WO2021179244A1

WO2021179244A1 - Fountain-code-based broadcast channel with limited feedback

Info

Publication number: WO2021179244A1
Application number: PCT/CN2020/078974
Authority: WO
Inventors: Kangqi LIU; Changlong Xu; Liangming WU; Jian Li; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2021-09-16

Abstract

Methods, systems, and devices for wireless communications are described. A transmitting device (a base station) may transmit encoded symbols (via a broadcast channel) in accordance with an acknowledgement feedback threshold (such as a hybrid automatic repeat request acknowledgment (HARQ-ACK) threshold), an erasure probability based threshold, or both. As such, a transmitting device may transmit encoded symbols of data units until an acknowledgement feedback threshold has been satisfied, until an erasure probability based threshold has been satisfied, or until both thresholds have been satisfied before proceeding to transmit encoded symbols of a subsequent data unit. For example, a transmitting device may transmit encoded data blocks, corresponding to a first data unit, until a quantity of received acknowledgement feedback satisfies or exceeds a threshold, after which the transmitting device may begin transmitting encoded data blocks corresponding to a next data unit (such as a second data unit after the first data unit).

Description

FOUNTAIN-CODE-BASED BROADCAST CHANNEL WITH LIMITED FEEDBACK

TECHNICAL FIELD

The following relates generally to wireless communications and more specifically to fountain-code-based broadcast channel operation with limited feedback.

DESCRIPTION OF THE RELATED TECHNOLOGY

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

Wireless communications systems may exchange packets (which may be referred to as symbols) to transmit information. In some cases, symbols may be encoded to, for example, improve the reliability of the transmitted information. In some examples, encoded symbols may provide redundancy, which may be used to correct errors that may result from the transmission environment (such as, path loss, obstacles) . Some examples of encoding codes that employ error correcting codes are based on the use of fountain codes, such as Luby transform (LT) codes or rapid tornado (Raptor) codes.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support rapid tornado fountain-code-based broadcast channel operation with limited feedback. Generally, the described techniques provide for efficient transmission of information (for example, one or more data units) encoded using one or more fountain codes based on acknowledgement feedback from one or more receiving devices, erasure probabilities associated with one or more transmissions to one or more receiving devices, or both. A transmitting device may include a base station, a user equipment (UE) , an integrated access and backhaul (IAB) network node, or another wireless device, among other examples. The transmitting device may encode symbols using one or more fountain codes (such as Luby transform (LT) codes or rapid tornado (Raptor) codes) . According to the techniques described herein, a transmitting device may transmit encoded symbols in accordance with an acknowledgement feedback threshold (such as a hybrid automatic repeat request acknowledgment (HARQ-ACK) threshold) , an erasure probability based threshold, or both. As such, a transmitting device may transmit encoded symbols of a data unit until an acknowledgement feedback threshold has been satisfied, until an erasure probability based threshold has been satisfied, or until both thresholds have been satisfied and may then proceed to transmit encoded symbols of a subsequent data unit.

For example, a transmitting device (such as a base station) may encode information (such as source symbols of a first data unit) into one or more data blocks (such as including encoded symbols) using one or more fountain codes. The transmitting device may transmit the one or more data blocks, corresponding to the first data unit, to one or more receiving devices (such as one or more UEs monitoring a broadcast channel for the one or more data blocks) . A receiving device may then transmit an acknowledgement feedback message to the transmitting device upon reception of enough data blocks for the receiving device to determine (for example, to recover the source symbols of) the first data unit or successfully decode the first data unit. As such, a transmitting device may transmit encoded data blocks corresponding to a first data unit until a quantity of one or more acknowledgement feedback messages received from UEs served by the transmitting device satisfies a threshold (for example a HARQ-ACK threshold) , at which point the transmitting device may begin transmitting encoded data blocks corresponding to one or more other data units (such as a second data unit after the first data unit) .

Additionally or alternatively, a transmitting device may transmit one or more data blocks, which may correspond to a data unit, in accordance with an erasure probability based threshold. For example, a transmitting device may determine a respective erasure probability (for example, a probability that a data block is received by a UE based on channel conditions or a UE capability, among other examples) for each of one or more UEs associated with a broadcast channel. The transmitting device may then determine a quantity of one or more data blocks to transmit for a given data unit based on the determined erasure probabilities for one or more of the served UEs. For example, a transmitting device may determine a quantity of one or more data blocks to transmit for a given data unit based on an erasure probability, such as a highest erasure probability (for example, associated with a worst-case scenario UE) , or based on an average erasure probability (such that some average quantity of encoding symbols may be received by the served UEs) , among other examples.

BRIEF DESCRIPTION OF THE DRAWINGS

Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.

Figure 1 illustrates an example of a wireless communications system that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 2 illustrates an example of a wireless communications system that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 3 illustrates an example of an encoding scheme that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 4 illustrates an example of an encoding and transmission scheme that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 5 illustrates an example of an encoding and transmission scheme that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 6 illustrates an example of a process flow that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 7 illustrates an example of a process flow that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figures 8 and 9 show block diagrams of devices that support fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 10 shows a block diagram of a communications manager that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 11 shows a diagram of a system including a device that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figures 12 and 13 show block diagrams of devices that support fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 14 shows a block diagram of a communications manager that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figure 15 shows a diagram of a system including a device that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Figures 16–21 show flowcharts illustrating methods that support fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure.

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

The following description is directed to particular implementations for the purposes of describing innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving radio frequency (RF) signals according to one or more of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, the IEEE 802.15 standards, the

standards as defined by the Bluetooth Special Interest Group (SIG) , or the Long Term Evolution (LTE) , 3G, 4G, or 5G (New Radio (NR) ) standards promulgated by the 3rd Generation Partnership Project (3GPP) , among others. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal FDMA (OFDMA) , single-carrier FDMA (SC-FDMA) , single-user (SU) multiple-input multiple-output (MIMO) , and multi-user (MU) MIMO.

Wireless communications systems may exchange packets (which may be referred to as symbols) to transmit information. In some examples, symbols may be encoded to improve the reliability of the transmitted information. For example, encoded symbols may provide redundancy, which may be used to correct errors that may result from the transmission environment (for example, path loss, obstacles) . Some examples of encoding codes that employ error correcting codes are based on the use of fountain codes, such as Luby transform (LT) codes or rapid tornado (Raptor) codes. A fountain code may be an example of a rateless code in which a set of source symbols (K symbols) of a data unit may be encoded as any quantity of encoding symbols (for example, a quantity of symbols greater than K symbols) . Encoding the source symbols may include combining one or more source symbols into at least some encoding symbols, if not each encoding symbol. The encoding may include using a degree distribution in which the degree distribution may represent a probability mass function of a set of degrees d _i (for example, d ₁, d ₂, d ₃, …) . The probability of randomly selecting a degree d _i (a degree with index i) from the degree distribution may be represented by ρ (i) . In the encoding process, the degree d _i may represent the quantity of source symbols that may be combined into a given encoding symbol.

The encoding symbols (for example, encoded source symbols of a data unit) may be transmitted as a set of data blocks (or encoded symbols) from a first node (which may be referred to herein as a transmitting device) of a network to a second node (which may be referred to herein as a receiving device) of the network. Based on the encoding and combining by the transmitting device, such as based on the one or more fountain codes used by the transmitting device, a receiving device may decode the set of source symbols from the set of encoded symbols despite the symbol loss (for example, packet loss) or other conditions, for example, to determine or successfully decode the data unit. For instance, a receiving device may be able to receive, or successfully decode, a data unit after a quantity of received data blocks (N) is greater than a quantity of source symbols (K) encoded by the transmitter.

However, in some examples (such as for broadcast channel transmissions) , wireless communications systems may not employ a feedback mechanism for receiving devices to notify the transmitting device about the success of the transmissions. As such, a transmitting device may conservatively transmit a large quantity of redundant encoding symbols (a large quantity of data blocks corresponding to a data unit) in order to provide for high recovery possibility for all receiving devices. For instance, it may be difficult for a transmitting device to estimate a successful transmission probability of one or more data units via one or more transmitted data blocks corresponding to the one or more data units without feedback from one or more receiving devices (such that the transmitting device may over-transmit data blocks in an effort to provide for successful reception by various receiving devices served by the transmitting device) . In some examples, this over-transmitting may result in excessively redundant transmission of data blocks (which may thus result in additional overhead, increased latency of communications, or reduced performance and capacity of broadcast channels, among other issues) .

According to the techniques described herein, a transmitting device (for example, a base station) may transmit encoded symbols (for example, via a broadcast channel) in accordance with an acknowledgement feedback threshold (such as a hybrid automatic repeat request acknowledgment (HARQ-ACK) threshold) , an erasure probability based threshold, or both. In some examples, a transmitting device may transmit encoded symbols of one or more data units until an acknowledgement feedback threshold has been satisfied, until an erasure probability based threshold has been satisfied, or until both thresholds have been satisfied, before transmitting encoded symbols of one or more other data units. In some examples, these techniques and operations may provide for more efficient signaling of encoded transmissions. For example, a quantity of redundant data symbols transmitted may be reduced while also successfully conveying one or more data units, the capacity of a broadcast channel may be increased over a given duration, and latency of broadcast channel communications may be reduced, among other advantages. Further, the described techniques may provide for transmitting device control or network control over an expected successful transmission probability (based on consideration of receiving device erasure probabilities) .

Aspects of the disclosure are initially described in the context of example wireless communications systems. Example encoding schemes and an example process flow are then described. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to fountain-code-based broadcast channel operation with limited feedback.

Figure 1 illustrates an example of a wireless communications system 100 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The wireless communications 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 communications system 100 may be a LTE network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a NR network. In some examples, the wireless communications system 100 may support enhanced broadband communications, ultra-reliable (for example, mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

The base stations 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may be devices in different forms or having different capabilities. The base stations 105 and the UEs 115 may wirelessly communicate via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base station 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a base station 105 and a UE 115 may support the communication of signals according to one or more radio access technologies.

The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated with reference to Figure 1. The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, the base stations 105, or network equipment (for example, core network nodes, relay devices, IAB nodes, or other network equipment) , as shown with reference to Figure 1.

The base stations 105 may communicate with the core network 130, or with one another, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (for example, via an S1, N2, N3, or other interface) . The base stations 105 may communicate with one another over the backhaul links 120 (for example, via an X2, Xn, or other interface) either directly (for example, directly between base stations 105) , or indirectly (for example, via core network 130) , or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

One or more of the base stations 105 described herein may include or may be referred to by a person having ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or other suitable terminology.

A UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, in which the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a multimedia/entertainment device (for example, a radio, a MP3 player, a video device) , a camera, a gaming device, a navigation/positioning device (for example, GNSS (global navigation satellite system) devices based on, for example, GPS (global positioning system) , Beidou, GLONASS, or Galileo, a terrestrial-based device) , a tablet computer, a laptop computer, a netbook, a smartbook, a personal computer, a smart device, a wearable device (for example, a smart watch, smart clothing, smart glasses, virtual reality goggles, a smart wristband, smart jewelry (for example, a smart ring, a smart bracelet) ) , a drone, a robot/robotic device, a vehicle, a vehicular device, a meter (for example, parking meter, electric meter, gas meter, water meter) , a monitor, a gas pump, an appliance (for example, kitchen appliance, washing machine, dryer) , a location tag, a medical/healthcare device, an implant, a sensor/actuator, a display, or any other suitable device configured to communicate via a wireless or wired medium. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices, and may provide for automated communication between machines (for example, via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. 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 business charging. In an aspect, techniques disclosed herein may be applicable to MTC or IoT UEs. MTC or IoT UEs may include MTC/enhanced MTC (eMTC, also referred to as CAT-M, Cat M1) UEs, narrowband IoT (NB-IoT) (also referred to as CAT NB1) UEs, as well as other types of UEs. eMTC and NB-IoT may refer to future technologies that may evolve from or may be based on these technologies. For example, eMTC may include FeMTC (further eMTC) , eFeMTC (enhanced further eMTC) , mMTC (massive MTC) , and NB-IoT may include eNB-IoT (enhanced NB-IoT) , FeNB-IoT (further enhanced NB-IoT) .

The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the base stations 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown with reference to Figure 1.

The UEs 115 and the base stations 105 may wirelessly communicate with one another via one or more communication links 125 over one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a radio frequency spectrum band (for example, a bandwidth part (BWP) ) that is operated according to one or more physical layer channels for a given radio access technology (for example, LTE, LTE-A, LTE-A Pro, NR) . Each physical layer channel may carry acquisition signaling (for example, synchronization signals, system information) , control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

Signal waveforms transmitted over a carrier may be made up of multiple subcarriers (for example, using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) . In a system employing MCM techniques, a resource element may consist of one symbol period (for example, a duration of one modulation symbol) and one subcarrier, in which the symbol period and subcarrier spacing are inversely related. The quantity of bits carried by each resource element may depend on the modulation scheme (for example, the order of the modulation scheme, the coding rate of the modulation scheme, or both) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. A wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (for example, spatial layers or beams) , and the use of multiple spatial layers may further increase the data rate or data integrity for communications with a UE 115.

