Satellite communication channels are affected by ionospheric scintillation phenomenon, causing signal attenuation. This paper presents the performance of a WaveletBased Multi-Carrier Code Division Multiple Access (WBMC-CDMA) under flat scintillation channels, in comparison with the Fourier-Based method. With scintillation, as the scintillation index S4 increases, the performance of communicatio...

We propose to combine directional antennas in a conformal array configuration with a matching two-stage receiver architecture to improve performance of code-division multiple-access (CDMA) communication systems in time-varying channels. We propose a reduced-dimension space–time (ST) RAKE architecture that matches the ST correlation structure of the data received by a circular array. In time-var...

This paper examines code-division multiple-access (CDMA) techniques used in unslotted fiber-optic packet networks. Since the inherent properties and signal processing of the conventional communication channels are different from those of the fiber-optic channels, new code sequences must be constructed for fiber-optic applications. In unslotted systems, the exact solution is very difficult to ob...

We consider a wireless network consisting of two classes of potentially mobile users: primary users and secondary users. Primary users license frequency channels and transmit in their respective bands as required. Secondary users resort to unlicensed access of channels that are not used by their primary users. Primaries impose access fees on the secondaries which depend on access durations and ...

This paper examines code-division multiple-access (CDMA) techniques used in slotted fiber-optic packet networks. Since the inherent properties and signal processing of the conventional communication channels are different from those of the fiber-optic channels, new code sequences must be constructed for fiber-optic applications. The goal of our research is to analyze the performance of fiber-op...

We present a cognitive spectrum access solution for FH-CDMA ad hoc networks. Building on a cluster-based split phase multi-channel MAC protocol, we propose a mechanism for local interference avoidance through distributed hopset adaptation. Its goal is to identify and substitute channels not suitable for reliable communication. Substitution rules replace channels by locally unused hopsets. This ...

The secret π-calculus extends the π-calculus by adding an hide operator that permits to declare channels as secret. The main aim is confidentiality, which is gained by restricting the access of the object of the communication. Communication channels protected by hide are more secure since they have static scope and do not allow the context’s interaction, and can be implemented as dedicated chan...

While there are continuous efforts to introduce new communication systems and standards, it is legitimate to ask the question: how can one send additional bits by minimally changing the systems that are already operating? This is of a significant practical interest, since it has a potential to generate additional value of the systems through, for example, introduction of new devices and only a ...

ment of wireless communication systems in recent years, especially for broadband multiuser communication systems which severely suffer from intersymbol interference (ISI) and multiple access interference (MAI). This article reviews batch processing algorithms for blind equalization using higher-order statistics for mitigation of the ISI induced by single-input, single-output channels as well as...