Abstract: Systems and methodologies are described that facilitate assigning resources for an anchor carrier and an additional carrier with a grant message. The grant message communicated with an anchor carrier can include resource information a plurality of carriers. Moreover, the systems and methodologies that facilitate identifying control information for an anchor carrier and/or an additional carrier based upon an operating mode, wherein the operating mode is a legacy mode or an extended mode. Based on the operating mode, particular resources associated with control regions are monitored for control information for respective anchor carrier(s) or additional carrier(s).

Abstract: Methods, systems, and devices for wireless communications are described. The described techniques generally provide for improved reference signal sharing techniques that support low latency communications. In accordance with the described techniques, a base station may transmit, and a user equipment (UE) may receive, signaling configuring the UE to transmit (or receive) a demodulation reference signal (DMRS) in an indicated transmission time interval (TTI) of a plurality of TTIs, where the DMRS is used for demodulation of a data symbol transmitted in a second TTI of the plurality of TTIs. In various examples, the base station or the UE may determine to skip a data transmission in the indicated TTI (e.g., depending on whether the transmission is in the uplink or downlink direction). The base station or the UE may then transmit the DMRS in the indicated TTI and the data symbol in the second TTI.

Abstract: Methods, systems, and devices for wireless communications are described for mapping demodulation reference signal (DMRS) data to resource elements (REs) within a shortened transmission time interval (sTTI) so as to avoid collision with other reference signal data that the sTTI may be configured to include, such as channel state information reference signal (CSI-RS) data, cell-specific reference signal (CRS) data, or the like. A base station may select a DMRS mapping pattern for an sTTI based on one or more factors, including a CSI-RS configuration, a CRS configuration of the sTTI, an antenna port configuration for CRS (e.g., a number of CRS ports and associated number of layers configured for CRS, such as a one port CRS having a two-layer configuration, or a two port CRS having a four-layer configuration), or a type of subframe that includes the sTTI.

Abstract: Methods, systems, and devices for wireless communications are described. A transmitting node, such as a base station, may transmit downlink control information (DCI) to a user equipment (UE) using a number of shortened control channel elements (sCCEs). Each sCCE may consist of a number of shortened resource element groups (sREGs). The base station may map each sCCE to one or more sREGs using a mapping function to ensure that each sCCE is mapped to a unique set of sREGs (e.g., no single sREG is allocated to more than one sCCE). Use of the mapping function may further ensure that each sREG mapped to an sCCE is within a single symbol. The transmitting node may also configure a set of resource blocks (RBs) corresponding to the sREGs such that the number of RBs per symbol is an integer multiple of the number of sREGs per sCCE.

Abstract: A user equipment (UE) may receive, during a first transmission time interval (TTI), one or more broadcasts from a base station over a first frequency range. The UE may receive, during the first TTI, a reference signal over a second frequency range that is disjoint from the first frequency range. The UE may receive, during a subsequent TTI, a downlink grant from the base station scheduling a downlink data transmission over at least portions of both the first frequency range and the second frequency range, wherein the downlink grant comprises a reference signal sharing indication. The UE may obtain a channel estimate for the second frequency range of the subsequent TTI based at least in part on the reference signal and may refrain from applying the channel estimate to the first frequency range in the subsequent TTI.

Abstract: Methods, systems, and devices for wireless communications are described. A UE may configure a physical uplink shared channel (PUSCH) using shortened transmission time intervals (sTTIs), which may be referred to as a shortened PUSCH (sPUSCH), to transmit uplink control information (UCI) to a base station or other wireless device. The UE may use mapping rules, which may be based at least in part on a number of data symbols included in the sPUSCH, to map different types of UCI to different resource elements (REs) within the sPUSCH. A base station or other wireless device may use mapping rules, which may be based at least in part on a number of data symbols included in an sPUSCH, to determine one or more REs within the sPUSCH to monitor for different types of UCI.

