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  • On the need for dynamic downlink intercell interference coordination for realistic long term evolution deployments

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    Wireless communications and mobile computing
    Date of publication: 2014-03
    Journal article

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    Intercell interference is the main issue limiting the capacity of modern orthogonal frequency-division multiple access based cellular networks. Recently, extensive research work has been carried out in this field, and intercell interference coordination techniques have been recognized as key enablers of current (and future) cellular technologies. In this article, (i) a comprehensive survey of the most representative contributions is provided together with (ii) a generic methodology to measure their actual merit. The performance of several interference avoidance strategies has been evaluated both from system and user point of view in the context of a Long Term Evolution (LTE)-based network considering not only synthetic cellular scenarios but also realistic deployments. Our literature review indicates that there is a need for adaptive/operatorcustomizable low-complex intercell interference coordination (ICIC) schemes suitable for realistic LTE deployments. Results obtained by means of a comprehensive set of simulations corroborate and support this premise. In this article, it is shown that simultaneous gains in terms of spectral/energy efficiency and fairness can be achieved through dynamic mechanisms with respect to both classic hard reuse schemes and static ICIC techniques. Besides numerical results, a novel merit assessment methodology based on several weighted performance metrics is proposed. Our findings show that dynamic schemes outperform static techniques by around 20–35% in realistic deployments.

  • Design of Static Intercell Interference Coordination Schemes for Realistic LTE-based Cellular Networks

     González González, David
    Defense's date: 2014-01-29
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Actualmente los sistemas 3.5 y 4G tales como Long Term Evolution (LTE) y LTE-Advanced (LTE-A) soportan servicios basados en paquetes y proporcionan a elevadas tasas de transmisión. En este contexto, aparecen nuevos retos técnicos que deben ser resueltos eficientemente. El objetivo último es conseguir un salto cualitativo importante en la experiencia de usuario. Con tal fin, un factor clave en las redes celulares basadas en OFDMA es la gestión de interferencias. La utilización de un factor de reuso bajo permite una elevada eficiencia espectral pero a costa de una distribución no homogénea de la calidad de servicio (QoS), depende de la posición del usuario. Así, el rendimiento en los límites de la celda se ve muy penalizado y es un problema importante a resolver en LTE y LTE-A.La coordinación de interferencias entre celdas (ICIC, Intercell Interference Coordination) engloba las estrategias cuyo objetivo es mantener la interferencia intercelular (ICI) lo más baja posible en los bordes de celda. Esto permite aliviar la situación mencionada. La contribución presentada en esta tesis doctoral incluye el diseño de nuevos mecanismos de ICIC estática para los canales de datos y control, con mejoras en la eficiencia energética. A partir de una revisión del estado del arte, se identificaron una serie de retos que requerían esfuerzos de investigación. En concreto, la necesidad de métodos de evaluación flexibles y marcos de optimización de las estrategias de ICIC estáticas. Estos mecanismos se agrupan en dos familias: esquemas que definen restricciones sobre el dominio de la frecuencia y los que proponen ajustes en los niveles de potencia. La base de la gran mayoría de propuestas ICIC estáticas son la reutilización de frecuencias de tipo soft y fraccional (SFR y FFR, respectivamente).De este modo, durante la primera parte de la tesis, se han estudiado los aspectos más importantes del funcionamiento de SFR y FFR, haciendo especial énfasis en las conclusiones que van más allá de las conocidas. Ello ha permitido introducir un nuevo marco estadístico para evaluar el funcionamiento de estos sistemas en condiciones de despliegue real. Como resultado de estos análisis, se muestra el pobre desempeño de SFR y FFR en despliegues reales cuando funcionan con sus configuraciones clásicas y se establece la necesidad de optimización. También se pone de manifiesto la importancia del funcionamiento conjunto entre esquemas ICIC estáticos y otras funcionalidades de la red radio, tales como el feedback del CSI (Channel State Information). De este modo, se han propuesto diferentes esquemas de feedback apropiados para trabajar conjuntamente con SFR y FFR. Estos mecanismos explotan el patrón de asignación de recursos que se utiliza en ICIC estático.La segunda parte se centra en la optimización de SFR y FFR. Se ha investigado el uso de técnicas multiobjetivo como herramienta para lograr una optimización eficaz, que es específica de cada red. El enfoque ofrece ventajas, por un lado, se permite la optimización simultánea de varios criterios contradictorios. Por otro lado, la naturaleza multiobjetivo implica obtener como resultado configuraciones de red de elevada calidad (Pareto eficientes), con un equilibrio casi óptimo entre las diferentes métricas. Los algoritmos evolucionarios permiten la utilización de estructuras matemáticas complejas sin necesidad de relajar el problema, de este modo capturan adecuadamente su comportamiento. La formulación consigue un ajuste efectivo de los parámetros operacionales de SFR y FFR, a nivel de celda y red. Además, la investigación se extiende satisfactoriamente a los canales de control, PDCCH y ePDCCH.Finalmente, en un esfuerzo por mejorar la eficiencia energética de la red, se introduce en el análisis el apagado inteligente de celdas, estrategia con estrechos vínculos con ICIC. A través del método propuesto, se obtienen mejoras significativas con respecto a los enfoques tradicionales y propuestas previas.

