Research On Channel Adaptation Ability And Papr Reduction Methods Of Tdcs

Transform Domain Communication System (TDCS) is a new type of wireless communication system. It can generates the basis function without interference frequency in transform domain, the transmission waveform of TDCS(basis function)and the interference signal in channel has the orthogonal features, so TDCS has a strong ability to suppress interference; At the same time, TDCS can use interval frequency resources for information transmission. So TDCS will be widely used in anti-jamming communications of military and cognitive radio communications of civil.In wireless communication environments, the fading characteristics of channel(multi-path transmission unsatisfactory amplitude fading and phase fading),the different electromagnetic spectrum of sender and receiver will seriously impact the performance of the system. Also, because of the multi-carrier characteristics that are similar to Orthogonal Frequency Division Multiplexing (OFDM) signals, Peak-to-Average Power Ratio (PAPR) of TDCS is too large to raise the requirements on the power amplifier. For these two problems, this paper will carry out the following research work.First of all, the basic theory of TDCS and the basic principle of its related technologies are introduced; the system diagram and mathematical models are given. In order to study exactly, a system simulation platform is established.Secondly, the channel adaptable performance of TDCS is analyzed. From the two aspects of theoretical and simulation, we analyze the impact of gaussian white noise,narrow-band interference,multi-path interference,fading and the different electromagnetic spectrum of sender and receiver on TDCS.In order to reduce the impact of the different electromagnetic spectrum of sender and receiver on system performance, two solutions have been proposed: the improved TDCS based on a total band of communication theory and the improved TDCS based on spectral characteristics of the receiver. It proves that these improved TDCS are effective and feasible.Taking into account the PAPR of TDCS signal is too large, we discuss its characteristics. By combining the PAPR suppression methods of OFDM and the technical characteristics of TDCS, we propose the technology of PAPR reduction in TDCS based on clipping and verify its technical performance.