The increased power consumption of next-generation basestations may be one of the dirty little secrets of 5G, which might not be a secret much longer as operators roll out initial networks.

The power consumption of a 5G basestation is three times that of its 4G LTE predecessor, according to Zhengmao Li, EVP at China Mobile, at a presentation at Mobile World Congress last week, as noted by my Heavy Reading Colleague, Gabriel Brown:

Challenges of 5G deployment, according to Zhengmao Li, EVP China Mobile (biggest operator on the world).

1. 5G needs 3 X base stations for same coverage as LTE due to higher frequencies

2. Power consumption of a 5G base staion is 3 X LTE

3. 5G base station costs 4 X price of LTE — Gabriel Brown (@Gabeuk) February 24, 2019

5G basestations bump up the power requirements over 4G LTE, in part because of the massive antenna arrays (MIMO) used for the next generation tech. Earl Lum, president of EJL Wireless Research, says that MIMO increases the "power amplifiers" and "analog-to-digital paths" required, as well as overall digital circuitry in the units. For instance, typical 4G basestations now use 4 transmitter and 4 receiver (4T4R) elements, while 5G is expected to use 64T64R MIMO arrays.

"Sprint stuff is 64T64R," Lum notes. (See Sprint's Initial 5G Cities Will Get 4G Massive MIMO First.)

Lum expects this to increase power requirements at cellsites, "Now you'll need 10 kilowatts of power," he says, so that operators would likely want to have 15 kilowatts of power at hand. 4G cellsites use around 6 kilowatts for power, assuming a three-sector, 12 radio set-up.

This might cause some carriers to downgrade their MIMO requirements. South Korean operators are using 32T32R arrays for 5G, Lum says.

"There are lots of trade-offs, 64T64R makes sense for," Heavy Reading's Gabriel Brown notes. "Say Sprint with a US cell grid and the need for dual LTE-NR support, whereas somewhere like Korea or Europe 32T32R is a sweet spot."

Lum expects China Mobile to look to deploy 16T16R arrays in more rural areas, which will reduce costs but also speed and capacity.

Overall, power consumption should come down on 5G infrastructure over time. "Materials technology is improving," Brown says, while noting that "power-saving techniques" and AI will all come into play too over time.

While EJL Wireless Research's Lum says operators could hold off "maybe three years" in expectation of better power consumption results for 5G.

— Dan Jones, Mobile Editor, Light Reading