It's somewhat overwhelming to think about the volume of wireless signals radiating around us in a typical urban environment. Imagine having one device that would simultaneously detect and demodulate every wireless signal at any given time and location, enabling you to simultaneously tune in every radio and TV transmission while eavesdropping on wireless calls, Wi-Fi hotspots, satellite broadcasts and so on.
Or like the stories of surprised dental patients picking up AM radio signals on their metal fillings, imagine a hapless human who would somehow involuntarily detect all these myriad signals. He'd quickly need sedation to combat the instant sensory overload!
Then there's the research regarding the potential health hazards of all these electromagnetic fields. One study sponsored by the Dutch government showed that exposure to 3G transmissions can cause headaches and nausea. But it also can boost cognitive functions, memory, and response times (sort of like a wireless cup of java, I guess).
Make no mistake about it. We are in the midst a wireless revolution. The density of the data around us is still at the leading edge of a steep, steep ramp. The notion of the RF spectrum being divided into neat slices, each dedicated to a discrete broadcast, is being challenged on multiple fronts. Through spread spectrum, OFDM, time-division multiplexing, and other schemes, we'll keep finding ways to accommodate more users and higher data rates.
Meanwhile, the concept of a device dedicated to a single receiving function is similarly under fire. Next-generation cell phones and other devices will use software-defined radio (SDR) and cognitive radio concepts plus DSP to simultaneously accommodate voice, GPS, video, and RF-ID with e-commerce, digital media, and data services like messaging, video conferencing, and VoIP. 3G devices will seamlessly switch between radios and/or antennas to suit the environment or the activity. And, these devices will serve as a mobile window to the coming wave of machine-to-machine communications. Homeowners will be able to use the "phone" to remotely control security and automation systems, as well as monitor webcams by the pool or in the home. Projections call for as many as 14 billion intelligent connected devices within five years.
TUNING IN I imagine that as electronic designers working to keep on top of this revolution, you sometimes feel overloaded with information about new wireless technologies. Our mission is to help you dial in the right informational frequencies and filter out the cacophony around you. Hence, we bring you this special Wireless Everywhere issue.Communications/Networking Editor Louis E. Frenzel starts the issue with a comparison of some of the leading wireless solutions. He then focuses on two of the hottest up-and-coming technologies within the wireless family, mesh networks and WiMAX. And since the wireless revolution affects so many fronts in design engineering today, all of our tech editors are looking at how wireless impacts their individual areas. We hope you find this special issue helpful as you consider how new wireless solutions may change the direction of your current projects.
For a link to the NTIA spectrum allocation chart, enter Drill Deeper 11053 at www.elecdesign.com. For more thoughts on wireless, check out my notes from my recent trip to the Northwest at Drill Deeper 11054
