公开(公告)号：US20060227812A1

公开(公告)日：2006-10-12

申请号：US11373764

申请日：2006-03-09

申请人： Bojan Vrcelj ,  Ashok Mantravadi ,  Fuyun Ling ,  Krishna Mukkavilli

发明人： Bojan Vrcelj ,  Ashok Mantravadi ,  Fuyun Ling ,  Krishna Mukkavilli

IPC分类号： H04J3/06

CPC分类号： H04L25/0232 ,  H04L25/0212 ,  H04L25/0224 ,  H04L25/025 ,  H04L27/2662 ,  H04L27/2665

摘要： Systems and methods are provided for determining and applying timing corrections in a digital communications system. In an aspect, a timing correction method is provided for a multi-carrier system. This includes aligning two or more symbols with respect to each other from a symbol subset in order to account for timing differences between the symbols. The symbol alignment is first carried out to generate channel estimates for data demodulation. The channel estimates, thus generated, along with the timing alignment information are in turn used for determining timing corrections to be applied to future symbols.

摘要翻译： 提供了用于在数字通信系统中确定和应用定时校正的系统和方法。 在一方面，为多载波系统提供定时校正方法。 这包括从符号子集彼此对准两个或更多个符号，以便考虑符号之间的时序差异。 首先执行符号对齐以产生用于数据解调的信道估计。 由此生成的信道估计与定时对准信息一起被用于确定要应用于未来符号的定时校正。

公开(公告)号：US20050063298A1

公开(公告)日：2005-03-24

申请号：US10931324

申请日：2004-08-31

申请人： Fuyun Ling ,  Alok Gupta ,  Raghuraman Krishnamoorthi ,  Ramaswamy Murali ,  Rajiv Vijayan ,  Bojan Vrcelj

发明人： Fuyun Ling ,  Alok Gupta ,  Raghuraman Krishnamoorthi ,  Ramaswamy Murali ,  Rajiv Vijayan ,  Bojan Vrcelj

IPC分类号： H04B3/10 ,  H04J20060101 ,  H04J1/16 ,  H04J11/00

CPC分类号： H04L27/2657 ,  H04L5/005 ,  H04L25/022 ,  H04L27/2613 ,  H04L27/2662 ,  H04L27/2665 ,  H04L2027/003

摘要： In an OFDM system, a transmitter broadcasts a first TDM pilot on a first set of subbands followed by a second TDM pilot on a second set of subbands in each frame. The subbands in each set are selected from among N total subbands such that (1) an OFDM symbol for the first TDM pilot contains at least S1 identical pilot-1 sequences of length L1 and (2) an OFDM symbol for the second TDM pilot contains at least S2 identical pilot-2 sequences of length L2, where L2>L1, S1·L1=N, and S2·L2=N. The transmitter may also broadcast an FDM pilot. A receiver processes the first TDM pilot to obtain frame timing (e.g., by performing correlation between different pilot-1 sequences) and further processes the second TDM pilot to obtain symbol timing (e.g., by detecting for the start of a channel impulse response estimate derived from the second TDM pilot).

摘要翻译： 在OFDM系统中，发射机在第一组子带上广播第一TDM导频，随后在每帧中的第二组子带上接收第二TDM导频。 每个组中的子带从N个总子带中选出，使得（1）第一TDM导频的OFDM符号包含长度为L1的至少S1个相同的导频1序列，以及（2）第二TDM导频的OFDM符号包含 至少S2个长度为L2的导频-2序列，其中L2> L1，S1.L1 = N，S2.L2 = N。 发射机还可以广播FDM导频。 接收机处理第一TDM导频以获得帧定时（例如，通过执行不同导频-1序列之间的相关）并且进一步处理第二TDM导频以获得符号定时（例如，通过检测导出的信道脉冲响应估计的开始 从第二TDM导频）。

公开(公告)号：US20070140322A1

公开(公告)日：2007-06-21

申请号：US11303589

申请日：2005-12-15

申请人： Michael Wang ,  Bojan Vrcelj ,  Fuyun Ling ,  Rajiv Vijayan

发明人： Michael Wang ,  Bojan Vrcelj ,  Fuyun Ling ,  Rajiv Vijayan

IPC分类号： H04B1/00

CPC分类号： H04L27/2656 ,  H04L27/261 ,  H04L27/2675

摘要： Apparatus and methods for use in a wireless communication system are disclosed for recovery of timing tracking in a device, such as a wireless transceiver, after decoding errors occur due to incorrect timing tracking. In particular, the disclosed methods and apparatus recover timing tracking by monitoring a decoded signal in the transceiver for decoding errors occurring during a first frame, determining whether a number of decoding errors is greater than a predetermined amount, reacquiring a first pilot channel at a start of a subsequently received second frame when the number of decoding errors is determined to be greater than the predetermined amount, and resetting timing tracking of the transceiver based on the reacquired first pilot channel.

