Combined Beamforming and Space-Time Block Coding for High Speed Wireless Indoor Communications

The combination of a digital beamforming technique with space-time block coding in an indoor wireless environment is the purpose of this paper. Uplink transmission is achieved by an omnidirectional mobile antenna, with signals arriving at the base station having relatively wide angular spread. The spatial channel response, an estimate of the channel angular gain pattern, is obtained by using an array antenna at the base station. The array creates scanned multiple beams in azimuth and provides the effective angular spread of the incoming signals. These signals are assumed to be propagated in a microcell radio channel with a large number of single bounce multipath components. A simple algorithm estimates the number of beams for downlink transmission, and the transmitter beamforming network in the base station provides the required beams. Based on the number of beams, different signals are transmitted simultaneously. In particular, space-time block coding is applied to the beams. The performance of the proposed method is studied with respect to the number of transmited beams and of multipath components.