Dell'Oro: Mid-band and Massive MIMO are not enough to handle large traffic, 6Ghz is the key

In a recent blog post, Stefan Pongratz, vice president and analyst at market research firm Dell'Oro Group, analyzed the spectrum required for the future development of 5G technology. According to forecasts, mobile data traffic is expected to increase by another 15-25 times in the next decade, and existing mid-band and Massive MIMO technologies are not sufficient to cope with such traffic growth.

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With 5G now being deployed at full speed in sub-6 GHz spectrum (both low-band and mid-band), the focus is shifting to the next spectrum frontier. Even though mid-band used in conjunction with Massive MIMO has been a huge success from an economic and technical perspective, delivering more total capacity and throughput growth at much lower capital expenditure than originally envisioned, the baseline scenario shows that mobile data traffic is expected to grow another 15-25 times over the next decade, exceeding 1ZB per month by 2030. While Massive MIMO and sub-6 GHz spectrum will largely deliver 5x to potentially 15x growth, it may not be enough to meet capacity needs over the next decade given the economic constraints facing operators.

As a result, all eyes are now on the forefront of next-generation 5G spectrum – also known as the 6 GHz band spectrum (5.925-7.125 GHz). The Federal Communications Commission (FCC) recently announced plans to make 1200MHz of spectrum in the 6GHz band available for unlicensed use. To maximize overall efficiency and potential impact on the wireless economy, other countries and regions must consider a more balanced approach between unlicensed and licensed spectrum in the 6GHz band. The WRC-23 IMT designation for the 6425-7025MHz band will provide service providers with a solid foundation to deliver on their 5G vision while providing consumers, enterprises and industry with 600MHz of incremental unlicensed spectrum to manage increasingly crowded WiFi networks.

The baseline scenario assumes that mobile data traffic will grow 15-25 times over the next decade. While this may initially seem relatively slow compared to the growth rates of previous decades, the reality is that we are on track to consume as much data traffic in 2030 as we did in the first 20 years of the smartphone era.

There is no magic. From the earliest 1G networks to today’s 5G networks, operators have mastered three basic tools to deal with capacity growth, including introducing more efficient technologies, deploying more cell sites, and using more spectrum.

随着移动通信行业的发展，这些提升容量的手段的作用也随着时间的推移而波动，然而，一个始终不变的主题是：唾手可得的果实已经摘了下来，要想获得显著的收益，难度越来越大。

Assuming all other conditions remain constant, the transition from 4G to 5G can improve spectral efficiency by 20%-30%. The number of macro base station deployments worldwide is growing at a high single-digit percentage each year. Small cell deployments are accelerating, but at the same time, co-channel densification without beamforming technology increases interference between base stations, limiting growth.

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 the intended users while minimizing the level of interference to the remaining users.

Therefore, from a technology perspective, Massive MIMO and beamforming are the next most effective solutions in the capacity toolkit. In addition, more targeted beams are improving the cell range of base stations, allowing operators to achieve equivalent 2GHz LTE coverage on higher mid-band frequencies, thereby reducing the need to add more sites to compensate for the higher path loss that comes with higher operating bands.

And, since the coupling between mobile infrastructure investment and wireless capital intensity remains strong, meaning that constrained operator revenue growth will ultimately impact operators’ ability to increase capital expenditures, the appeal of mid-band Massive MIMO is understandable. The combination of increased capacity and the cost-per-bit benefits that come from not having to add more sites is the foundation for Massive MIMO’s success – Massive MIMO technology accounted for more than 70% of the 5G mobile infrastructure market in 2019.

Not surprisingly, the outlook for Massive MIMO remains bullish, suggesting that operators will use 32T32R, 64T64R, and eventually 128T128R antennas to squeeze as much capacity and value as possible from this valuable mid-band spectrum. It is challenging to determine the exact growth potential at this juncture, but it is not inconceivable that an effective Massive MIMO strategy could generate another 5-15x growth, depending on the spectrum asset.

In any case, Massive MIMO on mid-band spectrum will not be sufficient to cope with the baseline scenario of more than 1ZB of mobile traffic per month by 2030. And it certainly will not cope with any of the disruptive device introductions that will spur changes in mobile network usage behavior and video traffic consumption. Although video consumption accounted for the largest share of mobile data traffic in 2019, the average smartphone user still only watched about 20 minutes of streaming video per day on the mobile network, and the baseline forecast is based on the assumption that by 2030, the average smartphone user will spend no more than 45 minutes per day watching 4K video.

Unlicensed spectrum proponents favor allocating most or all of the 6 GHz band to unlicensed applications, implying that 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 station installations expected in 2020 and mmWave smartphone devices already delivering Gbps performance, most agree that mmWave based 5G NR technology is advancing much faster than initially expected. At the same time, the economics are not yet compelling enough for most early and late operators to deploy mmWave systems in wider urban areas, and the technology is not yet capable of handling a significant portion of overall mobile data traffic given capex constraints. Even with the upward revision in 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 networks to deploy Massive MIMO systems with beamforming, giving operators more capacity to not only address the baseline growth forecast for the next decade within a constrained CAPEX context, but also have some wiggle room to address the introduction of new disruptive devices or greater than expected IoT/Fixed Wireless Access use cases.

From a speed perspective, a more important requirement in the IMT-2020 standard and vision is that 5G networks should always be able to provide 100mbit/s data rates to all users anywhere, anytime. Therefore, in addition to planning for network capacity, operators also need to design the network to provide a consistent experience in every cell and every day.

In short, we don’t know how much of the 5G vision will be realized over the next decade. But we do know what tools operators have at their disposal to deal with the ongoing transition from MBB to eMBB and IoT. While mobile network growth may slow much faster than expected and spectrum policies need to consider alternatives, what if people spend more than 5% of their daily time watching videos on mobile networks?