LINK 16

Link 16 Systems tree

What is LINK 16?

Link-16 is a high capacity, secure, jam-resistant, nodeless broadcast-type RF data link that uses a Time Division Multiple Access (TDMA) protocol. It provides information distribution, position location, and identification capabilities in an integrated form for tactical military operations. Link-16 utilises the Joint Tactical Information Distribution System (JTIDS) or the Multi-Functional Information Distribution System (MIDS) terminals, and the protocols, conventions, and fixed word message formats defined by STANAG 5516. JTIDS/MIDS operates in the upper ultra high frequency Lx band.

How does LINK 16 work?

Link 16 operates in the UHF frequency band, providing line-of-sight and beyond-line-of-sight connectivity over considerable distances. It employs a TDMA (Time Division Multiple Access) architecture, allowing multiple users to transmit and receive data on the same frequency without interference.

What are the 3 requirements to get into link 16?

• Correct crypto (Key)
• Network Design Load (NDL)
• Time synchronization (NTR)

Which F-16 Variants have LINK 16 implemented?

Check F-16 Variants.

What is a J-Series message?

• It is a template for data exchange that is programmed into the link 16 structure
• Its data fields are populated by transmitting aircraft and interpreted by receiving aircraft

LINK 16 Limitations in Falcon BMS

• Only C2 can provide SURV air track information.
• Secondary fighter air target tracks, Lock lines and AMRAAM shotlines are not currently implemented.
• Ground LINK 16 is not currently implemented.

LINK 16 PPLI vs Surveillance

• Add later

Acronyms

Short form	Full form	Implemented in BMS	Meaning
	Donor	Partially yes	For situational awareness during a mission, pilots may want to monitor aircraft or targets reported by aircraft that aren’t part of their flight or team. These aircraft, known as donors, can be designated during mission planning (via the Data Cartridge), or selection or deselection can be managed in the cockpit through the LINK 16 DNR page on the DED. Note: Secondary fighter air target tracks, Lock lines and AMRAAM shotlines are not currently implemented.
FC	Fighter Channel	Yes	This Channel establishes the subnet on intraflight communications. This subnet is used to share ownship targets within a flight. The pilot would change the Fighter Channel to receive target information from aircraft that are operating on a different fighter-to-fighter subnet (e.g. different donors) or to join another flight. All members of the flight must select the same Fighter Channel; otherwise, the Link 16 target sorting messages from the flight members will not be received. The numerical value can be set between 0 and 126.
IDM	Improved Data Modem	Yes	The F-16's improved data modem is a crucial component of its avionics system, enhancing communication capabilities for both command and control purposes anddata transfer. The IDM facilitates seamless and secure transmission of various typesof data, including mission-critical information, sensor data, and tactical updates between aircrafts. IDM was designed in the late 70’s before LINK 16 was on the horizon of the aircraft manufactures. Even if limited in features compared to MIDS/JTIDS systems, it follows the same principle of exchanging data.
JDN	Joint Data Net	Yes	An interconnected network of JTIDS/MIDS based systems which links air and missile defence Command and Control and weapons systems across L16 capable forces.
JTIDS	Joint Tactical Information Distribution System	Yes	Refers to the communications component of Link-16. It encompasses the Class 2 terminal software, hardware, RF equipments, and the high-capacity, secure, antijam waveform that they generate. Among NATO subscribers, the equivalent term for JTIDS is the Multifunctional Information Distribution System (MIDS).
MC	Mission Channel	Yes	This Channel establishes the subnet on the C2 (e.g. AWACS or ABCCC) aircraft is operating. The control NPG is used by C2 to transmit assignments to the flight lead and for the flight lead to transmit responses and report assignment status. As a flight progresses to the target area, the controlling aircraft could change. When a controller change is required, the current controlling aircraft transmits a request for handover message to the flight indicating the new controllers subnet (i.e., MC). After accepting the handover request, the flight members change the mission channel to communicate with the new controller. The numerical value can be set between 0 and 127.
MIDS	Multifunctional Information Distribution System	Yes	See JTIDS
NDL	Network Design Load	Yes	This system used to initialize the JTIDS/MIDS terminal
NPG	Network Participation Groups	Yes	FC and MC channels are part of dedicated NPG’s. Each channel and its number define what data can be exchanged on that channel. If you create a package for example, all LINK 16 capable aircraft of this package will have the same FC and MC (because one AWACS controller will be responsible for this package).
PPLI	Precise Participant Location and Identification	Yes	PPLI air tracks are shared between aircraft sharing the same NPG. Each PPLI message contains an abundance ofinformation about a unit, including its detailed position andidentification information, its time quality, its IFF codes, and much more.
SC	Special Channel	Yes	This Channel establishes for SEAD NPG and identification information.The numerical value can be set between 0 and 126.
SURV	Surveillance	Yes	This message is used to share air trajectory data and is primarily disseminated by command and control agencies.

