Method and apparatus for retransmitting random access messages in wireless communications

Abstract

Aspects described herein relate to determining a failure associated with reception by a base station of an initial transmission of a random access message transmitted by a UE in a two-step random access procedure; and configuring parameters of retransmission and / or retransmitting at least a portion of the random access message based on determining a failure condition associated with the reception of the random access message.

Description

[0001] This application is a divisional application of an invention patent application with an international application date of February 7, 2020 and application number 202080016015.0 (international application number PCT / US2020 / 017275) and entitled “Method and Apparatus for Retransmitting Random Access Messages in Wireless Communications”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims priority to provisional application No. 62 / 811,352, filed on February 27, 2019, entitled “TECHNIQUES FOR RETRANSMITTING RANDOMACCESS MESSAGES IN WIRELESS COMMUNICATIONS,” and U.S. patent application No. 16 / 783,985, filed on February 6, 2020, entitled “TECHNIQUES FOR RETRANSMITTING RANDOMACCESS MESSAGES IN WIRELESS COMMUNICATIONS,” the entire contents of which are expressly incorporated herein by reference. Background Art

[0004] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly to random access procedures.

[0005] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, etc. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

[0006] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. For example, the fifth generation (5G) wireless communication technology, which may be referred to as 5G New Radio (5G NR), is designed to expand and support diverse usage scenarios and applications relative to current mobile network generations. On the one hand, 5G communication technology may include: enhanced mobile broadband for human-centric use cases for accessing multimedia content, services, and data; ultra-reliable low latency communications (URLLC) with certain specifications on latency and reliability; and massive machine type communications, which may allow very large numbers of connected devices and the transmission of relatively small amounts of non-delay sensitive information.

[0007] In some wireless communication technologies, a user equipment (UE) may use a random access procedure to establish a connection with a base station. The random access procedure may typically include four steps of communicating messages between the UE and the base station in order to establish a connection. Recent proposals have introduced a two-step random access procedure, in which the UE transmits a first message including a random access preamble and a payload in a shared random access opportunity, and the base station receiving the first message may transmit a second message including a random access response (e.g., a response to the random access preamble) and contention resolution information. The first message may include two separate (e.g., in time) transmissions of the preamble and payload portions of the message, and the gap between the preamble transmission and the payload transmission is configurable. Summary of the invention

[0008] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be presented later.

[0009] According to one aspect, a method of wireless communication is provided. The method includes: determining, by a user equipment (UE), a failure associated with a base station receiving an initial transmission of a random access message transmitted by the UE in a two-step random access procedure; and transmitting, by the UE, a retransmission of at least a portion of the random access message to the base station based on determining the failure.

[0010] In another aspect, a method for wireless communication is provided. The method includes: receiving a random access message transmitted by a UE in a two-step random access procedure; determining whether the random access message is an initial transmission or a retransmission of the random access message; and decoding the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0011] In another aspect, an apparatus for wireless communication is provided, the apparatus comprising a transceiver, a memory configured to store instructions, and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to: determine a failure associated with a base station receiving an initial transmission of a random access message transmitted in a two-step random access procedure; and transmit a retransmission of at least a portion of the random access message to the base station based on determining the failure.

[0012] In another aspect, an apparatus for wireless communication is provided, the apparatus comprising a transceiver, a memory configured to store instructions, and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to: receive a random access message transmitted by a UE in a two-step random access procedure; determine whether the random access message is an initial transmission or a retransmission of the random access message; and decode the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0013] In another aspect, an apparatus for wireless communication is provided, comprising: a device for determining a failure associated with a base station's reception of an initial transmission of a random access message transmitted in a two-step random access procedure; and a device for transmitting a retransmission of at least a portion of the random access message to the base station based on determining the failure.

[0014] On the other hand, an apparatus for wireless communication is provided, comprising: a device for receiving a random access message transmitted by a UE in a two-step random access procedure from the UE; a device for determining whether the random access message is an initial transmission or a retransmission of the random access message; and a device for decoding the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0015] In another aspect, a computer-readable medium including code executable by one or more processors for wireless communication is provided. The code includes code for: determining, by a UE, a failure associated with reception by a base station of an initial transmission of a random access message transmitted by the UE in a two-step random access procedure; and transmitting, by the UE, a retransmission of at least a portion of the random access message to the base station based on determining the failure.

[0016] In another aspect, a computer-readable medium including code executable by one or more processors for wireless communication is provided. The code includes code for: receiving a random access message transmitted by a UE in a two-step random access procedure; determining whether the random access message is an initial transmission or a retransmission of the random access message; and decoding the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0017] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosed aspects will be described below in conjunction with the accompanying drawings, which are provided to illustrate rather than limit the disclosed aspects, wherein like reference numerals designate like elements, and wherein:

[0019] Figure 1 An example of a wireless communication system according to various aspects of the present disclosure is illustrated;

[0020] Figure 2 is a block diagram illustrating an example of a UE according to various aspects of the present disclosure;

[0021] Figure 3 is a block diagram illustrating an example of a base station according to various aspects of the present disclosure;

[0022] Figure 4 is a flow chart illustrating an example of a method for retransmitting a random access message according to various aspects of the present disclosure;

[0023] Figure 5 is a flow chart illustrating an example of a method for receiving a retransmission of a random access message according to various aspects of the present disclosure;

[0024] Figure 6 An example of allocating resources for transmission and / or retransmission of a random access message according to various aspects of the present disclosure is illustrated;

[0025] Figure 7 An example of a system for transmitting and / or retransmitting a random access message in accordance with various aspects of the present disclosure is illustrated; and

[0026] Figure 8 is a block diagram illustrating an example of a MIMO communication system including a base station and UEs according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0027] Now, various aspects are described with reference to the accompanying drawings. In the following description, for the purpose of explanation, numerous specific details are set forth to provide a thorough understanding of one or more aspects. However, it is apparent that such aspects can be practiced without these specific details.

[0028] The features described generally relate to retransmitting messages in a two-step random access procedure, but the concepts may also be applied to random access procedures with more or less than two steps. In a two-step random access procedure, a base station may broadcast a signal with parameters for establishing a connection with the base station. Such signals may include synchronization signal blocks (SSBs), system information blocks (SIBs), reference signals (RSs), and the like. A user equipment (UE) may receive the broadcast signal and may synchronize with a downlink from the base station, perform system information (SI) decoding and measurements, and the like. In addition, the UE may determine one or more random access opportunities for transmitting a random access message based on the parameters in the broadcast signal to establish a connection with the base station. When the UE desires to establish a connection with the base station, the UE may transmit a first message of the two-step random access procedure, which may include a preamble portion and a payload portion (e.g., wherein the payload portion may include physical uplink shared channel (PUSCH) data), and these portions may be transmitted as separated in time by transmission gaps. The base station may receive the first message (eg, as a preamble and a payload portion) and may transmit a response message to the UE, where the response message may include a random access response and / or contention resolution information.

[0029] As described, for example, there may be a transmission gap defined and used by the UE between the preamble portion and the payload portion of the first message. For example, the transmission gap may allow a timing adjustment (TA) for the first message transmission, where the TA may be unknown or outdated. In addition, for example, the transmission gap may allow different parameter sets, bandwidths, beam selections, power control schemes, sampling rates for the preamble and payload between the preamble portion and the payload portion, compatibility with a listen-before-talk (LBT) scheme (e.g., on a new radio (NR)-U interface), and the like. In addition, for example, the transmission of the preamble portion of the first message may include a guard time between each transmission (e.g., as defined by a wireless communication technology (such as NR) for any time division duplex (TDD) signal transmission). In this example, the transmission gap may be reduced in view of the increased guard time (compared to no guard time). In an example, the transmission gap may also be reduced subject to the constraint that the transition period between "the end of the ON power of the physical random access channel (PRACH)" and "the beginning of the ON power of the PUSCH" is not less than the length of the time mask. Additionally or alternatively, timing adjustments applied to the payload may shorten the effective transmission gap.

