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In this paper, an overview of a new physical layer specification for power line communications, named Lite-PLC, and simulation and lab test results showing the expected performance of the newly designed PLC modem, are presented. The specification uses OFDM for data transmission and is intended to operate in the low-frequency of 100 – 450 kHz in the ARIB band plan.
Impulsive noise (IN) consists of sudden short time peaks of high power which appear in communication channels from time to time. The IN influence on Power Line Communications (PLC) has been proved to be very harmful. A particular feature of PLC standards is the prohibition of signal power transmission at the frequency bands used by radio amateurs, which are referred to as the masked tones; however...
The spread spectrum clock (SSC) is known to have the ability to reduce the quasi-peak level of clock harmonics noise. However, SSC may also have an adverse effect on wireless systems. In the present paper, a SSC with optimized parameters is developed that has a beneficial effect on one-segment broadcasting, which is based on orthogonal frequency division multiplexing and is used for mobile TV in some...
Different guard interval techniques for the Orthogonal Frequency Division Multiplexing (OFDM) transmission are suggested to reduce the interference between successive symbols (i.e. Inter-Symbol Interference, ISI) and interference between different carriers within the same symbol (i.e. Inter-Carrier Interference, ICI). In this paper, the impact of replacing the Cyclic Prefix (CP) by zeros insertion...
Orthogonal frequency-division multiplexing (OFDM) wireless communication systems suffer severe inter- channel interference(ICI) due to high Doppler frequency spread, the paper investigate a kind of channel estimation approach that combines the multiply continue OFDM symbols and decision feedback technology. Further, we present a low-complexity algorithm to evaluate the ICI components for decision...
Noise in water is very crtical and may destroy the the OFDM based underwater acoustic communication system. The performance of pilot tones based channel estimation will not be the good choice under low SNRs. Complete frequency response of data channel is usually obtained by interpolating channel frequency response at pilot bits, such that the error of interpolation influences and degrades the performance...
This paper discusses coexisting signal detection technique of the interference DAA (Detect And Avoid) operation. In this paper, the emission of the coexisting singles and their occupied frequency band detection technique for the MB-OFDM (Multi-Band OFDM) system is proposed in order to improve the DER (miss Detection Error Rate) and the FAR (False Alarm Rate). The received coexisting signal is assumed...
This paper presents a self-adjustment of the length of the channel impulse response using a classical Cholesky Factorization. This is of special importance in the context of algorithms containing a matrix inversion and the rank of this matrix is strongly related to the length of the channel impulse, i.e. interferer cancellation algorithm [1]. When the length of the channel impulse response is overestimated,...
Narrowband powerline communication has the great potential market application like Auto-Meter-Reading (AMR). This paper focuses on the design and implementation of narrowband powerline communication module with the OFDM technology. Firstly, it introduces the OFDM solution for low voltage powerline communication module design, then it describes the implementation of the sync module, Viterbi code translation...
Orthogonal Frequency Division Multiplexing (OFDM) is one of the leading technology that is ruling the communication field. But unfortunately, it is shrouded in mystery. A good knowledge in Linear Algebra is required to appreciate the technology in a better way. So the work focuses on explaining OFDM system from linear algebra point of view. Also, OFDM model communication system is simulated using...
This paper presents some techniques for estimating the time difference of arrival (TDOA) associated with signals in a multipath communication channel for wireless indoor positioning. Recently, variants of Matrix Pencil (MP) algorithms have been presented to estimate the direction of arrival (DOA) of coherent or non-coherent signals using uniform linear arrays (ULA). These include the Unitary Matrix...
Novel blind and semi-blind subspace channel estimations are proposed for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems in the presence of virtual carriers (VC). Slow convergence rate is a drawback of subspace method in deriving the noise/signal subspaces from the second-order statistics of received signals, especially when the dimension of received...
This paper presents a data-aided Carrier Frequency Offset (CFO) estimation algorithm targeting the Wideband OFDM systems. Utilizing 3 consecutive preambles and processing them at frequency domain, the algorithm is robust to both Frequency Independent (F-I) and Frequency Dependent (F-D) I/Q Mismatch (I/Q-M). To evaluate the effectiveness of the proposed CFO estimation technique, we conduct extensive...
In this paper, we analyze the channel estimation technique for OFDM (orthogonal frequency division multiplexing) used in VLC (Visible Light Communication system). A Post-Processing DFT (Discrete Fourier Transformation) channel estimation method was proposed to improve the system performance by eliminating the noise outside the maximum channel delay. After linear interpolation, the channel estimation...
Due to aggressive goals for future communication systems, direct-conversion receivers are an attractive option in terms of compactness and power dissipation. However, the price to pay is an additional impairment introduced by IQ imbalance, which might be compensated by appropriately designed DSP algorithms. In this context, joint recovery of carrier phase and IQ gain/phase imbalance has been presented...
In this paper, hardware design for a blind fine carrier frequency offset (CFO) estimation method is proposed for MB-OFDM UWB system. The method utilizes the conjugate symmetry in frequency domain of the physical layer convergence protocol (PLCP) preamble sequence to achieve high accuracy and low complexity fine CFO estimation with wider range of CFO error. Previous contribution to CFO estimation has...
Detailed knowledge of the interference scenario is necessary for power line communication (PLC) systems. PLC model with appropriate noise model creates the basics in a way of searching for the most powerful coding and modulation techniques. This paper brings an overview of PLC communication model focusing mainly on a noise scenario. Finally, a blocks of the PLC communication model are mentioned and...
This paper presents a maximum likelihood (ML) approach to mitigate the effect of narrow band interference (NBI) in a zero padded orthogonal frequency division multiplexing (ZP-OFDM) system. The NBI is assumed to be time variant and asynchronous with the frequency grid of the ZP-OFDM system. The proposed structure based technique uses the fact that the NBI signal is sparse as compared to the ZP-OFDM...
A characterization of a phase modulated coherent optical OFDM system based on Hartley transform is performed. The use of phase modulation minimizes OFDM amplitude fluctuations, resulting in reduced peak-to-average power ratio. Also, it is based on Hartley transform for simplifying the signal processing. In this paper, theoretical models are developed for describing the behavior of the system when...
In this paper, we investigate the information theoretical limits on the performance of cooperative multicarrier underwater acoustic (UWA) communication systems. We assume decode-and-forward (DF) relaying and consider non-orthogonal half-duplex cooperation. Under the assumptions of sparse and frequency-selective Rician fading channel and correlated Gaussian ambient noise, we derive the maximum achievable...
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