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Emergent Cooperation for Energy-efficient Connectivity via Wireless Power Transfer

Winston Hurst, Anurag Pallaprolu, Yasamin Mostofi

TL;DR

The paper tackles energy-constrained, non-cooperative UEs acting as relays to help a blocked source-AP link by using wireless power transfer as an RF-native payment. It introduces a Myerson auction-based cooperation protocol, proving valuation regularity under lognormal fading and enabling a simple bisection search to find the optimal source transmit power. The approach yields substantial practical gains: significant outage reductions with few relay candidates and meaningful source power savings compared to baselines, validated through simulations with real-world parameters. Overall, the work enables emergent, energy-efficient cooperative relaying in wireless networks without requiring monetary exchange, relying instead on wireless power as a coordination currency.

Abstract

This paper addresses the challenge of incentivizing energy-constrained, non-cooperative user equipment (UE) to serve as cooperative relays. We consider a source UE with a non-line-of-sight channel to an access point (AP), where direct communication may be infeasible or may necessitate a substantial transmit power. Other UEs in the vicinity are viewed as relay candidates, and our aim is to enable energy-efficient connectivity for the source, while accounting for the self-interested behavior and private channel state information of these candidates, by allowing the source to ``pay" the candidates via wireless power transfer (WPT). We propose a cooperation-inducing protocol, inspired by Myerson auction theory, which ensures that candidates truthfully report power requirements while minimizing the expected power used by the source. Through rigorous analysis, we establish the regularity of valuations for lognormal fading channels, which allows for the efficient determination of the optimal source transmit power. Extensive simulation experiments, employing real-world communication and WPT parameters, validate our theoretical framework. Our results demonstrate over 71% reduction in outage probability with as few as 4 relay candidates, compared to the non-cooperative scenario, and as much as 70% source power savings compared to a baseline approach, highlighting the efficacy of our proposed methodology.

Emergent Cooperation for Energy-efficient Connectivity via Wireless Power Transfer

TL;DR

The paper tackles energy-constrained, non-cooperative UEs acting as relays to help a blocked source-AP link by using wireless power transfer as an RF-native payment. It introduces a Myerson auction-based cooperation protocol, proving valuation regularity under lognormal fading and enabling a simple bisection search to find the optimal source transmit power. The approach yields substantial practical gains: significant outage reductions with few relay candidates and meaningful source power savings compared to baselines, validated through simulations with real-world parameters. Overall, the work enables emergent, energy-efficient cooperative relaying in wireless networks without requiring monetary exchange, relying instead on wireless power as a coordination currency.

Abstract

This paper addresses the challenge of incentivizing energy-constrained, non-cooperative user equipment (UE) to serve as cooperative relays. We consider a source UE with a non-line-of-sight channel to an access point (AP), where direct communication may be infeasible or may necessitate a substantial transmit power. Other UEs in the vicinity are viewed as relay candidates, and our aim is to enable energy-efficient connectivity for the source, while accounting for the self-interested behavior and private channel state information of these candidates, by allowing the source to ``pay" the candidates via wireless power transfer (WPT). We propose a cooperation-inducing protocol, inspired by Myerson auction theory, which ensures that candidates truthfully report power requirements while minimizing the expected power used by the source. Through rigorous analysis, we establish the regularity of valuations for lognormal fading channels, which allows for the efficient determination of the optimal source transmit power. Extensive simulation experiments, employing real-world communication and WPT parameters, validate our theoretical framework. Our results demonstrate over 71% reduction in outage probability with as few as 4 relay candidates, compared to the non-cooperative scenario, and as much as 70% source power savings compared to a baseline approach, highlighting the efficacy of our proposed methodology.
Paper Structure (17 sections, 3 theorems, 10 equations, 3 figures)

This paper contains 17 sections, 3 theorems, 10 equations, 3 figures.

Table of Contents

  1. Introduction
  2. System Model and Motivation
  3. Communication System Model
  4. Wireless Power Transfer
  5. Information Assumptions
  6. Problem Formulation
  7. Bayesian Reverse Auction Formulation
  8. Formal Problem Statement
  9. Solution via Myerson Auctions
  10. Buyer-Optimal Reverse Auctions
  11. Optimal WPT Auction
  12. Numerical Examples
  13. Outage Probability
  14. Source Transmit Power
  15. Harvested Transmission Power
  16. ...and 2 more sections

Key Result

Lemma 1

If all bidder valuations are independently distributed according to regular distributions, $f_i$, then for an auction with valuations $v=\{v_i\}_{i=0}^n$, the revenue-maximizing mechanism for a reverse auction is given by and with $z(i) = \sup \{s\,|\,c_i(s)<v_0\, \text{ and }\, c_{i}(s)< c_j(v_j),\ \forall j\neq i\}$

Figures (3)

  • Figure 1: Fundamental scenario considered in this work: A single source UE attempts to communicate with a blocked AP using one of the $n$relay candidate UEs, incentivizing cooperation with wireless power transfer.
  • Figure 2: Sample simulation results: (a) Consistent reduction in outage probability with a Myerson auction-based relay selection, incentivized by WPT for (left) various values of WPT circuitry efficiency, $\alpha$ with $\Gamma = 1$ and (right) several scales of small-scale fading variance, $\Gamma$ with $\alpha=0.3$. (b) Higher relative source power savings of the Myerson mechanism with increasing number of relay candidates (c) Variation in harvested power with WPT efficiency ($\alpha$) as the number of relay candidates grows, with an overall reduction due to higher source power savings. See color PDF for optimal viewing.
  • Figure 3: (a) Sample placement of UEs for candidate selection study (b) Variation in selection likelihood across several scales ($\Gamma$) of fading. See color PDF for optimal viewing.

Theorems & Definitions (7)

  • Lemma 1
  • proof
  • Lemma 2
  • proof
  • Corollary 1
  • proof
  • Remark 1