# Analysis of LTE-M Adjacent Channel Interference in Rail Transit
### Related Literature  
Many studies on interference have been conducted in recent years, mainly including interference between 4G and 5G systems [9; 10; 11; 12], 4G and 4G communication systems [13; 14; 15], satellite service ground station systems and 5G systems [16; 17; 18; 19; 20], and LTE and broadcasting systems [21; 22; 23]. In 5G new radio (NR) frequency-division duplexing (FDD) systems that coexist with LTE systems, simulation study is executed to explore the required isolation degree under common and non-common station of the base station [9; 10; 11]. The results show that non-common station scenarios require a higher isolation degree. On the basis of [9; 10; 11], the authors of [12] investigated the interference coexistence of LTE and NR systems using dynamic spectrum sharing (DSS) technology and discovered that LTE neighbor cells have a stronger impact on NR cells. The deterministic analysis method is utilized to investigate coexistence interference between LTE FDD and Time Division Long Term Evolution (TD-LTE) systems, as well as between TD-LTE and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) systems in [13; 14; 15]. The main emphasis is devoted towards the isolation of the coexistence of base stations under common address, common coverage, and the safe distance between base stations. In [16; 17; 18; 19; 20], the minimum coupling loss method is used to evaluate the interference of adjacent channels between different service earth stations, 5G base stations, and user equipment. The results show that, the source's interference power should be lowered, and more frequency separation needs to be used to assure system coexistence. In [21; 22; 23], the authors focus on the analysis of ACI between the LTE mobile systems and Digital Video Broadcasting-Terrestrial (DVB-T) systems, with the main conclusion that increasing the separation distance between LTE BS and DVB-T reduces interference between adjacent channels, and the minimum separation distance decreases with the presence of a guard band.  
The purpose of a coexistence study is to enable the compatibility between adjacent channel systems through the interference analysis. If the coexistence of the systems cannot be ensured using the methods described in the literature, a range of approaches are utilized to reduce system interference and ensure coexistence. In [24; 25], a novel approach for suppressing ACI induced by RF front-end non-linearity is described, which involves digital frequency domain filtering of adjacent signals to remove out-of-band emissions from the received signal. In [26], the power control scheme is proposed to mitigate the impact of ACI on vehicle-to-vehicle broadcast communication. In [27], a measurement data-driven machine learning paradigm is proposed to set power control parameters for optimal uplink interference management of a LTE system. In [28], the impact of co-channel interference on a Global System for Mobile Communications-Railway (GSM-R) system is evaluated for the signal received power threshold that affects the performance of a GSM-R network. In [29], an optimizing model is proposed to maximize the receiving SINR to suppress the jamming in railway wireless communication systems. As for the abnormal train-ground communication caused by complex environmental factors, electric arc dynamics, and electromagnetic noise along the subway, [PERSON] et al.'s study [30] shows that the main source is the transient electromagnetic interference generated by the sliding contact between catenary and pantograph, which has little impact on the communication system. The authors of [31] propose a method to improve the anti-electromagnetic interference ability of the entire railway vehicle from the grounding and wiring aspects. In [32; 33], the authors proposed that signal interference can be solved by establishing a shielding network or adding a filter to the base station.