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公开(公告)号：US5905742A
公开(公告)日：1999-05-18
申请号：US579349
申请日：1995-12-27
CPC分类号： H04L1/0071 , H03M13/41 , H03M13/6502 , H04L1/0009 , H04L25/03216
摘要： A low complexity, high performance trellis decoder adapts the complexity of the trellis decoding process based on a current condition of the communications system. A trellis structure of nodes and branches is developed to decode the sequence of symbols received over a communications channel. Each set of nodes in the trellis represents the possible values of a received symbol at one time instant. Each branch defines a specific transition between nodes at different time instants, and each branch has an associated branch metric or weight. A linkage of branches between the nodes and the trellis defines a path through the trellis that represents one possible symbol sequence, and an accumulated metric/weight is generated for each possible path through the trellis. A variable number M survivor paths through the trellis is determined based on their accumulated path metric/weights. The value of the variable M depends on the current condition of the communications system. Once the value of M is adapted to the current condition, the sequence of received symbols is decoded using M survivor paths through the trellis.
摘要翻译： 低复杂度的高性能网格解码器基于通信系统的当前状况来适应网格解码过程的复杂性。 开发节点和分支的网格结构来解码通过通信信道接收的符号序列。 网格中的每组节点在一个时刻表示接收到的符号的可能值。 每个分支定义不同时刻的节点之间的特定转换，并且每个分支具有关联的分支度量或权重。 节点和网格之间的分支的链接定义了通过网格的路径，其表示一个可能的符号序列，并且通过网格为每个可能的路径生成累积的度量/权重。 根据其累积的路径度量/权重来确定通过网格的可变数M个幸存者路径。 变量M的值取决于通信系统的当前状态。 一旦M的值适合于当前条件，则使用经过网格的M个幸存路径来解码接收符号的序列。
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公开(公告)号：US5285480A
公开(公告)日：1994-02-08
申请号：US753578
申请日：1991-09-03
CPC分类号： H04B7/2643 , H04L25/03038 , H04L25/03254 , H04L2025/03477 , H04L2025/03726 , H04L25/03229 , H04L25/03299
摘要： A TDMA RF received signal is demodulated by first being filtered with a fixed transversal filter having a characteristic selected for matching a fixed square root raised cosine pulse characteristic of the received signal. The filtered signal is then adaptively filtered for compensating for a time varying impulse response of the channel. The adaptive filtering is performed initially during a synchronizing portion (preamble) of the filtered signal in accordance with a fast recursive least squares algorithm. Subsequent filter adaptation to a data portion of the filtered signal is accomplished in accordance with a computationally less expensive normalized least mean square procedure. The adaptive filter repetitively applies a modified Viterbi algorithm to blocks of 2D symbols, such that D symbols are released for adapting the adaptive filter means during the data portion of the filtered signal and the signal. The released symbols are also employed for adapting elements required in computing a metric for the modified Viterbi algorithm and the reconstructed signal used to form an error signal that drives the adaptation algorithms.
摘要翻译： 首先用固定的横向滤波器对TDMA RF接收信号进行解调，该固定横向滤波器具有选择用于匹配接收信号的固定平方根升余弦脉冲特性的特性。 滤波后的信号然后自适应滤波，以补偿信道的时变脉冲响应。 根据快速递归最小二乘法算法，最初在滤波信号的同步部分（前导码）期间执行自适应滤波。 根据计算上较便宜的归一化最小均方程序，完成对滤波信号的数据部分的后续滤波器适配。 自适应滤波器重复地将修改的维特比算法应用于2D符号的块，使得在滤波信号和信号的数据部分期间释放D符号以适应自适应滤波器装置。 释放的符号也用于调整计算修改的维特比算法的度量所需要的元素，以及用于形成驱动适应算法的误差信号的重建信号。
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公开(公告)号：US5283811A
公开(公告)日：1994-02-01
申请号：US754105
申请日：1991-09-03
CPC分类号： H04L7/0062 , H03H21/003 , H04L25/03057 , H04L7/10
摘要： An adaptive Decision Feedback Equalizer (DFE) (40) for a digital cellular mobile radio channel demodulator (30) employs a Complex Fast-Kalman Adaptation algorithm (56) to track channel variations. Sensitivity to sample timing jitter is reduced by providing the DFE with fractionally spaced feed-forward taps (50'). Deficiencies inherent in using a reduced precision implementation are overcome by adding a dither signal to sets of operations in the algorithm, the dither signal comprising an appropriately selected Gaussian random variable. For small delay spreads of approximately one third of a symbol duration or less, a resulting degradation in Bit Error Rate is avoided by switching the DFE out of the circuit or by reducing the number of taps of the DFE. For delay spreads of less than 40 microseconds and greater than approximately 10 microseconds, a (2,3) fractionally spaced DFE provides an adequate compromise between complexity and performance.
