Chapter 1 : Introduction
1.
A Cellular Network : Introduction
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1.1 Introduction
A cellular network is a radio network distributed over land through cells where each cell includes a fixed location transceiver known as base station. These cells together provide radio coverage over larger geographical areas. User equipment (UE), such as mobile phones, is therefore able to communicate even if the equipment is moving through cells during transmission.
Cellular networks give subscribers advanced features over alternative solutions, including increased capacity, small battery power usage, a larger geographical coverage area and reduced interference from other signals. Popular cellular technologies include the Global System for Mobile Communication, general packet radio service, 3GSM and code division multiple access.
Cellular network technology supports a hierarchical structure formed by the base transceiver station (BTS), mobile switching center (MSC), location registers and public switched telephone network (PSTN). The BTS enables cellular devices to make direct communication with mobile phones. The unit acts as a base station to route calls to the destination base center controller. The base station controller (BSC) coordinates with the MSC to interface with the landline-based PSTN, visitor location register (VLR), and home location register (HLR) to route the calls toward different base center controllers.
Cellular networks maintain information for tracking the location of their subscribers' mobile devices. In response, cellular devices are also equipped with the details of appropriate channels for signals from the cellular network systems. These channels are categorized into two fields:
- Strong Dedicated Control Channel: Used to transmit digital information to a cellular mobile phone from the base station and vice versa.
- Strong Paging Channel: Used for tracking the mobile phone by MSC when a call is routed to it.
1.2 Cellulat Network : Architecture
A typical cell site offers geographical coverage of between nine and 21 miles. The base station is responsible for monitoring the level of the signals when a call is made from a mobile phone. When the user moves away from the geographical coverage area of the base station, the signal level may fall. This can cause a base station to make a request to the MSC to transfer the control to another base station that is receiving the strongest signals without notifying the subscriber; this phenomenon is called handover. Cellular networks often encounter environmental interruptions like a moving tower crane, overhead
Figure 1 :Cellular Network
power cables, or the frequencies of other devices.
To the mobile user, the main part of equipment is the handset and the radio unit; these could be separate units or an integral unit allowing portability. Additional units could be added to the basic unit - answering equipment, and data terminals.
A cellular radio telephone service differs from previous modes of mobile communications in a number of ways. One significant aspect is the improvement of the utilization of the radio spectrum, made possible by the management techniques of the spectrum (e.g. frequency re-use).
Chapter 2: Elements of a Cellular Network
2
ELEMENTS OF A CELLULAR NETWORK
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2.1 Overview
In this section, the general system architecture of a cellular network is introduced:
- Mobile Station (MS) : This is basically the mobile phone.
- Base Station (BS): The covered area of a cellular network is
Figure 2 : Elements of Cellular Network
divided into smaller areas called cells. Each cell has a
Impressum
Verlag: BookRix GmbH & Co. KG
Tag der Veröffentlichung: 03.03.2021
ISBN: 978-3-7487-7642-0
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