On Space-Time Coded ARTM CPM to Solve the Two-Antenna Problem

Abstract

The space-time block code approach to solving the two-antenna problem is extended to ARTM CPM. The space-time block code is a block-based extension of the Alamouti space-time block code used in space-time coded SOQPSK-TG systems. A demodulator/decoder is described and analyzed both mathematically and in computer simulation. Without complexity reducing techniques, the decoder requires the Viterbi Algorithm operating on a trellis with 4,194,304 states. Complexity reduction techniques are applied to reduce the number of states to 256. Complexity reduction is accomplished at the cost of loss in detection efficiency that is a function of the differential delay between the space-time coded ARTM CPM signals transmitted from the two transmit antennas on the airborne test article.