Hidden Node Detection in Cellular Unlicensed Bands
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Solution Overview
Problem
In communication networks operating on unlicensed bands, the hidden node problem causes interference due to neighboring nodes, leading to poor user experience, as transmitters are unaware of interference conditions at the receiver, resulting in failed data transmissions.
Innovation Solution
A system and method that dynamically manage the hidden node issue by having a receiving node assess the channel status for interference and communicate this status to the transmitting node, allowing the system to determine if the channel is clear for transmission, and if not, to wait and re-attempt communication after a specified time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmitter transmits data when the channel appears clear, then transmission efficiency is improved, but interference from hidden nodes causes transmission failures
Solution Approach 1:
The receiving node provides feedback to the transmitter about the actual channel conditions at the receiver side. When the receiver detects interference from hidden nodes, it sends an interrupt signal to the transmitter, causing the transmitter to stop transmission. This feedback mechanism ensures that transmission decisions are based on actual receiver-side conditions rather than just transmitter-side channel assessment.
2Reliability
If the transmitter waits for receiver confirmation before transmitting, then transmission reliability is improved, but transmission delay increases
Solution Approach 1:
The system performs preliminary channel assessment at the transmitter side before actual data transmission. The transmitter checks if the channel is clear and prepares to transmit, but actually starts transmission only after receiving confirmation from the receiver. This preliminary action allows the system to quickly assess channel conditions while maintaining reliability through receiver confirmation.
3Reliability
If RTS/CTS handshaking is implemented to detect hidden nodes, then transmission reliability is improved, but system complexity and overhead increase
Solution Approach 1:
The patent extracts the essential function of hidden node detection from the complex RTS/CTS handshaking protocol. Instead of implementing the full RTS/CTS sequence, the system uses a simplified approach where the receiver monitors for interference and sends interrupt signals to the transmitter when hidden node interference is detected. This extracts only the necessary reliability-improving function while eliminating unnecessary protocol complexity.
Data Source
AI summary
Method and system for managing hidden node problem in a communication network. A receiving node in the system, upon receiving a data transmission request from at least one transmitting node, dynamically checks status of the channel between the transmitting node and the receiving node. If the channel is found to be clear for transmission, then the receiving node sends a message that indicates that the channel is clear, to the transmitting node, and the transmitting node starts transmitting the data. Upon receiving a message from the receiving node that the channel is not clear for transmission, then the transmitting node waits for a particular time period and attempts the connection again.