCH) information, a control format indicator (CFI) value (e.g., carried on a physical control format indicator channel (PCFICH)), one or more grants (e.g., downlink grants, uplink grants), and/or the like. Downlink control information (DCI) may be received in the PDCCH. A control resource set (CORESET) may also be limited to the PDCCH.

A UE may use a RACH procedure to synchronize with a base station and to establish a radio resource control (RRC) connection to the base station. This may give the UE the capability to transmit data to and receive data from the base station. To start the RACH procedure, the UE may transmit a first RACH message to the base station to initiate communication with the base station. The base station may, in response, transmit a second RACH message to the UE in DCI, which would be in the PDCCH, shown by control portion302ofFIG.3.

The DL-centric slot may also include a DL data portion304. The DL data portion304may sometimes be referred to as the payload of the DL-centric slot. The DL data portion304may include the communication resources utilized to communicate DL data from the scheduling entity (e.g., UE or BS) to the subordinate entity (e.g., UE). In some configurations, the DL data portion304may be a PDSCH. Data portion304may be considered to be outside the PDCCH. If a UE is to receive a RACH message outside of the PDCCH, in which DCI is absent, the UE may monitor for the RACH message in a set of resource candidates (e.g., symbols, subcarriers) that are located in data portion304, such as in a physical downlink shared channel (PDSCH), rather than in the PDCCH of control portion302. For example, the UE may monitor for second RACH message310in a set of resource candidates308, which includes more symbols than the two or three symbols that are available for the second RACH message in control portion302. The set of resource candidates308may also be scheduled absent DCI, or scheduled by signaling that is not in DCI.

The DL-centric slot may also include an uplink (UL) short burst portion306. UL short burst portion306may sometimes be referred to as an UL burst, an UL burst portion, a common UL burst, a short burst, an UL short burst, a common UL short burst, a common UL short burst portion, and/or various other suitable terms. In some aspects, UL short burst portion306may include one or more reference signals. Additionally, or alternatively, UL short burst portion306may include feedback information corresponding to various other portions of the DL-centric slot. For example, UL short burst portion306may include feedback information corresponding to control portion302and/or data portion304. Non-limiting examples of information that may be included in UL short burst portion306include an acknowledgement (ACK) signal (e.g., a physical uplink control channel (PUCCH) ACK, a physical uplink shared channel (PUSCH) ACK, an immediate ACK), a negative acknowledgement (NACK) signal (e.g., a PUCCH NACK, a PUSCH NACK, an immediate NACK), a scheduling request (SR), a buffer status report (BSR), a hybrid automatic repeat request (HARQ) indicator, a channel state indication (CSI), a CQI, a sounding reference signal (SRS), a demodulation reference signal (DMRS), PUSCH data, and/or various other suitable types of information. UL short burst portion306may include additional or alternative information, such as information pertaining to RACH procedures, scheduling requests, and various other suitable types of information.

As illustrated inFIG.3, the end of DL data portion304may be separated in time from the beginning of UL short burst portion306. This time separation may sometimes be referred to as a gap, a guard period, a guard interval, and/or various other suitable terms. This separation provides time for the switch-over from DL communication (e.g., reception operation by the subordinate entity (e.g., UE)) to UL communication (e.g., transmission by the subordinate entity (e.g., UE)). The foregoing is one example of a DL-centric wireless communication structure, and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

As indicated above,FIG.3is provided as an example. Other examples may differ from what is described with regard toFIG.3.

FIG.4is a diagram400showing an example of an UL-centric slot or wireless communication structure, in accordance with various aspects of the present disclosure. The UL-centric slot may include a control portion402. Control portion402may exist in the initial or beginning portion of the UL-centric slot. The control portion402inFIG.4may be similar to control portion402described above with reference toFIG.4. The UL-centric slot may also include an UL long burst portion404. UL long burst portion404may sometimes be referred to as the payload of the UL-centric slot. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (e.g., UE) to the scheduling entity (e.g., UE or BS). In some configurations, control portion402may be a PDCCH. In some aspects, a UE may receive DCI in control portion402. If the UE is to receive a RACH message in DCI, the UE may receive the RACH message in control portion402.

As illustrated inFIG.4, the end of control portion402may be separated in time from the beginning of UL long burst portion404. This time separation may sometimes be referred to as a gap, guard period, guard interval, and/or various other suitable terms. This separation provides time for the switch-over from DL communication (e.g., reception operation by the scheduling entity) to UL communication (e.g., transmission by the scheduling entity).

