TECHNICAL FIELD

The technology discussed below relates generally to wireless communication systems, and more particularly, to transmission configuration indication (TCI) field invalidation after physical downlink shared channel (PDSCH) beam setting.

INTRODUCTION

In 5G NR, physical channels and reference signals may be transmitted using antenna ports. Two antenna ports may be said to be quasi co-located (QCL) if properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. Accordingly, if two antenna ports are QCL, then a receiving device that detects channel properties of a signal from one antenna port may apply those channel properties to detect a signal from the other, QCL antenna port. In wireless communication systems, such as those specified under standards for 5G NR, both the base station and wireless communication devices may identify beams for beamforming of various channels or signals based on QCL relationships associated with the various channels or signals.

Transmission configuration indication (TCI) states may be used for configuring a QCL relationship between reference signals and antenna ports of the various channels or signals. TCI states may be activated or deactivated for a particular component carrier (CC) or a particular bandwidth part (BWP).

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a form as a prelude to the more detailed description that is presented later.

A method of wireless communication operable at a user equipment (UE) is provided. The method includes detecting a beam failure on a connected beam. The method also includes transmitting a beam failure recovery request. The beam failure recovery request includes an indication of a candidate beam. The method further includes receiving a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In addition, the method includes applying the candidate beam to the PDSCH when the second message is received at least a predetermined number of symbols after receiving the first message.

A method of wireless communication operable at a base station is provided. The method includes receiving a beam failure recovery request from a user equipment (UE) based on a beam failure on a connected beam. The beam failure request includes an indication of a candidate beam. The method also includes transmitting, to the UE, a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

A user equipment (UE) in a wireless communication system is provided. The UE includes a wireless transceiver. The UE also includes a memory. The UE further includes a processor communicatively coupled to the wireless transceiver and the memory. The processor and the memory are configured to detect a beam failure on a connected beam. The processor and the memory are also configured to transmit a beam failure recovery request. The beam failure recovery request includes an indication of a candidate beam. The processor and the memory are further configured to receive a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In addition, the processor and the memory are configured to apply the candidate beam to the PDSCH when the second message is received at least a predetermined number of symbols after receiving the first message.

A base station in a wireless communication system is provided. The base station includes a wireless transceiver. The base station also includes a memory. The base station further includes a processor communicatively coupled to the wireless transceiver and the memory. The processor and the memory are configured to receive a beam failure recovery request from a user equipment (UE) based on a beam failure on a connected beam. The beam failure request includes an indication of a candidate beam. The processor and the memory are also configured to transmit, to the UE, a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

A non-transitory, processor-readable storage medium of a user equipment (UE) having instructions stored thereon is provided. The instructions, when executed by a processing circuit, cause the processing circuit to detect a beam failure on a connected beam. The instructions, when executed by the processing circuit, also cause the processing circuit to transmit a beam failure recovery request. The beam failure recovery request includes an indication of a candidate beam. The instructions, when executed by the processing circuit, further cause the processing circuit to receive a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In addition, the instructions, when executed by the processing circuit, cause the processing circuit to apply the candidate beam to the PDSCH when the second message is received at least a predetermined number of symbols after receiving the first message.

A non-transitory, processor-readable storage medium of a base station having instructions stored thereon is provided. The instructions, when executed by a processing circuit, cause the processing circuit to receive a beam failure recovery request from a user equipment (UE) based on a beam failure on a connected beam. The beam failure request includes an indication of a candidate beam. The instructions, when executed by the processing circuit, also cause the processing circuit to transmit, to the UE, a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

A user equipment (UE) is provided. The UE includes a means for detecting a beam failure on a connected beam. The UE also includes a means for transmitting a beam failure recovery request. The beam failure recovery request includes an indication of a candidate beam. The UE further includes a means for receiving a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In addition, the UE includes a means for applying the candidate beam to the PDSCH when the second message is received at least a predetermined number of symbols after receiving the first message.

A base station is provided. The base station includes a means for receiving a beam failure recovery request from a user equipment (UE) based on a beam failure on a connected beam. The beam failure request includes an indication of a candidate beam. The base station also includes a means for transmitting, to the UE, a first message including a beam failure recovery response and a second message including downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

In some examples, the second message is transmitted at least a predetermined number of symbols after the first message is transmitted, and the DCI includes a transmission configuration indication (TCI) state configuration field. In some examples, the predetermined number of symbols is based on a beam switch latency threshold for the UE. In some examples, the predetermined number of symbols comprises twenty-eight (28) symbols. In some examples, the beam failure recovery request is transmitted on a primary cell (PCell). In some examples, the first message including the beam failure recovery response is transmitted on a PCell. In some examples, the candidate beam is associated with a secondary cell (SCell). In some examples, the connected beam is a beam of the SCell. In some examples, the beam failure recovery request is received in a medium access control (MAC) control element (MAC-CE).

These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments in conjunction with the accompanying figures. While features may be discussed relative to certain embodiments and figures below, all embodiments can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.

