Resource selection under congestion conditions

Abstract

Methods, systems, and devices are described for wireless communication. A user equipment (UE) can identify a message to be transmitted over a wireless channel, such as a vehicle-to-everything (V2X) system. The UE can determine a channel reservation limit for reserving resources for the message on the wireless channel based on a channel busy ratio of the wireless channel. The UE can determine that available resources are insufficient for an initial transmission of the message and a retransmission of the message based on the channel reservation limit. The UE can reserve resources for the initial transmission of the message on the wireless channel based on the available resources being insufficient for the initial transmission of the message and the retransmission of the message.

Description

[0001] Cross-reference of related applications

[0002] This patent application claims the benefit of International Patent Application No. PCT / CN2020 / 117057 entitled “RESOURCE SELECTIONUNDER CONGESTED CONDITIONS” filed by Yin et al. on September 23, 2020, which has been assigned to its assignee and whose entire contents are expressly incorporated herein by reference. Technical Field

[0003] The following pertains to wireless communications, including resource selection under congestion conditions. Background Technology

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, and broadcasting. These systems can support communication with multiple users by sharing 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), LTE-A Advanced (LTE-A), or LTE-A Pro systems, and fifth-generation (5G) systems, which may 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 Extended Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each supporting communication with multiple communication devices simultaneously, which may also be referred to as User Equipment (UE).

[0005] In some wireless communication systems, such as vehicle-to-everything (V2X) systems, the UE can reserve resources on the wireless channel to send messages. Summary of the Invention

[0006] The technology relates to improved methods, systems, devices, and apparatuses for supporting resource selection under congestion conditions. Typically, the technology provides efficient reservation of wireless resources in wireless communication systems, such as vehicle-to-everything (V2X) wireless communication systems. In some V2X wireless communication systems, V2X devices, such as vehicle user equipment (UE), can reserve resources for communication on V2X wireless channels. In some V2X wireless communication systems, V2X devices can be restricted to reserving a certain amount of resources on a wireless channel based on the channel busy rate (CBR). The wireless communication system described herein supports techniques for UEs to improve spectral efficiency and reduce packet error loss when channel reservation restrictions exist. For example, when a UE has a message to send on a V2X wireless channel, the UE can determine the CBR of the wireless channel and determine a channel reservation restriction based on that CBR. If the UE is restricted to a certain amount of available resources such that the UE cannot reserve sufficient resources for initial transmissions and retransmissions, the UE can choose not to reserve resources for retransmissions. The UE can then reserve resources for the initial transmission, and the UE can use the resources reserved for the initial transmission to send application packets.

[0007] A method for wireless communication at a UE is described. The method may include identifying a message to be transmitted on a wireless channel; determining a channel reservation limit for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel; determining, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and reserving resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0008] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions, executable by the processor, cause the apparatus to identify a message to be transmitted on a wireless channel; determine a channel reservation limit for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel; determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and reserve resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0009] Another apparatus for wireless communication at a UE is described. The apparatus may include components for identifying a message to be transmitted on a wireless channel; components for determining a channel reservation limit for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel; components for determining, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and components for reserving resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0010] A non-transitory computer-readable medium is described, storing code for wireless communication at a UE. The code may include processor-executable instructions to identify a message to be transmitted on a wireless channel; determine, based on the channel busy rate of the wireless channel, a channel reservation limit for reserving resources on the wireless channel for the message; determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and reserve resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0011] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, determining that available resources may be insufficient may include operations, features, components, or instructions for performing the following: determining the number of available sub-channels for a message based on channel reservation limits, and determining that the number of available sub-channels may be insufficient for the initial transmission and retransmission of the message.

[0012] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, determining that available resources may be insufficient may include operations, features, components, or instructions for determining the number of available sub-channels for the message based on authorized resources for one or more event-driven transmissions.

[0013] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, determining that available resources may be insufficient may include operations, features, components, or instructions for determining the number of available sub-channels for the message based on channel occupancy within a channel occupancy assessment window, which includes a first portion of past resources and a second portion of future resources.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, determining that available resources may be insufficient may include operations, features, components, or instructions for performing the following: determining a first number of available sub-channels for the message based on a first channel reservation limit; determining that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; determining a second number of available sub-channels for the message based on a second channel reservation limit and the insufficiency of the first number of available sub-channels; and determining that the second number of available sub-channels is insufficient for the initial transmission and retransmission of the message, but sufficient for the initial transmission of the message.

[0015] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for determining the channel busy rate of a wireless channel based on a received signal strength indicator measurement of that wireless channel.

[0016] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the channel reservation limit may be based on the message priority.

[0017] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the channel reservation limit corresponds to the number of sub-channels that a wireless device may reserve for transmission over a period of time.

[0018] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, available resources can be determined based on the duration of a semi-persistent scheduling period and channel reservation constraints.

[0019] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions for performing operations that avoid reserving retransmission resources based on the determination that available resources may be insufficient.

[0020] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the wireless channel includes a V2X channel. Attached Figure Description

[0021] Figure 1 Examples of wireless communication systems that support resource selection under congestion conditions are shown in accordance with various aspects of this disclosure.

[0022] Figure 2 Examples of wireless communication systems that support resource selection under congestion conditions are shown in accordance with various aspects of this disclosure.

[0023] Figure 3 Examples of process flows supporting resource selection under congestion conditions are shown, according to various aspects of this disclosure.

[0024] Figure 4 and Figure 5 A block diagram of a device that supports resource selection under congestion conditions, according to various aspects of this disclosure, is shown.

[0025] Figure 6 A block diagram of a communication manager that supports resource selection under congestion conditions is shown, according to various aspects of this disclosure.

[0026] Figure 7 A diagram of a system, including devices supporting resource selection under congestion conditions, is shown according to various aspects of this disclosure.

[0027] Figure 8 and Figure 9 A flowchart illustrating a method for supporting resource selection under congestion conditions is shown, according to various aspects of this disclosure. Detailed Implementation

[0028] Some wireless communication systems support vehicle-to-everything (V2X) communication. In some V2X wireless communication systems, V2X devices, such as vehicle user equipment (UE), can reserve resources for communication on the V2X wireless channel. In some V2X wireless communication systems, the V2X device can be restricted to reserving a certain number of resources on the wireless channel based on the channel busy rate (CBR). For example, if the CBR is between 60% and 80%, the V2X UE can be restricted to reserving a maximum of 30 sub-channels on the V2X wireless channel to transmit an application packet. The V2X UE can attempt to reserve resources for the initial transmission and retransmission of the application packet using these 30 sub-channels. However, in some cases, the application packet may use more resources than the limited number of sub-channels to schedule the initial transmission and retransmission. Therefore, the V2X UE can attempt to schedule and transmit the initial transmission and retransmission, but there may only be enough resources on the channel for the complete transmission of the initial transmission. In busy channels, requiring the UE to schedule resources for both initial transmission and retransmission simultaneously when available resources are limited can degrade performance.

[0029] If insufficient resources are available for initial transmission and retransmission, the wireless communication system described herein supports techniques for the UE to ensure reliable initial transmission. For example, when the UE has a message (e.g., application packets) to send on a V2X wireless channel, the UE can determine the Channel Reservation Limit (CBR) of the wireless channel and determine channel reservation limits based on that CBR. If the UE is limited to a certain amount of available resources, making it impossible for the UE to reserve sufficient resources for initial transmission and retransmission, the UE can choose not to reserve resources for retransmission to ensure reliable initial transmission and reduce packet loss due to partial retransmission. The UE can then reserve resources for initial transmission, and the UE can use the resources allocated for initial transmission to send application packets.

[0030] The various aspects of this disclosure are first described in the context of a wireless communication system. These aspects are further illustrated and described by apparatus diagrams, system diagrams, and flowcharts relating to resource selection under congestion conditions.

[0031] Figure 1 Examples of a wireless communication system 100 supporting resource selection under congestion conditions are illustrated according to various aspects of this disclosure. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low-latency communication, communication with low-cost and low-complexity devices, or any combination thereof.

