Network Computingwww.networkcomputing.com

We gathered an assortment of portable wireless pagers, modems and cell phones from a range of service providers, took the devices to a variety of locations and tested them under real-world conditions. In the paging category, we tested GoAmerica's ARDIS-based service and the two-way RIM Inter@ctive Pager 850 from Research In Motion, the SkyTel two-way paging network using pagers from Motorola and Glenayre Technologies, and the BellSouth Mobitex network (also known as BellSouth Wireless Data, or BSWD) with the Palm VII. We also ran a Metricom Ricochet wireless modem through its paces and tested a data-capable CDMA (Code Division Multiple Access) cellular phone from Sprint PCS.

Other service providers and wireless devices are available, but ours is a representative sample. Although our primary focus was on the various network technologies you can use right now, in a real-world test it's impossible to separate the network from the device that accesses the network and from the service provider through which you purchase the device and service plan. We've examined all three components here.

Our Test Bed

Most of our testing took place in the Washington area, which has a fairly complete range of wireless services available. We tested in and around downtown D.C., in a suburban area of Maryland, and in various outlying areas, including rural southern Virginia outside the Richmond area, various highway locations and in downtown Baltimore. We also conducted some limited testing in Las Vegas and Los Angeles. The tests were real-world-based and as simple as could be designed because we were examining such a wide variety of networks, services, protocols and devices. We recorded the time it took to send a standard text message of known size over each device and repeated each trial a minimum of 10 times. We discarded the high and low values for each trial, along with any data points that were more than one standard deviation from the mean value.

Our standard test-file size was 5 KB--chosen because several of the paging networks or e-mail clients limit single messages to that size. We also tested larger file transfers (up to 45 KB) with the devices and services--CDMA, CDPD (Cellular Digital Packet Data) and Ricochet--that supported them.

Our test results cannot be considered scientific; throughput varies widely with all these devices depending on their physical location, proximity to the nearest transmitter or cell tower, RF (radio frequency) interference and environment, network traffic and other factors. But in a real-world sense, we obtained results in situations that should be comparable with the range of operational circumstances an average user might experience.