[0030] Additionally, the UE may define a transmit power time mask and use it when transmitting, wherein the mask may define one or more transient periods allowed between transmit OFF power symbols and transmit ON power symbols (e.g., transmit ON / OFF as defined in 3GPP Technical Specification (TS) 38.101), and / or between consecutive ON power transmissions with power variation or resource block (RB) hopping applied, etc. In the case where RB hopping is applied, for example, the transient period(s) associated with each RB set may be shared symmetrically. In any case, the transmission and / or retransmission of the random access message (e.g., and / or the transmission / retransmission of the preamble and payload portion of the first message) may be subject to the transmission gap and / or the transmit power time mask.

[0031] Various aspects described herein relate to facilitating retransmission of a random access message in a random access procedure (e.g., a two-step random access procedure). For example, retransmission of a first message (also referred to as "msgA") may be supported in a two-step random access procedure (e.g., a random access channel (RACH) procedure). For example, retransmitting a preamble and / or payload of the first message may utilize time / frequency / space diversity to improve performance. In another example, in order to facilitate coherent / incoherent combining by a base station (e.g., a gNB), the UE may repeat an initial transmission of the first message and / or may indicate whether the first message is new data or a retransmission by using one or more parameters in one or more signals transmitted by the UE. In addition, retransmission of at least a portion of the first message may be triggered by one or more events, beam management may be used to distinguish between retransmissions, and the like. In this regard, the UE may receive feedback for the first RACH message from the base station or otherwise detect that the base station did not receive at least a portion of the first RACH message (or did not transmit feedback for the at least a portion), and the UE may accordingly retransmit the first RACH message or a portion thereof to the base station to allow the base station to correctly receive and decode the first message.

[0032] The following will refer to Figure 1-8 The described features are presented in more detail.

[0033] As used in this application, the terms "component", "module", "system" and similar terms are intended to include computer-related entities, such as but not limited to hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, but not limited to, a process, a processor, an object, an executable, a thread of execution, a program, and / or a computer running on a processor. As an illustration, both an application running on a computing device and the computing device can be a component. One or more components may reside in a process and / or a thread of execution, and a component may be localized on a computer and / or distributed between two or more computers. In addition, these components can be executed from various computer-readable media on which various data structures are stored. These components can communicate by means of local and / or remote processes, such as according to a signal having one or more data packets, such as data from a component that interacts with a local system, another component in a distributed system, and / or interacts with other systems across a network such as the Internet.

[0034] The technology described herein can be used for various wireless communication systems, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are usually used interchangeably. A CDMA system can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA). CDMA2000 covers IS-2000, IS-95 and IS-856 standards. IS-2000 versions 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA systems can implement technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM TMRadio technologies such as UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and Advanced LTE (LTE-A) are new UMTS versions that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization called the "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein can be used for the systems and radio technologies mentioned above as well as for other systems and radio technologies, including cellular (e.g., LTE) communications on shared radio frequency spectrum bands. However, the following description describes an LTE / LTE-A system for example purposes, and LTE terminology is used in most of the following descriptions, but these techniques can also be applied to applications other than LTE / LTE-A (e.g., to fifth generation (5G) new radio (NR) networks or other next generation communication systems).

[0035] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, substitute, or add various procedures or components. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to some examples may be combined in other examples.

[0036] Various aspects or features will be presented in the form of systems that may include a number of devices, components, modules, and the like, etc. It should be understood and appreciated that the various systems may include additional devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. discussed in conjunction with the figures. Combinations of these approaches may also be used.

[0037] Figure 11 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) may include a base station 102, a UE 104, an evolved packet core (EPC) 160, and / or a 5G core (5GC) 190. The base station 102 may include a macro cell (a high power cellular base station) and / or a small cell (a low power cellular base station). The macro cell may include a base station. The small cell may include a femto cell, a pico cell, and a micro cell. In an example, the base station 102 may also include a gNB 180, as further described herein. In an example, some nodes of the wireless communication system may have a modem 240 and a communication component 242 for transmitting and / or retransmitting a random access message in a random access procedure. In addition, some nodes may have a modem 340 and a scheduling component 342 for scheduling or otherwise implementing the use of resources for transmitting and / or retransmitting a random access message, as described herein. Although UE 104 is shown as having a modem 240 and a communication component 242, and base station 102 / gNB 180 is shown as having a modem 340 and a scheduling component 342, this is an illustrative example, and substantially any node or node type may include a modem 240 and a communication component 242 and / or a modem 340 and a scheduling component 342 to provide the corresponding functionality described herein.

[0038] The base station 102 configured for 4G LTE (which may be collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 via a backhaul link 132 (e.g., using an S1 interface). The base station 102 configured for 5G NR (which may be collectively referred to as the Next Generation RAN (NG-RAN)) may interface with the 5GC 190 via a backhaul link 184. The base station 102 may perform, among other functions, one or more of the following functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. Base stations 102 may communicate with each other directly or indirectly (e.g., through EPC 160 or 5GC 190) over backhaul link 134 (e.g., using an X2 interface). Backhaul link 134 may be wired or wireless.

[0039] The base station 102 may communicate wirelessly with one or more UEs 104. Each base station 102 may provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group (which may be referred to as a closed subscriber group (CSG)). The communication link 120 between the base station 102 and the UE 104 may include an uplink (UL) (also known as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also known as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may be through one or more carriers. For each carrier allocated in a carrier aggregation of up to Yx MHz (e.g., for x component carriers) for transmission in the DL and / or UL direction, the base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth. These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0040] In another example, some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0041] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0042] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may boost the coverage of the access network and / or increase the capacity of the access network.

[0043] Whether a small cell 102' or a large cell (e.g., a macro base station), the base station 102 may include an eNB, a gB node (gNB), or other types of base stations. Some base stations (such as gNB 180) may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When gNB 180 operates in mmW or near mmW frequencies, gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW can be extended down to 3 GHz frequencies with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 102 referred to herein may include a gNB 180.

[0044] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may be in communication with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0045] 5GC 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. AMF 192 may be in communication with a unified data management (UDM) 196. AMF 192 may be a control node that processes signaling between UE 104 and 5GC 190. In general, AMF 192 may provide QoS flow and session management. User Internet Protocol (IP) packets (e.g., from one or more UEs 104) may be delivered via UPF 195. UPF 195 may provide UE IP address allocation for one or more UEs and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0046] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmission reception point (TRP), or some other suitable term. The base station 102 provides an access point to the EPC 160 or the 5GC 190 for the UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a health care device, an implant, a sensor / actuator, a display, or any other similar functional device. Some UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.). IoT UEs may include machine type communication (MTC) / enhanced MTC (eMTC, also known as Category (CAT)-M, Cat M1) UEs, NB-IoT (also known as CAT NB1) UEs, and other types of UEs. In the present disclosure, eMTC and NB-IoT may refer to future technologies that may evolve from or be based on these technologies. For example, eMTC may include FeMTC (further eMTC), eFeMTC (further enhanced eMTC), mMTC (massive MTC), etc., and NB-IoT may include eNB-IoT (enhanced NB-IoT), FeNB-IoT (further enhanced NB-IoT), etc. UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable term.

[0047] In one example, the scheduling component 342 can broadcast information related to transmitting a random access message, and the communication component 242 can process the broadcast information and transmit the random access message during the random access opportunity accordingly. The communication component 242 can additionally detect a trigger for retransmitting the random access message or at least a portion thereof. For example, the communication component 242 can receive a response message including feedback for the initial random access message, parameters for retransmitting the random access message, etc. from the scheduling component 342, and / or can detect that a response message is not received from the scheduling component 342 within a time period. The communication component 242 can retransmit at least a portion of the random access message accordingly, as further described herein.

[0048] Now go to Figure 2-8 , various aspects are described with reference to one or more components and one or more methods that can perform the actions or operations described herein, where various aspects in dashed lines may be optional. Figure 4-5 The operations described in the description are presented in a particular order and / or as being performed by example components, but it should be understood that the order of these actions and the components performing the actions may vary depending on the implementation. Moreover, it should be understood that the following actions, functions, and / or components described may be performed by a specially programmed processor, a processor executing specially programmed software or computer-readable media, or by any other combination of hardware components and / or software components capable of performing the described actions or functions.

[0049] refer to Figure 2 , an example of an implementation of UE 104 may include various components, some of which have been described above and are further described herein, including components such as one or more processors 212 and memory 216 in communication via one or more buses 244 and a transceiver 202, which may operate in conjunction with a modem 240 and / or a communication component 242 to transmit and / or retransmit random access messages.

