Wireless Device Initial Access via Inter-Frequency Synchronization
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Solution Overview
Problem
Current wireless devices face challenges in efficiently accessing radio access networks supporting multiple radio access technologies (RATs) due to frequency errors and increased power consumption, especially when transitioning from legacy systems like 2G/3G/4G to 5G, which requires higher carrier frequencies and less frequent synchronization signals.
Innovation Solution
A method and device configuration that allows for efficient initial access to a radio access network by obtaining system information using a first carrier frequency and RAT, then synchronizing with a second RAT at a higher carrier frequency, reducing frequency errors and power consumption through inter-frequency cell information and optimized synchronization procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a wireless device uses a low-cost crystal oscillator running at 26 MHz for initial access, then cost and power consumption are reduced, but frequency error increases to 20-30 kHz at 2 GHz carrier frequencies
Solution Approach 1:
The patent applies preliminary action by performing frequency calibration using synchronization signals before actual data reception. The crystal oscillator is calibrated in advance during the cell search process, reducing frequency error from 20-30 kHz to less than 100 Hz before normal operation begins. This preliminary calibration ensures accurate frequency tracking without requiring a more expensive oscillator.
2Adaptability or versatility
If a wireless device supports multiple RATs including legacy systems, then versatility is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements multi-functionality by using a single low-cost 26 MHz crystal oscillator to support multiple RATs (2G, 3G, 4G, and 5G) through frequency calibration. Instead of requiring separate oscillators for each RAT, the system calibrates the same oscillator for different carrier frequencies, reducing device complexity while maintaining versatility across legacy and frontier RATs.
3Loss of energy
If synchronization signals are transmitted less frequently to reduce network overhead, then network efficiency is improved, but search intervals and averaging time must be increased
Solution Approach 1:
The patent applies feedback by using the calibrated frequency from initial synchronization to guide subsequent synchronization signal detection. The frequency calibration feedback from the first synchronization allows the device to narrow its search range and reduce averaging time for subsequent synchronization signals, even when they are transmitted less frequently (e.g., every 40 ms instead of every 5 ms).
Data Source
AI summary
There is provided mechanisms for initial access to a radio access network. The method is performed by a wireless device. The wireless device is configured for accessing the radio access network using at least a first cellular RAT and a second cellular RAT. The method comprises obtaining system information using a first carrier frequency and the first RAT. The system information comprises inter-frequency cell information of the second RAT. The method comprises synchronizing with the second RAT using a second carrier frequency based on the obtained system information in order to establish initial access to the radio access network. The second carrier frequency is higher than the first carrier frequency.