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

Namseok CHANG  Gye-Tae GIL  Joonhyuk KANG  Gangyoul YU  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.2   pp.633-636
Publication Date: 2008/02/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.2.633
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
OFDM,  space-time block code,  space-frequency block code,  

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In this letter, a switched transmission technique is presented that can provide the orthogonal frequency division multiplexing (OFDM) systems with additional diversity gain. The space-time block coding (STBC) and space-frequency block coding (SFBC) are considered for the transmission of the OFDM signals. A proper coding scheme is selected based on the estimated normalized delay spread and normalized Doppler spread. The selection criterion is derived empirically. It is shown through computer simulations that the proposed switching technique can improve the bit error rate (BER) performance of an OFDM system when the corresponding wireless channel has some time variation of time selectivity as well as frequency selectivity.