Waveform flexibility in database-oriented cognitive wireless systems

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper we discuss the idea of waveform flexibility in future wireless networks utilizing cognitive radio functionality. Mainly, we consider the possibility to adjust the shape of the waveform based on the information about the surrounding environment stored in a dedicated context-information database. In our approach, the cognitive terminal has an option to select one of four available waveforms to adapt itself in the best way to the constraints delivered by the database. In this paper we present the key concept of waveform flexibility, the proposed algorithm for waveform selection and the achieved simulation results.Peer ReviewedPostprint (author's final draft

Técnicas de ARQ en un esquema de acceso por paquetes DS-CDMA

Peer ReviewedPostprint (published version

DVB-T signal detection for indoor environments in low-SNR regime

The problem of coexistence between the primary (licensed) and secondary (non-licensed) users can be solved in various ways. One of them assumes the application of the detailed Radio Environment Maps being a kind of database, where some crucial information about the licensed transmission can be stored. In this paper we propose the new methods for signal detection in low signal-to-noise regime and compare it through hardware experiment with other known techniques used for spectrum sensing.Peer ReviewedPostprint (author’s final draft

ISMA-DS/CDMA MAC protocol for mobile packet radio networks

In this paper an ISMA-DS/CDMA MAC protocol for a packet transmission network is presented. The main feature of this protocol is its ability to retain the inherent flexibility of random access protocols while at the same time reducing to some extent the randomness in the access in order to increase the system capacity. In this framework, the protocol is adapted to a frame structure similar to that specified in the UTRA ETSI proposal for third generation mobile communication systems. Additionally, some adaptive mechanisms are proposed that improve protocol performance by means of varying the transmission bit rate according to the channel load that is broadcast by the base station. As a result, an adaptive bit rate algorithm is presented that reaches a throughput value close to the optimumPeer ReviewedPostprint (published version

A combined polling and ISMA-DS/CDMA protocol to provide QoS in packet mobile communications systems

This paper presents a new mechanism that combines the flexibility of an access protocol such as ISMA-DS/CDMA with the ability of a polling mechanism to provide a specific bound for the access delay. This protocol is proposed for a packet transmission mobile communication system together with a scheduling algorithm that arranges the different transmissions depending on the quality of service required by the set of considered services.Peer ReviewedPostprint (published version

Performance analysis of an ISMA DS-CDMA packet data network

The efficiency of MAC protocols for a packet switching DS-CDMA network strongly depends on the offered traffic statistic. For bursty sources where transmission needs are restricted to short message lengths, a protocol such as S-ALOHA can be efficient. However, for longer messages, a reduction in the randomness is required in order to improve the system performance. This improvement can be provided by a protocol such as ISMA when combined with the DS-CDMA technique. In this paper an analytical approach to modeling the resulting ISMA CDMA scheme is presented, and some design issues regarding the number of codes to be used are presented.Peer ReviewedPostprint (published version

On the value of context awareness for relay activation in beyond 5G radio access networks

This paper envisions to augment the Radio Access Network (RAN) infrastructure in Beyond 5G(B5G) systems by exploiting relaying capabilities of user equipment (UE) as a way to improve the coverage, capacity and robustness. Despite the concept and enabling technologies have been in place for some time, their efficient realization requires the conception and development of new features in B5G systems. Among them, this paper focuses on the Relay UE (RUE) activation decision making, in charge of deciding where and when a UE is suitable to be activated to relay traffic from other UEs. Specifically, the paper analyses seven RUE activation strategies that differ on the criteria and the type of context information considered for this decision-making problem. The considered strategies are evaluated through system level simulations in a realistic urban scenario with the objective of assessing the value of each type of context information. Results reveal that the most efficient strategies from the perspective of outage probability reduction are those that account for the number of UEs that would be served by a RUE based on the experienced spectral efficiency.This paper is part of ARTIST project (ref. PID2020-115104RB-I00) funded by MCIN/AEI/10.13039/ 501100011033.Peer ReviewedPostprint (author's final draft

Leveraging user equipment for radio access network augmentation

Along the successive generations, mobile network infrastructure deployments have required continuous expansion and upgrades to respond to the ever increasing traffic demand. At the same time, user equipment (UE) has evolved with the introduction of powerful and advanced communication and computational capabilities. Moreover, several industrial initiatives are promoting the principles of RAN disaggregation through the split of RAN functionalities among multiple interoperable components in contrast to traditional monolithic solutions. Embracing these trends, this paper presents the vision of a Beyond 5G (B5G) scenario where the UE takes a more active role in the communication service provisioning and is used to augment the RAN infrastructure as a source of distributed capacity and network intelligence. This is expected to bring benefits for Mobile Network Operators by reducing the number of base stations to deploy and by providing the RAN with a new degree of flexibility for smartly and dynamically adapting the RAN to the specific needs. In this direction, after discussing the main enabling technologies of the envisaged RAN augmentation concept, this paper presents a simulation-based assessment to quantify the performance improvements and the achievable savings in terms of infrastructure deployment.This paper is part of ARTIST project (ref. PID2020- 115104RB-I00) funded by MCIN/AEI/10.13039/ 501100011033.Peer ReviewedPostprint (author's final draft

Fundamentos de diseño y gestión de sistemas de comunicaciones móviles celulares

Descripció del recurs: 23 de setembre de 2014El libro pretende proporcionar al alumno una visión sintetizada sobre los conceptos fundamentales en que se sustenta el diseño de los actuales sistemas de comunicaciones móviles. Para ello, se abordan los contenidos progresivamente empezando por la caracterización del canal, a partir de la cual se presentan los parámetros de diseño que intervienen en el balance del enlace entre un transmisor y un receptor móviles así como las técnicas de ingeniería para hacer frente a los efectos del canal. A continuación, se presentan las técnicas de acceso por radio y los mecanismos de gestión de las mismas para permitir la compartición del canal por parte de múltiples transmisores y receptores. Finalmente, se plantean las comunicaciones móviles desde un punto de vista de sistema que involucra diferentes elementos de red para proporcionar servicios extremo a extremo y se presentan las metodologías de planificación y dimensionado de dichos sistemas

An efficient RAN slicing strategy for a heterogeneous network with eMBB and V2X services

Emerging 5G wireless technology will support services and use cases with vastly heterogeneous requirements. Network slicing, which allows composing multiple dedicated logical networks with specific functionality running on top of a common infrastructure, is introduced as a solution to cope with this heterogeneity. At the radio access network (RAN), the use of network slicing involves the assignment of radio resources to each slice in accordance with its expected requirements and functionalities. Therefore, RAN slicing will provide the required design flexibility and will be necessary for any network slicing solution. This paper investigates the RAN slicing problem for providing two generic services of 5G, namely enhanced mobile broadband (eMBB) and vehicle-to-everything (V2X). In this respect, we propose an efficient RAN slicing scheme based on an off-line reinforcement learning followed by a low-complexity heuristic algorithm, which allocates radio resources to different slices with the target of maximizing the resource utilization while ensuring the availability of resources to fulfill the requirements of the traffic of each RAN slice. A simulation-based analysis is presented to assess the performance of the proposed solution. The simulation results have shown that the proposed algorithm improves the network performance in terms of resource utilization, the latency of V2X services, achievable data rate, and outage probability.Peer ReviewedPostprint (published version