[0050] In one aspect, the one or more processors 212 may include a modem 240 using one or more modem processors and / or may be part of the modem 240. Thus, various functions associated with the communication component 242 may be included in the modem 240 and / or the processor 212, and in one aspect, may be performed by a single processor, while in other aspects, different ones of these functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 212 may include any one or any combination of the following: a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with the transceiver 202. In other aspects, some of the features of the one or more processors 212 and / or the modem 240 associated with the communication component 242 may be performed by the transceiver 202.

[0051] In addition, the memory 216 can be configured to store local versions of data and / or applications 275 used herein, or the communication component 242 and / or one or more subcomponents thereof executed by the at least one processor 212. The memory 216 may include any type of computer-readable medium usable by a computer or the at least one processor 212, such as a random access memory (RAM), a read-only memory (ROM), a tape, a magnetic disk, an optical disk, a volatile memory, a non-volatile memory, and any combination thereof. In one aspect, for example, when the UE 104 is operating the at least one processor 212 to execute the communication component 242 and / or one or more subcomponents thereof, the memory 216 may be a non-transitory computer-readable storage medium storing one or more computer-executable codes defining the communication component 242 and / or one or more subcomponents thereof and / or data associated therewith.

[0052] The transceiver 202 may include at least one receiver 206 and at least one transmitter 208. The receiver 206 may include hardware, firmware, and / or software code executable by a processor for receiving data, the code including instructions and stored in a memory (e.g., a computer-readable medium). The receiver 206 may be, for example, a radio frequency (RF) receiver. In one aspect, the receiver 206 may receive signals transmitted by at least one base station 102. Additionally, the receiver 206 may process such received signals and may also obtain measurements of the signals, such as, but not limited to, Ec / Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. The transmitter 208 may include hardware, firmware, and / or software code executable by a processor for transmitting data, the code including instructions and stored in a memory (e.g., a computer-readable medium). Suitable examples of the transmitter 208 may include, but are not limited to, an RF transmitter.

[0053] In addition, in an aspect, the UE 104 may include an RF front end 288 that may operate in communication with the one or more antennas 265 and the transceiver 202 for receiving and transmitting radio transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by the UE 104. The RF front end 288 may be connected to the one or more antennas 265 and may include one or more low noise amplifiers (LNAs) 290, one or more switches 292, one or more power amplifiers (PAs) 298, and one or more filters 296 for transmitting and receiving RF signals.

[0054] In one aspect, the LNA 290 can amplify the received signal to a desired output level. In one aspect, each LNA 290 can have a specified minimum and maximum gain value. In one aspect, the RF front end 288 can use one or more switches 292 to select a particular LNA 290 and its specified gain value based on the desired gain value for a particular application.

[0055] In addition, for example, one or more PAs 298 can be used by the RF front end 288 to amplify the signal to obtain an RF output at a desired output power level. In one aspect, each PA 298 can have a specified minimum and maximum gain value. In one aspect, the RF front end 288 can use one or more switches 292 to select a particular PA 298 and its specified gain value based on the desired gain value for a particular application.

[0056] In addition, for example, one or more filters 296 can be used by the RF front end 288 to filter the received signal to obtain the input RF signal. Similarly, in one aspect, for example, a corresponding filter 296 can be used to filter the output from the corresponding PA 298 to produce an output signal for transmission. In one aspect, each filter 296 can be connected to a specific LNA 290 and / or PA 298. In one aspect, the RF front end 288 can use one or more switches 292 to select a transmit or receive path using a specified filter 296, LNA 290, and / or PA 298 based on a configuration as specified by the transceiver 202 and / or the processor 212.

[0057] As such, the transceiver 202 may be configured to transmit and receive wireless signals through one or more antennas 265 via the RF front end 288. In an aspect, the transceiver may be tuned to operate at a specified frequency so that the UE 104 may communicate, for example, with one or more base stations 102 or one or more cells associated with the one or more base stations 102. In an aspect, the modem 240 may configure the transceiver 202 to operate at a specified frequency and power level based on, for example, a UE configuration of the UE 104 and a communication protocol used by the modem 240.

[0058] In one aspect, modem 240 may be a multi-band-multi-mode modem that may process digital data and communicate with transceiver 202 so that digital data is sent and received using transceiver 202. In one aspect, modem 240 may be multi-band and configured to support multiple frequency bands for a specific communication protocol. In one aspect, modem 240 may be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, modem 240 may control one or more components (e.g., RF front end 288, transceiver 202) of UE 104 to enable transmission and / or reception of signals from the network based on a specified modem configuration. In one aspect, modem configuration may be based on the mode of the modem and the frequency band used. In another aspect, modem configuration may be based on UE configuration information associated with UE 104, such as provided by the network during cell selection and / or cell reselection.

[0059] In an aspect, communication component 242 can optionally include a failure detection component 252 for detecting that the base station did not properly receive the random access message, and / or a retransmission component 254 for retransmitting the random access message.

[0060] In one aspect, the processor(s) 212 may correspond to a Figure 8 Similarly, the memory 216 may correspond to one or more of the processors described in conjunction with the UE. Figure 8 The memory described by the UE in.

[0061] Reference Figure 3 , an example of an implementation of a base station 102 (e.g., base station 102 and / or gNB 180, as described above) may include various components, some of which have been described above, but also include components such as one or more processors 312 and memory 316 in communication via one or more buses 344 and a transceiver 302, which may operate in conjunction with a modem 340 and a scheduling component 342 to schedule or otherwise enable use of resources for transmitting and / or retransmitting random access messages.

[0062] The transceiver 302, receiver 306, transmitter 308, one or more processors 312, memory 316, application 375, bus 344, RF front end 388, LNA 390, switch 392, filter 396, PA 398, and one or more antennas 365 may be the same as or similar to corresponding components of UE 104 as described above, but are configured or otherwise programmed for base station operation rather than UE operation.

[0063] In an aspect, scheduling component 342 can optionally include a message receiving component 352 for receiving a random access message, and / or a feedback component 354 for indicating feedback for the random access message.

[0064] In one aspect, processor(s) 312 may correspond to a combination of Figure 8 Similarly, the memory 316 may correspond to one or more of the processors described in the base station in FIG. Figure 8 The memory described in the base station.

[0065] Figure 4 A flowchart illustrating an example of a method 400 for retransmitting a random access message. In one example, UE 104 may use Figure 1 and 2 One or more components described in the method 400 may be used to perform the functions described in the method 400.

[0066] In the method 400, optionally at block 402, the UE 104 may receive broadcast signaling indicating one or more parameters for transmitting and / or retransmitting a first random access message. In one aspect, the communication component 242 (e.g., in combination with the processor(s) 212, the memory 216, the transceiver 202, etc.) may receive broadcast signaling indicating one or more parameters for transmitting and / or retransmitting a first random access message from a base station (e.g., the base station 102). For example, the base station 102 may transmit broadcast signals on a known spectrum for a wireless communication technology (e.g., LTE, NR, etc.), which may include SSBs, SIBs, RSs, etc., as described. The SIBs may indicate various system information parameters, which may include information related to random access opportunities for transmitting random access messages. Additionally, in an example, the system information may include one or more parameters related to retransmitting the random access message, as further described herein (e.g., different opportunities for retransmission, preamble sequences, resources or modulation and coding schemes (MCS) to use, sequences or cyclic shift combinations used by demodulation reference signals (DM-RS), durations of transmission gaps to use, explicit indicators to use, etc. to retransmit the random access message). In an example, the communication component 242 may determine a random access opportunity for transmitting the random access message to the base station. In another example, the communication component 242 may additionally or alternatively determine parameters for retransmitting the random access message, as further described herein.

[0067] In method 400, optionally at block 404, UE 104 may transmit an initial transmission of a random access message to a base station. In one aspect, communication component 242 (e.g., in combination with processor(s) 212, memory 216, transceiver 202, etc.) may transmit an initial transmission of a random access message to a base station (e.g., base station 102). For example, communication component 242 may transmit the initial transmission in a random access opportunity determined based on received broadcast signaling. For example, the random access opportunity may be indicated based on one or more parameters in system information that specify a time period for transmitting the random access message (or parameters from which the time period may be determined). In an example, the random access message may be the first message in a two-step random access procedure, and the random access message may include a preamble portion and a payload portion, as described. For example, the preamble portion may be similar to a RACH preamble defined in LTE / NR, and the payload portion may include a PUSCH transmission of related PUSCH data. As described, each portion may be transmitted separately with a transmission gap and / or a guard time between the portions, and the transmission gap and / or the guard time may also be configured based on system information from a base station, in one example determined based on compliance with wireless communication technology (e.g., LTE / NR) according to instructions stored in memory 216, and the like.

