Have you ever wondered what the little “E” next to your mobile phone network indicator meant? What it signifies? EDGE stands for ‘Enhanced Data Rates for GSM Evolution’. Even though higher communication standards are already being used, like 3G and 4G, EDGE is still one of the most popular data systems used in GSM networks today, especially in countries like India, where 4G is a long way off, and 3G is still not widespread.
The Evolution of mobile technologies – Pre-cellular Networks (0G)
But before we can understand about EDGE technology, it helps to know about its predecessor, namely the first generation of wireless telephone technology, commonly known as 1G. Introduced in the 1980’s, the first generation of wireless telephone technology was comparatively basic, and is quite different from the technology we use today.
The first generation of wireless telephone technology was comparatively simple. More than anything, it was an evolution of the mobile radio telephone, which is sometimes referred to as 0G. Even though it’s not commonly considered a part of wireless technology as we know it, it was definitely a precursor to the mobile phones we use today.
Pre cellular systems like these also had specific frequency bands and protocols for each country, and mostly used technologies like PTT (Push To Talk), Mobile Telephone System (MTS), Improved Mobile Telephone System (IMTS) and Advanced Mobile Telephone System (AMTS). Think of them as advanced walkie-talkies, because they were used mainly for point to point voice communication, in situations where the phone might not be actually stationary. They were available commercially as well, but weren’t as commonly used.
The Beginning of mobile telephony – 1G
1G was the beginning of the cellular generation. Introduced by NTT (Nippon Telegraph and Telecom) in 1979, the Japanese were the first to embrace cellular technology. NTT has always been an innovator in the field of mobile communications, and it is interesting to note that this Japanese giant is also a stakeholder in Tata DoCoMo. In fact, the ‘DoCoMo’ name comes from them.
As mentioned, 1G was pretty much an evolution of pre cellular networks. It still included only voice based communication, but was used for quite a long time. In 1981, the Nordic Mobile System (NMT) was launched in Sweden, Denmark, Finland and Norway, which had the distinction of being the first mobile network to have the international roaming feature. This was quite a big step forward, since pre cellular systems were area limited.
In the United States of America, Chicago based Ameritech introduced the first 1G network that ran on the iconic Motorola DynaTAC phone. This large and clunky looking device probably doesn’t look like much today, but has always been pretty much the default image for mobile phones in the 1980’s and early 1990’s.
1G used FDM (Frequency Division Multiplexing) to divide bandwidth into frequencies for calls, which has been continued even today. Data rates hovered around a 28k and 56k modem, but were completely used only for voice call.
The Digital Age – 2G
Mobile phones as we know it started becoming popular in the 1990’s. This new mobile technology was introduced by Radiolinja in Finland (now part of Elisa Oyj), in 1991. It ran on the now standard GSM standard. GSM stands for Global System for Mobile Communications, although it was first launched as Groupe Spécial Mobile. These protocols were developed by the European Telecommunications Standards Institute (ETSI), to succeed 1G mobile technology and bring some real big changes into the wireless communication game.
With the advance of integrated circuits in the 1990’s, it was only logical for mobile telephones and communications to go digital. To make it commercially viable, it was important that mobile telephony was secure, efficient and robust, so the switch to digital communication was made. This opened up a whole new world of possibilities, and had many advantages like:
- Digital encryption, which meant higher security and no interference
- Lower transmitting power
- Higher signal penetration
- Full duplex signals
- Multiple users on one channel
- Mobile data with voice
The introduction of full digital networks meant that mobile telephony suddenly meant much more than just voice calling, and the inclusion of data transfer opened up new avenues.
Multiple Access Techniques
Since 2G technology and GSM networks allowed multiple users on a single channel or frequency band, it was imperative to adopt multiple access techniques. There are mainly three techniques, which are used even today:
Frequency Division Multiple Access (FDMA) – As the name suggests, FDMA employed frequency division, which meant that users were assigned one frequency slot in a channel for voice and data usage. A whole different band was allotted to this type of multiple access technology to prevent clashes with other types.
Time Division Multiple Access (TDMA) – Time Division Multiple Access, or TDMA was another technique, which let users transmit data and voice over a single frequency, but assigned different time slots to each one.
Code Division Multiple Access (CDMA) – CDMA, used even today, but not as much as the other standards, stands for Code Division Multiple Access. This technique borrowed some principles from direct sequence spread spectrums, and used high bandwidth modulated waveforms called signature waveforms or codes. Basically, even though users could transmit data and voice over a single frequency, these modulated waveforms wouldn’t interfere with each other because of low cross correlation.
Faster Data and Better Networks – 2.5G (GPRS)
Although commonly referred to as 2.5G, it was not actually an industry standard like 2G or 3G. 2.5G and subsequent point revisions were simply used to denote addition of services and refinement of existing technologies. To make it easier, 2.5G can be referred to as the GPRS (General Packet Radio Service) generation.
GPRS was the introduction of packet switched domains, while 2G used only circuit switched domains. It was also the reason for the launch of WAP (Wireless Application Protocol). WAP is a technical standard for data transfer over a mobile network, and in simple words was a protocol that allowed mobile phones to browse the internet.
Again, this opened up a whole new world of possibilities, and put the power of the internet into people’s hands. When you think about that, it’s one of the biggest steps forward in communication as a whole. WAP also brought with it the ability the check emails, which was crucial in business environments, and Multimedia Messaging (MMS), which allowed users to transfer multimedia over the mobile network.
2.5G supported data rates from 56kbps to 115kbps, which is still quite decent for day to day usage, and partly the reason why it’s still part of many networks around the world. This evolution of 2nd generation mobile technologies was a huge step forward, which now brings us to EDGE networks.
Pre 3G Networks – 2.75G (EDGE)
Commonly confused for 2.5G, EDGE networks were the next step forward after the introduction of GPRS. While not a huge increase in terms of data rates, EDGE was nevertheless a big addition to mobile technologies. So big, in fact, that it is still in use today! Perhaps the first truly widespread and accessible network the world has ever seen, EDGE plays a huge part in today’s mobile telephony.
First deployed in 2003 on Cingular’s network in the United States, EDGE was simply an addon to 2.5G, and as such didn’t require too much change in terms of hardware and software. To facilitate higher data rates and more efficient transmission, EDGE made use of 8 bit Phase-shift keying (PSK). PSK is a digital modulation technique that depends on modulation of the phase of the carrier wave.
It also introduced several different efficiency measures like Incremental Redundancy and rate adaption algorithms, which allowed better and faster signal decoding, even of damaged data packets via redundancy information. Theoretically, it can provide data rates of upto 236 kbps for 4 timeslots, which effectively means that it can handle four times as much traffic as GPRS.
This increase in data transmission and efficiency as well as the fact that 2G networks were already established since years meant that EDGE networks pretty much became the standard default network around the world. Even now, pretty much 90% of mobile networks around the world use EDGE networks, even though 3G networks are up and running there.
Interestingly, it can be noted that the first true smartphones started out using the EDGE network, and Apple famously decided to stick with it even with the introduction of 3G in the first iPhone. Its popularity means that these networks have shaped a whole generation of smartphone and mobile device users, and pushed manufacturers to create devices with internet and multimedia capabilities to take advantage of accessible data. Mobile internet was no more only for the elite customers. In countries like India where mobile networks offer cost effective solutions for a price sensitive market, 3G still isn’t close to being a standard, and EDGE still reigns as king.
So that was our feature on EDGE networks and its predecessors, do let us know what you think via the comments below!