GSM vs CDMA

There is a time when you start getting bored with your long time phone. And you feel like you've been holding it forever in your hands. And you decide to buy a new one. Buying a phone is a hard choice. Even more, it is a hard set of choices, a bunch of decisions wrapped into one. First, you have to think about your budget, then when your budget is ready you have to decide among many choices such as the operating systems, hardware, and feature lists. More importantly you've got to choose a network, with its distinct coverage areas, rate plans and customer service. Another quandary is the technology. GSM or CDMA? Physically there is no significant difference between GSM and CDMA even at the first glance they look similar. The major difference between the two technologies is how they turn voice data into radio waves and how the carrier connects to the phone. Other differences include the coverage area, the data transfer speeds, and the type of hardware used.

GSM (Global System for Mobile Communications)
GSM stands for Global System for Mobile Communications, is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones. The GSM standard was developed as a replacement for first generation (1G) analog cellular networks, and originally described a digital, circuit switched network optimized for full duplex voice telephony. This was expanded over time to include data communications, first by circuit switched transport, then packet data transport via GPRS (General Packet Radio Services) and EDGE (Enhanced Data rates for GSM Evolution or EGPRS).

GSM is a digital technology that works by sending data packets based on time, or better known as the time slot. GSM itself is a derivative technology of Time Division Multiple Access (TDMA). TDMA is a technology to send data based unit consisting of time, it means a GSM data packet will be divided into multiple time slots. These time slots will be used by the GSM network users temporarily. The purpose and use of temporary time slots is, the time slots will be monopolized by users during their use, regardless, or when they're actively talking or even when they're being silent. GSM phones make use of a SIM card to identify the user's account. The use of the SIM card allows GSM network users to quickly move their phone number from one GSM phone to another by simply moving the SIM card. Currently, GSM networks operate on the 850MHz, 900MHz, 1800MHz, and 1900MHz frequency bands. Devices that support all four bands are called quad-band, with those that support three or two bands called tri-band and dual-band, respectively. GSM network is divided into three main systems: Swithing Systems (SS), Base Station System (BTS) and Operation and Support System (OSS).

CDMA (Code Division Multiple Access)
Code division multiple access (CDMA) is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne, CDMA2000 (the 3G evolution of cdmaOne) and WCDMA (the 3G standard used by GSM carriers), which are often referred to as simply CDMA, and use CDMA as an underlying channel access method.

CDMA describes a communication channel access principle that employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code). CDMA also refers to digital cellular telephony systems that use this multiple access scheme, as pioneered by QUALCOMM, and W-CDMA by the International Telecommunication Union (ITU), which is used in GSM’s UMTS.

Here's the following considerations:

Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.

Data Transfer Speed: With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies.

EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready.

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required.

In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance.

Subscriber Identity Module (SIM) cards: In the United States only GSM phones use SIM cards. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention. The SIM itself is tied to the network, rather than the actual phone. Phones that are card-enabled can be used with any GSM carrier.

The CDMA equivalent, a R-UIM card, is only available in parts of Asia but remains on the horizon for the U.S. market. CDMA carriers in the U.S. require proprietary handsets that are linked to one carrier only and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one with the ESN (electronic serial number).

Roaming: For the most part, both networks have fairly concentrated coverage in major cities and along major highways. GSM carriers, however, have roaming contracts with other GSM carriers, allowing wider coverage of more rural areas, generally speaking, often without roaming charges to the customer. CDMA networks may not cover rural areas as well as GSM carriers, and though they may contract with other CDMA carries for roaming in more rural areas, the charge to the customer will generally be significantly higher.

International Roaming: If you need to make calls to other countries, a GSM carrier can offer international roaming, as GSM networks dominate the world market. If you travel to other countries you can even use your GSM cell phone abroad, providing it is a quad-band phone (850/900/1800/1900 MHz). By purchasing a SIM card with minutes and a local number in the country you are visiting, you can make calls against the card to save yourself international roaming charges from your carrier back home. CDMA phones that are not card-enabled do not have this capability, however there are several countries that use CDMA networks. Check with your CDMA provider for your specific requirements.

