公开(公告)号：US5151926A

公开(公告)日：1992-09-29

申请号：US703516

申请日：1991-05-21

申请人： Sandeep Chennakeshu ,  Gary J. Saulnier

发明人： Sandeep Chennakeshu ,  Gary J. Saulnier

IPC分类号： H03D3/00 ,  H04L7/04 ,  H04L27/233

CPC分类号： H04L27/2338 ,  H03D3/007 ,  H04L7/042 ,  H03D2200/0035 ,  H03D2200/005 ,  H03D2200/0062 ,  H03D3/006

摘要： A digital radio receiver for synchronization of radiowave transmissions for digital and analog FM signals in TDMA systems such as cellular telephones uses a Sine/Cosine detector that minimizes the bit error rate. The detector employs an A/D converter, a sorter circuit that produces a predetermined number of samples to be used in the decoding based upon a sample timing adjustment, and a sample and phase adjustment circuit that selects samples based on a sample timing adjustment and adds a carrier phase adjustment to the samples. A cosine detector and a sine detector each decode samples into signals that are measured by a cosine level check circuit and a sine level check circit respectively. A decision logic circuit produces a pair of bits from the levels detected by the cosine level check circuit and the sine level check circuit as the decoded transmitted information. Adjustments to the sample timing and carrier phase are performed by an adjustment circuit that monitors the phase error between the decoded information and a predetermined information set in the preamble of each TDMA slot. The adjustment circuit sends the sample timing and carrier phase adjustments to the SPA circuit which selects different samples to be decoded and uses the carrier phase adjustment to recalculate different coefficients from these samples and pass the signal through the remainder of the circuit and eventually to the adjustment circuit. The signal is iteratively cycled through this loop until the best sample timing and carrier phase adjustments are reached.

摘要翻译： 用于在诸如蜂窝电话的TDMA系统中用于数字和模拟FM信号的无线电波传输的同步的数字无线电接收机使用最小化误码率的正弦/余弦检测器。 检测器采用A / D转换器，分选器电路，其基于采样定时调整产生将用于解码中的预定数量的采样，以及采样和相位调整电路，其基于采样定时调整来选择采样，并且添加 样品的载体相位调整。 余弦检测器和正弦检测器各自将样本解码为由余弦电平检查电路和正弦电平检查电路测量的信号。 决定逻辑电路从由余弦电平检查电路和正弦电平检查电路检测的电平产生一对位作为解码的发送信息。 对采样定时和载波相位的调整由监视解码信息与每个TDMA时隙的前导码中设置的预定信息之间的相位误差的调整电路来执行。 调整电路将采样定时和载波相位调整发送到SPA电路，该电路选择不同的待解码样本，并使用载波相位调整从这些采样中重新计算不同的系数，并将信号通过电路的其余部分并最终调整 电路。 信号通过该循环迭代循环，直到达到最佳采样定时和载波相位调整。

公开(公告)号：US07099410B1

公开(公告)日：2006-08-29

申请号：US09237356

申请日：1999-01-26

申请人： Sandeep Chennakeshu ,  Kambiz Zangi ,  Gregory E. Bottomley

发明人： Sandeep Chennakeshu ,  Kambiz Zangi ,  Gregory E. Bottomley

IPC分类号： H04L27/06

CPC分类号： H04L25/03197 ,  H04L25/03299

摘要： The present invention involves demodulation of radio signals modulated with M-ary modulation in the presence of intersymbol interference distortion. The invention presents a method for reducing the number of multiplications needed to implement a maximum-likelihood-sequence-estimation (MLSE) equalizer for signals modulated with M-ary modulation. In exemplary embodiments of the present invention, the number of multiplications is reduced by pre-computing certain values needed for the determination of the branch metric and storing these pre-computed values in a product table. When a branch metric computation is to be made, whether it is an Euclidean branch metric computation or an Ungerboeck branch metric computation, certain multiplication operations are replaced by simple table look-up operations. As a result, the power efficiency and speed of the system are increased. Any receiver that demodulates signals that are modulated with M-ary modulation can be implemented using the present invention. The resulting demodulator will have a lower complexity than existing demodulators.

