Since Anatel’s (National Telecommunications Agency) proposal for the 5G spectrum tender was known, the sum of pitfalls up to reaching the last report of the regulator's Spectrum and Orbits Committee, seems to have delivered the final blow: The tender could only be carried out in early 2021, although this cannot be assured at this point either.
After learning about the large number of opinions issued by almost all the members of the Brazilian telecommunications market, it became difficult to reconcile the interests defended by each sector. In any case, one of these proposals did not offer major objections and was accepted by the majority: in the 3.5 GHz band, 400 MHz would be tendered nationally in four batches of 100 MHz each, while for regional batches would reserve 40 MHz or 60 MHz.
However, that point of agreement seems to be behind us after the report of the Spectrum Committee was known. Based on two internal studies on the coexistence between 5G mobile systems (IMT-2020) in the 3.5 GHz band and the Fixed Satellite Service (FSS), in band C, revealed that the tests carried out with different filters did not give the expected results to mitigate the interferences and, therefore, recommend a series of actions. These include the need to implement a guard band of at least 20 MHz or a dynamic of 40 MHz to solve the problem. Thus, the availability of 400 MHz in that band disappears, to be used for 5G technology.
In detail, the Anatel report points out that the coexistence of both systems free of harmful interference requires combined solutions, since the synergy between them and the possibility of greater efficiency in the mitigation effort were demonstrated.
Regarding solutions and coexistence techniques, the document recommends to adopt more rigid operational conditions for IMT-2020, compared to those suggested as a reference by the 3GPP (3rd Generation Partnership Project- which is in charge of the 5G standards) , as it has been done in other countries.
In this framework, the need to establish these guard bands, mentioned above, between the two radio communication systems is pointed out and, as an example, points out that a 20 MHz guard band was adopted in the United States, although in some cases a dynamic band of 40 MHz can be used. The use of these guard bands facilitates the coexistence of the two systems and considerably reduces the need for more invasive solutions such as the geographical separation of several kilometers, decreased operating powers and the replacement of equipment and devices like tuners, waveguide filters and others.
As for the LNBF (Low Noise Block Feedhorn) devices tested to mitigate interference - a solution proposed by large operators through SindiTelebrasil - the work indicates that in the tests carried out they did not perform as expected. Nevertheless, it states that the development of new devices that can adequately fulfill this function is possible, for which these new devices should be more robust and allow an aggregate interference of less than 25 dBm (decibel milliwatt), if cost production allows it.
Nevertheless, there is also another solution that was analyzed at the time, which is the migration of all open satellite television that is now in the C band, for it to operate in the Ku band satellite, but it has an almost insurmountable barrier: its cost is estimated at US$ 540 million and the winning operators of lots would not be willing to carry out this disbursement.
The possibility of refarming bands currently occupied by 4G is also contemplated, as proposed by the head of the Anatel, Leonardo Euler de Morais, in the frequencies of 700 MHz, 1.8 GHz and 2.1 GHz, among others, as other countries are analyzing.
In this way, Anatel must surely make a general reformulation of the composition of the lots to be tendered and see how to achieve an efficient deployment of the new technology. It will also have some impact on negotiations (despite having been denied by authorities) the possibility that finally only three major mobile operators will compete, if the sale of Oi's mobile business to the association formed by Vivo and TIM for this operation. Everything is at stake and the end is still open more than ever.