Average relay transmit-power analysis in dual-hop amplify-and-forward relaying systems

What is it about?

Network lifetime is an important performance for wireless relaying systems and many relay selections have been proposed to prolong the network lifetime. But in most cases only simulation results were given, rather than a closed form of average relay transmit-power or network lifetime. In this paper, we firstly give a general analytical expression of average relay transmit-power for any relay selection strategy when all relays have enough energy in amplify-and-forward (AF) relaying systems. In order to analyze the probability density function (PDF) of relay transmit-power, we derive the constraints of probability for arbitrary possible transmit-power. Then, we get two special PDFs, which correspond to the minimum average relay transmit-power (MinARTP) and the maximum average relay transmit-power (MaxARTP). Finally, MinARTP and MaxARTP are derived. Simulation results validate that MinARTP and MaxARTP can approximately represent the lower bound and the upper bound of average relay transmit-power for the system.

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Why is it important?

In this paper, we analyze average relay transmit-power for AF cooperative systems when every relay has enough energy. Both the minimum average relay transmit-power (MinARTP) and the maximum average relay transmit-power (MaxARTP) can be calculated for a given cooperative relaying system. Simulations validate our analysis.Based on our analysis, both MinARTP and MaxARTP can be derived easily for any case that the transmission power is discrete in practical applications. Furthermore, the results can be used to estimate the network lifetime limitation or evaluate relay selection schemes by comparing the average relay transmit-power with the MinARTP and MaxARTP.

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