Many people wonder if 5G networks operating in the millimeter band (tens of GHz) will gain in popularity due to the small range of base stations. Physics is unrelenting. The higher the frequency of the radio signal, the more it is suppressed. Fortunately, tests conducted for 28 GHz frequency show that 5G in the millimeter band makes sense. However, Nokia showed that you can also use the 90 GHz frequency for this purpose.
Why would operators want to use such high frequencies to build 5G networks? The bandwidth of radio devices is often expressed in percentages, which express the ratio of bandwidth to its center frequency. For example, a device that supports a bandwidth of 10% designed for 1 GHz can send a signal by 100 MHz channel. The same solution, but redesigned at 10 GHz, could transmit a signal occupying 1 GHz (i.e. 1000 MHz) of spectrum. A 10 times wider bandwidth means 10 times faster data transmission. As you guessed, 5G working on frequencies in the 28 GHz millimeter band will be much faster than systems using the 3700 MHz frequency. A higher band also means reservations for wider frequency blocks for a larger number of operators.
Nokia believes that 90 GHz is suitable for 5G as well as 28 GHz
Higher frequency radio waves are more susceptible to damping caused by bad weather conditions and all kinds of obstacles. Three times the frequency also means nine times greater attenuation due to the propagation of the wave under ideal conditions. However, the researchers from Nokia Bell Labs have an idea on how to solve this problem. For this purpose, a special antenna array system has been developed, which can be expanded to 256 radiating elements. As a result, the base station can radiate a concentrated electromagnetic beam directed towards the selected user. Thanks to such an approach, the higher attenuation of the radio signal is compensated by the higher directional gain of the base station antenna.
Higher frequency also means that individual elements that radiate such a large antenna are small. That’s why scientists working for Nokia could have developed such huge antenna array. The largest Japanese operator NTT DOCOMO is interested in the practical application of the new solution.