摘要翻译： 本发明涉及在存在符号间干扰失真的情况下解调用M进制调制的无线电信号。 本发明提出了一种用于减少对用M-ary调制调制的信号实现最大似然序列估计（MLSE）均衡器所需的乘法次数的方法。 在本发明的示例性实施例中，通过预先计算确定分支度量所需的某些值并将这些预先计算的值存储在产品表中来减少乘法次数。 当进行分支度量计算时，无论是欧几里德分支度量计算还是Ungerboeck分支度量计算，某些乘法运算都被简单的表查找操作所取代。 结果，系统的功率效率和速度增加。 可以使用本发明来实现解调通过M进制调制调制的信号的任何接收机。 所产生的解调器将具有比现有解调器更低的复杂度。

公开(公告)号：US06563861B1

公开(公告)日：2003-05-13

申请号：US09273480

申请日：1999-03-22

申请人： Leonid Krasny ,  Sandeep Chennakeshu ,  David Koilpillai

发明人： Leonid Krasny ,  Sandeep Chennakeshu ,  David Koilpillai

IPC分类号： H04B1500

CPC分类号： H04B7/01 ,  H04B1/707 ,  H04B1/709 ,  H04B2201/70701

摘要： A receiving apparatus Doppler spread estimator includes a receiver receiving signals over a transmission channel that varies over time due to fading and converting the signals to digital samples for processing. A stationarizer operatively associated with the receiver stationarizes the digital samples. An estimator is operatively associated with the stationarizer for estimating spectral density of the stationarized digital samples. The correlator is operatively coupled to the estimator for correlating the spectral density estimates with functions corresponding to hypotheses of plural Doppler spread values to select one of the Doppler spread values as an estimate of actual Doppler spread.

摘要翻译： 接收装置多普勒扩展估计器包括接收器，其通过传输信道接收由于衰落而随时间变化的信号，并将信号转换为数字样本进行处理。 与接收器可操作地相关联的台式计算机将数字样本平均化。 估计器可操作地与台式计算机相关联，用于估计平台化数字样本的频谱密度。 相关器可操作地耦合到估计器，用于将频谱密度估计与对应于多个多普勒扩展值的假设的函数相关联，以选择多普勒扩展值中的一个作为实际多普勒扩展的估计。

公开(公告)号：US06532374B1

公开(公告)日：2003-03-11

申请号：US09595318

申请日：2000-06-16

申请人： Sandeep Chennakeshu ,  David Townsend ,  David R. Irvin ,  Randy Bright

发明人： Sandeep Chennakeshu ,  David Townsend ,  David R. Irvin ,  Randy Bright

IPC分类号： H04B106

CPC分类号： H04B1/3822 ,  B60R11/0241 ,  H04M1/6091 ,  H04M2250/02

摘要： A radiotelephone includes a base unit mounted within the vehicle having a wide area transceiver for communicating with a station outside the vehicle, a control unit disposed in the vehicle remotely from the base unit, and a local area network for establishing a communication link between the base unit and the control unit. The local area network is adapted to transmit control and data signals between the base unit and the control unit. The control unit includes a keypad for entering commands and data that are transmitted to the base unit via the local area network, and a display for displaying information to the user. The control unit may also include a speaker and microphone. Alternatively, the speaker and microphone may be contained in a remote audio unit that is linked to the base unit via the local area network. The control unit may, for example, be incorporated into the steering wheel of a vehicle while the base unit is concealed in the trunk or under the seat of the vehicle.

摘要翻译： 无线电话机包括安装在车辆内的基座单元，其具有用于与车辆外部的站通信的广域收发器，远离基本单元设置在车辆中的控制单元和用于在基座之间建立通信链路的局域网 单元和控制单元。 局域网适于在基本单元和控制单元之间传输控制和数据信号。 控制单元包括用于输入通过局域网发送到基本单元的命令和数据的键盘，以及用于向用户显示信息的显示器。 控制单元还可以包括扬声器和麦克风。 或者，扬声器和麦克风可以包含在经由局域网链接到基本单元的远程音频单元中。 例如，控制单元可以被结合到车辆的方向盘中，同时基座单元被隐藏在车厢的后备箱或座椅下方。

