US Patent 7783316 Public safety communications network using asymmetric receive/transmit channels

A public safety communications network uses asymmetric channels for receiving requests for data from a mobile client over a narrowband land mobile radio system (LMRS) channel and delivering wideband data over a digital television (DTV) network channel to a DTV datacast receiver with the mobile client. An emergency operations center connected to the LMRS receives and processes the data requests and forwards the requested data. DTV network stations have a data multiplex insertion system for inserting the requested data into a DTV signal. The DTV network may be a public television network. An addressing system identifies unique mobile client addresses and unique mobile client group addresses and selects a DTV transmitter for delivering response messages in accordance with the addresses. A forward error correction (FEC) regulation system is used in transmitting requested data with FEC strength regulated as a function of historical bit-error-rate or receive power for a geographical location.