Military Mobile
Ad-Hoc Networking
Research Proposal
Performance Metric Evaluation and Commercial Availability
Thomas Moscon
6/15/2014
1|Page
Contents
1
2
Introduction ................................................................................................................................ 4
Literature Review ............................................................................................................................ 5
2.1
Networking Fundamentals...................................................................................................... 6
2.1.1
3
OSI Model........................................................................................................................ 6
2.2
Ad-hoc Networking ................................................................................................................. 7
2.3
MANETs ................................................................................................................................... 7
2.4
MANET History ........................................................................................................................ 8
2.5
MANET Achievements ............................................................................................................ 9
2.6
MANET Challenges .................................................................................................................. 9
2.7
MANET Performance .............................................................................................................. 9
2.8
MANET Metric Evaluation ....................................................................................................... 9
2.9
MANET Challenges for Military use ...................................................................................... 10
2.10
Combat-net Radios ............................................................................................................... 10
2.11
Multi-hop vs. Single-hop ....................................................................................................... 10
2.12
Metrics .................................................................................................................................. 11
2.13
Commercial-Off-The-Shelf Products ..................................................................................... 11
2.14
COTS Products ....................................................................................................................... 12
Methodology................................................................................................................................. 13
3.1
Literature Comparison .......................................................................................................... 13
3.2
Simulations............................................................................................................................ 13
4
Conclusion ..................................................................................................................................... 14
5
Bibliography .................................................................................................................................. 15
Student address: mosta002@unisa.edu.au
Student ID number: 110043629
Award: Bachelor of Information Technology: Network and Security
Provisional thesis title: Military Mobile Ad-hoc Networking: Performance Metric Evaluation and
Commercial Availability
Supervisors’ names: Grant Wigley
Date of submission: June 15th 2014
Thesis Questions:
What are the key metrics in evaluating performance for Military MANETs?
Thesis Sub-Question
What commercially available products suit the needs for a Military based Combat Net Radio
MANET?
1
Introduction
The Defense Science and Technology Organisation (DSTO) are currently undergoing research on
Military Mobile Ad-hoc Networks or MANETs for tactical warfare purposes due to the need for an
infrastructure-less network communication platform. Currently, the Australian Defence Force (ADF)
is using legacy communications hardware with limited bandwidth capabilities and requires a tactical
communication solution that allows convergence with speeds as low as sub megabit.
Unlike other countries like the United States, the ADF does not have the resources to deploy a fully
converged network infrastructure using satellites and other infrastructure to aid communications
within a short timeline on the battlefield. Instead, ‘Combat Net Radios’ and ‘Man packs’
communicating over UHF and VHF frequencies make up the bulk of the network, most of which is
either carried by soldiers or mounted in vehicles.
MANETs have been used and developed around the world for different tactical purposes and even
spawned from the need for better and more robust tactical networks. The reason Militaries look
towards MANETs is that they provide an infrastructure-less, easy and rapidly deployed network with
little to no management. This type of solution proves to be invaluable since there isn’t always the
time or money to setup network infrastructures on the battlefield for warfare. Instead of routers and
switches forwarding packets between layers of the network, all packets are forwarded by the
Combat Net Radios and Man Packs, making every soldier and vehicle a router in essence.
However there are still many challenges and unsolved issues relating to MANETs with research and
development being an ongoing process, one major issue is the scalability of the network. MANETs
have proven to work for small networks or networks with lots of nodes passing information between
neighbors or back to a server, but a fully converged brigade in the army with up to 1500 nodes
would require an extremely robust system. On top of that, the path of the data through the network
can be altered by the design of the Combat Net Radios and how they interface with the other
hardware.
For this, MANETs as a solution needs to be analyzed and tested thoroughly in order to produce solid
evidence about how to evaluate the performance of a network, and what are the key metrics
involved with the overall performance.
