A Brief Overview of the Evolution of 4G - Glossary of Competence
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Before we begin, as I mentioned earlier, we need to clarify and define some tech terms so that all of our readers can be on the same page. Actually, regardless of our current experience in the field of mobile communication systems, after reading this article, you should feel competent enough to hold a conversation with professionals.
First of all, let's begin with those Gs: 0G, 1G, 2G, 3G, pre-4G, and 4G. Basically, these stand for generations and the higher the number, the more evolved the specific technology. The first one is only used for historical reference because it represents the zeroth generation. The second one, 1G (the first generation), is the era of analog digital phones.
We should only "care" about the generations starting from 2G - the second generation. It represents wireless telephone technology, which was the first generation based on digital signals. 1G was analog, 2G is digital. We can divide 2G into two subcategories as per standards: TDMA- and CDMA-based. The first stands for the ubiquitously popular GSM cellular network standard, while the second holds the standard of cdmaOne, which is mostly used in the Americas and Asia.
Let's mention some of the basic advantages and drawbacks of second generation systems. Surely, the most outstanding benefit of 2G can be summarized in one word: "digital." This is important because digital data services (SMS, e-mail, etc.) and error checking can be included as well as the use of codecs, which improves the clarity of voice, but loses shades of tonality. Less power consumption, lower power emissions, and the like are also pros. As for drawbacks, it's pretty much the dependence on cell towers (weak or no signal at all in certain areas) and air conditions; signal dropouts are also an issue.
The next main generation in cellular communication systems is the so-called 3G. Although some consider 2.5G to be a stepping-stone, it contains nothing more than a new technology (GPRS) that wasn't present in the original 2G. It seems "3G-like" but its speed is slower than 3G's requirements and, therefore, it does not qualify for 3G.
UMTS (Universal Mobile Telecommunications System) is one of the strongest standards in the third generation. It is sometimes marketed as 3GSM to hint at the fact that it's the GSM standard implemented in the 3G technology. Thus, it's a sort of "success formula." UMTS, in general, uses the W-CDMA air interface.
What does this new generation offer? In a nutshell, higher connection speeds. In theory UMTS with W-CDMA can go up to 14.0mbps. The most common speeds are around 384kbps (R99 phones) and 3.6mbps (HSDPA phones), but this depends on dozens of other factors. HSDPA stands for a newer generation of handsets that support faster downlink transfer rates and capacities based on UMTS.
Another interesting feature that 3G brings is the ability to establish video calls. Consequently, this allows videoconferencing. Once there's video support, the ability to download videos and clips is also open. Ultimately, we saw the advent of 3.5G, yet another transition stage. This combines the technologies of HSDPA and HSUPA to provide really high downlink and uplink speeds, such as 7.2mbps.
It's also worthwhile to mention CDMA2000; it is a hybrid 2.5G/3G technology. It's based on the traditional CDMA. One of its most important standards is the EV-DO. In order to improve the overall efficiency of this system, it also uses some parts of TDMA along with CDMA.
Fortunately, UMTS is backwards compatible with earlier GSM networks on an air interface level. Thus, this stands for a higher rate of interoperability and allows for global roaming. Traveling in non-UMTS areas automatically transitions (even during a call) the phone system to the GSM standard, so this never caused any significant issues.
As you would have already guessed, after 3G and 3.5G dominated the market for a few years, it's time for a fourth generation. That's what all of that 4G-hype is about. Right now we have nothing but pre-4G systems along with lots of expectations regarding the real 4G. That will be covered in the next section.
Next: Pre-4G: WiMAX and LTE >>
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