Asynchronous CDMA Transponder Spread Spectrum Communication
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Solution Overview
Problem
Remote monitoring systems face challenges in environments with obstructions that prevent line-of-sight communication between transponders and base stations, leading to interference and increased complexity in transponder hardware.
Innovation Solution
The system employs spread spectrum communication using unique spreading codes for transponders to transmit asynchronously, allowing multiple transponders to use the same frequency without synchronicity constraints, reducing interference and hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous communication with timing constraints is used, then communication reliability is improved, but transponder hardware complexity increases
Solution Approach 1:
The patent extracts the timing synchronization requirements from the transponder hardware by implementing asynchronous communication. The detector handles all timing and synchronization functions centrally, while transponders simply transmit their unique spreading codes without any timing constraints or handshaking protocols, thereby reducing transponder complexity while maintaining communication reliability.
Solution Approach 2:
The detector acts as an intermediary that manages all synchronization and timing functions. It receives signals from multiple transponders asynchronously, performs correlation detection to identify spreading codes, and reconstructs communication data without requiring transponders to synchronize their transmissions, thus eliminating the need for complex timing hardware in transponders.
2Productivity
If multiple transponders transmit simultaneously on the same frequency, then communication efficiency is improved, but signal interference increases
Solution Approach 1:
The patent segments the shared frequency spectrum into multiple unique spreading codes, one for each transponder. Each transponder is assigned a distinct spreading code that spreads its signal across the entire frequency band. The detector uses correlation techniques to separate and identify individual spreading codes within the composite signal, enabling multiple transponders to transmit simultaneously without interference.
Solution Approach 2:
The patent changes the signal parameter from simple frequency to spread spectrum code. Instead of assigning different frequencies to different transponders (which would reduce efficiency), the system uses unique spreading codes that modulate the frequency in a coded pattern. This allows simultaneous transmission on the same frequency while enabling the detector to distinguish between different transponders through code correlation.
3Measurement precision
If line-of-sight communication is used, then signal quality is improved, but adaptability to obstructed environments deteriorates
Solution Approach 1:
The patent adds a code dimension to the communication system. Instead of relying solely on frequency and spatial dimensions for signal differentiation, the system introduces unique spreading codes as an additional dimension. This code dimension enables signal separation and identification even when signals arrive at different times or with different strengths due to obstructions, thereby improving adaptability to obstructed environments while maintaining signal quality.
Data Source
AI summary
A system provides for remote monitoring using asynchronous code division multiple access (CDMA) communication techniques between a base station and one or more transponders. Each transponder is attached or otherwise associated with an object or an environment to be monitored. Upon receipt of an interrogation signal, a transponder generates and transmits a coded transponder signal containing the monitored data. The coded transponder signal is generated using a spreading code. Each transponder is associated with a unique, mutually exclusive set of spreading codes. Each spreading code is based on a unique transponder address and the monitored data to be sent. A detector asynchronously monitors received signals for any of the available spreading codes. Once the detector detects a particular spreading code, the base station can identify the source transponder and extract the monitored data.