An interference nulling based channel independent precoding for MIMO-OFDM systems with insufficient cyclic prefix

In this paper, a new interference nulling based channel independent precoding for MIMO-OFDM systems of n_t transmit and n_r receive antennas with insufficient cyclic prefix (CP) is proposed. By employing the notion of interference nulling, we show that our proposed channel independent precoding scheme can eliminate the inter-block interference (IBI) caused by the insufficient CP with higher bandwidth efficiency than the conventional zero-padded or a sufficient CP added block transmission system when n_r≤ n_t. It is also shown that when n _r>n_t, the IBI can be eliminated without the need of any zero-padding or adding CP or precoding when the OFDM block length is not too small.