TECH BRIEF - LINK 16 Link 16 Modernisation

TECH BRIEF LINK 16 MODERNISATION

Part 2 – Strategy Development

The May - June issue of ADBR explored the four key enhancements delivered by Link 16 modernisation. Modernisation of the ADF’s primary Tactical Data Link (TDL) will directly affect the joint force’s capability and capacity to remain at the tactical edge and will most certainly impact our ability to remain fully interoperable with our closest operational ally, the United States.

There are two considerations associated with Link 16 modernisation which involve either upgrading the pre-existing MIDS-Low Volume Terminal (LVT), or acquiring the new MIDS-Joint Tactical Radio System (JTRS). This is not a straightforward decision as capability managers need to balance how to remain fully interoperable and ensure a complete operational capability while meeting mandated operational deadlines, procurement schedules, costs, integration effort and the subsequent maintenance and support needs. In this issue we will examine the strengths and weaknesses of choosing to upgrade an existing MIDS-LVT against acquiring a new MIDS-JTRS, while ensuring an interoperable Link 16 capability.

BLOCK UPGRADE 2 Block Upgrade (BU) 2 is the name given to upgrade the older hardware-defined MIDS-LVT Link 16 terminals, and the level of effort necessary requires further analysis due to several factors.

Firstly, while BU2 provides three of the four enhancements – Cryptographic Modernisation (CM), Frequency Remapping, and Enhanced Throughput (ET) – it does not support the fourth –

BY FELIX DEFENCE Concurrent Multi-Netting (CMN)-4.

The CMN-4 enhancement is described as an advanced capability and is currently only applied to the MIDS-JTRS Software-Defined Radio (SDR). This instantly puts a user who has chosen the BU2 upgrade path into the category of being classed as a disadvantaged user in future Link 16 networks, and potentially undermine the user’s operational capability and thus interoperability. However, CMN-4 has not yet been mandated for use but for how long that remains the case is still unclear.

Secondly, for a platform to realise the full potential of ET and be able to employ all five ET rates, it would have to make considerable changes to the host system and most likely the interface that connects their MIDS-LVT to the host. For example, the host would have to be able to ‘push, pull, and process’ far more Link 16 data than normal. Furthermore, many MIDS-LVT users utilise a 1553 data bus interface to enable this connection, and the problem is that some platforms use this same 1553 data bus to support the transfer of other data outside of Link 16.

Consequently, the ability to operate at some ET rates may not be achievable as the 1553 bus quite simply cannot handle the increase in data. The only option is for the user to configure a double bus, ie a second ‘Capability managers connection. But ET has not yet been mandated for use and, even if are already aware of the operational deadline it is, what would be the minimum ET rate required? regarding cryptographic modernisation’

CAPABILITY MANAGER’S LINK 16

MODERNISATION CHALLENGE

CAPABILITY

INTEROPERABILITY

It’s a question of getting the balance right (above) between the variables. Below: an MIDS-LVT(1) Link-16 Tactical Airborne Terminal. VIASAT

MODERNISATION PATH

OPERATIONAL DEADLINES

PROCUREMENT

COST

INTEGRATION

MAINTENANCE & SUPPORT

This MIDS-JTRS unit allows for simultaneous 4-channel operation for Link-16, TACAN and Advanced Waveforms. VIASAT

Understandably, capability managers do not want to implement only as far as ET rate 1 to subsequently discover ET rate 2, 3, or 4 is the minimum requirement. Moreover, they do not want to make unnecessary changes to accommodate these higher ET rates if the operational community will never use them.

Thus, BU2 provides enough capability for a user to meet the minimum requirements and should be viewed as a short-term option. The risk for users who choose this path and want to maintain their Link 16 capability in the long-term is that they become a ‘disadvantaged user’ and can only play a reduced part in future operational Link 16 networks.

MIDS-JTRS MIDS-JTRS is undoubtedly the SDR of choice when it comes to Link 16. There are a range of MIDSJTRS from the basic MIDS-JTRS (4) through to the MIDS-JTRS (7), all offering a range of capabilities that complement Link 16 or exist outside of it.

Currently, for many users the four-channel MIDSJTRS (5) is the most practical option and provides the user with all four enhancements. Nonetheless, while MIDS-JTRS users would not require a double bus, capability managers are still faced with the same issue – what ET rate to integrate?

The problem is further compounded with a requirement for the host to be able to process even more data when the MIDS-JTRS is set to receive even more data. As mentioned earlier, the second advanced capability is that of CMN-4, and this enhancement allows a user to receive considerably more data simultaneously, all of which puts increased pressure on the host.

In conclusion, MIDS-JTRS has many advantages over BU2 in that, if changes are integrated to the host system, a user can employ all four enhancements. The addition of the three further programmable channels to support future growth only adds to the list of advantages, and simply being a Software-Defined Radio should allow for a more rapid maintenance and support process. But there are disadvantages, most notably demand and cost, and one should not view the replacement of a MIDS-LVT with a MIDS-JTRS as a simple plugand-play process.

Capability managers are already aware of the operational deadline regarding cryptographic modernisation. They can potentially meet this by choosing BU2, but that will only delay the inevitable move to MIDS-JTRS. Understanding how long a user can survive before the advanced capabilities are mandated is the predicament regrettably no-one can currently answer. The basic trade-off involves sacrificing near-term interoperability for a much more capable system in the future.

In the next issue of ADBR we will introduce and discuss the latest TDL being procured by the ADF – Link 22.