Electronic Warfare A Concept of Operations

Transcription

1 SCI-185 ELECTRONIC WARFARE IN JOINT LITTORAL OPERATIONS Electronic Warfare A Concept of Operations Allan Roberts 23 March 2009

2 INTRODUCTION For the military, the unseen enemy is the radio spectrum. Unless armed forces have mastery of it, the battle is already lost whether that it is in combat terms, during an exercise or on a humanitarian operation. In all circumstances, effective, reliable communications are essential. This white paper, looking mainly at the armed services combat role, considers how that is achieved. ii

3 Table of Contents SCOPE NATO EW - THE OPERATIONAL ENVIRONMENT VISION Overall Goal Operational Environment SPECTRUM MANAGEMENT Background NATO Military Spectrum Management Structure and Organisations A CONOPS FOR THE LITTORAL ENVIRONMENT Introduction Characterising Potential Enemy Locations Characterising Enemy Equipment Determining Optimum Sensor Locations Setting up Communications Deploying a Jammer Conclusion THE ROLE OF COMMUNICATIONS IN EW OPS Intercept, DF and Jamming Mission Planning Static Scenario Dynamic Scenario THE LITTORAL ENVIRONMENT CONSIDERATIONS Propagation The Fighting Environment Equipment Compatibility and Spectrum Management BIBLIOGRAPHY iii

4 SCOPE Electronic Warfare a Concept of Operations EW Concept of Operations (CONOPS) caters for the full range and intensity of combined joint military operations including peacetime, humanitarian operations, and warfare. This paper will concentrate on the warfare segment utilising spectrum in the possible frequency range 9kHz to 400GHz. The paper will remind the reader of NATOs EW operational environment vision, how it conducts electromagnetic spectrum management and will concentrate on a particular scenario and modelling tool to demonstrate a suggested CONOPS. It will conclude by identifying some of the issues and constraints on using the littoral environment for EW operations. 1-1

5 Electronic Warfare a Concept of Operations NATO EW - THE OPERATIONAL ENVIRONMENT VISION Overall Goal The headline vision for the transformation of NATO EW and related disciplines is: "Shaping and exploitation of the Electro-magnetic (EM) environment to provide shared situational awareness, communications, navigation and protection of joint forces and achievement of effects in support of joint objectives through military use of EM energy and dominance of the EM battlespace" Operational Environment Operational environments are places, tangible or intangible, that cut across all levels of warfare. They are the arenas where military operations and other military activities take place and where effects are achieved. Classically they comprise the geophysical environments of the sea, land and air/space. Now that the electromagnetic environment (EME) and the information environment are central to successful action military commanders must operate within them to achieve success. Actions take place in and between all these environments and information flows through them. These actions and information flows then exert influence in the cognitive domain, i.e. in the minds of adversaries, affected population and own military forces. This is a separate domain because unlike the operational environments actions cannot directly take place within it, an important distinction and planning consideration. This broader view represents a necessary challenge which is increasingly recognised by military leaders and thinkers. The classical geophysical dimensions of the battlespace are where traditional warfare has been waged and with which commanders and their forces are most familiar, being trained from the beginning of their careers. In more recent conflicts - where ideas and perceptions prevail, the simple military exploitation of the battlespace can look increasingly clumsy and misplaced. Today, winning is very much about hearts, minds and perceptions. Today, success requires domination of the EME to ensure that military capability is applied judiciously. It requires domination of the information environment to ensure the dissemination, exploitation or denial of information. Ultimately, success requires domination of the cognitive domain because it is here that the comprehension of victory or defeat rests. b. Figure 1 shows how these environments overlap and interact with each other and how effects usually rely on this interplay. 2-1

6 Electromagnetic Air/Space Land Maritime Cognitive Domain Information Action or Information Flow Influence Figure 1: The Operational Environments (Note that the intention is to show the constant flow of information and activities among environments with the intention of influencing change) c. The EME bridges the maritime, land, air/space and information environments. Success in the EME is often a precursor to success in the other environments. Indeed, success in the EME may itself be sufficient to achieve a desired effect. EW is the sum of all defensive and offensive measures that directly take place in the EME. Along with Communications, most Navigations and Intelligence, Surveillance, target Acquisition and Reconnaissance (ISTAR) and management functions these constitute EM operations (EMO). The goal is for fully integrated, effects-based operations with EM aspects and effects to be considered from the start. The aim is to be able to dominate those elements of the EM spectrum required at the time and space required for any particular NATO operation. In terms of an effects based approach to manoeuvre, like the other environments, the EME can be exploited, shaped and used for attack and/or defence. 2-2

