Research On E-band Channel Measurements And Channel Characteristics In Urban Environments

With the development of communication systems towards 6G,the frequency of wireless mobile communication has increased,the coverage of base stations has decreased,and the number of base stations has increased.The backhaul network used to connect base stations with the core network has also become increasingly complex.If we insist on using traditional fiber optic transmission,the installation cost is high and deployment is difficult.Wireless backhaul is easy to deploy and has a lower cost,making it an alternative solution for urban backhaul networks.E-band millimeter waves(71-76 GHz and 81-86GHz)have an extremely large bandwidth of 10 GHz,so they can meet the requirements of high-speed and large-capacity wireless transmission.At the same time,the propagation environment of electromagnetic waves in urban areas is complex,and both pedestrians and vehicles can affect the propagation of electromagnetic waves.Therefore,before designing the urban backhaul system,it is necessary to fully understand the characteristics of the E-band millimeter wave propagation channel in the urban environment.In order to study the E-band millimeter wave propagation characteristics of urban backhaul scenes,this paper conducted measurement experiments in two typical urban echo scenarios:(1)pole station(2)O2I.In the pole station scenario,the transceiver distance is400m-700 m and the antenna installation height is 2.75m? In the O2 I scenario,the distance between the transceiver is 760 m,the antenna installation height is 25 m,and both transmitter and receiver adopt horn antennas.The channel characteristics of path loss,fading,and multipath phenomena in two scenarios are analyzed based on the measured experimental data.At the same time,we estimate the backhaul rate of the single polarization SISO of the measurement system without encoding.The measurement results show that the passing of vehicles and pedestrians in the pole station scenario can cause serious fading phenomena.Considering that the LOS path is not blocked during the measurement process,the reason for this phenomenon is vehicles and pedestrians cause or affect multipath propagation.Electromagnetic waves from multiple paths generate phase lengthening or canceling interference at the RX.Due to the high antenna height,there is no multipath time variation impact in the O2 I scenario on the roof,thus,there is no obvious fading phenomenon,and the measured path loss is very close to the free space propagation loss.Therefore,when designing an E-band echo system in urban environments,it is important to consider the antenna mounting height to avoid excessive fading.When the transmitting signal rate is 600 MBaud,the modulation method capable of reliable transmission is 16 QAM,so backhaul rate for single polarization SISO transmission in this system is 2.4Gbps.If the MIMO technology is used to achieve polarization multiplexing and spatial multiplexing,the backhaul rate can be increased to tens of Gbps,which can meet the high-speed and high-capacity backhaul requirements of urban environments.This article analyzed the E-band channel characteristics in two typical backhaul scenarios in urban environments and verifies the feasibility of achieving high-speed and highcapacity backhaul in urban areas with E-band.This helps to understand the E-band millimeter wave propagation characteristics of O2 I scenarios and pole scenarios,and ultimately contributes to the design of wireless backhaul systems in urban environments.