| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 105 === LTE-Advanced proposed carrier aggregation techniques which utilizes aggregated multiple carriers to increase the bandwidth and achieve high data rate. In practice, LTE-Advanced uplink systems adopt single carrier frequency division multiple access (SC-FDMA) which has a low Peak to Average Power Ratio (PAPR) characteristic. In order to lower the bit error rate, we used the Discrete Wavelet Transform(DWT) to replace conventional Discrete Fourier Transform this precoding operation in SC-FDMA. The system we used which named Wavelet SC-FDMA(W-SC-FDMA). In this thesis, we proposed a new system structure let W-SC-FDMA with Carrier Aggregation.
However, not only the conventional SC-FDMA but also the W-SC-FDMA system’s low PAPR characteristic will lose as the number of aggregated carriers are increasing. Therefore, we adopt the Partial Selected Mapping (PSLM) technique to reduce PAPR and discussed how to design the PSLM in Wavelet Transform structure. PAPR will reduce by multiplying phase factor which represents as the Side Information (SI) at the receiver. The receiver must have received the side information in order to recover the signal’s phase but as the SI were transmitted in system would decrease data rate because of the extra SI data.
To avoid this situation, our structure adopts Physical Uplink Shared Channel (PUSCH), its time slot structure includes reference symbol which can be used for channel estimation. Therefore, we use the reference symbol to substitute the SI to achieve without directly sending SI. And we also use reference symbol’s characteristics to estimate the phase factor and recover the signal’s phase by estimated phase. In this thesis, we chose five kinds of phase estimate methods and discussed in imperfect channel estimation in order to observe what would change in BER. Furthermore, as previous section we mentioned the W-SC-FDMA system, the new system structure with CA and lower PAPR methods; we will simulate the BER performance of new structure in different channel models, equalizers, different aggregation bandwidth and different number of aggregated carriers. Further, we compared the PAPR’s variation in original and new structure.
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