Link 22 Link 22 is a secure digital radio link in HF and UHF band , mainly used by military forces . For example , coast guard will use Link 22 as interoperable communication within homeland security . During the late 1980s , NATO , agreeing on the need to improve the performance of Link 11 , produced a mission need statement that became the basis for the establishment of the NATO Improved Link Eleven ( NILE ) Program . This program specified a new tactical message standard in the NATO STANdardization AGreement ( STANAG ) 5522 to enhance data exchange and provide a new layered communications architecture . This new data link was designated Link 22 by NATO . The NILE program is funded and collaboratively conducted by seven nations under the aegis of a Memorandum Of Understanding ( MOU ) . A steering committee controls the complete NILE program . The program is managed by the Project Management Office ( PMO ) , located at the Space and Naval Warfare Command ( SPAWAR ) ' s Program Management Warfare ( PMW ) 150 in San Diego , California . The PMO consists of a representative from each participating nation and a Project Manager from the US . The Link 22 goals are From 2007 to 2009 NILE nation Germany contracted German industry to enhance performance and tactical capabilities for Link 22 HF fixed frequency ( FF ) operation . Three goals were achieved : In 2012 Germany submitted the new HF - FF technology to NATO and NILE program , for ratification and adoption respectively . The Link 22 system is centered around its core component , the System Network Controller ( SNC ) . This software exists as a single implementation , produced by the NILE PMO and owned by the NILE nations . To ensure compatibility across Link 22 implementations , all participants must use this SNC software . Each implementing nation will acquire this software and will implement it in a hardware environment suitable for its own application . Therefor the SNC is not available as commercial product and is applied by NILE PMO to NILE agreed Third - Party Sales nations at annual maintenance fee . An excellent overview and introduction to Link 22 provides the " Link 22 Guidebook " published by the NILE PMO in July 2009 . This Guidebook has been written in a manner that provides suitable information for Link 22 operators , planners , managers , executives , developers , and testers . Given below is an abstract of chapter 1 of the Link 22 Guidebook . The other chapters 2 - 3 of the Link 22 Guidebook are only available to NILE and Third - Party Sales nations . Chapter 1 should be read by managers , procurers , and anyone who is new to Link 22 . Chapter 2 should be read by planners , operators , and technicians ( those in charge of hardware configurations ) . Chapter 3 should be read by implementers , integrators , testers , and software engineers . Guidebook Chapter 1 : Link 22 Overview . Section A : Introduction . Link 22 is a North Atlantic Treaty Organization ( NATO ) secure radio system that provides Beyond Line - Of - Sight ( BLOS ) communications . It interconnects air , surface , subsurface , and ground - based tactical data systems , and it is used for the exchange of tactical data among the military unit s of the participating nations . Link 22 will be deployed in peacetime , crisis , and war to support NATO and Allied warfare taskings . The Link 22 Program was initially conducted collaboratively by seven nations under the aegis of a Memorandum Of Understanding ( MOU ) . The original seven nations were Canada , France , Germany , Italy , the Netherlands , the United Kingdom ( UK ) , and the United States ( US ) , with the US acting as the host nation . Spain has replaced the Netherlands as a NILE ( NATO Improved Link Eleven ) Nation . Link 22 was developed to replace and overcome the known deficiencies of Link 11 . Link 22 was also designed to complement and interoperate easily with Link 16 . It was designed with automated and simple management to ensure that it is easier to manage than both Link 11 and Link 16 . This program is called “ NATO Improved Link Eleven ” , which is abbreviated to “ NILE ” . The tactical data link provided by the NILE system has been officially designated Link 22 . Communications Security . Link 22 employs a strong COMmunications SECurity ( COMSEC ) system , which is provided by the inclusion of an integral encryption / decryption device inside the Link 22 system . This cryptographic device ( crypto ) at the data link level is called the Link Level COMSEC ( LLC ) . transmission security is also available by the optional use of frequency hopping radios . Tactical Messages . Tactical data is transmitted on Link 22 in fixed format messages , which are part of the J - Series family of messages . It uses the same field definitions as Link 16 to provide standardization between the two tactical data links . Many of the Link 16 tactical messages are transmitted without modification within Link 22 tactical messages . Link 22 specific messages are more efficient versions of Link 16 messages and therefore use less Bandwidth ( signal processing ) . Link 22 provides a number of Quality of Service ( QoS ) features , which are specified with each transmission request . Among other features , the selection of messages for transmission is based on the priority