QoS-Aware VoIP Support in WMNs via PSO-Based Multi-Level Node Monitoring

Wireless Mesh Networks (WMNs) provide low-cost, self-organizing and self-healing connectivity, but multi-hop interference, hidden-node effects and unbalanced load make delay-sensitive Voice over Internet Protocol (VoIP) communication difficult to support. This paper presents a Particle Swarm Optimization (PSO)-driven node monitoring and traffic scheduling framework for QoS-aware VoIP in WMNs. In the revised method, multi-level monitoring is explicitly defined through three measurable levels: node-state monitoring (identifier, residual energy and queue occupancy), link-quality monitoring (delivery probability, loss, delay and interference), and traffic/QoS monitoring (VoIP classification and priority scheduling). These normalized features are combined in a dimensionally consistent PSO fitness function that jointly maximizes packet delivery ratio and residual energy while minimizing delay, packet loss and hop count. A MATLAB-based discrete-event simulation was conducted for WMNs with 50-300 nodes, bidirectional CBR/UDP VoIP flows, IEEE 802.11 CSMA/CA access and common channel/interference assumptions. Under the modeled conditions, the proposed PSO-MLNM-EPDR method achieved 97.7-98.8% packet delivery ratio, compared with 94.1-95.2% for RAAOR-WMN and 92.7-93.7% for FDOE-WMN, while keeping one-way delay within 7.4-8.6 ms. The study is limited to controlled simulation settings without mobility or field deployment; therefore, future work should validate the method under realistic traffic bursts, mobility and heterogeneous radio environments.