COMMUNICATIONS AND NETWORKING

The ability to communicate – typically wirelessly – is a fundamental function of IoT devices. Southampton has been at the forefront of wireless communications, signal processing and service management research for more than three decades, feeding into the standards and protocols for each generation of mobile technology.

With 5G (and eventually 6G) opening up more capacity for massive machine-type communications, the Centre’s researchers are developing techniques for more efficient transmission to enable the mobile network to accommodate the ever-growing number of IoT devices. They are also looking at how best to optimise communication within networks of low-power or intermittently powered IoT devices.

As with other aspects of IoT technology, the challenges around communication and networking vary depending on the application. For some IoT systems – for example those used in smart vehicles – high-speed communication is essential and the transmission of large volumes of data, such as streamed video, might be necessary. Other devices, such as environmental sensors, might only need to transmit a small amount of data each day, but may only have a very small power resource with which to do it. Much of our research focuses on this tension between the amount of energy a device is available for communication, the quantity of data it needs to transmit, and how far and how fast the data needs to go.

“One challenge is how to make efficient use of the spectrum resources, because the spectrum allocated for supporting this type of wireless communication is very limited. Supposing we have a billion IoT devices, all of them wireless, on a bandwidth of 10MHz – how do we use that 10MHz of bandwidth to support the devices? That’s the challenge we’re working on.”

Professor Lie-Liang Yang Professor in Next Generation Wireless

Optimising wireless communications for the IoT

We have research streams looking at how the technologies within 5G and beyond can best support the IoT’s growing communication and networking needs. For example, we’re part of a joint project with the University of Surrey and industry partners on New Air Interface Techniques for Future Massive Machine-Type Communications. This project, which funded by the Engineering and Physical Sciences Research Council (EPSRC), is developing new techniques supporting efficient wireless data transmission in the wireless networks with ultra-densely distributed devices.

Transmitting data wirelessly involves converting it into radio waves that travel through the air –this stage is the air interface. However, the air interface processes signals over very crowded and expensive radio frequencies, and too much data traffic across these limited frequencies can lead to interference. Our researchers are developing new techniques for sending and receiving signals, and novel designs of the signals themselves, to make the most efficient use of the radio frequency spectrum.

Our researchers were also key players in FLAME7, a four-year EU-funded programme that tested the adoption of 5G in the media sector, designing network architecture to meet the exponentially increasing demands on mobile broadband access. The programme conducted 50 trials with partner companies across Barcelona, London and Bristol, where software-defined 5G infrastructures were deployed as service delivery platforms, enabling localised content delivery with lower latency and higher efficiency.

Another area of investigation is grant-free multiple access (GFMA). In the current cellular system, each time someone uses their phone it has to request access to the network from the base station – known as grant multiple access. But in the context of millions of IoT devices, requiring a ‘handshake’ for each connection would overwhelm the base station, result in heavy overhead, long delay and resource wastage. For low-power IoT devices, it would also use up limited energy and computational resource within the devices themselves.

7 https://www.ict-flame.eu/index.html

“This project was all about managing cloud native service delivery into the edge of networks. As part of the Internet Engineering Task Force (IETF)

‘Computing in the Network’ Research Group, we’re exploring novel use cases pushing software defined connectivity at layer 2 further into device.”

Professor Michael Boniface Director of IT Innovation Centre

A GFMA system removes this problem by enabling devices to send their information without requesting access. However, it adds complexity at the base station, which is no longer in control of what type of information is coming in and from which IoT devices. Our researchers are helping to overcome this challenge by designing high-efficiency GFMA schemes and the algorithms that will enable base stations to understand and effectively manage the network traffic.

Communication in motion

As IoT devices become integral to vehicles and transport systems, the Centre’s researchers are exploring new ways to ensure effective wireless communication when travelling at high speed. For example, how can IoT devices on a plane or train communicate with a fixed station on the ground, and how will the autonomous vehicles of the future exchange information while travelling on the motorway? In these contexts, the speed of travel causes problems such as the Doppler frequency shift and the wireless channel changes very quickly, creating rapid changes in the quality of the transmission. Our researchers are exploring spectrum sharing schemes and multiple access schemes to overcome this.

