Coordinated Beamforming for MISO Interference Channel: Complexity Analysis and Efficient Algorithms

• Published in: IEEE transactions on signal processing Vol. 59; no. 3; pp. 1142 - 1157
• Main Authors: Liu, Ya-Feng, Dai, Yu-Hong, Luo, Zhi-Quan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Antennas; Applied sciences; Array signal processing; Base stations; Beamforming; Channels; Complexity; coordinated beamforming; cyclic coordinate descent algorithm; Detection, estimation, filtering, equalization, prediction; Exact sciences and technology; global convergence; Harmonic analysis; Information, signal and communications theory; Interference; Interference channels; Maximization; Miscellaneous; MISO interference channel; Optimization; Polynomials; Signal and communications theory; Signal processing; Signal, noise; Stations; Telecommunications and information theory; Utilities; Wireless communications; Performance evaluation; Harmonic; Base station; Wireless telecommunication; Information rate; Transmitter; Equity; Downlink; Updating; Cell network; Beam forming; Complexity; MISO interference channel; MISO system; Antenna array; Information exchange; Antenna; Mobile radiocommunication; Computer simulation; global convergence; cyclic coordinate descent algorithm; Single carrier; coordinated beamforming; Algorithm; Information transmission; Algorithm performance; NP hard problem; Signal processing
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2010.2092772

In a cellular wireless system, users located at cell edges often suffer significant out-of-cell interference. Assuming each base station is equipped with multiple antennas, we can model this scenario as a multiple-input single-output (MISO) interference channel. In this paper we consider a coordinated beamforming approach whereby multiple base stations jointly optimize their downlink beamforming vectors in order to simultaneously improve the data rates of a given group of cell edge users. Assuming perfect channel knowledge, we formulate this problem as the maximization of a system utility (which balances user fairness and average user rates), subject to individual power constraints at each base station. We show that, for the single-carrier case and when the number of antennas at each base station is at least two, the optimal coordinated beamforming problem is NP-hard for both the harmonic mean utility and the proportional fairness utility. For general utilities, we propose a cyclic coordinate descent algorithm, which enables each transmitter to update its beamformer locally with limited information exchange and establish its global convergence to a stationary point. We illustrate its effectiveness in computer simulations by using the space matched beamformer as the benchmark.