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.

Abstract: Handling of asynchronous multi-carrier is discussed. In new radio (NR) fifth generation (5G) networks, the potential for provision of multi-carrier operations (e.g., carrier aggregation (CA), dual connectivity (DC), etc.) that include asynchronous component carriers (CCs) has been proposed. However, because of the asynchronous relationship network entities, such as base stations and user equipments (UEs) will manage the asynchronous CCs by obtaining timing offset information, either through derivation or direct signaling, and determining a subframe correspondence based on the timing offset relative to a reference CC. By determining the subframe correspondence to the reference CC, the base stations and UEs can accurately map communications over the asynchronous CCs to the appropriate subframes across CCs.

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: Techniques provide for identifying uplink resources that are to be used for uplink transmissions using shortened transmission time intervals (sTTIs), such as low latency or high reliability transmissions. A reference signal (RS) configuration for a three-symbol sTTI, including locations of one or more RS symbols and one or more data symbols within the sTTI may be identified. The RS configuration, along with the allocation of uplink resources, may be provided to a user equipment (UE) which may transmit uplink communications using the allocated uplink resources.

Abstract: Described techniques provide for prioritization of radio bearers and logical channels based on mixed TTI durations or numerologies of the bearers or logical channels. Two or more bearers may be identified for uplink data transmission that carry data to be transmitted using different TTI durations or numerologies. Each bearer may be prioritized based on the associated bearer type, TTI duration or numerology, or combinations thereof. Additionally, one or more logical channels may be associated with one or more bearers, and also prioritized based on the associated bearer type, TTI duration or numerology, or combinations thereof. A buffer status report (BSR) may be generated that has one or more portions associated with the different priorities of bearers or logical channels. Buffer information associated with the higher priority bearers or logical channels may be provided ahead of buffer information associated with lower priority bearers or logical channels.

Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) and a base station may communicate according to a timing configuration that includes a time delay between uplink and downlink communications. The time delay may be based on UE capabilities, scheduling in the system, and an uplink timing advance. The UE may determine an uplink timing advance and transmit an indication of the uplink timing advance to the base station. Using the uplink timing advance, the base station may determine a timing configuration to use for communicating with the UE. The timing configuration may be dynamically configured based on the value of the uplink timing advance with respect to a timing advance threshold and may be shortened or lengthened depending on whether the uplink timing advance crosses the timing advance threshold. Multiple timing advance thresholds may be used, and a timing configuration may be selected accordingly.

Abstract: Described techniques provide for communications using multiple different transmission time intervals (TTIs) while in a configured DRX mode that allows efficient scheduling and allocation of resources, and relatively efficient power usage at a user equipment (UE). In some cases, two or more available TTIs for transmissions between a base station and a UE may be identified, and a DRX cycle configured based at least in part on the available TTIs. During monitoring periods of a configured DRX cycle for a first TTI, the UE may be configured to monitor for control signal transmissions associated with a different TTI duration. In some cases, resources for a shorter TTI may be allocated using a two-stage grant. In some cases, multiple component carriers may be configured for one or more different TTIs, and one component carrier may be used to cross schedule resources on other component carriers.

Abstract: Methods, systems, and devices for wireless communication are described that provide for identifying uplink transmissions that are to be made using shortened transmission time intervals (sTTIs), and allocating uplink resources for such transmissions. A portion of the uplink resources may be reserved for reference signal transmissions, such as demodulation reference signal (DMRS) transmissions. Resources for a number of sTTIs may be aligned within a slot that comprises a number of orthogonal frequency division multiplexing (OFDM) symbols, and one of the OFDM symbols may have resources reserved that are to be shared by two or more sTTIs within the slot for DMRS transmission. The reserved OFDM symbol may be shared by two overlapping sTTIs in which the reserved OFDM symbol is common between the two sTTIs. A DMRS sequence for each sTTI may be selected based on the allocated uplink resources for the sTTIs.

Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) may transmit uplink (UL) messages in unlicensed spectrum with a reduced UL timing delay. The UL timing delay may be reduced by using a shortened transmission time interval (TTI) (e.g., a TTI that is reduced in duration relative to other TTIs in the system or in a legacy system) or by reducing the number of TTIs between a grant and the corresponding UL message. The reduced UL timing delay may decrease the likelihood that the UE will wait for a subsequent transmit opportunity (TxOp) to transmit the UL message. In some cases, the reduced UL timing delay corresponds to a reduced hybrid automatic repeat request (HARM) processing delay. In some cases, a time difference (e.g., measured in TTIs) between a measurement reference TTI a corresponding channel state information (CSI) report may also be reduced.

Abstract: Described techniques provide for identifying uplink transmissions that are to be made using shortened transmission time intervals (sTTIs), and allocating uplink resources for such transmissions. Based at least in part on the allocated uplink resources and the information to be transmitted, a reference signal configuration may be identified. The reference signal configuration, along with the allocation of uplink resources, may be provided to a user equipment (UE) which may transmit uplink communications using the allocated uplink resources. The reference signal configuration, such as a demodulation reference signal (DMRS) configuration, may be identified dynamically by a base station and signaled to the UE. In some cases, the sTTIs may include two-symbol sTTIs, three-symbol sTTIs, or combinations thereof.

