Abstract-In this letter, we derive the probability density function (PDF) and cumulative distribution function (CDF) of the minimum of two non-central Chi-square random variables with two degrees of freedom in terms of power series. With the help of the derived PDF and CDF, we obtain the exact ergodic capacity of the following adaptive protocols in a decode-andforward (DF) cooperative system over dissimilar Rician fading channels: (i) constant power with optimal rate adaptation; (ii) optimal simultaneous power and rate adaptation; (iii) channel inversion with fixed rate. By using the analytical expressions of the capacity, it is observed that the optimal power and rate adaptation provides better capacity than the optimal rate adaptation with constant power from low to moderate signalto-noise ratio values over dissimilar Rician fading channels. Despite low complexity, the channel inversion based adaptive transmission is shown to suffer from significant loss in capacity as compared to the other adaptive transmission based techniques over DF Rician channels.
In REF , precise ergodic capacity for different adaptive protocols in DF system under different Rician fading channels was studied for optimal rate adaptation with constant power, optimal rate adaptation and simultaneous power, channel inversion based fixed rate.
On the Capacity of Decode-and-Forward Relaying over Rician Fading Channels
IEEE Communications Letters
IEEE Communications Letters
Computer Science Mathematics