[0032] Base stations 105 can be distributed throughout a geographical area to form the wireless communication system 100, and can be devices of different forms or with different capabilities. Base stations 105 and UE 115 can communicate wirelessly via one or more communication links 125. Each base station 105 can provide a coverage area 110, on which UE 115 and base station 105 can establish one or more communication links 125. The coverage area 110 can be an example of a geographical area where base stations 105 and UE 115 can support signal communication according to one or more radio access technologies.

[0033] UE 115 can be distributed throughout the entire coverage area 110 of the wireless communication system 100, and each UE 115 can be stationary, mobile, or both at different times. UE 115 can be devices with different forms or different capabilities. Figure 1Some example UE 115s are shown in the document. The UE 115 described herein is capable of communicating with various types of devices, such as other UE 115s, base station 105, or network devices (e.g., core network nodes, relay devices, access backhaul integrated (IAB) nodes, or another network device), such as... Figure 1 As shown.

[0034] Base station 105 can communicate with the core network 130, or with each other, or with both simultaneously. For example, base station 105 can be connected to the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). Base station 105 can communicate with each other directly (e.g., directly between base stations 105) or indirectly (e.g., via the core network 130) or simultaneously via both methods through the backhaul link 120 (e.g., via X2, Xn, or other interfaces). In some examples, the backhaul link 120 can be or includes one or more radio links.

[0035] One or more base stations 105 described herein may include, or may be referred to by those skilled in the art as, base station, radio base station, access point, radio transceiver, NodeB, eNodeB (eNB), next-generation NodeB or giga-NodeB (both may be referred to as gNB), home NodeB, home eNodeB or other suitable terms.

[0036] In other examples, UE 115 may include or be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or some other suitable term, wherein "device" may also be referred to as a unit, station, terminal, or client. UE 115 may also include or be referred to as 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 include or be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine-type communication (MTC) device, etc., which may be implemented in various objects such as appliances, or vehicles, meters, etc.

[0037] The UE 115 described herein can communicate with various types of devices, such as other UEs 115 that can sometimes act as relays, as well as base station 105 and network devices, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, etc. Figure 1 As shown.

[0038] UE 115 and base station 105 can wirelessly communicate with each other via one or more carriers through one or more communication links 125. The term "carrier" can refer to a set of radio spectrum resources with a defined physical layer structure used to support communication link 125. For example, a carrier for communication link 125 may include a radio spectrum band (e.g., a portion of a bandwidth portion (BWP)) operating under one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating carrier operation, user data, or other signaling. The wireless communication system 100 can use carrier aggregation or multi-carrier operation to support communication with UE 115. Depending on the carrier aggregation configuration, UE 115 can be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation can be used with frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0039] In some examples (e.g., in a carrier aggregation configuration), the carrier may also have acquisition signaling or control signaling to coordinate the operation of other carriers. The carrier may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and can be located according to a channel grating for discovery by UE 115. The carrier may operate in standalone mode, where initial acquisition and connection can be performed by UE 115 via the carrier, or the carrier may operate in non-standalone mode, where connections are anchored using different carriers (e.g., the same or different radio access technologies).

[0040] The communication link 125 shown in the wireless communication system 100 may include uplink transmission from UE 115 to base station 105, or downlink transmission from base station 105 to UE 115. The carrier may carry downlink or uplink communication (e.g., in FDD mode), or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0041] A carrier can be associated with a specific bandwidth of the radio spectrum, and in some examples, the carrier bandwidth can be referred to as the carrier or the “system bandwidth” of the wireless communication system 100. For example, the carrier bandwidth can be one of several defined bandwidths of a carrier used for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). The devices of the wireless communication system 100 (e.g., the base station 105, the UE 115, or both) can have hardware configurations that support communication on a specific carrier bandwidth, or can be configured to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 or UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 can be configured to operate on a portion (e.g., a subband, BWP) or all of the carrier bandwidth.

[0042] The signal waveform transmitted on a carrier can consist of multiple subcarriers (e.g., using multicarrier modulation (MCM) techniques such as Orthogonal Frequency Division Multiplexing (OFDM) or Discrete Fourier Transform Extended OFDM (DFT-S-OFDM). In a system employing MCM, a resource element can include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and subcarrier spacing are inversely correlated. The number of bits carried by each resource element can depend on the modulation scheme (e.g., the order of the modulation scheme, the decoding rate of the modulation scheme, or both). Therefore, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate of the UE 115 can be. Wireless communication resources can refer to a combination of radio spectrum resources, temporal resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers can further improve the data rate or data integrity for communication with the UE 115.

[0043] One or more numbers can be supported for a carrier, where the numbers may include the subcarrier spacing (Δf) and a cyclic prefix. A carrier can be divided into one or more BWPs with the same or different numbers. In some examples, the UE115 can be configured with multiple BWPs. In some examples, a single BWP of a carrier can be active at a given time, and the communication of the UE115 may be limited to one or more active BWPs.

[0044] The time interval of the base station 105 or the UE 115 can be expressed as a multiple of a basic time unit, for example, the basic time unit can refer to T. s =1 / (Δf) max ·N f The sampling period is ) seconds, where Δf maxThis can represent the maximum supported subcarrier spacing, and N f This can represent the maximum supported Discrete Fourier Transform (DFT) size. Communication resources can be organized into time intervals based on radio frames, each with a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a System Frame Number (SFN), ranging from 0 to 1023.

[0045] Each frame may comprise multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided into subframes (e.g., in the time domain), and each subframe may be further divided into multiple time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include multiple symbol periods (e.g., depending on the length of the cyclic prefix appended to each symbol period). In some wireless communication systems 100, time slots may be further divided into multiple micro-time slots containing one or more symbols. In addition to the cyclic prefix, each symbol period may contain one or more (e.g., N) f Sampling period. The duration of the symbol period can depend on the subcarrier spacing or the operating frequency band.

[0046] A subframe, time slot, micro-time slot, or symbol can be the smallest scheduling unit of the wireless communication system 100 (e.g., in the time domain) and can be referred to as a transmission time interval (TTI). In some examples, the duration of the TTI (e.g., the number of symbol cycles in the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 can be dynamically selected (e.g., in a burst of shortened TTIs (sTTIs)).

[0047] Physical channels can be multiplexed on a carrier using various techniques. For example, one or more Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), or hybrid TDM-FDM techniques can be used to multiplex physical control channels and physical data channels on a downlink carrier. The control region of a physical control channel (e.g., a control resource set (CORESET)) can be defined by multiple symbol periods and can span a subgroup of system bandwidth or a carrier. One or more control regions (e.g., CORESETs) can be configured for a set of UEs 115. For example, one or more UEs in UE 115 can monitor or search for control regions for control information based on one or more search space sets, and each search space set can include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level of control channel candidates can refer to multiple control channel resources (e.g., control channel elements (CCEs)) associated with encoded information in a control information format with a given payload size. The search space set can include a common search space set configured to transmit control information to multiple UEs 115, and a UE-specific search space set for transmitting control information to a specific UE 115.

[0048] Each base station 105 may provide communication coverage via one or more cells, such as macro cells, small cells, hotspots, or other types of cells, or any combination thereof. The term "cell" may refer to a logical communication entity used to communicate with base station 105 (e.g., via a carrier) and may be associated with an identifier used to distinguish neighboring cells (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID), or others). In some examples, a cell may also refer to a geographic coverage area 110 or a portion of geographic coverage area 110 (e.g., a sector) on which a logical communication entity operates. Depending on various factors such as the capabilities of base station 105, the range of such cells can vary from small areas (e.g., structures, subsets of structures) to large areas. For example, a cell may be or include buildings, subsets of buildings, external space between or overlapping geographic coverage areas 110, etc.

