Jad Nasreddine

• PhD
• Senior Researcher at i2CAT Internet and Digital Innovation in Catalonia

The radio interface is the bottleneck of most wireless communication systems. All techniques used to enhance this interface require certain knowledge of the radio environment. This knowledge usually concerns either short-term, or long-term models and statistical characteristics of the environment, depending on the technique. Short-term models are s...

Wireless network deployments are becoming increasingly complex in order to cope with the exponential growth in mobile data traffic. Multi-tier technologies capable of supporting spatially dense networks enable high data rates, but require timely and accurate models of the radio environment, particularly for scenarios that incorporate dynamic access...

In this paper we investigate the possibility of using measurement-based propagation models in the framework of Dynamic Spectrum Access (DSA), where secondary users can opportunistically access the licensed spectrum of a primary system. In principle this will provide a precise representation of the radio environment since it takes into account all e...

In this paper we explore the use of stochastic approaches for opportunistic access based on models of primary user activity. We focus in particular on a scenario where the secondary user does not perform traditional sensing at all, but relies only on statistical information of primary transmissions. Using techniques from the theory of alternating r...

In this paper we propose a heuristic algorithm that exploits additional information that can be in general known by a secondary network willing to opportunistically access the spectrum allocated to a primary network. The algorithm aims at finding the maximum allowed transmission power with which a secondary node can transmit while respecting primar...

Vehicular communications are positioned to be one of the most impacted sectors in the next generation of cellular networks, enabling a massive rollout of unseen vehicular use cases. However, the inherent high mobility associated with vehicles can lead to vehicular congestions, where the increase in data traffic introduced by vehicular communication...

In cross-border mobility scenarios, interactions between mobile network operator (MNO) infrastructures and multi-access edge computing (MEC) systems across international borders are required at both the control and data planes to provide seamless and uninterrupted services to users transitioning between two MNOs. However, the exchange of informatio...

Cooperative, Connected and Automated Mobility (CCAM) and Future Railway Mobile Communications System (FRMCS) use cases present strict requirements in terms of service end-to-end latencies, data-rates, reliability and service availability , posing challenges in the design of 5G network architectures for cross-border scenarios, where current roaming...

Abstract— Polycystic Ovary Syndrome (PCOS) is a medical condition affecting the female’s reproductive system causing ano/oligoovulation, hyperandrogenism, and/or polycystic ovaries. Due to the complexities in diagnosing this disorder, it was of upmost importance to find a solution to assist physicians with this process. Therefore, in this study, we...

Falls are a prevalent and severe health problem in the elderly community, leading to unfortunate and devastating consequences. Some falls can be prevented through interventions, proper management, and extra care. Therefore, studying and identifying elderly people with risk of falls is essential to minimize the falling risk and to minimize the sever...

There is an increasing interest in developing older adult fall-risk prediction models that can be used as a preventive approach to predict future risk of falling in the elderly community. This study's primary objective is to implement and compare supervised machine-learning methods to classify elderly subjects as fallers or non-fallers. Features us...

Global warming is becoming a paramount concern in the world. One way to decrease the effect of global warming is by decreasing carbon emission and using renewable energy. In particular, there are many works on using renewable energy technologies in mobile communication systems. In order to enable such technologies in mobile communication systems, w...

-The focus of this paper is targeted towards multi-cell 5G networks which are composed of HPNs (High Power Node) such as evolved NodeBs (HPNs) that control signaling and system broadcasting information and of simplified LPNs (Low Power Node) co-existing in the same operating area and sharing the scare radio resources. Consequently, greater emphasis...

The migration to smart cities will provide citizens with a plethora of services under the umbrella of Internet of Things, such as real time health monitoring, smart vehicular, and road control systems. To meet smart cities’ needs, technological development in the fields of Smart Grid, Big Data processing and Broadband Communication, has started. In...

The target of this paper is to propose a practical low-complexity power allocation algorithm that strikes a good balance between Spectral Efficiency (SE) and power saving for the downlink of interference-limited cellular networks. Because abundant interference usually results from dense frequency reuse and high power transmission, power optimizatio...

Dynamic time-division duplex (TDD) mode has been suggested to be used in LTE systems for small-sized cells with asymmetric traffic. Despite its flexibility, the TDD mode suffers from sophisticated interference patterns, i.e. mobile-to-mobile and Base station-to-Base Station interference. In order to solve this problem, the 3GPP has specified a set...

Traditional design of wireless networks mainly focuses on system capacity and spectral efficiency. As green networking is an inevitable trend, energy-efficient design for future wireless networks becomes paramount. In this paper, we address energy efficient resource management in downlink Orthogonal Frequency Division Multiple Access (OFDMA) networ...

