Phone with two standards gsm and cdma. Differences between CDMA and GSM standards

In this material, CDMA phones will be considered, 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.

The two main mobile standards

At the moment, the most widespread are mobile devices of two standards: GSM and CDMA. Each of them is a digital standard. But the signal transmission in each of these cases is carried out in a different way. In the first case, it is divided into parts, each conversation occupies only a small part of the spectrum. In the second case, the encoding allows the subscriber to use the entire radio frequency resource. As a result, in this case, the quality of communication is much better. But today devices for mobile networks of the first type have become more widespread. This standard was presented much earlier and at the time of the announcement of CDMA solutions it was already actively used. Now we will get an answer to the question: "CDMA phones - what kind of devices are they?" These are devices that are targeted at mobile CDMA networks. Likewise, GSM solutions are only used in such cellular networks.

Supported devices

Many devices are oriented towards functioning. First of all, these are mobile phones of the corresponding standard. They have a relatively low level of functionality: conversation, text and multimedia messages. In some cases, this list can be extended by data transmission. So the answer to the question: "CDMA phones - what are they?" - is such a definition: "This is a device that allows you to make calls, send and receive text or multimedia messages or connect to the Internet in CDMA networks." The second type of device that can be used in such networks is modems. They can perform only one task - to provide transmission and reception of data from the global web to a PC. Another type of device is mobile Wi-Fi routers. They do the same thing as modems, but in this case, the presence of 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. These are mobile devices, the capabilities of which are enhanced through the use of special software. In this case, you can watch videos, listen to music, and communicate on social networks ... You can even use it as a mobile Wi-Fi router.

Operators in Ukraine

Until recently, there were quite a few mobile operators in Ukraine that functioned in this standard. These are Welton, and Ukrainian Wave, and People.net, and Intertelecom. But now only the last two continue to provide services. The first two of them were acquired by Intertelecom, and their subscribers joined its cellular network. In turn, People.net, due to economic difficulties, began to "roll up" 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. Its subscriber base is based on 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 the owners of CDMA devices can work in Ukraine only in one cellular network.

Lenovo A330e

A 5-inch display diagonal and an 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 accelerate 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 supplied battery is 2000 mAh, which will definitely be enough for 2 days of use. The operating system in this case is "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 operates under the control of "Android". Its computing basis is the 2-core "Snapdragon" MCM8625 with a peak frequency of 1 GHz. The RAM is 0.5 GB, and the capacity of the built-in storage is equal to the "modest" 4 GB. The diagonal of the display is only 4 inches, and its resolution is 480x800. The battery with a capacity of 1350 mAh is responsible for the autonomy. This is definitely enough for 1 day of work. The price for this device is 5750 rubles.

Lenovo A805E

It is the most affordable 5.5-inch GSM-CDMA mobile phone at the moment. 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 work on this device is provided by 1 GB of RAM and 8 GB of integrated storage. A 2500 mAh battery is responsible for autonomy, this is quite enough for 1-2 days of 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 more affordable models is the HTC N329d. Like all previously reviewed gadgets, this smartphone is dual-band and can work simultaneously in 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 capacity of the built-in storage is 4 GB. The diagonal of the screen is 4 inches. The resolution of 800x480 allows you to display the displayed 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 communication methods that allow you to fully and fully unleash its potential. You can buy such a device now for 7,500 rubles.

Summary

This article answered the question: "CDMA phones - what are these devices and what are they for?" Also indicated are the characteristics and cost of real models of this type of device, mobile operators who provide services in this standard in Ukraine. Any of these models will be a great buy and will allow you to communicate and receive data from the Internet.

In this review we will talk about the CDMA communication standard - we will discuss the characteristics and principle of operation, we will give a full detailed description. Let's consider the differences from other standards, the spread of technology in Russia and tell you about special smartphones.

Description and characteristics

Let's start the article by defining what it is, CDMA in a smartphone.
CDMA is (from the English Code Division Multiple Access) communication standard of the second generation, which is analogous to GSM.

Please note that these are not interchangeable technologies, but two communication methods that compete with each other. What is the difference between CDMA and GSM? Let's talk in detail below.

The connection of two subscribers within the framework of this technology occurs by allocating a spectrum of frequencies, the identification of connections is carried out using special codes.

For now, let's consider the advantages of the technology:

  • Excellent information security;
  • Good sounding voice when calling, no interference;
  • Minimization of communication failures;
  • High speed of data transfer;
  • High capacity of the cellular network;
  • Economical battery consumption;
  • Reducing the radiation level of the mobile device.

The standard was adopted in 1992, although development was carried out much earlier, and has become widespread in many countries around the world. Until now, CDMA phones are actively used in various countries - in Africa, China and others.

