With time, generations change, whether it is mankind or technological. But the biggest and fastest changes have only been noticed in the communication network generations in the last few years. We have noticed a great electronic change in wireless communication network generations ranging from 1G to 2G, 3G and 4G in a very short span.
Traditionally, there are three ways the mobile industry can add more capacity to its network: by adding more spectrum, by improving spectrum efficiency or by rolling out more infrastructure. Each generation is characterised by new frequency bands, higher data rates and non-backward-compatible transmission technology.
Presently, wireless networking devices have occupied a significant place in society due to their easy access and expanding utility. Such devices are almost surpassing the human number on the Earth, and it is unimaginable to think about a place on Earth where these technologies have not reached. People now expect a lot more applications from mobile networks, and scientists and engineers along with industries are always working to make it happen.
1G refers to the first generation of wireless telephone technology (mobile telecommunications). These analogue telecommunications standards were introduced in the 1980s and continued until being replaced by 2G (second-generation wireless telephone technology) digital telecommunications.
The main difference between 1G and 2G is that the radio signals used by 1G networks are analogue, while 2G networks are digital. Although both use digital signalling to connect radio towers (which listen to handsets) to the rest of the telephone system, voice itself during a call is encoded to digital signals in 2G, whereas in 1G it is only modulated to higher frequency, typically 150MHz and up. The inherent advantages of digital technology over that of analogue meant that 2G networks eventually replaced these almost everywhere.
Second-generation, or 2G, mobile telecom networks were commercially launched in 1991. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally-encrypted, 2G systems were significantly more efficient on the spectrum, allowing far greater mobile phone penetration levels, and 2G introduced data services for mobile, starting with SMS text messages.
2G technologies enabled various mobile phone networks to provide services such as text, picture and multimedia messages (MMSes). All text messages sent over 2G are digitally encrypted, allowing for transfer of data in such a way that only the intended receiver can receive and read it.
2G has been superseded by newer technologies such as 2.5G, 2.75G, 3G and 4G; however, 2G networks are still used in many parts of the world.
3G, short for third generation, is the third generation of mobile telecommunications technology. The first 3G networks were introduced in 1998. This technology is based on a set of standards used for mobile devices, and mobile telecommunications use services and networks that comply with International Mobile Telecommunications-2000 (IMT-2000) standard specifications by International Telecommunication Union. 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV.
3G telecommunication networks support services that provide an information transfer at the rate of at least 200kbps. Later 3G releases, often denoted as 3.5G and 3.75G, provide mobile broadband access of several Mbps to smartphones and mobile modems in laptop computers. This ensures it can be applied to wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV technologies.
Fourth generation, or 4G, the next generation of mobile telecommunications technology, succeeding 3G and preceding 5G, was introduced in 2008. A 4G system, in addition to the usual voice and other services of 3G, provides mobile broadband Internet access, for example, to laptops with wireless modems, smartphones and other mobile devices.
Potential and current applications include amended mobile Web access, IP telephony, gaming services, high-definition mobile TV, video conferencing, 3D television and cloud computing. Two 4G candidate systems that have been commercially deployed are mobile WiMAX standard and the first-release Long Term Evolution (LTE) standard.
Expected 5G network visions
Rapid development of wireless technologies coupled with standards convergence herald the emergence of fifth-generation (5G) wireless communication. Broadly speaking, 5G is expected to provide much greater capacity to meet growing user demand resulting from a number of new services compared to 4G.
5G (fifth-generation mobile networks or fifth-generation wireless systems) denotes the next major phase of mobile telecommunications standards beyond the current 4G/IMT-Advanced standards. Experts feel that 5G should be rolled out by 2020 to meet business and consumer demands.
The major difference from a user point of view between 4G and 5G techniques must be something else than increased peak bit rate. It could be higher number of simultaneously-connected devices, higher system-spectral efficiency (data volume per area unit), lower battery consumption, lower outage probability (better coverage), high bit rates in larger portions of coverage area, lower latencies, higher number of supported devices, lower infrastructure deployment costs, higher versatility and scalability or higher reliability of communications.
In addition to simply providing faster speeds, experts predict that 5G networks will also need to meet the needs of new use-cases such as the Internet of Things (IoT) as well as broadcast-like services and lifeline communications in times of natural disasters. The Next Generation Mobile Networks Alliance defines the following requirements for 5G networks:
- Data rates of several tens of Mbps should be supported for tens of thousands of users
- 1Gbps to be offered simultaneously to tens of workers on the same office floor
- Several hundreds of thousands of simultaneous connections to be supported for massive sensor deployments
- Spectral efficiency should be significantly enhanced compared to 4G
- Coverage should be improved
- Signalling efficiency should be enhanced
- Latency should be significantly reduced compared to LTE
Expectations are that 5G will provide uniform throughput of at least 1Gbps, peaking at around 10Gbps, with a couple of milliseconds of latency, offering a highly-reliable service. 5G will provide a truly ubiquitous unlimited mobile experience through terminals enhanced with artificial intelligence (AI) capabilities.
