Algorithm for Detecting the Number of Transmit Antennas in MIMO-OFDM Systems

In wireless MIMO-OFDM systems, knowledge of the channel between all transmit-receive antenna pairs is essential to enable the decoupling of spatial streams and coherent data detection at a receiver. Regarding a typical preamble design for MIMO channel estimation in an ad-hoc network, the preamble structure depends on the number of transmit antennas and this number must be known before the actual MIMO channel estimation is accomplished. In this work, we propose an algorithm to detect the number of transmit antennas, using only the received pilot sequences intended for MIMO channel estimation. Thus, no explicit signaling is needed, i.e. overhead and transmission latency can be reduced.