[0049] Macro cells typically cover a relatively large geographical area (e.g., a radius of several kilometers) and can allow unrestricted access for UE 115 with a service subscription from a network provider supporting the macro cell. In contrast, small cells can be associated with a lower-power base station 105 and can operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macro cells. Small cells can provide unrestricted access to UE 115 with a service subscription from a network provider, or restricted access to UE 115 associated with a small cell (e.g., UE 115 in a Closed Subscriber Group (CSG), UE 115 associated with a user at home or office, etc.). Base station 105 can support one or more cells and can also support communication on one or more cells using one or more component carriers.

[0050] In some examples, operators can support multiple cells and configure different cells based on different protocol types that can provide access for different types of devices (e.g., MTC, Narrowband IoT (NB-IoT), Enhanced Mobile Broadband (eMBB)).

[0051] In some examples, base station 105 may be mobile, thus providing communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but can be supported by the same base station 105. In other examples, different base stations 105 may support overlapping geographic coverage areas 110 associated with different technologies. Wireless communication system 100 may include, for example, a heterogeneous network, in which different types of base stations 105 use the same or different radio access technologies to provide coverage for various geographic coverage areas 110.

[0052] The wireless communication system 100 can support synchronous or asynchronous operation. For synchronous operation, the base station 105 can have similar frame timing, and transmissions from different base stations 105 can be approximately aligned in time. For asynchronous operation, the base station 105 can have different frame timing, and in some examples, transmissions from different base stations 105 can be misaligned in time. The techniques described herein can be used for both synchronous and asynchronous operation.

[0053] Some UE 115s, such as MTC or IoT devices, can be low-cost or low-complexity devices that 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 can include communication from a device that integrates sensors or meters to measure or capture information and forward such information to a central server or application that uses the information or presents it to humans interacting with the application. Some UE 115s can be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based service charging.

[0054] Some UE 115s can be configured to operate in reduced power consumption 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, operating on limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UE 115s can be configured to operate using a narrowband protocol type associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a carrier's guard band, or outside a carrier.

[0055] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. The UE 115 can be designed to support ultra-reliable, low-latency, or mission-critical functions (e.g., mission-critical functions). Ultra-reliable communication may include private or group communication and may be supported by one or more mission-critical services, such as Mission-Critical Push-to-Talk (MCPTT), Mission-Critical Video (MCVideo), or Mission-Critical Data (MCData). Support for mission-critical functions may include service prioritization, and mission-critical services may be used for public safety or general business applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency are used interchangeably herein.

[0056] In some cases, UE 115 may also be able to communicate directly with other UE 115 via device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UE 115s utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other UE 115s in such a group may be outside the geographic coverage area 110 of base station 105 or otherwise unable to receive transmissions from base station 105. In some examples, the group of UE 115s communicating via D2D communication may utilize a one-to-many (1:M) system, where each UE 115 sends to every other UE 115 in the group. In some examples, base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication between UE 115s is performed without the involvement of base station 105.

[0057] In some systems, the D2D communication link 135 may be an example of a communication channel between vehicles (e.g., UE 115), such as a sidelink communication channel. In some examples, vehicles may communicate using V2X communication, vehicle-to-vehicle (V2V) communication, or some combination thereof. Vehicles may use signals to notify information related to traffic conditions, signal control, weather, safety, emergencies, or any other information relevant to the V2X system. In some examples, vehicles in a V2X system may use vehicle-to-network (V2N) communication to communicate with roadside infrastructure (such as roadside units) or with the network, or both, via one or more network nodes (e.g., base station 105).

[0058] Core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. Core network 130 can be an evolved packet core (EPC) or a 5G core (5GC), and can include at least one control plane entity (e.g., a Mobility Management Entity (MME), Access and Mobility Management Function (AMF)) managing access and mobility, and at least one user plane entity (e.g., a Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), User Plane Function (UPF)) routing packets or interconnecting to external networks. The control plane entity can manage non-access stratum (NAS) functions of UE 115 served by base station 105 associated with core network 130, such as mobility, authentication, and payload management. User IP packets can be transmitted through the user plane entity, which can provide IP address allocation and other functions. The user plane entity can connect to one or more network operator IP services 150. IP services 150 can include access to the Internet, intranets, IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0059] Some network devices, such as base station 105, may include sub-components such as access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with UE 115 through one or more other access network transport entities 145, which may be referred to as a radio head, smart radio head, or transmit / receive point (TRP). Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or combined into a single network device (e.g., base station 105).

[0060] Wireless communication system 100 can operate using one or more frequency bands typically in the range of 300 Hz (MHz) to 300 GHz (GHz). The region from 300 MHz to 3 GHz is generally referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelength range is from approximately 1 decimeter to 1 meter. UHF waves may be blocked or redirected by buildings and environmental features, but these waves can penetrate structures sufficiently to allow macrocells to provide service to UE 115 located indoors. Compared to transmission using smaller frequencies and longer waves in the lower 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).

[0061] The wireless communication system 100 can also operate in the 3 GHz to 30 GHz frequency band, also known as the centimeter band, in the ultra-high frequency (SHF) region, or in the extremely high frequency (EHF) region (also known as the millimeter band) of the spectrum (e.g., 30 GHz to 300 GHz). 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 individual devices can be smaller and more closely spaced than UHF antennas. In some examples, this may be advantageous for the use of antenna arrays within the devices. However, compared to SHF or UHF transmissions, EHF transmissions may experience greater atmospheric attenuation and a shorter range. The techniques disclosed herein can be employed across transmissions using one or more different frequency regions, and the designated use of frequency bands across these frequency regions may vary by country or regulatory body.

[0062] The wireless communication system 100 can utilize both licensed and unlicensed radio spectrum bands. For example, the wireless communication system 100 can use Licensed Assisted Access (LAA), LTE Unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5 GHz Industrial, Scientific, and Medical (ISM) band. When operating in unlicensed radio spectrum bands, devices such as base station 105 and UE 115 can employ carrier sensing for collision detection and avoidance. In some examples, operation in unlicensed bands can be based on a combination of carrier aggregation configuration and component carriers operating in licensed bands (e.g., LAA). Operation in unlicensed spectrum can include downlink transmissions, uplink transmissions, P2P transmissions, D2D transmissions, and so on.

[0063] Base station 105 or UE 115 may be equipped with multiple antennas, which may employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of base station 105 or UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located within a single antenna assembly, such as an antenna tower. In some examples, 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 can support various MIMO or beamforming operations. Additionally or alternatively, antenna panels may support radio frequency beamforming for signals transmitted via antenna ports.

[0064] Base station 105 or UE 115 can utilize MIMO communication by transmitting or receiving multiple signals via different spatial layers to take advantage of multipath signal propagation and increase spectral efficiency. This type of technique can be referred to as spatial multiplexing. For example, multiple signals can be transmitted by a transmitting device via different antennas or different combinations of antennas. Similarly, these multiple signals can be received by a receiving device via different antennas or different combinations of antennas. Each of these multiple signals can be referred to as a separate spatial stream and can carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) that transmits multiple spatial layers to the same receiving device, and multi-user MIMO (MU-MIMO) that transmits multiple spatial layers to multiple devices.

[0065] Beamforming, also known as spatial filtering, directional transmission, or directional reception, is a signal processing technique used at transmitting or receiving devices (e.g., base station 105, UE 115) to shape or manipulate antenna beams (e.g., transmit or receive beams) 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 some signals propagating in a particular direction relative to the antenna array experience constructive interference, while others experience destructive interference. Adjustments to the signals transmitted via antenna elements can include applying an amplitude offset, a phase offset, or both to the signals carried by the transmitting or receiving device via the antenna elements associated with that device. The adjustment associated with each antenna element can be defined by a beamforming weight set associated with a specific azimuth (e.g., relative to the antenna array of the transmitting or receiving device, or relative to some other direction).

[0066] Base station 105 or UE 115 may use beam scanning technology as part of beamforming operations. For example, base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with UE 115. 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. For example, base station 105 may transmit signals according to different beamforming weight sets associated with different transmission directions. Transmissions in different beam directions may be used to identify (e.g., by a transmitting device such as base station 105 or a receiving device such as UE 115) the beam direction for subsequent transmission and / or reception by base station 105.

