Base Station MCS Adjustment for Beam Switch BLER Reduction
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Solution Overview
Problem
In wireless communication systems, particularly in 5G New Radio (NR) scenarios, beam switching leads to increased block error rates (BLER) due to link adaptation convergence transients, especially when switching between beams with different reference signal received power (RSRP) levels, affecting the modulation and coding scheme (MCS) adjustments.
Innovation Solution
A method and system where a base station adjusts the MCS by modifying it based on the difference in RSRP between the current and new beams, either by using beam measurement reports or channel state feedback, to minimize BLER during beam switches, often implemented in the first slot after the switch, and further refined through outer-loop link adaptation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam switching is performed to improve communication quality, then the ability to adapt to channel conditions improves, but block error rate increases due to link adaptation convergence transients
Solution Approach 1:
The base station performs preliminary actions by determining the RSRP difference between the first and second beams before completing the beam switch. This advance calculation allows the MCS to be pre-adjusted based on the expected signal quality change, preventing BLER spikes that would otherwise occur during the beam switching transition.
Solution Approach 2:
The patent directly changes the MCS parameter based on the RSRP difference between beams. When the RSRP difference exceeds a threshold, the MCS is adjusted (typically reduced) to account for the expected signal quality change, thereby maintaining reliable communication during beam switching without requiring full link adaptation convergence.
2Reliability
If MCS adjustment is made immediately after beam switch to minimize BLER, then communication reliability improves, but system complexity increases due to additional processing
Solution Approach 1:
The patent extracts only the essential element needed for MCS adjustment - the RSRP difference between beams - rather than performing full link adaptation. By isolating and using only this critical parameter, the base station achieves reliable BLER minimization without the complexity of complete link adaptation convergence processes.
Solution Approach 2:
The base station uses feedback information (beam measurement reports or channel state feedback) containing RSRP values to automatically adjust the MCS. This feedback mechanism enables the system to adapt to beam switching conditions with simple, rule-based adjustments rather than complex real-time optimization, reducing processing complexity while maintaining reliability.
Data Source
AI summary
Aspects of the disclosure relate to minimizing the block error rate (BLER) experienced by a user equipment (UE) upon a downlink beam switch at the base station. The base station may mitigate the link adaptation convergence transient upon performing a beam switch by modifying the modulation and coding scheme (MCS) according to a difference in reference signal received power (RSRP) between the old beam and the new beam. The base station may further adjust the MCS utilizing an outer-loop link adaptation process or channel state feedback (CSF) provided by the UE after the beam switch. Other aspects, features, and embodiments are also claimed and described.