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Age of Information-Aware Cognitive Shared Access Networks with Energy Harvesting

Georgios Smpokos, Dionysis Xenakis, Marios Kountouris, Nikolaos Pappas

TL;DR

This work addresses AoI optimization in a cognitive shared network with energy harvesting, where secondary transmitters harvest energy and opportunistically access the channel under a guard-zone protection around the primary receiver. It combines stochastic geometry (PPP) for spatial deployment and DTMCs for battery dynamics to derive the primary AoI under FCFS, Queue-with-Replacement, and Generate-at-Will policies, linked through the primary service rate $mu_p$ and the interference-aware SINR expression. Key contributions include analytical expressions or tight approximations for AoI under all three policies, characterization of energy-state probabilities, and practical insights into how $r_{eh}$ and $r_{gz}$ shape AoI and secondary throughput in EH-enabled cognitive networks. The findings show that the Generate-at-Will policy consistently yields the lowest AoI, highlighting important trade-offs between energy harvesting, interference management, and information freshness in shared wireless environments.

Abstract

This study investigates a cognitive shared access network with energy harvesting capabilities operating under Age of Information (AoI) constraints for the primary user. Secondary transmitters are spatially distributed according to a homogeneous Poisson Point Process (PPP), while the primary user is located at a fixed position. The primary transmitter handles bursty packet arrivals, whereas secondary users operate under saturated traffic conditions. To manage interference and energy, two distinct zones are introduced: an energy harvesting zone around the primary transmitter and a guard zone around the primary receiver, within which secondary transmissions are prohibited. Secondary users access the channel probabilistically, with access decisions depending on their current battery state (charged or empty) and their location relative to the guard zone. Our objective is to analyze the primary user's AoI performance under three distinct packet management policies.

Age of Information-Aware Cognitive Shared Access Networks with Energy Harvesting

TL;DR

This work addresses AoI optimization in a cognitive shared network with energy harvesting, where secondary transmitters harvest energy and opportunistically access the channel under a guard-zone protection around the primary receiver. It combines stochastic geometry (PPP) for spatial deployment and DTMCs for battery dynamics to derive the primary AoI under FCFS, Queue-with-Replacement, and Generate-at-Will policies, linked through the primary service rate and the interference-aware SINR expression. Key contributions include analytical expressions or tight approximations for AoI under all three policies, characterization of energy-state probabilities, and practical insights into how and shape AoI and secondary throughput in EH-enabled cognitive networks. The findings show that the Generate-at-Will policy consistently yields the lowest AoI, highlighting important trade-offs between energy harvesting, interference management, and information freshness in shared wireless environments.

Abstract

This study investigates a cognitive shared access network with energy harvesting capabilities operating under Age of Information (AoI) constraints for the primary user. Secondary transmitters are spatially distributed according to a homogeneous Poisson Point Process (PPP), while the primary user is located at a fixed position. The primary transmitter handles bursty packet arrivals, whereas secondary users operate under saturated traffic conditions. To manage interference and energy, two distinct zones are introduced: an energy harvesting zone around the primary transmitter and a guard zone around the primary receiver, within which secondary transmissions are prohibited. Secondary users access the channel probabilistically, with access decisions depending on their current battery state (charged or empty) and their location relative to the guard zone. Our objective is to analyze the primary user's AoI performance under three distinct packet management policies.

Paper Structure

This paper contains 8 sections, 2 theorems, 21 equations, 5 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. Performance Analysis
  4. FCFS - Geo/Geo/1 Queue
  5. Queue with Replacement (QR)
  6. Generate-at-Will policy (GW)
  7. Numerical Analysis
  8. Conclusions

Key Result

Lemma 3.1

From the DTMC presented in Figure fig3, the steady-state probabilities are given by where $\rho = \frac{\lambda (1 - \mu_p)}{\mu_p (1 - \lambda)}$, $\pi_1 = \frac{\lambda (1 - \rho)}{\mu_p}$, $r = \lambda (1 - \mu_p)$, $s = \mu_p (1 - \lambda)$, and $\mu_p$ is given in equation (eq_mu_p).

Figures (5)

  • Figure 1: Two-state Discrete-Time Markov Chain (DTMC) modeling the ST battery state evolution.
  • Figure 2: DTMC representing the evolution of the Geo/Geo/1 queue at the PT.
  • Figure 3: DTMC modeling the queue evolution at the PT under the replacement policy. Here, $r = \lambda (1 - \mu_p)$ and $s = \mu_p (1 - \lambda)$.
  • Figure 4: Average AoI comparison among FCFS, QR, and GW as a function of the access probability $p_s$.
  • Figure 5: Average AoI behavior of the considered policies. Left: as a function of the access probability $p_s$ and the energy harvesting zone radius $r_{eh}$. Right: as a function of the access probability $p_s$ and the guard zone radius $r_{gz}$.

Theorems & Definitions (2)

  • Lemma 3.1
  • Lemma 3.2