But specialized mobile radio, as it is known, has been rediscovered. It is now considered one of the biggest prizes in the all-out war for the public airwaves. The reason: high-tech companies have figured out how to profitably rebuild the antiquated dispatching system into an advanced cellular-telephone network that can take on the likes of AT&T and the giant Baby Bells. Upstart Nextel Communications sent shock waves through the industry last week when it agreed to buy Motorola's SMR frequencies for $1.8 billion.
That could pose a serious threat to cellular hegemony. Although both systems are based on the same basic technology, SMR systems are digital and cover almost 25 times as much area as the average cellular network. SMR handsets won't work on cellular systems and tend to be bulkier than cellular phones, though they provide more features, like a digital pager service. And while cellular growth has tripled to some 13 million subscribers since 2000, the technology has been losing ground. It is running out of channel capacity so fast, in fact, that 40% of cellular calls in high-density areas like Manhattan and Los Angeles fail to be completed. SMRs have capacity to spare, and service could eventually be priced 10% to 15% less than cellular. Dispatchers predict they will have at least 10 million subscribers by the end of the decade. There are now about 1.5 million users of SMRs.
The addition of another contender to an already crowded field of telephone systems will surely multiply the confusion. By the year 2010, consumers will be able to choose from at least half a dozen vendors of a dizzying array of wireless-communications services, including pagers, voice mail answering machines and cellular phones. Phone and cable television operators, such as Bell South, MCI and Cox Enterprises, are developing so-called personal communications networks, or PCNs, a highly advanced portable-phone system that is expected to cover a wider area, connect to a greater variety of services and be cheaper to operate than conventional cellular.
And many companies that have gambled on the wrong technological standards, and invested billions trying to develop the same markets, will undoubtedly lose a great deal of money before the shakeout is over. "The winners", says Nextel chairman Morgan O'Brien, "will be those who can make the choice for consumers easy". With all the anticipated confusion—mindful of the early years of personal computers—it is likely to be years before anyone calls the purchase of wireless products an "easy" choice.
How did mobile radio systems find its business competitiveness?
A.Its technological features have radically changed.
B.It has been rebuilt to cater to various subscribers.
C.Its dimensions have been reduced by wide margins.
D.It was connected to a greater variety of services.
第1题
病毒性心肌炎的主要病原体是 ()
A.流感病毒
B.肠道病毒
C.艾柯病毒
D.柯萨奇病毒B3
E.呼吸道合胞病毒
第3题
病毒性心肌炎的主要病原体是
A、柯萨奇病毒B3
B、埃可病毒
C、腺病毒
D、呼吸道合胞病毒
E、流感病毒
第7题
该患儿呼吸道感染可能的病原体是
A.呼吸道合胞病毒
B.腺病毒
C.流感病毒
D.埃可病毒
E.柯萨奇病毒
第8题
成人普通感冒最常见的病原体是()
A.鼻病毒
B.副流感病毒
C.呼吸道合胞病毒
D.埃可病毒
E.柯萨奇病毒
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