Elimination of Data Identification Problem for Data-Dependent Superimposed Training
Date Issued
2015
Date
2015
Author(s)
Chan, Kuei-Cheng
Abstract
For channel estimation without data-induced interference, the data-dependent superimposed training (DDST) scheme is proposed in single carrier (SC) system by adding a data-dependent sequence before transmission. In DDST scheme, the data-induced interference which occurs during channel estimation is eliminated at the expense of data distortion. Unfortunately, this distortion causes a data identification problem (DIP), where data sequence can’t be uniquely determined at the receiver end. Although DIP has been widely investigated in the literature, an effective solution for preventing its occurrence has yet to be proposed. Accordingly, in contrast to previous studies which explained the occurrence of DIP only for a special case, the present study explores the theoretical foundations for DIP in DDST schemes using a signal sub-space technique and derives the general conditions under which DIP occurs. It is shown mathematically that the occurrence of DIP is related to the adopted modulation scheme and the pilot pattern. Therefore, a pilot design criterion which theoretically eliminates DIP is proposed. In addition, the precoded SC system using DDST scheme is further proposed in this study. It is proved that the proposed precoded SC can eliminate the DIP and keep the advantages of conventional DDST scheme in SC system by carefully designing the precoding matrix. Furthermore, a low complexity detection method for the precoded SC system is also proposed. The proposed detection method can reduce the searching number to reduce computational complexity at the receiver end obviously. Finally, simulation results are conducted to verify that the proposed schemes successfully eliminate the DIP in DDST scheme and have the low peak-to-power ratio property as in SC system. Finally, the application of DDST scheme on cooperative relaying network is introduced. By using the proposed structure, secondary user can relay primary user’s information and transmit its own signal simultaneously. Simulation results demonstrated that the proposed scheme works even when the direct link is unavailable.
Subjects
Single carrier system
data-dependent superimposed training
pilot design
channel estimation
precoding
peak-to-average power ratio
cooperative network
secondary user
Type
thesis