Driven by New Technology:
Even though we have only recently seen a full-scale rollout of 4G in the UK, there are a number of technologies that demand (or will soon demand) functionality that existing and planned 4G infrastructures will be unable to meet. To my mind, it is these technologies that will shape the development of the network of the future. Whilst not describing a particular technology, and as yet not comprising any particular standards, 5G is something of a moving target. It is, however, likely to be defined by the demands of future technologies set against the limitations of current wireless infrastructure.
For most of us the 4G networks meet our current needs in terms of high speed and low latency, which seem to be the current focus of the consumer market. However, new applications are being developed all the time, and these are expected to dictate the requirements of any new network specification. A likely key driver could be the growth of the 'Internet of Things', which envisages a wide variety and massive number of wireless-enabled devices communicating with us and each other. Bandwidth-hungry applications such as ultra-high-definition (UHD) video and virtual reality are set to rise, and the ability to transition these high data-rate/low-latency data streams seamlessly between transmitters as users move will be key to positive user experiences.
To meet the demands of new applications and technologies, the network of the future will need to provide for incredible speeds and low latency across a wide geographical area. It will need to ensure great service in crowds by providing large bandwidth in regions of high-demand, as well as ensuring that the best experience follows the user as they move. Reliable, always-on, real-time connections are anticipated to be central to the success of 5G.
The new network will need to be smart, in that it must dynamically alter its behaviour to deliver a level of service suitable to each individual user's requirements. For example, an embedded sensor periodically reporting on the status of critical infrastructure will need access to a reliable, robust and resilient network, but perhaps only with very low bandwidth requirements. On the other hand, a UHD video service will require high bitrates and low latency, but not necessarily all the time. Such 'context-aware' networking will be essential to enable the efficient servicing of the huge number of networked devices expected to be introduced over the coming years. 5G networks will need significant capacity, flexibility, and energy and cost efficiency improvements over existing 4G networks to cope with increasingly data-hungry devices.
Building the Network:
There are technical hurdles that will need to be addressed before devices and networks can meet a 5G standard, and there are a number of approaches that could help resolve them, together with the conversion or adaptation of existing wireless networks such as GSM, HSPA, LTE, and Wi-Fi. One possible technical solution to bandwidth challenges might be 'Massive MIMO' (Multiple Input Multiple Output), which would use hundreds of antennas at transmitters and receivers to achieve more efficient spectrum use. However, advances in radio and antenna technology will be required before large numbers of antennas can be cost-effectively deployed.
Predicted bottlenecks in capacity (number of users) and bandwidth (data volume per user) could be addressed by using other parts of the electromagnetic spectrum for broadcast. Today, mobile networks predominantly use spectrum in the sub-3GHz band. In the future, 5G could use spectrum in the 10-30 GHz and 30-300 GHz where there are large chunks of continuous spectrum available for use. Whilst these high frequencies are attenuated to a greater extent as they travel through air and obstacles (and therefore have a shorter range), they may be more suitable for urban environments with a high density of wireless devices where range is not an issue. Higher frequency transmissions may also be used to complement lower frequencies when in sufficient proximity to other networks, with lower frequencies being used to provide the core service. For further information on the current thinking at EU level on spectrum planning for 5G see here.
In modern wireless networks upload and download channels tend to be given different spectrum allocations so that there is no interference between the channels. If the same allocation of spectrum could be used for both upload and download, then spectrum capacity could theoretically be doubled. Self-interference remains a big hurdle to overcome before this technology can be implemented however, although both analogue and digital techniques have been used to reduce interference. The potential gains if these techniques were to be further developed are certainly of interest, and this interest might drive more funds into the development of this technology.
Whilst 5G is very much a network of the future, it is already receiving attention from both political institutions (such as the European Commission) and industry. On that basis alone, it is definitely one to watch over the coming years.