Dell'Oro: 6 GHz - the next 5G frontier?

Today, 5G is being deployed at full speed in the sub-6GHz spectrum, and the focus has quietly shifted to the next band frontier.

Mid-band spectrum used in conjunction with Massive MIMO achieves more total capacity and throughput growth using a low budget and will largely drive the 515-fold growth, but the baseline scenario shows that mobile data traffic is expected to grow another 1525-fold to exceed 1ZB per month by 2030, which will not be enough to meet capacity needs over the next decade given the economic constraints facing operators.

Therefore, people have turned their attention to the next-generation 5G spectrum frontier - the 6 GHz spectrum (5.925-7.125GHz).

The Federal Communications Commission (FCC) has announced a plan to make 1200 MHz of spectrum available for unlicensed use in the 6 GHz band, allowing low-power devices in the band and standard-power devices in 850 MHz. To maximize efficiency, other countries must consider a more balanced approach between unlicensed and licensed spectrum in the 6 GHz band. The WRC-23 IMT designation for the 6425-7025 MHz band will provide service providers with a solid foundation to realize their 5G vision while providing consumers, businesses and industries with 600 MHz of incremental unlicensed spectrum to manage increasingly crowded WiFi networks.

The baseline scenario suggests that mobile data traffic will grow 15 to 25 times over the next decade. From 1G networks to today’s 5G networks, operators have mastered three basic tools to manage capacity growth, including introducing more efficient technologies, deploying more cell sites, and using more spectrum.

As the mobile communications industry has grown, there has been one consistent theme: the low-hanging fruit has been picked, and it is becoming increasingly difficult to reap the higher rewards.

Assuming all other conditions remain the same, the transition from 4G to 5G will bring a 20% to 30% increase in spectrum efficiency. The number of macro base stations worldwide is growing rapidly every year, and the deployment of small cells is also increasing steadily, but at the same time, co-channel densification without beamforming will increase interference between base stations, thereby limiting uplink space.

Massive MIMO and beamforming technologies address the interference limitations associated with small cell densification by increasing the number of antennas at a site, enabling operators to optimize the RF signal directed to targeted users while minimizing interference levels for remaining users.

Therefore, from a technology perspective, Massive MIMO and beamforming are the next most effective solutions to the capacity toolkit. In addition, more targeted beams are improving the cell range of base stations, allowing operators to achieve equivalent 2 GHz LTE coverage on higher mid-band frequencies, reducing the number of sites required.

The cost-per-bit benefits of Massive MIMO are greatly improved due to the increased capacity and the fact that there is no need to add more sites. It is not difficult to understand the huge appeal of Massive MIMO to operators. In 2019, Massive MIMO technology accounted for more than 70% of the 5G mobile infrastructure market.

So there is no doubt that the outlook for Massive MIMO remains positive, suggesting that operators will use 32T32R, 64T64R, and eventually 128T128R antennas to squeeze as much capacity and value as possible from mid-band spectrum. Depending on the spectrum asset, an effective Massive MIMO strategy can generate another 5-15x increase.

In any case, Massive MIMO in mid- and high-band spectrum is not enough to support the huge traffic consumption in the future, nor can it cope with the introduction of any disruptive devices. Although video consumption accounted for the largest share of mobile data traffic in 2019, the average smartphone user now spends only about 20 minutes per day watching videos on cellular networks, and the baseline forecast: by 2030, the time spent streaming 4K video per day will exceed 45 minutes.

Unlicensed spectrum proponents tend to allocate most of the 6 GHz band to unlicensed applications, meaning they expect the growth in mobile data consumption to slow much faster than generally expected, or that millimeter wave technology can play a major role in addressing the expected shortage.

With more than 100,000 mmWave base stations installed in 2020 and mmWave smartphones already capable of Gbps performance, it is widely believed that mmWave based on 5G NR technology is developing much faster than expected. At the same time, the current economics are not yet sufficient for most operators to deploy mmWave systems in more urban areas, and the technology cannot handle a large portion of overall mobile data traffic under capital constraints. Even with the upward adjustment of expectations, 5G mmWave systems will still account for less than 5% of radio shipments in the next five years.

However, with 600MHz of 6GHz spectrum and macro base stations based on EIRP levels, operators will be able to leverage existing macro grids to deploy Massive MIMO systems with beamforming, enabling them to not only handle baseline growth forecasts for the next decade, but also have some leeway to handle the introduction of new disruptive devices.

From the perspective of speed, an important requirement of the IMT-2020 standard and vision is that 5G networks can provide 100 Mbit/s data rates to all users anytime, anywhere. Therefore, in addition to planning network capacity, operators also need to ensure that the network experience is consistent everywhere, every day.

Although mobile network growth will slow down significantly, spectrum policy will need to consider alternatives, and we don’t know how much of the 5G vision will be realized over the next decade, we do know what tools operators have at their disposal to navigate the ongoing transition from MBB to eMBB and IoT.