and the QoS of each message , which provides better use of available resources based on the operational situation . Link 22 Super Network . An operational Link 22 system is called a Link 22 Super Network . In its simplest form , a Link 22 Super Network consists of just two units communicating with each other in a single NILE Network . The most complex Link 22 Super Network would consist of the maximum number of units ( 125 ) with eight NILE Networks . A unit participating within the Link 22 Super Network can be a member of up to four of the NILE Networks . A more complex Super Network is shown below . A Super Network enables seamless communication between units using different media to satisfy operational requirements within prevailing media radio propagation conditions . In a Super Network , any NILE unit can communicate with all other NILE units without regard to the NILE Network in which they are participating , thereby extending the operational theater . When a unit retransmits a message to extend coverage this is called relay , which is an automatic function of Link 22 . Automatic Relay . Coverage beyond what the media itself is capable of is provided by the automatic relay of messages and the ability to adapt to changes automatically , without operator intervention . This removes the need for dedicated air relay platforms and relay slot planning and management . A unit will automatically retransmit a received message when necessary to ensure that the message is received by its addressees . The System Network Controller ( SNC ) calculates whether the relay is necessary , based on its knowledge of the connectivity among units . The ability of a unit to relay can be affected by its relay setting . This setting ’ s default is automatic relay , but the unit can be disabled from performing relay or designated as a preferred relayer . Relay is performed on a per message basis . Because messages are retransmitted only when necessary , this reduces the use of bandwidth . Beyond Line - of - Sight communications . Each NILE Network can employ either High Frequency ( HF ) or Ultra High Frequency ( UHF ) communications . HF communications are in the 2 - 30 MHz band , which provides Beyond Line - Of - Sight ( BLOS ) communication ( HF Sky Wave or HF Ground Wave ) optimized for transmission up to . HF also provides direct Line - Of - Sight ( LOS ) communications . UHF communications are in the 225 - 400 MHz band , which provides only LOS communication . Within each band , either fixed frequency or frequency hopping radios can be used . Greater coverage is provided by the automatic relay of messages within the Link 22 system as previously mentioned . Strong Waveforms and Error Correction . Link 22 has better tactical data throughput than Link 11 , and it can even work in conditions where Link 11 will not . When conditions are bad , Link 22 can use more robust media parameter s and maintain communication , although at a lower data rate than usual . When conditions are good , Link 22 can optimize the media parameters to maximize its data throughput . For example , specific media parameters were designed to operate in high latitudes , which present some of the worst - case conditions , and where Link 11 rarely operates . Distributed Protocols – No Single Point of Failure . Link 22 uses distributed protocols , so it has no single point of failure ( that is , the loss of a single unit does not cause the loss of an entire network ) . Some units perform specific management roles , but the system will continue operating without them . Each unit that performs a special role is required to designate a Standby unit , which can automatically take over the role in case of failure . Link 22 has automated Network Management functions that require a minimum of operator interaction , if any . These functions are controlled by the transmission of Network Management messages . Each unit can define whether or not to automatically respond to , and whether or not to automatically perform , each of the Network Management functions . Time Division Multiple Access . Time Division Multiple Access ( TDMA ) is the method by which the transmission capacity available to the entire network is distributed among its members . A cyclical period of time is divided up into timeslot s , which can be of different durations . Most timeslots are allocated to specific units in the network . A unit transmits during its own timeslots . All other units listen during this period , and they may or may not receive the transmission . Priority Injection timeslots may be available , which can reduce the length of time a unit has to wait before it is able to transmit high - priority messages . If multiple units transmit in a Priority Injection timeslot at the same time , the transmission may not be received . Because of this , the transmission is also repeated in the units ’ own timeslot . Automated Congestion Management . At the tactical level , when a unit is congested , it can reduce the local traffic that it generates based on the provided congestion information . In addition , Link 22 automates Congestion Management in a number of different ways . The routing of messages takes congestion into account and will route messages using alternative paths to reduce congestion . Link 22 has