Soft prioritized network coding in multiple access relay networks

We propose soft prioritized network coding techniques that provide a variable quality of service (QoS) to different nodes in multiple access relay networks. The basic idea is to exclude the low priority nodes in the network encoder when their channel gains towards the destination are below a threshold or above a threshold, and vary the threshold to provide a variable QoS. The proposed techniques can provide a soft-level prioritized service to different nodes depending on their assistance needs. They are a natural generalization of current prioritized network coding techniques which can provide only a hard-level (fixed) prioritized service. We derive the probability of decoding error for the prioritized and non-prioritized nodes in Rayleigh flat fading channel with path loss and additive white Gaussian noise taking into account the channel estimation error.