Abstract: A method for wireless communication at a user equipment (UE) includes transmitting a scheduling request (SR) transmission in a radio frequency spectrum band on at least one resource of a contention-based physical uplink shared channel (PUSCH), and monitoring the radio frequency spectrum band for a response to the SR transmission. A method for wireless communication at a network access device includes receiving, from a UE, a SR transmission in a radio frequency spectrum band on at least one resource of a contention-based PUSCH; determining an availability of uplink resources allocable to the UE; selecting, based at least in part on the determined availability of uplink resources, the response to the SR transmission; and transmitting in the radio frequency spectrum band, to the UE, the selected response to the SR transmission. The response to the SR transmission includes an uplink grant or an acknowledgement of the SR transmission.

Abstract: Certain aspects relate to methods and apparatus for latency reduction for UEs in a RRC connected mode. During contention-based uplink access by groups of UEs within a subframe, an eNB may decode the received uplink transmission based, at least in part, on the assigned group of resources assigned to the UE and used for transmission. Additional orthogonalization techniques such as reduced TTI size can be used to reduce collisions among different users performing contention-based transmissions. Furthermore, when the eNB fails to successfully decode the uplink transmission, the eNB may identify the UE that sent the uplink transmission based on a detected reference signal and may transmit an uplink assignment to the identified UE.

Abstract: Methods, systems, and devices for wireless communications are described. The described techniques generally support downlink transmissions. For example, a user equipment (UE) may receive a resource configuration for reception of a downlink transmission within a repetition window, the resource configuration including an indicator of a repetition window size for the downlink transmission. The UE may monitor, according to the resource configuration, one or more transmission time intervals (TTIs) of the repetition window for reception of the downlink transmission. In some cases, the downlink transmission may be a grant-free downlink transmission. Here, the UE may attempt to decode the grant-free downlink transmission during the one or more TTIs based at least in part on the repetition window size.

Abstract: Methods, systems, and devices for wireless communication are described. In some aspects, a user equipment (UE) may identify a resource block set that includes a data region and a control region, wherein the resource block set spans a portion of a system bandwidth in a shortened transmission time interval (sTTI), wherein the sTTI includes three symbols, wherein the control region occupies the three symbols and includes control information for the UE for the sTTI, and wherein the control region and the data region are frequency division multiplexed. The UE may obtain content in the sTTI based at least in part on the control information. Numerous other aspects are provided.

Abstract: Various techniques for narrowband communications in a wireless communications network are provided. Narrowband communications may be transmitted using a single resource block (RB) of a number of RBs used for wideband communications. In order to provide for efficient device discovery and synchronization using narrowband communications, a synchronization signal, such as a primary synchronization signal (PSS) or secondary synchronization signal (SSS), may be transmitted within the single resource block. The synchronization signal may be transmitted, for example, using multiple orthogonal frequency division multiplexing (OFDM) symbols within the single RB. A common reference signal (CRS) may also be present in the single resource block, which may puncture the synchronization signal, in some examples. In other examples, the synchronization signal may be mapped to non-CRS symbols of the single resource block.

Abstract: Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a device may determine a nominal coding rate of a communication based at least in part on a modulation and coding scheme (MCS) of the communication; determine whether to use a first base graph or a second base graph for decoding or transmission of the communication, wherein the determination of whether to use the first base graph or the second base graph is based at least in part on the nominal coding rate and a transport block size (TBS) of the communication, and wherein the TBS is based at least in part on a nominal number of resources and the MCS of the communication; and perform the decoding or transmission based at least in part on the determination of whether to use the first base graph or the second base graph. Numerous other aspects are provided.

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: Methods, systems, and devices for wireless communication are described that provide allocation of wireless resources for UEs in carrier aggregation resource groups that span two or more component carriers (CCs). A carrier aggregation resource group may include a portion of available wireless resources in two or more CCs, and multiple carrier aggregation resource groups may be configured that may include resources that span overlapping or non-overlapping CCs. Downlink control information may be transmitted using a downlink control region that spans two or more CCs in a carrier aggregation resource group. A UE may be configured to monitor multiple CCs for downlink control information, such as through blind decodes of each CC that may contain downlink control information.

Abstract: Methods, systems, and devices for wireless communication using various patterns of data and reference signals are described. For example, in a system that supports operation using different duration transmission time intervals (TTIs), a base station may initiate communication with a user equipment (UE) or between two UEs, and UEs may communicate with the base station or with one another using an indicated pattern of data and reference signals. The base station may send a downlink control message indicating a transmission pattern selected from a set of patterns. UEs may identify the pattern based on the indicator and decode a sequence of data and reference signals based on the pattern. In some examples, the sequence may include a set of TTIs, which may have a shorter duration than other TTIs.

