| CPC H04B 7/088 (2013.01) [H04L 5/0051 (2013.01); H04W 16/28 (2013.01); H04W 24/10 (2013.01); H04W 76/19 (2018.02)] | 20 Claims |

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1. A method, comprising:
sending, by a first terminal apparatus, K2 first reference signals to a second terminal apparatus in K1 directions, wherein each of the K1 directions is a direction of a beam selectable by the first terminal apparatus to send a data signal to the second terminal apparatus, each first reference signal in each of the K2 first reference signals is configured to be used to detect whether a beam in a direction in which the respective first reference signal is located fails, both K1 and K2 are positive integers, and K2 is greater than or equal to K1;
determining, by the first terminal apparatus, that beams in the K1 directions all fail for N1 consecutive times, wherein N1 is a positive integer;
sending, by the first terminal apparatus, P2 second reference signals to the second terminal apparatus in P1 directions, wherein each second reference signal in the P2 second reference signals is configured to be used to measure quality of a beam in a direction in which a first reference signal of the K2 first reference signals is located, the P1 directions are a part or all of sending directions supported by the first terminal apparatus, P1 is a positive integer, and P2 is an integer greater than or equal to P1;
receiving, by the first terminal apparatus, measurement results that are of the P2 second reference signals and that are from the second terminal apparatus; and
determining, by the first terminal apparatus based on the measurement results of the P2 second reference signals, whether P1 beams corresponding to the P1 directions are available.
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