The paper aim was an investigation on use of chaotic sequence in DS-CDMA. The DS-CDMA systems offer physical layer security without the need for a significant increase in computation or power requirements. Nowadays, DSCDMA has been used widely. These systems suffers from multiple access interference because of other users transmitting in the cell, channel inter symbol interference and additive ...

In this contribution, we give an overview of the sensitivity of a number of multicarrier systems to carrier and symbol synchronization errors. A comparison is made between orthogonal frequency-division multiplexing/multiple access (OFDM(A)) and two combinations of the orthogonal multicarrier (MC) transmission technique with the code-division multiple access technique (CDMA), i.e. multicarrier C...

In this paper, we investigate the influence of different Walsh-Hadamard (WH) code allocation techniques on the performance of multi-carrier code division multiple access (CDMA) systems in the presence of high power amplifier (HPA) non-linearities. We consider two different multi-carrier CDMA schemes: multi-carrier CDMA (MCCDMA) and multi-carrier direct sequence CDMA (MC-DSCDMA) and analyse thei...

Code division multiple access (CDMA) using direct sequence (DS) spread spectrum modulation provides multiple access capability essentially thanks to the adoption of proper sequences as spreading codes. The ability of a DSCDMA receiver to detect the desired signal relies to a great extent on the auto-correlation properties of the spreading code associated to each user; on the other hand, multi-u...

The coherent reception of Direct Sequence Code Division Multiple Access(DSCDMA) signals in a multipath fading channel is considered. The channel model assumes independent paths with Nakagami fading statistics. This model includes the Rayleigh channel as a special case and a reasonable model for a frequency selective fading channel. The bit error rate(BER) performance of a RAKE receiver under va...

| An iterative detection and decoding algorithm is explored for a convolutionally coded DSCDMA system. The optimum decoding strategy is to consider the trellises of all the users simultaneously, but this has exponential complexity in the number of users. We use an iterative +multistage detection scheme combined with the MAP algorithm to reduce the complexity of the receiver without signi cant p...

This paper introduces a novel approach for considering the Dynamic Resource Allocation (DRA) in a multi-rate DS-CDMA wireless network supporting non realtime (NRT) communication. The allocated bit rate obeys to a user-centric approach by introducing a non-satisfaction user probability that has to be maintained below its targeted value while still keeping the best exploitation of the maximum ava...

Software Radios will have an important role in future terminal and base station definition. Although the ideal software radio architecture is highly restricted by technology, at present it is possible to build complex systems completely customised and reconfigurable using the FPGA devices. They provide to the designer the possibility to modify the hardware functional qualities without giving up...

The communication system under present study utilizing 1⁄2 rated convolutional encoding and interleaving schemes over an Additive White Gaussian Noise (AWGN) and other fading (Rayleigh and Rican) channels with deployment of Alamouti scheme. The simulation study is made with the development of a computer program written in MATLAB source code. Computer simulation results on BERs demonstrate that ...

Abstract— The paper investigates the application of a recently introduced learning technique, referred to as the relevance vector machine (RVM) to construct a block-adaptive kernel-based nonlinear multiuser detector (MUD) for direct-sequence code-division multiple-access (DSCDMA) signals transmitted through multipath channels. It is demonstrated that the RVM MUD is capable of closely matching t...