The time intervals for the base stations 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T _s=1/ (Δf _max·N _f) seconds, in which Δf _max may represent the maximum supported subcarrier spacing, and N _f may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (for example, 10 milliseconds (ms) ) . Each radio frame may be identified by a system frame number (SFN) (for example, ranging from 0 to 1023) .

Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (for example, in the time domain) into subframes, and each subframe may be further divided into a number of slots. Alternatively, each frame may include a variable quantity of slots, and the quantity of slots may depend on subcarrier spacing. Each slot may include a quantity of symbol periods (for example, depending on the length of the cyclic prefix prepended to each symbol period) . In some wireless communications systems 100, a slot may further be divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (for example, N _f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (for example, in the time domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI) . In some examples, the TTI duration (for example, the quantity of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (for example, in bursts of shortened TTIs (sTTIs) ) .

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (for example, a control resource set (CORESET) ) for a physical control channel may be defined by a quantity of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (for example, CORESETs) may be configured for a set of the UEs 115. For example, one or more of the UEs 115 may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to a quantity of control channel resources (for example, control channel elements (CCEs) ) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets for sending control information to a specific UE 115.

Each base station 105 may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a base station 105 (for example, over a carrier) and may be associated with an identifier for distinguishing neighboring cells (for example, a physical cell identifier (PCID) , a virtual cell identifier (VCID) , or others) . In some examples, a cell may also refer to a geographic coverage area 110 or a portion of a geographic coverage area 110 (for example, a sector) over which the logical communication entity operates. Such cells may range from smaller areas (for example, a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station 105. For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with geographic coverage areas 110, among other examples.

A macro cell generally covers a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by the UEs 115 with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered base station 105, as compared with a macro cell, and a small cell may operate in the same or different (for example, licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to the UEs 115 with service subscriptions with the network provider or may provide restricted access to the UEs 115 having an association with the small cell (for example, the UEs 115 in a closed subscriber group (CSG) , the UEs 115 associated with users in a home or office) . A base station 105 may support one or multiple cells and may also support communications over the one or more cells using one or multiple component carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (for example, MTC, NB-IoT, enhanced mobile broadband (eMBB) ) that may provide access for different types of devices.

In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, the overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (for example, via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that makes use of the information or presents the information to humans interacting with the application program. Some UEs 115 may 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 business charging.

The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC) or mission critical communications. The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions (for example, mission critical functions) . Ultra-reliable communications may include private communication 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 prioritization of services, and mission critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission critical, and ultra-reliable low-latency may be used interchangeably herein.

In some examples, a UE 115 may also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (for example, using a peer-to-peer (P2P) or D2D protocol) . One or more UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105 or be otherwise unable to receive transmissions from a base station 105. In some examples, groups of the UEs 115 communicating via D2D communications may utilize a one-to-many (1: M) system in which each UE 115 transmits to every other UE 115 in the group. In some examples, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between the UEs 115 without the involvement of a base station 105.

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or 5G core (5GC) , which may include at least one control plane entity that manages access and mobility (for example, a mobility management entity (MME) , an access and mobility management function (AMF) ) and at least one user plane entity that routes packets or interconnects to external networks (for example, a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the base stations 105 associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to the network operators IP services 150. The operators IP services 150 may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched Streaming Service.

Some of the network devices, such as a base station 105, may include subcomponents such as an access network entity 140, which may be an example of an access node controller (ANC) . Each access network entity 140 may communicate with the UEs 115 through one or more other access network transmission entities 145, which may be referred to as radio heads, smart radio heads, or transmission/reception points (TRPs) . Each access network transmission entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (for example, radio heads and ANCs) or consolidated into a single network device (for example, a base station 105) .

The wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. The UHF waves may be blocked or redirected by buildings and environmental features, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. The transmission of UHF waves may be associated with smaller antennas and shorter ranges (for example, less than 100 kilometers) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band, or in an extremely high frequency (EHF) region of the spectrum (for example, from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, the wireless communications system 100 may support millimeter wave (mmW) communications between the UEs 115 and the base stations 105, and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

The wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, devices such as the base stations 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (for example, LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

A base station 105 or a UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, MIMO communications, or beamforming. The antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a quantity of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for a signal transmitted via an antenna port.

The base stations 105 or the UEs 115 may use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (for example, the same codeword) or different data streams (for example, different codewords) . Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include SU-MIMO, in which multiple spatial layers are transmitted to the same receiving device, and MU-MIMO, in which multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (for example, a base station 105, a UE 115) to shape or steer an antenna beam (for example, a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that some signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude offsets, phase offsets, or both to signals carried via the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (for example, with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

The wireless communications system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or a core network 130 supporting radio bearers for user plane data. At the physical layer, transport channels may be mapped to physical channels.

The UEs 115 and the base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (for example, using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (for example, automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (for example, low signal-to-noise conditions) . In some examples, a device may support same-slot HARQ feedback, in which the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

In some examples, the wireless communications system 100 may support techniques for efficient transmission of information (for example, data units) encoded using one or more fountain codes based on acknowledgement feedback from receiving devices, erasure probabilities associated with transmissions to receiving devices, or both. A transmitting device may generally include a base station 105, a UE 115, an integrated access and backhaul (IAB) network node, an IAB relay node, or another wireless device. The transmitting device may encode symbols using one or more fountain codes (such as LT codes or Raptor codes) . According to the techniques described herein, a transmitting device may transmit encoded symbols in accordance with an acknowledgement feedback threshold (such as a HARQ-ACK threshold) , an erasure probability based threshold, or both. As such, a transmitting device may transmit encoded symbols of a data unit until an acknowledgement feedback threshold has been satisfied, until an erasure probability based threshold has been satisfied, or until both thresholds have been satisfied before proceeding to transmit encoded symbols of a subsequent data unit.

For example, a transmitting device (such as a base station 105) may encode information (such as source symbols of a first data unit) into one or more data blocks (such as encoded symbols) using one or more fountain codes. The base station 105 may transmit the one or more data blocks, corresponding to the first data unit, to one or more receiving devices (such as one or more UEs 115 monitoring a broadcast channel for the one or more data blocks) . A UE 115 may then transmit an acknowledgement feedback message to the base station 105 upon reception of enough data blocks for the UE 115 to determine or successfully decode the first data unit. A base station 105 may continue to transmit encoded data blocks, corresponding to a first data unit, until a quantity of acknowledgement feedback messages received from one or more UEs 115 served by the base station 105 satisfies or exceeds a threshold (a HARQ-ACK threshold) , at which point the base station 105 may begin transmitting encoded data blocks corresponding to a next data unit (such as a second data unit after the first data unit) .

Additionally or alternatively, a base station 105 may transmit one or more data blocks, corresponding to a data unit, in accordance with an erasure probability based threshold. For example, the base station 105 may determine a respective erasure probability (a probability that a data block may be unsuccessfully received by a UE 115 based on channel conditions, a UE 115 capability, or other criteria) for each of one or more UEs 115 associated with a broadcast channel. The base station 105 may then determine a quantity of data blocks to transmit for a given data unit based on the determined erasure probabilities for one or more of the served UEs 115. For example, a base station 105 may determine a quantity of data blocks to transmit for a given data unit based on a highest erasure probability (associated with a worst-case scenario UE 115) or based on an average erasure probability (such that some average quantity of encoding symbols may be received by the served UEs 115) . Generally, the techniques described herein may enable network nodes (such as the base stations 105 and the UEs 115) to improve efficiency and reliability of communications in the wireless communications system 100 by reducing the amount of redundant overhead and communications latency while maintaining an efficient probability of successful decoding of transmitted information.

Figure 2 illustrates an example of a wireless communications system 200 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100. For example, the wireless communications system 200 may include a base station 105-a and the UEs 115-a through 115-d, which may be examples of the corresponding devices as described with reference to Figure 1. The wireless communications system 200 may illustrate a transmitting device (a base station 105-a) transmitting respective sets of encoded data blocks corresponding to each data unit 205 communicated over a broadcast channel 210. The UEs 115-a through 115-d may receive one or more sets of data blocks to receive, or successfully decode, respective data units 205.

As described herein, encoding schemes that employ error correcting codes may be based on the use of fountain codes (for example, such as LT codes or Raptor codes) . A fountain code may be an example of a rateless code in which a set of source symbols (K symbols) of a data unit 205 may be encoded as any quantity of data blocks or encoding symbols (for example, a quantity of symbols greater than K symbols) . Encoding the source symbols may include combining one or more source symbols into each encoding symbol. The encoding symbols (or data blocks) may be transmitted as a set of encoded symbols from a first node (for example, the base station 105-a) to one or more receiving nodes (for example, the UEs 115-a through 115-d) . For example, a data unit 205 (a data unit X) may be encoded into a set of data blocks of some block length. A block length X may represent the transmission of the data unit X (a block length X may correspond to the source symbols K of data unit X, the one or more fountain codes used for encoding, or the quantity of redundant transmissions of data blocks) . In some cases (for example, for broadcast channel transmission) there may be no UE 115 feedback mechanism to notify the base station 105-a about the success of the transmissions. As such, in some systems, a large quantity of redundant encoding symbols may be transmitted to provide for high recovery possibility for all UEs 115 (for example, because it may be difficult to estimate the successful transmission probability without the UE 115 feedback, such that the default may be to over-transmit in an effort to ensure success) . In some cases, such systems may be associated with unnecessary overhead and increased latency for broadcast channel communications.

According to the techniques described herein, a transmitting device (the base station 105-a) may transmit encoded symbols in accordance with an acknowledgement feedback threshold (such as a received HARQ-ACK threshold) , an erasure probability based threshold, or both. The transmitting device may transmit encoded symbols of a data unit 205 (data unit X) until an acknowledgement feedback threshold has been satisfied, until an erasure probability based threshold has been satisfied, or until both thresholds have been satisfied, before proceeding to transmit encoded symbols of a subsequent data unit (data unit X+1) .

For example, in some examples, the base station 105-a may transmit a first set of data blocks corresponding to encoded source symbols of a first data unit 205 (data unit X) . The first set of data blocks may be transmitted via the broadcast channel 210, which may be monitored by the UEs 115-a through 115-d. According to the techniques described herein, a UE 115 may transmit an acknowledgement feedback message 215 upon reception of N data blocks in which N data blocks may refer to a threshold quantity of data blocks used by the UE 115 in order to receive and successfully decode the corresponding K source symbols of the data unit 205 being transmitted by the base station 105-a (as described in more detail herein, for example, with reference to Figure 3) . For instance, in the example of Figure 2, the UEs 115-a through 115-c may each receive at least N data blocks (such that the UEs 115-athrough 115-c may each receive and successfully decode a corresponding data unit 205) . Generally, the UEs 115-a through 115-d may each transmit respective acknowledgement feedback messages 215 at the time at which N data blocks are received by the corresponding UE 115.

The base station 105-a may transmit a first set of data blocks (which may be referred to as encoded data blocks) corresponding to a first data unit 205 (data unit X) . The base station 105-a may transmit the encoded data blocks, corresponding to the first data unit 205 (data unit X) , until a quantity of acknowledgement feedback messages 215 received from the UEs 115-a through 115-d served by the base station 105-a satisfies or exceeds a threshold (a HARQ-ACK threshold of a%) , at which point the base station 105-a may begin transmitting encoded data blocks corresponding to a next data unit 205 (data unit X+1) . That is, the UEs 115-a through 115-d may transmit an acknowledgment feedback message (an ACK feedback message) upon successful decoding of the first data unit 205 (for example, which may be based on successful reception of N>K data blocks for recovery or decoding of the K source symbols of the first data unit 205) . The base station 105-a may thus transmit the first set of data blocks until ACK feedback messages are received from a threshold quantity of UEs 115 (for example, until a threshold quantity of UEs indicate successful reception of N>K data blocks or successful decoding of the entire first data unit 205.

In the example of Figure 2, the base station 105-a may receive some percentage (for example, a%) of acknowledgement feedback messages 215 from the served UEs 115-a through 115-d at time 220, and the base station 105-a may proceed to transmit a second set of data blocks corresponding to a next data unit X+1. Subsequently, after the base station 105-a receives some percentage (for example, a%) of acknowledgement feedback messages 215 from the served UEs 115-a through 115-d that correspond to the second data unit X+1 (at time 225) , the base station 105-a may proceed to transmit a third set of data blocks corresponding to a next data unit X+2. The base station 105-a may proceed in such a manner until all data units (including some last data unit N) are transmitted by the base station 105-a and are acknowledged by some a%of served UEs 115.

