Beam Failure Recovery in Wireless Access Networks
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Solution Overview
Problem
Ultra-dense wireless networks using beamforming techniques are susceptible to sudden coverage loss due to beam failure, which is not efficiently addressed by existing technologies, especially in UE-specific beam-based systems where always-on reference signals are not feasible.
Innovation Solution
A method for detecting beam failure through feedback-based determination using acknowledgement or negative acknowledgement messages, and selecting an available backup beam based on radio link quality to ensure continuous communication in wireless access networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If beamforming technique is used to concentrate transmitted energy, then data rates are improved, but susceptibility to beam failure increases
Solution Approach 1:
The system performs preliminary actions by transmitting multiple beams (first beam and second beams) simultaneously before beam failure occurs. When beam failure is detected through feedback-based determination (absence of ACK/NACK messages), the system has already prepared alternative communication paths through the second beams, enabling immediate recovery without service interruption.
Solution Approach 2:
The system changes the beam parameter dynamically by switching from the first beam to second beams based on feedback information. When the first beam fails (detected through lack of response), the system transitions to using second beams with different spatial parameters, thereby adapting to changing channel conditions and maintaining reliable communication.
2Device complexity
If feedback-based determination is used for beam failure detection, then device complexity is reduced, but detection reliability may be affected
Solution Approach 1:
The system employs feedback-based determination where the access node monitors for ACK/NACK messages from the UE in response to transmitted data messages. The absence of expected feedback indicates beam failure. This approach uses existing feedback mechanisms already present in the communication protocol, avoiding the need for separate always-on reference signals and reducing overall system complexity while maintaining reliable detection.
3Reliability
If always-on reference signals are used for beam failure detection, then detection reliability is improved, but energy consumption increases
Solution Approach 1:
The invention extracts the beam failure detection function from the traditional always-on reference signal mechanism and integrates it into the existing data message feedback process. By removing the need for separate reference signals and using only the necessary ACK/NACK feedback messages already required for data transmission, the system achieves reliable detection without the additional energy burden of continuous reference signal transmission.
Data Source
AI summary
The present invention generally relates to wireless communication, more particularly, relates to recovery from beam failure in a wireless access network where beamforming technique is used in communication between network elements. According to one aspect of the present invention, there is provided a method for recovery from beam failure in a wireless access network accessed by a user equipment (UE). The method comprises: at the wireless access network, determining whether the beam failure occurs on the basis of presence of a response from the UE during communicating between the wireless access network and the UE via a first beam; and if it is determined that the beam failure occurs, communicating with the UE via an available beam selected from the first beam and one or more second beams.