An $\Omega(D\log (N/D))$ Lower Bound for Broadcast in Radio Networks

We show that for any randomized broadcast protocol for radio networks, there exists a network in which the expected time to broadcast a message is $\Omega(D\log (N/D))$, where D is the diameter of the network and N is the number of nodes. This implies a tight lower bound of $\Omega(D\log N)$ for any $D \le N^{1-\varepsilon}$, where $\varepsilon > 0$ is any constant.