Propagation Measurements and Modelling for Multiband Communications on Tactical VHF Channels

Large scale characterization of the channel average power-delay properties is considered based on quasi-simultaneous mobile propagation measurements at the lower VHF frequencies 37.8, 57.0, and 77.5 MHz. The measurements were conducted in three different environments using vehicle height antennas at both the fixed and mobile terminals, and are therefore considered applicable to tactical networking scenarios likely to be encountered in practice. Model parameters which statistically describe the individual and joint behaviour of power-delay taps as a function of transmission range are estimated from the measured data by least squares regression. Power biases incurred as a result of low power levels at some delays, i.e. below the measurement system multipath sensitivity in certain locations, are mitigated by a statistical imputation algorithm. The results illustrate the impact of transmitter-receiver (Tx-Rx) range and obstacle density in the propagation environment on transmission loss and impulse response shape.