Distributed Power Splitting for SWIPT in Relay Interference Channels using Game Theory (1408.3206v1)

Abstract: In this paper, we consider simultaneous wireless information and power transfer (SWIPT) in relay interference channels, where multiple source-destination pairs communicate through their dedicated energy harvesting relays. Each relay needs to split its received signal from sources into two streams: one for information forwarding and the other for energy harvesting. We develop a distributed power splitting framework using game theory to derive a profile of power splitting ratios for all relays that can achieve a good network-wide performance. Specifically, non-cooperative games are respectively formulated for pure amplify-and-forward (AF) and decode-and-forward (DF) networks, in which each link is modeled as a strategic player who aims to maximize its own achievable rate. The existence and uniqueness for the Nash equilibriums (NEs) of the formulated games are analyzed and a distributed algorithm with provable convergence to achieve the NEs is also developed. Subsequently, the developed framework is extended to the more general network setting with mixed AF and DF relays. All the theoretical analyses are validated by extensive numerical results. Simulation results show that the proposed game-theoretical approach can achieve a near-optimal network-wide performance on average, especially for the scenarios with relatively low and moderate interference.

• The paper demonstrates that using game theory, Nash Equilibria are achieved for both AF and DF relay protocols to optimize power splitting.
• It introduces a distributed iterative algorithm that converges rapidly, enabling each relay to locally compute optimal power splitting in interference channels.
• Numerical analysis confirms that the method significantly improves network data rates and energy harvesting efficiency in cooperative wireless systems.

Distributed Power Splitting for SWIPT in Relay Interference Channels Using Game Theory

The paper presents a methodical approach to solve the problem of simultaneous wireless information and power transfer (SWIPT) in relay interference channels. It addresses a system where multiple source-destination pairs communicate with the assistance of dedicated energy harvesting relays. The relays must split their received signals into streams for both information forwarding and energy harvesting. The paper applies game theory to develop a distributed power splitting framework, ensuring network-wide performance optimization through strategic game formation.

Problem and Approach

The problem is set within a relay interference channel framework, characterized by mutual interference due to multiple source-destination pairs utilizing the same spectral resources. The paper aims to determine optimal power splitting ratios that maximize network-wide performance, quantified by the sum of achievable rates across all links. Due to the inherent non-convexity, even centralized optimization struggles to efficiently compute global optima. Thus, the paper proposes a distributed solution using game theory.

The methodology involves modeling each source-relay-destination pair (link) as a strategic player in a non-cooperative game. Each player aims to optimize its allocated relay’s power splitting ratio to maximize its achievable rate. Games were formulated separately for amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols, as well as for hybrid networks with mixed relay strategies.

Key Findings and Results

1. Existence and Uniqueness of Nash Equilibria: The paper demonstrates the existence of Nash Equilibria in both AF and DF game formulations using the principles of game theory. Uniqueness is achieved through demonstrating that these games align with the standard function approach, ensuring convergence to a single equilibrium point.
2. Game-Theoretical Framework: The research provides detailed formulations, showing that at Nash Equilibrium, a link's power splitting decision does not change, given the power splitting decisions of other links remain constant. This results in a balance of conflicting objectives under mutual interference.
3. Distributed Algorithm: The paper introduces a distributed iterative algorithm with assured convergence to the Nash Equilibrium, allowing each relay to locally compute its best response with respect to current network states. The algorithm's efficiency and rapid convergence are confirmed through numerical simulations.
4. Numerical Validation: Extensive numerical analysis supports theoretical findings, indicating that the proposed game-theoretical frameworks achieve near-optimal performance, especially under scenarios with moderate inter-link interference.

Implications

The proposed distributed power splitting method enables efficient management of relay interference channels, promising advancements in cooperative communication systems with constrained energy resources. Particularly in wireless sensor networks and cellular networks, this approach provides a scalable solution to enhance lifetime and data rate performance, mitigating challenges posed by interference.

Future Directions

Potential developments include integrating dynamic power allocation techniques with the proposed game theoretical framework to optimize for changing channel conditions. Other avenues could involve advanced joint optimization of power control at the source and power splitting at relays, allowing for further system performance improvements.

Through its comprehensive analysis and proposed solutions, the paper contributes to a richer understanding of relay channel dynamics, showcasing the efficacy of game theory in resolving complex optimization problems in ICT infrastructure design.