Detection of SOQPSK in a space-time coded system with arrival time differences

This paper presents an algorithm suitable for space-time codes (STC) in power-limited, high rate data links subject to shadowing due to antenna placement (such as aeronautical telemetry channels). Two difficulties arise when using STC on such channels-they employ offset modulations (such as shaped offset QPSK or SOQPSK) due to the need for a constant envelope waveform and the spacing between multiple transmit antennas can lead to arrival time differences among the received signals. The algorithm presented in this paper deals with these two difficulties and provides a solution to this situation. The performance of the algorithm is simulated and presented, and it is shown that the use of STC along with the algorithm presented here eliminates the occurence of data dropouts which result when multiple antennas are used at the transmitter (without STC).