CROSS REFERENCES AND PRIORITY CLAIM

The present application is a 371 national phase filing of International Application No. PCT/US2018/021892 by Lee et al., entitled “RADIO LINK MONITORING WITHOUT ALWAYS-ON REFERENCE SIGNALS”, filed Mar. 10, 2018, which claims priority to U.S. patent application Ser. No. 15/917,553 by Lee et al., entitled “RADIO LINK MONITORING WITHOUT ALWAYS-ON REFERENCE SIGNALS”, filed Mar. 9, 2018, which claims priority to U.S. Provisional Patent Application No. 62/470,862 by Lee, et al., entitled “RADIO LINK MONITORING WITHOUT ALWAYS-ON REFERENCE SIGNALS,” filed Mar. 13, 2017, each of which is assigned to the assignee hereof and incorporated by reference herein in its entirety.

INTRODUCTION

The following relates generally to wireless communication, and more specifically to radio link monitoring (RLM) without always-on reference signals (RSs). Certain embodiments enable and provide communication devices, methods, systems, and techniques with improved connection reliability and power efficient usage.

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system, or a New Radio (NR) system). A wireless multiple-access communications system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).

Receiving devices (e.g., UEs) in some wireless communications systems may monitor radio link quality to determine synchronicity when communicating with a transmitting device (e.g., a base station, another UE, etc.) and identify radio link failures. In such cases, the receiving device may use a quality of an always-on transmission of certain RSs to perform radio link quality measurements. However, some systems may not use always-on transmissions of these RSs, and efficient techniques for radio link monitoring may be desirable to ensure robust communications.

SUMMARY

The described techniques relate to improved methods, systems, devices, or apparatuses that support RLM without always-on RSs. Generally, the described techniques provide for the use of a discontinuous reception (DRX) periodicity to enable monitoring of an RS used for RLM procedures associated with a downlink control channel. For example, a transmitting device (e.g., a base station) may configure a DRX periodicity for an RS, where the configured DRX periodicity may include a periodicity of discrete transmissions of the RS or a periodicity of a transmission window in which the RS is located (e.g., within at least one transmission time interval (TTI) of respective transmission windows). Accordingly, a receiving device (e.g., a UE) may identify the DRX periodicity and monitor radio link quality using the RS based on the DRX periodicity. In some examples, the RS may be transmitted independent of control channel transmissions, and the transmitting device may configure one or more control resource sets for the RS. Additionally, the receiving device may opportunistically monitor radio link quality independent of the configured DRX periodicity associated with the RS (e.g., the receiving device may monitor radio link quality outside of the configured discrete transmissions or transmission windows).

A method of wireless communication is described. The method may include identifying a DRX periodicity for an RS for RLM procedures, monitoring, based at least in part on the identified DRX periodicity of the RS, a radio link quality, and receiving the RS according to the DRX periodicity.

An apparatus for wireless communication is described. The apparatus may include means for identifying a DRX periodicity for an RS for RLM procedures, means for monitoring, based at least in part on the identified DRX periodicity of the RS, a radio link quality, and means for receiving the RS according to the DRX periodicity.

Another apparatus for wireless communication is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to identify a DRX periodicity for an RS for RLM procedures, monitor, based at least in part on the identified DRX periodicity of the RS, a radio link quality, and receive the RS according to the DRX periodicity.

A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to identify a DRX periodicity for an RS for RLM procedures, monitor, based at least in part on the identified DRX periodicity of the RS, a radio link quality, and receive the RS according to the DRX periodicity.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining a periodicity of discrete transmissions of the RS. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for monitoring the radio link quality independent of the periodicity of the discrete transmissions of the RS based at least in part on a detected presence of the RS.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for determining a periodicity of transmission windows for the RS, wherein the RS may be received within respective transmission windows, and monitoring the radio link quality independent of the periodicity of the transmission windows based at least in part on a detected presence of the RS.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, each of the respective transmission windows comprises one or more TTIs, and the RS may be included within at least one TTI of the one or more TTIs. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for receiving an indication of the DRX periodicity or of a length of the respective transmission windows, wherein the indication may be received via radio resource control (RRC) signaling, system information broadcast signaling, or a combination thereof.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting the RS within a particular transmission window for the RLM procedures based at least in part on one or more signal-to-noise ratios (SNRs) of discrete transmissions of the RS within the respective transmission windows.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for selecting the RS within a particular TTI for the RLM procedures based at least in part on one or more SNRs of discrete transmissions of the RS within one or more TTIs within the respective transmission windows. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the DRX periodicity for the RS may be independent of reception of control channels.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying one or more control resource sets associated with receiving the RS associated with the RLM procedures. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the one or more control resource sets comprise at least resources associated with a common control channel or resources associated with a UE-specific control channel.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying a first control resource set associated with receiving the RS. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for identifying a second control resource set associated with receiving the RS. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for using at least the first control resource set, the second control resource set, or a combination thereof the RLM procedures.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for decoding the downlink control channel. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for resetting or boosting an RLM counter based at least in part on the decoded downlink control channel.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, boosting the RLM counter comprises: identifying a type of control channel resources or an aggregation level associated with the downlink control channel. Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for boosting the RLM counter based at least in part on the identified type of control channel resources or aggregation level.

A method of wireless communication is described. The method may include identifying an RS for RLM procedures, configuring a DRX periodicity for the RS, and transmitting the RS according to the configured DRX periodicity.

An apparatus for wireless communication is described. The apparatus may include means for identifying an RS for RLM procedures, means for configuring a DRX periodicity for the RS, and means for transmitting the RS according to the configured DRX periodicity.

Another apparatus for wireless communication is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable to cause the processor to identify an RS for RLM procedures, configure a DRX periodicity for the RS, and transmit the RS according to the configured DRX periodicity.

A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to identify an RS for RLM procedures, configure a DRX periodicity for the RS, and transmit the RS according to the configured DRX periodicity.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for configuring a periodicity of transmission windows for the RS wherein the RS may be transmitted within respective transmission windows, or configuring a periodicity of discrete transmissions of the RS. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, each of the respective transmission windows comprises one or more TTIs, and the RS may be transmitted within at least one TTI of the one or more TTIs.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for transmitting an indication of the DRX periodicity or of a length of the respective transmission windows, wherein the indication may be transmitted via RRC signaling, system information broadcast signaling, or a combination thereof. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the DRX periodicity for the RS may be independent of control channel transmissions.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, or instructions for configuring one or more control resource sets for transmission of the RS associated with the RLM procedures. In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the one or more control resource sets comprise at least resources associated with a common control channel or resources associated with a UE-specific control channel.