7 SPECTRUM MANAGEMENT Electronic Warfare a Concept of Operations Background The Electromagnetic Spectrum (EMS) is widely used on military operations. Competing demands need to be strictly coordinated and controlled. Battlespace Spectrum Management (BSM) can be defined as the planning, coordination and management of the EMS through operational, engineering and administrative procedures; it enables military electronic systems to perform their functions within intended environments without causing or suffering harmful interference. BSM is primarily a J3/5 function although the detailed management of the EMS is often delegated to J6. Managing the EMS presents some unique challenges, as it cannot be defined in physical terms. Efficient use of the EMS provides an operational advantage in the Combined Joint Task Force (CJTF) and enables optimum spectrum use through deconfliction, protection, exploitation and denial of this valuable resource within the Operations Area (OA). Without robust BSM procedures, however, electromagnetic interference is likely to occur with temporary or permanent loss of access to systems. Failure to implement proper BSM procedures is likely to hamper manoeuvre and reduce tempo; at worst, it could result in electronic fratricide. NATO Military Spectrum Management Structure and Organisations For all types of deployment NATO Spectrum Management Offices (SMOs) will control all spectrum usage. The SMOs were introduced into the NATO Command Structure in 1997 as a consequence of the introduction of the CJTF Concept and in order to better support non-article 5 operations. This form of organisation provides the foundational structure for co-ordination and management of frequencies and the entire radio-frequency spectrum, and is now part of all NATO planning and operations, to include Article 5 and non-article 5 activities. Management of the spectrum follows the NATO Command and Control (C2) management process used for other activities and is based on the structure illustrated in Figure 2 below. HQ NATO NARFAs Strategic Strategic Commands (SCs) Operational Tactical Regional Commands (RCs) Joint Sub-Regional Commands (JRSCs) / Component Commands (CCs) Formation / Task Force / Air Operating Base / Combined Air Operations Centres (CAOCs) Combined Joint Task Force (CJTF) Unit / Ship / Air Squadron Figure 2: Generic NATO Command Structure 3-1

8 A NATO SMO daily co-ordinates and communicates with many diverse organisations and activities in order to fulfil its mission. These are summarised in Figure 3. It is important to note that just because an SMO has automated and interconnected capabilities that provide access to extensive databases of frequencies; this does not mean that the SMO necessarily has the authority to assign those frequencies. The SMO must co-ordinate frequency requests and receive permission from the appropriate Cognisant Assignment Authority (CAA) of a frequency before assigning it. In cases of operations where formal agreements have been established for an SMO to act as a CAA, they will do so to the full extent of the agreement, and other SMOs will co-ordinate with them for frequency requests within their area of responsibility. Requestor From/Co-ordinate With These Agencies Inform These Agencies As Needed National Civilian Assignment Authority Neighbour National Assignment Authority SHAPE & NACOSA (TACSAT) NATO HQ C3S SMB RC North RC South (TACSAT) RC North RC South Or SHAPE NATO HQ C3S SMB National Civilian Assignment Authority IO NGO PVO Neighbour National Assignment Authority SMO MOD HQ IO NGO PVO National Civilian Assignment Authority Frequency Requestors Inside the Country or AOR Ground Units Air Units Naval Units IO NGO PVO CAOC Units Deploying Into AOR National Command EUCOM etc Neighbour National Assignment Authority Frequency Requestors Outside the Country or AOR Figure 3: SM Relationships 3-2

