A system for transmitting data over a communication network operating in an Ethernet or serial communication mode, where an Ethernet or serial cable is replaced by radios transmitting over an over-the-air radio link. The system includes computer processors that receive the data and assemble that data into smaller OTA data packets for delivery across the link and operating protocols that provide collision avoidance of OTA packets transmitted in an overlapping manner by radios on opposite sides of the over-the-air link. In a preferred mode the system operates in the 902-928 MHz ISM band, and the data being transmitted over distances much greater than for 2.4 GHz transmission.