Reconfigurable intelligent surface-assisted N-ary Alamouti

Area of Science:

• Wireless Communications
• Information Theory
• Signal Processing

Background:

• Reconfigurable intelligent surfaces (RIS) are emerging as a key technology for future wireless networks.
• Existing RIS-assisted Alamouti (RIS-Alamouti) schemes offer a foundation for improved wireless transmission.
• The conventional Alamouti scheme, a basis for RIS-Alamouti, utilizes multiple transmit and receive antennas.

Purpose of the Study:

• To propose a novel Multiple-Input Multiple-Output (MIMO)-based scheme called the N-ary RIS-assisted Alamouti (N-RIS-Alamouti) scheme.
• To enhance spectral efficiency in RIS-assisted wireless communications.
• To maintain or improve error performance compared to existing RIS-Alamouti schemes.

Main Methods:

• The N-RIS-Alamouti scheme transmits additional information bits using N-ary phase shift keying (NPSK) symbols over four time slots.
• It models the NPSK symbol pair as an additional phase component of the channel.
• The scheme leverages MIMO configurations and RIS technology.

Main Results:

• The N-RIS-Alamouti scheme enhances spectral efficiency by transmitting additional bits per channel use without sacrificing reliability.
• Achievable spectral efficiency scales with the number of receive antennas.
• Simulations show 128-RIS-Alamouti and 256-RIS-Alamouti achieve comparable BER to RIS-Alamouti with additional bits transmitted (7 and 8 bits, respectively).

Conclusions:

• The N-RIS-Alamouti scheme offers a significant advancement in wireless communication efficiency.
• It provides a method to increase data rates through improved spectral efficiency.
• The scheme's performance benefits increase with a higher number of receive antennas.