The Effectiveness of Random MFSK (Multiple Frequency-Shift-Keying) Frequency-Hopping ECCM Radios against Worst-Case Partial-Band Noise Jamming
Abstract
The system analyzed for bit error rate (BER) performance is frequency-hopped (FH) multiple frequency-shift-keying (MFSK) wherein the M symbol frequency assignments are independently and randomly chosen on each hop, and the information transmission is repeated L times (L-hop diversity) for a soft symbol decision. This FH/RMFSK system is intended to counter systematic follow-on jamming. The reported analysis is of the system's BER in worst-case partial-band noise jamming (WCPBNJ). To be effective, the receiver must employ nonlinear combining of the L hops; several hop weighting schemes are evaluated with different assumptions about available real-time information on relative powers of signal, noise, and jamming. These include adaptive gain control, clipping, hard-decision, and self-normalizing (nonparametric) schemes. It is shown that a simple, self-normalizing receiver, using no jamming state information or measurements, can perform nearly as well as one using a priori values of received noise-plus-jamming powers for adaptive gain control. It is also demonstrated that a hard-decision receiver (majority logic decoding of the L repetitions) achieves an ECCM effect and is viable if the SNR is high. Although the BER varies with jammer power in much the same way as for conventional FH/MFSK (given the parameters M, L, and the unjammed SNR), including a diversity gain for high SNR, FH/RMFSK in general is more vulnerable to WCPBNJ for M greater than 2. Therefore, it is concluded that implementation of effective diversity schemes is feasible, and that for a binary system the additional complexity of random hopping can be assessed to the additional protection gained against follow-on jamming.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1986
- Accession Number
- ADA172929
Entities
People
- J. Lee
- L. E. Miller
- L. J. Cowles
- R. H. French