Now showing items 1-20 of 78

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

      Pérez Romero, Jordi; Agustí Comes, Ramon; Sallent Roig, Oriol (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      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 ...
    • A direct-sequence spread-spectrum super-regenerative receiver 

      Moncunill Geniz, Francesc Xavier; Mas Casals, Orestes Miquel; Palà Schönwälder, Pere (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference lecture
      Open Access
      Current applications of the super-regenerative receiver use narrowband modulations. In this paper a new architecture that allows incoherent detection of spread-spectrum signals is presented. A pseudorandom code generator ...
    • A dynamic non-singleton fuzzy logic system for DS/CDMA communications 

      Pérez Neira, Ana Isabel; Sueiro, Jesús Cid; Roca, Josep; Lagunas Hernandez, Miguel A. (Institute of Electrical and Electronics Engineers (IEEE), 1998)
      Conference report
      Open Access
      We investigate a dynamic fuzzy logic system, specifically, its non-singleton generalization, and derive a novel adaptive fuzzy line enhancer that successfully solves the non-linear problem of narrowband interference (NBI) ...
    • A fast OFDM-CDMA user demultiplexing architecture 

      Marti Puig, Pere; Sala Álvarez, José (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      A fast algorithm based on a butterfly structure is presented that demultiplexes the symbols of a particular type of MC-MA (multi-carrier multiple-access) modulation previously proposed for indoor radio communications. A ...
    • A generic radio channel emulator to evaluate higher layer protocols in a CDMA system 

      Umbert Juliana, Anna; Díaz Romero, M. del Pilar (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      Currently, we are involved in the standardisation process to specify the next mobile system generation. A wideband code division multiple access (WCDMA) system is considered in most of the region versions. It would be very ...
    • A mobile controlled algorithm for improving the throughput in a s-aloha ds-cdma system 

      Sallent Roig, Oriol; Agustí Comes, Ramon (Institute of Electrical and Electronics Engineers (IEEE), 1996)
      Conference report
      Open Access
      This paper presents a novel adaptive DS-CDMA slotted-ALOHA packet random access scheme with transmitter-based spreading codes for mobiles. It is aimed at improving the throughput and message delay delivery when traffic ...
    • A near-optimum mac protocol based on the distributed queueing random access protocol (dqrap) for a cdma mobile communication system 

      Alonso Zárate, Luis Gonzaga; Agustí Comes, Ramon; Sallent Roig, Oriol (2000-09)
      Article
      Open Access
      This paper presents and analyses a new near– optimum random access protocol. The proposed access scheme is suitable for a CDMA environment and minimises the total number of spreading codes needed to achieve a certain ...
    • A near-optimum MAC protocol based on the distributed queueing random access protocol (DQRAP) for a CDMA mobile communication system 

      Alonso Zárate, Luis Gonzaga; Agustí Comes, Ramon; Sallent Roig, Oriol (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2000-09)
      Article
      Open Access
      This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The proposed access scheme is suitable for a CDMA mobile communication environment, and keeps under control and upper bounded the ...
    • A novel approach to security enhancement of chaotic DSSS systems 

      Nguyen, Xuan Quyen; Nguyen, Chuyen T.; Barlet Ros, Pere; Dojen, Reiner (Institute of Electrical and Electronics Engineers (IEEE), 2016)
      Conference report
      Open Access
      In this paper, we propose a novel approach to the enhancement of physical layer security for chaotic direct-sequence spread-spectrum (DSSS) communication systems. The main idea behind our proposal is to vary the symbol ...
    • A probabilistic method for blind multiuser detection using array observations 

      Antón Haro, Carles; Rodríguez Fonollosa, José Adrián; Rodríguez Fonollosa, Javier (IEEE, 1997)
      Conference report
      Open Access
      In this paper, a blind algorithm for detecting active users in a DS-CDMA system is presented. This probabilistic algorithm relies on the theory of hidden Markov models (HMM) and is completely blind in the sense that no ...
    • A proposal for an adaptive s-aloha access system for a mobile cdma environment 

      Sallent Roig, Oriol; Agustí Comes, Ramon (1998-08)
      Article
      Open Access
      This paper presents a novel adaptive direct-sequence code-division multiple-access (DS-CDMA) slotted-ALOHA (S-ALOHA) packet random-access scheme with transmitter-based spreading codes for mobiles. It is aimed at improving ...
    • A radio channel emulator for WCDMA, based on the hidden Markov model (HMM) 

      Umbert Juliana, Anna; Díaz Romero, M. del Pilar (Institute of Electrical and Electronics Engineers (IEEE), 2000)
      Conference report
      Open Access
      One of the main development and research subjects within the telecommunications area activity is the 3G mobile systems standardisation. The radio access is, of course, the main trouble in mobile systems, so it is important ...
    • Adaptive s-aloha cdma as an alternative way of integrating services in mobile environments 

      Sallent Roig, Oriol; Agustí Comes, Ramon (2000-05)
      Article
      Open Access
      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 CDMA as an alternative way of integrating services in mobile environments 

      Sallent Roig, Oriol; Agustí Comes, Ramon (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2000-05)
      Article
      Open Access
      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 schemes for packet data in a ds-cdma environment 

      Sallent Roig, Oriol; Agustí Comes, Ramon (IEEE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, INC., 1997)
      Conference report
      Open Access
      This paper presents a novel adaptive DS-CDMA slotted-ALOHA packet random access scheme for improving the throughput of the conventional DS-CDMA slotted-ALOHA system. For this purpose a mobile-assisted algorithm is envisaged ...
    • An efficient data transmission policy in an integrated voice-data ds-cdma network 

      Sallent Roig, Oriol; Agustí Comes, Ramon (IEEE Vehicular Technology Society, 1998)
      Conference report
      Open Access
      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 ...
    • An emulator framework for a new radio resource management for QoS guaranteed services in W-CDMA 

      Sallent Roig, Oriol; Pérez Romero, Jordi; Casadevall Palacio, Fernando José; Agustí Comes, Ramon (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2001-10)
      Article
      Open Access
      In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper ...
    • Analysis and design of the second order delay-lock loop in a CDMA system 

      Olmos Bonafé, Juan José; Agustí Comes, Ramon (. VEHICULAR TECHNOLOGY CONFERENCE'92, 1992)
      Conference report
      Open Access
      In code-division multiple access (CDMA) systems a delay-lock loop (DLL) is used to keep a fine alignment between sequences. A simulation program for the second-order DLL has been developed. The program allows an optimum ...
    • Analysis and evaluation of decentralized multiaccess Mac for ad-hoc networks 

      Pérez Neira, Ana Isabel; Realp, Marc (2003)
      Conference report
      Open Access
      In mobile ad-hoc radio networks, terminals are mobile and heterogeneous, the architecture of the network is continuously changing, communication links are packet oriented and radio resources are scarce. Therefore, ...
    • Analysis of a type II hybrid ARQ strategy in a DS-CDMA packet transmission environment 

      Pérez Romero, Jordi; Agustí Comes, Ramon; Sallent Roig, Oriol (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2003-08)
      Article
      Open Access
      A type II hybrid automatic repeat request scheme is considered as a retransmission strategy in a direct-sequence code-division multiple-access packet mobile radio network. An analysis based on equilibrium point analysis ...