公开(公告)号：US06414945B1

公开(公告)日：2002-07-02

申请号：US09166793

申请日：1998-10-06

申请人： Sandeep Chennakeshu ,  Nils Rydbeck ,  Amer A. Hassan ,  Paul W. Dent

发明人： Sandeep Chennakeshu ,  Nils Rydbeck ,  Amer A. Hassan ,  Paul W. Dent

IPC分类号： H04B7212

CPC分类号： H04W68/00 ,  H04B7/18567 ,  H04L1/08 ,  H04W4/14 ,  H04W28/06 ,  H04W52/06 ,  H04W52/48

摘要： A method and system for transmitting short data messages in a control station-based TDMA radiocommunication system. Selected TDMA frames are assigned as message frames, and one or more data slots from each message frame are assigned to transmitter/receivers. Data messages can be encoded and transmitted multiple times, at an increased power level, from a control station to a transmitter/receiver over the appropriate data slots in each message frame. The selected TDMA frames are preferably slow associated control channel frames. Also, short alphanumeric messages can be transmitted over the broadcast control channel of a digital radiocommunication link, or another communication channel consisting of one or more slots from successive frames in a TDMA communication link. An increase in transmission power is used in combination with repetition to increase effective signal margin without complications in the mobile unit design, significant delay, or co-channel interference. Where a more significant increase in signal margin is desired, when a longer message is required, or for voice messages, the message may be stored and the mobile unit alerted of the message.

摘要翻译： 一种用于在基于控制站的TDMA无线电通信系统中发送短数据消息的方法和系统。 所选TDMA帧被分配为消息帧，并且来自每个消息帧的一个或多个数据时隙被分配给发射机/接收机。 在每个消息帧中的数据消息可以通过适当的数据时隙从控制站到发射机/接收机以增加的功率电平被多次编码和传输。 选择的TDMA帧优选地是慢关联的控制信道帧。 此外，可以通过数字无线电通信链路的广播控制信道或由TDMA通信链路中的连续帧的一个或多个时隙组成的另一个通信信道来传送短的字母数字消息。 传输功率的增加与重复结合使用以增加有效信号容限，而不会在移动单元设计，显着的延迟或同信道干扰中出现并发症。 在需要更大幅度地增加信号余量的情况下，当需要更长的消息或者对于语音消息时，可以存储消息并且移动单元提醒消息。

公开(公告)号：US06327317B1

公开(公告)日：2001-12-04

申请号：US09393881

申请日：1999-09-10

申请人： Sandeep Chennakeshu ,  Ravinder David Koilpillai

发明人： Sandeep Chennakeshu ,  Ravinder David Koilpillai

IPC分类号： H03D100

CPC分类号： H04L1/0057 ,  H04L25/03019 ,  H04L25/03178 ,  H04L25/03184

摘要： Combined equalization and decoding of codewords in a coded modulation symbol sequence that has been received from a channel is accomplished in a number of ways. In an intersymbol interference (ISI) cancellation technique, channel impulse response (CIR) estimates corresponding to each received symbol of the coded modulation symbol sequence are determined. Codeword k of the received symbol sequence is then decoded using a maximum likelihood decoding trellis with a path metric that depends upon the CIR estimates and that includes at least one term representing intersymbol interference resulting from symbols of previously decoded codewords. The decoding step is repeated until all of the codewords of the received coded modulation symbol sequence have been decoded. In a maximum likelihood sequence estimation (MLSE)-based technique, an MLSE trellis is advanced from one stage to a next stage by updating a path metric having dependence on the CIR estimates and upon symbols of a codeword corresponding to a state in a previous trellis stage. The trellis-advancing step is repeated until all stages of the MLSE trellis are completed. Then, the codewords are decoded by using a traceback along the best path in the completed MLSE trellis. In another embodiment, a hybrid MLSE-ISI technique utilizes a path metric that depends upon the CIR estimates and upon symbols of a codeword corresponding to a state in a previous trellis stage. The path metric further includes at least one term that represents intersymbol interference resulting from symbols of previously decoded codewords.

