Due to rapidly increasing energy consumption of wireless communication systems, energy efficiency (EE) has become an important metric in designing theses networks. In wireless networks, relaying is supposed to be a low energy consumption technique since the long distance is devided in to several short distance transmissions. so relaying can increase EE. Most detection techniques and optimization methods in cooperative networks assume that perfect channel state information is available. While in practical situations, the estimates of the channels may only be known and for acquiring such knowledge, a fraction of power and bandwidth have to be spent for channel estimation using pilot symbols. In long distances transmission power dominates circuit power so we can neglect circuit power consumption. But e.g in wireless sensor networks the average distance between nodes is less than ten meters so in these networks we have to consider circuit power consumption. Previous results in this area assume that perfect CSI is available. Instead, in this thesis we consider imperfect CSI for both the source-relay and relay-destination channels. power allocation between pilot and data symbols is investigated to maximize EE for one-way and two-way relay transmission with channel estimation error and considering circuit power consumption. To evaluate the accuracy of the alternative optimization method, is compared with exhausive search method. Simulation results indicate that channel estimation error decreases energy efficiency, and energy efficiency versus spectral efficiency is as same as without channel estimation. Keywords: Energy Efficiency , Spectral Efficiency , Power Allocation , Channel state information, Circuit power
