Cdma gsm smartphones. GSM and CDMA: What is the difference and which is better? The CDMA standard works completely differently
Hello dear readers. Most cell phone owners only have to worry about one technology called global system for mobile communications or GSM. As the name suggests, this standard has been widely adopted and is used for communication using cellular communication.
But not everyone has jumped on the GSM train. An alternative standard known as Code Division Multiple Access, or CDMA, is also used by many operators around the world. This standard is most popular in the USA and Russia, but is also used in some African and Asian countries, where it competes with GSM.
Here's what cell phone owners should know before purchasing a device that supports one of these technologies.
This is the first question potential owners will ask, and it's a valid one. But in this case there is no simple answer.
GSM and CDMA- This different ways achieving the same goal. And the fact that popular networks have been built on the basis of each of them proves that it is not the standard that is important, but the quality of the network. For example, in the US, two of the four largest carriers (Verizon and Sprint) use CDMA, while the other two (AT&T and T-Mobile) have chosen GSM.
From a technical point of view, no standard has an advantage in terms of quality. But there are some things you should take into account. GSM phones can be unlocked and transferred to other operators, and CDMA phones are most often locked to one operator and nothing can be done about it.
Additionally, most phones support either GSM or CDMA, so your choice of phone may determine which standard you end up using. Apart from that, it all depends on what operators are available in your territory. Some areas are better covered by GSM providers, while in others CDMA providers may have an advantage.
Many phones are compatible with GSM or CDMA, but not both. In the case of CDMA phones, you will have to purchase a device made specifically for your operator. The easiest way is to buy it directly from this operator. For example, if you want to use an iPhone on Verizon's network, you need to purchase a branded iPhone from Verizon, not Sprint or AT&T. However, if you decide to switch to another operator, you will not be able to take the phone with you, as it is locked.
If you don't want to limit yourself to one carrier, you can look for unlocked GSM phones from third-party retailers. Such phones will work with any GSM operator; you just need to change the SIM card. For example, Amazon sells many unlocked GSM phones. The Nexus 5 model from Google and some devices in versions are also unlocked. Any retail or online store that sells cell phones, should provide information about which networks each specific device can work with.
Be careful with phone compatibility. Devices sold in markets where both standards operate most often support either GSM or CDMA. Only some phones are compatible with both standards. If you purchased a CDMA phone from a third party retailer, you will have to call your carrier to activate it. If you purchase a GSM phone, you will need to purchase a SIM card and insert it into the device to activate its network capabilities.
CDMA phone owners don't have to worry about SIM cards, but that's a curse rather than a blessing. CDMA devices are mired in compatibility restrictions that are difficult to get around, and GSM phone owners can simply remove the SIM card and replace it with another one. Most CDMA networks will not allow you to use a phone purchased from another operator, even if it is technically compatible. It is very important to remember this limitation when choosing a CDMA network. If you later decide to change carriers, you will most likely have to purchase new phone, even if the network you are switching to also uses CDMA.
Even though GSM is more open, access may still be limited to the frequency range supported by the phone. Frequencies vary from 380 to 1900 MHz and depend on local operators. You should check what frequencies your operator operates on and make sure that the phone you are about to buy supports them. However, GSM is concentrated around four main bands: 850, 900, 1800 and 1900 MHz. A phone that supports all four will work in most countries. This is why GSM phones that are compatible with all major frequency bands are called “world phones”.
If you understand the importance GSM and CDMA, Great! Now let's completely destroy your arrogance by talking about the newcomer, LTE (Long Term Evolution).
LTE is new standard , which has come into fashion over the past few years. Although it is based on GSM principles, but is still a separate standard that operates outside the GSM and CDMA networks. This is truly the fourth generation of cellular data transmission.
LTE is most widespread in South Korea, where the standard is used by most of the market, but it is also popular in Japan, Australia, Sweden and the United States. For now, it is mainly used for data transmission, but LTE can also serve as a replacement for traditional cellular networks. The American company Verizon Wireless, for example, announced its plans to release LTE phones at the end of 2014.
