EDGE technology: what is it and why is it needed?
The past 3GSM World Congress, followed by CeBIT 2006 in Hannover, brought with them a lot of new announcements cell phones with support for EDGE technology (Enhanced Data for Global Evolution or, as you can sometimes hear, Enhanced Data rates for GSM Evolution). This is no coincidence - although vendors mobile phones pay more and more attention to supporting third generation (3G) standards, such as CDMA2000 1x, W-CDMA and UMTS, the development of 3G networks is extremely slow, and interest in second generation (2G) and second and a half (2.5G) networks is not is weakening, but, on the contrary, growing, both in the markets of developing countries and in the markets of developed countries.
Evolution of cellular standards
In the name of "propaedeutics without bloodshed" I will return a little to history and tell you about what generations of cellular communication standards are now known to science. Those of you who are already familiar with this issue can skip straight to the next section on the EDGE technology itself.
iSo standards first generation cellular communication (1G), (developed in 1978, introduced into service in 1981) and (introduced in 1983), were analog: a low-frequency human voice was transmitted on a high-frequency carrier (~ 450 MHz in the case of NMT and 820-890 MHz in the case AMPS) using an amplitude-frequency modulation scheme. In order to provide communication for several people at the same time, in the AMPS standard, for example, the frequency bands were divided into channels with a width of 30 kHz - this approach was called FDMA (Frequency Division Multiple Access). First generation standards were created for and provided exclusively for voice communications.
Standards second generation (2G), such as (global system for mobile communications) and (Code Division Mutiple Access), brought with them several innovations. In addition to the frequency division of FDMA communication channels, the human voice was now digitized (coding), that is, a modulated carrier frequency was transmitted over the communication channel, as in the 1G standard, but not with an analog signal, but with a digital code. This is a common feature of all second generation standards. They differ in the methods of "multiplexing" or channel separation: GSM uses the TDMA (Time Division Multiple Access) approach, and CDMA uses Code Division Mutiple Access, which is why this standard is called that. Second-generation standards were also created to provide voice communication, but due to their "digital nature" and in connection with the need to provide Internet access via mobile phones during the spread of the Global Web, they made it possible to transfer digital data via a mobile phone, like a regular wired modem. Initially, the second generation standards did not provide high throughput: GSM could provide only 9600 bit / s (this is exactly what is required to provide voice communication in one "compressed" channel using TDMA), CDMA - several tens of Kbit / s.
In standards third generation (3G), the main requirement for which, according to the specifications of the International Telecommunication Union (ITU) IMT-2000, was to provide video communication at least in QVGA (320x240) resolution, it was necessary to achieve a digital data transmission capacity of at least 384 Kbit / s. To solve this problem, frequency bands of increased width (W-CDMA, Wideband CDMA) or a larger number of simultaneously used frequency channels (CDMA2000) are used. By the way, initially the CDMA2000 standard could not provide the required bandwidth (providing only 153 Kbps), however, with the introduction of new modulation schemes and multiplexing technologies using orthogonal carriers in 1x RTT and EV-DO add-ons, the threshold is 384 Kbps. s was successfully overcome. And such a data transmission technology as CDMA2000 1x EV-DV will have to provide a bandwidth of up to 2 Mbit / s, while the HSDPA (High-Speed \u200b\u200bDownlink Packet Access) technology currently being developed and promoted in W-CDMA networks is up to 14.4 Mbps.
In addition, in Japan, South Korea and China, work is now underway on the next, fourth generation standards, which can, in the future, provide transmission and reception rates of digital data in excess of 20 Mbit / s, thus becoming an alternative to wired broadband networks.
However, despite all the prospects that third generation networks promise, not many are in a hurry to switch to them. There are many reasons for this: the high cost of telephones, caused by the need to return the funds invested in research and development; and the high cost of airtime associated with the high cost of licenses for frequency bands and the need to switch to equipment incompatible with the existing infrastructure; and short battery life due to excessively high (compared to second generation devices) load when transferring large amounts of data. At the same time, the standard of the second generation GSM, due to the originally built in it the possibility of global roaming and the lower cost of devices and airtime (here the licensing policy of the main supplier of CDMA technologies, Qualcomm, played a cruel joke with it), received a truly global distribution, and already last year the number of GSM subscribers exceeded 1 billion. It would be wrong not to take advantage of the situation both from the point of view of operators who would like to increase the average revenue per subscriber (ARPU) and ensure the provision of services that are competitive with those of 3G networks, and from the users who would like to have mobile access to the Internet. The same thing that happened with this standard in the future can be called a small miracle: it was invented evolutionary approach, whose ultimate goal was to transform GSM into a third generation standard compatible with UMTS (Universal Mobile Telecommunications System).
