PETAR: A Predictive Energy and Trust-Aware Secure Routing Protocol for Energy-Efficient Wireless Sensor Networks in Smart Healthcare and Urban Monitoring

Technical Summary: PETAR – A Predictive Energy and Trust-Aware Secure Routing Protocol

Problem Statement
Wireless Sensor Networks (WSNs) are pivotal for real-time data collection in smart healthcare and urban monitoring systems. However, these networks face critical limitations that hinder their deployment in sustainable environments. The primary challenges identified are:

1. Energy Constraints: Sensor nodes operate on limited battery power that cannot be easily replaced, directly impacting network lifetime and reliability.
2. Security Vulnerabilities: Open deployment environments expose networks to data interception, node capture, and malicious attacks, which is particularly critical for sensitive healthcare data.
3. Fragmented Solutions: Existing research often addresses energy efficiency and security as separate issues. Traditional protocols (e.g., LEACH, PEGASIS) focus on energy but lack robust security, while security-focused models often compromise network efficiency. There is a lack of integrated frameworks that simultaneously optimize energy consumption, routing stability, and data security.

Methodology: The PETAR Framework
The paper proposes PETAR (Predictive Energy and Trust-Aware Secure Routing), a unified framework designed to enhance energy efficiency, network stability, and security. The methodology operates through the following phases:

• Predictive Energy Estimation: Unlike traditional methods that rely solely on current residual energy, PETAR forecasts the future energy levels of nodes based on their consumption patterns across sensing, processing, and communication stages. Nodes with higher predicted energy are prioritized for critical roles.
• Trust Evaluation Mechanism: To ensure security, the protocol assigns a trust value to neighboring nodes based on behavioral metrics, including packet forwarding rates, communication consistency, cooperation levels, and packet loss. Nodes with trust values below a specific threshold are excluded from routing and cluster head (CH) candidacy.
• Hybrid Cluster Head (CH) Selection: CHs are elected using a hybrid metric that combines predicted residual energy, trust value, distance to the Base Station (BS), and communication capability. This ensures that only reliable and energy-efficient nodes manage cluster data.
• Adaptive Cluster Rotation: To prevent rapid energy depletion of CHs, the protocol dynamically rotates CH roles. If a CH's energy drops below a rotation threshold, a new CH is selected from the remaining cluster members.
• Secure Data Aggregation and Dual-Path Routing:
  • Aggregation: CHs aggregate data from member nodes to remove redundancy and compress information before transmission.
  • Encryption: A lightweight encryption technique is applied to maintain data confidentiality and integrity.
  • Dual-Path Routing: The protocol establishes two communication paths (primary and secondary) between the CH and the BS. The primary path is selected based on a cost function involving energy, trust, and distance. If the primary path fails, the system automatically switches to the backup path, enhancing fault tolerance.

Key Contributions

1. Integrated Framework: PETAR uniquely integrates predictive energy modeling, trust-aware node evaluation, and dual-path secure routing into a single protocol, addressing the gap where energy and security are usually treated separately.
2. Predictive Energy Modeling: The shift from reactive (current energy) to predictive (future energy) node evaluation allows for more proactive and balanced cluster head selection.
3. Trust-Based Security: The inclusion of a dynamic trust evaluation system specifically targets malicious or unreliable nodes without relying solely on heavy cryptographic overhead, making it suitable for resource-constrained WSNs.
4. Fault Tolerance: The dual-path routing mechanism ensures continuous data transmission even in the event of node failure or path disruption.

Results and Performance Evaluation
The PETAR algorithm was evaluated using MATLAB simulations in a 100m × 100m area with 100 sensor nodes, benchmarked against LEACH, PEGASIS, Energy-Aware Routing, and AI-based routing protocols. The simulation results indicate that PETAR outperforms existing protocols across all key metrics:

• Network Lifetime: PETAR achieved a maximum of 2,100 rounds, significantly higher than LEACH (1,200) and PEGASIS (1,400).
• Residual Energy: The protocol maintained a higher residual energy level of 13.8 J compared to 8.2 J for LEACH.
• Packet Delivery Ratio (PDR): PETAR achieved a 96% delivery ratio, surpassing the 82–91% range of other protocols.
• Throughput: The system reached a throughput of 3,500 kbps, compared to 2,200 kbps for LEACH.
• End-to-End Delay: PETAR reduced latency to 420 ms, a notable improvement over the 820 ms observed in LEACH.
• Node Longevity: The protocol sustained a higher number of active nodes for a longer duration, contributing to overall network stability.

Significance
The paper posits that PETAR offers a robust solution for the specific demands of smart healthcare and sustainable urban monitoring. By simultaneously optimizing energy consumption and securing data transmission, the protocol extends the operational lifetime of sensor networks while ensuring the reliability required for critical applications. The authors conclude that PETAR is well-suited for deployment in environments where energy efficiency and data security are of equal importance, thereby supporting the development of smarter, safer, and more sustainable cities and healthcare systems.