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1. 发明专利

JP2000307481A RECEIVER FOR DISCRETE MULTITONE MODULATED SIGNAL HAVING WINDOW FUNCTION 失效
公开(公告)号：JP2000307481A
公开(公告)日：2000-11-02
申请号：JP2000034721
申请日：2000-02-14
申请人： NEC USA INC
发明人： KAPOOR SAMIR , NEDIC SLOBODAN
IPC分类号： H04J11/00 , H04B3/04 , H04L1/00 , H04L27/26
摘要： PROBLEM TO BE SOLVED: To suppress color noise by providing a 1st stage with a frequency response to apply discrete Fourier transform to an input signal and a frequency region equalizer having an input coupled with its output to the title receiver thereby enhancing the performance even in the presence of noise. SOLUTION: An input signal is fed to 1st and 2nd data paths 100, 200. An FFT 120 applies discrete Fourier transform an input signal in the 1st data path 100 to generate a 1st transform signal and an FEQ 120 equalizes the 1st transform signal to supply a frequency region equalization signal in a frequency region. A window function is applied to the input signal in the 2nd data path 200 to supply a pulse shaping signal and to suppress a side lobe of the 1st transform signal. An output from the 1st data path 100 or the 2nd data path 200 is selected based on a test that is defined in advance and a selected output denoting a demodulated digital bit stream is supplied.

2. 发明专利

JP2000244371A DMT COMMUNICATION SYSTEM, AND METHOD FOR DECIDING T- COEFFICIENT OF TIME DOMAIN EQUALIZER 失效
公开(公告)号：JP2000244371A
公开(公告)日：2000-09-08
申请号：JP2000016187
申请日：2000-01-25
申请人： NEC USA INC
发明人： KAPOOR SAMIR
IPC分类号： H04J11/00 , H04B3/06 , H04L25/03 , H04L27/26
摘要： PROBLEM TO BE SOLVED: To reduce the spectrum coloring of an additional noise due to a time- domain equalizer by substantially concentrating the energy of a valid impulse response at the time of combining at least a communication channel with the time-domain equalizer in a second area, and controlling the fluctuation of the frequency spectrum of an additional noise signal existing in the output of the time-domain equalizer. SOLUTION: The T-coefficient of the time-domain equalizer is decided so that the energy concentration level of valid impulse response heff(n) can be maximized in a prescribed sample band (having first length) when a transmission channel 20 is connected to the time-domain equalizer 33, and the energy concentration level of an impulse response h(n) can be maximized in another sample band (having second length) when only the transmission channel 20 is present. In this case, the first length is set so as to be longer than the second length. Those T-coefficients are decided so that a further flat frequency spectrum can be indicated by the noise characteristics of the output of the time-domain equalizer 33.

3. 发明专利

JP2001148643A EQUALIZATION PROCESSING ADAPTIVE FOR EACH BIN IN WINDOW CONTROL DISCRETE MULTI-TONE TYPE MODEM RECEIVER 失效
公开(公告)号：JP2001148643A
公开(公告)日：2001-05-29
申请号：JP2000259979
申请日：2000-08-29
申请人： NEC USA INC
发明人： NEDIC SLOBODAN , POPOVIC NENAD
IPC分类号： H04J11/00 , H04B3/10 , H04L25/03
摘要： PROBLEM TO BE SOLVED: To solve the problem that the conventional technique of calculating the coefficient of a domain equalizer does not cope with the change of the time and position of a narrow band interference source. SOLUTION: A receiver provided with plural delay circuits 102 for delaying discrete multi-tone signals, plural window control circuits 104 for receiving delay signals 102, a finite section fast Fourier transformation circuit 106 for outputting complex number signals for expressing plural bins corresponding to the sub channels of the discrete multi-tone signals for the output of the window control circuits 104, plural multiplication circuits 109 for outputting the products of a complex number factor 108 for correcting a phase shift by the plural delay circuits and the respective complex number signals, an equalization circuit 110 for receiving the output of the multiplication circuits 109 and outputting signals encoded to partial response signals and a partial response signal decoder 112 for receiving partial response signal encoded signals and outputting output codes for indicating input codes is introduced.

