We present our initial findings in the investigation of an adaptive protocol for relaying of information in tactical packet-radio networks. Our protocol employs fountain codes to facilitate a relaying scheme involving two relays for improved throughput. In addition, the protocol adapts the modulation format and error-control code for each packet transmission in response to the time-varying propagation loss in the channel. The adaptation is carried out with the help of simple statistics that can be easily derived from the decoder. I. INTRODUCTIONWe investigate a scenario in which a file must be sent from a source to a destination in a distributed tactical packet radio network. All nodes in the network are halfduplex packet radios. The file is divided into a set of information packets, and the transfer of the file occurs by means of a sequence of packet transmissions. The source and destination are not connected by a reliable radio link, so some form of packet relaying is required.In such situations, it is common to use intermediate radios for relaying packets from the source to the destination. We focus our attention on a situation in which two relays are available to forward packets from the source to the destination. A conventional store-andforward relaying scheme would normally select the single relay that provides the best route to the destination. With normal procedures, the use of multiple relay nodes produces duplicate packets and may cause packet collisions or scheduling conflicts at the destination. Our suggested protocol employs fountain coding in a way that does not create any duplicate packets, yet it permits a second relay node to take part in the file transfer. We show that our approach provides a significant increase in throughput over packet relaying by a single node.Our approach also uses adaptive modulation and channel coding to mitigate the effects of fading on the radio links. The control information needed for adaptive transmission is derived from a simple statistic that is computed in each radio's receiver as it demodulates and decodes each incoming packet. This control information is employed for packet-by-packet adaptation of the channel code and the modulation on each radio link.