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Cognitive radio technology. If cognitive radio technology was used for 5G mobile systems, it would enable the user equipment/handset to look at the radio landscape in which it is located and choose the optimum radio access network, modulation scheme and other parameters to configure itself to gain the best connection and optimum performance.

Wireless mesh networking and dynamic ad-hoc networking. With a variety of different access schemes, it will be possible to link to others nearby to provide ad-hoc wireless networks for much speedier data flows.

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Smart antennae. Another major element of any 5G mobile system will be that of smart antennae. Using these, it will be possible to alter the beam direction to enable more direct communication, limit interference and increase overall cell capacity.

Scepticism about 5G networks
Every new mobile standard brings with it calls from operators for more spectrum, and 5G is no exception. If mobile operators want to deliver more and more capacity, they will need more and more wireless spectrum to do so. And, with every generation of mobile tech, governments around the world must identify what spectrum those operators will need, whether anyone is using those bands and how to move them off those, if so. And then find the best way to sell that spectrum at the right price and finally make sure that all operators are meeting the obligations that buying the spectrum imposed on them.

The history of the wireless industry is littered with tales of fouled-up spectrum auction procedures, delays to network rollouts, mud-slinging between mobile companies, obligations not met and clean up procedures not followed. Spectrum is and will remain a major challenge for the success and early rollout of 5G. There is not enough spectrum in general and 5G is a lot about optimising the use of spectrum.

New mobile generations are typically assigned new frequency bands and wider spectral bandwidth per frequency channel (1G up to 30kHz, 2G up to 200kHz, 3G up to 20MHz and 4G up to 100MHz), but skeptics argue that there is little room for larger channel bandwidths and new frequency bands suitable for land-mobile radio.

From users’ point of view, previous mobile generations have implied substantial increase in peak bit rate (that is, physical layer net bit rates for short-distance communication), up to 1Gbps, to be offered by 4G. If 5G appears, it reflects these prognoses.

The major issue with 5G technology is that there is such an enormously wide variation in requirements—superfast downloads to small data requirements for the IoT—that any one system will not be able to meet these needs. Accordingly, a layer approach is likely to be adopted. It is rightly said that 5G is not just a mobile technology but an ubiquitous access to high and low data rate services.

Challenges associated with next-generation network
There are many new techniques and technologies that will be used in the new 5G mobile telecommunications system. These new 5G technologies are still being developed and overall standards have not yet been defined. However, as required technologies develop, these will be incorporated into the new system, which will be defined by the standards bodies over the coming years.

There are several key areas that are being investigated by research organisations. These include:
Millimetre-wave technologies. Using frequencies much higher in the frequency spectrum opens up more spectrums and also provides the possibility of having much wide-channel bandwidth of possibly 1GHz-2GHz. However, this poses new challenges for handset development where maximum frequencies of around 2GHz and bandwidths of 10MHz-20MHz are currently in use.

For 5G, frequencies of above 50GHz are being considered. This will present some real challenges in terms of circuit design, technology and also the way the system is used, as these frequencies do not travel as far and are absorbed almost completely by obstacles.

Future PHY/MAC. This area presents many possibilities, from the use of new modulation formats including generalised frequency division multiplexing (GFDM) as well as filter bank multi-carrier (FBMC), universal filtered multi-carrier (UFMC) and other schemes to the management of multiple access schemes.

All these need to be developed. Higher levels of processing that will be available by the time 5G is launched means that multi-carrier systems will not require to be orthogonal as in the case of OFDM. This provides considerably more flexibility.

Massive MIMO. Although multiple-input multiple-output (MIMO) technology is being used in many applications from LTE to Wi-Fi, the number of antennae is fairly limited. Using microwave frequencies opens up the possibility of using many tens of antennae on a single equipment because of antenna size and spacing in terms of wavelength.

Dense networks. Reducing the size of cells provides a much more overall effective use of the available spectrum. Techniques to ensure that small cells in the macro-network deployed as femto cells can operate satisfactorily are required.

Requirements of 5G network
From a network perspective, 5G requires tight and seamless interworking among existing and future standards. Rising demand for mobile traffic will enforce new ways of enhancing capacity, such as dense deployment of small cells, as well as intelligent traffic steering and offload schemes.

Ever-growing energy consumption in wireless networks imposes new mechanisms of energy control and reduction. Finally, there is a need for autonomous network management because of network complexity and heterogeneity.

Devices are becoming more powerful and more numerous. Beyond devices like smartphones, tablets or game consoles, the future wireless landscape will have to serve cars, smart grid terminals, health-monitoring devices, household appliances and so on. It is estimated that M2M traffic will increase 24-fold between 2012 and 2017.

Taking e-health as an example, remote patient monitoring using a body area network, where a number of wireless sensors, both on-skin and implanted, record the patient’s health parameters and send reports to a doctor, will soon become a reality. Therefore in order to offer e-health services, 5G will need to provide high bandwidth, meet stringent requirements for quality of service (such as ultra-low latency and loss-less video compression) and implement enhanced security mechanisms.

Work will be needed to manage radio resources efficiently, because of the diversity of traffic types, ranging from reports sent periodically by the meters to high-quality medical video transmission.

With new broadband services and high demand for mobile data, future wireless systems will require much higher capacity than can be provided today. There are three main ways of enhancing capacity, namely, dense deployment, additional spectrum bands and higher spectral efficiency.

Moving towards 5G will impose changes not only in the radio access network but also in the core network, where new approaches to network design are needed to provide connectivity to a growing number of users and devices. The trend is to de-couple hardware from software and move network functions towards software.

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