4. 发明专利

JP2000244587A METHOD AND DEVICE FOR ASSIGNING DISCRETE PLURAL TONE COMMUNICATION BIT 失效
公开(公告)号：JP2000244587A
公开(公告)日：2000-09-08
申请号：JP2000018690
申请日：2000-01-27
申请人： NEC USA INC
发明人： KAPOOR SAMIR , CHOUDHARY PRASHANT
IPC分类号： H04L27/00 , H04J11/00 , H04L5/14 , H04L27/26
摘要： PROBLEM TO BE SOLVED: To assign a bit to a group of transmission sub-channels by storing at least one bit-signal-to-noise ratio table in a memory in order to decide a bit assigning value and a gain magnification concerning each element of a group of transmission sub-channels based on this table. SOLUTION: At least, one bit-signal-to-noise ratio table is stored in the memory to decide the bit assigning value and the gain magnification concerning each element of the group of transmission sub-channels based on this stored at-least one bit-signal-to-noise ratio table. Bits are assigned to the group of transmission sub-channels in a communication system in this way. In this case, the stored table is formed of a group of minimum signal-to-noise ratio values and a group of bit values respectively corresponding to the group, this minimum signal-to-noise ratio value is decided based on a maximum allowable gain; further, a signal-to-noise ratio value respectively corresponds to the group of bit values.

5. 发明专利

DE69918945T2 未知
公开(公告)号：DE69918945T2
公开(公告)日：2004-12-16
申请号：DE69918945
申请日：1999-11-17
申请人： NEC USA INC
发明人： KAPOOR SAMIR , NEDIC SLOBODAN
IPC分类号： H04J11/00 , H04B3/04 , H04L1/00 , H04L27/26
摘要： A receiver structure for improving the performance of conventional Discrete Multitone Modulation (DMT) based Asymmetric Digital Subscriber Line (ADSL) modems, particularly in the presence of noise and/or interference. A conventional demodulator having an FFT followed by a single-tap-per-bin frequency-domain equalizer is augmented by an additional data-path utilizing windowing or pulse shaping. Windowing is done independently for each symbol over the orthogonality interval and can be carried out efficiently in the time domain or frequency domain. A decision feedback equalizer is used at the output of the windowed data-path to cancel inter-bin-interference created by windowing. Windowing is most effective against narrowband interference (NBI) and other conditions which lead to diminished orthogonality between bins such as inadequate channel shortening in ADSL, symbol timing offset and jitter. Limited performance gains may also be achieved in the presence of crosscalk with strong spectral coloration. The overall technique is potentially also applicable to other DMT based modems such as VDSL and wireless OFDM. The receiver does not require changes to be made to the transmitter.

6. 发明专利

DE69918945D1 未知
公开(公告)号：DE69918945D1
公开(公告)日：2004-09-02
申请号：DE69918945
申请日：1999-11-17
申请人： NEC USA INC
发明人： KAPOOR SAMIR , NEDIC SLOBODAN
IPC分类号： H04J11/00 , H04B3/04 , H04L1/00 , H04L27/26
摘要： A receiver structure for improving the performance of conventional Discrete Multitone Modulation (DMT) based Asymmetric Digital Subscriber Line (ADSL) modems, particularly in the presence of noise and/or interference. A conventional demodulator having an FFT followed by a single-tap-per-bin frequency-domain equalizer is augmented by an additional data-path utilizing windowing or pulse shaping. Windowing is done independently for each symbol over the orthogonality interval and can be carried out efficiently in the time domain or frequency domain. A decision feedback equalizer is used at the output of the windowed data-path to cancel inter-bin-interference created by windowing. Windowing is most effective against narrowband interference (NBI) and other conditions which lead to diminished orthogonality between bins such as inadequate channel shortening in ADSL, symbol timing offset and jitter. Limited performance gains may also be achieved in the presence of crosscalk with strong spectral coloration. The overall technique is potentially also applicable to other DMT based modems such as VDSL and wireless OFDM. The receiver does not require changes to be made to the transmitter.