摘要翻译： 在无线通信系统中使用的装置和方法被公开用于在诸如无线收发器的设备中恢复定时跟踪，在由于不正确的定时跟踪而导致解码错误之后。 具体地，所公开的方法和装置通过监视收发器中的解码信号来恢复定时跟踪，以解码在第一帧期间发生的错误，确定解码错误的数量是否大于预定量，在开始时重新获取第一导频信道 当确定解码错误的数量大于预定量时，随后接收到的第二帧，并且基于重新获取的第一导频信道来重置收发信机的定时跟踪。

公开(公告)号：US07623607B2

公开(公告)日：2009-11-24

申请号：US11264532

申请日：2005-10-31

申请人： Bojan Vrcelj ,  Fuyun Ling ,  Michael Mao Wang

发明人： Bojan Vrcelj ,  Fuyun Ling ,  Michael Mao Wang

IPC分类号： H04L7/00

CPC分类号： H04L27/2662 ,  H04L27/2676

摘要： Methods and apparatus for setting timing of sampling of one or more symbols. The disclosed methods account for at least three types of effective interference (EI) and are used to set the timing of a sampling window for sampling received symbols. The methods includes setting timing based on determining an energy density function accounting for both static and dynamic EI, determining the minimum of a total energy profile and sliding the sampling window to ensure that the minimum point is at a predetermined point, and determining and using a composite energy profile accounting for short term and long term fading effects. The disclosed apparatus include a transceiver employing one or more of the disclosed methods for setting timing when receiving the symbols.

摘要翻译： 用于设置一个或多个符号的采样定时的方法和装置。 所公开的方法至少有三种类型的有效干扰（EI），并且用于设置用于采样接收符号的采样窗口的定时。 所述方法包括基于确定静态和动态EI两者的能量密度函数来设定定时，确定总能量分布的最小值，并滑动采样窗口以确保最小点在预定点，以及确定和使用 复合能量曲线描述短期和长期衰落影响。 所公开的装置包括采用一种或多种所述方法的收发机，用于在接收符号时设置定时。

公开(公告)号：US08265214B2

公开(公告)日：2012-09-11

申请号：US12324818

申请日：2008-11-26

申请人： Bojan Vrcelj ,  Krishna Kiran Mukkavilli

发明人： Bojan Vrcelj ,  Krishna Kiran Mukkavilli

IPC分类号： H04L7/00

CPC分类号： H04L25/0212 ,  H04L27/2662 ,  H04L27/2665

摘要： An adaptive timing synchronization process dynamically adapts timing synchronization parameters for both wide and local area channels based on channel estimates. Timing synchronization parameters are dynamically adapted according to C/I estimates calculated from WID/LID energies. The timing synchronization algorithm 102 takes as the primary input, the current channel estimate 110 and produces an output comprising a correction to the current Fast Fourier Transform (FFT) sampling window position delta T (or offset) for locating the start of data within a current symbol 108. After dynamic parameter adjustment of noise filtering thresholds 104 and weak channel tap sensitivities 106 based on a calculated C/I from the channel estimate, a timing synchronization algorithm 102 locates the beginning of each continuous symbol by finding the boundary between the preamble, or cyclic prefix, and the useful data portions interlaced with pilots for channel information defining the start of a symbol 108.

