Research On Interference Mitigation For MB-OFDM UWB

UWB(Ultra Wideband)technology as one of the important technologies in future short-range wireless communications has been widespread concerned in many countries.Since the UWB signals use a very wide frequency band,it is sure that there are some narrowband(Compared with UWB)systems exist in the UWB frequency band to share spectrum.The problem of UWB coexistence with narrowband system has been the most important reason which restricts the development of UWB technology.The current mainstream's form of UWB including multi-band OFDM(MB-OFDM UWB) and direct sequence spread spectrum(DS-UWB).As MB-OFDM UWB has many advantages in interference mitigation with narrowband system,the interference mitigation technology for MB-OFDM UWB has been the focus of research in UWB areas.On the background of Detect And Avoid technology must be used in UWB,this paper propose a new interference detection method for MB-OFDM UWB,and give some improve suggestion of interference avoid technology for MB-OFDM UWB,then verify the feasibility of the new interference detection method,and the superiority of the improved interference avoid method.The research on DAA technology is still in the initial stage,there are still some issues to be resolved:The current MB-OFDM UWB detect technology is mainly based on power detection,using power detection UWB system need to add hardware,and the detect bandwidth can not be flexibly changed.This paper propose an interference detection method based on comparison of symbol energy,this method is simple to achieve,and it can flexible detect the narrowband interference which is unknown,also it can estimated bandwidth of interference signal.The current MB-OFDM UWB interference avoid technology is mainly use subcarrier nulling technology,but it must combining with sub-carrier sideband suppression technology to achieve optimum power attenuation.The method still has room to be improved.This paper propose an improved sub-carrier sideband suppression method,which can effective improve the effect of power attenuation.Finally,I set up a simulation platform of MB-OFDM UWB communication system by using MATLAB,to verify the feasibility of the new interference detection method and the improved method of interference avoid.The simulation results show that:the new interference detection method can accurately detect the existence of narrow-band interference,and estimated the bandwidth of narrow-band interference;the improved method of interference avoid has a better power suppression than the traditional method.