Joint data detection and channel estimation for OFDM systems

Abstract

Abstract-We develop new blind and semi-blind data detectors and channel estimators for orthogonal frequency-division multiplexing (OFDM) systems. Our data detectors require minimizing a complex, integer quadratic form in the data vector. The semi-blind detector uses both channel correlation and noise variance. The quadratic for the blind detector suffers from rank deficiency; for this, we give a low-complexity solution. Avoiding a computationally prohibitive exhaustive search, we solve our data detectors using sphere decoding (SD) and V-BLAST and provide simple adaptations of the SD algorithm. We consider how the blind detector performs under mismatch, generalize the basic data detectors to nonunitary constellations, and extend them to systems with pilots and virtual carriers. Simulations show that our data detectors perform well.Index Terms-Channel estimation, orthogonal frequency-division multiplexing (OFDM), sphere decoding (SD).

SNR‐dependent radius control sphere detection for MIMO systems and relay networks

“…The initial radius for SE is typically set as d D 1 [1]. More results on sphere decoders may be found [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

“…For consistency with the results of [34], the average energy of the transmitted signals is not set to one. Therefore, by using [34, Theorem 2] and the SNR-dependent radius d 2 SRC-SD (11), the expected complexity of SRC-FP is given as Equation (14), where g kl .q/ is the coefficient of…”

“…Nevertheless, the sphere decoders suffer from (i) high complexity in the low SNR region and (ii) a high variability in complexity as a function of the SNR. To address these challenges, many variants have been developed [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For example, [3] uses conditional probabilities to select more reliable candidates, but the complexity is still high for near-ML performance and for high-order constellations.…”

Effective deep learning-based channel state estimation and signal detection for OFDM wireless systems

“…The channel influence at the receiver, channel state information (CSI), must be precisely estimated to retrieve the transferred symbols. In general, the receiver estimates the CSI by employing pilot symbols that are known to both the receiver and the transmitter [2,3].…”