Random access channel procedure with external assistance

Abstract

A low complexity user equipment (UE) can communicate with another UE (e.g., with a high-end UE or a more capable UE) via a device-to-device communication link (e.g., via a sidelink), and the low complexity UE can utilize the device-to-device link to improve (e.g., simplify, speed up, etc.) a random access procedure performed by the low complexity UE. For example, the low complexity UE can request a contention-free random access (CFRA) resource via the device-to-device link with another UE. Another device (e.g., another UE in device-to-device communication with the low complexity UE) can receive the request from the low complexity UE and forward the request to the network (e.g., to a base station). The network can then configure the CFRA resource for the low complexity UE. Upon receiving the CFRA configuration, the low complexity UE can perform a random access procedure (e.g., a CFRA procedure) with the network (e.g., with the base station) accordingly.

Description

[0001] BACKGROUND

[0002] The following relates generally to wireless communications, and more specifically to out-of-band assisted random access channel procedures.

[0003] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems can be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple- access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which can be referred to as New Radio (NR) systems. These systems can employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communications system can include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which can be otherwise known as user equipment (UE).

[0004] Some wireless communications systems can support one or more random access procedures (e.g., a UE can perform a random access procedure during initial access to establish a connection with a network). The random access procedure can involve a series of handshake messages exchanged between a UE and a base station using random access time / frequency resources. Random access procedures can include a contention-based random access (CBRA) procedure in which a device must contend for the channel before attempting access and a contention-free random access (CFRA) procedure in which resources are preconfigured for a device. In some aspects, a random access procedure can be performed on a physical random access channel (PRACH) and can involve exchanging one or more random access channel (RACH) signals (e.g., RACH message 1 (msgl), RACH message 2 (msg2), and so on).

[0005] SUMMARY

[0006] The described techniques relate to improved methods, systems, devices, and apparatuses that support random access channel procedures with out-of-band assistance. Generally, the described techniques provide for improved random access procedures for reduced capability user equipment (UEs) such as, for example, low complexity UEs, low-end UEs, new radio (NR) light devices, Internet of Things (IoT) devices, and so on. According to some aspects, a low complexity UE can utilize out-of-band assistance from other UEs (e.g., via device-to-device communications) to improve random access procedures for low complexity UEs.

[0007] For example, a low complexity UE can communicate with another UE (e.g., with a high-end UE or more capable UE) via a device-to-device communication link (e.g., via a sidelink), and the low complexity UE can leverage the device-to-device link to improve (e.g., simplify, speed up, etc.) a random access procedure performed by the low complexity UE. As such, a low complexity UE can request a contention-free random access (CFRA) resource via a device-to-device link with another UE, in accordance with the techniques described herein. In some cases, the request can include a reason for the request (e.g., a condition of the low complexity UE), a preferred CFRA resource, and / or the like. Another device (e.g., another UE in device-to-device communication with the low complexity UE) can receive the request from the low complexity UE and forward the request to the network (e.g., to a base station). The network can then configure a CFRA resource for the low complexity UE, and can communicate the CFRA configuration directly to the low complexity UE, can communicate the CFRA configuration to the low complexity UE through another UE (e.g., through some other UE to forward to the low complexity UE), and / or the like. Upon receiving the CFRA configuration, the low complexity UE can perform a random access procedure (e.g., a CFRA procedure) with the network (e.g., with a base station) accordingly.

[0008] A method of wireless communication is described at a first UE. The method can include transmitting, to a second UE, a request for contention-free random access resources based on a low power capability of the first UE, receiving a contention-free random access configuration based on the request, and performing a contention-free random access procedure based on the received contention-free random access configuration.

[0009] An apparatus for wireless communication at a first UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to transmit, to a second UE, a request for contention-free random access resources based on a low power capability of the first UE, receive a contention-free random access configuration based on the request, and perform a contention-free random access procedure based on the received contention-free random access configuration.

[0010] Another apparatus for wireless communication at a first UE is described. The apparatus can include means for transmitting, to a second UE, a request for contention-free random access resources based on a low power capability of the first UE, receiving a contention-free random access configuration based on the request, and performing a contention-free random access procedure based on the received contention-free random access configuration.

[0011] A non-transitory computer-readable medium storing code for wireless communications at a first UE is described. The code can include instructions executable by a processor to transmit, to a second UE, a request for contention- free random access resources based on a low power capability of the first UE, receive a contention-free random access configuration based on the request, and perform a contention-free random access procedure based on the received contention-free random access configuration.

[0012] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining to request the contention-free random access resources based on a contention-based random access configuration of the first UE, a low power capability of the first UE, a capability of the first UE to communicate with the second UE on a device-to-device link, or some combination thereof, where the request can be transmitted based on the determination. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the request includes an indication of the contention-based random access configuration of the first UE, the low power capability of the first UE, the capability of the first UE to communicate with the second UE on the device-to-device link, or some combination thereof.

[0013] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the contention-free random access configuration can include operations, features, means, or instructions for receiving the contention-free random access configuration from the second UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the contention-free random access configuration can include operations, features, means, or instructions for receiving the contention-free random access configuration from the base station. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the contention-free random access configuration can include operations, features, means, or instructions for receiving the contention-free random access configuration from a third UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the request includes an identifier of the first UE, and the contention-free random access configuration can be received by the first UE based on the identifier.

[0014] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the identifier comprises a cell radio network temporary identifier of the first UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the contention- free random access configuration comprises a random access time resource, a random access frequency resource, a random access preamble, a random access occasion, or some combination thereof. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the contention- free random access configuration comprises one or more synchronization signal block indexes, one or more channel state information reference signal resource identifications, or some combination thereof, associated with the random access time resource, the random access frequency resource, the random access preamble, the random access occasion, or some combination thereof. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a preferred random access resource, a preferred random access preamble, a preferred random access occasion, or some combination thereof, where the request comprises an indication of the preferred random access resource, the preferred random access preamble, the preferred random access occasion, or some combination thereof.

[0015] Some examples of the method, apparatuses, and non-transitory computer- readable medium described herein can further include operations, features, means, or instructions for determining one or more preferred synchronization signal block indexes, one or more channel state information reference signal resource identifications, or some combination thereof, associated with the preferred random access resource, the preferred random access preamble, the preferred random access occasion, or some combination thereof, where the request comprises the determined one or more preferred synchronization signal block indexes, the one or more channel state information reference signal resource identifications, or some combination thereof. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining whether the contention- free random access resource can be for a four-step random access channel procedure, a two-step random access channel procedure, or both, where the request comprises an indication of the determination.

[0016] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the contention-free random access configuration includes an indication of whether the contention-free random access configuration can be for a four-step random access channel procedure, a two-step random access channel procedure, or both. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, performing the contention-free random access procedure with the base station can include operations, features, means, or instructions for transmitting a random access channel preamble at a random access occasion based on the received contention-free random access configuration. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining to request the contention-free random access resource based on a condition of the first UE, where the request includes an indication of the condition.

[0017] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the condition includes an initial access from an idle mode condition, a radio resource connection reestablishment procedure for radio link failure recovery, a downlink data arrival during a connected mode when uplink synchronization can be lost without contention-free random access possibly being configured, an uplink data arrival during a connected mode when uplink synchronization can be lost without contention-free random access possibly being configured, an uplink data arrival during a connected mode when a physical uplink control channel resource for a scheduling request can not be available, a scheduling request failure, a request by radio resource control upon a synchronization reconfiguration for handover without contention-free random access possibly being configured for handover, a transition from a first UE non-active mode, establishing time alignment for a secondary timing advance group, a request for other system information, a beam failure recovery without contention-free random access possibly being configured for beam failure recovery, or some combination thereof.

[0018] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the request can be transmitted on a device-to-device link with a second UE.

[0019] A method of wireless communication is described. The method can include receiving, from a first UE, a request for contention-free random access resources over a device-to-device link based on a low power capability of the first UE, and transmitting the request to a base station based on the received request.

[0020] An apparatus for wireless communication at a second UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to receive, from a first UE, a request for contention- free random access resources over a device-to-device link based on a low power capability of the first UE, and transmit the request to a base station based on the received request.

[0021] Another apparatus for wireless communication at a second UE is described. The apparatus can include means for receiving, from a first UE, a request for contention- free random access resources over a device-to-device link based on a low power capability of the first UE, and transmitting the request to a base station based on the received request.

[0022] A non-transitory computer-readable medium storing code for wireless communication at a second UE is described. The code can include instructions executable by a processor to receive, from a first UE, a request for contention- free random access resources over a device-to-device link based on a low power capability of the first UE, and transmit the request to a base station based on the received request.

[0023] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving, from the base station, a contention-free random access configuration based on the transmitted request, and transmitting the contention-free random access configuration to the first UE over the device-to-device link. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the request includes an identifier of the first UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the identifier of the first UE includes a cell radio network temporary identifier of the first UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the contention-free random access configuration includes a random access time resource, a random access frequency resource, a random access preamble, a random access occasion, or some combination thereof.

[0024] In some examples of the methods, apparatuses (devices), and non-transient computer-readable media described herein, the contention-free random access configuration includes: one or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof. In some examples of the methods, apparatuses (devices), and non-transient computer-readable media described herein, the contention-free random access configuration includes indications as to whether the contention-free random access configuration may be for a four-step random access channel procedure, a two-step random access channel procedure, or both.

[0025] In some examples of the methods, apparatuses (devices), and non-transient computer-readable media described herein, the request includes an indication of a contention-based random access configuration for the first UE, a low-power capability of the first UE, the ability of the first UE to communicate with a second UE on a device-to-device link, or a combination thereof. In some examples of the methods, apparatuses (devices), and non-transient computer-readable media described herein, the request includes: an indication of a preferred random access resource for the first UE, a preferred random access preamble for the first UE, a preferred random access timing for the first UE, or a combination thereof. In some examples of the methods, apparatuses (devices), and non-transient computer-readable media described herein, the request includes: one or more preferred synchronization block indices for the first UE, one or more channel state information reference signal resource identifiers for the first UE, or a combination thereof.

[0026] In some examples of the methods, apparatus (devices), and non-transient computer-readable media described herein, the request includes an indication of whether the contention-free random access resource can be used for a four-step random access channel procedure, a two-step random access channel procedure, or both. In some examples of the methods, apparatus (devices), and non-transient computer-readable media described herein, the request includes an indication of conditions for a first UE. In some examples of the methods, apparatus (devices) and non-transient computer-readable media described herein, the condition includes: initial access from idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connectivity mode when uplink synchronization may be lost in the event that contention-free random access may not be configured, uplink data arrival during connectivity mode when uplink synchronization may be lost in the event that contention-free random access may not be configured, uplink data arrival during connectivity mode when physical uplink control channel resources for scheduling requests may be unavailable, scheduling request failure, request made by radio resource control during synchronization reconfiguration for handover in the event that contention-free random access for handover may not be configured, transition from a first UE inactive mode, establishing time alignment for a sub-timing advance group, request for other system information, beam failure recovery in the event that contention-free random access for beam failure recovery may not be configured, or a combination thereof. Attached Figure Description

[0027] Figure 1 Examples of systems for supporting wireless communication with externally assisted random access channel protocols are explained according to various aspects of this disclosure.

[0028] Figure 2 Examples of communication systems that support externally assisted random access channel procedures according to various aspects of this disclosure are explained.

[0029] Figure 3A and 3B An example communication diagram illustrating a random access channel procedure with external assistance, supported by various aspects of this disclosure, is provided.

[0030] Figure 4 An example of the process flow supporting an externally assisted random access channel procedure according to various aspects of this disclosure is explained.

[0031] Figure 5 and 6 A block diagram of an apparatus supporting an externally assisted random access channel procedure is shown according to various aspects of this disclosure.

[0032] Figure 7 A block diagram of a communication manager supporting random access channel procedures with external assistance, according to various aspects of this disclosure, is shown.

[0033] Figure 8 A diagram of a system including a device supporting an externally assisted random access channel protocol is shown according to various aspects of this disclosure.

[0034] Figure 9 and 10 A block diagram of an apparatus supporting an externally assisted random access channel procedure is shown according to various aspects of this disclosure.

[0035] Figure 11 A block diagram of a communication manager supporting random access channel procedures with external assistance, according to various aspects of this disclosure, is shown.

[0036] Figure 12 A diagram of a system including a device supporting an externally assisted random access channel protocol is shown according to various aspects of this disclosure.

