Architecture and Context

The PSTN¹ was the earliest example of traffic engineering to deliver Quality of Service (QoS²) guarantees. A.K. Erlang (1878 – 1929) is credited with establishing the mathematical foundations of methods required to determine the amount and configuration of equipment and the number of personnel required to deliver a specific level of service.

In the 1970s the telecommunications industry conceived that digital services would follow much the same pattern as voice services, and conceived a vision of end-to-end circuit switched services, known as the Broadband Integrated Services Digital Network (B-ISDN³). The B-ISDN vision has been overtaken by the disruptive technology of the Internet. Only the oldest parts of the telephone network still use analog technology for anything other than the last mile loop to the end user, and in recent years digital services have been increasingly rolled out to end users using services such as DSL⁴, ISDN⁵, FTTX and cable modem systems.

Many observers believe that the long term future of the PSTN is to be just one application of the Internet – however, the Internet has some way to go before this transition can be made. The QoS guarantee is one aspect that needs to be improved in the Voice over IP (VoIP) technology.

There are a number of large private telephone networks which are not linked to the PSTN, usually for military purposes. There are also private networks run by large companies which are linked to the PSTN only through limited gateways, like a large private branch exchange (PBX⁶).

Notes:

¹PSTN – postal telephone network – почтовая телефонная сеть связи; public switched telephone network – коммутируемая телефонная сеть общего пользования.

²QoS – Quality of Service – качество обслуживания.

³B‑ISDN – the Broadband Integrated Services Digital Network – широкополосная цифровая сеть с интегрированным обслуживанием.

⁴DSL – Digital Subscriber Line – цифровая абонентская линия.

⁵ISDN – integrated-service digital network – интегральная цифровая сеть связи.

⁶PBX – private branch exchange – учрежденческая телефонная станция с исходящей и входящей связью.

23. Find the following information in the text.

1. Digital technology as an advanced technology in the telecommunications industry.

2. The application of the PSTN in the future.

24. Say where the information presented in the text can be used.

Unit II Satellite and Ground Systems of Mobile Network and Broadcasting

Part A

Word List

access	//'xkses///	доступ
affiliate	//'qfIlIeIt//	компания-филиал, партнер
alpha-numeric	//"xlfqnjH'merIk//	содержащий буквенные и цифровые данные
angle	//'xNgl//	угол
cache	//kxS//	прятать про запас
disseminate	//dI'semIneIt//	распространять
gear	//gIq(r)//	включаться, приводить в движение
handheld	//'hxndheld//	умещающийся в руке
latency	//'leIt(q)nsi//	скрытое состояние
link	//lINk//	канал связи
perigee	//'perIdZi://	перигей
wireline	//'waIqlaIn//	телефонный кабель

1. Compare the meanings of the following English words with the Russian ones. They may have different meaning.

Class, distribution, equator, generation, geosynchronous, globe, inadequate, location, multi-megabit, orbit, polar, present, sensor, system, terminal, unique, place, transmission.

2. Read the following words in each line and define their roots. Translate the words into Russian:

1. apply, application, applicator;

2. distribute, distribution, distributive, distributor;

3. communicate, communication, communicative, communicator;

4. transmit, transmitter, transmission;

5. generate, generation, generational, generative, generator.

3. Fill in the gaps with words derived from the words in brackets.

1. Geosynchronous systems have several advantages in terms of long satellite life and wide area … (cover) by a small number of satellites.

2. OmniTRACS provides two-way communications as well as … (locate) positioning.

3. The system is used … (extensive) for alphanumeric … (message) and on-board sensor reading for trucking fleets.

4. Newer generations of Inmarsats are incorporating … (digit) techniques for use with smaller, … (little) expensive terminals.

5. The advantages of little LEOs are their small size and … (relative) low costs.

6. The system presents considerable challenges for … (apply) development.

4. Translate the following sentences paying attention to the words in bold type. What part of speech do they belong to?

1. However, LEOs require substantially greater numbers of satellites to provide adequate coverage, and these will need more frequent replacement.

2. Qualcomm's OmniTRACS provides two-way communications as well as location positioning.

3. Beyond its current ability to distribute digital video, it is ripe for data communications experimentation and pilot applications development.

4. Unlike the other mobile satellite systems, DBS is not intended to be used as a two-way system over the satellite segment.

5. The downlink data rate is between 5 Kbps and 15 Kbps while the uplink is between 55 bps and 165 bps.

6. The data communications uplink is provided through wireline networks such as the public switched telephone system (PSTN) and Internet gateways.

7. These weaknesses are addressed by the low earth orbit systems, which follow elliptical orbits, allowing them to provide reduced delays and better coverage and elevation angles when close to their orbital perigee.

5. Read the text and name the key points raised in it.

6. Divide the text into logical parts and entitle them.

7. Choose the adjectives and adverbs used to describe:

1. the advantages of geosynchronous systems;

2. the disadvantages of geosynchronous systems;

3. big LEOs’ capabilities;

4. little LEOs’ capabilities.