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OFDM (Orthogonal Frequency Division Multiplexing) is used in many applications that require high-speed communication. However, in the system using OFDM such as PLC (power line communication), there is a problem that reception characteristics are strongly deteriorated by the impulsive noise because impulsive noise has short time duration and very large magnitude. Therefore, many schemes such as clipping...
Periodic blockage of the received signal due to rotor blades is one of the most important problems in helicopter satellite communications. Time diversity is a promising method in order to overcome the periodic blockage. In this paper, a novel time diversity combining scheme is proposed. It performs maximal ratio combining on the basis of the channel blockage information estimated with a pseudo bit...
We propose digital-signal-processing algorithms that achieve fast decoding and LLR-computation for high-order set-partitioned 4D-QAM formats based on their parity-check functions. Computer-simulation results show that computational complexity of the decoder can significantly be reduced with negligible power penalty using such algorithms.
This paper proposes a virtual antenna mapping method for backward compatible massive or large-scale antenna multiple input multiple output (MIMO) base stations that provide communication services for legacy user equipment (UE) that can recognize only two or four base station antennas. The proposed method adopts and improves the omnidirectional beamforming that has been pioneered in previous works...
The next generation of digital terrestrial broadcasting systems using dual-polarized SDM-MIMO technology is under development. The reception deteriorates under an AWGN channel when the XPD for the SDM-MIMO system is low. We describe a method for inter-polarization spreading in the SDM-MIMO transmission system that compensates for the deterioration and our investigation of the reception in a computer...
A new multiple-input multiple-output (MIMO) transmission scheme named\textit{ trellis coded space-shift keying} (TC-SSK) is proposed in this paper. This scheme is obtained by the combination of trellis coding and SSK for a given spectral efficiency, number of transmit antennas and trellis states. A soft decision Viterbi decoder is employed at the receiver to decode the transmitted SSK symbols. Using...
This paper proposes the theoretical derivation method of both the frequency spectrum and the bit error rate (BER) performance for uplink Orthogonal Frequency Division Multiple Access (OFDMA) in the presence of the nonlinear distortion. Since OFDMA has two different subcarrier allocation methods such as localized FDMA (LFDMA) and interleaved FDMA (IFDMA), there is the difference, in terms of the influence...
As the limits of the magnetic storage systems appear, the holographic data storage (HDS) devices with high data transfer rate and high recording density are emerging as attractive candidates for next-generation optical storage devices. In this paper, to effectively improve the detection performance that is degraded by the two-dimensional inter-symbol interference under the HDS channel environment...
Several previous studies have demonstrated that additional low-rate data can be transmitted in Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems by modulating the polarity of the transmitter identification (TxID) signal. Previously proposed additional-data transmission schemes can offer an additional reliable transmission channel, and thus they have a very large...
One of promising transmission technologies in wireless body area networks (BANs) is ultra wideband-impulse radio (UWB-IR) transmission, which can provide high data rate for real-time transmission, and extremely low power consumption for increasing device longevity. Moreover, energy detection scheme in UWB-IR transmission is advantageous in terms of simple implementation. On the other hand, UWB-IR...
A compact construction for nonbinary low-density parity-check (LDPC) codes over GF(q) (q>2) using permutation polynomials (PPs) is proposed in this paper. Following the previous compact construction for binary LDPC codes using quadratic permutation polynomials (QPPs) over integer rings, a QPP whose coefficients are chosen for maximizing the girth is used for determining all the positions of nonzero...
A new 2-step maximum likelihood block signal detection employing QR decomposition and M-algorithm (QRM-MLBD) is proposed to further reduce the computational complexity while keeping a good bit error rate (BER) performance for the single-carrier (SC) transmission in a frequency-selective fading channel. Prior to QRM-MLBD, a computationally efficient minimum mean square error based frequency-domain...
High power efficiency and low nonlinear distortion is very important for wireless visible light communication system. OFDM (orthogonal frequency division multiplexing) system has been studied a lot as the method to transmit high speed data in wireless visible light communication system. However, OFDM system has drawbacks which are non-linear distortion by high PAPR characteristic and ICI problem occurred...
A virtual multiple-input multiple-output (MIMO) system based on cooperative communication is studied actively. This system is formed between base station and source node with using of two or more nodes around itself. These transmitters are equipped with a single antenna. This system is one of the solution methods for deterioration in communication quality from that the power supply of the node is...
This paper studies the performance degradation caused by optical Doppler shift induced by frequency offset in traffic systems which integrate visible light communication (VLC). Through computer simulations the bit error rate (BER) has been derived for the system, and we can observe that frequency offset plays a significant role in the communication performance deterioration due to inter-carrier interference...
One of the major factors of performance degradation in OFDM transmission is influence of additive impulsive noise. Because of wide band property of impulsive noise, it affects the symbols transmitted on many sub-carriers and bit error rate characteristic severely degrades. In this paper, an iterative scheme that reduces influence of impulsive noise by generating a replica signal of impulsive noise...
In mobile environment, decode quality is largely influenced by multipath fading and Doppler shift. In this paper, we reported improvement of mobile reception for high-definition television (HDTV) of integrated services digital broadcasting - terrestrial (ISDB-T) by using maximum ratio combining (MRC) diversity and using two-dimensional (2D) filter in channel estimation. From computer simulations,...
Multi-access interference (MAI) free uplink transmission can be achieved by 2-dimensional (2D) block spread code division multi access (CDMA), and low-complexity single-user frequency-domain equalization (FDE) is performed at base station to obtain the frequency diversity gain. Cyclic delay transmit diversity (CDTD) can further improve the transmission performance by obtaining a larger frequency diversity...
Recently, a frequency-domain block signal detection (FDBD) using maximum likelihood detection (MLD) employing QR decomposition and M-algorithm (QRM-MLD) was proposed for the reception of the single-carrier (SC) signals transmitted over a frequency-selective fading channel. SC-FDBD with QRM-MLD can significantly improve the bit error rate (BER) performance of SC transmission while reducing significantly...
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