摘要翻译： 基于信道估计，自适应定时同步过程动态地适应广域和局域信道的定时同步参数。 定时同步参数根据从WID / LID能量计算的C / I估计动态调整。 定时同步算法102将当前信道估计110作为主要输入，并产生包括对当前快速傅立叶变换（FFT）采样窗位置增量T（或偏移）的校正的输出，用于定位当前数据的开始 基于来自信道估计的计算出的C / I，在噪声滤波阈值104和弱信道抽头灵敏度106的动态参数调整之后，定时同步算法102通过找到前导码之间的边界来定位每个连续符号的开始， 或循环前缀，并且有用数据部分与用于定义符号108的开始的信道信息的导频隔行扫描。

公开(公告)号：US20100002817A1

公开(公告)日：2010-01-07

申请号：US12324818

申请日：2008-11-26

申请人： Bojan Vrcelj ,  Krishna Kiran Mukkavilli

发明人： Bojan Vrcelj ,  Krishna Kiran Mukkavilli

IPC分类号： H04L7/00

CPC分类号： H04L25/0212 ,  H04L27/2662 ,  H04L27/2665

摘要： An adaptive timing synchronization process dynamically adapts timing synchronization parameters for both wide and local area channels based on channel estimates. Timing synchronization parameters are dynamically adapted according to C/I estimates calculated from WID/LID energies. The timing synchronization algorithm 102 takes as the primary input, the current channel estimate 110 and produces an output comprising a correction to the current Fast Fourier Transform (FFT) sampling window position delta T (or offset) for locating the start of data within a current symbol 108. After dynamic parameter adjustment of noise filtering thresholds 104 and weak channel tap sensitivities 106 based on a calculated C/I from the channel estimate, a timing synchronization algorithm 102 locates the beginning of each continuous symbol by finding the boundary between the preamble, or cyclic prefix, and the useful data portions interlaced with pilots for channel information defining the start of a symbol 108.

摘要翻译： 基于信道估计，自适应定时同步过程动态地适应广域和局域信道的定时同步参数。 定时同步参数根据从WID / LID能量计算的C / I估计动态调整。 定时同步算法102将当前信道估计110作为主要输入，并产生包括对当前快速傅立叶变换（FFT）采样窗位置增量T（或偏移）的校正的输出，用于定位当前数据的开始 基于来自信道估计的计算出的C / I，在噪声滤波阈值104和弱信道抽头灵敏度106的动态参数调整之后，定时同步算法102通过找到前导码之间的边界来定位每个连续符号的开始， 或循环前缀，并且有用数据部分与用于定义符号108的开始的信道信息的导频隔行扫描。

公开(公告)号：US20060133388A1

公开(公告)日：2006-06-22

申请号：US11021310

申请日：2004-12-22

申请人： Michael Wang ,  Bojan Vrcelj ,  Krishna Mukkavilli ,  Raghuraman Krishnamoorthi ,  Rajiv Vijayan

发明人： Michael Wang ,  Bojan Vrcelj ,  Krishna Mukkavilli ,  Raghuraman Krishnamoorthi ,  Rajiv Vijayan

IPC分类号： H04L12/56

CPC分类号： H04L5/0048 ,  H04L5/0007 ,  H04L5/0083 ,  H04L27/261

摘要： The embodiments utilize OFDM symbols to communicate network IDs. The IDs are encoded into symbols utilizing the network IDs as seeds to scramble respective pilots that are then transmitted by utilizing the symbols. The pilots can be structured into a single OFDM symbol and/or multiple OFDM symbols. The single symbol structure for transmitting the network IDs is independent of the number of network ID bits and minimizes frequency offset and Doppler effects. The multiple symbol structure allows a much coarser timing accuracy to be employed at the expense of transmitting additional symbols. Several embodiments employ a search function to find possible network ID candidates from a transmitted symbol and a selection function to find an optimum candidate from a network ID candidate list.

摘要翻译： 这些实施例利用OFDM符号来传送网络ID。 ID被编码成使用网络ID作为种子的符号，以对通过利用符号进行发送的各个导频进行加扰。 导频可以被构造成单个OFDM符号和/或多个OFDM符号。 用于发送网络ID的单个符号结构与网络ID比特数无关，并且使频偏和多普勒效应最小化。 多符号结构允许以牺牲传输附加符号为代价采用更粗糙的定时精度。 几个实施例采用搜索功能来从发送的符号和选择功能中找到可能的网络ID候选，以从网络ID候选列表中找到最佳候选。

公开(公告)号：US08249116B2

公开(公告)日：2012-08-21

申请号：US12644856

申请日：2009-12-22

申请人： Bojan Vrcelj ,  Krishna K. Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

发明人： Bojan Vrcelj ,  Krishna K. Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

