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A communication network is called a radio network if its nodes exchange messages in the following restricted way. First, a send operation performed by a node delivers copies of the same message to all directly reachable nodes. Secondly, a node can successfully receive an incoming message only if exactly one of its neighbors sent a message in that step. It is this semantics of how ports at nodes send and receive messages that defines the networks rather than the fact that only radio waves are used as a medium of communication; but if that is the case then just a single frequency is used. We discuss algorithmic aspects of exchanging information in such networks, concentrating on distributed randomized protocols. Specific problems and solutions depend a lot on the topology of the underlying reachability graph and how much the nodes know about it. In single-hop networks each pair of nodes can communicate directly. This kind of networks is also known as the multiple access channel. Popular

this paper we extend the prioritized conflict resolution algorithm to be dynamic, so during execution the algorithm is able to accept newly arrived messages. The dynamic model is more realistic since messages (packets) continuously arrive at network nodes and wait for transmission. Our dynamic algorithm still ensures that the expected running time as well as the expected waiting time of (both new and old) messages are both small. Our algorithm is suitable for fully-connected broadcast networks with or without the collision detection (CD) feature, i.e., whether transmission will be discontinued due to detected collision. We also present a new tighter analysis of our static PCR algorithm.