Recently, overlap frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion which requires no guard interval (GI) insertion was proposed for signal transmission using multi-code direct sequence code division multiple access (DS-CDMA) in a frequency-selective fading channel. Another promising equalization technique is time-domain sliding-window chip equalization (SW...

Multi-user receivers in asynchronous Direct Sequence Code Division Multiple Access (DS-CDMA) systems require the knowledge of several parameters such as timing delay between users. The goal of this work is to present a QHDU IDU resistant joint multi-user synchronization and detection algorithm for DSCDMA systems. The solution is based on the Conditional Maximum Likelihood (CML) estimation metho...

This paper presents a novel Adaptive DSCDMA Slotted-ALOHA packet random access scheme with transmitter-based spreading codes for mobiles. It is aimed at improving the throughput and message delay delivery when traffic load values below the saturation point of the conventional DS-CDMA Slotted-ALOHA system are sensed in the channel. For this purpose, one Mobile and two Base Station assisted algor...

In this paper, we propose a new algorithm for joint time-delay and direction-of-arrival (DOA) estimation, here called two-dimensional code acquisition, in an asynchronous directsequence code-division multiple-access (DS-CDMA) array system. This algorithm depends on eigenvector-eigenvalue decomposition of sample correlation matrix, and requires to know desired user’s training sequence. The perfo...

A reduced complexity multiuser detector for DSCDMA is proposed for beyond 3G (B3G) systems with large bandwidth. We first argue that the resulting increase in intersymbol interference and data rate in B3G systems makes the computational load of multiuser receivers very high. Two solutions are proposed to reduce complexity. First, a frequency domain implementation of the RAKE receiver is describ...

In this paper we propose a blind interference cancellation (IC) receiver for asynchronous direct-sequence code-division multiple-access (DSCDMA) systems using a maximum mean energy (MME) optimization criterion. The simulation results show that this scheme offers performance gains over the well known blind receiver that is based on the minimum mean squared error (MMSE) optimization criterion. Ou...

A new method for frequency synchronization based upon Zero-Intermediate Frequency (Zero-IF) receiver and characteristics of the received signal’s power spectrum for MC-DSCDMA-Uplink system is proposed in this paper. In addition to this, employing Zero Correlation Zone (ZCZ) sequences, designed specifically for quasisynchronous uplink transmissions, is proposed to exploit frequency and temporal ...

The problem of estimating propagation delays of orthogonally modulated signals in asynchronous DSCDMA system over time-varing Rayleigh-fading channels is treated in this paper. The Maximum Likelihood (ML) estimator and its unaffordable complexity for implementation are discussed. Some suboptimal solutions, e.g., whitened sliding correlator, MMSE estimator, subspace-based estimator, approximate ...

Orthogonal and quasi-orthogonal codes are integral part of any DSCDMA based cellular systems. Orthogonal codes are ideal for use in perfectly synchronous scenario like downlink cellular communication. Quasi-orthogonal codes are preferred over orthogonal codes in the uplink communication where perfect synchronization cannot be achieved. In this paper, we attempt to compare orthogonal and quasi-o...

One of the promising techniques to allow highspeed data transmission with a limited bandwidth is multiinput multi-output (MIMO) multiplexing. As a signal separation scheme, an iterative frequency-domain interference cancellation (FD-IC) using two-dimensional minimum mean square error (2D-MMSE) frequencydomain equalization (FDE) was recently proposed. There are two types of FD-IC: parallel FD-IC...