  Reliability and determinism of Wi-Fi can be tangibly improved by means of
seamless redundancy, to the point of making this technology suitable for
industrial environments. As pointed out in recent papers, the most benefits can
be achieved when no phenomena can simultaneously affect transmissions on all
channels of a redundant link. In this paper, several aspects are analyzed
which, if not properly counteracted, may worsen seamless redundancy
effectiveness. Effects they cause on communication have been experimentally
evaluated in real testbeds, which rely on commercial Wi-Fi devices. Then,
practical guidelines are provided, which aim at preventing joint interference
through a careful system design. Results show that measured communication
quality can be made as good as expected in theory.
