5G Beam Recovery Using Reference Signals and Random Access
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Solution Overview
Problem
In high-frequency 5G New Radio systems, beam failure and loss pose a significant challenge due to high pathloss, necessitating effective mechanisms for communications beam recovery.
Innovation Solution
A system and method for communications beam recovery involving the generation and transmission of configuration messages specifying reference signals and random access channel resources, enabling identification of new beams through preamble sequences, and determining UE identity based on these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high frequency (HF) operating frequencies are used to exploit greater available bandwidth and less interference, then bandwidth availability and interference reduction are improved, but pathloss increases significantly
Solution Approach 1:
The system performs preliminary beamforming configuration and reference signal transmission before actual data communication. The access node pre-establishes beam pairs using synchronization signals and channel state information reference signals, so that when beam failure occurs, recovery can proceed efficiently with pre-configured resources and parameters already in place.
Solution Approach 2:
Reference signals serve as intermediaries between the access node and UE for beam management. Specifically, synchronization signals and channel state information reference signals are transmitted through the access node to enable UE to measure and identify suitable beams, facilitating beam recovery without direct device-to-device signaling.
2Object-affected harmful factors
If beamforming is used to overcome high pathloss in HF, then pathloss compensation is improved, but system complexity increases
Solution Approach 1:
The beamforming system is segmented into distinct functional components: synchronization signal transmission for initial beam alignment, channel state information reference signal transmission for beam quality assessment, and separate random access resources for beam recovery. This segmentation allows each component to be optimized independently and simplifies the overall system management.
Solution Approach 2:
The system dynamically changes parameters such as beam directions, reference signal resources, and random access channel configurations based on channel conditions and beam failure detection. When beam failure is detected, the UE transitions from using failed beam parameters to alternative pre-configured parameters, enabling adaptive pathloss compensation without complex real-time optimization.
3Reliability
If beam failure recovery mechanisms are implemented, then system reliability is improved, but communication latency increases
Solution Approach 1:
The access node pre-configures multiple reference signals and random access resources before beam failure occurs. When failure is detected, the UE can immediately use these pre-configured resources for recovery without needing to establish new connections or wait for reconfiguration, significantly reducing recovery latency.
Solution Approach 2:
The beam failure recovery procedure skips several traditional steps by directly utilizing pre-configured reference signals and random access resources. The UE transitions from beam failure detection to recovery transmission without full re-establishment procedures, rushing through the recovery process using already-allocated resources.
4Measurement precision
If multiple reference signals are configured for beam identification, then beam identification accuracy is improved, but signaling overhead increases
Solution Approach 1:
The configured reference signals serve multiple functions: synchronization signal transmission for initial access and beam alignment, channel state information reference signal transmission for beam quality measurement and reporting, and implicit beam identification through random access resource selection. This multi-functionality reduces the need for separate dedicated reference signals for each purpose.
Solution Approach 2:
The system merges beam management functions by combining synchronization signals and channel state information reference signals into a unified reference signal framework. Both signal types are transmitted through the access node using the same physical infrastructure and can be jointly used for beam identification, reducing overall signaling overhead compared to separate dedicated beam management signals.
Data Source
AI summary
A method for operating an access node includes generating a configuration message including information specifying a set of reference signals of a first reference signal type and a set of reference signals of a second reference signal type used to identify a new beam, and information specifying random access channel resources allocated for transmitting preamble sequences, wherein each random access channel resource is associated with a reference signal of the first reference signal type, sending, to one or more user equipments (UEs), the configuration message, receiving, from a UE, a preamble sequence on one of the random access channel resources, and determining an identity of the UE in accordance with the preamble sequence and the one of the random access channel resources.