2026-04-13T07:26:46Zhttps://recercat.cat/oai/request

oai:recercat.cat:2117/1172382026-01-24T03:49:32Zcom_2072_1033col_2072_452950

A proposal for an adaptive s-aloha access system for a mobile cdma environment Sallent Roig, Oriol Agustí Comes, Ramon Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Radiocomunicació i exploració electromagnètica::Comunicacions mòbils Intelligent transportation systems Forward error correction Access protocols Code division multiple access Packet radio networks Land mobile radio Spread spectrum communication Delays Markov processes Telecommunication traffic Sistemes de transport intel·ligent 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 throughput and message delay delivery when traffic load values below the saturation point of the conventional DS-CDMA S-ALOHA system are sensed in the channel. For this purpose, one mobile-station (MS) and two base-station (BS)-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 almost be reached at a low-complexity cost. A traffic model based on a realistic statistical length distribution of the messages illustrates how the delay delivery can be greatly reduced with the proposed algorithms. Finally, the impact of forward-error-correction (FEC) coding on the adaptive system is also studied. Peer Reviewed Postprint (published version) 1998-08 Article http://ieeexplore.ieee.org.recursos.biblioteca.upc.edu/document/704852/ Open Access