Multi-Beam Former

Status: Mature

Introduction

Beam-forming is the technique of combining the information of an array of antennas in order to create a single beam with higher gain and lower beamwidth of what one of those antennas could have achieved. By electronically changing the phase of the signal at the moment of combination, one can steer the direction of the beam without physically moving the antenna array. This technique have found many applications in radar system and modern 5G communication.

The phase changing operation can be done in the analog domain or in the digital domain, but in the latter one can take advantage of the capabilities of parallel digital systems (FPGAs), to achieve, for example, multiple beam forming simultaneously. In this project, a digital, frequency domain, beam-former is implemented in ROACH2. The first iteration of this project achieved 3 simultaneous beams at 5.8GHz with a bandwidth of ~35MHz. A latter iteration of the project extended it to 16 simultaneous beams and 40MHz bandwidth.

Documentation

• Information on the ADC (16 inputs, 250MSPS) used for the project:

  • https://casper.ssl.berkeley.edu/wiki/ADC16x250-8

  • https://casper.ssl.berkeley.edu/wiki/ADC16x250-8_coax_rev_2

• Francisco Casado's engineer thesis on the project: http://repositorio.uchile.cl/handle/2250/151287

Code and Models

• ROACH2 models and bofs (no scripts) for 3 beams, 16 beams and 64 beams (16 beams multiplexed in time 4 times): https://github.com/FrancoCalan/simulink_models/tree/master/Multi_Beam_Former/ROACH2

• ROACH2 64 beams model (16 beams multiplexed in time 4 times) bofs and scripts standalone repository: https://github.com/FrancoCalan/Radiovision-ROACH