[0068] In the method 400, at block 406, the UE 104 may determine a failure associated with a base station receiving an initial transmission of a random access message. In one aspect, the failure detection component 252 (e.g., in combination with the processor(s) 212, the memory 216, the transceiver 202, the communication component 242, etc.) may determine a failure associated with a base station (e.g., the base station 102) receiving an initial transmission of a random access message (e.g., the initial transmission in block 404). For example, the failure detection component 252 may determine the failure based on receiving feedback from the base station 102, based on detecting that feedback or a response message is not received within a threshold time period (e.g., after transmitting the random access message), and so on. In an example, the failure detection component 252 may determine the failure as a trigger for retransmitting the random access message or at least a portion thereof, as described herein. Additionally, for example, the failure detection component 252 may detect the failure as a failure to receive at least a portion of the random access message (e.g., a preamble portion or a payload portion), and / or may determine to retransmit the portion based on the detected failure.

[0069] In the event that failure is determined at block 406, optionally at block 408, the UE may monitor for a response message to the initial transmission for at least a period of time. In an aspect, failure detection component 252 (e.g., in combination with processor(s) 212, memory 216, transceiver 202, communication component 242, etc.) may monitor for a response message (e.g., from base station 102) for at least the period of time (e.g., a period of time measured from transmitting the initial transmission). In an example, failure detection component 252 may monitor for a response message on a resource associated with receiving a response message (e.g., a RACH or other channel and / or based on a radio network temporary identifier (RNTI) associated with a RACH procedure of UE 104). For example, failure detection component 252 may initialize a timer based on transmitting the initial transmission, and may determine that the initial transmission was not received if the timer expires before a response to the initial transmission is received. This may indicate a failure of the base station to receive the random access message and / or may trigger a retransmission of the random access message. Additionally, for example, failure detection component 252 can receive a response message that can indicate feedback for a random access message, which can also be a trigger for retransmitting the random access message (e.g., when the feedback indicates a negative acknowledgement (NACK) for the random access message). In one example, the response message can also indicate parameters for retransmitting the random access message.

[0070] In the event that a failure is determined at block 406, optionally at block 410, the UE 104 may receive an indication of beam management from the base station in response to the initial transmission. In one aspect, the failure detection component 252 (e.g., in combination with the processor(s) 212, the memory 216, the transceiver 202, the communication component 252, etc.) may receive an indication of beam management from the base station (e.g., the base station 102) in response to the initial transmission. In an example, the receipt of the indication may indicate a failure of the base station to receive the random access message and / or may trigger a retransmission of the random access message, where the retransmission may be based on beam management. For example, the indication may be received as a response message to the initial transmission of the random access message, and may be received when the base station is unable to decode at least a portion of the random access message or otherwise does not receive at least a portion of the random access message (e.g., a preamble portion or a payload portion). The indication of beam management may specify beam information for retransmitting the random access message, and the retransmitted random access message may use a different beam than the beam used to transmit the initial transmission (e.g., at block 404). For example, the beam management information may specify one or more parameters for beam switching from a beam used for initial transmission or beam refinement for a beam used for initial transmission.

[0071] For example, the initial transmission of the msgA preamble and payload may take into account different RACH beam configurations in association with the SSB beam settings that vary from cell to cell. The retransmission of the msgA preamble and payload may take into account a RACH beam switching / refinement that is different from the beam configuration in the first transmission. In one example, the base station may command beam switching in the downlink control information (DCI) of a response message (e.g., the response message is also referred to as "msgB") for retransmission of both the preamble and payload of msgA, or only the payload of msgA. Retransmission of the preamble may assist the base station in receive (RX) beam switching / refinement. Figure 6 An example is shown in .

[0072] Figure 6 An example of resources 600 that can be allocated for initial transmission and retransmission of a random access message is illustrated. For example, the resources 600 include a set of frequency / beam and time resources that can be allocated in a spectrum for wireless communication. The resources 600 include a resource allocation 602 for initial transmission of a preamble portion of a random access message, and a corresponding resource allocation 604 for transmission of a payload portion of the random access message (e.g., including a PUSCH and a corresponding DM-RS for demodulating a signal) (e.g., separated from the resource allocation 602 by a transmission gap). In an example, the communication component 242 can select these resources for transmitting the respective portions of the random access message based on the random access opportunity detected at the time of the resource allocation 602 and using a beam determined based on the detected SSB from the base station 102. In addition, in an example, the base station 102 can specify (e.g., in a SIB) parameters for determining the transmission gap and / or frequency / beam difference between the resource allocation 602 for the preamble portion and the resource allocation 604 for the payload portion.

[0073] In this example, failure detection component 252 can detect that base station 102 did not receive an initial transmission of the preamble portion or the payload portion, or can otherwise receive a response message from base station 102 with feedback indicating that at least a portion of the random access message was not received. The response message can specify an indication of beam management for retransmitting the random access message, which can include an indication of a beam to be used when retransmitting the random access message (such as the beam used to retransmit the preamble in resource allocation 606 and / or the beam used to retransmit the payload portion in resource allocation 608 as shown). Thus, in one example, the indication of beam management (which can be received in the response message) can include beam information for both the preamble and payload portions, or only one of these portions, and so on. In this example, in Figure 6In the embodiment of the present invention, a base station may receive a first preamble and may indicate feedback, and the UE may retransmit the preamble in a second preamble portion and corresponding two payload portions based on the feedback. For example, UE 104 may transmit a first payload portion associated with an initial transmission of a preamble based on a beam / frequency (e.g., resource set A, as depicted) indicated for the payload portion (e.g., in system information), and / or may transmit a second payload portion associated with a retransmission of a preamble based on a different beam / frequency (e.g., resource set B, as described) indicated for the retransmission of the payload portion (e.g., in system information, in a response message (which may include a response to the preamble or feedback for the preamble), etc.).

[0074] In the method 400, at block 412, the UE 104 may transmit a retransmission of at least a portion of the random access message to the base station based on the determination of the failure. In one aspect, the retransmission component 254 (e.g., in combination with the processor(s) 212, the memory 216, the transceiver 202, the communication component 242, etc.) may transmit a retransmission of at least a portion of the random access message to the base station (e.g., the base station 102) based on the determination of the failure. For example, the retransmission component 254 may retransmit at least the portion of the random access message to the base station by repeating at least the portion of the random access message (e.g., repeating the content of at least the portion of the random access message in a different signal, such as a redundant version). In this regard, for example, the repetition of at least the portion of the random access message may have the same transport block size as the initial transmission of at least the portion of the random access message. In this regard, as further described herein, the base station receiving at least the portion of the random access message may combine multiple received transmissions / retransmissions to improve the performance of the received signal.

[0075] In one example, in the event that a retransmission is transmitted at block 412, the UE 104 can optionally transmit the retransmission using a different beam than the initial transmission at block 414. In one aspect, the retransmission component 254 (e.g., in conjunction with the processor(s) 212, memory 216, transceiver 202, communication component 242, etc.) can transmit the retransmission using a different beam than the initial transmission. As described above with reference to Figure 6 As described, for example, the retransmission component 254 can determine a different beam configuration for retransmitting the random access message, which can be indicated in a response message to the initial transmission or otherwise determined based on feedback to the initial transmission of the random access message. Thus, in one example, the initial transmission and the retransmission can use different beams and / or corresponding frequency resources.

[0076] In another example, when transmitting a retransmission, the retransmission component 254 can retransmit the random access message based on one or more parameters indicated in the broadcast signaling from the base station 102. For example, the broadcast information can include one or more parameters indicating a mechanism to be used to distinguish a retransmission from an initial transmission so that the base station 102 can determine which of the retransmission and the initial transmission is received from the UE 104. In this regard, for example, in the case of transmitting a retransmission at block 412, the UE 104 can optionally generate the retransmission at block 416 to include an indication of the retransmission. In one aspect, the retransmission component 254 (e.g., in combination with the processor(s) 212, the memory 216, the transceiver 202, the communication component 242, etc.) can generate the retransmission to include an indication of the retransmission or the type of retransmission. For example, the retransmission component 254 can generate the retransmission based on one or more parameters that can indicate the retransmission, such as a preamble sequence, a random access opportunity, a resource allocation, an MCS, a sequence / cyclic shift combination for a DM-RS, a time duration of a transmission gap, an explicit indication (e.g., a new data indicator (NID) bit in a payload portion of a retransmission), etc.

