Abstract:
Methods, systems, and devices for wireless communication are described that provide for reduced timing between certain downlink communications and responsive uplink communications relative to certain legacy systems (e.g., legacy LTE systems). A user equipment (UE) or base station may be capable of operating using two or more timing configurations that each include an associated time period between receipt of a downlink communication (e.g., a grant of uplink resources or shared channel data) and a responsive uplink communication (e.g., an uplink transmission using the granted uplink resources or feedback of successful reception of the shared channel data). In cases where a UE or base station are capable of two or more timing configurations, a timing configuration for a transmission may be determined and the responsive uplink communication transmitted according to the determined timing configuration.
Abstract:
Methods, systems, and devices for wireless communication are described. Data may be received during transmission time intervals (TTIs) that have a short duration relative to other TTIs. The short-duration TTIs may occur within or overlap a longer duration TTI, such as a subframe. Feedback responsive to the data may be generated and assigned for transmission during an uplink TTI according to a feedback timing or delay, which may be selected to reduce latency or balance the payload size of uplink messages sent during the assigned uplink TTI. Data and feedback assignments in short-duration TTIs may be configured based on a time division duplexing (TDD) configuration for some TTIs (e.g., subframes). TTIs that are a Long Term Evolution (LTE) subframe, an LTE slot, and a duration of two LTE symbol periods may be supported. Portions of special TTIs may be used for transmissions according to shorter-duration TTIs.
Abstract:
Various aspects described herein relate to communicating uplink control information (UCI) in low-latency communications. A resource assignment is received from an access point to transmit over a first symbol and a second symbol that comprise a first TTI, wherein the resource assignment includes, at least for the first symbol, an indication of one or more consecutive frequency resources in a system bandwidth based on a decimation factor. A reference signal is transmitted in the first TTI over the first symbol and a data signal indicating UCI over the second symbol according to the resource assignment.
Abstract:
Various aspects described herein relate to managing ultra low latency (ULL) communications over a plurality of component carriers (CC). A configuration for aggregating a set of CCs can be received, wherein the set of CCs includes at least a primary cell and a secondary cell. Based on the received configuration, at least the primary cell can be communicated with for legacy communications, wherein the legacy communications are based on a first transmission time interval (TTI) having a first duration. Based on the received configuration, the primary cell and the secondary cell can be communicated with for ULL communications, wherein the ULL communications are based on a second TTI having a second duration that is less than the first duration.
Abstract:
An example data structure for managing user equipment communications in a wireless communications system is presented, as well as methods and apparatuses configured to implement the data structure. For instance, the data structure may include a downlink subframe comprising two slots and including one or more quick downlink channels having a single-slot transmission time interval. In addition, the example data structure may include one or more resource element blocks each comprising one or more resource elements into which a frequency bandwidth is divided within one or both of the two slots, wherein each of the one or more resource element blocks comprises a control channel region or a data channel region. Furthermore, the example data structure may include one or more resource grants, located within one or more control channel regions, for one or more user equipment served by the one or more quick downlink channels.
Abstract:
Noise and interference may be estimated at a user equipment (UE) in a system that may support transmissions having different transmission time intervals (TTIs). The UE may perform a channel estimation for a first set of transmissions having a first TTI based at least in part on an estimated interference from a second set of transmissions having a second TTI that is shorter than the first TTI. The UE may perform channel estimation for orthogonal frequency division multiplexing (OFDM) symbols of the first set of transmissions. The first set of transmissions may then be demodulated based at least in part on the channel estimation for the first set of transmissions. Noise and interference may also be estimated based on one or more null tones within one or more OFDM symbols of the allocated resources.
Abstract:
Methods, systems, and devices for wireless communication are described. A wireless device may identify an uplink/downlink (UL/DL) configuration that defines subframe configuration options for each subframe of a frame. For example, the UL/DL configuration may establish parameters for time division duplexing (TDD) operation between a base station and a user equipment (UE). The wireless device (e.g., the UE or base station) may determine a constraint for a subframe of the frame based on the UL/DL configuration and then determine an adaptive subframe configuration based on the constraint. The adaptive subframe configuration may include one or several downlink symbol periods and one or several uplink symbol periods. The wireless device may then communicate during the subframe according to the adaptive subframe configuration rather than the original UL/DL configuration; and, because the adaptive subframe may be constrained by the identified UL/DL configuration, the communication during the subframe may avoid disruption to UEs.
Abstract:
Methods, systems, and devices for wireless communication are described. A wireless device may identify multiple regions within a subframe, such as one or more uplink regions, one or more downlink regions, and a guard region. The wireless device may identify and communicate during each region based on a timing relationship between the downlink region and the uplink region. For example, the device may expect hybrid automated repeat request (HARQ) feedback for one downlink region in the same subframe based on the proximity to the next uplink region. Another downlink region may not have HARQ feedback in the same subframe. Similarly, uplink regions may or may not be scheduled within the same subframe.
Abstract:
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive a downlink transmission from a base station, transmit a first stage of feedback for the downlink transmission, identify a condition associated with the downlink transmission, and determine whether to transmit a second stage of feedback for the downlink transmission based at least in part on the identified condition associated with the downlink transmission. The second stage of feedback for the downlink transmission may be transmitted (or not transmitted) based at least in part on the identified condition associated with the downlink transmission.
Abstract:
Methods, systems, and devices for wireless communication are described. A user equipment (UE) or a base station may identify a timing advance parameter and a processing parameter for the UE, and one or both may determine a hybrid automatic repeat request (HARQ) timing based on the identified parameters. For example, if the UE has a large timing advance or reduced processing capacity, a longer HARQ timing may be chosen. When the UE receives downlink (DL) transmissions from the base station, the UE may send an acknowledgement (ACK) or negative acknowledgement (NACK) based on the chosen HARQ timing. The base station may send a retransmission (in the case of a NACK) based on the HARQ timing. In some cases, the UE may request a specific HARQ timing, or request an updated timing advance. If HARQ synchronization is lost, the UE and the base station may default to a preconfigured HARQ timing.