Performance Of An Adaptive Space-time Processing Receiver For The User Terminal Of 3g Wcdma Systems Under Cost-259 Channel Models

This paper presents an adaptive multi-target space-time architecture for downlink receivers in the user terminal of WCDMA systems under soft handoff. The receiver consists of M antennas and K array processors, each one followed by a chip-rate equalizer and a despreader. The resulting signals from these K branches are combined in an adaptive ratio combiner which is updated by the common channel information in UTRA FDD systems. When a large number of antennas is used each array processor is able to collect a given target ray and filter out all the others. On the other hand, when only a small number of antennas is used, due to cost or physical limitation, the chip-rate equalizers try to eliminate the residual interchip interference that strongly affects receiver performance. In both cases an efficient coherent receiver is obtained that exploits the space and time diversity in the incoming signal at the user terminal. All the signal structure of the FDD WCDMA downlink signal is exploited for improved performance. Simulation results using COST-259 channel models for vehicle speed of 50 km/h are compared with results obtained for a difficult hypothetical fixed channel condition.5615761(2000) Third Generation Mobile Communication Systems, , R. Prasad, W. Mohrand, W. Konhäuser, EditorsArtech House, Boston, USA(2001) UMTS: Mobile Communications for the Future, , F. Muratore, EditorJohn Wiley & Sons Ltd., Chichester, EnglandLiberti J.C., Jr., Rappaport, T.S., (1999) Smart Antennas for Wireless Communications: IS-95 and Third Generation CDMA Applications, , Prentice-Hall PTR, New JerseyAndersson, S., Adaptive antennas for GSM and TDMA (IS-136) systems (2002) Handbook of Antennas in Wireless Communications, pp. 24/1-24/33. , CRC Press, USAKarlsson, J., Mazur, S., Interference suppression in CDMA mobile stations using multiple antennas Proc. of the 7th IEEE Int. Conf. on Universal Personal Communications, Firenze, Italy, October 1998Ramos, J., Zoltowski, M.D., Liu, H., Low-complexity space-time processor for DS-CDMA communications (2000) IEEE Trans. on Signal Processing, 48 (1), pp. 39-52. , JanuaryWinters, J.H., Smart antennas for wireless systems (1998) IEEE Personal Comm., Mag., pp. 23-27. , FebruaryMeyr, H., Moeneclaey, M., Fechtel, S., (1998) Digital Communication Receivers: Synchoronization, Channel Estimation and Signal Processing, , John Wiley & SonsPaulraj, A., Papadias, C., Space-time models for wireless personal communications (1998) IEEE Signal Processing Mag., pp. 49-83. , FebruaryGodara, L.C., Application of antenna arrays to mobile communications, part I: Performance improvement, feasibility, and system considerations (1997) Proceedings of the IEEE, 85 (7). , JulyGodara, L.C., Application of antenna arrays to mobile communications, part II: Beam-forming and direction of arrival considerations (1997) Proceedings of the IEEE, 85, p. 8. , AugustJanaswamy, R., Spatial diversity for wireless communications (2002) Handbook of Antennas in Wireless Communications, pp. 19/1-19/24. , CRC Press, USAUniversal mobile telecommunications system (UMTS)physical layer - General description 3G TS 25.201Correia, L.M., (2001) Wireless Flexible Personalized Communications, , Wiley & Son