The Need For Networks
In the dynamic environment of a battlefield, where a fixed communications infrastructure is often impractical, a mobile ad hoc network offers clear advantages. However, there are significant challenges involved in developing such a system, which industry is seeking to tackle.
DIGITAL BATTLESPACE, VOL. 9, NO. 5, September/October, 2017 – A mobile ad hoc network (MANET) describes a communications infrastructure that is partly or completely mobile, while providing the same service as fixed infrastructure from the point of view of the user.
The ‘routers’ on which the network depends are mobile, and the infrastructure needed to create and maintain the network – such as radios and antennas – can be carried on ground vehicles, ships, aircraft, space vehicles or persons. It should not be confused with the kind of service provided on mobile phones or other devices by wireless or cellular networks, which tend to come from fixed infrastructure
A MANET effectively takes infrastructure that has traditionally been fixed and makes it mobile, said Richard Franklin, head of secure communications at Airbus Defence and Space. He compared it to taking mobile phone masts, stacking them on top of trucks and then driving around. This leads to a constantly changing ‘topology’, which refers to the position of different nodes in a network in relation to one another. ‘You need to be able to manage that and make sure you always know the way across that network to the particular person that you’re trying to talk to,’ Franklin said.
A MANET can comprise many different ‘bearers’, from 4G to satellite to Bluetooth. It is important to be able to successfully incorporate all of these, Franklin emphasised. The aim is for the assets to continuously communicate with one other, even switching to another bearer if one is not working, he said, using an example of three or four tanks moving at roughly 65km/h over rough, undulating terrain, while communicating with each other: ‘One minute there are houses between them stopping communications – the next minute they’ve got line of sight. The things are bucking like broncos, and yet they’re all trying to share data continuously – where to fire, what their radars can see, etc.’
The technologies used to accomplish this exist on both an application and hardware level, Franklin said. ‘You have to bring all of that together through all the different bearers, whether it be radio, Bluetooth, Internet or whatever.’ It is vital that applications can cope with these various bearers. As an example, he explained that a major focus is providing video to end users in highly challenging environments. A good video conversation requires a certain level of capacity; as this degrades, it may be necessary to switch from a satellite to a radio network, thus retaining voice communications even when the video has gone.
‘We’ve got certain products that will help you maintain the conversation,’ Franklin said. ‘It won’t drop out… It carries on with the voice in a secure way, until that bearer comes back to a certain level of quality, when the video would automatically come back.’
Networks like MANETs rely on the use of the Internet Protocol (IP) ‘as the underlying transport for content and services’, according to Darrel Beach, consulting systems engineer at Cisco. The company is a major supplier of products and services associated with MANETs, such as Embedded Services Routers (ESRs), which are card- and software-based routers that can be embedded inside mobile devices, turning anything that moves into a node in a network.
Following the ‘broad protocol model of Internet technology’, an application will use IP for delivery of data, while at the same time allowing the IP to make use of underlying media, Beach said. In the case of a MANET, this underlying media would be the network infrastructure, such as radios.
Defence tactical networks rely on the use of multiple radio networks, according to Beach. This makes the IP router the single most important element, as it is required to link separate radio networks together. ‘Evolving tactical networks into broad, comprehensive architectures interconnecting everything is an exercise in effectively and efficiently interconnecting multiple types of underlying radio networks into increasingly larger supersets of users and devices,’ he said.
While the information flow between radio networks goes through IP routers, the type of information involved varies greatly, ranging from full streaming video to standalone position information messages, Beach explained. The ultimate delivery depends on the effectiveness of the IP routers, as these are the building blocks of an IP-based internetwork – a term that refers to the combination of several networks.
‘How effectively the underlying radio systems are used by the IP routing layer and the inherent capabilities of the routers will have a direct and profound impact on not just the effectiveness of the tactical internetwork, but also what capabilities can realistically expect to be functional,’ he said.
The use of IP is now a constant for the delivery of tactical information. ‘This architecture is already the basis for forming all types of tactical networks,’ explained Beach. ‘Understanding this should make it clear that there needs to be particular attention on the features, capabilities and flexibility within the IP routers used in these tactical networks, and with special emphasis on certain technologies.’
On The Battlefield
One of the challenges in building an ad hoc network is incorporating a range of different assets, such as radios and some terrestrial assets, said Chris A Ciufo, chief technology officer at General Micro Systems (GMS), a US producer of computer systems and rackmount servers.
‘[Users] have to deal with the problems of an ad hoc network where the radios are different, the radio performance is different and where sometimes the equipment includes software-defined radios that operate on different waveforms and different radio protocols,’ he explained. ‘And then those radios move: they’re on vehicles; they’re on UAVs. Sometimes they’ve got good transmission and receive capabilities, sometimes they do not and sometimes there’s interference.’
A traditional fixed network infrastructure uses wires to tie these disparate elements together. This is not possible on a battlefield, for obvious reasons, which is why the network is built using equipment such as radios.