a Dynamic TDMA ( DTDMA ) protocol which , when enabled on a NILE Network , allow congested units to automatically request and receive additional capacity on a permanent or temporary basis ( thereby modifying the TDMA structure ) . If DTDMA does not achieve the desired result , the unit managing a NILE Network can change the configuration of the network to redistribute the available capacity , or change the parameters of the media in use in an attempt to increase the network ’ s capacity . As a last resort , a unit can interact with the operator to decide which , if any , of the tactical messages received and queued for relay may be deleted . Late Network Entry . After the Super Network has been started , units that arrive late can join the tactical data link by initiating a protocol called Late Network Entry ( LNE ) . The system also supports units that just want to listen to a network , called receive - only units , which have the capability to request access to the network , but are not allocated any transmission capacity . In addition , the system also supports units that only want to listen to a network without performing any transmissions at all ( silent join units ) . Test Facilities . Link 22 has extensive test facilities available for both compatibility and interoperability testing . The compatibility test system is called the NILE Reference System ( NRS ) , which was developed to test the System Network Controller ( SNC ) and ensure that all modifications to the SNC meet and continue to meet the Link 22 requirements . It can also be used to test the other components of the Link 22 system , such as the LLC and SPCs / Radios . The interoperability test system is called the Multiple Link System Test & Training Tool ( MLST3 ) which was extended to incorporate Link 22 and has multiple configurations available for testing . Section B : Features . This section covers the following Link 22 main features . System Architecture . The design of Link 22 uses a layered communications stack approach to produce an open system architecture , with well defined interfaces between the subcomponents . The approach maximizes extensions and enables contributions from multiple providers . The NILE Communications Equipment ( NCE ) components are the following . The Link 22 system , shown by the outer green box in the figure , consists of the NCE and the Link 22 portion of the Data Link Processor ( DLP ) . Within the DLP , this consists of the interface to the SNC and the handling of the tactical messages that it transmits and receives on the data link . The tactical messages are defined in the NATO STANdardization AGreement STANAG 5522 ] . The DLP is connected to , or is part of , the Tactical Data System ( TDS ) , also known as Host System of the NILE unit , which processes the received tactical messages and generates tactical messages for transmission in accordance with the unit ’ s national requirements . All NILE system components have been jointly defined and designed . The SNC and LLC subsystems have been commonly developed . The development of all other Link 22 subsystems is a national or manufacturer ’ s responsibility . Secure Communications . The LLC uses a weekly key to encrypt and decrypt the data traffic that passes through it . Two sets of keys can be loaded into the device , enabling it to operate up to 14 days without any operator intervention . The next week ’ s key can be loaded at any time during the current week . Detailed information on the crypto key management is contained in the Crypto Key Management Plan document . Transmission security is provided when frequency hopping radios are used . The system is capable of using frequency hopping radios in both the HF and UHF bands . Tactical Messages within Link 22 are handled as sealed envelopes and the system works without access to the tactical data contents . This provides the possibility to encrypt the tactical data at the top level and still be able to transmit it . This additional level of security cannot be provided by Link 16 as the terminal must retain access to the tactical data being transmitted . Tactical Message Transmission . Link 22 transmits tactical data in fixed format messages , and uses the same data element definitions as Link 16 . This provides standardization between the two tactical data links . Tactical messages are composed of from one to eight Tactical Message Words ( TMWs ) . Each TMW is 72 bits in length . Link 22 messages are called F - Series messages and are part of the J - Family of messages . The F - Series consists of two types of messages , the Unique F messages and the FJ messages . The Unique F - Series messages are more compact versions of Link 16 ’ s messages , or messages that do not exist in Link 16 . The FJ messages encapsulate Link 16 J - Series messages within Link 22 messages , enabling Link 16 tactical messages to be transmitted without modification within Link 22 . The DLP requests transmission of a Link 22 tactical message with a Transmission Service Request ( TSR ) . Each request for transmission utilizes a unique identifier and defines the required Quality of Service ( QoS ) . The DLP creates the Link 22 tactical messages from tactical data and the defined transmission requirements of STANAG 5522 . Alternatively , the tactical