9 Electronic Warfare a Concept of Operations A CONOPS FOR THE LITTORAL ENVIRONMENT Introduction Communications electronic warfare missions especially in the littoral environment require careful planning if the mission objectives are to be achieved in the optimum manner. The practical aspects that have to be addressed, which may include: Determination of optimum sensor location to maximise performance against enemy systems. This includes: o Characterisation of probable enemy locations and emitters o Determination of most advantageous propagation paths between emitter and sensor. o Identification of potential sensor sites from propagation analysis. o Selection of best practical sites from the candidate list when considering practical aspects such as vehicular access, type of ground and operational constraints. Assessment of likely mission success probability given the proposed sensor baseline. Re-working the solution if mission success probability is too low. Planning communications between distributed sensors deployed (direct links or via relays). Once enemy links have been identified, it may be desirable to deploy a jammer, in which case the optimum location for it has to be established in the same way as for the sensors. These tasks can be individually demanding, but not only that; what is best for one may not be best for the other aspects; some trade-off is usually required. This makes the overall task even more complex. In the past, these have often been completed manually, based on the operators' training and experience. However, given the complexity of modern systems and the diverse nature of modern operating environments, this approach will normally lead to sub-optimum solutions. However, modern software systems 1 can provide analysis and decision support via modelling on mission planning tools deployed on the battlefield. This section illustrates some of the methods that can be used. To simplify description, necessary tasks have been broken down into the individual steps of: Characterising potential enemy locations. Characterising enemy equipment. Determining optimum sensor locations. Setting up communications. Deploying a jammer. 1 Modelling software used for representating ideas in this section is HTZ Warfare from ATDI Ltd. 4-1

10 Characterising Potential Enemy Locations To illustrate the methods that can be used, a hypothetical exercise will be used, based on the real locations shown in Figure 4. Figure 4: The hypothetical exercise area SW Scotland and N Ireland in the UK One of the first tasks for an unfamiliar operational area is to get a feel for the lie of the land. This can be achieved by reading the contours from a paper map, but a pseudo-3d representation is often more revealing as shown in Figure 5. Figure 5: 3D image of operational terrain 4-2

11 This helps us establish that the area is primarily rural (few towns and no large ones) and is fairly hilly, with a series of ridges running north to south. This knowledge may prove useful later during the exercise. Now let's say that we have knowledge of the enemies' likely operating areas. These will have been derived from intelligence or other methods. Once they and other operational limits are known they can be entered into the planning tool, both for display purposes and also for further processing later in the process. Figure 6: Operational boundaries Figure 6 shows a simple example of this. More refined methods allow the operator to prioritise specific areas rating them relative to one another; thus, in some circumstances it may be that the enemy will be either in built up areas or on roads with a 70% chance of being in the urban environment and a 30% chance of being in the road environment. In general, the better we can characterise enemy disposition, the better planning we can do. Figure 6 has been created using a common set of vector drawing tools within HTZ Warfare. Characterising Enemy Equipment As well as characterising enemy disposition, we also need to characterise the equipment they are using. Some of this may be based on established knowledge and some will be based on estimates, but even with the most rudimentary information, it is possible to start 4-3

12 adding some basic characteristics to the modelling. All this will undoubtedly depend on a specific situation, but if we were to assume that it is known that the enemy are using VHF portable and mobile radios, then we can make some basic assumptions, such as: We can assume that they will be using power levels typical of such kit. We can calculate the expected sensitivity of the receiver based on physics and thus we can determine an approximate link budget for their radio links. We can assume that the portables will most often be used at metres above local ground height. We can assume that mobiles will typically be at approximately 2 metres above local ground. We can plan our system based on the assumption that they are using the highest frequency their equipment is capable of; in propagation terms, this is the worst case scenario. Once we have deployed an initial baseline and acquired new data, we can then refine the estimates further, but this basic information will allow us to proceed at present. Determining Optimum Sensor Locations Now that we have some appreciation of where the enemy are and the equipment we believe they are using, we can start to think about assessing the best locations for our sensors. If we assume our equipment is a combined detection / Direction Finding (DF) system, we can enter that into the planning system, typically in the way shown below. Figure 7: Basic parameters for a detection / DF system Now, the task is to position the minimum number of sensors to provide the best coverage of the target areas. In this example, we will start by examining the best places to detect the enemy wherever he is within the search area. This is likely to be somewhere within or 4-4

13 around the stripped polygon shown in blue in Figure 8, but we need to refine the best locations further. Figure 8: Likely location for a detection sensor within the scope of the exercise We can do this by performing multiple simulations, each one placing enemy transmissions randomly within the enemy area and then collating the results to show which potential locations within our own allowed area are best. It is important to ensure that the random locations properly reflect the entire enemy area; otherwise the results will be skewed. The number of samples to achieve this can be determined using standard statistics. Figure 9: Searching for optimum sites A typical result is shown in Figure 9. The different colours represent the relative quality of all areas within the allowed sensor deployment area. The generally 'hotter' colours represent the better areas for deployment as indicated by the key, although the planning tool can also give a numerical metric to allow fine selection. Once the general simulation 4-5