Strictly speaking, mobile Internet access has been available for a long time: CSD (Circuit-Switched Data) technology allowed a modem connection at a speed of 9600 bps, but, firstly, it was inconvenient due to the low speed, and secondly - due to per-minute billing. Therefore, at first, data transmission technology (General Packet Radio Service) was invented and implemented, which marked the beginning of the transition to a batch approach, and then EDGE technology. By the way, there is also an alternative GPRS technology HSCSD (High-Speed \u200b\u200bCircuit Switched Data), but it is less common, since it also implies per-minute tariffication, while GPRS takes into account traffic - packet forwarding. This is the main difference between GPRS and various technologies based on the CSD approach: in the first case, the subscriber terminal sends over the air packets that go with arbitrary channels to the addressee, in the second, a point-type connection is established between the terminal and the base station (acting as a router) -point using a standard or extended communication channel. The GSM standard with GPRS technology occupies an intermediate position between the second and third generations of communication, therefore it is often called the second and a half generation (2.5G). It is also called that way because GPRS marks half the way for GSM / GPRS networks to be UMTS compatible.
EDGE technology, as you might guess from its name (which can be translated as "improved data rates for the evolution of the GSM standard") plays two roles at once: firstly, it provides higher bandwidth for transmitting and receiving data, and secondly , serves as another step from GSM to UMTS. The first step, the introduction of GPRS, has already been done. The second step is not far off - the introduction of EDGE has already begun in the world and in our country.
Coverage map of the EDGE network of the operator "Megafon" in Moscow (at the end of February 2006)
EDGE - what is it and what is it eaten with?
EDGE technology can be implemented by two different ways: As an extension of GPRS, in which case it should be called EGPRS (enhanced GPRS) or as CSD extension (ECSD). Considering that GPRS is much more widespread than HSCSD, let's dwell on EGPRS.
1. EDGE is not a new cellular standard.
However, EDGE implies an additional physical layer that can be used to increase the capacity of GPRS or HSCSD services. At the same time, the services themselves are provided in the same way as before. Theoretically, the GPRS service is capable of providing throughput up to 160 Kbps (at the physical layer, in practice, devices supporting GPRS Class 10 or 4 + 1/3 + 2 provide only up to 38-42 Kbps and then, if the congestion of the cellular network allows), and EGPRS - up to 384-473.6 Kbps. This requires the use of a new modulation scheme, new methods of channel coding and error correction.
2. EDGE, in fact, is an "add-on" (or rather, an adjustment, if we assume that the physical layer is below the rest) to GPRS and cannot exist separately from GPRS. EDGE, as mentioned above, implies the use of different modulation and code schemes, while maintaining compatibility with the CSD voice service.
Figure 1. Modified nodes are shown in yellow.
Thus, from the point of view of the client terminal, nothing should change with the introduction of EDGE. However, the base station infrastructure will undergo some changes (see Fig. 1), albeit not so much. In addition to increasing the bandwidth for data transmission, the introduction of EDGE increases the capacity of the cellular network: you can now “pack” a larger number of users into the same time slot, so you can hope not to receive a “network busy” message at the most inopportune moments.
| Table 1. Comparative characteristics of EDGE and GPRS | ||
| GPRS | EDGE | |
| Modulation circuit | GMSK | 8-PSK / GMSK |
| Symbol rate | 270 thousand per second | 270 thousand per second |
| Bandwidth | 270 kbps | 810 kbps |
| Time slot bandwidth | 22.8 kbps | 69.2 kbps |
| Data transfer rate per time slot | 20 kbps (CS4) | 59.2Kbps (MCS9) |
| Data transfer rate using 8 time slots | 160 (182.4) kbps | 473.6 (553.6) kbps |
Table 1 illustrates the different technical specifications for EDGE and GPRS. Although both EDGE and GPRS send the same number of symbols per unit of time, due to the use of a different modulation scheme, the number of data bits in EDGE is three times more. Let us immediately make a reservation here that the values \u200b\u200bof throughput and data transfer rates given in the table differ from each other due to the fact that the first also takes into account packet headers, which are unnecessary for the user. Well, the maximum data transfer rate of 384 Kbps (required to comply with the IMT-2000 specifications) is obtained if eight time slots are used, that is, there is 48 Kbps for each time slot.
