145 research outputs found
A Reduced Complexity Ungerboeck Receiver for Quantized Wideband Massive SC-MIMO
Employing low resolution analog-to-digital converters in massive
multiple-input multiple-output (MIMO) has many advantages in terms of total
power consumption, cost and feasibility of such systems. However, such
advantages come together with significant challenges in channel estimation and
data detection due to the severe quantization noise present. In this study, we
propose a novel iterative receiver for quantized uplink single carrier MIMO
(SC-MIMO) utilizing an efficient message passing algorithm based on the
Bussgang decomposition and Ungerboeck factorization, which avoids the use of a
complex whitening filter. A reduced state sequence estimator with bidirectional
decision feedback is also derived, achieving remarkable complexity reduction
compared to the existing receivers for quantized SC-MIMO in the literature,
without any requirement on the sparsity of the transmission channel. Moreover,
the linear minimum mean-square-error (LMMSE) channel estimator for SC-MIMO
under frequency-selective channel, which do not require any cyclic-prefix
overhead, is also derived. We observe that the proposed receiver has
significant performance gains with respect to the existing receivers in the
literature under imperfect channel state information.Comment: This work has been submitted to the IEEE for possible publication.
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Artificial Intelligence-aided OFDM Receiver: Design and Experimental Results
Orthogonal frequency division multiplexing (OFDM) is one of the key
technologies that are widely applied in current communication systems.
Recently, artificial intelligence (AI)-aided OFDM receivers have been brought
to the forefront to break the bottleneck of the traditional OFDM systems. In
this paper, we investigate two AI-aided OFDM receivers, data-driven fully
connected-deep neural network (FC-DNN) receiver and model-driven ComNet
receiver, respectively. We first study their performance under different
channel models through simulation and then establish a real-time video
transmission system using a 5G rapid prototyping (RaPro) system for
over-the-air (OTA) test. To address the performance gap between the simulation
and the OTA test caused by the discrepancy between the channel model for
offline training and real environments, we develop a novel online training
strategy, called SwitchNet receiver. The SwitchNet receiver is with a flexible
and extendable architecture and can adapts to real channel by training one
parameter online. The OTA test verifies its feasibility and robustness to real
environments and indicates its potential for future communications systems. At
the end of this paper, we discuss some challenges to inspire future research.Comment: 29 pages, 13 figures, submitted to IEEE Journal on Selected Areas in
Communication
Efficient space-frequency block coded pilot-aided channel estimation method for multiple-input-multiple-output orthogonal frequency division multiplexing systems over mobile frequency-selective fading channels
© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.An iterative pilot-aided channel estimation technique for space-frequency block coded (SFBC) multiple-input multiple-output orthogonal frequency division multiplexing systems is proposed. Traditionally, when channel estimation techniques are utilised, the SFBC information signals are decoded one block at a time. In the proposed algorithm, multiple blocks of SFBC information signals are decoded simultaneously. The proposed channel estimation method can thus significantly reduce the amount of time required to decode information signals compared to similar channel estimation methods proposed in the literature. The proposed method is based on the maximum likelihood approach that offers linearity and simplicity of implementation. An expression for the pairwise error probability (PEP) is derived based on the estimated channel. The derived PEP is then used to determine the optimal power allocation for the pilot sequence. The performance of the proposed algorithm is demonstrated in high frequency selective channels, for different number of pilot symbols, using different modulation schemes. The algorithm is also tested under different levels of Doppler shift and for different number of transmit and receive antennas. The results show that the proposed scheme minimises the error margin between slow and high speed receivers compared to similar channel estimation methods in the literature.Peer reviewe
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