[0077] Thus, in an example, the retransmitting component 254 and the communication component 242 can use one or more of the following: different preamble sequences for new data (i.e., initial transmission) and retransmissions (e.g., when both the preamble and the payload are retransmitted); different timings for new data and retransmissions (e.g., by puncturing available preamble / PUSCH timings); different resource allocations or MCSs for new data and retransmissions (e.g., by assigning different time / frequency offsets); different combinations of DM-RS sequences and cyclic shifts for new data and retransmissions; different configurations of transmission gaps between preambles and payloads for new data and retransmissions; and the like. In an example, as described, these options can be configured and indicated by system information and / or by dynamic signaling from the base station 102 (e.g., in broadcast signaling or msgB, etc.). When msgA is repeated or retransmitted, the base station 102 can collect and combine multiple copies of msgA to improve the performance of the received signal. In one example, it may be beneficial for the UE to explicitly indicate to the base station whether the UE's msgA carries new data or is a retransmission.

[0078] Figure 5 A flow chart illustrating an example of a method 500 for receiving a transmission and / or retransmission of a random access message. In one example, the base station 102 may use Figure 1 and 3 One or more components described in the method 500 may be used to perform the functions described in the method 500.

[0079] In method 500, optionally at block 502, base station 102 can broadcast one or more parameters related to retransmitting random access messages. In an aspect, scheduling component 352 (e.g., in combination with processor(s) 312, memory 316, transceiver 302, etc.) can broadcast one or more parameters related to retransmitting random access messages. For example, scheduling component 342 can transmit SSBs, SIBs, RSs, etc., which can include information for determining random access opportunities, beam information to be used when transmitting random access messages, parameters for retransmitting random access messages, etc., as described.

[0080] In method 500, at block 504, base station 102 may receive a random access message from a UE. In one aspect, message receiving component 352 (e.g., in combination with processor(s) 312, memory 316, transceiver 302, scheduling component 342, etc.) may receive a random access message from a UE (e.g., UE 104). For example, message receiving component 352 may receive the random access message in a random access opportunity defined in broadcast system information, based on one or more beams transmitted in an SSB, etc., as described. In an example, the random access message may include one or more portions (e.g., a preamble portion and / or a payload portion), and in an example, receiving the random access message may include receiving a portion of the random access message (e.g., a preamble portion). In an example, the random access message may be a first random access message (e.g., msgA) in a two-step RACH procedure, as described.

[0081] In the method 500, optionally at block 506, the base station 102 may transmit a response message to the random access message. In one aspect, the feedback component 354 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) may transmit a response message to the random access message (e.g., in the case where the base station 102 receives and / or decodes at least a preamble portion of the random access message). The response message may include a random access response and / or contention resolution information in one example (e.g., in the case where the random access message is successfully received), and may be the second random access message (e.g., msgB) in a two-step RACH in one example. In another example, in the case where the random access message (e.g., both parts) is not successfully received and / or decoded, the response message may include beam management information and / or feedback.

[0082] Thus, for example, in the case where a response message is transmitted at block 506, optionally at block 508, the base station 102 can indicate the beam management information in the response message. In one aspect, the feedback component 354 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) can indicate the beam management information in the response message. For example, the feedback component 354 can indicate one or more of the following: a beam to be used for transmitting a retransmission and / or information from which a beam can be derived, a time period during which the random access message is to be retransmitted, and the like, as described above with reference to Figure 6 Thus, in one example, the feedback component 354 can indicate different beams for the preamble portion and the payload portion of the random access message.

[0083] Additionally, for example, in the case where a response message is transmitted at block 506, optionally at block 510, the base station 102 can indicate feedback in the response message. In one aspect, the feedback component 354 (e.g., in conjunction with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) can indicate feedback (e.g., ACK / NACK feedback) in the response message. For example, the feedback can indicate whether an initial transmission of a random access message was correctly received and decoded, whether one or more portions of the initial transmission were received and decoded, and the like.

[0084] In method 500, optionally at block 512, base station 102 may determine a beam and / or associated resources on which to receive a random access message. In one aspect, message receiving component 352 (e.g., in conjunction with processor(s) 312, memory 316, transceiver 302, scheduling component 342, etc.) may determine a beam and / or associated resources on which to receive a random access message. For example, the beam and / or associated resources may indicate whether the random access message is an initial transmission or a retransmission; similarly, the transmission of the response message at 506 may indicate that the random access message is an initial transmission.

[0085] In any case, at block 514, the base station 102 may determine whether the random access message is an initial message or a retransmission. In one aspect, the message receiving component 352 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) may determine (e.g., at block 504) whether the random access message received from the UE is an initial message or a retransmission. For example, the message receiving component 352 may determine whether the message is an initial message or a retransmission based on one or more attributes of the random access message. As described, for example, the scheduling component 342 may broadcast parameters for retransmitting the random access message, such as different times for retransmission, preamble sequences, resources to use, sequence / cyclic shift combinations to use for DM-RS, transmission gaps to use, explicit indicators to use, etc., and the message receiving component 352 may determine whether the random access message is an initial message or a retransmission based on one of these attributes of the random access message. In another example, the feedback component 354 can specify beam management information for retransmitting the random access message, and thus, the message receiving component 352 can determine whether the random access message is an initial message or a retransmission based on the beam used to transmit the random access message.

[0086] In the event that it is determined at block 514 that the random access message is a retransmission, optionally at block 516, the base station 102 may combine the retransmission with the initial transmission and / or one or more other retransmissions. In one aspect, the message receiving component 352 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) may combine the retransmission with the initial transmission and / or one or more other retransmissions (e.g., to improve the performance of the received signal). As described, for example, the retransmission may be a repetition of the initial transmission of the random access message (e.g., using the same message and / or attributes, such as redundancy version, transport block size, etc.), which may allow the base station 102 to combine the transmissions to receive the message. Additionally, in one example, optionally at block 518, the base station 102 may modify the receive beam based at least in part on the retransmission. In one aspect, the message receiving component 352 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) may modify the receive beam based at least in part on the retransmission. For example, the message receiving component 352 can modify the receive beam to receive a retransmission of the random access message based on the beam management information indicated in the response message.

[0087] In any case, based on determining whether the random access message is an initial transmission or a retransmission, optionally at block 520, the base station 102 can decode the random access message based on determining whether the random access message is an initial transmission or a retransmission. In one aspect, the message receiving component 352 (e.g., in combination with the processor(s) 312, the memory 316, the transceiver 302, the scheduling component 342, etc.) can decode the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0088] Figure 7 An example of a system 700 for transmitting a random access message and / or providing feedback for a random access message in a two-step random access procedure is illustrated. Prior to starting a two-step RACH, the UE receives and processes SSB / SIB / RS from a serving gNB. For example, the system 700 includes a UE 104 that can transmit a random access message to a gNB 102 to request connection establishment with the gNB 102. In this example, the gNB 102 can transmit the SSB, SIB, and RS 702. The UE 104 can perform downlink synchronization, system information decoding, and / or measurements at 704. Based on data in a buffer of the UE 104, a UE identifier, and system information, the UE 104 can generate a message A (msgA) and transmit the message A (msgA) to the gNB on a RACH opportunity (RO) associated with a suitable SSB beam. The UE 104 can transmit msgA as a preamble portion 706 and a payload portion 708. After possibly receiving and processing the msgA preamble / payload, the gNB 102 may proceed as follows: if both preamble detection and payload decoding are successful at 710 and 712, the gNB 102 may generate message B (msgB) and transmit it to the two-step RACH UE 104 at 714, in which case msgB may include a contention resolution ID or an ACK for the msgA payload; if preamble detection is successful at 710 and payload decoding fails at 712, the gNB 102 may also generate msgB and transmit it to the UE 104, in which case msgB may include a random access preamble index (RAPID) or an ACK for the msgA preamble, and a DCI for retransmission of msgA, wherein the DCI may command retransmission of both the preamble and the payload, or only request retransmission of the payload; or if neither the preamble nor the payload is detected at 710 and 712, the gNB does not transmit msgB 714.

