Research On Key Techniques Of Anti-Interference Receivers For Ultra-Wideband Radio

With the rapid development of consumer electronics techniques,the demand for shortrange high-speed wireless communication is increasing.Ultra-Wideband(UWB)radio technique is widely used in personal area network,intelligent transportation system,wireless sensor networks,radio frequency identification,imaging applications and other fields because of its strong anti-interference ability,high transmission rate,large system capacity,low transmission power,good confidentiality,portability and low cost.Federal Communications Commission only limits the radiation power of UWB itself.However,there are a great number of conventional radio signals in the huge signal bandwidth of UWB.The power spectral density of these radio signals is much higher than that of UWB itself,and the particularity and diversity of signal propagation will bring great challenges to the design of UWB receivers.On the one hand,due to multipath propagation,the signals received by UWB receivers inevitably contain multipath interference(MPI);on the other hand,UWB systems share the same frequency band with other narrowband systems at low power,and narrowband systems will interfere with or even block UWB receivers,which greatly reduces the performance of UWB communication systems.In the thesis,the suppression of MPI and Narrowband Interference(NBI)in UWB radio system is studied.The main research contains:(1)The basic theory of UWB radio technique is discussed.Firstly,the UWB pulse waveform and modulation mode at the transmitter are expounded.Secondly,the mathematical expression of UWB channel model parameters(IEEE 802.15.3a and IEEE 802.15.4a channel model)is given,and the relevant simulation analysis is carried out.Thirdly,the basic principle of Rake receiver is discussed,including the selection and merging strategy of multipath components.Finally,the receiving performance of the UWB signal in the ordinary receiver affected by NBI and the Rake receiver containing NBI and MPI is discussed.(2)In order to solve the problem of strong correlation between adjacent multipath components when Rake receiver is used in UWB signals,a DC-PRake receiver method based on decorrelation algorithm is proposed.Before merging the multipath components of each branch,the decorrelation operation is performed on each branch to avoid the influence of the correlation on subsequent processing.At the same time,the effectiveness of the proposed DCPRake receiver is verified in the IEEE 802.15.4a standard CM1 channel model(LOS)and CM4 channel model(NLOS).The simulation results show that compared with the conventional Rake receiver,the DC-PRake receiver improves the anti-MPI ability of UWB signals.(3)UWB signals occupy a large signal bandwidth and inevitably share spectrum resources with a great number of conventional radio signals.The power spectral density of these traditional radio signals is usually much higher than that of UWB radio signals.There is no doubt that these conventional radio signals will cause serious interference with low-power UWB radio signals.In order to effectively reduce the influence of NBI and MPI on the receiving performance,a SS-Rake receiving scheme based on morphological component analysis of Compressed Sensing(CS)is proposed.A signal separation module is added to the front end of Rake receiver,and the problem of signal separation is transformed into the problem of solving underdetermined equations by using the sparsity of UWB signal and NBI signal.The optimization objective is solved by orthogonal matching pursuit algorithm,and UWB signal and NBI signal are separated to remove NBI.Only the useful signal is sent to the traditional Rake receiving module for subsequent processing.To verify the performance of the proposed SS-Rake receiver,computer simulations are performed under IEEE 802.15.4a standard CM1 channel model and CM4 channel model.Simulation results show that the proposed SS-Rake receiver can effectively resist the influence of strong NBI on the receiver performance compared with the traditional Rake receiver under the condition of strong NBI and can meet the stable reception of UWB signals in the scenario of coexistence of NBI and MPI.