Random Access Uplink Beam Indication via Reference Signal Quality
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Solution Overview
Problem
In wireless communication systems, particularly in uplink dense deployment systems and those using supplementary uplink carriers, selecting an uplink beam based on a downlink beam can result in lower communication quality and potential failure to receive random access messages due to decoupling of uplink and downlink beams.
Innovation Solution
The base station configures user equipment (UE) with random access uplink beams independently of downlink beams by transmitting reference signals and identifying optimal uplink beams based on signal quality, providing control signaling for UE to use in subsequent random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uplink beam is selected based on downlink beam, then device complexity is reduced, but communication quality deteriorates due to uplink-downlink beam decoupling
Solution Approach 1:
The UE autonomously selects uplink beams by measuring downlink reference signals and identifying corresponding uplink beams based on signal quality, without requiring base station configuration or control signaling. This self-service approach eliminates the need for complex base station processing while maintaining reliable communication through quality-based beam selection.
2Reliability
If independent uplink beam configuration is implemented, then communication quality is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The base station pre-configures the UE with multiple uplink beams and their associated reference signals before random access procedures. The UE performs measurements and identifies suitable beams in advance, storing this information for later use during random access, thereby avoiding real-time complex processing while ensuring communication quality.
Solution Approach 2:
The UE measures downlink reference signals transmitted by the base station using different downlink beams, evaluates signal quality metrics, and uses this feedback information to autonomously select the corresponding uplink beam. This feedback mechanism ensures high communication quality without requiring complex base station intervention during the actual random access process.
3Measurement precision
If multiple reference signals are transmitted for beam identification, then beam selection accuracy is improved, but transmission time and latency increase
Solution Approach 1:
The base station transmits multiple downlink reference signals using different downlink beams before the random access procedure, and the UE performs measurements and identifies suitable uplink beams in advance. This preliminary beam identification eliminates the need for time-consuming beam testing during random access, thereby maintaining high selection accuracy while reducing latency.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described that support enhanced methods for indicating random access transmission beams. For example, a user equipment (UE) may transmit a set of uplink reference signals to a base station, each uplink reference signal corresponding to a respective uplink beam. The base station may receive the uplink reference signals and may determine signal qualities for the uplink beams. The base station may identify one or more uplink beams for the UE to use in subsequent random access procedures and may transmit control signaling to the UE indicating one or more beams for random access procedure transmissions. The UE may transmit random access messages to the base station using an uplink beam selected based on the control signaling received from the base station.