Wireless technologies

摘要

In 1983, few Americans could have imagined how profoundly society would be transformed following Ameri-tech's launch of the first US cellular telephone service in Chicago. Expectations were modest for the early 'mobile' phone-often referred to as a 'brick phone'-weighing over two pounds, with a purchase price of $4000 and costing nearly a dollar a minute to operate. The service seemed destined, at best, to satisfy a small niche demand of sophisticated business users and the very wealthy. Yet, by 2009, both the cost and the size of wireless phones had shrunk dramatically. Today, the typical mobile handset weighs only a few ounces, has a price tag that might range from 'free' to a few hundred dollars, and incurs usage charges that have fallen to roughly 5 cents a minute. From their origins as a voice-only handset, modern mobiles have evolved into an all-purpose voice, data and video appliance. The market response has been dramatic. Today there are over 276 million active customers in the US and over 4 billion worldwide.