Multicarrier Code Division Multiple Access Schemes (MC-CDMA) have been recently introduced in existing CDMA based systems to improve security, data transmission rate and to minimize Inter Symbol Interference (ISI). CDMA experiences severe multipath fading which badly affects its performance. By transmitting identical narrowband DirectSequence (DS) waveforms using frequency diversity, in paralle...

A hybrid pulse interval modulation – code division multiple access (PIM-CDMA) is proposed. Expression for bit error rate (BER) is given. Numerical results presented are compared with hybrid PPM-CDMA and OOK-CDMA schemes. For a low number of users PIM-CDMA achieves similar and marginally lower BER performance compared with PPM-CDMA and OOK-CDMA, respectively. For large number users it offers bet...

Low signal to noise ratio (SNR) channels require careful design of communication systems in order operate reliably such extreme channels. Special measures and techniques must be considered when designing for environments counteract the effect high power. Channel coding is a powerful tool aid against adverse channel conditions including low SNR. Coupling with spreading technique can further stre...

The need for a communication system with higher data rate and mobility grows along information technology development. Combining MC-CDMA the MIMO supporting good transmit diversity technique is promising idea to provide needed system, especially in high conditions. can support ubiquitous communications without affecting achievable BER more capable of high-speed mobility. It integrates benefit b...

Orthogonal sequences can be assigned to a regular tessellation of hexagonal cells, typical for synchronised code-division multiple-access (S-CDMA) systems. The within any cell should both orthogonal in the adjacent cells and require sufficient number users each cell. However, binary sequences, capacity communication system is limited. So, new family non-binary constructed, which has more per th...

This paper introduces the principles of interferometry to multicarrier code division multiple access (MC-CDMA). Specifically, we propose the use of MC-CDMA with novel carrier interferometry (CI) complex spreading codes. The CI/MC-CDMA method, applied to mobile wireless communication systems, offers enhanced performance and flexibility relative to MC-CDMA with conventional spreading codes. Speci...

Abstract OFDM, MC-CDMA and DS-CDMA are being researched vigorously as the prospective signaling technique for the next generation of mobile communications systems, which will be characterized by the broadband packet technology. With packet transmission, hybrid ARQ (HARQ) will be inevitable for error control. HARQ with rate compatible punctured turbo (RCPT) codes is one of the promising techniqu...

| Multicarrier CDMA and direct sequence CDMA have been suggested for both narrowband and broadband multiple access systems. A series of concepts have further been proposed for variable rate broadband multimedia transmission within a CDMA system. These principally diierent techniques exhibit certain common characteristics that can be exploited. In this paper we propose a generalised unifying dis...

We have two goals in this paper. One is the comparison of Spread Spectrum (SS) CDMA and Spread Time (ST) CDMA. The other is to propose a new SS-ST CDMA system, which is an adaptive CDMA with both merits of SS and ST CDMA. SS and ST CDMA are compared from the view point of two dimensional space "frequency (B Hz) time (T Sec) " together with their communication capacity. A primary modulation is a...