Uplink Beam Sweeping for Random Access in Wireless Systems
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently determining the best uplink beam for random access procedures, particularly in scenarios with uplink dense deployment or supplementary uplink techniques, where the optimal beam may differ from the downlink beam used for control messages.
Innovation Solution
The implementation of an uplink beam sweeping procedure during random access, where the user equipment (UE) transmits a series of reference signals using a set of directional beams, allowing the base station to select the best beam and indicate it in a random access response message, enabling the UE to transmit subsequent messages using the optimal beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE uses a downlink beam for uplink transmission during random access, then the beam selection procedure is simplified, but the uplink communication efficiency deteriorates because the optimal uplink beam may differ from the downlink beam
Solution Approach 1:
The UE performs uplink beam sweeping by transmitting reference signals using multiple directional beams before the actual uplink data transmission. This preliminary beam selection allows the base station to identify the optimal uplink beam in advance, ensuring that subsequent communications use the best beam rather than defaulting to a downlink-based selection.
Solution Approach 2:
The system dynamically adapts the uplink beam selection based on real-time channel conditions. Instead of statically using the downlink beam for uplink transmission, the UE sweeps through multiple directional beams and the base station selects the optimal one based on received signal quality, making the beam selection adaptive to current uplink channel characteristics.
2Productivity
If the UE performs uplink beam sweeping with multiple directional beams, then the uplink communication efficiency is improved, but the random access procedure latency increases
Solution Approach 1:
The UE performs beam sweeping with a limited set of directional beams rather than exhaustively testing all possible beams. The base station configures the UE with a specific set of beams to sweep through, which is sufficient to find an adequate uplink beam without requiring complete coverage of all spatial directions, thus reducing the time overhead.
Solution Approach 2:
The beam sweeping procedure focuses on local spatial regions where the UE is most likely to find suitable uplink beams based on downlink measurements. Instead of uniformly sweeping all directions, the system concentrates beam testing in promising spatial sectors, reducing the overall number of beams that need to be tested while maintaining effective beam selection.
3Measurement precision
If the base station receives reference signals from multiple directional beams, then the beam selection accuracy is improved, but the signal processing complexity increases
Solution Approach 1:
The base station processes reference signals from multiple directional beams by segmenting the beam set into manageable groups. Instead of simultaneously processing all beams from all UEs, the system divides the beam sweeping process into discrete, organized sequences that can be processed efficiently, reducing the computational burden while maintaining the ability to evaluate multiple beam options.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The method may involve a user equipment (UE) utilizing beam sweeping during a random access procedure to determine an uplink beam for subsequent communication with a base station. The UE may transmit a first message indicating a random access preamble for a random access procedure and a plurality of reference signals using a set of directional beams. The base station may receive the reference signals or information related to the reference signals and transmit a second message indicating a directional beam of the set of directional beams and a set of resources. Upon receiving the second message, the UE may transmit the third message over the set of resources using the indicated directional beam.