Intelligent Reflecting Surface (IRS) vs. Backscatter: Key Differences

This page compares Intelligent Reflecting Surface (IRS) vs. Backscatter and mentions the difference between Intelligent Reflecting Surface (IRS) and Backscatter. Intelligent Reflecting Surface or metasurface is also known as Reconfigurable Intelligent Surface (RIS).

Intelligent Reflecting Surface (IRS) / Reconfigurable Intelligent Surface (RIS)

The RIS uses two-dimensional passive reflecting elements. These surfaces are also known as metasurfaces.

It works based on the modified Snell’s law principle.

RIS converts plane waves into scattered waves.

The elements of RIS are controlled by an RIS controller, which helps in controlling the delay/phase and polarization of scattered waves.

Figure 1 depicts RIS used in one such wireless network scenario. Metasurfaces are mainly used to serve subscribers who are blocked by any obstacles.

Backscatter

Image courtesy: arXiv (Ambient Backscatter Communications: A Contemporary Survey)

An ambient backscatter device communicates by absorption and reflection of RF signals. The device uses a harvesting circuit to convert received ambient RF energy into DC voltage. The charge is stored in a capacitor for its operation.

The harvester part also has a power management system that takes care of the utilization of stored power.

In a backscatter communication system, a device communicates by modulating the reflection of incident RF signals rather than generating its own RF signals. The ambient RF signal is received by the backscatter receiver part as shown.

Difference between Intelligent Reflecting Surface and Backscatter

The following table mentions similarities and differences between Intelligent Reflecting Surface (IRS) and Backscatter.