An Adaptive Secure Channel Coding Scheme for Data Transmission over LEO Satellite Channels

Both secure and error control coding are very extensive subjects, each with a variety of subdisciplines. A secure channel coding (joint encryption-channel coding) scheme provides both data secrecy and data reliability in one process to combat problems in an insecure and unreliable channel. In this paper, a joint encryption-channel coding scheme is developed, based on concatenated turbo codes for more ecient and secure transmission of LEO satellite data. Reliability and security are achieved by adapting the pseudo-random puncturing strategy with a change of distance between satellites and ground stations in the communication seance, an issue further burdened by reducing energy consumption or increasing bit rate of data transmission. Simulation results show the relevance and superior performance of the proposed scheme compared with the traditional data transmission system.

Error control and security are both important aspects of modern digital communications and are often used together in one application. The demand for a reliable, secure and ecient digital data transmission system has been accelerated by the emergence of large-scale and high speed communication networks. In recent years, the use of small satellites in Low Earth Orbit (LEO) for remote sensing imagery has been extensive. Remote sensing imagery produces large amounts of data that often need to be secretly and reliably transmitted over a band-limited channel. In 1948, Shannon [1] demonstrated that errors induced by a noisy channel can b e reduced to a desired level by proper encoding of the information. Since Shannon’s work, a great deal of developments have contributed toward achieving data transmission reliability, so that the use of error control coding has become an integral part in the design of modern communication systems and digital computers. Forney [2] studied concatenated coding schemes as a class of codes whose probability of error decreased exponentially at rates less than the capacity, while decoding complexity increased only algebraically. Parallelconcatenated convolutional codes (turbo codes) introduced in [3] obtained remarkable coding gains close to theoretical limits, yet admitting a relatively simple iterative decoding technique. The recently proposed serial concatenation of interleaved codes may o er a superior performance to that of parallel concatenated codes [4]. In both schemes, the core of the iterative decoding structure is a Soft-Input Soft-Output (SISO) A Posteriori Probability (APP) module [5]. Adding security to channel coding is an attractive topic, as it could reduce the overall processing cost of providing secure encoded data. A secret channel coding scheme is one that provides both data secrecy and data reliability in one process, to deal with problems in an insecure and unreliable channel. Using error-correcting codes as cryptosystems was introduced by McEliece [6]. The McEliece proposal was to use a Goppa code as the underlying basis of an ingenious public-key scheme. The security of this scheme is based on the well known NP-completeness of the decoding problem for general linear codes [7] and the fact that there are a huge number of equivalent Goppa codes with a given set of parameters. Some other public-key cryptosystems, based on algebraic linear codes, are proposed in [8- 11]. It is well-known that public-key cryptosystems can b e used as private-key cryptosystems. Therefore, Rao and Nam [12] proposed a modi cation of the McEliece scheme and, subsequently, introduced

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