In the conclusion, Digital-based cellular phone system, whether it's GSM or CDMA has its advantages and disadvantages. For a populous areas, seems CDMA technology is way more superior to serve many connections simultaneously. This is due to the characteristics and CDMA network itself. A dense usage areas will have a higher possibility of connection, by using the CDMA network, although it could be any reduction in the coverage area and the sound quality when the networks load is too high. GSM technology is more suitable for less-populated areas, but need a constant coverage area. Moreover, urban areas have a lot of buildings. Geographical character like this is potentially reduce the signal so the coverage area is getting smaller.

Apple Finally Launches iOS 7

Apple finally announced the arrival of their newest operating system, iOS 7. In the event of Worldwide Developers Conference (WWDC) in San Francisco, Craig Federighi announced the latest generation of iOS, which is called the biggest change since the presence of the iPhone.

Apple has given the operating system for its iPhones, iPads, and iPod Touches a new look with the introduction of iOS 7. But what are the differences between the previous generation? Is it quite enough to satisfy eager Apple fans who are constantly looking to upgrade to the next generation of iPhone? The differences that are immediately visible on iOS 7 is a flat design icons and more brightly colored than the previous generation of iOS. This new operating system is compatible for devices starting to iPhone 4, iPod Touch5 and iPad 2.

Here are some new features in iOS 7:

Control Center
Apple has finally put all the frequently used settings in one place, which is called the Control Center. From here you can control your music and switch on and off airplane mode, Wi-Fi, and Bluetooth, as well as turn on a flashlight or increase the screen's brightness. It should make managing and using different features on your phone much, much easier.

Safari
Apple has improved the Safari mobile browser in iOS 7. The biggest change to the browser is a unified search and URL field. Now there's more flexibility with browser tabs. The tabs now preview as vertically scrolling rectangular cards, and you can swipe them away in a gesture, just like we've seen on some Android phones. The new Safari in iOS 7 will also let users access Apple's new iCloud Keychain, which stores passwords and credit card numbers in the cloud to provide access across multiple devices.

Multitasking
In iOS 7, Apple has finally improved multitasking. All apps will now be able to update in the background while you're handling other tasks on your phone. And, Apple promises this won't affect battery life. You can double tap the screen to bring up a tiny thumbnail of icons of open apps. Again, it looks like Apple has borrowed a bit from Microsoft and Android in the design of this new feature.

AirDrop
Another new feature included in iOS 7 is AirDrop, which lets users create a local ad-hoc network among other iOS users that are nearby. It allows you to share a photo or some other bit of content simply by hitting a share button. Apple uses Wi-Fi and Bluetooth to send the content over a very short distance to the recipient. The feature is similar to Samsung's own sharing tool that uses the tap and go technology called NFC. This is one of those features that is limited by hardware. And it will be available only via the iOS 7 update on the iPhone 5, fifth-generation iPod Touch, fourth-generation iPad, and iPad Mini.

Camera and photos
As part of the redesign of iOS 7, the look and feel of the camera app has been updated. In a nutshell, Apple has made it easier to access available shooting modes, such as still, panorama, video, and a square, Instagram-like configuration. And it's also made it supersimple to apply filters to the still or square shots. The new iOS 7 also provides a different way of organizing phones in the Camera Roll. Instead of just allowing you to organize photos by when they were taken, it now organizes them by geotagged location. You can also arrange your pictures by year and get an overview of a particular year with teeny tiny images. It's much like the organizational features available in Apple's desktop iPhoto app.

iTunes Radio
Apple has launched its own Internet radio station. There's nothing new or different here when compared to other music services. It basically lets you build radio stations around a favorite artist, song, and genre of music. The service can be used on any device running your iTunes account. And it's ad-free for iTunes Match users.

Siri
Apple has also updated Siri, its voice activation feature. The updated version lets users switch to a male Siri voice and it offers non-English speakers access to the service. But the most substantial addition to the feature, is that the updated Siri can now trigger actions on your phone's system settings, like play a past voicemail, turn on Bluetooth, and increase the brightness settings on the screen. You can also ask Siri to search Wikipedia and Twitter.

