hat receives a signal to wait a random length of time before retransmission. If it receives another copy of the same signal while it is waiting, it does not retransmit the signal. The "flooding" technique is clearly an inefficient way for Radio A to send a message to Radio B. It results in excessive transmission by other terminals and few messages can be sent across the network at the same time. However, it may be useful to broadcast a short emergency message to many terminals. In order for Radio A to more efficiently transmit a message to Radio B, it needs to know the connectivity of radios in the network SO that it can route a message through the network. This means that somehow all radios must learn about how the radios in the network are connected to each other. Thus there are two problems: 1. How do radios learn of their connectivity in the network? 2. When network connectivity is known, how should a radio transmitter route messages through the network? One approach is to assume there is a common network key that is used to generate a common pseudorandom sequence for the purpose of handling network overhead traffic. This sequence is used by the radios to learn how the radio network is connected. Here the flooding technique can be utilized with one radio sending a "route-finding" packet and each other radio adding its own identification to the packet before retransmitting it. Then whenever a radio receives such a signal it learns the sequence of radios that transmit- ted it. With enough such retransmissions each radio can obtain some knowl- edge of how the radio network is connected. For a time-varying mobile radio network this route-finding flooding technique is repeated periodically as the network changes. Given a network connection table stored in memory, a radio can now transmit a message to any other radio by first selecting a route through the network based on this knowledge [8]-[27]. Now rather than use the com- mon network key, the radio can route a message to the next radio in a mul- tihop route by t