The Interaction between Communication, Computation, and Control Sekhar Tatikonda, Yale University Coordination and computation over wireless networks Traditionally the design has been separated Projects: Role of feedback in communication Control with communication constraints Distributed detection and compression in sensor networks Advanced iterative decoding techniques

Feedback in Communication Traditional information theory does not treat latency Examples: - streaming video - communication in the control loop Acks and channel measurements can increase capacity Output feedback can decrease latency: - Error decays at a double exponential rate over fading channels Goals: - develop efficient feedback codes - practical issues: noisy feedback, what do we feedback

Control with Communication Constraints Controls: x := Ax + Bu + w Consider communication between sensors and controller and between controller and actuators The communication requirements for stability: C > log (det A) Similar results for other performance objectives Goals: - Communication coordination between distributed controllers plant controller

Distributed Processing in Sensor Networks Sensor measurements are correlated and localized Low power constraints Minimize bits not messages - computation much cheaper than communication Routing based on both correlation and geography Slepian-Wolf coding

Iterative Decoding Techniques LDPC decoding based on the iterative sum-product algorithm Distributed computation based on message passing This algorithm be applied to distributed estimation tasks as well What if messages are corrupted? Goals: - develop fault tolerant message passing schemes - develop feedback codes p1 p2 b1 b2 b3 b4