Mobile Communication Impacts Analysis On The Beidou RDSS Service In 2.5 GHz Band

Beidou and 5G systems are important national-level basic projects.Beidou’s Radio Determination Satellite Service（RDSS）provides a unique service compared with other Global Navigation Satellite System（GNSS）.The working RDSS frequency is close to 5G,and the received power is far less than 5G.Thus,RDSS is vulnerable to interference from5G and loses normal function.The paper highlights that with the expansion of urban areas and an increase in the network model complexity,Beidou users have been increasingly likely to encounter interference from different 5G cellular networks,which could result in large uncertainty.In order to ensure Beidou RDSS for a long time and high precision of the normal operation,the coexistence problem between RDSS and mobile communication systems in adjacent band must be fully considered.We focus on a series of problems about the interference between 5G system and Beidou RDSS system:1)The basic theory is the core evaluation model of the Adjacent Channel Interference Ratio（ACIR）.Three critical factors,the 5G system,the signal design,and the receiver of RDSS are extracted and considered under the rule of ACIR.We obtained the safe distance making the two systems coexist by the deterministic analysis method and used the method of Monte Carlo system simulation to analyze the effects on Carrier-to-Noise power spectral density ratio（CN₀）,positioning and communication of RDSS user due to 5G adjacent interference.2)We analyze the signal structure of Beidou RDSS system and the spectrum characteristics of receiver filter.Three different types of Radio Frequency（RF）front-ends are designed,and their performance in suppressing adjacent frequency interference is analyzed under actual signal conditions.3)Modeling and analysis for aggregate interference using Poisson Hard Core Process（PHCP）mode,and coexistence analysis using stochastic geometry and providing coexistence criteria in different cases.4)Under the full consideration of Doppler frequency shift,Beidou users’moving speed,service base station switching and other influencing factors,we systematically analyze the changes of interference of Beidou users in the process of crossing the 5G cell-networks,and obtain the relationship between the CN₀-Loss and the moving speed of Beidou user.Aiming at the problem of adjacent frequency interference between systems encountered in actual deployment,we discuss the coexistence conditions to protect Beidou satellite navigation system from adjacent frequency interference of other systems,and put forward a reasonable protection strategy for interference coexistence.It provides support and suggestions for relevant departments to formulate relevant protection policies and plan the parameter design of communication devices in advance.Through this research,we summarize the exact scope of adjacent frequency impact from two aspects of 5G and RDSS systems.Suggestions on how to enhance the electromagnetic protection ability are made for RDSS receivers.The research in this paper is of great significance for the compatibility and coexistence of Beidou system and 5G system.