IoT PRACH Signal Frequency Selection for Narrowband Access
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Solution Overview
Problem
The existing PRACH signal of public network LTE cannot be directly applied to Internet of Things systems due to bandwidth incompatibility, as it occupies a continuous bandwidth of 1.08 MHz, which is not suitable for the narrow band frequencies (25 kHz) provided in Internet of Things systems, particularly in power systems.
Innovation Solution
A random access method that selects frequencies with preset bandwidths for sending a PRACH signal, ensuring no intersection between frequency bands, and generates a target PRACH signal based on a root allocated by the base station and a cyclic shift, allowing for successful random access in Internet of Things systems by matching the system's features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the PRACH signal of public network LTE is used, then the random access function is provided, but the bandwidth occupation of 1.08 MHz is incompatible with the narrow band frequencies (25 kHz) of Internet of Things systems
Solution Approach 1:
The patent divides the PRACH signal transmission into multiple narrow band frequency resources (25 kHz each) instead of using a single continuous 1.08 MHz bandwidth. The terminal selects at least two frequencies from the available narrow band frequencies to send the PRACH signal, with each frequency occupying a discrete narrow band resource. This segmentation approach makes the PRACH signal compatible with the Internet of Things system's narrow band frequency structure while maintaining the random access function.
2Adaptability or versatility
If multiple frequencies are selected for PRACH signal transmission, then compatibility with Internet of Things system is improved, but the complexity of frequency selection and signal generation increases
Solution Approach 1:
The base station pre-configures and notifies the terminal about the available narrow band frequency resources (25 kHz frequencies) that can be used for PRACH signal transmission. The base station also pre-generates multiple PRACH sequences with different cyclic shifts and associates them with different frequency resources. This preliminary preparation reduces the real-time complexity for the terminal during actual random access, as the terminal only needs to select from pre-defined options rather than generating signals from scratch.
Solution Approach 2:
The patent changes the key parameter of frequency bandwidth from the traditional 1.08 MHz continuous bandwidth to discrete 25 kHz narrow band frequencies. By adjusting this fundamental parameter to match the Internet of Things system's frequency structure, the system achieves compatibility while using standardized PRACH signal generation methods, thereby limiting the increase in complexity.
Data Source
AI summary
A random access method and a device are provided, to enable a device in the Internet of Things to implement random access. The method includes: selecting, by a terminal from at least two frequencies, frequencies used to send a physical random access channel PRACH signal, as frequencies occupied by target PRACH resources, where the at least two frequencies each have a preset bandwidth, and there is no intersection between frequency bands of the at least two frequencies; generating, by the terminal, a target PRACH signal based on the frequencies occupied by the target PRACH resources, a root allocated by a base station, and a cyclic shift corresponding to the root allocated by the base station; and sending, by the terminal, the target PRACH signal to the base station on the target PRACH resources.