Abstract: Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive data from both a source base station and a target base station during handover. For example, the UE may refrain from resetting or reestablishing media access control (MAC) and packet data convergence protocol (PDCP) layer configurations until after a successful access procedure is performed with the target base station. In some cases, a single radio link control (RLC)/PDCP stack may be used during handover procedures. A source base station may, for example, forward data to a target base station after receiving a handover execution message. A UE may identify and resolve any duplicate data sent by both base stations during the transition. Additional signaling may be used (e.g., during the radio resource control (RRC) configuration) to indicate that a UE supports dual link handover.

Abstract: Techniques are described for wireless communication. A first method may include receiving at a user equipment (UE) over an unlicensed radio frequency spectrum band an indication of a time window associated with a transmission of a synchronization signal, and monitoring the unlicensed radio frequency spectrum band during the time window to receive a synchronization signal from a base station. A second method may include transmitting an indication of a time window associated with a transmission of a synchronization signal; performing a plurality of clear channel assessments (CCAs) on an unlicensed radio frequency spectrum band during the time window; and transmitting the synchronization signal over the unlicensed radio frequency spectrum band at a transmission time during the time window. The transmission time may be based at least in part on a result of at least one of the CCAs.

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: Aspects of the present disclosure provided techniques for wireless communications by a user equipment (UE). An exemplary method, performed by the UE, generally includes identifying a level of coverage enhancement (CE) for the UE to communicate on at least one narrowband region within a wider system bandwidth in which the UE communicates with a base station (BS) and taking one or more actions to alter one or more procedures related to mobility of the UE, based on the level of CE.

Abstract: Certain aspects of the present disclosure generally relate to wireless communications, and more specifically to random access procedures and/or prioritization of broadcast transmissions in machine type communications (MTC) devices and enhanced MTC (eMTC). An example method generally includes determining a plurality of subframes in which the UE may transmit a bundled random access channel (RACH) message to a base station (BS), determining, within the subframes, at least one narrowband region for transmitting the bundled RACH message, determining a bundling size for the bundled RACH message, the bundling size indicating a number of the plurality of subframes in which the bundled RACH message is transmitted, and transmitting the bundled RACH message in the narrowband region of the plurality of subframes, based at least in part on the determined bundling size.

Abstract: Methods, systems, and devices are described for hierarchical communications and low latency support within a wireless communications system. An eNB and/or a UE may be configured to operate within the wireless communications system which is at least partially defined through a first layer with first layer transmissions having a first subframe type and a second layer with second layer transmissions having a second subframe type. The first subframe type may have a first round trip time (RTT) between transmission and acknowledgment of receipt of the transmission, and the second layer may have a second RTT that is less than the first RTT. Subframes of the first subframe type may be multiplexed with subframes of the second subframe type, such as through time division multiplexing. In some examples symbols of different duration may be multiplexed such that different symbol durations coexist.

Abstract: Techniques for transmitting and receiving wireless communications over an unlicensed radio frequency spectrum band are disclosed, including techniques for transmitting and receiving service information blocks over the unlicensed radio frequency spectrum band, techniques for gaining access to the unlicensed radio frequency spectrum band by performing extended clear channel assessments (eCCAs), techniques for transmitting and receiving synchronization signals and reference signals over the unlicensed radio frequency spectrum band, techniques for communicating locations of reference signals, and techniques for communicating availability of certain resources to be combined across multiple different transmissions.

Abstract: Methods, systems, and devices are described for hierarchical communications and low latency support within a wireless communications system. An eNB and/or a UE may be configured to operate within the wireless communications system which is at least partially defined through a first layer with first layer transmissions having a first subframe type and a second layer with second layer transmissions having a second subframe type. The first subframe type may have a first round trip time (RTT) between transmission and acknowledgment of receipt of the transmission, and the second layer may have a second RTT that is less than the first RTT. Subframes of the first subframe type may be multiplexed with subframes of the second subframe type, such as through time division multiplexing. In some examples symbols of different duration may be multiplexed such that they different symbol durations coexist.

Abstract: According to the present disclosure, CSI and/or a plurality of ACKs related to a group of DL data transmissions may be buffered at the UE as a GACK until a DCI trigger is received from the eNB. Once the trigger is received, the UE may transmit the CSI and/or GACK to the eNB. In this way HARQ feedback and/or CSI may be reliably communicated while reducing payload. In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus send, to a UE, data transmissions associated with a first plurality of downlink subframes. In an aspect, the apparatus increments a counter for each data transmission sent to the UE. In a further aspect, the apparatus transmits, to the UE, a first trigger for a first GACK when a counter is greater than or equal to a threshold.

Abstract: Methods, systems, and devices for wireless communication are described. Discontinuous reception (DRX) operation may be configured differently on enhanced component carriers (eCCs) than on other component carriers, including a primary cell (PCell). In some cases, a user equipment (UE) may be configured with several different eCC DRX modes. An eCC DRX configuration may, for example, be coordinated with downlink (DL) transmission time interval (TTI) scheduling so each DRX ON duration may correspond to a DL burst duration of the corresponding eCC. The eCC DRX ON durations may also be scheduled according to hybrid automatic repeat request (HARQ) process scheduling. In some examples, eCC DRX ON durations may be based on listen-before-talk (LBT) procedures. In some cases, eCC DRX ON durations may be configured to contain an uplink (UL) burst to enable channel state information (CSI) reporting. The eCC DRX may also be configured to minimize interruption of the PCell.

