Abstract: Methods, systems, and devices for wireless communication are described. A wireless system utilizing one or more time-division duplexing (TDD) configured carriers may utilize a dual transmission time interval (TTI) structure (e.g., at the subframe level and symbol-level). The symbol level TTIs may be referred to as low latency (LL) TTIs, and may be organized within LL subframes. A LL subframe may be a subframe that is scheduled for transmissions in one direction (e.g., uplink or downlink, according to a TDD configuration) and may include multiple LL symbols scheduled for both uplink (UL) and downlink (DL) transmissions. Guard periods may be scheduled between adjacent LL symbols that have opposite directions of transmission to enable user equipment (UEs) to transition from receiving mode to transmit mode (or vice versa). The LL subframes may be transparent to receiving devices that do not support LL operations.

Abstract: Methods, systems, and devices for wireless communication are described. A receiving device may detect a signal associated with low latency transmissions and decode a non-low latency communication accordingly. The receiving device may receive an indicator from a transmitting device that indicates where and when low latency communications occur. The indication may specify frequency resources or symbols used by the low latency communication. The indicator may be transmitted during the same subframe as the low latency communication, at the end of a subframe, or during a subsequent subframe. The receiving device may use the indicator to mitigate low latency interference, generate channel estimates, and reliably decode the non-low latency communication. In some cases, the interfering low latency communication may occur within the serving cell of the receiving device; or the interfering low latency communication may occur in a neighboring cell.

Abstract: Methods, systems, and devices for wireless communication are described. A base station may select, and a user equipment (UE) may identify, an initial symbol of a transmission time interval (TTI) based on a particular characteristic of a communication link between the base station and UE. A two-symbol TTI for one UE may thus be scheduled to align with or complement a longer TTI for another UE. For instance, the initial symbol of a two-symbol TTI may be restricted to certain symbol periods of a Long Term Evolution (LTE) subframe to limit interference with other transmissions scheduled during the subframe (e.g., reference signals, control channels, guard periods, etc.). Additionally or alternatively, a UE may identify and blindly decode control channel transmissions for low latency communications by assuming a presence of reference signals within the symbols that include a low latency control channel.

Abstract: Certain aspects of the present disclosure provide techniques that may be used for low latency communications. For example, aspects allow a single group acknowledgement to be used to acknowledge a plurality of low latency transmissions. An exemplary method generally includes receiving, from a base station, a plurality of downlink channel transmissions, wherein each of the downlink channel transmissions is sent using a first transmission time interval (TTI) that is reduced relative to a legacy TTI and providing, in a single uplink channel transmission sent using a second TTI that is larger than the first TTI, a group acknowledgement indicating whether or not the downlink channel transmissions were successfully received by a UE.

Abstract: Methods, systems, and apparatuses for wireless communication are described. In some wireless systems (e.g., new radio (NR) systems), a system may employ fixed or variable length uplink burst regions (e.g., in an uplink-centric slot). The base station may semi-statically or dynamically configure a user equipment (UE) or group of UEs for uplink control channel transmissions within an uplink burst region. In semi-static configuration, the UE may determine the uplink control channel transmission based on values transmitted or indicated via higher-layer signaling or based on default values. In dynamic configuration, the UE may receive an indication of actual resources used by the base station in a physical layer message. The UE may transmit using an uplink control channel transmission based on the indication. In some cases, the base station may allocate code division multiplexing (CDM) groups based on which UEs are semi-statically configured and which are dynamically configured.

Abstract: Methods, systems, and devices for wireless communication are described. A wireless device may receive a data transmission during a transmission time interval (TTI) that has one duration, and the device may transmit a responsive control message (e.g., acknowledgment information) in a subsequent TTI that has a different duration (e.g., a greater duration). In some cases, the control message may include bundled acknowledgment information for multiple downlink transmissions. The control message may, for instance, include acknowledgment information for data received during several TTIs having one duration bundled with acknowledgment information for data received during TTIs that have a different duration. The acknowledgment information may be compressed using, for example, a starting point and run length of consecutive negative acknowledgments.

