Abstract: Methods, systems, and apparatuses for wireless communication are disclosed. In one aspect, a user equipment (UE) determines to perform a synchronization procedure and receives at least one synchronization signal. The UE may generate a detection metric based at least in part on the at least one synchronization signal and compare the detection metric or detection metrics accumulated since determining to perform the synchronization procedure with a detection threshold. The detection threshold may be associated with the at least one synchronization signal utilized to determine whether the synchronization procedure can be terminated prior to receiving a predetermined number of synchronization signals. The UE may continue or terminate the synchronization procedure based at least in part on a result of the comparison.

Abstract: Methods, systems, and devices for wireless communications are described to enable a base station to configure additional reference signals, which may be referred to as configured reference signals, to include in a transmission to a user equipment (UE). The UE may transmit a report to the base station, indicating a UE capability for supporting configured reference signals, and the base station may configure a pattern for the configured reference signals. The base station may transmit an indication of the pattern to the UE, where the indication may include one or more characteristics associated with the configured reference signals. The base station may transmit the configured reference signals to the UE according to the pattern, along with one or more baseline reference signals, within an associated transmission. The UE may use the configured reference signals and the baseline reference signals to receive a transmission from the base station.

Abstract: Methods, systems, and devices for wireless communications are described. A frame, scheduling instance, scheduling period etc. may include a set of downlink subframes and a set of uplink subframes. At least one control message transmitted in a downlink subframe may schedule a set of data messages in the downlink subframes of the frame. The downlink subframe may also include data messages scheduled by a control message of a previous frame. Further, feedback timings for data messages of the frame may be determined based on the corresponding control messages (e.g., from the current frame and the previous frame). Feedback responses corresponding to the data messages may be transmitted in a bundled manner in the set of uplink subframes. Using this cross-frame scheduling technique, the resources of a frame may be efficiently utilized.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may determine a relationship between a first set of antenna ports, used for demodulation reference signals (DMRS) associated with a machine-type communication physical downlink control channel (MPDCCH) and used for the MPDCCH, and a second set of antenna ports used for cell-specific reference signals (CRS); receive CRS on one or more antenna ports of the second set of antenna ports; and receive the MPDCCH using at least the CRS based at least in part on the relationship. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may retune from a first narrowband carrier to a second narrowband carrier. The UE may determine to retune in one or more symbols of either a first narrowband subframe or a second narrowband subframe based on the number of symbols for the UE to retune and a number of other factors. The other factors may include the start symbol of a downlink channel scheduled in the second narrowband subframe, the number of antenna ports configured for the UE, hybrid automatic repeat request (HARQ) identifier (ID), coding rate or effective coding rate, among others. The UE may determine to retune in the first narrowband subframe, the second narrowband subframe, or in both subframes in order to utilize reference signals transmitted to the UE and reception of all downlink messages scheduled for the UE.

Abstract: Methods, systems, and devices for wireless communications are described. In some cases, devices such as band limited (BL) or coverage enhancement (CE) user equipment (UE) having limited transmitting and receiving capability may operate using a subset of a system bandwidth of a carrier (e.g., narrowbands). To support frequency hopping or frequency diversity in transmissions, for example, such devices may utilize retuning when a resource allocation moves from a first narrowband to a second narrowband. Retuning, however, may create challenges when transmitting and receiving capability is limited. Aspects of this disclosure may support a flexible starting physical resource block (PRB) for indicating new resource allocations for BL or CE UEs. In some aspects, a UE is disclosed which may retune between consecutive transmission time intervals (TTIs) or subframes, for example, from a first tuning band to a second tuning band (e.g., a newly defined retuning narrowband).

Abstract: Methods, systems, and devices for wireless communications are described. A user equipment (UE) may retune from a first narrowband carrier to a second narrowband carrier. The UE may determine to retune in one or more symbols of either a first narrowband subframe or a second narrowband subframe based on the number of symbols for the UE to retune and a number of other factors. The other factors may include the start symbol of a downlink channel scheduled in the second narrowband subframe, the number of antenna ports configured for the UE, hybrid automatic repeat request (HARQ) identifier (ID), coding rate or effective coding rate, among others. The UE may determine to retune in the first narrowband subframe, the second narrowband subframe, or in both subframes in order to utilize reference signals transmitted to the UE and reception of all downlink messages scheduled for the UE.

