RU GNSS Clock Synchronization Without IEEE 1588 Hardware
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Solution Overview
Problem
Conventional ORAN systems require expensive hardware and software compliance with IEEE 1588 standards, leading to high costs and constraints for network products like small cell base stations, due to the need for costly components such as Telecom Grandmaster and network interface cards supporting the IEEE 1588 standard for time synchronization.
Innovation Solution
The ORAN system integrates a Global Navigation Satellite System (GNSS) module, crystal oscillator, clock generator, digital counter, and slot tick module in the radio unit (RU) to generate and adjust oscillation frequency, eliminating the need for costly Telecom Grandmaster and IEEE 1588-compliant hardware, and achieving time synchronization through GPS satellite signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IEEE 1588 standard compliance is implemented with Telecom Grandmaster and IEEE 1588-compliant network interface cards, then time synchronization accuracy is improved, but hardware cost and system complexity increase significantly
Solution Approach 1:
The patent extracts the time synchronization function from the expensive Telecom Grandmaster and IEEE 1588-compliant network interface card, implementing it instead within the RU's FPGA using a crystal oscillator and digital counter. This removes the need for specialized external synchronization hardware while maintaining the essential timekeeping function.
Solution Approach 2:
The patent replaces expensive, specialized hardware (Telecom Grandmaster, IEEE 1588 NIC) with inexpensive, readily available components (standard crystal oscillator, basic digital counter, GPS module). These cheaper components achieve sufficient synchronization accuracy without requiring costly proprietary equipment.
2Measurement precision
If IEEE 1588 standard compliance is implemented across all hardware components, then time synchronization accuracy is improved, but system cost increases
Solution Approach 1:
The patent replaces expensive, specialized hardware (Telecom Grandmaster, IEEE 1588 NIC) with inexpensive, readily available components (standard crystal oscillator, basic digital counter, GPS module). These cheaper components achieve sufficient synchronization accuracy without requiring costly proprietary equipment.
Solution Approach 2:
The patent uses a GPS receiver to obtain time information from satellite signals, copying the authoritative time source directly into the RU's internal clock system. This eliminates the need to purchase and deploy expensive Telecom Grandmaster equipment while still achieving accurate time synchronization.
3Reliability
If dedicated logic cores are allocated in the High-PHY layer and MAC layer for reading timestamps, then time synchronization reliability is improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent merges the time synchronization function into the FPGA's fabric, combining the crystal oscillator, digital counter, and synchronization logic into a single integrated module. This eliminates the need for separate dedicated logic cores in the High-PHY and MAC layers, reducing software complexity while maintaining reliability through hardware-level integration.
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 solution reduces costs by eliminating the need for expensive hardware and software compliance with IEEE 1588 standards, enabling precise time synchronization between the RU and DU without dedicated logic cores, and maintaining accuracy even in adverse weather conditions.
Implementation Method 1
a crystal oscillator that is set with a standard oscillation frequency
Implementation Method 2
a global navigation satellite system (GNSS) module that generates a pulse per second (PPS) signal every second
Data Source
AI summary
An ORAN system includes an RU and a DU. The RU includes a crystal oscillator set with a standard oscillation frequency, and a clock generator using the frequency as a reference to define one second, generating a drive signal and generating clock pulse signals according to the frequency. The RU includes a digital counter, which, upon receiving each clock pulse signal, adds one to a count value, and which receives a PPS signal from a GNSS module every second. Upon receiving the PPS signal, the digital counter reads the count value, determines whether the read count value is equal to a value of the frequency, and resets the count value to zero. If the read count value is not equal to the value of the frequency, the digital counter sends an oscillation frequency adjustment signal to the crystal oscillator for adjusting the crystal oscillator's oscillation frequency.