The Research of Beamforming in WiMAX System

As the close-loop beam forming needs to occupy extra system resource, the proposed paper presents two scenarios for open-loop beam forming, according to the 802.16e protocol. With utilizing pilots in uplink data zone and fast-feedback zone, it estimates the channel information, and then achieves open-loop beam forming. Especially, the shape of uplink data zone is designed as sounding zone. After analyzing characteristics of Piecewise linear interpolation, Lagrange polynomial interpolation and cubic spline interpolation, the paper adopts Piecewise linear interpolation to estimating channel state information and follows the Maximal Signal-to-Noise Ratio principle, then calculates weight vectors, finally completes beam forming. The paper simulates two scenarios respectively and analyses simulating results.