Coordinated Multi-Point Transmission of MIMO-OFDM System with Per-Antenna Power Constraints

This paper describes an efficient approach to discrete rate and power allocation for MIMO-OFDM systems with individual power-constrained antennas. The system is configured with multiple base stations, each with a single transmit antenna, for coordinated multi-point transmissions. The traditional OFDM loading problem can be extended to the MIMO-OFDM case provided that the channel state information between all transmit and receive antennas is known. However, due to unequidistant between coordinated base stations and user terminal, a per-antenna average power constraint is more practical than a total average power constraint in order to keep each antenna peak power manageable to avoid low power efficiency of the power amplifier in each antenna. The replacement of the per-antenna power constraint results in a more complex loading optimization problem, and we show it can still be solved efficiently using the dual Lagrange decomposition method. A multidimensional Lagrange search is needed to find the optimal solution and is accomplished via the Ellipsoid Method and the Analytical Center Cutting-Plane Method.