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Conventional correlation-based frame synchronization techniques can suffer significant performance degradation over multi-path frequency-selective channels. As a remedy, in this paper we consider joint frame synchronization and channel estimation. This, however, increases the length of the resulting combined channel and its estimation becomes more challenging. On the other hand, since the combined...
Narrowband power line communications (NB-PLC) and unlicensed wireless communications are the two leading communications technologies for the emerging two-way Vehicle-to-Grid (V2G) communications applications. In this paper, we exploit the media diversity provided by the availability of both the NB-PLC and wireless links to enhance the robustness against the interference and noise encountered on both...
In this paper, we propose a novel approach to recover off-grid narrow-band-interference (NBI) in orthogonal-frequency-division-multiplexing (OFDM) systems using a compressive-sensing (CS) framework. NBI degrades the performance of OFDM systems which motivates the need for mitigation techniques to reduce its effect. NBI is a sparse signal in the frequency-domain (FD). However, frequency-grid mismatch...
Next-generation wireless networks target dense deployment scenarios where many heterogeneous devices, from high-end laptops to low-power Internet of Things (IoT) devices and wearables, must coexist and operate reliably. With increased deployment of IoT devices and wearables, increasing the energy efficiency without increasing complexity#x002F;cost is highly desirable in future dense wireless networks...
A free-space optical system using subcarrier intensity modulated quadrature phase shift keying (QPSK) is investigated for Gamma-Gamma fading channels with receiver in-phase and quadrature (I/Q) imbalances. The I/Q imbalance caused by imperfection of analog components is unavoidable using any direct-conversion transceivers. In addition to the receiver I/Q imbalances, the performance of a subcarrier...
Narrowband powerline communications (NB-PLC) and unlicensed wireless communications are considered as two leading communications technologies for emerging Smart Grid applications. The diversity provided by the simultaneous transmission of the same information over powerline and wireless links can be exploited to enhance the overall system reliability. In this paper, we consider differential transmission/detection...
In this paper, we propose a cyclostationary noise model for multi-input multi-output (MIMO) narrowband power line communication (NB-PLC) based on frequency-shift (FRESH) filtering. The MIMO FRESH filters are designed to shape a multi-input white noise spectrum to a muti-output cyclic spectrum extracted from experimental noise measurements of three-phase low-voltage power lines. The noise modeling...
This paper investigates the effect of in-phase and quadrature timing mismatch (IQTM) on millimeter- wave system performance and reveals that the IQTM, which is commonly neglected in the literature, degrades system performance significantly. As a solution to this IQTM problem, this paper proposes novel pilot designs for transmit and receive IQTM estimation, and develops corresponding estimators. Simulation...
We investigate the physical layer security of synchronous multiple access transmissions using the Alamouti space-time block code in fading channels where multiple users communicate with a single intended receiver in the presence of an eavesdropper. We propose an artificial-noise-aided technique to secure the transmissions by having the Alamouti users collaborate with each other, without exchanging...
This paper investigates a cross-layer design to secure a set of buffered legitimate source nodes wishing to communicate with a common destination node. We assume a slotted-system and time-division multiple-access spectrum sharing where only one legitimate source node is allowed to transmit in a given time slot. The users' assignment probabilities to the time slots are optimized to satisfy a certain...
In this paper, we propose a cyclostationary noise model for narrowband power line communication (NB-PLC) based on frequency-shift (FRESH) filtering. The FRESH filters are designed to shape an input white noise spectrum to a cyclic spectrum extracted from experimental noise measurements. The noise modeling problem is considered as a system identification problem that minimizes the time-averaged mean...
Visible light communications (VLC) technology has recently emerged as a complementary technology to the indoor radio frequency (RF) networks. While the backhauling of the indoor RF networks has been supported by fiber optics, the backhauling of the VLC network is still an open research problem. Power line communications (PLC) has been considered as a possible solution for the VLC networks due to its...
This paper investigates artificial noise injection into the temporal and spatial dimensions of a legitimate wireless communication system to secure its transmissions from potential eavesdropping. We consider a multiple-input single-output (MISO) orthogonal frequency division multiplexing (OFDM) system in the presence of a single-antenna passive eavesdropper and derive both the secrecy rate and average...
Differential space time block coding (STBC) achieves full spatial diversity and avoids channel estimation overhead. Over highly frequency-selective channels, STBC is integrated with orthogonal frequency division multiplexing (OFDM) to achieve high performance. However, low-cost implementation of differential STBC- OFDM using direct-conversion transceivers is sensitive to In-phase/Quadrature-phase...
In this paper, a novel approach is proposed to jointly recover the transmitted data and mitigate narrow-band interference (NBI) in OFDM systems using compressive sensing (CS) framework. NBI degrades the performance of OFDM systems which motivates the need for mitigation techniques to reduce its effect. The main idea behind our approach is to represent the transmitted data and the NBI signal as a sparse...
In this paper, narrow-band interference (NBI) mitigation is addressed in amplify-and-forward orthogonal-frequency-division-multiplexing (AF-OFDM) cooperative communication systems. Based on the channel gains between the interferer, destination and the relay nodes, three copies of the NBI are received at the destination node in addition to the desired signal. Hence, NBI degrades the performance of...
In this paper, a novel approach is proposed to jointly recover the transmitted signal and mitigate narrow-band interference (NBI) in OFDM systems using a compressive sensing (CS) framework. NBI degrades the performance of OFDM systems which motivates the need for mitigation techniques to reduce its effect. The main idea behind our approach is to represent the transmitted data and the NBI signal as...
In this paper, we address the problem of sparse signal recovery from scalar quantized compressed sensing measurements, via optimization. To compensate for compression losses due to dimensionality reduction and quantization, we consider a cost function that is more sparsity-inducing than the commonly used ℓ1-norm. Besides, we enforce a quantization consistency constraint that naturally handles the...
In this paper, we address the problem of sparse signal recovery, from multi-bit scalar quantized compressed sensing measurements, where the saturation issue is taken into account. We propose a convex optimization approach, where saturation errors are jointly estimated with the sparse signal to be recovered. In the proposed approach, saturated measurements, even though over-identified, are considered...
In this paper, we propose a general framework that transforms the problems of designing sparse finite-impulse response channel-shortening equalizers and target impulse response filters for multiple antenna systems into the problems of sparsest-approximation of a vector in different dictionaries. Additionally, we compare several choices of the sparsifying dictionaries in terms of the worst-case coherence...
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