Design of Distributed Network-Channel Codes for Wireless Sensor Networks

In this paper, we use extrinsic information transfer (EXIT) chart to design irregular low density generator matrix (LDGM) codes to form distributed network-channel codes in a wireless sensor network. We formulate the code design and code search as a linear programming (LP) problem. We consider a real-time wireless network with randomly changeable fading channels, resulting in link failures and time varying network topology. In forming such a dynamic network, the connected number of source nodes at each relay needs to satisfy previously obtained degree distributions. At the same time, the channel quality of the data links connecting the source nodes and relay nodes has to be considered. We propose the optimal relaying selection scheme to present such a solution. Simulation results of the proposed irregular codes show that a considerable performance improvement can be achieved in the waterfall region compared with the existing codes.