Base Station Synchronization Using GNSS and PTP
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Solution Overview
Problem
Existing wireless base-station synchronization methods face challenges in achieving precise time and frequency alignment, especially in environments where GPS satellite visibility is compromised, and are prone to errors due to multipath and asymmetry issues.
Innovation Solution
The use of global navigation satellite systems (GNSS) in conjunction with network-based packet synchronization methods, allowing for collaborative operation among receivers to develop over-determined equations that mitigate noise and error, and enable syntonization of clocks for frequency and synchronization of time using Precision Timing Protocol (PTP) and GNSS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS satellite visibility is compromised in obstructed environments, then synchronization accuracy deteriorates, but the need for base station synchronization remains critical
Solution Approach 1:
The patent combines multiple satellite systems (GPS, GLONASS, Galileo, BeiDou) into a unified receiver architecture that processes signals from all available satellites regardless of which specific system they belong to. This merging of satellite resources provides redundancy and maintains synchronization capability even when individual satellite systems are partially blocked or unavailable.
Solution Approach 2:
The patent creates virtual representations of satellite signals through signal processing techniques that generate synthetic signal copies. When direct satellite signals are blocked, the system uses copies and reconstructions of satellite signals combined with terrestrial reference signals to maintain synchronization accuracy.
2Adaptability or versatility
If packet-based synchronization methods are used, then implementation flexibility improves, but asymmetry and multipath errors increase
Solution Approach 1:
The patent implements bidirectional packet exchange between master and slave receivers with timestamp recording in both directions. The slave receiver sends packets back to the master, and both parties record arrival and departure times. This feedback mechanism allows calculation of asymmetry in the packet path and enables correction of synchronization errors caused by multipath and network asymmetry.
Solution Approach 2:
The patent explicitly models and corrects for asymmetry in packet transmission paths by measuring the difference between forward and reverse packet travel times. Rather than assuming symmetric paths, the system calculates and compensates for the asymmetric delay components, thereby improving synchronization accuracy despite using flexible packet-based methods.
3Measurement precision
If collaborative receiver techniques are implemented, then error mitigation improves, but system complexity increases
Solution Approach 1:
The patent designs a universal collaborative synchronization framework where receivers can simultaneously perform multiple functions: acting as both master and slave at different times, participating in both GNSS-based and packet-based synchronization, and serving as reference for other receivers. This multi-functionality reduces the need for specialized hardware or protocols for each synchronization mode.
Solution Approach 2:
The collaborative receiver system is self-organizing and self-synchronizing. Receivers automatically select their roles (master/slave), establish communication protocols, and coordinate their operations without external control. The system autonomously manages the complexity of collaboration by having receivers independently negotiate and maintain their synchronization relationships.
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 provides robust and accurate synchronization of base-stations, even in obstructed environments, by leveraging multiple satellite views and collaborative receiver techniques to minimize measurement and clock errors, ensuring reliable location and timing services.
Implementation Method 1
The receiver estimates the range from SV-k by establishing the time-of-arrival of the time marker event contained in the broadcast signal from SV-k
Implementation Method 2
The relationship between time and distance follows the speed of propagation of the radio signal, essentially the speed of light (nominally 3×10^8 m/s)
Data Source
AI summary
With the increasing usage of mobile devices for communication, the need for wireless base-stations deployed in strategic locations is becoming increasingly important. The increased bandwidths being transmitted between the base-station and the mobile device has mandated that enhanced transmission formats and techniques be deployed, and, in order to operate correctly, these techniques require a tight synchronization in both time/phase, and in frequency, between the various base-stations serving a general area. Due to the need to establish the geographic location of the mobile device with a high degree of accuracy, it is also necessary to establish the location of the serving base-stations with a high degree of accuracy. The invention disclosed herein provides robust and practical methods for synchronizing base-stations, as well as providing for accurate location, by leveraging the usage of global navigation satellite systems receivers in conjunction with network based schemes for packet-based (time/phase/frequency) synchronization.