The 220 MHz ITS spectral allocation: potential, pitfalls, and applications

In 1992 five narrowband frequency pairs in the 220-222 MHz band were allocated for intelligent transportation system (ITS) applications. These allocations are capable of supporting low-rate digital communications (4-30 kb/s). This article examines potential applications within the ITS program which can effectively use the low data rate that these allocations can provide. An overview of the narrowband wireless data communication challenges and the communication theoretic techniques likely to be employed on high-performance modems is provided. An experimental system was built, and preliminary field test results are presented which demonstrate that spectral efficiencies in excess of 3 b/s/Hz are achievable in practical modems.