  • The help4mood wearable sensor network for inconspicuous activity measurement

     Pérez Diaz de Cerio, David; Ruiz Boque, Silvia; Rosell Ferrer, Francisco Javier; Ramos Castro, Juan Jose; Valenzuela Gonzalez, Jose Luis; Colomé Castellví, Josep Maria
    IEEE Wireless communications
    Date of publication: 2013-08
    Journal article

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    The Help4Mood EU FP7 project (H4M) [1] proposes to significantly advance the state-ofthe-art in computerized support for people with Major Depression by monitoring mood, physical activity and voice characteristics while promoting activities in reaction to examined inputs. Employing actigraphy can provide supplementary data about patients with depression. Nonetheless, its use is not standardized and there is a lack of public analyses about treated patients with depression using this technique, which is the objective of the project. The purpose of the Personal Monitoring System (PMS) used in H4M is to compile objective data about the changes and trends of activity patterns during long periods of time. This would comprise daily activity, rest time and, if possible, sleep quality. The PMS uses inconspicuous methods but keeping the cost associated with sensor installation at the patient¿s home to a minimum. This work focuses on the Wireless Sensor Network (WSN) enhancements introduced after real testbeds and considering User Quality of Experience (QoE), mainly oriented to reduce energy consumption and required data transmission and consequently improving the autonomy and range of the sensors.

  • Aperiodic ICIC-oriented CSI reporting for LTE networks

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia
    Date of publication: 2013-12-31
    Book chapter

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    Broadband Wireless Access Networks for 4G: Theory, Application, and Experimentation presents the latest trends and research on mobile ad hoc networks, vehicular ad hoc networks, and routing algorithms which occur within various mobile networks. This publication smartly combines knowledge and experience from enthusiastic scholars and expert researchers in the area of wideband and broadband wireless networks. Students, professors, researchers, and other professionals in the field will benefit from this book¿s practical applications and relevant studies.

  • Improved component carrier selection considering MPR information for LTE-A uplink systems

     Lema Rosas, Maria Angel; Garcia Lozano, Mario; Ruiz Boque, Silvia; González González, David
    IEEE International Symposium on Personal Indoor and Mobile Radio Communications
    Presentation's date: 2013-09-09
    Presentation of work at congresses

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    Carrier Aggregation (CA) is one of the key features introduced in LTE Release 10 to achieve higher levels of throughput. Two or more component carriers (CCs) are aggregated and user equipments (UEs) simultaneously transmit in more than one. The use of non-contiguous resource allocation in the uplink (UL) implies higher peak to average power ratio, so power de-rating is essential to avoid inter-modulation distortion and adjacent channel leakage-power ratio. CC selection is a key radio resource management procedure by which the eNB assigns UEs to CCs. While most CC selection algorithms deal with downlink, existing literature lacks efforts on UL CA. Moreover the mechanism is determinant on the UL performance. Given the UE power limitation, different criteria must be used in each link. This work proposes a novel CC selection algorithm that distinguishes between power limited and non-power limited UEs. In particular it is proposed to introduce information on maximum power reduction in selection decisions. Besides, UEs are not directly rejected if they are power limited, an acceptance margin is defined. This contains information on throughput variations between the allocation in several or just one CCs. This novel approach is contrasted with other CC selection techniques. Results show cell edge throughput improvements and the benefit of allowing bandwidth aggregation in a subset of power limited users.

  • Introduction of MPR information for enhanced multi-cluster scheduling in LTE-A uplink

     Lema Rosas, Maria Angel; Garcia Lozano, Mario; Ruiz Boque, Silvia; González González, David
    Wireless and Mobile Networking Conference
    Presentation's date: 2013-04-23
    Presentation of work at congresses

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    Against previous Long Term Evolution (LTE) re-leases, LTE-Advanced (LTE-A) allows the use of non-contiguous resource allocation in the uplink (UL). This feature leads to an increase in spectral efficiency thanks to link performance gains obtained from frequency diversity. At the same time noncontiguous allocations bring higher peak to average power ratio (PAPR) and so potentially higher inter-modulation and adjacent channel leakage-power ratio (ACLR). Power de-rating has been proposed as a means to avoid this problem and thus user equipments (UEs) must reduce their maximum transmitted power. However, the additional link loss on power limited UEs partially counteracts the gain brought by multi-cluster allocation. In this sense, this paper proposes to include Maximum Power Reduction (MPR) information in opportunistic scheduling decisions. The new scheduling proposal is able to determine whether multi-clustering leads to a net gain in instantaneous throughput or if localized allocation is preferred. Results show that this method improves cell throughput and allows making a smarter use of clustered transmission.

