以正交频分复用(orthogonal frequency division multiplexing,OFDM)调制为基础的宽带电力线通信技术,为智能电网、智能家居以及"最后一公里"提供了高效可靠的信息传输方案,然而OFDM对同步错误极度敏感,针对此问题,采用多相...以正交频分复用(orthogonal frequency division multiplexing,OFDM)调制为基础的宽带电力线通信技术,为智能电网、智能家居以及"最后一公里"提供了高效可靠的信息传输方案,然而OFDM对同步错误极度敏感,针对此问题,采用多相序列作为主同步信号的多用户帧结构,利用一种新的多相序列族(用于用户群搜索)作为主同步信号,序列族的设计不仅要考虑每个序列都有更优良的自相关特性即更高的峰值对旁瓣峰值比,还要求有很好的互相相关特性以对抗其他用户训练序列引起的用户间干扰。多用户系统中不同用户采用不同的序列作为同步序列,这种方法对系统的复杂性没有任何影响。在作者自制的硬件平台上实现了该算法,实验和仿真结果均表明该同步设计更适用于电力线环境。展开更多
New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are...New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are modulatable orthogonal polyphase sequences,which have both good autocorrela-tions and cross-correlations.The channel impulse response (CIR) can be obtained by measuring the cor-relation between the received training sequence and the locally generated training sequence.The trainingsequences are used as guard interval instead of cyclic prefix,which not only improve the transmission ef-ficiency but also enable the channel estimator to track time-varying channel.The simulation results showthat the proposed method has about 2dB SNR gain over conventional methods in fast time-varying chan-nel.展开更多
For an odd prime p, a new sequence family of period prom- 1, size （M-1）pmr is proposed using multi-plicative and additive characters. The upper bound for the maximum magnitude of nontrivial correlations of the seque...For an odd prime p, a new sequence family of period prom- 1, size （M-1）pmr is proposed using multi-plicative and additive characters. The upper bound for the maximum magnitude of nontrivial correlations of the sequence family is derived using well-known character sums. The upper bound is shown to be （r ＋ 1）√pm ＋ 3, which meets the Welch bound asymptotically.展开更多
文摘以正交频分复用(orthogonal frequency division multiplexing,OFDM)调制为基础的宽带电力线通信技术,为智能电网、智能家居以及"最后一公里"提供了高效可靠的信息传输方案,然而OFDM对同步错误极度敏感,针对此问题,采用多相序列作为主同步信号的多用户帧结构,利用一种新的多相序列族(用于用户群搜索)作为主同步信号,序列族的设计不仅要考虑每个序列都有更优良的自相关特性即更高的峰值对旁瓣峰值比,还要求有很好的互相相关特性以对抗其他用户训练序列引起的用户间干扰。多用户系统中不同用户采用不同的序列作为同步序列,这种方法对系统的复杂性没有任何影响。在作者自制的硬件平台上实现了该算法,实验和仿真结果均表明该同步设计更适用于电力线环境。
基金the National High Technology Research and Development Program of China(No.2006AA01Z270)the National Natural Science Foundation of China(No.60332030,60496316)
文摘New training sequences and frame structure are proposed to estimate time-varying channel for multi-pie-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems.Thetraining sequences are modulatable orthogonal polyphase sequences,which have both good autocorrela-tions and cross-correlations.The channel impulse response (CIR) can be obtained by measuring the cor-relation between the received training sequence and the locally generated training sequence.The trainingsequences are used as guard interval instead of cyclic prefix,which not only improve the transmission ef-ficiency but also enable the channel estimator to track time-varying channel.The simulation results showthat the proposed method has about 2dB SNR gain over conventional methods in fast time-varying chan-nel.
文摘For an odd prime p, a new sequence family of period prom- 1, size （M-1）pmr is proposed using multi-plicative and additive characters. The upper bound for the maximum magnitude of nontrivial correlations of the sequence family is derived using well-known character sums. The upper bound is shown to be （r ＋ 1）√pm ＋ 3, which meets the Welch bound asymptotically.