In examples in which the base station 105-a transmits fountain codes (for example, Raptor code, LT-code, or both) based broadcast channel 210 transmissions, the UEs 115-a through 115-d may transmit an acknowledgement feedback message including a 1-bit ACK ( ‘1’ ) to the base station 105-a upon successful recovery of the data unit i. Otherwise (for example, if the data unit i is not recovered successfully, which may be the case if a quantity of received data blocks N is less than K) , the UE may not transmit feedback to the base station 105-a. In some examples, the acknowledgement feedback message may include other information (via additional bits) , such as a data index (X) corresponding to the acknowledgement feedback message, a UE ID of the UE 115 transmitting the acknowledgement feedback message, or other information, depending on implementation. As described, the base station 105-a may stop sending the first set of data blocks corresponding to the first data unit (data unit X) and may begin transmission of a second set of data blocks corresponding to a second data unit (data X+1) after the base station 105-a receives acknowledgement feedback messages, that correspond to the data X, from a%of the served UEs 115-a through 115-d (at time 220) .

Additionally or alternatively, a transmitting device (the base station 105-a) may transmit one or more data blocks, corresponding to a data unit 205, in accordance with an erasure probability based threshold. For example, the base station 105-a may determine a respective erasure probability (a probability that a data block is unsuccessfully received by a UE 115 based on channel conditions or a UE 115 capability, among other examples) for each of the served UEs 115-a through 115-d associated with a broadcast channel 210. The base station 105-a may then determine a quantity of data blocks to transmit for a given data unit 205 based on the determined erasure probabilities for one or more of UEs 115-a through 115-d. For example, due to the rateless nature of fountain-code-based encoding, the base station 105-a may determine a quantity of data blocks to transmit for a given data unit 205 based on a highest erasure probability (associated with a worst-case scenario UE 115) or based on an average erasure probability (such that some average quantity of encoding symbols may be received by the served UEs 115-a through 115-d) .

For instance, the base station 105-a may consider the erasure probability {p ₀, p ₁, p ₂, …, p _U-1, } for U UEs when transmitting data or information (for example, data units 205 encoded into a set of data blocks using one or more fountain codes) over broadcast channel 210. Specifically, in some examples, the base station 105-a may determine a quantity (a number) of data blocks to be transmitted for a given data unit 205 based on one or more erasure probabilities of the served UEs 115-a through 115-d. The quantity of data blocks may be determined to satisfy some erasure probability based threshold. For a UE i associated with an erasure probability p _i, Quantity _{ReceivedPackets}=p _i*Quantity _{TransmittedPackets}.

For example, in some implementations, the base station 105-a may determine a highest erasure probability (for example, corresponding to a worst-case-scenario UE 115 or a UE 115 with the highest probability of erasure of communications from the base station 105-a) , and the base station 105-a may determine the quantity of data blocks (encoding symbols) to be transmitted for a given data unit 205 based on the highest erasure probability. In other words, a transmitting device may transmit

data blocks (encoding symbols) over the broadcast channel 210, which may result in the worst-case-scenario UE 115 (for example, the UE 115 with the highest erasure probability) being able to receive N encoding symbols (such that the worst-case-scenario UE 115 may be able to successfully decode the corresponding data unit 205 based on N>K as described herein, for example, with reference to Figure 3) . In some examples, transmitting

data blocks may be referred to herein as transmitting one or more data blocks, corresponding to a data unit 205, in accordance with a highest erasure probability based threshold. In other words, the base station 105-a may determine a ceiling of the quantity of data blocks N to transmit over broadcast channel 210 such that a UE 115 with the lowest or minimum reception probability (and highest probability of erasure) may still receive N data blocks for successful reception and decoding of K source symbols of the corresponding data unit 205.

In other examples, the base station 105-d may determine an average erasure probability (from the {p ₀, p ₁, p ₂, …, p _U-1, } for U UEs) , and the base station 105-a may determine the quantity of data blocks (encoding symbols) to be transmitted for a given data unit 205 based on the average erasure probability. In other words, a transmitting device may transmit

data blocks (encoding symbols) over the broadcast channel 210, which may result in the average UE 115 served by the base station 105-a being able to receive N encoding symbols (such that the average quantity of data blocks received by a served UE 115 may be N for successful decoding of the corresponding data unit 205 based on N>K as described herein, for example, with reference to Figure 3) . In some examples, transmitting

data blocks may be referred to herein as transmitting one or more data blocks, corresponding to a data unit 205, in accordance with an average erasure probability based threshold.

Generally, wireless communications system 200 (and the base station 105-a) may be configured to support transmissions (fountain code-based encoded transmissions) based on various erasure probabilities by analogy, without departing from the scope of the described techniques. For instance, the base station 105-a may determine a quantity of data blocks (encoded symbols) to transmit for a given data unit 205 based on one or more given erasure probabilities (for example a minimum erasure probability, a maximum erasure probability, an average erasure probability, an erasure probability above or below some threshold, among other examples) , in order to realize various overhead metrics, reliability metrics, efficiency metrics, among other examples. Accordingly, the quantity of the one or more data blocks transmitted by the transmitting device may satisfy the employed erasure probability based threshold (for example, such that the number of transmitted data blocks satisfies N>K at served receiving devices for a highest erasure probability, for the average erasure probability, or some other erasure probability) .

In some examples, wireless communications system 200 may be configured to support transmissions (fountain code-based encoded transmissions) based on an acknowledgement feedback message threshold, an erasure probability based threshold, or both. For example, in some implementations, the UEs 115-a through 115-d served by the base station 105-a via broadcast channel 210 may not be configured to transmit acknowledgement feedback messages 215, and the base station 105-a may transmit a quantity of data blocks for each respective data unit 205 determined based on one or more erasure probabilities associated with the served UEs 115-a through 115-d.

In some examples, the base station 105-a may determine an erasure probability for each served UE 115 based on previous communications (such as based on previous HARQ-ACK processes) , based on channel measurements, or based on received signal measurements from a corresponding UE 115, among other examples. In some examples, each of the UEs 115 may determine its respective erasure probability and transmit an indication of such to the base station 105-a. For instance, in some examples, each of the UEs 115-a through 115-d may count a quantity of received symbols (over some interval) and determine its respective erasure probability by comparing the counted quantity of received symbols to a symbol ID (or packet ID) of a most recently received symbol.

For example, the UE 115-a may count 9 received symbols, and the last received symbol may correspond to a symbol ID of 10. In such an example, the UE 115-a may determine it has received 9 of 10 symbols, such that the erasure probability of the UE 115-a may be 10% (in which the reception probability is 90%) . In cases in which the UE 115-d counts 8 received symbols in which the last received symbol corresponds to a symbol ID of 10, the UE 115-d may determine it has received 8 of 10 symbols such that the erasure probability of the UE 115-d may be 20% (in which the reception probability is 80%) . In such an example, the UE 115-d may have the higher erasure probability. In cases in which the base station 105-a transmits one or more data blocks, corresponding to a data unit 205, in accordance with a highest erasure probability based threshold, the base station 105-a may transmit

data blocks. In cases in which the base station 105-a transmits one or more data blocks, corresponding to a data unit 205, in accordance with an average erasure probability based threshold, the base station 105-a may transmit

data blocks.

Figure 3 illustrates an example of an encoding scheme 300 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, the encoding scheme 300 may implement aspects of wireless communications system 100 or wireless communications system 200. For example, the encoding scheme 300 may be associated with communications between a transmitting device, such as a base station 105, and a receiving device, such as a UE 115, as described herein.

The encoding scheme 300 may use Raptor coding to encode symbols for transmission, for example via a broadcast channel between a base station 105 and a UE 115. A base station 105 may encode a set of source symbols 305 (for example, a quantity K of source symbols 305) into a set of encoding symbols 325 (which may be referred to herein as a set of data blocks) . The quantity of encoding symbols 325 may be greater than the quantity of source symbols 305 to improve a probability of successfully decoding the source symbols 305 at a receiving device (such as one or more UEs 115 served by the base station 105) . In some examples, the encoding scheme 300 may be rateless in which the quantity of encoding symbols 325 may have no upper limit.

The encoding scheme 300 may include a precoding process 310. In the precoding process 310, the transmitting device may map one or more source symbols 305 to each of a set of intermediate symbols 315 (for instance, in the example of Figure 3, the K=6 source symbols may be mapped to the set of 9 intermediate symbols which may include 3 redundant intermediate symbols) . The transmitting device may generate a quantity of redundant intermediate symbols 315 (for example, a quantity of intermediate symbols 315 in addition to a quantity K of intermediate symbols 315 directly mapped to the K source symbols 305) . In some examples, the redundant intermediate symbols 315 may include a quantity S of low-density parity-check (LDPC) symbols in which one or more copies of each source symbol 305 may be represented in each LDPC symbol. Additionally or alternatively, the redundant intermediate symbols 315 may include a quantity H of half symbols in which each half symbol may include ceil (H/2) source symbols 305, and in which ceil (x) may represent a ceiling function mapping x to a least integer greater than or equal to x. For example, for each half symbol generation, ceil (H/2) source symbols may be randomly chosen and XORed.

The encoding scheme 300 may include an LT coding process 320 following the precoding process 310. In the LT coding process 320, the transmitting device may map the intermediate symbols 315 to the set of encoding symbols 325. The LT coding process 320 may employ a degree distribution Ω in which degree d _i (for example, d ₁, d ₂, d ₃, …) may follow the degree distribution Ω. The probability of randomly selecting a degree d _i (for example, a degree with index i) from the degree distribution may be represented by ρ (i) . In the LT coding process 320, the degree d _i may represent the degree of the ith encoding symbol 325 (the quantity of intermediate symbols 315 which the transmitting device may combine into an ith encoding symbol 325) . For example, if the degree d ₁=2 is selected for a first encoding symbol 325, two intermediate symbols 315 may be randomly selected and combined into the first encoding symbol 325. Similarly, if the degree d ₂=1 is selected for a second encoding symbol, a single intermediate symbol 315 may be combined into the second encoding symbol 325. In some examples, the intermediate symbols 315 may be combined into encoding symbols 325 using a logic operation such as a logic XOR operation. In some examples, each encoding symbol 325 may include information identifying the source symbols 305 used to construct the encoding symbol 325. For example, the encoding symbol may include indices (for example, s ₁, s ₂, s ₃, s _K) associated with the source symbols 305 used to construct the encoding symbol 325.

The encoding symbols 325 may be transmitted as a set of data blocks from the transmitting device to the receiving device (for example, via a broadcast channel) . In some examples, the encoding scheme 300 may be represented by a generator matrix G, for example, associated with one or more fountain codes that are rateless with unlimited columns. The K source symbols 305 contained in the encoding symbols 325 of a given encoded symbol may be represented by p _j, which may be defined by Equation (1) below:

In some examples, one or more encoded symbols (data blocks) may be lost based on the conditions of the communication link between a transmitting device and a receiving device within a transmission environment. The number of lost symbols may be associated with an erasure probability. The receiving device may receive a subset of encoded symbols (for example, a quantity N of encoded data blocks) via the multi-hop network. The source symbols 305 contained in encoding symbols 325 of a given encoded symbol received (or recovered, successfully decoded) by the receiving device may be represented by SS _k, which may be defined by Equation (2) below:

Based on the encoding scheme 300, the receiving device may recover all source symbols 305 in the set of K source symbols 305 when the matrix G _nk of the received symbols is invertible. Additionally or alternatively, the receiving device may recover all source symbols 305 in the set of K source symbols 305 when the matrix G _nk of the received symbols has a rank K in which K is the quantity of source symbols 305 in the set of source symbols 305. To increase a probability of the receiving device successfully decoding the set of source symbols 305, the encoding scheme 300 may be designed such that the representative generator matrix G _nk is invertible for a minimum quantity N of received encoded symbols. For example, encoding scheme 300 may be implemented such that the original generator matrix (G _kj) is designed such that symbols received by a receiving device may be combined to generate or obtain a reconstruction matrix G _nk, which may be invertible, when a minimum N>K symbols are received, to obtain the K source symbols.

The receiving device may decode the received encoding symbols 325 to obtain the source symbols 305. For example, the receiving device may decode N>K received encoding symbols 325 to obtain the K source symbols 305 (which may be referred to as receiving or successfully decoding the data unit corresponding to the K source symbols 305) . The receiving device may begin a decoding process by identifying an encoding symbol 325 with an index t _j that is connected to a single source symbol 305 with an index s _i. The receiving device may determine that the encoding symbol 325 with index t _j is equivalent to the source symbol 305 with index s _i. The receiving device may then apply an XOR operation to each other encoding symbol 325 connected to the source symbol 305 with index s _i, and remove all edges connected to the source symbol 305 with index s _i to determine or obtain the s _i source symbol 305. The receiving device may repeat this process until each source symbol 305 is determined from the received encoding symbols 325.