EDGE modulation circuit
In the GSM standard, the modulation scheme GMSK (Gaussian minimum shift keying) is used, which is a type of phase modulation of the signal. To clarify the principle of the GMSK circuit, consider the phase diagram in Fig. 2, which shows the real (I) and imaginary (Q) parts of the complex signal. The phase of the transmitted logic "0" and "1" differ from each other by the phase p. Each character transmitted per unit of time corresponds to one bit.
Figure 2. Different modulation schemes in GPRS and EDGE.
EDGE uses the 8PSK modulation scheme (8-phase shift keying, the phase shift, as seen from the figure, is equal to p / 4), using all the same specifications for the structure of frequency channels, coding and bandwidth as in GSM / GPRS. Accordingly, adjacent frequency channels create exactly the same mutual interference as in GSM / GPRS. The smaller phase shift between symbols, which now encodes not one bit, but three (symbols correspond to combinations of 000, 001, 010, 011, 100, 101, 110 and 111), makes the task of detection more difficult, especially if the signal level is low. However, in conditions of good signal level and stable reception, it is not difficult to discriminate against each character.
Coding
GPRS can use four different coding schemes: CS1, CS2, CS3 and CS4, each of which uses its own error correction algorithm. For EGPRS, nine coding schemes have been developed, MCS1..MCS9, respectively, whose purpose is also to provide error correction. Moreover, in the "lower" MSC1..MSC4 modulation scheme GMSK is used, in the "senior" MSC5..MSC9 - the modulation scheme 8PSK. Figure 3 shows the dependence of the data transfer rate on the use of different modulation schemes, coupled with different coding schemes (the data transfer rate varies depending on how much redundant information required for the operation of error correction algorithms is put into each encoded packet). It is easy to guess that the worse the reception conditions (signal-to-noise ratio), the more redundant information has to be added to each packet, and therefore the lower the data transfer rate. The slight difference in data rate observed between CS1 and MCS1, CS2 and MCS2, etc. is due to the difference in the size of the packet headers.
Figure 3. Different code schemes in GPRS and EDGE.
However, if the signal-to-noise ratio is small, not all is lost: the older modulation-code schemes EGPRS MCS7, MCS8, MCS9 provide for an overlay procedure: since the standard is able to send groups of packets on different carriers (within the frequency range), for each of which conditions (and above all - "noisiness") can be different, in this case, the retransmission of the entire block can be avoided if you know in which group the failure occurred and re-broadcast this particular group. Unlike the older code scheme GPRS CS4, which does not use a similar error correction algorithm, in EGPRS MCS7, MCS8, MCS9, different data blocks are "superimposed" on each other, therefore, if one of the groups fails (as shown in the figure), re-transmission only half of the packages are subject (see Figure 4).
Figure 4. Using overlay packet groups in EDGE.
Packet processing
If for some reason a packet sent using the "higher" coding schemes was not received correctly, EGPRS allows it to be retransmitted using the "lower" coding scheme. GPRS did not provide for such a possibility, called "resegmentation": an incorrectly received packet is sent again using the same modulation-coding scheme as in the previous time.
Addressing window
Before a sequence of encoded (ie, multi-bit "words") packets (frame) can be transmitted over the RF interface, the transmitter assigns the packets an identification number included in the header of each packet. Packet numbers in GPRS range from 1 to 128. After a sequence of packets (for example, 10 pieces) is sent to the addressee, the transmitter waits for the receiver to confirm that they have been received. The report that the receiver sends back to the transmitter contains the packet numbers that were successfully decoded and that the receiver was unable to decode. An important nuance: packet numbers take values \u200b\u200bfrom 1 to 128, and the width of the address window is only 64, as a result of which a newly transmitted packet can receive the same number as in the previous frame. In this case, the protocol is forced to resend the entire current frame, which negatively affects the data transfer rate in general. To reduce the risk of such a situation in EGPRS, the packet number can take values \u200b\u200bfrom 1 to 2048, and the address window is increased to 1024.
