Sharif Digital Repository

In this letter, we study the Gaussian two-way relay channel (GTWRC) with a direct link in which two nodes want to exchange information with each other with the help of a relay node in the presence of a direct link between two nodes. Specially, we focus on a protocol with four phases, which is called the hybrid broadcast (HBC) protocol. In the HBC protocol, sequential transmissions from both users are followed by a transmission from the relay. Using nested lattice codes, we obtain a new achievable rate region for this protocol. In fact, utilizing a four-stage lattice partition chain, we introduce an intermediate lattice in our lattice-based coding scheme, and by using it, we split the... 

A Gaussian cognitive interference channel with state (G-CICS) is studied. In this paper, we focus on the two-sender, two-receiver case and consider the communication situation in which two senders transmit a common message to two receivers. Transmitter 1 knows only message W1, and transmitter 2, referred to as the cognitive user, knows both messages W1 and W2 and also the channel’s states sequence non-causally. Receiver 1 needs to decode only W1 while receiver 2 needs to decode both messages. In this paper, we investigate the weak and moderate interference case where we assume that the channel gain a satisfies |a|≤1. In addition, inner and outer bounds on the capacity region are derived in... 

In this paper, we consider the generalized point-to-point Additive White Gaussian Noise (AWGN) channel with state: The State-Dependent Gaussian Interference Channel (SD-GIC) with a common message in which two senders transmit a common message to two receivers. Transmitter 1 knows only message μ1 while transmitter 2 in addition μ1 also knows the channel state sequence non-causally. In this paper, we consider the strong interference case where the channel state has unbounded variance. First, we show that a scheme based on Gelfand-Pinsker coding cannot achieve the capacity within a constant gap for channel gains smaller than unity. In contrast, we propose a lattice-based transmission scheme... 

Deterministic approach of [1] models the interaction between the bits that are received at the same signal level by the modulo 2 sum of the bits where the carry-overs that would happen with real addition are ignored. By this model in a multi-user setting, the receiver can distinguish most significant bits (MSBs) of the stronger user without any noise. A faithful implementation of the deterministic model requires one to 'neutralize interference' from previous carry over digits. This paper proposes a new implementation of 'interference neutralization' [2] using structured lattice codes. We first present our implementation strategy and then, as an application, apply this strategy to a symmetric... 

A class of Gaussian Z-interference channels with state is investigated in the regime of high state power in which two transmitters communicate two independent messages through a 'dirty' Z-interference channel. Transmitter 1 (primary user) interferes with receiver 2 while transmitter 2 (secondary user) does not interfere with receiver 1. In addition, receiver 2 suffers from a random state sequence which is non-causally known only at transmitter 1. For this setup, which is also investigated by Duan et al. in [1], first we characterize the capacity region for the deterministic case and then by the obtained insight from analyzing the deterministic case, we establish sufficient conditions under... 

In this work, we consider an additive state-dependent Gaussian interference channel (ASD-GIC) where there is a common additive interference, known to both transmitters but not to the receivers. First, we obtain an outer bound on the sum-capacity for the asymptotic case where the interference is assumed to be Gaussian variable with unbounded variance. This asymptotic case has been referred to as the "strong interference" in [1]. By applying a lattice-based coding scheme, an achievable rate-region is provided. Under some conditions, which depend on the noise variance and channel power constraints, this achievable sum-rate region meets the outer bound and therefore lattice codes can achieve the... 

In this paper, we study a general additive state-dependent Gaussian interference channel (ASD-GIC) where we consider two-user interference channel with two independent states known non-causally at both transmitters, but unknown to either of the receivers. A special case, where there is a common additive state is studied in [1], [2], where it is shown that the gap between the achievable symmetric rate and the upper bound is less than 1 /4 bits for the strong interference case. Here, we also consider the case where interference link gains satisfy a12 ≥ N1/ N2 and a 21 ≥ N2/ N1 (Ni is the channel noise variance) and each channel state has an unbounded variance [3], which is referred to as the... 

This paper analyzes the problem of transmitting a Gaussian source over an additive white Gaussian noise (AWGN) channel in the presence of an unknown interference. The goal is to estimate the source at the receiver with minimum mean squared error (MMSE) distortion. We introduce a lattice-based coding scheme and calculate its achievable distortion. If the interference distribution and the lattice voronoi region satisfy some conditions, the effect of interference can be reduced  

In this work, we consider the problem of communicating linear functions of correlated Gaussian sources over a two-user additive Gaussian noise multiple access channel (MAC) in the presence of known interference at the transmitter. The goal is to estimate a linear combination of two sources at the receiver with minimum average mean squared error (MSE) distortion. Here, a lattice-based coding scheme is presented and its achievable distortion is analyzed. In addition, two lower bounds on the achievable distortion are derived. The proposed lattice coding scheme can cancel channel interference completely  

This paper studies the Gaussian two-way relay channel (GTWRC), where two nodes exchange their messages with the help of a half-duplex relay. We investigate a cooperative transmission protocol, consisting of four phases: multiple access (MA) phase, broadcast (BC) phase, and two cooperative phases. For this setup, we propose a new transmission scheme based on superposition coding for nested lattice codes, random coding, and jointly typical decoding. This scheme divides the message of each node into two parts, referred to as satellite codeword and cloud center. Depending on the phase type, the encoder sends a linear combination of satellite codewords or cloud centers. For comparison, a rate... 

