In this paper, we propose a novel scheme, which combines both advantages of adaptive modulation and the concept of distributed switching. Unlike previous incremental relaying protocols under adaptive modulation, we consider a more realistic scenario where the link providing higher spectral efficiency is chosen for data transmission. We also examine the outage probability, bit error rate, and spectral efficiency, which are important performance measures for the proposed system. Based on the derived expression and its approximate form, we demonstrate that the proposed network enhances the system performance in terms of spectral efficiency by around 3 dB, compared to the conventional incremental relaying networks. Finally, the derivation is validated through Monte Carlo simulations.Index Terms-amplify-and-forward, Rayleigh fading, outage probability, spectral efficiency, bit error rate, adaptive transmission, incremental relaying.

This investigation aims to compare the full energy peak efficiencies in the energy range of 46-1836 keV on a type-p coaxial HPGe and estimate the coincidence summing factor for the case of Marinelli Beaker samples used by two general Monte-Carlo simulation software MCNP and PENELOPE. The radioactive nuclides used in determining the coincidence summing factor include 22Na, 60Co, 88Y, 133Ba, 134Cs, 154Eu, and 208Tl, which are prepared in HCl 2M solution and contained in a Marinelli beaker with the source’s volume of 3000 ml. The results demonstrate there is a good agreement between the two simulation software with an average discrepancy of 1.3%. On the other hand, the simulation coincidence summing factor values are also compared with the results from the calculating software ETNA with an average discrepancy of approximately 3.1%.

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