I’ve often been asked about 5G and the key differentiation from previous generations. In this piece, I explain more about the technical requirements for 5G, from the spectrum, infrastructure to the core. I hereby apologize in advance for the technical details but this is necessary to explain 5G to those who may wish to know more about the recent developments within this field. As standards are being formulated and research is ongoing within this area, please note that there may have been changes in some of the technologies discussed in this piece. And this is only a short guide.
Every ten years, there is always a shift from previous generation onto a newer generation. In 1991, the development of GSM made voice calls to become reliable and cheaper and encouraged the widespread adoption of SMS and MMS. 1n 2001, 3G ushered in an era of data services and allowed workers access to emails from any location and this increased work productivity. 1n 2010, 4G led to the development of mobile internet and video based applications which triggered the development of many sectors like online shopping, e-banking etc. 2020 is not going to be different as it promises an era of high-speed connectivity, ubiquitous coverage and low latency, all thanks to 5G.
WHAT IS 5G?
What exactly is 5G? It’s a newer generation which presents different opportunities to different stakeholders depending on where your interests lie. To an equipment vendor like Ericsson, 5G represents a market opportunity to drum up the sales of infrastructures like small cells etc. To an academic, 5G would provide an opportunity to solve complex research problems and open up the potential for successful grant applications. To a car manufacturer, 5G simply represents the opportunity to make revenues from new offerings like connected cars. To a regulator, 5G would lead to the opportunity to make increased profits from new spectrum release and lots of debate on band issues etc. To telcos, it may represent a way to increase revenue, consider new offerings (verticals) and address the increased competition from over the top (OTTs) applications like WhatsApp etc. For the technology media, it’s an opportunity to increase subscription audience and perhaps pitch the development and deployment of 5G as a race between countries or operators.
ITU has classified 5G in terms of the three use-cases presented below:
- Enhanced Mobile Broadband: simply an extension of 4G and promises a speed of 10/20Gbps for either your uplink/downlink. In literal terms, as a user, you should be able to download a HD film in seconds.
- Ultra-Reliable and Low latency: Here, a stringent requirement of less than a milli-sec of delay is anticipated for applications like autonomous driving and remote surgery e.g. imagine a robot performing a surgery operation during an emergency, a delay could have damning consequence.
- Machine to Machine type Communications: allow for IoT based applications, 106 devices per km2g. smart metering, smart city, smart agriculture etc.
In order to transit from 4G to 5G, a combination of technological solutions e.g. network densification, spectral aggregation etc. have been proposed to maximize the capacity and spectrum usage respectively.
Here I explain more on the recent developments within the industry geared at providing more spectrum and increasing the efficiency of the existing spectrum for 5G applications. I also discuss the challenges associated with providing new spectrum for 5G.
The digital switchover has been able to free up spectrum; the 700MHz Band is in fact being cleared of incumbent to provide some bandwidth for 5G. Besides 700MHz, some other bands will be refarmed for 5G.
Furthermore, unlicensed spectrum (2.4GHz etc.) can support offloading from licensed bands. This is important because 5G would involve a combination of different technologies like LTE/WiFI etc. But the issue is Quality of Service cannot be guaranteed when using unlicensed spectrum. So it needs to be well planned and carefully integrated with licensed bands.
Now, the higher frequencies (30-300GHz), termed mm wave, are able to provide a large amount of bandwidth for 5G. The higher the frequency, the more data that can be transmitted. These frequencies were traditionally being used for satellites and radar applications. However, the use of these frequencies for 5G present challenges such as losses, shorter transmission range, signal blocking/absorption by objects etc. as a result of their different propagation characteristics.
Besides, at higher frequencies, the antennas become very small because of the small wavelength dimensions (from the name mm-wave) and the signals propagate very short distances, which is an issue for signal reception. Hence to maximize the signal reception, a large number of small antennas are combined within the transmitter and receiver to provide for spatial and multiplexing gain (hence the use of Massive MIMO technique which simply implies that the number of antennas is far greater than the number of data stream and requires hundreds/thousands of antennas).
To combat the propagation challenges I mentioned earlier, one method is to situate base stations closer to the users (which reduces the loss) or use techniques such as adaptive beam-forming to target the radiation towards or away from the user which also helps to mitigate interference. The downside however with citing base stations closer to the public is that it increases the public’s concern and worry of the effect of electromagnetic radiation on their health.
Now, the use of different frequency bands also mean that you need to be able to combine the carriers in different bands in a clever manner using a technique like carrier aggregation.
Previously, spectrum assignment was static and regulators simply monitor the spectrum to ensure that its’ being utilized for the right purpose. Research has shown this is inefficient and there are better ways to maximize the scarce spectrum resource. For example, the use of dynamic spectrum allocation (e.g. Nominet Dynamic Spectrum Management) allows for the allocation of spectrum in real-time using a database which checks for the usage, location of user and the demand.
The summary here is that the spectrum needed for 5G would be realized in different bands; hence spectrum harmonization will be key here in providing the needed spectrum for 5G applications.
Here, I discuss the technological solutions within the radio interface to maximize the capacity.
Network Densification has been proposed to improve the spectral efficiency. It simply involves the deployment of low power nodes (pico cells, femto cells, Distributed Antennas etc.) within localized regions of high traffic demands. It’s anticipated that most traffic would originate from indoor areas, hotspots, public areas like stadium, malls etc., hence it makes sense to deploy an overlay of small cells within the macro coverage area.
