Scientific communication

1. Scan the text. While scanning look for answers to the following questions:

1. What are the main parts of cellular systems?

2. What enhances the profitability of mobile networks?

How mobile telephony got going

Cellular systems may be divided conceptually into five parts: radios, switching systems, databases, processing centers, and external networks. Often, though, multi­ple parts will be realized in a single phys­ical entity-a database combined with a switching system, for example.

The mobile connection of cellular sub­scriber and fixed telecommunications network is, of course, realized with radios. The mobile station (MS) is usually a small handset these days. Its corresponding base site radio, or base transceiver station (BTS), works through a base station controller (BSC), which keeps the rest of the fixed network happily in the dark about the radio details of the mobile MS-BTS con­nection. Together, the BTS and BSС are called a base station (BS).

All first generation analog cellular sys­tems, such as AMPS, use narrowband FM radio techniques that need only 10-30 kHz of spectrum for each channel. Today, the variety of radio link technologies feeds the controversies in third generation proposals. Since the radio link defines the base and mobile stations, a lot is at stake. The argu­ments tend to mask continuing innovation in the fixed parts of mobile networks.

The switching function is a combination of computing platforms and transmission facilities that route user information and signaling among nodes throughout the mobile network. The functional entity is called the mobile switching center (MSC). The center, its attached base stations, and any interworking functions to terrestrial networks or other kinds of networks are collectively called a mobile switching cen­ter, and an interworking function, BMI. The BMI is said to communicate with mobile stations over an air interface.

Several types of databases are queried by network entities while providing services to mobile subscribers. Location reg­isters manage mobility and are unique to mobile networks. The home location reg­ister (HLR) permanently stores subscriber data relative to network intelligence, while the visitor location register (VLR) maintains temporary working copies of active subscribers in the network.

Peripheral computing platforms en­hance the profitability of mobile net­works. The authentication center (AC), for instance, performs functions that validate a mobile station's identity. Voice-announce­ment systems and message centers are other functions.

2. Express your comprehension of the text “The mobile phone meets the Internet”.

3. Find the part of the text “The mobile phone meets the Internet” devoted to the following points and speak on items:

1. The advantages of the fourth generation.

2. The disadvantages of the third and fourth generations.

4. Divide the text into logical parts and find the topical sentence of each part.

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