In some examples, LT coding process 320 may be implemented to reduce encoding and decoding complexity of the encoding scheme 300. In some examples, a transmitting device may randomly select a degree d _i from a degree distribution Ω for each encoding symbol 325. The transmitting device may randomly select d _i distinct source symbols 305 with uniform distribution and XOR them. During the decoding process , a receiving device may find an encoding symbol t _j (for example, an encoding symbol 325-a) that is connected to only one source symbol s _i (for example, an source symbol 305-a) , and the receiving device may set s _i=t _j, XOR s _i to encoding symbols that are connected to s _i, and remove the edges connected to the source symbol s _i. The receiving device may repeat such a process until all s _i are determined. If there is no encoding symbol (received by the receiving device) that is connected to only one source symbol, the decoding process may fail.

In some examples, Raptor codes may be implemented to further reduce the encoding and decoding complexities of the LT-code-based encoding scheme 300 by reducing the average degree. For example, a coding scheme that employs Raptor codes (such as encoding scheme 300) may include the additional precoding stage 310 (compared to encoding schemes employing standalone LT codes) . As described herein, the precoding stage 310 may include generation of redundant intermediate symbols 315 (which may include S LDPC symbols and H Half symbols) . For instance, K source symbols may be used to generate intermediate symbols 315 including redundant nodes (redundant intermediate symbols 315) and the intermediate symbols 315 may all be used to generate the encoding symbols 325 (via LT coding process 320) . As such, a receiving device may only need to decode some of the intermediate symbols 315 (for example, some unique intermediate symbols 315 and some redundant intermediate symbols 315) to determine the source symbols 305 (in which the redundant intermediate symbols 315 may aid in such determination and reduce decoding complexity, as source symbols 305 with high degree distribution may not necessarily need to be directly recovered due to utilization of redundant intermediate symbols 315) .

According to the techniques described herein, a transmitting device (such as a base station 105) may implement encoding schemes (such as encoding scheme 300 or similar encoding schemes) based on acknowledgement feedback thresholds, erasure probability based thresholds, or both acknowledgement feedback thresholds and erasure probability based thresholds. For example, various aspects of encoding scheme 300 may be designed or implemented to provide for efficient fountain-code-based transmissions in accordance with techniques described herein.

In examples in which acknowledgement feedback thresholds are implemented, a transmitting device may transmit encoding symbols 325 until acknowledgement feedback messages are received from a threshold quantity (α%) of UEs. In some examples, a transmitting device may transmit additional encoding symbols 325 until acknowledgement feedback messages are received from enough served UEs according to the acknowledgement feedback threshold (for instance, the rateless encoding itself may not cease until the threshold α%has been met) . In other examples, a transmitting device may drop encoding symbols 325 that have already been generated if acknowledgement feedback messages are received from enough served UEs according to the acknowledgement feedback threshold (and the transmitting device may proceed with transmission of data blocks associated with a next data unit) . In cases in which erasure probability based thresholds are implemented, a transmitting device may determine a quantity of encoding symbols 325 to be transmitted based on the erasure probability based threshold (as described in more detail herein, for example, with reference to Figure 2) . In some examples, the precoding process 310 may be implemented such that a quantity of intermediate symbols 315 (and redundant intermediate symbols 315) generated may conform with the quantity of encoding symbols 325 determined based on the erasure probability based threshold.

Generally, encoding scheme 300 may be modified, by analogy, for efficient transmission of information (for example, source symbols 305 of corresponding data units) encoded using one or more fountain codes based on the techniques described herein. For instance, precoding process 310 or LT coding process 320 may be implemented to adhere generation and transmission of encoding symbols 325 to acknowledgement feedback thresholds, erasure probability based thresholds, or both. The encoding scheme 300 described herein may enable improved efficiency and reliability of communications (such as, for example, broadcast communications) by reducing the number of transmitted encoding symbols 325 (when N>K symbols have been received by α%of receiving devices) and, in some examples, by increasing receiving devices’ probabilities of successful decoding source symbols 305 transmitted as encoding symbols 325. Moreover, the techniques described herein may be implemented for increased network control and configurability (for example, encoding scheme 300 may be implemented based on a highest erasure probability, an average erasure probability, or some other erasure probability, based on network tradeoffs in efficiency, reliability, overhead, and throughput) .

Figure 4 illustrates an example of an encoding and transmission scheme 400 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, the encoding and transmission scheme 400 may implement aspects of wireless communications system 100, wireless communications system 200, or encoding scheme 300. For example, the encoding and transmission scheme 400 may be associated with communications between a transmitting device, such as a base station 105, and one or more receiving devices, such as UEs 115, as described herein. Encoding and transmission scheme 400 may illustrate how source symbols 410 (s ₀ through s _K) of a data unit 405 may be encoded into, and transmitted as, encoding symbols 415 (p ₀, p ₁, p ₂, …) . In some examples, encoding symbols 415 (p ₀, p ₁, p ₂, …) may be referred to herein as data blocks.

In the illustrated example, the encoding and transmission scheme 400 may employ fountain coding (such as Raptor coding or LT coding) to encode source symbols 410 into encoding symbols 415 for transmission to receiving devices. For example, a data unit 405 may include some quantity (n) bits. The n bits of a data unit 405 may be partitioned into some quantity (K) source symbols 410. For instance, each source symbol 410 may include some quantity (l) bits, and the n bits of a data unit 405 may be partitioned into K source symbols 410 based on sets of l bits. In other words, each data unit of length n may be partitioned into

source symbols 410 (which in some examples may be referred to as input symbols) in which each source symbol 410 includes l bits. A transmitting device (for example, an encoder) may use these K source symbols 410 to generate encoding symbols 415 as described herein.

A receiving device may recover a data unit 405 with high probability when N>K encoding symbols 415 are received (for example, due to properties of fountain codes, such as Raptor codes, described herein with reference to Figures 2 and 3) . For example, in some examples a data unit 405 may be partitioned into K=600 source symbols 410, a transmitting device may encode the source symbols 410 into 700 encoding symbols 415, and a receiving device may receive N=650 encoding symbols 415 (for example, with an erasure probability of 7.14%and a reception probability of 92.86%) . In such an example, the receiving device may receive and successfully decode the data unit 405 because the receiving device received N>K encoding symbols 415. As used herein, receiving may refer to successful decoding of a data unit 405. For example, in some examples, receiving a data unit may refer to receiving and successfully decoding a threshold quantity N symbols (for example, where N>K) encoding symbols 415 associated with a transmitted data unit 405. In some examples, receiving a data unit may refer to determining that N>K encoding symbols 415 associated with a transmitted data unit 405 have been received, such that decoding the data unit 405 is possible by the receiving device (for example, the use of “receiving” may not necessarily imply decoding has been performed or is being performed) .

For a broadcast channel with erasures (for example, for transmission environments associated with an erasure probability for communications between a transmitting device and a receiving device) , one or more of encoding symbols 415 may be erased or unsuccessfully received by a receiving device (due to channel conditions, including interference or blockage) . For example, in some examples, an encoding symbol p ₂ may be erased or otherwise unsuccessfully received by a receiving device due to channel conditions. However, as described herein, in some examples, some fountain codes (for example, Raptor codes) may be used such that as long as a receiving device receives N>K encoding symbols 415, the receiving device may be able to recover (receive) the corresponding data unit 405.

As described herein, in some implementations, receiving devices (for example, UEs 115 monitoring a broadcast channel for fountain code-based broadcast data) may transmit acknowledgement feedback messages (for example, ACK/NACKs) to a transmitting device (for example, a base station 105 serving the UEs 115) . Such feedback may reduce large quantities of redundant encoding symbols while maintaining efficient data unit recovery for receiving devices. For instance, a transmitting device may cease transmission of encoding symbols 415 associated with a data unit 405 that has been recovered by some α%of receiving devices (in accordance with ACK/NACK received from received devices and an acknowledgement feedback message threshold) , rather than continuing to transmit additional or redundant encoding symbols 415 in systems that do not utilize limited feedback from receiving devices.

Additionally or alternatively, as described herein, a transmitting device (for example, a base station 105 serving UEs 115 via a broadcast channel) may determine a quantity of encoding symbols 415 to transmit to receiving devices (for example, the UEs 115 monitoring the broadcast channel for fountain code-based broadcast channel data) based on one or more erasure probability based thresholds. Such techniques may reduce large quantities of redundant encoding symbols while maintaining efficient data unit recovery for receiving devices. For instance, a transmitting device may determine a quantity of encoding symbols 415 to transmit based on a worst-case-scenario receiving device, based on a desired expected successful transmission probability or based on a desired average quantity of N encoding symbols 415 to be received by receiving devices, among other examples. The transmitting device may then cease transmission (and encoding) of encoding symbols 415 associated with a data unit 405 after the determined quantity of encoding symbols 415 have been transmitted (in accordance with one or more erasure probability based thresholds) , rather than continuing to transmit additional or redundant encoding symbols 415 without regard to erasure probabilities associated with receiving devices.

Figure 5 illustrates an example of an encoding and transmission scheme 500 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, the encoding and transmission scheme 500 may implement aspects of wireless communications system 100, wireless communications system 200, encoding scheme 300, or encoding and transmission scheme 400. For example, the encoding and transmission scheme 500 may be associated with communications between a transmitting device, such as a base station 105, and one or more receiving devices, such as UEs 115, as described herein. Encoding and transmission scheme 500 may illustrate examples in which data blocks 505 associated with different data units may be transmitted in an interleaved pattern in accordance with one or more acknowledgement feedback message thresholds.

For instance, in some examples, a transmitting device may spend some time transmitting some data blocks for a previous data unit ‘O’ (data X) after beginning to transmit data blocks for a subsequent data unit ‘N’ (data X+1) . In the example of Figure 5, data blocks 505 ( ‘O’ data blocks) corresponding to encoding symbols of a previous data unit X may be interleaved with data blocks 510 ( ‘N’ data blocks) corresponding to encoding symbols of a subsequent (current) data unit X+1. A transmitting device may transmit data blocks for the subsequent data unit X+1 in response to receiving acknowledgement feedback messages from a quantity of receiving devices that satisfies a data unit transition threshold (for example, ACKs from b%of served UEs) at time 515. The transmitting device may stop or cease transmission of data blocks for the previous data unit X when the transmitting device receives acknowledgement feedback messages from a quantity of receiving devices that satisfies a data unit stop threshold (for example, ACKs from b′%of served UEs) at time 520.

For example, a transmitting device may transmit encoding symbols (data blocks 505) corresponding to a data unit X. At time 515, the transmitting device may receive acknowledgement feedback messages from a quantity of receiving devices that satisfies a data unit transition threshold (for example, ACKs from b%of served UEs for beginning to transmit data blocks corresponding to a subsequent data unit X+1) . After the data unit transition threshold has been satisfied (for example, after receiving ACKs from b%of served UEs that correspond to data unit X+1) , the transmitting device may begin transmission of a set of data blocks (of block length X+1) that includes both data blocks 505 (corresponding to the data unit X) as well as data blocks 510 (corresponding to the data unit X+1) . Upon receipt of at least some remaining acknowledgement feedback messages from receiving devices that had not yet acknowledged the previous data X, the transmitting device may cease transmission of encoding symbols (data blocks 505) corresponding to the previous data X and proceed to only transmit data blocks 510 corresponding to the data X+1. For example, at time 520, the transmitting device may receive a total number of ACKs from b′%of served UEs, which may satisfy a data unit stop threshold.

At 525, the transmitting device may receive acknowledgement feedback messages from a quantity of receiving devices that satisfies the data unit transition threshold for data unit X+1 (for example, the transmitting device may receive ACKs from b%of served UEs that correspond to data unit X+1, such that the transmitting device may begin to transmit data blocks corresponding to a subsequent data unit X+2) . In such cases, the transmitting device may begin transmitting data blocks of a block length X+2 that may include data blocks 510 corresponding to data unit X+1 as well as data blocks corresponding to data unit X+2 (for example, in an interleaved pattern) . Upon reception of a total number of ACKs from b′%of served UEs that correspond to data unit X+1, which may satisfy a data unit stop threshold for data unit X+2, the transmitting device may cease transmission of the data unit X+1.

In general, one or more acknowledgement feedback message thresholds may be implemented. In the example of Figure 5, a first acknowledgement feedback message threshold (b%) may be satisfied before a transmitting device transitions to transmitting data blocks of a next data unit X+1 and a second acknowledgement feedback message threshold (b′%) may be satisfied before a transmitting device ceases transmission of data blocks associated with the data unit X (for example, in which b′> b) .

In some examples, because there is no NACK feedback (as no feedback is transmitted by a receiving device until reception of N>K data blocks are received) , a receiving device may feedback ‘1’ for the ACK of the current data (for example, for data X+1 in the example of Figure 5) and ‘0’ for the ACK of previous data (for example, for data X in the example of Figure 5) .

