Abstract—This paper analyzes the influence of time-varyingcyclic delay diversity (TV-CDD) on the channel fadingcorrelation properties in orthogonal frequency division multiplexing(OFDM) based systems. The underlying transmitdiversity technique CDD only increases the frequencydiversity at the receiver. In contrast, TV-CDD introducesadditionally time diversity which can be exploited withoutthe need of additional complexity at the receiver. Thispaper gives investigations regarding the resulting channelcharacteristics from TV-CDD and the impact on the systemperformance. Due to the increased frequency and timeselectivity, an unintended higher channel estimation effort ispossible. Therefore, we analyze the impact of choice of themaximum cyclic delay. We show that the resulting channelfor TV-CDD can be seen as an uncorrelated Rayleighfading channel (except for the first sub-carrier) for a largemaximum cyclic delay. Furthermore, analysis and simulationresults demonstrate a feasible choice of small time-varyingcyclic delays for guaranteeing the standard conformabilityof the TV-CDD technique at the receiver without significantperformance degradations.

Cite: Simon Plass, Armin Dammann, Gerd Richter, and Martin Bossert , "Channel Correlation Properties in OFDM by using Time-Varying Cyclic Delay Diversity," Journal of Communications, vol. 3, no.3, July, pp.19-26, 2008.