  • Improved scheduling decisions for LTE-A uplink based on MPR information

     Lema, Maria A.; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    European Cooperative in Science And Technology
    Presentation's date: 2013-02-07
    Presentation of work at congresses

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    Advanced (LTE-A) allows for non-contiguous resource allocation in the uplink. The aim is to increase the spectral efficiency by exploiting users’ frequency diversity gain. This feature implies that clustered-DFT-S-OFDM must be used in the uplink, no longer preserving the single carrier property of previous releases. Multi-cluster transmission brings an increase in the signal’s Peak-to-Average Power Ratio (PAPR) and so power de-rating must be introduced to control out-of-band emissions. Maximum power Reduction (MPR) can counteract the frequency gain and bring losses to the users’ performance. This paper proposes a novel scheduler that considers the MPR information. The packet scheduler’s main task is to evaluate the gain or loss in throughput of the multi-cluster transmission over a conventional contiguous one. Based on the Sounding Reference Signals (SRSs) channel estimation, the eNB can predict the multi- cluster transmission’s performance. Results show that enabling the MPR information in the scheduler adapts the transmission mode to each particular case, enhancing the system throughput

  • Power allocation for the PDCCH in LTE: a way to increase its capacity in realistic deployments

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia
    International Symposium on Wireless Personal Multimedia Communications
    Presentation's date: 2013-06-26
    Presentation of work at congresses

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    In Long Term Evolution (LTE), the provision of Quality of Service (QoS) strongly depends on the ef¿ciency with which control resources are allocated. Unfortunately, the design of the control channel, the Physical Downlink Control Channel (PDCCH), is not ¿exible enough to support Intercell Interference Coordination (ICIC) and hence, its degradation at cell edges (a well known issue in LTE) severely jeopardizes system performance. This problem acquires especial relevance in realistic large scale deployments where Signal to Interference plus Noise Ratio (SINR) distributions are much worse than the ones predicted by means of hexagonal layouts. Thus, this paper investigates the challenge of improving SINR levels at cell edges in order to enhance the performance of the PDCCH. The proposed scheme adjusts the power allocated to the PDCCH at each cell in order to improve SINR distributions (minimizing the usage of control resources) and, due to its multiobjective nature, it considers several perspectives of the problem. The results show that gains in the order of 25% can be obtained in severely interfered cells while overall energy savings are around 50%.

  • Intercell interference coordination for the ePDCCH in LTE-advanced macrocellular deployments

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia
    International Conference on Wireless and Mobile Communications
    Presentation's date: 2013-07-25
    Presentation of work at congresses

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    This paper investigates several schemes to improve the performance of the enhanced Physical Downlink Control Channel (ePDCCH) in Long Term Evolution Advanced (LTEA) networks by means of Intercell Interference Coordination (ICIC). Given the flexible design of the ePDCCH, based on frequency division multiplexing, static ICIC techniques such as Soft Frequency Reuse (SFR) can be applied and hence, performance degradations at cell edges can be avoided in contrast to its antecesor, the Physical Downlink Control Channel (PDCCH) in LTE. The study is focused in realistic/irregular deployments, where the amount of intercell interference received at different cells varies considerably making very difficult the task of homogenizing the performance of the ePDCCH over the coverage area. In order to address this problem, the proposed multiobjective scheme adjusts the configuration of SFR at cell level. The problem formulation includes several performance metrics including spectral efficiency, cell edge performance, consumption/amount of control resources and energy requirements. The results reveal that the proposed scheme is able to (1) reduce the average consumption of control resources and, (2) minimize energy needs without penalizing the capacity of data channels.

  • Improved scheduling techniques for efficient uplink communications with carrier aggregation

     Lema Rosas, Maria Angel; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    Workshop on SON Algorithms for Energy Efficiency
    Presentation's date: 2013-05-28
    Presentation of work at congresses

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    Transmitted power in Long Term Evolution - Advanced (LTE-A) uplink (UL) is strongly related to the number of physical resource blocks (PRBs) allocated. As the transmitted bandwidth increases power does so. However, this rise in power is also required to increase throughput. It is necessary to create efficient techniques that allows sending more information (bits) with the same power requirements. Against previous LTE releases, LTE-A allows the use of non-contiguous resource allocation in the UL together with the simultaneous transmission along multiple component carriers named, carrier aggregation. These features lead to an increase in spectral efficiency thanks to ling performance gains obtained from frequency diversity. This work studies the effect of scheduling techniques on the throughput performance and power consumption of users. Results show that cell edge performance is very sensitive to the scheduling decisions, therefore, limitations in bandwidth are introduced in order to reduce power consumption and improve throughput. Carrier Aggregation turns out to be more efficient as users can be classified and improve spectral and energy efficiency.

  • Adapting fractional frequency reuse to realistic OFDMA cellular networks

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Lema, Maria A.; Lee, Dong Seop
    Wireless and Mobile Networking Conference
    Presentation's date: 2013-04-23
    Presentation of work at congresses

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    Effective intercell interference (ICI) mitigation has been identified as a key challenge for emerging OFDMA cellular technologies such as Long Term Evolution (LTE). In order to address this issue, mobile operators have adopted static Intercell Interference Coordination (ICIC) strategies, including Fractional Frequency Reuse (FFR), given their low complexity and easy implementation. However, recent results made evident the need for additional research efforts as the performance of FFR is poor in realistic cellular deployments. Thus, this paper presents a solution to this problem by means of a novel multiobjective optimization framework able to adapt FFR to any realistic cellular layout. By tuning the operational parameters of FFR at cell level, the proposed scheme succeeds in finding solutions outperforming reference schemes and baseline designs in terms of network capacity and cell edge performance while keeping energy consumption as low as possible.

