Implementation on SDR platform of algorithms for noncoherent reception of optimal signals built on the basis of eigenfunctions

Abstract

Formulation of the problem. When transmitting data at speeds above the Nyquist barrier, the algorithmic and computational complexity of radio modems increases significantly, especially with incoherent signal reception. Non-coherent reception algorithms can be implemented on a software-defined radio platform, on which optimal signals are formed and received. The ability to programmatically change the radio frequency parameters of signals without making structural changes to the transmit-receive path can significantly reduce the computing resources of radio modems. The goal is to determine the possibility of practical implementation on the SDR platform (Software Defined Radio) of noncoherent processing algorithms with decision feedback with the choice of optimal values of the observation interval for symbol rates R>1/T using optimal signals built on the basis of eigenfunctions. Results. The possibility of using differential modulation of optimal signals, the forms of which are obtained as a result of solving an optimization problem in accordance with the criterion of the maximum decay rate of the spectrum level outside the occupied frequency band, is shown for packet data transmission protocols and the use of an incoherent processing algorithm in channels with additive Gaussian noise. It is shown that when using algorithms of incoherent element-by-element processing with optimization of the observation interval, it is possible to ensure stable reception of binary optimal signals up to transmission rates exceeding the Nyquist barrier by 1.66 times and for an error probability of 10–3, the energy loss is about 18 dB relative to potential noise immunity. The digital modem of optimal spectrally efficient signals, built on the basis of the SDR platform, makes it possible to conduct spectral and energy efficiency studies in real time in the presence of additive channel noise, and the influence of clock synchronization inaccuracies during packet messaging leads to energy losses of no more than 1 dB. Practical significance. The use of differential modulation of optimal signals can be used in digital television and radio broadcasting systems in the European digital television standards DVB-S2 (Digital Video Broadcasting Satellite Second Generation), DVB-T2 (Digital Video Broadcasting Terrestrial Second Generation).