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Time domain spreading and frequency domain maximal ratio combining reception for frequency diversity enhancement in single carrier UWB communication systems

Single carrier systems with frequency domain equalization have attracted much interest for high data rate communications. In this paper frequency diversity is investigated for single carrier ultra-wideband systems by employing simple maximal ratio combining reception in frequency domain with complex quadratic spreading sequences. Since ultra-wideband channels exhibit dense multipaths and strong frequency selectivity, analysis and simulation results indicate the proposed system can gain significant performance improvement over traditional single carrier frequency domain equalization systems. Compared with multicarrier systems, like orthogonal frequency-division multiplexing and multi-carrier code division multiple access, receiver complexity is reduced greatly. To accommodate multiuser communication, block spreading is further introduced. Combined with block spreading, multi-user interference free receiver can be realized for the proposed system.