  • Interoperability and sensor communications in Help4Mood: Personal monitoring system to support the treatment of depression

     Estevez Cruz, Soraya; Aragones, Carlos; Pérez Diaz de Cerio, David; Ruiz Boque, Silvia
    IADIS Multi Conference on Computer Science and Information Systems
    Presentation's date: 2013-07
    Presentation of work at congresses

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    Help4Mood aims to develop a platform to support the treatment of people with depression in their own home. Depression is one of the main causes of disability worldwide. For depression, it is essential to have a continuous control in order to check the patient status and avoid relapses. Thus, we propose Help4Mood, which is designed as a Personal Health System. It consists of a set of different wireless sensors whose data sink is centralized on a laptop and it is administered by a clinician that supports the treatment of depression. The outcome of the platform is available to the clinician in order to check the patient's status during the periodic appointments. The use of standards contributes to improve care delivery, optimize workflow and reduce ambiguity. For this reason Help4Mood is able to communicate with the Healthcare Provider using the standard of communications protocol Health Level Seven (HL7). In this work, we describe the main components, principal features of the Help4Mood and the results from the evaluation of the activity monitoring system on patients who had recovered from depression in Catalonia, Scotland and Romania. Updates caused by the results of the evaluation in the design of Wireless Sensor Network are included.

  • On the performance of LTE UL power control in realistic conditions

     Lema Rosas, Maria Angel; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering (LNICST)
    Date of publication: 2013-05-07
    Journal article

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    This paper deals with the interference control in the uplink (UL) of Long Term Evolution (LTE) systems. Although the multiple access technique allows an almost null intra-cell interference, the system is still sensitive to the inter-cell component caused by neighbouring cells. The UL power control proposed by the 3GPP is a means to reduce this interference. In this sense, user equipments (UE) establish an operation point (open loop power control or OLPC) to compensate the mean path loss and its slow variations. Additionally, this may be fine tuned by specific commands (closed loop). The current paper focuses on the performance of OLPC when deployed in realistic scenarios where heterogeneity is a key feature, both in the deployment of sites and in the concentration of users. The investigation is done in a comparative way, against a classic synthetic and regular scenario. Results indicate that the performance of the OLPC differs from the theoretical environment, due to the difference in the scenario nature. The summation of indoor coverage and guided path-loss results the urban scenario OLPC optimal point to lie in between two limits, one established by the reduced transmitted power fixed by the OLPC and the other by the interferences.

  • A metaheuristic-based downlink power allocation for LTE/LTE-A cellular deployments

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Lee, Dong Seop
    Wireless networks
    Date of publication: 2013-12-24
    Journal article

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    The explosive growth of cellular networks makes their deployment and maintenance more and more complex, time consuming, and expensive. Self-Organizing Networks have been recognized as a promising way to alleviate this problem by minimizing human intervention in such processes. This paper introduces a novel multiobjective framework, based on evolutionary optimization, aiming at improving network performance and users Quality of Service. By tuning the transmitted power at each cell, average intercell interference levels are minimized. The design of the proposed scheme is feasible for distributed implementations in Long Term Evolution (LTE) and LTE-Advanced networks and its operation is compatible with current specifications. The framework is able to provide effective network-specific optimization and obtained results show that gains in terms of network capacity and cell edge performance are 5 and 10 %, respectively. Energy savings always accompanied such enhancements with reductions up to 35 %.

  • Optimization of soft frequency reuse for irregular LTE macrocellular networks

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Lee, Dong Seop
    IEEE transactions on wireless communications
    Date of publication: 2013-05-29
    Journal article

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  • Best paper award of the 6th Joint IFIP Wireless and Mobile Networking Conference (WMNC'2013)

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Lema Rosas, Maria Angel; Lee, Dong Seop
    Award or recognition

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  • Best Paper Award of the 9th International Conference on Wireless and Mobile Communications (ICWMC 2013)

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia
    Award or recognition

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  • Resource management in 4G networks

     Ruiz Boque, Silvia; Cardona, Narcís; Hecker, Andreas; Garcia Lozano, Mario; Monserrat, José F.
    Date of publication: 2012
    Book chapter

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  • Help4Mood personal monitoring system: management of interoperatibilty in a wireless home for mental health treatment

     Castro, Juan Carlos; Estevez, Soraya; Aragonés, Carlos; Pérez Diaz de Cerio, David; Ruiz Boque, Silvia
    IADIS Multi Conference on Computer Science and Information Systems
    Presentation's date: 2012-07-18
    Presentation of work at congresses

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    Help4Mood is a project inside 7th European Framework Programme (FP7) for developing a computational distributed system to support remotely the treatment of patients with major depression at home. Core components are integrated with the ICE framework. One of the main goals of this system is to use the paradigm of a Virtual Agent to support the first symptoms of clinician alert of a patient, to interact with him an to prevent some causes of relapse after monitoring he/she with different sensors. The system processes inputs from different devices for monitoring patient activity at home and how he/she sleeps (also know as the Personal Monitoring System), transmitting this data to a Decision Support System, and defining how a Virtual Agent should interact with the patient before clinical support from hospital is needed if an alert is detected. This data is transmitted by a wireless network designed to improve data communication from sensors in a home environment (easy of installation and maintenance) and implemented using customized protocols and algorithms for reducing power consumption of these sensors. The technical framework is using open source implementations of ICE and HL7-standard-based healthcare integration engines to interact with the different subsystems. Particularly, the use of these standards will contribute to commercialization of the project results and the potential impact through the development, dissemination and use.