LINK 16 Net Message Table (STANAG 5516)

J	Series	Message	Note
J0.0	Network Management	Initial Entry	Provides the data elements, in a known time slot, required for net entry.
J0.1		Test Message	Used for terminal test and performance evaluation.
J0.2		Net Time Update	Adjusts the system time to a standard time.
J0.3		Time Slot Assignment	Permits dynamic assignment of time slots.
J0.4		Radio Relay Control	Provides the means for the JU responsible for relay control to assign and deassign the paired slot radio relay function to a terminal and to control the relay function parameter.
J0.5		Repromulgation Relay	Requests that those messages in the same time slot containing the J0.5 message be relayed by all JUs receiving the message.
J0.6		Comm Control	Initiate or terminates specific transmissions to control communications, and requests network management actions.
J0.7		TSR Announcement	Provides the capability for a JU to request a percentage of time slots from a shared pool and disseminate the requests of other JUs.
J1.0		Connectivity Interrogation	Solicits direct or indirect connectivity of the addressed JUs to support route establishment.
J1.1		Connectivity Status	Disseminates direct or multilevel connectivity of the source JUs.
J1.2		Route Establishment	Establishes a route for relay/destination control.
J1.3		Acknowledgment	Used by a JU involved in ground-to-ground communications to respond to messages that require machine receipt/compliance.
J1.4		Communication Status	Used by JUs to report the connectivity quality of its direct communicants to Net Control Station (NCS) and other direct communicants.
J1.5		Net Control Initialization	Provides a number of initial terminal parameters required to allow a terminal to actively participate in an established net under the control of a dynamic net manager
J1.6		Needline PG Assignment	Used by the designated NCS to assign an addressed JU its associated destination Source Track Numbers (STNs) with Participation Group (PG) numbers to form Needline PGs.
J2.0	Precise Participation Location & Identification (PPLI)	Indirect Interface Unit PPLI	Provides Participating Unit/Reporting Unit/Generic Unit information on the Link 16 network when network participation status, identification, and positional information is forwarded from Link 11/11B.
J2.2		Air PPLI	Provides all JUs information about airborne JUs on the Link 16 network. It is used by airborne JUs to provide network participation status, identification, positional information, and relative navigation information.
J2.3		Surface (Maritime) PPLI	Provides all JUs information about surface JUs on the Link 16 network. It is used by surface JUs to provide network participation and relative navigation information.
J2.4		Subsurface (Maritime) PPLI	Provides all JUs information about subsurface JUs on the Link 16 network. It is used by subsurface JUs to provide network participation status, identification, positional information, and relative navigation information.
J2.5		Land (Ground) Point PPLI	Provides all JUs information about stationary ground JUs on the Link 16 network. It is used by stationary ground JUs to provide network participation status, identification, positional information, and relative navigation information.
J2.6		Land (Ground) Track PPLI	Provides all JUs information about mobile ground JUs on the Link 16 network. It is used by mobile ground JUs to provide positional information, and relative navigation information.
J3.0	Surveillance	Reference Point	Used to exchange tactical information about geographic references.
J3.1		Emergency Point	Provides the location and type of an emergency that requires search and rescue.
J3.2		Air Track	Used to exchange information on air tracks.
J3.3		Surface (Maritime)	Used to exchange information on surface tracks.
J3.4		Subsurface (Maritime) Track	Used to exchange information on subsurface tracks and Datums.
J3.5		Land (Ground) Point/Track	Used to exchange tactical surveillance information on land points and tracks.
J3.6		Space Track	Exchanges information on Space and Ballistic Missile tracks.
J3.7		Electronic Warfare Product Information	Provides the means to exchange tactically significant information that has been derived from electromagnetic sources.