摘要翻译： 用于数字蜂窝移动无线电信道解调器（30）的自适应判决反馈均衡器（DFE）（40）采用复合快速卡尔曼适配算法（56）来跟踪信道变化。 通过为DFE提供分数间隔的前馈抽头（50'）来减少对采样定时抖动的灵敏度。 通过将抖动信号添加到算法中的操作集合来克服使用简化精度实现中固有的缺陷，抖动信号包括适当选择的高斯随机变量。 对于大约三分之一符号持续时间或更短的小延迟扩展，通过将DFE切换到电路外或通过减少DFE的抽头数来避免产生的误码率的降低。 对于小于40微秒和大于10微秒的延迟扩展，（2,3）分数间隔的DFE在复杂性和性能之间提供了充分的折中。
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4.发明授权Trellis coding technique to improve adjacent channel interference protection ratio in land mobile radio systems 失效网格编码技术提高了陆地移动无线电系统中的相邻信道干扰保护比
公开(公告)号：US5311552A
公开(公告)日：1994-05-10
申请号：US898670
申请日：1992-06-15
CPC分类号： H04L27/186 , H03M13/25
摘要： An optimum communication system for communicating on adjacent frequency bands with minimal interference between adjacent channels comprises an encoder that is serially coupled to a mapper and two parallel processing branches, each processing branch having a transmit filter a digital-to-analog converter, a low pass filter and a modulator coupled in series. Both modulators are coupled to a summer, and an rf amplifier having a transmit antenna. The encoder is optimized by choosing a desired minimum Euclidean distance (DMED) between symbols, an encoder alphabet and a number of constellation points, permutating all possible encoder states and all possible input symbols to result in a plurality of encoder sets U, determining an in-band to adjacent band power ratio P.sub.ib /P.sub.ab for each code set is determined, discarding code sets U that having a minimum distance between symbol sets that do not exceed DMED, shifting by 90 degrees with respect to each other the phase of the signals passing through the modulators, and transmitting to a receiver the summation of the signals in each one of the parallel processing branches, whereby the encoder produces the code set of the remaining sets having the largest in-band to adjacent band power ratio P.sub.ib /P.sub.ab resulting in a transmitted signal having a spectrum that maximizes the ratio of in-band to adjacent band power for LMR systems. Maximizing the in-band to adjacent band power increases the ACIPR and also allows for increased data transmission rates.
摘要翻译： 用于在相邻频道之间以最小干扰在相邻频带上通信的最佳通信系统包括串行耦合到映射器和两个并行处理分支的编码器，每个处理分支具有发射滤波器，数模转换器，低通 滤波器和串联耦合的调制器。 两个调制器耦合到一个夏天，一个射频放大器具有发射天线。 编码器通过在符号，编码器字母表和多个星座点之间选择期望的最小欧几里德距离（DMED）来优化，排列所有可能的编码器状态和所有可能的输入符号，以产生多个编码器集合U， 确定每个代码集的带到相邻带功率比Pib / Pab，丢弃具有不超过DMED的符号集之间的最小距离的代码集合U，相对于彼此相对于信号通过的相位相移90度 通过调制器，并且向接收机发送每个并行处理分支中的信号的总和，由此编码器产生具有最大带内至相邻频带功率比Pib / Pab的剩余组的码集，导致 具有使LMR系统的带内相邻带功率的比率最大化的频谱的发射信号。 将带内最大化到相邻频带功率增加了ACIPR，并且还允许增加数据传输速率。
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5.发明授权Trellis coding technique to increase adjacent channel interference protection ratio in land mobile radio systems under peak power constraints 失效网格编码技术在峰值功率约束下增加陆地移动无线电系统中的相邻信道干扰保护比
公开(公告)号：US5311553A
公开(公告)日：1994-05-10
申请号：US975201
申请日：1992-06-15
CPC分类号： H03M13/256 , H03M13/00 , H03M13/25 , H04L27/186
摘要： An optimum communication system employs an encoder coupled to a mapper and two parallel branches, each branch having a transmit filter a digital-to-analog converter, a low pass filter and a modulator coupled in series. Both modulators are coupled to a summer which provides an rf signal to a transmit antenna. A second antenna is coupled to a first down converter, an IF filter, a second down converter, an analog-to-digital converter and a decoder. The encoder is optimized by choosing a desired minimum Euclidean distance between symbols multiplied by the average to peak transmit power ratio (MPDR), an encoder alphabet and a number of constellation points. All possible encoder states and all possible input symbols are permutated to result in a plurality of encoder sets. The minimum distance between coded symbols and a P.sub.ib /P.sub.ab power ratio for each code set is determined. The encoder is adapted to output an encoder set U having a largest P.sub.ib /P.sub.ab power ratio having a large adjacent channel interference protection ratio. In an alternative embodiment, a minimum P.sub.ib /P.sub.ab power ratio (MPR) is chosen. The encoder is adapted to output an encoder set U having the largest minimum distance between coded symbols multiplied by the average to peak transmitted power ratio, that also has a P.sub.ib /P.sub.ab ratio that exceeds MPR.
