试题查看

首页 > 考研 > 试题查看
【单选题】

Until recently, mobile radio was to wireless communications what the Yugo was to transportation. With a mixed clientele ranging from truckers usingCBs to police armed with walkie-talkies to taxi drivers dispatched by radio, it was viewed as an unglamorous business and a technological backwater.

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 ofAT & T and the giantBabyBells. Upstart NextelCommunications 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 LosAngeles 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 asBell South, MCI andCoxEnterprises, 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.
SMR systems gain an edge over other services mostly by virtue ofA.its prohibitive retail prices.
B.its operational convenience.
C.its wider coverage areas.
D.its small storage capacity.
查看答案解析

参考答案:

正在加载...

答案解析

正在加载...

根据网考网移动考试中心的统计,该试题:

30%的考友选择了A选项

11%的考友选择了B选项

54%的考友选择了C选项

5%的考友选择了D选项

你可能感兴趣的试题

不符合白血病的描述是A.患者易发生出血B.患者易发生贫血C.急性白血病增生的细胞下列酶中以NADP+为辅酶的是A.苹果酸脱氢酶B.α-酮戊二酸脱氢酶C.琥珀酸脱下列有关Crohn病的临床表现正确的是A.最常累及直肠B.回肠很少被累及C.病变内源性血液凝固过程一般开始于A.组织细胞释放因子ⅢB.磷脂胶粒反应C.血小板聚集属于炎症的变质性病变是A.风湿病时心外膜的纤维蛋白B.烫伤时表皮内水泡C.流脑时Justhowdoesapersonarriveatanideaofthekin