Research On Interference-carrier-based Communication System And Detection Technology

Wideband high-power interference is a major problem faced by wireless communication system.With the application of small-scale computing equipment widely used,requirements of low energy and high-frequency spectrum utilization efficiency are put forward for communication systems.Therefore,how to realize signal antiinterference and improve spectrum utilization efficiency under the condition of low energy becomes an urgent problem to be solved.We introduce an interference-carrier-based communication system to actively resist interference,which uses ambient backscatter technology to send communication signals with interference signal as carrier.However,the traditional ambient backscatter system transmits the binary phase shift keying modulation signals,and detection algorithms are proposed to detect these on-off keying signals.The problem of low data transmission rate and high bit error rate exist in this system.Therefore,the aim of the paper is to propose signal detection algorithms that can be applied to higher-order modulation signals with lower bit error rate.Firstly,we introduce the research background and significance of the ICBC system.We calculate the channel capacity and analyzes the feasibility of the system.We introduce the ambient backscatter communication technology used in the system to transmit communication signals.The technology includes the structure of the backscatter and the traditional signal detection algorithm at the receiver.Through simulating the detection algorithm and analyzing the results,we summarize the research focus of the ICBC system is signal detection algorithm with lower bit error rate and higher data transmission rate.Secondly we study the signal detection algorithm based on the expectation maximum algorithm.According to the huge difference between the communication signal and the background interference in signal transmitting rate,the average energy of the received signal in a communication signal symbol frame can be used to detect the signal.We use EM algorithm to estimate the parameters of the mixed distribution model,and calculate the optimal threshold.We calculate the average energy of the received signal and classify them into clusters to detected the communication signal.When the communication signal is phase modulated,the channel selection method based on minimum bit error rate is added to reduce the bit error rate of the received signal.However,this method would increase the frame error rate of the signal,which also affects the normal communication of the ICBC system.We study the ICBC system with multiple antennas for both the transmitter and the receiver.When different signal detection methods are used,we select the best channel to receive signal with different measurement to reduce the bit error rate.According to our analysis and the simulation results,we find that the more antennas we use,the system is more complex and have lower bit error rate.Then,a signal detection algorithm based on ICA is proposed.The received signal is separated into the signal of the direct link and the signal of the backscatter link.For the backscatter link,the one-to-one correspondence between the signal phase and the constellation is established through the preamble.We propose a synchronization algorithm for the relative delay between the signal of the two links.What's more,the communication scheme for when there is no interference signal in the system is designed,with adding the background signal detection module.By using the signal detection algorithm based on ICA,the complexity of the system is increasing,and the bit error rate and frame error rate are reduced.