2
Literature Review
This research is dedicated to the findings on how to evaluate networking performance for Military
Mobile Ad-Hoc networks and what commercial-off-the-shelf (COTS) products are available as a
solution to this problem. Ad-Hoc networks can be designed for many purposes, but for each
different purpose, they are designed differently in order to suit networking needs in a very specific
way. The nature of the topic is looking to answer what performance metrics are more important for
a Military scenario and how we know those metrics are important.
The basis for this research is on a Military based MANET with up to 1500 nodes/soldiers in at least a
100x100km square block of mountainous and harsh terrain where nodes are constantly moving.
These types of network parameters are hard to build a network around, but so far, it is theorized
that ad-hoc networking is plausible for this type of tactical warfare.
The research will include looking at previous simulations that have been carried out in the same field
to examine how they weigh metrics, evaluation models and frameworks that outline how to
generally evaluate MANET performance, and a comparison of commercially available products to
determine what type of hardware best suits the needs of a Military MANET and what that hardware
does to perform that way.
2.1
Networking Fundamentals
Generic Local Area Network (LAN) or Wide Area Network (WAN) networks designed for office
buildings and enterprises usually consist of a hierarchical infrastructure. The most basic of these
infrastructures are the three layer hierarchical model, consisting of a core layer providing high speed
routing between major regions of the network, the distribution layer which provides most of the
routing, security and policies and is usually situated at a branch office connecting to the core and the
final layer, the access layer, which connects user devices and servers to the network. This design
model is shown in the figure 1 [12].
2.1.1 OSI Model
Not all networks are designed like this, however they all share a model known in networking as the
‘Open Systems Interconnection model’ (OSI Model) seen in Figure 2 [13].
The OSI Model consists of seven layers of networking each responsible for different tasks in data
transmission within a network.
Application Layer
Reserved for application protocols such as HTTP and FTP. It acts as a user-interface for the user
responsible for displaying images and data in a human-readable format by communicating with both
the presentation and session layer.
Transport Layer
The foundation for TCP, this layers main task is to provide end-to-end communication for
applications within or between networks. It provides reliability and flow-control to ensure data is
transmitted between hosts without failures, corruption or congestion.
Network Layer
Responsible for the routing and forwarding of packets between intermediate routers under
protocols such as Internet Protocol (IPv4/6) and Internet Control Message Protocol (ICMP) through
the utilization of host addressing to distinguish a packets destination.
Data Link Layer
The layer responsible for Ethernet on Local Area Networks (LAN). This layer provides encapsulation
of packets into frames and forwarding data between nodes on the same network with additional
functions such as error detection and correction.
Physical Layer
One of the most complex layers, responsible for network hardware transmission technologies of a
network. Digital Subscriber Line (DSL), Integrated Services for Digital Network (ISDN) and Wi-Fi are
three technologies that reside on the physical layer. Unlike the network layer, the physical layer
transmits raw bits instead of packets over physical links such as copper wires or Cat5 cables.
2.2
Ad-hoc Networking
Ad-hoc networks are an infrastructure-less and decentralized approach to network design. The word
Ad-hoc meaning ‘for this purpose’ assumes that the network is setup for a specific situation or
purpose. In our case, it is for Tactical Warfare. The network is ad-hoc because it does not rely on an
underlying infrastructure with managed routers, servers, access points like a traditional Wireless
Area Network would. Instead, each and every node in the network acts as a router-device,
responsible for forwarding and controlling traffic flow around the network [2].
2.3
MANETs
Mobile Ad-Hoc Networks were originally developed for tactical network communication due to the
dynamic nature of tactical warfare. Military networks have always required a mobile and dynamic
design without reliance on a fixed pre-configured infrastructure, not only to ensure rapid
deployment, but also to keep costs and complexity to a minimum and autonomy at a maximum.
MANETs create a framework suitable for this type of network design by providing an infrastructureless network built mainly upon multi-hop peer-to-peer technology that allows nodes to
communication over long distances and beyond Line of Sight.
