Data Transmission with FSK Permutation Modulation

The technique of iV-ary frequency modulation in which energy is transmitted on 1 out of N frequencies to convey log2 N bits of information per character has been known for some years. 1,2 David Slepian3 has recently described a general modulation system, permutation modulation, which is applied here to a multifrequency modulation scheme in which energy is transmitted simultaneously on M frequencies out of N, thus conveying log2 ^^ bits of information per character. Binary and one out of N FSK modulation are special cases of FSK permutation modulation. Such a transmission scheme is basically not new; it has been used for many years for transmitting decimal digits, address, and other supervisory information in the telephone plant. This work was motivated by a requirement to compare the information transmission capability of these alphabets. However, the application analyzed here is, in fact, different because we assume a baud synchronous matched filter receiver with a mutually orthogonal set of signals. The channel is assumed to be nonfading, frequency flat, with white gaussian additive noise. 1131