System performance of distributed transmit diversity for OFDM-based 1xEV-DO broadcast networks

This paper considers the application of distributed transmit diversity (TD) to digital broadcast networks. Distributed TD allows spatial encoding across transmit sectors (cell-sites or satellites) each with a single antenna. We focus on Alamouti space-frequency (SF) codes in particular and consider terrestrial systems based on cellular type networks. System coverage results are presented for a 1xEV-DO broadcast network based on a comprehensive evaluation methodology developed in 3GPP2 for system modeling and orthogonal frequency division modulation (OFDM). The results show that distributed transmit diversity can deliver significant coverage gains. For example, given a bandwidth of 1.25 MHz, a data rate of 1.2 Mbps and a minimum bit-error rate (BER) requirement of 0.1%, the broadcast coverage increases from roughly 40% in the absence of distributed TD to 70% with the Alamouti linear combiner and to 82% with a zero-forcing (ZF) spatial equalizer