A multi-antenna transmitting entity transmits data to a single- or multi-antenna receiving entity using (1) a steered mode to direct the data transmission toward the receiving entity or (2) a pseudo-random transmit steering (PRTS) mode to randomize the effective channels observed by the data transmission...http://www.google.co.uk/patents/US20050180312?utm_source=gb-gplus-sharePatent US20050180312 - Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
