This paper studies a network coding scheme that exploits a cooperative diversity and adaptation to variant link states for reliable networks. We propose a scheme, adaptive rate network coding (ARNC), to change the number of transmission in relay nodes according to channel states over fading channels by matching network graphs with rateless code graphs, raptor codes. In ARNC scheme, a relay transmits potentially limitless coded symbols to a destination until receiving an ACK for a successful decoding, so the destination can recover the message from the network with high probability.