[0037] Figures 13 to 16 A flowchart illustrating a method for supporting an externally assisted random access channel procedure according to various aspects of this disclosure is shown. Detailed Implementation

[0038] Some wireless communication systems can support low-complexity user equipment (UEs) (e.g., they may be referred to as light devices, new radio (NR) light devices, low-end devices, Internet of Things (IoT) devices, etc.). Low-complexity UEs may also be referred to as low-end UEs, where some features or high-end features may not be needed or useful. For example, low-complexity UEs can include sensors (e.g., industrial sensors), cameras (e.g., video surveillance equipment), wearable devices, IoT devices, low-end or loosely configured devices, etc. Such low-complexity UEs can be used in a variety of applications, including healthcare, smart cities, transportation and logistics, power distribution, processing automation, and building automation. Low-complexity UEs can communicate with base stations and operate in the same cell as other non-low-complexity UEs (e.g., they may be referred to as conventional UEs, high-end UEs, etc.). For example, in some cases, in addition to connecting to other UEs (e.g., one or more high-end UEs) via device-to-device (e.g., sidelink) connections, low-complexity UEs can also connect to the network via a connection to a base station.

[0039] Thus, in some situations, a low-complexity UE can execute random access procedures (e.g., to establish a connection with a base station, to achieve uplink synchronization with the base station, etc.). A random access procedure may include a series of handshake messages carrying information that facilitates the establishment of a connection between the UE and the base station. For example, the network may implement periodic and / or aperiodic time / frequency resources that the UE (e.g., including low-complexity UEs) can use to execute random access procedures. Random access procedures may include contention-based random access (CBRA) procedures (e.g., where devices contend for channels to obtain random access procedure signaling) and contention-free random access (CFRA) procedures (e.g., where time / frequency resources are pre-configured for the UE to perform random access procedure signaling).

[0040] However, in some situations, low-complexity UEs may be configured with reduced capabilities, which could lead to inefficient random access procedures. For example, a low-complexity UE may be configured to transmit with reduced transmit power compared to other non-low-complexity devices (e.g., compared to other high-end UEs that can operate in the same cell as the low-complexity UE). For example, the uplink transmit power capability of a low-complexity UE may be, for example, 10 dB less than that of a high-end UE. Thus, a low-complexity UE configured with CBRA procedures (e.g., where the low-complexity UE contends for the channel among other high-power high-end UEs) may have difficulty or may be unable to successfully execute such CBRA procedures (e.g., low-complexity UE CBRA procedures may be associated with network connection latency, poor network connectivity, etc.).

[0041] According to the techniques described herein, a low-complexity UE can utilize external assistance from other UEs (e.g., via device-to-device communication) to improve random access procedures. For example, a low-complexity UE can communicate with another UE (e.g., a higher-end UE or a more capable UE) via a device-to-device communication link (e.g., via a side link), and the low-complexity UE can utilize the device-to-device link to improve (e.g., simplify, accelerate, etc.) the random access procedures performed by the low-complexity UE. For example, according to the techniques described herein, a low-complexity UE can request CFRA resources via a device-to-device link with another UE. In some cases, the request may include a reason for the request (e.g., conditions of the low-complexity UE), preferred CFRA resources, etc. The assisting device (e.g., another UE in device-to-device communication with the low-complexity UE) can receive the request from the low-complexity UE and forward it to the network (e.g., forward it to the base station). The network can then configure CFRA resources for the low-complexity UE and can transmit the CFRA configuration directly to the low-complexity UE, or forward it to the low-complexity UE through another UE (e.g., through another UE), etc. Upon receiving the CFRA configuration, the low-complexity UE can accordingly execute random access procedures (e.g., CFRA procedures) with the network (e.g., with the base station).

[0042] The described techniques can provide improved random access configurations and more efficient random access procedures, allowing low-complexity UEs to retain their intended benefits (e.g., power savings). For example, a low-complexity UE can request CFRA resources (e.g., via a device-to-device link with a high-end UE) and receive CFRA configurations to increase the likelihood of a successful random access procedure with the base station (e.g., this could result in a more efficient random access procedure, which could further lead to reduced latency and improved network connectivity relative to other CFRA procedures performed by the low-complexity UE). Furthermore, utilizing an externally assisted low-complexity UE from another UE (e.g., from a connected high-end UE) can increase the likelihood of successfully communicating such requests for CFRA resources to the base station (e.g., because a connected high-end UE can more efficiently request CFRA resources on behalf of a low-complexity UE that may be associated with reduced transmit power capabilities).

[0043] The aspects of this disclosure are initially described in the context of wireless communication systems. Example communication diagrams and example process flows illustrating the aspects of the techniques discussed are then described. The aspects of this disclosure are further explained and described by means of, and with reference to, apparatus diagrams, system diagrams, and flowcharts relating to random access channel procedures with external assistance.

[0044] Figure 1Examples of a wireless communication system 100 supporting an externally assisted random access channel protocol according to various aspects of this disclosure are described. The wireless communication system 100 includes a base station 105, a user interface device (UE) 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low latency communication, or communication with low-cost and low-complexity devices.

[0045] Base station 105 can wirelessly communicate with UE 115 via one or more base station antennas. Base station 105 described herein may include, or may be referred to by those skilled in the art as, a base transceiver station, radio base station, access point, radio transceiver, B-node, evolved B-node (eNB), next-generation B-node, or gigabit B-node (any of which may be referred to as gNB), home B-node, home evolved B-node, or any other suitable term. Wireless communication system 100 may include different types of base station 105 (e.g., macrocell base station or small cell base station). UE 115 described herein may be able to communicate with various types of base station 105 and network equipment (including macro eNB, small cell eNB, gNB, relay base station, etc.).

[0046] Each base station 105 may be associated with a specific geographic coverage area 110, within which communication with various UEs 115 is supported. Each base station 105 may provide communication coverage to the corresponding geographic coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communication link 125 shown in the wireless communication system 100 may include uplink transmission from the UE 115 to the base station 105, or downlink transmission from the base station 105 to the UE 115. Downlink transmission may also be referred to as forward link transmission, and uplink transmission may also be referred to as reverse link transmission.

[0047] The geographic coverage area 110 of base station 105 can be divided into sectors that constitute part of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 can provide communication coverage to macrocells, small cells, hotspots, or other types of cells, or various combinations thereof. In some examples, base station 105 can be mobile and thus provide communication coverage to mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, and overlapping geographic coverage areas 110 associated with different technologies can be supported by the same base station 105 or different base stations 105. The wireless communication system 100 can include, for example, heterogeneous LTE / LTE-A / LTE-A Pro or NR networks, wherein different types of base stations 105 provide coverage to various geographic coverage areas 110.

[0048] The term "cell" refers to a logical communication entity used to communicate with base station 105 (e.g., on a carrier) and may be associated with identifiers to distinguish adjacent cells operating via the same or different carriers (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)). In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types that provide access for different types of devices (e.g., Machine-Type Communication (MTC), Narrowband Internet of Things (NB-IoT), Enhanced Mobile Broadband (eMBB), or others). In some cases, the term "cell" may refer to a portion (e.g., a sector) of the geographical coverage area 110 on which the logical entity operates.

[0049] Each UE 115 can be distributed throughout the wireless communication system 100, and each UE 115 can be stationary or mobile. UE 115 may also be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or any other suitable term, where "device" may also be referred to as a unit, station, terminal, or client. UE 115 can also be a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, UE 115 may also refer to a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or MTC device, etc., which can be implemented in various items (such as appliances, vehicles, instruments, etc.).

[0050] Some UE 115 devices (such as MTC or IoT devices) can be low-cost or low-complexity devices and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with base station 105 without human intervention. In some examples, M2M communication or MTC may include communication from devices that have integrated sensors or meters to measure or capture information and relay that information to a central server or application that can utilize the information or present it to people interacting with the program or application. Some UE 115 devices may be designed to collect information or enable automated machine behavior. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wilderness survival monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based commercial toll collection.

[0051] Some UEs 115 can be configured to operate in reduced-power modes, such as half-duplex communication (e.g., a mode that supports unidirectional communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication can be performed at a reduced peak rate. Other power-saving techniques for UE 115 include entering a power-saving "deep sleep" mode when not engaged in active communication, or operating on limited bandwidth (e.g., according to narrowband communication). In some cases, UE 115 can be designed to support critical functions (e.g., mission-critical functions), and the wireless communication system 100 can be configured to provide ultra-reliable communication for these functions.

[0052] In some scenarios, UE 115 may also be able to communicate directly with other UE 115 (e.g., using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more UEs in a group of UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other UEs 115 in the group may be outside the geographic coverage area 110 of base station 105 or may be unable to receive transmissions from base station 105 for other reasons. In some scenarios, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, where each UE 115 transmits to every other UE 115 in the group. In some scenarios, base station 105 facilitates the scheduling of resources for D2D communication. In other scenarios, D2D communication is performed between the individual UEs 115 without involving base station 105.

[0053] Base station 105 can communicate with core network 130 and with each other. For example, base station 105 can interface with core network 130 via backhaul link 132 (e.g., via S1, N2, N3 or other interfaces). Base stations 105 can communicate with each other directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) on backhaul link 134 (e.g., via X2, Xn or other interfaces).

[0054] Core network 130 provides user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. Core network 130 may be an evolved packet core (EPC), which may include at least one Mobility Management Entity (MME), at least one Serving Gateway (S-GW), and at least one Packet Data Network (PDN) Gateway (P-GW). The MME manages non-access stratum (e.g., control plane) functions, such as mobility, authentication, and bearer management of UE 115 served by base station 105 associated with the EPC. User IP packets can be delivered via the S-GW, which itself may connect to the P-GW. The P-GW provides IP address allocation and other functions. The P-GW may connect to network operator IP services. Operator IP services may include access to the Internet, intranets, IP Multimedia Subsystem (IMS), or packet-switched (PS) streaming services.

[0055] At least some network devices (such as base station 105) may include sub-components, such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity may communicate with each UE 115 through several other access network transport entities, which may be referred to as a radio headend, a smart radio headend, or a transmit / receive point (TRP). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio headends and access network controllers) or combined into a single network device (e.g., base station 105).

[0056] Wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 MHz to 300 GHz. Generally, the 300 MHz to 3 GHz band is referred to as the Ultra High Frequency (UHF) band or decimeter band because the wavelengths range from approximately 1 decimeter to 1 meter. UHF waves can be blocked or redirected by buildings and environmental features. However, these waves can penetrate various structures sufficiently for macrocells to provide service to UE 115 located indoors. Compared to transmissions using smaller frequencies and longer waves in the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz, UHF wave transmission can be associated with smaller antennas and shorter ranges (e.g., less than 100 km).

[0057] The wireless communication system 100 can also operate in the ultra-high frequency (SHF) zone using a frequency band from 3 GHz to 30 GHz (also known as the centimeter band). The SHF zone includes frequency bands that can be used opportunistically by devices that can tolerate interference from other users (such as the 5 GHz Industrial, Scientific and Medical (ISM) band).

[0058] The wireless communication system 100 can also operate in extremely high frequency (EHF) zoning (e.g., from 30 GHz to 300 GHz), also known as the millimeter band. In some examples, the wireless communication system 100 can support millimeter-wave (mmW) communication between the UE 115 and the base station 105, and the EHF antennas of the corresponding devices can be even smaller and more closely spaced than UHF antennas. In some cases, this can facilitate the use of antenna arrays within the UE 115. However, the propagation of EHF transmissions may suffer from even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein can be employed across transmissions using one or more different frequency zonings, and the frequency band usage specified across these frequency zonings may vary by country or regulatory authority.

[0059] In some scenarios, wireless communication system 100 may utilize both licensed and unlicensed radio spectrum bands. For example, wireless communication system 100 may employ License-Assisted Access (LAA), LTE Unlicensed (LTE-U) radio access technology, or NR technology in unlicensed frequency bands (such as the 5 GHz ISM band). When operating in unlicensed radio spectrum bands, wireless devices (such as base station 105 and UE 115) may employ a Listen-Before-Talk (LBT) protocol to ensure the frequency channel is open before transmitting data. In some scenarios, operation in unlicensed frequency bands may be based on carrier aggregation configurations (e.g., LAA) in coordination with component carriers operating in licensed frequency bands. Operation in unlicensed spectrum may include downlink transmission, uplink transmission, peer-to-peer transmission, or a combination thereof. Duplexing in unlicensed spectrum may be based on Frequency Division Duplex (FDD), Time Division Duplex (TDD), or a combination thereof.

