Location aided transmit strategy in two-way relay networks

In this paper, a simple transmit beamforming scheme over MISO channel in two-way relay networks is proposed. Beam in the proposed scheme is built to maximize sum of the receive power of the two receivers according to their geographic location. The key consideration is to estimate signal direction of arrival (DOA) with the location information supported by localization and tracking instead of using complex DOA estimation algorithm. System performance impacted by DOA of signal of each receiver is analyzed. Two special DOA cases-coherent position and orthogonal position are shown, which bound the performance of this scheme. In coherent position, both receivers will benefit 3 dB array gain, while in orthogonal position system performs as two separate SISO channel. Theoretical and simulative analyses of the transmit strategy is carried out. It is found that the proposed scheme can support simple and higher rate transmission over MISO channel, and suitable to relay networks.