A multi-objective optimization algorithm aims at producing (1) solutions as close as possible to the POS and (2) solutions as diverse as possible in the obtained non-dominated set. This diverse set of optimal solutions expresses trade-offs between different objectives. Routing protocols for WMSN must take into account a set of QoS requirements like bandwidth, delay, energy consumption. The ETX metric allows finding high throughput paths on a multi-hop wireless network, and incorporates the effects of link loss ratios, asymmetry in the loss ratios between the two directions of each link, and the interference among the successive links of a path.
In the route selection process, DSR only considers hop count, not meeting WMSN QoS requirements. Hop count does not consider the paths links conditions. HTLC-MeDSR uses ETX during the path selection process to evaluate link conditions along the path. Since HTLC-MeDSR is a multipath routing protocol, it also considers the Correlation Factor during the path selection process, to find multiple paths with minimum cross interference among a source-destination pair. The proposed MOEA algorithm allows finding paths that minimize both objectives, and paths that express trade-offs among objectives.
The paths found by the proposed SPEA present 2.2 and 2.15 times less ETX than those found and used by HTLC-MeDSR for scenarios 1 and 2 respectively. In terms of end-to-end delay, the paths found by the proposed SPEA present 26.07 and 51.95 times less delay than the ones found and used by DSR, and 4.39 and 3.30 times less delay than the ones found and used by HTLC-MeDSR, for scenarios 1 and 2 respectively.
The insertion of the proposed MOEA on HTLC-MeDSR route sets building procedure and subsequent evaluation is left for future work.