  N-continuous orthogonal frequency division multiplexing (NC-OFDM) is a
promising technique to obtain significant sidelobe suppression for baseband
OFDM signals, in future 5G wireless communications. However, the precoder of
NC-OFDM usually causes severe interference and high complexity. To reduce the
interference and complexity, this paper proposes an improved time-domain
N-continuous OFDM (TD-NC-OFDM) by shortening the smooth signal, which is
linearly combined by rectangularly pulsed OFDM basis signals truncated by a
smooth window. Furthermore, we obtain an asymptotic spectrum analysis of the
TD-NC-OFDM signals by a closed-form expression, calculate its low complexity in
OFDM transceiver, and derive a closed-form expression of the received
signal-to-interference-plus-noise ratio (SINR). Simulation results show that
the proposed low-interference TD-NC-OFDM can achieve similar suppression
performance but introduce negligible bit error rate (BER) degradation and much
lower computational complexity, compared to conventional NC-OFDM.
