http://hdl.handle.net/2117/7265 2013-06-19T06:48:51Z http://hdl.handle.net/2117/19328 Title: Simulation of LTE IR H-ARQ at system level using MIESM error prediction Authors: Olmos Bonafé, Juan José; Serra, Albert; García Lozano, Mario; Ruiz Boqué, Sílvia; Pérez Díaz de Cerio, David 2013-05-17T11:30:15Z http://hdl.handle.net/2117/18860 Title: Energy-efficiency evaluation of a medium access control protocol for cooperative ARQ Authors: Alonso Zárate, Jesús; Stavrou, Eirini; Stamou, Adamantia; Angelidis, Pantelis; Alonso Zárate, Luis Gonzaga; Verikoukis, Christos Abstract: We present in this paper the evaluation of the energy consumption of PRCSMA, an 802.11-based medium access control protocol designed to coordinate the retransmissions from the relays in a wireless network implementing a Cooperative Automatic Retransmission Request (C-ARQ) scheme. A comparison in terms of energy efficiency with non-cooperative ARQ schemes (retransmissions performed only from the source) and with ideal C-ARQ (with perfect scheduling among the relays) is included in this paper. The main results show the conditions under which a C-ARQ scheme with PRCSMA outperforms, in terms of energy efficiency, non-cooperative ARQ schemes and also show that the overhead of the MAC layer cannot be neglected in order to accurately evaluate the performance of a C-ARQ scheme. Description: Best Paper Award in Communications QoS, Reliability and Modelling. IEEE ICC 2011 2013-04-18T09:57:56Z http://hdl.handle.net/2117/18796 Title: Analysis of the hidden and exposed terminal effects in wireless networks with cooperative ARQ Authors: Alonso-Zarate, J.; Alonso Zárate, Luis Gonzaga; Kormentzas, Georgios; Verikoukis, Christos Abstract: Cooperative Automatic Retransmission Request (C-ARQ) schemes allow those users which overhear a transmission to act as spontaneous relays when a packet has been received with errors at destination. When these users assist a source-destination pair in the retransmission process, the area exposed to the original transmission increases in comparison with non-cooperative ARQ schemes. In addition, the extension of the transmission time, due to the retransmissions, increases the vulnerability of a transmission to the hidden terminal problem. The paper provides a performance analysis of the hidden and exposed terminal effects in an 802.11-based wireless network where a C-ARQ scheme is executed at the Medium Access Control (MAC) layer. The presented analysis is supported by computer-based simulations. 2013-04-15T14:15:59Z http://hdl.handle.net/2117/18762 Title: Multi-radio cooperative retransmission scheme for reliable machine-to-machine multicast services Authors: Laya Romero, Andrés Ernesto; Wang, Kun; Alonso Zárate, Luis Gonzaga; Alonso Zárate, Jesús Abstract: Mobile Machine-to-Machine (M2M) market is expected to grow dramatically in the upcoming years; predictions agree that the majority of wireless traffic will correspond to this type of communication. M2M devices deployed in proximity to each other might be handled as groups or clusters when sharing the same communication attributes and serving to achieve joint target. Moreover, devices that feature multiple radio interfaces are commonly used nowadays; they can be connected to a cellular access network, e.g., LTE, and simultaneously to a short-range network, also known as capillary network, among surrounding devices, e.g., Wi-Fi and ZigBee. For services such as over-the-air (OTA) firmware update, the same information shall be sent to all the group members over the cellular access network. A Multi-Radio Cooperative Retransmission Scheme for Reliable Multicast Services is presented as a solution to reliably manage reception errors occurred over the cellular network; by carrying out retransmissions over a short-range network it is possible to reduce both the traffic load over the cellular link and the energy consumption in error recovery. Ns-3 simulations were performed with LTE network models to analyze the scheme in terms of energy consumption and prove its usefulness in autonomous, battery driven, devices. 2013-04-10T16:17:35Z http://hdl.handle.net/2117/18654 Title: Improved scheduling decisions for LTE-A uplink based on MPR information Authors: Lema, Maria A.; García Lozano, Mario; Ruiz Boqué, Sílvia; Olmos Bonafé, Juan José Abstract: 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 2013-04-05T15:27:25Z http://hdl.handle.net/2117/18578 Title: Analysis of energy efficient distributed neighbour discovery mechanisms for machine-to-machine networks Authors: Vazquez, Francisco; Alonso-Zarate, J.; Alonso Zárate, Luis Gonzaga; Dohler, Mischa Abstract: Energy efficiency is one of the main challenges of Machine-to-Machine (M2M) networks, since they aim at connecting devices with limited access to power sources and operate without human intervention. It has been shown in the past that the use of short-range cooperation between wireless devices equipped with multiple Radio Access Technologies (RATs) can achieve energy savings and extend the lifetime of cellular wireless networks. Devices with cellular connectivity can become temporary gateways to provide energy-constrained devices within the short-range cluster with access to the long range cellular infrastructure. To this end, the devices need to discover their neighbours using their short-range radio interface to identify and select potential gateway candidates. Existing neighbour discovery mechanisms perform poorly in terms of delay and energy consumption to maintain, continuously at each device, complete neighbourhood information, and thus may not be suitable for energy-constrained M2M networks. In this paper, we focus on distributed neighbour discovery mechanisms that are initiated dynamically and spontaneously by a single device to discover only its single-hop neighbours. We formulate accurate delay and energy models of three discovery mechanisms based on frame slotted-ALOHA and contention tree algorithms, and compare their performance in terms of delay and energy consumption. 