Multi-Tone CDMA is a spectrum-efficient multiuser transmission technique, and regarded as a promising platform for multimedia communications. We study the multi-rate physical-layer transmissions, based on Multi-Code (MC) and Variable-Spreading-Length (VSL) access. A general and systematic system model accommodating both access methods with multiuser detections (MUD) is constructed, which is use...

In this paper, we explore the effects of various spreading codes chiefly GMW, WG and 3term sequences on interference levels in the multicarrier code-division multiple access (MC-CDMA) system. We evaluate the performances of these codes in terms of interference cancellation in differentsubcarrier systems. In the system, the data from the user is spreaded using a special sequence (code). The spre...

This paper presents a new algorithm that ensures low complexity implementation of a blind ST Rake receiver for DS-CDMA. The algorithm is applicable for both periodic and non-periodic spreading sequences provided that the system utilizes two layers of code separation: a spreading code layer and a scrambling code layer. The new method consists of two kinds of recursions: PAST recursions for a des...

This paper studies the trade-off between coding and direct-sequence spreading in a code-division multiple-access (CDMA) system, in the presence of errors in the delay estimate. One extreme is when all spreading is done by forward error correcting codes , referred to as code-spread CDMA (CS-CDMA) systems. CS-CDMA systems have been shown to achieve high capacity, assuming perfect channel knowledg...

Adaptive Array, with spatial processing, used in CDMA multiuser communications can enhance range, reliability and capacity. Moreover, the adaptive beamforming technologies can remove unwanted noise and interference from the received signal. In this paper, we propose four adaptive antenna receiver structures for DS/CDMA multiuser environment with multipath fading channels. LMS and RLS algorithms...

This paper analyzes the asymptotic performance of maximum likelihood (ML) channel estimation algorithms in wideband code division multiple access (WCDMA) scenarios. We concentrate on systems with periodic spreading sequences (period larger than or equal to the symbol span) where the transmitted signal contains a code division multiplexed pilot for channel estimation purposes. First, the asympto...

| 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...

wireless communication is the major form of connection nowadays. in most cases it exploits the benefits of the spread spectrum techniques to overcome channel introduced corruptions like doppler residual frequency, noise, interference and jamming. these techniques also enhance the security and quality of the link. using long spreading pseudo-noise codes provides further security for the link tho...

We consider a direct-sequence spread-spectrum multipleaccess network. It is widely known that the probability of symbol error in such a network is dependent on the carrier and spreading code chip phases of the interfering terminals with respect to the signal of interest. As a result, for a given total interference power, the performance is worse for the case of one strong interferer when compar...