Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Applicability of existing CSI acquisition methods to different categories of RISs.
| Hyrbid RIS | |||
|---|---|---|---|
| CSI acquisition method | IRS/active RIS | Selection type | Beamforming type |
| Implicit CSI acquisition | Preferable | Not necessary | Not necessary |
| Double link channel separation | Preferable | Not necessary | Not necessary |
| Cascaded channel estimation | Preferable | Not necessary | Not necessary |
| Individual channel estimation | Conditional | Preferable | Preferable |
