Random Access Preamble Spatial Overloading via Beam Resolution
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Solution Overview
Problem
In wireless communication systems, random access preamble collisions lead to increased system latency and resource utilization, as multiple user equipment (UEs) may transmit the same preamble in a random access channel (RACH) occasion, causing collisions that require additional signaling for collision resolution.
Innovation Solution
The described techniques employ spatial beam resolution to identify UEs based on the spatial separation of receive beams corresponding to preambles, allowing the base station to transmit distinct random access response messages to each UE, thereby reducing latency and resource usage by resolving collisions efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple UEs transmit the same preamble in a RACH occasion, then the system supports random access from multiple users, but preamble collisions occur leading to increased latency and resource utilization
Solution Approach 1:
The patent introduces spatial dimension (beam direction) as an additional differentiation dimension beyond the traditional preamble sequence dimension. By associating each SSB with specific beam directions and allowing different UEs to transmit the same preamble through different spatial beams, the system resolves collisions by separating users in the spatial domain rather than requiring unique preambles for each user.
2Adaptability or versatility
If multiple UEs transmit the same preamble in a RACH occasion, then the system supports random access from multiple users, but additional signaling is required for collision resolution increasing resource utilization
Solution Approach 1:
The patent introduces spatial dimension (beam direction) as an additional differentiation dimension beyond the traditional preamble sequence dimension. By associating each SSB with specific beam directions and allowing different UEs to transmit the same preamble through different spatial beams, the system resolves collisions by separating users in the spatial domain rather than requiring unique preambles for each user.
3Productivity
If the base station uses spatial beam resolution to identify UEs, then collision resolution efficiency is improved, but the system complexity increases due to beam management
Solution Approach 1:
The base station performs beam sweeping and SSB transmission beforehand to establish spatial channel characteristics and identify the best beam directions for each UE. This preliminary beam management enables the base station to pre-determine the spatial separation of UEs before random access occurs, making the subsequent collision resolution more efficient without adding complex real-time processing during the RACH procedure.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a configuration of random access resources from a base station. The configuration may indicate a quantity of a plurality of random access preambles, a quantity of a plurality of synchronization signal blocks (SSBs), and a quantity of random access preambles per SSB. The received configuration may indicate that each random access preamble of the plurality of random access preambles is available to the UE in the random access occasion for each SSB of a plurality of SSBs transmitted by the base station. The UE may select a random access preamble of the plurality of random access preambles based at least in part on the received configuration and transmit the selected random access preamble to the base station in the random access occasion.