"The ability to transmit data from a source to a destination reliably in the presence of adversarial intervention, such as jamming, is of paramount importance and concern," said lead author Tamer Basar.
According to Basar, the prototype described in the paper "captures scenarios that arise in many application areas, such as remote sensing systems, networked control systems, and cyber-physical systems".
For example, a sensor collects information over a period of time and transmits the data to a decision centre that must work to accurately process the original data. The data can become corrupted as it must be encoded prior to the decision centre and decoded afterwards. Time constraints and limited energy resources further complicate matters. To complicate issues even more, a jammer can stop everything by literally jamming the system with a gluttony of noise.
"The sensor, the encoder, and the decoder act in unison, toward a common goal, whereas a jammer operates in a way to counteract the actions of the first three," Basar said.
The researchers grouped the three pieces together, comprising one actor in the system, working to counter the actions of the jammer. By having all three pieces work as one, they simultaneously announce their policies regarding information.
It's the difference between communicating via a carrier pigeon or a phone. A person must tie a message to the pigeon's leg, the pigeon must travel, and the receiver must retrieve the message from the pigeon. Then the receiver must respond and repeat the process in reverse. The message could be lost or damaged at several points. If the same people picked up the phone, it's far more likely they could decide on a course of action together with minimal interference.
When the sensor, encoder, and decoder work together, they commit to their next actions together. They don't block the jammer altogether, but the jammer doesn't have the opportunity to interrupt the work and cause a substantial error as the actors communicate back and forth.
Called a Stackelberg feedback solution, this hierarchal manoeuvre allows the system to commit to processing information based on a set of pre-computable thresholds, which depends on time and the number of transmission opportunities left. The jammer is left out of consideration as the sensor, encoder, and decoder decide together what, how, and when to process.
While effective, the solution is currently limited to one channel. The researchers hope to change that.
"Our goal is to extend the model introduced in the paper to more complex systems, allowing for more general source processes, multiple sensors, multiple channels, and sensors that are equipped with an energy harvester that has the potential to replenish the sensor's used energy based on random availability of such resources - such as solar or wind power," concluded Basar.
