Interference Alignment and Power Control for Wireless Interference Networks

This thesis deals with the design of efficient transmission schemes for wireless interference networks, when certain channel state information (CSI) is available at the terminals. In wireless interference networks multiple source-destination pairs share the same transmission medium for the communications. The signal reception at each destination is affected by the interference from unintended sources. This may lead to a competitive situation that each source tries to compensate the negative effect of interference at its desired destination by increasing its transmission power, while it in fact increases the interference to the other destinations. Ignoring this dependency may cause a significant waste of available radio resource. Since the transmission design for each user is interrelated to the other users’ strategies, an efficient radio resource allocation should be jointly performed considering all the source-destination pairs. This may require a certain amount of CSI to be exchanged, e.g. through feedback channels, among different terminals. In this thesis, we investigate such joint transmission design and resource allocation in wireless interference networks. We first consider the smallest interference network with two sourcedestination pairs. Each source intends to communicate with its dedicated destination with a fixed transmission rate. All terminals have the perfect global CSI. The power control seeks feasible solutions that properly assign transmission power to each source in order to guarantee the successful communications of both source-destination pairs. To avoid interference, the transmissions of the two sources can be orthogonalized. They can also be activated non-orthogonally. In this case, each destination may directly decode its desired signals by treating the interference signals as noise. It may also perform decoding of its desired signals after decoding and subtracting the interference signals sent from the unintended sources. The non-orthogonal transmission can more efficiently utilize the