Posts Tagged ‘cell phones’

Working Of Cell Phones

Cell phones, which operate on radio frequency, cover compartmentalized cell like areas with the help of base stations. Learn more. It’s truly amazing when you think how far we have come in the technology of cellular phones.

Cell phones or cellular phones are so called as they cover compartmentalized, cell like areas. The origin of the Cell phone can be traced back to the year 1973 when Motorola came up with World`s first cellular portable telephone which was commercialised as Motorola DynaTAC 8000X.

These days, new cell phones are being added at a rapid pace. The parts of them typically consist of following: circuit board; antenna; keyboard; LCD – liquid crystal display; battery; microphone; speaker.

In recent times, they are available with a wide range of functions. To list a few functions, depending on the type of cell phone you choose: store contact information; keep track of appointments; set reminders; prepare to-do lists; send/receive e-mail; play games; send text messages (sms); access to internet; watch and enjoy TV; built-in calculator; integration with other devices like GPS receivers, MP3 players, etc.

Cell phones, operating on radio frequency, have come up with an innovative cellular approach to counter limited availability of RF spectrum. Now, several cell phone towers are used to cater to a large geographic area.

Each tower (base station), covers a circular area called a cell. A large region is split into a number of cells allowing different base stations to use the same channels/frequencies for communication. This enables thousands and thousands of mobile telephone users to share far fewer channels.

Another important aspect is that, phones need less power to transmit to reach any base station as each base station covers a smaller area. Reducing the required transmit power reduces the size of the battery and thereby the weight of the phone. This has led to miniaturization of cell phones which would not have been possible without the cellular technology.

When you use your cell phone, following things happen. First the phone locates base station having strongest signal, and requests for a channel assignment. The base station permits channel assignment and the call gets accepted. The call is then forwarded to the local telephone network if it is to a regular phone otherwise it is transmitted through the cellular network. The call is then sent to its destination through the telephone network.

When the cell phone is switched on, SID (System Identification Code) on the control channel compares it to the SID programmed into the phone. If the SIDs match, the phone understands that the cell is communicating with home system. The phone sends a registration request, along with the SID and the MTSO keeps track of the phone`s location in a database. If the SID on the control channel does not match the SID of your phone, then the phone is in roaming.

The three technologies commonly used by 2G cell phone networks for transmitting information: frequency division multiple access (FDMA); time division multiple access (TDMA); code division multiple access (CDMA).

GSM (Global System for Mobile communications) implements TDMA, to connect to the specific service providers in different countries. GSM uses subscriber identification module (SIM). SIM stores all the connection data/identification numbers needed to access a particular wireless service provider.

Standard 2.5G protocols used widely are GPRS, EDGE to name a few. Some latest 3G protocols are: Universal Mobile Telecommunication Service (UMTS); Wideband Code-Division Multiple Access (WCDMA); High-Speed Downlink Packet Access (HSDPA); Evolution Data Maximized (EVDO).

A few popular cell phone models in the market have been offered by Nokia, Ericsson, Motorola, Samsung, LG, etc. with each model with its own range of collections.The year 2008 may be a high watermark in the cell phone history with Nokia N-Gage 2, HTC Dream, Apple iPhone 2, BlackBerry Touchscreen, Sony PlayStation Phone which are expected to be launched.

This article can be accessed in portuguese from the Article section of page Cell_Phone

Roberto Sedycias works as IT consultant for PoloMercantil.

Mobile Phone Signal Booster

Now that we’re settled in the house, we’ve noticed that our mobile phone reception is quite poor. We both work at home quite often and use our mobiles when we do, so have been looking for a mobile phone signal booster.

First public cell

Cellular phones from the early 1990’s are considered second generation (2G) and they were able to work on mobile phone systems such as GSM, IS-136 (TDMA) and IS-95 (CDMA). Digital mobile phone networks were in use in the United States.

Verizon software to mobile phones

Jill plans to build a “mobile widgets” for future phones will likely work on any operating system, Verizon decision support in its future smartphones. Seven organizations are currently fighting for the inner track to start the mobile computer in the future.

Technorati Tags: 2g, cell phones, gsm, how does a cell phone work, mobile phone, Mobile Technology

Gsm Vs Cdma Mobile Technology

GSM and CDMA network technologies are the two main competing technologies set up by cellular service providers across the globe.

GSM is an abbreviation of Global System for Mobile Communications, while CDMA is an abbreviation of Code Division Multiple Access
The technology:

Mobile communication systems have to make use of the microwave frequencies above 800 MHz for transmission and reception of the signals. Different service providers operate in pre allocated frequency bands given to them by the international standards. Below listed are the methods to access these microwave frequencies.

FDMA (Frequency Division Multiple Access) – FDMA puts each call on a separate frequency.

TDMA (Time Division Multiple Access) – TDMA assigns each call a certain portion of time on a designated frequency.

CDMA (Code Division Multiple Access) – CDMA gives a unique code to each call and spreads it over available frequencies.

GSM is a global standard based on TDMA.
How these technologies affect the common man:
In case of GSM:

If you opt for GSM technology, you have the freedom to choose handset separately from the wide variety of big handset companies like Nokia, Motorola, Sony Ericsson, etc who retail their products in the market.

You can then purchase a SIM card from any of the GSM service providers like Hutch, Airtel, etc and insert it in to your handset and start talking.

You even enjoy the freedom to switch the service provider and still continue with the same handset.

GSM service providers are well networked globally. Therefore it offers much better international roaming. You must check for roaming call rates and coverage in the regions or countries where you visit frequently.

Another major benefit that GSM users enjoy is that if you travel to other countries you can make use your same GSM cell phone there too( if it is a quad-band phone 850/900/1800/1900 MHz). To save yourself from roaming charges from your service provider, you can purchase a local SIM card with call value and a local number in the country you are visiting.
In case of CDMA:

Here the handset is network locked. You have to buy a complete package from the service provider that includes both, the handset and the connection (prepaid / postpaid).

Two main CDMA players in India are Reliance and TATA.

Earlier it was difficult for Reliance users who wanted to retain the same number but wanted to change their reliance handsets, to do so. However now it is possible by making use of the handset change card that is available in a nominal amount.

TATA however made it very user friendly. Due to its T – SIM enabled handsets; it is easier for TATA users to change their handsets

Reliance and TATA now have a range of entry level, mid-segment and features rich advance handsets available with them. However in this case the choice of handsets is limited to the models offered by the Service Provider.

You cannot change the service provider and still keep the same handset.

Voice clarity in CDMA network is supposed to be better as it uses same frequency across all cells.

Here you need to check for International roaming tie ups if you travel abroad frequently. You do not enjoy the freedom like GSM mobiles.

TATA is soon launching T-SIM to enable international roaming with one world one number concept.

Before choosing a CDMA or GSM Mobile phone from any mobile store, you need to understand the features and services provided by these mobile phones well

By: Mohit Sharma

Article Directory: http://www.articledashboard.com

Mohit Sharma is an expert author and have written many good quality articles on online shopping, mobile store and online computer shopping

Technorati Tags: cdma, cell phones, gsm