摘要翻译： 已经以多种方式实现了从信道接收到的编码调制符号序列中码字的组合均衡和解码。 在符号间干扰（ISI）消除技术中，确定与编码调制符号序列的每个接收符号对应的信道脉冲响应（CIR）估计。 然后使用具有取决于CIR估计的路径度量的最大似然解码网格对接收到的符号序列的码字k进行解码，并且包括至少一个表示由先前解码的码字的符号产生的符号间干扰的项。 重复解码步骤，直到所接收的编码调制符号序列的所有码字已被解码。 在基于最大似然序列估计（MLSE）的技术中，通过更新具有对CIR估计的依赖性的路径度量以及对应于先前网格中的状态的码字的符号，MLSE网格从一个阶段进入下一个阶段 阶段。 重新进行网格推进步骤，直到MLSE网格的所有阶段完成。 然后，通过使用在完成的MLSE网格中的最佳路径的回溯来对码字进行解码。 在另一个实施例中，混合MLSE-ISI技术利用取决于CIR估计的路径度量，以及对应于先前网格级中的状态的码字的符号。 路径度量还包括至少一个术语，其表示由先前解码的码字的符号产生的符号间干扰。

公开(公告)号：US6134260A

公开(公告)日：2000-10-17

申请号：US991770

申请日：1997-12-16

申请人： Gregory E. Bottomley ,  Raymond L. Toy ,  Sandeep Chennakeshu ,  Karl J. Molnar

发明人： Gregory E. Bottomley ,  Raymond L. Toy ,  Sandeep Chennakeshu ,  Karl J. Molnar

IPC分类号： H04B1/7075 ,  H04B1/7085 ,  H04R15/00

CPC分类号： H04B1/7075 ,  H04B1/7085

摘要： Systems and methods for frequency acquisition and channel tracking in a direct sequence code division multiple access system are described. Frequency estimates are prepared and refined, which estimates are also used in the channel tracking process.

摘要翻译： 描述了直接序列码分多址系统中频率采集和信道跟踪的系统和方法。 频率估计被准备和改进，这些估计也用于信道跟踪过程。

公开(公告)号：US5691980A

公开(公告)日：1997-11-25

申请号：US484750

申请日：1995-06-07

申请人： Kenneth Brakeley Welles, II ,  Jerome Johnson Tiemann ,  Sandeep Chennakeshu ,  Harold Woodruff Tomlinson, Jr.

发明人： Kenneth Brakeley Welles, II ,  Jerome Johnson Tiemann ,  Sandeep Chennakeshu ,  Harold Woodruff Tomlinson, Jr.

IPC分类号： G01C21/00 ,  B61L25/02 ,  G01S5/00 ,  G01S19/03 ,  G01S19/21 ,  G07C5/00 ,  G08B25/04 ,  G08G1/127 ,  H04B7/212 ,  H04L12/28 ,  H04B7/185

CPC分类号： H04W84/20 ,  B61L25/021 ,  B61L25/025 ,  G01S5/0027 ,  G08G1/127 ,  B61L2205/04 ,  G01S2205/002 ,  Y02B60/50

摘要： A mobile local area network (LAN) of tracked assets utilizing minimal power and bandwidth allows a large number of assets to be tracked in a practical manner. The mobile LAN is established between a plurality of tracking units in close proximity. Assets are approximately located according to their connection in the mobile LAN where the exact location of at least one of the network nodes is known. Each tracked asset has capability to independently determine and report its position to a central station, and each asset also has capability to communicate locally with other cooperative assets via the LAN. The LAN is dynamically reconfigurable so that as other cooperative assets come into proximity, they can join the network, and as others move away, they can leave the network. Within the network, a protocol is followed which assigns one of the assets to be the "master" and all others to be "slaves". The master asset takes responsibility for determining its own exact geographical position via LORAN, OMEGA, Global Positioning System (GPS) or other navigational aid. When connected in a LAN, slave assets report their ID to the master asset and do not determine their own locations in order to conserve power. The master reports its location and ID, as well as the IDs of the other assets in the LAN, to the central station. Uncertainty in the location of a slave asset is limited by the known possible geographical extent of the LAN which is known a priori.

摘要翻译： 使用最小功率和带宽的跟踪资产的移动局域网（LAN）允许以实际的方式跟踪大量资产。 在紧邻的多个跟踪单元之间建立移动LAN。 资产大致上根据它们在移动LAN中的连接而定位，其中至少一个网络节点的确切位置是已知的。 每个跟踪资产都有能力独立地确定并向中心站报告其位置，每个资产还具有通过局域网与其他合作资产进行本地通信的能力。 LAN可动态重新配置，以便随着其他合作资产的接近，他们可以加入网络，而随着其他人的移动，他们可以离开网络。 在网络中，遵循一个协议，将一个资产分配为“主”，所有其他资源都将作为“从属”。 主资产负责通过LORAN，OMEGA，全球定位系统（GPS）或其他导航辅助来确定其自己的确切地理位置。 当连接到局域网时，从属资产将其ID标识为主资产，并且不确定自己的位置以节省电力。 主人将其位置和ID以及LAN中其他资产的ID报告给中心站。 从属资产位置的不确定性受到先验已知的LAN已知可能的地理范围的限制。

