channel interference. CDMA brings a whole new approach to managing in- terference and, with it, a very different set of issues and solutions. The cellular environment today is portable telephones at traffic densities far beyond our 1983 forecasts using digital radio technology far beyond what we had then. The cel- lular environment tomorrow will add wireless local loop and high data rates. The cel- lular reality of 2002 and our visions of the cellular world of 2012 are nevertheless faith- ful to the cellular principles of 20 years ago. 6.3 Managed Interference Since the dawn of radio technology, radio engineers have fought the signal-to-noise bat- tle. More powerful transmitters, lower-noise receivers, and higher-gain antennas have been the focus of broadcast radio and television as well as dispatch services. The concept of managed interference was the big breakthrough of cellular. We still have all the noise issues to contend with, but the history of cellular radio has been con- tinuing refinement of the tradeoff between quality and quantity of calls. New technol- ogy has pushed the quality-quantity frontier further and further, but the cellular engi- neer's job remains the management of that tradeoff. This is not a sellout. Many of the products we used to know and love have become more available and less expensive at the cost of lower quality. Things that used to be made of high-quality sheet metal are now stamped out of cheap plastic. Less expensive ingredients are substituted to bring a price-competitive product to market. That some wireless vendors have taken the low road in their service offerings is not an indictment of the cellular technology that made these choices possible. The IMTS that cellular replaced was a terribly inadequate service. Only 14 simulta- neous calls could be supported in the entire New York City area, the signal quality was lousy, and everybody in the world could listen in. Not only could everybody listen to your call, but also those who wanted to make a call did listen so that they c