| The wideband code-division multiple access (CDMA) concept (FMA2) developed in the European FRAMES AC090 project supports variable data rate transmission. The data rate can be altered by changing either the spreading factor or by using multiple spreading codes in parallel. In order to facilitate exible changing of data rate, orthogonal Walsh codes are used for channel separation, followed by s...

In this report, we derive the performance graphs for UWB communication systems using different combining techniques in a RAKE Receiver. Comparisons have also been made between the techniques and conclusions have been drawn based on the requirements. We also incorporate the effect of number of fingers on the performance of the receivers. The results obtained give us way to evaluate the performan...

In this paper we proposed an analytical method which is used for 802.15.3a UWB channel to find out the effect of rake receiver finger with Maximal ratio combining (MRC) scheme. We used a mathematical model which is derived while considering the receiver is MRC rake receiver. In this receiver we assigned weights to rake receiver finger in such a way to maximize the signal to noise ratio (SNR). W...

We describe the results of a longitudinal study on five infants from age 12 to 20 months, presented with an out of reach toy and a rake-like tool within reach. Five conditions of spatial relationship between toy and rake were tested. Outcomes and types of behavior were analyzed. There were successes observed around 12 months in the condition of spatial contiguity between rake and toy, but these...

A differential space-time block code (DSTBC) modulation scheme is used to improve the performance of DS-CDMA systems in fast time-dispersive fading channels. The resulting scheme is referred to as the differential space-time block code modulation for DS-CDMA (DSTBC-CDMA) systems. The new modulation and demodulation schemes are especially studied for the down-link transmission of DS-CDMA systems...

Rake receiver can be implemented in any communication system, which has possibility of multipath components. Rake receiver can take advantage from these multipath components and combined all multipath components to achieve optimum result. The bit error rate (BER) performance of the Code Division Multiple Access (CDMA) cellular system based on IS-95 standard in the presence of an additive white ...

In this paper a Rake finger grid structure for direct-sequence code division multiple access (DS-CDMA) systems is analyzed as an alternative to the conventional Rake structure using individual fingers with timingand phasor tracking. The grid uses a group of equispaced Rake fingers in the delay domain. Each of the Rake fingers uses linear minimum mean-squared error (LMMSE) tap weight estimation ...

To achieve a better tracking of time-varying channel parameters, a structure using blind adaptive minimum output energy (MOE) detection in conjunction with a Rake combining diversity for direct-sequence code-division multiple-access (DS/CDMA) communications over the frequency selective multipath fading channels is introduced. In this MOE-RAKE structure, the signal replicas received from multipl...

An alternative method to channel estimation is presented as a means of supplying a RAKE receiver with the coefficients for Maximal Ratio Combining (MRC). The proposed RAKE receiver utilizes TimeHopping Pulse Position Modulation (TH-PPM), and is specifically designed to be used in Ultra Wideband (UWB) communication systems in which channel estimation becomes problematic because of the high sampl...

The frequencyand time-domain expressions are derived for the signal-to-noise power ratio (SNR) of an ideal Rake combiner output in a direct sequence spread spectrum (DSSS) mobile communication system. The derived SNR expressions make it possible to estimate the SNR statistics after Rake combining for an arbitrary spreading chip rate in the frequencyselective multipath channel. key words: spread...