CDMA-450 or CDMA 2000 appeared in 2000 - the standard operates at 450 MHz and was actively distributed in Russia, mainly the CDMA communication standard was present in Moscow.

At the moment - in 2018 in Russia all CDMA operators are closed, no telecommunications company provides such services. In our country, a more familiar format is used - GSM.

Differences from GSM

Let's highlight the differences between the technology described above and GSM. Despite the fact that both standards belong to the same generation, they have a slight difference in how they work:

  • Ability to interact with frequency resources. GSM uses time and frequency separated channels, while the second technology is based on code division;
  • SDMA bandwidth is wider than the competitor, which improves voice quality and reduces interference;
  • Less power consumption, since the signal power is significantly reduced and depends on the distance to the base station;
  • SDMA has a large station capacity, wide range and easy network setup.

And what is the difference between WCDMA and CDMA - WCDMA technology is a derivative of SDMA and belongs to the third generation of mobile communications (3G). At the moment, these technologies cannot be used simultaneously and are a transitional stage to the latest standard - LTE.

Smartphones

In this part of the section, we will discuss dual-standard smartphones. At the moment, both of the second generation standards described above are widespread throughout the world and cannot be used at the same time - but there is one exception.

These are special devices designed for use in two networks at the same time - the capabilities are expanded through the installation of special software. Smartphones are equipped with the ability to receive a signal in two different ways, specific to these networks.

There are quite a number of smartphone manufacturers offering dual-band products with two SIM cards - these are giants such as Xiaomi, Lenovo, Huawei, HTC and many others. In addition, you can purchase a modem that works in the required range.

What's the difference between GSMandCDMA?

As a rule, people do not really think 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 analogs 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, the small capacity of base stations, poor protection against interference, etc.

1 G was replaced by 2 Gs.

The first digital standard was GSM with improved protection against interference, good quality of speech transmission due to the voice codec, protection against interception. It began to appear in 1991, gradually replacing all other standards. It was developed by the European Institute for Communication Standardization ( ETSI).

1993 Qualcomm Technology CDMA developed a new standard, IS-95 (cdmaOne), which entered the market in 1995.

Below we will try to figure out what are 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 the frequency resource.

GSM uses channels separated by time and frequency, allocating a small frequency band for each subscriber, through 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 a high frequency is used, the subscriber does not notice it. But in real life, this can be seen by the squeaking sound in the speakers, which appears if there is a phone nearby that is being called or a message or notification has been received.

CDMA uses code division multiplexing. Any subscriber who has a connection to a base station can use the entire available frequency resource, which is common to all, while the base station communicates with everyone. Each subscriber is assigned a specific code that distinguishes him from the general radio air.

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 in turn, for example, 30 seconds each - the scheme of work GSM.

And the second part speaks different languages ​​at the same time - the scheme of work CDMA.

Benefits of CDMA and GSM

The difference lies in how it works. Frequency band at CDMA is wider than GSM - which translate into certain advantages:

Better voice transmission quality. the wider the bandwidth, the more resistant it is to interference

Security, because if you intercept the signal CDMA , then it will look like noise, from which it is difficult to distinguish a specific subscriber.

Less power consumption of the communication device, because signal strength CDMA less than GSM and depends on the distance to the base station. Such a signal is harder to distinguish, since it is less powerful.

The advantage of CDMA is a large capacity of base stations, range, simplicity in network configuration, resistance to congestion. CDMA - Operators have the ability to cover a larger area with less equipment that 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 taken its niche in the market with a ready-made choice of equipment for operators and consumers. But more perfect CDMA required considerable computing power, the creation of new solutions for a new technology, and communication devices were more expensive than for GSM , plus did not have compatibility yet.

Well, and of course, ease of use played a significant role.

In GSM network the user could save information to SIM -card, and when changing the phone, simply rearrange SIM card.

On CDMA network the data was stitched into the phone itself, in which there was no slot for SIM -card. Therefore, when changing the phone, all data had to be flashed again.

For CDMA standard SIM analog -cards appeared in 2002 - R - UIM ... The emergence of dual-standard phones also began. Therefore, gradually the problem with the choice was resolved. American operators played an important role, which gave impetus to the development of the standard. In Ukraine CDMA occupies a noticeably smaller share, the choice of phones is less, but part of the equipment is imported by operators, and subscribers can buy a phone on international platforms themselves.

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.

Communication evolution

The above data was made on the basis of ordinary telephone communication, but in the modern world, simple conversations have long become one of the operator's services.

Let us now consider the quality of communication from the side of Internet access.