The UL-centric slot may also include an UL short burst portion406. UL short burst portion406inFIG.4may be similar to UL short burst portion306described above with reference toFIG.3, and may include any of the information described above in connection withFIG.3. The foregoing is one example of an UL-centric wireless communication structure, and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

As indicated above,FIG.4is provided as an example. Other examples may differ from what is described with regard toFIG.4.

As explained earlier, a UE may transmit a RACH message to a base station to initiate communication with the base station. The RACH message may be what the UE first transmits when the UE is powered on. The RACH message may be transmitted on a physical RACH (PRACH) and may be referred to more generally as a PRACH communication. The UE may use the RACH message to request an uplink allocation from the base station.

A first RACH message may include a PRACH sequence (also referred to as a PRACH preamble or a PRACH preamble sequence) that may be used to differentiate UEs. The UE may use a PRACH format to determine the PRACH sequence and/or transmission properties of the PRACH sequence. The UE may receive an initial RACH configuration in a transmission from the base station and use the initial RACH configuration for transmitting the first RACH message. The first RACH message may initiate a RACH procedure to obtain the uplink allocation.

FIGS.5A and5Bare diagrams illustrating an example500of a 4-step RACH procedure and an example502of a 2-step RACH procedure, respectively. In each example, a UE is performing a RACH procedure with a base station.

In LTE and NR, the 4-step RACH procedure may be a RACH procedure with a four message (msg1, msg2, msg3, msg4) handshake between the UE and the base station. The UE may transmit msg1 with a PRACH preamble to the base station on a PRACH, as an example of a first RACH message. The base station may transmit msg2 to the UE on a PDCCH and a PDSCH, as an example of a second RACH message. Msg2 may include a random access response. In a 4-step RACH procedure, the UE may monitor for the second RACH message (e.g., msg2) in DCI in the PDCCH. However, according to various aspects described herein, the UE may monitor for the second RACH message in a set of resource candidates that are based at least in part on transmitting the first RACH message absent DCI. That is, according to one example, the resources for the second RACH message are based at least in part on the transmitted first RACH message, DCI is not used to schedule the second RACH message, and the second RACH message is not received in DCI. In some aspects, the second RACH message may be scheduled via an RMSI message, or in other system information.

The UE may transmit msg3 on a PUSCH. Msg3 may include a contention request and device information. The base station may transmit msg4 on the PDCCH and the PDSCH. Msg4 may include a contention resolution. The contention request and contention resolution relate to resolving contention from multiple UEs that happen to use the same PRACH preamble.

In NR, the 2-step RACH procedure is another RACH procedure. In the 2-step procedure, a base station broadcasts system information and synchronization signal block (SSB) information to UEs. A UE may transmit a PRACH preamble as part of a msgA message to the base station, as an example of a first RACH message. MsgA may also include a payload. The base station may process the preamble, detect the preamble, and process the payload. The base station may send a response in msgB, as an example of a second RACH message. Msg1 and msg3 of the 4-step RACH may be considered to be collapsed into the msgA, and msg2 and msg4 are considered to be collapsed into msgB.

In a 2-step RACH procedure, the UE may monitor for the second RACH message (e.g., msgB) in DCI in the PDCCH. However, according to various aspects described herein, the UE may instead monitor for the second RACH message in a set of resource candidates that are based at least in part on the transmitted first RACH message absent DCI. That is, the resources for the second RACH message are based at least in part on the first RACH message, DCI is not used to schedule the second RACH message, and the second RACH message is not received in DCI. In some aspects, the second RACH message may be scheduled via an RMSI message, or in other system information.

As indicated above,FIG.5is provided as two examples of a RACH procedure. Other examples may differ from what is described with regard toFIG.5.

A UE may transmit a first RACH message to a base station to initiate communication. The base station may respond with a second RACH message (e.g., msg2, msgB) that includes information on a PDCCH. However, if UE coverage or signal strengths are below a threshold level for certain frequencies (e.g., millimeter Wave 5G), the base station may be limited in how the base station can boost transmission of the second RACH message. The PDCCH may present a bottleneck for RACH messages. The base station is only able to use two or three symbols in the PDCCH because the PDCCH is limited to a CORESET and thus transmit power increases are limited to the two or three symbols.

According to various aspects described herein, the UE may monitor for and receive the second RACH message in time and frequency resources outside the PDCCH. This may be referred to as a PDCCH-less second RACH message (e.g., PDCCH-less msg2, PDCCH-less msgB) or a RACH message without a PDCCH. In one example, because DCI is included in the PDCCH, a RACH message without a PDCCH may be a RACH message without DCI. That is, the DCI may be absent from the RACH message that is without a PDCCH. By transmitting the second RACH message outside the PDCCH, the UE may have a better chance to receive the second RACH message because the UE may receive more symbols for the second RACH message (e.g., up to 14 symbols).