Figure 6 illustrates an example of a process flow 600 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, the process flow 600 may implement aspects of wireless communications system 100, wireless communications system 200, encoding scheme 300, encoding and transmission scheme 400, or encoding and transmission scheme 500. Process flow 600 may include a base station 105-b, a UE 115-e, and a UE 115-f, which may be respective examples of a base station 105 and UEs 115 described herein. In the following description of the process flow 600, the operations between the base station 105-b, the UE 115-e, and the UE 115-f may be transmitted in a different order than the order shown, or the operations performed by the base station 105-b, the UE 115-e, and the UE 115-f may be performed in different orders or at different times. Some operations may also be left out of the process flow 600, or other operations may be added to the process flow 600. It is to be understood that while the base station 105-b, the UE 115-e, and the UE 115-f are shown performing a number of the operations of process flow 600, any wireless device may perform the operations shown.

At 605, the base station 105-b may encode one or more first data units (for example, K source symbols of n bits of data) into a first set of data blocks (for example, encoding symbols) using one or more fountain codes (for example, Raptor codes, LT codes) . For example, the base station 105-b may determine a set of source symbols for the one or more first data units, generate one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme (in which the one or more intermediate symbols comprises at least one redundant intermediate symbol) , and generate a set of encoded symbols based at least in part on the one or more intermediate symbols.

At 610, the base station 105-b may transmit the first set of data blocks to one or more UEs (such as the UE 115-e and the UE 115-f) via one or more broadcast channels.

At 615, the UEs 115-e and 115-f may monitor for, and attempt to receive and decode, the first set of data blocks. For example, due to erasure, the UEs 115-e and 115-f may receive subsets of the full first set of data blocks transmitted by the base station 105-b (as some encoding symbols of the first set of data blocks may be erased on the broadcast channel) .

At 620, the UE 115-e may transmit an acknowledgement feedback message to the base station 105-b in accordance with the techniques described herein. For example, the UE 115-e may monitor for the first set of data blocks at 615, and may transmit an ACK upon reception of N>K data blocks (such that the first data unit may be recovered by the UE 115-e) .

At 625, the UE 115-f may, in some implementations, transmit an acknowledgement feedback message to the base station 105-b in accordance with the techniques described herein. For example, the UE 115-f may monitor for the first set of data blocks at 615, and may transmit an ACK if the UE 115-f successfully receives N>K data blocks (such that the first data unit may be recovered by the UE 115-f) . In some examples, the UE 115-f may not successfully receive N>K data blocks (and thus may not transmit an acknowledgement feedback message at 625.

At 630, the base station 105-b may determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold (for example, the base station 105-b may determine that it has received acknowledgement feedback messages from α%of the served UEs 115) . In such cases, the base station 105-b may cease transmitting the first set of data blocks based at least in part on the received one or more acknowledgement feedback messages.

At 635, the base station 105-b may encode one or more second data units (for example, K source symbols of n bits of a second data) into a second set of data blocks (for example, encoding symbols) using one or more fountain codes (for example, Raptor codes, LT codes) . At 640, the base station 105-b may transmit the second set of data blocks to one or more UEs (such as the UE 115-e and the UE 115-f) via the one or more broadcast channels.

As described herein, the base station 105-b may transmit data blocks corresponding to different data units in accordance with one or more acknowledgement feedback message thresholds. For example, in some implementations, the base station 105-b may cease transmission of the first set of data blocks at 630 upon receiving ACKs from α%of the served UEs 115. In other cases, the base station 105-b may begin transmission of the second set of data blocks at 640 upon receiving ACKs from b%of the served UEs 115, and the base station 105-b may cease transmission of the first set of data blocks at 630 (occurring after 640) upon receiving ACKs from b′%of the served UEs 115. For instance, in some implementations the base station 105-b may receive one or more acknowledgement feedback messages from the one or more UEs 115-e and 115-f and determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold (for example α%or b%) .

In some examples, the base station 105-b may receive one or more second acknowledgement feedback messages from the one or more UEs 115-e and 115-f and determine that a second quantity comprising the one or more acknowledgement feedback messages and the one or more second acknowledgement feedback messages satisfies a second threshold (for example b′%, in which b′ considers all received acknowledgement feedback messages corresponding to a given data unit) . For instance, in examples where the base station 105-b transmits a second set of data blocks including data blocks corresponding to the first data unit interleaved with data blocks corresponding to a second data unit, the base station 105-b may receive additional acknowledgment feedback message corresponding to the first data unit (for example, from one or more UEs that did not acknowledge the first data unit based on the first set of data blocks) . In such cases, when the total ACKs corresponding to the first data unit (received in response to data blocks of the first set of data blocks and received in response to data blocks of the second set of data blocks that correspond to the first data unit) are received from b′%of served UEs, base station 105-b may cease transmission of data blocks corresponding to the first data unit (for example, data blocks of the second set of data blocks transmitted after ACKs are received from b′%of served UEs may correspond only to the second data unit) .

In some examples, the base station 105-b may transmit at least a subset of the first set of data blocks (at 610) and at least a subset of the second set of data blocks (at 640) in an interleaved pattern (as described in more detail herein, for example, with reference to Figure 5) . In such examples, in some implementations, a UE 115 (for example, the UE 115-e or the UE 115-f) may transmit a positive acknowledgement (at 620, 625, or after 640) indicating that the UE 115 received the current data unit (data unit X) . In some examples, a UE 115 (for example, the UE 115-e or the UE 115-f) may transmit a negative acknowledgement (at 620, 625, or after 640) indicating that the UE 115 received the previous data unit (data unit X-1) .

Figure 7 illustrates an example of a process flow 700 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. In some examples, the process flow 700 may implement aspects of wireless communications system 100, wireless communications system 200, encoding scheme 300, encoding and transmission scheme 400, encoding and transmission scheme 500, or process flow 600. Process flow 700 may include a base station 105-c, a UE 115-g, and a UE 115-h, which may be respective examples of a base station 105 and UEs 115 described herein. In the following description of the process flow 700, the operations between the base station 105-c, the UE 115-g, and the UE 115-h may be transmitted in a different order than the order shown, or the operations performed by the base station 105-c, the UE 115-g, and the UE 115-h may be performed in different orders or at different times. Some operations may also be left out of the process flow 700, or other operations may be added to the process flow 700. It is to be understood that while the base station 105-c, the UE 115-g, and the UE 115-h are shown performing a number of the operations of process flow 700, any wireless device may perform the operations shown.

At 705, the base station 105-c may determine a respective erasure probability for each of one or more UEs 115 (the UE 115-g and the UE 115-h) associated with one or more broadcast channels. In some examples, the base station 105-c may determine such erasure probabilities based on indications from the UEs 115. For example, the UE 115-g and the UE 115-h may determine an erasure probability based at least in part on a quantity of data blocks received from the base station 105-c, a symbol identification of a symbol received from the base station, one or more channel measurements, or any combination thereof. The UE 115-g and the UE 115-h may then each transmit an indication of their respective determined erasure probability to the base station 105-c. In other examples, the base station 105-c may determine or estimate the respective erasure probability for each of one or more UEs 115.

At 710, the base station 105-c may determine a quantity of data blocks to be transmitted for one or more data units based on the respective erasure probabilities for the U served UEs (determined at 705) . As described herein, the base station 105-c may determine a highest erasure probability of the determined erasure probabilities for the one or more UEs, an average erasure probability based at least in part on the determined erasure probabilities for the one or more UEs, or some other erasure probability based threshold. The base station 105-c may then determine a quantity of data blocks to transmit for the first one or more data units based at least in part on the implemented erasure probability based threshold and a second quantity of data blocks associated with successful reception of the one or more first data units by UE (for example, the second quantity of data blocks based on a quantity K of source symbols associated with the one or more first data units) .

At 715, the base station 105-c may encode one or more first data units (for example, K source symbols of n bits of data) into a first set of data blocks (for example, encoding symbols) using one or more fountain codes (for example, Raptor codes, LT codes) in accordance with the determined quantity of data blocks. For example, the base station 105-b may determine a set of source symbols for the one or more first data units, generate one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme (in which the one or more intermediate symbols comprises at least one redundant intermediate symbol) , and generate a set of encoded symbols based at least in part on the one or more intermediate symbols.

At 720, the base station 105-c may transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on at least one erasure probability of the determined erasure probabilities for the one or more UEs. For instance, the base station 105-c may transmit the determined quantity of the first set of data blocks to the one or more UEs 115.

At 725, the base station 105-c may cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on transmitting the determined quantity of the first set of data blocks.

Generally, the base station 105-c may determine a quantity of data blocks based at least in part on at least one erasure probability (for example, based on a highest erasure probability, an average erasure probability, a successful reception threshold determined based on erasure probabilities of served UEs 115, among other examples) . The quantity of data blocks may be determined in accordance with the erasure probability based threshold as well as in accordance with a quantity of data blocks (N) associated with successful reception of the one or more first data units (in which N>K) . The base station 105-c may then transmit the first set of data blocks to the one or more UEs based at least in part on the determined quantity of data blocks and cease transmitting the first set of data blocks based at least in part on transmitting the determined quantity of data blocks.

Figure 8 shows a block diagram of a device 805 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 805 may be an example of aspects of a UE 115 as described herein. The device 805 may include a receiver 810, a communications manager 815, and a transmitter 820. The communications manager 815 can be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses) .

The receiver 810 may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to fountain-code-based broadcast channel operation with limited feedback) . Information may be passed on to other components of the device 805. The receiver 810 may be an example of aspects of the transceiver 1120 described with reference to Figure 11. The receiver 810 may utilize a single antenna or a set of antennas.

The communications manager 815 may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels, decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units, and transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units. The communications manager 815 may be an example of aspects of the communications manager 1110 described herein.

The communications manager 815, or its sub-components, may be implemented in hardware, code (for example, software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 815, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The communications manager 815, or its sub-components, may be physically located at different locations, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the communications manager 815, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 815, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 820 may transmit signals generated by other components of the device 805. In some examples, the transmitter 820 may be collocated with a receiver 810 in a transceiver component. For example, the transmitter 820 may be an example of aspects of the transceiver 1120 described with reference to Figure 11. The transmitter 820 may utilize a single antenna or a set of antennas.

Figure 9 shows a block diagram of a device 905 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 905 may be an example of aspects of a device 805, or a UE 115 as described herein. The device 905 may include a receiver 910, a communications manager 915, and a transmitter 935. The communications manager 915 can be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses) .

The receiver 910 may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to fountain-code-based broadcast channel operation with limited feedback) . Information may be passed on to other components of the device 905. The receiver 910 may be an example of aspects of the transceiver 1120 described with reference to Figure 11. The receiver 910 may utilize a single antenna or a set of antennas.

The communications manager 915 may be an example of aspects of the communications manager 815 as described herein. The communications manager 915 may include a data block manager 920, a decoder 925, and an UE feedback manager 930. The communications manager 915 may be an example of aspects of the communications manager 1110 described herein.

The data block manager 920 may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels. The decoder 925 may decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units. The UE feedback manager 930 may transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units.

The transmitter 935 may transmit signals generated by other components of the device 905. In some examples, the transmitter 935 may be collocated with a receiver 910 in a transceiver component. For example, the transmitter 935 may be an example of aspects of the transceiver 1120 described with reference to Figure 11. The transmitter 935 may utilize a single antenna or a set of antennas.

Figure 10 shows a block diagram of a communications manager 1005 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The communications manager 1005 may be an example of aspects of a communications manager 815, a communications manager 915, or a communications manager 1110 described herein. The communications manager 1005 may include a data block manager 1010, a decoder 1015, an UE feedback manager 1020, a data unit manager 1025, and an erasure probability manager 1030. Each of these components may communicate, directly or indirectly, with one another (for example, via one or more buses) .

The data block manager 1010 may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels. In some examples, the data block manager 1010 may receive one or more data blocks of a second set of data blocks from the base station via the one or more broadcast channels based on the one or more transmitted acknowledgement feedback messages. In some examples, at least a subset of the one or more data blocks of the first set of data blocks and at least a subset of the one or more data blocks of the second set of data blocks are received in an interleaved pattern.

The decoder 1015 may decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units. In some examples, the decoder 1015 may decode the one or more data blocks of the second set of data blocks.

The UE feedback manager 1020 may transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units. In some examples, the UE feedback manager 1020 may transmit a negative acknowledgement to the base station in response to receiving one or more data blocks of the first set of data blocks, the negative acknowledgment indicating that the UE successfully received the one or more first data units. In some examples, the UE feedback manager 1020 may transmit a positive acknowledgement to the base station in response to a received one or more data blocks of a second set of data blocks, the positive acknowledgment indicating that the UE successfully received the one or more second data units. In some examples, the one or more acknowledgement feedback messages are transmitted to the base station via a feedback channel.

The data unit manager 1025 may determine one or more second data units based on the decoding the subset of the second set of data blocks. In some examples, the data unit manager 1025 may determine the one or more first data units based on the decoding, in which the one or more acknowledgement feedback messages are transmitted to the base station based on the determined one or more first data units. In some examples, the data unit manager 1025 may determine that a quantity of the received one or more data blocks satisfies a threshold for determining the one or more first data units.

