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Non-Coherent receivers are attractive for IR-UWB systems and are preferred over its coherent counterpart, because of its implementation simplicity and non-requirement of channel state information (CSI). UWB systems have a low Power Spectral Density (PSD) which limits it from achieving a wide coverage and high data rate despite, providing an adequate system performance. Hence, cooperative diversity...
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...
In SC-FDMA systems the bit error rate (BER) is very sensitive to channel estimation errors. We propose the use of blind (or semi-blind) subspace decomposition to estimate the channel frequency responses between the transmitter and the multiple antennas of the receiver in the uplink of a 4G system employing SC-FDMA. The proposed subspace- based channel estimation technique requires very little overhead...
Information hiding based on error correcting code is one of the difficulties in information hiding research. Current information hiding algorithms cannot confirm the upper bound of covert channel capacity when channels are interfered. In this paper, a capacity self-adaption information hiding algorithm based on RS code is proposed to solve this problem. Firstly, Channel covert communication model...
Duobinary partial response (PR) filtered single-carrier frequency-domain multi-access (SC-FDMA) uplink has a potential to achieve higher spectral efficiency (SE) by allowing spectrum overlapping between adjacent users. However, strong multiuser interference (MUI) degrades the bit-error rate (BER) and throughput performances. In this paper, we present two types of frequency-domain MUI cancellation...
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...
This paper analyzes the performance of the OS-CDMA system using OFDM technique to enhance the channel data rate, to save power and increase the number of user of OSCDMA systems. This system compared with previous hybrid subcarrier multiplexing/optical spectrum code division multiple-access (SCM/OSCDMA) system. The average received SNR with the nonlinearity of subcarriers is derived. The theoretical...
A new class of code called Flexible Cross-Correlation (FCC) for Spectral-Amplitude Coding Optical Code-Division Multiple-Access (SAC-OCDMA) systems has been de-veloped. The FCC code has advantages, such as flexible cross-correlation property at any given number of users and weights, as well as effectively reduces the impact of Phase-Induced Intensity Noise (PIIN) and Multiple-Access Interference (MAI)...
Recently, we proposed a multi-block frequency-domain equalization (MB-FDE) for single-carrier space-time block coded time-division duplex (SC-STBC TDD) transmission. In this paper, we propose an adaptive two-dimension (2D) multi-input multi-output (MIMO) channel estimation (CE) for SC-STBC TDD transmission in a high mobility environment. In the proposed adaptive 2D-MIMO-CE, the channel over consecutive...
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...
Superposed multicarrier transmission scheme is known to improve frequency utilization efficiency when several wireless systems share the same spectrum. To suppress the effect of interference, forward error correction (FEC) metric masking is proposed. In the technique, log-likelihood ratio (LLR) that corresponds to superposed band is set to zero, because received bits that correspond to superposed...
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, a unified framework, denoted as generalized nonlinear detection (GND), is developed to encompass existing nonlinear detection technologies as well as further optimize the performance of nonlinear detection for noncoherent impulse radio (IR) ultra-wideband (UWB) receivers. Computer simulations show that independent of absence or presence of narrowband interferences (NBIs), the GND-based...
In this paper, we propose an audio watermarking method using processed sound of music. For audio signals, watermarks are embedded in time domain or Fourier domain. In existing methods, it is required that noises are not perceived in stego signal. On the other hand, in the proposed method, there is no problem even if a different sound from host signal is perceived when stego signal is maintained as...
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...
Security becomes the critical issue in incoherent spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems. In preventing the unintended users from decoding and extracting the data due to the cross-correlation among code sequences, an ideal detection technique is needed to enhance the security of the SAC-OCDMA systems. In this paper, we study the efficiency of the modified-AND...
A 2-Dimensional (2-D) Wavelength/Time (W/T) scheme is proposed for spectral amplitude coding OCDMA network system. The new hybrid codes are utilizing Flexible Cross Correlation (FCC) and Modified Double Weight (MDW) codes which both codes have good correlation properties and capable to suppress multiple access interference (MAI). From the numerical calculation, it has been shown that this new hybrid...
Multihop free space optical (FSO) system using optical amplify-and-forward (OAF) relaying technique combined with wavelength division multiplexing (WDM) is proposed for all-optical access networks. The proposed system can provide a low cost, flexible, and high-bandwidth access network for multiple users. To investigate the system performance, we consider a special case of dual-hop WDM-FSO system taking...
This paper presents a mathematical model for car-to-car (C2C) visible light communications (VLC) that aims to predict the system performance under different communication geometries. A market-weighted headlamp beam pattern model is employed. We consider both the line-of-sight (LOS) and non-line-of-sight (NLOS) links, and outline the relationship between the communication distance, the system bit error...
We experimentally demonstrate a FDMA-PON system targeting 20 Gbps per wavelength in the upstream, using a real-time FPGA-based transmitter and low-speed baseband DSP, and 39 Gbps in the downstream using a new resources allocation algorithm with 11.5GHz electrical bandwidth, in the framework of the EU research project FABULOUS.
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