Recently, the new spreading sequence obtained by the Weyl sequence is proposed for CDMA systems. Its crosscorrelation function follows O( 1 N ), where N is the code length of the spreading sequence. In this paper, we optimize the Weyl sequence code design to assign to each user for CDMA systems and we analytically calculate its theoretical SIR (Signal to Interference Noise Ratio). It is theoret...

Conventional DS-CDMA systems employ a RAKE receiver in an attempt to make full use of the signal energy scattered in the time domain; however, the multipath effect causes a loss of orthogonality which degrades RAKE receiver performances. The literature on multi-carrier CDMA (MC-CDMA) has shown that receivers employing frequency diversity (in an effort to make full use of energy spread in the fr...

Abstract The downlink bit error rate (BER) performances of DSand MC-CDMA in a frequency-selective fading channel can be significantly improved by the use of frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion. However, the uplink BER performance degrades due to strong multi-user interference (MUI) since different users’ signals go through different channels a...

A K-user pseudo-orthogonal (PO) randomly spread CDMA system, equivalent to transmission over a subset of K ′ ≤ K single-user Gaussian channels, is introduced. The high signal-to-noise ratio performance of the PO-CDMA is analyzed by rigorously deriving its asymptotic multiuser efficiency (AME) in the large system limit. Interestingly, the K -optimized PO-CDMA transceiver scheme yields an AME whi...

Multi-Carrier Code Division Multiple Access (MCCDMA) is a modulation scheme that combines the advantages of OFDM and CDMA to provide robustness against frequency selectivity in wireless channels. Arrayed MC-CDMA systems combine MC-CDMA and antenna array technology to harness the spatial and temporal ’signatures’ of received signals, thus making it possible to realize high transmission rates env...

Currently, a global third generation cellular system based on CDMA is being developed with a wider bandwidth than existing second generation system. The RAKE Receiver instead of completely eliminating multipath uses techniques to effectively utilize multipath to produce the desired signal. This paper proposes interference mitigation by CDMA RAKE receiver with WalshHadamard Sequence for DSCDMA s...

Orthogonal multicode direct sequence code division multiple access (DS-CDMA) has a flexibility in offering various data rate services. However, in a frequency-selective fading channel, the bit error rate (BER) performance is severely degraded since othogonality among spreading codes is partially lost. In this paper, we apply frequency-domain equalization and antenna diversity combining, used in...

The MC-CDMA (multi-carrier code division multiple access) technique is known to be appropriate for high data-rate wireless communications such as mobile multimedia communication due to its robustness to multipath fading and its capability of handling high data rates with a simple onetap equalizer. In this paper, the performance of an MC-CDMA system employing antenna array at the base station in...

Served as one of the most widely used wireless airlink interface, CDMA has been identified as a major technique for 3G wireless communications. The current IS-95 CDMA provides a nearsatisfactory security solution to voice centric wireless communications because each voice conversation only lasts for a very short period of time. However, the security features provided by IS-95 CDMA are far from ...

Multi carrier code division multiple access (MC-CDMA), a strong contender for future mobile communication is a combination of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). Turbo coding technique can be used for improving the performance of MC-CDMA system in terms of bit error rate (BER). The objective of this work is to form a coding scheme that red...