Abstract: Methods, systems, and devices for wireless communication are described. Some wireless communications systems (e.g., New Radio (NR) systems) may support the dynamic configuration of time intervals (or slots) for communication in a specific link direction (e.g., uplink, downlink, sidelink, etc.). In such cases, a base station may dynamically allocate time intervals (or slots) for broadcast or multicast data (e.g., via a physical downlink control channel (PDCCH)) based on the dynamically determined configuration of certain time intervals (or slots). The dynamic allocation of resources for broadcast or multicast data may ensure that broadcast or multicast data is not scheduled to be transmitted during time intervals configured for uplink communication. In some cases, the broadcast or multicast data may be transmitted on a portion of a system bandwidth that is frequency division multiplexed with another portion of the system bandwidth allocated for mobile broadband (MBB) communications.

Abstract: Methods, systems, and devices for wireless communication are described. Wireless communications systems as described herein may be configured to support several service types with different latency, reliability, or throughput rates or standards. One such service type may be referred to as ultra-reliable, low-latency communications (URLLC). Enhancements to improve URLLC performance in coexistence with and as a complement to legacy service types, such as LTE are described. These include, for example, enhanced timing resource allocations, enhanced transmission repetition schemes, enhanced feedback mechanisms, or a combination of these features to achieve certain reliability and latency targets.

Abstract: Methods, systems, and devices for wireless communication are described. Wireless communications systems as described herein may be configured to support several service types with different latency, reliability, or throughput rates or standards. One such service type may be referred to as ultra-reliable, low-latency communications (URLLC). Enhancements to improve URLLC performance in coexistence with and as a complement to legacy service types, such as LTE are described. These include, for example, enhanced timing resource allocations, enhanced transmission repetition schemes, enhanced feedback mechanisms, or a combination of these features to achieve certain reliability and latency targets.

Abstract: Random access techniques may use subcarriers allocated for random access requests in narrowband communication. Physical resources may be selected for transmission of a random access request based on a “coverage class” of a user equipment (UE). In some examples, a set of coverage classes may be identified based on one or more UE channel conditions, such as pathloss. Each coverage class may have one or more associated subcarriers of a set of subcarriers in a narrowband bandwidth, and random access messages may be transmitted using the associated subcarrier(s) for the coverage class of a UE. In some examples, different coverage classes may have different numbers of redundant transmissions of a random access message, which may be based on channel conditions associated with a particular coverage class. A UE, based on a measured channel condition, may determine a coverage class and select a subcarrier based on the determined coverage class.

Abstract: Methods, systems, and devices for wireless communication are described. Wireless communications systems as described herein may be configured to support several service types with different latency, reliability, or throughput rates or standards. One such service type may be referred to as high-reliability, low latency communication (HRLLC). Enhancements to improve HRLLC performance in coexistence with and as a complement to legacy service types, such as LTE are described. These include, for example, downlink and uplink control enhancements, channel state information (CSI) feedback enhancements, physical uplink shared channel (PUSCH) enhancements, and UL power control enhancements to support HRLLC.

Abstract: Various aspects described herein relate to communicating in a wireless network. A resource grant comprising an indicator of whether to transmit a demodulation reference signal (RS) for an uplink control channel or an uplink data channel can be received from a network entity. It can be determined whether to transmit the RS in at least one transmission time interval (TTI) based at least in part on the indicator.

Abstract: Aspects of the present disclosure describe communicating control data based on reference signals in wireless communications. A timeline for transmitting uplink communications can be determined, where the timeline can relate to whether to process downlink communications based on at least one of a first type of reference signal (RS) or a second type of RS, a length or number of symbols in the reference signal, or a timing advance.

