The use of Coding-Decoding Systems on Unmanned Aircraft with the Sensor Networks Operation
This paper is aimed at such an area of modern scientific interests as the use of sensor self-organizing networks in the scientific research fields, where it is necessary to rebuild the network quickly and correctly with the minimum power consumption. In particular, this article discusses the use of self-organizing sensor communication networks in building a communication channel between unmanned aircraft, and this communication channel protection carried out by means of bringing the digital data encryption algorithms into the existing protection system.
Materials and Methods.
The unmanned aircraft, which will be used, mainly, to create the closest flying fragment to the earth surface and, in some cases, the only such flying fragment, have very limited possibilities in terms of flying length. So, selection of a rational information collection route appears to be of primary importance. The first results show that to solve this problem, it is reasonable to use the traveling salesman problem solving methods, which, of course, is connected to many calculations. Real-time receiving of information from the aircraft is of great importance too. So, it is impossible to just refuse to transmit the information during the flight, but it is necessary to protect the data transmission channel and the data itself against an unauthorized access in the best way, which would meet all the safety and productivity requirements. This paper implies that at present the unmanned aircraft – the base communication channel uses such protection ways as a periodical pseudorandom operational frequency readjustment, an operational frequency readjustment in the event of communication loss, and the automatic unmanned aircraft landing in the event of a long communication interruption.
The tests estimated the erroneous decisions frequency Pλ for various λi, when i=(1.7) ̅, with different Eb /N0 ratios. By carrying out the experiment it was found out that it is reasonable to use estimations from λ4 value to λ7 value to form the equivalent code combinations. It is necessary to use the decoding algorithm starting with 4 dB to reduce the risks. For that end short codes are the best to use. When the noise ratios are lower, it is necessary to use the data repeat or the code composition. In the general case, the permutation decoding is able to heighten an effect of the batteries power conservation and the wireless sensor networks safety.
When writing this article the authors set themselves the following tasks: selection of optimal ways of encrypting various data transmitted through a protected communication channel; development of an information system, which will use the selected methods to simulate the encrypted information transmission through the channel between the unmanned aircraft and the radio station. One of the most commonly used approaches in this case is the use of a technology of multiplexing of encoded orthogonal frequency-division multiplexing (OFDM), which has a high spectral efficiency and interference resistance. The communication system quality directly depends on the channel parameters estimation methods. If to compare the traditional wireless communication networks and the unmanned aircraft systems, then the radio communication channel in the unmanned aircraft system is notable for the high range and high speed of the unmanned aircraft flight, as there is a great difference between the signal arrival time and the high Doppler frequency shift, and with the Doppler frequency shift the frequency orthogonality is lost and the demodulation quality is lowered. This means that it is necessary to estimate the Doppler frequency shift influence on the information transmission efficiency between the unmanned aircraft and the ground control station with the use of OFDM.
The authors believe that currently there is a great deal of systems of the intelligence data transmission from the unmanned aircraft in real time. The following scheme is used in those systems: the operator sees a picture from the unmanned aircraft cameras practically without delays. Apart from that, complete independence allows the unmanned aircraft to accomplish military missions in the areas where electronic warfare systems operate.