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The DFT-based channel estimation method is widely used in OFDM systems due to a good balance between computation complexity and performance. But this DFT-based method encounters degradation of performance caused by the energy leakage from non-sample locations of the multipath timing. To alleviate the leakage effect, a channel estimation method by adding virtual channel frequency response (VCFR) was...
We present a novel cost-efficient architecture based on a hybrid mode locked laser capable to simultaneously generate wavelength division multipliexed (WDM) passive optical network (PON) and radio over fiber (RoF) signals for 60 GHz applications. The proposed approach is compatible with the ITU frequency grid and does not require high bandwidth Mach-Zehnder modulators. Simulation results reveal the...
Among the OFDM synchronization algorithms, the algorithm based on repeated structured training sequence is widely used because of its simple structure and high accuracy of frequency estimation. An implementation method of OFDM timing synchronization with repeated-structured training sequence is presented in this paper, which uses FPGA as a hardware platform. There are three parts in this design. The...
In this paper we propose new Zadoff-Chu (ZC) based synchronization sequences suitable for future broadcast system preambles. While maintaining the same overall structure and length as in the DVB-T2 P1, we replace the synchronization mechanism by a particular combination of ZC sequences capable of carrying one or more signaling bits. We will present the design methodology, the possible ZC constructions...
Recently, compressive sensing (CS) algorithms have been adopted to improve the accuracy of channel estimation for wide-band wireless communication systems. Since the wireless channel is usually time and frequency doubly selective fading, the performance of CS based channel estimation is limited by the estimation accuracy of the channel's sparsity level. In this paper, an adaptive subspace pursuit...
The street light system, using a Power Line network, requires detailed knowledge about transmission medium, such as: transfer function, parasitic capacity, induced inductances and noise due to capacitive coupling between phases, in order to undertake a reliable master/slave communication. This paper proposes an innovative algorithm useful for a network dynamic configuration. It will allow to reduce...
In this paper, an iterative receiver with Turbo equalization and soft demapping is proposed for high data rate communication in multipath channels. Minimum mean square error (MMSE) equalization is adopted to avoid noise enhancement. With the assumption that the distribution of estimated symbols is Gaussian distribution, log likelihood ratios (LLR) of encoded bits are obtained with soft demapping....
In this paper, equalization of multihop relaying orthogonal frequency division multiplexing (OFDM) signal is investigated under time-varying channel with unknown noise powers, channel orders and Doppler frequencies. An iterative algorithm is developed under variational expectation maximization (EM) framework. The proposed algorithm iteratively estimates the channel, learns the channel and noise statistical...
In this paper, an optimized time-frequency interleaving scheme is proposed to combat against the narrowband interference (NBI) and time-domain impulsive noise (TIN) for orthogonal frequency division multiplexing (OFDM) systems in power line communications (PLC). To improve both the anti-NBI and anti-TIN performance, we propose two criteria based on which the optimized interleaving scheme is designed:...
Mutual coupling among receive antennas can profoundly reduce the ergodic capacity of MIMO systems. Prior work has shown that these losses can often be mitigated by using multi-port antenna matching at the receiver; however, previous studies have focused exclusively on frequency-nonselective matching and rely on assumptions which are valid only for small bandwidths. In this paper, we revisit the ergodic...
This paper is concerned with a challenging problem of channel estimation for amplify-and-forward cooperative relay based orthogonal frequency division multiplexing (OFDM) systems in the presence of sparse underwater acoustic channels and of the correlative non-Gaussian noise. We exploit the sparse structure of the channel impulse response to improve the performance of the channel estimation algorithm,...
The paper presents a physical (PHY) layer simulation of the low voltage powerline communication (LV PLC) system in accordance with the PRIME standard. The simulation concept is based on the transmission line and two port network theory. The simulator PrimeSim is implemented within the Matlab and introduces a graphical user interface for the network setup and results management. Furthermore, the simulator...
This paper deals with the automatic classification of signals for aeronautical communication. The automatic signal classification is an important feature for the application of Cognitive Radio in aeronautical communications. Cognitive Radio will allow of automatically adapting the transmission parameters according with the radio environment and the channel conditions, with the aim of assuring reliable...
Multipath spread is one of the most important factors which limit data transfer with high bit rate. Data transfer with high bit rate is possible in the range of gigahertz. The main problem in this frequency range is multipath spread. Orthogonal frequency division multiplexing (OFDM) technique divides the transferring symbols between several subcarriers and transfers them simultaneously. Accordingly...
In this paper, we propose two novel receiver designs for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO- OFDM). The first one, termed 'Proposed Receiver I', exploits the structure of the clipping noise which improves the power efficiency over the state-of- the-art ACO-OFDM receiver. The second one, termed 'Proposed Receiver II', exploits the benefit of bit error correction...
In this paper we investigate the performance of distributed space-time block coding (D-STBC) orthogonal frequency division multiplexing (OFDM) over underwater acoustic (UWA) channels. In particular, we consider a relaying system consisting of one source, two relays, and one destination. The relays operate in amplify-and-forward (AF) mode. The underlying channels are assumed to be time-varying frequency...
In this paper, we consider Doppler compensation for time varying underwater acoustic channels. The underlying system model comprises two sources, S1 and S2, communicating with each other through a relay, R. The transmission process goes through two phases. In the first phase, the two sources transmit simultaneously and the relay receives. In the second phase, the relay processes the received signals...
In this work we present a case for dynamic spectrum sharing between different operators in systems with carrier aggregation (CA) which is an important feature in 3GPP LTE-A systems. Cross-carrier scheduling and sensing are identified as key enablers for such spectrum sharing in LTE-A. Sensing is classified as Type 1 sensing and Type 2 sensing and the role of each in the system operation is discussed...
Frequency offset (FO) is an inherent feature of wireless communications. It results from differences in the operating frequency of different radio oscillators. Failure to compensate for the FO may lead to a decoding failure, particularly in OFDM systems. IEEE 802.11a/g systems use a globally known preamble to deal with this issue. In this paper, we demonstrate how an adversary can exploit the structure...
Multicarrier communication is a well-known and widely used method in the current wireless or wired data transmission. Orthogonal Frequency Division Multiplexing (OFDM) is the leading technology in this area and is implemented in various forms in almost every current broadband communication systems. It has a number of advantages, but also few significant shortcomings. Especially the high out-of-band...
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