Scheme On Nonlinearity Of High Power Amplifier In Non-contiguous Orthogonal Frequency Division Multiplexing Based Cognitive Radio

In recent years,although techonologies of wireless communication has been developing rapidly,it can not meet the increasing demands,the primary reason is that the frequency spectrum is scarce. On the other hand,according to the research result of the FCC, the allocated frequency resource of wireless communication is not busy in different degree in both time and space,which leads to waste of spectrum resource. NC-OFDM based CR has innovated the traditional OFDM, it can detect spectrum hole, then transmit data,meanwhile it can reduce the interference of PU(Primary User) to the SU(Secondary User).It is well known to all that HPA is necessary to wireless communication both base station and user equipment.NC-OFDM model and some research was done in this thesis, in order to get a reasonable and efficient method.three key aspects was researched.firstly, for the disadvantages of the PAPR and Sidelobe,a joint scheme(MCS-SLM) was proposed.through simulation,the results show that the joint scheme can reduce PAPR and Sidelobe.for example,when IBO=4,the Sidelobe is5dB lower and so is CCDF of PAPR;2)as for the nonlinearity of HPA, a Digital Pre-distorted method was proposed,simulations show that the characters of the HPA such as AM/AM,linearity degree,constellation and so on have better performances;3)the system gets more complex because of MCS-SLM and DPD,the efficiency of HPA also gets lower,so at the receiver, Compress Sense was carried out. Scheme results show that when the SNR is smaller, the innovation is not obvious;when the SNR is bigger,the innovation is obvious.when the overload of the HPA is4.5dB, the SNR of outrage capacity has4.6dB gain.when the conditions are the same,SIMO has better performaces than SI SO.