Orthogonal Frequency Division Multiplexing (OFDMA) accepted as the multiple access scheme for the 4G Systems provides resistance to inter-symbol and intra-cell interference. However inter-cell interference, when dense frequency reutilization is used, can deteriorate the performance of users with bad channel quality, in particular at cell-edge. Inte...

Femtocells are a promising approach to provide high data rates through autonomous configuration in indoor environments. However, due to the random and uncontrolled deployment of femtocells within users premises, interference between femtocells themselves and with macrocell base stations is a major issue. In this work, we look into the interference...

Time Division Duplex (TDD) mode can provide highly asymmetric services due to the flexible radio resource management. This flexibility allows the use of crossed slots especially when the rate of asymmetry is not the same in all cells. In crossed slots, some cells may be active in downlink while neighboring cells are active in uplink. The presence o...

In this paper we propose an opportunistic access procedure in an OFDMA-based femtocell scenario. The procedure allows the femtocells to provide its users with higher data rate by accessing the unused sub-channels of the macrocells. It is based on combining information from the overall system architecture with side information used to detect the unu...

We study the performance characteristics of cognitive wireless networks under different dynamic spectrum access scenarios. Our focus is especially on the influence of spatial structures of the primary and secondary user networks on the achievable performance of the secondary network. We adopt techniques from spatial statistics to develop stochastic...

In this demonstration we show an approach for constructing radio environment maps from massive data sets. Unlike earlier approaches, the methods used in the demonstrator can scale to millions of measurement points, enabling coverage prediction and other spatial estimation problems to be solved at country-wide scales. The demonstrator GUI enables at...

In this article, we present a layered radio environment map architecture along with its applications to the self-organizing network functionalities of heterogeneous LTE radio access networks comprising macrocells and femtocells. In this architecture, the functional blocks reappear with different spatial and temporal granularity at different archite...

Femtocells and WiFi have been considered as viable concepts in cellular networks to increase overall system capacity. Critical functionalities for the successful integration of such technologies in macro-cellular topologies are related to radio resource allocation and interference management techniques that must ensure seamless intra-cell and inter...

The paper investigates the use of Radio Environment Maps (REMs) as a tool for Interference Management (IM) in two-tier cellular networks comprising macro- and femto-cells. The REMs are databases that provide, through different instances distributed over network elements, a variety of network- and user-related context information for improving IM an...

In this paper we address the use of utility-based optimization in wireless networks. Our optimization approach is enabled by well-defined, technology- and platform-independent generic interfaces. The latter provide an abstract and unified representation of data and services available from the protocol stack, ranging from old legacy protocols to new...

In this paper, we explore the possibility of deploying a cognitive network that can opportunistically access the spectrum allocated to a primary cellular network. The main problem is that cellular networks are characterized by multiple simultaneous and dynamic transmissions combined with power control. The proposed approach assumes that the cogniti...

We explore the effects of spectrum sensing time parameters on non-cooperative dynamic spectrum access by jointly considering the PHY layer sensing and the MAC layer sensing scheduling. Our work not only incorporates singular sensing performance measures in terms of the probability of missed detection and false alarm, but also takes into account the...

In this article we describe a demonstrator that shows how the cognitive resource manager (CRM) and the radio-environmental map (REM) can be efficiently implemented in full commercial grade cellular system (i.e., LTE system). The demonstrator shows how the modular CRM together with its open interface, the universal link-layer API (ULLA), facilitates...

In this contribution a layered radio environment map (REM) architecture is designed and applied in the framework of radio-access network optimization for heterogeneous LTE systems that comprise both macrocells and femtocells. We define layer as the hierarchical representation of a geographical area. In each layer, different instances of the same ar...

We empirically study problems of online estimation and modeling of radio activity (ON/OFF) patterns and their duty cycles. We consider performance of two algorithms that analyze power spectrum samples in time domain as sensed by WARP SDR boards placed at different indoor locations. The first algorithm utilizes density function of the marginal distr...

In this paper we introduce a utility-based optimization approach for wireless communication based on developed Common Application Requirement Interface (CAPRI). The proposed system allows applications to register their utility functions to a radio resource controller at run-time and in automatic way. This enables the implementation of utility-based...

We study the influence of the structure and dynamics of the primary network on occurrence and quality of transmit opportunities of the secondary network. In order to obtain accurate results, we develop a framework for performance evaluation that allows detailed modeling of the networks involved, while still enabling general conclusions to be drawn....

In this paper we describe an experimental testbed to empirically study the construction of Radio Environmental Maps (REMs) in indoor environments. The testbed allows investigating the characteristics and modeling of the radio environment for indoor scenarios. The deployed system is a network of over 80 heterogeneous wireless spectrum sensors with s...

The increasing complexity of the future wireless networks leads to the requirement for self-organization. This is true especially in home networking where users are typically not networking professionals and cannot be expected to perform complex optimization and management tasks. In this context, cognitive radio concept combining cross-layer optimi...