Abstract: Control information may be transmitted for different TTI lengths. Different control information for the different TTIs may be transmitted using control channel resources that are established for communication of control information, such as a physical downlink control channel (PDCCH), for example. Control information for a first TTI may be located in a first set of resources, and control information for a second TTI may be located in a second set of resources. The first set of resources may be located within a first search space that may be searched by a user equipment (UE) to identify the first control information. The second set of resources may be located within a second search space that may be searched by the UE to identify the second control information.

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 communications are described. The described techniques generally support downlink transmissions. For example, a user equipment (UE) may receive a resource configuration for reception of a downlink transmission within a repetition window, the resource configuration including an indicator of a repetition window size for the downlink transmission. The UE may monitor, according to the resource configuration, one or more transmission time intervals (TTIs) of the repetition window for reception of the downlink transmission. In some cases, the downlink transmission may be a grant-free downlink transmission. Here, the UE may attempt to decode the grant-free downlink transmission during the one or more TTIs based at least in part on the repetition window size.

Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) and a base station may use low latency communications to improve the throughput of a wireless link. To facilitate efficient low latency communication, the UE may send UE-initiated CSI reports in addition to periodic and base station-initiated reports. For example, the UE may, in various examples, send UE-initiated CSI reports using contention based spectrum, using a request-to-transmit, or using a CSI differential (i.e., an indicator of a change in channel conditions). The base station may schedule different UEs for uplink low latency communication by providing resources to each UE for CSI and scheduling requests (SRs) using coherent or non-coherent uplink transmissions. The CSI and SR may also be combined with uplink feedback.

Abstract: Techniques are described for wireless communication. A first method includes receiving from a base station an indication of a set of one or more uplink interlaces of an unlicensed radio frequency spectrum band allocated for a sounding reference signal, and transmitting the sounding reference signal for a user equipment (UE) over the indicated set of one or more uplink interlaces of the unlicensed radio frequency spectrum band. A second method includes receiving an indication of an interlace of an unlicensed radio frequency spectrum band allocated for a physical uplink control channel (PUCCH) transmission, and transmitting a scheduling request and a buffer status report over the indicated interlace.

Abstract: Techniques are described for wireless communication. A first method includes winning a contention for access to an unlicensed radio frequency spectrum band, and transmitting at least a portion of a channel usage beacon signal (CUBS) over the unlicensed radio frequency spectrum band. The at least portion of the CUBS is transmitted in a number of frequency interlaces of the unlicensed radio frequency spectrum band. A second method includes winning a contention for access to an unlicensed radio frequency spectrum band; determining whether the contention is won within a threshold time before a next symbol period boundary; and transmitting at least a portion of a CUBS over the unlicensed radio frequency spectrum band. The at least portion of the CUBS is transmitted during a preamble including a fractional period of a first symbol period. The at least portion of the CUBS may be based at least in part on the determining.

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: Coordinated wireless communications using multiple transmission time intervals (TTIs) are described. Multiple TTIs may include a first TTI and a second TTI, the second TTI having a shorter duration than the first TTI. One or more parameters may be determined for communications using the first TTI and the second TTI. A first parameter of the determined parameters for the second TTI may be associated or linked with a corresponding parameter of the first TTI, and communications using the first TTI or the second TTI may be performed using the first parameter. Wireless network nodes using the first TTI may form a CoMP cooperating set, and wireless network nodes using the second TTI may for another CoMP cooperating set, and the first parameter may be applied to each of the CoMP cooperating sets.

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: Methods, systems, and devices for wireless communication are described. Different transmission time interval (TTI) durations may be supported and configured to coexist with one another. A set of TTIs with a relatively short duration may overlap in time with longer duration TTIs. Boundaries of TTIs with a relatively short duration may be configured to align with boundaries of relatively longer duration TTIs. For example, TTIs that are a Long Term Evolution (LTE) subframe, an LTE slot, and a duration of two LTE symbol periods may be supported. Two-symbol period TTIs may align with or be embedded within slot-duration TTIs, which, in turn, may align with or be embedded within a subframe. In some examples, one or more symbol periods of a subframe may be designated as a gap between two-symbol TTIs within the subframe, or such symbols may be merged with a two-symbol TTI within the subframe.

Abstract: Methods, systems, and devices for wireless communication are described. A wireless device may establish a configuration for at least one carrier based on multiple transmission time interval (TTI) lengths. Several TTI lengths may be associated in a TTI group, and aspects of the configuration may be the same for all TTIs having a TTI length in the TTI group. The device may then communicate using the carrier configuration based on the TTI group. In some cases, a second TTI group with different TTI lengths from the first group may also be identified, and the device may communicate using TTI from the second group using a different TTI group configuration. Aspects of a TTI group configuration may include a common control channel format, resource allocation granularity, hybrid automatic repeat request (HARQ) process, HARQ timing, soft buffer size, channel state information (CSI) reporting configuration, or an uplink control channel.