Spatial Random Access Handling for Preamble Collision Resolution
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Solution Overview
Problem
In wireless communication systems, multiple user equipments (UEs) transmitting the same random access preamble and channel occasion cause collisions, leading to inefficient resource allocation and increased latency due to contention resolution failures, which consume network and UE resources.
Innovation Solution
Utilizing spatial domain information to differentiate UEs in random access procedures by transmitting dedicated uplink resource allocations based on unique spatial domain characteristics, allowing UEs to monitor for multiple responses and select the best communication path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple UEs transmit random access messages using the same preamble and RACH occasion, then the random access procedure can be initiated, but preamble sequence collisions occur leading to resource allocation conflicts and increased latency
Solution Approach 1:
The patent introduces spatial domain information (angular domain) as an additional dimension to distinguish between UEs that use the same preamble and RACH occasion. By incorporating spatial domain parameters such as angle of arrival or beam identifiers, the system transforms the collision problem from a two-dimensional conflict (preamble + time) into a three-dimensional solution (preamble + time + space), enabling multiple UEs to be differentiated and served simultaneously without interference.
2Productivity
If multiple UEs transmit random access messages using the same preamble and RACH occasion, then the random access procedure can be initiated, but resource allocation conflicts occur
Solution Approach 1:
The patent segments the random access response by providing separate resource allocations for each detected UE based on their unique spatial domain information. Instead of a single shared resource allocation that causes conflicts, the system divides the uplink resources into distinct allocations (e.g., different time-frequency resources or spatial beams) tailored to each UE's spatial characteristics, thereby eliminating resource allocation conflicts.
3Loss of time
If spatial domain information is used to distinguish between UEs, then preamble sequence collisions are resolved and resource allocations are optimized, but the complexity of the random access handling increases
Solution Approach 1:
The patent enables UEs to self-identify and self-select appropriate uplink resources based on the spatial domain information contained in the random access response. Each UE uses its own spatial characteristics (e.g., its received beam or angle of arrival) to automatically determine its allocated resources without requiring complex centralized scheduling or additional signaling overhead, thereby reducing system complexity while maintaining low latency.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first network entity may transmit, to a second network entity, a first random access communication including a random access preamble. The first network entity may receive, from the second network entity, a second random access communication including an identifier indicative of the random access preamble, and a first resource allocation. The first network entity may receive, from the second network entity, a third random access communication including the identifier, and indicating a second resource allocation. The first network entity may transmit, to the second network entity, a fourth random access communication via a particular resource allocation, wherein the particular resource is either the first resource allocation or the second resource allocation. Numerous other aspects are described.