# Energy Efficiency of Opportunistic Device-to-Device Relaying Under Lognormal Shadowing

## TL;DR

This paper analyzes the energy efficiency of opportunistic device-to-device relaying in wireless networks under log-normal shadowing, deriving bounds and demonstrating improvements over direct transmission through analytical and simulation results.

## Contribution

It introduces an analytical framework for evaluating energy consumption in opportunistic D2D relaying considering shadowing and circuit energy, showing energy savings over direct transmission.

## Key findings

- Protocol reduces energy consumption compared to direct transmission.
- Analytical bounds and scaling laws for energy use are derived.
- Simulations confirm the protocol's effectiveness in realistic scenarios.

## Abstract

Energy consumption is a major limitation of low power and mobile devices. Efficient transmission protocols are required to minimize an energy consumption of the mobile devices for ubiquitous connectivity in the next generation wireless networks. Opportunistic schemes select a single relay using the criteria of the best channel and achieve a near-optimal diversity performance in a cooperative wireless system. In this paper, we study the energy efficiency of the opportunistic schemes for device-to-device communication. In the opportunistic approach, an energy consumed by devices is minimized by selecting a single neighboring device as a relay using the criteria of minimum consumed energy in each transmission in the uplink of a wireless network. We derive analytical bounds and scaling laws on the expected energy consumption when the devices experience log-normal shadowing with respect to a base station considering both the transmission as well as circuit energy consumptions. We show that the protocol improves the energy efficiency of the network comparing to the direct transmission even if only a few devices are considered for relaying. We also demonstrate the effectiveness of the protocol by means of simulations in realistic scenarios of the wireless network.