Without a cyclic prefix (CP), most single-carrier (SC) transmissions can not adopt frequency-domain equalizer (FDE) directly. This work utilizes frequency-domain channel estimator (FD-CE) and decision-feedback aliasing canceller (DF-AC) to produce single-FFT SC-FDE. In this way, non-CP single-carrier block transmission (SCBT) can be decoded using sphere decoder of MIMO-OFDM modems to support multimode and backward compatibility under an acceptable complexity in IEEE 802.11 very high throughput (VHT). An iV-point FFT is sufficient to measure channel frequency responses (CFR) from .L-sample preambles (L ≤ JV/2). And then, M-bit block codes (M ≤ L) are decodable over frequency domains with DF-AC's help. Simulations and measurements imply that this work can ensure adequate performance, even if there is no CP existed against the distortions of multipath propagation.