This paper proposes a shortened transmit technique using repetitive transmission in the frequency domain. For a single antenna OFDM system, a hybrid selection combining and maximum ratio receive combining technique was proposed for better performance, but it is effective only for high Eb/N0 region. This paper suggests a new method of removing zeros generated from repetitive transmission and of reconfiguring repetitive transmit time domain signals for maximum ratio receive combining at the receiver, by which we can obtain better performance comparing to SISO case at the expense of a few algebraic calculations and FFT/IFFT executions.

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This paper proposes a hybrid shortened transmission/ expanding reception technique and single carrier modulation with a zero forcing frequency domain equalizer when a single carrier modulation with a guard period is transmitted. Regarding single carrier transmission data as shortened OFDM transmission data allows an expanding reception technique and a maximum ratio to be combined in the receiver, and a parallel single carrier modulation with a frequency domain equalizer is used as a secondary receiver. The proposed hybrid scheme does not have channel codec but simulation results show it has better performances in comparison with the coded OFDM algorithm at the expense of algebraic calculations and FFT executions.

This paper proposes an alternate time-switched multiplexed space-time block coding technique for single-carrier modulation systems. Alternate time-switched scheme of transmitting time-domain zeros gives an additional frequency domain diversity at the expense of switches. Simulation results show that alternate time-switched scheme has advantages for single-carrier modulation as well as OFDM case compared to the multiplexed STBC without alternate switching. Keywords-maximal ratio combining (MRC); multiplexed space-time block coding (STBC); SCM; switchI.2

This paper proposes an alternate time-switched space-frequency block coding transmission technique for orthogonal frequency division modulation systems. There are two antennas in the transmitter but it still has only a baseband and RF and a switch that alternates between the antennas at every symbol timing. Alternating transmit symbols result in zeros that make maximal ratio receive combining possible in the receiver. Simulation results show that it provides better performance than the traditional algorithm at the expense of one additional antenna.