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| Mobile Telephone |
| Mobile Devices by: Lawrence Harte Mobile Devices Mobile devices (also called access terminals) are input and output devices that are used to communicate with a radio site (base stations). Mobile devices may include removable subscriber identity modules (SIMs) that hold service subscription information. The common types of available mobile devices include external radio modems, PCMCIA cards, radio modules, and dual mode mobile telephones. Subscriber Identity Module (SIM) The subscriber identity module (SIM) is a small "information" card that contains service subscription identity and personal information. This information includes a phone number, billing identification information and a small amount of user specific data (such as feature preferences and short messages). This information is stored in the card rather than programming this information into the phone itself. This intelligent card, either credit card-sized (ISO format), or the size of a postage-stamp (Plug-In format), can be inserted into any SIM ready wireless telephone. Figure 1.11 shows a block diagram of a SIM. This diagram shows that SIM cards have 8 electrical contacts. This allows for power to be |
applied to the electronic circuits inside the card and for data to be sent to and from the card. The card contains a microprocessor that is used to store and retrieve data. Identification information is stored in the cards protected memory that is not accessible by the customer. Additional memory is included to allow features or other information such as short messages to be stored on the card. PCMCIA Air Cards The PCMCIA card uses a standard physical and electrical interface that is used to connect memory and communication devices to computers, typically laptops. The physical card sizes are similar to the size of a credit card 2.126 inches (51.46 mm) by 3.37 inches (69.2 mm) long. There are 4 different card thickness dimensions: 3.3 (type 1), 5.0 |
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Figure 1.11., Subscriber Identity Module (SIM) Block Diagram |
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24 Nov 2006 Definitions FREE at www.IPTVDictionary.com
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(type 2), 10.5 (type 3), and 16 mm (type 4). WCDMA PCMCIA radio cards can be added to most laptop computers to avoid the need of integrating or attaching radio devices.
Embedded Radio Modules Embedded radio modules are self-contained electronic assemblies that may be inserted or attached to other electronic devices or systems. Embedded radio modules may be installed in computing devices such as personal digital assistants (PDAs), laptop computers, and other types of computing devices that can benefit from wireless data and/or voice connections. Mobile Telephones Mobile telephones are radio transceivers (combined transmitter and receive) that convert signals between users (typically people, but not always) and radio signals. Mobile telephones can vary from simple voice units to advanced multimedia personal digital assistants (PDAs). External Radio Modems External radio modems are self-contained radios with data modems that allow the customer to simply plug the radio device to their USB or Ethernet data port on their desktop or laptop computer. External modems are commonly connected to computers via standard connections such as universal serial bus (USB) or RJ-45 Ethernet connections. |
To allow for the conversion from analog systems to digital systems, some mobile systems allow for the use of dual mode or multi-mode mobile radios. These mobile radios may be capable of operating on an analog or digital radio channel or on multiple types of digital channels, depending on whichever is available. Most dual mode phones prefer to use the most recent version of digital radio channels in the event both are available (e.g. 3G is preferred over 2G). This allows them to take an advantage of the additional capacity and new features such as short messaging and digital voice quality, as well as offering greater capacity.
Figure 1.12 shows the common types of mobile devices available to customers. This diagram shows that the product types available for mobile systems include dual mode and single mode mobile telephones, PCMCIA data cards, integrated (embedded) radio modules and external radio modems. Mobile telephones may be capable of operating on voice and analog radio channels or on the data only channels "dual mode". PCMCIA data cards may allow for both data and voice operations when inserted into portable communications devices such as laptops or personal digital assistants (PDAs). Small radio assemblies may be integrated (embedded) into other devices such as laptop computers or custom communication devices. External modems may be used to provide data services to fixed users (such as desktop computers). |
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Series Source: Introduction to Mobile Telephone 2nd Edition $19.99 printed $16.99 eBook |
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| Figure 1.12., Mobile Product Types | ||
25 Nov 2006 Subscriptions FREE at www.IPTVMagazine.com
Copyright 2007 Althos Inc. All rights reserved.
