A novel multiuser-interference (MUI)-free code division multiple access (CDMA) transceiver for frequency-selective multipath channels is developed in this paper. Relying on chip-interleaving and zero padded transmissions, orthogonality among different users’ spreading codes is maintained at the receiver even after frequency-selective propagation. As a result, deterministic multiuser separation ...

We examine the average-case performance of a code-division multiple-access (CDMA) multiuser demodulator in which quantum fluctuations are utilized to demodulate the original message within the context of Bayesian inference. The quantum fluctuations are built into the system as a transverse field in the infinite-range Ising spin glass model. We evaluate the performance measurements by using stat...

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An optical fast frequency modulation code division multiple access communication system is proposed. In this system, an electrically controlled tunable optical filter (TOF) is used to encode the modulated broadband light source. The code depends on the function set to the controller. Two-dimensional code named functional code is also proposed based on a shifted sine function. The function defin...

In Code Division Multiple Access (CDMA) communications, Multiuser Detection (MUD), that reduces the multi-access interference (MAI) and that solves the near-far problem, has been widely studied for over 15 years. Since optimal multiuser detection is generally NP hard, many sub-optimal algorithms that provide reliable performance and ensure polynomial complexity have been proposed. However, ther...

We derive approximations for the probability of a bit error for a code division multiple access (CDMA) system with one-stage soft decision parallel interference cancellation. More precisely, we derive the exponential rates, Jk with cancellation and Ik without cancellation, of a CDMA system with k users and processing gain equal to n as n → ∞. Whereas the rates Ik follow explicitly from Cramér’s...

With the emergence of network driven applications and high speed requirements in communication along with security and large bandwidth, there is a need for a network technique which is capable of providing all the above with a reduced cost. A multiple access technique called Optical Code Division Multiple Access (OCDMA) seems to be fulfilling the above criteria. OCDMA combines the large bandwid...

We analyze the performance of truncated power control in a code-division multiple-access (CDMA) communication system. This power control scheme compensates for propagation gain above a certain cutoff fade depth: below the cutoff level, data transmission is suspended. We assume a channel with fast Rayleigh fading and slow lognormal shadowing plus path loss, where truncated power control is appli...

This paper investigates the use of non-linear convolutional coding techniques for use in a DS-CDMA cellular communication system. Comparisons are made between various error-correction strategies and the Wiener minimum mean square error receiver filter, implemented with the same bandwidth expansion. The use of Gold codes in conjunction with an orthogonal convolutional encoder is shown to produce...

The concept of group detection is introduced to address the design of suboptimum multiuser detectors for CodeDivision Multiple-Access (CDMA) channels. A group detection scheme consists of a bank of P group detectors, one each for detecting the information symbols of users in each group of a P group partition of the li simultaneously transmitting users. In a parallel group detection scheme, thes...