14 has been conducted, the operator may focus on a particular area to identify both technical and tactical site considerations. This same approach can be performed for the other two enemy areas (in fact it is also possible to perform a prediction combining all three in one step). From this, an initial detection sensor baseline can be established, as shown in Figure 10, where the blue circles show the detection/df sensors and command post locations. Figure 10: Selected baseline following search analysis Next, we can check the performance of the system against the specified target transmission originating from within the target areas. This is illustrated in Figure 11, which shows expected detection probability in a traffic light scheme (green = good, yellow = fair, red = poor). The thresholds can be set by the operator, and in fact up to 11 separate levels can be set by the operator in the HTZ Warfare tool. 4-6

15 Figure 11: Detection probability shown in a traffic light scheme The deployed system is not only a detection network, but also a DF system. For this to be effective, we require hits from more than one DF preferably all three. Again, current mission planning tools can predict this. In Figure 12, the traffic light scheme is again used, with green = coverage by all three, yellow = only two of the three and red = only one of the three. Figure 12: DF coverage simultaneous coverage 4-7

16 This analysis can also be augmented by other simulations, designed to determine multipath vulnerability at the selected sensor site (which can adversely affect DF performance). We can also run a test of the sensor network performance by placing enemy emitters in the target areas and identifying the network performance against them, as shown in Figure 13. Figure 13: Test of the sensor network using randomly placed enemy emitters. If we assume that the sensor network in Figure 13 is acceptable, we next need to determine how to link the DF network sensors together via a communications network. Setting up Communications In this part we will only skim the surface of the communications requirements. The next section looks more closely at this very important issue. It is essential for the deployed elements to be able to quickly communicate DF hits to the other parts of the network. The potential for doing so can be established using standard link analysis, using the technical parameters for the radio links available to all the sensor deployments. Figure 14 shows that most sensors have a communications link back to HQ but HQ and sensors 1 and 2 do not. 4-8

17 Figure 14: Communications between sensors and HQ We now need to investigate other steps to establish communications, and again modern planning tools can assist in this as well. We will need to add a re-broadcast (re-bro) station, and we can determine the best location using the following method. Although the links between the sensors may be directional, we can for the moment assume they are omni-directional (this is not always true, but if the links are based on omni-directional antennas, this approach still works). This is equivalent to saying we know they are directional and will need to be aligned towards the other node, as yet we have not established which direction this is. Thus, if we do a complete coverage prediction sweep around both of the existing nodes, we can determine where a re-bro can be positioned such that it can communicate with each node. If we then overlap the coverage of both sensor predictions, we can then directly see where a re-bro can be positioned such that it can link to sensor locations and HQ simultaneously. We can then prove this by adding a re-bro and confirming that communications are indeed established. This is shown in Figure

18 Figure 15: A re-bro deployment 4-10

19 Deploying a Jammer Once DF hits start coming in and the enemy network becomes clear, it may be appropriate to deploy a communications jammer. In Figure 16, the red elements show enemy node approximate locations detected by the DF baseline. There may be other elements present, but these are the ones we are aware of. The thin blue lines between each node show which ones will be physically capable of communicating with one another. Figure 16: Detected enemy emitters From this data, it is possible to perform a type of 'reverse coverage' prediction from each of the known nodes and then collate the results to determine the best location within our restricted deployment area for positioning a jammer. This is illustrated in Figure

20 Figure 17: Jammer position searching From this, the same process as used for the positioning of DF sensors can be used for positioning the jammer. In Figure 18, a jammer location has been selected, its characteristics configured (e.g. power, antenna height, antenna characteristics) and immediately the impact on the enemy links can be seen by the black lines which terminate midway along the links that will be jammed (in blue). 4-12

21 Figure 18: A jammer deployed One question may be how much radio power do we need to apply in order to just jam all of the links? Again, the modern planning tool can help. The system can perform calculations to determine the minimum power necessary and provide the results as shown in Figure 19. In this case, a power of 50W and 25W (respectively) is necessary; this might be achieved by 5W of RF power and a 10 dbi antenna gain. 4-13

