Long-term Effect of Thermal Variation on the Performance of Ethernet Cabling Dielectrics. Florence Akinnuoye 1 , Hugh Sasse 1 , Paul Cave 2 , Steve Prescott 3 , and Alistair Duffy 1 1 School of Engineering and Sustainable Development De Montfort University, Leicester, LE1 9BH, United Kingdom florence.akinnuoye@dmu.ac.uk, hgs@dmu.ac.uk, PaulCa@mayflex.com, steve.prescott1@btopenworld.com,apd@dmu.ac.uk 2 Excel Networking. Excel House, Junction 6 Industrial Park, Electric Avenue. Birmingham. B6 7JJ. 3 2 The Ridings. Whittle-le-Woods, Chorley. Lancashire. PR6 7QH Abstract Currently, remote powering over the Ethernet (including PoE, PoE+, etc.) has emerged as a cost-effective option to power networked devices using balanced twisted pair cabling. Power delivery through Ethernet cables has numerous benefits including space saving and, of course, the ‘green’ benefit of using fewer natural resources. However, this raises several questions: could a combination of the transmission of high power and consequent increased ambient (local) temperature affect the performance of the cable dielectrics? How far would the change in the dielectric property affect cable performance, including throughput and Ethernet signal integrity? The previous study presented at the IWCS Cable Connectivity Conference in 2016 assessed the effect of thermal cycling on some generic dielectric samples based on the Cavity Perturbation Method of the ASTM D2520-13 standard. Some permanent changes to the dielectric constant of the generic samples were reported. This study seeks to investigate those observed phenomena further. The dielectric constant of different insulation types used in Ethernet cabling was examined at a room temperature to establish performance at 1GHz, 2.4GHz and 5GHz. Then, at 60 0 C to observe the effect of an increase in temperature on the performance of the dielectrics across the three frequencies. Moreover, Foamed-Skin HDPE was thermally cycled between the room temperature and 60 0 C to study the effect of thermal variation on its dielectric constant. The last study cycled the Foamed-Skin HDPE up to 90 0 C to observe both the transient and permanent changes in the value of the dielectric constant. The results of the baseline measurements support the insulation potential of the dielectric materials. Furthermore, it was found that increase in temperature has effects on the dielectric constant of all the dielectrics evaluated from the first heating cycle. Besides, thermal cycling showed a remarkable non-reversible modification in the dielectric constant of the Foam-Skin HDPE at 60 0 C. However, when the temperature was increased to 90 0 C, there were irreversible changes (permanent change) in the dielectric constant of the Foamed-Skin HDPE during the cooling of the material. The study further established the marked effect of an increase in ambient temperature on the physical and rheological behaviour of dielectric materials. With previous changes noted in physical and the rheological properties of the Ethernet cables as a response to temperature increase, this study suggests further works on the long-term heating and its direct effects on Ethernet signal integrity. Keywords: Dielectric constant, Degradation, Heating, 5G, IoT, PoE/PoE+, Power, Temperature, Gigabit, and Speed. 1.0 Introduction Global mobile networking technology has advanced rapidly in the past decade. The technology is now moving towards the era of 5G networks. The interest in 5G has grown mainly from the Internet of Things (IoT) which will enable many business opportunities [1]. However, while the transition to 5G has its own set of benefits, its effect on the architecture of the internet presents a significant challenge for adoption, mass rollout and management. With 5G Technology, it is likely that there will be an enormous increase in the demand for many online services [1]. This will mean that the number of devices that will be connected to the internet will increase compared to the numbers in the existing 4G network [1]. With many devices and streams of activity data from mobile users at the periphery, near the centre of a system, data rates must be increased to serve the hubs and the switches that are located in the outer parts of the networks. Key requirements in 5G Technology include providing high-speed low-latency access to the Internet for the networked devices to support services like High Definition video and maintaining the current cost and energy consumption rates while effectively increasing the devices that connect to the networks [2]. This is because as the data speeds grow, the energy requirements for the devices to process the data also grow. According to [1], 5G backhaul should be designed to be adaptive in such a way that it accommodates the varying demand for data speeds from different networks and this is where Ethernet backhauls play a major role. The use of copper wired backhauls offers sufficient throughput [3]. This increases the importance of the wired backhaul in the global wireless networks as the growing demand for faster network services will need to be serviced through faster backhauling. Although, as recommended in [1], small cells should be used as data offloading points to prevent the backhaul from being overloaded with requests for high-speed data transfers. In this case, small cells will play a major role in establishing the link between ultra-dense networks (UDN) and the backhaul for lower latency communications [1]. Another objective of using small cells is to make sure that power consumption does not become a limiting factor in the backhaul and this is where Power over Ethernet Technologies (PoE) play pivotal roles. Power over Ethernet is a Technology that allows electrical power to be transferred concurrently with data on the same Ethernet cable without the need for a separate electrical outlet [4]. Depending on the application requirements, different power levels can be transmitted through the cable to the end devices [5]. The adoption of PoE Technology in the 5G networks will enable flexibility of device placement. However, the main challenge is being able to provide high electrical power and high throughput data concurrently on the same Ethernet cable while maintaining Ethernet signal integrity.