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Adaptive S-ALOHA CDMA as an alternative way of integrating services in mobile environments
Sallent Roig, José Oriol; Agustí Comes, Ramon
Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions; Universitat Politècnica de Catalunya. GRCM - Grup de Recerca en Comunicacions Mòbils
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 Reviewed
Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Radiocomunicació i exploració electromagnètica::Comunicacions mòbils
Mobile communication systems
Adaptive systems
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
Sistemes de comunicacions mòbils

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