Abstract: Symbol alignment and power scaling are provided for different length transmission time intervals (TTIs) within predefined boundaries, such as boundaries of a slot of a subframe. Described techniques provide for identifying time and/or frequency resources for one or more TTIs and allocating such resources based on a location within a subframe, pilot signals that may be transmitted using the resources, other processing timelines, or any combination thereof. In some cases, a power allocation for symbols within a TTI may be determined based on the allocated resources for the TTI. Frequency hopping patterns and power scaling for three-symbol TTIs are also provided.

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: Methods, systems, and devices for wireless communication are described. A user equipment (UE) may be scheduled for overlapping or concurrent uplink control information (UCI) transmissions on a non-low latency channel (e.g., physical uplink control channel (PUCCH)) and a low latency channel (shortened PUCCH (sPUCCH)). The UE may transmit on PUCCH or on sPUCCH, or both, according to the UE's configuration or capability. The UE may transmit low latency UCI on PUCCH and refrain from transmitting on sPUCCH, or the UE may transmit on sPUCCH and refrain from transmitting on PUCCH. In other examples, the UE may transmit on PUCCH and sPUCCH concurrently. The UE may split power between the PUCCH and sPUCCH so that the combined power of the two transmissions remains within a transmission power budget. In other examples, the UE may switch between concurrent transmissions and transmitting on one channel while refraining from transmitting on another channel.

Abstract: Techniques are described for wireless communication. A method for wireless communication at a user equipment (UE) includes transmitting precoder selection signals from at least two antennas of the UE during performance of a random access procedure over a wireless network; and receiving, from the wireless network during the random access procedure, an indication of a refined precoding setting for the UE. A method for wireless communication at a network access device includes receiving, from a UE during a random access procedure performed by the UE, precoder selection signals from at least two antennas of the UE; identifying a refined precoding setting for the UE based at least in part on the received precoder selection signals; and transmitting an indication of the refined precoding setting to the UE.

Abstract: Various aspects relate to determining whether one or more subframes are multicast-broadcast single-frequency network (MBSFN) subframes. A user equipment (UE) can receive, from a base station, a system information broadcast signal that includes an indication of one or more subframes as MBSFN subframes, and a subsequent system information broadcast signal that indicates at least scheduling information for a multicast control channel (MCCH) in at least a portion of the one or more subframes. The UE can determine, based at least in part on the indication or on the subsequent system information broadcast signal, a numerology for a physical multicast channel (PMCH) corresponding to the MCCH in at least the portion of the one or more subframes, and can process at least the portion of the one or more subframes based at least in part on the scheduling information or the numerology for the PMCH.

Abstract: Methods, systems, and devices for wireless communication are described. A base station may allocate resources for communication with a user equipment (UE). The resources may include one or more subframes, and each subframe may include one or more shortened transmission time intervals (sTTIs). Each sTTI may be assigned a transmission direction according to a time division duplex (TDD) pattern. Based on traffic needs and/or interference from other UEs and/or base stations, the base station may determine to modify the TDD pattern used for communication. Accordingly, a base station may transmit an indicator in a control message or control region of a TTI or sTTI, to indicate to users that a transmission direction of an sTTI in the TDD pattern is being changed. Subsequently, a user may communicate with the base station according to the reconfigured TDD pattern.

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.

Abstract: Various aspects described herein relate to receiving wireless communications from an access point, determining resources of the wireless communications associated with a search space for control information in the received wireless communications, and performing one or more of a set of blind decodes over the search space to decode at least low latency control information associated with a low latency communication technology, wherein the low latency communication technology utilizes a transmission time interval (TTI) having a duration that is less than a subframe of a legacy communication technology.

Abstract: Methods, systems, and devices for wireless communication are described that provide for uplink common burst symbol waveform selection and configuration. A waveform for the uplink common burst symbol may be selected to be a single-carrier frequency division multiplexing (SC-FDM) waveform, an orthogonal frequency division multiplexing (OFDM) waveform, or combinations thereof, based at least in part on information that is to be transmitted. A pattern for SC-FDM sequences may be selected to provide enhanced channel estimation through common pilot tones across different sequences, wideband or narrowband sequences may be selected based at least in part on information to be transmitted, and acknowledgment feedback may be transmitted in an end portion of the uplink common burst symbol in some cases to provide additional processing time for determining the acknowledgment feedback.

Abstract: Methods, systems, and devices for wireless communication are described. In one example, an indication in a first control message in a control region of a first transmission time interval (TTI) identifies a data region of the first TTI. A data region of the second TTI may be identified based on a grant of resources received in a second control message of a second TTI, where the data region of the first TTI and the control region of the second TTI are frequency division multiplexed with the data region of the second TTI. Other examples include a downlink grant at the beginning of a control region and uplink grants at the end of the control region. In other examples, a downlink grant for a user equipment (UE) may include an indication of resources allocated to the UE in that resource block and a second resource block.