The fifth generation (5G) mobile network is becoming more widespread in order to provide consumers with hitherto unattainable services and data transfer speeds. In order to provide an adequate response to the exponential growth of data traffic in the cellular network, operators use an infrastructure in which both macro and small cells are present. The first uses the classic (macro) cell towers, which are already used successfully for 3G and 4G LTE networks, offer coverage of several tens of kilometers and allow access to hundreds or thousands of users.

Small cells have a range that varies depending on environmental conditions, from a few tens of meters to an area with a radius of several kilometers. These cells ensure better coverage of the territory and greater efficiency when using the radio signal. To meet the challenging requirements of 5G deployment, small cells require rectifiers and DC / DC converters that can provide a high level of efficiency and dissipate heat efficiently.

Implementation of 5G

Currently, 5G technology is going through different phases, with all macro cells being upgraded. The transition from 4G to 5G technology is very expensive, mainly due to the deployment of macro towers that are 200 to 300 feet high. Small cells, on the other hand, can be easily mounted on an electric pole or lightning rod and are cheaper.

5G requires more power than previous mobile technologies and provides the highest bandwidth and bandwidth in mid, high and high frequency bands, including millimeter waves (mmWave) above 24 GHz. This is where the real benefits of 5G will come from, because higher frequency means higher bandwidth, which leads to better data throughput.

“Currently, the trend is to make full use of the middle band – upgrading tall towers from 4G to 5G radios – but we know from physics that as the frequency increases, the wavelength becomes shorter and the signal coverage is reduced.” said Raj Rajasami, a leader in the 5G and wireless segment in ABB Power Conversion.

This means that a 200-foot tower that can cover a 10-mile radius running 2G and 3G technology can handle less than a 5-mile radius with 5G radio, or even less than a mile when works in the mmWave range.

“Over the next three to four years, we expect a wave of transition from macro cells to more small cell deployment,” Rajasami said. “For example, in the United States, the number of small cells is expected to double from about 2024 to 2025, from about 400,000 to 800,000 small cell implants.1

Small cell power solutions

Therefore, rectifiers or DC / DC converters, depending on how the power is supplied to the small cell radios, will be installed at the top of the light pole or power pole. If AC is already available at the pole, a rectifier is required. However, there are some cases where it may not be possible to touch the AC directly from the pole; in these cases DC is provided by a centralized installation using DC / DC converters.

It should be noted that the drop in DC voltage on the line depends on how far the load point is from the power supply. If the distance is greater than one mile, the voltage drop is not negligible.

ABB Power Conversion’s solution to this problem is what they call linear power. The voltage is increased to ± 190 V and applied to the individual sites with small cells. With high voltage already available, it is possible to compensate for the voltage drop and reach one mile, two miles, or four to five miles.

With the continued implementation and deployment of 5G technology, efficient and reliable powering of next generation networks will be a must. To support the widespread deployment of 5G to its customers, ABB Power Conversion recently expanded its product portfolio with the CC1600 rectifier, CC1600 high-voltage DC / DC converter and QS200 downstream converter, all suitable for meeting the energy needs of small cell networks.

The QS200 (Figure 1) converts up to four 100-V channels of ± 190 VDC from a converter up the circuit to a highly reliable 48 VDC to power the client equipment from the far end. The remote mains converter meets the requirements for 5G power supply, providing up to 300 W, 6 A rated power of 48 V (actual output voltage is 55 V). The efficiency is very high, up to 92% at full load, and the temperature range is from -40˚C to 65˚C with self-protection above the upper limit. The QS200 has a degree of protection of IP68 and is hardened for outdoor operation with natural convective cooling. It extends from a centralized power supply to the loading device via a twisted pair of copper cables and can be mounted on a thread, pole or ground, regardless of potential water saturation, making it ideal for low-energy, outdoor loads such as broadband DSL applications as well as small cell and 5G applications. The outputs of all four input channels (each with the possibility of 75-W output power) are combined into one output. This means that if one input channel is lost, 225 W is still available at the output.

Figure 1: QS200 power converter

CC1600-SC55 is a conductive rectifier designed for reliable operation both indoors and outdoors, thanks to its airtight and weatherproof housing. High range AC input (200-240 VAC), can deliver a maximum output power of 1600 W at enclosure temperatures below 50˚C. With low range AC input (100–120 VAC), it delivers up to 1200 W at body temperatures below 50˚C. With an efficiency of over 94%, the rectifier can be mounted on a pole, on the side of a building or various other outdoor areas that are vulnerable to the elements, making it ideal for powering 5G equipment.

The 1600 W power supply is also available as a high voltage DC / DC converter (CC1600SC54HV), which offers outdoor installation options similar to a rectifier, but is powered by ± 190-VDC input instead of 240-VAC input found on the rectifier CC1600. It can remotely power small cells from a centralized location with a spare battery.

“We look closely at each part of the design, identifying where we can increase efficiency, such as the PFC phase, and make sure we optimize each phase in an appropriate way to improve efficiency and reduce energy consumption,” Rajasami said.

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