Author_Institution :
Dept. of Radio Commun. Syst., R. Inst. of Technol., Stockholm, Sweden
Abstract :
To improve the performance of frequency-hopping systems on interference-limited HF channels, so-called adaptive frequency-hopping (AFH), which uses an adaptively selected pool of the “best” hopping-frequencies for communication, has been proposed. We extend the adaptivity of the AFH scheme by adjusting the transmitted power on each channel individually and by adaptively changing the number Na of active channels that are selected to the pool. Fewer active channels (up to a certain point) give improved communication performance since the used channels, on the average, are less interfered. However, by decreasing Na, the protection against hostile detection is decreased. This trade-off between communication and LPI (low probability of intercept) performance with respect to Na is shown. Our analysis shows that the codeword error rate is minimized when about 20% of the channels are selected to the active pool, and that the LPI protection against the two tested hostile detectors, as expected, improves for larger Na. Generally, the hostile detectors require less received signal-to-interference ratio than the legal AFH receiver to obtain acceptable performance. For the parameters we have chosen in our duel simulation, the results indicate that the LPI performance seems to be more sensitive to the choice of active channel pool size than the communication performance
Keywords :
adaptive control; coding errors; error statistics; frequency hop communication; military communication; power control; radio spectrum management; radiofrequency interference; spread spectrum communication; telecommunication channels; telecommunication control; AFH scheme; HF communications; LPI FH system; active channel pool size; active channel selection; active channels; adaptive frequency-hopping; codeword error rate; frequency-hopping systems; hostile detection; interference-limited HF channels; power control; signal-to-interference ratio; transmitted power; Detectors; Frequency shift keying; Performance analysis; Power control; Protection; RF signals; Radio communication; Radiofrequency interference; Sensor systems; Signal analysis;