RACH Signature Mapping by Beam Type to Reduce Preamble Collisions
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in RACH signature distribution due to uniform allocation across different beam types, leading to increased preamble collisions and uneven utilization, particularly affecting UEs served by wide and narrow beams.
Innovation Solution
Variable RACH signature mapping is implemented, where the number of RACH signatures associated with each synchronization signal block (SSB) is based on the beam type, allowing for dynamic allocation to optimize signature usage and reduce collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform RACH signature allocation is used across all SSBs, then implementation simplicity is maintained, but preamble collision rate increases and resource utilization becomes uneven
Solution Approach 1:
The patent applies local quality by differentiating RACH signature allocation based on beam type characteristics. Wide beams (covering larger areas) are assigned fewer signatures, while narrow beams (covering smaller areas) are assigned more signatures. This localized adaptation to different beam qualities resolves the contradiction by optimizing reliability for each beam type while maintaining a systematic allocation approach.
Solution Approach 2:
The patent changes the allocation parameter from a uniform fixed value to a variable value based on beam type. The base station configures different numbers of RACH signatures for different SSBs according to their beam types, transforming the allocation from a static uniform parameter to a dynamic parameter that adapts to channel conditions and beam characteristics, thereby improving reliability without excessive complexity.
2Quantity of substance
If more RACH signatures are allocated to wide beams, then more UEs can access wide beam areas, but signature collision probability increases in those areas
Solution Approach 1:
The patent changes the signature allocation parameter inversely to beam width: wide beams receive fewer signatures while narrow beams receive more signatures. This parameter transformation resolves the contradiction by allocating resources according to actual demand - narrow beams need more signatures to serve their UEs without collision, while wide beams can serve more UEs with fewer signatures due to their larger coverage area distributing the load.
3Productivity
If variable RACH signature mapping based on beam type is implemented, then resource utilization is optimized and collisions are reduced, but system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing SSBs into different groups based on beam type (wide beams vs. narrow beams). Each segment (beam type group) receives a customized signature allocation scheme. This segmentation resolves the contradiction by organizing the complexity into manageable segments rather than requiring individual customization for each SSB, thereby improving productivity while controlling system complexity.
Solution Approach 2:
The patent applies preliminary action by having the base station pre-configure and indicate the variable RACH signature mapping to UEs before RACH access occurs. The mapping information is provided in advance through system information or dedicated signaling, allowing UEs to select appropriate signatures without real-time complex calculations, thus improving RACH efficiency while minimizing the complexity burden on both base station and UE.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may select a random access channel (RACH) signature from among one or more RACH signatures associated with a synchronization signal block (SSB). The UE may transmit, to a base station (BS), a RACH communication using the selected RACH signature. Numerous other aspects are provided.