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State detection techniques for digital subscriber line systems.

机译：数字用户线系统的状态检测技术。

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摘要

While digital subscriber line (DSL) transmission environments are typically modeled as time-invariant systems, certain events make the system better described by a model where the environment is in one of several states. For typical DSL scenarios, the descriptions of each state can be saved in memory. Hence, instead of estimating a new state, DSL modems need only detect the state by referring to this saved information. This will be known as state detection in the DSL system. We introduce this state model to increase loop reach, data rate, and robustness to intermittent changes.; In splitterless DSL, the channel response can change whenever a phone switches from being on-hook to off-hook, or vice-versa. This may lead to the need to retrain. However, full retraining can be averted by saving the channel response for each on/off-hook configuration and detecting which channel response is present. In simulations, recovery time is reduced from more than 1 second to less than .06 seconds.; In multiuser DSL transmission we propose allowing crosstalk modems to transmit energy only when they transmit information. Using a state model, we discuss how to take advantage of times during which the crosstalk interference is minimal or when the crosstalk interference can be canceled. This can lead to large increases in data rate or loop reach. We develop several detection schemes and investigate their performance. In some cases data rates can more than double.; While such bursty DSL transmission can lead to significant performance enhancements, service providers are worried about legacy systems that cannot adapt to changing noise conditions quickly. So, current modems often transmit all the time in order to maintain a consistent environment. We therefore propose sending a fixed symbol when information is not being sent, called a Qmode signal. Detection of the Qmode signal and subsequent cancellation can increase data rates significantly and allow for longer loop lengths. We develop a statistic for the detection of the Qmode signal and a new inspection scheme that can quickly determine its presence.
机译：尽管通常将数字用户线（DSL）传输环境建模为时不变系统，但是某些事件使该系统可以通过环境处于几种状态之一的模型更好地描述。对于典型的DSL场景，每个状态的描述都可以保存在内存中。因此，代替估计新状态，DSL调制解调器仅需要通过参考该保存的信息来检测状态。在DSL系统中，这称为状态检测。我们引入这种状态模型来增加循环覆盖率，数据速率和对间歇性变化的鲁棒性。在无分离器DSL中，每当电话从挂机切换到摘机（反之亦然）时，通道响应都会改变。这可能导致需要重新培训。但是，可以通过为每个挂机/摘机配置保存信道响应并检测存在哪个信道响应来避免完全重新训练。在仿真中，恢复时间从1秒钟以上减少到0.06秒钟以下。在多用户DSL传输中，我们建议允许串扰调制解调器仅在它们传输信息时才传输能量。使用状态模型，我们讨论了如何利用串扰最小或可以消除串扰的时间。这会导致数据速率或环路范围的大幅增加。我们开发了几种检测方案，并研究了它们的性能。在某些情况下，数据速率可能会增加一倍以上。尽管这种突发性DSL传输可以显着提高性能，但服务提供商担心传统系统无法快速适应不断变化的噪声状况。因此，当前的调制解调器通常一直在传输数据，以保持一致的环境。因此，我们建议在不发送信息时发送一个固定的符号，称为Qmode信号。 Qmode信号的检测和随后的消除可以显着提高数据速率，并允许更长的环路长度。我们开发了用于检测Qmode信号的统计数据和可以快速确定其存在的新检查方案。

著录项

  • 作者

    Salvekar, Atul Arvind.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 110 p.
  • 总页数 110
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;
  • 关键词

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