High Time Resolution Carrier Interferometry for MIMO/OFDM

In MIMO systems, channel estimation is important to distinguish transmit signals from multiple transmit antennas. When MIMO systems are introduced in cellular systems, we have to measure the received power from all the connectable base station (BS), as well as to identify all the channel state information (CSI) for the combination of transmitter and receiver antenna elements. One of the most typical channel estimation schemes for MIMO in a cellular system is to employ a code division multiplexing (CDM) based scheme in which a unique spreading code is assigned to identify both BS and MS antenna elements. However, by increasing the number of transmit antenna elements, a large spreading code and pilot symbols are required to estimate an accurate CSI. To reduce this problem, in this paper, we propose a high time resolution carrier interferometry (HTRCI) for MIMO/OFDM to achieve an accurate CSI without increasing the number of pilot symbols.