DOI: https://doi.org/10.20535/2411-1031.2017.5.2.136991

Method of adaptive spatial coding of signals for non-stationary frequency-selective channels of wireless communication

Liudmyla Pohrebniak, Mykola Naumenko

Abstract


General using of orthogonal-frequency multiplexing (OFDM) and multi-element antenna systems (MIMO) in wireless non-stationary frequency selective channels of mobile networks and broadband networks were considered. Methods of spatial block encoding (space-time (STBC), spatial-frequency (SFBC), spatial-frequency with high resistance to non-stationary (WHSTBC-CC) and spatial-frequency with increased resistance to frequency selectivity ( )) were analyzed and conditions for their efficient use were determined. It was shown that methods of spatial block coding are effective only for certain diapason of the values of statistical parameters of non-stationary and frequency selectivity (normalized Doppler frequency shift and mean square delay of signal propagation). The contradiction of the time influence and frequency selectivity on structural-parametric optimization of the technology MIMO-OFDM complicates objectively the development of the universal high-performance spatial encoding method for a wide class of non-stationary frequency-selective channels. The advanced method of adaptive spatial signal coding was proposed in order to increase the speed of the information transfer and quality of users service (reducing the probability of the information transmission error). The essence of the improvement is to integrate the channel noise protection of the channel (signal to noise ratio), normalize the value of the Doppler frequency shift, time and frequency correlation coefficients when determining the optimal situational application of SFBC, STBC, WHSTBC-CC, , that ensure the proper use of non-stationary frequency-selective channels with non-invariant parameters in time. The obtained scientific results can be used for modernization of existing and designing perspective wireless networks.


Keywords


Non-stationary; frequency-selectivity; MIMO; OFDM; spatial coding methods; mobile communication network; broadband access network.

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ISSN 2411-1031 (Print), ISSN 2518-1033 (Online)