22 Figure 19: Minimum jammer power calculation Thus we have now completed the initial task to design a detection/df baseline and a jammer to counter enemy communications. This somewhat simple illustration shows the basic concepts of such an activity, which can be achieved in minutes or at worst a few hours. This is a considerable improvement on manual methods which may take many hours or days to complete and which will provide poorer results. Also, when (inevitably) things change, the same methods can be quickly used to re-configure the network to meet the new challenges. Conclusion This section has illustrated some relatively simple methods available in modern mission planning tools for communications electronic warfare operations. In fact, the methods described are the mere tip of the iceberg; products such as HTZ Warfare feature a far wider array of methods which are too complex to discuss in a short paper; these include jamming methods for frequency hopping and wideband systems. However, it is worth noting that unless the methods described accurately reflect real life, they are no more than pretty pictures and their benefit to commanders is less than useful. Thus, and planning tool has to have the following characteristics in order to be beneficial: The propagation models used must accurately reflect what actually happens in the real world. This will be dependent on frequency band and environment and different models will be required for urban warfighting, desert operations and for operations involving high-altitude aircraft, for example. The use of a rudimentary model to cover all of these situations is counter-productive and will lead to wrong results and wrong decisions. Also, models must be able to cope with abnormal conditions that may be encountered in practice. Propagation models must be validated for the specific application and verified against real data before operational use; no one model will suit all needs, and there is no excuse not to use state-of-the-art models. The modelling of the environment must be sufficient for the data input requirements of the prediction models. This will vary according to the methods used in each model. Thus sometimes it may be necessary to have data down to individual building level or less, whereas other times a coarser model is most appropriate; 4-14

23 excess data requires nugatory effort to acquire and too much time to process for no extra gain. This will include not only terrain but also at least radio clutter models including urbanisation, vegetation, water bodies and so on. The data used within the models must be appropriate to the modelling; this will vary according to the way each model works. Modelling of radio equipment must equally be of appropriate fidelity to the modelling methods used. Increasingly, this goes beyond the basics of the link budget values and also includes high-fidelity modelling of antenna characteristics (including modern adaptive antenna systems), system performance metrics and spectral characteristics so that the effects of jamming can be appropriately assessed. Also, for direction finding systems, sophisticated localisation methods are available. Equipment characteristics must be captured and expressed in order to get the best out of modern prediction techniques. As long as these criteria are achieved, modern communications electronic warfare mission planning tools offer a unique opportunity to improve system deployment, maximise the efficiency of each deployed element (in effect, act as an equipment force-multiplier) and to maximise the chance of mission success. 4-15

24 Electronic Warfare a Concept of Operations THE ROLE OF COMMUNICATIONS IN EW OPS Intercept, DF and Jamming As you read in the last section great importance is placed on the performance of radio intercept receivers, direction finders and communications jamming equipment, and rightly so. A key feature determining mission success, however, is the physics of terrestrial and low-altitude communications radio paths. It is this factor that dictates whether there will a successful intercept, DF or jam and whether information can be shared between sensor platforms and passed back to the rest of the Command structure. The first crucial aspect is positioning the sensor or jammer in such a way as to be able to find and exploit or attack the targets, whether their position is known explicitly or if only a general search area is known. This will depend on the sensitivity of the receiving sensor, the original transmit power, frequency and environment of the target and the nature of the radio path in between. This will be influenced by such factors as distance, terrain, and clutter such as vegetation and urbanization and for higher frequencies atmospheric effects such as precipitation. Where the target location and parameters are known, this scenario can be simulated and a locus of possible sensor or jammer locations can be determined. This is not the end of the story however. Along with successful positioning to attack or exploit the target, it is necessary to ensure that sensors and their platforms can be successfully controlled and for multiple platform systems, coordinated and also that information collected can be disseminated up the chain of command. In some cases this can be achieved by mobile line communications but in most cases on the modern battlefield this to must be achieved via radio communications. This gives us a secondary problem therefore; how to ensure that while sensors or jammers are in a viable location to get onto targets, they are concurrently in communication with each other and with the rest of the organizational structure. For given sensor or jammer locations, this gives us another locus of possible solutions that must overlap the first. Naturally, the communications EW planner has some control over sensor location, so the sensor location itself is a variable in this equation. It is easy to see that the situation rapidly becomes very complex and we are not finished bounding the problem yet. In very many circumstances, a communications EW mission will not happen in isolation but will have to live alongside other activities on the battlefield, each of them users of radio communications. Since inappropriate re-use of the same (or nearby) radio spectrum may cause interference to one or both parties, it is essential that coordination of spectral usage is carried out with respect to: Other J2/J3/J6 activities within the range that may affect radio performance The aims of individual communications EW missions (e.g. one unit does not jam an enemy frequency that is being successfully exploited by another) Enemy EW/communications EW activities Civil transmissions including safety critical such as aircraft beacons, but also normally covering TV and radio broadcast and other important services. A final aspect that can be important to some missions is to manage mission risk; in other words not placing sensor or jammer platforms in unacceptably dangerous locations either to physical harm or to mission failure due to enemy actions (e.g. jamming or counterexploitation). 5-1