Measurement accuracy
To ensure the correct functioning of the GPRS technology in the GSM environment, it is necessary to constantly measure the radio conditions: the signal / noise level in the channel, the error rate, etc. These measurements do not affect the quality of voice communication in any way, where it is enough to constantly use the same coding scheme. When transmitting data to GPRS, the measurement of radio conditions is possible only in "pauses" - twice in a period of 240 ms. In order not to wait every 120 ms, EGPRS defines such a parameter as the bit error probability (BEP) in each frame. The BEP is influenced by both the signal-to-noise ratio and the time dispersion of the signal and the speed of the terminal. Changing the BEP from frame to frame allows you to estimate the terminal speed and jitter, but for a more accurate estimate, the average value of the probability of error per bit for every four frames and its sample standard deviation are used. As a result, EGPRS responds more quickly to changes in conditions: it increases the data transfer rate when the BEP decreases and vice versa.
Control over the connection speed in EGPRS
EGPRS uses a combination of two approaches: link speed tuning and incremental redundancy. Adjusting the connection speed, measured either by the mobile terminal by the amount of data received per unit of time, or by the base station by the amount, respectively, of the transmitted data, allows you to select the optimal modulation-code scheme for subsequent data volumes. Typically, the use of a new modulation code scheme can be assigned when a new block (four groups) of data is transmitted.
Incremental redundancy is natively applied to the oldest modulation code scheme, MCS9, with little attention to error correction and no consideration of radio conditions. If the information is decoded by the addressee incorrectly, not the data itself is transmitted over the communication channel, but a certain control code that is "added" (used for conversion) to the already loaded data until the data is decoded successfully. Each such "incremental piece" of complementary code increases the probability of successful decryption of the transmitted data - this is the redundancy. The main advantage of this approach is that there is no need to monitor the quality of radio communications, therefore incremental redundancy is mandatory in the EGPRS standard for mobile terminals.
EGPRS integration into existing GSM / GPRS networks - UMTS is just around the corner!
As mentioned above, the main difference between GPRS and EGPRS is the use of a different modulation scheme at the physical layer. Therefore, to support EGPRS, it is sufficient to install a transceiver that supports the new modulation schemes and software for processing packets on the base station. To ensure compatibility with non-EDGE mobile phones, the standard specifies the following:
- EDGE and non-EDGE mobile terminals must be able to use the same timeslot
- Supported and non-EDGE capable transceivers must use the same frequency range
- Partial EDGE support possible
- Supporting the 8PSK modulation scheme only in the downlink data stream and
- Supports 8PSK in both receive and uplink data streams
The introduction of EGPRS, as mentioned above, allows achieving throughput that is about three times more than in GPRS technology. In this case, exactly the same QoS profiles (quality of service, quality of service) are used as in GPRS, but taking into account the increased bandwidth. In addition to the need to install the transceiver in the base station, EGPRS support requires a software update to handle the modified packet protocol.
The next evolutionary step on the way of GSM / EDGE cellular communication systems to "full-fledged" third generation networks will be further improvement of packet (data) forwarding services to ensure their compatibility with UMTS / UTRAN (UMTS terrestrial radio access network). These improvements are currently under review and are likely to be incorporated into a future version of the 3GPP (3G Partnership Project) specifications. The main difference between GERAN and the currently deployed EDGE technology will be QoS support for interactive, background, streaming and conversation classes. Support for these QoS classes is already available in UMTS, which makes it possible, for example, for video communication in UMTS networks (say, W-CDMA 2100 or 1900 MHz). In addition, in the next generation of EDGE, it is planned to provide simultaneous parallel processing of data streams with different QoS priorities.
What is EDGE. Its advantagesRecently, a mysterious word has been appearing on the shelves of our stores more and more often EDGE... What is this terrible beast, what are the advantages of this technology and what is its future in Russia?
