University of Tabriz Tabriz Journal of Electrical Engineering 2008-7799 51 2 2021 07 23 Joint Power Allocation and Constellation Rotation in Alamouti coded Interference Alignment in X-Channel with imperfect CSI Joint Power Allocation and Constellation Rotation in Alamouti coded Interference Alignment in X-Channel with imperfect CSI 243 254 13675 FA H. Khaleghi Bizaki Deparement of Electrical and Computer Engineering, Malek Ashtar University of Technology, Tehran, Iran. E. Rahimi Deparement of Electrical and Computer Engineering, Malek Ashtar University of Technology, Tehran, Iran. Journal Article 2012 09 15 Interference Alignment (IA) with Alamouti coding is an innovative method to increase the multiplexing gain and the diversity gain, simultaneously, in wireless Multiple-Input Multiple-Output (MIMO) systems. The main limitation of this method is requiring Perfect Channel State Information (CSI) to perform the beamforming on transmitters and receivers signals. Contrary to the acceptable performance of Alamouti coding in perfect CSI conditions, its efficiency is severely reduced in imperfect CSI conditions. In order to overcome this shortcoming, this paper discusses about the effect of imperfect CSI on a two user MIMO X-channel which uses interference alignment together with Alamouti coding. Also, a closed form solution is extracted for the received signal in an imperfect CSI scenario. Our analysis shows that when the variance of the CSI error is increased, the Bit Error Rate (BER) of system increases linearly. Also, we propose a joint Power Allocation (PA) and constellation rotation algorithm to improve the performance of system in an imperfect CSI scenario. Computer simulations show a desirable improvement in BER by using PA, constellation rotation and joint of them. Interference Alignment (IA) with Alamouti coding is an innovative method to increase the multiplexing gain and the diversity gain, simultaneously, in wireless Multiple-Input Multiple-Output (MIMO) systems. The main limitation of this method is requiring Perfect Channel State Information (CSI) to perform the beamforming on transmitters and receivers signals. Contrary to the acceptable performance of Alamouti coding in perfect CSI conditions, its efficiency is severely reduced in imperfect CSI conditions. In order to overcome this shortcoming, this paper discusses about the effect of imperfect CSI on a two user MIMO X-channel which uses interference alignment together with Alamouti coding. Also, a closed form solution is extracted for the received signal in an imperfect CSI scenario. Our analysis shows that when the variance of the CSI error is increased, the Bit Error Rate (BER) of system increases linearly. Also, we propose a joint Power Allocation (PA) and constellation rotation algorithm to improve the performance of system in an imperfect CSI scenario. Computer simulations show a desirable improvement in BER by using PA, constellation rotation and joint of them. https://tjee.tabrizu.ac.ir/article_13675_92262b1c0b9b02a849a3b9398979567e.pdf