[0060] In some examples, base station 105 or UE 115 may be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. For example, wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., base station 105) and a receiving device (e.g., UE 115), wherein the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communication may employ multipath signal propagation to increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. For example, the transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Similarly, the receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of these multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiving device; and multi-user MIMO (MU-MIMO), in which multiple spatial layers are transmitted to multiple devices.

[0061] Beamforming (also known as spatial filtering, directional transmission, or directional reception) is a signal processing technique used at a transmitting or receiving device (e.g., base station 105 or UE 115) to shape or guide an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array, such that signals propagating relative to a particular orientation of the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to the signals transmitted via the antenna elements may include the transmitting or receiving device applying specific amplitude and phase shifts to the signals carried via each antenna element associated with that device. The adjustments associated with each antenna element may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or relative to some other orientation).

[0062] In one example, base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communication with UE 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by base station 105 in different directions. This may include a signal being transmitted according to different beamforming weight sets associated with different transmission directions. Transmissions in different beam directions can be used (e.g., by base station 105 or receiving equipment, such as UE 115) to identify the beam direction used by base station 105 for subsequent transmission and / or reception.

[0063] Some signals (such as data signals associated with a particular receiving device) may be transmitted by base station 105 in a single beam direction (e.g., the direction associated with the receiving device (such as UE 115). In some examples, the beam direction associated with transmission along a single beam direction may be determined at least in part based on the signals transmitted in different beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions, and UE 115 may report to base station 105 an indication of the signals it received with the highest signal quality or other acceptable signal quality. Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may use similar techniques to transmit signals multiple times in different directions (e.g., to identify the beam direction used by UE 115 for subsequent transmission or reception) or to transmit signals in a single direction (e.g., to transmit data to the receiving device).

[0064] A receiver device (e.g., UE 115, which may be an example of an mmW receiver device) may attempt multiple receive beams when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from base station 105. For example, the receiver device may attempt multiple reception directions by: receiving via different antenna subarrays; processing received signals according to different antenna subarrays; receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of the antenna array; or processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of the antenna array, any of which may be referred to as “listening” according to different receive beams or reception directions. In some examples, the receiver device may use a single receive beam to receive along a single beam direction (e.g., when a data signal is received). Individual receive beams may be aligned at least in part based on beam directions determined by listening to different receive beam directions (e.g., at least in part based on beam directions determined to have the highest signal strength, highest signal-to-noise ratio, or other acceptable signal quality by listening to multiple beam directions).

[0065] In some cases, the antennas of base station 105 or UE 115 may be located within one or more antenna arrays that support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may coexist at an antenna assembly (such as an antenna tower). In some cases, the antennas or antenna arrays associated with base station 105 may be located in different geographical locations. Base station 105 may have an antenna array with several rows and columns of antenna ports that base station 105 can use to support beamforming for communication with UE 115. Similarly, UE 115 may have one or more antenna arrays that support various MIMO or beamforming operations.

[0066] In some scenarios, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communication at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. The Radio Link Control (RLC) layer performs packet segmentation and reassembly for communication on logical channels. The Media Access Control (MAC) layer performs priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use Hybrid Automatic Repeat Request (HARQ) to provide retransmissions at the MAC layer, thereby improving link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide the establishment, configuration, and maintenance of RRC connections between UE115 and base station 105 or core network 130 supporting user plane data radio bearers. At the physical layer, transport channels can be mapped to physical channels.

[0067] In some scenarios, UE 115 and base station 105 may support data retransmission to increase the likelihood of successful data reception. HARQ feedback is a technique to increase the likelihood of correctly receiving data on communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), forward error correction (FEC), and retransmission (e.g., Automatic Repeat Request (ARQ)). HARQ can improve MAC layer throughput in poor radio conditions (e.g., signal-to-noise ratio conditions). In some scenarios, the wireless device may support simultaneous time-slot HARQ feedback, where the device can provide HARQ feedback in a specific time slot for data received in previous symbols within that time slot. In other scenarios, the device may provide HARQ feedback in subsequent time slots or according to some other time interval.

[0068] The time interval in LTE or NR can be represented by a basic time unit (which may, for example, refer to the sampling period T). s = 1 / 30,720,000 seconds) is used as a multiple. The time interval of communication resources can be organized according to radio frames, each with a duration of 10 milliseconds (ms), where the frame period can be expressed as T. f =307,200T s Radio frames can be identified by System Frame Numbers (SFNs) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. Subframes may be further divided into two time slots, each with a duration of 0.5 ms, and each time slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix preceding each symbol period). Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be referred to as a Transmission Time Interval (TTI). In other cases, the smallest scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in a shortened TTI (sTTI) burst or in a selected component carrier using an sTTI).

[0069] In some wireless communication systems, time slots can be further divided into multiple mini-time slots containing one or more symbols. In some instances, the symbol or mini-time slot of a mini-time slot can be the smallest scheduling unit. For example, the duration of each symbol may vary depending on the subcarrier spacing or operating frequency band. Furthermore, some wireless communication systems can implement time slot aggregation, where multiple time slots or mini-time slots are aggregated together and used for communication between UE 115 and base station 105.

[0070] The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications on communication link 125. For example, a carrier of communication link 125 may include a portion of a radio spectrum band operating according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a predefined frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be located according to a channel grid for discovery by UE 115. A carrier may be downlink or uplink (e.g., in FDD mode), or configured to carry both downlink and uplink communications (e.g., in TDD mode). In some examples, the signal waveform transmitted on a carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as Orthogonal Frequency Division Multiplexing (OFDM) or Discrete Fourier Transform Extended OFDM (DFT-S-OFDM)).

[0071] The carrier organization structure can vary depending on the radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). For example, communication on a carrier can be organized according to TTIs or time slots, each of which may include user data and control information or signaling supporting the decoding of the user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information) and control signaling coordinating carrier operation. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling coordinating the operation of other carriers.

[0072] Physical channels can be multiplexed on a carrier using various techniques. Physical control channels and physical data channels can be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM), frequency division multiplexing (FDM), or a hybrid TDM-FDM technique. In some examples, control information transmitted in the physical control channel can be distributed in a cascaded manner between different control regions (e.g., between a shared control region or shared search space and one or more UE-specific control regions or UE-specific search spaces).

[0073] A carrier may be associated with a specific bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth may be one of a plurality of predetermined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each served UE 115 may be configured to operate on a portion or all of the carrier bandwidth. In other examples, some UEs 115 may be configured to operate using a narrowband protocol type associated with a predefined portion or range within the carrier (e.g., a set of subcarriers or RBs) (e.g., “in-band” deployment of a narrowband protocol type).

[0074] In systems employing MCM technology, a resource element may include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Therefore, the more resource elements UE 115 receives and the higher the order of the modulation scheme, the higher the data rate UE 115 can achieve. In MIMO systems, wireless communication resources can refer to a combination of radio frequency spectrum resources, temporal resources, and spatial resources (e.g., spatial layers), and using multiple spatial layers can further improve the data rate for communication with UE 115.

[0075] The devices of the wireless communication system 100 (e.g., base station 105 or UE 115) may have a hardware configuration that supports communication on a specific carrier bandwidth, or may be configurable to support communication on a single carrier bandwidth within a set of carrier bandwidths. In some examples, the wireless communication system 100 may include base station 105 and / or UE 115 that support simultaneous communication via carriers associated with more than one different carrier bandwidth.

[0076] The wireless communication system 100 can support communication with the UE 115 on multiple cells or carriers, a feature that may be referred to as carrier aggregation or multi-carrier operation. The UE 115 can be configured to have multiple downlink component carriers and one or more uplink component carriers according to the carrier aggregation configuration. Carrier aggregation can be used in conjunction with both FDD and TDD component carriers.

[0077] In some scenarios, the wireless communication system 100 may utilize enhanced component carrier (eCC). eCC can be characterized by one or more features, including a wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or a modified control channel configuration. In some scenarios, eCC may be associated with carrier aggregation configurations or dual connectivity configurations (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). eCC can also be configured for use in unlicensed or shared spectrum (e.g., where more than one operator is permitted to use the spectrum). eCC characterized by a wide carrier bandwidth may include one or more segments that can be utilized by a UE 115 that is unable to monitor the entire carrier bandwidth or is otherwise configured to use a limited carrier bandwidth (e.g., to save power).

[0078] In some cases, eCC may utilize symbol durations different from those of other component carriers. This may include using a reduced symbol duration compared to that of other component carriers. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. Devices utilizing eCC (such as UE 115 or base station 105) can transmit wideband signals (e.g., based on frequency channels or carrier bandwidths of 20, 40, 60, 80 MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). The TTI in eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in the TTI) may be variable.

[0079] Wireless communication system 100 can be an NR system that can utilize any combination of licensed, shared, and unlicensed spectrum bands. The flexibility of eCC symbol duration and subcarrier spacing allows eCC to be used across multiple spectrums. In some examples, NR shared spectrum can improve spectrum utilization and spectral efficiency, particularly through dynamic vertical (e.g., across frequency domains) and horizontal (e.g., across time domains) sharing of resources.

[0080] Wireless communication system 100 can support low-complexity UE 140 (e.g., which may be referred to as a light device, NR light device, low-end device, IoT device, etc.). Low-complexity UE 140 may also be referred to as a low-end UE, where some features or high-end features may not be needed or useful. For example, low-complexity UE 140 may include smart devices, sensors (e.g., industrial sensors), cameras (e.g., video surveillance equipment), wearable devices, IoT devices, low-end or loose-fitting devices, etc. Such low-complexity UE 140 can be used in a variety of applications, including healthcare, smart cities, transportation and logistics, power distribution, process automation, and building automation. Low-complexity UE 140 can communicate with base station 105 and operate in the same cell as other non-low-complexity UEs (e.g., which may be referred to as a conventional UE 115, high-end UE, etc.). For example, in some cases, in addition to connecting to other UEs 115 (e.g., one or more high-end UEs) via device-to-device (e.g., sidelink) connections, the low-complexity UE 140 can also connect to the network via a connection to base station 105.

[0081] Thus, in some situations, the low-complexity UE 140 can execute random access procedures (e.g., to establish or maintain a connection with base station 105). The random access procedure may include a series of handshake messages carrying information facilitating the establishment of a connection between the low-complexity UE 140 and base station 105. For example, the network may enable periodic and / or aperiodic time / frequency resources available to the UEs (e.g., UE 115 and low-complexity UE 140) for executing random access procedures. The random access procedure may include: CBRA procedures (e.g., where devices contend for channels to obtain random access procedure signaling) and CFRA procedures (e.g., where time / frequency resources are pre-configured for devices to perform random access procedure signaling).

[0082] While the low-complexity UE 140, with its relatively limited capabilities, can meet and support the requirements of communications such as Narrowband Internet of Things (NB-IoT) and Machine Long Term Evolution (LTE) (LTE-M), such limited capabilities can also impose additional challenges in wireless communication systems. That is, allowing the low-complexity UE 140 to retain its intended benefits (e.g., power savings, low-cost / low-complexity design, etc.) may lead to challenges for certain operations or applications.

[0083] For example, a low-complexity UE 140 may be configured to have reduced capabilities, which could lead to inefficient random access procedures. For instance, compared to other non-low-complexity devices (e.g., compared to other high-end UEs 115 that can operate in the same cell as the low-complexity UE 140), the low-complexity UE 140 may be configured to transmit with reduced transmit power. For example, the uplink transmit power of the low-complexity UE 140 may have a transmit power capability that is, for example, 10 dB less than that of the high-end UE 115. Thus, a low-complexity UE 140 configured with CBRA procedures (e.g., where the low-complexity UE 140 contends for the channel among other higher-power high-end UEs 115) may have difficulty or may be unable to successfully execute such CBRA procedures (e.g., CBRA procedures executed by the low-complexity UE 140 may be inefficient and may be associated with network connection latency, poor network connectivity, etc.).