They are also looking at the optimum routing protocols for networks of smart vehicles, where it’s useful to share information such as accident and traffic information, or stream entertainment for passengers. This can be done via fixed base stations along the route, or the vehicles can transmit information between themselves. Using theoretical design and computer simulation methods, our researchers have found that a hybrid technique that uses vehicles and the roadside infrastructure is the most efficient approach.

Using smart devices to extend the communications infrastructure

Smart IoT devices can themselves be used to enable communications in circumstances where the existing infrastructure is unable to meet demand – for example a large crowd in a football stadium. In scenarios like these, teams of drones can serve as temporary base stations and our researchers are using optimisation and machine learning techniques to analyse networks and understand how drones can be used most effectively.

“This research aims to understand the communication links between the drones and the users on the ground in order to find out the number of drones needed to cover a specific area, how best to position them and whether it’s more effective for the drones to cooperate to provide maximum coverage, or for each drone to service a particular group of users.”

Dr Mohammed El-Hajjar Associate Professor in Next Generation Wireless

Smart drones can also provide additional communication resource by caching soughtafter information to avoid overwhelming base station resources. This could prove useful in scenarios where there are large crowds and the network isn’t able to cope with demand, or for getting information to people in disaster situations where the communications infrastructure has been damaged.

The drones would identify the most searchedfor topics and cache relevant information, sending it to users on request and therefore reducing the number of contacts with the base station. Our researchers have explored ways to identify and cache the information and how best to optimise the deployment of the drones in different scenarios. This included looking at drone numbers and location, and whether it was more effective for each drone to cache one topic or for every drone to cache several topics.

Communication within intermittently powered and batterypowered networks

An IoT device that is plugged into a power source can communicate through a wifi network, but battery or self-powered devices, which make up a large proportion of IoT devices, don’t have the necessary ‘energy budget’ to use wifi. That’s where the use of low-power networking technologies comes in. Typically in these networks, data travels from the devices to a central hub, where it is collected and sent on to its final destination via the internet.

A branch of the Centre’s work is investigating how the individual devices can best transmit or ‘hop’ data across the network to achieve this end goal. In particular, our researchers are looking at how to select the most efficient route for data in networks where the devices are powered by energy harvesting. This is a challenge because, in the interests of energy efficiency, the devices are only switched on when they need to perform a particular task.

Where devices are battery powered, the challenge lies in optimising the battery life, balancing the energy needed for communication against the requirements of other essential functions. Our researchers have looked at how to route data in different ways at different times to maximise the battery life of all the devices in a network. At central hub or base station level, they have also used techniques such as genetic algorithms and machine learning to optimise battery life across a network.

Testing compatibility and standardisation for environmental monitoring

Deploying IoT capability in remote locations and harsh conditions creates a specific set of communications challenges, and our environmental monitoring specialists have tested different types of networks and channels, as well as looking at the standardisation that is needed for the IoT to realise its full potential. Their work on glacier monitoring has taken advantage of long-range radio and the low-power internet (the same technology used to transmit data from domestic smart meters, for example) and direct long-distance communication between devices across the web and low-power web.

Communications for the molecular IoT

Looking to the future, the molecular IoT is an area full of exciting possibilities – for example, it could see the deployment of self-organised networks of nano-scale devices inside the human body to diagnose health conditions, or in the environment to monitor soil or water

“My interest is in communication across intermittently powered networks – how you pick the route that’s most likely to get your data from the source to its destination when neither the sender or the receiver are continually switched on.”

Professor Geoff Merrett Head of Centre for IoT and Pervasive Systems

quality. Our researchers are investigating ways to support molecular communication in nano-networks, and how to overcome issues relating to the efficient propagation and detection of molecular signals in different physical environments.

“For environmental work it’s all about lower-frequency, longer-range communications, and transmitting tiny amounts of data rather than downloading web pages or sending big files. The communications are slower over a longer range and must be robust against the elements. Ideally, they should also use web protocols that offer a standardised way of setting up and configuring communications networks, rather than requiring bespoke programmes.”

Professor Kirk Martinez Professor in Web and Internet Science