2.4
MANET History
The concept of a military MANET over radio originated from an agency known as the Defense
Advanced Research Projects Agency (DARPA). In 1973, the group researched packet-switched radio
communication in order to provide mobile network access to computers and terminals within a
mobile environment [1]. This research was motivated by the need for tactical communication on the
battlefield, and to this day is still being researched for both military and commercial markets.
Packet Radio Networks were the first generation of ad-hoc networks back in 1973. The network
consisted of firmware pre-loaded packet radios that had minimal functionality, but was able to
communicate to other radios using early radio frequency technology. This technology implemented
the physical layer, data link layer and network layer of the OSI model.
The firmware was capable of providing network metrics such as power usage, signal to noise ratio
and even had a basic error detection system which forced a retransmission of dropped packets. The
routing, although primitive at the time, allowed for rapid and automatic deployment of the network,
which was and still is a key factor for tactical communication [6][14].
Second generation ad-hoc networks arrived in the 1980s up to 1993, which were developed and
implemented as a part of SURAN (Survivable Adaptive Radio Network Programs). This enhancement
improved radio performance by making the networks smaller, cheaper, efficient and more secure
[6][14].
A project by the name of GloMo (Global Mobile Information Systems) further enhanced mobile
networking by researching self organizing/self healing networks aimed at intelligence information
systems for the deployment of forces.
The next development in the second generation of ad hoc networks was NTDR (Near Term Digital
Radio Systems), the purpose of which was to provide self-organizing mobile communication
between Army Battle Command System automated systems and units at a brigade level and below
[6].
Finally third generation MANETs, from the 1990s until present day exploded with the invention of
portable laptops and other commercial communication devices based on packet radio systems [6].
MANETS were implemented during this generation and have since been developed for an array of
applications.
2.5
MANET Achievements
Despite the Military background of MANETs, in modern day society, MANETs are used for many
different applications in order to pass information around users. In a lecture by Kim Smith [3], one
particular example of a MANET is Dieselnet, which monitors users who get on and off buses in order
to map out where people are coming and going so that the bus system can create better routes.
2.6
MANET Challenges
MANETs propose many challenges due to the way it is inherently designed. In a MANET, all nodes
are independent of each other, and all operate in a peer-to-peer mode. This infrastructure-less
design adds difficulty to network management, making it challenging to detect and manage faults.
Because nodes in a MANET will always be moving, the topology of the network will be dynamic,
causing frequent route changes which can result in packet losses.
2.7
MANET Performance
The routing performance for MANETs differs for each routing protocol. For example, a routing
protocol such as Dynamic Source Routing (DSR) may incur less overhead than a protocol such as
Optimised Link State Routing Protocol (OLSR) due to the fact that it will transmit traffic data only
when there is data to be sent, where as OLSR floods the network with control and traffic data aimed
at keeping the routing tables updated as much as possible [7][17][26].
However this doesn’t always mean that certain routing protocols are better than others, they may
perform better in certain scenarios and for different purposes.
2.8
MANET Metric Evaluation
In an RFC written by S. Corson and J Macker [4], the authors distinguish a difference in metrics
between a routing protocol and the network context itself. To a further degree, it is also stated that
separate qualitative and quantitative metrics are evaluated for a network protocol.
Qualitative metrics explained were sleep and security, etc., where as quantitative metrics include
throughput and delay, efficiency which looks at data/control bits sent and received, and route
acquisition time. Finally, metrics that are important to a routing protocols overall context are
network size, network connectivity, traffic patterns, mobility, link capacity, and topological rate of
change and others.
There are two main ways to evaluate the performance of a MANET. The first approach uses
measurement techniques in order to evaluate a real prototype network, usually a test bed, which is
important in realising constraints and issues with a network that may not show up in simulations.
One of the largest testbeds with up to 30 nodes is the Uppsala University APE testbed which
revealed problems relating to different transmission ranges for control and data frames, a problem
known as the ‘communication gray zones’ [2].