[0084] According to the techniques described herein, a low-complexity UE 140 can utilize external assistance (e.g., via device-to-device communication) from another UE 115 to improve random access procedures. For example, the low-complexity UE 140 can communicate with another UE 115 (e.g., with a higher-end UE or a more capable UE) via a device-to-device communication link (e.g., via a side link), and the low-complexity UE 140 can utilize the device-to-device link to improve (e.g., simplify, accelerate, etc.) the random access procedures performed by the low-complexity UE 115. For example, according to the techniques described herein, the low-complexity UE 140 can request CFRA resources via a device-to-device link with another UE 115. In some cases, the request may include a reason for the request (e.g., conditions of the low-complexity UE 140), preferred CFRA resources, etc. The auxiliary UE 115 (e.g., another UE 115 in device-to-device communication with the low-complexity UE 140) can receive a request from the low-complexity UE 140 and forward the request to the network (e.g., to base station 105). The network (e.g., wireless communication system 100) can then configure CFRA resources for the low-complexity UE 140, and can transmit the CFRA configuration directly to the low-complexity UE 140, or transmit the CFRA configuration to the low-complexity UE 140 via another UE 115 (e.g., via another UE 115 to forward to the low-complexity UE 140), and so on. Upon receiving the CFRA configuration, the low-complexity UE 140 can accordingly execute a random access procedure (e.g., CFRA procedure) with the network (e.g., with base station 105).

[0085] The described techniques provide improved random access configurations and more efficient random access procedures, allowing the low-complexity UE 140 to retain its intended benefits (e.g., power savings, low transmit power, high efficiency, etc.) in device-to-device communication. For example, the low-complexity UE 140 can request CFRA resources (e.g., via a device-to-device link with the high-end UE 115) and receive CFRA configurations to increase the likelihood of a successful random access procedure with the base station 105 (e.g., this could result in a more efficient random access procedure, which could further lead to reduced latency and improved network connectivity relative to other CFRA procedures performed by the low-complexity UE 140). Furthermore, utilizing external assistance from other UEs 115 (e.g., from a connected high-end UE) can increase the likelihood of successfully communicating such requests for CFRA resources to the base station 105 (e.g., because the connected high-end UE 115 can more efficiently request CFRA resources on behalf of the low-complexity UE 140, which may be associated with reduced transmit power capabilities).

[0086] Figure 2 Examples of a wireless communication system 200 supporting an externally assisted random access channel protocol according to various aspects of this disclosure are described. In some examples, the wireless communication system 200 may implement various aspects of the wireless communication system 100. For example, the wireless communication system 200 may include a base station 105-a, a UE 115-a, and a low-complexity UE 140-a (e.g., a smartwatch), which may be referenced... Figure 1 Examples of the corresponding devices described herein. Furthermore, as described herein, low-complexity UE140-a typically includes or refers to lightweight devices, NR lightweight devices, low-end devices, IoT devices, smart devices, sensors, cameras, wearable devices, etc.

[0087] The low-complexity UE 140 can be designed for low cost and low power consumption. For example, the low-complexity UE 140 can be designed for wireless sensor applications such as pressure sensors, humidity sensors, thermometers, motion sensors, accelerometers, etc. In some cases, the low-complexity UE 140 can be designed for wearable device applications such as smartwatches, rings, electronic health-related devices, medical monitoring devices, fitness or biomonitoring devices, etc. Thus, the low-complexity UE 140 can be smaller in size and have a lower battery capacity compared to a conventional UE 115 (e.g., compared to mobile phones, tablets, etc.). Thus, the low-complexity UE 140 can be designed to reduce device complexity and operating procedures. According to the techniques described herein, the low-complexity UE 140 can utilize (e.g., using) external assistance from other UEs 115 to simplify the random access procedures of the low-complexity UE 140 based on device-to-device communication.

[0088] For example, the low-complexity UE 140-a can perform device-to-device communication and therefore maintain links to other UEs 115 and to the base station 105. Figure 2 As shown, UE 140-a can maintain link 205 (e.g., which may be referred to as a device-to-device link, side link, PC5 link, etc.) to UE 115-a and link 210 (e.g., which may be referred to as a link to the cellular air interface, Uu interface, etc. of base station 105-a). In some cases, low-complexity UE 140-a can use link 205 to extend its communication coverage, increase channel throughput to the cellular network, etc. (e.g., via communication via link 215 that can be forwarded by UE 115-a via link 205, via communication via link 205 that can be forwarded by UE 115-a via link 215, etc.). For example, UE 115-a can connect to base station 105-a via link 215 (e.g., a link to the cellular air interface, Uu interface, etc.) and can provide forwarding operations for communication between low-complexity UE 140-a and base station 105-a. The low-complexity UE 140-a can maintain both links 210 and 205 because the coverage of the cellular network (e.g., coverage via link 210) may be wider than the coverage via link 205. Furthermore, the low-complexity UE 140-a can maintain both links 210 and 205 because communication via link 205 can be associated with the lower power consumption of the low-complexity UE 140-a.

[0089] As discussed herein, random access can be used by a low-complexity UE 140-a, for example, to achieve uplink synchronization with base station 105-a (e.g., to enable the low-complexity UE 140-a to send information to base station 105-a). In some cases, random access procedures (e.g., random access channel (RACH) procedures) can be executed for initial access from idle mode, for RRC connection re-establishment procedures, for downlink or uplink data arrival during uplink synchronization loss in connected mode, for uplink data arrival during connected mode when no physical uplink control channel (PUCCH) resources are available for scheduling requests (SR), for SR failures, for requests made by RRC during synchronization reconfiguration for handover, for transitions from UE inactive mode to establish time alignment for the secondary timing advance group (TAG), to request other system information (other SIs), to perform beam fault recovery, etc. In some cases, random access can be contention-based (such as, for example, with CBRA procedures), where multiple UEs (e.g., multiple UEs 115 and / or low-complexity UE 140) may perform random access together, potentially leading to conflicts. In other cases, random access can be contention-free (such as, for example, with CFRA procedures), where UE-specific RACH resources and preambles can be allocated (e.g., this can reduce or eliminate conflicts).

[0090] The techniques described herein can provide a low-complexity UE 140 that requests CFRA resources and preambles for random access. Generally, CFRA resources can refer to resources reserved for random access procedures performed by a device (such as, for example, the low-complexity UE 140). That is, CFRA resources (and CFRA configuration) can refer to resources reserved or configured for random access procedures in the context of a system that also supports contention-based access with other resources (e.g., CFRA resources may not necessarily imply complete non-contention with other radio devices, however, CFRA resources can be reserved and configured within the system to reduce or eliminate contention with other radio devices within the system).

[0091] Requests for CFRA resources by low-complexity UE 140 (e.g., base station 105-a configuration resulting from CFRA resources for low-complexity UE 140) can provide faster random access by low-complexity UE 140, and can improve random access success rate when low-complexity UE 140 has reduced maximum uplink transmit power, etc.

[0092] In the wireless communication system 200, if a low-complexity UE 140-a determines that it needs to perform random access to the network (e.g., to base station 105-a), a CFRA (Concurrent Access Restriction) is configured for the low-complexity UE 140-a. If the low-complexity UE 140-a can communicate with UE 115-a via link 205, the low-complexity UE 140-a can request CFRA resources and a preamble (e.g., by transmitting the request to UE 115-a using link 205). UE 115-a can transmit or forward the request to the network (e.g., to base station 105-a), and the network can configure the low-complexity UE 140-a with a CFRA configuration based on the request. Thus, upon receiving the CFRA configuration, the low-complexity UE 140-a can perform CFRA to the network (e.g., the low-complexity UE 140-a can perform a CFRA procedure with base station 105-a).

[0093] In some cases, a low-complexity UE 140-a may include a reason for random access in its request for CFRA resources and preambles (e.g., the low-complexity UE 140-a may include an indication of conditions of the low-complexity UE 140-a that prompts a request for CFRA resources for random access procedures). For example, in some cases, certain conditions of the low-complexity UE 140-a may prompt or trigger the low-complexity UE 140-a to request CFRA resources for random access procedures. Such conditions (or, in other words, scenarios) may include initial access from idle mode, RRC connection re-establishment procedures for radio link failure recovery, downlink or uplink data arrival during connected mode when uplink synchronization is lost without CFRA configured, uplink data arrival during connected mode when no PUCCH resources are available for SR, SR failure, requests by RRC during synchronization reconfiguration for handover without CFRA configured for handover, transition from UE inactive mode, establishing time alignment for sub-TAG, requesting other SIs, beam failure recovery without CFRA configured for beam failure recovery, and so on. For example, low-complexity UE 140-a can use link 205 to transmit a request for CFRA resources to UE 115-a. This request may include indications that low-complexity UE 140-a is attempting to perform initial access from idle mode, indications of radio link failure recovery conditions for low-complexity UE 140-a, indications that no PUCCH resources for beam fault recovery are available for low-complexity UE 140-a, indications that low-complexity UE 140-a is transitioning from UE inactive mode, indications that no CFRA is configured for beam fault recovery by low-complexity UE 140-a, and so on. Generally, the request may include information indicating various conditions of low-complexity UE 140-a and / or information indicating the reason / scenario for low-complexity UE 140-a requesting CFRA resources.

[0094] In some examples, the low-complexity UE 140-a may include preferences (e.g., preferences for random access configuration) in the request. For example, the low-complexity UE 140-a may identify or determine a preferred synchronization block (SSB) index, a preferred channel state information reference signal (CSI-RS) resource ID (e.g., if CSI-RS has been configured to the low-complexity UE 140-a prior to random access), etc., associated with preferred random access resources, preferred preambles, preferred random access timing, etc. For example, different SSBs may be mapped to different resource sets used as TDM-based RACH resources or different SSBs may be mapped to overlapping time resource sets used for RACH transmission (e.g., FDM-based RACH resources). Additionally or alternatively, different SSBs may further correspond to different spatial resources, such as different directional downlink transmit beams and uplink receive beams. Thus, in some examples, the low-complexity UE 140-a can determine the preferred random access resource, preferred random access preamble, and / or preferred random access timing, and the low-complexity UE 140-a can include indications of such information in the CFRA request. In some examples, the low-complexity UE 140-a can determine one or more preferred SSB indices and / or one or more CSI-RS resource identifiers associated with the preferred random access resource, preferred random access preamble, or preferred random access timing, and the low-complexity UE 140-a can include indications of such information in the CFRA request. Furthermore, in some examples, the CFRA request can indicate whether the requested random access resource is for a 4-step RACH, a 2-step RACH, or both.

[0095] In some scenarios, low-complexity UE 140-a may include its unique identity (e.g., UE_ID) in the CFRA request, and this unique identity may be used to identify low-complexity UE 140-a in air signaling from base station 105-a to UE 115-a (e.g., the unique identity of low-complexity UE 140-a may be used by UE 115-a or another UE 115 to forward CFRA configuration from base station 105-a to low-complexity UE 140-a). In some scenarios, the identity or identifier of low-complexity UE 140-a may be its Cellular Radio Network Temporary Identifier (C-RNTI) (e.g., if low-complexity UE 140-a has already obtained the C-RNTI in the cell before performing random access).

[0096] The network (e.g., base station 105-a) can configure CFRA resources and preambles to the low-complexity UE 140-a. CFRA configuration may include (e.g., but not limited to) random access time / frequency resource information, preamble information (e.g., CFRA preamble information), random access timing information, associated SSB time index information, CSI-RS resource ID information (e.g., if CSI-RS has been configured to the low-complexity UE 140-a prior to random access), and so on. For example, in some cases, CFRA configuration may be determined and configured by the network at least in part based on (e.g., considering / complying some, all, or not considering / complying) the preferences included in the request (e.g., at least in part based on the preferred CFRA resources, preferred SSB index, etc., indicated by the low-complexity UE 140-a in the CFRA request). In some cases, CFRA configuration may be based on a preference indicated for 4-step RACH, 2-step RACH, or both (e.g., included in the CFRA request) (e.g., and CFRA configuration may indicate whether random access resources are associated with 4-step RACH, 2-step RACH, or both).

[0097] In some examples, CFRA configuration can be based on conditions included in the CFRA request. For example, in some cases, the network (e.g., base station 105-a) may configure CFRA resources for some conditions of low-complexity UE 140, and may not configure CFRA resources for other conditions of low-complexity UE 140 (e.g., based on various considerations made by the network, such as the importance or critical nature of the conditions indicated by the CFRA request, such as the application of low-complexity UE 140 and the application of other UEs 115, such as the priority of low-complexity UE 140 and the priority of other UEs 115, such as network congestion, such as the availability of CFRA resources, etc.).

