Sensor to Shooter: Steps towards the digital battlefield | ADM Aug 08

1 August 2008

Will the so-called digital battlefield—that disappearing point on the horizon of successive NCW Roadmaps—ever be fully realised?

Perhaps not, but in the meantime even piecemeal adoption of technologies contributing to that land NCW ideal—the digital soldier—have to be steps in the right direction.

By Tom Muir

Implicit in the achievement of the networked battlespace is access to bandwidth and the transfer of data on a scale that may have seemed unthinkable even a decade or so ago.

The introduction of battle management systems for mounted and dismounted infantry in battle groups, and C2 systems for artillery and armoured brigades, is possible only because of the availability of fast data transfer systems below the brigade level, able to handle and process their multi-dimensional information requirements.

But despite the advantages of the high capacity digital combat radios that the ADF is currently assessing for the networking of deployed battle groups, their VHF/UHF voice and data networks are limited by terrain and range.

Full coverage of the battlespace must necessarily rely on radio relays, such as those deployed on UAVs, and of course, satellite communications.

And one aspect of the latter in which the Defence Science & Technology Organisation (DSTO) is showing interest, is military command-on-the-move via satellite, whereby commanders in vehicles can receive and transmit satellite while moving.

Satcom-on-the-move
Queensland firm EM Solutions, a specialist designer and supplier to commercial and military users in the telecommunications sector, has won a CTD contract for battle command-on-the-move X and Ka band communications.

It is expected that the proposed system would be able to be integrated onto a variety of military platforms—Bushmaster a possible example—providing ADF commanders with enhanced mobile situational awareness while on the move.

Over the past 10 years EMS has built an enviable reputation for its ability to meet challenging demands from military and civil clients.

Its microwave link products and military satcom equipment have demonstrated high performance and reliability.

The company recently supplied Defence with RF equipment for the Navy's Advanced Satcom Terrestrial Infrastructure System (ASTIS) Maritime Communications Element (MCE). This equipment consists of 70/140 MHz to Ka band up/down Converters and Ka band solid state power amplifiers (SSPA).

The company is also supplying RF Equipment for use by the Australian Army consisting of L-band to Ka band up converters and Ka band SSPA.

EMS also installed a trial broadband-on-the-move for pay-TV services on the Cairns Tilt Train, using their Ku band satellite tracking antenna system.

The diesel tilting train travels at speeds of up to 160 kilometres per hour between Cairns and Brisbane.

However the system did not progress to operational service as the availability of the system was below an acceptable level.

According to Peter Woodhead, EMS Business Development Director, the development of a Ka-band satellite tracking antenna system was very much a strategic decision by EMS.

To date EMS has concentrated on development of Radio Frequency (RF) components as part of systems developed by other vendors.

However the company felt that its long-term sustainable growth would be enhanced if it developed an antenna subsystem where a high level of integration of the RF and antenna was required.

Woodhead says EMS regards the CTD program as particularly important in that it provides an opportunity for an Australian SME (EMS), a Defence Prime (their teammate BAE Systems Australia) and a potential End User (the military) to define, develop and test an emerging capability for the ADF.

Wideband Global Satellite system
And it would appear that EMS lost no time in seeking future opportunities from the advent of the Wideband Global Satellite (WGS) system.

Earlier this month, following a successful operational test program, Australia commenced receiving operational capability from the WGS system providing access to a world-leading communications capability in terms of coverage, operational flexibility and bandwidth.

More capability will be incrementally received from the system as more satellites are added to the constellation, with full operational capability achieved by 2013.

The WGS program will comprise a constellation of six 13-kilowatt spacecraft in support of US and Australian warfighting information exchange requirements, enabling execution of tactical C4ISR, battle management and combat support information.

WGS will provide two-way X-band and Ka-band communications as well as Ka-band broadcast services to meet US and Australian military requirements.

The WGS design includes 19 independent coverage areas that can be positioned throughout the field of view of each satellite.

This includes eight steerable and shapeable X-band beams formed by separate transmit and receive phased arrays, 10 Ka-band beams served by independently steerable, diplexed antennas, including three with selectable RF polarization, and transmit/receive X-band Earth coverage beams.

The enhanced connectivity capabilities of WGS enable any user to communicate with any other user with very efficient use of satellite bandwidth.

A digital channelizer divides the uplink bandwidth into nearly 1900 independently routable 2.6 MHz subchannels, providing connectivity from any uplink coverage area to any downlink coverage area (including the ability to cross-band between X and Ka frequencies).

Under its agreement with the US, Australia has funded one satellite plus associated ground infrastructure to extend the constellation to six satellites, with the US providing funds for the remaining five.

Battle Group BLOS communications
Our understanding is that the CTD awarded to EM Solutions will aim to demonstrate broadband satellite feeds directly into battle group and below command vehicles, while on the move as distinct from mobile satcom 'at-the-halt'.

There are of course significant advantages in having robust beyond-line-of-sight (BLOS) communications available on and behind the battlespace.

Broadband satcom, as promised by the WGS capability, will be able to deliver data, voice and video directly down to battle group and lower echelon commanders.

This CTD, which is properly C2-on-the-move (C2OTM) will provide tactical commanders with important new capabilities, especially in fast moving counter insurgency or similar operations.

Assuming command vehicles could be operating close to or within hostile territory, a major challenge for EMS (and their teaming partner BAES) will be to design a (preferably) low profile antenna that can provide continuous connectivity in conditions where commercial terminals could be expected to fail, providing up to 1 Mbps continuous data rates for command elements on the move.

The antenna must be able to automatically and rapidly recover from signal blockages due to buildings, terrain or foliage or weather and other atmospheric conditions (Ka-Band is susceptible to attentuation from rain).