The goal is to offload some of the traffic from the base stations (macro cells) to the small cells which therefore improves the frequency reuse. Of course, this requires careful network planning to balance the load and address interference challenges.
The small cells could be deployed with self – organizing network capabilities which allows the cells to sense their environment, switch off when in idle mode (reduces energy consumption), coordinate with other base stations to deal with interference challenges within the environment.
As small cells require less power and cooling and can be deployed closer to the user and within existing networks; the deployment of small cells would therefore reduce the CAPEX and OPEX incurred by operators.
Now, since the traffic bottle neck varies from network to network, offloading strategy could be between networks of the same air interface technologies (Macro/small cells) or between networks of different air interface technologies (LTE/Wi-Fi) or between mobile operator core network and public internet. These combination of technological solutions involving the use of network of different technologies or network of multiple layers of different sizes is referred to as a Heterogeneous Network (HetNet) and has been proposed for use in 5G network. Interoperability is vital here to allow these technological solutions work together.
The deployment of a HetNet to increase capacity has to be complemented with a backhaul for this to translate into an enhanced user experience. A proposed technique for backhaul in 5G involves the use of the cloud Radio Access Network (cloud RAN) architecture with Coordinated Multipoint processing (CoMP). In a cloud RAN, the signal processing from the base stations is centralized within a pool and can be visualized whilst CoMP simply involves the dynamic cooperation and coordination between multiple geographically separated base stations to improve spectral efficiency, address interference and reduce energy consumption. Wireless backhaul is also an alternative for use in 5G.
As seen so far, the three use cases of 5G have different stringent requirements e.g. latency, bandwidth etc. It therefore becomes a challenge to support all these services within the same physical infrastructure. Another challenge for the network is that it has to be able to react to the demand of the users regardless of the geographic locations.
To address these challenges, end to end Network Slicing, has been introduced. In 5G, the network will be sliced into multiple virtual networks to support different radio access technologies or services with different requirements. As network slices are logical arrangements, which can separated into individual entities, the slices can therefore be customized depending on the requirements of the applications. For example, an autonomous system may require low latency whereas a user downloading a video requires bandwidth. These services will be delivered on different virtual network slices and transported within the same physical infrastructure.
Now, in order to facilitate the smooth transport of the various virtual slices within the network as well as control slices on the fly (depending on application requirements), Network Function Virtualization (NFV) has been introduced. In simple terms, it means the virtualization of network functions like routers, firewalls, evolved packed core etc. and simply represents a shift from hardware to software within the network. NFV would enable the network to become programmable, agile and dynamic and reduces the costs associated with purchasing hardware for network entities. In essence, it would allow the network to be able to react to the demand of the users, a key necessity for 5G services.
The deployment of NFV within a traditional cellular network would make control and management very difficult; hence, the introduction of Software Defined Networking (SDN), an intelligent network architecture, for use within the 5G network. This simply replaces traditional hardware with programmable software services and separates the control plane from the data plane. It allows for a simplified network management and introduces flexibility within the network. SDN allows for the dynamic reconfiguration of the network and thereby give users the perception of infinite capacity for their applications.
The softwarisation of the network has enabled the introduction of newer technologies like Mobile Edge Computing (MEC) within the network. This simply means bringing the cloud/IT services closer to the edge of the network or the users. This reduces latency, improves the quality of experience, allow for contextualized services and efficient use of resources.
In summary, the core will be developed based on a ‘Service based architecture’ due to softwarisation and virtualization. This would allow logical entities within the virtual network to communicate via protocols. The virtualization and softwarisation of the core would also allow for tools like Artificial Intelligence (AI), Machine Learning (ML) and Data Analytics to be used for other capabilities within the network.
OTHER TECHNOLOGIES AND DEVELOPMENT
Other Technologies: There are of course other technologies e.g. Satellites which may have not been mentioned previously but have a key role to play in the deployment of 5G. For example, Satellites could be used for backhaul, offload traffic from base stations, deliver broadband services in underserved areas or emergency regions and for can be used in safety services. The integration of terrestrial and satellites domains within the 5G network is all due to Virtualization.
Waveforms and Access technologies; New waveforms and Access technologies e.g. Non-Orthogonal Multiple Access (NOMA), Sparse Code Multiple Access (SCMA), Quadrature Amplitude Modulation Filter-Band Multi-Carrier (QAM-FBMC) etc. are being researched for use in 5G.
Security and Privacy: The virtualization of the network raises complex issues for critical services and security. The heterogeneous nature of the 5G network mean that each layer of the network could be owned and operated by different operators, therefore privacy concerns become an issue. Interoperability is key for the deployment of 5G and raises important questions on ethics, security and privacy concerns.
Green Initiatives: It is anticipated that Green Communication technologies would be implemented within the 5G network to reduce energy consumption and improve energy efficiency.
5G represents a shift from consumer technologies to industrial technologies as it promises to lead to the development of a highly automated and intelligent environment which would revolutionalise many industries, including automotive, transportation, supply chain, manufacturing, energy and utility services, retail, agriculture, health, education, etc. For this to happen, 5G networks must be able to provide diversified services, support accesses of multiple standards and coordinates multi-connectivity technologies. This has resulted in the virtualization and softwarization of the network to facilitate interoperability and encourage a seamless operation among different technologies. The core is the heart of the 5G network, developed using a service based architecture, which has therefore triggered the development of new business models e.g. Network as a Service and market opportunities which would no doubt justify the investment in 5G. There are however risks and issues that need to be addressed e.g. Spectrum harmonization, Interoperability, security and privacy.