The erasure probability manager 1030 may determine an erasure probability based on a quantity of data blocks received from the base station, a data block identification of a data block received from the base station, one or more channel measurements, or any combination thereof. In some examples, the erasure probability manager 1030 may transmit an indication of the determined erasure probability to the base station. In some examples, receiving the one or more data blocks of the first set of data blocks includes receiving the one or more data blocks of the first set of data blocks based on the determined erasure probability.

Figure 11 shows a diagram of a system including a device 1105 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 1105 may be an example of or include the components of device 805, device 905, or a UE 115 as described herein. The device 1105 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 1110, an I/O controller 1115, a transceiver 1120, an antenna 1125, memory 1130, and a processor 1140. These components may be in electronic communication via one or more buses (for example, bus 1145) .

The communications manager 1110 may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels, decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units, and transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units.

The I/O controller 1115 may manage input and output signals for the device 1105. The I/O controller 1115 may also manage peripherals not integrated into the device 1105. In some examples, the I/O controller 1115 may represent a physical connection or port to an external peripheral. In some examples, the I/O controller 1115 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 1115 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some examples, the I/O controller 1115 may be implemented as part of a processor. In some examples, a user may interact with the device 1105 via the I/O controller 1115 or via hardware components controlled by the I/O controller 1115.

The transceiver 1120 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1120 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1120 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some examples, the wireless device may include a single antenna 1125. However, in some examples the device may have more than one antenna 1125, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1130 may include RAM and ROM. The memory 1130 may store computer-readable, computer-executable code or software 1135 including instructions that, when executed, cause the processor to perform various functions described herein. In some examples, the memory 1130 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1140 may include an intelligent hardware device, (for example, a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some examples, the processor 1140 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 1140. The processor 1140 may be configured to execute computer-readable instructions stored in a memory (for example, the memory 1130) to cause the device 1105 to perform various functions (for example, functions or tasks supporting fountain-code-based broadcast channel operation with limited feedback) .

The software 1135 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The software 1135 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some examples, the software 1135 may not be directly executable by the processor 1140 but may cause a computer (for example, when compiled and executed) to perform functions described herein.

Figure 12 shows a block diagram of a device 1205 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 1205 may be an example of aspects of a base station 105 as described herein. The device 1205 may include a receiver 1210, a communications manager 1215, and a transmitter 1220. The communications manager 1215 can be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses) .

The receiver 1210 may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to fountain-code-based broadcast channel operation with limited feedback) . Information may be passed on to other components of the device 1205. The receiver 1210 may be an example of aspects of the transceiver 1520 described with reference to Figure 15. The receiver 1210 may utilize a single antenna or a set of antennas.

The communications manager 1215 may encode one or more first data units into a first set of data blocks using one or more fountain codes, transmit the first set of data blocks to one or more UEs via one or more broadcast channels, cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages, and receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks.

The communications manager 1215 may also determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels, encode one or more first data units into a first set of data blocks using one or more fountain codes, transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based on at least one erasure probability of the determined erasure probabilities for the one or more UEs, and cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based on transmitting a quantity of the first set of data blocks.

The communications manager 1215 may be an example of aspects of the communications manager 1510 described herein. The communications manager 1215, or its sub-components, may be implemented in hardware, code (for example, software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 1215, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The communications manager 1215, or its sub-components, may be physically located at different locations, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the communications manager 1215, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 1215, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 1220 may transmit signals generated by other components of the device 1205. In some examples, the transmitter 1220 may be collocated with a receiver 1210 in a transceiver component. For example, the transmitter 1220 may be an example of aspects of the transceiver 1520 described with reference to Figure 15. The transmitter 1220 may utilize a single antenna or a set of antennas.

Figure 13 shows a block diagram of a device 1305 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 1305 may be an example of aspects of a device 1205, or a base station 105 as described herein. The device 1305 may include a receiver 1310, a communications manager 1315, and a transmitter 1340. The communications manager 1315 can be implemented, at least in part, by one or both of a modem and a processor. Each of these components may be in communication with one another (for example, via one or more buses) .

The receiver 1310 may receive information such as packets, user data, or control information associated with various information channels (for example, control channels, data channels, and information related to fountain-code-based broadcast channel operation with limited feedback) . Information may be passed on to other components of the device 1305. The receiver 1310 may be an example of aspects of the transceiver 1520 described with reference to Figure 15. The receiver 1310 may utilize a single antenna or a set of antennas.

The communications manager 1315 may be an example of aspects of the communications manager 1215 as described herein. The communications manager 1315 may include an encoder 1320, a data block manager 1325, an UE feedback manager 1330, and an erasure probability manager 1335. The communications manager 1315 may be an example of aspects of the communications manager 1510 described herein.

The encoder 1320 may encode one or more first data units into a first set of data blocks using one or more fountain codes. The data block manager 1325 may transmit the first set of data blocks to one or more UEs via one or more broadcast channels. The UE feedback manager 1330 may receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks. The data block manager 1325 may cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages.

The erasure probability manager 1335 may determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels. The encoder 1320 may encode one or more first data units into a first set of data blocks using one or more fountain codes. The data block manager 1325 may transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based on at least one erasure probability of the determined erasure probabilities for the one or more UEs. The data block manager 1325 may cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based on transmitting a quantity of the first set of data blocks.

The transmitter 1340 may transmit signals generated by other components of the device 1305. In some examples, the transmitter 1340 may be collocated with a receiver 1310 in a transceiver component. For example, the transmitter 1340 may be an example of aspects of the transceiver 1520 described with reference to Figure 15. The transmitter 1340 may utilize a single antenna or a set of antennas.

Figure 14 shows a block diagram of a communications manager 1405 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The communications manager 1405 may be an example of aspects of a communications manager 1215, a communications manager 1315, or a communications manager 1510 described herein. The communications manager 1405 may include an encoder 1410, a data block manager 1415, an UE feedback manager 1420, a data unit transition threshold manager 1425, a data unit stop threshold manager 1430, and an erasure probability manager 1435. Each of these components may communicate, directly or indirectly, with one another (for example, via one or more buses) .

The encoder 1410 may encode one or more first data units into a first set of data blocks using one or more fountain codes. In some examples, the encoder 1410 may encode one or more first data units into a first set of data blocks using one or more fountain codes. In some examples, the encoder 1410 may encode one or more second data units into a second set of data blocks using the one or more fountain codes. In some examples, the encoder 1410 may determine a set of source symbols for the one or more first data units. In some examples, generating one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, in which the one or more intermediate symbols includes at least one redundant intermediate symbol.

In some examples, the encoder 1410 may generate a set of encoded symbols based on the one or more intermediate symbols. In some examples, the encoder 1410 may determine a set of source symbols for the one or more first data units. In some examples, generating one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, in which the one or more intermediate symbols includes at least one redundant intermediate symbol. In some examples, the encoder 1410 may generate a set of encoded symbols based on of the one or more intermediate symbols.

The data block manager 1415 may transmit the first set of data blocks to one or more UEs via one or more broadcast channels. In some examples, the data block manager 1415 may cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages. In some examples, the data block manager 1415 may transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based on at least one erasure probability of the determined erasure probabilities for the one or more UEs. In some examples, the data block manager 1415 may cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based on transmitting a quantity of the first set of data blocks.

In some examples, the data block manager 1415 may transmit the second set of data blocks to the one or more UEs via the one or more broadcast channels based on the received one or more acknowledgement feedback messages. In some examples, transmitting the first set of data blocks and the second set of data blocks includes transmitting at least a subset of the first set of data blocks and at least a subset of the second set of data blocks in an interleaved pattern. In some examples, the data block manager 1415 may continue transmitting the first set of data blocks to the one or more UEs based on the first quantity being less than the threshold.

In some examples, the data block manager 1415 may determine a first quantity of data blocks based on the highest erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the highest erasure probability, in which transmitting the first set of data blocks to the one or more UEs is based on the first quantity of data blocks. In some examples, the data block manager 1415 may determine a first quantity of data blocks based on the average erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the average erasure probability, in which transmitting the first set of data blocks to the one or more UEs is based on the first quantity of data blocks.

In some examples, the data block manager 1415 may transmit the first set of data blocks to the one or more UEs based on the determined first quantity of data blocks. In some examples, the data block manager 1415 may cease transmitting the first set of data blocks based on transmitting the determined first quantity of data blocks. In some examples, the data block manager 1415 may transmit the first set of data blocks to a second set of one or more UEs via the one or more broadcast channels based on the at least one erasure probability of the determined erasure probabilities for the one or more UEs. In some examples, the second quantity of data blocks associated with successful reception of the one or more first data units by the first UE is based on a quantity of source symbols associated with the one or more first data units.

The UE feedback manager 1420 may receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks. In some examples, the UE feedback manager 1420 may determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, in which ceasing transmitting the first set of data blocks is based on the first quantity satisfying the threshold. In some examples, the UE feedback manager 1420 may receive one or more second acknowledgement feedback messages from the one or more UEs. In some examples, the UE feedback manager 1420 may receive a negative acknowledgement from a first UE of the one or more UEs, the negative acknowledgment indicating that the first UE received the one or more first data units.

In some examples, the UE feedback manager 1420 may receive a positive acknowledgement from a first UE of the one or more UEs, the positive acknowledgment indicating that the first UE received the one or more second data units. In some examples, the UE feedback manager 1420 may monitor a feedback channel for the one or more acknowledgement feedback messages based on transmitting the first set of data blocks to the one or more UEs.

The erasure probability manager 1435 may determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels. In some examples, the erasure probability manager 1435 may determine a highest erasure probability of the determined erasure probabilities for the one or more UEs, in which transmitting the first set of data blocks to the one or more UEs is based on the determined highest erasure probability. In some examples, the erasure probability manager 1435 may determine an average erasure probability based on the determined erasure probabilities for the one or more UEs, in which transmitting the first set of data blocks to the one or more UEs is based on the determined average erasure probability.

In some examples, the erasure probability manager 1435 may determine a first quantity of data blocks based on the at least one erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the at least one erasure probability. In some examples, the erasure probability manager 1435 may receive an indication of a first erasure probability from a first UE of the one or more UEs, in which determining the first erasure probability for the first UE is based on the received indication.

The data unit transition threshold manager 1425 may determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, in which the second set of data blocks is transmitted to the one or more UEs based on the received one or more acknowledgement feedback messages satisfying the threshold. In some examples, the data unit transition threshold manager 1425 may determine that a first quantity of the received one or more acknowledgement feedback messages is less than a threshold.

The data unit stop threshold manager 1430 may determine that a second quantity including the one or more acknowledgement feedback messages and the one or more second acknowledgement feedback messages satisfies a second threshold, in which ceasing transmitting the first set of data blocks is based on the second quantity satisfying the second threshold.

Figure 15 shows a diagram of a system including a device 1505 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The device 1505 may be an example of or include the components of device 1205, device 1305, or a base station 105 as described herein. The device 1505 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 1510, a network communications manager 1515, a transceiver 1520, an antenna 1525, memory 1530, a processor 1540, and an inter-station communications manager 1545. These components may be in electronic communication via one or more buses (for example, bus 1550) .

The communications manager 1510 may encode one or more first data units into a first set of data blocks using one or more fountain codes, transmit the first set of data blocks to one or more UEs via one or more broadcast channels, cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages, and receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks. The communications manager 1510 may also determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels, encode one or more first data units into a first set of data blocks using one or more fountain codes, transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based on at least one erasure probability of the determined erasure probabilities for the one or more UEs, and cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based on transmitting a quantity of the first set of data blocks.

The network communications manager 1515 may manage communications with the core network (for example, via one or more wired backhaul links) . For example, the network communications manager 1515 may manage the transfer of data communications for client devices, such as one or more UEs 115.

The transceiver 1520 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1520 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1520 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some examples, the wireless device may include a single antenna 1525. However, in some examples the device may have more than one antenna 1525, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1530 may include RAM, ROM, or a combination thereof. The memory 1530 may store computer-readable code or software 1535 including instructions that, when executed by a processor (for example, the processor 1540) cause the device to perform various functions described herein. In some examples, the memory 1530 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1540 may include an intelligent hardware device, (for example, a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some examples, the processor 1540 may be configured to operate a memory array using a memory controller. In some examples, a memory controller may be integrated into processor 1540. The processor 1540 may be configured to execute computer-readable instructions stored in a memory (for example, the memory 1530) to cause the device 1505 to perform various functions (for example, functions or tasks supporting fountain-code-based broadcast channel operation with limited feedback) .

The inter-station communications manager 1545 may manage communications with other base station 105, and may include a controller or scheduler for controlling communications with UEs 115 in cooperation with other base stations 105. For example, the inter-station communications manager 1545 may coordinate scheduling for transmissions to UEs 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communications manager 1545 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

The software 1535 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The software 1535 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some examples, the software 1535 may not be directly executable by the processor 1540 but may cause a computer (for example, when compiled and executed) to perform functions described herein.

