The Maximum Length of a Line with PoE Repeaters

Relevance: Modern intra-facility information and telecommunication systems include subsystems utilizing Ethernet technology. These include IP telephony, Wi-Fi access points, video surveillance systems, access control and management systems, smart environment sensor systems comprising Internet of Things sensors and actuators, etc. Power for many subsystems can be supplied centrally from Ethernet switches and injectors using Power over Ethernet (PoE) technology. PoE repeaters or extenders are used to increase the distance to terminal devices.

Problem Statement. When designing an intra-facility communication line whose segments are interconnected via PoE repeaters, it is necessary to determine its maximum length. A methodology for calculating the maximum length of a line with PoE repeaters is not presented in known sources.

Objective: To develop an engineering method for determining the maximum length of an intra-facility communication line using PoE repeaters. The input parameters are the loop resistance of the twisted pair, the source voltage, the self-consumption power of the repeater, and the power consumption of the powered terminal device. Individual segments of such a structure are considered identical, and constraints from the IEEE 802.3af and IEEE 802.3at specifications apply regarding linear path parameters and active equipment used.

Novelty: A mathematical model of serially connected sections of an intra-facility communication line, interconnected via PoE repeaters, has been developed.

Practical Significance: The limitations of PoE repeaters are determined, and the influence of their self-consumption power on the maximum line length is shown. The developed calculation method can be used for designing components of intra-facility information and telecommunication systems. The proposed model, calculation methodology, and its investigation can be used in the educational process at SPbSUT and other telecommunications universities.

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