Beamforming in Chunk-Based OFDM Systems

In this paper we first introduce a fixed beamfroming (BF) technique for orthogonal frequency division multiplexing (OFDM) systems. The basic idea of beamforming is that the phase of the transmitted signal is shifted according to the user direction, while at the receiver side, the phase shifting performs again to maximize the received signal-to-noise ratio (SNR). We also propose a discrete Fourier transform (DFT) based estimation algorithm which can estimate the beam domain channel. To reduce the computational complexities and feedback signaling, we do beamforming and channel estimation based on the chunk, which is a unit that occupies several symbol time intervals and subcarriers. The simulation results show the performance of the proposed beamforming technique associated with channel estimation algorithm. We also compare the beamforming technique we proposed with Alamouti space-time block coding (STBC).