In this paper, we propose a new spatial-multiplexing (SM) scheme employing an orthogonal precoder over Rayleigh-fad-ing channels for an erasure event in single frequency networks (SFN). To optimize the precoder, the average bit error rate (BER) is evaluated and minimized through a mathe-matical analysis. Compared to an ordinary SM, the proposed scheme guarantees identical BER performance under non-erasure fading channels and achieves a greatly improved performance under erasure fading channels, especially for a higher erasure-ratio and SNR values. This improvement is mainly due to the increase in the diversity gain incurred by the optimized precoder over the erasure event. We also compare the performance of the proposed SM to that of the conventional constella-tion-rotation (CR) scheme applied to the single antenna SFN systems. The results of a com-puter simulation show that the performance of the new scheme is more effective than that of a conventional CR across all simulation cases.