In a RACH procedure, data for the second RACH message on the PDSCH may normally be scheduled by DCI carried in the PDCCH. Instead of scheduling the data on the PDSCH via the PDCCH, the base station may schedule the PDSCH via information in the second RACH message, information in an RMSI message, other system information, and/or the like.

FIG.6illustrates an example600of a base station transmitting a RACH message without a PDCCH, in accordance with various aspects of the present disclosure.FIG.6shows a base station (BS)610(e.g., BS110depicted inFIGS.1and2) and a UE620(e.g., UE120depicted inFIGS.1and2) that may communicate with one another.

As shown by reference number630, UE620may transmit a first RACH message as part of a RACH procedure (e.g., 4-step RACH, 2-step RACH). The first RACH message may include a PRACH preamble. UE620may transmit the first RACH message in a first format that is selected from among the first format and a second format, where the first format indicates that BS610may transmit a responsive second RACH message in alternate resources outside the PDCCH, and the second format indicates that the second RACH message may be transmitted in the PDCCH, as normally expected.

In some aspects, UE620may determine to transmit the first RACH message in the first format based at least in part on a RACH type (e.g., 2-step, 4-step), a signal measurement, a RACH format, a set of RACH sequences (e.g., a preamble sequence subset), a RACH time resource, RACH occasions, a subset of RACH occasions, or a combination thereof. For example, UE620may be configured to use a RACH format and thus the first format may be the RACH format. UE620may receive the RACH format in a configuration message from BS610, such as in an RMSI message or in other system information. BS610may determine to instruct UE620to transmit the first RACH message in the first format based at least in part on a RACH type, a signal measurement, a RACH format, a set of RACH sequences, a preamble sequence subset, RACH occasions, or a subset of RACH occasions, a RACH time resource, or a combination thereof.

In some aspects, UE620may determine to transmit the first RACH message in the first format, rather than the second format, based at least in part on a result of a signal measurement. UE620may measure an RSRP of an SSB broadcast and determine that the RSRP does not satisfy an RSRP threshold. As a result, UE620may determine to use a first format that may trigger a responsive second RACH message that is able to use more symbols and/or more transmit power in alternative resources outside the PDCCH. The RSRP threshold may be a threshold for the PDCCH.

In some aspects, UE620may determine to transmit the first RACH message in the first format based at least in part on a RACH type or a number of RACH sequences. For example, UE620may determine that a particular RACH type, a preamble sequence subset, and/or a threshold number of RACH sequences in a PRACH preamble may be necessary to identify UE620. UE620may thus determine that the second RACH message may be better received in alternate resources outside the PDCCH.

In some aspects, UE620may determine to transmit the first RACH message in the first format based at least in part on any combination of factors discussed above. In some aspects, BS610may configure UE620with rules for selecting the first format over the second format (or any other format) and/or for monitoring the alternative resources for the second RACH message.

As shown by reference number635, BS610may receive the first RACH message and determine how to transmit the second RACH message. For example, BS610may determine to transmit the second RACH message in the alternative resources outside the PDCCH based at least in part on receiving the first RACH message in the first format. BS610may schedule the RACH message via an RMSI message or another system information message that does not involve downlink control information in a PDDCH. In some aspects, BS610may determine to transmit the second RACH message in the alternative resources based at least in part on other characteristics of the first RACH message such as a RACH type, a signal measurement, a RACH format, a set of RACH sequences, a preamble sequence subset of the first RACH message, a RACH time resource, RACH occasions, a subset of RACH occasions, or a combination thereof.

As shown by reference number640, BS610may transmit the second RACH message on the alternative resources outside of the PDCCH. These alternative resources may be part of a set of resource candidates. The set of resource candidates may be in the PDSCH. As shown by reference number645, UE620may monitor the set of resource candidates for the second RACH message, because the alternative resources may be one or more of resources in the set of resource candidates. UE620may perform blind detection on the set of resource candidates to detect on which alternative resources UE620may receive the second RACH message. UE620may also perform a cyclic redundancy check (CRC) for any data received on the alternative resources. The set of resource candidates may be based at least in part on a RACH occasion, which may be a time window for receiving a RACH message. In some aspects, UE620may receive the set of resource candidates from BS610in an RMSI message or in other system information.

UE620may normally receive control information, such as DCI, in the PDCCH for determining a location and/or schedule for receiving data on the PDSCH, but if UE620is to monitor for the second RACH message outside of the PDCCH, there may have to be another way for UE620to receive the control information. In some aspects, UE620may receive the control information in the second RACH message, an RMSI message, or in other system information.

