Simultaneous Information and Energy Transfer in Large-Scale Networks with/without Relaying (1310.6511v2)

Abstract: Energy harvesting (EH) from ambient radio-frequency (RF) electromagnetic waves is an efficient solution for fully autonomous and sustainable communication networks. Most of the related works presented in the literature are based on specific (and small-scale) network structures, which although give useful insights on the potential benefits of the RF-EH technology, cannot characterize the performance of general networks. In this paper, we adopt a large-scale approach of the RF-EH technology and we characterize the performance of a network with random number of transmitter-receiver pairs by using stochastic-geometry tools. Specifically, we analyze the outage probability performance and the average harvested energy, when receivers employ power splitting (PS) technique for "simultaneous" information and energy transfer. A non-cooperative scheme, where information/energy are conveyed only via direct links, is firstly considered and the outage performance of the system as well as the average harvested energy are derived in closed form in function of the power splitting. For this protocol, an interesting optimization problem which minimizes the transmitted power under outage probability and harvesting constraints, is formulated and solved in closed form. In addition, we study a cooperative protocol where sources' transmissions are supported by a random number of potential relays that are randomly distributed into the network. In this case, information/energy can be received at each destination via two independent and orthogonal paths (in case of relaying). We characterize both performance metrics, when a selection combining scheme is applied at the receivers and a single relay is randomly selected for cooperative diversity.

• The paper analyzes simultaneous information and energy transfer with power splitting in large networks using stochastic geometry, modeling non-cooperative and cooperative protocols.
• Analysis of the non-cooperative protocol yields closed-form expressions for outage and harvested energy, optimizing transmitted power under constraints.
• The cooperative protocol with dynamic relays (PPP) improves performance and utilizes RF interference beneficially for energy harvesting.

Overview of "Simultaneous Information and Energy Transfer in Large-Scale Networks with/without Relaying"

The paper by Ioannis Krikidis explores the utilization of energy harvesting (EH) via radio-frequency (RF) electromagnetic waves in large-scale communication networks. This approach addresses the energy efficiency challenges which are critical for sustainable communication systems, particularly as data traffic continues to grow. The paper uniquely employs stochastic geometry to characterize and optimize large-scale network configurations, moving beyond the more commonly analyzed small-scale structures.

Key Contributions

The paper focuses on the power splitting (PS) technique, which allows simultaneous information and energy transfer at the receivers. Two primary protocols are considered: a non-cooperative protocol and a cooperative protocol with relaying assistance.

1. Non-Cooperative Protocol: The analysis begins with a non-cooperative framework where each transmitter-receiver pair in the network operates independently. The paper delivers closed-form expressions for both the outage probability and the average harvested energy, allowing a detailed understanding of how the power splitting affects these metrics. Furthermore, an optimization problem is constructed to minimize transmitted power while meeting constraints for both outage probability and harvesting requirements. The explicit solutions provided underline the trade-offs between efficient energy usage and system reliability.
2. Cooperative Protocol: The subsequent examination involves a cooperative protocol incorporating dynamic relay nodes, modeled as a Poisson Point Process (PPP). This setup enhances the network's performance by allowing information and energy to be transferred via multiple independent paths through the network, which can significantly improve robustness against path-loss and fading. The paper innovatively models relay selection through a random selection process within a sectorized area, optimizing cooperative gains without the complexity of instantaneous channel state information.

Practical and Theoretical Implications

The findings of the paper are particularly relevant for the design of future 5G networks where energy efficiency equates to both extended network life and reduced operational costs. The rigorous mathematical treatment offers valuable insights into the trade-offs between outage performance and energy harvesting. Moreover, the cooperative protocol displays how relays can effectively transform RF interference into a beneficial asset for energy harvesting, enhancing the overall efficiency of the network.

Speculations for Future Developments

Future research could expand on this work by exploring more advanced relay selection mechanisms that could dynamically adjust to instantaneous network conditions and user demands. Additionally, integrating other advanced techniques, such as machine learning, to predict and optimize EH and information transfer efficiency in real-time could further refine system performance. Adapting these techniques within the paradigms of advanced MIMO systems and cognitive radio networks could yield insights into seamless spectrum and energy resource management.

Conclusion

The research offers a comprehensive analytical framework for simultaneous information and energy transfer in large-scale wireless networks. Through stochastic geometry, the paper derives meaningful insights into how large-scale networks can optimize their operations using RF energy harvesting. This work sets a foundation for subsequent research on energy-efficient communication systems and exemplifies the intricate balance between energy sustainability and communication reliability.