ITS wireless narrowband land mobile data communications

Five narrowband frequency pairs in the 220-222 MHz land mobile band have been allocated for applications in intelligent transportation systems (ITS). Low rate data communications in the range of 4 to 30 kbps can be supported on these 4 kHz channels. This paper describes an ongoing project to design, construct, and field test a high performance wireless modem architecture for application in the ITS spectrum allocation. In an effort to achieve high bandwidth efficiency, the modem architecture employs recent advances in transmitter diversity, pilot symbol assisted modulation, frame and frequency synchronization, and forward error control coding. Field testing of this modem architecture has demonstrated that bandwidth efficiencies in excess of 3 bps/Mz are achievable at bit error probabilities of around 10(-5). The experimental system which has been built serves as an effective testbed for further advances in narrowband wireless communications and for ITS application development.