Wireless Random Access Using SSB-Independent Preambles
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Solution Overview
Problem
Existing approaches to random access in wireless communication networks face challenges in scaling the number of downlink beams for finer-grained beamforming without increasing random access latency, leading to increased preamble collision probability and reduced preamble availability.
Innovation Solution
Implementing a set of random access preambles that are not associated with any synchronization signal blocks (SSBs), allowing wireless communication devices to select preambles without reporting preferred SSBs in certain situations, thereby increasing preamble availability and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of SSBs and associated downlink beams is increased for finer-grained beamforming, then received-signal quality is improved, but the number of preambles mapped to each SSB decreases leading to increased preamble collision probability
Solution Approach 1:
The patent segments the random access preamble resources into two distinct categories: SSB-specific preambles for beam identification and SSB-independent preambles for direct access. This segmentation allows the system to maintain multiple downlink beams for improved signal quality while providing a separate preamble pool that is not constrained by the number of SSBs, thereby reducing preamble collision probability.
Solution Approach 2:
The SSB-independent random access preambles serve multiple functions: they enable random access without requiring SSB reporting, support scenarios where beamforming is not needed or already determined, and provide an additional access path that reduces overall system load on SSB-specific preambles. This multi-functionality resolves the contradiction by creating a universal access mechanism that works across different beam configurations.
2Adaptability or versatility
If the number of SSBs is increased to support more downlink beams, then beamforming granularity is improved, but random access latency increases due to multiplexing SSBs across different occasions
Solution Approach 1:
The patent segments the random access procedure into two parallel paths: one requiring SSB reporting (for scenarios needing beam identification) and one without SSB reporting (for scenarios where beamforming is not needed or already determined). This segmentation allows devices to immediately use SSB-independent preambles for direct access, eliminating the time-consuming SSB reporting step and reducing random access latency while maintaining support for fine-grained beamforming through SSB-specific preambles when needed.
Solution Approach 2:
The system performs preliminary beamforming configuration and determination before the random access procedure. When the network has already determined the appropriate downlink beam for a device (through prior measurements or configurations), the device can directly use SSB-independent preambles without needing to perform SSB reporting during random access. This preliminary action eliminates unnecessary reporting steps and reduces access latency.
3Loss of information
If preambles are mapped to specific SSBs for reporting, then beam identification is achieved, but the total number of available preambles for different situations decreases
Solution Approach 1:
The patent divides the total preamble resource pool into two independent segments: SSB-specific preambles (for beam identification scenarios) and SSB-independent preambles (for scenarios where beam identification is not required). This segmentation ensures that preambles mapped to specific SSBs maintain their beam identification function, while the SSB-independent segment provides additional preambles that are not consumed by the SSB mapping mechanism, thereby increasing the total number of available preambles for different access situations.
Solution Approach 2:
The SSB-independent preambles act as an intermediary access mechanism that bridges scenarios where beam identification is needed and scenarios where it is not. These preambles provide an alternative access path that does not require SSB reporting, effectively mediating between the need for beam identification (handled by SSB-specific preambles) and the need for additional preamble resources (handled by SSB-independent preambles), thereby resolving the resource allocation contradiction.
Data Source
AI summary
A wireless communication device (12) receives a random access configuration (18) from a radio network node (14) configured to transmit multiple SSBs (16-1 . . . 16-N). The random access configuration (18) configures the wireless communication device (12) with a set (20) of one or more random access preambles. This set (20) of one or more random access preambles is not associated with any of the multiple SSBS (16-1 . . . 16-N). Upon receiving a random access preamble from this set, the radio network node (14) may transmit a random access response as a response to the random access preamble. The radio network node (14) may do so by transmitting the random access response on one or more downlink beams that are estimated from measurement of an uplink beam or uplink signal from the wireless communication device (12).