Time domain fractional diversity method in single-carrier ultra-wideband systems
LI Bohua1,2, PEI Yukui2,3,4
1. Department of Electronic Engineering, Tsinghua University, Beijing 100084, China; 2. Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing 100084, China; 3. Tsinghua Space Center, Tsinghua University, Beijing 100084, China; 4. Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
Abstract：Long delays and dense paths seriously affect the performance of single-carrier ultra-wideband (SC-UWB) systems. Traditional channel equalization methods are not sufficient for these systems and the traditional diversity methods are very complex with excessive data redundancy. This paper presents a joint design method for single-carrier frequency domain equalization (SC-FDE) with time domain fractional diversity to improve the complex multipath characteristics of ultra-wideband (UWB) systems. At the transmitting end, this method uses one diversity branch for two or more information branches. At the receiving end, the system first performs the SC-FDE and then combines operations based on the posterior probabilities combination or the low complexity equal gain combination of the equalization results obtained by the information branches and the diversity branch. The system then finally recovers the original information. This time domain fractional diversity method has outstanding performance with a single antenna and low redundancy. The system needs only 1.5 or less applications of the diversity mode and obtains excellent diversity gains. Simulations show that this scheme has a 3 dB diversity gain over the SC-FDE scheme for a bit error rate of 10-3.
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