Adaptive time diversity and spatial diversity for OFDM

摘要

An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

主权项

1. A device, comprising:
a plurality of first antennas configured to transmit a respective plurality of feedback signals from a channel to second antennas of a receiving device in response to receiving a plurality of Orthogonal Frequency-Division Multiplexing (OFDM) signals from the receiving device, the OFDM signals utilizing a common set of sub-carriers, the OFDM signals being received onto the channel by the first antennas, the first antennas further configured to receive feedback information from the receiving device, the feedback information encoding transmission type decisions for groups of sub-carriers, the transmission type decisions representing a selection between a transmit diversity and a spatial multiplexing (SM).