Secondary Cell Beam Failure Recovery via Primary Cell MAC CE
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Solution Overview
Problem
In wireless communication networks using mmWave spectrum, beam failures can occur due to factors like UE orientation and environmental obstructions, disrupting communication links between user equipment (UE) and secondary cells (SCells), necessitating effective beam failure recovery (BFR) mechanisms.
Innovation Solution
The UE initiates a BFR operation by transmitting a BFR Medium Access Control (MAC) Control Element (CE) to the primary cell, employing various methods such as dedicated scheduling requests, contention-based random access, and timer/counter-controlled retransmissions to recover beam failures with secondary cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If beamforming is used for mmWave communication, then directional signal transmission is achieved, but beam failure occurs due to UE orientation, mobility, or environmental obstructions
Solution Approach 1:
The network pre-configures multiple candidate beams and beam failure recovery resources before beam failure occurs. When beam failure is detected, the UE can immediately use the pre-prepared candidate beams for recovery without waiting for network reconfiguration, thus maintaining high data transmission speed while improving beam connection reliability through prepared redundancy
Solution Approach 2:
The system dynamically changes beam parameters (beam direction, beam width) based on UE mobility and environmental conditions. By adjusting beamforming parameters in real-time and having multiple candidate beam configurations available, the system adapts to orientation changes and obstructions, maintaining reliable connection while supporting high-speed transmission
2Productivity
If carrier aggregation is implemented with multiple base stations, then throughput is increased, but complexity of beam failure management increases
Solution Approach 1:
The patent extracts the beam failure management function for SCells from the UE and centralizes it in the network. The network independently detects beam failure on SCells and manages recovery operations, removing the burden of complex multi-cell beam failure management from the UE while maintaining high throughput through carrier aggregation
Solution Approach 2:
The network acts as an intermediary that coordinates beam failure recovery across multiple cells in carrier aggregation. Instead of the UE managing beam failures for each SCell independently, the network mediates the recovery process by receiving BFR requests and coordinating resource allocation, simplifying UE complexity while maintaining high productivity
3Reliability
If UE transmits BFR MAC CE to primary cell for secondary cell beam failure, then recovery is achieved, but transmission resources are consumed
Solution Approach 1:
The system uses partial action by transmitting only essential BFR information through compact MAC CE formats rather than full reconfiguration messages. This reduces transmission energy consumption while achieving the necessary recovery reliability. The BFR MAC CE contains only critical information (SCell index, candidate beam indicator) needed for recovery, avoiding excessive data transmission
Data Source
AI summary
A user equipment (UE) is connected to a wireless network and operates in a carrier aggregation (CA) state that includes a first connection to a primary cell and a second connection to a secondary cell. The UE determines a beam failure has occurred for one of the first connection or the second connection and initiates a beam failure recovery (BFR) operation. The BFR operation includes transmitting, to the primary cell, a BFR Medium Access Control (MAC) Control Element (CE).