[0067] Some signals, such as data signals associated with a specific 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 based on signals transmitted in one or more beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions and may report to base station 105 an indication that UE 115 received signals with the highest signal quality or otherwise acceptable signal quality.

[0068] In some examples, multiple beam directions can be used to perform transmissions by a device (e.g., by base station 105 or UE 115), and the device can use a combination of digital pre-decoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from base station 105 to UE 115). The UE 115 can report feedback indicating pre-decoding weights for one or more beam directions, and this feedback can correspond to a configured number of beams spanning the system bandwidth or one or more subbands. The base station 105 can transmit reference signals (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)), which can be pre-decoded or undecoded. The UE 115 can provide feedback for beam selection, which can be a pre-decoded matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may employ similar techniques to transmit signals multiple times in different directions (e.g., to identify the beam direction of subsequent transmissions or receptions by UE 115) or to transmit signals in a single direction (e.g., to transmit data to a receiving device).

[0069] A receiving device (e.g., UE 115) may attempt multiple receiving configurations (e.g., directional listening) when receiving various signals from base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, the receiving device may attempt multiple receiving directions by: receiving via different antenna subarrays; processing the received signals according to different antenna subarrays; receiving according to different sets of receiving beamforming weights applied to signals received at multiple antenna elements of the antenna array (e.g., different sets of directional listening weights); or processing the received signals according to different sets of receiving beamforming weights applied to signals received at multiple antenna elements of the antenna array, depending on the different receiving configurations or receiving directions, any of which can be referred to as "listening". In some examples, the receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving data signals). The single receiving configuration may be aligned based on beam directions determined according to listening according to different receiving configuration directions (e.g., determined to have the highest signal strength, the highest signal-to-noise ratio (SNR), or other acceptable signal quality based on listening according to multiple beam directions).

[0070] The wireless communication system 100 can 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 can be IP-based. The Radio Link Control (RLC) layer can perform packet segmentation and reassembly for communication on logical channels. The Media Access Control (MAC) layer can perform priority processing and multiplex logical channels into transport channels. This MAC layer can also use error detection techniques, error correction techniques, or both, to support retransmissions at this MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide the establishment, configuration, and maintenance of RRC connections between the UE 115 and the base station 105 or A core network 130 that supports radio bearers for user plane data. At the physical layer, transport channels can be mapped to physical channels.

[0071] UE 115 and base station 105 can support data retransmission to increase the likelihood of successful data reception. Hybrid Automatic Repeat Request (HARQ) feedback is a technique used to increase the likelihood of correct data reception over communication link 125. HARQ can 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 throughput at the MAC layer under adverse radio conditions (e.g., low signal-to-noise ratio conditions). In some examples, the device can support HARQ feedback within the same time slot, where the device can provide HARQ feedback in a specific time slot for data received in the previous symbol within that time slot. In other cases, the device can provide HARQ feedback in subsequent time slots or according to certain other time intervals.

[0072] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, and broadcasting. These systems can be multiple access systems, capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Wireless networks, such as wireless local area networks (WLANs) and Wi-Fi (i.e., IEEE 802.11) networks, can include access points (APs) that can communicate with one or more wireless or mobile devices. APs can be coupled to a network, such as the Internet, and can enable mobile devices to communicate via the network (or with other devices coupled to the access point). Wireless devices can communicate bidirectionally with network devices. For example, in a WLAN, a device can communicate with an associated AP via a downlink (e.g., a communication link from the AP to the device) and an uplink (e.g., a communication link from the device to the AP). Wireless personal area networks (PANs), which may include Bluetooth connectivity, can provide short-range wireless connectivity between two or more paired wireless devices. For example, a wireless device such as a cellular phone can utilize wireless PAN communication to exchange information such as audio signals with a wireless headset.

[0073] Wireless communication systems can perform V2X communication. In some V2X systems, V2X devices, such as UE 115, can reserve resources for communication on the V2X wireless channel. In some V2X wireless communication systems, the V2X device can be restricted to reserving a certain amount of resources on the wireless channel for channel-based CBR (Concurrent Batch Buffer). The V2X device can attempt to reserve resources for the initial transmission and retransmission of application packets using the available resources. However, in some cases, the initial transmission and retransmission may use more resources than the limited number of available sub-channels, which may affect retransmissions and increase packet loss.

[0074] If insufficient resources are available for initial transmission and retransmission, the wireless communication systems described herein, such as wireless communication system 100, support techniques for UE 115 to ensure reliable initial transmission and reduce packet loss. For example, when UE 115 has a message (e.g., an application packet) to send on a V2X wireless channel, UE 115 can determine the Channel Reservation Limit (CBR) of the wireless channel and determine a channel reservation limit based on the CBR. If UE 115 is limited to a certain amount of available resources such that UE 115 cannot reserve sufficient resources for initial transmission and retransmission, UE 115 may choose not to reserve resources for retransmission to ensure sufficient resources for reliable initial transmission. Conversely, UE 115 may reserve resources only for initial transmission, and UE 115 can use the resources reserved for initial transmission to send application packets.

[0075] Figure 2Examples of a wireless communication system 200 supporting resource selection under congestion conditions are shown according to various aspects of this disclosure. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. The wireless communication system includes UE 115-a and UE 115-b, which may be referenced respectively. Figure 1 An example of UE 115.

[0076] The wireless communication system 200 may be an example of a V2X wireless communication system. For example, UE115-a and UE115-b may be examples of a vehicle UE 115 (e.g., V-UE), a pedestrian UE 115 (e.g., P-UE), or some other example of a device operating in a V2X wireless communication system.

[0077] V2X devices in wireless communication system 200 can communicate on wireless channel 205. In some cases, wireless channel 205 can be a V2X wireless channel or a sidelink wireless channel. V2X devices, such as UE 115-a or UE 115-b, can reserve resources on wireless channel 205 to transmit messages. For example, UE 115-a can identify an application packet to be transmitted to UE 115-b, and UE 115-a can reserve a first resource 210 for the initial transmission of the application packet and a second resource 215 for the retransmission of the application packet.

[0078] In some cases, V2X devices can be restricted to reserving a certain amount of resources on radio channel 205 based on the CBR of radio channel 205. For example, UE 115-a can measure the CBR of radio channel 205. UE 115-a can measure the Reference Signal Strength Indicator (RSSI) of the radio channel and determine a portion or percentage of the subchannels of radio channel 205 that exceed the configured threshold.

[0079] The measured CBR can indicate a channel occupancy reservation limit, or a channel reservation limit, corresponding to the number of sub-channels that UE115-a can reserve over a period of time. In some cases, the channel reservation limit can be based on the priority of the messages that UE115-a wants to transmit via radio channel 205. For example, for an application packet (e.g., each packet has a ProSe priority (PPPP) of PPPP3 to PPPP5), if the measured CBR is between 60% and 80%, UE115-a may be able to reserve up to 30 sub-channels over a duration of 1 second. If the measured CBR is between 80% and 100%, UE115-a may be able to reserve up to 20 sub-channels for the application packet over a duration of 1 second. Higher priority packets may have less stringent channel reservation limits, while lower priority packets may have more stringent channel reservation limits.

[0080] UE 115-a may attempt to reserve first resource 210 and second resource 215 for the initial transmission and retransmission of application packets, but UE 115-a may not have sufficient resources due to channel reservation limitations. For example, first resource 210 and second resource 215 could be used together for 40 sub-channels for initial transmission and retransmission. However, UE 115-a may be limited to reserving 30 sub-channels, thus UE 115-a may not have sufficient available resources. In busy channels, requiring the UE to schedule resources for initial transmission and retransmission simultaneously when available resources are scarce can increase latency and degrade performance. In some cases, UE 115-a's attempt to schedule resources for initial transmission and retransmission may affect the quality of application packets, and UE 115-b may fail to successfully decode or receive initial transmissions and retransmissions. For example, when UE 115-a is subject to channel reservation limitations, the packet error rate during transmission under congestion conditions may increase significantly. In some cases, UE 115-a may not be able to send all the retransmitted information because, due to limitations, UE 115-a may not be able to reserve enough resources for retransmission.

