Achievable Rate Maximization for Multi-Relay AF Cooperative SWIPT Systems with a Nonlinear EH Model

Area of Science:

• Wireless communication systems
• Cooperative communication
• Simultaneous wireless information and power transfer (SWIPT)

Background:

• Multi-relay amplify-and-forward systems are crucial for extending wireless network coverage.
• Simultaneous wireless information and power transfer (SWIPT) enables energy harvesting at nodes, but receiver nonlinearities impact performance.
• Optimizing resource allocation in SWIPT systems with energy harvesting (EH) constraints is essential for maximizing data rates.

Purpose of the Study:

• To maximize the achievable information rate in multi-relay SWIPT systems considering nonlinear EH circuits.
• To analyze and compare the performance of time switching (TS) and power splitting (PS) schemes under nonlinear EH conditions.
• To derive optimal resource allocation strategies and achievable rates for both TS and PS schemes.

Main Methods:

• Formulation of achievable rate maximization problems as convex and non-convex optimization problems for TS and PS schemes, respectively.
• Development of efficient algorithms to solve the optimization problems and obtain optimal TS/PS ratios and maximum achievable rates.
• Asymptotic analysis of maximum achievable rates at low and high signal-to-noise ratios (SNRs).

Main Results:

• Optimal TS and PS ratios and maximum achievable rates were obtained using efficient algorithms.
• The nonlinear EH model provides significant performance gains for the TS scheme compared to the linear model.
• The PS scheme is more sensitive to relay location and channel variations, while the TS scheme is more sensitive to resource allocation mismatches.

Conclusions:

• The nonlinear EH model significantly enhances the performance of the TS scheme in multi-relay SWIPT systems.
• The choice between TS and PS schemes depends on system sensitivities to location, channel parameters, and resource allocation.
• Efficient algorithms can optimize SWIPT systems with nonlinear EH, leading to improved information rates.