  • On the use of mutual information at bit level for accurate link abstraction in LTE with incremental redundancy H-ARQ

     Olmos Bonafé, Juan José; Serra, Albert; Ruiz Boque, Silvia; Latif, Imran
    European Cooperative in Science And Technology
    Presentation's date: 2012-09-25
    Presentation of work at congresses

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    Link abstraction methods are able to predict the BLER in multicarrier wideband systems using AMC techniques under multipath fading. The basic idea is to map the vector of the subcarrier SNR’s to a single scalar, the Effective SNR (ESNR), which is then used to predict the BLER. This procedure is important during real system operation, since the mobile terminal must report the Channel Quality Indicator (CQI) to the base station, and also for the system level simulators. In order to take into account H-ARQ, it is also interesting to predict the BLER after one or more IR retransmissions have happened. With IR H-ARQ there is an additional complexity, since the BLER performance of a given redundancy version (rv) depends on the SNR experienced by the receiver at current rv but also on the SNR of previously received rv's. We propose a novel link abstraction method that can predict the BLER with good accuracy in multipath fading and including the effects of H-ARQ retransmissions. The proposed method is based on estimating the mutual information between the transmitted bits and the received LLRs. We show that, by working at bit level, the effect of unequal error protection in 16 and 64QAM modulations is properly captured without resorting to any set of calibration constants. We also show how to reduce the set of reference BLER curves when working with multiple modulation and code schemes (MCS). Simulation results for LTE downlink with SISO transmission mode are included in the paper.

  • A novel ICIC-oriented channel state information feedback scheme for aperiodic reporting in LTE

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    European Cooperative in Science And Technology
    Presentation's date: 2012-02-08
    Presentation of work at congresses

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    In moderm OFDMA-based cellular networks, intercell interference is the main issue limiting the capacity of these systems. Recently, intensive research work has been focused on intercell interference coordination as it has been recognized as an important element to achieve seamless levels of quality of service. However, in most of the cases, this issue is addressed as a standalone issue. In this work, a novel channel state information feedback mechanism is proposed aiming at improving the system performance when static interference coordination techniques are also considered. By means of the proposed scheme, gains in terms of (1) users throughput, (2) cell edge performance and (3) energy efficiency are achieved with respect to existing aperiodic LTEbased mechanisms. Moreover, given the low complexity of the proposed solution, feasibility aspects are also discussed and a possible LTE implementation alternative is suggested.

  • An analytical view of static intercell interference coordination techniques in OFDMA networks

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    IEEE Wireless Communications and Networking Conference
    Presentation's date: 2012-04-02
    Presentation of work at congresses

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    This paper presents a novel methodology to assess the downlink performance of static intercell interference coordination techniques in the context of OFDMA-based cellular networks. In the last few years, interference mitigation techniques have been considered a research topic of utmost importance since intercell interference is the main issue limiting the capacity of modern cellular technologies such as LTE and WiMAX. The methodology presented in this paper should be understood not only as an analytical shortcut to foresee overall network interference conditions but also a mean to properly establish bounds to parameters associated to static intercell interference techniques operation. Moreover, the analysis allows to take into account both local large scale fading particularities and mobile operators’ preferences. In this sense, results show how the resulting set of preferred operational points is in general operatordependent and hence, the usefulness of the proposed framework is established.

  • A wireless sensor network design for the Help4Mood european project

     Pérez Diaz de Cerio, David; Ruiz Boque, Silvia; Rosell Ferrer, Francisco Javier; Ramos Castro, Juan Jose; Castro Robles, Joan Carles
    European Wireless Conference
    Presentation's date: 2012-04
    Presentation of work at congresses

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    Help4Mood is a closed loop approach supporting the control, communication and treatment management of patients with Major Depression. The first out of the three main components of the Help4Mood solution is the Personal Monitoring System (PMS), a set of different wireless sensors whose data sink is centralized on a laptop. The objective of this PMS is to monitor the activity of the patients, so several sensors have been chosen to cover the needs of different individuals. These include a wrist watch, a key ring, a waist/belt sensor, an under mattress sensor and a cellular phone. This paper describes the first prototype and the results obtained from this Wireless Sensor Network.

  • Improving channel state information feedback for static Intercell interference coordination in LTE

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    IEEE International Conference on Communications
    Presentation's date: 2012-06-12
    Presentation of work at congresses

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    Intercell Interference is the main issue limiting the capacity of modern OFDMA-based cellular networks. Recently, extensive research work has been focused on intercell interference coordination since it has been recognized as a key concept to achieve seamless levels of quality of service. Nevertheless, very often this problematic is addressed as a standalone issue. In this work, a novel channel state information feedback scheme is proposed aiming at improving the overall system performance when both channel state information and static interference coordination are jointly considered. By means of the proposed scheme, gains in terms of users throughput, cell edge performance and energy efficiency are achieved with respect to existing aperiodic LTE-based mechanisms without additional complexity.