Abstract: Methods, systems, and devices for wireless communication are described. A base station may employ a multiplexing configuration based on latency and efficiency considerations. The base station may transmit a resource grant, a signal indicating the length of a downlink (DL) transmission time interval (TTI), and a signal indicating the length of a subsequent uplink (UL) TTI to one or more user equipment (UEs). The base station may dynamically select a new multiplexing configuration by, for example, setting the length of an UL TTI to zero or assigning multiple UEs resources in the same DL TTI. Latency may also be reduced by employing block feedback, such as block hybrid automatic repeat request (HARQ) feedback. A UE may determine and transmit HARQ feedback for each transport block (TB) of a set of TBs, which may be based on a time duration of a downlink TTI.

Abstract: Techniques are described for wireless communication. One method includes determining, based at least in part on a number of downlink component carriers (CCs) scheduled for a user equipment (UE) during a reporting interval, a number of bits to be included in a physical uplink control channel (PUCCH) acknowledgement/non-acknowledgement (ACK/NAK) payload for the reporting interval; and selecting, based at least in part on the determined number of bits, a format of the PUCCH ACK/NAK payload.

Abstract: Aspects of the present disclosure provided techniques that may be applied in systems to allow for communication over a control channel utilizing a relatively narrowband (e.g., six physical resource blocks) based search space. An exemplary method, performed, for example, by a machine type communication (MTC) UE, generally includes identifying, within a subframe, a first search space to monitor for a control channel that occupies a first number of physical resource blocks (PRBs) that represents a narrowband within a system bandwidth comprising a plurality of narrowbands and monitoring at least the first search space for the control channel, wherein the control channel comprises broadcast control information.

Abstract: Techniques are described for wireless communication. One method includes winning a contention for access to an unlicensed radio frequency spectrum band, transmitting a request message upon winning the contention for access to the unlicensed radio frequency spectrum band, and receiving a response message over the unlicensed radio frequency spectrum band. The request message is transmitted by a user equipment (UE) on an enhanced physical random access channel (ePRACH), to access a cell that operates in the unlicensed radio frequency spectrum band. The response message is received in response to transmitting the request message.

Abstract: Certain aspects of the present disclosure relate to reporting difference in timing between cells using multiple connectivity in a wireless network. A first connection served by at least a first cell and a second connection served by at least a second cell to facilitate communicating with at least the first cell and at least the second cell are established. A reporting configuration specifying one or more parameters related to reporting a timing difference between cells is received. A timing difference between at least the first cell and at least the second cell is determined, and the timing difference is reported to at least the first cell over the first connection or to at least the second cell over the second connection. This can facilitate scheduling time aligned operations over the first and second cells, or related cell groups, in multiple connectivity.

Abstract: Aspects of the present disclosure provide hybrid automatic repeat request (HARQ) techniques for enhanced machine type communication (eMTC). In one aspect, a method is provided which may be performed by a wireless device such as a user equipment (UE) for determining a HARQ ID. The method generally includes determining a HARQ ID based, at least in part, on a coverage enhancement (CE) level, and performing a HARQ process timeline based, at least in part, on the determined HARQ ID. Another method is provided for determining a subframe to transmit feedback. The method generally includes determining at least one subframe to transmit a physical uplink control channel (PUCCH) to acknowledge one or more downlink transmissions based, at least in part, on availability of uplink subframes following one or more downlink subframes carrying the downlink transmissions to be acknowledged and transmitting the PUCCH in the determined at least one subframe.

Abstract: Methods, systems, and devices are described for wireless communication. A base station may configure a set of timing adjustment groups (TAGs) and a set of PUCCH cell groups for a user equipment (UE). The serving cells in the TAGs may be associated with different PUCCH cell groups. The UE may initiate a time alignment timer for each TAG, and if the timer expires prior to receiving a timing adjustment command, the UE may initiate a timing alignment procedure for a subset of serving cells based on the association between the TAGs and the PUCCH cell groups.

Abstract: Methods, systems, and devices for wireless communication are described. Discontinuous reception (DRX) operation may be configured differently on enhanced component carriers (eCCs) than on other component carriers, including a primary cell (PCell). In some cases, a user equipment (UE) may be configured with several different eCC DRX modes. An eCC DRX configuration may, for example, be coordinated with downlink (DL) transmission time interval (TTI) scheduling so each DRX ON duration may correspond to a DL burst duration of the corresponding eCC. The eCC DRX ON durations may also be scheduled according to hybrid automatic repeat request (HARQ) process scheduling. In some examples, eCC DRX ON durations may be based on listen-before-talk (LBT) procedures. In some cases, eCC DRX ON durations may be configured to contain an uplink (UL) burst to enable channel state information (CSI) reporting. The eCC DRX may also be configured to minimize interruption of the PCell.

Abstract: Certain aspects relate to methods and apparatus for conveying system information by a base station, comprising broadcasting a first system information common to each cell of a group of cells in an area and broadcasting a second system information that can vary between cells in the group of cells, wherein the second system information is broadcast more frequently than the first system information.

Abstract: Techniques are described for wireless communication. One method includes identifying a priority parameter associated with data to be transmitted on an uplink carrier; selecting, based at least in part on the identified priority parameter, between a first type of message for requesting uplink resources in a shared radio frequency spectrum band or a dedicated radio frequency spectrum band, or a second type of message for requesting uplink resources in the dedicated radio frequency spectrum band; and transmitting the selected type of message.