Communication System Threshold Control for Hidden Terminal Collision
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Solution Overview
Problem
In near-field communication systems, the 'hidden terminal' problem occurs when communication devices fail to exclusively use electromagnetic waves, leading to crosstalk and data reception issues due to incomplete detection of neighboring devices, requiring complex control logic and increased costs to resolve.
Innovation Solution
A communication system where a first communication device starts outputting an electromagnetic wave if it detects no wave above a first threshold, and a second device requires a wave above a second threshold to communicate, ensuring data demodulation and preventing collisions by adjusting output based on detected wave levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communication devices use electromagnetic wave detection to control exclusive use, then data transfer reliability is improved, but hidden terminal problem causes crosstalk and reception failures
Solution Approach 1:
The patent introduces two distinct threshold parameters (first threshold for detection, second threshold for communication) to resolve the hidden terminal problem. By changing the parameter values based on the communication stage, the system achieves reliable detection while preventing crosstalk during data transfer.
Solution Approach 2:
The patent performs preliminary electromagnetic wave detection at a first threshold before actual communication begins. This preliminary action identifies the presence of other devices, allowing the system to adjust communication parameters or avoid conflicts before data transfer starts, thereby preventing hidden terminal issues.
2Reliability
If conventional RTS/CTS control logic is used to solve hidden terminal problem, then data collision prevention is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential function of collision prevention from the complex RTS/CTS protocol, retaining only the critical threshold-based detection and control mechanism. This simplification maintains data collision prevention while removing unnecessary protocol overhead and reducing device complexity.
Solution Approach 2:
The communication devices autonomously determine whether to transmit based on comparing detected electromagnetic wave levels against predetermined thresholds. This self-service mechanism eliminates the need for complex centralized control logic, allowing each device to independently make transmission decisions while preventing collisions.
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 effectively prevents data collisions and ensures reliable data transfer by establishing clear communication thresholds, simplifying the system and reducing costs compared to conventional methods.
Implementation Method 1
when detecting means does not detect the electromagnetic wave at the level of a first threshold or more, a first communication device starts to output an electromagnetic wave
Implementation Method 2
a second communication device requires the electromagnetic wave at the level of a second threshold or more higher than the first threshold so as to obtain data by demodulating means
Data Source
AI summary
An RF (radio frequency) signal is generated at a first communication device and is modulated. A second RF signal provided to the first communication device from the second communication device is demodulated. The second RF signal is detected. The generating is actuated to initiate an active or a passive mode communication, when the detecting does not detect the second RF signal at a level of a first threshold or more, the active mode including a transmission of modulated data at the first communication device and the second communication device, the passive mode providing load modulated communication from the second communication device to the first communication device. When the first communication device receives an indication to start a communication of the active mode from the second communication device, the demodulating receives data at a level of a second threshold or higher, the second threshold being higher than the first threshold.