  • On the role of downlink control information in the provision of QoS for NRT services in LTE

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    IEEE Vehicular Technology Conference
    Presentation's date: 2012-05-07
    Presentation of work at congresses

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    The provision of Quality of Service (QoS) to users of LTE networks depends to a large degree on the choice of an appropriate scheduling algorithm able to meet the requirements of mobile operators. Dynamic packet scheduling has been recognized as a key approach to maximize the utility of OFDMAbased systems due to its inherent ability to exploit the frequency selectiveness of wideband channels both in time and frequency domain. However, one of the main issues associated to dynamic scheduling is the high amount of signaling overhead required to provide users with resource allocation information. While the impact of control channel limitations on LTE VoIP capacity has been widely studied yet, tradeoffs associated to control channel usage and the provision of QoS for Non-Real Time (NRT) services has been basically omitted in current literature. In this paper, such tradeoffs have been addressed from several perspectives. Results show that the relationship between scheduling policies, offered levels of QoS (expressed in terms of guaranteed bit rates) and control channels capacity is not trivial and requires careful planning.

  • Help4Mood: testing and achievements of the first wireless sensor network prototype

     Pérez Diaz de Cerio, David; Ruiz Boque, Silvia; Rosell Ferrer, Francisco Javier; Ramos Castro, Juan Jose; Colomé Castellví, Josep Maria
    European Cooperative in Science And Technology
    Presentation's date: 2012-02-10
    Presentation of work at congresses

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    Help4Mood is a closed loop approach supporting the control, communication and treatment management of patients with Major Depression. The first out of the three main components of the Help4Mood solution is the Personal Monitoring System (PMS), a set of different wireless sensors whose data sink is centralized on a laptop. The objective of this PMS is to monitor the activity of the patients, so several sensors have been chosen to cover the needs of different individuals. These include a wrist watch, a key ring, a waist/belt sensor, an under mattress sensor and a cellular phone. This paper describes the first prototype and the results obtained from this Wireless Sensor Network

  • Optimization of realistic full frequency reuse OFDMA-based cellular networks

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José; Lee, Dong Seop
    IEEE International Symposium on Personal Indoor and Mobile Radio Communications
    Presentation's date: 2012-09-09
    Presentation of work at congresses

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    Nowadays mobile operators are planning and de- signing their mid/long term strategies based on new OFDMA- based cellular technologies such as LTE and WiMAX. Co-siting and re-utilization of existing facilities are within their roadmap in order to keep CAPEX as low as possible. Therefore, the optimization of OFDMA networks subject to fixed/previous (and usually suboptimal) coverage is mandatory. In addition, recently there is a great interest in reducing OPEX mainly by means of energy savings. This paper presents a novel multiobjective formulation aiming at improving the performance of OFDMA networks where full frequency reuse is employed. The proposed framework is flexible and results indicate that it is also effective as it improves both spectral efficiency and cell edge performance while it simultaneously reduces energy consumption.

  • On the performance of LTE UL power control in realistic conditions

     Lema, Maria A.; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    International ICST Conference on Mobile Networks and Management
    Presentation's date: 2012-09-24
    Presentation of work at congresses

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  • Improving soft frequency reuse for realistic OFDMA-based cellular deployments

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Lee, Dong Seop
    IEEE Global Communications Conference
    Presentation's date: 2012-12-04
    Presentation of work at congresses

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    Effective interference management is a technical challenge of utmost importance for emerging OFDMA-based technologies such as Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). Static Intercell Interference Coordination techniques including Soft Frequency Reuse (SFR) have enjoyed acceptance among mobile operators as a solution to deal with this problem mainly due to their low complexity and easy implementability. However, recent results indicate that the performance of default SFR settings directly applied to realistic cellular deployments is quite suboptimal and hence optimization is mandatory. This paper addresses this issue by presenting a novel multiobjective framework able to achieve accurate fine tuning of SFR and hence, enhance system capacity and cell edge performance while reducing energy consumption.

  • Admission control in LTE uplink systems with sounding reference signals based channel state indicator

     Lema, Maria A.; Ramon Ferran, Sergi; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    European Cooperative in Science And Technology
    Presentation's date: 2012-02-08
    Presentation of work at congresses

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    This article focuses on the investigation of the Admission Control techniques in order to assure Quality of Service (QoS) in Long Term Evolution (LTE) systems. So as to estimate the users bandwidth requirement, Sounding Reference Signals (SRS) bandwidth are allocated to each user in order to have accurate up-to-date channel state information at the evolved Node B (eNB). Since User Equipments (UEs) are power limited, several SRS are required to scan the full bandwidth for UEs with high path loss. Therefore, in order to own reliable information the eNB must trade-off up-to-date information and accuracy of the measurement. This paper investigates a novel way in which the eNB measures the users radio requirements in order to accomplish QoS, using the information on the SRS already known by the eNB. This measurement technique is compared against two models presented in [1], first a reference AC model in which users are accepted up to a cell bit-rate limit, and a second one proposed by the authors in which the users requirements are estimated using the power control formula and the Shannon capacity. The methodology followed is based on system level simulations. Results show that the SRS based AC is more optimist when estimating users channel conditions and therefore more users are accepted to the system, increasing the overall cell throughput when compared to the power control based algorithm.