In some aspects, an SSB may include resources that carry a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH)330, and/or the like. An SSB may also be referred to as a synchronization signal and PBCH block. A UE may monitor for and/or measure SSBs using different receive (Rx) beams during an initial network access procedure. Based at least in part on the monitoring and/or measuring, the UE may indicate one or more SSBs with a best signal parameter (e.g., an RSRP parameter and/or the like) to a base station. The base station and the UE may use the one or more indicated SSBs to select one or more beams to be used for communication between the base station and the UE (e.g., for a RACH procedure and/or the like). In some aspects, UE620may determine that a PDSCH is quasi-colocated with an SSB beam and thus UE620may use SSB beam information to locate the PDSCH.

UE620may monitor and receive the second RACH message outside the PDCCH, such as in resources that are based on the first RACH message, absent DCI. The second RACH message may have been boosted by BS610to improve coverage beyond what is available in the PDCCH. UE620may proceed with and complete the RACH procedure and successfully connect to BS610without wasting resources and without adding latency.

FIG.7is a diagram illustrating an example process700performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process700is an example where the UE (e.g., UE120depicted inFIGS.1and2, UE620depicted inFIG.6, and/or the like) performs operations associated with a RACH message without the PDCCH.

As shown inFIG.7, in some aspects, process700may include transmitting a first RACH message to a base station (block710). For example, the UE (e.g., using receive processor258, transmit processor264, controller/processor280, memory282, and/or the like) may transmit a first RACH message to a base station, as described above.

As further shown inFIG.7, in some aspects, process700may include monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information (block720). For example, the UE (e.g., using receive processor258, transmit processor264, controller/processor280, memory282, and/or the like) may monitor for a second RACH message from the base station in a set of resource candidates that are outside of a PDCCH based at least in part on the transmitted first RACH message, as described above.

Process700may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, monitoring for the second RACH message in the set of resource candidates is based at least in part on one or more of a RACH type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions.

In a second aspect, alone or in combination with the first aspect, process700includes receiving information identifying the set of resource candidates from the base station.

In a third aspect, alone or in combination with one or more of the first and second aspects, receiving the information identifying the set of resource candidates includes receiving the information identifying the set of resource candidates in a remaining minimum system information message or in another system information message.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, monitoring for the second RACH message includes performing blind detection on one or more resource candidates of the set of resource candidates.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process700includes determining control information for data on a physical downlink shared channel based at least in part on the second RACH message.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the set of resource candidates is based at least in part on a RACH occasion.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process700includes determining that a physical downlink shared channel is quasi-colocated with an SSB beam based at least in part on a determination that the second RACH message from the base station is outside of the PDCCH.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, monitoring for the second RACH message includes performing a CRC on one or more resource candidates of the set of resource candidates.

AlthoughFIG.7shows example blocks of process700, in some aspects, process700may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted inFIG.7. Additionally, or alternatively, two or more of the blocks of process700may be performed in parallel.

FIG.8is a diagram illustrating an example process800performed, for example, by a base station, in accordance with various aspects of the present disclosure. Example process800is an example where the base station (e.g., BS110depicted inFIGS.1and2, BS610depicted inFIG.6, and/or the like) performs operations associated with a RACH message without the PDCCH.

As shown inFIG.8, in some aspects, process800may include receiving a first RACH message from a UE (block810). For example, the base station (e.g., using transmit processor220, receive processor238, controller/processor240, memory242, and/or the like) may receive a first RACH message from a UE, as described above.

As further shown inFIG.8, in some aspects, process800may include transmitting a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message (block820). For example, the base station (e.g., using transmit processor220, receive processor238, controller/processor240, memory242, and/or the like) may transmit a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message, as described above.

Process800may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, process800includes determining a RACH configuration that specifies that the UE is to transmit the first RACH message in a first format from among the first format and a second format based at least in part on one or more of a RACH type, a signal measurement, a RACH format, a set of RACH sequences, a RACH time resource, or a combination of two or more of the signal measurement, the RACH format, the set of RACH sequences, or the RACH time resource; and transmitting the RACH configuration to the UE.

In a second aspect, alone or in combination with the first aspect, transmitting the RACH configuration includes transmitting the RACH configuration in a remaining minimum system information message or in another system information message.

