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 23GHz bands have begun to saturate.
This potential spectrum crunch for small cell backhaul presents mobile service providers with the necessity of choosing between other alternatives, of which the 10.5GHz, 26GHz and 28GHz 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 wave bands (30GHz-3000GHz) which are currently little used. These lower bands are the most active in most markets, according to Maravedis-Rethink’s Backhaul Regulatory Database, encompassing 64 countries and seven frequency bands, with information provided directly by regulators.
Currently, 10.5GHz 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 do so, mainly on a point-to-point (PtP) basis. Even though point-to-multipoint (PtMP) links are allowed in these countries, they are actually used in only two.
The 26GHz and 28GHz bands are also being used widely for PtP, and to a lesser extent for PtMP, to backhaul mobile services. 26GHz accounts for the largest number of active links in the countries analyzed, distributed among 25 countries for PtP and five for PtMP. Similarly, 28GHz is being used for PtP and PtMP in 13 and two 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 28GHz — is their lesser susceptibility to attenuation due to rain effects, compared to higher (millimeter) bands. However, there is a drawback, particularly in 10.5GHz, where regulators often focus on Fixed Wireless Access (FWA) usage (in 15 countries from different regions). In addition, if demand trends in 26GHz and 28GHz continue upward, both 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 42GHz band, or Colombia and Qatar, which have regulated V-Band (57-64GHz). The majority, though, have no regulation at all in any of the millimeter bands.
Another issue is whether unlicensed bands could reduce costs and congestion. This is a hot topic in the industry, especially for vendors interested in developing solutions for unlicensed spectrum. However, there are only six 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 networks is tough. We can expect more spectrum to be assigned, mostly for PtP links in the traditional 26GHz and 28GHz bands. However, as new licences come to occupy these bands, other choices will be needed to satisfy increasing demand.
For this reason, it would be good to expand the backhaul market to other topologies, particularly PtMP. Even though these links are allowed in many countries, they are actually used in only a few. Both carriers and vendors need to work on the basis that there is room for more PtMP licences to be allocated, and even more in higher spectrum bands. Of the seven options analyzed, 42GHz seems to be an attractive alternative as it can be used for PtMP, and some vendors are pushing hard with regulators to get it available to backhaul Small cells.
This analysis was contributed by Luis Reyes, spectrum analyst at Maravedis-Rethink, which has created a unique Backhaul Regulatory Database and associated services. For more information, please contact Adlane Fellah on [email protected].