The purpose of this Data Links Series is to identify different data links, discuss how they have developed politically, and then to provide an insight as to currently available solutions until the future goal of interoperability is reached.  Data link expert Rick Snyder gives us professional insight as he explains IDM, Link 11 and Link 16, their history, and how they can be used together in a complimentary fashion as opposed to competing data links.
Data Links Series Part 3:
Gateways that Enable Communication between Link 11, Link 16, and IDM
Data Links:  Gateways – the way forward with the US Services
The US Services have finally come to grips with the fact that they need to interoperate and the data links they have purchased in the past will not talk to each other.  In fact, in the USAF Tactical Data Link Roadmap they state “The existence of multiple tactical datalink message formats, waveforms, and media impedes the seamless exchange of information across the battlespace.  Gateways enable the exchange of digitally formatted information among otherwise non-interoperable systems.”  They further go on to say “Gateway capability is required to integrate the multi-datalink battlespace (e.g. Link 16, VMF, etc.).  Systems which provide multi-datalink and/or gateway capabilities are a high priority for achieving information interoperability between Link 16 and legacy systems.”
Data Links:  Gateways – definitions of design
Since this revelation that Gateways are required to make disparate data links work with each other many documents have been written on the interoperability requirements and even one MIL-STD that attempted to define how gateways should be designed.  As one might expect, several companies have also developed elaborate gateways to connect the various systems.  Not all gateways are created equal and are not even hosted in the same way.  Some are found in command centers, some on airborne platforms and even some are part of the TACP CASS package.
Data Links:  Gateways – construction
Gateways are similar in construction however.  They all use the hardware associated with each data link they want to “gateway” and a computer to connect them all together.  So a gateway between TADIL J and TADIL K would use the Link 16 hardware connected via a computer to the IDM, a voice radio and a crypto unit.  Gateway architecture will remain this way until the manufacturer of one data link builds the hardware and software into their system to handle the frequency band, frequency hopping and crypto of another data link.
Data Links:  Gateways – Joint Tactical Radio System
Eventually, this will be greatly simplified by the Joint Tactical Radio System (JTRS) which is the “holy grail” of radio compatibility.  JTRS has been in development for approximately 10 years now with only limited results.  Some radio manufacturers claim their radios are “JTRS compatible”, but that only means they have a software defined radio that follows the software configuration architecture (SCA) document defined by the JTRS program.  It does not necessarily mean that they support all the radio waveforms planned to be integrated into JTRS (like Link 11, Link 16 and VMF).  Also, SCA does not necessarily mean that the software from one manufacturer can be ported to another manufacturer’s radio.
Data Links:  Gateways – where do we go from here?
What should countries do until JTRS is available?  Keep your existing data links that came with the various platforms and use gateways to link them together.  As mentioned above, there are several companies that build gateways, but realistically, this is something that could be developed domestically.  That way, the end user has control over the forwarding rules that are used to move data from one data link to another.  The Joint Interoperability of Tactical Command and Control Systems (JINTACCS) in the US is a good place to start for a definition of forwarding rules.  Complying with JINTACCS requirements will ensure coalition interoperability.
If you are looking to purchase new data links, then look at your information exchange requirements (IERs) and also speed of service required.  Ultimately, the parameter that determines data link selection is cost.  While Link 16 is an excellent system, it is very expensive to purchase the hardware, integrate it into the host platform and maintain.  If price is no object, then Link 16 is an excellent choice.  If a low cost data link with Link 16 interoperability is desired, then use IDM and gateways.
Data Links: More information
Now you understand how Gateways are used to bridge the data links communication gap.  This concludes Part 3 of our series Harmonizing Link 11, Link 16 and IDM Through Gateways For Future Interoperability.  For further information visit our website www.symetrics.com.