'4G' technologies do not officially exist - yet

Over the past 12 months, the mobile industry and media have built up a rather confusing amount of hype surrounding the availability of fourth generation network technology. Both Sprint Nextel and TeliaSonera have heavily hyped their so-called ‘4G’ services. The problem is that ‘4G’ does not officially exist, yet.

We have heard it all so far: 1G, 2G, 2.5G, 2.75G, 3G, 3.5G, 3.9G, 4G. The reality is that most of those terminologies are coming from marketing experts whose priorities are to ride the trend wave and promote their companies’ leading technological edge before offering it to consumers. However, so far, the ITU has acknowledged and defined 1G, 2G and 3G, and is currently working on defining the underlying technology behind 4G.

According to the ITU, the story is simple. Throughout their life cycles, wireless standards evolve rapidly and behind every generation of technology lies either an ‘evolution’ or a ‘revolution’ in technical capability. A revolution implies that an operator acquires additional spectrum, builds an overlay network and utilises multi-band mobile equipment. An evolution, in contrast, means that an operator makes one technology compatible with a newer one within its existing spectrum.

In the 1980s, cellular services were offered via analog networks (1G). In the 1990s, the definition of 2G was therefore easy since we were revolutionising the industry by moving from analog to digital. In 1992, the ITU started work on its global framework that would later be known as the International Mobile Telecommunications-2000 (IMT-2000) standard and would facilitate future developments via ‘evolutionary’ or ‘revolutionary’ routes. In the late 2000s, spectrum was auctioned and media coverage focused on those ‘revolutionary’ operators, even though the vast majority of 3G users were connected to ‘evolutionary’ IMT-2000 technology.

There are two typical IMT-2000 ‘evolutionary’ 3G standards – 2G CDMA: from IS-95 (cdmaOne) to IMT-MC (CDMA2000); 2G TDMA: from IS-136 (GSM) to IMT-SC (EDGE). In contrast, IMT-2000 ‘revolutionary’ 3G standards include the deployments of IMT-DS (WCDMA) and IMT-TC (TD-SCDMA and UTRA TDD) networks. In the same way, HSPA and CDMA2000 1X EV-DO networks are evolutions of WCDMA and CDMA2000 1X.

Hence, there is a general consensus on what constitutes 1G and 2G networks, but there is more confusion as to how to define a 3G network. To separate 2G from 3G, the ITU has taken into account data speeds and defined performance levels significantly higher than 2G networks. To qualify as 4G, networks will therefore have to match new data speed requirements as well as other key criteria such as additional spectrum and multi-band equipment.

The ITU has defined IMT-Advanced as a 4G standard and is currently assessing which technology should be standardised. One of IMT-Advanced’s key features is to reach peak data rates of 100 Mbps for mobile and 1 Gbps for fixed services along with the release of additional spectrum. Consequently, the ITU argues that a number of so-called 4G networks today are simply evolutions of 3G networks. For instance, Long Term Evolution (LTE) has been designed by 3GPP (Release 8) and is based on IMT-2000 recommendations, not IMT-Advanced – by strict definition, LTE should not be referred to as 4G.

As a matter of fact, one of the drivers behind today’s popular use of ‘4G’ has been the aggressive marketing push behind IEEE 802.16e (WiMAX). However, the 4G version of WiMAX is expected to be coded 802.16m and the 4G version of LTE (Release 8) is likely to be LTE-Advanced (Release 10).

Hence, IMT-Advanced (4G) is currently work in progress. 3GPP has submitted its LTE-Advanced Release 10 to the ITU to evaluate it as a possible candidate for the official IMT-Advanced standard. Release 10 specifications are expected to be approved by the end of this year. Until then, there are no official ‘4G’ networks available in the market.