Serially concatenated convolutional coding for frequency-hopped PSK in partial-band jamming

This paper presents results on the performance of the serial concatenation of a convolutional code and differentially encoded phase-shift keying (PSK) in the presence of partial-band white-noise jamming. Frequency hopping is used to combat the effects of the jamming. We assume that the carrier phase is constant over a hop, but varies randomly from hop to hop. An expanded trellis-based demodulator, which assumes a quantized phase offset, is used to provide nearly coherent performance. Iterative demodulation and decoding provides excellent performance at relatively low E_b/N₀. A fixed block length is considered to limit the delay and processing requirements. We show that, consequently, there is a trade-off between nearly coherent reception and antijam (AJ) protection. That is, more symbols per hop provide better performance when the phase offset is unknown, but having more hops per code block enables better protection from jamming.