By Drazen Vitez

Recent raging energy price rises have moved the topic of energy saving to the top of the telecom boardroom agenda. Migration toward new and more energy efficient technologies are key to the energy saving strategies of operators.  But this is a slow and cumbersome process, so operators are looking for additional new ways to save on energy bills which can be implemented in a short period of time. We would like to propose 5G Hybrid Access as a 5G energy saving strategy.

Fig 1 – Proximus CEO LinkedIn Post on 29-09-2022

Understanding the 5G NR energy saving conundrum

In mobile networks, the radio network is responsible for the lion’s share of energy consumption. According to a Nokia whitepaper “5G network energy efficiency”¹  80% of total MNO energy use comes from base stations.

Even though 5G NR is marketed as radically more energy efficient compared to 4G RAN, this will not always materialize into lower energy consumption. The key metric used to demonstrate 5G NR energy efficiency over 4G RAN is “Wh/bit”. This is in fact an unhelpful metric for MNO’s. The fact is that each 5G site will need two to three times more power than the 4G-equivalent site, according to industry estimates².

Figure 2 – Share of base station energy consumption¹

Many operators have already implemented systems for smart energy management of radio network sites which are contributing to energy savings:

–  at site level by implementing micro sleep mode, MIMO muting etc. and

–  at RAN level by implementing complete site sleeps and shutdowns in case of e.g. overlap coverage etc.

Energy management systems are important because the energy consumption of mobile networks is not very load sensitive. In the traditional RAN just 15 percent of the energy spent on operating a network is used for forwarding bits, which means that 85 percent of the energy does not contribute to generating revenue. ¹ Most energy is used for system broadcasts and running idle resources, to power fans and cooling systems.

How much savings those management systems yield will depend on underlying radio technology, and also on network usage. 5G NR has much more energy saving capabilities than 4G RAN. In the following example (see charts below) we can see the power consumption of the 4G and 5G NR base stations in idle mode³. We can see that a more flexible reference interval defined in 5G NR allows for much longer TX micro sleep intervals which are then reflected in the higher energy savings of the 5G NR site, but only in low or no traffic situations. Such features make 5G NR energy consumption more load sensitive than 4G RAN.

Figure 3 – 4G vs 5GNR energy consumption in idle mode³	Figure 4 – Power use reduction in low load regimes¹

As long as traffic remains high in 5G NR networks, there is limited scope for impact by smart energy management systems on energy savings. 

5G FWA, as one of the the favourite 5G NR applications of MNO’s, fills the 5G NR network with a huge amount of traffic (100x smartphone usage per user). Therefore, any offload of mobile traffic from 5G NR to fixed networks and WiFi will help energy management systems to better utilize new 5G NR features and reduce MNO energy consumption.  

Enter 5G Hybrid Access

5G Hybrid access combines existing fixed broadband network and 5G NR infrastructure to provide superior connectivity for users. Tessares has rolled out hybrid access in non-fiber areas in order to provide significant user experience improvements over copper networks.

Compared to 5G FWA, 5G Hybrid access can provide the same user experience (speed, latency) while transmitting up to 85% less data over the 5G NR network. Since 5G FWA can be responsible for 80% of all traffic, off-loading up to 50% of that traffic (some FWA use cases are not suitable for Hybrid replacement) will have a major impact on the number of cell sites that can operate in low-load mode and increase the duration of the low-load regime. This, in turn, will allow smart energy management systems to utilize those 5G NR features for low-load energy saving and contribute to overall energy saving for the MNO.

Contact us for more information or better yet, come and visit us at Network X in Amsterdam, October 18-20, 2022 Booth G16 in the 5G World Area.

References:

¹ Nokia: 5G network energy efficiency

²McKinsey: The case for committing to greener telecom networks

³Ericsson: 5G network energy performance