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Mobile POS’s Unfixable Single Point Of Failure: Wi-Fi

October 13th, 2011

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.


2 Comments | Read Mobile POS’s Unfixable Single Point Of Failure: Wi-Fi

  1. ed Says:

    One frightening aspect of this is social engineering where an 10 year old can own the “jammer” device and cannot be charged as an adult but can disrupt the transactional process of a small store at the height of their shopping season.

    The only true solution is a wired primary system installed in place. M-commerce/Wi-Fi should just be a “nice to have” and not a critical transaction component of any retail operation.

    With that said, I prefer mobile/wi-fi to be limited to digital signage, product/price lookups and couponing and impulse buy offers in the layout.

    Another thing to keep is mind is make sure the mobile transaction device can work in offline mode and can queue the transactions intelligently. So if the wi-fi is jammed, the transactions are stored locally and secure on the mobile device and when restored, can be sent for processing in a delayed fashion.

  2. Richard Nedwich Says:

    Depending on Wi-Fi for critical retail applications such as POS is not new to Retailers. Even cash registers can be connected to Wi-Fi with NIC cards (network interface cards). As Ed points out, fallback can be as simple as batching orders until connectivity is restored, with wired stations as a last resort. What’s new is the ease with which anyone could disrupt that network. In fact, without a ‘scrambler’ one could simply use their smartphone’s Wi-Fi hotspot capability near the retailer’s access point to create interference (there’s a tip). However, some Wi-Fi solutions are designed to handle interference by using spectrum management solutions to detect, classify and mitigate those sources and/or change channels to avoid them. Others are designed with a single channel architecture that can continue to operate down to a single good RF channel while operating at full power (which tends to swamp out lower power interference sources anyway). Ask your WLAN vendor how they handle this situation, and can they operate down to a single channel?


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