Abstract: Methods, systems, and devices for wireless communication are described. In some wireless communications systems, a base station may transmit downlink control information (DCI) to a user equipment (UE) in a search space of a shortened transmission time interval (sTTI) using a particular aggregation level. The aggregation level may correspond to the number of control channel elements (CCEs) used to transmit the DCI in the search space. In some cases, various aggregation levels may be supported for transmitting DCI to the UE, and the aggregation levels may be nested such that the CCEs of a lower aggregation level may be included in the CCEs of a higher aggregation level. In such cases, in order to allow a UE to correctly identify the DCI transmitted using a particular aggregation level, the base station may map the modulation symbols of the DCI to resource element groups (REGs) differently for different aggregation levels.

Abstract: Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a base station may communicate with a user equipment (UE) during short transmission time intervals (sTTIs). The base station may transmit reference signals in an sTTI for the UE to use to perform channel estimation for demodulating the data received in the sTTI. As described herein, a base station may transmit reference signals in a subset of the sTTIs used for downlink communications with the UE. The UE may receive the reference signals in the subset of the sTTIs and use these reference signals to perform channel estimation for demodulating data received in other sTTIs. In some cases, the UE may use the reference signals in one or more previous sTTIs in combination with the reference signals received in a current sTTI to perform channel estimation for demodulating data received in the current sTTI.

Abstract: Methods, systems, and devices for wireless communications are described. In some systems, base stations may transmit downlink transmissions in short transmission time intervals (sTTIs) shorter than 1 millisecond (ms) transmission time intervals (TTIs). The base stations and user equipment (UE) receiving the downlink transmissions may be configured to determine a transport block size, soft channel bit buffer size, or rate matching based on the sTTI. The transport block size may be selected based on a scaling factor associated with signaling overhead or a type, length, or index of sTTI, or based on an sTTI transport block size table. The buffer size may be selected based on scaling or not scaling a buffer size value, N_IR, associated with a TTI. Additionally, UEs may handle receiving retransmissions of downlink transmissions in different length TTIs, and base stations may select channel quality indicator-to-modulation and coding scheme mappings on an sTTI-by-sTTI basis.

Abstract: A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus may identify a potential collision between a scheduled legacy transmission time interval (TTI) communication and a scheduled shortened TTI (sTTI) communication, the legacy TTI communication having a legacy TTI duration that is longer than an sTTI duration associated with the sTTI communication. The apparatus may determine whether the legacy TTI communication is within a threshold time of being transmitted. The apparatus may transmit at least one of the sTTI communication, the legacy TTI communication, or any combination thereof, based at least in part on the determination.

Abstract: Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a base station may precode downlink signals to be transmitted to a user equipment (UE) using a precoding matrix. The precoding matrix may be selected by a UE from a number of precoding matrices (e.g., a codebook) and reported to the base station in a channel state information (CSI) report. As described herein, a base station may support techniques for limiting a number of precoding matrices that a UE may evaluate to identify a preferred precoding matrix to be indicated to the base station. In addition, the techniques described herein allow a base station to dynamically indicate an appropriate set of precoding matrices for the UE to evaluate based on the channel conditions at a given time.

Abstract: In wireless communication networks using carrier aggregation including a secondary component carrier in unlicensed spectrum, a user equipment (UE) may monitor a downlink radio link quality of secondary cells for an event indicating failure of a communication link in the unlicensed spectrum with a secondary cell. The UE detects one or more failure events based on the downlink radio link quality. When a designated set of failure events is detected, the UE declares a failure state on the secondary cell. In response to the failure state, the UE may adjust operations related to the secondary component carrier in the unlicensed spectrum in order to save power and resources.

Abstract: Methods, systems, and devices for wireless communication are described. In some cases, a user equipment (UE) may be scheduled to transmit uplink signals on different carriers during transmission time intervals (TTIs) that have different durations. As such, a TTI on a first carrier (e.g., a reference carrier) may overlap with multiple shortened TTIs (sTTIs) on a second carrier (e.g., a non-reference carrier). Using the techniques described herein, the UE may select a calibration point (or a gain index) for uplink transmissions at the beginning of the TTI on the reference carrier based on an amount of power reserved for expected power increases during the TTI. As such, when the UE has to update its transmit power for an uplink transmission during an sTTI on the second carrier, the UE may apply a digital back-off from a power associated with the calibration point.

