Frequency Hopping Random Access Preamble for IoT Coverage
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Solution Overview
Problem
Current cellular network technologies face limitations in uplink coverage and battery life due to high peak-to-average power ratio (PAPR) in communication signals, which necessitates higher power amplifier backoff, reducing efficiency and coverage in IoT devices.
Innovation Solution
A frequency hopping pattern is implemented for random access preamble signals, hopping a fixed frequency distance at some symbol groups and a pseudo-random frequency distance at others, to minimize PAPR and enhance time-of-arrival estimation accuracy while maximizing PA efficiency and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-carrier frequency-division multiple-access (SC-FDMA) modulation is used for uplink data and control channels, then device complexity is reduced, but peak-to-average power ratio (PAPR) increases, requiring higher power amplifier backoff and reducing uplink coverage
Solution Approach 1:
The patent applies frequency hopping that dynamically changes the frequency position of symbol groups within a resource block. The frequency hop pattern varies the subcarrier allocation for different symbol groups, transforming the static single-tone transmission into a dynamic multi-frequency transmission. This dynamic frequency allocation reduces PAPR by avoiding sustained high peak power on a single frequency while maintaining SC-FDMA's low complexity benefits.
Solution Approach 2:
The patent changes the frequency domain parameters by implementing frequency hopping across multiple subcarriers within a resource block. Instead of using a fixed single tone, the system varies the frequency position (subcarrier index) for each symbol group according to a hopping pattern. This parameter change reduces PAPR while maintaining the single-carrier structure's low complexity advantage.
2Reliability
If higher power amplifier backoff is used to handle high PAPR signals, then signal transmission is possible, but power amplifier efficiency decreases, reducing device battery lifetime
Solution Approach 1:
The patent changes the frequency allocation parameters dynamically through frequency hopping, varying the subcarrier position for each symbol group. This parameter variation reduces the peak power requirements, allowing the power amplifier to operate closer to its optimal efficiency point without sacrificing signal transmission capability. The frequency hop pattern ensures that peak power moments are distributed and reduced.
3Ease of operation
If fixed frequency distance hopping is used for random access preamble signals, then frequency hopping is implemented, but time-of-arrival estimation accuracy is limited
Solution Approach 1:
The patent combines two types of frequency hopping patterns: fixed frequency distance hopping and pseudo-random frequency distance hopping. This composite hopping pattern integrates the simplicity of fixed hopping with the estimation accuracy benefits of pseudo-random hopping. The fixed component provides predictable frequency transitions for easy implementation, while the pseudo-random component enhances time-of-arrival estimation by providing better correlation properties.
Solution Approach 2:
The patent segments the frequency hopping pattern into two distinct components: a fixed frequency distance part and a pseudo-random frequency distance part. This segmentation allows each component to serve its specific function - the fixed part ensures simple implementation and the pseudo-random part improves measurement precision for time-of-arrival estimation.
4Measurement precision
If pseudo-random frequency distance hopping is used for random access preamble signals, then time-of-arrival estimation accuracy is improved, but frequency hopping pattern complexity increases
Solution Approach 1:
The patent segments the frequency hopping pattern into two manageable components: a fixed frequency distance component and a pseudo-random frequency distance component. This segmentation reduces the overall complexity by breaking down the complex hopping pattern into simpler, more manageable parts that can be implemented separately and combined.
Solution Approach 2:
The patent implements a dynamic frequency hopping pattern that adapts between fixed and pseudo-random behavior. The system dynamically switches between or combines fixed frequency hops and pseudo-random frequency hops, providing the measurement precision benefits of pseudo-random hopping while maintaining the implementation simplicity of fixed hopping through dynamic adaptation.
Data Source
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AI summary
A wireless communication device (14) (e.g., a user equipment) in a wireless communication system (10) is configured for transmitting a random access preamble signal (16). The wireless communication device (14) in particular is configured to generate a random access preamble signal (16) that comprises multiple symbol groups (18), with each symbol group (18) on a single tone during a different time resource, according to a frequency hopping pattern that hops the random access preamble signal (16) a fixed frequency distance at one or more symbol groups (18) and hops the random access preamble signal (16) a pseudo random frequency distance at one or more other symbol groups (18). Each symbol group (18) comprises one or more symbols. The wireless communication device (14) is also configured to transmit the random access preamble signal (16).