5G Antennas in a Nutshell

5G takes advantage of sophisticated SDMA (Spatial Diversity Multiplexing Access) technique to reuse the time/frequency resources available in the communication channel.

In the following you can have a fast look at some antenna technologies adopted for SDMA in 5G. More information are available in the other Sections of this site

Basically, a MIMO antenna is a 'standard' antenna whose pattern is modulated by data.

Loosely speaking, information transmission is based on 'surprise'. Every time we receive something unexpected, we gain information.

The field radiated by a "standard" antenna has a known spatial configuration in far-field. The standard far-field antenna parameters, as Directivity, Gain, radiation pattern and so on, are a direct consequence of the single spatial configuration of the field.

In MIMO antenna using spatial multiplexing we have more than one possible pattern. Consequently, the receiver does not know which 'pattern' will be used. Only when the incident field impinges on the receiving antenna, the specific pattern is identified. Each pattern is associated to a different piece of information. Consequently, transmission on N bits requires a set a 2^N patterns. In 5G, the set of pattern is used to transmit more symbol.

Simple, smart, intriguing...

In this movie you can see and example of how the pattern is modified according to the transmitted information in case of a QPSK constellation using 2 MIMO channels.

(more information in the "Paper-Information and Electromagnetic" section on the site.)

A Multi-user MIMO (MU-MIMO) antenna connects more than one user at the same time and using the same frequency band. So, instead of having only one beam, the antenna has multiple beams.

The field radiated by a MU-MIMO antenna connecting four users (circles) in a scattering environment (rhombs)

(more information in the "Paper-Information and Electromagnetic" section on the site.)

Massive MIMO antennas are antenna with a lot of radiating elements. The ability to concentrate the radiated energy in the space depends on the number of elements of the antenna: more elements, larger the antenna in terms of wavelengths. The use of larger antennas reduces the probability of 'overlapping' of the beams associate to different users, allowing to transmit information using same frequency bands and time slots with low interference.