Location based beamforming

When channel state information is available at the transmitter, it can be exploited to increase the throughput, or to enhance the performance of a multiple input multiple output (MIMO) system. Beamforming schemes, such as closed loop MIMO and transmit beamforming constitute efficient means to achieve the aforementioned objectives. A significant shortcoming of transmit beamforming schemes is the signaling overhead required to provide the transmitter with the downlink channel knowledge. Another drawback of transmit beamforming schemes is their sensitivity to channel state information accuracy. In this paper we suggest an alternative beamforming method that uses the receiver positioning data, for example GPS positioning data, to create the transmit beamforming vector. This approach is attractive as in many modern communications systems location based services provide the transmitter (for example a cellular base station) with continuous information respective to the physical position of the receiver (the celluar phone in this case). The location based beamforming method constructs precoding vectors that are optimized for line of sight scenarios. Our simulations show that line of sight precoders are superior to regular codebooks based precoders, such as the IEEE802.16e codebook, in line of sight scenarios. Surprisingly the proposed precoders exhibit acceptable (and even superior) performance in some non line of sight scenarios.