Key Technique Study of Channel Evaluation in Adaptive Frequency Hopping Systems

An adaptive frequency hopping (AFH) scheme can increase the interference rejection capability of the frequency hopping system, which adopt digital signal processing technology, so it is proposed in military communication gradually. An AFH scheme is based on real time channel evaluations, which makes use of them to analyze and to evaluate the frequency status. A straightforward AFH scheme for duplex links is proposed and analyzed. In such a link, link quality measurements are fed back to the transmitter such that known interference (i.e., 'bad' frequencies) may be avoided according to the frequency selecting algorithm. The tradeoff between the amount of feedback information and link throughput as well as the impact of feedback reliability is important. The antijam property of the AFH scheme is very promising.