Research Of Key Technology On Three Dimensional Beamforming

Along with the widespread application of small cell deployment, the demand for interference coordination is also in explosive growth. Sufficient use of information from the spatial domain is one of the indispensable aspects to reduce mutual interference. Massive antenna array efficiently uses spatial domain information. Development of this technology makes three-dimensional beamforming (3D-beamforming) possible.3D-beamforming is a key technology of Long Term Evolution-Advanced (LTE-A) mobile communication system, and is an efficient user-specific transmission scheme.Firstly, an overview of beamforming techniques is presented, including the structure of beamforming system and several common guidelines, as well as an universal model for antenna array received signal. With these basic knowledge, introduction of some traditional methods for Direction of Arrival (DOA) estimation, the basis of effective beamforming, is made. Detailed analysis is carried out particularly for a Total Least Squares-Estimation of Signal Parameters via Rotational Invariance Techniques (TLS-ESPRIT) algorithm, which is applicable to rectangle massive antenna array.Then an algorithm that combines the above TLS-ESPRIT algorithm with Orthogonal Frequency Division Multiplexing (OFDM) algorithm is proposed. The algorithm achieves a joint estimation of DOA and channel impulse response for multiuser multipath environment. Simulation results show that this algorithm can resist the influence caused by multipath and phase shift of antenna array with received signal effectively.This paper proposes a two-layer beamforming algorithm for base station (BS) in wireless communication system. The algorithm takes advantages of both Smart Antenna (SA) and multiple-input multiple-output (MIMO). It can increase transmission speed, improve operation accuracy and system performance, and is suitable for time division duplex (TDD) and frequency division duplex (FDD) systems.Finally, considering the imperfection of existing hybrid beamforming algorithm used in massive antenna array, a hybrid 3D beamforming algorithm with high angular resolution is proposed for intensive multiuser environment. It can be applied to both TDD and FDD systems. Compared with existing hybrid beamforming algorithm, this algorithm can get reduction of system overhead, efficiently reduce mutual interference between user equipments (UE) in intensive multiuser environment, and improve system throughput.