New applications are foreseen that will facilitate domains such as e-health and machine-to-machine (M2M) communication. Its salient features would include:
- A super-efficient mobile network that delivers a better performing network at lower investment costs. It would address mobile network operators’ pressing need to see the unit cost of data transport falling at roughly the same rate as the volume of data demand is rising. It would be a leap forward in efficiency based on IET demand attentive network (DAN) philosophy.
- A super-fast mobile network comprising the next generation of small cells densely clustered together to give a contiguous coverage over at least urban areas and gets the world to the final frontier for true wide area mobility. It would require access to spectrum under 4GHz, perhaps via the world’s first global implementation of dynamic spectrum access.
- A converged fibre wireless network that uses, for the first time for wireless Internet access, millimetre wave bands (20GHz-60GHz) so as to allow very wide bandwidth radio channels that can support data access speeds of up to 10Gbps. The connection essentially comprises short wireless links on the end of the local fibre-optic cable. It would be more a nomadic service (like Wi-Fi) rather than a wide area mobile service.
5G mobile systems overview
The 5G technology for mobile systems is very much in the early development stages. Many companies are looking into technologies that could be used to become part of the system.
In addition to this, a number of universities have set up 5G research units focused on developing technologies for 5G. Many technologies to be used for 5G will start to appear in the systems used for 4G and then, as the new 5G mobile system starts to formulate in a more concrete manner, these will be incorporated into the new 5G mobile system.
As different generations of mobile telecommunications have evolved, each one has brought its own improvements. The same will be true of 5G technology. As with any new generation, 5G mobile technology would need to provide significant gains over previous systems to provide an adequate business case for mobile operators to invest in it.
Facilities that might be seen with 5G technology include far better levels of connectivity and coverage. The term World Wide Wireless Web, or WWWW, is being coined for this. For 5G technology to be able to achieve this, new methods of connecting will be required, as one of the main drawbacks with previous generations is lack of coverage, dropped calls and low performance at cell edges. 5G technology will need to address this.
Although the standards bodies have not yet defined the parameters needed to meet a 5G performance level yet, other organisations have set their own aims that may eventually influence final specifications.
These are some ideas being put forward for a 5G standard, but these are not accepted by any official body yet. The table below shows some suggested typical wireless parameters for a 5G standard.
There are many new concepts that are being investigated and developed for the new 5G mobile system. Some of these include:
This technology is being considered for 5G mobile systems, in which a user can concurrently be connected to several wireless access technologies and seamlessly move between these.
Group cooperative relay
This is a technique that is being considered to make high data rates available over a wider area of the cell. Currently, data rates fall towards the cell edge where interference levels are higher and signal levels are lower.
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.
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:
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.
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.
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.
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.
Despite never being able to successfully predict what each forthcoming generation of mobile technology would deliver in order to satisfy future users, the industry has, nonetheless, reached some consensus on the use cases for 5G. M2M communication is one. 5G should enable the IoT, the future where all our online-enabled objects will quietly pass on data to our tech overlord of choice.
Facilitating the use of mobile networks by connected or autonomous cars, remotely-controlled industrial robots, tele-health systems and smartcity infrastructure are also all expected to figure large in 5G.
Industries and researchers are actively preparing for the growing communication needs of society, involving a combination of existing and evolving systems. 5G will comprise the set of technical components and systems needed to support these requirements and overcome the limits of current systems.
5G network addresses the world of the IoT. This changes the dynamics of wireless systems completely. It takes these from today’s interference-limited environment, where interference from other mobiles radiates everywhere, like everyone yelling on the corner of a street, and now makes radio energy very focused like megaphones, with everyone talking with a megaphone to only whom they want.
We can imagine a world, possible by 2020, where almost anything that could be connected will be connected. Transition to 5G mobile communications is expected to include offloading traffic to unlicensed spectrum, improved carrier aggregation (up to 32 carriers), massive MIMO and support for a radio optimised for the low-end of the IoT market.
Before defining the road map to implement 5G networks, a lot of work has to be done ranging from testing the technology to defining performance requirements before commercial implementation.
Global 5G research is still taking place in isolation, but this will change. Various groups have different technology favourites, and standardisation discussions will start soon and technology selection will also begin in due course of time.
Dr S.S. Verma is a professor at Department of Physics, Sant Longowal Institute of Engineering and Technology, Sangrur, Punjab
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