[0089] In this example, the UE 104 may monitor msgB 714 within the configured random access response (RAR) window after completing the transmission of msgA and start a timer. If the UE 104 successfully decodes msgB 704, where msgB 704 includes the remaining messages for the two-step random access procedure and / or an acknowledgement of receiving a random access message, the UE 104 does not need to retransmit msgA. If the UE 104 does not detect any msgB 714 when the timer expires, the UE 104 may retransmit in a configured random access opportunity using the configured beam management options (e.g., based on system information). If the UE 104 detects msgB with a negative acknowledgement for a payload and / or beam management information for transmitting a payload, the UE 104 may stop the timer and retransmit msgA according to the DCI and system information (e.g., by retransmitting the preamble portion 706 and / or the payload portion 708, which may also be indicated in msgB 714).

[0090] Figure 8 1 is a block diagram of a MIMO communication system 800 including a base station 102 and a UE 104. The MIMO communication system 800 may be explained with reference to Figure 1 The wireless communication access network 100 is described in detail. The base station 102 may be a reference Figure 1 Examples of various aspects of base station 102 are described. Base station 102 may be equipped with antennas 834 and 835, and UE 104 may be equipped with antennas 852 and 853. In MIMO communication system 800, base station 102 may be able to send data on multiple communication links simultaneously. Each communication link may be referred to as a "layer", and the "rank" of a communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system where base station 102 transmits two "layers", the rank of the communication link between base station 102 and UE 104 is 2.

[0091] At the base station 102, a transmit (Tx) processor 820 may receive data from a data source. The transmit processor 820 may process the data. The transmit processor 820 may also generate a control symbol or a reference symbol. The transmit MIMO processor 830 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, or reference symbols, where applicable, and may provide an output symbol stream to transmit modulators / demodulators 832 and 833. Each modulator / demodulator 832 to 833 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator / demodulator 832 to 833 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a DL signal. In one example, the DL signals from modulators / demodulators 832 and 833 may be transmitted via antennas 834 and 835, respectively.

[0092] UE 104 may be a reference Figure 1-2 Examples of various aspects of the UE 104 described. At the UE 104, the UE antennas 852 and 853 can receive DL signals from the base station 102 and can provide the received signals to the modulators / demodulators 854 and 855, respectively. Each modulator / demodulator 854 to 855 can condition (e.g., filter, amplify, downconvert, and digitize) the respective received signals to obtain input samples. Each modulator / demodulator 854 to 855 can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 856 can obtain the received symbols from the modulator / demodulators 854 and 855, perform MIMO detection on the received symbols where applicable, and provide detected symbols. The receive (Rx) processor 858 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide the decoded data for the UE 104 to the data output, and provide the decoded control information to the processor 880 or the memory 882.

[0093] Processor 880 may, in some cases, execute stored instructions to instantiate communication component 242 (eg, see Figure 1 and 2 ).

[0094] On the uplink (UL), at the UE 104, a transmit processor 864 may receive and process data from a data source. The transmit processor 864 may also generate reference symbols for a reference signal. The symbols from the transmit processor 864 may be precoded by a transmit MIMO processor 866, if applicable, further processed by modulators / demodulators 854 and 855 (e.g., for SC-FDMA, etc.), and transmitted to the base station 102 according to the communication parameters received from the base station 102. At the base station 102, the UL signals from the UE 104 may be received by antennas 834 and 835, processed by modulators / demodulators 832 and 833, detected by a MIMO detector 836, if applicable, and further processed by a receive processor 838. The receive processor 838 may provide decoded data to a data output and to the processor 840 or memory 842.

[0095] Processor 840 may in some cases execute stored instructions to instantiate scheduling component 342 (eg, see Figure 1 and 3 ).

[0096] The components of the UE 104 may be implemented individually or collectively with one or more ASICs adapted to perform some or all applicable functions in hardware. Each of the modules mentioned may be a device for performing one or more functions related to the operation of the MIMO communication system 800. Similarly, the components of the base station 102 may be implemented individually or collectively with one or more application-specific integrated circuits (ASICs) adapted to perform some or all applicable functions in hardware. Each of the components mentioned may be a device for performing one or more functions related to the operation of the MIMO communication system 800.

[0097] The above detailed description set forth above in conjunction with the accompanying drawings describes examples and does not represent the only examples that can be implemented or fall within the scope of the claims. The term "example" when used in this description means "used as an example, instance, or illustration", and does not mean "better than" or "better than other examples". This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0098] Information and signals may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, computer executable codes or instructions stored on computer-readable media, or any combination thereof.

[0099] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed with a specially programmed device, such as, but not limited to, a processor designed to perform the functions described herein, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The specially programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The specially programmed processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0100] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, each function may be stored as one or more instructions or codes on a non-transient computer-readable medium or transmitted by it. Other examples and implementations fall within the scope and spirit of the present disclosure and the appended claims. For example, due to the nature of software, each of the above functions may be implemented using software, hardware, firmware, hard wiring, or any combination thereof executed by a specially programmed processor. The features that implement the functions may also be physically located in various locations, including being distributed so that the various parts of the functions are implemented at different physical locations. In addition, as used herein (including in the claims), the "or" used in the enumeration of items followed by "at least one of" indicates a disjunctive enumeration, so that, for example, the enumeration of "at least one of A, B, or C" represents A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0101] Computer-readable media include both computer storage media and communication media, including any media that facilitates a computer program to be transferred from one place to another. Storage media can be any available media that can be accessed by a general or special-purpose computer. As an example and not limitation, computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, or any other media that can be used to carry or store the desired program code means in the form of instructions or data structures and can be accessed by a general or special-purpose computer or a general or special-purpose processor. Any connection is also properly referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, wherein disk usually reproduces data magnetically, while disc reproduces data optically with laser. Combinations of the above media are also included in the scope of computer-readable media.

[0102] The previous description of the disclosure is provided to enable those skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. In addition, although the elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is also contemplated unless explicitly stated to be limited to the singular. In addition, all or part of any aspect and / or embodiment may be used in conjunction with all or part of any other aspect and / or embodiment, unless otherwise stated. Thus, the disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

[0103] In the following, an overview of further examples is provided:

[0104] 1. A method for wireless communication, comprising:

[0105] determining, by a user equipment (UE), a failure associated with reception by a base station of an initial transmission of a random access message transmitted by the UE in a two-step random access procedure; and

[0106] A retransmission of at least a portion of the random access message is transmitted, by the UE to the base station based on determining the failure.

[0107] 2. The method of Example 1, wherein the retransmission is a repetition of the random access message.

[0108] 3. A method as described in any of Examples 1 or 2, wherein the retransmission is transmitted on a different beam than the initial transmission.

[0109] 4. The method as described in any one of Examples 1 to 3 further includes: receiving an indication of beam management information from a base station in response to an initial transmission, the beam management information including beam management signaling for beam switching or beam refinement.

[0110] 5. A method as described in Example 4, wherein the indication of beam management information is part of downlink control information received from the base station.

[0111] 6. A method as described in any of Examples 4 or 5, wherein the indication further specifies the portion of the random access message to be retransmitted as including at least one of a preamble portion of the random access message and / or a payload portion of the random access message.

[0112] 7. A method as described in any one of Examples 4 to 6, wherein the indication further specifies a first beam for retransmitting a preamble portion of a random access message and a second beam for retransmitting a payload portion of the random access message.

[0113] 8. A method as described in any one of Examples 1 to 7, wherein the retransmission of the portion of the random access message includes an indication of a retransmission type to the UE.

[0114] 9. A method as described in Example 8, wherein the indication of the retransmission type includes configuring at least one of the following: a preamble sequence different from the preamble sequence used for initial transmission, a timing different from the timing used for initial transmission, a resource allocation or modulation and coding scheme (MCS) different from the resource allocation or MCS used for initial transmission, a sequence and / or cyclic shift combination used by a demodulation reference signal different from the sequence and / or cyclic shift combination used for initial transmission, a transmission gap between the preamble portion and the payload portion different from the transmission gap used for initial transmission, or including a bit in the payload portion of the retransmission indicating a retransmission rather than a new data transmission.

