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OFDM is the most commonly used modulation technique in today's world due to its capability of supporting high data rates. The major disadvantage in using OFDM is its high Peak to Average Power Ratio (PAPR). This makes very difficult for designers to design efficient RF amplifiers for transmission. In this paper a joint technique of Logrithmic Companding and Selective Mapping is presented which efficiently...
The performance of Binary Phase Shift Keying (BPSK) in a Joint fading and Two-path Shadowing (JFTS)environment is analyzed. Closed form expression for the exact Average Bit Error Rate (ABER) of coherent BPSK scheme is presented using the Moment Generating Function (MGF) of the JFTS distribution. Finally the coherent BPSK ABER of a wireless communication system is simulated over JFTS fading / shadowing...
Future Free Space Optical (FSO) communication systems have the potential of communicating data at very high rates with very high levels of integrity over distances of up to a few kilometers (for terrestrial links). This technology has also been a candidate for setting up very high speed (∲3 Gbps) and highly reliable (BER ∲10−9) communication links between satellites in geo-synchronous orbits and ground...
Asymmetric Distributed Source-Channel coding (DSC) is considered, where a pair of correlated sources are transmitting to a central node. The distributed scheme is based on Turbo Trellis Coded Modulation (TTCM), where the first source will be channel encoded and then compressed before it is sent over Nakagami-m fading channels. The second source signal, however, is assumed to be available flawlessly...
In this paper, we propose a pseudo block-coded SC transmission with frequency-domain equalization (FDE). We call this scheme as pseudo block-coded SC with FDE (PBCSC-FDE). A concatenation of block encoding matrix, interleaving matrix, DFT matrix, mapping matrix and channel matrix can be viewed as an equivalent MIMO channel and FDE and block decoding can be jointly performed based on the minimum mean...
Polyphase magnitude modulation (MM) has been shown to be a robust and effortless mean to improve the efficiency of a transmitter's high power amplifier (HPA), due to the real-time reduction of the peak to average power ratio (PAPR). MM's technique flexibility allows us to include the MM system on any existing single-carrier (SC) based transmission system with clear benefits on the achieved bit error...
Variational Bayesian inference is one of the most powerful tools that can be used in estimation of random variations. Traditionally, in digital modulation, random noise is modeled as an additive white Gaussian noise (AWGN). In this paper, a novel coding scheme is introduced by which the effect of AWGN is decreased and the bit error rate (BER) versus the signal to noise ratio (SNR) curves are enhanced...
Non-orthogonal multiple access improves spectral efficiency through sharing the same frequency resource with multiple wireless terminals. In 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 the power of an interference signal is stronger than that of a desired signal. This implies that the spectrum...
Quantum-based transmission is an attractive solution conceived for achieving absolute security. In this quest, we have conceived an EXtrinsic Information Transfer (EXIT) chart aided channel code design for symbol-based entanglement-assisted classical communication over quantum depolarizing channels. Our proposed concatenated code design incorporates a Convolutional Code (CC), a symbol-based Unity...
The objective of this paper is to study and analyze the suitability of Luby Transform (LT) codes for fading channels such as Rayleigh and Rician channels. The performance of LT codes is actually governed by a well-defined degree distribution function used in LT process. Hence, this paper presents a novel approach called Modified Degree Distribution (MDD) for improving the delay and Bit Error Rate...
The benefits of employing 2-Dimensional (2D) Wave-length/Time (W/T) Hybrid code to mitigate the optical noise in spectral amplitude coding OCDMA networks system is in-vestigated. This analysis allows us to identify the influences of optical noise such as PIIN noise, shot noise and thermal noise in the system performance by using 2D Hybrid FCC-MDW code. The mathematical calculation reveals this new...
An elegant encoding/decoding architecture based on two-code keying scheme for high-rate transmission in non-coherent spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems, is suggested. To evaluate the performance improvement, a commercial OptiSystem software (Version 12.2.1) is used. The simulation results show that SAC-OCDMA system using the proposed architecture exhibited...
Various two-dimensional (2-D) OCDMA codes have been introduced in recent years due to their capabilities in enhancing cardinality, suppressing phase induced intensity noise (PIIN) and eliminates multiple access interference (MAI). This paper presents our new proposal of 2-D spectral/spatial Extended Enhanced Double Weight (2-D Extended-EDW) code. This code is designed to enhance cardinality and effective...
In this paper, we propose a dirty paper coding (DPC) scheme that uses trellis shaping for the overlay cognitive radio channel, where a cognitive user and a primary user transmit concurrently in the same spectrum. Interference of the primary user is assumed to be known at the cognitive transmitter non-causally. Based on this knowledge, the shaping code selection, as a key feature of the proposal, is...
In this paper, we propose a dirty paper coding (DPC) scheme for the cognitive radio channel where multiple cognitive users coexist with a primary user. The cognitive transmitter is assumed to know the primary signals non-causally and is equipped with two antennas, of which each transmits to a single-antenna receiver. In our proposal, zero-forcing DPC is employed to cancel the interference not only...
In this paper, we propose a space-time block coded (STBC) amplify-and-forward cooperative (STBC-Co-AF) relay which requires no knowledge of CSI at relay station (RS). In STBC-Co-AF relay, the source node transmits 2-block signal to both RS and the destination node in the first time slot and then, RS transmits amplified STBC-coded signal to the destination node in the second time slot. The destination...
In this paper we propose a new solution for improving BER performance of the virtual quasi orthogonal space time block coding (QOSTBC). The proposed scheme is compared with virtual QOSTBC and virtual orthogonal space time block coding (OSTBC) schemes. The considered schemes are used for creating virtual 4x1 multiple input-single output (MISO) channel. These schemes include one base station (BS), one...
Error estimating coding has attracted significant attention recently. It enables a receiver to estimate bit error rate (BER) of a partially correct packet. Our study in this paper shows that based on the popular M-QAM modulation schemes, symbol errors have a well-defined structure, which is ultimately translated into a strong correlation in the BER of bits that constitute a symbol. We leverage this...
On the basis of Lu's syndrome-based decoding algorithm, we propose an improved decoding algorithm for turbo product code, which has lower complexity and latency. On one hand, the proposed algorithm further reduces the computational complexity and the decoding latency by simplifying the calculation of syndrome and selecting a proper number of least reliable bits. On the other hand, this algorithm obtains...
Two-dimensional Optical Code Division Multiple Access (2-D OCDMA) has gained great interest among researchers in optical communication systems. This work is aimed to present an alternative way of formulating the spectral/spatial incoherent two-dimensional Extended Enhanced Double Weight (2-D Extended-EDW) code. This code is proposed to suppress the phase induced intensity noise (PIIN) by using multiple...
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