Abstract The multiple-access interference (MAI) limits the transmission performance of the CDMA uplink transmission. In this paper, we propose a generalized chip-interleaved (GCI)-CDMA with 2-dimensional (2D)-OVSF spreading. Since MAI can be removed, single-user frequency-domain equalization based on the MMSE criterion can be applied for signal detection. The GCI-CDMA allows flexible multi-rate...

In this paper, a multi-coded CDMA system employing a variable spreading gain (VSG) approach is proposed for high-rate applications, which is based on two algorithms for selecting multi-code set. From the simulation results, in addition to simple receiver structure thanks to level clipping, the multi-coded VSG CDMA system provides an high bit rate transmission, while maintaining an acceptable pe...

Minimax problems arise in a wide range of important applications including robust adversarial learning and Generative Adversarial Network (GAN) training. Recently, algorithms for minimax the Federated Learning (FL) paradigm have received considerable interest. Existing federated general require full aggregation (i.e., local model information from all clients) each training round. Thus, they are...

Relying on block-symbol spreading and judicious design of user codes, this paper builds on the generalized multicarrier (GMC) quasisynchronous CDMA system that is capable of multiuser interference (MUI) elimination and intersymbol interference (ISI) suppression with guaranteed symbol recovery, regardless of the wireless frequency-selective channels. GMC-CDMA affords an alldigital unifying frame...

This paper gives a review of DS-CDMA, RAKE receiver and multicarrier DS-CDMA as well as a proposal and numerical result for a multicarrier DS-CDMA system. This paper is organized as follows: Section I introduces the development of methods for wireless communication over multipath fading channel. Section II gives Turin's evaluation of the e ects of multipath and fading on the performance of DS-C...

Direct sequence (DS) and Multi-carrier (MC) code division multiple access (CDMA) are competing schemes for wireless multiple access systems. They have been studied and compared by many researchers. Time and frequency domains have long been used to represent linear systems in dual forms. In this paper it is shown, using time-frequency duality, that DS and MC can be considered dual CDMA systems o...

In this paper, the capacity of the Code Division Multiple Access Wireless Local Loop (CDMA WLL) system is analytically derived, and the capacity gain achieved in a CDMA WLL over a cellular mobile environment is calculated. The results show that the CDMA WLL system can support up to 36 % more users than CDMA cellular mobile system. The paper also propose a new approach to increase the reverse li...

In this paper, we analyze capacity and spectrum utilization of spectrally overlaid systems using single-code CDMA (SC-CDMA) and multi-code CDMA (MC-CDMA) techniques according to varying system parameters. The spectrum utilization defined as maximally achievable total throughput in the overlaid systems is compared with that of the un-overlaid systems. Analytical results show that the dominant pa...

For the reception of multicode direct sequence (DS)-CDMA signals, the MMSE frequency domain equalisation is applied instead of RAKE combining. The achievable BER performance in a frequency selective Rayleigh fading channel is evaluated by computer simulation. It is shown by computer simulation that the DS-CDMA with MMSE frequency domain equalisation outperforms the DS-CDMA with RAKE combining a...

We investigate the possible role of optical CDMA (O-CDMA) in future access networks. We begin with a short review of the O-CDMA technique for those unfamiliar with the technology. Next, we investigate in detail those characteristics of O-CDMA that make it an attractive technology for application in metro access networks: fairness, flexibility, simplified network control and management, service ...