সোমবার, ১৭ জুন, ২০১৩
মঙ্গলবার, ১১ জুন, ২০১৩
TELECOMMUNICATION SYSTEMS AND TECHNOLOGIES-Vol 1- wireless terrestrial communications: cellular Telephony
WIRELESS TERRESTRIAL COMMUNICATIONS: CELLULAR TELEPHONY
Arial Pashtan
Aware Networks, Inc, Buffalo Grove, Illinois, USA
Keywords: mobile network, mobile terminal, cellular phone, cellular service, cellular operator,mobile subscriber, radio access network, cell site, wireless application protocol, wireless internet, short message, instant message, emergency call, emergency call, quality-of-service.
Contents
1.Introduction
2.Mobile networks
2.1. Cellsites
2.2. Mobile RF spectrum
2.3. Subscriber mobility
3 Mobile terminals
4. cellular telephony evolution from1G to 3G
4.1. 1G collar systems
4.2. 2G collar systems
4.3. 2.5G collar systems
4.4. 3G collar systems
4.4.1.EDGE
4.4.2.W-CDMA
4.4.3. cdma2000
5. cellular services
5.1.Text messaging
5.2.Instant messaging
5.3.Multimedia messaging
5.4.E-mail
5.5.Emergency calls
5.6.Video service and mobile TV
5.7.Push-to-talk
5.9.IP-based multimedia communication
6Cellular quality-of-service
6.1.Basic Qos concepts
6.2.UMTS Qos atchitecture
7.Billing for cellular services
7.1.Voixe and data billing
7.2.Content-based-billing
8 Conclusion
Glossary
Bibliography
Biographical sketch
Summary
Cellular telephony
encompasses the use of cellular phones to place voice calls, exchange short messages, transmit data .browse the web and issue multimedia calls. In this topic we describe the evolution of cellular services and underlying and underlying supporting technologies.
1. Introduction
A wireless mobile communication network enables users equipped with mobile terminals to initiate and receive phone calls. This capability is referred to as cellular telephony. In the following we describe mobile networks and the mobile terminals used by mobile subscribers to carry out cellular calls. We proceed with an account of the
history of cellular telephony and elaborate on the evolution of networks and subscriber services, including the convergence of data networks towards the wired internet standards.
Cellular telephony has evolved to include many services that are based on the transmission of data and multimedia, not just voice. Mobile subscriber services offered by cellular operators are described next. the underlying technologies of some services are detailed as well. Finally, we end with a description of cellular telephony quality-of-service and explain how cellular operators bill for user services.
2. Mobile networks
Cellular telephony derives its name from the partition of a geographic area into small "cells". Each cell is covered by a local radio transmitter and receiver just powerful enough to enable connectivity with cellular phones, referred to also as mobile terminals, within its area (figure-1). The set of cells forms the radio access network, and the radio frequencies used for the transmission of calls and data can be reused between cells. A different type of reuse, digital code reuse, is used in CDMA-based networks described later on. voice and
data exchanged between a mobile network which consists of the cellular operator's radio access network and core network.
figure1:Μobile network
2.1 Cell sites
А cell site is a site where antennas and radio transmitters and receivers are placed to create a radio coverage area in the mobile network. Cell sites can be min-sector, meaning that the same frequencies are used in all directions, 3-sector where the site coverage is partitioned into three distinct directional areas, each referred to as a cell (figure-2).
Figure:2.3-sector cell site
The spectrum of radio frequencies available for communication is limited and a benefit of a mobile network is its ability to reuse radio frequencies in different cells, provided that radio interference does not affect the calls. This reuse provides for increased network capacity as more mobile subscribers can be supported in a given geographic area. As the number of mobile subscribers increases, mote cells can be added or existing cells can be split into smaller ones. Two major factors that impact interference are the distance between cells and the cells transmission power. The layout of cells, allocation of frequencies, and transmission power specifications are part of radio frequency(RF) planning carried out by the cellular operators.
2.2 Mobile RF spectrum
Radio frequencies are allocated to different cellular radio technologies as shown in the map pf (figure3).
Figure 3: Radio frequencies allocation
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