Abstract — Testbeds are projected to be the next generation of mechanisms for protocol verification and performance validation of wireless networks. One important objective of these testbeds is to depict the propagation mechanism accurately. This paper presents measurements and models of propagation between stationary transmitters and receivers in a dynamic environment. These measurements indicate that in some environments, the signal strength displays wide variations, while in other environments, there is less variation in the signal strength. A diffusion-based stochastic model is presented that can be used to increase the accuracy of testbed emulations I.

Abstract—Channel estimation algorithms are proposed for the initialization phase of a wireless sensor network, during which the nodes are still unaware of their neighbors or channel qualities. Both expectation propagation (EP) and diffusion least mean squares (LMS) algorithms are applied

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The measurement of channel gains is a widely used method for determining properties of substances. A common way of performing this measurement is by sending a harmonic signal with known amplitude through the substance followed by a filtering of the received signal, which yields an estimation

Abstract — The presence of both multiple-access interference (MAI) and intersymbol interference (ISI) constitutes a major impediment to reliable communications in multipath code-division multiple-access (CDMA) channels. In this paper, an iterative receiver structure is proposed for decoding

Cooperative diversity has been recently proposed as a way to form virtual antenna arrays that provide dramatic gains in slow fading wireless environments. However, most of the proposed solutions require distributed space–time coding algorithms, the careful design of which is left for future

Abstract—We consider the problem of distributed channel estimation in a sensor network which employs a random sleep strategy to conserve energy. If theN network nodes are randomly placed at unknown positions, some prior information about the channel gains can be obtained due to the path loss effect

diversity, in which diversity gains are achieved via the cooperation of mobile users. Part I describes the user cooperation strategy, while Part II focuses on implementation issues and performance analysis. Results show that, even though the interuser channel is noisy, cooperation leads not only

Abstract—Channel capacity is usually undetermined in cooperative communication because of the various power allocations. In order to improve the channel capacity, power allocation for tri-terminal cooperative communication is discussed for Gaussian channel gains in EGC model and MRC model

Abstract — We introduce a variable-rate (VR) M-PSK modu-lation scheme, for communications over fading channels, in the absence of channel gain estimation at the receiver. The choice of the constellation size is based on the signal-plus-noise (S+N) sampling value rather than on the signal