Originally EDGE was meant as an extension of GPRS technology. For the first time they started talking about it back in 1997 at ESTI (European Telecommunication Standardization Institute). At the same time, its first decryption was presented as Enhanced Data Rates for GSM Evolution (Enhanced Data Transfer Technology for GSM Evolution). EDGE employs eight-position phase shift keying (8-PSK), which provides approximately 2 times the maximum speed compared to GPRS - it is 384 Kbps, while the maximum theoretical GPRS speed is 171 Kbps. Of course, the real speed is much lower. To transmit information EDGE, as well as GPRS, uses timeslots (time intervals of a frame). There is an identical GPRS policy for distributing timeslots between channels for receiving and transmitting. Another advantage is that the maximum stream rate in one timeslot is 48 kbps (versus 9.6 kbps for GPRS). Naturally, this speed is achieved only with perfect reception, in reality everything will be much worse. Depending on the quality of communication, 9 coding algorithms are provided from MCS-1 to MCS-9 (the latter has the smallest coding redundancy, respectively - the fastest).
Subsequently, with the advent of the specification of 3rd generation networks, the name EDGE was rephrased and now it stands for Enhanced Data rates for Global Evolution (Advanced Data Transfer Technology for Global Development). So we can say that EDGE is a full-fledged transitional link on the way to 3G or, as it is sometimes called, 2.5G.
Primary Application of EDGE Is a high-speed Internet access, the organization of a mobile office is an indispensable thing for business people. And also, such opportunities as: exchange of pictures, photos and other information via the same Internet, watching streaming video, Internet radio, sending faxes, mail, and many, many other interesting things. Based on its merits, we can say that EDGE technology is designed for 2 different classes of the population: for businessmen, for whom it is important to always be aware of the latest events, and for adolescents / teenagers for whom the Internet is a lifestyle.
It is also impossible to give a definite answer to the question which is better than GPRS or EDGE, although at the moment the use of GPRS is more justified than the use of EDGE. This is mainly due to the fact that GPRS is widespread, and EDGE is just beginning to spread in Russia. But EDGE, unlike GPRS, whose connection is very unstable, and the speed in rare cases rises above 56 Kbps, there are two incomparable advantages: high speed and quality of connection. Therefore, EDGE technology has every chance to replace the obsolete GPRS technology.
Users of mobile phones or tablets with SIM card support may have noticed that the icon next to the antenna, symbolizing data transmission, can change to one of the following: G, E, 3G, 3.5G, 3G +, H, H +, 4G, L or LTE ... Let's try to figure out what each of them means.
G (GPRS)
GPRS (General Packet Radio Service - "general packet radio communication") is an add-on over GSM mobile communication technology, which carries out packet data transmission. It is one of the first implementations of the mobile Internet. Today, an outdated way of connecting to the World Wide Web. The theoretical maximum data transfer rate is 171.2 Kbps (depending on the GPRS class).
E (EDGE)
EDGE (Enhanced Data rates for GSM Evolution) or Enhanced GPRS - digital technology wireless transmission data for mobile communications, which is an add-on over 2G and 2.5G (GPRS) networks.
Connecting to the network via EDGE is about 3 times faster than via GPRS, namely, the maximum data transfer rate can be 474 Kbps. In the picture above, the connection speed measured by the application is in KB / s (kilobytes per second). To convert to kilobits per second, you need to multiply the displayed value by 8, that is, 17 Kbps x 8 \u003d 136 Kbps.
3G
3G (from the English third generation - the third generation) - mobile communication technologies of the 3rd generation - a set of services that combines both high-speed mobile access to the Internet, and radio communication technology, which creates a data transmission channel (voice, messages, etc.) etc.). Currently, this term most often refers to UMTS technology with an HSPA add-on (hence the "H" or "H +" icon on the phone).
Third generation 3G networks operate at frequencies slightly higher than traditional GSM (850 MHz, 900 MHz, 1800 MHz, 1900 MHz), namely 1900-2100 MHz, which, in addition to other serious differences from GSM and improvements, allows increasing the bandwidth and , respectively, the data transfer rate.
Varieties of 3G
HSPA
The maximum theoretical data transfer rate according to the HSPA standard is 14.4 Mbps (the data transfer rate from the base station to all local subscribers) and up to 5.76 Mbps from the subscriber. The first stages of implementation of the standard had a speed of 3.6 Mbit / s to an HSDPA subscriber (D - downlink). After the introduction of the second stage of HSUPA (U - uplink, that is, accelerating the transmission from the subscriber), the entire technology was abbreviated as HSPA.