2013-04-03T14:15:55Z http://hdl.handle.net/2117/18254 Title: Modelling channel estimation error in LTE link level simulations Authors: Serra, Albert; Olmos Bonafé, Juan José; Lema Rosas, María Ángel Abstract: Channel estimation is a key aspect for the performance of the physical layer in all MIMO-OFDM systems. In order to obtain realistic performance assessments from the LTE link level simulator, channel estimation errors must be taken into account. Implementing a detailed channel estimation algorithm may lead to long simulation time, in particular for wideband MIMO transmission modes where many channels have to be estimated, and for procedures like Wiener filtering which require matrix multiplications. In this paper we propose to simulate channel estimation errors by a Gaussian additive noise error model. The noise variance of the model is calibrated as a function of the received SNR for different channel models and Doppler spreads. The model is validated by comparing the BLER curves obtained with the model with the curves obtained when using real channel estimation. 2013-03-13T10:39:31Z http://hdl.handle.net/2117/18109 Title: Optimization of realistic full frequency reuse OFDMA-based cellular networks Authors: González González, David; García Lozano, Mario; Ruiz Boqué, Sílvia; Olmos Bonafé, Juan José; Lee, Dong Seop Abstract: 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. 2013-03-06T15:09:28Z http://hdl.handle.net/2117/17899 Title: Help4Mood: testing and achievements of the first wireless sensor network prototype Authors: Pérez Díaz de Cerio, David; Ruiz Boqué, Sílvia; Rosell Ferrer, Francisco Javier; Ramos Castro, Juan José; Colomé Castellví, Josep Maria Abstract: 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 2013-02-20T16:51:31Z http://hdl.handle.net/2117/17887 Title: Improving soft frequency reuse for realistic OFDMA-based cellular deployments Authors: González González, David; García Lozano, Mario; Ruiz Boqué, Sílvia; Lee, DongSeop Abstract: 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. 2013-02-19T15:51:57Z http://hdl.handle.net/2117/17723 Title: A wireless sensor network design for the Help4Mood european project Authors: Pérez Díaz de Cerio, David; Ruiz Boqué, Sílvia; Rosell Ferrer, Francisco Javier; Ramos Castro, Juan José; Castro Robles, Joan Carles Abstract: 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. 2013-02-13T14:33:25Z http://hdl.handle.net/2117/17512 Title: Help4Mood personal monitoring system: management of interoperatibilty in a wireless home for mental health treatment Authors: Castro, Juan Carlos; Estevez, Soraya; Aragonés, Carlos; Pérez Díaz de Cerio, David; Ruiz Boqué, Sílvia Abstract: 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. 2013-01-24T16:26:25Z http://hdl.handle.net/2117/17505 Title: Improving channel state information feedback for static Intercell interference coordination in LTE Authors: González González, David; García Lozano, Mario; Ruiz Boqué, Sílvia; Olmos Bonafé, Juan José Abstract: 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. 2013-01-23T17:33:44Z http://hdl.handle.net/2117/17504 Title: "Green" distance-aware base station sleeping algorithm in LTE-advanced Authors: Bousia, Alexandra; Antonopoulos, Angelos; Alonso Zárate, Luis Gonzaga; Verikoukis, Christos Abstract: In this paper, we propose a switch on/off algorithm for Base Stations (BSs), which exploits the knowledge of the distance between the User Equipments (UEs) and their associated BS. Our novel approach hopes to provide an improvement to the problem of energy consumption. The major concern lies on reducing the energy consumption of the telecommunication networks by optimizing the power utilization without sacrificing the offered Quality of Service (QoS). Our proposed scheme achieves a significant power saving, based on switching off the Base Stations that are underutilized during low traffic periods (especially during night) in the LTE-Advanced. 2013-01-23T17:25:58Z http://hdl.handle.net/2117/17413 Title: Experimental study of bluetooth, ZigBee and IEEE 802.15.4 technologies on board high-speed trains Authors: Higuera Portilla, Jorge Eduardo; Kartsakli, Elli; Valenzuela González, José Luis; Alonso Zárate, Luis Gonzaga; Laya Romero, Andrés Ernesto; Martínez, Raquel; Aguilar, Alicia Abstract: This paper studies the feasibility of using low-power wireless technologies such as Bluetooth, IEEE 802.15.4 and ZigBee in high-speed railway scenarios that involve bidirectional ground-to-train communication. The presented results have been obtained through experimental tests conducted at the Madrid- Barcelona high-speed rail line. A multiplatform communication system has been installed in a high-speed train, circulating at velocities up to 300 km/h, whereas autonomous devices have been disseminated along of the railway path to communicate with the onboard devices. The conclusions drawn from this work will be used as guidelines for the future implementation of autonomous communication platforms for high-speed rail connectivity. 2013-01-17T19:28:24Z