[0081] If insufficient resources are available for initial transmission and retransmission, the wireless communication system 200 can support techniques for UE 115 (such as UE 115-a or UE 115-b) to ensure reliable initial transmission. For example, when UE 115-a has a message (e.g., an application packet) to send to UE 115-b on wireless channel 205, UE 115-a can determine the CBR of wireless channel 205 and determine channel reservation restrictions based on the CBR. If UE 115-a is restricted to a certain amount of available resources such that UE 115-a cannot reserve sufficient resources for initial transmission and retransmission, UE 115-a may not reserve a second resource 215 for retransmission. Then, UE 115-a can reserve a first resource 210 for initial transmission, and UE 115-a can use the first resource 210 for initial transmission to send application packets. This reduces the packet error rate of signaling.

[0082] UE 115-a can determine channel reservation limits and, based on these limits, determine whether there are sufficient resources for initial transmission and retransmission. For example, UE 115-a can use equation (1) to calculate the total resources available for retransmission.

[0083] (1) Availablesubchannels=Floor[CR_limit_subchan*SPS period / 1000ms / 2]

[0084] In some cases, channel reservation limits may be based on half-periodic signaling (SPS) periods. In one example, the SPS period is 100 milliseconds. If the channel reservation limit is 30 sub-channels, then one channel may be available. In this example, there may not be enough sub-channels for retransmission, so UE 115-a may reserve the first resource 210 only for the initial transmission. If the channel reservation limit is 20, then one sub-channel may be available, so UE 115-a may reserve the first resource 210 only for the initial transmission. If the channel reservation limit is 150, then seven sub-channels may be available, so UE 115-a may reserve the first resource 210 for the initial transmission and the second resource 215 for retransmission.

[0085] In some cases, UE 115-a may detect reserved resources over a duration, including both past and future reserved resources. For example, UE 115-a may determine the amount of reserved resources over a first duration of past resources and a second duration of future resources. In some cases, UE 115-a may detect the amount of resources in the most recent 900 milliseconds and the amount of reserved resources in the next 100 milliseconds. In this way, UE 115-a can determine the number of available subchannels based on used and licensed subchannels. For example, the number of available subchannels may be based on channel occupancy reservation limits minus the number of used subchannels (e.g., in the past portion of the window) and minus the number of licensed subchannels (e.g., in the future portion of the window). In some cases, UE 115-a may detect licensed resources in the future portion of the window based on received signaling indicating resources in the future portion, such as by receiving control information or sidelink control information indicating future reserved resources. In some cases, when evaluating the future portion of the window, UE 115-a may consider or calculate higher PPPP signaling. For example, UE 115-a can exclude reserved transmissions (e.g., initial transmissions and retransmissions) or transmissions of UE 115-a for the same SPS stream.

[0086] In some cases, UE 115-a can assess channel occupancy limits at multiple points. For example, during the first (e.g., initial) transmission, UE 115-a can determine if the number of available sub-channels is sufficient for the initial transmission. If the number of sub-channels required for the initial transmission exceeds the channel occupancy limit, UE 115-a may abandon the initial transmission. If there are enough sub-channels available for the initial transmission, UE 115-a can send the initial transmission. Then, during a retransmission of the initial transmission, UE 115-a can again assess the channel occupancy limit to determine if there are sufficient resources for retransmission. If there are sufficient resources for retransmission, UE 115-a can initiate a retransmission of the initial transmission. If there are insufficient resources available for retransmission, UE 115-a may abandon the retransmission.

[0087] Authorized subchannels may correspond to resources reserved for transmission by UE 115-a or other UE 115 (e.g., in future resources). Authorized subchannels may be reserved for event-driven transmissions. In some cases, event-driven transmissions may be one-off transmissions, such as dynamic signaling. For example, event-driven transmissions may not be SPS transmissions. In some cases, event-driven transmissions may be higher-priority signaling, which may be based on higher PPP.

[0088] When considering authorized subchannels to determine the number of available subchannels, UE 115-a can determine the number of available subchannels based on equation (2), where CR_limit_subch corresponds to the channel reservation limit or channel occupancy limit, used_subchannels corresponds to the number of subchannels in the past part of the window, and granted_subchannels corresponds to the number of subchannels reserved in the future part of the window.

[0089] (2) Available subchannels

[0090] =(CR_limit_subch-Used_subchannels

[0091] -granted_subchannels

[0092] In some examples, UE 115-a can determine different channel occupancy limits. In some cases, different channel occupancy limits may correspond to different thresholds or tolerances for channel occupancy. For example, UE 115-a can determine the channel occupancy limit using equation (3) or equation (4). The determined channel occupancy limits are packet_limit_subch_1 and packet_limit_subch_2, respectively, and each can be an example of CR_limit_subch in equation (2).

[0093] (3) packet_limit_subch_1=Floor[CR_limit_subch*SPS_Period / 1000ms

[0094] (4) packet_limit_subch_2=Floor[CR_limit_subch*SPS_Period / 1000ms / 2

[0095] For example, UE 115-a may have pending SPS transmissions, with a first number of resource blocks for initial transmission and a second number of resource blocks for retransmission. If the number of available subchannels in Equation (2) is sufficiently large to satisfy both the first and second number of resource blocks when using the channel occupancy limit in Equation (3), then UE 115-a may reserve resources for both initial transmission and retransmission simultaneously. If not, but the number of available subchannels in Equation (2) is sufficiently large when using the channel occupancy limit in Equation (4), then UE 115-a may reserve resources only for initial transmission. If not, but UE 115-a selects an MCS for the first number of resource blocks within the pre-configured subchannel range, then UE 115-a reserves resources for initial transmission. If none of these conditions are met, then UE 115-a may abandon both initial transmission and retransmission. In this way, UE115-a can check multiple conditions for reserving resources for initial transmission and retransmission, and UE115-a can adaptively increase or decrease the amount of reserved resources based on the conditions that may be met.

[0096] Figure 3 Examples of a process flow 300 supporting resource selection under congestion conditions are shown according to various aspects of this disclosure. In some examples, this process flow 300 may implement aspects of the wireless communication system 100. This process flow 300 may be implemented by UE 115-c and UE 115-d, each of which may be a reference. Figure 1 and Figure 2Examples of UE 115. In some cases, UE 115-c and UE 115-d may be examples of V2X devices, such as V-UE, P-UE, Transmit and Receive Point (TRP), Roadside Unit, or other devices operating in a V2X communication system.

[0097] At 305, UE 115-c can identify a message to be transmitted over a radio channel. For example, UE 115-c can identify an application packet to be transmitted to UE 115-d via a V2X radio channel or sidelink. In some cases, this message may be associated with a priority level. For example, the message may be associated with PPPP3 to PPPP5.

[0098] In some cases, UE 115-c can determine the Channel Reservation Limit (CBR) of a radio channel based on RSSI measurements. At 310, UE 115-c can determine channel reservation limits for reserving resources on the radio channel for the message based on the CBR. Channel reservation limits can correspond to the number of sub-channels that a radio device (such as UE 115-c) is allowed to reserve for transmission over a period of time. For example, UE 115-c can be limited to reserving 150 sub-channels, 30 sub-channels, or 20 sub-channels for a duration of 1 second. In some cases, if the CBR is very low (e.g., below 30%), UE 115-c may not have channel reservation limits for the radio channel.

[0099] At point 315, UE 115-c can determine, based on the channel reservation limit, that available resources are insufficient for the initial transmission and retransmission of the message. For example, UE 115-c can reserve up to 30 sub-channels, but the initial transmission and retransmission can each use 40 sub-channels. If UE 115-c attempts to reserve resources for retransmission, it may be unable to send all the information for the retransmission, potentially leading to packet loss and an increased packet error rate. Therefore, UE 115-c can reserve resources for the initial transmission rather than for retransmission.

[0100] At 320, UE 115-c may reserve resources on the radio channel for the initial transmission of the message if the available resources are insufficient for both the initial transmission and retransmission of the message. In some cases, UE 115-c may avoid reserving resources for message retransmission.