Abstract: Techniques are described for handling collisions between uplink transmissions and downlink transmissions over a wireless spectrum. Some of the techniques allow a UE to perform a collision management procedure after identifying a transmission collision (e.g., a collision between a downlink transmission with repetition and an uplink transmission, or a collision between a downlink transmission with repetition and a guard frame for an uplink transmission). The collision management procedure allows the UE to refrain from transmitting at least part of an uplink transmission, refrain from decoding at least part of a downlink transmission, or a combination thereof. Other techniques allow a base station to mitigate transmission collisions by scheduling downlink transmissions based on received, inferred, or determined parameters of uplink transmissions.

Abstract: Channel estimation performance depends on the amount of averaging performed by a channel impulse response coherent filter. For half-duplex UEs, which use a single phase locked loop (PLL) for both downlink transmissions and uplink transmissions, averaging may not be performed across downlink subframes before and after uplink subframes if the PLL's phase changes and locks to a random initial value when switching transmission directions. Techniques disclosed herein facilitate estimating the PLL's random initial phase and enable correcting the phase of symbols accordingly. By correcting the phase of the symbols, it is possible to average across symbols before and after a frequency re-tune and/or a transmission direction switch based on the phase correction. This may serve to improve the accuracy of channel estimation.

Abstract: Aspects of the disclosure relate to techniques for mitigating the decoding errors observed at the receiver as a result of puncturing symbols between consecutive subframes having the same transmission direction. To reduce the decoding errors, a plurality of transmission options, each including a number of resource blocks and a modulation and coding scheme (MCS), may be identified. In addition, each transmission option may be associated with one or more puncturing patterns that hinder decoding of a codeword at the receiver. The base station or user equipment (UE) may then select or modify at least one aspect of a scheduling decision involving the communication of the codeword in a given subframe of at least two consecutive subframes to minimize decoding errors. For example, a selected puncturing pattern or a transport block size associated with a selected transmission option may be modified.

Abstract: Techniques performed by a User Equipment (UE) are provided for fast timing acquisition for Discontinuous Reception (DRX) cycles. The UE determines one or more System Frame Number (SFN) hypotheses. Each of the one or more SFN hypothesis can represent a possible SFN at which the UE can wake up from a sleep state of a Discontinuous Reception (DRX) cycle. For at least one of the one or more SFN hypotheses, the UE generates a detection metric based at least partially on a Physical Broadcast Channel (PBCH) sequence received from a base station, and determines, based on a value of the detection metric, whether the at least one SFN hypothesis represents a current SFN in accordance with a clock source used the base station for communicating with the UE. Other aspects, embodiments, and features are also claimed and described.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration that identifies one or more narrowband channels in which the UE is to receive one or more physical downlink shared channel (PDSCH) repetitions of a paging message associated with a discontinuous reception procedure. The UE may receive, in an online mode of the UE, one or more machine-type communication physical downlink control channel (MPDCCH) repetitions of control information. The UE may receive, in the online mode of the UE, the one or more PDSCH repetitions in the one or more narrowband channels identified by the configuration. The UE may process, in an offline mode of the UE, the one or more MPDCCH repetitions and the one or more PDSCH repetitions. Numerous other aspects are provided.

Abstract: Methods, systems, and devices for wireless communications are described to enable a base station to configure additional reference signals, which may be referred to as configured reference signals, to include in a transmission to a user equipment (UE). The UE may transmit a report to the base station, indicating a UE capability for supporting configured reference signals, and the base station may configure a pattern for the configured reference signals. The base station may transmit an indication of the pattern to the UE, where the indication may include one or more characteristics associated with the configured reference signals. The base station may transmit the configured reference signals to the UE according to the pattern, along with one or more baseline reference signals, within an associated transmission. The UE may use the configured reference signals and the baseline reference signals to receive a transmission from the base station.

