This article proposes a time/frequency synchronization algorithm in the multiple input multiple output （MIMO） systems, in which the perfect complete generalized complementary orthogonal loosely synchronous code grou...This article proposes a time/frequency synchronization algorithm in the multiple input multiple output （MIMO） systems, in which the perfect complete generalized complementary orthogonal loosely synchronous code groups are used as the synchronization sequence. The synchronization algorithm is divided into four stages： 1） synchronization in time domain by signal autocorrelation; 2） synchronization in frequency domain by fast Fourier transform （FFT）; 3） multipath dissociation using coherent detection and fine time synchronization; 4） fine frequency offset estimation by phase rotation. As per the perfect complete generalized complementary orthogonal loosely synchronous code groups, the cross-correlation and out-of-phase auto-correlation for any relative shift between any two codes is always zero. This ideal property makes the time/frequency synchronization algorithm simple and efficient. The simulation results show that even in the multipath fast fading channel with low signal noise ratio （SNR）, the MIMO system can get synchronized both in the time domain and frequency domain with high stability and reliability.展开更多
This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of...This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of the single subcarrier modulation in a conventional MC DS-CDMA scheme, this novel scheme introduces the nonorthogonal subcarrier-group modulation, whose interferences caused by the non-orthogonal spacing in a subcarrier group can be reduced by a multicode detector. A detailed analysis for this system architecture and also a multiple-input-multiple output （MIMO） MC DS-CDMA solution to satisfy the requirement of beyond 3G mobile communication system are proposed. Simulated results demonstrate that this scheme can obtain excellent bit error rate （BER） performance, as well as achieve more than twice the spectral efficiency as that of conventional MC DS-CDMA systems.展开更多
基金supported by the National Natural Science Foundation of China(90604035)
文摘This article proposes a time/frequency synchronization algorithm in the multiple input multiple output （MIMO） systems, in which the perfect complete generalized complementary orthogonal loosely synchronous code groups are used as the synchronization sequence. The synchronization algorithm is divided into four stages： 1） synchronization in time domain by signal autocorrelation; 2） synchronization in frequency domain by fast Fourier transform （FFT）; 3） multipath dissociation using coherent detection and fine time synchronization; 4） fine frequency offset estimation by phase rotation. As per the perfect complete generalized complementary orthogonal loosely synchronous code groups, the cross-correlation and out-of-phase auto-correlation for any relative shift between any two codes is always zero. This ideal property makes the time/frequency synchronization algorithm simple and efficient. The simulation results show that even in the multipath fast fading channel with low signal noise ratio （SNR）, the MIMO system can get synchronized both in the time domain and frequency domain with high stability and reliability.
基金This study is supported by the National Natural Science Foundation of China （90604035）.
文摘This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of the single subcarrier modulation in a conventional MC DS-CDMA scheme, this novel scheme introduces the nonorthogonal subcarrier-group modulation, whose interferences caused by the non-orthogonal spacing in a subcarrier group can be reduced by a multicode detector. A detailed analysis for this system architecture and also a multiple-input-multiple output （MIMO） MC DS-CDMA solution to satisfy the requirement of beyond 3G mobile communication system are proposed. Simulated results demonstrate that this scheme can obtain excellent bit error rate （BER） performance, as well as achieve more than twice the spectral efficiency as that of conventional MC DS-CDMA systems.