[0098] As discussed herein, low-complexity UE 140-a can typically transmit requests for CFRA resources by utilizing external assistance (e.g., by using a device-to-device link, such as link 205). Such signaling for requests for CFRA resources by low-complexity UE 140 is described herein, for example, with reference to... Figure 3A Further description. Based on the request for CFRA resources, the network can determine the CFRA resource configuration for the low-complexity UE 140-a, and the network (e.g., base station 105) can transmit the CFRA configuration, as illustrated herein by reference, for example. Figure 3BFurther description. Upon receiving configured random access resources and associated information (e.g., upon receiving CFRA configuration), the low-complexity UE 140-a can perform CFRA on the radio network. For example, base station 105-a can detect the RACH preamble associated with the CFRA configuration at the random access timing associated with the CFRA configuration.

[0099] Figure 3A and 3B Example communication diagrams 300-303 supporting random access channel procedures with external assistance according to various aspects of this disclosure are illustrated. In some examples, communication diagrams 300-303 may implement aspects of wireless communication system 100 and / or wireless communication system 200. For example, communication diagram 300 may include base station 105-b, UE 115-b, UE 115-c, and low-complexity UE 140-b (e.g., a smartwatch), which may be references Figure 1 and 2 Examples of the corresponding devices described herein. Furthermore, as described herein, low-complexity UE 140-b typically includes or refers to lightweight devices, NR lightweight devices, low-end devices, IoT devices, smart devices, sensors, cameras, wearable devices, etc.

[0100] Figure 3A Example communication diagram 300 illustrates the signaling of a request for CFRA resources by a low-complexity UE 140. For example, low-complexity UE 140-b can forward the request to UE 115-b. In some cases, this request may be referred to herein as a request for random access resources, a request for CFRA resources, a random access assistance request, an external assistance request, etc. UE 115-b (e.g., connected UE 115, high-end UE 115, etc.) can then forward or transmit the request to base station 105-b. Thus, base station 105-b can receive the request and can configure random access resources (e.g., CFRA resources) for low-complexity UE 140-b. As discussed herein, such external assistance from UE 115-b (e.g., via a device-to-device link between UE 115-b and the low-complexity UE 140-b) can provide a more efficient request for random access resources by the low-complexity UE 140-b (e.g., because the low-complexity UE 140-b can transmit more efficiently at low power on the device-to-device link, and UE 115-b can subsequently forward the request to base station 105-b at higher transmit power, which can increase the likelihood of successful reception by base station 105-b).

[0101] Figure 3BExample communication diagrams 301-303 illustrate the example network (e.g., base station 105-b) configuration for random access resources for low-complexity UE 140-b. In example communication diagram 301, random access resource configuration (e.g., CFRA configuration, CFRA resource configuration, etc.) can be transmitted from base station 105-b through UE 115-b. UE 115-b can then transmit the random access configuration to low-complexity UE 140-b via a device-to-device link. In the example of communication diagram 301, the random access resource configuration can be transmitted from base station 105-b to low-complexity UE 140-b via UE 115-b forwarding random access resource requests on behalf of low-complexity UE 140-b. That is, in some cases, communication diagram 300 can explain aspects of a low-complexity UE 140-b requesting random access resources, and communication diagram 301 can explain aspects of the random access resource configuration of base station 105-b for low-complexity UE 140-b (e.g., aspects of communication diagram 300 and communication diagram 301 can be combined in implementation).

[0102] In example communication diagram 302, random access resource configuration (e.g., CFRA configuration, CFRA resource configuration, etc.) can be transmitted by base station 105-b through UE 115-b and / or UE 115-c. UE 115-b and / or UE 115-c can then transmit the random access configuration to low-complexity UE 140-b via a corresponding device-to-device link with low-complexity UE 140-b. In the example of communication diagram 302, random access resource configuration can be transmitted from base station 105-b to low-complexity UE 140-b via UE 115-b forwarding random access resource requests on behalf of low-complexity UE 140-b, and / or random access resource configuration can be transmitted from base station 105-b to low-complexity UE 140-b via UE 115-c, which can be a different UE 115 than those available to low-complexity UE 140-b. That is, in some cases, communication diagram 300 can explain aspects of a low-complexity UE 140-b requesting random access resources, and communication diagram 302 can explain aspects of the random access resource configuration of base station 105-b for low-complexity UE 140-b (e.g., aspects of communication diagram 300 and communication diagram 302 can be combined in implementation).

[0103] In example communication diagram 303, random access resource configuration (e.g., CFRA configuration, CFRA resource configuration, etc.) can be directly transmitted from base station 105-b to low-complexity UE 140-b (e.g., via direct link, Uu interface, cellular air interface, etc.). In some cases, communication diagram 300 can illustrate aspects of the low-complexity UE 140-b requesting random access resources, and communication diagram 303 can illustrate aspects of the random access resource configuration of base station 105-b for low-complexity UE 140-b (e.g., aspects of communication diagrams 300 and 303 can be combined in implementation).

[0104] As discussed herein, in some scenarios, a request for random access resources may include an identifier for the low-complexity UE 140-b. Thus, in example communication diagrams 301-303, UE 115-b, UE 115-c, and / or the low-complexity UE 140-b may identify a random access configuration intended for the low-complexity UE 140-b. In example communication diagrams 301-302, in some scenarios, UE 115-b and / or UE 115-c may forward a random access configuration to the low-complexity UE 140-b, at least in part, based on an identifier for the low-complexity UE 140-b included in the request (e.g., using a corresponding device-to-device link with the low-complexity UE 140-b).

[0105] Figure 4 Examples of process flow 400 supporting random access channel procedures with external assistance according to various aspects of this disclosure are described. In some examples, process flow 400 may implement aspects of wireless communication system 100 and / or wireless communication system 200. For example, process flow 400 may include base station 105-c, UE 115-d, and low-complexity UE 140-c (e.g., smartwatch), which may be referenced Figure 1 Examples of the corresponding devices described in sections 3 and 3. Furthermore, as described herein, the low-complexity UE 140-c typically includes or refers to lightweight devices, NR lightweight devices, low-end devices, IoT devices, smart devices, sensors, cameras, wearable devices, etc. Process flow 400 includes functions and communications implemented by base station 105-c, UE 115-d, and low-complexity UE 140-c in the context of externally assisted random access channel procedures (e.g., for more efficient random access configuration and more efficient random access procedures performed by the low-complexity UE).

[0106] In the following description of process flow 400, operations between base station 105-c, UE 115-d, and low-complexity UE 140-c may be transmitted in a different order than shown, or these operations may be performed in a different order or at different times. Some operations may also be excluded from process flow 400, or other operations may be added to process flow 400. It will be understood that although base station 105-c, UE 115-d, and low-complexity UE 140-c are shown to be performing several operations of process flow 400, any wireless device may perform the operations shown.

[0107] At 405, the low-complexity UE 140-c can determine whether to request CFRA resources. For example, the low-complexity UE 140-c can determine whether to request CFRA resources based on its CFRA configuration, its low-power capability, and its ability to communicate with UE 115-d on a device-to-device link.

[0108] In some examples, a low-complexity UE 140-c may determine whether to request CFRA resources based on conditions of the low-complexity UE 140-c. For example, such conditions (e.g., which may prompt or trigger a CFRA resource request) may include: initial access from idle mode conditions, RRC re-establishment procedure for radio link failure recovery, downlink data arrival during uplink synchronization loss in connected mode without CFRA configured, uplink data arrival during uplink synchronization loss in connected mode without CFRA configured, uplink data arrival during connected mode when physical uplink control channel resources for scheduling requests are unavailable, scheduling request failure, requests controlled by radio resources during synchronization reconfiguration for handover without CFRA configured for handover, transition from inactive mode of low-complexity UE 140-c, establishing time alignment for secondary timing advance groups, requests for other system information, beam failure recovery without CFRA configured for beam failure recovery, and so on.

[0109] In 410, in some situations, a low-complexity UE 140-c can identify or identify certain preferences for random access procedures (e.g., for requests to configure random access resources). For example, such preferences may include preferred random access preamble, preferred random access resources, preferred SSB, preferred CSI-RS resources, preferred 2-step RACH procedure, preferred 4-step RACH procedure, etc.

[0110] In section 415, the low-complexity UE 140-c may transmit a request for CFRA resources to UE 115-d (e.g., based on the low-power capability of the low-complexity UE 140-c). As discussed herein, in some cases, the request may include a reason for the request (e.g., a condition indicating the request of the low-complexity UE 140-c), any preference for random access procedures, or both. For example, in some cases, the request may include an indication of the CFRA configuration of the low-complexity UE 140-c, the low-power capability of the low-complexity UE 140-c, the ability of the low-complexity UE 140-c to communicate with UE 115-d on a device-to-device link, or a combination thereof. Additionally or alternatively, the request may include an indication of preferred random access resources, preferred random access preambles, preferred random access timing, one or more preferred SSB indices, one or more CSI-RS resource identifiers, or a combination thereof.

[0111] At 420, UE 115-d may transmit (e.g., forward) the request to base station 105-c (e.g., as further described herein, for example, with reference to communication diagram 300).

[0112] At 425, base station 105-c can determine a random access configuration for low-complexity UE 140-c. For example, based on this request, base station 105-c can determine the CFRA resource configuration for low-complexity UE 140-c. In some cases, the random access configuration can be based at least in part on a reason or condition of low-complexity UE 140-c that can be indicated by the request. In some cases, the random access configuration can be based at least in part on a preference for random access procedures that can be indicated by the request.

[0113] At 430, base station 105-c can transmit random access configuration (e.g., CFRA resource configuration). In some examples (e.g., at 430-a), base station 105-c can transmit the random access configuration to UE 115-d. In such examples, UE 115-d can forward the random access configuration to low-complexity UE 140-c at 432 (e.g., as further described herein with reference to communication diagram 301, for example). In other examples (e.g., at 430-b), base station 105-d can transmit the random access configuration directly to low-complexity UE 140-c (e.g., as further described herein with reference to communication diagram 303, for example). In yet another example, base station 105-b can transmit the random access configuration via some other UE 115 connected to low-complexity UE 140-c via a device-to-device link (e.g., as further described herein with reference to communication diagram 302, for example).

[0114] At 435, the low-complexity UE 140-c can perform random access procedures with base station 105-c based on the received random access configuration. For example, the low-complexity UE 140-c can perform CFRA procedures with base station 105-c based on the received CFRA configuration (e.g., base station 105-c can detect the RACH preamble at the random access timing, which is associated with the random access configuration determined at 425 and transmitted at 430).

[0115] Figure 5 A block diagram 500 of an apparatus 505 supporting an externally assisted random access channel protocol according to various aspects of this disclosure is shown. Apparatus 505 may be an example of various aspects of a UE 115 as described herein. Apparatus 505 may include a receiver 510, a communication manager 515, and a transmitter 520. Apparatus 505 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0116] Receiver 510 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to random access channel procedures with external assistance). The information can be transmitted to other components of device 505. Receiver 510 can be a reference... Figure 8 Examples of various aspects of the transceiver 820 described. The receiver 510 may utilize a single antenna or an array of antennas.

[0117] Communication manager 515 may: receive requests for contention-free random access resources from a first UE (e.g., from low-complexity UE 140) on a device-to-device link based on the low-power capability of the first UE, and communication manager 515 may forward the request to a base station based on the received request. Communication manager 515 may be an example of various aspects of communication manager 810 described herein.

[0118] The communication manager 515 or its sub-components may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functionality of the communication manager 515 or its sub-components may be performed by a general-purpose processor, DSP, application-specific integrated circuit (ASIC), FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described in this disclosure.

[0119] The communication manager 515 or its subcomponents may be physically located at various locations, including being distributed such that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of this disclosure, the communication manager 515 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of this disclosure, the communication manager 515 or its subcomponents may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in this disclosure, or combinations thereof.

[0120] Transmitter 520 can transmit signals generated by other components of device 505. In some examples, transmitter 520 may coexist with receiver 510 in a transceiver module. For example, transmitter 520 may be a reference... Figure 8 Examples of various aspects of the transceiver 820 described. The transmitter 520 may utilize a single antenna or an array of antennas.

[0121] Figure 6 A block diagram 600 of a device 605 supporting an externally assisted random access channel protocol according to various aspects of this disclosure is shown. Device 605 may be an example of aspects of device 505 or UE 115 as described herein. Device 605 may include a receiver 610, a communication manager 615, and a transmitter 625. Device 605 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0122] Receiver 610 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to random access channel procedures with external assistance). The information can be transmitted to other components of device 605. Receiver 610 can be a reference... Figure 8 Examples of various aspects of the transceiver 820 described. The receiver 610 may utilize a single antenna or an array of antennas.