公开(公告)号：US5371471A

公开(公告)日：1994-12-06

申请号：US143011

申请日：1993-10-29

申请人： Sandeep Chennakeshu ,  Ravinder D. Koilpillai ,  Raymond L. Toy

发明人： Sandeep Chennakeshu ,  Ravinder D. Koilpillai ,  Raymond L. Toy

IPC分类号： H04L25/02 ,  H04L25/03 ,  H04L27/12

CPC分类号： H04L25/0236 ,  H04L2025/03401 ,  H04L25/03178

摘要： A low complexity adaptive equalizer for use in U.S. digital cellular radios demodulates .pi./4-shifted differentially encoded quadrature phase shift keyed (DQPSK) encoding in the presence of intersymbol interference (ISI) with reduced decoding complexity by employing an estimated received constellation which takes into account channel changes over time and ISI. The decoding complexity is reduced by tracking a reduced number of estimated reference symbol constellation points and taking advantage of the geometry to estimate the remaining symbol constellation points. Reference symbol constellation points are updated directly to compensate for changes in the channel, instead of determining channel impulse response (CIR) coefficients, and convolving the CIR coefficients with received symbols to determine new reference symbol constellation points.

摘要翻译： 用于美国数字蜂窝无线电的低复杂度自适应均衡器在存在码间干扰（ISI）的情况下，通过采用估计的接收星座来解调具有降低的解码复杂度的π/ 4位差分编码正交相移键控（DQPSK）编码 帐户频道随时间变化和ISI。 通过跟踪估计的参考符号星座点的数量减少并利用几何来估计剩余的符号星座点来减少解码复杂度。 参考符号星座点被直接更新以补偿信道中的变化，而不是确定信道脉冲响应（CIR）系数，并且将CIR系数与接收的符号进行卷积以确定新的参考符号星座点。

公开(公告)号：US5349589A

公开(公告)日：1994-09-20

申请号：US724280

申请日：1991-07-01

申请人： Sandeep Chennakeshu ,  Raymond L. Toy

发明人： Sandeep Chennakeshu ,  Raymond L. Toy

IPC分类号： H03M13/35 ,  H03M13/41 ,  H04L1/00 ,  G06F11/10

CPC分类号： H04L1/0065 ,  H03M13/35 ,  H03M13/41 ,  H03M13/4115 ,  H03M13/4123 ,  H03M13/413 ,  H03M13/6502 ,  H04L1/0054 ,  H04L1/007

摘要： A method and apparatus for digital radio communication employs separation of a frame of data to be transmitted into key bits, critical bits and unprotected bits. The key bits are processed to provide parity bits. The parity bits, and key bits are convolutionally encoded using a tail-biting scheme and merged with unprotected bits, and then transmitted. At the receiver, the decoder splits the received data into convolutionally encoded bits and unprotected bits, and trellis decodes the convolutionally encoded bits into a number of possible paths through a trellis using a generalized Viterbi algorithm. The tail-biting scheme reduces the number of bits that must be transmitted. Paths having errors in the key bits are rejected, and the path having the best metric without key bit errors is used in decoding the transmitted information. In the event that there is no such path, a previously selected path is substituted and decoded.

摘要翻译： 一种用于数字无线电通信的方法和装置通过将要发送的数据帧分离成密钥位，关键位和未受保护位。 处理关键位以提供奇偶校验位。 奇偶校验位和密钥位使用尾巴方案进行卷积编码，并与未受保护的位合并，然后发送。 在接收机处，解码器将接收到的数据分解成卷积编码比特和无保护比特，并且使用广义维特比算法将卷积编码的比特格网解码成通过网格的多个可能路径。 尾巴方案减少了必须传输的位数。 在密钥比特中出现错误的路径被拒绝，并且在解码所发送的信息中使用具有没有密钥比特错误的最佳度量的路径。 在没有这样的路径的情况下，先前选择的路径被替换和解码。