This standard uses SIM cards, so users will be able to switch to other networks, if the device supports them, of course, simply by changing the SIM card. However, now LTE is used mainly for data transmission, not voice. This means that owners of CDMA/LTE phones will still not be able to use other networks. This will change when carriers like Verizon fully switch to LTE networks. But this may take several years.
Although this standard has great potential, there are obstacles to its adoption. Outside of South Korea, LTE does not account for more than a quarter in any market. South Korea, in general, and Verizon Wireless in the US are actually an exception to the rule. In most markets, even carriers that offer LTE only offer it in limited areas.
There is also a problem with the spectrum. Remember that GSM/CDMA operate on many different frequencies? The same is true for LTE. You will have to check that your phone is compatible with the frequency bands supported by the operator, and you will not be able to use an LTE phone on another network with the same standard but different frequencies. It is not yet clear whether this standard will become “worldwide” in the same sense as GSM, which settled on four main frequencies supported by most GSM phones.
Summarizing
Take a deep breath. It's time to sum up everything that has been said.
First of all, neither GSM, nor CDMA have no advantage over each other from a technical point of view. They are designed for one purpose, and the quality of the network depends on the operator, not the standard it uses.
Secondly, GSM phones can be unlocked and used with another operator, while CDMA is locked to one operator. It is usually cheaper to purchase unlocked GSM phones than contracted CDMA devices.
Thirdly, you need to carefully check the frequencies supported by the phone. Most are compatible with either GSM or CDMA, and both standards can operate on different frequency bands depending on the region.
Finally, LTE has the potential to become a global standard, but falls prey to even greater frequency division than GSM and CDMA. This technology is relatively new and has not yet been widely implemented.
I hope that cleared everything up. Cellular networks are constantly evolving, and the standards supported by phones may change from year to year. Feel free to ask any questions you have in the comments.
Dessert Iphone 6
Enjoy watching!
https://www.youtube.com/watch?v=jKjXbwPIiHM
This material will look at CDMA phones, what kind of devices they are and in what cases you simply cannot do without them. The characteristics of real models will also be indicated and recommendations regarding their purchase will be given.
Two main mobile communication standards
Currently the most widespread mobile devices two standards: GSM and CDMA. Each of them is digital standard. But signal transmission in each of these cases is carried out differently. In the first case, it is divided into parts, each conversation occupies only a small part of the spectrum. In the second case, encoding allows the subscriber to use the entire radio frequency resource. As a result, in this case the quality of communication is an order of magnitude better. But today devices for mobile networks first type. This standard was introduced much earlier and was already in active use at the time of the announcement of CDMA solutions. Now we will get an answer to the question: “CDMA phones - what kind of devices are these?” These are devices that are designed for use in mobile CDMA networks. Similarly, GSM solutions are used only in such cellular networks.
Supported devices
There are many devices designed to function in it. First of all, these are mobile phones of the appropriate standard. They have a relatively low level of functionality: conversation, text and multimedia messages. In some cases, this list can be expanded by data transfer. So the answer to the question: “CDMA phones - what are they?” - is the definition: “This is a device that allows you to make calls, send and receive text or multimedia messages, or connect to the Internet on CDMA networks.” The second type of device that can be used in such networks is modems. They can perform only one task - to transmit and receive data from the World Wide Web to a PC. Another type of device is mobile Wi-Fi routers. They do the same thing as modems, but in this case, a computer is not necessary to make the connection. The router creates a wireless computer network, to which any device with a Wi-Fi transmitter can be connected. The last type of device is smartphones. This mobile devices, the capabilities of which are expanded through the use of special software. In this case, you can watch videos, listen to music, and communicate via in social networks... You can even use it as a mobile Wi-Fi router.
