CPDMA Transmitter Phase Synchronization via GPS Timing
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Solution Overview
Problem
In wireless communications systems, especially satellite communications, the lack of synchronization among transmitters leads to phase collisions, reducing the number of simultaneous transmitters that can be reliably decoded, and existing methods to increase transmitter count either increase system complexity or require higher bandwidth, making it financially unviable to synchronize all devices directly or with a satellite ground station.
Innovation Solution
Utilizing GPS satellite information to synchronize the phase of transmitters, aligning the code phase of signals at the communications satellite to coincide with a specific timing tick, ensuring that the chip times of spreading codes are substantially aligned, thereby increasing the number of simultaneous transmitters that can be reliably decoded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transmitters operate asynchronously without synchronization, then device complexity and system cost are reduced, but the number of simultaneous transmitters that can be reliably decoded decreases due to phase collisions
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing transmitters to GPS satellite timing signals before transmission. Each transmitter adjusts its code phase to align with GPS-derived time ticks, ensuring that signals arrive at the satellite receiver with synchronized code phases. This preliminary synchronization prevents phase collisions during decoding, allowing reliable reception of multiple simultaneous transmitters without requiring complex real-time synchronization mechanisms at the receiver.
2Reliability
If direct synchronization between transmitters or with ground station is implemented, then the number of simultaneous transmitters that can be reliably decoded increases, but system complexity and cost increase
Solution Approach 1:
The patent introduces GPS satellites as an intermediary synchronization source. Instead of requiring direct peer-to-peer synchronization between transmitters or complex coordination with the ground station, each transmitter independently synchronizes to the GPS satellite timing signals. The GPS infrastructure acts as a common reference that all transmitters can access autonomously, eliminating the need for complex inter-transmitter communication or ground-station-controlled synchronization while achieving reliable multi-transmitter decoding.
Data Source
AI summary
A communications protocol in accordance with one exemplary embodiment uses information from GPS satellites to synchronize the phases of transmitters, and aligns the phase with a spreading code used to de-spread the received signals at, for example, a ground station.