In a third aspect, alone or in combination with one or more of the first and second aspects, process800includes transmitting information identifying the set of resource candidates to the UE.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, transmitting the information identifying the set of resource candidates includes transmitting the information identifying the set of resource candidates in a remaining minimum system information message or in another system information message.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the set of resource candidates is based at least in part on a RACH occasion.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the second RACH message includes control information for data on a physical downlink shared channel.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the transmitting of the second RACH message in the set of resource candidates outside of the PDCCH is based at least in part on information in the first RACH message, where the information indicates one or more of a RACH message type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the transmitting of the second RACH message in the set of resource candidates outside of the PDCCH is based at least in part on a determination that a signal measurement satisfies a threshold.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, process800includes transmitting a RACH configuration that indicates that the second RACH message is to be transmitted in the set of resource candidates outside of the PDCCH based at least in part on a RACH type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions associated with the first RACH message.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the set of resource candidates are located in a PDSCH.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the second RACH message is scheduled via an RMSI message or another system information message.

AlthoughFIG.8shows example blocks of process800, in some aspects, process800may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted inFIG.8. Additionally, or alternatively, two or more of the blocks of process800may be performed in parallel.

FIG.9is a block diagram of an example apparatus900for wireless communication in accordance with various aspects of the present disclosure. The apparatus900may be, be similar to, include, or be included in a UE (e.g., UE620shown inFIG.6). In some aspects, the apparatus900includes a reception component902, a communication manager904, and a transmission component906, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus900may communicate with another apparatus908(such as a client, a server, a UE, a base station, or another wireless communication device) using the reception component902and the transmission component906.

In some aspects, the apparatus900may be configured to perform one or more operations described herein in connection withFIG.6. Additionally, or alternatively, the apparatus900may be configured to perform one or more processes described herein, such as process700ofFIG.7. In some aspects, the apparatus900may include one or more components of the first UE described above in connection withFIG.2.

The reception component902may provide means for receiving communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus908. The reception component902may provide received communications to one or more other components of the apparatus900, such as the communication manager904. In some aspects, the reception component902may provide means for 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 component902may include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller/processor, a memory, or a combination thereof, of the first UE described above in connection withFIG.2.

The transmission component906may provide means for transmitting communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus908. In some aspects, the communication manager904may generate communications and may transmit the generated communications to the transmission component906for transmission to the apparatus908. In some aspects, the transmission component906may provide means for performing signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and may transmit the processed signals to the apparatus908. In some aspects, the transmission component906may 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 first UE described above in connection withFIG.2. In some aspects, the transmission component906may be co-located with the reception component902in a transceiver.

In some aspects, the communication manager904may provide means for transmitting a first RACH message to a base station, and means for monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information. In some aspects, the communication manager904may include a controller/processor, a memory, or a combination thereof, of the first UE described above in connection withFIG.2. In some aspects, the communication manager904may include the reception component902, the transmission component906, and/or the like. In some aspects, the means provided by the communication manager904may include, or be included within, means provided by the reception component902, the communication manager904, and/or the like.

In some aspects, the communication manager904and/or one or more components of the communication manager904may include or may be implemented within hardware (e.g., one or more of the circuitry described in connection withFIG.2). In some aspects, the communication manager904and/or one or more components thereof may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the UE120described above in connection withFIG.2.

In some aspects, the communication manager904and/or one or more components of the communication manager904may be implemented in code (e.g., as software or firmware stored in a memory), such as the code described in connection withFIG.11. For example, the communication manager904and/or a component (or a portion of a component) of the communication manager904may 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 communication manager904and/or the component. If implemented in code, the functions of the communication manager904and/or a component may be executed by a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the UE120described above in connection withFIG.2.

The number and arrangement of components shown inFIG.9are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown inFIG.9. Furthermore, two or more components shown inFIG.9may be implemented within a single component, or a single component shown inFIG.9may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown inFIG.9may perform one or more functions described as being performed by another set of components shown inFIG.9.

FIG.10is a diagram illustrating an example1000of a hardware implementation for an apparatus1002employing a processing system1004. The apparatus1002may be, be similar to, include, or be included in the apparatus900shown inFIG.9.

The processing system1004may be implemented with a bus architecture, represented generally by the bus1006. The bus1006may include any number of interconnecting buses and bridges depending on the specific application of the processing system1004and the overall design constraints. The bus1006links together various circuits including one or more processors and/or hardware components, represented by a processor1008, the illustrated components, and the computer-readable medium/memory1010. The bus1006may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and/or the like.

The processing system1004may be coupled to a transceiver1012. The transceiver1012is coupled to one or more antennas1014. The transceiver1012provides a means for communicating with various other apparatuses over a transmission medium. The transceiver1012receives a signal from the one or more antennas1014, extracts information from the received signal, and provides the extracted information to the processing system1004, specifically a reception component1016. In addition, the transceiver1012receives information from the processing system1004, specifically a transmission component1018, and generates a signal to be applied to the one or more antennas1014based at least in part on the received information.

