mmWave, 5G, and Satcom: Making the Most of Spectrum

The issues and the conversation around mmWave are an open secret. It seems that while India might have enough mmWave spectrum, the government has been working on deciding who gets how much of it. As such, this has seen insistence from both telcos and satcom players for use of mmWave. Satcom players have a legitimate worry; it is one of the only four bands that satcom uses. There have been accusations against telcos on their attempts of hoarding spectrum. Is mmWave the new target for telcos, or do they actually need all of it?

What is mmWave, Though?

In spectrum-speak, mmWave forms the part of the frequencies that have millimeter-scale wavelengths. Hence, millimeter-wave, or mmWave. This spectrum band forms the lower bit of the Ka-band, one of the four spectrum bands used by satellite ISPs. Technically, the mmWaves come under the Extremely High-Frequency designation by the IEEE. In the Indian context, however, the waves comprise the 26.5 to 29.5 GHz band. This band falls right on the edge of EHF but lies in the SHF or the Super High Frequency. Incidentally, the mid-band spectrum also lies in this range, and that is called, rather imaginatively, the centimeter waves.

However, these shorter wavelengths have their own benefits as well. Small antennas can achieve the same amount of high gain and directivity as the lower bands. This translates, along with the high free space loss, to more efficient use of frequencies for point-to-multipoint applications.

These highly directive antennas can go in a larger number than a normal antenna in a given area. Therefore, mmWaves can have a greater user density due to higher frequency reuse. This is precisely what makes the band precious to telcos – with India’s urban teledensity at 138.72%, this could prove to be a game-changer. Also, the high usable channel capacity in this band can also allow it to serve some applications that would otherwise use fiber-optics, such as telecom backhaul.

The Headaches of High Frequency

The telcos can make use of the great usability of the spectrum, and the high capacity and bandwidth, that allows telcos to support dense urban settings, but that is it. There is no practical range to speak of, especially with mmWave. Neville Ray, President of Technology, T-Mobile, had said in a blog post back in 2019, that the mmWave spectrum used for 5G “will never materially scale beyond small pockets of 5G hotspots in dense urban environments”. This potentially means that no 5G for rural settings.

Incredibly mmWave struggles to penetrate even glass doors. This low penetration, coupled with its limited range, implies that telcos have to install a ridiculous amount of antennas. That means, 5G over mmWave is going to be useless outside of a very limited footprint. Therefore, To use the 5G to the best of effects, one has to stay within a limited footprint of around 1 square kilometer, where the reception is good enough. However, most people do not stay within such a small footprint.

It does not mean that it can’t be used in rural settings. The sheer amount of infrastructure that it would require makes it prohibitively expensive. Let’s take an example. Suppose a suburb is 10 kilometers away from the city center. Let’s also suppose that we want to take the mmWave to this suburb from the city. Given the average range of 1-1.5 kilometers, we will need 5-10 antennas to just bring it to the suburb. That is a considerable amount of investment, no matter how you look at it.

The best use for mmWaves is to use it to deploy 5G in small pockets of high-density urban areas, it seems. And even then, it can’t even penetrate materials, making it a really questionable investment to make. However, GSMA called the use of spectrum above 24GHz “vital” for high-speed 5G. And it is – lower bands translate to lower speeds. This is mostly because of the sheer amount of unused spectrum in higher bands. Also, one can count the bands with considerable unused blocks of spectrum below 1GHz on one hand.

Sell it, or Allocate it?

Earlier this month, the DoT decided that it will put the mmWave on auction, rather than going for allocation. After the DoT had asked TRAI to provide recommendations on September 13, TRAI floated a consultation paper. TRAI, in its consultation paper, answered over 70 questions asked by the telecom department. Furthermore, it had earlier asked the department to provide details on the mmWave spectrum such as the use cases and the quantum available for sale.

The “auction” corner has been talking about how it would ensure a “level playing field” because everyone will get to auction for the spectrum. However, not all of the satcom operators can compete with telcos in that regard. Starlink and OneWeb can, and will, but apart from those two, no one else can invest the kind of money required in the spectrum.

Therefore, the government was considering offering only a part of the mmWave spectrum for auction, between 24.5 and 28.5 GHz. Notably, 3GPP has standardized the mmWave band up to 29.5 GHz for telcos. The government will earmark the remaining 1 GHz of the band for satcom companies. However, neither the telcos nor the satcom operators want the said bifurcation. It has to be realized that for telcos, the mmWave band might prove a crucial ingredient to building powerful 5G networks, and monetizing them via use cases.  However, for satcom operators, mmWave remains the only way they can operate.

This will of course lead to different issues, however, this was the only solution without leaving anyone dissatisfied.

Making the Right Call

Interestingly, yesterday, Cristian Gomez, Senior Director, Government & Regulatory Affairs, Asia-Pacific, Viasat, warned the government of significant losses if it decided to give the 26-28 GHz spectrum to telcos. "If India makes the mistake of offering 28 GHz in full or part to 5G mobile industry which has not been demonstrated any uptake in the mid-band so far then it will lose $184 billion by 2030 and may end up with underutilized spectrum", Gomez said.

He further added, "...mmWave is not being used and processed globally. It is hard to understand why India is focusing on it when the rest of the world is going in a different direction... we are concerned that India may not be able to benefit from the space economy if there is no spectrum for satcom". Viasat also added that while satcom needs the 28 GHz band, the government can adjust the telcos in the 26 GHz band. It added that the said spectrum band offers 3.2 GHz of spectrum, and hence, can accommodate all the telcos.

Incidentally, the telcos said that they need at least 1 GHz of mmWave per operator to build an efficient network. Further, as the networks mature, they will need a total of 2 GHz spectrum per operator in mmWave. They also claimed that if the government reserves a part for satcom, telcos can’t build an efficient 5G network.

Viasat further added that no county has prioritized building 5G networks over mmWave. Gomez added, "even though countries that prioritize mmWave have now shifted their focus...the key reason is 5G is expensive to deploy and requires new gear, especially in mmWave. You will need millions of new towers...deploying a national 5G network using mmWave is not realistic while on the other hand lower frequency needs lesser towers".

Finding a Middle Ground

There are two things that we need to address here. First, the telcos need to realize that 5G can work without them having all of the mmWave spectra. Second, the satcom players have to realize that without the spectrum in question, telcos can't build effective networks.

India’s urban population is steadily growing and it has some of the most jam-packed cities in the world. Therefore, Indian telcos will need mmWave to support the cities. Apart from that, there is not much mmWave can do for telcos. However, satcom can use the unused spectrum for internet from space, and telecom backhaul. This also allows for a massive B2B application for satcom as well in the country. With India recently allowing satcom companies to provide satellite backhaul without a separate license for it, satcom remains poised to make the most out of the space economy.

The lack of clarity has seen discussion on a potential Spectrum Act to solve these issues once and for all. However, any such legislation would also need time to formulate and implement. Ultimately, it comes down to what solution will use the most spectrum in an efficient way.