BACKGROUND

The following relates generally to wireless communications, including to relaxed control channel element (CCE) and blind decoding overbooking and dropping for New Radio (NR) ultra-reliable low-latency communications (URLLC).

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 fourth generation (4G) systems such as Long-Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as NR systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM).

A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UEs). In some wireless communications systems, a base station may transmit control information to a UE in a physical downlink control channel (PDCCH), and the UE may be configured to monitor multiple PDCCH candidates for the PDCCH that includes the control information from the base station. In particular, the UE may perform blind decoding on each of the multiple PDCCH candidates to identify the PDCCH with the control information from the base station. Improved techniques for supporting blind decoding may be desirable.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support relaxed control channel element (CCE) and blind decoding overbooking and dropping for New Radio (NR) ultra-reliable low-latency communications (URLLC). Generally, the described techniques provide for efficiently limiting a number of blind decoding attempts or CCEs that a user equipment (UE) is configured to monitor to limit complexity at the UE. When a UE is configured to use blind decoding for monitoring CCEs in multiple spans in a slot for control information from a base station, the UE may be configured to perform dropping of blind decoding candidates or CCEs in a subset of the spans (e.g., instead of in all of the spans). In other words, the UE may identify a dropping rule to drop CCE monitoring occasions or blind decoding attempts in excess of a maximum number of non-overlapping CCEs per span or a maximum number of blind decoding attempts per span, respectively, and the UE may apply the dropping rule to fewer than all of the spans within the slot. In some implementations, for example, the UE may apply the dropping rule to the first span within the slot.

A method of wireless communications at a UE is described. The method may include determining that the UE is configured to use blind decoding for monitoring CCEs in a CORESET in accordance with at least one of a maximum number of blind decoding attempts per span within a slot or a maximum number of non-overlapping CCEs per span within the slot, identifying a dropping rule for the UE to drop CCE monitoring occasions or blind decoding attempts in excess of the maximum number of non-overlapping CCEs per span or the maximum number of blind decoding attempts per span, respectively, and applying the dropping rule to fewer than all spans within the slot.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to determine that the UE is configured to use blind decoding for monitoring CCEs in a CORESET in accordance with at least one of a maximum number of blind decoding attempts per span within a slot or a maximum number of non-overlapping CCEs per span within the slot, identify a dropping rule for the UE to drop CCE monitoring occasions or blind decoding attempts in excess of the maximum number of non-overlapping CCEs per span or the maximum number of blind decoding attempts per span, respectively, and apply the dropping rule to fewer than all spans within the slot.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for determining that the UE is configured to use blind decoding for monitoring CCEs in a CORESET in accordance with at least one of a maximum number of blind decoding attempts per span within a slot or a maximum number of non-overlapping CCEs per span within the slot, means for identifying a dropping rule for the UE to drop CCE monitoring occasions or blind decoding attempts in excess of the maximum number of non-overlapping CCEs per span or the maximum number of blind decoding attempts per span, respectively, and means for applying the dropping rule to fewer than all spans within the slot.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to determine that the UE is configured to use blind decoding for monitoring CCEs in a CORESET in accordance with at least one of a maximum number of blind decoding attempts per span within a slot or a maximum number of non-overlapping CCEs per span within the slot, identify a dropping rule for the UE to drop CCE monitoring occasions or blind decoding attempts in excess of the maximum number of non-overlapping CCEs per span or the maximum number of blind decoding attempts per span, respectively, and apply the dropping rule to fewer than all spans within the slot.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a fixed span within the slot in which the UE may apply the dropping rule. In such examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include operations, features, means, or instructions for dropping one or more CCE monitoring occasions or one or more blind decoding attempts for the fixed span. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the fixed span may include a first temporal span within the slot. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the fixed span may include a span in which a common search space (CSS) is present. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include operations, features, means, or instructions for dropping one or more CCE monitoring occasions or one or more blind decoding attempts for a number of spans in which a CSS may be present. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include operations, features, means, or instructions for dropping one or more CCE monitoring occasions or one or more blind decoding attempts for a number of spans in which a CSS may be present and when the slot may be for communications with either a primary cell (PCell) or a primary-secondary cell (PSCell).