Since the WGS provides multiple steerable spotbeams including diplex antennas, direct communication via satellite between vehicles or battle group headquarters will be possible, or the satellite feed could be distributed via high speed modems to mobile 'subscribers' or through IP networks accessible by high data capacity combat radio systems, such as MBITR JEM and EPLARS, now being acquired under Land 200 and JP 2072.

But are we reinventing the wheel?

The US communications network program WIN-T is the fundamental communications network developed for current/modular and Future Forces, providing the tactical and mobile enterprise network from theatre through battalion and down to the Land Warrior squad.

While existing networks support command posts on the halt, WIN-T will extend its services to all forces, while stationary and on the move.

The system integrates satellite and line of sight waveforms providing capacity and efficiency over current transmission systems.

General Dynamics, is the prime contractor for WIN-T (and the since-dismissed prime contractor for JP 2072).

With users relying on video and images, broadband connectivity becomes an essential service at all echelons. Providing wide-band connectivity to mobile and dismounted users still poses a technical challenge for WIN-T development, requiring special terminals

Antenna design opportunity
Satellite on-the-move (SOTM) capability requires a satcom terminal to maintain communications with the satellite, while on the move.

This is achieved by stabilising the antenna or utilising electronic wave forming mechanism and various antenna systems are being proposed for this application.

Perhaps this is where EMS steps in with its own ideas on small aperture antenna design and of course access to the expertise of its teaming partner, BAE Systems, on what may turn out to be a very demanding task.

Woodhead feels that the CTD offers the ADF an opportunity to direct the investigation and demonstration of what is possible with a satellite on-the-move system, particularly at Ka-band, and add this to other available technology.

Interestingly ViaSat which has racked up extraordinary prowess in satellite technology, claims to be able to provide affordable, 2-way, always-on, cable-like broadband IP access via satellite to ground, airborne, and maritime platforms while on the move.

This comms on-the-move system allows commanders, sensors, and weapons systems to interact to establish a real-time view of the battlefield and allocate firepower as effectively as possible.

The system enables the IP-based capabilities such as live video conferencing, streaming video, and C2PC Situational Awareness.

ViaSat's ArcLight-based systems feature very small aperture antennas and intelligent burst control technology to combat the effects of satellite signal blockage to deliver cost-effective broadband access while in motion.

ViaSat's Mobile Satcom System is operating on several platforms ranging from Black Hawk helicopters to Humvees.

Satellite IP network
DSTO's interest in satellite communications is wide ranging and, unrelated to the foregoing Satcom-command-on-the-move CTD, it has devised a communications system, Secure Satellite Internet Protocol Network (SSATIN) to demonstrate access-on-demand and bandwidth-on-demand capabilities to the Australian military.

According to DSTO researcher Phil Stimson, SSATIN has been envisaged as a means of supporting networked operations in a deployed theatre, with communications connected back to Australia by a separate, but network connected, rear link.

The advantages SSATIN offers over traditional satellite link systems are that the available bandwidth can be used more efficiently and more flexibly.

SSATIN essentially constitutes a sky-borne Ethernet system that can be easily integrated with terrestrial IP networks and network management systems.

Space communications terminal
The system has been trialled using the Ka-band regional and steerable spot beams of the Optus C1 satellite, but could be used on any satellite with transponders having sufficient bandwidth.

The WGS system is an obvious example and its steerable multi spot beam capabilities will enable system managers to change the area of terrestrial coverage provided when supporting deployed military operations.

The system uses Time Division Multiple Access (TDMA), commonly applied in mobile phone networks.

TDMA allows several users to share the signal bandwidth of a particular frequency channel by dividing the signal into different timeslots.

Each of several users on a given frequency has an individual set of timeslots, with blocks of digital information (constituting a voice call or computer file transfer operation) transmitted in rapid succession.

During SSATIN transmission operations, IP packets of digital data flow from a Local Area Network into a SSATIN terminal, and are divided into transmit data blocks.

These blocks are transmitted to the satellite and subsequently received by all the modems in the SSATIN system. The appropriate terminal then transfers the data to the destination host.
A transmission burst size of 160 user data bytes has been chosen for SSATIN as an optimal compromise between small bursts, which are more efficient at Voice Over Internet Protocol (VOIP) transmissions, and large bursts, which offer greater efficiency for data file transfers.

Traffic control
The SSATIN system consists of a number of interlinked communications terminals, so that any terminal can interact with any other in the SSATIN system if authorised to do so.

The process of regulating the system is undertaken by the Network Controller, which issues transmission instructions in updated form every 0.4 seconds.

During operations, the SSATIN terminals continually monitor their IP traffic loads and traffic priorities.

The Network Controller is able to grant more bandwidth for needy service users while reducing allocated bandwidth for idling users, thereby optimising network operations.

To protect against eavesdropping, various aspects of system operations, including user data, network management information and user requests for access and bandwidth, are all encrypted, and packet length information is also protected.

In addition to data security, SSATIN incorporates features to enhance security against interference.

Protective measures include control signals that are time-hopped in a random manner, and all user terminal slot allocations are likewise randomly varied.

To guard against system failure, identical software is loaded on all SSATIN terminals so that any terminal may become a Network Controller if the original controller becomes defective.

SSATIN allows for the simultaneous use of full duplex (two way), asymmetric and broadcast (one way) services simultaneously.

Voice communications are carried via VOIP technology, and multicast IP traffic for audio-visual communications is also supported.

The SSATIN system overall is seen to offer the advantages of flexibility, access for greater numbers of users, increased efficiency with higher total traffic volumes serviced, and a synergy with other network-based information technology systems.

It also makes possible reductions in manning and personnel costs, and provides better communications support for operatives, including warfighters, on the move.