In this paper we propose a general model to estimate the maximum allowed transmit power of a secondary node based on the measured signal from the primary transmitter that is willing to share its downlink spectrum. The transmit power should satisfy primary constraints related to the minimum required Signal to Interference and Noise Ratio (SINR) of i...

The demand for higher data rates, capacity and better quality-of-service is constantly growing for home networks. Therefore, there is a pressing need for efficient use of wireless network resources. In this context, the application of cognitive radio principles that enable network nodes to characterize their environment and control their resources...

A common concept to mitigate the effects of spectrum scarcity is to allow opportunistic dynamic spectrum access (DSA) to licensed frequency bands. In this context, the license holder may experience a decrease in the performance of its network. For cellular networks this may lead to unwanted coverage holes at locations where the secondary-induced in...

In this paper we describe an LTE based demonstrator of the Universal Link Layer API (ULLA) and Cognitive Resource Manager (CRM) modules that are developed in ARAGORN project. The demonstrated LTE system comprises one LTE TDD eNode B and one User Equipment (UE). We first introduce ULLA and CRM framework and then demonstrate their suitability to be i...

The deployment of highly dense wireless local area networks (WLAN) can cause an excessive level of interference in the commonly used 2.4 GHz ISM band, which leads to network performance degradation. This paper analyses the possibility to reduce congestion in the crowded ISM band by allowing some access points (APs) to opportunistically operate in a...

The E2R-II prototyping environment, as part of the E2R-II project, is a framework that pretends to demonstrate the most promising radio resource management proposals that are developed within the project. Such demonstrations have been based on a dedicated proof-of-concept environment, which serves for validating the work in the areas of cognitive n...

Activity patterns of primary users have significant influence on the opportunities for secondary use of spectrum. In this paper we explore this impact in terms of spatial spectrum reuse opportunities. More specifically, we model the primary user activity as a Semi-Markov ON/OFF process with varying distributions of holding times of ON and OFF state...

Cognitive Radios have emerged as one the most promising methods to increase wireless system efficiency through dynamic spectrum access combined with other cross-layer optimization methods. Most of the research prototypes and demonstrations have so far focused on either general platforms or scenarios that are predominantly taken from military or eme...

We propose a distributed channel selection protocol for cognitive radio networks that are organized as ad hoc architectures considering single hop transmission. The channel selection is performed over a common control channel in such a way that channel congestion as well as heavy sensing effort is avoided. Simulation results show that the proposed...

In this paper, we propose an advanced spectrum management approach for the downlink of WCDMA systems using genetic algorithms and the concept of coupling matrix, which is able to capture inter-cell interactions. Simulation results show that the proposed approach increases spectrum efficiency while guaranteeing the required QoS levels. Moreover, it...

Wireless technologies are rapidly evolving to allow operators to deliver more advanced multimedia services. High-speed packet access (HSPA) for uplink and downlink is seen as an intermediate evolutionary step since the first wave of wideband code division multiple access (WCDMA)-based networks rollout, while evolved universal mobile telecommunicati...

Wireless technologies are rapidly evolving to allow operators to deliver more advanced multimedia services. High-speed packet access (HSPA) for uplink and downlink is seen as an intermediate evolutionary step since the first wave of wideband code division multiple access (WCDMA)-based networks rollout, while evolved universal mobile telecommunicati...

The authors propose a new advanced spectrum management (ASM) methodology for wideband code division multiple access systems based on the concept of coupling matrix, which is able to capture inter-cell interactions. The proposed methodology takes into account the fact that each cell can be associated to more than one carrier and aims at liberating s...

In this paper, we introduce a framework encompassing the creation and the exploitation of secondary spectrum usage opportunities. The paper develops a complete positioning-based framework to assess the feasibility of supporting secondary communications on frequencies which are released by primary spectrum management methodologies. In particular, th...

In this paper, we propose a new Advanced Spectrum Management (ASM) methodology for WCDMA systems using simulated annealing and the concept of coupling matrix, which is able to capture inter-cell interactions. The proposed methodology takes into account the fact that each cell can be associated to more than one carrier. Simulation results show that...

This chapter addresses the implementation of decentralized RAT selection strategies at the mobile terminal in a heterogeneous wireless network scenario. This can be achieved if the network provides some information or guidelines to assist the terminal in its decisions, making use of the IEEE P1900.4 protocol. In order to illustrate the procedure, a...

This paper addresses the implementation of decentralized RAT selection strategies at the mobile terminal in a heterogeneous wireless network scenario. This can be achieved if the network provides some information or guidelines to assist the terminal in its decisions, making use of the IEEE P1900.4 protocol. In order to illustrate the procedure, a s...

