On estimation of protection parameters for unequal error protection distributed fountain codes in wireless relay networks

In many applications of wireless relay networks (WRNs), such as image and video systems, unequal error protection (UEP) among the transmission data from different source nodes is required. All the source nodes in a WRN with different protection requirements form multiple protection groups. In this paper, we focus on estimating the protection parameter, i.e., the protection weight, for each protection group. We first analyze the bit error rate (BER) upper bound of the UEP distributed fountain codes over Rayleigh fading channels for WRNs. Then based on the analysis results, we derive the approximate expression for the BER upper bound with protection weight as the variable. The derived approximate expression can be used to estimate the protection weights for the protection groups according to their various performance requirements. Finally, examples on the application of the approximate expression in estimating protection weights are given.