Ergodic capacity for the bit-detect-and-forward
(BDF) cooperative protocol over gamma-gamma fading channels with pointing errors is here analyzed. Novel closed-form approximate ergodic capacity expression is here obtained for a 3-way free-space optical (FSO) communication system using the well-known inequality between arithmetic and geometric means of positive random variables (RV) in order to derive an
approximate closed-form expression of the sum of gamma-gamma with pointing errors variates. It can be concluded that a greater and robust capacity strongly dependent on the relay location is achieved compared to a direct transmission.
