Energy-Efficient Rate Splitting for MIMO STAR-RIS-Assisted Broadcast Channels with I/Q Imbalance

• Published in: 2023 31st European Signal Processing Conference (EUSIPCO) pp. 1504 - 1508
• Main Authors: Soleymani, Mohammad, Santamaria, Ignacio, Jorswieck, Eduard
• Format: Conference Proceeding
• Language: English
• Published: EURASIP 04.09.2023
• Subjects: Energy efficiency; improper Gaussian signaling; Interference; majorization minimization; MIMO broadcast channels; rate splitting; Receivers; reflecting intelligent surface; Signal processing; Stars; Transceivers; Transmitters
• ISSN: 2076-1465
• DOI: 10.23919/EUSIPCO58844.2023.10289964

Ahstract- This paper proposes an energy-efficient scheme for multi cell multiple-input, multiple-output (MIMO) simultaneous transmit and reflect (STAR) reconfigurable intelligent surfaces (RIS)-assisted broadcast channels by employing rate splitting (RS) and improper Gaussian signaling (IGS). Regular RISs can only reflect signals. Thus, a regular RIS can assist only when the transmitter and receiver are in the reflection space of the RIS. However, a STAR-RIS can simultaneously transmit and reflect, thus providing a 360° coverage. In this paper, we assume that transceivers may suffer from I/Q imbalance (IQI). To compensate for IQI, we employ IGS. Moreover, we employ RS to manage intracell interference. We show that RIS can significantly improve the energy efficiency (EE) of the system when RIS components are carefully optimized. Additionally, we show that STAR-RIS can significantly outperform a regular RIS when the regular RIS cannot cover all the users. We also show that RS can highly increase the EE comparing to treating interference as noise.