FaceTime audio
FaceTime isn't just for video chats anymore. The new iOS 7 will allow people to make audio-only voice calls using the FaceTime app via a Wi-Fi connection.

iOS in the car
Apple has greatly improved in-car functionality for its iOS devices with iOS 7. The update will let people control more systems in their cars via their iOS device. This includes placing calls, playing music, and looking up directions. All of it is voice activated, thanks to integration with Siri. Some car brands have teamed up with Apple to integrate iOS in their cars. Next year, several models of Honda, Mercedes-Benz, Nissan, Chevy, Kia, Volvo, Acura, and a few other brands, will integrate their system settings on the dashboard with iOS

App Store
Another cool new feature for those using iOS 7 is an update to the App Store that allows users to search for popular apps based on location. So for example, say you're in a museum, you can search and find apps relevant to that particular museum.

Source: http://news.cnet.com/

What is Telecommunication Engineering?

Telecommunications engineering, or telecom engineering, is an engineering discipline that integrates electrical engineering with computer science to enhance telecommunication systems. Telecommunication is the exchange of information over significant distances by electronic means, particularly through electrical signals or electromagnetic waves. A complete, single telecommunications circuit consists of two stations, each equipped with a transmitter and a receiver. The transmitter and receiver at any station may be combined into a single device called a transceiver. Data are conveyed in a telecommunication circuit by means of an electrical signal called the carrier or carrier wave. The medium of signal transmission can be electrical wire or cable (also known as "copper"), optical fiber or electromagnetic fields. The free-space transmission and reception of data by means of electromagnetic fields is called wireless. The form of telecommunications can be divided into three parts, such as:

1. One-way communication (Simplex). In one-way communication (Simplex) transmitter and receiver cannot establish a continuous communication through the same medium. For example: Television, radio.
2. Two-Way Communication (Duplex). A duplex communication system is a point-to-point system composed of two connected parties or devices that can communicate with one another in both directions, simultaneously. For example: Telephone, VoIP.
3. Semi Two-Way Communication (Half Duplex). A half-duplex system provides communication in both directions, but only one direction at a time (not simultaneously). Typically, once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying (antennas are of trans-receiver type in these devices, so as to transmit and receive the signal as well). For example: Handy Talkie, Fax.

There are several basic elements to support telecommunication systems:

1. Information: This is data that will be sent, such as; sounds, images, and files.
2. Transmitter: Takes information and converts it to a signal.
3. Transmission medium: A tool that serves to send from the transmitter to the receiver. Because of the distance, the signal from transmitter will be changed with radio waves (modulation), and then converted into electromagnetic waves emitted by the device called Antenna.
4. Receiver: Takes the signal from the channel and converts it back into usable information.

Telecommunication is a diverse field of engineering, which is connected to electronics, civil, structural, and electrical engineering. Ultimately, telecom engineers are responsible for providing the method for customers to have telephone and high-speed data services. It helps people who are closely working in political and social fields, as well accounting and project management.

A telecommunication engineer is responsible for designing and overseeing the installation of telecommunications equipment and facilities, such as complex electronic switching systems, copper wire telephone facilities, and fiber optics. Telecommunication engineering also overlaps heavily with broadcast engineering.

Telecom engineers use a variety of equipment and transport media available from a multitude of manufacturers to design the telecom network infrastructure. The most common media, often referred to as plant in the telecom industry, used by telecommunications companies today are copper, coaxial cable, fiber, and radio.

Telecom engineers are often expected, as most engineers are, to provide the best solution possible for the lowest cost to the company. This often leads to creative solutions to problems that often would have been designed differently without the budget constraints dictated by modern society. In the earlier days of the telecom industry, massive amounts of cable were placed that were never used or have been replaced by modern technology such as fiber optic cable and digital multiplexing techniques.

Telecom engineers are also responsible for overseeing the companies' records of equipment and facility assets. Their work directly impacts assigning appropriate accounting codes for taxes and maintenance purposes, budgeting and overseeing projects.

Source: http://en.wikipedia.org/wiki/Telecommunications_engineering