Difference between Intelligent Reflecting Surface and Backscatter

This page compares Intelligent Reflecting Surface Vs Backscatter and mentions 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)

Reconfigurable Intelligent Surface RIS in wireless network

The RIS uses two dimensional passive reflecting elements. These surfaces are also known as metasurfaces. It works based on modified snell's law principle. RIS converts plane waves into scattered waves. The elements of RIS are controlled by RIS controller which helps in controlling delay/phase and polarization of scattered waves. The figure-1 depicts RIS used in one such wireless network scenario. Metasurfaces are mainly used to serve subscribers which are blocked by any obstacles. Refer Reconfigurable Intelligent Surface based cell free network architecture for more information.


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

An ambient backscatter device communicates by absorption and reflection of RF signals. The device uses harvesting circuit to convert received ambient RF energy into DC voltage. The charge is being stored in capacitor for its operation. The harvester part also has power management system which takes care of utilization of stored power. In backscatter communication system, device communicates by modulating reflection of incident RF signals rather than having generation of its own RF signals. Ambient RF signal is received by backscatter receiver part as shown. Refer ambient backscatter architecture >> and advantages/disadvantages of ambient backscatter >>.

Difference between Intelligent Reflecting Surface and Backscatter

Following table mentions similarities and difference between Intelligent Reflecting Surface (IRS) and Backscatter.

Parameters RIS (Reconfigurable Intelligent Surface) Backscatter
Operating mechanism Passive/active reflection Passive Reflection
Duplex Full Full
Number of transmit RF chains required Zero Zero
Hardware cost Low Very Low
Energy consumption Low Very Low

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