Abstract: Methods, systems, and apparatuses for wireless communication are disclosed. In one aspect, a user equipment (UE) determines to perform a synchronization procedure and receives at least one synchronization signal. The UE may generate a detection metric based at least in part on the at least one synchronization signal and compare the detection metric or detection metrics accumulated since determining to perform the synchronization procedure with a detection threshold. The detection threshold may be associated with the at least one synchronization signal utilized to determine whether the synchronization procedure can be terminated prior to receiving a predetermined number of synchronization signals. The UE may continue or terminate the synchronization procedure based at least in part on a result of the comparison.

Abstract: Techniques performed by a User Equipment (UE) are provided for fast timing acquisition for Discontinuous Reception (DRX) cycles. The UE determines one or more System Frame Number (SFN) hypotheses. Each of the one or more SFN hypothesis can represent a possible SFN at which the UE can wake up from a sleep state of a Discontinuous Reception (DRX) cycle. For at least one of the one or more SFN hypotheses, the UE generates a detection metric based at least partially on a Physical Broadcast Channel (PBCH) sequence received from a base station, and determines, based on a value of the detection metric, whether the at least one SFN hypothesis represents a current SFN in accordance with a clock source used the base station for communicating with the UE. Other aspects, embodiments, and features are also claimed and described.

Abstract: Channel estimation performance depends on the amount of averaging performed by a channel impulse response coherent filter. For half-duplex UEs, which use a single phase locked loop (PLL) for both downlink transmissions and uplink transmissions, averaging may not be performed across downlink subframes before and after uplink subframes if the PLL's phase changes and locks to a random initial value when switching transmission directions. Techniques disclosed herein facilitate estimating the PLL's random initial phase and enable correcting the phase of symbols accordingly. By correcting the phase of the symbols, it is possible to average across symbols before and after a frequency re-tune and/or a transmission direction switch based on the phase correction. This may serve to improve the accuracy of channel estimation.

Abstract: Techniques and apparatus for early termination of decoding of communication channels for power saving in narrowband devices are provided. One technique includes monitoring for one or more first repetitions of at least one communication channel from a base station. The device determines, based on the monitoring, whether to refrain from monitoring for one or more second repetitions of the at least one communication channel. The device enters a low power mode if the determination is to refrain from monitoring for the one or more second repetitions of the at least one communication channel.

Abstract: Methods, systems, and devices for wireless communications are described. The method includes monitoring a set of master information block broadcasts from a base station to obtain a first set of samples associated with a first prior target transmission time interval (TTI) and a second set of samples associated with a current TTI, identifying a payload change in the master information block broadcasts between the first set of one or more prior TTIs and the current TTI based on a comparison between the first set of samples and the second set of samples, modifying the first set of samples based on the identified payload change, and decoding a master information block based on a combination of the modified first set of samples and the second set of samples. Other aspects, embodiments, and features are also claimed and described.

Abstract: Methods, systems, and devices for wireless communications are described. The method includes monitoring a set of master information block broadcasts from a base station to obtain a first set of samples associated with a first prior target transmission time interval (TTI) and a second set of samples associated with a current TTI, identifying a payload change in the master information block broadcasts between the first set of one or more prior TTIs and the current TTI based on a comparison between the first set of samples and the second set of samples, modifying the first set of samples based on the identified payload change, and decoding a master information block based on a combination of the modified first set of samples and the second set of samples. Other aspects, embodiments, and features are also claimed and described.

Abstract: Aspects of the disclosure relate to techniques for mitigating the decoding errors observed at the receiver as a result of puncturing symbols between consecutive subframes having the same transmission direction. To reduce the decoding errors, a plurality of transmission options, each including a number of resource blocks and a modulation and coding scheme (MCS), may be identified. In addition, each transmission option may be associated with one or more puncturing patterns that hinder decoding of a codeword at the receiver. The base station or user equipment (UE) may then select or modify at least one aspect of a scheduling decision involving the communication of the codeword in a given subframe of at least two consecutive subframes to minimize decoding errors. For example, a selected puncturing pattern or a transport block size associated with a selected transmission option may be modified.