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    Synchronisation
    3.
    发明授权
    Synchronisation 有权
    同步

    公开(公告)号：US06751261B1

    公开(公告)日：2004-06-15

    申请号：US09147230

    申请日：1999-02-09

    申请人： Lennart Olsson ,  Gunnar Bahlenberg ,  Daniel Bengtsson ,  Siwert Håkansson ,  Anders Isaksson ,  Lars-Ake Isaksson ,  Mikael Isaksson ,  Magnus Johansson ,  Mauritz Lahti ,  Lis-Marie Ljunggren ,  Hans Lundberg ,  Tomas Nordstrom ,  Sven-Rune Olofsson ,  Tomas Stefansson ,  Hans Oman ,  Goran Okvist

    发明人： Lennart Olsson ,  Gunnar Bahlenberg ,  Daniel Bengtsson ,  Siwert Håkansson ,  Anders Isaksson ,  Lars-Ake Isaksson ,  Mikael Isaksson ,  Magnus Johansson ,  Mauritz Lahti ,  Lis-Marie Ljunggren ,  Hans Lundberg ,  Tomas Nordstrom ,  Sven-Rune Olofsson ,  Tomas Stefansson ,  Hans Oman ,  Goran Okvist

    IPC分类号： H04L506

    CPC分类号： H04L27/2662 ,  H04L27/2657 ,  H04L27/2672 ,  H04L27/2678

    摘要： With OFDM systems the frequency domain data is the Fourier transform of the received time domain OFDM frames. The time domain frames must be sampled, at the receiver, in synchronism with the transmitter, so that each received frame contains data from only a single transmitted frame. It is vital for this synchronism to be maintained in order to maintain the orthogonality of the frames. A typical multi-carrier system, of the OFDM type, which uses a cyclic prefix permits orthogonality to be maintained when there is a small deviation from exact frame synchronisation. Because the signalling interval includes both an entire frame and the cyclic prefix, which is a repetition of part of the frame, a frame sampled within the signalling interval will contain data from only one frame. Since the signalling interval is greater than the frame period, this gives some leeway in frame alignment. In a multi-carrier system of the OFDM type, an adaptive channel equalizer, operating in the frequency domain, is often used. The internal parameters in such an equalizer contain, in addition to information about the characteristics of the channel, information which can be interpreted as the time deviation between the sampling clocks of the transmitter and the receiver. The present invention utilizes this information to control the sampling clock of the receiver in a more robust way than has previously been possible with known techniques. The present invention is particularly suitable for use in ADSL and VDSL modems which can be used to give broadband access over copper networks. The invention is also of relevance to broadband transmission in mobile and semi-mobile systems for transmission over the radio channels.

    摘要翻译： 对于OFDM系统，频域数据是接收的时域OFDM帧的傅里叶变换。 必须在接收机处与发射机同步地采样时域帧，使得每个接收的帧包含来自仅一个发射帧的数据。 为了保持帧的正交性，保持该同步是至关重要的。 使用循环前缀的OFDM类型的典型多载波系统当与精确帧同步的偏差很小时，允许维持正交性。 由于信令间隔包括作为帧的一部分的重复的整个帧和循环前缀，所以在信令间隔内采样的帧将仅包含来自一个帧的数据。 由于信令间隔大于帧周期，所以在帧对齐中给出了一些余地。 在OFDM类型的多载波系统中，经常使用在频域中工作的自适应信道均衡器。 除了关于信道特性的信息之外，这种均衡器中的内部参数还包含可被解释为发射机和接收机的采样时钟之间的时间偏差的信息。 本发明利用该信息以比先前已知技术可能的更可靠的方式来控制接收机的采样时钟。 本发明特别适用于ADSL和VDSL调制解调器，可用于通过铜网络提供宽带接入。 本发明还涉及用于在无线电信道上传输的移动和半移动系统中的宽带传输。