In this letter, we study the joint source-channel coding problem of communicating the linear functions of correlated Gaussian sources over a Gaussian multiple access channel. In this setup, each transmitter observes one of two correlated sources. The receiver aims to reconstruct a linear combination of both correlated Gaussian sources within an average distortion level. For this setup, we first obtain a new lower bound on the achievable distortion and then, we propose a novel lattice-based hybrid transmission scheme and its achievable distortion is derived. We show that our proposed scheme can achieve the optimal distortion under some conditions  

Resistance spot weldability of martensitic stainless steels is impaired by the formation of brittle martensite in the fusion zone (FZ). In this paper, in situ rapid tempering via applying a second pulse current after a first melting/solidification pulse during resistance spot welding of AISI 420 martensitic stainless steel sheets was used as a pathway to enhance the toughness of the FZ. By using proper second pulse conditions, the FZ with reduced hardness can be generated which is featured by a decomposed martensitic structure with nano-sized carbide precipitations. The improved toughness as a consequence of this modified microstructure resulted in remarkable enhancement of the peak load and... 

Herein, the effect of electrodeposition time on the super-capacitive performance of three-dimensional (3D) MnO2/g-C3N4 heterostructured electrodes was investigated. MnO2 nanoparticles were electrodeposited on the g-C3N4 nanosheets drop-casted on the Ni foam substrate. The microstructural analysis, carried out by FE-SEM and TEM, confirmed the homogeneous distribution of MnO2 nanoparticles on g-C3N4 nano-sheet layers. The electrochemical capacitive performances of the MnO2/g-C3N4 electrodes were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge tests, and electrochemical impedance spectra (EIS). The obtained results suggested that the supercapacitor (SC) performance of all... 

The electrodeposition of cadmium is studied by electrochemical techniques with the presence of the organic agents. The cyclic voltammetry results clearly show that the electrodeposition of cadmium is a diffusion-controlled process associated with a typical nucleation process. With addition of the thiourea, 3-Picolin and benzyl alcohol organic agents simultaneously in sulfate solution, the redox potential of cadmium is shifted to more negative potentials. In this case, the current transients reveal an instantaneous nucleation with a typical three-dimensional (3D) growth mechanism, while it shows progressive nucleation mechanism without the ternary-species organic agents. In addition, the... 

This paper presents an analytical model to predict the residual stress distribution induced by Shot peening. The analytical approach is based on the work of Shen and Atluri (2006) [18] with some modifications. The modifications are related to the elasto-plastic unloading of shot impingements, friction coefficient effect and the fraction of kinetic energy transmitted to the treated material. In order to predict more realistic residual stresses, the elasto-plastic unloading phase of shot impacts is modeled using two nonlinear kinematic hardening models considering the Bauschinger effect. Moreover, the effect of the Coulomb friction between target surface and shots is evaluated. For this... 

In this letter, the Gaussian two-way relay channel with direct links is investigated in which two users aim at exchanging their messages with the help of a relay node. We propose a new lattice-based compress-and-forward strategy and obtain its achievable rate-region. We show that the proposed scheme is superior to all previously known achievable schemes for channel gains larger than one. In particular, under the symmetric case, the proposed scheme is able to achieve a capacity region within 0.5 bit or (1/2)log 3 ≅ 0.79 bit, depending on the power of the relay  

The 3rd Generation Partnership Project (3GPP) defined a new architecture, called Home eNode B (HeNB). HeNB is able to provide new services with higher data rate in a low cost. Security is a critical aspect of HeNB. In order to have HeNB secure access to core network, 3GPP defines an authentication protocol based on IKEv2. A number of security vulnerabilities such as HeNB masquerading have not been addressed and solved by 3GPP technical specification yet. In this paper an improved HeNB authentication protocol is introduced which does not allow an attacker to connect unauthorized network users using a mask. Finally, we evaluate our protocol performance and verify it by Automated Validation of... 

This paper presents the application of reduced order modeling technique for investigation of liquid sloshing in three-dimensional tanks. The governing equations of sloshing are written using a boundary element formulation for incompressible potential flow. Then, the governing equations are reduced to a more efficient form that is represented only in terms of the velocity potential on the liquid free surface. This particular form is employed for eigen-analysis of fluid motion and the sloshing frequencies and mode shapes are determined. Then, the sloshing frequencies and the corresponding right- and left-eigenvectors are used along the modal analysis technique to find a reduced order model... 

Despite the proven advantage of the low-salinity waterflooding (LSWF) technique, mechanistic understanding of the underlying phenomena at pore-scale remains uncertain. Hence, the corresponding models have limited predictability. In this study, wettability alteration via electrical double-layer (EDL) expansion is captured in a pore-scale model using a multispecies, multiphase computational fluid dynamics simulator. A combination of a pore-doublet and snap-off model is used to evaluate the low-salinity effect (LSE) in two geometries with different pore-Throat size distributions. Contact angle is calculated intrinsically within the model using the concept of disjoining pressure through the... 

In this paper, we address the problem of data description using a Bayesian framework. The goal of data description is to draw a boundary around objects of a certain class of interest to discriminate that class from the rest of the feature space. Data description is also known as one-class learning and has a wide range of applications. The proposed approach uses a Bayesian framework to precisely compute the class boundary and therefore can utilize domain information in form of prior knowledge in the framework. It can also operate in the kernel space and therefore recognize arbitrary boundary shapes. Moreover, the proposed method can utilize unlabeled data in order to improve accuracy of...