‘The trouble is different branches of the service [and] different governments use different radios, and their radios use different protocols,’ he said. ‘Some of them are software-defined but don’t have a fixed waveform – their waveform can hop around intentionally, so the enemy can’t track it. The radios sometimes get interfered with. The radios are moving. The radios are different.’
To counter this problem, GMS uses Cisco’s ESR 5921, which implements Cisco’s protocols, meaning ‘data can be exchanged, mobile ad hoc networks can be created and torn down, and traffic moves around on the battlefield as fast as the radios will allow that traffic to move around’. Effectively, this means that all radios that implement the protocol can communicate with one another, relaying information on their bandwidths such as typical data rates, current status, etc. Routers on the battlefield then have sufficient information to know where a radio is and how to route packets of information to that radio in the most expedient way.
‘The router may see one radio is the fastest way to get [information] to that tank or that truck or that UAV, but also that it’s got a degraded bandwidth right now or its bandwidth is inconsistent, so instead it is going to route its data to another radio,’ Ciufo explained. ‘And sometimes radios disappear and the routers have to find a different way to move their data. So when devices, including routers and radios, implement the Cisco protocol, MANETs can be created.’
GMS uses ESR 5921 in its King Cobra S2U rackmount server, a 19in device ‘intended to go in vehicles or be used in tactical operations and be forward deployed’, Ciufo said. The system can be deployed as part of a MANET and used to relay a wide range of data.
He pointed to blue force tracking as an example, which communicates information on the position of friendly and hostile forces. ‘In order for [the network] to be useful, each of those battlefield assets has to exchange information like civilian airplanes do up in the sky,’ he said. ‘They are saying “I’m a good guy, and that thing over there I see moving around must be a bad guy”. So they could be exchanging moving map data, they may have the capability to identify targets, and they may use radio communications to communicate their map location.’
Additionally, the use of inertial navigation systems on vehicles may automatically communicate a person or asset’s location, so that ‘everyone else is notified and everyone’s map is accordingly updated’.
Another challenge associated with highly mobile networks is that connections to routing neighbours can come and go due to distance and radio obstructions, according to Beach. In order to counter this problem, Cisco offers Radio Aware Routing (RAR), through which radios use specialised routing protocols to quickly provide information on the appearance, disappearance and link conditions of nearby routers.
There are a range of advantages that come through using RAR, according to Cisco. These include high quality voice and video, for example with a faster network convergence through the immediate recognition of changes in routers. In addition, RAR can route around failing or fading radio links and between line-of-sight and non-line-of-sight paths, Beach said.
Furthermore, RAR brings efficiency gains by allowing radio resources and bandwidth to be used more efficiently and allowing route selection to be based upon radio power conservation. Congestion control is performed within the router, limiting the impact on the radio. The company also points to the fact that the use of routing protocols through RAR ‘allows routers and radios to evolve at their own paces’: the two functions are separated, although the networks are integrated.
There are a variety of assets through which data can be transmitted, Franklin said, using an air refuelling tanker as an example. ‘Why not use this as an intelligence hub in the sky?’ he asked. ‘It is sitting slightly out of harm’s way, a good distance from the action, but it is in contact with all of the fighters, probably with ships and probably with ground troops.’ It could therefore be used as a data relay, ‘disseminating and sharing information from the ground, which could be optical pictures’.
He also pointed to UAVs: ‘If you’ve got a UAV flying over an area of interest taking photos, how do you get that information to the marines that are about to land on the beach? That’s the challenge, and MANETs are at the core of that.’
Airbus works in the field of MANETs in a number of ways. As one of the world’s major manufacturers of satellites, the company understands communication challenges, Franklin said, and has created a number of enabling technologies on the ground to help support SATCOM. Perhaps most notably, the Airbus Mobile IP Node is designed to transmit voice, data and video when fixed communications are not available.
‘It’s a very evolving space,’ Franklin said. ‘People are trying more and more to bring the COTS-type technologies, in particular 3G and 4G technologies, into the military space. So being able to deploy those bearers and [support them with] satellite or ground infrastructures has become a major focus for us.’
Airbus is investing heavily in two areas related to MANETs, developing hybrid networks of different bearers and extending the reach of the networks. For the latter, there is particular interest in extending the aerial side of a MANET. ‘What you’re increasingly seeing in defence is they want all of these aerial assets – whether they be planes or helicopters, through to UAVs – to be able to share data, and send that back to base,’ explained Franklin.
There has been a move towards the increasing use of UAVs and UGVs, said Byron Henderson, VP of marketing at MeshDynamics. The US company provides a range of MANET-focused products and services. Its mesh network aims to allow radios to act as both transmitters and receivers of data simultaneously, rather than performing one task after the other.
Henderson identified two distinct trends in building defence-focused MANETs: on the one hand, using highly sophisticated UAVs and UGVs; on the other, deploying thousands of small, ‘dumb’ sensors. ‘It’s gone in both directions, both really dumb, really simple sensors and these very hightech mobile robots,’ he said.
