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Impulse noise (IN) is one of the major impairments for data transmission over power lines. For power line communications (PLC) systems with bandwidths in the high kHz to MHz range, IN occurs in bursts. As long as those bursts are sufficiently short compared to a signal-processing (e.g. coding) frame, there is hope to successfully mitigate IN. In this paper, we introduce a new IN mitigation technique...
Cognitive radio (CR) technology provides great flexibility in spectrum utilization with orthogonal frequency-division multiplexing (OFDM) as its candidate transmission technique. In this paper, we propose a simple spectrum shaping scheme for OFDM-based CRs to enhance spectral compactness and ensure bandwidth efficiency. By mapping antipodal symbol pairs onto adjacent subcarriers at the edges of the...
In this paper, a new Orthogonal Frequency Division Multiplexing (OFDM) with Permutation block spreading scheme is introduced; the transmitted stream is divided into blocks and the data symbols in each block is used to select the spreading code. Therefore, the increased frequency diversity in the system due to spreading improves bit error rate performance in the presence of frequency selective fading...
In the consumer electronics market, the need for error tolerance in wireless systems is increasing especially from I-Q imbalances and non-linearity in RF front-end. In most applications such as encoded image transmission, not all bits are equally important. However, current error tolerance schemes give equal importance to all transmitted bits. In this paper, an OFDM data transfer methodology that...
Unique word - orthogonal frequency division multiplexing (UW-OFDM) is a novel OFDM concept that uses deterministic sequences, which we call unique words, as guard intervals instead of the conventional cyclic prefixes. Since unique words represent known sequences, they can advantageously be used for synchronization, channel estimation, but also for improving the bit error ratio (BER) behavior of a...
In coding theory, concatenated codes form a class of error-correcting codes that are derived by combining an inner code with an outer code. This is a solution to the problem of finding a code that has both exponentially decreasing error probability with increasing block length and polynomial-time decoding complexity. The work presented in this paper, provides link level performance analysis of non-line...
In this paper, a linearly coded (LC) relaying scheme is proposed for multiuser relay network in which a number of users communicate simultaneously with a common destination with the help of one relay node, by using orthogonal frequency division multiple access (OFDMA). The proposed linear coding at the relay node enables exploiting the frequency diversity in the relay-to-destination (R-to-D) link...
Recently we presented a novel OFDM (orthogonal frequency division multiplexing) signaling concept, where the cyclic prefixes (CPs) are replaced by deterministic sequences which we call unique words (UWs). The UWs are generated by appropriately loading so-called redundant subcarriers. By that a complex number Reed Solomon (RS) code construction is introduced which can advantageously be exploited in...
In this paper, we consider a dual carrier modulation (DCM) which is employed in multi-band orthogonal frequency multiplexing (OFDM) ultra wide-band (UWB) system. DCM transforms two QPSK symbols to two 16-QAM symbols with different bit-to-symbol mappings. We find that the basic idea of DCM is the same as that of the rotation code. More specifically, both the rotation code and DCM can provide not only...
In this paper, we propose a 2 × 2 cooperative multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) scheme based on Alamouti space-time coding. In this scheme, the the relay and the destination antennas receive the transmitted symbols from the source during the first stage. Then, both the relay and the destination generate their own decision variables using an Alamouti...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) system proposes enhanced spectrum utilization in contrast to Orthogonal Frequency Division Multiplexing system (OFDM). Spectral efficiency is increased by relaxing the orthogonality condition while maintaining the same transmission rate per individual channel, hence, for the same bandwidth allocation SEFDM offers higher throughput than OFDM...
We propose the use of simple full interference cancellation (FIC) and orthogonal frequency-division multiplexing (OFDM) within a two-hop asynchronous cooperative four relay network. This approach can achieve the full available diversity and asymptotically full rate. The four relay nodes are arranged as two groups of two relay nodes with offset transmission scheduling. Therefore, the source can serially...
In this paper, we employ to provide a method which combines Turbo codes and Low-Density Parity-Check (LDPC) codes based on Orthogonal Frequency Division Multiplexing (OFDM) system by adaptive encoding. The technique of channel estimation is used. The code rate and encoding scheme are all adaptive selection in the light of different channel conditions, so that we can make good use of these two types...
In this paper, we present a new robust scheme for use in asynchronous cooperative networks over frequency-selective channels through using three and four relay nodes. Based on extended orthogonal space-time block coding (EO-STBC), we have presented a direct quantized feedback approach that can achieve full cooperative diversity and array gain with unity code rate over each hop. In this scheme, we...
The instantaneous bit error rate (I-BER) is a direct representation of system performance given a particular channel realization. The I-BER knowledge enables wireless system to combat fading channel impairments by properly adapting transmission parameters. In this paper, we derive the I-BER for a bit-interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system. In high signal-to-noise...
Orthogonal frequency division multiplexing (OFDM) and interleave-division multiple-access (IDMA) are both attractive technique in modern wireless communication. In this paper, we study a multi-user system, which combines OFDM and IDMA, and fortunately, inherits many advantages. In order to improve system performance, low-density parity-check (LDPC) coding is further applied. And moreover, a turbo-type...
Modern wireless communication demands reliable data communication at high throughput in severe channel conditions like narrowband interference, frequency selective fading due to multipath and attenuation of high frequencies. Traditional single carrier systems address this set of problems by the use of complex, computationally intensive equalization filters. The Orthogonal Frequency Division Multiplexing...
A conventional OFDM system often poses a stringent linearity requirement to the transmitter, especially the radio-frequency power amplifier (RFPA), to maintain its bit error rate (BER). As a result, the output power from a RFPA is often limited, thus, the communication distance is compromised. With the deployment of WiMAX (IEEE 802.16), which is targeting at the mobile market, the communication distance...
In this paper, a new scheme that combines Orthogonal Frequency Division Multiplexing (OFDM) with parity bit selected block spreading is introduced. In this proposed method, the data symbols in each block is used to select the spreading code. Therefore, frequency diversity in the system is increased as well as improving the symbol detection due to the inherent coding in the spreading technique. Simulation...
A novel Peak to Average Power Ratio (PAPR) reduction method leveraging the rare occurrence of large magnitude Orthogonal Frequency Division Multiplexing (OFDM) symbols is proposed. A distinct innovation of this approach is the exploitation of the sparseness structure of a bit-plane binary number representation of time domain OFDM symbols. By encoding the sparsely populated non-zero entries in the...
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