[0101] At position 325, UE 115-c can send a message to UE 115-d via the radio channel on the resource. In some cases, if UE 115-c has reserved resources for retransmission, UE 115-c can send a retransmission at position 330.

[0102] Figure 4A block diagram 400 of a device 405 supporting resource selection under congestion conditions is shown, according to various aspects of this disclosure. The device 405 may be an example of various aspects of a UE 115 as described herein. The device 405 may include a receiver 410, a communication manager 415, and a transmitter 420. The device 405 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0103] The receiver 410 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 resource selection under congestion conditions). This information can be transmitted to other components of the device 405. The receiver 410 can be a reference. Figure 7 Examples of various aspects of the transceiver 715. The receiver 410 may utilize a single antenna or a set of antennas.

[0104] The communication manager 415 can identify a message to be transmitted on a wireless channel; determine a channel reservation limit for reserving resources on the wireless channel for the message based on the channel busy rate; determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and reserve resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message. The communication manager 415 may be an example of various aspects of the communication manager 710 described herein.

[0105] The communication manager 415 or its sub-components may be implemented in hardware, processor-executable code (e.g., software or firmware), or any combination thereof. If implemented as processor-executable code, the functionality of the communication manager 415 or its sub-components may be performed by a general-purpose processor, DSP, application-specific integrated circuit (ASIC), FPGA or other programmable logic device designed to perform the functions described in this disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0106] The communication manager 415 or its sub-components may be physically located in various orientations, including distributed portions of the functionality implemented by one or more physical components at different physical locations. In some examples, according to various aspects of this disclosure, the communication manager 415 or its sub-components may be separate and distinct components. In some examples, according to various aspects of this disclosure, the communication manager 415 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.

[0107] Actions performed by the communication manager 415 as described herein can be implemented to achieve one or more potential advantages. One implementation allows UE 115 to reduce packet loss. For example, UE 115 may reserve resources only for the initial transmission, rather than reserving resources for both the initial transmission and partial retransmissions. In some cases, if UE 115 is limited to reserving sufficient resources for retransmissions, UE 115 may only be able to send a portion of the retransmission information, which may not be decoded or successfully received by the receiving device. Furthermore, these techniques can improve spectral efficiency. For example, if UE 115 reserves resources for the initial transmission instead of retransmissions, the resources reserved by UE 115 for retransmissions can be used by other radio devices. In some cases, avoiding reserving resources for retransmissions may reduce the CBR of the radio channel.

[0108] The transmitter 420 can transmit signals generated by other components of the device 405. In some examples, the transmitter 420 can be co-located with the receiver 410 in a transceiver module. For example, the transmitter 420 can be a reference... Figure 7 Examples of various aspects of the transceiver 715 are described. The transmitter 420 can utilize a single antenna or a set of antennas.

[0109] Figure 5 A block diagram 500 of a device 505 supporting resource selection under congestion conditions is shown, according to various aspects of this disclosure. The device 505 may be an example of aspects of device 405 or UE 115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 540. The device 505 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0110] The 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 resource selection under congestion conditions). The information can be transmitted to other components of the device 505. The receiver 510 can be a reference. Figure 7 Examples of various aspects of the transceiver 715. The receiver 510 may utilize a single antenna or an array of antennas.

[0111] The communication manager 515 may be an example of aspects of the communication manager 415 as described herein. The communication manager 515 may include a message identification component 520, a channel reservation restriction component 525, an available resource determination component 530, and a resource reservation component 535. The communication manager 515 may be an example of aspects of the communication manager 710 as described herein.

[0112] The message identification component 520 can identify a message to be sent on a wireless channel. The channel reservation restriction component 525 can determine the channel reservation restriction for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel.

[0113] The available resource determination component 530 can determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message. The resource reservation component 535 can reserve resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0114] The transmitter 540 can transmit signals generated by other components of the device 505. In some examples, the transmitter 540 can be co-located with the receiver 510 in a transceiver module. For example, the transmitter 540 can be a reference... Figure 7 Examples of various aspects of the transceiver 715 are described. The transmitter 540 can utilize a single antenna or a set of antennas.

[0115] Figure 6 A block diagram 600 of a communication manager 605 supporting resource selection under congestion conditions is shown, according to various aspects of this disclosure. The communication manager 605 may be an example of aspects of communication manager 415, communication manager 515, or communication manager 710 as described herein. The communication manager 605 may include a message identification component 610, a channel reservation restriction component 615, an available resource determination component 620, a resource reservation component 625, and a channel busy rate component 630. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0116] The message identification component 610 can identify a message to be transmitted on a wireless channel. In some cases, the wireless channel includes a V2X channel. The channel reservation restriction component 615 can determine the channel reservation restriction for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel.

[0117] The available resource determination component 620 can determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message. In some examples, the available resource determination component 620 can determine the number of available sub-channels for the message based on the channel reservation limit. In some examples, the available resource determination component 620 can determine that the number of available sub-channels is insufficient for the initial transmission and retransmission of the message. In some cases, the available resource determination component 620 can determine the number of available sub-channels for the message based on one or more event-driven transmission licensed resources. In some examples, the available resource determination component 620 can determine the number of available sub-channels for the message based on the channel occupancy assessment window, which includes a first portion of past resources and a second portion of future resources.

[0118] In some examples, the available resource determination component 620 may determine a first number of available sub-channels for the message based on a first channel reservation limit. The available resource determination component 620 may determine that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message. The available resource determination component 620 may determine a second number of available resources for the message based on a second channel reservation limit and the insufficiency of the first number of available sub-channels, and the available resource determination component 620 may determine that the second number of available sub-channels is insufficient for the initial transmission and retransmission of the message, but sufficient for the initial transmission of the message.

[0119] The resource reservation component 625 can reserve resources on the wireless channel for the initial transmission of the message if the available resources are insufficient for both the initial transmission and retransmission of the message. In some examples, the resource reservation component 625 can avoid reserving retransmission resources based on the determination that available resources are insufficient. The channel busy rate component 630 can determine the channel busy rate of the wireless channel based on the received signal strength indicator measurement of the wireless channel.

[0120] Figure 7 A diagram of a system 700, including device 705 supporting resource selection under congestion conditions, is shown according to various aspects of this disclosure. Device 705 may be an example of device 405, device 505, or UE 115 described herein, or a component including device 405, device 505, or UE 115. Device 705 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communication manager 710, transceiver 715, antenna 720, memory 725, and processor 735. These components may communicate electronically via one or more buses (e.g., bus 740).

[0121] The communication manager 710 can identify a message to be sent on a wireless channel; determine a channel reservation limit for reserving resources on the wireless channel for the message based on the channel busy rate of the wireless channel; determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message; and reserve resources on the wireless channel for the initial transmission of the message based on the insufficient available resources for the initial transmission and retransmission of the message.

[0122] As described above, the transceiver 715 can communicate bidirectionally via one or more antennas, wired links, or wireless links. For example, the transceiver 715 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 715 may also include a modem for modulating packets and providing the modulated packets to the antennas for transmission, as well as demodulating packets received from the antennas.

[0123] In some cases, the wireless device may include a single antenna 720. However, in other cases, the device may have more than one antenna 720, which is capable of transmitting or receiving multiple wireless transmissions simultaneously.

[0124] The memory 725 may include RAM and ROM. The memory 725 may store computer-readable, computer-executable code 730, including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 725 may also contain a BIOS, which controls basic hardware or software operations, such as interaction with peripheral components or devices.

[0125] The code 730 may contain instructions for implementing various aspects of this disclosure, including instructions for supporting wireless communication. The code 730 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, the code 730 may not be directly executed by the processor 735, but may instead enable a computer (e.g., at compile and execution time) to perform the functions described herein.

[0126] Processor 735 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 735 may be configured to use a memory controller to operate a memory array. In other cases, the memory controller may be integrated into processor 735. Processor 735 may be configured to execute computer-readable instructions stored in memory (e.g., memory 725) to cause device 705 to perform various functions (e.g., functions or tasks supporting resource selection under congestion conditions).