The processor1008is coupled to the computer-readable medium/memory1010. The processor1008is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1010. The software, when executed by the processor1008, causes the processing system1004to perform the various functions described herein in connection with a client. The computer-readable medium/memory1010may also be used for storing data that is manipulated by the processor1008when executing software. The processing system1004may include any number of additional components not illustrated inFIG.10. The components illustrated and/or not illustrated may be software modules running in the processor1008, resident/stored in the computer readable medium/memory1010, one or more hardware modules coupled to the processor1008, or some combination thereof.

In some aspects, the processing system1004may be a component of the UE120and may include the memory282and/or at least one of the TX MIMO processor266, the RX processor258, and/or the controller/processor280. In some aspects, the apparatus1002for wireless communication provides means for transmitting a first RACH message to a base station, and means for monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information. The aforementioned means may be one or more of the aforementioned components of the processing system1004of the apparatus1002configured to perform the functions recited by the aforementioned means. As described elsewhere herein, the processing system1004may include the TX MIMO processor266, the RX processor258, and/or the controller/processor280. In one configuration, the aforementioned means may be the TX MIMO processor266, the RX processor258, and/or the controller/processor280configured to perform the functions and/or operations recited herein.

FIG.10is provided as an example. Other examples may differ from what is described in connection withFIG.10.

FIG.11is a diagram illustrating an example1100of an implementation of code and circuitry for an apparatus1102for wireless communication. The apparatus1102may be, be similar to, include, or be included in the apparatus1002shown inFIG.10and/or the apparatus900shown inFIG.9. The apparatus1102may include a processing system1104, which may include a bus1106coupling one or more components such as, for example, a processor1108, computer-readable medium/memory1110, a transceiver1112, and/or the like. As shown, the transceiver1112may be coupled to one or more antennas1114.

As further shown inFIG.11, the apparatus1102may include circuitry for transmitting a first RACH message to a base station (circuitry1116). For example, the apparatus1102may include circuitry1116to enable the apparatus1102to transmit a first RACH message to a base station.

As further shown inFIG.11, the apparatus1102may include circuitry for monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information (circuitry1118). For example, the apparatus1102may include circuitry1118to enable the apparatus1102to monitor for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information.

As further shown inFIG.11, the apparatus1102may include, stored in computer-readable medium1110, code for transmitting a first RACH message to a base station (code1120). For example, the apparatus1102may include code1120that, when executed by the processor1108, may cause the transceiver1112to transmit a first RACH message to a base station.

As further shown inFIG.11, the apparatus1102may include, stored in computer-readable medium1110, code for monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information (code1122). For example, the apparatus1102may include code1124that, when executed by the processor1108, may cause the transceiver1112to monitor for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information.

FIG.11is provided as an example. Other examples may differ from what is described in connection withFIG.11.

FIG.12is a block diagram of an example apparatus1200for wireless communication in accordance with various aspects of the present disclosure. The apparatus1200may be, be similar to, include, or be included in a base station (e.g., base station610shown inFIG.6and/or base station110shown inFIGS.1and2). In some aspects, the apparatus1200includes a reception component1202, a communication manager1204, and a transmission component1206, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus1200may communicate with another apparatus1208(such as a client, a server, a UE, a base station, or another wireless communication device) using the reception component1202and the transmission component1206.

In some aspects, the apparatus1200may be configured to perform one or more operations described herein in connection withFIG.6. Additionally, or alternatively, the apparatus1200may be configured to perform one or more processes described herein, such as process800ofFIG.8. In some aspects, the apparatus1200may include one or more components of the base station described above in connection withFIG.2.

The reception component1202may provide means for receiving communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus1208. The reception component1202may provide received communications to one or more other components of the apparatus1200, such as the communication manager1204. In some aspects, the reception component1202may provide means for performing 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 component1202may 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 withFIG.2.

The transmission component1206may provide means for transmitting communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus1208. In some aspects, the communication manager1204may generate communications and may transmit the generated communications to the transmission component1206for transmission to the apparatus1208. In some aspects, the transmission component1206may provide means for performing signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and may transmit the processed signals to the apparatus1208. In some aspects, the transmission component1206may 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 withFIG.2. In some aspects, the transmission component1206may be co-located with the reception component1202in a transceiver.

The communication manager1204may provide means for receiving a first RACH message from a UE, and means for transmitting a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message. In some aspects, the communication manager1204may include a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the base station described above in connection withFIG.2. In some aspects, the communication manager1204may include the reception component1202, the transmission component1206, and/or the like. In some aspects, the means provided by the communication manager1204may include, or be included within means provided by the reception component1202, the transmission component1204, and/or the like.