messages may be created by the TDS and then passed to the DLP . The DLP , however , is the component responsible for passing all Link 22 tactical messages to be transmitted to the NCE . Likewise , the DLP is the destination for all tactical messages received by the NCE . The DLP may perform limited processing of the received tactical messages or may simply pass them on to the TDS for processing . Each message , as mentioned above , can be defined with different QoS . The DLP performs other tactical functions , such as track management , correlation , reporting responsibility , conflict resolution , data filtering , and data forwarding STANAG 5616 Volumes II and III . These functions are a national responsibility , and they may be performed either by the DLP or the TDS . The DLP can perform minimal tactical message processing , or it can be a complete multilink Command and Control ( C2 ) system . Quality of Service . Link 22 provides a number of QoS features that are specified in the TSR . These features enable the efficient use of available resources . QoS features include the following . Priority . Link 22 provides four levels of Priority ( 1 - 4 ) , where priority 1 is the highest and 4 is the lowest . Priority 1 requests can also utilize the Priority Injection Indicator Flag , which has the effect of increasing the priority by moving the request to the top of the priority 1 queue and eligible for early additional transmission in a Priority Injection timeslot , if available . TSRs are considered during packing for transmission in a timeslot in highest priority , oldest TSR order . Reliability . The required reliability of the destination unit receiving the message is included with each tactical message to be transmitted . Three levels of reliability are provided : Standard Reliability has an 80 percent probability of reception , High Reliability has a 90 percent probability of reception , and there is also a Guaranteed Delivery protocol . The probability of reception requested is used to calculate how many repeat transmissions are made . Reliability Protocols remove the need for redundant transmissions by the DLP . The Guaranteed Delivery protocol minimizes the repetition of transmission based on the acknowledgements received . Data Originator Identification . The originator of the data to be transmitted is provided in the TSR . The Link 22 system ensures that this Data Originator Identification is delivered along with the data , so that any unit receiving it knows which unit originated the data regardless of its route through the system . Perishability . Four levels of message perishability are provided by the system , and the TSR specifies which level applies to the data to be transmitted . Perishability allows the definition of how old the data can be before it is no longer relevant , and the Link 22 system ensures that data that has perished is not transmitted . Indicator Flags . There are two indicator flags . Addressing . Two different Addressing services are provided , with and without Acknowledgement , which can usually be used at the same time . For both of these services , there are five types of addressing available . Fundamental Parameters . Link 22 requires each unit to initialize with the same fundamental parameters as all other units . This is fundamental to the operation of the system . It significantly reduces the amount of configuration data to be distributed by the system . These fundamental parameters are supplied to each unit in the Operational Tasking ( OPTASK ) Link Message ( OLM ) , which is provided to the TDS . The fundamental parameters must be supplied to the SNC by the DLP during SNC initialization . This data is maintained within the SNC and is referred to as the Super Network ( SN ) Directory . The generation of the OLM is performed by network planners , who take into account many pieces of information , such as the location of the operations , how many units are expected to participate , the expected tactical message throughput of each unit , and so on . The planners also consider which other tactical data links will be involved . They understand the complete communications infrastructure and define where and how Link 22 is to be used . Media . Media using High Frequency ( HF ) in the 2 - 30 MHz band provides Beyond Line - of - Sight ( BLOS ) communications , optimized for ( but not limited to ) transmission up to . Media using Ultra High Frequency ( UHF ) in the 225 - 400 MHz band provides Line - of - Sight communications only . Within both bands , either fixed frequency or frequency hopping radios may be employed , for a total of four different media types . Each media has one or more different settings , which use different modulation and encoding schemes . Along with the fragmentation rate , these factors determine the number of bits per network packet that are available for transmission , which ranges between 96 and 1824 bits , as can be seen in the following table . The duration of a UHF Frequency Hopping Media Coding Frame is a classified number , and is shown by the notation “ < CN > ” in the table . Network Cycle Structure . The Network Cycle Structure ( NCS ) defines the TDMA protocol for each NILE Network . Time is divided into fixed length periods called minislots , the duration of which