摘要翻译： 最佳通信系统采用耦合到映射器和两个并行分支的编码器，每个分支具有发射滤波器，数模转换器，低通滤波器和串联耦合的调制器。 两个调制器耦合到向发射天线提供射频信号的夏季。 第二天线耦合到第一下变换器，IF滤波器，第二下变频器，模数转换器和解码器。 通过选择符号乘以平均与峰值发射功率比（MPDR），编码器字母和星座点数之间的期望的最小欧几里德距离来优化编码器。 所有可能的编码器状态和所有可能的输入符号被排列以产生多个编码器组。 确定每个代码集的编码符号与Pib / Pab功率比之间的最小距离。 编码器适于输出具有大的相邻信道干扰保护比的具有最大Pib / Pab功率比的编码器组U。 在替代实施例中，选择最小Pib / Pab功率比（MPR）。 编码器适于输出编码符号之间具有最大最小距离乘以平均值与峰值发射功率比的编码器组U，其也具有超过MPR的Pib / Pab比。
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6.发明授权Order recursive lattice decision feedback equalization for digital cellular radio 失效为数字蜂窝无线电订单递归晶格决策反馈均衡
公开(公告)号：US5249205A
公开(公告)日：1993-09-28
申请号：US753579
申请日：1991-09-03
CPC分类号： H04L25/03057 , H03K5/159
摘要： A received time division multiple access (TDMA) signal having a time slot comprised of a plurality of symbols including at least one sequence of synchronizing symbols and a plurality of data symbols is demodulated by adaptively filtering the received signal to minimize inter-symbol interference due to an effect of channel signal propagation delay. The adaptive filtering step is performed by processing the received signal with a multi-stage lattice decision feedback equalizer having (M=N.sub.1 -N.sub.2) stages followed by (N.sub.2 -1) two-dimensional stages. A metric is next formed for each of the stages in accordance with a predetermined mathematical relationship between the output signals of each of two stages. A plurality of the formed metrics are next accumulated over a plurality of time slots. A number of stages are then recursively determined for the lattice decision feedback equalizer for use during the next time slot by comparing, to a threshold value, the difference between the values of two accumulated metrics.
摘要翻译： 通过对接收到的信号进行自适应滤波来解调具有由包括至少一个同步符号序列和多个数据符号的多个符号组成的时隙的接收到的时分多址（TDMA）信号，以最小化由于 通道信号传播延迟的影响。 通过用具有（M = N1-N2）级和（N2-1）二维级的多级格子判决反馈均衡器处理接收信号来执行自适应滤波步骤。 根据两级的每一级的输出信号之间的预定的数学关系，接下来针对每个级形成度量。 下面在多个时隙中累积多个形成的度量。 然后递归地确定多个阶段，以便在下一个时隙期间通过将两个累积度量的值之间的差值与阈值进行比较来使用。
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公开(公告)号：US4290502A
公开(公告)日：1981-09-22
申请号：US74150
申请日：1979-09-10
申请人： John B. Anderson
发明人： John B. Anderson
CPC分类号： A47C12/02
摘要： When folded the step stool is self standing and has a narrow width to permit the step stool to be stored in otherwise unusable spaces. When the legs are extended, a stable triangular support for two or more steps is provided. The vertical uprights of the device carry a handgrip positioned well above the level of the highest step to be useful when a person is on the highest step and during ascent and descent of the steps.
摘要翻译： 当折叠时，台凳是自立式的，并且具有窄的宽度，以允许将步凳存储在其他不可用的空间中。 当腿伸展时，提供了两个或更多个步骤的稳定的三角支架。 装置的垂直立柱携带一个手柄，其位置远远高于最高级别的水平，当人处于最高台阶时，以及在上升和下降步骤期间是有用的。
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