Interference management schemes for multi-user interference channels

Abstract

Since many concurrent wireless communication systems can be modeled as multi-user interference channels, interference management in this channel becomes an important issue in design for wireless communication systems. In this thesis, we propose interference management schemes to mitigate interferences in various wireless communication systems such as overloaded multiple-input multiple-output (MIMO) interference systems, multi-user ad-hoc systems, and multi-cell cellular systems with wired/wireless relays. This thesis consists of three part, those are as follows.

In the first part of the thesis, a new transceiver architecture for overloaded MIMO interference channels is proposed to fix the rate saturation problem of purely linear beamforming in this case. The proposed scheme is based on a mixture of linear beamforming and multi-user detection. We develop a process for designing proposed nonlinear scheme and a special case, thereof called successive interference cancellation, analyze their achievable degrees of freedom. It is shown that a non-trivial degree of freedom can be achieved by the proposed mixed scheme by properly dividing the interference signals for linear processing and multiuser detection, and the achievable degrees of freedom of the proposed scheme is obtained. The sum rates of proposed nonlinear scheme is compared with that of linear beamforming. Numerical results show that the proposed scheme outperforms linear beamforming in overloaded MIMO interference channels.

In the second part of the thesis, a cellular network architecture with a wired shared relay equipped with directional antennas is proposed to mitigate inter-cell interferences, where shared relay is placed at the intersection of adjacent cells. This location is where the inter-cell interference is the most severe. In the proposed architecture, the shared relay is connected to the corresponding BS by a reliable link like an optic fiber, and thus the shared relay will operate as a...