Figure 16 shows a flowchart illustrating a method 1600 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 1600 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1600 may be performed by a communications manager as described with reference to Figures 12–15. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 1605, the base station may encode one or more first data units into a first set of data blocks using one or more fountain codes. The operations of 1605 may be performed according to the methods described herein. In some examples, aspects of the operations of 1605 may be performed by an encoder as described with reference to Figures 12–15.

At 1610, the base station may transmit the first set of data blocks to one or more UEs via one or more broadcast channels. The operations of 1610 may be performed according to the methods described herein. In some examples, aspects of the operations of 1610 may be performed by a data block manager as described with reference to Figures 12–15.

At 1615, the base station may receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks. The operations of 1615 may be performed according to the methods described herein. In some examples, aspects of the operations of 1615 may be performed by an UE feedback manager as described with reference to Figures 12–15.

At 1620, the base station may cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages. The operations of 1620 may be performed according to the methods described herein. In some examples, aspects of the operations of 1620 may be performed by a data block manager as described with reference to Figures 12–15.

Figure 17 shows a flowchart illustrating a method 1700 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 1700 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1700 may be performed by a communications manager as described with reference to Figures 12–15. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 1705, the base station may encode one or more first data units into a first set of data blocks using one or more fountain codes. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be performed by an encoder as described with reference to Figures 12–15.

At 1710, the base station may transmit the first set of data blocks to one or more UEs via one or more broadcast channels. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed by a data block manager as described with reference to Figures 12–15.

At 1715, the base station may receive one or more acknowledgement feedback messages from the one or more UEs based on the first set of data blocks. The operations of 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed by an UE feedback manager as described with reference to Figures 12–15.

At 1720, the base station may determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold. The operations of 1720 may be performed according to the methods described herein. In some examples, aspects of the operations of 1720 may be performed by an UE feedback manager as described with reference to Figures 12–15.

At 1725, the base station may cease transmitting the first set of data blocks based on the received one or more acknowledgement feedback messages satisfying the threshold. The operations of 1725 may be performed according to the methods described herein. In some examples, aspects of the operations of 1725 may be performed by a data block manager as described with reference to Figures 12–15.

At 1730, the base station may encode one or more second data units into a second set of data blocks using the one or more fountain codes (for example, based on the one or more acknowledgement feedback messages associated with the first data unit satisfying the threshold) . The operations of 1730 may be performed according to the methods described herein. In some examples, aspects of the operations of 1730 may be performed by an encoder as described with reference to Figures 12–15.

At 1735, the base station may transmit the second set of data blocks to the one or more UEs via the one or more broadcast channels based on the received one or more acknowledgement feedback messages (for example, based on the one or more acknowledgement feedback messages associated with the first data unit satisfying the threshold) . The operations of 1735 may be performed according to the methods described herein. In some examples, aspects of the operations of 1735 may be performed by a data block manager as described with reference to Figures 12–15.

Figure 18 shows a flowchart illustrating a method 1800 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 1800 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1800 may be performed by a communications manager as described with reference to Figures 12–15. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 1805, the base station may determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels. The operations of 1805 may be performed according to the methods described herein. In some examples, aspects of the operations of 1805 may be performed by an erasure probability manager as described with reference to Figures 12–15.

At 1810, the base station may encode one or more first data units into a first set of data blocks using one or more fountain codes. The operations of 1810 may be performed according to the methods described herein. In some examples, aspects of the operations of 1810 may be performed by an encoder as described with reference to Figures 12–15.

At 1815, the base station may transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based on at least one erasure probability of the determined erasure probabilities for the one or more UEs. The operations of 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed by a data block manager as described with reference to Figures 12–15.

At 1820, the base station may cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based on transmitting a quantity of the first set of data blocks. The operations of 1820 may be performed according to the methods described herein. In some examples, aspects of the operations of 1820 may be performed by a data block manager as described with reference to Figures 12–15.

Figure 19 shows a flowchart illustrating a method 1900 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 1900 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1900 may be performed by a communications manager as described with reference to Figures 12–15. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 1905, the base station may determine a respective erasure probability for each of one or more UEs associated with one or more broadcast channels. The operations of 1905 may be performed according to the methods described herein. In some examples, aspects of the operations of 1905 may be performed by an erasure probability manager as described with reference to Figures 12–15.

At 1910, the base station may encode one or more first data units into a first set of data blocks using one or more fountain codes. The operations of 1910 may be performed according to the methods described herein. In some examples, aspects of the operations of 1910 may be performed by an encoder as described with reference to Figures 12–15.

At 1915, the base station may determine a first quantity of data blocks based on the at least one erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the at least one erasure probability. The operations of 1915 may be performed according to the methods described herein. In some examples, aspects of the operations of 1915 may be performed by an erasure probability manager as described with reference to Figures 12–15.

At 1920, the base station may transmit the first set of data blocks to the one or more UEs based on the determined first quantity of data blocks. The operations of 1920 may be performed according to the methods described herein. In some examples, aspects of the operations of 1920 may be performed by a data block manager as described with reference to Figures 12–15.

At 1925, the base station may cease transmitting the first set of data blocks based on transmitting the determined first quantity of data blocks. The operations of 1925 may be performed according to the methods described herein. In some examples, aspects of the operations of 1925 may be performed by a data block manager as described with reference to Figures 12–15.

Figure 20 shows a flowchart illustrating a method 2000 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 2000 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 2000 may be performed by a communications manager as described with reference to Figures 8–11. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 2005, the UE may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels. The operations of 2005 may be performed according to the methods described herein. In some examples, aspects of the operations of 2005 may be performed by a data block manager as described with reference to Figures 8–11.

At 2010, the UE may decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units. The operations of 2010 may be performed according to the methods described herein. In some examples, aspects of the operations of 2010 may be performed by a decoder as described with reference to Figures 8–11.

At 2015, the UE may transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units. The operations of 2015 may be performed according to the methods described herein. In some examples, aspects of the operations of 2015 may be performed by an UE feedback manager as described with reference to Figures 8–11.

Figure 21 shows a flowchart illustrating a method 2100 that supports fountain-code-based broadcast channel operation with limited feedback in accordance with aspects of the present disclosure. The operations of method 2100 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 2100 may be performed by a communications manager as described with reference to Figures 8–11. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 2105, the UE may receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels. The operations of 2105 may be performed according to the methods described herein. In some examples, aspects of the operations of 2105 may be performed by a data block manager as described with reference to Figures 8–11.

At 2110, the UE may decode the one or more data blocks of the first set of data blocks based on one or more fountain codes, the one or more data blocks including one or more first data units. The operations of 2110 may be performed according to the methods described herein. In some examples, aspects of the operations of 2110 may be performed by a decoder as described with reference to Figures 8–11.

At 2115, the UE may transmit one or more acknowledgement feedback messages to the base station based on successfully decoding the one or more first data units. The operations of 2115 may be performed according to the methods described herein. In some examples, aspects of the operations of 2115 may be performed by an UE feedback manager as described with reference to Figures 8–11.

At 2120, the UE may receive one or more data blocks of a second set of data blocks from the base station via the one or more broadcast channels based on the one or more transmitted acknowledgement feedback messages. For example, the UE may transmit an acknowledgment feedback message corresponding to the first data unit, and the UE may expect the base station to transmit the second set of data units corresponding to a second data unit based on the transmitted acknowledgement feedback message. The operations of 2120 may be performed according to the methods described herein. In some examples, aspects of the operations of 2120 may be performed by a data block manager as described with reference to Figures 8–11.

At 2125, the UE may decode the one or more data blocks of the second set of data blocks. The operations of 2125 may be performed according to the methods described herein. In some examples, aspects of the operations of 2125 may be performed by a decoder as described with reference to Figures 8–11.

It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

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

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM) , read-only memory (ROM) , electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc in which disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, 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 (A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communication at a base station, comprising:

encoding one or more first data units into a first set of data blocks using one or more fountain codes;

transmitting the first set of data blocks to one or more user equipment (UEs) via one or more broadcast channels;

receiving one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks; and

ceasing transmitting the first set of data blocks based at least in part on the received one or more acknowledgement feedback messages.
The method of claim 1, further comprising determining that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, wherein ceasing transmitting the first set of data blocks is based at least in part on the first quantity satisfying the threshold.
The method of any one of claims 1 or 2, further comprising:

encoding one or more second data units into a second set of data blocks using the one or more fountain codes; and

transmitting the second set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on the received one or more acknowledgement feedback messages.
The method of claim 3, further comprising determining that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, wherein the second set of data blocks is transmitted to the one or more UEs based at least in part on the received one or more acknowledgement feedback messages satisfying the threshold.
The method of any one of claims 1–4, further comprising:

receiving one or more second acknowledgement feedback messages from the one or more UEs; and

determining that a second quantity comprising the one or more acknowledgement feedback messages and the one or more second acknowledgement feedback messages satisfies a second threshold, wherein ceasing transmitting the first set of data blocks is based at least in part on the second quantity satisfying the second threshold.
The method of any one of claims 3–5, wherein transmitting the first set of data blocks and the second set of data blocks comprises transmitting at least a subset of the first set of data blocks and at least a subset of the second set of data blocks in an interleaved pattern.
The method of claim 6, wherein receiving the one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks comprises receiving a negative acknowledgement from a first UE of the one or more UEs, the negative acknowledgment indicating that the first UE received the one or more first data units.
The method of any one of claims 6 or 7, further comprising receiving a positive acknowledgement from a first UE of the one or more UEs, the positive acknowledgment indicating that the first UE received the one or more second data units.
The method of any one of claims 1–8, wherein transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels comprises:

determining that a first quantity of the received one or more acknowledgement feedback messages is less than a threshold; and

continuing transmitting the first set of data blocks to the one or more UEs based at least in part on the first quantity being less than the threshold.
The method of any one of claims 1–9, further comprising monitoring a feedback channel for the one or more acknowledgement feedback messages based at least in part on transmitting the first set of data blocks to the one or more UEs.
The method of any one of claims 1–10, wherein encoding the one or more first data units into the first set of data blocks using the one or more fountain codes comprises:

determining a set of source symbols for the one or more first data units;

generating one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, wherein the one or more intermediate symbols comprises at least one redundant intermediate symbol; and

generating a set of encoded symbols based at least in part on the one or more intermediate symbols.
A method for wireless communication at a base station, comprising:

determining a respective erasure probability for each of one or more user equipment (UEs) associated with one or more broadcast channels;

encoding one or more first data units into a first set of data blocks using one or more fountain codes;

transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on at least one erasure probability of the determined erasure probabilities for the one or more UEs; and

ceasing transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on transmitting a quantity of the first set of data blocks.
The method of claim 12, further comprising determining a highest erasure probability of the determined erasure probabilities for the one or more UEs, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the determined highest erasure probability.
The method of any one of claims 12 or 13, further comprising determining a first quantity of data blocks based at least in part on the highest erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the highest erasure probability, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the first quantity of data blocks.
The method of claim 14, wherein the second quantity of data blocks associated with successful reception of the one or more first data units by the first UE is based at least in part on a quantity of source symbols associated with the one or more first data units.
The method of any one of claims 12–15, further comprising determining an average erasure probability based at least in part on the determined erasure probabilities for the one or more UEs, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the determined average erasure probability.
The method of claim 16, further comprising determining a first quantity of data blocks based at least in part on the average erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the average erasure probability, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the first quantity of data blocks.
The method of claim 17, wherein the second quantity of data blocks associated with successful reception of the one or more first data units by the first UE is based at least in part on a quantity of source symbols associated with the one or more first data units.
The method of any one of claims 12–18, wherein transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on the at least one erasure probability comprises:

determining a first quantity of data blocks based at least in part on the at least one erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the at least one erasure probability;

transmitting the first set of data blocks to the one or more UEs based at least in part on the determined first quantity of data blocks; and

ceasing transmitting the first set of data blocks based at least in part on transmitting the determined first quantity of data blocks.
The method of any one of claims 12–19, further comprising receiving an indication of a first erasure probability from a first UE of the one or more UEs, wherein determining the first erasure probability for the first UE is based at least in part on the received indication.
The method of any one of claims 12–20, wherein encoding the one or more first data units into the first set of data blocks using the one or more fountain codes comprises:

determining a set of source symbols for the one or more first data units;

generating one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, wherein the one or more intermediate symbols comprises at least one redundant intermediate symbol; and

generating a set of encoded symbols based at least in part on of the one or more intermediate symbols.
The method of any one of claims 12–21, further comprising transmitting the first set of data blocks to a second set of one or more UEs via the one or more broadcast channels based at least in part on the at least one erasure probability of the determined erasure probabilities for the one or more UEs.
A method for wireless communication at a user equipment (UE) , comprising:

receiving one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels;

decoding the one or more data blocks of the first set of data blocks based at least in part on one or more fountain codes, the one or more data blocks comprising one or more first data units; and

transmitting one or more acknowledgement feedback messages to the base station based at least in part on successfully decoding the one or more first data units.
The method of claim 23, further comprising:

