ECE 445S Real-Time Digital Signal Processing Laboratory - Lecture 16 - Announcements

Announcements: Cellular Basestation Design

• 4G Basestations.
  • 360-degree view broken into three sectors
  • One RF processing chain for each antenna element.
  • Each sector has up to 8 antenna elements with 8 RF chains
  • Uses transmission bands below 6 GHz
  • Bands are 1.4, 3, 5, 10, 15, or 20 MHz wide
  • Up to five bands aggregated (up to 100 MHz width)
  • Data converters: sampling rate up to 200 MHz and 10-12 bits of resolution.
• 5G Basestations Using 4G Approach.
  • Use 4G bands below 6 GHz and millimeter bands
  • Millimeter bands (24/28/37/39/47 GHz) have about 1 GHz bandwidth
  • Transmission in multiples of 100 MHz
  • To overcome high propagation losses, digital beamforming (spatial filtering) combined with 60-100 antenna elements/sector to focus transmit power into 2-degree beams
  • Data converters have high power consumption due to high sampling rates and high resolution
  • One RF chain per antenna element would require too much power
• 5G Basestations Using Hybrid Beamforming.
  • Power consumption in data converters exponential in number of bits
  • Hybrid beamforming split effort across analog and digital domains
    • passive analog beamforming combines (averages) outputs of each group of 10 antenna elements into one RF signal to improve SNR
    • an RF chain is applied to each RF signal
    • reduces power consumption by a factor of 10
  • Use low-resolution data converters (4-6 bits) to reduce power further

Last updated 11/16/22. Send comments to bevans@ece.utexas.edu