[0115] 10. The method as described in any of Examples 8 or 9 further includes: determining a mechanism for including the indication and the configuration of the retransmission based on at least one of broadcast signaling or dynamic signaling from a base station.

[0116] 11. The method as described in any one of Examples 1 to 10 further includes: monitoring a response message from a base station to an initial transmission of a random access message as defined in a two-step random access procedure, wherein determining the failure includes: determining that no response message is received within a time period after the initial transmission.

[0117] 12. A method as described in any one of Examples 1 to 11, wherein the random access message includes a preamble, a payload including a demodulation reference signal and a physical uplink shared channel, and a configurable transmission gap.

[0118] 13. A method for wireless communication, comprising:

[0119] receiving, from a user equipment (UE), a random access message transmitted by the UE in a two-step random access procedure;

[0120] determining whether the random access message is an initial transmission or a retransmission of the random access message; and

[0121] The random access message is decoded based on determining whether the random access message is an initial transmission or a retransmission.

[0122] 14. The method of Example 13, wherein determining comprises determining that the random access message is a retransmission based on one or more parameters associated with the retransmission.

[0123] 15. The method of Example 14, wherein decoding the random access message is based at least in part on combining the retransmission with the initial transmission and / or one or more other retransmissions of the random access message.

[0124] 16. A method as described in any of Examples 14 or 15, wherein the one or more parameters associated with the retransmission include at least one of: a preamble sequence, a random access timing, a resource allocation or a modulation and coding scheme (MCS), a sequence and / or cyclic shift combination for a demodulation reference signal, a time duration of a transmission gap between a preamble portion and a payload portion, or a bit indicating a retransmission rather than a new data transmission.

[0125] 17. The method of any one of Examples 14 to 16, further comprising: transmitting a configuration of the one or more parameters to be used when retransmitting the random access message.

[0126] 18. The method of Example 17, wherein transmitting the configuration comprises transmitting a broadcast signal indicating the one or more parameters.

[0127] 19. A method as described in any of Examples 13 to 18, wherein the determination includes: determining that the random access message is a retransmission based at least in part on receiving an initial transmission and transmitting a response message to the initial transmission, wherein the response message indicates a beam to be used when transmitting the retransmission.

[0128] 20. The method of Example 19, wherein determining that the random access message is a retransmission is based at least in part on determining a beam and / or associated resources based on which the random access message was received.

[0129] 21. A method as described in any of Examples 19 or 20, wherein the response message indicates a first beam to be used when retransmitting a preamble portion of the random access message and a second beam to be used when retransmitting a payload portion of the random access message.

[0130] 22. The method as described in any one of Examples 19 to 21 further includes: modifying a receiving beam of a base station receiving the random access message based at least in part on the retransmission.

[0131] 23. The method of any one of Examples 13 to 22, further comprising: transmitting a response message to the initial transmission in a two-step random access procedure.

[0132] 24. The method of Example 23, wherein the response message indicates feedback for receiving at least a portion of the initial transmission.

[0133] 25. The method of Example 24, further comprising: receiving a retransmission of the random access message based at least in part on the feedback.

[0134] 26. An apparatus for wireless communication, comprising:

[0135] Transceiver;

[0136] a memory configured to store instructions; and

[0137] one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to:

[0138] Determine the initial transmission of a random access message transmitted by the base station in a two-step random access procedure

[0139] Failures associated with the receipt of input; and

[0140] A retransmission of at least a portion of the random access message is transmitted to the base station based on determining the failure.

[0141] 27. The apparatus of Example 26, wherein the retransmission is a repetition of the random access message.

[0142] 28. An apparatus as described in any of Examples 26 or 27, wherein the one or more processors are configured to: transmit the retransmission on a different beam than the initial transmission.

[0143] 29. An apparatus as described in any of Examples 26 to 28, wherein the one or more processors are further configured to: receive an indication of beam management information from a base station in response to an initial transmission, the beam management information including beam management signaling for beam switching or beam refinement.

[0144] 30. An apparatus as described in Example 29, wherein the indication of beam management information is part of downlink control information received from a base station.

[0145] 31. An apparatus as described in any of Examples 29 or 30, wherein the indication further specifies the portion of the random access message to be retransmitted as including at least one of a preamble portion of the random access message and / or a payload portion of the random access message.

[0146] 32. An apparatus as described in any one of Examples 29 to 31, wherein the indication further specifies a first beam for retransmitting a preamble portion of a random access message and a second beam for retransmitting a payload portion of the random access message.

[0147] 33. An apparatus as described in any of Examples 26 to 32, wherein the retransmission of the portion of the random access message includes an indication of a retransmission type.

[0148] 34. An apparatus as described in Example 33, wherein the indication of the retransmission type includes configuring at least one of: a preamble sequence different from the preamble sequence used for the initial transmission, a timing different from the timing used for the initial transmission, a resource allocation or modulation and coding scheme (MCS) different from the resource allocation or MCS used for the initial transmission, a sequence and / or cyclic shift combination used by a demodulation reference signal different from the sequence and / or cyclic shift combination used for the initial transmission, a transmission gap between the preamble portion and the payload portion different from the transmission gap used for the initial transmission, or including a bit in the payload portion of the retransmission indicating a retransmission rather than a new data transmission.

[0149] 35. An apparatus as described in any of Examples 33 or 34, wherein the one or more processors are further configured to: determine a mechanism for including the indication and configuration for retransmission based on at least one of broadcast signaling or dynamic signaling from a base station.

[0150] 36. An apparatus as described in any of Examples 26 to 35, wherein the one or more processors are further configured to: monitor a response message from a base station to an initial transmission of a random access message as defined in a two-step random access procedure, wherein the one or more processors are configured to: determine the failure at least in part by determining that no response message is received within a time period after the initial transmission.

[0151] 37. An apparatus as described in any one of Examples 26 to 36, wherein the random access message includes a preamble, a payload including a demodulation reference signal and a physical uplink shared channel, and a configurable transmission gap.

[0152] 38. An apparatus for wireless communication, comprising:

[0153] Transceiver;

[0154] a memory configured to store instructions; and

[0155] one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to:

[0156] receiving, from a user equipment (UE), a random access message transmitted by the UE in a two-step random access procedure;

[0157] determining whether the random access message is an initial transmission or a retransmission of the random access message; and decoding the random access message based on determining whether the random access message is the initial transmission or the retransmission.

[0158] 39. The apparatus of Example 38, wherein the one or more processors are configured to determine that the random access message is a retransmission based on one or more parameters associated with the retransmission.

[0159] 40. An apparatus as described in Example 39, wherein the one or more processors are further configured to: decode the random access message at least in part by combining the retransmission with the initial transmission and / or one or more other retransmissions of the random access message.

[0160] 41. An apparatus as described in any of Examples 39 or 40, wherein the one or more parameters associated with the retransmission include at least one of: a preamble sequence, a random access timing, a resource allocation or a modulation and coding scheme (MCS), a sequence and / or cyclic shift combination for a demodulation reference signal, a time duration of a transmission gap between a preamble portion and a payload portion, or a bit indicating a retransmission rather than a new data transmission.

[0161] 42. An apparatus as described in any of Examples 39 to 41, wherein the one or more processors are further configured to: transmit a configuration of the one or more parameters to be used when retransmitting a random access message.

[0162] 43. An apparatus as described in Example 42, wherein the one or more processors are configured to: transmit the configuration in a broadcast signal indicating the one or more parameters.

[0163] 44. An apparatus as described in any of Examples 38 to 43, wherein the one or more processors are configured to: determine that the random access message is a retransmission based at least in part on receiving an initial transmission and transmitting a response message to the initial transmission, wherein the response message indicates a beam to be used when transmitting the retransmission.

[0164] 45. An apparatus as described in Example 44, wherein the one or more processors are configured to: determine that the random access message is a retransmission based at least in part on determining the beam and / or associated resources on which the random access message is received.

[0165] 46. ​​An apparatus as described in any of Examples 44 or 45, wherein the response message indicates a first beam to be used when retransmitting a preamble portion of a random access message and a second beam to be used when retransmitting a payload portion of the random access message.

