ECE 445S Real-Time Digital Signal Processing Laboratory - Lecture 16 - Announcements
Prof. Brian L. Evans
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.
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bevans@ece.utexas.edu