An efficient data transmission policy in an integrated voice-data ds-cdma network

CDMA schemes appear to be promising access techniques for coping with the requirements of third-generation mobile systems, mainly because of their flexibility. This paper proposes an adaptive S-ALOHA DS-CDMA access scheme as a method for integrating non-real time (i.e. Internet applications) and real-time (i.e. voice) services, by exploiting the potentials of CDMA under time-varying conditions. The adaptive component terminals autonomously change their transmission rate according to the total (voice+data) channel occupancy, so that the minimum possible data delay is almost always achieved.Peer 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

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

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

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

A novel autonomous RAT selection algorithm for non real time services

This paper proposes a new solution for autonomous decision-making in the RAT selection process in multi-service multi-access network scenarios. It is based on exploiting the time dimension in the RAT selection, so that, based on the current mobile terminal and network context and its future evolution, terminals can choose the appropriate initiation time to start a given transmission, waiting for the arrival to the coverage area of the most suitable RAT. The proposed strategy is claimed to have applicability for non-real time services without stringent deadline constraints (e.g. e-mails, downloading MP3 files, etc.). The algorithm is evaluated through simulations in different scenarios, revealing that it provides remarkable capacity increases, while at the same time ensuring that non real time transmissions do not exceed specific delay bounds.Postprint (published version

Optimization of multitenant radio admission control through a semi-Markov decision process

© 2019 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.Network slicing in future 5G systems enables the provision of multitenant networks in which a network infrastructure owned by an operator is shared among different tenants, such as mobile virtual operators, over-the-top providers or vertical market players. The support of network slicing within the radio access network requires the introduction of appropriate radio resource management functions to ensure that each tenant gets the required radio resources in accordance with the expected service level agreement (SLA). This paper addresses radio admission control (RAC) functionality in multiservice and multitenant scenarios as a mechanism for regulating the acceptance of new guaranteed bit rate service requests of different tenants. This paper proposes an optimization framework that models the RAC as a semi-Markov decision process and, as a result, derives an optimal decision-making policy that maximizes an average long-term function representing the desired optimization target. A reward function is proposed to capture the degree of tenant satisfaction with the received service in relation to the expected SLA, accounting for both the provision of excess capacity beyond the SLA and the cost associated with sporadic SLA breaches. The proposed approach is evaluated by means of simulations, and its superiority to other reference schemes in terms of reward and other key performance indicators is analyzed.Peer ReviewedPostprint (author's final draft

Adaptive S-ALOHA CDMA as an alternative way of integrating services in mobile environments

Code-division multiple-access (CDMA) schemes appear to be very promising access techniques for coping with the requirements of third-generation mobile systems, mainly because of their flexibility. This paper proposes an adaptive S-ALOHA DS-CDMA access scheme as a method for integrating nonreal-time (i.e., Internet applications) and real-time (i.e., voice) services in a multicell scenario by exploiting the potentials of CDMA under time-varying channel load conditions. The adaptive component makes data terminals autonomously change their transmission rate according to the total (voice+data) channel occupancy, so that the minimum possible data delay, which can be analytically obtained by defining a birth-death process, is almost always achieved. Moreover, by means of a simplified cellular model, the proposed algorithm revealed the same behavior, i.e., it tries to select the most suitable transmission rate at any time slot, when it is affected by intercell interference and even by power control imperfections. Finally, in order to gain more insight into the potentials of such an access strategy, the adaptive S-ALOHA CDMA scheme is then compared to a reservation time-division multiple-access (TDMA)-based protocol (PRMA++), showing the benefits of the CDMA-based solution in terms of capacity, flexibility, and data delay performance.Peer Reviewe

Issues on packet transmissioin strategies in a TDD-TD/CDMA scenario

This paper presents a packet transmission scheme that deals with the problems of a TDD CDMA scenario with different levels of frame structure asymmetry in adjacent base stations by distributing the users in the slots depending on their Time Advance. A multiple access protocol and a scheduling algorithm are also proposed to provide a certain degree of Quality of Service.Peer ReviewedPostprint (published version

SDN-based traffic engineering for improved resilience in integrated satellite-terrestrial backhaul networks

© 2017 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.Resilience and high availability are considered as essential requirements in 5G networks. To fullfil these requirements, the integration of a satellite component within mobile backhaul networks arises as a compelling proposition to provide backup connectivity to critical cell sites and divert traffic from congested areas so that a limited capacity in their terrestrial links could be supplemented during peak-time or even replaced in case of total/partial failure or maintenance. This is especially of interest for public protection and disaster relief (PPDR) communications in remote/rural areas that might require the fast deployment of nework capacity as well as in distressed areas where the terrestrial backhaul infrastructure might have suffered damages. This paper first describes an architectural framework that enables the integration and management of the satellite capacity as a constituent part of a Software Defined Networking (SDN) -based traffic engineered mobile backhaul network. Then, a SDN-based Traffic Engineering (TE) application is proposed to manage some amount of dynamically steerable satellite capacity provisioned for resilience purposes to maximize a network utility function under both failure and nonfailure conditions in the terrestrial links. Numerical results are presented to assess the benefits of the proposed TE application and its performance is compared to that of a traditional overflow solution.Peer ReviewedPostprint (author's final draft