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New Robust Estimation/Detection Techniques With Applications to Wireless CDMA Communications
Final rept Aug 97-Sep 99
OHIO STATE UNIV COLUMBUS
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Current research into the development of receivers for wireless Code-Division Multiple-Access signals had focused on systems where perfect knowledge of communication parameters exists prior to the research funded by the grant in question. It is clear that such a scenario is unlikely as most parameters will be transmitted over the noisy wireless channel or will be estimated. While there had been work evaluating the impact of imperfect knowledge of the necessary parameters on previously derived receivers, there was yet to be research performed on the development of receivers that are insensitive to parameter estimate errors. The primary aim of the research was to investigate methods of introducing robustness into Direct-Sequence Code-Division Multiple-Access DS-CDMA receivers that exploit both some preliminary knowledge of parameter errors as well as the multiple access interference inherent to such multiuser systems. In addition, preliminary research on the novel area of spacetime block coding for DS-CDMA systems was also conducted. Transmit diversity coding across multiple transmit an- tennae is another method of increasing robustness and thus improving performance in DS-CDMA wireless channels. To date, there appears to be no work in this area that is specifically focused on designing spacetime block codes for DS-CDMA. There has been work devoted to applying pre- viously proposed narrowband codes to the wideband problem. By exploiting properties of the DS-CDMA signals, we have been able to improve performance.
APPROVED FOR PUBLIC RELEASE