The other approach to evaluating the performance of a MANET is via a simulation model, usually
simulated on either OPNET or NS-2. Many simulation models have been constructed in order to test
the performance of a MANET [8][9][10][11][23][24][25], but it is important to note that a
simulations do not accurately represent the actual performance of an entire network, rather they
aid us in answering specific questions about the network or help us to diagnose imperatives in the
design. Mobility models in particular aid in discovering the effects of mobility on a network, though
limited, the results these types of models can still provide useful and intelligence evidence.
Lastly, using simulations as a method of evaluating a large network can sometimes be deceiving and
a large understanding of networking is required in order to evaluate the data correctly. Many
researchers delve into the credibility of simulations for MANETs because of this issue [15].
2.9
MANET Challenges for Military use
Many popular MANET algorithms that were designed were done so for small fixed networks,
however a lot of tactical MANETs are designed with thousands of nodes in mind which makes
scalability still an issue that has unresolved challenges that range from configuration management,
security, interoperability, addressing and most of all routing.
In the Military, a term coined SWAP (Size, Weight and Power) is an extremely important aspect for
operating in tactical warfare and adds an extra budget for the types of physical networking devices
plausible out on the field [5][16]. Reducing the size, weight and power of each device on a soldier is
crucial for a more mobile and logistical mission. However, this limits the amount of processing
power allowed on each node which in turn limits the effectiveness of the MANET since every node
must act as a router as well as an end-user device. This proposes a tradeoff between efficiency and
reliability.
2.10 Combat-net Radios
Radio’s used for tactical purposes are generally known as ‘Combat-net Radios’ (CNRs). These radios
are primarily push-to-talk handheld devices that utilize certain waveforms in order to transmit and
receive radio signals. CNRs most popularly operate on the Very High Frequency (VHF band) and the
Ultra High Frequency (UHF) band, meaning they only transmit radio signals between the frequencies
of 30-300 MHz and 300-3,000 MHz respectively.
There are many factors that determine the performance of a CNR. These include power, frequency,
line of sight and environmental interference. For the factors we as humans can control, the more
power used, the greater the range of transmission, but most radios reach up to 10 watts.
2.11 Multi-hop vs. Single-hop
Networks can be also be defined into single-hop or multi-hop. Single-hop refers to a network where
there is only one hop between the source and destination, usually a default gateway or router.
Multi-hop networks are used when there is no default router available, much like a traditional
MANET where every node acts as a router to forward data around the network.
This approach is usually preferable for rapid deployment in hard-to-wire areas making it ideal for
tactical MANETs as it is impossible for the military to wire a network backbone in every location of
operation. It is also required in order to extend coverage of the network through multi-hop
forwarding.
2.12 Metrics
In networking, there are many parameters that can affect the performance of a network, which are
known as metrics. Some metrics are more important to analyse than others when diagnosing issues
or slowness within a network, making it a network administrator’s job to know which metrics are
important for what type of application or network usage. When diagnosing the performance of a
network, network tools are commonly used to display metrics between devices and the overall
network, but can also be output from simulations in order to analyse the performance of a network
in the scenario being simulated.
In the simplest cases, downloading large files from somewhere is a scenario in which a large
throughput is desired, making the speed in which the files are received quicker. Alternatively,
playing a video game over the internet requires extremely low latency, where no delays are present
and the actions/data sent by the client to the server and vice versa and almost synced. With a high
latency, lag would occur and the game would become unplayable.
OPNET, one of the most common networking simulators, is able to output a variety of metrics
including throughput, utilization, number of hops per route, route discovery time, average power
and retransmission attempts. Some of these metrics may affect the performance of the network
more, and others may be barely useful at all. These types of simulators can tell us valuable
information about how a network would perform in a certain scenario, but require a decent
knowledge of the network being simulated in order to properly diagnose the results to make
decisions and answer questions based upon them.