  • Improving the Interplay between Periodic Channel State Information Feedback and Static Intercell Interference Coordination in LTE

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    Journal of communications
    Date of publication: 2012-09-01
    Journal article

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  • CROSS-LAYER DESIGN AND OPTIMIZATION OF MEDIUM ACCESS CONTROL PROTOCOLS FOR WLANS  Open access

     Kartsakli, Elli
    Defense's date: 2012-02-16
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    This thesis provides a contribution to the field of Medium Access Control (MAC) layer protocol design for wireless networks by proposing and evaluating mechanisms that enhance different aspects of the network performance. These enhancements are achieved through the exchange of information between different layers of the traditional protocol stack, a concept known as Cross-Layer (CL) design. The main thesis contributions are divided into two parts. The first part of the thesis introduces a novel MAC layer protocol named Distributed Queuing Collision Avoidance (DQCA). DQCA behaves as a reservation scheme that ensures collision-free data transmissions at the majority of the time and switches automatically to an Aloha-like random access mechanism when the traffic load is low. DQCA can be enriched by more advanced scheduling algorithms based on a CL dialogue between the MAC and other protocol layers, to provide higher throughput and Quality of Service (QoS) guarantees. The second part of the thesis explores a different challenge in MAC layer design, related to the ability of multiple antenna systems to offer point-to-multipoint communications. Some modifications to the recently approved IEEE 802.11n standard are proposed in order to handle simultaneous multiuser downlink transmissions. A number of multiuser MAC schemes that handle channel access and scheduling issues and provide mechanisms for feedback acquisition have been presented and evaluated. The obtained performance enhancements have been demonstrated with the help of both theoretical analysis and simulation obtained results.

  • Comunicaciones móviles eficientes basadas en redes heterogéneas y coordinación de interferencias

     Garcia Lozano, Mario; González González, David; Laya Romero, Andres Ernesto; Pérez Diaz de Cerio, David; Valenzuela Gonzalez, Jose Luis; Lema Rosas, Maria Angel; Ruiz Boque, Silvia; Alonso Zárate, Luis Gonzaga; Olmos Bonafé, Juan José
    Participation in a competitive project

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  • Simulation of LTE IR H-ARQ at system level using MIESM error prediction

     Olmos Bonafé, Juan José; Serra, Albert; Garcia Lozano, Mario; Ruiz Boque, Silvia; Pérez Diaz de Cerio, David
    European Cooperative in Science And Technology
    Presentation's date: 2011
    Presentation of work at congresses

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  • LTE UL power control evaluation in a system level simulator for synthetic and realistic scenarios

     Lema, Maria A.; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José; Pérez Diaz de Cerio, David
    European Cooperative in Science And Technology
    Presentation's date: 2011-10-19
    Presentation of work at congresses

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    The research involved in this study comprises the analysis of the impact of the power control algorithm and its performance in the system level. Following our work in TD 01040, the LTE system level simulator has been equipped with a power control block that enables interference management at the same time that controls the fairness among users. Rising from the fact that it is very sensitive to the environment, the algorithm is tested in two different scenarios in a comparative way. First, the conventional synthetic scenario, with regular hexagonal base stations distribution, and then a piece of the scenario of Vienna, developed during the COST 273 action in the MORANS initiative. This dissimilarity in simulation environment leads to strong differences in the system performance. Results show how the real scenario is not so sensitive to interferences and so that the major issue is the availability of transmission power at the cell edge.

  • Impact of downlink signaling capacity constraints on the provision of QoS in LTE

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    European Cooperative in Science And Technology
    Presentation's date: 2011-10-19
    Presentation of work at congresses

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    Choosing appropriate scheduling policies is of utmost importance to deliver acceptable levels of Quality of Service (QoS) to users of LTE networks. This decision is not only conditioned by the type of services expected to be offered but also by targeted QoS levels properly said. In this sense, preliminary performance evaluations depend to a large degree on the accuracy with which relevant practical system limitations are modelled. In LTE, the capacity of control channels is clearly one of the most important issues. While the impact of control channel limitations on LTE VoIP capacity has been widely studied yet, tradeoffs associated to control channel usage and the provision of QoS for Non-Real Time (NRT) services has been basically omitted in current literature. In this paper, several experiments have been conducted to investigate such interplay from different points of view. Results show that the relationship between scheduling policies, offered levels of QoS (expressed in terms of guaranteed bit rates) and control channels capacity is not trivial and requires careful planning.