Operators in Ukraine
Until recently, there were quite a lot of cellular operators in Ukraine that operated using this standard. This includes Velton, Ukrainian Wave, People.net, and Intertelecom. But now only the last two continue to provide services. The first two of them were acquired by Intertelecom, their subscribers joined its cellular network. In turn, People.net, due to economic difficulties, began to “wind down” its coverage, because of this, many of its subscribers were forced to switch to its direct competitor, Intertelecom, which then became the only national CDMA operator. The basis of its subscriber base is made up of dual-standard CDMA-GSM phones. Odessa is the city from which this operator began its victorious march across the country. Now its coverage covers most of the country. So owners of CDMA devices can work in Ukraine only on one cellular network.
"Lenovo A330e"
The 5-inch display diagonal and affordable price are the main advantages of this model. The hardware basis of the device is Snapdragon 200 with two computing modules. Each of them can theoretically be overclocked to 1.2 GHz. The memory subsystem is represented by 512 MB of RAM and 4 GB of integrated data storage. The capacity of the included battery is 2000 mAh, which is definitely enough for 2 days of use. operating system in this case - "Android". The price for this device starts at 6,000 rubles.
Huawei Y321C
One of the most affordable devices of this standard is the Huawei Y321C CDMA phone. Although this is already a smartphone that runs Android. Its computing basis is the 2-core Snapdragon MCM8625 with a peak frequency of 1 GHz. Random access memory 0.5 GB, and the capacity of the built-in storage is “modest” 4 GB. The display diagonal is only 4 inches, and its resolution is 480x800. A battery with a capacity of 1350 mAh is responsible for autonomy. This is definitely enough for 1 day of work. The price for this device is 5,750 rubles.
"Lenovo A805e"
This is the most affordable one at the moment mobile phone GSM - CDMA with a diagonal of 5.5 inches. Its main computing power is the 4-core Snapdragon 410 CPU. Each of its computing modules can increase its frequency up to 1.2 GHz. Comfortable operation on this device is ensured by 1 GB of RAM and 8 GB of integrated storage. A 2500 mAh battery is responsible for autonomy, this is enough for 1-2 days battery life. The price of this gadget is 8,000 rubles.
HTC T329d
HTC also has solutions for this digital standard. CDMA-standard phones from this manufacturer, although not so often, can still be found. One of the most affordable models is the HTC N329d. Like all previously reviewed gadgets, this smartphone is dual-band and can operate simultaneously in both a CDMA network and GSM coverage. At the heart of this device is a 2-core CPU that can dynamically accelerate to 1 GHz. The amount of RAM is 768 GB, and the built-in storage capacity is 4 GB. Screen diagonal - 4 inches. The resolution of 800x480 allows you to display the output image with sufficient quality. The battery capacity allows you to count on 2 days of battery life without recharging.
The device is equipped with a variety of wired and wireless information transfer methods that allow you to fully realize its potential. You can buy such a device now for 7,500 rubles.
Summary
This article answered the question: “CDMA phones - what are they and what are they for?” The characteristics and cost of real models of this type of device, operators mobile communications who provide services in this standard in Ukraine. Any of the above models will be an excellent purchase and will allow you to communicate and receive data from the Internet.
What's the difference between GSMAndCDMA?
As a rule, people do not think much about the difference in communication standards when choosing a mobile operator. But there are differences between them.
The first communication standards belonged to generation 1 G , which are wireless analogues of conventional telephone communication. But there were a number of disadvantages: the power of the transmitters was so high that it could have a bad effect on human health, small capacity base stations, poor interference protection, etc.
1 G was replaced by 2 G.
The first digital standard was GSM with improved interference protection, good quality speech transmission using a voice codec, protected from interception. It began to appear in 1991, gradually replacing all other standards. It was developed by the European Institute for Communication Standardization ( ETSI).
In 1993, Qualcomm technology CDMA developed a new standard IS-95 (cdmaOne), which appeared on the market in 1995.
