Research On Indoor Relay And Key Components For Wireless Communication

With the increasing number of smart terminals,the demand for wireless communication is rapidly increasing,but the spectrum in low-frequency is unable to meet with the demand of bandwidth.Therefore,the mm-wave frequency will be used in the next-generation wireless communication.Comparing to microwave frequency,the available bandwidth in mm-wave is wider,but mm-wave frequency has a shorter wavelength and weaker diffracting and scattering capabilities,resulting in indoor communication shadows or blind zones inevitable in large-scale cities.In this dissertation,the research and design of indoor relay are studied to solve the problem of indoor communication shadows or blind zones and to improve the indoor communication Quality of Service(QoS).The main work can be summarized as follows:1.To cover indoor communication shadows or blind zones,a novel wireless relay combining with industrial glass is proposed.Unlike the conventional relay,the proposed relay takes the influence of glass into account.It overcomes the shielding effect of buildings and breaks through the limitation of mm-wave communication,which is helpful for the signal to coverage all of indoor areas and to ensure the QoS of indoor wireless communication.The relay approach is compatible with a plurality of duplex modes,which is helpful for different communication modes to be compatible and to decarese the operating cost of telecoms operators.2.A passive relay used for improving indoor coverage is proposed,it reduces the energy consumption and opearting cost.Compared with the traditional relay device,the passive relay does not need additional energy,which is good for the green communication and consists with the sustainable development.In addition,a passive relay unit based on substrate integrated waveguide(SIW)slot antenna is proposed,it can be used to cover different areas by different relay units and combinations.The proposed passive relay is low cost,easy to install and flexible to design,it can be used for different communication scenarios.3.A linear polarizated filtering antenna using SIW resonator and non-resonant slot is proposed to decrease the size and noise figure.By etching a co-plane waveguide(CPW)structure into the edge of the SIW cavity,two additional resonant frequencies are introduced,and thus the bandwidth is improved.Also,a hybrid electromagnetic coupling is realized by the CPW,which generates two radiating zeros at the upper and lower edges of the passband to suppress out-of-band clutter.The high-order mode of SIW cavity in the linear polarizated filtering antenna is excited by the non-resonant slot,it improves the bandwidth and generates an adjustable radiation zero to enhance the out-of-band rejection.Furthermore,a single-port SIW circularly polarized filtering antenna using SIW cavities and cross slots is proposed.4.A compact wideband filter for relay using dual-/multi-mode resonators and quarter wavelength resonators is proposed.By adding a perturbation structure,such as a high-impedance shorted stub or an open stub,to the conventional resonant,some resonant modes can be excited,and then the bandwidth can be improved without increasing the circuit size.There are two coupled paths in the filter,one of them is electrical coupling introduced by the parallel line and another one is magnetic coupling introduced by high impedance line.Therefore,a finite transmission zero is introduced at the upper and lower passband edges respectively,which improves the frequency selectivity.The proposed wideband filter has compact size,good in-band and out-of-band electrical characteristics,it can be used in the relay to improve the purification of spectrum.5.The tranditional SIW filter consists of multiple resonators has a large size,resulting in a bulky size when used in the relay.To solve the problem,a multi-path coupled narrow-band filter based on stacked SIW cavity is proposed.A series of second-order narrow-band filters are realized by making full use of the three-dimensional structure of the multilayer substrate.Since the coupling in different location of the SIW cavity are different,two coupling paths with electric coupling and magnetic coupling are realized by etching slots or hole in different location.It generates a transmission zero on the upper and lower stop bands respectively and improves the frequency selectivity.The proposed SIW narrowband filter is simple and easy for integration,which provides a compact filtering circuit and interconnection structure for the proposed relay.