  • Uplink system and link level simulation of 3GPP-LTE Rel. 8

     Lema, Maria A.; Garcia Lozano, Mario; Olmos Bonafé, Juan José; Ruiz Boque, Silvia
    European Cooperative in Science And Technology
    Presentation's date: 2011-06-20
    Presentation of work at congresses

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  • Help4Mood: a computational distributed system to support the treatment of patients with major depression

     Pérez Diaz de Cerio, David; Valenzuela Gonzalez, Jose Luis; Ruiz Boque, Silvia; Garcia Lozano, Mario; Colomé, Josep Maria
    European Cooperative in Science And Technology
    Presentation's date: 2011-06-20
    Presentation of work at congresses

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  • On the performance of static inter-cell interference coordination in realistic cellular layouts

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering (LNICST)
    Date of publication: 2011-05-25
    Journal article

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  • Metaheuristic procedure to optimize transmission delays in DVB-T single frequency networks

     Garcia Lozano, Mario; Lema, Maria Angel; Ruiz Boque, Silvia; Minerva, Flaminio
    IEEE transactions on broadcasting
    Date of publication: 2011-08-15
    Journal article

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  • An early stage training network in enabling technologies for GREEN radio

     Laya Romero, Andres Ernesto; Kartsakli, Elli; Olmos Bonafé, Juan José; Ruiz Boque, Silvia; Valenzuela Gonzalez, Jose Luis; Collado Gomez, Juan Carlos; Garcia Lozano, Mario; Alonso Zárate, Luis Gonzaga; Pérez Diaz de Cerio, David
    Participation in a competitive project

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  • 3GPP LTE: hacia la 4G móvil

     Cardona, Narcís; Olmos Bonafé, Juan José; Garcia Lozano, Mario; Monserrat, José F.; Cabrejas Peñuelas, Jorge; Calabuig Soler, Daniel; Fernández Aguilella, Ana; González González, David; Martín-Sacristán Gandía, David; Ruiz Boque, Silvia
    Date of publication: 2011-04-01
    Book

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  • Access to the full text
    Static inter-cell interference coordination techniques for LTE networks: a fair performance assessment  Open access

     González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    International Workshop on Multiple Access Communications
    Presentation's date: 2010-09-14
    Presentation of work at congresses

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    Link abstraction models based on mutual information for LTE downlink  Open access

     Olmos Bonafé, Juan José; Ruiz Boque, Silvia; Garcia Lozano, Mario; Martín Sacristán, David
    European Meeting COST 2100. Pervasive Mobile & Ambient Wireless Communications
    Presentation of work at congresses

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    Postprint (author’s final draft)

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    Metaheuristic proposal to minimize self-interference in single frequency networks  Open access

     Garcia Lozano, Mario; Ruiz Boque, Silvia; Lema, Maria A.; Torras, Evelyn; Olmos Bonafé, Juan José; Minerva, Flaminio
    European Meeting COST 2100. Pervasive Mobile & Ambient Wireless Communications
    Presentation of work at congresses

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  • Performance evaluation of static inter-cell interference coordination in realistic cellular layouts

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    European Cooperation in the Fiel of Scientific and Techinical Research
    Presentation of work at congresses

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    Effective interference management has been recognized by the industry and standardization bodies as a key enabler for 4G systems. This work is about static Inter-Cell Interference Coordination for OFDMA based cellular networks such as LTE. The majority of previous ICIC studies, both theoretical and simulation-based, have been conducted considering synthetic and/or small cellular layouts. In this work, the performance of static ICIC strategies in non-regular cellular layout is studied introducing some related RRM functions in the methodology. The overall performance assessment gives special attention to the efficiency vs. fairness tradeoff and the elements associated to it. Results show that the design of suitable and effective ICIC schemes for realistic cellular networks can not be done by simply extending classical approaches.

  • Access to the full text
    Performance evaluation of downlink interference coordination techniques in LTE networks  Open access

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José; Corvino, Virginia
    IEEE Vehicular Technology Conference
    Presentation's date: 2010-09-09
    Presentation of work at congresses

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  • On the performance of static inter-cell interference coordination in realistic cellular layouts

     González González, David; Garcia Lozano, Mario; Ruiz Boque, Silvia; Olmos Bonafé, Juan José
    International ICST Conference on Mobile Networks and Management
    Presentation's date: 2010-09-23
    Presentation of work at congresses

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    Effective interference management has been recognized by the industry and standardization bodies as a key enabler for 4G systems. This work is about static Inter-Cell Interference Coordination for OFDMA based cellular networks such as LTE. The majority of previous ICIC studies, both theoretical and simulation-based, have been conducted considering synthetic and/or small cellular layouts. In this work,the performance of static ICIC strategies in non-regular cellular layout is studied introducing some related RRM functions in the methodology. The overall performance assessment gives special attention to the efficiency vs. fairness tradeoff and the elements associated to it. Results show that the design of suitable and effective ICIC schemes for realistic cellular networks can not be done by simply extending classical approaches.

  • Access to the full text
    Static delays optimization to reduce self-interference in DVB-T networks  Open access

     Garcia Lozano, Mario; Ruiz Boque, Silvia; Minerva, Flaminio
    IEEE International Symposium on Broadband Multimedia Systems and Broadcasting
    Presentation's date: 2010-03-25
    Presentation of work at congresses

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  • ESTUDIO DE TÉCNICAS AVANZADAS DE CALIDAD DE SERVICIO Y CROSS-LAYERING PARA LA MEJORA DE REDES BASADAS EN EL ESTÁNDAR 802.11

     Pérez Diaz de Cerio, David
    Defense's date: 2010-12-17
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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