SSB to PRACH Mapping for Remote Interference Mitigation
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Solution Overview
Problem
Current wireless network designs are not robust against remote interference, particularly in Time Division Duplexing (TDD) systems, where atmospheric ducting events can cause downlink signals to interfere with uplink transmissions, degrading network performance.
Innovation Solution
The proposed solution involves reordering the mapping of Synchronization Signal Blocks (SSBs) to PRACH occasions based on remote interference levels, such that beams experiencing high interference are mapped to PRACH occasions that are further away from the uplink period, thereby minimizing the impact of remote interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current SSB to PRACH occasion mapping is used, then the mapping is simple and standardized, but the system is vulnerable to remote interference in TDD networks
Solution Approach 1:
The patent applies dynamics by making the SSB to PRACH occasion mapping configurable and adaptable rather than fixed. The network can dynamically adjust the mapping configuration based on remote interference conditions, allowing the system to transition between different mapping patterns (e.g., first mapping pattern under normal conditions, second mapping pattern under high interference) to optimize PRACH preamble robustness while maintaining manageable complexity through network-controlled flexibility
2Reliability
If beams experiencing high remote interference are mapped to PRACH occasions closer to the uplink period, then the initial access response time is reduced, but the interference impact on PRACH preamble is increased
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different beams based on their specific interference characteristics. Instead of uniform mapping, the network identifies beams experiencing high remote interference and applies specialized mapping to those specific beams, mapping them to PRACH occasions further from the uplink period to avoid interference, while other beams can use different mapping strategies, thus optimizing both reliability and time performance locally for each beam condition
3Reliability
If the PRACH occasion is positioned further away from the uplink period to avoid remote interference, then the interference exposure is reduced, but the access latency increases
Solution Approach 1:
The patent applies dynamics by enabling the network to dynamically select between different SSB to PRACH occasion mapping patterns based on real-time or historical remote interference conditions. When remote interference is detected or anticipated, the network switches to a mapping pattern that assigns affected beams to later PRACH occasions; when interference is absent, the network uses a faster mapping pattern, thus optimizing productivity adaptively rather than sacrificing efficiency permanently
Data Source
AI summary
Systems and methods are disclosed herein for mapping Synchronization Signal Blocks (SSBs) to transmit beam directions taking into account remote interference. In this regard, embodiments of a method performed by a base station in a cellular communications network are disclosed. In some embodiments, a method performed by a base station in a cellular communications network comprises determining a beam direction to SSB index mapping, taking into consideration remote interference. The method further comprises using the beam direction to SSB index mapping. Because the SSBs have corresponding Physical Random Access Channel (PRACH) occasions, determining the beam direction to SSB index mapping taking into account remote interference improves PRACH preamble robustness.