[0127] Figure 8 A flowchart of a method 800 for supporting resource selection under congestion conditions, according to various aspects of this disclosure, is shown. The operation of method 800 can be implemented by UE 115 or its components, as described herein. For example, the operation of method 800 can be implemented by reference to... Figures 4 to 7 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 described function. Additionally or alternatively, the UE can use dedicated hardware to perform aspects of the described function.

[0128] At point 805, the UE can identify a message to be transmitted on the radio channel. The operation of point 805 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the 805 operations that can be performed by the message identification component.

[0129] At 810, the UE can determine the channel reservation limit for reserving resources on the radio channel for the message based on the channel busy rate of the radio channel. The operation at 810 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the various aspects of the operation of 810 that can be performed by the channel reservation limiting component.

[0130] At point 815, the UE can determine, based on the channel reservation limit, that the available resources are insufficient for the initial transmission and retransmission of the message. The operation at point 815 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the components that can be used to perform the 815 operation, which can be determined by available resources.

[0131] At point 820, the UE may reserve resources on the radio channel for the initial transmission of the message, based on the premise that the available resources are insufficient for the initial transmission and retransmission of the message. The operation at point 820 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the 820 operations that can be performed by the resource reservation component.

[0132] Figure 9 A flowchart illustrating a method 900 for supporting resource selection under congestion conditions, according to various aspects of this disclosure, is shown. The operation of method 900 can be implemented by a UE 115 or its components as described herein. For example, the operation of method 900 can be provided by reference to... Figures 4 to 7The 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 described function. Additionally or alternatively, the UE can use dedicated hardware to perform aspects of the described function.

[0133] At position 905, the UE can identify the message to be transmitted on the radio channel. The operation at position 905 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The description covers various aspects of the 905 operation that can be performed by the message identification component.

[0134] At 910, the UE can determine the channel busy rate of the wireless channel based on the received signal strength indicator (RSI) measurement of the wireless channel. The operation at 910 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the 910 operations that can be performed by the channel busy rate component.

[0135] At point 915, the UE can determine the channel reservation limit for reserving resources on the radio channel for the message based on the channel busy rate of the radio channel. The operation at point 915 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the 915 operations that can be performed by the channel reservation limiting component.

[0136] At point 920, the UE can determine, based on the channel reservation limit, that available resources are insufficient for both the initial transmission and retransmission of the message. The operation at point 920 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the components that can be used to perform the 920 operation, which can be determined by available resources.

[0137] At point 925, the UE can reserve resources on the radio channel for the initial transmission of the message, assuming that the available resources are insufficient for both the initial transmission and retransmission of the message. The operation at point 925 can be performed according to the methods described herein. In some examples, such as references... Figures 4 to 7 The described aspects are the 925 operations that can be performed by the resource reservation component.

[0138] 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 possible. Furthermore, aspects from two or more methods can be combined.

[0139] The following provides an overview of the various aspects of this disclosure:

[0140] Aspect 1: A method for wireless communication at a UE, comprising: identifying a message to be transmitted on a wireless channel; determining, at least in part, a channel reservation limit for reserving resources on the wireless channel for the message based on a channel busy rate of the wireless channel; determining, at least in part, based on the channel reservation limit, that available resources are insufficient for the initial transmission of the message and for retransmission of the message; and reserving resources on the wireless channel for the initial transmission of the message based at least in part on the insufficient available resources for the initial transmission of the message and for retransmission of the message.

[0141] Aspect 2: According to the method of aspect 1, determining that available resources are insufficient includes: determining the number of available sub-channels for the message based at least in part on the channel reservation limit; and determining that the number of available sub-channels is insufficient for the initial transmission and retransmission of the message.

[0142] Aspect 3: According to the method of aspect 2, determining that available resources are insufficient includes: determining the number of available sub-channels for the message based at least in part on the authorized resources of one or more event-driven transmissions.

[0143] Aspect 4: The method according to any one of Aspects 2 to 3, wherein determining that available resources are insufficient comprises: determining the number of available sub-channels for the message based at least in part on the channel occupancy rate within a channel occupancy rate assessment window, the channel occupancy rate assessment window comprising a first portion of past resources and a second portion of future resources.

[0144] Aspect 5: The method according to any one of Aspects 1 to 4, wherein determining that available resources are insufficient comprises: determining a first number of available sub-channels for the message based at least in part on a first channel reservation constraint; determining that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; determining a second number of available sub-channels for the message based at least in part on a second channel reservation constraint and the insufficiency of the first number of available sub-channels; and determining that the second number of available sub-channels is insufficient for the initial transmission and retransmission of the message, but sufficient for the initial transmission of the message.

[0145] Aspect 6: The method according to any one of Aspects 1 to 5 further includes: determining the channel busy rate of the wireless channel based at least in part on the received signal strength indicator measurement of the wireless channel.

[0146] Aspect 7: The method according to any one of Aspects 1 to 6, wherein the channel reservation constraint is based at least in part on message priority.

[0147] Aspect 8: The method according to any one of Aspects 1 to 7, wherein the channel reservation limit corresponds to the number of sub-channels that a wireless device is allowed to reserve for transmission over a period of time.

[0148] Aspect 9: The method according to any one of Aspects 1 to 8, wherein the available resources are determined at least in part based on the duration of the semi-persistent scheduling period and channel reservation constraints.

[0149] Aspect 10: The method according to any one of Aspects 1 to 9 further includes: avoiding reserving retransmission resources at least in part based on the determination that available resources are insufficient.

[0150] Aspect 11: The method according to any one of Aspects 1 to 10, wherein the wireless channel includes a vehicle-to-everything (V2X) channel.

[0151] Aspect 12: An apparatus for wireless communication at a UE, comprising a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to any one of aspects 1 to 11.

[0152] Aspect 13: An apparatus for wireless communication at a UE, comprising at least one component for performing the method of any one of aspects 1 to 11.

[0153] Aspect 14: A non-transitory computer-readable medium storing code for wireless communication at a UE, the code including instructions executable by a processor to perform the method of any one of Aspects 1 to 11.

[0154] While various 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 many descriptions, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications. For example, the techniques described can be applied to a variety of other wireless communication systems, such as Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0155] The information and signals described herein can be represented using any of a variety of different technologies and processes. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout this specification can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0156] The various illustrative blocks and components described herein can be implemented or performed using a general-purpose processor, DSP, ASIC, CPU, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware component, or any combination thereof, designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any 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 combined with a DSP core, or any other such configuration).

[0157] The functionality described herein can be implemented by hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functionality can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functionality described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functionality can also be physically located in various positions, including distributed such that different parts of the functionality are implemented in different physical orientations.

[0158] Computer-readable media include both non-transitory computer storage media and communication media, with communication media encompassing any medium that facilitates the transfer of a computer program from one place to another. Non-transitory storage media can be any available medium accessible by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, optical disc (CD) ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store required program code in the form of instructions or data structures and can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Furthermore, any connection is appropriately 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, these are all included in the definition of computer-readable media. The disks and optical discs used in this article include CDs, laser discs, optical discs, digital multifunction discs (DVDs), floppy disks, and Blu-ray discs. Disks typically reproduce data magnetically, while optical discs reproduce data optically using lasers. Combinations of these are also included within the scope of computer-readable media.

[0159] As used herein, the word "or" in a list of items (e.g., a list of items beginning with phrases such as "at least one" or "one or more") in the claims indicates an inclusive list. Thus, for example, a list of at least one of 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). Furthermore, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, an example step described as "based on condition A" could 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".

[0160] In the accompanying drawings, similar components or features may have the same reference numerals. Furthermore, various components of the same type can be distinguished by adding a dash after the reference numeral and a second label to differentiate them from other similar components. If only the first reference numeral is used in the description, the description applies to any similar component having the same first reference numeral, regardless of the second or other subsequent reference numerals.