In this paper, we propose a novel analytical framework that is able to capture inter-cell interactions and relevant variations in WCDMA systems using the so-called coupling matrix. Coupling matrix properties related to its spectral radius are analyzed and used to introduce a pertinent indicator which is able to dynamically optimize spectrum efficie...

This article presents a shadowing simulation model based on multiple-edge diffraction. Such model provides an appropriate tool for simulating shadowing in cases where over-obstacle diffraction is the main propagation mechanism. Results show that the model is in good agreement with literature in terms of its statistical parameters. Moreover, its cap...

In this paper a new spectrum management methodology for WCDMA systems is proposed based on the concept of coupling matrix, which is able to capture inter-cell interactions. The proposed methodology takes into account the fact that uplink and downlink frequency carriers are jointly allocated and optimizes simultaneously the two link directions. Simu...

The combination of the TDD mode and the TDMA technique in WCDMA systems engenders a new degree of flexibility that can increase system capacity and QoS levels of active channels if efficient slot allocation techniques are used. These techniques allow the system to control the allocation of slots to users, and thus lead to relevant reduction in inte...

This paper presents a comparative analysis of system-level TD-CDMA simulation results obtained for different shadowing simulation models. Namely, relevance of aspects such as cross-correlation or spatial autocorrelation of shadowing is studied. It is shown that, in terms of system capacity, modelling of cross-correlation plays a more important role...

Future wireless systems are expected to endure significant increase in cell loads as well as non-uniform distribution of the traffic over cells. Hence, interference profiles are subject to high increases that can highly affect interference limited systems. The allocation of several frequencies to each operator in 3G systems presents new dimensions...

In this paper, we propose an evolution of adaptive power control algo- rithms for Universal Mobile Telecommunications System (UMTS). The pro- posed mechanism uses an adaptive power step to carry out with high ∞uc- tuations in the radio interface. Furthermore, we propose the integration of a stabilization zone where the transmitted power is kept con...

Classical spectrum planning exercise is based on some expected spatial traffic distributions and corresponding load levels. Nevertheless, practical network deployments show that the dynamism in mobile scenarios and unpredictable changes in traffic distribution make traffic estimation severely frail. Hence, new approaches should be developed to dete...

Although a single carrier frequency is usually considered in wideband code division multiple access (WCDMA) systems, each operator has more than one carrier frequency in practical 3G systems. Moreover, QoS levels and the throughput within a given frequency highly depend on interference patterns, which are mainly related to cell-frequency allocation...

Many multimedia services of the next generation mobile telecommunication systems have an asymmetric traffic distribution between uplink and downlink. The combination of the time division duplexing (TDD) with the time division multiple access (TDMA) technique in the Universal Mobile Telecommunications System (UMTS) allows an asymmetric use of radio...

Adaptive power control algorithms has been widely studied for interference reduction, base station radiation decrease and terminal battery saving in 3G cellular systems. We study some of the existent adaptive power control algorithms and we propose an evolution of these algorithms in the forward link. In the proposed algorithm, we try to maintain t...

This paper describes a hardware platform that has been designed to validate joint detection receivers for UMTS/TDD. This testbed includes transmitters, a multipath baseband channel emulation and a receiver. The receiver includes channel estimation, multiuser detection (MUD) and channel turbo decoding. It consists of a set of DSP and FPGA boards hos...

The proposed algorithm can be used in both link directions of the FDD mode and in the downlink of the TDD mode of UMTS, where the same closed-loop power control is used. Adaptive power control algorithms have a dynamic transmitted power update step. For these algorithms, power control steps depend on the instantaneous mobile command and the command...

We propose a time slot allocation scheme (interference avoidance methods) based on normalized path gain for TD-CDMA TDD system. Like other interference avoidance methods, the proposed method uses path gains between a mobile and interfering base stations to avoid high inter-mobile interference. In addition, it considers the uplink transmitted power...

Power control is of great importance in reducing cochannel interference and increasing the capacity of mobile telecommunications systems. The aim of optimum power control procedure is to achieve a maximum carrier-to-interference ratios (CIR) in all active communication links (i.e. CIR balancing). Optimum power control with CIR balancing has been wi...

TD-CDMA TDD technique allows UMTS to utilize the bandwidth and the rare radio resource more efficiently if dynamic channel allocation is used. This technique is suited especially for systems that offer highly asymmetric services. However, the rate of symmetry is not the same in all cells. Hence, it is possible that in some slots, called crossed slo...

Power control is a very important feature of CDMA systems and it dramatically impacts the cellular capacity. The UTRA-TDD (Universal Terrestrial Radio Interface with Time Division Duplex) adopted for third generation systems is a hybrid radio interface, which mixes TDMA and CDMA schemes. Therefore, power control and slot allocation must be optimise...