2.13 Commercial-Off-The-Shelf Products
Many Governments purchase what is known as Commercial-off-the-shelf products, meaning
products that are publicly available which can be bought under a government contract. The
advantage of this purchase is the reduction of development, maintenance time and a saving on cost.
Notably, COTS products can also provide a standardized approach instead of a custom in-house
development approach which would add a significant cost to time and money. Standardization also
means that there is already more than enough documentation and support for the product.
It is believed that COTS products are of a higher quality than custom developed products due to the
competitive nature of the marketplace, however true, it may lead to some security issues with the
purchase. Notably in IT especially, COTS products can pose security risks due to the public nature of
the product and the integration with other products. Although this is more prominent for software
products than hardware it is still worth noting that COTS products have been the cause of safety
concerns for the Military in the past.
2.14 COTS Products
Few companies design commercial products for MANET solutions, as they are not a popular choice
for industry networks, however there is still Research and Development carried out for Tactical
MANETs, below are a few examples of some MANET technologies.
Cisco
- Radio Aware Routing for Mobile Networking
Bluetronix (Bluestar)
- R&D for Government Military MANET solutions
- SWARM Intelligent Routing
Trellisware
- Military MANET development, Robust Hardware
- Converged physical/network layer waveform
- Tactical Scalable MANET (TSM) Waveform
Harris
- Another Military hardware provider
- Joint Tactical Radio System (JTRS) certified products
3
Methodology
3.1
Literature Comparison
The first pool of results will aim to compare the simulations and data gathered from existing public
papers to get a rough overview of the most important and key metrics involved with the
performance of MANETs. Only quantitative data will be collected as qualitative data is not relevant
in a Military scenario. The only significant qualitative metric would be security which is a non-issue
for the military.
Metric rankings will be collected from at least 10 different sources, the sources being mostly
conference papers, journal articles and published books. Points will be given to each metric based on
their effect on the performance for each scenario tested.
As this method is unreliable in giving a sure answer to the question with the possibility of mixed
results and a mixture of different test scenarios, it is only done for interests sake, and to see if any
patterns emerge that may provide me with useful information.
3.2
Simulations
Simulations will be conducted using one of the two popular network simulators NS-2 or OPNET. The
conditions for the simulations will be 1 test with a chosen best routing algorithm. First, a base
simulation will be conducted with 1500 nodes in order to achieve a decent network benchmark.
From there, each different network metric will be purposefully interfered with in order to observe
the effect that metric has on the performance of the network.
The effect on the performance of the network will be measured by sending the same artificial traffic
around the network for each test, and analyzing performance metrics such as packet loss, speed of
packets, total control/data traffic sent/received, etc.
Once all the simulations have been carried out as carefully as possible, the data gathered will
hopefully show which metric affects performance the most, and which one affects it the least. From
this, graphs and tables can be deduced that show each metrics affect on the performance of the
network and if there is enough convincing evidence, a ranking table will be formulated.
4
Conclusion
It is obvious that MANETs have potential as a solution for tactical communications but not without
many issues and challenges to overcome such as scalability, network management, terrain
interference, bandwidth and hardware limitations, and overall performance.
However there is no doubt a need for this type of network in the military due to the lack of possible
ways to deploy networking infrastructure on the fly. Utilizing MANETs means cheap and rapid
deployment for the army in the easiest way possible.
Using Commercial-off-the-shelf products is an obvious choice for governments as it cuts cost,
development and maintenance time. As well it provides a more standardized approach allowing for
better support for the product and a better performance guarantee.
Much of the research done for MANETs however doesn’t explain exactly how to measure its
performance. Most of this is done by network tools through the use of algorithms, but a lot of those
tools were intended to measure the performance of generic LAN scenarios and not MANET scenarios
where mobility plays an overarching factor on the performance, as well as the conditions that are
added due to a military setting.
This advocates the question “What are the key metrics in evaluating performance for Military
MANETs”.
5
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