25 Mission Planning It should by now be clear that successfully planning and coordinating modern communications EW missions is a major juggling act involving concurrent optimisation of assets by space and spectrum. This aspect although complex cannot be ignored - it is utterly essential to mission success. For modern mobile systems such as UAV mounted sensors, it becomes entirely critical not only to mission success but also to retrieving the air platform in fact, in the worse scenario, loss of communications to a UAV may cause the air vehicle itself to become a threat to safety. The elements of mission planning are shown below. Relaying Figure 20: Mission Planning Elements We can examine some of the aspects of mission planning in more depth for two distinct scenarios. The first is the largely static situation and later we will look at a more dynamic scenario. The differentiation between the two is that successive stages of a static scenario can be planned in depth individually, where the dynamic scenario calls for planning of a complete mission in one go. 5-2

26 Static Scenario A typical static scenario would be a deployment of terrestrial, probably vehicle mounted equipment. The main factors that can be modified by the planner are platform location and frequency bands used for inter-platform communications (where there is sufficient flexibility in the spectrum management plan to allow this). Figure 21: Static Scenario The principal weapon in the armoury of the static mission planner is the operational environment, and the principal methods are to exploit terrain and clutter. For enhancement in performance, high ground facing the target search area can be exploited. For managing the risk of interception, terrain and clutter shielding can be used. The reliability of inter-platform communications can be assessed using path prediction methods and, if necessary, relay stations can be used to improve communications links. Often in the static scenario, ranges both to other platforms and to the target are relatively short, even for HF but particularly for VHF and above. This can vary with the atmospheric conditions and the particular operational environment but typically ranges are of the order of tens of kilometres. This has some impact on the options available to the mission planner and coordinator. For a start, it is possible to arrange the design of the mission to achieve the objectives but minimise the impact on other activities by carefully positioning communications links, selecting appropriate frequencies and by the use of directional antennas for example. The importance of these measures is that interference effects to other missions can be minimised and frequencies can be re-used over relatively short distances. Optimal mission planning for multiple concurrent missions can be achieved using computer mission planning tools, thereby resulting in good use of the available radio spectrum and consequently a higher probability of achieving mission objectives. The computation time compared to deployment timescale is relatively short making this a viable option. 5-3

27 Dynamic Scenario The dynamic scenario can be characterised by a faster moving situation. This can be terrestrial systems but, increasingly, is more likely to be airborne such as an Unmanned Airborne Vehicle (UAV). A UAV fitted with a communications EW sensor or jammer has many advantages over its terrestrial counterpart. THREAT SEARCH GROUND CONTROL STATION Figure 22: Dynamic Scenario Firstly, increased speed over the ground means that the sensor can be on target long before a terrestrial platform arrives. Secondly, increased altitude of the sensor generally leads to enhanced detection and effectiveness range between sensor and target. Thirdly, for detection of unlocalised targets, UAVs can search an area rapidly. These benefits come at a price. UAVs are more vulnerable to enemy fire, have limited time on target and are costlier than terrestrial systems. Also, payload limitations restrict the systems that can be deployed in this manner. They also rely on communications, which can affect mission performance in a number of ways, including: Positioning the UAV in a location where it cannot receive control instructions, therefore increasing the risk of losing the vehicle and preventing achievement of mission goals Positioning the UAV in a location where sensor data cannot be relayed back to the Ground Control Station thereby preventing achievement of mission goals 5-4

