Wireless Node Phase Synchronization via Beacon Feedback
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Solution Overview
Problem
In multi-user wireless communication systems, synchronizing the phases and frequencies of transmitters is challenging due to independent local oscillators that can drift over time, leading to energy inefficiencies and potential cancellation of signals at the destination.
Innovation Solution
A system and method where a primary beacon signal is generated by a destination node and propagated through source nodes, allowing each node to estimate and synchronize local phase and frequency, with secondary beacon signals being retransmitted to ensure phase and frequency alignment, enabling constructive combination of signals at the destination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If each transmitter uses an independent local oscillator, then device complexity is reduced and ease of operation is improved, but phase and frequency synchronization deteriorates leading to energy inefficiency
Solution Approach 1:
The patent implements feedback mechanisms where transmitters monitor their phase and frequency alignment with the destination and adjust their local oscillators accordingly. The destination provides feedback signals indicating phase/frequency offsets, and transmitters use this feedback to correct their transmissions, maintaining energy efficiency while using independent oscillators.
Solution Approach 2:
Each transmitter independently adjusts its own phase and frequency based on received feedback from the destination. The system enables self-synchronization where nodes autonomously compensate for oscillator drift without requiring complex centralized control, resolving the contradiction between operational simplicity and energy efficiency.
2Device complexity
If transmitters do not synchronize phases and frequencies, then device complexity is reduced, but signal cancellation occurs and reliability deteriorates
Solution Approach 1:
The patent implements preliminary synchronization actions where transmitters exchange pilot signals and adjust their phase/frequency before actual data transmission. This preliminary alignment ensures reliable constructive combination during the main transmission without requiring complex continuous synchronization systems throughout the entire communication process.
3Use of energy by moving object
If precise phase alignment is achieved, then energy efficiency is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent implements partial synchronization where transmitters achieve sufficient phase alignment for practical beamforming without requiring perfect precision. The system targets a practical threshold of alignment that provides adequate energy efficiency gains while avoiding the excessive complexity of achieving theoretical perfect synchronization, recognizing that beyond a certain point, additional complexity yields diminishing returns.
Data Source
AI summary
A system and method for synchronizing the phases and frequencies of devices in multi-user, wireless communications systems are provided. A primary beacon signal is transmitted by a destination node in a wireless communications network to a plurality of source nodes. Secondary beacon signals are also exchanged between the source nodes. Using the primary and secondary beacon signals, the nodes generate local phase and frequency estimates which are used to control local phases and frequencies of the source nodes. The source nodes then transmit common information to the destination at carrier frequencies based on the estimated local frequencies and phases, so that the phases and frequencies of the transmitted information are synchronized to facilitate coherent combining of the bandpass signals at the destination. Phase and frequency synchronization can be applied to wireless communications systems having any number of source nodes, and effects of Doppler shifts and moving platforms are accounted for. Acoustic and radio-frequency signaling can be utilized.