Title :
Two-Stage Subspace Constrained Precoding in Massive MIMO Cellular Systems
Author :
An Liu ; Lau, Vincent K. N.
Author_Institution :
Dept. of Electr. & Comput. Eng., Hong Kong Univ. of Sci. & Technol., Hong Kong, China
Abstract :
We propose a subspace constrained precoding scheme to fully unleash the gain provided by massive antenna array with reduced channel state information (CSI) signaling overhead. The MIMO precoder at each base station (BS) is partitioned into an inner precoder and a Transmit (Tx) subspace control matrix. The inner precoder is adaptive to the local CSI at each BS for spatial multiplexing gain. The Tx subspace control is adaptive to the channel statistics for inter-cell interference mitigation. Specifically, the Tx subspace control is formulated as a QoS optimization problem which involves an SINR chance constraint where the probability of each user´s SINR not satisfying a service requirement must not exceed a given outage probability. Such chance constraint cannot be handled by the existing methods due to the two-stage precoding structure. To tackle this, we propose a bi-convex approximation approach, which consists of three key ingredients: random matrix theory, chance constrained optimization and semidefinite relaxation. Then we propose an efficient algorithm to find the optimal solution of the resulting bi-convex approximation problem. Simulations show that the proposed design has significant gain over various baselines.
Keywords :
MIMO communication; antenna arrays; cellular radio; convex programming; interference suppression; matrix algebra; precoding; probability; quality of service; radiofrequency interference; space division multiplexing; telecommunication network reliability; wireless channels; BS; CSI signaling overhead reduction; QoS optimization problem; SINR; SINR probability; Tx subspace control; base station; biconvex approximation approach; chance constrained optimization; channel state information signaling overhead reduction; channel statistics; intercell interference mitigation; massive MIMO cellular system; massive antenna array; outage probability; random matrix theory; semidefinite relaxation; spatial multiplexing gain; transmit subspace control matrix; two-stage subspace constrained precoding; Approximation methods; Interference; MIMO; Optimization; Quality of service; Signal to noise ratio; Tin; Massive MIMO; QoS Guarantees; Subspace constrained precoding;
Journal_Title :
Wireless Communications, IEEE Transactions on
DOI :
10.1109/TWC.2015.2403364