Each optimal path can possibly satisfy a particular QoS constraint
not yet satisfied by any other path. QoS routing guarantees
finding apaththat satisfies the QoS constraints ifit exists, by considering
all QoS optimal paths. The number of optimal paths can grow
exponentially with respect to the network size [19].
The WMSN QoS routing problem can be addressed metaheuristically
using multi-objective optimization algorithms, as
explained in the following section.