Sustainability and power drive for 6G telecoms
Sustainability and reducing power consumption are key drivers for 5G and 6G telecoms networks, says Peadar Forbes, Director of Radio and Platform Development at Analog Devices. New algorithms and AI are being used to cut the energy use of radio unit in particular.
“There was a lot of interest in sustainability, that was definitely a big theme both for electricity prices and meeting sustainability targets,” said Forbes, who is based at ADI in Limerick, Ireland. tells eeNews Europe.
“It’s the number one topic in a lot of meetings to reduce the energy in the radio access network (RAN). About 70% of the power consumption is in the RAN and less than 30% in the core network. Within that, the bulk of that is in the radio unit so ADI is in a strong position to address that,” he said.
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He points to the efficiency of the power amplifier (PA) as a key area that can be talked by using digital pre-distortion (DPD) algorithms. These were previously run on FPGAs but demonstration at MWC with Marvell with a massive MIMO antenna system saw the algorithms running in software on ADI’s Radioverse transceivers and Marvell’s Octeon processor.
“Previously the efficiency of the PA was around 30% so most of the power is not getting to the cellphone,” he said. “Now with advances in PA and DPD algorithms its pushing into the low 50s – that’s pretty big improvements.”
“In this massive MIMO system we have managed to eliminate the FPGA from the radio unit,” he said. “This eliminates considerations around he hot spots that the FPGAs can cause in the radio units which need to be passively cooled with large heatsinks and that all amounts to weight. By using these ASIC solutions you can reduce the weight of the basestation by 5kg and that’s significant because the weight has limits on cranes and installers. Ideally you want a one person installation and that greatly reduces the installation cost and that’s typically around 20kg so a 5kg reduction can get you there and it also saves costs.”
“The drive to mMIMO has came about from the insatiable demand for more bandwidth and spectrum is limited having used up the lower frequency bands,” he said.
“The frequency profile of the higher bands say 3.5GHz means the propagation of the signals is lower and that’s where mMIMO comes in. Instead of broadcasting a signal, it uses beamforming which is more energy efficient and spectrum efficient. It also allows you to use the same spectrum to another user, so it maintains the same intersite distance while increasing the capacity of the network.”
“This is a cheaper alternative to having a new cell site,” he added.
Moving the mMIMO support into dedicated hardware is possible as 5G technology has matured.
“The mMIMO technology is settling down and we are far enough into 5G to figure out what can be hardened and what can’t be to get the most efficiency out of the PAs,” said Forbes. “This means we are able to put more of the DPD smarts in software rather than hardware, applying the coefficients to linearise the signal.”
Sustainability is also key for the next generation 6G technology.
“Its still pretty early days in the research for 6G, and it will probably be 2028 before there’s a standard,” said Forbes.
“What was most significant was the ITU announced that for the first time sustainability and energy efficiency has to be included, as well as providing coverage everywhere with non-terrestrial networks, so it’s great we are talking more about the environmental and societal things rather than technologies, which is different from how the standards have evolved in the past,” he said.
“There’s two main frequency bands being talked about, 7 to 20GHz which is interesting, but requires some reallocation of spectrum and that’s very interesting. There’s also the sub-THz range which will have propagation challenges over more than a few metres, and that will be used for niche industrial applications, including sensing, but the bulk of the activity will be in the 7 to 20GHz bands,” he said.
“AI will be a big thing in 6G right across the network in every node and in particular the air interface will have a lot more AI. One example is being adaptable to the type of data and the radio environment to better estimate the channel characteristics so we are very excited about the potential for AI,” he said.
He points to a collaboration with Keysight Technologies on test and design for intelligent edge systems and radios.
“We will need higher order antenna arrays for 7 to 20GHz and more densely packed radios, and that puts pressure on integration and power consumption as well as test for these large arrays,” he said, “More near term we are showing how the advanced sleep modes can enable network energy savings of up to 40%. The network doesn’t operate at 100% all the time, it’s quiet at night, and even during the day on a 10ms basis it can be sitting doing nothing so you don’t want the PA powered up all the time so we are looking at powering up and down very quickly.”