Conditional Reference Signal Transmission for Multi-Beam Radio Link Monitoring
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Solution Overview
Problem
In multi-beam wireless communication systems, UEs face challenges in performing Radio Link Monitoring (RLM) due to the absence of consistently transmitted reference signals and sporadic DL/UL communication, leading to difficulties in deriving PDCCH reliability and increased resource overhead from periodic reference signal transmissions.
Innovation Solution
Implementing conditional reference signal transmission and measurement, where the base station determines whether to transmit reference signals based on UE feedback within a time window, allowing for skipping or modifying transmissions when certain conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic reference signal transmissions are implemented for RLM, then the UE can perform reliable radio link monitoring, but wireless resource overhead increases
Solution Approach 1:
The patent implements periodic reference signal transmissions at configurable intervals (e.g., every N slots or N milliseconds) rather than continuous transmissions. The base station transmits reference signals periodically to enable UE RLM while reducing overall transmission frequency. This resolves the contradiction by maintaining monitoring reliability through regular periodic updates while significantly reducing resource overhead compared to continuous transmissions.
Solution Approach 2:
The patent introduces dynamic adjustment mechanisms where the reference signal transmission period and UE monitoring behavior adapt based on radio link conditions. When conditions are good, transmissions occur less frequently; when conditions deteriorate, frequency increases. This dynamic approach maintains reliability when needed while minimizing overhead during stable conditions.
2Measurement precision
If reference signals are transmitted continuously for RLM, then measurement accuracy is maintained, but energy consumption increases
Solution Approach 1:
The UE performs reference signal measurements periodically rather than continuously, synchronized with the base station's periodic reference signal transmissions. This allows the UE to maintain measurement accuracy by regularly sampling the radio link quality while consuming significantly less energy compared to continuous monitoring. The periodic measurement cycle is configured based on reference signal transmission intervals.
Solution Approach 2:
The UE utilizes existing periodic downlink communications (data transmissions, control channels) as implicit reference signals for RLM when dedicated reference signals are not transmitted. This self-service approach allows the UE to perform measurements using available signals, maintaining measurement capability while minimizing additional energy consumption from dedicated reference signal processing.
3Adaptability or versatility
If dedicated reference signals are transmitted for each beam in multi-beam operation, then beam-specific RLM is enabled, but device complexity increases
Solution Approach 1:
The patent implements a universal reference signal structure that can serve multiple beams simultaneously or be reused across different beam directions. Instead of creating entirely separate reference signal sets for each beam, the system uses a unified reference signal design that can be transmitted on different spatial filters or beamforming weights, enabling beam-specific RLM while reducing base station complexity through signal reuse and standardized processing.
Solution Approach 2:
The patent segments the multi-beam RLM functionality into independent configurable parameters (such as beam-specific monitoring occasions, separate measurement filters, and independent reporting mechanisms) while using a shared reference signal transmission framework. This segmentation allows beam-specific capabilities without requiring completely separate signal generation and processing chains for each beam, thereby reducing overall device complexity.
Data Source
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AI summary
A user equipment apparatus determines whether a transmission is received from a base station within a time window and skips measurement of a reference signal during a subsequent period, when a transmission is received from the base station within the time window. A base station apparatus configures a UE to monitor one or more reference signals associated with a beam pair link and transmits a first signal in a transmission to the UE. The base station determines whether the transmission is received at the UE within a time window and determines whether to transmit a reference signal, based on whether the transmission is received at the UE within the time window. Upon determining that the transmission was received at the UE, the base station may skip transmission of the reference signal or modify a time, a frequency, a power, and/or a reference signal offset for the reference signal.