The journey to Gigabit LTE
As we stand on the cusp of mainstream Gigabit speed mobile networks, it’s staggering to think that there was no mobile Internet just twenty years ago. Back then the idea of even business connections reaching speeds of over 100Mbits/sec would have seemed a pipe dream, yet here we are with a technology that could give us speeds of over 800Mbits/sec on a mobile device. How did we come this far, this fast?
To answer, we need to go back into the history of cellular communications, and look at the revolutionary technologies that have paved the road to Gigabit LTE. Along the way, we’ll see how networks, hardware and software have evolved to transform the way we live and work today.
The early years
The first mobile networks were restricted to a single area or city and based on simple analogue radio technology, the transceivers themselves so large that they were more likely to be mounted in a car than handheld. These early carphones weren’t even full duplex; only one person could talk at a time, holding a button in order to speak.
Primitive is putting it mildly. Early networks like the UK General Post Office’s 1959 Manchester-based service could only handle one call per channel at a time, so if six people were making or taking calls, a seventh would have to wait until one of them finished. Steadily, though, these analogue systems developed, and were able to handle more calls, provision channels automatically and support full duplex calling. All the same, a network that could handle hundreds, let alone millions of users, seemed utterly impractical.
That changed with the introduction of cellular networks, first in Japan in 1979, then in the Nordic territories two years later. Cellular networks took advantage of nascent computer technology to divide the area covered by a network into cells, each one served by one to three fixed transmitters. This had the advantage that the same frequency could be used by multiple calls provided those calls took place in different cells. To allow for movement, the system reserved the channel in that cell and in adjacent cells, which also ensured that there was no interference between different calls in adjacent cells.
These early cellular networks enabled the growth of carphones and mobile phones, but not enough to make them a mass-market proposition. What’s more, you had different analogue systems operating across different territories and often within the same territory. What was needed was a way to cope with more calls from a larger userbase and a standard to enable cross-compatibility. Both came with GSM.
The birth of a standard
In 1982 the European Conference of Post and Telecommunications Administrations set up a working group – the Groupe Speciale Mobile – to define a new pan-European mobile network standard. The result, known as GSM, used the available radio bands as a vehicle for digital transmissions, incorporating time-division multiplexing (TDM) and compression to fit up to 16 different calls into a single radio frequency. What’s more, GSM added authentication and encryption to prevent other users snooping on your calls; one of the big concerns with the old analogue technology.
GSM rolled out in Finland in 1991, with the UK’s first services, Mercury One2One, Vodafone and Orange, launching less than two years later. GSM had its teething troubles – signal break-up and poor coverage – but the move to digital had another effect; a network that carried voice traffic could also carry other types of data. In 1995 the first mobile fax, data and SMS messaging services appeared. Four years later, the first phones compliant with the Wireless Application Protocol (WAP) standard arrived, enabling simple, text-based Web browsing on a mobile device.
From WAP to the mobile Web
With WAP, you could check the headlines, stock prices and sports results or read your email, or use a few other basic services. While interesting, however, the experience wasn’t close to going online with a fixed modem on a desktop or laptop PC. GSM speeds maxed out at a mere 9.6Kbits/sec, while the numeric keypads and low-resolution, monochrome displays of mainstream mobiles weren’t really up to handling anything more advanced.
The speed issue was taken care of quickly. 2000 saw the arrival of the first GPRS (General Packet Radio Service) networks, transferring data in more efficient packets to boost speeds up to between 35 and 171Kbits/sec. This was followed in 2003 by EDGE (Enhanced Data Rates for GSM Evolution); a fairly quick and easy upgrade to GPRS that boosted transfer speeds up to between 120 and 384Kbits/sec. GPRS and EDGE allowed networks to carry more sophisticated, even graphics-rich content and the handsets evolved to match, with colour screens, built-in cameras, MMS messaging and Web browsers that, while basic, were actually useful.
From EDGE to real 3G
Even with EDGE, however, you couldn’t get the full power of the Web. By the early 2000s the online world was changing, fuelled by the growth of ADSL and cable broadband networks to the home. Users wanted a richer browsing experience; the ability to upload and download high-resolution photos, play online games and download music – even video.
Luckily, the industry was one step ahead. The 3rd Generation Partnership Project (3GPP) – an association of global telecoms associations – was preparing for a new third generation of mobile networks, with higher data rates right at their core. With the help of mobile phone manufacturers, processor manufacturers and network providers, it defined a new standard based on Universal Mobile Telecommunications System (UMTS). UMTS used newly available frequency bands and High Speed Packet Access (HSPA) technology to accelerate speeds up to 14.4Mbits/sec for downloads and 5.76Mbits/sec for uploads. With an upgrade to HSPA+ in 2010 to 2012, those maximum speeds increased to 42Mbits/sec and 22Mbits/sec respectively (though typical real-world connection speeds are significantly lower).
In 2003, the arrival of the first 3G smartphones was met with a collective shrug. By 2007, however, the technology had matured and network coverage increased and the networks were ready for a new breed of smartphone, including Android devices from the likes of Samsung and HTC. These devices were built to provide a full-scale Web experience on the go, with data-rich apps and streaming services that empowered communications, entertainment and commerce on the go. That’s exactly what 3G networks could deliver.
3G was fast, but users wanted faster. The arrival of music streaming services, video streaming services and cloud-based apps and storage soon created pressure for an even speedier network. For some, the halfway house of HSPA+ was enough, but a true 4G technology needed to redefine mobile networks for a new era.
4G and the Future
Here, there was more than one contender. In the US, Intel, Nokia, Google, Sprint and Comcast, amongst others, pushed WiMAX: a wireless broadband standard designed to enable high-speed multimedia-ready connectivity across a range of 30 miles, targeting not just smartphones but tablets and laptop computers. However, the 3GPP – a group of telecoms associations from around the globe – proposed an evolution of the existing GSM/UMTS technology, known as Long Term Evolution (LTE).
Using new signal processing techniques and modulations, LTE was designed to provide more bandwidth and reduce latency over newly available frequency bands, taking download speeds up to a maximum of 100Mbits/sec with Quality of Service (QoS) features to prioritise traffic. For a number of reasons, LTE eclipsed WiMax and has become the principal standard for 4G mobile networks. In practice, typical real-world speeds are closer to the 20Mbits/sec mark, though these have been improved with a successor standard, LTE Advanced, which accelerates real-world download speeds to over 40Mbits/sec. All the same, there’s overlap there with low-end fibre Broadband speeds, and enough bandwidth for HD video streaming or cloud computing.
That’s fast, but the future looks even faster. The world’s leading mobile networks are already rolling out Gigabit LTE technology across their infrastructures, ready for devices based on the Qualcomm® Snapdragon™ 835 Mobile Platform which integrates the Snapdragon Gigabit LTE modem. Together, this will allow smartphones to connect at peak speeds of 1Gbits/sec, and if real-world speeds won’t always match that, they’ll certainly get closer. That’s not just fast enough to feed a new generation of mobile devices and applications, but fast enough for Gigabit LTE to replace home broadband connections, too. In twenty years, we’ve seen mobile networks increase in speed from 9.6Kbits/sec to over 1,000,000Kbits/sec – and we’re only getting started. Ultra-fast, seamless, wire-free networking is just around the corner, with Qualcomm providing the technology to connect.