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In this paper a receiver making use of a complexity-optimized Decision feedback equalization (DFE) structure and adaptive noise filtering is presented. Vehicular transmission systems such as IEEE 802.11p are facing serious challenges originating from the vehicular channel. Due to the channels high Doppler frequencies and long path delays, channel estimation and equalization is a pivotal aspect of...
Fast time-varying, phase variation, and Doppler shift constitute the features of the underwater acoustic (UWA) communication channel. As a consequence, the effect of intercarrier interference (ICI) becomes significantly critical for orthogonal frequency division multiplexing (OFDM) based UWA communication systems. In this paper, an ICI countermeasure, termed two-path transmission, is proposed. The...
To verify the performance of communication systems, software and hardware prototypes are widely used. However, with the increasing complexity of communication systems, software prototypes cannot meet the needs of real-time operations while hardware prototypes are expensive and time-consuming to develop. Nowadays, Graphics Processing Unit (GPU) shows great prospect as a coprocessor and has the capability...
We propose a factor-graph-based approach to joint channel, impulse, symbol and bit estimation (JCISB) of LDPC-coded orthogonal frequency division multiplexing (OFDM) systems in impulsive noise environments. Impulsive noise arises in many modern wireless and wireline communication systems, such as cellular LTE and powerline communications, due to uncoordinated interference that is much stronger than...
In high data rate communication systems using a Hybrid Automatic Repeat Request, Log-likelihood Ratio (LLR) values should be handled effectively and optimally for reducing memory size. In the paper an adaptive compression algorithm for LLR values is proposed. The approach is based on a dynamic two-dimensional quantization principle and a Huffman encoding. The algorithm was verified for QPSK, 16QAM...
Superposed multicarrier transmission is known to improve frequency utilization efficiency when several wireless systems share spectrum. In the superposed multicarrier transmission scheme, interference can be suppressed by setting the corresponding initial log likelihood ratio (LLR) for forward error correction (FEC) decoder to zero or proper values determined by the desired to undesired power ratio...
This paper investigates space-frequency (SF) coding for non-coherent (NC) Multiple Input Multiple Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) fading links, where neither the transmitter nor the receiver knows the channel. Our strategy consists in distributing the convolutional encoded and interleaved bits over the different transmit antennas, OFDM tones and OFDM symbols. The combination...
Non-orthogonal access improves the spectral efficiency through sharing the same frequency resource with multiple wireless terminals. In the previous researches, it has been shown that a log likelihood ratio (LLR) calculated from a signal on the sharing spectrum should be masked to zero if a power of an interference signal is stronger than that of a desired signal. This implies that the spectrum is...
The high mobility of vehicular networks makes channel estimation and phase tracking challenging and an important problem for OFDM receiver design. In IEEE 802.11p vehicular networks, the channel estimation based on a long preamble in the PHY frame performs poorly in fast-fading channels. Moreover, the pilot-based phase tracking usually suffers from large residual phase errors. In this paper, we propose...
Recently, rateless codes have displayed a promising paradigm for rate adaptation. They enable the sender to transmit packets with a fixed data rate, and the receiver to decode the packets with a data rate comparable to its channel condition. Therefore, rateless codes can achieve higher wireless throughput than the fixed rate codes, especially over time-varying channels. However, as wireless multicarrier...
Joint channel estimation (CE) and turbo multiuser detection (MUD)/decoding for space-division multiple-access based orthogonal frequency-division multiplexing communication has to consider both the decision-directed CE optimisation on a continuous search space and the MUD optimisation on a discrete search space, and it iteratively exchanges the estimated channel information and the detected data between...
Power line communication (PLC) is an emerging technology that aims to provide communication over power lines. In this paper, bit error rate (BER) performances of low-density parity-check (LDPC) coded orthogonal frequency-division multiplexing (OFDM) systems have been investigated in broadband (BB) PLC channels. The performance analyses have been performed for three different indoor channel conditions...
In this paper, a novel hybrid OFDM receiver based on sparse variational Bayesian (VB) learning and soft-input soft-output decoding is proposed. By noticing that a key part of the inference problem approximated by VB (message-passing) methods may be inferred exactly, an genetic interfacing structure is proposed allowing the use of virtually all existing soft-input soft-output decoding schemes. Therefore...
A 10-bit current-steering digital-to-analog converter (DAC) has been proposed. This study is used for the transmitter (Tx) of the powerline communication (PLC) analog-front-end (AFE), and it reaches the standard of the HomePlug AV2. The proposed DAC also uses a technique as digital random-return-to-zero (DRRZ) [1] to achieve high performance in the OFDM communication systems. The test chip was fabricated...
Orthogonal Frequency Division Multiplexing (OFDM) is a promising technology for high data rate transmission, that is widely used in modern wireless communication systems because of its suitability for frequency selective channels. However channel time variations destroy the orthogonality between sub-carriers resulting in Inter-Carrier Interference (ICI), that degrades performance in OFDM. Various...
In this paper, we complement the open literature by presenting a comparative performance evaluation between conventional and modified Viterbi metrics for soft-decision decoding of binary convolutional codes in the framework of IEEE 802.11n systems with transmit beamforming, space division multiplexing and spatial spreading transceiver architectures. Simulation results show that the inclusion of channel...
In this paper, we propose a Differential Overlap Decoding(DOD) algorithm to solve the hidden-terminal problems in OFDM based WLAN systems. DOD exploits the retransmission and random-jitter features of WLAN to decode the collided packets as a whole. DOD provides with new methods and views to jointly separate and decode collided packets in OFDM based system. In DOD, we formulate IFFT/FFT, channel influence...
This paper investigates channel coded transmission schemes for two-way relay networks (TWRNs) where two terminal nodes exchange information through a set of amplify-and-forward (AF) relays over frequency-selective fading channels. Specifically, we assume that the two terminal nodes employ bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM) for coded data transmission,...
Performance of underwater acoustic communication system is influenced on channel characteristic. Especially, an important feature of the underwater acoustic communication is multipath propagation and Doppler spread cause by the surface and bottom reflections. In this paper, we study the application of high speed image transmission using multi-carrier modulation, where this capability can enable the...
Cost-effective, asynchronous 4 ONUs OOK-OCDM-based 10G-PON system using a novel multiple access noise suppression at RN and its 50km-SMF transmission without dispersion compensation is experimentally demonstrated for the first time.
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