Originally GSM gave the maximum possible data transfer rate - up to 9.6 kbps. Generation 2 GPRS and EDGE technologies G , developed this speed up to 474 kbps. In generation 3 G technology is used for data transmission WCDMA derived from CDMA.

CDMA initially had a high margin of safety and gave the maximum possible transfer rate - up to 153 kbps. AT 3 G networks for data transmission used EV-DO technology. Depending on the standard of the implemented generation - REV - the maximum transfer speed has become from 2.4 / 153 Mbps (Rev.0, upload / download) to 73.5 / 27 Mbps (Rev.B).

The figures given for each communication standard are approximate. the actual access speed may be much slower.

Theoretically, further development is possible 3 G networks, an increase in the data transfer rate, but in practice this looks questionable. So far, the available speed is sufficient for user requests.

In connection with the increasing questions about CDMA and GSM phones, and the resulting confusion, I will try to clarify the difference between them. CDMA phones are cheaper in most cases, and many hope that they will work with Kyivstar, MTS or Life.

I can safely dispel this myth and explain in detail.

About GSM communication standard

GSM is a communication standard that is actively used by our operators Kyivstar, MTS and Life. These operators have become a part of our everyday life, and many buyers are buying phones. Because we buy phones in 90% of cases with these operators in mind. Recall that the GSM communication standard is based on a channel frequency division algorithm, using TDMA technology (common frequencies are divided in time), and medium-level security. There are four main GSM frequency bands, and accordingly phones are divided into three groups:

  • Single-band - used in a limited number of models, the selection of the desired frequency can be performed through a special engineering menu
  • Dual Band - operate at 900/1800 (Asia, Africa, Australia, Europe) and 850/1900 (Canada, USA). Phones have a rigid regional binding
  • Tri-band (English Tri-Band) - 900/1800/1900 (Asia, Africa, Australia, Europe) and 850/1800/1900 (Canada, USA).
  • Quad-Band - all four bands are used accordingly - 850/900/1800/1900. These include all new smartphones released with rare exceptions.

Services that are available to the user of a GSM phone - voice calls, SMS, fax, roaming (convenient transition from network to network in other countries while maintaining the subscriber's mobile number), packet data exchange using WAP / GPRS / EDGE technologies. You can read about the differences from 3G and setting up the mobile Internet in this section ... As a disadvantage, GSM operators do not provide 3G Internet and telephony services.

About CDMA communication standard

CDMA communication standard has firmly entered the US market as the development of cellular communications, and the name itself denotes the principle of working with frequencies. Each frequency is used throughout the entire time by all subscribers, special codes are used for access. It has a high degree of security, which excludes the possibility of intercepting a message, since the entire spectrum is occupied by noise, and each signal is accompanied by a unique code. The total bandwidth allows you to occupy one frequency and serve a larger number of subscribers. Network congestion can only cause a deterioration in communication, but not an opportunity not to get through (this is a feature of GSM). The second feature is quieter and harmless frequencies for the subscriber.

CDMA2000 - A modern communication standard that is actively developing. The frequency is 1.23 MHz, and the packet data rate is 2 Mbps. As you know, the power of the radiation itself is rather weak against GSM (250 mW versus 2W for GSM900). It can also be argued that the harm of radiation has not been proven, but there is also no refutation.

To connect smartphones, either a special RUIM card is used, or the phone is simply stitched in the operator's service center.

Benefits of CDMA?

CDMA phones offer a rather unusual type of service - direct city number, mobile number, message transfer, packet data exchange using CDMA EVDO 3G technology at a speed of 2.3 Mbit per second. Quite loyal tariffs and a convenient option for buying a direct city number make CDMA phones the most attractive in Ukraine. After all, the service of a direct city number for a GSM operator costs an average of 200 UAH per month for call forwarding. Here, rates can be up to 30-50 UAH per month. Operators in Ukraine provide sufficient quality service to subscribers CDMA Ukraine and Intertelecom.

How to turn on a CDMA smartphone


There is one slight inconvenience when buying a CDMA smartphone. You will not be able to check the connection on the spot at the time of purchase. Since there is no understandable SIM card here, and some phones do not even have a slot for connection. Therefore, further activation of your purchase takes place either at the operator's service center or at its authorized dealer. When buying a new CDMA phone, you will be asked to conclude a contract and you will be assigned your mobile and landline number (you will be offered a choice from the available ones). After successful activation, all services will work on your smartphone. Yes, Intertelecom and CDMA Ukraine services work only under a contract, so to connect your phone, be sure to take your passport.

How to check IMEI? He's not there!

