In this paper, we compare two signal designs for uplink quasi-synchronous code division multiple access (CDMA) channels in order to optimize the trade-off between bandwidth efficiency and power efficiency. The design we call band-limited DS/CDMA design, is based on the time-domain assignment of Gold sequences, just as in the ordinary DS/CDMA, but with band-constrained cyclic chip interpolation ...

Multi-carrier code division multiple access (MC-CDMA) technique maintains the original signaling interval while it spreads the signal over wide bandwidth like direct-sequence code division multiple access (DS-CDMA) technique. Low amount of delay spread reduces the guard interval in MC-CDMA and make it power efficient. MC-CDMA is sensitive to frequency offset and small Doppler spread is preferre...

The future (third-generation) mobile communications system will provide not only voice and low-speed data services, but also video and high-speed data services. It will eventually have the capability for wireless multimedia communications. As a radio-access technique for such a system, the code-division multiple access (CDMA) has been considered in many potential third-generation systems includ...

The optical CDMA and WDM systems have been of widespread implementation for local and metro access network. This is because optical CDMA systems provide users both simultaneous and asynchronous access to networks with high security [1], and WDM systems provide a relatively high transmission capacity [2]. In addition, optical CDMA can be overlaid onto existing WDM networks in order to enhance th...

Code division multiple access (CDMA) is a highly flexible multiple access protocol, however, significant signal bandwidth expansion is required. Given the Terahertz pass band of optical fiber, the frequency spreading of the CDMA signal is no impediment, provided it can be accomplished optically. Among wide variants of optical CDMA techniques, only a spectral encoding based approach [1] has pene...

We describe a heterogeneous simulation framework in which conventional simulation models and the DEVS (Discrete Event Systems Specification) models can be interoperable. The framework conceptually consists of three layers: the model layer, the DEVS layer, and the HLA (High Level Architecture) layer. The model layer has a collection of heterogeneous simulation models, such as DEVS, CSIM, SLAM, a...