Sensor Network Collision Avoidance via Pseudo-Random Time Slots
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Solution Overview
Problem
Remote sensing networks face interference and false readings due to proximity of multiple transmitters, which existing techniques like CSMA and cellular data networks are not well-suited to handle, especially in low-cost, rugged, and long-lasting sensor devices.
Innovation Solution
A method and system that use random number generation and pseudo-random processes to adjust transmission times, allowing multiple transmitters to access a shared communication medium without collisions, by generating and transmitting random numbers and using time offsets to synchronize data message transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple transmitters are deployed in close proximity to extend sensor network coverage, then the area monitored by the sensor network increases, but signal interference and false readings increase
Solution Approach 1:
The patent segments the shared communication medium into distinct time slots for different transmitters. Each transmitter is assigned specific time windows during which it can transmit data, preventing simultaneous transmissions that would cause interference. This time-division approach allows multiple transmitters to operate in close proximity without signal collision.
Solution Approach 2:
The patent implements preliminary carrier sensing before each transmission opportunity. Transmitters check the communication medium to determine if it is currently occupied before attempting to transmit data. This preliminary detection action prevents transmissions that would cause interference with ongoing communications from other transmitters.
2Reliability
If traditional multiple access techniques like CSMA are implemented, then collision avoidance is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables each low-cost transmitter to autonomously determine its transmission schedule based on predetermined time slot assignments and local carrier sensing. Each device independently manages its own transmissions without requiring complex centralized coordination or sophisticated electronics, allowing the use of simple, battery-powered transmitters.
3Reliability
If transmitters use continuous monitoring and sophisticated collision avoidance protocols, then transmission reliability improves, but power consumption increases
Solution Approach 1:
The patent implements periodic transmission opportunities at predetermined time slots rather than continuous monitoring and transmission attempts. Transmitters wake at scheduled intervals to check for carrier availability and transmit data if the medium is clear, then return to sleep mode. This periodic approach maintains transmission reliability while dramatically reducing average power consumption compared to continuous operation.
Data Source
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AI summary
A method enables a radio receiver to distinguish sensor probes supplying data to the receiver over a long period of time. The method includes each probe generating a random number sent to the receiver to identify the probe. Each probe and the receiver also uses a pseudo-random process to identify a time of transmission for each probe. The pseudo-random process helps keep the transmission times for the probes separate in the presence of oscillator drift. If a transmission collision occurs, the receiver ignores all probes in the collision and waits until the pseudo-random process separates the probe transmissions.