Commenced in January 2007
Paper Count: 31093
Interest of the Sequences Pseudo Noises Codes of Different Lengths for the Reduction from the Interference between Users of CDMA Network
Abstract:The third generation (3G) of cellular system adopted the spread spectrum as solution for the transmission of the data in the physical layer. Contrary to systems IS-95 or CDMAOne (systems with spread spectrum of the preceding generation), the new standard, called Universal Mobil Telecommunications System (UMTS), uses long codes in the down link. The system is conceived for the vocal communication and the transmission of the data. In particular, the down link is very important, because of the asymmetrical request of the data, i.e., more remote loading towards the mobiles than towards the basic station. Moreover, the UMTS uses for the down link an orthogonal spreading out with a variable factor of spreading out (OVSF for Orthogonal Variable Spreading Factor). This characteristic makes it possible to increase the flow of data of one or more users by reducing their factor of spreading out without changing the factor of spreading out of other users. In the current standard of the UMTS, two techniques to increase the performances of the down link were proposed, the diversity of sending antenna and the codes space-time. These two techniques fight only fainding. The receiver proposed for the mobil station is the RAKE, but one can imagine a receiver more sophisticated, able to reduce the interference between users and the impact of the coloured noise and interferences to narrow band. In this context, where the users have long codes synchronized with variable factor of spreading out and ignorance by the mobile of the other active codes/users, the use of the sequences of code pseudo-noises different lengths is presented in the form of one of the most appropriate solutions.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1058548Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1041
 Houda KHERDHER ? Mémoire pour grade de ma├«tre ès science : Effet des codes correcteurs d-erreurs sur les systèmes CDMA ├á taux multiples, Université Laval.
 Direct sequence spread spectrum sequences par Christophe Boulanger (Sagem-Paris, Rue Watt, 75013 Paris), Gérard Loubet (INPG/LIS, Campus Universitaire, 38402 St Martin D'heres), Jean René Lequepeys (CEA-LETI, CEA GRENOBLE, Rua des Martyrs, 38054 GRENOBLE) et Laurent Ouvry CEA-LETI, Cea Grenoble, Rua des Martyrs, 38054 Grenoble).
 Statistique d-ordre supérieur pour le traitement du signal, J.L.Lacoume, P.O.Ambland, P.Comon, (Masson, paris, 1997).
 Pursley, M.B., "Performance Evaluation for Phase-coded Spread- Spectrum Multiple-Acces Communication. Part 1: System Analysis". IEEE Transactions on Communications, Vol 1. COM-25. No. 8, pp. 795- 799, Ao├╣t 1977.
 Pursley, M.B. et Sarwate, D.V., "Performance Evaluation for Phasecoded Spread-Spectrum Multiple-Acces Comrnunication. Part 2: Code Sequence Analysis". IEEE Transactions on Communications, Vol. COM-25, No. 8, pp. 800-803, Ao├╣t 1977.
 Pursley, M.B. et ROEFS, H.F.A., "Numerical Evaluation of Correlation Parameters for Optimal Phases of Binary Shift-Register Sequences". IEEE Transactions on Communications, Vol. COM-27, NO. 10, pp. 1597- 1604, October 1979.
 Ottosson, T. et Svensson, A., "Multi-Rate Schemes in DS/CDMA Systems". Proc. IEEE VTC'95, Chicago, Juillet 1995.
 Analyse des systèmes linéaires (chapitre 1 ├á 4) Jean COAT et Jean- Marie Escane.