varies according to the media type . Periods of time called timeslots are an integer number of minislots , which may be of different size within specific limits . A timeslot is either allocated to a specific NILE unit , or is a Priority Injection timeslot . A unit may only transmit in its allocated timeslot ( s ) , or for certain high - priority messages it may also transmit them in a Priority Injection timeslot . This ensures that each unit has an opportunity to transmit at least once within a given period of time , called the Network Cycle Time ( NCT ) . The NCT is the number of minislots that form the network cycle ( sum of the length of all timeslots ) . The NCT in the above figure is 40 minislots ; however , this can vary up to a maximum of 1024 . When a network is operational the NCS is referred to as the Operational NCS ( ONCS ) . Link 22 has the ability to modify the ONCS . This capability is called Dynamic TDMA ( DTDMA ) . The SNC can also modify the ONCS by supplying a new one . An NCS can be defined by the planners in the OLM . The planners take into account how many tactical messages per second a unit will need to transmit ( Capacity Need ) , including relay traffic , and how long it can wait between transmissions ( Access Delay ) . When the NCS is defined in the OLM , the DLP will initialize the network with the supplied NCS , which will then become the Operational NCS . The SNC can also compute an NCS , in which case the Capacity Need and Access Delay of each unit in the network must be supplied . The SNC also uses two other parameters ( Tolerance and Efficiency ) in its computation , which enables the generation of an optimized NCS that does not meet all the input Capacity Need and Access Delay when it is physically impossible to do so . Media types , media setting , and fragmentation rates all affect the size of timeslots in an NCS . Initialization . Every unit in the Link 22 Super Network uses the same Fundamental Link 22 Parameters to perform initialization . These parameters are specified in the OLM . This significantly reduces the volume of configuration data that needs to be distributed by the system . In fact , Link 22 can be initialized and can transmit tactical messages on a NILE Network at the instant the network is to start , with no prior communications on the network required . Initialization consists of the following two parts . The Link 22 unit ’ s subsystems must be initialized first , before it can initialize any networks . Hardware configuration information must be supplied to the SNC by the DLP . The DLP also must supply the Fundamental Link 22 Parameters so that the SNC can initialize its internal data . When SNC Initialization is complete , the DLP can begin to initialize the individual NILE Networks . The OLM can specify one of the two types of initialization ; either quick initialization ( known as Short Network Initialization ) or an initialization that requires probing of the environmental condition before allowing for tactical traffic to be generated ( known as Initialization with Probing ) . Short Network Initialization can use an NCS defined in the OLM or let the SNC calculate the NCS based on the Capacity Need and Access Delay parameters described above . If the unit has missed the start time for the network initialization , it should join the network by performing the Late Network Entry ( LNE ) protocol . Late Network Entry ( LNE ) provides the unit with the current parameters , which may have changed since the network was initialized . Network Management . Link 22 was designed , using lessons learnt from Link 16 experience , to operate with automated and simple management . The result is that it is significantly easier to plan and operate than either Link 11 or Link 16 . Link 22 has automated Network Management functions that require a minimum of operator interaction , if any . These functions are controlled by the transmission of Network Management messages . Each unit can define whether or not to automatically respond to , and whether or not to automatically perform , each of the Network Management functions . Link 22 specifies two network management roles . For each role , a standby unit automatically takes over the role if the unit performing or assigned that role fails . The new management unit immediately nominates a new standby unit . The system will therefore continue operation without the presence of units originally nominated to perform these management roles , and will operate even if no units are performing the roles . After the Link 22 system has started , the Super Network Management Unit ( SNMU ) has overall management responsibility for the entire Super Network . The Network Management Units ( NMUs ) have management responsibility only for their particular NILE Network . The SNMU can order the NMUs to perform their network management functions . The SNMU can be the NMU for the networks that it is active on . A NMU may be the NMU of more than one network . The SNMU and , in some cases the NMU , can order certain management changes to the Link 22 system , including the following . Other management functions do not require the use of an order , but do require transmission of a message to initiate the change . Joining a Network . A unit that arrives after the Super Network