generalized-K Channels Research Articles

Secure analysis over generalized-K channels

In this letter, we adopt the SOP definition in [4] and the simplified model of [8], and derive a closed-form expression for the proposed SOP over GK fading channels. To simplify this expression and obtain additional insights, we also perform an asymptotic analysis of the main link in the high SNR region.

Energy Harvesting From Multiple RF Sources in Wireless Fading Channels

Energy-harvesting technologies are currently under development to provide power for wireless networks and devices. This paper investigates the usage of radio frequency (RF) signals emitted from wireless nodes as sources in energy-harvesting systems. The system we consider consists of multiple RF source nodes, multiple destination nodes, and an energy-harvesting node with a limited-capacity rechargeable battery. We observe that the total received power at the antenna of the harvesting node changes with the number of RF source nodes and the channel conditions. At the same time, the variation of instantaneous received power and the selected modulation type affect the required time for recharging battery. We study statistical models for the battery recharging time in the presence of multiple RF source nodes and focus on the generalized-K channels that include both large-scale and small-scale fading models. Then, we propose a distribution for the battery recharging time that provides a close and analytically tractable expression. We derive the associated fundamental statistical expressions for the battery recharging time in closed form. The simulations and numerical studies are used to verify the theoretical results. The Gamma distribution provides tight approximation to simulation results in fading wireless channel conditions. Additionally, we present battery recharging test results for two sources as a real-life application of energy harvesting with multiple RF sources. Our test results show close fit with the derived distribution equations, supporting theoretical analyses.

SER performance of cooperative systems with the Nth best path selection in generalized-K channels

We investigate performance of the both variable and fixed-gain amplify-and-forward cooperative communication systems over composite fading and shadowing channels modeled by independent but not necessarily identically distributed generalized-K distribution. We consider two different Nth best path selection schemes: the Nth best relay and link selection. In the Nth best relay selection (RS) scheme, signals received from the Nth best relay and the direct path are combined with maximal-ratio combining and decoded at the destination. In the Nth best link selection (LS) scheme, the direct path is included to the selection set and only the signal received from the selected path is decoded at the destination. New symbol error rate (SER) expressions are derived analytically by using the moment generating function (MGF) approach with Padé approximation and the cumulative distribution function approach. The MGF and SER expressions are in closed-form for the Nth best RS and LS systems, respectively. The derived SER expressions are almost exact at any signal-to-noise ratio. We also present the asymptotic diversity order of the system. The analytical results are verified by Monte-Carlo simulations. Since the generalized-K channel model is a quite general channel model, the existing symbol error probability results given in the literature for cooperative systems with path selection over conventional Rayleigh or Nakagami-m fading channels can be obtained as special cases of our results.

Performance Analysis of Decode and Forward Cooperative Relaying over the Generalized-K Channel

In this paper, we analyze the performance of cooperative diversity using adaptive Decode and Forward (DF) relaying over independent but non-necessarily identical flat composite fading channels which include multipath fading and shadowing simultaneously. We have considered the transmission of M-QAM modulated signals over Generalized-K channel model which is very versatile and accurately approximates many of the commonly used channel models as Nakagami-m, Log-Normal distributions and the mixture of the two distributions for the composite fading. Using an approximation of the Generalized-K pdf by a Gamma pdf, we derive analytical expressions for the outage probability and the Average Symbol Error Probability (ASEP) of the proposed scenario and analyze their dependence on the channel parameters. We assume in our context that the relay decides independently whether or not to forward the signal to the destination based on the received signal quality. Simulations are provided for 16-QAM modulation for both the outage and the ASEP. The obtained results are discussed and proved to be in good agreement with our theoretical analysis.