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include operations, features, means, or instructions for refraining from applying the dropping rule in a number of spans that do not include a CSS. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include operations, features, means, or instructions for refraining from applying the dropping rule to any span within the slot based on the slot not including a CSS.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a maximum number of spans in which the UE may apply the dropping rule, where applying the dropping rule to fewer than all of the spans within the slot may be based on the maximum number of spans determined by the UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the operations, features, means, or instructions for determining the maximum number of spans may be based on a UE capability. In such examples, some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting the UE capability to a base station, and identifying that a number of spans that include a CSS within the slot may be in accordance with the UE capability.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the maximum number of spans may be common for different span timing and length configurations for the UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the maximum number of spans may be different for different span timing and length configurations for the UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the maximum number of spans may include operations, features, means, or instructions for determining the maximum number of spans in which the UE may be able to apply the dropping rule based on a physical downlink shared channel (PDSCH) or physical uplink shared channel (PUSCH) minimum processing time capability of a cell with which the UE communicates over the slot.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a fixed set of spans within the slot in which the UE may apply the dropping rule. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, applying the dropping rule to fewer than all of the spans within the slot may include dropping one or more CCE monitoring occasions or one or more blind decoding attempts for the fixed set of spans. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the fixed set of spans includes a first temporal span within the slot. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the fixed set of spans includes at least one span in which a CSS is present.

A method of wireless communications at a base station is described. The method may include identifying a maximum number of spans per slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configuring one or more CSSs within spans of a slot for communication with the UE such that a number of spans within the slot that include a CSS is less than or equal to the maximum number of spans per slot, and indicating, to the UE, a CSS configuration in accordance with the configuring.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify a maximum number of spans per slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configure one or more CSSs within spans of a slot for communication with the UE such that a number of spans within the slot that include a CSS is less than or equal to the maximum number of spans per slot, and indicate, to the UE, a CSS configuration in accordance with the configuring.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying a maximum number of spans per slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, means for configuring one or more CSSs within spans of a slot for communication with the UE such that a number of spans within the slot that include a CSS is less than or equal to the maximum number of spans per slot, and means for indicating, to the UE, a CSS configuration in accordance with the configuring.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to identify a maximum number of spans per slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configure one or more CSSs within spans of a slot for communication with the UE such that a number of spans within the slot that include a CSS is less than or equal to the maximum number of spans per slot, and indicate, to the UE, a CSS configuration in accordance with the configuring.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the maximum number of spans may be common for different span timing and length configurations for the UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the maximum number of spans may be different for different span timing and length configurations for the UE. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the maximum number of spans may be based on a PDSCH or PUSCH minimum processing time capability of a cell associated with the base station and with which the UE communicates over the slot.

A method of wireless communications at a base station is described. The method may include identifying a fixed span within a slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configuring one or more CSSs within spans of the slot for communication with the UE such that at least the fixed span within the slot includes a CSS, and indicating, to the UE, a CSS configuration in accordance with the configuring.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify a fixed span within a slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configure one or more CSSs within spans of the slot for communication with the UE such that at least the fixed span within the slot includes a CSS, and indicate, to the UE, a CSS configuration in accordance with the configuring.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying a fixed span within a slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, means for configuring one or more CSSs within spans of the slot for communication with the UE such that at least the fixed span within the slot includes a CSS, and means for indicating, to the UE, a CSS configuration in accordance with the configuring.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to identify a fixed span within a slot in which a UE may apply a dropping rule, where the dropping rule indicates that the UE is to drop CCE monitoring occasions or blind decoding attempts in accordance with the dropping rule, configure one or more CSSs within spans of the slot for communication with the UE such that at least the fixed span within the slot includes a CSS, and indicate, to the UE, a CSS configuration in accordance with the configuring.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the fixed span is a first temporal span within the slot. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the CSS is an only CSS configured within the spans of the slot for communication with the UE.

