Research On Separation Method Of Alias Signal In Vibration Communication

Near Field Communication(NFC)is an emerging technology that allows electronic devices to transmit data in a contactless point-to-point manner.NFC technology has low power consumption,low cost,high speed and miniaturization,so it is widely used in many fields such as electronic communication,industry and agriculture.Currently implemented NFCbased applications include authentication,electronic payment and data exchange.These applications are convenient for people's daily lives and become a new type of business in the field of mobile communications.However,the existing short-range wireless communication technology has a huge security risk.Researchers have found that even if the communication distance of NFC technology is very close,eavesdroppers can successfully decode NFC transmissions in close range,resulting in leakage of user privacy.In response to this problem,the researchers proposed a new type of short-range wireless communication technology-vibration communication technology.As the name suggests,vibration communication technology means that two devices transmit data with the vibration characteristics of the object as a medium under the condition of mutual contact.Since the vibration communication technology uses the physical contact between the transceiver devices as the communication condition,the vibration communication technology has higher security than the conventional NFC technology.However,the existing vibration communication technologies all have the problem of low bit rate,and it is obviously no longer applicable today when the data rate is rapidly developed.In order to solve this problem,this paper proposes whether it is possible to transmit multiple vibration signals in parallel,so that the vibration transmission efficiency is doubled.The difficulty in realizing this idea is how to separate and separately decode the aliased multipath vibration signals.In this paper,we design a Vi Sep(Vibration Separation System)method for aliasing vibration signals suitable for mobile devices.The transmitting end of Vi Sep uses a vibration motor that is currently widely used in mobile phones as a transmitter,and its receiving end uses an accelerometer as a receiver.Vi Sep mainly consists of three modules: noise filtering module,attenuation compensation module and separation algorithm module.Among them,the separation algorithm module is the core module of Vi Sep.In the noise filtering module,Vi Sep filters out the interference caused by noise interference in the environment and hardware defects of the vibration motor of the system.Among them,the interference of environmental noise is filtered by Butterworth filtering technology,and the interference caused by hardware defects is filtered by anti-noise sequence.In the attenuation compensation module,Vi Sep compensates for the attenuation problem of the vibration signal in the transmission path to avoid inputting the wrong reception signal to the separation algorithm module,resulting in the separation of the wrong source signal.In the separation algorithm module,since the two simultaneously transmitted vibration signals are nonlinearly coupled to cause frequency aliasing,the separation algorithm first needs to decompose the detected aliased signals to construct a new signal to solve a mixture from only receiving.Separating and recovering the original two-way signal in the stacked signal is a mathematically unsolvable problem because it is similar to the number of unknowns being greater than the number of equations.After constructing a new signal,Vi Sep performs decoupling by finding the decoupling signal and matrix by eigenvalue decomposition of the autocorrelation function of the new signal.Finally,Vi Sep performs joint diagonalization of high-order cumulants to estimate the source signal.We have experimentally verified the performance of Vi Sep in different scenarios.The experimental results show that Vi Sep can minimize the influence of nonlinear interference,and Vi Sep can show an average accuracy of 98.6% under the influence of different influence factors.The experimental results verify the validity and accuracy of Vi Sep,and prove that Vi Sep can accurately estimate the source signal with a low bit error rate.