28 Deliberate jamming of control and telemetry links by the enemy therefore increasing risk of losing the vehicle and preventing achievement of mission goals Inadvertent interference of control and telemetry links by friendly forces, including other UAV missions, again increasing risk of loss and preventing achievement of mission goals Inadvertent interference of control and telemetry links by neutral and civilian transmissions, increasing risk of loss and preventing achievement of mission goals Each of these situations affects the ability of the UAV system to achieve the desired goal and may jeopardise future missions if the airborne vehicle is lost. This is further complicated by the fact that, owing to the antennas on the UAV being high above the battlefield, the probability of interference from external sources is increased for a variety of reasons, including: Transmissions from other terrestrial and airborne sensors will probably travel further at the UAV altitude than they would at ground level. This increases received signal power and hence interference probability. Similarly, the effective range of enemy jammers is increased, whether they be ground or airborne Spectrum management systems for terrestrial systems will often not consider the effects of transmissions at higher altitudes, therefore coordination between terrestrial and airborne systems does not occur. With no management, it is impossible to take account of the possible interference effects. Signal strength will vary for airborne platforms more than for terrestrial systems, leading both to higher variation in control and telemetry links and to interfering signals. This makes interference prediction more difficult to achieve. Mitigating factors such as terrain and clutter shielding are far less likely to provide a solution particularly over a complete mission since the location of the UAV will change rapidly. It can be seen therefore that the management of dynamic scenarios is more complex than that of static situations. Also, if the situation is changing rapidly, computation of the possible variables to minimise interference is not possible within the time constraints. We can now compare and contrast mission planning methods for the static and dynamic scenarios and draw some conclusions. It is possible to distinguish between two types of mission planning, which I have characterised as pre-planning and planning. Pre-planning is essentially drawing up guidelines to be followed during the planning process and they can assist in putting together workable plans. The following actions may provide solutions. Action Static Dynamic Comments PRE-PLANNING PHASE Creating a de-conflicted frequency plan with non-reusable frequencies over the operational theatre Analysing existing spectrum occupancy in operational theatre to determine local usage and therefore eliminate potential interference by eliminating used frequencies from the frequency plan X X Minimises interference potential but reduces spectral efficiency. Computation time may be long but once calculated, can be used rapidly. X X Ideal, but usually difficult in practise due to lack of available information. Determination takes lots of effort and time and the situation may change through time. Drawing up guidelines on minimum X X Good practise, but again reduces 5-5

29 spatial and spectral distance for concurrent missions Action Static Dynamic Comments spectral efficiency. Once established, can be used by experienced operators. PLANNING PHASE Use of de-conflicted frequency plan X X Again, minimum risk but also minimum spectral efficiency. Can be achieved quickly. Use of guidelines for spatial and spectral coordination Modelling of mission to determine interference likelihood from known deployments, enemy and civil activities (based on distance) Use of antenna height minimisation for communications, maximisation for sensors X X As above X X But more difficult and risky for UAV systems. Generally short prediction timescales but answer needs to build in sufficient safety margin to be used effectively. X X Limited potential for UAV due to need to maintain contact with GCS and also antennas are co-located. Optimisation requires fairly detailed modelling and may take some time. Use of terrain and clutter shielding X Generally of limited benefit to UAV systems. Calculation time can be lengthy but still fine for static deployments. Detailed interference prediction using modelling techniques using terrain and clutter and advanced propagation models Use of directional antennas for communications links Use of advanced interference prediction techniques involving all of the above to determine level of interference throughout battlespace Use of advanced automatic frequency assignment techniques to use above interference prediction to design spectrum usage. X X X X Generally too risky for UAV operation since not all information will be available. Again, calculation times more suited to the static situation. Technically difficult in UAV but has been tried. Computation time short if terminal locations known. Variability of signal strength at UAV altitudes generally precludes this method. Advanced and detailed computer models required, which take significant time. Still OK for the static situation however. As above The layout of the table is such that in general the action further down the table will result in the better solution in terms of spectral efficiency and probability of mission success. This leads to the following general conclusion. For static and terrestrially-based scenarios, the use of detailed computer models provides the best solution, especially where there is sufficient detail of information available to allow the use of terrain shielding, antenna height optimisation and directional antennas. If this information is available, it is practical to generate a detailed plan with high spectral efficiency and one that can be updated for evolving situations within the required time frame. For dynamic scenarios, the variability of signal strength, high probability of the existence of interfering signals due to relatively long propagation paths and the reduction of time to compute solutions imply that pre-planning is generally more important as a mission 5-6

