Evan Schuman's StorefrontBacktalk

Even more of a potential problem is Wi-Fi equipment from other retailers, especially (in an indoor mall) from holiday pop-up stores. Those stores have to be set up and torn down quickly, often on a tight budget. That means Wi-Fi is very appealing, and so is keeping non-standard or off-brand equipment around long after it should have been replaced.

That’s an invitation to problems, especially for the pop-up store’s neighbors. For example, some Wi-Fi access points that used early versions of the 802.11n standard worked perfectly with equipment from the same vendor but completely wiped out all other Wi-Fi communications within range of the signal, which—being 802.11n—is a much wider area than previous Wi-Fi access points covered.

Lots of that so-called “pre-N” equipment is still in use, which means a new, temporary next-door neighbor could intermittently disrupt a store’s mobile POS through the whole holiday season—exactly when mobile POS is supposed to be helping the most. And ironically, even though it could subject the whole store to a much stronger signal than the low-power, short-range pocket jammer carried by a saboteur, that unintentional jamming is technically legal.

Unfortunately, there’s not much that IT can do in advance when a Wi-Fi jammer moves in next door or a saboteur settles in for the afternoon. If the store is using Wi-Fi-equipped phones and there’s a cell signal available, associates might switch to that—but that won’t work with the iPod Touch and Wi-Fi-only iPad, the two most popular in-store mobile devices.

In some cases, a store’s Wi-Fi can be switched from 2.4 GHz to the less frequently used 5 GHz band if the equipment can support either 802.11a or some versions of 802.11n. But that won’t work with the iPod Touch either. (The Wi-Fi iPad can use 5 GHz—and it’s nice to know you get something more than a pretty screen for all that extra money and bandwidth.)

Mostly, though, associates who have Wi-Fi problems will probably have trouble even figuring out that Wi-Fi is the problem. With new wireless networking equipment, new mobile devices that get bumped around more than expected and new back-end software that may choke under the stress of Black Friday and the days that follow, associates might not even think the problem could be anywhere but in the store’s own systems.

Yes, it could—and in a certain number of cases, it probably will be. Just hope that if their Wi-Fi is jammed, it’s because of a prankster who causes problems for a few minutes and then moves on. If the problem is a new neighbor, the Wi-Fi could be jammed for the rest of the year.