Memorize the following basic vocabulary and terminology to text 4C:
deploy v — разворачиваться
scarce adj — скудный, недостаточный allotte v — наделять
congest v — перегружать, переполнять barrage n — огромное количество slump n — резкое падение интереса, цен chunk n — зд. область
bounce v — зд. перемещаться
Text 4 C
Benefits and Applications of adaptive antenna arrays
Wireless networks that employ adaptive antenna arrays have several advantages over conventional cellular networks. Because a base station equipped with an adaptive array has a far greater range than an ordinary station transmitting at the same power, fewer stations are needed to cover a given area. Although adaptive arrays may be more expensive than traditional antennas, reducing the number of base stations dramatically cuts the overall cost of deploying and operating a wireless network.
Adaptive arrays also enable a cellular service company to make better use of a scarce resource: the spectrum of frequencies allotted to the company for its radio signals. Many cellular systems are becoming overloaded with customers in certain congested sectors, the barrage of signals sometimes exceeds the amount that can be carried on the limited number of radio channels. Customers feel the crunch when their calls are dropped or they hear poor-quality signals. But because adaptive arrays allow several cell-phone users within a base station coverage area to share the same radio channel the technology increases the capacity of the spectrum. The improvement over ordinary antennas is significant: base stations outfitted with adaptive
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arrays can serve about six times as many people for voice communications and up to 40 times as many for data transmission. The result is better service and less interference, not to mention less wasted energy and radio pollution.
It is not surprising then, that adaptive antenna arrays are already in commercial use. Arrays using technology created by ArrayComm Eave Seen have been mounted on more than 150,000 cellular base stations in Japan, China, Thailand and other countries in Asia and Africa. All told, the arrays provide phone service to more than 15 million people. Commercial adoption has been slower in the US and Europe, partly because the telecommunications industry's economic slump has curtailed new investment in cellular networks. But one U.S. manufacturer, Airnet in Melbourne, Fla., is currently making cellular base stations that employ ArrayComm’s technology. And Marconi, British telecommunications company, is developing an advanced base station that will contain adaptive arrays.
Adaptive arrays are also a boon to wireless data networks. Because the arrays minimize interference, they can receive and transmit more data to users in a given chunk or frequency spectrum. A base station equipped with an adaptive array could deliver data to as many as 40 concurrent users at a rate of one megabit a second, which is about 20 times as fast as the typical data rate for existing long-range wireless networks. Because all the users in such a network do not usually require peak data rates at the same time, one station with an adaptive array could serve several thousand people. Users with laptops or other portable devices would be able to get uninterrupted high-speed access to the Internet walking or driving across the coverage area.
Since late 1990s the telecommunications industry has been heralding the advent of the wireless Internet. The new networks have been developing more slowly than originally predicted, but work is nonetheless progressing. As wireless carriers continue to pursue 3G networks — next-generation cellular systems that transmit data in packets — other companies are offering a variety
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of competing solutions for high-speed data transmission. Smart antennas have been incorporated into some of these solutions and can be put to use in existing networks as well. A data network is now operating in Sydney, Australia, and similar networks. Several major manufacturers of telecommunications equipment plan to incorporate smart-antenna technology into their next generation. For almost 100 years after Alexander Graham Bell invented the telephone, voice communications relied on a physical connection — a copper wire or a coaxial cable — between the caller and the network. Over the past 30 years, though, cellular phones have given us a taste of the freedom to communicate without wires. With the help of adaptive-array technology, wireless carriers will be able to offer far better performance at a much lower cost than wired networks do. Only then we will rid ourselves of the copper cage.
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Answer the following questions.
1. What are the advantages of adaptive antenna arrays over the conventional arrays? 2. What is the role of frequencies spectrum in wireless networks? 3. Where are adaptive antenna arrays commonly used now? 4. Why can adaptive arrays transmit more data to the users? 5. What is a new class of systems for high speed data transmission? What do you know about it?
Task 1. Discuss the application of adaptive antenna arrays with your partner and give additional information about it.
Task 2. Justify the idea that adaptive arrays provide cellular-phone services.
Task 3. Summarize the information about the benefits of adaptive antenna arrays in wireless communication and give your presentation.
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Grammar exercise № 4
Translate the following sentences.
1.In 1997 there were 5 channels on TV in the U.K. — BBC1, BBC2, ITV, Channel 4 and Channel 5. Provided the subscriber (абонент) wanted to receive satellite TV programs, he had to pay extra for a satellite dish.
2.Provided with satellite dish, the subscriber can receive satellite TV programs.
3.Lately TV viewers provided their old analog TV sets with digital tuners that enable them to receive surprisingly sharp pictures.
4.Even if your TV set can receive over-the-air digital signals, that does not guarantee the high resolution pictures.
5.Provided cable TV operators supply all households with DTV tuners, TV viewers all over the country will get access to hundreds of channels.
6.Unless cable subscribers provided their TV sets with new high-definition recorder, they wouldn’t be able to record programs at the highest resolution.
7.Provided other transmitters interfere with your reception, your only real option is to wait.
8.Were cognitive radio as new smart wireless communication technology available everywhere, it would provide connection with any open (free) radio frequency that is particularly important in an emergency.
9.When cable and satellite subscribers provided their TV sets with new high definition recorder, they could record programs at the highest resolution.
10.Providing cognitive radio were now used even in remote rural areas, the cost of wireless services could drop dramatically.
11.Unless we install a satellite dish, we won’t be able to watch satellite TV programs.
12.Hadn’t the aerial of your TV set been grounded (earthed), the lightning might have caused a lot of damage.
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13.Adaptive antenna arrays can vastly improve wireless communication provided they connect mobile users with virtual wires.
14.Provided with powerful digital procession that manipulates the incoming and outgoing signals adaptive antenna arrays can maintain and offer cellular-phone service to more than 15 million people.
15.Unless your home electrical appliances are safely grounded, you may get electric shock if you accidentally touch the machinery.
16.Provided the number of base station for wireless communication is reduced, the cost of operating a wireless network will go down (fall).
17.Adaptive antenna arrays provided a vast quality improvement of wireless communication.
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