[0123] Communication manager 615 may be an example of aspects of communication manager 515 as described herein. Communication manager 615 may include CFRA request manager 620. Communication manager 615 may be an example of aspects of communication manager 810 as described herein.

[0124] The CFRA request manager 620 can receive requests for contention-free random access resources from the first UE (e.g., from low-complexity UE 140) on a device-to-device link based on the low-power capability of the first UE, and the CFRA request manager 620 can transmit the request to the base station based on the received request.

[0125] Transmitter 625 can transmit signals generated by other components of device 605. In some examples, transmitter 625 may coexist with receiver 610 in a transceiver module. For example, transmitter 625 may be a reference... Figure 8 Examples of various aspects of the transceiver 820 described. The transmitter 625 may utilize a single antenna or an array of antennas.

[0126] Figure 7 A block diagram 700 is shown of a communication manager 705 supporting an externally assisted random access channel protocol according to various aspects of this disclosure. The communication manager 705 may be an example of aspects of the communication manager 515, communication manager 615, or communication manager 810 described herein. The communication manager 705 may include a CFRA request manager 710 and a CFRA configuration manager 715. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0127] The CFRA request manager 710 can receive requests for contention-free random access resources from a first UE (e.g., from a low-complexity UE 140) on a device-to-device link based on the first UE's low-power capabilities. In some examples, the CFRA request manager 710 can forward the request to a base station based on the received request. In some cases, the request includes an identifier of the first UE. In some cases, the identifier of the first UE includes the first UE's cellular radio network temporary identifier.

[0128] In some cases, the request includes an indication of a contention-based random access configuration for the first UE, a low-power capability for the first UE, the ability of the first UE to communicate with a second UE on a device-to-device link, or a combination thereof. In some cases, the request includes an indication of preferred random access resources for the first UE, a preferred random access preamble for the first UE, a preferred random access timing for the first UE, or a combination thereof. In some cases, the request includes one or more preferred synchronization block indices for the first UE, one or more channel state information reference signal resource identifiers for the first UE, or a combination thereof.

[0129] In some cases, the request includes an indication of whether the contention-free random access resource is used for a four-step random access channel procedure, a two-step random access channel procedure, or both. In some cases, the request includes an indication of conditions for the first UE. In some cases, the conditions include: initial access from idle mode conditions, a radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during uplink synchronization loss in connected mode without contention-free random access configured, uplink data arrival during uplink synchronization loss in connected mode without contention-free random access configured, uplink data arrival during connected mode when the physical uplink control channel resource for scheduling requests is unavailable, scheduling request failure, a request made by radio resource control during synchronization reconfiguration for handover without contention-free random access configured for handover, transition from the first UE's inactive mode, establishing time alignment for the sub-timing advance group, a request for other system information, beam failure recovery without contention-free random access configured for beam failure recovery, or a combination thereof.

[0130] The CFRA configuration manager 715 can receive a contention-free random access configuration from the base station based on a transmitted request. In some examples, the CFRA configuration manager 715 can transmit the contention-free random access configuration to a first UE over a device-to-device link. In some cases, the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof. In some cases, the contention-free random access configuration includes one or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, associated with the random access time resources, the random access frequency resources, the random access preamble, the random access timing, or a combination thereof. In some cases, the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

[0131] Figure 8 A block diagram of a system 800 including device 805 supporting a random access channel protocol with external assistance, according to various aspects of this disclosure, is shown. Device 805 may be an example of device 505, device 605, or UE 115 as described herein, or a component including device 505, device 605, or UE 115. Device 805 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 810, an I / O controller 815, a transceiver 820, an antenna 825, a memory 830, and a processor 840. These components may be in electronic communication via one or more buses (e.g., bus 845).

[0132] The communication manager 810 can: receive a request for contention-free random access resources from the first UE (e.g., from the low-complexity UE 140) on a device-to-device link based on the low-power capability of the first UE, and transmit the request to the base station based on the received request.

[0133] The I / O controller 815 manages the input and output signals of the device 805. The I / O controller 815 can also manage peripheral devices not integrated into the device 805. In some cases, the I / O controller 815 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 815 may utilize an operating system, such as... MS- MS- OS / Or another known operating system. In other cases, the I / O controller 815 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 815 may be implemented as part of a processor. In some cases, a user may interact with the device 805 via the I / O controller 815 or via hardware components controlled by the I / O controller 815.

[0134] Transceiver 820 can communicate bidirectionally via one or more antennas, wired or wireless links, as described above. For example, transceiver 820 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 820 may also include a modem to modulate packets and provide the modulated packets to the antenna for transmission, and to demodulate packets received from the antenna.

[0135] In some cases, a wireless device may include a single antenna 825. However, in other cases, the device may have more than one antenna 825, which may be able to transmit or receive multiple wireless transmissions concurrently.

[0136] Memory 830 may include RAM and ROM. Memory 830 may store computer-readable, computer-executable code or software 835, including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, memory 830 may, in particular, contain a BIOS that controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0137] Processor 840 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 840 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into processor 840. Processor 840 may be configured to execute computer-readable instructions stored in memory (e.g., memory 830) to cause device 805 to perform various functions (e.g., functions or tasks supporting random access channel protocols with external assistance).

[0138] Software 835 may include instructions for implementing various aspects of this disclosure, including instructions for supporting wireless communication. Software 835 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, software 835 may not be directly executed by processor 840, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0139] Figure 9 A block diagram 900 of a device 905 supporting an externally assisted random access channel protocol according to various aspects of this disclosure is shown. Device 905 may be an example of various aspects of a low-complexity UE 140 as described herein. Device 905 may include a receiver 910, a communication manager 915, and a transmitter 920. Device 905 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0140] Receiver 910 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to random access channel procedures with external assistance). The information can be transmitted to other components of device 905. Receiver 910 can be a reference... Figure 12 Examples of various aspects of the transceiver 1220 described. The receiver 910 may utilize a single antenna or an array of antennas.

[0141] Communication manager 915 may: transmit a request for contention-free random access resources to a second UE (e.g., UE 115) based on the low-power capability of a first UE (e.g., low-complexity UE 140); receive a contention-free random access configuration based on the request; and execute a contention-free random access procedure based on the received contention-free random access configuration. Communication manager 915 may be an example of various aspects of communication manager 1210 described herein.

[0142] The communication manager 915 or its sub-components may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functionality of the communication manager 915 or its sub-components may be performed by a general-purpose processor, DSP, application-specific integrated circuit (ASIC), FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

[0143] The communication manager 915 or its sub-components may be physically located at various locations, including being distributed such that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of this disclosure, the communication manager 915 or its sub-components may be separate and distinct components. In some examples, according to various aspects of this disclosure, the communication manager 915 or its sub-components may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in this disclosure, or combinations thereof.

[0144] Transmitter 920 can transmit signals generated by other components of device 905. In some examples, transmitter 920 may coexist with receiver 910 in a transceiver module. For example, transmitter 920 may be a reference... Figure 12 Examples of various aspects of the transceiver 1220 described. The transmitter 920 may utilize a single antenna or an array of antennas.

[0145] Figure 10 A block diagram 1000 of a device 1005 supporting an externally assisted random access channel protocol according to aspects of this disclosure is shown. Device 1005 may be an example of aspects of device 905 as described herein or a low-complexity UE 140. Device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1035. Device 1005 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0146] Receiver 1010 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to random access channel procedures with external assistance). The information can be transmitted to other components of device 1005. Receiver 1010 can be a reference... Figure 12 Examples of various aspects of the transceiver 1220 described herein. The receiver 1010 may utilize a single antenna or an array of antennas.

[0147] Communication manager 1015 may be an example of aspects of communication manager 915 as described herein. Communication manager 1015 may include: CFRA request manager 1020, CFRA configuration manager 1025, and CFRA procedure manager 1030. Communication manager 1015 may be an example of aspects of communication manager 1210 as described herein.

[0148] The CFRA request manager 1020 can transmit a request for contention-free random access resources to a second UE (e.g., UE 115) based on the low-power capability of the first UE (e.g., low-complexity UE 140). The CFRA configuration manager 1025 can receive a contention-free random access configuration based on the request. The CFRA procedure manager 1030 can execute a contention-free random access procedure with the base station based on the received contention-free random access configuration.

[0149] Transmitter 1035 can transmit signals generated by other components of device 1005. In some examples, transmitter 1035 may coexist with receiver 1010 in a transceiver module. For example, transmitter 1035 may be a reference... Figure 12 Examples of various aspects of the transceiver 1220 described. The transmitter 1035 may utilize a single antenna or an array of antennas.

[0150] Figure 11 A block diagram 1100 is shown of a communication manager 1105 supporting random access channel procedures with external assistance, according to various aspects of this disclosure. Communication manager 1105 may be an example of aspects of communication manager 915, communication manager 1015, or communication manager 1210 described herein. Communication manager 1105 may include: CFRA request manager 1110, CFRA configuration manager 1115, CFRA procedure manager 1120, and random access manager 1125. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0151] The CFRA request manager 1110 can transmit a request for contention-free random access resources to a second UE (e.g., UE 115) based on the low-power capabilities of a first UE (e.g., low-complexity UE 140). In some cases, the request includes an identifier of the first UE, and the first UE receives the contention-free random access configuration based on that identifier. In some cases, the identifier includes a temporary cellular radio network identifier of the first UE. In some cases, the request is transmitted over a device-to-device link with the second UE.

[0152] The CFRA configuration manager 1115 can receive a contention-free random access configuration based on this request. In some examples, the CFRA configuration manager 1115 can receive the contention-free random access configuration from a second UE. In some examples, the CFRA configuration manager 1115 can receive the contention-free random access configuration from the base station. In some examples, the CFRA configuration manager 1115 can receive the contention-free random access configuration from a third UE. In some cases, the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof.

[0153] In some cases, the contention-free random access configuration includes: one or more synchronization block indices, one or more channel state information reference resource identifiers, or a combination thereof, associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof. In some cases, the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

[0154] The CFRA procedure manager 1120 can execute a contention-free random access procedure with the base station based on the received contention-free random access configuration. In some examples, the CFRA procedure manager 1120 can transmit a random access channel preamble at the random access timing based on the received contention-free random access configuration.

[0155] The random access manager 1125 may determine whether to request the contention-free random access resource based on the contention-based random access configuration of the first UE, the low-power capability of the first UE, the first UE's ability to communicate with the second UE on a device-to-device link, or a combination thereof, wherein the request may be transmitted based on the determination. In some examples, a preferred random access resource, a preferred random access preamble, a preferred random access timing, or a combination thereof is determined, wherein the request includes an indication of the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof.

[0156] In some examples, one or more preferred synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof are determined to be associated with the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof, wherein the request includes the determined one or more preferred synchronization block indices, the one or more channel state information reference signal resource identifiers, or a combination thereof.

[0157] In some examples, the random access manager 1125 may determine whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both, wherein the request includes an indication of that determination. In some examples, the random access manager 1125 may determine whether to request the contention-free random access resource based on conditions of the first UE, wherein the request includes an indication of those conditions. In some cases, the request includes: an indication of a contention-based random access configuration for the first UE, a low-power capability of the first UE, the first UE's ability to communicate with a second UE on a device-to-device link, or a combination thereof.

[0158] In some cases, the condition includes: initial access from idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connected mode when uplink synchronization is lost without contention-free random access configured, uplink data arrival during connected mode when uplink synchronization is lost without contention-free random access configured, uplink data arrival during connected mode when physical uplink control channel resources for scheduling requests are unavailable, scheduling request failure, request made by radio resource control during synchronization reconfiguration for handover without contention-free random access configured for handover, transition from the first UE inactive mode, establishing time alignment for the sub-timing advance group, request for other system information, beam failure recovery without contention-free random access configured for beam failure recovery, or a combination thereof.

[0159] Figure 12 A block diagram of a system 1200 including device 1205 supporting a random access channel protocol with external assistance, according to various aspects of this disclosure, is shown. Device 1205 may be an example of device 905, device 1005, or a component of a device as described herein, or may include such components. Device 1205 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 1210, an I / O controller 1215, a transceiver 1220, an antenna 1225, a memory 1230, a processor 1240, and an encoding manager 1250. These components may be in electronic communication via one or more buses (e.g., bus 1245).

[0160] The communication manager 1210 can: transmit a request for contention-free random access resources to the second UE based on the low-power capability of the first UE, receive a contention-free random access configuration based on the request, and execute a contention-free random access procedure based on the received contention-free random access configuration.

