One or more devices, systems, and/or methods involve communicating with a node using a wireless transmission; receiving a node transmission responsive to the wireless transmission; and transmitting a wireless reference transmission responsive to the node transmission. The wireless reference transmission is transmitted aperiodically and responsive to a node transmission received from the node. Additionally, one or more devices, systems, and/or methods involve receiving, from a node, a wireless transmission; transmitting, to the node, a node transmission about the wireless transmission; and receiving a wireless reference transmission from the node responsive to the node transmission.