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...

Recently, an optimum structure of the discrete time Rake receiver according to the maximum a posteriori criterion has been proposed. The obtained receiver, known as the decorrelating discrete time Rake receiver (DDRR), uses estimates of the channel statistics in order to compute its decision variable. In this letter, we study the DDRR robustness in the presence of dynamic statistics due to birt...

For the reception of multicode direct sequence (DS)-CDMA signals, the MMSE frequency domain equalisation is applied instead of RAKE combining. The achievable BER performance in a frequency selective Rayleigh fading channel is evaluated by computer simulation. It is shown by computer simulation that the DS-CDMA with MMSE frequency domain equalisation outperforms the DS-CDMA with RAKE combining a...

Wideband CDMA systems with orthogonal spreading codes suffer severely due to the loss of orthogonality by multipath propagation. This yields Multiple Access Interference (MAI) which gravely reduces the performance of classical systems with Rake-receivers. In our approach we attempt to restore orthogonality again by using a fractional T-equalizer. The results are compared with a system using the...

We propose a novel scheme of subband adaptive array (SBAA) for direct-sequence code division multiple access (DS-CDMA). The scheme exploits the spreading code and pilot signal as the reference signal to estimate the propagation channel. Moreover, instead of combining the array outputs at each output tap using a synthesis filter and then despreading them, we despread directly the array outputs a...

Acoustic communications using a direct-sequence spread spectrum modulation with a RAKE receiver was tested during the KauaiEx experiment (in Hawaii). The oceanography was measured along the communications path during this test, so that the propagation of the communications transmissions could be subsequently modeled. Such simultaneous measurements provide a continuous picture of how the ocean w...

We investigate precoding of the information symbols before spreading for downlink DS-CDMA systems subject to multipath fading. With precoding, a conventional receiver (RAKE) can achieve performance comparable to other suboptimal multiuser receivers, e.g. MMSE and ZF. We extend the work in [1] regarding constrained precoding for multipath channels and present closed form solutions. Through simul...

3G mobile devices and base stations employ rake receivers. An important issue in the design of such receivers is finger allocation. This paper explores the relationship between finger placement and the correlation properties of rake combined signals. The dependence of correlation coefficients on system parameters such as the multipath characteristics of the propagation channel, the number of us...

The simulation of nanometric cutting of copper with diamond cutting tools, with the Molecular Dynamics method is considered. A 2D model of orthogonal nano-scale cutting is presented and the influence of the depth of cut and tool rake angle on chip morphology and cutting forces is investigated. For the analysis, three different depths of cut, namely 10Å, 15Å and 20 Å and four tool rake angles, n...

model, a RAKE receiver can be used to detect the signal from the multipath fading channel. the tap weights were assumed known when deriving RAKE receiver, but in practice a correlator is used to estimate the tap weights. Multipath fading is one of the major practical concernS in communications. Multipath problem always exists in mobile environment, especially for m~ bile unit which is often emb...