We remind you that IMEI CDMA phones are not present under the control of the Ukrchastotnadzor base, and when buying a CDMA smartphone, you can rest assured that your phone is on a gray, white, black or light green list. That is why CDMA Phones are especially popular. You can read about the lists and the current state on them.

Conclusions:

Now let's take a quick overview of the above:

  • CDMA phones work in other frequencies and are incompatible with GSM operators - KYIVSTAR, LIFE, MTS, UTEL, UkrTelekom
  • CDMA phones are served only by CDMA operators - CDMA Ukraine or Intertelecom
  • CDMA phones may not have a slot for an operator card, and more often they are simply stitched to the desired number
  • CDMA phones are serviced on a contract basis
  • CDMA phones work in 3G data transfer mode
  • CDMA phones provide a free and without forwarding direct landline number in addition to a mobile
  • CDMA phones do not have IMEI in the UDTSR database lists and cannot be disabled as "gray", "black".
  • CDMA phones can be much cheaper than GSM counterparts

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 cellular communication.

But not everyone 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 it is also used in some African and Asian countries, where it competes with GSM.

Here's what mobile 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 is completely justified. But in this case, there is no simple answer to it.

GSM and CDMA Are different ways to achieve the same goal. And the fact that popular networks are 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 opted for GSM.

From a technical point of view, no standard has a quality advantage. But there are a few things you must 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.

In addition, most phones support either GSM or CDMA, so your choice of phone may determine which standard you end up using. In addition, it all depends on which operators are available in your territory. Some areas are better covered by GSM providers, while others may benefit from CDMA providers.

Many phones are compatible with GSM or CDMA, but not both. In the case of CDMA phones, you will need to purchase a device made specifically for your carrier. The easiest way is to buy it directly from this operator. For example, if you want to use an iPhone on the Verizon 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 search for unlocked GSM phones from third-party retailers. These phones will work with any GSM operator, you just need to change the SIM card. For example, Amazon sells many unlocked GSM phones. Google's Nexus 5 and some devices in versions are also unlocked. Any retail or online retailer that sells cell phones must provide information on which networks each particular device can work with.

Be careful with phone compatibility. Devices sold in markets where both standards work most often support either GSM or CDMA. Only a few phones are compatible with both standards. If you bought 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 buy a SIM card and insert it into the device to activate its network capabilities.

CDMA phone owners do not need to worry about SIM cards, but this is more of a curse than a blessing. CDMA devices are bogged down in compatibility restrictions that are difficult to circumvent, and GSM phone owners can simply remove the SIM card and replace it with another. Most CDMA networks do not allow a phone purchased from another carrier to be used, even if it is technically compatible. It is very important to keep this limitation in mind when choosing a CDMA network. If you later decide to change carriers, you will most likely have to buy a new phone, even if the network you are switching to also uses CDMA.

Despite the fact that GSM is more open, access can still be limited to the frequency range supported by the phone. Frequencies range from 380 to 1900 MHz and depend on local operators. You should check what frequencies your carrier 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 telephones".

If you understand the importance GSM and CDMA, perfect! Now, let's break your arrogance completely by talking about the newbie, LTE (Long Term Evolution).

LTE is the new standard, which has become fashionable over the past few years. Although it is based on GSM principles, it is still a separate standard operating outside of GSM and CDMA networks. This is the true fourth generation of cellular data transmission.

LTE is most widespread in South Korea, where this standard is used by most of the market, but it is also popular in Japan, Australia, Sweden and the United States. So far, 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 can switch to other networks, if of course the device supports them, 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 can take several years.

While this standard has great potential, there are obstacles to its dissemination. Outside South Korea, LTE does not occupy more than a quarter in any market. South Korea in general and Verizon Wireless in the US are actually the exception to the rule. In most markets, even LTE operators only offer it in limited areas.

There is also a problem with the spectrum. Remember that GSM / CDMA operates on many different frequencies? The same is true for LTE. You will have to check if your phone is compatible with the frequency bands supported by the carrier, and you will not be able to use your LTE phone on another network with the same standard but different frequencies. It is not clear yet whether this standard will become "worldwide", in the same sense as GSM, which settled on the four main frequencies supported by most GSM phones.

Summarizing

Take a deep breath. It's time to take stock of all that has been said.

First, neither GSM nor CDMA do not have advantages 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 tied to one operator. It is usually cheaper to purchase unlocked GSM phones than contractual CDMA devices.

Third, 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 may become a global standard, but it is falling prey to even greater frequency division than GSM and CDMA. This technology is relatively new and has not yet been widely implemented.

Hope that clears it up. Cellular networks are constantly evolving and the standards supported by phones can change from year to year. Feel free to ask your questions in the comments.

Dessert Iphone 6

Happy viewing!

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