Random Access Preamble Scrambling for Inter-Cell Interference Reduction
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Solution Overview
Problem
In the NB-IoT system, target cells experience false alarms due to inter-cell interference during random access preamble transmission, as existing mechanisms lack effective interference randomization and synchronization, leading to collisions in deep coverage scenarios.
Innovation Solution
A terminal device obtains a scrambling code sequence based on its cell identifier, generates or obtains it, and uses this sequence to scramble the random access preamble, ensuring orthogonality through synchronization or cyclic shift, thereby eliminating inter-cell interference and reducing false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell-specific scrambling code sequences are used to orthogonalize interference and reduce false alarms, then reliability is improved, but device complexity increases due to additional scrambling operations
Solution Approach 1:
The patent applies cell-specific scrambling code sequences to randomly access preambles transmitted by terminal devices. Each cell uses a unique scrambling code identified by a cell-specific parameter, creating locally differentiated signal characteristics that enable orthogonalization of interference between cells. This local quality differentiation resolves the false alarm problem while maintaining system-wide compatibility.
Solution Approach 2:
The patent introduces cell-specific parameters (such as cell ID, frequency offset, or time offset) to modify the scrambling code sequences used in random access preambles. By changing the scrambling code parameter based on cell identity, the system transforms identical preambles into cell-distinguishable signals, thereby eliminating inter-cell interference and reducing false alarms without requiring fundamental system architecture changes.
2Productivity
If frequency hopping is used within limited subcarriers to support multiple preambles, then productivity is improved, but measurement precision deteriorates due to difficulty in distinguishing cells with identical sequences
Solution Approach 1:
The patent applies cell-specific scrambling code sequences to randomly access preambles transmitted by terminal devices. Each cell uses a unique scrambling code identified by a cell-specific parameter, creating locally differentiated signal characteristics that enable orthogonalization of interference between cells. This local quality differentiation resolves the false alarm problem while maintaining system-wide compatibility.
Solution Approach 2:
The patent introduces cell-specific parameters (such as cell ID, frequency offset, or time offset) to modify the scrambling code sequences used in random access preambles. By changing the scrambling code parameter based on cell identity, the system transforms identical preambles into cell-distinguishable signals, thereby eliminating inter-cell interference and reducing false alarms without requiring fundamental system architecture changes.
Data Source
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AI summary
Embodiments of this application provide a random access preamble transmission method and an apparatus. The method includes: obtaining, by a terminal device, a scrambling code sequence, scrambling a random access preamble by using the scrambling code sequence, and finally sending a scrambled random access preamble to a network device. In this technical solution, the terminal device scrambles the random access preamble, and sends the scrambled random access preamble, to effectively eliminate inter-cell interference, and resolve a possible target cell false alarm problem.