J5.4	Anti Submarine Warfare	Acoustic Bearing/Range	Used to report acoustic bearing and range of subsurface contacts.
J6.0	Intelligence	Intelligence Information	Provides the means to exchange tactically significant information that has been derived from electromagnetic sources.
J7.0	Track Management	Track Management	Used to transmit information necessary to effect management actions on tracks being reported within the interface. Management actions include dropping tracks, reporting environment/category and identity conflicts, changing environment/category and identity, changing alert status, and changing strength.
J7.1		Data Update Request	Used to request tactical information that has been locally generated by units participating within the interface.
J7.2		Correlation	Used to resolve a dual designation problem by identifying one track to be retained and another to be dropped.
J7.3		Pointer	Used to transmit a geographic position to an addressed unit within the interface.
J7.4		Track Identifier	Used to transmit special identification numbers associated with the reference track number (TN).
J7.5		IFF/SIF Management	Used to transmit Identification Friend or Foe/Selective Identification Feature (IFF/SIF) information or a special code on a referenced track. Provisions are available to obtain the most current information by exchanging, clearing, or updating IFF/SIF data between units within the interface.
J7.6		Filter Management	For foreign agency use
J7.7		Association	Used to transmit information, on two or more TNs, that has been automatically or manually associated when the information is deemed to pertain to the same contact. When a determination is made that the relationship above no longer exists, there is a provision for terminating this information association.
J8.0		Unit Designator	Used to transmit to a terminal (from its NCS) the unit designator associated with the TNs in the terminal’s Participation Group assignments. The message will also be used to inform an NCS of a terminal’s unit designator.
J8.1		Mission Correlation Change	Used to add, delete, or change Mission Correlators on a specific aircraft or flight of aircraft.
J9.0	Weapons Coordination & Management	Command	Provides the means to transmit threat warning conditions, alert states, and weapons condition orders, to direct weapon system engagement for air defense and air support, and to direct Anti-Submarine Warfare (ASW) operations.
J9.1		Engagement Coordination	Provides the means for two or more elements to coordinate engagement, to conduct more efficient engagement, and to reduce the probability of wasted resources.
J10.2		ECCM Coordination	Provides the status of an engagement between the Reference TN and the Target TN.
J10.3		Handover	Used to transfer control of aircraft and remotely piloted vehicles/missiles between controlling units.
J10.5		Controlling Unit Report	Used to identify the JU that is controlling the track and to provide the Mission Correlator and/or voice call sign.
J10.6		Pairing	Provides a means to indicate a pairing (not engagement status) between a friendly track and another track or point
J11.0		Weapon Response/Status (1)	Provides weapon compliance responses to controller directives.
J11.1		Weapon Directives (1)	Provides controller directives to a weapon.
J11.2		Weapon Coordination (1)	Used to coordinate the transfer of control authority and the delegation of third party source.
J12.0	Control	Mission Assignment	Used by C2 JUs and optionally by nonC2 JUs to assign missions, designate targets, and provide target information to nonC2 platforms. NonC2 JU acknowledgement of this message is through Receipt/Compliance (R/C) action.
J12.1		Vector	Used by C2 JUs to send vector information and vector discretes specifically to air units operating on its net. Vectors are given for interception of air targets, navigation, and air traffic control.
J12.2		Precision AC Direction	Used by controlling units for operations requiring precise control positioning of mission aircraft (for example, ground-directed release of ordinance, automatic carrier landing operations, etc.)
J12.3		Flight Path	Used by controlling units to provide air units with multiple-leg flight path information.
