The paper presents a construction of a wireless hybrid data link operates applying two transmission channels using optical radiation (FSO – Free Space Optics) and radio one (RF - Radio Frequency). Based on some parameters (e.g. laser power, optics aperture, photodetector detectivity, signal bandwidth, beam divergence) of the link components, its data range was determined for various operating conditions (visibility and turbulence). Preliminary tests of the link prototype (TRL 6) were carried out at the Military Communication Institute, Poland. The results showed that the use of FSO/RF technology systems can provide the increase in data transmission security, link availability, and immunity to intentional interference. Considering the features of this technology, high applicable potential to military activities was observed.
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 sophisticated military command and control systems causes the dynamic demand for broadband services including the transmission of video in real time by using telecommunications links. One way to resolve the problem of limited bandwidth in used military wireless systems is to use modern broadband radio stations. Broadband radio stations in addition to undoubted advantages such as increased system bandwidth, have also some limitations – in comparison to narrowband radios, broadband radios offer a smaller range and work in a wide band and high transmitter activity associated with the generation of maintenance traffic, which makes it easier to detect radio emission by the opponent. Modern electronic warfare systems can track down such systems and overpower them. That is why one of the main tasks, which currently are facing designers of advanced broadband radio communication systems, is to develop mechanisms to immunize broadband radio stations on the targeted interference. In this article the method of implementation of the national waveform allowing for securing the transmission in broadband radio stations will be presented. Transmission modes of the radio station (TDMA, CSMA/SC, CSMA/MC) will be discussed considering advantages and disadvantages of each of the above-mentioned modes of operation. In the next chapter selected results of experimental studies of broadband radio station R-450C with the above-mentioned implemented operating modes and universal defeat device for generation of diverse broadband interference will be presented. The obtained results will allow to assess the implemented modes of radio stations for resistances of broadband radio communication system on selected targeted interference. The developed analysis and obtained measurement results may be helpful both for people organizing radio communication using broadband radios as well as for those responsible for the proper operation of electronic warfare systems.
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.
One of the main concerns of the institutions dealing with the spectrum management as well as persons responsible for radio networks planning is the lack of electromagnetic resources. This is caused by various reasons. On the one hand, there is a very rapid increase in the number of radios used in modern military platforms. Another factor connected with it is the fact that modern radio communications systems, in order to meet the users’ requirements, e.g. to be able to transmit video streaming in a real time, need wideband transmission channels. On the other hand, current static methods cause substantially suboptimal spectrum management. An average level of the spectrum resources utilization in a frequency band from 30 MHz to 2000 MHz very rarely exceeds 15%. Contemporary tools for frequency planning use so called Interference Conflict Margin (ICM). It is a measure of the protection against interference from potentially disrupting transmitter at receiver side. But ICM do not take into account features of the modern radios which have anti-interference mechanisms implemented. Since modern radios adjust modulation and coding schemes to the current state of the radio channel, these features should be taken into account. The same applies to the range of the network and level of power necessary to maintain communications. In this point, the protection criterion should be defined similarly to the protection ratio in ITU-R BT.1368, ITU-R P.372-9 documents. Another important factor is to take into account the way how considered radio network works. Is there only voice communications or data? In the second case, it is also important to determine the minimum transmission rate. In this paper a more flexible approach is presented. Adaptive modulation and coding schemes as well as power levels are taken into account. Presented results of experiments and simulations show benefits arising from proposed approach.
Military wireless communication systems provide services using radio transmission technologies. However, this technology is exposed to modern radio-electronic warfare devices. In some operational scenarios, an application of laser data link (Free Space Optics - FSO) makes it possible to increase data transmission reliability and security. Such capability could be obtain using so-called hybrid FSO/RF communication system. The development of optoelectronic devices (lasers and photodetectors) operated in the spectral range of 8 – 12 μm (Long Wavelength Infrared Radiation - LWIR) enabled to construct a new FSO link. Compared to currently used FSO systems operating in 700-900 nm (NIR) or 1300 – 1550 nm (SWIR) spectral ranges, this link is characterized by less sensitivity to atmospheric phenomena (fog, mists or turbulences) and by greater difficulty of detection. The performed analyses shown that the use of FSO/RF technology systems can provide increase in data transmission security, link availability, secretiveness of operation, and immunity to intentional interference. The paper presents virtues of some wireless communication technologies based on radio, optical and hybrid system configuration. The status of the research on FSO link operated at LWIR wavelength range is also described. This study has been performed in the frame of LasBITer project financed by The Polish National Center of Research and Development. The developed optical data link is a unique device in relation to the FSO technologies available today, because of its operation in LWIR spectrum using quantum cascade lasers and HgCdTe detectors. Scenario of FSO/RF data link works in military operation is also presented.
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.
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.