During my time with the Air Force Life Cycle Management Center I provided engineering and acquisition support to the 653rd Electronic Systems Wing as a Mission Systems Engineer. With six squadrons and 720 personnel, the 653 ELSG acquires, delivers and sustains Air Force and Joint systems for airspace management, communications and intelligence, surveillance & reconnaissance, providing support to Air Force operations globally.

The wing provides systems engineering and integration to deliver “net centric capabilities to warfighters for effects based combat operations and support”. It also delivers and sustains networks, integrated information systems, enterprise services and applications for the Global Information Grid, facilitating communication between land, naval, air and space warfare forces. The group delivers capabilities for voice, video and data networks focused on joint and coalition warfighter needs to enable worldwide net-centric operations. 

One key system by the 653^rd is called Link 16, a military tactical data link network used by US, NATO and coalition nation states. With Link 16, military fixed wing and rotary wing aircraft as well as ground forces and surface ships  can exchange their tactical picture in near-real time, including the exchange of text messages and imagery data while also providing two channels of digital voice. Link 16 is defined as one of the digital services in NATO’s Standardization Agreement STANAG 5516 and a key service in coalition wartime planning & operations.

What does Link 16 provide to Combat Aircraft? 

As a digital data link for tactical applications, Link 16 offers high capacity, jam resistant message security and transmission security, line-of-sight (LOS) operation with relay to beyond LOS, waveform and data sets standardized for interoperability, a navigation capability, and positive friendly identification and location. 

Link 16 message standards are governed by MIL-STD 6016 & NATO STANAG (Standardization Agreement) 5516. They feature bit oriented messages in a fixed format and 75 bit “words” concatenated to form variable length messages. Also rigorous and well defined change and configuration management and test processes under the purview of DISA/JIEO (Defense Information Systems Agency/Joint Interoperability Engineering Organization). 

Link 16 features both a time slot architecture and multi-netting via. frequency hopping. Time slot assignment and relay assignment are enabled with time slots in a block distributed evenly in time.  By specifying the number of slots and starting slot, and then the number of slots in a block with the largest at 512 slots per each 12 second frame (every third slot). This creates 256 slots per frame. Operators can also assign multiple blocks to each platform. 

Frequency-hopping spread spectrum (FHSS) as employed in Link16 is a method for transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both the  transmitter and the receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code-division multiple access (CDMA) communications. 

What is Link 22? 

Designed to complement and interoperate easily with Link 16, Link 22 was developed to replace Link 11. The program is called “NATO Improved Link Eleven”, which when abbreviated spells “NILE”. The tactical data link provided by the NILE system has been officially designated Link 22. 

What it takes to make Link-16 Work . . . 

Integration of the terminal into the platform includes physical integration, definition of information exchange to support the mission(s), definition of concept for operating within Link-16 networks, design of the operator interface, host software development to ensure  the operation of the platform in Link-16 networks, exchange information with network participants, and provide for operator displays and controls.

How do other countries obtain Link 16 functionality?

In many situations, allied and coalition nations obtain Link 16 through the foreign military sales program . I’ve highlighted a recent example below from the Republic of South Korea:

The State Department has announced the Republic of Korea has requested to upgrade its F-16 Block 32 aircraft with Mode 5 Identification Friend or Foe (IFF) and Link 16 Tactical Datalink (TDL).  Included are ARC-238 radios; AN/APX-126 Combined Interrogator Transponders; Joint Mission Planning (JMPS) upgrade; KY-58M secure voice module; Simple Key Loader (SKL) crypto fill devices; Precision Measurement Equipment Laboratory (PMEL); aircraft ferry support; training; Computer Program Identification Number System (CPINS); flight manuals; flight tests; integration support and test equipment; U.S. Government and contractor, engineering, technical and logistics support services; sustainment and other support equipment; and other related elements of logistical and program support.  The total estimated cost is $194 million. Source: Defense Security Cooperation Agency

Conclusion 

Link 16 (and Link 22) is both a valuable capability and an information distribution system that is complex and expensive to integrate into a C2 or weapons system. It features both time slotting and multi-netting via. frequency hopping, a rich message set based on joint and international standards, and can be employed to support many types of tactical missions. To successfully integrate Link 16 into combat planning and operations requires a substantial operational and support infrastructure.