Space-time front-ends for RAKE receivers in the FDD mode of UTRA 1

A unified and general vision of different space-time processors is presented. Many popular receivers can be accomodated, like V-RAKE receivers, weighted V-RAKE, or spatial narrowband beamforming. By making appropriate assumptions on the space/time characteristic of the interference it is possible to enhance the performance of the receiver through spatial/temporal pre-processors. These receivers will be tested in the FDD mode of UTRA. I. Introduction The advent of the 3rd generation of mobile communications systems has been accompanied by the recognition of the large increase in system capacity that can be obtained from the use of adaptive antenna arrays. Care has been taken in the definition of the standard to include capabilities for space-time processing of the signals incoming and radiated from the base stations. Section II reviews the main characteristics of the European proposed air interface (UMTS). Section III presents the signal model. In section IV the different space-time receivers are presented in a unified vision. It will be seen that the use of multiple antennas and the temporal correlation diversity of multiple users allow additional degrees of freedom for cancellation of multiple access interference. Only single user approaches will be introduced although some ideas are easily extendable to the multiuser case. All these receivers need a reliable estimate of the correlation properties of the interferences, so different options are presented in section V. Performances are compared in terms of probability of error in section VI. II. UTRA FDD uplink air interface