There's no quick fix to cutting mobile network energy usage

The NGMN Alliance has published new recommendations to help the mobile industry reduce the amount of energy used by its networks, but most of the savings will not happen quickly.

The industry body notes that it is possible to reduce energy consumption by up to 10% in the short term by optimally configuring networks using existing power saving features.

That figure is not to be sneezed at; 10% is a fair amount when you consider the massive amount of energy consumer by the mobile industry, although admittedly NGMN does not put a figure on that. However, it’s significantly less of a game changer than the numbers the NGMN has come up with for medium and long-term energy savings.

In the near-term – we don’t have a more specific timeframe than that – it’s all about process optimisation. The industry can use machine learning (ML) to estimate the energy consumption reduction that can be realised through the use of existing power-saving schemes, enabling operators to select the most appropriate energy-saving policy.

In its list of example energy-saving solutions, the NGMN includes rules-based automation and AI-based automation of 3GPP energy-saving features; the former could bring a 3% energy-reduction in a 4G/5G network and the latter 9%. The full document is available here.

The examples given as medium-term solutions, under the theme of engineering optimisation, include the replacement of single-band remote radio units (RRUs) with tri-band RRUs to generate a saving of 30% per unit; a 50% reduction in feeding path losses from the use of passive antennas; and a 60% reduction in DC power losses per RRU by moving to bus-based architectures.

The RAN accounts for around three quarters of mobile network electricity consumption, with the RU, baseband unit and main control making up half of the electricity consumption of a typical cell site. Therefore, a 30%-40% energy saving per RU could result in a saving of around 12% across the RAN, the NGMN notes.

Longer term, network operators can look to new technologies to realise energy-savings, such as liquid immersion cooling, network disaggregation and cloudification, Reconfigurable Intelligent Surfaces (RIS), and distributed Massive MIMO. NGMN highlights cooling technologies as being of particular importance, noting that cooling accounts for up to 40% of RAN electricity consumption.

These technologies could be some way off, or at least it could take a while for them to become mainstream; for example, the NGMN describes the potential energy savings from RIS as coming with “Late 5G Advanced / Long term,” but for the most part the industry is talking about RIS as an element of 6G.

But telcos’ need to cut energy is much more immediate than that. Aside from the CSR angle and the drive to take telecoms businesses to net zero over the next decade or so, operators are hamstrung by soaring energy costs, which are taking their toll on opex figures.

Executives from Deutsche Telekom and Orange said exactly that in canned comments accompanying the NGMN publication.

“Our continuous efforts at NGMN are an important step in enabling operators and suppliers to identify practical and immediate ways to reduce network energy consumption,” added Arash Ashouriha, SVP Group Technology at Deutsche Telekom and Chairman of the NGMN Alliance Board.

Broadly, the NGMN recommends that operators review the energy saving potential of the options it outlines in the report and that “further studies are conducted” – by whom it does not say – on key areas that could help with energy-reductions, such as network disaggregation and cloudification. It also calls for more work on energy management and renewable energy solutions.

And clearly the telcos need to keep an eye on those automation techniques to help them realise that 10% short-term saving. It might not be a huge figure, but every little helps when it comes to keeping the electricity bill down.

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