Otsetova-Dudin, Ekaterina2020-11-232020-11-2320191339-5130http://drepo.uniza.sk/handle/hdluniza/367Mobile cellular networks are an indispensable part of modern life, where the need for customer satisfaction in the use of many different services by consumers is constantly increasing. The requirements for higher transmission speed, lossless transmission, reliability, efficiency, low latency, mass connectivity, guarantee of high Quality of Service criteria are repeatedly increasing. All this requires the continuous development of the used technologies as well as the introduction of new generations of networks. Handover mechanism is extremely important in cellular network because of the cellular architecture employed to maximize spectrum utilization. To ensure the quality of service in wireless cellular networks, the report proposes the use of a Horizontal Handoff Priority Scheme. Simulation experiments have been carried out, the probability parameters of the scheme have been evaluated and the probabilities of losses occurrence have been classified as rare events. The proposed material are various algorithms and techniques for the implementation of Vertical and Horizontal Handoff in 3G, 4G and fifth-generation networks to provide the required QoS for mobile users with Ultra-High Definition.enhttp://creativecommons.org/licenses/by/4.0/Handoff3G4G and 5GQuality of ServiceArticlehttps://doi.org/10.26552/tac.C.2019.2.6