HSPA +
HSPA + (English Evolved High-Speed \u200b\u200bPacket Access, "developed high-speed packet access") is a mobile communication standard, modernization of the third generation of mobile communication, with a high speed comparable to 4G.
It is customary to refer to HSPA + technologies that allow for packet data transfer with download speeds up to 42.2 Mbps and upload speeds up to 5.76 Mbps. In practice, the connection speed is lower and amounts to 10 - 20 Mbps (in the picture above 1.6 Mbps x 8 \u003d 12.8 Mbps).
This technology is considered to be a transition between third (3G) and fourth (4G) generation networks. Sometimes it is also called "3.5G".
4G
If you have an L, LTE or 4G icon on your phone, congratulations! Firstly, your device supports the LTE-A and WiMAX standard, and secondly, you are in the network of the newest and latest generation available in our country at the time of this writing with data download speeds up to 173 Mbps and upload speeds up to 58 Mbps!
This article will help you figure out what the Edge option means in the phone.
If you use the Internet through your phone, then you may be wondering: what does Edge mean on your phone? This option helps to increase the speed of information transmission in GSM networks. For you to use it, your mobile operator must support this option.
The high load of network lines, the level of data supply, the amount of free information in the network database - all this affects the operation of Edge. But using this option has its advantages over gprs:
- Highest speed of information transfer.
- The ability to go to global network from anywhere in your locality.
At present, such a seemingly modern, but already a little outdated option is gradually being ousted from the global mobile communications market. The evolution of cellular standards is moving forward. This is necessary for consumers who live in the rhythm of a big city. After all, Internet access is needed not only at home or at work, but also in the subway or in a minibus on the way home.
Users often ask the question: what does Edge mean in Samsung? In phone Samsung Galaxy The S7 edge prefix speaks of a curved screen. This version is much more popular than the previous model.
It's rare to see a user with Edge on a phone these days. This technology is being replaced by 3G and 4G networks. They have an even higher data transfer rate and a better signal.
Video: SPEEDTEST WIFI VS 2G / EDGE VS 3G VS 4G / LTE
The first launch of Microsoft Edge leaves a lasting impression. You have never seen such a quick start in any browser. It's clear that loaded with extensions, themes and plugins, Chrome and Firefox cannot show such agility, but it still looks very convincing.
The same can be said about the responsiveness of the interface. Opening new tabs and switching between them is just instant. But with the speed of opening pages, the situation is not so straightforward. As shown by numerous comparisons (,,), the surfing speed in the new browser is practically the same as in the competition. However, this can also be considered an achievement, isn't it?
2. Built-in reading mode and reading list
Microsoft Edge is great for all comfortable reading lovers. It provides a special view mode, when activated, the page is cleared of all unnecessary and only text and illustrations remain on it. The page background and font size used in reading mode can be selected in the program settings.
In addition, you can save the pages you are interested in in a special reading list, the panel of which appears on the right after clicking the corresponding button on the toolbar. It looks a bit like a Pocket Reading List and contains links to the pages you want with titles and covers.
3. Security
Yes, remembering Microsoft Explorer, this is hard to believe. But, according to the assurances of the developers, they drew conclusions from past mistakes and took all measures to protect their browser from hacking. The built-in SmartScreen security screen checks all sites you open and can block potentially dangerous ones. In addition, all pages are opened in separate processes, each of which is isolated from the rest of the system and is executed in the so-called sandbox. So even if something happens to the browser, operating system and your data will remain safe.
4. Convenient interface
I don't know about you, but I love the Microsoft Edge interface insanely. It has a minimalist design that fits perfectly into the overall look of Windows 10. The toolbar contains only the most essential buttons, and everything else is hidden in the panel that appears on the right. By the way, this panel can be fixed permanently, just like the sidebar works in Firefox, and more recently in Opera. Very handy, especially if developers eventually teach this panel to display not only bookmarks, downloads, and reading list, but other content as well.
5. Edit mode
And a big fly in the ointment
Despite all the listed advantages, new browser Windows 10 also has a big flaw. It lacks support for extensions. Yes, the available functions are interesting, the speed is good, the interface is nice, but this is not enough! Only full extension support can make Microsoft Edge a real competitor. However, Microsoft understands this and promises to present the first extensions for Edge to the world in the fall. So it won't be long to wait.
Would you dare to ditch your favorite browser and switch to Microsoft Edge if it comes with extensions?
