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This article analyzes the performance of CSI-assisted cooperative amplify-and-forward (CAF) relay networks that employ both the optimal power allocation strategy among collaborating nodes and adaptive M-ary quadrature amplitude modulation (MQAM) technique in Nakagami-m wireless fading environments. In particular, we advocate a simple yet unified numerical approach based on the marginal moment generating...
In this work, a site-specific validation of path loss models for a home indoor propagation topology was conducted. An 802.11g Wi-Fi system operating at 2.4 GHz was examined and extensive RF measurements were performed, at a residence in downtown Patras, Greece, including multiple floor measurements in order to validate floor penetration losses and the reliability of path loss models for multiple wall...
Wireless technology is a fast, flexible and easy-to-deploy solution to provide broadband access. In this context, the adoption of Femtocell Access Points, operating in the licensed cellular bands and typically designed to be used in SOHO, will improve the radio coverage and the building penetration of the existing mobile networks, based on macrocells. In the present paper an innovative approach to...
Cooperative Network Coding synergistically integrates cluster-based Cooperative Communications and Network Coding to provide high performance by decreasing the outage probability and increasing the network reliability. In this paper, we investigate the effect of the number of hops on the performance of Cooperative Network Coding and analyze different scenarios. Cooperative Network Coding provides...
Companding schemes are widely employed to reduce the peak-to-average-power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. This paper considers the classes of linear and nonlinear companding schemes and derives a sufficient condition under which the bit error rate (BER) performance of one is superior to that of the other. The high PAPR of the OFDM signal drives the transmitter's...
A novel iterative (turbo) receiver is introduced, suitable for orthogonal frequency division multiplexing (OFDM) employing quadrature amplitude modulation (QAM) and receiver diversity. The system operates over a double-selective channel and includes a carrier frequency offset (CFO). We propose a maximum a posteriori probability expectation-maximization (MAP-EM) receiver with a different EM parameter...
In this paper the reliability of a real-time service for multicast transmission over lossy Mobile Ad-hoc NETwork (MANET) is addressed. The proposed system combines application layer channel coding based on Luby Transform (LT) code with multicast delivery in a wireless network exploiting PUMA (Protocol for Unified Multicasting through Announcements). The main goal is to achieve a real-time service...
In our previous work, we exploited a modified version Borel Cayley Graphs (BCGs) as an underlying topology for dense wireless sensor networks using the BCG Topology Control (BCG-TC) algorithm. However, BCG-TC requires sensors to have a large transmission range to guarantee connectivity. In this paper, to overcome the transmission range limit and construct an efficient communication graph, we propose...
To keep healthcare costs under control, a high-level of medication adherence, or compliance with medication regimen, must be achieved. In this paper, we show how wireless technologies can be used to improve medication adherence. More specifically, we present the design, operation, and evaluation of a wireless medication system, termed Smart Medication Management System (SMMS). We also present multiple...
The paper presents new results of speech transmission quality measurements obtained by a recently developed algorithm POLQA — ITU-T P.863 [1]. Even though the algorithm is declared by its authors as not intended for coding technologies under 4kbit/s, our research shows acceptable accuracy for databases containing significant portion of low bit-rate coded samples, namely by MELPe 2.4 kbit/s. The POLQA...
The Serving Call Session Control Function (S-CSCF) is the main node in the IP Multimedia Subsystem (IMS) signaling plane. The S-CSCF, which acts as both a SIP server and registrar, is assigned to serve end users for the duration of their connection to the IMS network. The assignment of users to an S-CSCF is performed by the Interrogating CSCF (I-CSCF) during the user SIP agent registration. The I-CSCF...
The present work aims to provide an effective contribution in the analysis of the coexistence problem between DVB-T signals, operating in the lower part of the UHF band (470–790 MHz), and signals of future mobile communication systems (LTE), operating in the digital dividend portion of the UHF spectrum (from 790 MHz to 862 MHz), resulting from the digital switchover process. Simulation analysis are...
We present a study of average efficiency of power amplifiers (PAs) in power-controlled systems with multi-antenna diversity. The efficiencies are analytically calculated using the transmitted power distributions. Several well-known multiple-input multiple-output (MIMO) diversity techniques, power control rules, PA classes, and channel models are considered. The considered diversity techniques are...
It has been shown that the performance of GSM can be enhanced by the utilization of OSC (Orthogonal Sub Channel) and Dynamic Frequency and Channel Allocation (DFCA) functionalities. So far, the effect of OSC and DFCA on the radio performance and capacity gain has been investigated separately. This paper investigates the performance enhancement when both of the functionalities are utilized at the same...
In wireless multi-hop networks employing OFDM/TDMA, a collision-free time slot assignment is equal to finding a matching set in the network routing graph if an exclusive node (single hop) interference model is assumed. In order to maximize throughput, one must compute the maximum weighted matching set of the routing graph. Since the exclusive node interference model does not take into account interference...
Broadcasting systems have to deal with channel diversity in order to offer the best rate to the users. Hierarchical modulation is a practical solution to provide several rates in function of the channel quality. Unfortunately the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations...
The aim of this paper is to propose and evaluate power allocation techniques for SVD precoded multicell multiuser MIMO-OFDM based systems. We consider a highspeed backhaul network where the base stations are transparently linked by optical fiber to a central unit. This architecture allows an efficient joint multicell multiuser processing. The considered precoder is designed in two phases: first the...
In the last years indoor positioning is getting more and more important for industrial and commercial usage. Progressive approaches are developed to use leaky coaxial cables (LCX) not only for radio coverage but also for indoor navigation, too. Here latest results of the WIPoS project are shown, which focus on indoor positioning based on LCX measurements applying RF fingerprinting. With RF fingerprinting...
In wireless networks, careful planning and link budget analysis is required for delivering maximum throughput reliably with minimum overhead. The efficiency of planning and eventual network performance is totally dependent upon the accuracy and quality of data used for analysis. In most studies, computer simulations and analytical models are used for generating such data. However these simulations...
In this paper, we introduce an M2M(machine-to-machine) communications model based on 4G cellular system which is capable to establish Ad Hoc networks wherever the terminals are close enough. The M2M terminal structure is proposed accordingly. In Ad Hoc mode, the security issue becomes more critical. We consider a simplified protocol stack while introducing key components to provide secure communication...
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