The use of small, lightweight sensors – along the lines of a Smartdust system – is also on the rise. In this sense, lightweight refers to their low levels of power consumption, intelligence and computing power, as well as physical weight. ‘We’ve been working with some of our defence clients on ideas that are really simple protocols, much simpler than IP. These would be less hackable, more lightweight, and cheaper to deploy,’ Henderson added.
The information collected by these lightweight sensors is analysed using big data techniques, in order to provide data on trends, threats and other information, which would then be communicated across the MANET. ‘I think one of the things that definitely is going to go up is this wider deployment of simpler sensors: either it could be on a robotic device, it could be airdropped – there are all kinds of ways these will get deployed. So we think that’s on the low end, the simpler end,’ he said.
On the more sophisticated end, UGVs and UAVs ‘will have lots of video and other kinds of data feeds that will require high performance and might need real-time interaction’, Henderson asserted. ‘We see expansion at each end of the spectrum, from the very simple sensors on one side to the drones and robots that will be creating and receiving all kinds of data at higher speeds.’
However, there is still a grey area around how humans and machines will interact. ‘Will there be more intelligence in the machines, or will it be back at a command and control centre? Those are all areas that I think are in flux in the defence industry, and because of that, they want to be sure they have the potential for as much data at as high a performance as possible so these different things can play out,’ he said. ‘I think the future of that man-machine interface and interaction is a really interesting and somewhat perplexing open question.’
There is a huge amount of data on the modern battlefield, said John Dowdell, product manager at Airbus Defence and Space. It can therefore be very easy to flood a network. Airbus encourages users of the Mobile IP Node to enable decision-making within the applications based on certain rules. For example, they may set a minimum bandwidth requirement for sending video over the network. This frees the user from having to decide what type of data to send. ‘It’s not just about whether you send the data or the voice,’ he said. ‘It is also vital to decide what is operationally important to send.’
Developments In Defence
Traditionally defence has been ahead of the commercial domain in developing technologies, Franklin said. However, this has not been the case in the networking sector – developing a MANET in a highly dynamic military environment is difficult. ‘Networking between multiple assets in a challenging environment is really the focus – doing that securely on the land and then doing it in the air,’ he said.
Looking forward, Franklin explained that a number of countries have modernised their fixed network infrastructure and are now set to turn their attention to MANETs. ‘There is a real focus on how they integrate the radio, satellite and 5G bubbles into a genuine mobile network,’ he said. ‘And to be mobile in defence terms, it has to be ad hoc as well.’
Ciufo expects routers to be further miniaturised in the future, creating lowpower but capable technology that can be placed into any mobile device with ease. ‘If you take that router and migrate that more to the equipment, shrink it down to cell phone-like systems on a chip, then maybe these devices on the battlefield, appropriately configured, can set up ad hoc networks without routers in the middle, because they will have intelligent routers built inside of them,’ he said. ‘I can see that being miniaturised further and eliminating some of those chokepoints, because they’re just built into every device, with the appropriate protocols and the appropriate security.’
We are only now witnessing the birth of the technologies and techniques that will define tactical networks in the coming decades, according to Beach. These networks will be highly flexible and dynamic in terms of their creation and the information they carry, and there will be opportunities to create unforeseen capabilities based upon the ability to exchange more information more rapidly across a wider set of users.
‘There will certainly be some technical and doctrinal hurdles to address,’ he said. ‘How fast hurdles can be addressed and how fast new capabilities can be developed and deployed will in very large part depend on the capabilities of the underlying radio systems and, even more importantly, on the capabilities inherent in the IP router building block of tactical internetworks.’
Radio systems will continue to evolve, Beach said, with technologies like active electronically scanned array antennas and dynamic, high-bandwidth directional radio systems providing game-changing capabilities, ‘provided they can be effectively controlled and utilised at the IP layer by the routers used as the internetwork building blocks’.
Specific attention must be paid to the capabilities and characteristics of the underlying radio systems and how they are used by the IP routing layer. ‘The writing has been on the wall for many years,’ Beach confirmed. ‘IP-based communications enable game-changing advancements in speed, agility and reliability for communicating and collaborating across previously disparate organisations, equipment and even physical environments.
‘As the next phase of this evolution begins, it is critical to understand the power and flexibility that can be gained by proactively addressing the foundational IP capabilities as a core requirement in tactical communications.’
The development of MANETs has come with significant challenges, particularly surrounding functionality and security. MANETs and similar networks are interesting because of the trajectory of many areas of technological development, which have seen a shift from the civilian to the military space.
It seems certain that this area will see further major advances in the coming years. The continuous evolution of unmanned technologies and artificial intelligence seems to be a particularly crucial theme, expanding the range of potential platforms to carry the necessary infrastructure, without adding security risks.
By Gerrard Cowan