6G  

 

 

 

 

 

6G Antenna

 

As you may understand, the size of the most of RF components is inversally proportional to the frequency of the operating frequency. In other words, the size of the RF components gets smaller as the operating frequency increases. Antenna elements (single antenna) would be the components that best complies to this rule.

Considering very high operating frequency of 6G, we would easily guess that the size of an antenna elements would be very small.

 

The size of single dipole antenna element on PCB working at 1 Thz can be only 150 um and the size of graphene antenna (or any other antenna made of plasmonic materials) can be even smaller - e.g, 1umlong /10nm wide (Ref [1]).

This small size can be beneficial in that it can be applicable for on-chip communication or wearable communication but the small aperture would be limiting factor in terms of transmission power.

 

To overcome the power limi due to small aperture, multiple antenna elements in an array format is likely to be the one being used in real communication system (same logic as we use massive MIMO in 5G).

  • metallic antenna (like PCB antenna) arrays utilized in conjunction with electronic front-ends have been demonstrated at frequencies under 300 GHz with up to 16 controllable elements.  (Ref [1]).
  • in conjunction with plasmonic front-ends, very large graphene-based plasmonic antenna arrays with up to 1,024 elements have been proposed (this may be called as ultra-massive MIMO)  (Ref [1]).

 

 

 

MIMO/BeamForming Implementation

 

Thanks to the very small size of the antenna elements in the 6G frequency range enables huge number of antenna elements (array, e.g, 1024, 4096 or higher) can be integrated into Tx and Rx chipset. With this number of antenna elements, it would be easier to more sophisticated / accurate MU MIMO.

 

As in 5G FR2, it is highly likely that Hybrid Beamforming will be used in 6G as well. For the analog precoder part in the hybrid beamforming, usually two different types are used : Fully-Connected or Array of Subarrays (I think the array of subarray type is more commonly used). In 6G with utilizing much larger number of antenna elements, we can think of another types for the analog precoder part called dynamic array-of-subarrays which can change the configuration of the sub-arrays dinamically as illustrated below.

 

Source : Terahertz Band Communication: An Old Problem Revisited and Research Directions for the Next Decade

 

 

 

Reference

 

[1] Terahertz Band Communication: An Old Problem Revisited and Research Directions for the Next Decade

[2] Hera-X : Deliverable D2.1 Towards Tbps Communications in 6G: Use Cases and Gap Analysis

[3] ETSI GR mWT 022 V1.1.1 (2021-04)

[4] WHITE PAPER ON RF ENABLING 6G OPPORTUNITIES AND CHALLENGES FROM TECHNOLOGY TO SPECTRUM

[5] Roadmap to 6G