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Allowing a Large Access Timing Offset in OFDM-CDMA Using ZCZ Code and Block Spreading
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 Title & Authors
Allowing a Large Access Timing Offset in OFDM-CDMA Using ZCZ Code and Block Spreading
Na, Donj-jun; Choi, Kwonhue;
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We propose a new type of OFDM-CDMA scheme which allows large inter-user timing offset using zero correlation zone(ZCZ) code in conjunction with block spreading technique. Moreover to maximize spectral efficiency, the proposed OFDMA does not have guard time(GT). This is opposite to the trends in the conventional schemes where GT are supposed to be larger to allow larger inter-user timing offset. It is remarkable that the proposed GT-free OFDM-CDMA scheme completely cancels inter-user interference in the multipath fading simply by despreading process. This inter-user interference-free feature still remains even there exist inter-user timing offsets as large as multiple OFDM symbols. Although the self-user interference exists due to no GT, it can be effectively suppressed by simple successive interference cancellation(SIC) from the first symbol in spread block as it is free from inter symbol interference(ISI).
uplink;OFDMA;ZCZ code;Block spreading;access timing offset;
 Cited by
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