Abstract: Methods, systems, and devices for wireless communication are described in which scheduling of time and frequency resources for multiple component carriers (CCs) may be provided in a low latency physical downlink control channel (sPDCCH) transmission to a user equipment (UE). The scheduling information may include a first portion that is transmitted during a first transmission time interval (TTI) and that includes scheduling information (UE-specific or common for multiple UEs) for two or more shortened TTIs (sTTIs) on one or more CCs, and a second portion that may be specific to the particular sTTI on one or more CCs. Rate matching information may be provided to indicate portions of the sPDCCH that may be reallocated for shared channel transmissions. The scheduling information may be, in some cases, provided in a single-level scheduling information transmission for two or more UEs, that provides UE-specific resources on one or more CCs.

Abstract: Various aspects described herein relate to determining a configuration of reference signal (RS) resources in wireless communications. A scheduling grant of resources can be received from an access point, wherein the scheduling grant indicates one or more parameters related to transmission locations of one or more RSs. RS resource locations can be determined for the one or more RSs based at least in part on the one or more parameters. The one or more RSs can be received over the RS resource locations allowing for decimation of the RSs in time and/or frequency.

Abstract: Various aspects described herein relate to allocating resources in wireless communications. A subset of resource block (RB) groups configured for a legacy wireless communication technology having a first transmission time interval (TTI) can be determined, where the first TTI is based on one subframe in duration, and where each RB group in the subset of RB groups includes one or more RBs. A resource allocation for a low latency communication technology having a second TTI, the second TTI being less than one subframe in duration, can be determined where the resource allocation including one or more low latency RBs in the subset of RB groups. Data can be communicated over resources in the one or more low latency RBs, the low latency RBs being based on the second TTI, and the resources being associated with the resource allocation.

Abstract: Various aspects described herein relate to communicating in a wireless network. A transmission time interval (TTI) for an uplink control channel transmission within a subframe is determined, wherein the TTI comprises of a number of symbols which are a subset of a plurality of symbols in the subframe. Uplink control data can be transmitted over the uplink control channel during the TTI.

Abstract: Techniques for low latency point to multipoint (PTM) communications in a system supporting communications using multiple different transmission time interval (TTI) durations are provided. The low latency PTM communications may be supported by one or more physical channels that support PTM communications at shortened TTI durations. In some examples, a base station may allocate, in a PTM traffic channel, a first set of resources for PTM transmissions with a first user equipment (UE) and a second UE, and may allocate a second set of resources (e.g., in a physical downlink shared channel (PDSCH)) for unicast transmissions to the first UE. The PTM transmissions may be transmitted using TTIs configured with durations shorter than TTIs used for transmitting unicast transmissions. Different sets of PTM resources may be allocated for different PTM transmissions having different TTI durations.

Abstract: Methods, systems, and devices for wireless communication are described that support sounding reference signal (SRS) transmission in low latency wireless transmissions. A set of shortened transmission time intervals (sTTIs) for uplink transmissions of a first wireless service may be identified; the set of sTTIs located within subframe time boundaries of a subframe of a second wireless service with a longer TTI than the sTTIs. Two or more sTTIs within the set of sTTIs may be used for SRS transmissions within the subframe time boundaries.

Abstract: Methods, systems, and devices for wireless communication are described that identify an uplink transmission time interval (TTI) length for uplink transmissions, and a downlink TTI length for downlink transmissions, in which the uplink TTI length and the downlink TTI length may be different. The downlink TTI length may be a shortened TTI (sTTI) length, and the uplink TTI length may be longer than the downlink sTTI length. Various parameters for transmissions may be determined based on one or more of the uplink TTI length or the downlink TTI length, such as one or more of a feedback process transmission timing, a timing advance (TA) value, a transport block size (TBS), a number of spatial layers, a number of component carriers (CCs), or a channel quality information (CQI) reporting type may be determined based on one or more of the uplink TTI length or the downlink TTI length.