A wireless communication system having portable communication devices capable of establishing direct terminal-to-terminal communication through another terminal without having a fixed base station.

Terminal resistance method: to improve the quality of the communication on the 485 + and 485 - of the last 485 devices with a termination resistor of 120 ohms.

Terminal based on TETRA digital trunking mobile communication system could send and receive status and short data service message, and achieve navigation and location through short data service.