A Research On Dynamic Spectrum Access Methods And Its Implementation In Wideband Communications Systems

With the heat wave of intelligent terminal equipments’ s spreading,authorized band resources under 3GHz have been basically saturated while open band resources have been overloaded for long.As a result,people turn to reuse the authorized band.A lot of research on hierarchical spectrum access have been made,in which underlay spectrum sharing technique needs more attention,especially in the case of changeable Interference Margin.This paper focuses on the condition of variable Interference Margin and proposes a Selective Underlay Spectrum Sharing(SUSS)method.The performances are examined through simulations and its implementation is also given in the end.Firstly we derives the Soft-decision Spectrally Modulated Spectrally Encode(SD-SMSE)framework based on the frame structure of Spectrally Modulated Spectrally Encode(SMSE)and presents the designing steps of different multi-carrier waveforms,then we make a review on traditional interference temperature model.Secondly,the Overlay non-continuous orthogonal frequency division multiplexing(NC-OFDM)waveform and the Code Division Multiple Access(CDMA)waveform are generated through SD-SMSE,and performances of Overlay waveforms are examined as well.Thirdly,this paper studies the affects between different users with fixed Interference Margin,analyzes and optimizes the performances of underlay secondary users.It also finds the perfect ratio of the power of primary and secondary users.Then we propose a SUSS method to save certain primary user in the case of changeable Interference Margin,its feasibility is proved through simulation analysis.Finally,this paper builds an experimental hardware platform to complete the implementation of the proposed SUSS access method validation.