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To improve spectrum efficiency, most beyond 3G wireless systems advocate to increase the frequency reuse factor and even allow it to be one or so-called “universal frequency reuse”, where all the users in adjacent cells communicate simultaneously over the same band. In such multi-user systems, interference is the key factor that limits the network throughput.
Gaussian interference channel (GIC) is a basic mathematical model that characterizes many real-life interference limited communication systems, e.g., the aforementioned multi-cell cellular network. As shown in the figure, a classic K-user GIC consists of K pairs of transmitters and receivers, where transmitter k has its intended message only to receiver k. However, besides the desired signal from transmitter k, receiver k also receives K-1 interfering signals from the other transmitters at the same time.
Characterizing the global maximum of weighted sum-rate (WSR) for the K-user GIC, with the interference treated as additional Gaussian noise at receivers, is a key problem that is however not yet completely solved. Due to the users’ coupled transmission with interference, the resulted WSR maximization problem is in general non-convex and thus cannot be solved directly by conventional convex optimization techniques.
Based on techniques of monotonic optimization and rate profile, I develop an advanced algorithm that solves the WSR maximization problem globally optimally in GIC. Our proposed algorithm is the first one in the literature that can guarantee a global solution to WSR maximization problem in GIC with multi-antenna transmitters/receivers.
Journal Publications:
- L. Liu, R. Zhang, and K. C. Chua, “Achieving global optimality for weighted sum-rate maximization in the K-user Gaussian interference channel with multiple antennas,” IEEE Trans. Wireless Commun., vol. 11, no. 5, pp. 1933-1945, May 2012.
- L. Liu, and R. Zhang, “How to diagonalize a MIMO channel with arbitrary transmit covariance?” IEEE Wireless Commun. Lett., vol. 5, no. 4, pp. 352-355, Aug. 2016.
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