Check-Sum Aided MAP Detection of Relay Misbehavior in Wireless Network Coding

We propose check-sum aided maximum a posteriori (MAP) approach in detecting the misbehaving relay that injects false data, drops valid data, and/or adds channel errors into the network encoder in noisy multiple access relay networks. The MAP detection is optimal in the sense of minimizing the probability of incorrect detection (false alarm and misdetection), while requiring no transmission overhead. The accuracy of misbehavior detection is improved by having a check node to overhear a set of source nodes and send a check-sum of overheard data to the detector. We derive the probability of false alarm and misdetection in Rayleigh fading noisy channels, and analyze the improvement of detection as a function of transmission overhead (rate) and signal-to-noise ratio.