IPC分类号： H04J3/06 ,  H04J3/00 ,  H04B7/212

CPC分类号： H04L27/2662 ,  H04L25/0212 ,  H04L25/0216 ,  H04L27/2695

摘要： The embodiments provide mechanisms for synchronizing a receiver with OFDM pilots that are robust in the presence of channel fading conditions. In addition to using instantaneous channel estimate values to locate the first arriving path and last arriving path, the methods calculate time-domain averaged channel estimate values and use those averaged values to determine an average first arriving path and last arriving path. A combination of the instantaneous first arriving path and last arriving path and the average first arriving path and last arriving path may then be used to determine the delay spread and calculate a timing offset to be applied in timing synchronization. The various embodiments introduce improvements under channel fading conditions. Time-domain averaging may be embodied in a flexible DSP processor, or implemented in hardware and/or software. Using both instantaneous and time-averaged channel estimates greatly improves the robustness of time synchronization under channel fading conditions.

摘要翻译： 实施例提供了用于使接收机与在存在信道衰落条件的情况下鲁棒的OFDM导频同步的机制。 除了使用瞬时信道估计值来定位第一到达路径和最后到达路径之外，该方法还计算时域平均信道估计值，并使用这些平均值来确定平均第一到达路径和最后到达路径。 然后可以使用瞬时第一到达路径和最后到达路径以及平均第一到达路径和最后到达路径的组合来确定延迟扩展，并计算要在定时同步中应用的定时偏移。 各种实施例在信道衰落条件下引入改进。 时域平均可以体现在灵活的DSP处理器中，或者在硬件和/或软件中实现。 使用瞬时和时间平均信道估计大大提高了信道衰落条件下时间同步的鲁棒性。

公开(公告)号：US20060250937A1

公开(公告)日：2006-11-09

申请号：US11372930

申请日：2006-03-09

申请人： Michael Wang ,  Bojan Vrcelj ,  Krishna Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

发明人： Michael Wang ,  Bojan Vrcelj ,  Krishna Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

IPC分类号： H04J11/00

CPC分类号： H04L27/2613 ,  H04L5/0007 ,  H04L5/0048 ,  H04L25/023

摘要： Systems and methods are provided for the transmission of waveforms to aid channel estimation, timing synchronization, and AGC bootstrapping in a wireless network. The method includes inserting at least one TDM pilot symbol located at a transition between wide area and local area waveforms to facilitate decoding of the transmission block.

公开(公告)号：US20100246564A1

公开(公告)日：2010-09-30

申请号：US12644856

申请日：2009-12-22

申请人： Bojan Vrcelj ,  Krishna K. Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

发明人： Bojan Vrcelj ,  Krishna K. Mukkavilli ,  Raghuraman Krishnamoorthi ,  Ashok Mantravadi

IPC分类号： H04J3/06 ,  H04L27/28

CPC分类号： H04L27/2662 ,  H04L25/0212 ,  H04L25/0216 ,  H04L27/2695

摘要： The embodiments provide mechanisms for synchronizing a receiver with OFDM pilots that are robust in the presence of channel fading conditions. In addition to using instantaneous channel estimate values to locate the first arriving path and last arriving path, the methods calculate time-domain averaged channel estimate values and use those averaged values to determine an average first arriving path and last arriving path. A combination of the instantaneous first arriving path and last arriving path and the average first arriving path and last arriving path may then be used to determine the delay spread and calculate a timing offset to be applied in timing synchronization. The various embodiments introduce improvements under channel fading conditions. Time-domain averaging may be embodied in a flexible DSP processor, or implemented in hardware and/or software. Using both instantaneous and time-averaged channel estimates greatly improves the robustness of time synchronization under channel fading conditions.

摘要翻译： 实施例提供了用于使接收机与存在信道衰落条件时鲁棒的OFDM导频同步的机制。 除了使用瞬时信道估计值来定位第一到达路径和最后到达路径之外，该方法还计算时域平均信道估计值，并使用这些平均值来确定平均第一到达路径和最后到达路径。 然后可以使用瞬时第一到达路径和最后到达路径以及平均第一到达路径和最后到达路径的组合来确定延迟扩展，并计算要在定时同步中应用的定时偏移。 各种实施例在信道衰落条件下引入改进。 时域平均可以体现在灵活的DSP处理器中，或者在硬件和/或软件中实现。 使用瞬时和时间平均信道估计大大提高了信道衰落条件下时间同步的鲁棒性。