The use of radio-frequency (RF) devices for wireless transmission of data is an appealing way to set up local networks (LAN). RF-based routers have become relatively inexpensive, easily available from many suppliers, and simple to implement. In places like private homes, small business locations and even larger areas, such as malls and hotels, wireless networks have become about as common as telephones. Retailers, especially those that operate large brick-and-mortar stores (ie supermarkets ...