Adaptive Switching Technique for Space-Time/Frequency Coded OFDM Systems

Abstract

I thi leer, a witched tramo techique i preeted tht c provid th orthogoal frequecy divo mutpexng OFDM sytem wth atonal dverty gan. The pace-tme blck cdig STBC d spc-frequcy block coding SFBC r cosidrd for the trasmo of the OFDM sigals. A proper codig schme is slctd based on the estimated normalized delay spread and normalized Doler spread. The selection criterion is derived empiricay. It is shown troug computer smulatons that the proposed swtchng tchniqu can improv the bit eor rate BER performance of an OFDM system when the corresponding wireless channel has some time variation of time selectivity as well as frequency selectivity.

A Simple Adaptive Switching Scheme between STBC-OFDM and SFBC-OFDM Systems

“…Since STBC-OFDM and SFBC-OFDM are robust against frequency-and time-selective fading channel, respectively, the technique of adaptively switching between STBC-OFDM and SFBC-OFDM is expected to improve the BER performance over a continuously varying channel, but few researches associated with switching technique between STBC-OFDM and SFBC-OFDM have been conducted. In [4], a switching criterion between STBC-OFDM and SFBC-OFDM was found from empirical searching by comparing the BER curves of STBC-OFDM and SFBC-OFDM. Since this approach is based on empirical data, however, the proposed criterion may not be applicable for general cases.…”