In this paper, we study a recently proposed multirate system, called wavelet based scale-code division multiple access (W/S-CDMA). W/S-CDMA depends on the code, time and scale orthogonality introduced by pseudo-noise (PN) sequences, and wavelets. In this system, the channel is partitioned into different scales, and each scale into time slots. In addition, the PN sequences are used in each scale...

In this paper, we consider the effect of impulsive noise on the performance of multicarrier code division multiple access (MC-CDMA) systems and analyze the performance by examining the MC-CDMA system model in time domain. We have discovered that conventional Walsh-code based MC-CDMA is less robust to the presence of impulsive noise than the corresponding direct sequence (DS) CDMA and multicarri...

In this paper a power control techniques for CDMA system is presented. Power control is the most important system requirement for CDMA systems. For CDMA system to function effectively, we need to control the power; if power control is not implemented many problems such as the near-far effect will start to dominate and consequently will lower the capacity of the CDMA system. However, when the po...

Multicarrier code-division multiple-access is one of the effective techniques to gain its multiple access capability, robustness against fading, and to mitigate the ISI.In this paper, we propose an improved mulcarrier CDMA system with adaptive subchannel allocation. We analyzed the performance of our proposed system in frequency selective fading environment with narrowband interference existing...

In this paper, a code-division multiple access (CDMA) cellular overlay system is investigated, employing the idea of multicarrier CDMA, which has recently received significant attention as an alternative to traditional single-carrier CDMA [1]. Overlay is pursued here as a means of long-term transition from narrowband cellular to CDMA cellular. A major result of this paper is the demonstration t...

In this article we identify some of the key problems that may be encountered when designing a broadband multiple access system with bandwidth on the order of tens or even hundreds of megahertz. We commence with a comparative discussion in terms of the characteristics of three typical code-division multiple access schemes: single-carrier directsequence CDMA (SC DS-CDMA), multicarrier CDMA (MC-CD...

In this contribution, we have studied the performance of a Turbo-Coded (TC) Code Division Multiple Access (CDMA) based two-way relaying scheme. More explicitly, we employ a seven-user CDMA model, where two of the CDMA users are communicating with each other with the aid of an additional relay node, while the other five CDMA users are interferers. More explicitly, two CDMA users exchange their i...

Parallel simulation has not been widely accepted by the simulation practitioners due to the lack of language support and tools necessary for developing eecient parallel simulators. This paper describes the design of SPaDES (Structured Parallel Discrete-Event Simulation), a struc-tured parallel simulation workbench for developing portable simulation models, and a platform for designing experimen...

This paper describes a CSIM-based simulation tool, called MultiSim, which allows eecient simulation of large-scale mul-tiprocessors. Methods are described for simulating several variations of wormhole routing, including multicast communication , the use of variable-sized buuers at routers within the network, and the use of virtual channels. The key to eecient simulation of such networks is that...