Interference Alignment Algorithm For Multiuser Interference Channel With Relays

Interference Alignment technology can effectively overcome the shortcomings of traditional interference management methods so as to improve the degrees of freedom(Do F). Interference Alignment has become an effective interference management method. For interference channels without relay(s), interference alignment requires global channel state information(CSI) available at all transmit nodes to achieve the target Do F. Which leads to a great signaling complexity.This thesis aims at designing interference alignment methods for multiuser interference channel with relay(s) to improve the system performance. The main contributions of this thesis are as following:1. Firstly,the system models of K-user interference channel and K-user interference channel with a MIMO relay have been set up.The principles of interference alignment algorithm in different models are studied, and the performance achieved through interference alignment are evaluated via simulations.2. For K-user interference channel with a MIMO relay, a transmission method is designed by combining interference alignment with Alamouti space-time block code(STBC). In the proposed method, the transmit signals are encoded by Alamouti STBC and transmitted over two stages. The precoder at the relay is designed to align the interfering signals at the receive nodes. After nulling the aligned interference, the desired signal can be decoded. The analysis and simulations demonstrate that the proposed method can greatly improve the diversity gain.3. Finally, a signal transmission method is proposed for K-user interference channel with two MIMO relays. By using an alternate relay transmission and designing interference alignment precoders at the two relays, the proposed scheme can compensate the sum rate loss due to the half duplexing relay mode. The simulation results show that the proposed scheme can improve the sum Do F and consequently improve the system capacity.