Unequal error protection with eigen beamforming for partial channel information MIMO-OFDM

Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading algorithm, bits are distributed across the unitarily transformed eigenbeams in case of partial channel information (CSI) knowledge. However, ideal performance can not withstand the rapid wireless channel variation unless a restricted beamforming is used. For the case of partial CSI, we proposed a switched beamforming technique that can maintain the required performance protection levels.