In some aspects, the communication manager1204and/or one or more components thereof may include or may be implemented within hardware (e.g., one or more of the circuitry described in connection withFIG.14). In some aspects, the communication manager1204and/or one or more components thereof may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the BS110described above in connection withFIG.2.

In some aspects, the communication manager1204and/or one or more components thereof may be implemented in code (e.g., as software or firmware stored in a memory), such as the code described in connection withFIG.14. For example, the communication manager1204and/or a component (or a portion of a component) of the communication manager1204may 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 communication manager1204and/or the component. If implemented in code, the functions of the communication manager1204and/or a component may be executed by a controller/processor, a memory, a scheduler, a communication unit, or a combination thereof, of the BS110described above in connection withFIG.2.

The number and arrangement of components shown inFIG.12are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown inFIG.12. Furthermore, two or more components shown inFIG.12may be implemented within a single component, or a single component shown inFIG.12may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown inFIG.12may perform one or more functions described as being performed by another set of components shown inFIG.12.

FIG.13is a diagram illustrating an example1300of a hardware implementation for an apparatus1302employing a processing system1304. The apparatus1302may be, be similar to, include, or be included in the apparatus1200shown inFIG.12.

The processing system1304may be implemented with a bus architecture, represented generally by the bus1306. The bus1306may include any number of interconnecting buses and bridges depending on the specific application of the processing system1304and the overall design constraints. The bus1306links together various circuits including one or more processors and/or hardware components, represented by a processor1308, the illustrated components, and the computer-readable medium/memory1310. The bus1306may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and/or the like.

The processing system1304may be coupled to a transceiver1312. The transceiver1312is coupled to one or more antennas1314. The transceiver1312provides a means for communicating with various other apparatuses over a transmission medium. The transceiver1312receives a signal from the one or more antennas1314, extracts information from the received signal, and provides the extracted information to the processing system1304, specifically a reception component1316. In addition, the transceiver1312receives information from the processing system1304, specifically a transmission component1318, and generates a signal to be applied to the one or more antennas1314based at least in part on the received information.

The processor1308is coupled to the computer-readable medium/memory1310. The processor1308is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1310. The software, when executed by the processor1308, causes the processing system1304to perform the various functions described herein in connection with a server. The computer-readable medium/memory1310may also be used for storing data that is manipulated by the processor1308when executing software. The processing system1304may include any number of additional components not illustrated inFIG.13. The components illustrated and/or not illustrated may be software modules running in the processor1308, resident/stored in the computer readable medium/memory1310, one or more hardware modules coupled to the processor1308, or some combination thereof.

In some aspects, the processing system1304may be a component of the UE120and may include the memory282and/or at least one of the TX MIMO processor266, the RX processor258, and/or the controller/processor280. In some aspects, the apparatus1302for wireless communication provides means for receiving a first RACH message from a UE, and means for transmitting a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message. The aforementioned means may be one or more of the aforementioned components of the processing system1304of the apparatus1302configured to perform the functions recited by the aforementioned means. As described elsewhere herein, the processing system1304may include the TX MIMO processor266, the RX processor258, and/or the controller/processor280. In one configuration, the aforementioned means may be the TX MIMO processor266, the RX processor258, and/or the controller/processor280configured to perform the functions and/or operations recited herein.

FIG.13is provided as an example. Other examples may differ from what is described in connection withFIG.13.

FIG.14is a diagram illustrating an example1400of an implementation of code and circuitry for an apparatus1402for wireless communication. The apparatus1402may be, be similar to, include, or be included in the apparatus1102shown inFIG.11, and/or the apparatus1000shown inFIG.10. The apparatus1402may include a processing system1404, which may include a bus1406coupling one or more components such as, for example, a processor1408, computer-readable medium/memory1410, a transceiver1412, and/or the like. As shown, the transceiver1412may be coupled to one or more antennas1414.

As further shown inFIG.14, the apparatus1402may include circuitry for receiving a first RACH message from a UE (circuitry1416). For example, the apparatus1402may include circuitry1416to enable the apparatus1402to receive a first RACH message from a UE.

As further shown inFIG.14, the apparatus1402may include circuitry for receiving the update from the UE based at least in part on the federated learning configuration (circuitry1418). For example, the apparatus1402may include circuitry1418to enable the apparatus1402to receive the update from the UE based at least in part on the federated learning configuration.

As further shown inFIG.14, the apparatus1402may include, stored in computer-readable medium1410, code for receiving a first RACH message from a UE (code1420). For example, the apparatus1402may include code1420that, when executed by the processor1408, may cause the transceiver1412to receiving a first RACH message from a UE.

