Measurements And Modeling Of Indoor Full-duplex Self-interference Channel

Wireless radios today are generally half-duplex, i.e. time division duplex or frequency division duplex. Half-duplex communications perform not good in spectrum efficiency. With more and more radio spectrum occupied by new communication technologies, the scarcity of radio spectrum has become increasingly prominent. Recently, great breakthrough has been made in Co-Time Co-Frequency Full Duplex(CCFD), which enables transmitting and receiving signals in one channel simultaneously. Theoretically, communication systems using CCFD will save half the spectrum, so that to ease the strain on hard demands of radio spectrum resources.A technical difficulty of CCFD implementation is to eliminate the high-power self-interference over the local transmitter to the receiver. Mastering knowledge of self-interference channel is beneficial to suppressing self-interference power to the lowest; however, research in this area is still scarce.In view of this, this dissertation proposes a measurement scheme for indoor full-duplex self-interference channel, builds a frequency-domain channel measurement platform, and then obtains a large number of original data. Channel parameters are extracted from these data to help establish channel model. The main contents include:Firstly, common channel measurement methods and indoor models are studied for indoor radio channel. This dissertation explores principles of Periodic Pulse Detection Method, Spread Spectrum Sliding Correlation Method and Frequency-Domain Scanning Method, and analyzes their advantages and disadvantages. Meantime, the dissertation researches in indoor channel models, like logarithmic distance path loss model, Ericsson multiple breakpoints model. The work above lays the foundation for indoor full-duplex self-interference channel measurements and modeling.Secondly, this dissertation presents a channel measurement solution and masters key channel measurement techniques during actual measurements, according to the features of indoor full-duplex self-interference channel. In this dissertation, Frequency-Domain Scanning Method is selected, antenna spacing ranges from 0.05 m to 1.5m, 256 measurement points are picked and distributed randomly in the laboratory, and 3328 sets of data are obtained.Thirdly, by processing original data in frequency domain, the path loss equation is extracted, and then a large-scale channel model established. Original data needs pretreatment, which includes windowing in frequency domain. After pretreatment, path loss value at every point is calculated; the path loss equation is extracted, and then a large-scale channel model is established. Results show path loss coefficient in antenna near field in 1.515, and path loss coefficient in antenna far field is 1.856.Fourthly, On basis of inverse Chirp z transformation, this dissertation processes channel power delay profile from the time domain, extracts the rms delay spread parameter and tries to establish a multi-path delay channel model. By setting noise power threshold and adjusting time zero position, data fitting indicates that rms delay spread distribution obeys a lognormal segmentation model.This dissertation presents an indoor full-duplex self-interference channel model, this model provides a reference for grasping self-interference channel characteristics and self-inference signal cancelling technology. The above work will promote the development and application of full-duplex technology.