receiving one or more data blocks of a second set of data blocks from the base station via the one or more broadcast channels based at least in part on the one or more transmitted acknowledgement feedback messages; and

decoding the one or more data blocks of the second set of data blocks.
The method of claim 24, wherein at least a subset of the one or more data blocks of the first set of data blocks and at least a subset of the one or more data blocks of the second set of data blocks are received in an interleaved pattern.
The method of claim 25, further comprising determining one or more second data units based at least in part on the decoding the subset of the second set of data blocks.
The method of any one of claims 23–26, wherein transmitting the one or more acknowledgement feedback messages to the base station comprises transmitting a negative acknowledgement to the base station in response to receiving one or more data blocks of the first set of data blocks, the negative acknowledgment indicating that the UE successfully received the one or more first data units.
The method of any one of claims 23–27, wherein transmitting the one or more acknowledgement feedback messages to the base station comprises transmitting a positive acknowledgement to the base station in response to a received one or more data blocks of a second set of data blocks, the positive acknowledgment indicating that the UE successfully received the one or more second data units.
The method of any one of claims 23–28, wherein the one or more acknowledgement feedback messages are transmitted to the base station via a feedback channel.
The method of any one of claims 23–29, further comprising:

determining an erasure probability based at least in part on one or more of a quantity of data blocks received from the base station, a data block identification of a data block received from the base station, or one or more channel measurements; and

transmitting an indication of the determined erasure probability to the base station.
The method of claim 30, wherein receiving the one or more data blocks of the first set of data blocks comprises receiving the one or more data blocks of the first set of data blocks based at least in part on the determined erasure probability.
The method of any one of claims 23–31, further comprising determining the one or more first data units based at least in part on the decoding, wherein the one or more acknowledgement feedback messages are transmitted to the base station based at least in part on the determined one or more first data units.
The method of claim 32, wherein determining the one or more first data units based at least in part on the decoding comprises determining that a quantity of the received one or more data blocks satisfies a threshold for determining the one or more first data units.
An apparatus for wireless communication at a base station, comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

encode one or more first data units into a first set of data blocks using one or more fountain codes;

transmit the first set of data blocks to one or more user equipment (UEs) via one or more broadcast channels;

receive one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks; and

cease transmitting the first set of data blocks based at least in part on the received one or more acknowledgement feedback messages.
The apparatus of claim 34, wherein the instructions are further executable by the processor to cause the apparatus to determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, wherein ceasing transmitting the first set of data blocks is based at least in part on the first quantity satisfying the threshold.
The apparatus of claim 34, wherein the instructions are further executable by the processor to cause the apparatus to:

encode one or more second data units into a second set of data blocks using the one or more fountain codes; and

transmit the second set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on the received one or more acknowledgement feedback messages.
The apparatus of claim 36, wherein the instructions are further executable by the processor to cause the apparatus to determine that a first quantity of the one or more acknowledgement feedback messages satisfies a threshold, wherein the second set of data blocks is transmitted to the one or more UEs based at least in part on the received one or more acknowledgement feedback messages satisfying the threshold.
The apparatus of claim 37, wherein the instructions are further executable by the processor to cause the apparatus to:

receive one or more second acknowledgement feedback messages from the one or more UEs; and

determine that a second quantity comprising the one or more acknowledgement feedback messages and the one or more second acknowledgement feedback messages satisfies a second threshold, wherein ceasing transmitting the first set of data blocks is based at least in part on the second quantity satisfying the second threshold.
The apparatus of claim 36, wherein the instructions to transmit the first set of data blocks and the second set of data blocks are executable by the processor to cause the apparatus to transmit at least a subset of the first set of data blocks and at least a subset of the second set of data blocks in an interleaved pattern.
The apparatus of claim 39, wherein the instructions to receive the one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks are executable by the processor to cause the apparatus to:

receive a negative acknowledgement from a first UE of the one or more UEs, the negative acknowledgment indicating that the first UE received the one or more first data units.
The apparatus of claim 39, wherein the instructions are further executable by the processor to cause the apparatus to receive a positive acknowledgement from a first UE of the one or more UEs, the positive acknowledgment indicating that the first UE received the one or more second data units.
The apparatus of claim 34, wherein the instructions to transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels are executable by the processor to cause the apparatus to:

determine that a first quantity of the received one or more acknowledgement feedback messages is less than a threshold; and

continue transmitting the first set of data blocks to the one or more UEs based at least in part on the first quantity being less than the threshold.
The apparatus of claim 34, wherein the instructions are further executable by the processor to cause the apparatus to monitor a feedback channel for the one or more acknowledgement feedback messages based at least in part on transmitting the first set of data blocks to the one or more UEs.
The apparatus of claim 34, wherein the instructions to encode the one or more first data units into the first set of data blocks using the one or more fountain codes are executable by the processor to cause the apparatus to:

determine a set of source symbols for the one or more first data units;

generate one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, wherein the one or more intermediate symbols comprises at least one redundant intermediate symbol; and

generate a set of encoded symbols based at least in part on the one or more intermediate symbols.
An apparatus for wireless communication at a base station, comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

determine a respective erasure probability for each of one or more user equipment (UEs) associated with one or more broadcast channels;

encode one or more first data units into a first set of data blocks using one or more fountain codes;

transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on at least one erasure probability of the determined erasure probabilities for the one or more UEs; and

cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on transmitting a quantity of the first set of data blocks.
The apparatus of claim 45, wherein the instructions are further executable by the processor to cause the apparatus to determine a highest erasure probability of the determined erasure probabilities for the one or more UEs, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the determined highest erasure probability.
The apparatus of claim 46, wherein the instructions are further executable by the processor to cause the apparatus to determine a first quantity of data blocks based at least in part on the highest erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the highest erasure probability, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the first quantity of data blocks.
The apparatus of claim 47, wherein the second quantity of data blocks associated with successful reception of the one or more first data units by the first UE is based at least in part on a quantity of source symbols associated with the one or more first data units.
The apparatus of claim 45, wherein the instructions are further executable by the processor to cause the apparatus to determine an average erasure probability based at least in part on the determined erasure probabilities for the one or more UEs, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the determined average erasure probability.
The apparatus of claim 49, wherein the instructions are further executable by the processor to cause the apparatus to determine a first quantity of data blocks based at least in part on the average erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the average erasure probability, wherein transmitting the first set of data blocks to the one or more UEs is based at least in part on the first quantity of data blocks.
The apparatus of claim 50, wherein the second quantity of data blocks associated with successful reception of the one or more first data units by the first UE is based at least in part on a quantity of source symbols associated with the one or more first data units.
The apparatus of claim 45, wherein the instructions to transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on the at least one erasure probability are executable by the processor to cause the apparatus to:

determine a first quantity of data blocks based at least in part on the at least one erasure probability and a second quantity of data blocks associated with successful reception of the one or more first data units by a first UE corresponding to the at least one erasure probability;

transmit the first set of data blocks to the one or more UEs based at least in part on the determined first quantity of data blocks; and

cease transmitting the first set of data blocks based at least in part on transmitting the determined first quantity of data blocks.
The apparatus of claim 45, wherein the instructions are further executable by the processor to cause the apparatus to receive an indication of a first erasure probability from a first UE of the one or more UEs, wherein determining the first erasure probability for the first UE is based at least in part on the received indication.
The apparatus of claim 45, wherein the instructions to encode the one or more first data units into the first set of data blocks using the one or more fountain codes are executable by the processor to cause the apparatus to:

determine a set of source symbols for the one or more first data units;

generate one or more intermediate symbols from a first subset of the set of source symbols using at least a first coding scheme, wherein the one or more intermediate symbols comprises at least one redundant intermediate symbol; and

generate a set of encoded symbols based at least in part on of the one or more intermediate symbols.
The apparatus of claim 45, wherein the instructions are further executable by the processor to cause the apparatus to transmit the first set of data blocks to a second set of one or more UEs via the one or more broadcast channels based at least in part on the at least one erasure probability of the determined erasure probabilities for the one or more UEs.
An apparatus for wireless communication at a user equipment (UE) , comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels;

decode the one or more data blocks of the first set of data blocks based at least in part on one or more fountain codes, the one or more data blocks comprising one or more first data units; and

transmit one or more acknowledgement feedback messages to the base station based at least in part on successfully decoding the one or more first data units.
The apparatus of claim 56, wherein the instructions are further executable by the processor to cause the apparatus to:

receive one or more data blocks of a second set of data blocks from the base station via the one or more broadcast channels based at least in part on the one or more transmitted acknowledgement feedback messages; and

decode the one or more data blocks of the second set of data blocks.
The apparatus of claim 57, wherein at least a subset of the one or more data blocks of the first set of data blocks and at least a subset of the one or more data blocks of the second set of data blocks are received in an interleaved pattern.
The apparatus of claim 58, wherein the instructions are further executable by the processor to cause the apparatus to determine one or more second data units based at least in part on the decoding the subset of the second set of data blocks.
The apparatus of claim 56, wherein the instructions to transmit the one or more acknowledgement feedback messages to the base station are executable by the processor to cause the apparatus to transmit a negative acknowledgement to the base station in response to receiving one or more data blocks of the first set of data blocks, the negative acknowledgment indicating that the UE successfully received the one or more first data units.
The apparatus of claim 56, wherein the instructions to transmit the one or more acknowledgement feedback messages to the base station are executable by the processor to cause the apparatus to transmit a positive acknowledgement to the base station in response to a received one or more data blocks of a second set of data blocks, the positive acknowledgment indicating that the UE successfully received the one or more second data units.
The apparatus of claim 56, wherein the one or more acknowledgement feedback messages are transmitted to the base station via a feedback channel.
The apparatus of claim 56, wherein the instructions are further executable by the processor to cause the apparatus to:

determine an erasure probability based at least in part on one or more of a quantity of data blocks received from the base station, a data block identification of a data block received from the base station, or one or more channel measurements; and

transmit an indication of the determined erasure probability to the base station.
The apparatus of claim 63, wherein the instructions to receive the one or more data blocks of the first set of data blocks are executable by the processor to cause the apparatus to receive the one or more data blocks of the first set of data blocks based at least in part on the determined erasure probability.
The apparatus of claim 56, wherein the instructions are further executable by the processor to cause the apparatus to determine the one or more first data units based at least in part on the decoding, wherein the one or more acknowledgement feedback messages are transmitted to the base station based at least in part on the determined one or more first data units.
The apparatus of claim 65, wherein the instructions to determine the one or more first data units based at least in part on the decoding are executable by the processor to cause the apparatus to determine that a quantity of the received one or more data blocks satisfies a threshold for determining the one or more first data units.
An apparatus for wireless communication at a base station, comprising:

means for encoding one or more first data units into a first set of data blocks using one or more fountain codes;

means for transmitting the first set of data blocks to one or more user equipment (UEs) via one or more broadcast channels;

means for receiving one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks; and

means for ceasing transmitting the first set of data blocks based at least in part on the received one or more acknowledgement feedback messages.
An apparatus for wireless communication at a base station, comprising:

means for determining a respective erasure probability for each of one or more user equipment (UEs) associated with one or more broadcast channels;

means for encoding one or more first data units into a first set of data blocks using one or more fountain codes;

means for transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on at least one erasure probability of the determined erasure probabilities for the one or more UEs; and

means for ceasing transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on transmitting a quantity of the first set of data blocks.
An apparatus for wireless communication at a user equipment (UE) , comprising:

means for receiving one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels;

means for decoding the one or more data blocks of the first set of data blocks based at least in part on one or more fountain codes, the one or more data blocks comprising one or more first data units; and

means for transmitting one or more acknowledgement feedback messages to the base station based at least in part on successfully decoding the one or more first data units.
A non-transitory computer-readable medium storing code for wireless communication at a base station, the code comprising instructions executable by a processor to:

encode one or more first data units into a first set of data blocks using one or more fountain codes;

transmit the first set of data blocks to one or more user equipment (UEs) via one or more broadcast channels;

receive one or more acknowledgement feedback messages from the one or more UEs based at least in part on the first set of data blocks; and

cease transmitting the first set of data blocks based at least in part on the received one or more acknowledgement feedback messages.
A non-transitory computer-readable medium storing code for wireless communication at a base station, the code comprising instructions executable by a processor to:

determine a respective erasure probability for each of one or more user equipment (UEs) associated with one or more broadcast channels;

encode one or more first data units into a first set of data blocks using one or more fountain codes;

transmit the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on at least one erasure probability of the determined erasure probabilities for the one or more UEs; and

cease transmitting the first set of data blocks to the one or more UEs via the one or more broadcast channels based at least in part on transmitting a quantity of the first set of data blocks.
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:

receive one or more data blocks of a first set of data blocks from a base station via one or more broadcast channels;

decode the one or more data blocks of the first set of data blocks based at least in part on one or more fountain codes, the one or more data blocks comprising one or more first data units; and

transmit one or more acknowledgement feedback messages to the base station based at least in part on successfully decoding the one or more first data units.