Novel frequency-domain DFE equalizer with oblique projection for CP-free space-time block coded MIMO-OFDM systems

An Interference Nulling Based Channel Independent Precoding for MIMO-OFDM Systems with Insufficient Cyclic Prefix

“…From (6), the received frequency domain signal for the kth OFDM block can be equivalently expressed as:…”

“…A considerably long CP is needed if the multipath delay spread is large, resulting in a substantial loss in both bandwidth and power efficiencies. In order to improve the transmission efficiency, MIMO-OFDM systems with insufficient CP have been studied significantly in the past, see, for example, [1]- [6], and OFDM/DMT systems with insufficient CP, in, for example, [7]- [9]. In [4], an ICI and ISI aware beamforming algorithm is proposed based on the optimal steering vector design that requires the channel state information at the transmitter (CSIT).…”

“…Instead of adding sufficient redundancies in the time domain, the technique proposed in [9] adds redundancies in the frequency domain by adding unused subcarriers. Some other techniques have been also proposed in [1]- [3], [5], [6], [8].…”