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Securing radio frequency identification (RFID) systems against malicious attacks such as eavesdropping is a highly challenging task due to the resource constrained nature of such systems. In fact, the modest computational and storage capabilities of RFID tags makes it impossible to adopt classical cryptographic techniques. While existing work has mostly focused on lightweight cryptographic techniques,...
Coverage optimisation is an important self-organising capability that operators would like to have in LTE networks. This paper applies a Reinforcement Learning (RL) based Sparse Sampling algorithm for the self-optimisation of coverage through antenna tilting. This algorithm is better than supervised learning and Q-learning based algorithms as it has the ability to adapt to network environments without...
Professional Mobile Radio (PMR) requires higher reliability with less dense infrastructure than usual public mobile networks. Potential implementation of the next generation public mobile radio system Long Term Evolution (LTE) in PMR can bring new features, e.g., real time video. However, its feasibility must be carefully investigated with realistic PMR applications. This paper presents such an investigation...
A complementary Particle Swarm Antenna (PSA), which consists of an array of parasitically coupled microstrip patches, is presented for application in wireless communication systems. PSAs are characterised by their unique non intuitive designs which result from an application of Particle Swarm Optimisation (PSO) that does not implement constraints on the shape of the patch during the optimisation process...
The paper investigates the statistical modeling of on-body ultra wideband (UWB) radio channels based on measurements conducted in five different rooms for wireless body area network (WBAN) applications. Previously the authors proposed a UWB propagation loss model for WBAN and considered the effects of room volume. A measured delay profile can be divided into two domains: in the first domain (0 <...
This work presents an analysis of signal propagation in an indoor environment. Three empirical models were implemented: Modified Keenan-Motley, Log-Distance and Linear Attenuation. The simulation delivers a coverage map showing the reception power in the corresponding area, whose results are validated with experimental data acquired with a low cost test environment.
This paper presents a method to generate cryptography keys instead of exchange them over a public communication channel. Session keys exchange is considered as a major problem to be resolved in a communication network. When two terminals exchange data through an unsecured public channel, they use cryptography techniques to prohibit a third terminal from intercepting exchanged data. Symmetric cryptography...
Equipping base stations (BSs) with very large antenna arrays is a promising way to increase the spectral and energy efficiency of mobile communication systems without the need for new cell sites. However, the prominently theoretical works on this topic are based on several crucial assumptions about the wireless channel which have not been sufficiently validated by measurements. In this paper, we report...
A 1.5-bit 20-MHz bandwidth continuous-time delta-sigma modulator (CT-DSM), which is suitable for envelope pulse-width modulation (EPWM) transmitters, is presented. To compensate the process-voltage-temperature variation, a resistor calibration method is proposed. The proposed calibration scheme improves a signal-to-quantization-noise-ratio (SQNR) by 18%. The switched capacitor digital-to-analog converter...
Social mobility models attempt to mimic human movement characteristics with the motivation to provide more realistic experimentation environments. Being recent, these models have a few gaps, being one of them the lack of a realistic function to dynamically track pauses. This paper proposes and evaluates such a function against real-traces.
In this paper, we determine the performances of an Optical Code Division Multiple Access (OCDMA) based wireless transmission system for indoor healthcare monitoring application. We consider line of sight communication links between multiple emitters placed on monitored patients and a base station located at the environment ceiling. We first establish an analytical expression of error probability for...
The spectrum sharing has recently passed into a mainstream Cognitive Radio (CR) strategy. We investigate the core issue in this strategy: interference mitigation at Primary Receiver (PR).We propose a linear precoder design which aims at alleviating the interference caused by Secondary User (SU) from the source for Orthogonal Space-Time Block Coding (OSTBC) based CR. We resort to Minimum Variance (MV)...
This paper focuses on the enhancement of extended orthogonal space-time block coding (EO-STBC) when transmitting over a doubly-dispersive channel. The frequency selective nature of the channel favours the combination with a multicarrier approach such as orthogonal frequency division multiplexing (OFDM). However, as Doppler spread increases, OFDM loses its orthogonality, resulting in severe inter-symbol...
In this paper, the ergodic capacity of multiple antenna systems over spatially correlated Rayleigh-fading channels is investigated under the assumption that the channel state information (CSI) is unknown at the transmitter and perfectly known at the receiver. We derive a lower-bound expression, in closed form, for the ergodic capacity through the use of majorization theory and the probability density...
Interference alignment is a promising approach to handle the interference in mobile radio networks especially at high SNR. In the present paper, the interference alignment is achieved using a number of MIMO relays in a scenario with K single antenna node pairs. A two-phase transmission scheme is considered assuming the channel to be constant during the transmission phases. Firstly, the source nodes...
This paper presents some techniques for estimating the time difference of arrival (TDOA) associated with signals in a multipath communication channel for wireless indoor positioning. Recently, variants of Matrix Pencil (MP) algorithms have been presented to estimate the direction of arrival (DOA) of coherent or non-coherent signals using uniform linear arrays (ULA). These include the Unitary Matrix...
The increasing use of wireless networks has raised the desire to have not only a stable and good quality access to the network, but also to seamlessly change the network when moving. Various handover algorithms have been proposed to handle this situation. Unfortunately, many of these handover algorithms have only been evaluated by simulations. They do not take the wide range of mobile devices with...
Layered and cooperative elements such as femto-cells and relays can improve performance or energy efficiency in mobile networks; however, they consume energy per se and their durations in operational state must therefore be minimised. This paper investigates the use of relays in WiMAX network deployments and concentrates on the cost/revenue performance and energy efficiency trade-off in such cases...
Interference alignment (IA) has been shown to achieve the maximum degrees of freedom in the multiple-input multiple-output (MIMO) K-user interference channel (IFC). In the presence of frequency-selective channels, orthogonal frequency-division multiplexing (OFDM) is typically used to deal with the multipath nature of the channel. While IA techniques can be applied in a per-subcarrier basis (post-FFT),...
Energy efficiency has become a critical metric in the current wireless communication and network because we spend a number of energy for operating networks. In particular, the base station is the most energy consuming part of a mobile network. Therefore, there are many approaches to solve this problem. Among them, the sleep mode of macrocell base station is one of high impact techniques. The sleep...
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