Transmit Diversity and Multiplexing Methods for 3G-LTE Downlink Control Channels

In order to provide a smooth migration toward 4G, studies on 3G long-term Evolution (3G-LTE) have been announced recently in third generation partnership project (3GPP) [1] and standardization work is under way. This paper investigates multiplexing method combined with transmit antenna diversity for the downlink control channels in 3G- LTE. Four schemes, such as FDM-STBC, CDM-STBC, FDM- SFBC and CDM-SFBC, are investigated for the downlink control channels, in particular, for one bit type control channels. Through computer simulation, the receiver performance of these candidate schemes are analyzed under multi-path fading channel environments. The effects of channel estimation, Doppler shift and the number of users on the performance are investigated. It is shown that the CDM-SFBC outperforms other schemes. We believe that results will provide beneficial information to design the 3G-LTE downlink control channels.