NB-IoT Random Access Preamble Detection with Frequency Hopping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In NB-IoT systems, existing methods for detecting random access preambles using a frequency hopping scheme with a single tone face challenges in accurately estimating timing and detecting preambles, leading to high false alarm and miss detection probabilities.
Innovation Solution
A method and apparatus that remove the cyclic prefix from received signals, perform FFT to detect symbols, accumulate reception power based on a frequency hopping pattern, and estimate timing offset using inverse FFT, thereby improving detection performance by setting adaptive detection levels and normalizing subcarrier values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency hopping scheme with single tone is used for random access preamble transmission, then NB-IoT system achieves long distance communication with low power consumption, but timing estimation accuracy deteriorates leading to high false alarm and miss detection probabilities
Solution Approach 1:
The patent segments the frequency hopping pattern into multiple discrete hops, where each hop corresponds to a specific subcarrier transition. By identifying and analyzing individual frequency hops separately, the system can accurately estimate timing for each segment and combine them to achieve precise overall timing estimation, resolving the contradiction between maintaining detection reliability and improving timing precision in single-tone frequency hopping schemes
Solution Approach 2:
The patent performs preliminary detection of frequency hop patterns before final timing estimation. By first identifying the frequency hopping behavior and characteristics in advance, the system can prepare appropriate timing estimation parameters and thresholds, thereby improving timing accuracy without compromising the reliability of the overall detection process in NB-IoT random access procedures
2Reliability
If existing detection methods are used for random access preamble, then system complexity is kept simple, but detection performance deteriorates with high false alarm and miss detection rates
Solution Approach 1:
The patent introduces an intermediary frequency hop pattern analysis stage between signal reception and final preamble detection. This intermediary step processes the frequency hopping characteristics to generate enhanced detection parameters, which mediate between the simple received signal and the final detection decision, thereby improving detection performance while adding only moderate algorithmic complexity suitable for NB-IoT devices
Solution Approach 2:
The patent employs dynamic adaptation of detection parameters based on observed frequency hopping patterns. The detection algorithm dynamically adjusts thresholds and parameters according to the specific frequency hop characteristics detected in each random access attempt, enabling high detection performance with adaptive complexity that scales with the actual signal conditions rather than maintaining fixed high complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the detection performance of random access preamble sequences in NB-IoT systems by reducing false alarms and miss detections, while accurately measuring timing offsets, thus improving the reliability of preamble detection.
Implementation Method 1
performing fast Fourier transform (FFT) on the received signal with the CP removed therefrom to generate a frequency domain signal corresponding to each of a plurality of symbol periods
Implementation Method 2
performing inverse fast Fourier transform (IFFT) using a plurality of third subcarriers used to transmit the preamble sequence among the plurality of second subcarriers, and estimating timing offset of the preamble sequence based on a time domain signal with maximum energy
Data Source
AI summary
A random access preamble detection method of a base station includes removing a cyclic prefix (CP) from a received signal, detecting a plurality of first symbols corresponding to a plurality of first subcarriers included in an uplink available resource from the received signal with the CP removed, measuring reception power of the first symbol corresponding to each of a plurality of second subcarriers allocated to a random access channel among the plurality of first subcarriers, accumulating reception power with respect to each of the plurality of second subcarriers according to a predetermined frequency hopping pattern, and upon completely accumulating reception power according to the frequency hopping pattern, detecting a preamble sequence using each accumulated value of reception power of each of the plurality of second subcarriers.