Channel (broadcasting)

Diversity scheme

Mathematics

Maximum likelihood

Economic growth

Maximum a posteriori estimation

Algorithm

Statistics

Factor graph

Economics

Computational complexity theory

Frequency domain

Programming language

Convergence (economics)

Computer science

Message passing

Computer vision

Orthogonal frequency-division multiplexing

Decoding methods

Telecommunications

Frequency-division multiplexing

Detector

IEEE Transactions on Vehicular Technology

The emerging orthogonal time frequency space (OTFS) modulation technique has shown its superiority to the current orthogonal frequency division multiplexing (OFDM) scheme, in terms of its capabilities of exploiting full time-frequency diversity and coping with channel dynamics. The optimal maximum a posteriori (MAP) detection is capable of eliminating the negative impacts of the inter-symbol interference in the delay-Doppler (DD) domain at the expense of a prohibitively high complexity. To reduce the receiver complexity for OTFS scheme, this paper proposes a variational Bayes (VB) approach as an approximation of the optimal MAP detection. Compared to the widely used message passing algorithm, we prove that the proposed iterative algorithm is guaranteed to converge to the global optimum of the approximated MAP detector regardless the resulting factor graph is loopy or not. Simulation results validate the fast convergence of the proposed VB receiver and also show its promising performance gain compared to the conventional message passing algorithm.

A Simple Variational Bayes Detector for Orthogonal Time Frequency Space (OTFS) Modulation