On the Performance of ST-FSK Systems in the Presence of Relative Delay

Combining the advantages of space-time block codes and frequency-shift keying, space-time frequency-shift keying (ST-FSK), which does not require any channel state information at the transmitter and the receiver, can adopt the noncoherent ML detector under the Rayleigh fading channels. The paper deduces the noncoherent ML decision metric at the receiver with the knowledge of relative delay, and for the different SNRs it discusses the performance of binary and quaternary ST-FSK systems in the presence of distinct relative delay. Both theoretical analysis and simulation results show that, (1) lower SNR lessens the relative delay sensitivity of ST-FSK systems, but the relative delay sensitivity limits the systems performance for higher SNR; (2) the sensitivity makes little difference between binary and quaternary ST-FSK systems.