30 planning methodology. Some simulations can be carried out once the mission aims are known, but the required resilience of communications links mitigates against attempting a spectrally efficient solution. In most cases, in fact, it will probably be necessary to reserve sufficient spectrum for the required UAV missions, not to be used by other applications. 5-7

31 Electronic Warfare a Concept of Operations THE LITTORAL ENVIRONMENT CONSIDERATIONS The preceding sections outlined an EW CONOPS (from a software modelling tools viewpoint) and its communication considerations that, whilst not specific to the littoral environment, can equally be attributable in that environment. Propagation The littoral environment is undoubtedly a challenging one, with extreme factors such as heat and wave energy that must be handled with due consideration. The transition from one regime (sea) to another (land) can result in variable propagation conditions which will affect all EW sensors and systems. In today s war zones concentrating in the warmer climates this can be very pronounced. The problems in this environment can in some ways be overcome by using platforms high above the ground/sea where propagation conditions become more stable. This does however carry the risk of counter-detection. In areas where there are extreme tidal variations, planning is difficult particularly for highly directional links due to the main reflection point changing due to tide height. The Fighting Environment The costal environment is more dangerous for aircraft than the open seas because of the threat of attack from ground systems. Aircraft which, at sea, would fly at very low level to avoid naval radar, would need instead to fly high to avoid ground fire. In terms of disembarking or embarking troops for a landing, this represents a very difficult time for naval vessels. It puts them in a vulnerable position, having to stay fairly static and not having freedom to manoeuvre to fight the enemy. In this situation force protection measures must be at their best to combat potential enemy activity. In operational terms, it is a dangerous environment for ships because modern diesel submarines have the operational advantage; the variations in sea propagation of sound is also very variable and a high level of background noise due to wave action. This masks the (low) levels of noise radiated by the submarine. Also, the threat from missiles and gun fire from shore-based systems are increased for a number of reasons. Firstly, anti-ship missiles can be fired from coastal batteries giving little time for ship defence systems (including EW) to react. Secondly, it brings the ship into range of less potent but more prevalent systems such as RPGs and heavy machine guns. These can be launched from the shore or from small boats, which can often hide amongst legitimate fishing and commercial vessels. These weapons are generally immune from EW detection or counter. The risk of airborne attack is also higher for a number of reasons. Firstly, there may be legitimate commercial routes all around the operational area and there may be legitimate light aircraft at lower levels. Combatants, including potentially suicide light aircraft can hide among this traffic until the last second, again reducing reaction time. Equipment Compatibility and Spectrum Management Tri-service equipment may not be compatible in all cases, and demands on spectrum may effectively be tripled above that for a single-service operation (this is generalisation of the worst case situation). This makes spectrum management and communications planning more complex. This can be overcome by proper planning using systems capable of 6-1

32 modelling the spectrum demand and the spectrum availability given the constraints of the operational environment. However, it is important to point out that this planning is not trivial and must be given proper consideration. Time-based spectrum management that allows spectrum to be consumed for an operation and then released following completion of the operation is likely to be key for future operations. This may imply that some services are denied operational spectrum for a period (including EW). The risks of this must be balanced against the requirements. This implies that the management system must be capable of modelling, managing and disseminating frequency plans dynamically. This is not typically true today and it represents a significant capability enhancement to most NATO nations, if not all. EW operations will be complicated by the presence of both maritime and terrestrial civilian traffic. It may well be an operational requirement not to interfere with these systems. Enemy combatants will use this to their advantage, which complicates the EW situation. Additionally, enemy combatants may use commercial radios with identical characteristics to legitimate users, which means that EW needs to cover a wider range of frequency bands, both military and civil. In any case, the task of filtering operationally important from non-important traffic will be more complex in this environment. 6-2

33 Electronic Warfare a Concept of Operations BIBLIOGRAPHY Godderij, P (NLDAF) Military Committee Transformation Concept for Future NATO Electronic Warfare. (MCM ) Brussels: North Atlantic Military Committee McTeague, R ACP 190 (B). Washington: Combined Communication-Electronics Board Graham, A The Application of Modern Communications Electronic Warfare Mission Planning Support Tools in the Battlespace [Internet] Crawley: E-paper (Published 2007) Available at: 20Planning%20Support%20Tools.pdf [Accessed 4 February 2009]. Graham, A. Kirkman, N. & Paul, P Mobile Radio Network Design in the VHF and UHF Bands. Chichester: John Wiley & Sons Ltd. 7-1