[0161] The description herein, taken in conjunction with the accompanying drawings, describes exemplary configurations and does not represent all examples that can be implemented or that are within the scope of the claims. As used herein, the term "example" means "serving as an example, instance, or illustration," and not "preferred" or "superior to other examples." To provide an understanding of the described techniques, the detailed specification includes specific details. However, these techniques can be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0162] 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 readily apparent to those skilled in the art, and the general principles defined herein may 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 given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for performing wireless communication at a user equipment (UE), comprising: Identifies the message to be transmitted over the wireless channel; The first channel reservation limit for reserving resources on the wireless channel for the message is determined at least in part based on the channel busy rate of the wireless channel; The first number of available sub-channels for the message is determined at least in part based on the first channel reservation constraint; It is determined that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; The second number of available sub-channels for the message is determined at least in part based on the second channel reservation limit and because the first number of available sub-channels is insufficient for the initial transmission and the retransmission. The second number of available sub-channels is determined to be insufficient for the initial transmission and the retransmission, but sufficient for the initial transmission; as well as At least in part, based on the fact that the second number of available sub-channels is insufficient for the initial transmission and the retransmission but sufficient for the initial transmission, resources are reserved on the wireless channel solely for the initial transmission.

2. The method according to claim 1, wherein, Determining the first number of available sub-channels, at least in part, based on the first channel reservation constraint, includes: The first number of available subchannels is determined at least in part based on the authorized resources of one or more event-driven transmissions.

3. The method according to claim 1, wherein, Determining the first number of available sub-channels, at least in part, based on the first channel reservation constraint, includes: The first number of available subchannels is determined at least in part based on the channel occupancy rate within a channel occupancy rate assessment window, which includes a first portion of past resources and a second portion of future resources.

4. The method according to claim 1, further comprising: The channel busy rate of the wireless channel is determined at least in part based on the received signal strength indicator measurement of the wireless channel.

5. The method according to claim 1, wherein, The first channel reservation limit is based at least in part on the priority of the message.

6. The method according to claim 1, wherein, The first channel reservation limit corresponds to the number of sub-channels that the UE is allowed to reserve for transmission over a period of time.

7. The method according to claim 1, wherein, The first number of available sub-channels is determined at least in part based on the duration of the semi-persistent scheduling period and the first channel reservation limit.

8. The method according to claim 1, further comprising: Reserving retransmission resources is avoided, at least in part, based on the determination that the first number of available sub-channels is insufficient for the initial transmission and the retransmission.

9. The method according to claim 1, wherein, The wireless channel includes a vehicle-to-everything (V2X) channel.

10. An apparatus for performing wireless communication at a user equipment (UE), comprising: processor; Memory coupled to the processor; and Instructions, stored in the memory and executable by the processor, enable the device to: Identifies the message to be transmitted over the wireless channel; The first channel reservation limit for reserving resources on the wireless channel for the message is determined at least in part based on the channel busy rate of the wireless channel; The first number of available sub-channels for the message is determined at least in part based on the first channel reservation constraint; It is determined that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; The second number of available sub-channels for the message is determined at least in part based on the second channel reservation limit and because the first number of available sub-channels is insufficient for the initial transmission and the retransmission. The second number of available sub-channels is determined to be insufficient for the initial transmission and the retransmission, but sufficient for the initial transmission; as well as At least in part, based on the fact that the second number of available sub-channels is insufficient for the initial transmission and the retransmission but sufficient for the initial transmission, resources are reserved on the wireless channel solely for the initial transmission.

11. The apparatus according to claim 10, wherein, The instruction that determines the first number of available sub-channels based at least in part on the first channel reservation constraint can be executed by the processor to enable the device to: The first number of available subchannels is determined at least in part based on the authorized resources of one or more event-driven transmissions.

12. The apparatus according to claim 10, wherein, The instruction that determines the first number of available sub-channels based at least in part on the first channel reservation constraint can be executed by the processor to enable the device to: The first number of available subchannels is determined at least in part based on the channel occupancy rate within a channel occupancy rate assessment window, which includes a first portion of past resources and a second portion of future resources.

13. The apparatus of claim 10, wherein the instructions are further executable by the processor to cause the apparatus to: The channel busy rate of the wireless channel is determined at least in part based on the received signal strength indicator measurement of the wireless channel.

14. The apparatus according to claim 10, wherein, The first channel reservation limit is based at least in part on the priority of the message.

15. The apparatus according to claim 10, wherein, The first channel reservation limit corresponds to the number of sub-channels that the UE is allowed to reserve for transmission over a period of time.

16. The apparatus according to claim 10, wherein, The first number of available sub-channels is determined at least in part based on the duration of the semi-persistent scheduling period and the first channel reservation limit.

17. The apparatus of claim 10, wherein the instructions are further executable by the processor to cause the apparatus to: Reserving retransmission resources is avoided, at least in part, based on the determination that the first number of available sub-channels is insufficient for the initial transmission and the retransmission.

18. The apparatus according to claim 10, wherein, The wireless channel includes a vehicle-to-everything (V2X) channel.

19. An apparatus for performing wireless communication at a user equipment (UE), comprising: Components used to identify messages to be transmitted over a wireless channel; A component for determining a first channel reservation limit for reserving resources on the wireless channel for the message, based at least in part on the channel busy rate of the wireless channel; Components for determining a first number of available sub-channels for the message, at least in part, based on the first channel reservation limit; A component for determining that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; A component for determining a second number of available sub-channels for the message based at least in part on a second channel reservation limit and on the fact that the first number of available sub-channels is insufficient for the initial transmission and the retransmission; The component used to determine that the second number of available subchannels is insufficient for the initial transmission and the retransmission but sufficient for the initial transmission; as well as The component is used for reserving resources on the wireless channel for the initial transmission only, based at least in part on the second number of available sub-channels that is insufficient for both the initial transmission and the retransmissions but sufficient for the initial transmission.

20. The apparatus according to claim 19, wherein, The component for determining the first number of available sub-channels based at least in part on the first channel reservation limit includes: Components for determining the first number of available subchannels based at least in part on authorized resources of one or more event-driven transmissions.

21. The apparatus according to claim 19, wherein, The component for determining the first number of available sub-channels based at least in part on the first channel reservation limit includes: The component for determining the first number of available subchannels based at least in part on the channel occupancy rate within a channel occupancy rate assessment window, the channel occupancy rate assessment window comprising a first portion of past resources and a second portion of future resources.

22. The apparatus of claim 19, further comprising: A component for determining the channel busy rate of the wireless channel based at least in part on the received signal strength indicator measurement of the wireless channel.

23. The apparatus according to claim 19, wherein, The first channel reservation limit is based at least in part on the priority of the message.

24. The apparatus according to claim 19, wherein, The first channel reservation limit corresponds to the number of sub-channels that the UE is allowed to reserve for transmission over a period of time.

25. The apparatus according to claim 19, wherein, The first number of available sub-channels is determined at least in part based on the duration of the semi-persistent scheduling period and the first channel reservation limit.

26. The apparatus of claim 19, further comprising: A component for avoiding reserving retransmission resources based at least in part on the determination that the first number of available subchannels is insufficient for the initial transmission and the retransmission.

27. The apparatus according to claim 19, wherein, The wireless channel includes a vehicle-to-everything (V2X) channel.

28. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to perform the following operations: Identifies the message to be transmitted over the wireless channel; The first channel reservation limit for reserving resources on the wireless channel for the message is determined at least in part based on the channel busy rate of the wireless channel; The first number of available sub-channels for the message is determined at least in part based on the first channel reservation constraint; It is determined that the first number of available sub-channels is insufficient for the initial transmission and retransmission of the message; The second number of available sub-channels for the message is determined at least in part based on the second channel reservation limit and because the first number of available sub-channels is insufficient for the initial transmission and the retransmission. The second number of available sub-channels is determined to be insufficient for the initial transmission and the retransmission, but sufficient for the initial transmission; as well as At least in part, based on the fact that the second number of available sub-channels is insufficient for the initial transmission and the retransmission but sufficient for the initial transmission, resources are reserved on the wireless channel solely for the initial transmission.

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