As further shown inFIG.14, the apparatus1402may include, stored in computer-readable medium1410, code for transmitting a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message (code1422). For example, the apparatus1402may include code1422that, when executed by the processor1408, may cause the transceiver1412to transmit a second RACH message in a set of resource candidates that are outside of a PDCCH based at least in part on receiving the first RACH message.

FIG.14is provided as an example. Other examples may differ from what is described in connection withFIG.14.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method of wireless communication performed by a user equipment (UE), comprising: transmitting a first random access channel (RACH) message to a base station; and monitoring for a second RACH message from the base station in a set of resource candidates that are based at least in part on the transmitted first RACH message absent downlink control information.

Aspect 2: The method of aspect 1, wherein the monitoring for the second RACH message in the set of resource candidates is based at least in part on one or more of a RACH type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions.

Aspect 3: The method of aspect 1 or 2, further comprising receiving information identifying the set of resource candidates from the base station.

Aspect 4: The method of aspect 3, wherein receiving the information identifying the set of resource candidates includes receiving the information identifying the set of resource candidates in a remaining minimum system information message or in another system information message.

Aspect 5: The method of any of aspects 1-4, wherein monitoring for the second RACH message includes performing blind detection on one or more resource candidates of the set of resource candidates.

Aspect 6: The method of any of aspects 1-5, wherein monitoring for the second RACH message includes performing a cyclic redundancy check on one or more resource candidates of the set of resource candidates.

Aspect 7: The method of any of aspects 1-6, further comprising determining control information for data on a physical downlink shared channel based at least in part on the second RACH message.

Aspect 8: The method of any of aspects 1-7, wherein the set of resource candidates is based at least in part on a RACH occasion.

Aspect 9: The method of any of aspects 1-8, further comprising determining that a physical downlink shared channel is quasi-colocated with a synchronization signal and physical broadcast channel block (SSB) beam based at least in part on a determination that the second RACH message from the base station is outside of a physical downlink control channel (PDCCH).

Aspect 10: The method of any of aspects 1-9, wherein the set of resource candidates are located in a physical downlink shared channel.

Aspect 11: The method of any of aspects 1-10, wherein the second RACH message is scheduled via an RMSI message or another system information message.

Aspect 12: A method of wireless communication performed by a base station, comprising: receiving a first random access channel (RACH) message from a user equipment (UE); and transmitting a second RACH message in a set of resource candidates that are outside of a physical downlink control channel (PDCCH) based at least in part on receiving the first RACH message.

Aspect 13: The method of aspect 12, wherein the transmitting of the second RACH message in the set of resource candidates outside of the PDCCH is based at least in part on information in the first RACH message, wherein the information indicates one or more of a RACH message type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions.

Aspect 14: The method of aspect 12 or 13, wherein the set of resource candidates are located in a physical downlink shared channel.

Aspect 15: The method of any of aspects 12-14, further comprising scheduling the second RACH message via a remaining minimum system information message or another system information message.

Aspect 16: The method of any of aspects 12-15, wherein the transmitting of the second RACH message in the set of resource candidates outside of the PDCCH is based at least in part on a determination that a signal measurement satisfies a threshold.

Aspect 17: The method of any of aspects 12-16, further comprising transmitting a RACH configuration that indicates that the second RACH message is to be transmitted in the set of resource candidates outside of the PDCCH based at least in part on a RACH type, a preamble sequence subset of the first RACH message, RACH occasions, or a subset of RACH occasions associated with the first RACH message.

Aspect 18: The method of aspect 17, wherein transmitting the RACH configuration includes transmitting the RACH configuration in a remaining minimum system information message or in another system information message.

Aspect 19: The method of any of aspects 12-18, further comprising transmitting information identifying the set of resource candidates to the UE.

Aspect 20: The method of aspect 19, wherein transmitting the information identifying the set of resource candidates includes transmitting the information identifying the set of resource candidates in a remaining minimum system information message or in another system information message.

Aspect 21: The method of any of aspects 12-20, wherein the set of resource candidates is based at least in part on a RACH occasion.

Aspect 22: The method of any of aspects 12-21, wherein the second RACH message includes control information for data on a physical downlink shared channel.

Aspect 23: An apparatus for wireless communication at a device, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of one or more aspects of aspects 1-22.

Aspect 20: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the memory and the one or more processors configured to perform the method of one or more aspects of aspects 1-22.

Aspect 21: An apparatus for wireless communication, comprising at least one means for performing the method of one or more aspects of aspects 1-22.

Aspect 22: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of one or more aspects of aspects 1-22.

Aspect 23: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions that, when executed by one or more processors of a device, cause the device to perform the method of one or more aspects of aspects 1-22.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software.

Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code—it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.