Spectral occupancy at VHF: implications for frequency-agile cognitive radios

摘要: Frequency-agile cognitive radio is a potential solu- tion to the problem of inefficient use spectrum in 30- 300 MHz (VHF) range. This especially attractive if networks based on this technology can operate left unused by existing users, as opposed being allocated new through refarming. paper presents preliminary survey band large U.S. city, with goal quantifying spectral occupancy and thereby gaining some insight into feasibility approach. A comparable measurement 25-90 rural environment also presented, for comparison. In urban measurement, it found that sufficient probably available: example, estimated approximately 80% 30-60 essentially free signals within about 7 dB environmental noise limit at 30 kHz resolution. However, these measurements are limited duration, spatial sampling, temporal density, Requirements more comprehensive campaign proposed.