Dynamic RACH Tone Allocation for 5G NR Interference Mitigation
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Solution Overview
Problem
Current Physical Random Access Channel (PRACH) formats in 5G NR systems face interference issues due to inadequate guard tones, particularly with larger subcarrier spacings, which can lead to unacceptable interference with other uplink resources.
Innovation Solution
The method involves determining the number of RACH tones based on subcarrier spacing and RACH tone spacing within resource blocks to allocate sufficient guard tones, with additional tones allocated for rate matching or puncturing when necessary, ensuring adequate guard spacing to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If guard tones are allocated in current PRACH formats, then interference with other UL channels is reduced, but guard spacing is insufficient when larger subcarrier spacings are used
Solution Approach 1:
The patent changes the parameter of guard tone allocation by determining the number of RACH tones based on both the subcarrier spacing and the RACH tone spacing. When subcarrier spacing is increased (e.g., to 60 kHz), the patent dynamically adjusts the number of guard tones to maintain adequate guard spacing, rather than using a fixed guard tone allocation. This resolves the contradiction by adapting the guard tone parameter to the subcarrier spacing parameter.
Solution Approach 2:
The patent introduces dynamic adjustment of guard tone allocation based on the relationship between subcarrier spacing and RACH tone spacing. The number of RACH tones is determined dynamically rather than being fixed, allowing the system to adapt to different subcarrier spacing configurations (15 kHz, 30 kHz, 60 kHz, etc.) while maintaining adequate interference protection.
2Productivity
If subcarrier spacing is increased in 5G/NR frame structures, then system capacity and flexibility are improved, but interference from RACH preamble sequences becomes unacceptably high
Solution Approach 1:
The patent addresses this contradiction by changing the parameter of RACH tone allocation to account for larger subcarrier spacings. When subcarrier spacing increases (improving system capacity), the patent calculates an increased number of RACH tones including additional guard tones to maintain adequate spacing and prevent harmful interference, thus resolving the contradiction through parameter adaptation.
3Ease of manufacture
If fixed PRACH formats are used, then implementation is simplified, but adequate guard spacing cannot be ensured for varying subcarrier spacings
Solution Approach 1:
The patent transitions from fixed PRACH formats to dynamic RACH tone allocation that adapts to different subcarrier spacings. The base station determines the number of RACH tones based on the subcarrier spacing and RACH tone spacing, allowing the system to maintain reliability across different configurations while keeping the implementation relatively simple through standardized determination procedures.
Data Source
AI summary
To synchronize an apparatus during wireless communication, an apparatus may transmit a Random Access Channel (RACH) preamble sequence to a base station. However, care must be taken to prevent the RACH preamble sequence from causing inadequate levels of interference in other uplink resources. In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to determine, based on a RACH subcarrier spacing and a data tone subcarrier spacing, a number of RACH tones allocated for a transmission of a RACH preamble sequence. In this manner, the apparatus may ensure that adequate uplink resources are allocated to prevent interference.