Research On Long-Range Propagation Characteristics Of E-Band Millimeter Wave

With the emergency of various innovative applications,people have evergrowing demands on high-speed,low-latency,and wide-covered communication data-rate.For most remote areas,the key to improving quality of services(Qo S)lies in high-speed backhaul system.E-band millimeter-wave(Mm-Wave),at the 71-76 GHz and 81-86 GHz frequency band,has been considered a candidate technology for building wireless backhaul.Due to the large bandwidth and relatively low atmospheric attenuation compared to other mmwave bands,E-band has the potential of providing tens of Gigabits-per-second(Gbps)data rates in long-range transmissions.Before wireless communication system designing,fully understanding the E-band channel characteristics and their impact on E-band signal propagation is very important.Therefore,it is necessary to produce E-band channel measurement on long-distance scenarios.Aiming for providing backhaul connectivity in remote areas where laying fiber optic cables is infeasible or extremely costly,we have studied and designed an E-band longrange channel measurement system that operates at 74 GHz center frequency.We evaluated the system’s channel measurement capabilities.This system supports a maximum signal bandwidth of 1 GHz and covers a transmited-side-to-received-side distance up to25 km.Using the system,several experiments were performed to study E-band longdistance propagation in different environments.In the paper,we introduce the E-band experimental system and report propagation measurements conducted across the lake and desert in the Qaidam Basin of Qinghai Province,China,and across the sea near Sanya Bay,China,all having line-of-sight(LOS)conditions and a link distance of around 12 km.Based on the measured data,we study propagation characteristics that are crucial for backhaul system design,including pathloss,fading,multipath effects and polarization properties.The results show an average of 0-0.7 d B/km path attenuation additional to freespace loss,which tends to increase with atmospheric humidity.All three environments favor vertically-polarized wave propagation,as it has significantly lower pathloss than horizontally-polarized,i.e.,1-7 d B.The cross-polarization ratios(XPR)were found to be relatively high,i.e.,11-23 d B.Severe fading effects were observed,especially in the 12-km across-sea link where signal variation can reach 10 d B in a short time.No significant multipath,e.g.,reflection on the lake or sea surface,was observed.All these indicate that E-band can be used for long-range backhaul and there is a potential of using polarized multiple-input multiple-output(MIMO)technologies to further boost data rates.However,when designing the link budget,researchers also should take meteorological factors of application scenarios and severe fading in channel into consideration.Appropriate power distribution for horizontal and vertical polarization should also be taken into account.Overall,the experimental research contributes to E-band propagation modeling and future system design.