Cooperative spectrum sensing can improve the detection reliability in cognitive radio network. How to report the local sensing results to the fusion center has not aroused much interest. Since OFDM has been widely recognized as a promising candidate for cognitive radio in opportunistic spectrum access scenarios, a OFDMA-based sensing reporting scheme is designed. Correspondingly, several fusion rules at fusion center side are proposed according to the knowledge of the reporting channel and local sensing performance indices. It is shown by simulations that the fusion with the perfect reporting channel state information is optimum. If the fusion center has no knowledge of the reporting channel, soft fusion outperforms hard decision combination. Fusion with the statistic knowledge of the reporting channel is valid for practical use.