A method, comprising: forming coalitions of clusters of distributed data carriers, at least some of said data carriers including batteryless passive data carriers, said batteryless passive data carriers including passive RFID tags and/or acoustical tags; for each of said clusters, identifying a bridge data carrier that is capable to link with a bridge data carrier of another of said clusters; and enabling communication between batteryless passive data carriers of the clusters, wherein enabling communication between batteryless passive data carriers of the clusters includes: providing a carrier wave that can be backscattered; modulating the backscattered carrier wave with a first of said batteryless passive data carriers to generate an interrogation signal; and modulating the backscattered carrier wave with a second of said batteryless passive data carriers to generate a return signal in response to the interrogation signal, wherein the first of said batteryless passive data carrier initiates modulation of the backscattered carrier wave by: receiving power from the carrier wave; monitoring for a query signal associated with the carrier wave for a period of time; if the query signal is not detected after expiration of the period of time, generating and sending the interrogation signal to query the second of said data carriers; and if the query signal is detected prior to expiration of the period of time, responding to the query signal. forming coalitions of clusters of distributed data carriers, at least some of said data carriers including batteryless passive data carriers, said batteryless passive data carriers including passive RFID tags and/or acoustical tags; for each of said clusters, identifying a bridge data carrier that is capable to link with a bridge data carrier of another of said clusters; and enabling communication between batteryless passive data carriers of the clusters, wherein enabling communication between batteryless passive data carriers of the clusters includes: providing a carrier wave that can be backscattered; modulating the backscattered carrier wave with a first of said batteryless passive data carriers to generate an interrogation signal; and modulating the backscattered carrier wave with a second of said batteryless passive data carriers to generate a return signal in response to the interrogation signal, providing a carrier wave that can be backscattered; modulating the backscattered carrier wave with a first of said batteryless passive data carriers to generate an interrogation signal; and modulating the backscattered carrier wave with a second of said batteryless passive data carriers to generate a return signal in response to the interrogation signal, wherein the first of said batteryless passive data carrier initiates modulation of the backscattered carrier wave by: receiving power from the carrier wave; monitoring for a query signal associated with the carrier wave for a period of time; if the query signal is not detected after expiration of the period of time, generating and sending the interrogation signal to query the second of said data carriers; and if the query signal is detected prior to expiration of the period of time, responding to the query signal. receiving power from the carrier wave; monitoring for a query signal associated with the carrier wave for a period of time; if the query signal is not detected after expiration of the period of time, generating and sending the interrogation signal to query the second of said data carriers; and if the query signal is detected prior to expiration of the period of time, responding to the query signal.