KEYWORDS: Receivers, Transmitters, Telecommunications, RF communications, Radio propagation, Systems modeling, Antennas, Warfare, Wave propagation, Signal to noise ratio
An important problem that persons responsible for radio communication systems face is how to make these systems immune to jamming. Rapid development of contemporary electronic warfare systems is a reason why that task is difficult to solve without special supporting tools to analyze wave propagation. Currently, an attempt to jam an enemy radio network is a multiphase process for which the most crucially important is collection of information on the enemy radio communication system and then processing it. The results of the analysis enable to estimate efficiency of intended jamming activity and make the decision on emission of jamming signals. The tools that are useful for estimation of the possibility to jam selected radio objects are wave propagation prediction models chosen earlier in the phase of operational and technical analysis. A good example of propagation prediction model of HF waves is the model based on ITU-R P.533-13 recommendation. It is distributed as a free of charge dynamic linked library P533.dll.
The article presents the proposal of implementing the P533.dll library in order to increase the effectiveness of HF radio communication systems jamming. The information in this article may be useful for those who deal with HF radio communication and for those responsible for the operation of electronic warfare systems.
Modern systems of radio communication planning have two aims: ensuring both internal and external compatibility of the system (i.e. avoiding both interference within the network and jamming or interference by other sources). Currently, systems of planning concentrate only on ensuring internal compatibility of the radio system and avoiding usual interference from external sources. The part of ensuring external compatibility of the radio system related to avoiding jamming was carried out by using appropriate mode of radios, ex. frequency hopping mode, free channel search mode, etc. With this approach, we had no information about efficiency of the methods used. In particular, we had no information whether we have made the radio nets immune to jamming. We present a model of planning frequency assignment by a mobile military communication network taking into account not only internal interference of planner's own system but also potential presence of a rational opponent.
To do this, we use dynamic games with incomplete information and the concepts of belief distorted Nash equilibria, both in deterministic and stochastic form of expectations. This analysis allows us to find remedies to several types of behaviour of the opponent. From theoretical point of view, in existing approaches, the problems of frequency assignment for a mobile military communication network in various time instants are treated as independent static optimization problems with only one decision maker. First of all, we have to be conscious, that we face not a simple optimization problem, but a game: besides our communication network, there may be an opponent, whose aim is to detect and/or jam our transmission. Besides, a dynamic character of interaction has to be taken into account: using a plan of frequencies defined a priori and switching to the same reserve plans in predetermined way whenever jamming appears, makes it possible for the counteracting unit of the opponent to uncover the rules of our behaviour. Using dynamic game theory, in particular dynamic games with incomplete information, allows us to utilize information about rules of behaviour of the opponent during the process of frequency planning. The side which takes the dynamic character of the decision making problem into account as the first can benefit from this fact.
The rapid development of systems which use wireless technologies causes the escalation of the spectrum shortage problem. That is why the concept of coordinated dynamic spectrum management has appeared. It improves efficiency of the spectrum use and makes radio communication systems more resistant to interferences. The main element of the proposed solution is a frequency broker which provides frequency assignment plans for radio networks. Direct communication between the frequency broker and radio networks enables fast change of radio data. This paper presents an anti-interference method based on dynamic spectrum management, which is an implementation and extension of IST- 104/RTG-050 research task group “Cognitive Radio in NATO II” recommendations. The solution presented by the authors was tested in emulated and real environment. The designed algorithm of frequency assignment can effectively prevent interferences (including jamming) thanks to the implementation of monitoring mechanisms capable of obtaining information about the current state of radio channels from radio networks. Directions for further development of frequency planning algorithm based on belief distorted Nash equilibria for deterministic or stochastic beliefs were proposed.
KEYWORDS: Modulation, Computer security, Quadrature amplitude modulation, Telecommunications, Cryptography, Signal processing, Antennas, Defense and security, RF communications, Control systems
Rapid development of advanced military command and control systems results in a dynamic growth in demand for data rate. One of the methods that make it possible to deal with the problem of limited capacity of military wireless systems is the use of broadband radios. Another one is the increase in the capacity of narrowband radios by implementing advanced modulation systems. Apart from remarkable benefits, such as the increase in system bit rate, there are also certain limitations since such radios are more sensitive to radio-electronic countermeasures, and the operation in the broad band makes it easier for the enemy to detect the radio emission. In such a situation, it is essential to define again and implement the transmission security functions into modern radios consistently. In this article, some current NATO activities are discussed, regarding the definitions of transmission security functions and the way of implementing them in radios, while paying special attention to a new element, that is to AIE radio cryptography (On Air Encryption). In the paper, the authors present an exemplary implementation of the functions in the Cognitive Radio Demonstrator using R-450C radio, the results of the examinations as well as the conclusions.
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