has been started can still join by initiating the Late Network Entry ( LNE ) protocol . This protocol provides the unit with the most current parameters necessary to join the network . The protocol is initiated by the operator and is usually fully automatic , with the protocol ’ s progress available to the operator . A NILE unit may join a network in one of the following three ways . Resilience . The Link 22 system is designed to be resilient . If faults occur , it manages them and attempts to continue operating . A unit participating on multiple NILE Networks can have a failure on one network while continuing to operate on the other networks . A unit is able to handle the closure or shutdown of a network and the restart of the network after the hardware has been reset , without affecting the other networks . When the connectivity changes , possibly due to the loss of a unit or the failure of equipment , the relay automatically takes this into account and modifies message routing in an attempt to maintain the probability that messages get to their addressees . Link 22 automatically retransmits messages to ensure that the requested quality of service ( Reliability ) is achieved whenever possible . This removes the need for the DLP to perform redundant transmissions and minimizes bandwidth utilization . Retransmissions are always placed in different packets on the network so that the loss of a single packet cannot cause the loss of all repeated transmissions . The transmission on the NILE Networks is controlled by the TDMA structure , which is known to each unit , so the loss of any unit does not affect the ability of the remaining units to continue operation . Virtually all functions work in this manner ( called distributed protocols ) , so there is no single point of failure . Some units perform special roles , but the loss of these units is not disastrous to the operation of Link 22 . Any unit that is performing one of the special roles must ensure that it always has a standby unit available to take over the role in case the unit is lost or its Link 22 system fails . A Standby that takes over a role must ensure that a new standby is defined . Messages are exchanged between units , and the loss of reception from the role unit will cause its standby to activate the Role Takeover protocol . Similarly , if the role unit loses reception from its standby , it will give the standby role to another unit . Troubleshooting at the unit , network , or Super Network level is enabled by the reporting of monitoring and statistical data . Each unit ’ s SNC also validates all message data sent to it by the DLP before processing the message , and reports success or failure of each message back to the DLP . If the validation fails , the SNC also provides details of why the message failed validation . Congestion Management . Congestion Management is performed automatically in a number of ways . Message routing will use alternative paths to minimize congestion . When Dynamic TDMA ( DTDMA ) is enabled , a unit that is not congested can donate spare transmission capacity to a congested unit . This affects the allocation of timeslots within the ONCS , but does not affect the NCT . All of this occurs automatically , with no operator or DLP actions required . The NMU can change the ONCS to redistribute capacity . This function , called Network Reconfiguration , causes little or no network interruption . The NMU provides or causes the SNC to generate a new NCS , which can have a different NCT . On successful reconfiguration the NCS becomes the new ONCS . Media parameters can be modified by the NMU in an attempt to increase the available capacity of the network . This requires the network to be temporarily paused and reinitialized with new parameters , which causes a minor interruption of network operations . This procedure is called Network Re - Initialization . The NMU can optionally provide or causes the SNC to generate a new NCS , which can have a different NCT . On successful Re - Initialization the NCS becomes the new ONCS . Unit congestion arises from two sources : the messages the DLP requests to be transmitted , and the messages received from other units that must be relayed to ensure that the messages are received by their addressees . The DLP has full control over messages it has requested to be transmitted . The DLP could delete selected requests to reduce the congestion , and it could reduce the rate of transmission requests . Tactical messages that are being relayed are normally not under control of the DLP . In cases of high congestion , however , the DLP can be informed of the relay messages and decide whether it wants to delete any . This last resort reduces the congestion , but it also affects the delivery of messages . This decision process is called Relay Flow Control . Section C : Benefits . Link 11 is an old tactical data link that does not offer the capabilities and performance required by today ’ s operational community . Link 16 is a complex and robust tactical data link that attempts to meet current operational requirements but is still reasonably old technology . It does not offer recently derived operational concepts , requires extensive planning and is difficult to manage . Link 22 offers the latest technology and uses COTS products . It provides a simple - to - use , sophisticated suite of functions that require minimal operator interaction , and that enable it to be used as both an excellent stand - alone tactical data link or in a complementary role with Link 16 . Link 22 significantly enhances NATO tactical data link capabilities and meets today ’ s increasing need for successful interoperability within allied operations . Comparison with Link 11 . Link 11 has been in existence since the mid - 1950s . It was conceived to support small numbers of units performing mainly an Anti - Air Warfare ( AAW ) role on a single network . In normal use ( Roll Call ) a Link 11 network is controlled by a Net Control Station , which polls each unit in turn to request a transmission . When each unit is polled , it transmits its data without prioritizing the data , so no unit can be polled until the current transmitting unit completes its transmissions . A unit cannot transmit until it is polled . Link 22 was designed primarily as a maritime tactical data link for anti - surface and subsurface warfare , although , like Link 16 , it supports all battle environments . A comparison of Link 11 to Link 22 follows . Comparison with Link 16 . Although it supports all Environment types , Link 16 is primarily an anti - air warfare ( AAW ) tactical data link . Link 22 is primarily a maritime tactical data link designed to complement Link 16 operations . Data transfer rate comparison . The raw ( maximum ) data rates shown in the figures are what is available for Tactical Data transmission , after the low level overheads ( Error Detection And Correction ( EDAC ) bits , synchronization bits , etc . ) have been taken into consideration . Link 22 , unlike Link 11 , can perform simultaneous different transmission on up to 4 networks , which increases bandwidth . Two typical configurations are shown below . Link 22 complements Link 16 by providing additional bandwidth in other frequency ranges and in particular by providing the BLOS and automatic relay capabilities . Section D : Acquisition . It can be seen from the Link 22 architecture that the following components need to be acquired to add the Link 22 capability to a platform . Each listed item will be discussed further . Logistics spares also need to be acquired to provide an adequate level of cover in case of unit failure . Operator Interface System ( TDS / DLP ) . The Data Link Processor ( DLP ) is connected to , or is part of , the Tactical Data System ( TDS ) of the NILE unit . The DLP processes the received tactical messages and generates tactical messages for transmission in accordance with the unit ’ s national requirements . If Link 22 is to be added to an existing operator interface or TDS , it may be possible to incorporate the Link 22 TDS / DLP functions within the existing system ; otherwise , a new processor will be required to run the functions . However , if the existing system has spare link interfaces , it may be possible to connect Link 22 to the existing system using a spare link interface . In this case , a gateway system that converts from the existing link format to Link 22 would need to be purchased . SNC Processor Hardware . The SNC software requires a computer processor to execute the code . This would usually be Personal Computer ( PC ) type hardware , either running Windows XP or Linux operating systems . The SNC software is written in Ada 95 and is easily portable to other platforms as long as there is an Ada 95 compliant compiler available on the platform . The computer does not require significant processor power and any available current technology processor is sufficient . As a guide , a 1 GHz processor with one GByte of memory is more than adequate . The processor needs to support at least one Ethernet connection ( preferably 100 Mbit / s ) but , depending on the configuration , two may be required . The processor requires some storage for the operating system , the SNC executable and the TOD interface software . Possible configurations include a VME backplane enclosure with power supply and a VME processor card , or a rack mountable industrial PC . Link - Level COMSEC ( LLC ) . A single LLC can handle multiple networks depending on the type of media . The system can use a maximum of four LLCs which would be one LLC per network , but this would be an unusual configuration . A typical system will employ one LLC when up to four HF , or two UHF or one UHF and three HF networks are deployed . If more than two UHF Networks are deployed , two LLCs are needed . Associated with the LLC and its key loading , a Data Terminal Device ( DTD ) , which is used to load the keys into the LLC , would need to be acquired from the national crypto agency . Depending on the method of key distribution employed , a paper tape reader KOI - 18 may also be required . It is possible to distribute encrypted keys as PC files , in which case a special serial cable would be required to load the file from a PC into the DTD . The current LLC is a 19 ” rack mountable unit . The manufacturer refers to the LLC as the KIV - 21 / LLC . Signal Processing Controller ( SPC ) . An SPC is required for each network / media that the unit is required to operate on . A single SPC may be configured to use different media . An SPC hardware unit may