Below we will try to figure out what the main differences between CDMA and GSM , and what are their advantages.
DifferencesCDMAAndGSM
The most important difference between these standards is the ability to work with frequency resources.
GSM uses channels separated by time and frequency, allocating for each subscriber a small frequency band over which the phone communicates with the base station. But at the same time, data exchange sessions are recorded in time. The signal is interrupted, but because... high frequency is used, the subscriber does not notice it. But in real life this can be noticed by the beeping sound in the speakers, which appears if there is a phone nearby that is receiving a call or a message or notification has arrived.
CDMA uses code division. Any subscriber who has a connection to the base station can use the entire available frequency resource, which is common to everyone, and the base station communicates with everyone. Each subscriber is assigned a specific code that distinguishes him from the general radio airwaves.
Below is an example for a general understanding of how communication standards work.
Let’s say there is a group of subscribers in the room, divided into pairs. The first part speaks one language at a time, for example for 30 seconds - scheme of work GSM.
And the second part speaks simultaneously in different languages - scheme of work CDMA.
Advantages of CDMA and GSM
The difference lies in the operating principles. Frequency band CDMA is wider than GSM - which result in certain advantages:
The quality of voice transmission is better, because the wider the frequency band, the more resistant it is to interference
Safety, because if you intercept the signal CDMA , then it will look like noise, from which it is difficult to identify a specific subscriber.
Less energy consumption of the communication device, because signal strength CDMA is less than GSM and depends on the distance to the base station. It is more difficult to isolate such a signal, because it has less power.
Advantage of CDMA is a large capacity of base stations, range, simplicity in network setup, resistance to overloads. CDMA - Operators are able to cover a larger area with less equipment, which is easier to set up.
So why if CDMA better, the most common standard is GSM ? At the time of creation CDMA GSM has already found its niche in the market with a ready-made selection of equipment for operators and consumers. Here's a more perfect one CDMA demanded considerable computing power, creating new solutions for new technology, and communication devices were more expensive than for GSM , plus they didn’t have compatibility yet.
And of course, ease of use played a significant role.
On GSM network the user could save the information to SIM -card, and when changing the phone you can simply rearrange it SIM-ku.
On a CDMA network the data was stitched into the phone itself, which did not have a slot for SIM -map. Therefore, when changing the phone, all the data had to be re-flashed.
For the CDMA standard, an analogue of SIM -cards appeared in 2002 - R-UIM . The emergence of dual-standard telephones also began. Therefore, gradually the problem with the choice was solved. American operators played a major role in giving impetus to the development of the standard. In Ukraine CDMA occupies a noticeably smaller share, the choice of phones is smaller, but some of the equipment is imported by operators, and subscribers themselves can buy a phone on international sites.
Considering the pros and cons, it turns out that from a consumer point of view, the standards look similar, the final choice comes down to operator coverage.
Evolution of communication
The above data was made on the basis of ordinary telephone communication, but in modern world It’s just that conversations have long become one of the operator’s services.
Let us now consider the quality of communication from the Internet access side.
Originally GSM gave the highest possible data transfer rate - up to 9.6 kbit/s. GPRS and EDGE technologies related to generation 2 G , developed this speed to 474 kbit/s. In generation 3 G technology is used to transmit data WCDMA , which is a derivative of CDMA.
CDMA initially had a high safety margin and provided the highest possible transmission speed - up to 153 kbit/s. AT 3 G networks used EV-DO technology for data transmission. Depending on the standard of the generation implemented - REV - the maximum transfer speed increased from 2.4/153 Mbit/s (Rev.0, upload/download) to 73.5/27 Mbit/s (Rev.B).
The figures given for each communication standard are approximate, because... real speed access may be much less.
Theoretically, further development is possible 3 G networks, increasing data transfer speeds, but in practice this looks dubious. So far, the available speed is enough to meet user requests.