[0166] 47. An apparatus as described in any of Examples 44 to 46, wherein the one or more processors are further configured to: modify a receive beam of a base station that receives a random access message based at least in part on the retransmission.

[0167] 48. An apparatus as described in any of Examples 38 to 47, wherein the one or more processors are further configured to: transmit a response message to an initial transmission in a two-step random access procedure.

[0168] 49. The apparatus of Example 48, wherein the response message indicates feedback for receiving at least a portion of the initial transmission.

[0169] 50. The apparatus of Example 49, wherein the one or more processors are further configured to receive a retransmission of the random access message based at least in part on the feedback.

[0170] 51. A device for wireless communication, comprising:

[0171] means for determining a failure associated with reception by a base station of an initial transmission of a random access message transmitted in a two-step random access procedure; and

[0172] means for transmitting, to the base station, a retransmission of at least a portion of the random access message based on determining the failure.

[0173] 52. The apparatus of Example 51, wherein the retransmission is a repetition of the random access message.

[0174] 53. An apparatus as described in any of Examples 51 or 52, wherein the means for transmitting transmits the retransmission on a different beam than the initial transmission.

[0175] 54. A device for wireless communication, comprising:

[0176] means for receiving from a user equipment (UE) a random access message transmitted by the UE in a two-step random access procedure;

[0177] means for determining whether the random access message is an initial transmission or a retransmission of the random access message; and

[0178] Means for decoding the random access message based on determining whether the random access message is an initial transmission or a retransmission.

[0179] 55. The apparatus of Example 54, wherein the means for determining determines that the random access message is a retransmission based on one or more parameters associated with the retransmission.

[0180] 56. An apparatus as described in Example 55, wherein the means for decoding decodes the random access message based at least in part on combining the retransmission with the initial transmission and / or one or more other retransmissions of the random access message.

[0181] 57. A computer readable medium comprising code executable by one or more processors for wireless communication, the code comprising code for:

[0182] determining, by a user equipment (UE), a failure associated with reception by a base station of an initial transmission of a random access message transmitted by the UE in a two-step random access procedure; and

[0183] A retransmission of at least a portion of the random access message is transmitted, by the UE to the base station based on determining the failure.

[0184] 58. The computer-readable medium of Example 57, wherein the retransmission is a repetition of the random access message.

[0185] 59. A computer-readable medium as described in any of Examples 57 or 58, wherein the code for transmitting transmits the retransmission on a different beam than the initial transmission.

[0186] 60. A computer readable medium comprising code executable by one or more processors for wireless communication, the code comprising code for:

[0187] receiving, from a user equipment (UE), a random access message transmitted by the UE in a two-step random access procedure;

[0188] determining whether the random access message is an initial transmission or a retransmission of the random access message; and

[0189] The random access message is decoded based on determining whether the random access message is an initial transmission or a retransmission.

[0190] 61. The computer-readable medium of example 60, wherein the code for determining determines that the random access message is a retransmission based on one or more parameters associated with the retransmission.

[0191] 62. The computer-readable medium of example 61, wherein the code for decoding decodes the random access message based at least in part on combining the retransmission with an initial transmission and / or one or more other retransmissions of the random access message.

Claims

1. A method for wireless communication, comprising: determining, by a user equipment UE, a failure associated with reception by a base station of an initial transmission of a random access message transmitted by the UE in a two-step random access procedure; receiving a response from the base station in response to the initial transmission indicating the failure; as well as A retransmission of at least a portion of the random access message is transmitted, by the UE to the base station in a beam switched based on the response based on determining the failure.

2. The method of claim 1, wherein: The retransmission is a repetition of the random access message.

3. The method of claim 1, wherein: The retransmission is transmitted on a different beam than the initial transmission.

4. The method of claim 1, further comprising: An indication of beam management information is received from the base station in response to the initial transmission, the beam management information comprising beam management signaling for beam switching or beam refinement.

5. The method of claim 4, wherein: The indication of beam management information is part of downlink control information received from the base station.

6. The method of claim 4, wherein: The indication further specifies the portion of the random access message to be retransmitted as including at least one of a preamble portion of the random access message and / or a payload portion of the random access message.

7. The method of claim 4, wherein: The indication further specifies a first beam for retransmitting a preamble portion of the random access message and a second beam for retransmitting a payload portion of the random access message.

8. The method of claim 1, wherein: The retransmission of the portion of the random access message includes an indication of a retransmission type to the UE.

9. The method of claim 8, wherein: The indication of the retransmission type includes configuring at least one of: a preamble sequence different from the preamble sequence used for the initial transmission, a timing different from the timing used for the initial transmission, a resource allocation or MCS different from the resource allocation or modulation and coding scheme MCS used for the initial transmission, a sequence and / or cyclic shift combination used by a demodulation reference signal different from the sequence and / or cyclic shift combination used for the initial transmission, a transmission gap between a preamble part and a payload part different from the transmission gap used for the initial transmission, or including a bit in the payload part of the retransmission indicating a retransmission rather than a new data transmission.

10. The method of claim 8, further comprising: A mechanism for including the indication and configuration of the retransmission is determined based on at least one of broadcast signaling or dynamic signaling from the base station.

11. The method of claim 1, further comprising: Monitoring a response message from the base station to the initial transmission of the random access message as defined in the two-step random access procedure, wherein determining the failure comprises determining that the response message is not received within a time period after the initial transmission.

12. The method of claim 1, wherein: The random access message includes a preamble, a payload including a demodulation reference signal and a physical uplink shared channel, and a configurable transmission gap.

13. An apparatus for wireless communication, comprising: Transceiver; a memory configured to store instructions; as well as one or more processors communicatively coupled to the transceiver and the memory, wherein the one or more processors are configured to: determining a failure associated with reception by a base station of an initial transmission of a random access message transmitted in a two-step random access procedure; receiving a response from the base station in response to the initial transmission indicating the failure; as well as Transmitting a retransmission of at least a portion of the random access message to the base station in a beam switched based on the response based on determining the failure.

14. The device of claim 13, wherein: The retransmission is a repetition of the random access message.

15. The device of claim 13, wherein: The one or more processors are configured to transmit the retransmission on a different beam than the initial transmission.

16. The device of claim 13, wherein: The one or more processors are further configured to receive an indication of beam management information from the base station in response to the initial transmission, the beam management information comprising beam management signaling for beam switching or beam refinement.

17. The device of claim 16, wherein: The indication of beam management information is part of downlink control information received from the base station.

18. The device of claim 16, wherein: The indication further specifies the portion of the random access message to be retransmitted as including at least one of a preamble portion of the random access message and / or a payload portion of the random access message.

19. The device of claim 16, wherein: The indication further specifies a first beam for retransmitting a preamble portion of the random access message and a second beam for retransmitting a payload portion of the random access message.

20. The device of claim 13, wherein: The retransmission of the portion of the random access message includes an indication of a retransmission type.

21. The device of claim 20, wherein: The indication of the retransmission type includes configuring at least one of: a preamble sequence different from the preamble sequence used for the initial transmission, a timing different from the timing used for the initial transmission, a resource allocation or MCS different from the resource allocation or modulation and coding scheme MCS used for the initial transmission, a sequence and / or cyclic shift combination used by a demodulation reference signal different from the sequence and / or cyclic shift combination used for the initial transmission, a transmission gap between a preamble part and a payload part different from the transmission gap used for the initial transmission, or including a bit in the payload part of the retransmission indicating a retransmission rather than a new data transmission.

22. The device of claim 20, wherein: The one or more processors are further configured to determine a mechanism for including the indication and configuration of the retransmission based on at least one of broadcast signaling or dynamic signaling from the base station.

23. The device of claim 13, wherein: The one or more processors are further configured to monitor a response message from the base station to the initial transmission of the random access message as defined in the two-step random access procedure, wherein the one or more processors are configured to determine the failure at least in part by determining that the response message is not received within a time period after the initial transmission.

24. The apparatus of claim 13, wherein: The random access message includes a preamble, a payload including a demodulation reference signal and a physical uplink shared channel, and a configurable transmission gap.

25. A device for wireless communication, comprising: Apparatus for performing the method according to any one of claims 1-12.

26. A computer readable medium having stored thereon code for wireless communication, the code being executable by one or more processors to cause the one or more processors to perform the method of any one of claims 1-12.

Images