We firstly investigate an ideal multi path channel where MAI is only introduced by multi path fading channels .
As seen in Fig. 6, both in moderate loading (K = 16) and heavy loading (K = 32), the FDO-MMSE receiver outperforms traditional PU-MMSE receiver in terms of BER. Especially, when BER=10−4, the FDO-MMSE receiver can obtain 2dB performance improvement in case of heavy loading. Meanwhile, a cognitive-CDMA system is intrinsically a multi carrier signaling, which requires the strict orthogonality among sub carriers and is therefore sensitive to CFO. Hence, BER performances of different MMSE receivers in present of CFO are shown in Fig. 7. Clearly, the PU-MMSE receiver shows bad BER performance due to inter-carrier interference from CFO. However for our proposed FDO-MMSE receiver, it achieves a comparable robust BER performance under the effect of both frequency selective fading channels and CFO.
We firstly investigate an ideal multi path channel where MAI is only introduced by multi path fading channels . As seen in Fig. 6, both in moderate loading (K = 16) and heavy loading (K = 32), the FDO-MMSE receiver outperforms traditional PU-MMSE receiver in terms of BER. Especially, when BER=10−4, the FDO-MMSE receiver can obtain 2dB performance improvement in case of heavy loading. Meanwhile, a cognitive-CDMA system is intrinsically a multi carrier signaling, which requires the strict orthogonality among sub carriers and is therefore sensitive to CFO. Hence, BER performances of different MMSE receivers in present of CFO are shown in Fig. 7. Clearly, the PU-MMSE receiver shows bad BER performance due to inter-carrier interference from CFO. However for our proposed FDO-MMSE receiver, it achieves a comparable robust BER performance under the effect of both frequency selective fading channels and CFO.
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