A problem that manifests in wireless networks where some of the nodes are unaware of each other. Specifically, it can occur when all nodes are within signal range of the network's access point, but some are out of range of each other. Because traditional networking protocols rely on a node listening to network traffic and only transmitting data when the network is momentarily idle, it is possible that two nodes unaware of each other will attempt to transmit simultaneously. The addition of handshaking to the protocols is a partial cure, but no complete solution has yet been found. Compare exposed terminal problem.