Different pseudo-random or pseudo-noise (PN) as well as orthogonal sequences that can be used as spreading codes for code division multiple access (CDMA) cellular networks or can be used for encrypting speech signals to reduce the residual intelligence are investigated. We briefly review the theoretical background for direct sequence CDMA systems and describe the main characteristics of the max...

In this paper, we evaluate by computer simulations the throughput performance of the turbo-coded hybrid ARQ for direct sequence code division multiple access (DS-CDMA) with antenna diversity reception and Rake combining in a frequency selective Rayleigh fading channel. The effect of a range of system parameters and propagation parameters (viz., the frame length, puncturing rate, spreading facto...

--~~~~~ ~~~~~~~~~ ~~~ .... ~ .~~. ..... demodulated through two stages. In the first stage, the multi-code based PPM signal is demodulated through the Bayes decision Then, in the second stage, the demodulated multi-code signal is de-spreaded by using the M orthogonal spreading codes rule. Then, in the second stage, the demodulated multi-code signal is de-spreaded by using the M orthogonal SPrea...

| We view the asynchronous random{code{ division multiple{access channel as a time{varying convo-lutional code. We study the case where the users encode their data and therefore the single user transmitters and the CDMA channel appear as the concatenation of two coding systems. At the receiver we employ serial Turbo decoding strategies. Unlike conventional Turbo codes where both the inner and o...

We view the asynchronous random code-division multiple-access (CDMA) channel as a time-varying convolutional code. We study the case where the users encode their data, and, therefore, the single user transmitters and the CDMA channel appear as the concatenation of two coding systems. At the receiver we employ serial Turbo decoding strategies. Unlike conventional Turbo codes where both the inner...

In this article we propose a solution for the channel decoder in a iterative CDMA receiver. The iterative CDMA receiver resembles a Turbo decoder for serially concatenated convolution codes since the CDMA channel is viewed as a convolutional code. The proposed solution has complexity per bit that is linear in the number of users. For the rst time we observe performance within a fraction of a dB...

A complete complementary/prime/shifted prime (CPS) code family for the optical code-division multiple-access (OCDMA) system is proposed. Based on the ability of complete complementary (CC) code, the multiple-access interference (MAI) can be suppressed and eliminated via spectral amplitude coding (SAC) OCDMA system under asynchronous/synchronous transmission. By utilizing the shifted prime (SP) ...

A new method for generating families of ternary spreading sequences is presented. The sequences have aperiodic zero correlation zones and large families are created for a specific sequence length. The sequences are proposed as spreading sequences to provide high capacity and cancel multipath and multiple access interference (MAI) in a single carrier (SC) or multi-carrier (MC) direct-spread code...

This paper presents a novel chaotic spreading sequence for multiple input multiple output multi-carrier direct sequence code division multiple access (MIMO MCDS/CDMA) systems. The effect of multiple access interference can be mitigated by choosing the spreading sequences with appropriate cross-correlation properties. The performance of the system is analysed in multiuser scenario with the aid o...

A new method for generating families of ternary spreading sequences is presented. The sequences have aperiodic zero correlation zones and large families are created for a specific sequence length. The sequences are proposed as spreading sequences to provide high capacity and cancel multipath and multiple access interference (MAI) in a single carrier (SC) or multi-carrier (MC) direct-spread code...