The muscle behind 5G wireless communications comes from advanced antenna systems, according to Paul Challoner, vice president of network product solutions for Ericsson North America. Specifically, multiple-input multiple output (MIMO) active antenna systems (AAS) for the 2.5 GHz and 3.5 GHz or 3.7 GHz C-band are going to be highly important, he said.
“We’re on the next generation of MIMO radios, so we have to pack a lot into MIMO radios; there’s a lot of antennas,” Challoner said. “In this case, we’re saying 64 transmit, 64 receive, all in the same physical unit. In this generation, we have made a jump forward. We have taken 40 percent of the weight out, and maybe equally as important, 20 percent of the power consumption, delivering that in a leading class of capacity performance in a radio unit.
“When we talk about physical space, weight and wind loading, this next generation is going to make a difference in deployment,” Challoner added.
Challoner spoke at the April AGL Virtual Summit session, “5G MIMO Antennas Are Taking Off, but Is There Room on the Tower?”
The Ericsson executive said that the company has existing generations of equipment that it is deploying now and that address challenges involving the number of antenna positions on sites, making sure that wind load loading and structural calculations fit the sites. Although in Challoner’s view, Ericsson is having a good success rate with its current MIMO generation, he said the company sees the next generation of equipment to be a good evolution that will make it easier for carrier customers to deploy.
Session host Earl Lum of EJL Research asked Challoner whether Ericsson has a complete portfolio end-to-end to meet the carrier requirements on a macro cell tower, stealth tower, rooftop or small cells on poles. Challenor said the challenge lies in frequency variants in the United States.
“For each of those frequency variants, we have different radio types,” he said. “Then, we would have many classic radios to transmit to receive, for instance, 16, 32 and 64. Some of those have different power levels or high power levels. Some of those are optimized for tower mount, some for roof and pole mount, and of course not forgetting the indoor portfolio. So, we actually have in the portfolio hundreds of radios that cover these different deployment scenarios.”
The focus at Ericsson today, Challoner said, is on frequency-diverse arrays (FDAs), the massive MIMO portfolio, “because that really gives us the muscle, this capacity that we’re trying to add to 5G right now. We see that 64T 64R radios will be the weapon of choice for deployment. The incremental price performance of those radios gives compared with a classic radio is significant. An active antenna system or massive MIMO radio gives you two times to three times the capacity of the classic, existing radio types. It is a massive improvement in performance. We want to use that, maybe not everywhere, and it is a little bit band-specific, but certainly as we look at these new mid-bands, that for mid-band time-division duplexing (TDD), the AAS is the way to go. We think that the 64T is a good modifier.”
Lum turned the conversation to electrical power consumption at antenna sites. The 64T 64R massive MIMO antennas consume about 1,500 watts maximum, and Lum said many regions in the United States will require battery backup power because of hurricanes and other adverse weather conditions along the East Coast and elsewhere. He asked Challoner whether Ericsson has a way to address what operators need for battery backup power.
“We see the power solution as an end-to-end problem statement,” Challoner said. “We have a set of rectifiers, typically, in the base station site. Either we can add rectifiers, or we have done a lot of pre-planning for this kind of event to make sure we pre-populated as much of those types of equipment as possible. We can either add rectifiers or use the rectifier technologies that we have now. We have 98 percent efficient versus 96 percent; thus, you can improve the rectifier piece.”
Next, Challoner said, comes a battery. “Battery management is important,” he said. Lithium-ion technology may be something that can be introduced at the same time. Smart management of the battery in the battery-life cycle is important.”
Another important factor Challoner mentioned is the electrical conductor from the ground to the tower and the management of the cable booster technology.
“What’s even more important than that is how you manage the power consumption of the radio,” he said. “We apply lots of smart software now. We have artificial intelligence and machine learning techniques to optimize the way these different radios — maybe we have seven different bands or multiple different radios up the tower — work together, making sure we don’t have peak power draw across all of these radios at the same time. Plus, we also switch off radio capability that we don’t need in the middle of the night.
“It’s all about smart management of the radios with software, together with this end-to-end management from utility power to radio software,” he added.
With each new generation of the radio, Challoner said, Ericsson improves the power amplifier efficiency, and that determines the power draw of the site. He said the answer is how efficient the power amplifier is in turning DC power into RF power.
“It’s a huge challenge from a green perspective, as well, to make sure that our sites are as efficient as possible,” he said. “Typically, we’re going from an average of 10 kilowatts and, as you add multiples of these MIMO technologies, you may be going up to the 12-kilowatt to 15-kilowatt level. We have to manage that in the most cost-effective way and in the most environmentally friendly way.
As for the use of omnidirectional antennas, Challoner said they have limited applicability. He said MIMO solutions do not need omnis, and even many small cells have integrated antennas that do not need omnis. Some canister antennas are directional, he said, “so you have fairly limited opportunities for omnis.”
For 64 x 64 MIMO antennas, Challoner said that because of their size, he expects them first to go onto towers because of the real estate required. He said there are some applications or some ways in which they could go into the street level.
“One of the new trends is to balance the macro layer, which is on towers, with a street layer,” he said. “Thus, we are seeing massive MIMO antennas in the high-band in millimeter-wave; we have massive MIMO solutions there, and then we’ll see mid-band at the street level as well, with massive MIMO capabilities.
Asked whether 4 x 4 MIMO could achieve 5G speeds and latency goals, or does the MIMO number need to be higher, Challoner said that meeting the multi-gigabit promise of 5G requires a large amount of radio bandwidth, such as the mid band deployment, which has 100 megahertz or more of bandwidth.
“Typically, to make the most of that kind of bandwidth we use massive MIMO,” Challoner said. “For the capacity layer, you definitely need that AAS type of technology. There are some applications, maybe in the small cell environment, in the rural environment, where the 4T 4R capabilities would still be used, but you do not typically get to the multi-gigabit level with those solutions. If you want blazing fast speeds, you need to go to the massive MIMO with a decent amount of deployed bandwidth.”
Total Tech sponsors of the April AGL Virtual Summit included Raycap, Valmont Site Pro 1, Vertical Bridge and B+T Group. The Top Tech sponsor was Aurora Insight. Additional sponsors included NATE, Voltserver, WIA and Gap Wireless. The next AGL Virtual Summit is scheduled for June 8 at 2 p.m. Eastern time. The Summit is free to attend; register here.