955 research outputs found
Adaptive algorithms for improving the throughput in an indoor mobile s-aloha ds-cdma system
This paper presents a novel Adaptive DSCDMA
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 load values below the
saturation point of the conventional DS-CDMA
Slotted-ALOHA system are sensed in the channel. For
this purpose, one Mobile and two Base Station assisted
algorithms are envisaged to control the change of the
transmission rate according to the traffic load. These
algorithms revealed that the optimum behavior,
obtained using a Markov Chain model, may be almost
reached at a low complexity cost.Peer ReviewedPostprint (published version
A mobile controlled algorithm for improving the throughput in a s-aloha ds-cdma system
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 load values below the saturation point of the conventional DS-CDMA slotted-ALOHA system are sensed in the channel. For this purpose a mobile assisted algorithm is envisaged to control the change of the transmission rate according to the traffic load. This algorithm revealed that the optimum behavior, obtained using a Markov chain model, may be almost reached at a low complexity cost. Moreover, priorities between mobiles could be easily established. Finally, a traffic model based on a realistic statistical length distribution of the messages illustrates how the delay delivery can be greatly reduced.Peer ReviewedPostprint (published version
Adaptive schemes for packet data in a ds-cdma environment
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 to control the change of the transmission rate according to the traffic load. This algorithm revealed that the optimum behavior may be almost reached at a low complexity cost. Moreover, the proposed algorithm was found to be robust to intercell interferencePeer ReviewedPostprint (published version
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
TĂ©cnicas de ARQ en un esquema de acceso por paquetes DS-CDMA
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
Buscando los orĂgenes: Don Antonio Blázquez y Delgado Aguilera, Historiador, GeĂłgrafo e Intendente Militar
This work responds to the idea of recovering the memory of figures whose contributions have been of interest for the development of geography in our country. Thus, D. Antonio Blázquez y Delgado Aguilera, geographer and historian, developed a major work about the geography, because it can be considered one of the introducers of the thought of Vidal de la Blache in Spain by participating in the Castilian translation of one of its most representative works. A prolific writer, left a number of publications, some of great scientific interested and development of geography in the late nineteenth century and early s. XX.El presente trabajo responde a la idea de recuperar la memoria de figuras cuyas contribuciones han sido de interĂ©s para el desarrollo de la GeografĂa en nuestro paĂs. AsĂ, D. Antonio Blázquez y Delgado Aguilera, GeĂłgrafo e historiador, desarrollĂł una labor importante en torno a la GeografĂa, por cuanto puede considerarse como uno de los introductores del pensamiento de Vidal de la Blache en España al haber participado en la traducciĂłn al castellano de una de sus obras más representativas. Autor prolĂfico, legĂł un buen nĂşmero de publicaciones, algunas de gran interĂ©s para el desarrollo cientĂfico de la GeografĂa de finales del s. XIX y principios del s. XX
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
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