J12.4		Controlling Unit Change	Used to provide new control agency information to an aircraft prior to handoff to the new control agency. It is also used by a tactical aircraft to initiate control procedures with a new controlling unit or to effect a change of controlling unit in response to a Controlling Unit Change (CUC) Order or by a C2 JU to initiate control by own unit.
J12.5		Target/Track Correlation	Used by controlling C2 JUs to: Correlate a target and a track, Decorrelate a target and a track, and Correlate multiple targets with a track.
J12.6		Target Sorting	Used to: Enable nonC2 JUs to exchange targets and targeting information among themselves, Pass sensor data to C2 JUs and among nonC2 JUs, Pass nonC2 JU engagement status information between nonC2 JUs and from nonC2 JUs to C2 JUs, and; Provide control among nonC2 JUs.
J12.7		Target Bearing	Used by nonC2 JUs to: Exchange target reports using polar coordinates, and may include range, bearing, elevation, rate, and uncertainty data, and; Pass sensor data to JUs.
J13.0	Platform & System Status	Airfield Status	Reports operational status of airfields, runways, airfield facilities, and aircraft carrier flight decks.
J13.2		Air Platform Status	Provides the current status of an air platform including ordnance load, fuel, operational status, and on-board systems’ status.
J13.3		Surface Platform Status	Provides the current status of a surface platform including ordnance load, operational status and on-board systems’ status.
J13.4		Subsurface Platform Status	Provides the current status of a subsurface platform to include operational status and on-board systems’ status.
J13.5		Land Platform Status	Provides the current operational weapons and equipment status of a land platform.
J14.0	Electronic Warfare	EW Parametric	Provides the means to exchange parametric information that has been derived from electromagnetic sources.
J14.2		EW Coordination & Control	Provides the means for Electronic Warfare (EW) participants to coordinate EW activities among themselves.
J15.0	Threat Warning	Threat Warning	Provides the capability for threat warning to targeted friendly platforms, including Threat Type, Threat Posture, Position/Relative Position, Altitude, and Speed.
J16.0		Imagery	Provides the capability to transmit and receive imagery.
J17.0		Weather over target	Provides the current weather conditions over a target area.
J28.0	National Use	US National 1-Army	Purpose is defined by country and service of user.
J28.1		US National 2-Navy	Purpose is defined by country and service of user.
J28.2		US National 3-USAF	Purpose is defined by country and service of user.
J28.3		US National 4-USMC	Purpose is defined by country and service of user.
J28.4		FR National 1	Purpose is defined by country and service of user.
J28.5		FR National 2	Purpose is defined by country and service of user.
J28.6		US National 5-NSA	Purpose is defined by country and service of user.
J28.7		UK National 1	Purpose is defined by country and service of user.
J31.0	Miscellaneous	OTAR Management	Used to exchange cryptonet management information for rekeying the KGV-8 (Thornton).
J31.1		OTAR	Used to transmit the new cryptovariables.
J31.7		No Statement	Used to fill out the remainder of a transmission opportunity when the messages to be transmitted do not require the full number of Reed Solomon code words.
RTT-A	Round Trip Timing	RTT Addressed	Provides the means for a terminal to synchronize with system time using the active synchronization procedure. A specific terminal is interrogated and responds with the RTT Reply.
RTT-B		RTT Broadcast	Provides the means for a terminal to synchronize with system time using the active synchronization procedure. The RTT-B is not addressed to any particular terminal. Any terminal that meets the specified requirement for time quality level responds with the RTT Reply.
RTT-REP		RTT Reply	Provides the means for a terminal to support the active synchronization procedure of another JU by providing time-of-arrival data in response to either an RTT-A or RTT-B Interrogation.

Reference Sources

• MR-1235-AF | Interoperability - A Continuing Challenge in Coalition Air Operations | By Rand | ISBN 0-8330-2912-6
• Understanding Link-16 - A Guidebook for New Users (Link-16 system) (Ver 3 - Sep 2001) | By Northrop Grumman
• Understanding Voice and Data Link Networking - Northrop Grumman's Guide to Secure Tactical Data Links (Dec 2014) | By Northrop Grumman