Abstract: Methods, systems, and devices for wireless communication are described. Some wireless communications systems may support communication between a user equipment (UE) and a base station on multiple carriers (i.e., carrier aggregation). In some cases, the UE may be scheduled to transmit uplink signals on the different component carriers during transmission time intervals (TTIs) that have different durations. In such cases, it may be appropriate for the UE to determine a maximum transmit power limit relating to the amount of power used for the uplink transmissions on the multiple carriers. As described herein, the UE may identify one of the component carriers as a reference component carrier, and the UE may determine the maximum transmit power limit for a duration of a TTI associated with the reference component carrier. The UE may then transmit on the multiple carriers in compliance with the maximum transmit power limit.

Abstract: Methods, systems, and devices for wireless communication are described for shortened transmission time interval (TTI) configuration based on user equipment (UE) capabilities. A UE may determine, for each of one or more supported bands or band combinations, a capability of the UE to process transmissions having a first transmission time interval (TTI) duration and a second TTI duration, the first TTI duration being shorter than the second TTI duration. The UE may transmit to a base station an indicator representing the capability for the each of the one or more supported bands or band combinations. The base station may receive the indicator, schedule a component carrier within a frequency band of a first supported band combination of the one or more supported band combinations based at least in part on the received indicator, and transmit information within the frequency band of the component carrier based on the scheduling.

Abstract: Methods, systems, and devices for wireless communication are described that support dynamic transient period configurations for shortened transmission time intervals (sTTIs). A transient period may be configured within uplink transmissions such that protection is enabled for reference signals and data. For example, a user equipment (UE) may receive a resource grant from a base station for an uplink transmission, where the uplink transmission includes at least a first reference signal and a transmission time interval (TTI) that includes data and a second reference signal. The UE may identify a type of the reference signals and data, and may determine a priority based on the identified types of reference signals and data. The UE may then configure a transient period that overlaps with the first reference signal, the TTI, or both, based on the priority.

Abstract: A base station may transmit a grant to user equipment (UEs), indicating uplink resources for transmission of pending data at a UE. Uplink resources may include uplink resources associated with transmission time intervals (TTIs) and/or shortened TTIs (sTTIs). A UE may identify pending data associated with a data type (e.g., low latency data, internet traffic, etc.) and transmit a scheduling request (SR) for a grant of uplink resources. The data type of the pending data (e.g., the logic channel group identification (LCG ID) associated with a buffer status) may be indicated such that uplink resources may be granted to the UE to reduce latency. In some aspects, the SR may indicate uplink resources associated with sTTIs. Further, the UE may prioritize pending data and buffer status reports (BSRs) associated with other data within the received grant.

Abstract: An apparatus may receive a downlink subframe from a serving base station. The downlink subframe may include interference associated with a second subframe transmitted by an intra-frequency neighboring cell (IFNC). The apparatus may detect whether there are interfering cell-specific reference signals (CRS) in one or more symbols of the second subframe. The apparatus may determine, based on whether interfering CRS are detected in the one or more symbols of the second subframe, a subframe type of the second subframe. The apparatus may cancel detected interfering CRS from the received downlink subframe based on the determined subframe type of the second subframe.

Abstract: The present disclosure relates to reducing control overhead in a wireless communication system. For example, a network entity may determine to transmit data according to a codeword format based on at least one of a transmission time interval (TTI), or a traffic type of the data, or any combination thereof, and configure the data for transmission on a communication channel according to the codeword format. Further, for instance, a user equipment may receive a transmission from a network entity on a downlink communication channel according to a codeword format, and transmit at least one of an acknowledgement (ACK) or a negative acknowledgement (NACK) on an uplink communication channel in response to receiving the transmission from the network entity.

Abstract: A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus may identify a potential collision between a scheduled legacy transmission time interval (TTI) communication and a scheduled shortened TTI (sTTI) communication, the legacy TTI communication having a legacy TTI duration that is longer than an sTTI duration associated with the sTTI communication. The apparatus may determine whether the legacy TTI communication is within a threshold time of being transmitted. The apparatus may transmit at least one of the sTTI communication, the legacy TTI communication, or any combination thereof, based at least in part on the determination.