Threshold-Based User-Assisted Cooperative Relaying in Beamspace Massive MIMO NOMA Systems

Area of Science:

• Wireless Communications
• Signal Processing
• Information Theory

Background:

• Millimeter wave (mmWave) communications face coverage limitations.
• Massive MIMO (mMIMO) and NOMA offer potential solutions but require optimization.
• User-assisted cooperative relaying can extend coverage and improve efficiency.

Purpose of the Study:

• To propose and evaluate a threshold-based user-assisted cooperative relaying scheme in a beamspace mMIMO NOMA system.
• To enhance spectral and energy efficiency for mobile user terminals (MUTs), especially at the cell edge.
• To analyze the outage probability for cell-edge MUTs.

Main Methods:

• Implementing threshold-based relaying where intermediate MUTs relay signals upon meeting an SINR threshold.
• Utilizing a zero-forcing (ZF) precoder and iterative power allocation to minimize interference.
• Deriving an analytic expression for the outage probability of the cell-edge MUT.

Main Results:

• The proposed scheme significantly improves spectral and energy efficiency compared to existing systems.
• Outage probability for cell-edge MUTs is analyzed and an expression is derived.
• Performance gains are demonstrated in a delay-intolerant cell-edge scenario.

Conclusions:

• Threshold-based user-assisted cooperative relaying is an effective strategy for beamspace mMIMO NOMA systems.
• The proposed system offers superior performance in terms of spectrum efficiency, energy efficiency, and outage probability.
• This approach is particularly beneficial for extending coverage and reliability in mmWave communications.