contain more than one SPC . At the time this book was written , there were three manufacturers of SPCs , which all supported HF and UHF Fixed Frequency media . Frequency hopping media is also supported either within a separate SPC or embedded within a frequency hopping radio . The fixed frequency HF and UHF SPCs were available in 19 ” rack mountable chassis , with two of them containing VME cards which could be mounted in a suitably configured VME backplane . Radio frequency and power control by the SPC is optional . Refer to the SPC manufacturers ’ specifications to determine the options that are available with the supported radios . Radio System . The appropriate radio system is required for each of the media types that will be used , and consists of the following . The radio , power amplifier and power supply may be a single unit depending on the output power required . The higher the output power the more likely that separate units will be needed . One of the goals of the NILE program was to be able to reuse existing modern Link 11 radios and antennas equipment . If they are any available this would reduces the equipment that must be acquired . Time Of Day ( TOD ) Source . Link 22 needs to be supplied with coordinated universal time ( UTC ) which , if not already available on the platform , must be acquired . The TOD must be supplied to the DLP , SNC , SPCs and frequency hopping radios , if equipped . The recommended TOD input to the SPCs is the Extended Have Quick format as defined in STANAG 4430 . The SNC is delivered with a separate application ( Read TOD ) that accepts a Brandywine Serial 485 and 1 pulse per second ( pps ) input in compliance with STANAG 4430 For details visit www . brandywinecomm . com The Read TOD can be customized to supply the SNC with the appropriate time as detailed in section 3 of the [ NRS IDD ] . The TDS may also require an accurate time to guarantee synchronization among all the subsystems . If a more accurate source is not available , the Global Positioning System ( GPS ) may be used . GPS - based TOD hardware normally consists of the following : Connecting Cables and Equipment . The equipment needs to be housed in suitable enclosures appropriate to the environment in which the equipment is to be installed . Whether installed in single or multiple enclosures will depend on the site and the way that communications equipment is usually configured on that platform . Each set of equipment will require power and appropriate allowance for cooling . The components of the Link 22 architecture have to be inter - connected via appropriate cabling and communications devices . The DLP - to - SNC interface and the SNC - to - LLC interface both use Transmission Control Protocol / Internet Protocol ( TCP / IP ) . If TCP / IP is communicating within a processor , no cabling is required for the interface , which would be the case if the DLP and SNC were running on the same processor . When on separate equipment or processors , TCP / IP can use many types of network interfaces . The LLC interface uses Ethernet and so the SNC - to - LLC interface has to be Ethernet . Two Ethernet ports can be joined together with a simple cross - over Ethernet cable ( point - to - point ) , or joined together using an Ethernet hub or switch . The use of an Ethernet hub is recommended to allow for monitoring of the interface . If the SNC host processor only has one Ethernet port then a single hub could be used for both the DLP - to - SNC and the one or more SNC - to - LLC interfaces . The LLC is connected to the SPC via RS - 422 serial cable . The SPC is connected to its radio via a media specific interface , and is a national responsibility . It could even be implemented with the SPC being housed within the radio . Refer to the SPC and radio manufacturers ’ manuals for exact details of the interface . Spares . Logistics spares would also need to be acquired to provide an adequate level of cover in case of unit failure . The quantity and level of spares provided is a national responsibility and may vary depending on the platform , location and the number of operational units . Guidebook Chapter 2 : Link 22 Operations . Based on the technical aspects defined in STANAG 5522 and on the basis of operational procedures as defined in NATO document , Allied Data Publication [ ADatP - 33 ] this chapter is intended as a generic guideline for planners , operators and technicians uitlizing Link 22 in a single or a multiple link environment . National or platform specific procedures and operator actions are not covered in this guidebook . Guidebook Chapter 3 : Link 22 Technical . This chapter contains technical details of Link 22 , consisting of the architecture , functions , and protocols . It is primarily intended for integrators , software engineers and testers . Readers of this chapter are expected to have knowledge and understanding of the previous chapters , as this chapter will explain details without reiterating the higher level information already provided . This chapter will discuss non - tactical Link 22 features , functions , interfaces , and messages . The tactical messages were discussed in Chapter 2 Section D . Guidebook Appendices . Available for download at The Link 22 portal for Foreign Nations @ NILE Project Management Office .