SHF bands to solve metrocell’s backhaul spectrum puzzle May 14 2014

By Luis Reyes Figueroa, Spectrum Analyst, Maravedis-Rethink

Managing the surge of mobile data demand, particularly in dense urban areas, continues to cause headaches to carriers. The nature of cellular networks means the only way forward is the densification of the network. As the number of cells multiplies, the probability of having easy access to fiber when building each new site decreases. Well-proven microwave technology has conveniently solved such challenges in the past, but the typical 15 to 23 GHz bands have begun to saturate. On the other hand, mobile operators wonder whether it is the time to make use of Metrocells to overcome the situation.

The question of Metrocells will increasingly raise the issue of what backhaul spectrum to use to connect these cells, while both vendors and regulators are increasingly looking at the accelerated spectrum shortage. This potential crunch presents mobile service providers with the urgent necessity of choosing among alternatives, of which the 10.5 GHz, 26 GHz and 28 GHz bands are the most interesting immediate options. These already show considerable occupancy, especially in Europe. In addition, there are technical regulations for their usage in many countries, as opposed to millimeter bands (30-3000 GHz) which are little used. They are the most active bands in most markets, according to Maravedis-Rethink’s Backhaul Regulatory Database, encompassing 64 countries and 7 frequency bands with information provided directly by regulators.

Currently, 10.5 GHz band is mainly or mostly used for broadcasting and radio communications in 26 countries. However, some of those 26 countries are either already using it for backhaul, or planning to use it for backhaul, mainly on a Point to Point (PtP) basis. Even though PtMP links are allowed in 26 countries, they are actually used in only two, as shown in Graphs 1 and 2.

The 26 GHz and 28 GHzbands are also being used widely for PtP, and to a lesser extent  for PtMP, to backhaul mobile services. The 26 GHz accounts for most of the active links above the rest of the bands in the countries analyzed, distributed among 25 countries for PtP and 5 for PtMP.  Similarly, 28 GHz is being used for PtP and PtMP in 13 and 2 countries, respectively. This reflects intensive use of both bands in European countries. 

The most important advantage to using these three bands – 10.5, 26 and 28 GHz -- is their lesser susceptibility to attenuation due to rain effects, compared to higher (millimeter) bands. However, there is a drawback, particularly in 10.5 GHz, where a mainstreaming regulatory approach for usage is placed on Fixed Wireless Access (FWA) for Internet access in 15 countries from different regions. In addition, if demand trends in 26 GHz and 28 GHz continue upward, both bands will saturate soon, as is already happening in some European countries such as Belgium, Germany, Greece and Spain.

Regulation lagging behind technology…

Growth in allocations in the three bands mentioned is already a problem, and the lack of regulatory frameworks in higher millimeter bands must be considered as an additional challenge. This is important if we consider regulators as responsible for fostering development in the backhaul market. As mentioned above, technical regulations for the higher millimeter bands rarely exist in the countries analyzed. In the best scenario, preliminary dispositions for channel arrangements and power transmission limits are published. There are just a few exceptions in emerging markets, such as Argentina, which already has regulations for 42 GHz band, or Colombia, and Qatar, having regulated V Band (57-64 GHz). Others, the majority, are far behind with no regulation at all in any of the millimeter bands. 

A third issue would be whether unlicensed bands could alter growth in backhaul spectrum usage, and alleviate costs to carriers. This is a hot topic in the industry, especially for vendors interested in developing solutions for unlicensed spectrum. However, there are 6 countries proposing unlicensed bands in our analysis. Of these, only Sweden, Poland and Czech Republic actually use them for fixed links to backhaul mobile services. 

As observed, choosing spectrum to backhaul mobile data yields dissimilar frameworks and levels of use in countries analyzed. Certainly, there is a clear increasing demand, and trends suggest most allocations will be done in Europe due to its faster development in this field compared to other regions. However, there is no easy way to estimate how quickly that demand will grow. In my view, we can expect more spectrum assigned, mostly for PtP links in the traditional 26 GHz and 28 GHz. However, as new licenses come to occupy these bands, other choices will be needed to satisfy increasing demand.

In this sense, it would be good to expand the backhaul market to other latitudes, particularly PtMP. Even though these links are allowed in many countries, they are actually used – although intensively in some cases – just in a few of them, as can be observed in Graph 2. Both carriers and vendors would need to approach this situation with the idea that there is room for more PtMP licenses to be allocated, and even more in higher spectrum bands. From the seven bands analyzed, 42 GHz seems to be an attractive alternative as it could be used for Point to Multipoint, and some vendors are pushing hard with regulators to get it available to backhaul Small Cells. In the end, this could be a suitable solution for the question of Metrocells. 

Fore more information on the Backhaul Regulatory Database, please download the brochure.

About Maravedis-Rethink

Maravedis-Rethink is a premier wireless infrastructure analyst firm. We help customers with reliable, unbiased and timely market analysis in the wireless infrastructure industry.  We focus on broadband wireless infrastructure (including LTE, carrier WiFi, small cells, core network and wireless backhaul) as well as industry spectrum regulations and operator trends.