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Título:	Adaptive S-ALOHA CDMA as an alternative way of integrating services in mobile environments
Autor/a:	Sallent Roig, José Oriol; Agustí Comes, Ramon
Otros autores:	Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions; Universitat Politècnica de Catalunya. GRCM - Grup de Recerca en Comunicacions Mòbils
Abstract:	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.
Abstract:	Peer Reviewed
Materia(s):	-Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Radiocomunicació i exploració electromagnètica::Comunicacions mòbils -Mobile communication systems -Adaptive systems -Adaptive S-ALOHA DS-CDMA -Birth-death process -Cellular model -Cellular radio -Channel occupancy -Code division multiple access -Data delay performance -Data terminals -Integrated voice/data communication -Intercell interference -Mobile environments -Multicell system -Multiuser channels -Nonreal-time services -Packet reservation multiple access -Power control imperfections -Radiofrequency interference -Real-time services -Reservation time-division multiple-access -Services integration -TDMA-based protocol -Telecommunication services -Third-generation mobile systems -Time division multiple access -Time-varying channel load -Transmission rate -Voice services -CDMA -PRMA++ -Sistemes de comunicacions mòbils
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Tipo de documento:	Artículo
Editor:	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
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