[0161] I / O controller 1215 manages the input and output signals of device 1205. I / O controller 1215 can also manage peripheral devices not integrated into device 1205. In some cases, I / O controller 1215 may represent a physical connection or port to an external peripheral device. In some cases, I / O controller 1215 may utilize an operating system, such as... MS- MS- OS / Or another known operating system. In other cases, I / O controller 1215 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, I / O controller 1215 may be implemented as part of a processor. In some cases, a user may interact with device 1205 via I / O controller 1215 or via hardware components controlled by I / O controller 1215.

[0162] Transceiver 1220 can communicate bidirectionally via one or more antennas, wired or wireless links, as described above. For example, transceiver 1220 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 1220 may also include a modem to modulate packets and provide the modulated packets to the antenna for transmission, and to demodulate packets received from the antenna.

[0163] In some cases, the wireless device may include a single antenna 1225. However, in other cases, the device may have more than one antenna 1225, which may be able to transmit or receive multiple wireless transmissions concurrently.

[0164] Memory 1230 may include RAM and ROM. Memory 1230 may store computer-readable, computer-executable code or software 1235, including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, memory 1230 may, in particular, include a BIOS that controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0165] Processor 1240 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 1240 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into processor 1240. Processor 1240 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1230) to cause device 1205 to perform various functions (e.g., functions or tasks supporting random access channel protocols with external assistance).

[0166] Software 1235 may include instructions for implementing various aspects of this disclosure, including instructions for supporting wireless communication. Software 1235 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, software 1235 may not be directly executed by processor 1240, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0167] Figure 13 A flowchart illustrating a method 1300 supporting an externally assisted random access channel procedure according to various aspects of this disclosure is shown. The operation of method 1300 can be implemented by a low-complexity UE 140 or its components as described herein. For example, the operation of method 1300 can be implemented by, as referred to... Figures 9 to 12 The described communication manager is used for execution. In some examples, the low-complexity UE 140 can execute a set of instructions to control the functional elements of the low-complexity UE 140 to perform the following functions. Additionally or alternatively, the low-complexity UE 140 can use dedicated hardware to perform aspects of the following functions.

[0168] At 1305, the low-complexity UE 140 can transmit a request for contention-free random access resources to the second UE based on the low-power capability of the first UE. The operation of 1305 can be performed according to the methods described herein. In some examples, aspects of the operation of 1305 can be derived from, as referenced... Figures 9 to 12 The CFRA request manager described is used to execute this.

[0169] At 1310, the low-complexity UE 140 can receive a contention-free random access configuration based on this request. The operation of 1310 can be performed according to the methods described herein. In some examples, aspects of the operation of 1310 can be derived from, as referenced... Figures 9 to 12 The CFRA configuration manager is described and executed accordingly.

[0170] In 1315, the low-complexity UE 140 can execute a contention-free random access procedure with the base station based on the received contention-free random access configuration. The operation of 1315 can be performed according to the methods described herein. In some examples, aspects of the operation of 1315 can be determined by referring to... Figures 9 to 12 The CFRA procedure manager is described and executed accordingly.

[0171] Figure 14 A flowchart illustrating a method 1400 supporting an externally assisted random access channel procedure according to various aspects of this disclosure is shown. Operation of method 1400 can be implemented by a device or component thereof as described herein. For example, operation of method 1400 can be performed by, as referred to... Figures 9 to 12 The described communication manager is used for execution. In some examples, the device (e.g., low-complexity UE 140) can execute a set of instructions to control the functional elements of the device to perform the following functions. Additionally or alternatively, the device can use dedicated hardware to perform aspects of the following functions.

[0172] At 1405, the device may determine whether to request contention-free random access resources based on the contention-based random access configuration of the first UE, the low-power capability of the first UE, the capability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof, wherein the request is transmitted based on this determination. The operation of 1405 may be performed according to the methods described herein. In some examples, aspects of the operation of 1405 may be determined by reference to... Figures 9 to 12 The described random access manager is used to execute this.

[0173] At 1410, the device may, based on this determination, transmit a request for contention-free random access resources to the second UE. The operation of 1410 may be performed according to the methods described herein. In some examples, aspects of the operation of 1410 may be determined by reference to... Figures 9 to 12 The CFRA request manager described is used to execute this.

[0174] At 1415, the device can receive a contention-free random access configuration based on the request. The operation of 1415 can be performed according to the methods described herein. In some examples, aspects of the operation of 1415 can be derived from, as referenced... Figures 9 to 12 The CFRA configuration manager is described and executed accordingly.

[0175] At 1420, the device can execute a contention-free random access procedure with the base station based on the received contention-free random access configuration. The operation of 1420 can be performed according to the methods described herein. In some examples, aspects of the operation of 1420 can be determined by referring to... Figures 9 to 12 The CFRA procedure manager is described and executed accordingly.

[0176] Figure 15 A flowchart illustrating a method 1500 for supporting an externally assisted random access channel procedure according to various aspects of this disclosure is shown. Operation of method 1500 can be implemented by a UE 115 or its components as described herein. For example, operation of method 1500 can be implemented by, as referred to... Figures 5 to 8 The described communication manager is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the following functions. Alternatively or alternatively, the UE can use dedicated hardware to perform aspects of the following functions.

[0177] At 1505, the UE can receive requests for contention-free random access resources from the first UE on a device-to-device link based on the low-power capability of the first UE. The operation of 1505 can be performed according to the methods described herein. In some examples, aspects of the operation of 1505 can be determined by referring to... Figures 5 to 8 The CFRA request manager described is used to execute this.

[0178] At 1510, the UE can transmit the received request to the base station. The operation of 1510 can be performed according to the methods described herein. In some examples, aspects of the operation of 1510 can be determined by referring to... Figures 5 to 8 The CFRA request manager described is used to execute this.

[0179] Figure 16 A flowchart illustrating a method 1600 for supporting an externally assisted random access channel procedure according to various aspects of this disclosure is shown. Operation of method 1600 can be implemented by a UE 115 or its components as described herein. For example, operation of method 1600 can be performed by, as described in reference... Figures 5 to 8 The described communication manager is used to perform this function. In some examples, the UE can execute a set of instructions to control the functional elements of the UE to perform the following functions. Alternatively or alternatively, the UE can use dedicated hardware to perform aspects of the following functions.

[0180] At 1605, the UE can receive requests for contention-free random access resources from the first UE on a device-to-device link based on the low-power capability of the first UE. The operation of 1605 can be performed according to the methods described herein. In some examples, aspects of the operation of 1605 can be derived from, as referenced... Figures 5 to 8 The CFRA request manager described is used to execute this.

[0181] In 1610, the UE can transmit the received request to the base station. The operation of 1610 can be performed according to the methods described herein. In some examples, aspects of the operation of 1610 can be determined by referring to... Figures 5 to 8The CFRA request manager described is used to execute this.

[0182] In step 1615, the UE can receive a contention-free random access configuration from the base station based on a transmitted request. The operation of step 1615 can be performed according to the methods described herein. In some examples, aspects of the operation of step 1615 can be determined by referring to... Figures 5 to 8 The CFRA configuration manager is described and executed accordingly.

[0183] At 1620, the UE can transmit a contention-free random access configuration to the first UE on the device-to-device link. The operation of 1620 can be performed according to the methods described herein. In some examples, aspects of the operation of 1620 can be derived from, as referenced... Figures 5 to 8 The CFRA configuration manager is described and executed accordingly.

[0184] It should be noted that the methods described herein describe possible implementations, and the operations and steps can be rearranged or otherwise modified, and other implementations are also possible. Furthermore, aspects from two or more methods can be combined.

[0185] The techniques described in this article can be used in various wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and others. CDMA systems can implement radio technologies such as CDMA2000 and Universal Terrestrial Radio Access (UTRA). CDMA2000 encompasses the IS-2000, IS-95, and IS-856 standards. Versions of IS-2000 are often referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is often referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0186] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, 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 technologies described herein can be used with the systems and radio technologies mentioned herein, as well as with other systems and radio technologies. Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for illustrative purposes, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used in most of the descriptions, the techniques described herein may also be applied to applications beyond LTE, LTE-A, LTE-A Pro, or NR applications.

[0187] Macrocells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access by UEs with service subscriptions to a network provider. Small cells may be associated with lower-power base stations (compared to macrocells) and may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macrocells. Depending on the examples, small cells may include picocells, femtocells, and microcells. Picocells, for example, may cover a smaller geographic area and allow unrestricted access by UEs with service subscriptions to a network provider. Femtocells may also cover a smaller geographic area (e.g., a residential area) and provide restricted access by UEs associated with that femtocell (e.g., UEs in a closed subscriber group (CSG), UEs of users in that residence, etc.). An eNB used for a macrocell may be referred to as a macro eNB. An eNB used for a small cell may be referred to as a small cell eNB, pico eNB, femtocell eNB, or home eNB. eNB can support one or more (e.g., two, three, four, etc.) cells and can also support communication using one or more component carriers.

[0188] The wireless communication system described herein can support synchronous or asynchronous operation. For synchronous operation, base stations can have similar frame timings, and transmissions from different base stations can be approximately time-aligned. For asynchronous operation, base stations can have different frame timings, and transmissions from different base stations may not be time-aligned. The techniques described herein can be used for both synchronous and asynchronous operation.

[0189] The information and signals described herein can be represented using any of a wide variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout this description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0190] The various illustrative blocks and modules described herein can be implemented or executed using a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in alternatives, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other such configuration).

[0191] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored or transmitted as one or more instructions or code on a computer-readable medium. Other examples and implementations fall within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Features implementing the functions can also be physically located in various locations, including being distributed such that different parts of the function are implemented at different physical locations.

[0192] Computer-readable media includes both non-transient computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. Non-transient storage media can be any available medium accessible to a general-purpose or special-purpose computer. By way of example and not limitation, non-transient computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transient medium that can be used to carry or store desired program code in the form of instructions or data structures and is accessible to a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Similarly, any connection is also legitimately 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 microwave, then that coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used in this article, disk and disc include CDs, laser discs, optical discs, DVDs, floppy disks, and Blu-ray discs, where disks often magnetically reproduce data while discs optically reproduce data using lasers. Combinations of these media are also included within the scope of computer-readable media.

[0193] As used herein (including in the claims), the word "or" in an enumeration of items (e.g., an enumeration of items accompanied by phrases such as "at least one of" or "one or more of") indicates an inclusive enumeration, such that an enumeration of at least one of, for example, A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Similarly, as used herein, the phrase "based on" should not be construed as referencing a closed set of conditions. For example, an exemplary step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0194] In the accompanying drawings, similar components or features may have the same reference numerals. Furthermore, components of the same type may be distinguished by a dash following the reference numeral and a second reference numeral used to differentiate between similar components. If only the first reference numeral is used in the description, the description may apply to any of the similar components having the same first reference numeral, regardless of the second reference numeral or other subsequent reference numerals.

[0195] This document, illustrated with reference to the accompanying drawings, describes exemplary configurations but does not represent all examples that can be implemented or fall within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration" and does not mean "superior to" or "outperforms" other examples. This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may 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.

[0196] The description provided herein is intended to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the universal principles defined herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this 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.

Claims

1. A method for conducting wireless communication at a first user equipment (UE), comprising: The request for contention-free random access resources is transmitted to the second UE based at least in part on the low-power capability of the first UE. To receive a contention-free random access configuration at least in part based on the request; and The contention-free random access procedure with the network access node is executed at least in part based on the received contention-free random access configuration.

2. The method of claim 1, further comprising: The request for the contention-free random access resource is determined at least in part based on the contention-based random access configuration of the first UE, the low-power capability of the first UE, the ability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof, wherein the request is transmitted at least in part based on the determination.

3. The method of claim 2, wherein the request includes an indication of the contention-based random access configuration of the first UE, the low-power capability of the first UE, the capability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof.

4. The method of claim 1, wherein receiving the contention-free random access configuration includes: Receive the contention-free random access configuration from the second UE.

5. The method of claim 1, wherein receiving the contention-free random access configuration comprises: Receive the contention-free random access configuration from the network access node.

6. The method of claim 1, wherein receiving the contention-free random access configuration comprises: Receive the contention-free random access configuration from the third UE.

7. The method of claim 1, wherein the request includes an identifier of the first UE, and the contention-free random access configuration is received by the first UE at least in part based on the identifier.

