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11. 发明申请

US20090073869A1 Novel receiver architecture for pilot based OFDM systems 有权
标题翻译：基于导频的OFDM系统的新型接收机架构
公开(公告)号：US20090073869A1
公开(公告)日：2009-03-19
申请号：US12291905
申请日：2008-11-14
申请人： Kanu Chadha , Manish Bhardwai
发明人： Kanu Chadha , Manish Bhardwai
IPC分类号： H04J11/00
CPC分类号： H04L27/2662 , H04L27/266 , H04L27/2675
摘要： The invention relates to a novel methodology and apparatus for clock-offset compensation and common-phase offset correction in Frequency Division Multiplixing based wireless local area network (WLAN) environment, such as an Orthogonal Frequency Division Multiplexing (OFDM) environment. A curve fit, such as a threshold-based, least mean squares (LMS) fit of phase of the pilot sub-carriers in each OFDM symbol is used to estimate and counteract the rotation of the data sub-carriers due to residual frequency offset, low frequency phase noise, and clock offset. The invention is particularly well suited to wireless channels with multipath where pilots typically undergo frequency-selective fading. The thresholding LMS is implemented in a hardware-efficient manner, offering cost advantages over a weighted-LMS alternative. Additionally, the invention uses a unique phase-feedback architecture to eliminate the effects of phase wrapping, and avoid the need to refine channel estimates during packet reception.
摘要翻译：本发明涉及一种用于基于频分复用的无线局域网（WLAN）环境中的时分偏移补偿和公共相位偏移校正的新颖的方法和装置，例如正交频分复用（OFDM）环境。使用曲线拟合，例如每个OFDM符号中的导频子载波的相位的基于阈值的最小均方（LMS）拟合，以估计和抵消由于残余频率偏移导致的数据子载波的旋转，低频相位噪声和时钟偏移。本发明特别适用于具有多径的无线信道，其中导频通常经历频率选择性衰落。阈值LMS以硬件有效的方式实现，提供了超过加权LMS替代方案的成本优势。此外，本发明使用独特的相位反馈架构来消除相位缠绕的影响，并且避免在分组接收期间精细化信道估计的需要。

12. 发明授权

US07415059B2 Method and system for fast timing recovery for preamble based transmission systems 有权
标题翻译：用于基于前导码的传输系统的快速定时恢复的方法和系统
公开(公告)号：US07415059B2
公开(公告)日：2008-08-19
申请号：US10712800
申请日：2003-11-13
申请人： Kanu Chadha , Maneesh Soni , Manish Bhardwaj
发明人： Kanu Chadha , Maneesh Soni , Manish Bhardwaj
IPC分类号： H03D1/00 , H04L27/06
CPC分类号： H04L27/2675 , H04L27/261 , H04L27/2663 , H04L27/2665 , H04L27/2676
摘要： Using a combination of auto-correlation and cross-correlation techniques provides a symbol timing recovery in a Wireless Local Area Network (WLAN) environment that is extremely robust to wireless channel impairments such as noise, multi-path and carrier frequency offset. An auto-correlator provides an estimate for a symbol boundary, and a cross-correlator is subsequently used to more precisely identify the symbol boundary. Peak processing of the cross-correlation results provides further refinement in symbol boundary detection. In receiving a packet conforming to the IEEE 802.11a standard, the method requires a minimum of only three short symbols of the 802.11a short preamble to determine timing, and guarantees timing lock within the duration of the 802.11a short preamble. This method and system can be easily applied to any other preamble based system such as 802.11g and High Performance Radio LAN/2 (HIPERLAN/2).
摘要翻译：使用自相关和互相关技术的组合在无线局域网（WLAN）环境中提供对诸如噪声，多径和载波频率偏移之类的无线信道损伤非常鲁棒的符号定时恢复。自相关器提供符号边界的估计，随后使用互相关器更精确地识别符号边界。互相关结果的峰值处理提供了符号边界检测的进一步细化。在接收符合IEEE 802.11a标准的数据包时，该方法只需要802.11a短前导码中只有三个短符号，以确定定时，并保证802.11a短前导码持续时间内的定时锁定。该方法和系统可以容易地应用于诸如802.11g和高性能无线LAN / 2（HIPERLAN / 2）的任何其它基于前导码的系统。

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