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New spectrally and energy-efficient signal-code construction (SCC) based on Index Modulation aided OFDM and Space-Time Block Coding, and also its noise-immune version in phase instability conditions with Inter-Channel Interference compensation operator, built intoAlamouti's coder structure, and increasing signals frequency diversity operator (Walsh-Hadamard) are proposed. In a complicated interference environment, first of all, under the influence of electronic suppression means, such methods increase simultaneously the data rate and reliability of digital information transmission. The SCCs enhance the noise immunity of the new generation wireless systems, as well as modern wireless communication networks of special purpose, which require high-quality implementation of bulky multimedia applications with high energy efficiency, in conditions of limited energy resources with spectral efficiency up to 4 bits/s/Hz. Using two transmit and no more than a pair of receive antennas guarantees the minimum weight-dimensional characteristics of mobile stations while providing the necessary level of antenna space decorrelation. The highest informational efficiency of such methods is achieved by applying reference look-up tables for short subblocks and small signal constellations, which allows the practical implementation of an optimal Maximum Likelihood Detector based on modern digital signal processors.Електронне наукове фахове виданняжурнал «Проблеми телекомунікацій»• № 1 (24) • 2019 • http://pt.nure.ua

No abstract

Wireless communication systems are considered, the main task of which is to increase their spectral (SE) and energy efficiency (EE) in conditions of limited frequency and energy resources. Additional use of the spatial resource based on flexible and universal methods of signals Space-Time Coding (STC) in MIMO-systems (Multiple Input - Multiple Output) can significantly increase the SE and EE values, as well as significantly improve the capabilities and conditions for EE exchange on SE. The advantages and disadvantages of Orthogonal Space-Time Block Coding (OSTBC) and Non-Orthogonal STBC (NOSTBC) are shown. Two main methods of synthesis of spectrally and energy-efficient information transmission methods are demonstrated. The first method is implemented by creating Perfect-codes that simultaneously achieve maximum diversity and multiplexing gains. The exponential computational decoding complexity of such codes makes it impossible for their practical implementation in mobile terminals at the present stage of development of circuitry. The second method of synthesis is based on improving the simple basic STC methods in terms of increasing the SE and EE by creating Signal-Code Constructions (SCC), which have the advantages of the basic STC methods and are devoid of the disadvantages inherent in Perfect-codes. A technique for the synthesis of SCC is proposed, the essence of which is to determine the priority areas (by the value of the Signal-to-Noise Ratio (SNR)) of using the STC and corresponding signal constellations, which provide the maximum SE for a guaranteed Bit Error Rate (BER). It was found that MIMO 2x2 with Alamouti OSTBC has an advantage in terms of EE over NOSTBC type VBLAST for SE not more than 8 b/s/Hz and SNR under 35 dB, BER not exceeding 10-5. In MIMO 4x4, OSTBC codes are inferior to NOSTBC in terms of EE. VBLAST code allows to provide SE 4 - 8 b/s/Hz at SNR 10 - 20 dB, BER not exceeding 10-5. Based on the results obtained, propositions for further improvement of OSTBC and NOSTBC are formulated.

Розглянуто сумісне застосування ортогонально-частотного мультиплексування (OFDM) та системи багатоелементних антен (MIMO) у безпроводових нестаціонарних частотноселективних каналах мереж мобільного зв'язку та мереж широкосмугового доступу. Проведено аналіз методів просторового блочного кодування (просторово-часового (STBC), просторово-частотного (SFBC), просторово-часового з підвищеною стійкістю до нестаціонарності (WHSTBC-CC), та просторово-частотного з підвищеною стійкістю до частотної селективності ( SF )) та визначено умови їх ефективного використання. Показано,