8. The method of claim 7, wherein the identifier includes the cellular radio network temporary identifier of the first UE.

9. The method of claim 1, wherein the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof.

10. The method of claim 9, wherein the contention-free random access configuration includes: One or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, are associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof.

11. The method of claim 1, further comprising: Determine a preferred random access resource, a preferred random access preamble, a preferred random access timing, or a combination thereof, wherein the request includes an indication of the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof.

12. The method of claim 11, further comprising: The request includes determining one or more preferred synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof associated with the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof, wherein the request includes the determined one or more preferred synchronization block indices, the one or more channel state information reference signal resource identifiers, or a combination thereof.

13. The method of claim 1, further comprising: Determine whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both, wherein the request includes an indication of the determination.

14. The method of claim 1, wherein the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

15. The method of claim 1, wherein executing the contention-free random access procedure with the network access node comprises: The random access channel preamble is transmitted at the random access time, at least in part, based on the received contention-free random access configuration.

16. The method of claim 1, further comprising: The determination to request the contention-free random access resource is based at least in part on conditions of the first UE, wherein the request includes an indication of the conditions.

17. The method of claim 16, wherein the conditions include: The following are possible events: initial access under idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of unavailable physical uplink control channel resources for scheduling requests, scheduling request failure, requests made by radio resource control during synchronization reconfiguration for handover without contention-free random access for handover, transition from the first UE inactive mode, establishing time alignment for the secondary timing advance group, requests for other system information, beam failure recovery without contention-free random access for beam failure recovery, or a combination thereof.

18. The method of claim 1, wherein the request is transmitted on a device-to-device link with the second UE.

19. A method for conducting wireless communication at a second user equipment (UE), comprising: At least in part, the low-power capability of the first UE is used to receive requests for contention-free random access resources from the first UE on the device-to-device link; as well as The request is transmitted to the network access node based at least in part on the received request.

20. The method of claim 19, further comprising: The contention-free random access configuration is received from the network access node based at least in part on the transmitted request; as well as The contention-free random access configuration is transmitted to the first UE on the device-to-device link.

21. The method of claim 20, wherein the request includes the identifier of the first UE.

22. The method of claim 21, wherein the identifier of the first UE includes the cellular radio network temporary identifier of the first UE.

23. The method of claim 20, wherein the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof.

24. The method of claim 23, wherein the contention-free random access configuration comprises: One or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, are associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof.

25. The method of claim 19, wherein the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

26. The method of claim 19, wherein the request includes an indication of a contention-based random access configuration for the first UE, the low-power capability of the first UE, the capability of the first UE to communicate with the second UE on the device-to-device link, or a combination thereof.

27. The method of claim 19, wherein the request comprises: Indication of preferred random access resources for the first UE, preferred random access preamble for the first UE, preferred random access timing for the first UE, or a combination thereof.

28. The method of claim 27, wherein the request comprises: One or more preferred synchronization signal block indices for the first UE, one or more channel state information reference signal resource identifiers for the first UE, or a combination thereof.

29. The method of claim 19, wherein the request includes an indication of whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

30. The method of claim 19, wherein the request includes an indication of conditions for the first UE.

31. The method of claim 30, wherein the conditions include: The following are possible events: initial access under idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of unavailable physical uplink control channel resources for scheduling requests, scheduling request failure, requests made by radio resource control during synchronization reconfiguration for handover without contention-free random access for handover, transition from the first UE inactive mode, establishing time alignment for the secondary timing advance group, requests for other system information, beam failure recovery without contention-free random access for beam failure recovery, or a combination thereof.

32. An apparatus for performing wireless communication at a first user equipment (UE), comprising: processor; Memory coupled to the processor; as well as Instructions, which are stored in the memory and can be executed by the processor, to cause the device to: The request for contention-free random access resources is transmitted to the second UE based at least in part on the low-power capability of the first UE. To receive a contention-free random access configuration at least in part based on the request; and The contention-free random access procedure with the network access node is executed at least in part based on the received contention-free random access configuration.

33. The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to: The request for the contention-free random access resource is determined at least in part based on the contention-based random access configuration of the first UE, the low-power capability of the first UE, the ability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof, wherein the request is transmitted at least in part based on the determination.

34. The apparatus of claim 33, wherein the request includes an indication of the contention-based random access configuration of the first UE, the low-power capability of the first UE, the capability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof.

35. The apparatus of claim 32, wherein the instructions for receiving the contention-free random access configuration are executable by the processor to cause the apparatus to: Receive the contention-free random access configuration from the second UE.

36. The apparatus of claim 32, wherein the instructions for receiving the contention-free random access configuration are executable by the processor to cause the apparatus to: Receive the contention-free random access configuration from the network access node.

37. The apparatus of claim 32, wherein the instructions for receiving the contention-free random access configuration are executable by the processor to cause the apparatus to: Receive the contention-free random access configuration from the third UE.

38. The apparatus of claim 32, wherein the request includes an identifier of the first UE, and the contention-free random access configuration is received by the first UE at least in part based on the identifier.

39. The apparatus of claim 38, wherein the identifier includes a temporary cellular radio network identifier of the first UE.

40. The apparatus of claim 32, wherein the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof.

41. The apparatus of claim 40, wherein the contention-free random access configuration comprises: One or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, are associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof.

42. The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to: Determine a preferred random access resource, a preferred random access preamble, a preferred random access timing, or a combination thereof, wherein the request includes an indication of the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof.

43. The apparatus of claim 42, wherein the instructions are further executable by the processor to cause the apparatus to: The request includes determining one or more preferred synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof associated with the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof, wherein the request includes the determined one or more preferred synchronization block indices, the one or more channel state information reference signal resource identifiers, or a combination thereof.

44. The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to: Determine whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both, wherein the request includes an indication of the determination.

45. The apparatus of claim 32, wherein the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

46. ​​The apparatus of claim 32, wherein the instructions for performing the contention-free random access procedure with the network access node are executable by the processor to cause the apparatus to: The random access channel preamble is transmitted at the random access time, at least in part, based on the received contention-free random access configuration.

47. The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to: The determination to request the contention-free random access resource is based at least in part on conditions of the first UE, wherein the request includes an indication of the conditions.

48. The apparatus of claim 47, wherein the conditions include: The following are possible events: initial access under idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of unavailable physical uplink control channel resources for scheduling requests, scheduling request failure, requests made by radio resource control during synchronization reconfiguration for handover without contention-free random access for handover, transition from the first UE inactive mode, establishing time alignment for the secondary timing advance group, requests for other system information, beam failure recovery without contention-free random access for beam failure recovery, or a combination thereof.

49. The apparatus of claim 32, wherein the request is transmitted on a device-to-device link with the second UE.

50. An apparatus for wireless communication at a second user equipment (UE), comprising: processor; Memory coupled to the processor; as well as Instructions, which are stored in the memory and can be executed by the processor, to cause the device to: At least in part, the low-power capability of the first UE is used to receive requests for contention-free random access resources from the first UE on the device-to-device link; as well as The request is transmitted to the network access node based at least in part on the received request.

51. The apparatus of claim 50, wherein the instructions are further executable by the processor to cause the apparatus to: Receive contention-free random access configuration from the network access node at least in part based on the transmitted request; and The contention-free random access configuration is transmitted to the first UE on the device-to-device link.

52. The apparatus of claim 51, wherein the request includes an identifier of the first UE.

53. The apparatus of claim 52, wherein the identifier of the first UE includes a temporary cellular radio network identifier of the first UE.

54. The apparatus of claim 51, wherein the contention-free random access configuration includes random access time resources, random access frequency resources, random access preamble, random access timing, or a combination thereof.

55. The apparatus of claim 54, wherein the contention-free random access configuration comprises: One or more synchronization block indices, one or more channel state information reference signal resource identifiers, or a combination thereof, are associated with the random access time resource, the random access frequency resource, the random access preamble, the random access timing, or a combination thereof.

56. The apparatus of claim 50, wherein the contention-free random access configuration includes an indication of whether the contention-free random access configuration is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

57. The apparatus of claim 50, wherein the request includes an indication of a contention-based random access configuration for the first UE, the low-power capability of the first UE, the capability of the first UE to communicate with the second UE on the device-to-device link, or a combination thereof.

58. The apparatus of claim 50, wherein the request includes: Indication of preferred random access resources for the first UE, preferred random access preamble for the first UE, preferred random access timing for the first UE, or a combination thereof.

59. The apparatus of claim 58, wherein the request includes: One or more preferred synchronization signal block indices for the first UE, one or more channel state information reference signal resource identifiers for the first UE, or a combination thereof.

60. The apparatus of claim 50, wherein the request includes an indication of whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both.

61. The apparatus of claim 50, wherein the request includes an indication of conditions for the first UE.

62. The apparatus of claim 61, wherein the conditions include: The following are possible events: initial access under idle mode conditions, radio resource connection re-establishment procedure for radio link failure recovery, downlink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of uplink synchronization loss without contention-free random access, uplink data arrival during connected mode in case of unavailable physical uplink control channel resources for scheduling requests, scheduling request failure, requests made by radio resource control during synchronization reconfiguration for handover without contention-free random access for handover, transition from the first UE inactive mode, establishing time alignment for the secondary timing advance group, requests for other system information, beam failure recovery without contention-free random access for beam failure recovery, or a combination thereof.

63. An apparatus for performing wireless communication at a first user equipment (UE), comprising: A means for transmitting a request for contention-free random access resources to a second UE based at least in part on the low-power capability of the first UE; A means for receiving a contention-free random access configuration based at least in part on the request; as well as A means for executing a contention-free random access procedure with a network access node, at least in part based on a received contention-free random access configuration.

64. The apparatus of claim 63, further comprising: A means for determining, at least in part, to request the contention-free random access resource based on the contention-based random access configuration of the first UE, the low-power capability of the first UE, the ability of the first UE to communicate with the second UE on a device-to-device link, or a combination thereof, wherein the request is transmitted at least in part based on the determination.

65. The apparatus of claim 63, wherein the means for receiving the contention-free random access configuration comprises: A means for receiving the contention-free random access configuration from the second UE.

66. The apparatus of claim 63, wherein the means for receiving the contention-free random access configuration comprises: A means for receiving the contention-free random access configuration from the network access node.

67. The apparatus of claim 63, wherein the means for receiving the contention-free random access configuration comprises: A means for receiving the contention-free random access configuration from a third UE.

68. The apparatus of claim 63, further comprising: A means for determining a preferred random access resource, a preferred random access preamble, a preferred random access timing, or a combination thereof, wherein the request includes an indication of the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof.

69. The apparatus of claim 68, further comprising: A means for determining one or more preferred synchronization block indices, one or more channel state information reference resource identifiers, or a combination thereof, associated with the preferred random access resource, the preferred random access preamble, the preferred random access timing, or a combination thereof, wherein the request includes the determined one or more preferred synchronization block indices, the one or more channel state information reference resource identifiers, or a combination thereof.

70. The apparatus of claim 63, further comprising: A means for determining whether the contention-free random access resource is for a four-step random access channel procedure, a two-step random access channel procedure, or both, wherein the request includes an indication of the determination.

71. The apparatus of claim 63, wherein the means for executing the contention-free random access procedure with the network access node comprises: A means for transmitting a random access channel preamble at random access time based at least in part on a received contention-free random access configuration.

72. The apparatus of claim 63, further comprising: A means for determining, at least in part, to request the contention-free random access resource based on conditions of the first UE, wherein the request includes an indication of the conditions.

73. An apparatus for wireless communication at a second user equipment (UE), comprising: A means for receiving a request for contention-free random access resources from a first UE on a device-to-device link, based at least in part on the low-power capability of the first UE. as well as A means for transmitting a request to a network access node based at least in part on a received request.

74. A non-transient computer-readable medium storing code for wireless communication at a first user equipment (UE), the code including instructions executable by a processor for the following operations: The request for contention-free random access resources is transmitted to the second UE based at least in part on the low-power capability of the first UE. To receive a contention-free random access configuration at least in part based on the request; and The contention-free random access procedure with the network access node is executed at least in part based on the received contention-free random access configuration.

75. A non-transient computer-readable medium storing code for wireless communication at a second user equipment (UE), said code including instructions executable by a processor for the following operations: At least in part, based on the low-power capability of the first UE, requests for contention-free random access resources are received from the first UE on a device-to-device link; and The request is transmitted to the network access node based at least in part on the received request.

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