7. 发明专利

DE69729295D1 未知
公开(公告)号：DE69729295D1
公开(公告)日：2004-07-01
申请号：DE69729295
申请日：1997-08-20
申请人： NEC USA INC
发明人： KUEHNEL DR , VARLESE CHRISTOPHER
IPC分类号： H04L49/111 , H04W36/08 , H04W76/04 , H04Q7/24 , H04L12/56
摘要： The ATM switching architecture for a wireless telecommunications network comprises two separate units (10, 11) with different functionality. The first unit (10) performs the mobility control, wherein a virtual path which contains all virtual channels of a mobile terminal (4.1) is switched from a first port (12.1) that is associated with a first access point (3.1) to a second port (12.3) that is connected to a first port (13.1) of the second unit (11). The second unit (11) performs the switching operation, wherein the virtual channels of the mobile terminal (4.1) are distributed from the first port (13.1) of the second unit (11) to different destination ports in said unit (11). The two units may be dedicated hardware components. According to another embodiment, one single hardware component is functionally separated into two separate units which are connected by a loopback.

8. 发明公开

EP1081907A1 Windowing and frequency-domain equalisation in multicarrier receivers 审中-公开
标题翻译： Fensterung und Entzerrung im Frequenzbereich inMehrträgerempfängern
公开(公告)号：EP1081907A1
公开(公告)日：2001-03-07
申请号：EP00302440.3
申请日：2000-03-24
申请人： NEC USA, Inc.
发明人： Nedic, Slobodan , Popovic, Nenad
IPC分类号： H04L27/26 , H04L25/03
CPC分类号： H04L25/03159 , H04L2025/03414 , H04L2025/03522
摘要： An apparatus for receiving a discrete multi-tone (DMT) signal representative of a series of input symbols and including a plurality of orthogonal sinusoidal subchannels of finite length for each input symbol, the apparatus including a plurality of delay circuits (102), each operable to receive the DMT signal and produce a delayed DMT signal; a plurality of windowing circuits (104), each operable to receive a respective one of the delayed DMT signals and produce a windowed DMT signal; at least one finite duration fast Fourier transform (FFT) circuit (106), operable to receive the windowed DMT signals and produce respective complex signals representing a plurality of bins corresponding to the subchannels of the DMT signal; a plurality of multiplier circuits (108) each operable to produce a product of (i) a complex factor for compensating for a respective phase shift introduced by a corresponding one of the delay circuits, and (ii) a respective one of the complex signals; an equalizer circuit (110) operable to receive the products from the plurality of multiplier circuits and produce a partial response signaling (PRS) coded signal; and a PRS decoder (112) operable to receive the PRS coded signal and produce output symbols representative of the input symbols.
摘要翻译：一种用于接收表示一系列输入符号并包括每个输入符号的有限长度的多个正交正弦子信道的离散多音（DMT）信号的装置，所述装置包括多个延迟电路（102），每个可延迟电路以接收DMT信号并产生延迟的DMT信号; 多个开窗电路（104），每个开窗电路（104）可操作以接收延迟的DMT信号中的相应一个并产生加窗的DMT信号; 至少一个有限持续时间的快速傅立叶变换（FFT）电路（106），可操作以接收加窗的DMT信号并产生表示对应于DMT信号的子信道的多个存储区的相应复数信号; 多个乘法器电路（108），每个乘法器电路（108）可操作以产生（i）用于补偿由对应的一个延迟电路引入的相应相移的复数因子和（ii）复信号中的相应一个的乘积; 均衡器电路（110），可操作以从多个乘法电路接收产品并产生部分响应信令（PRS）编码信号; 以及PRS解码器（112），其可操作以接收PRS编码信号并产生表示输入符号的输出符号。

9. 发明授权

EP0898434B1 ATM switching architecture for a wireless telecommunications network 失效
标题翻译：对于无线电信网络ATM交换架构
公开(公告)号：EP0898434B1
公开(公告)日：2004-05-26
申请号：EP97810584.9
申请日：1997-08-20
申请人： NEC USA, Inc.
发明人： Kühnel, Thomas, Dr. , Varlese, Christopher
IPC分类号： H04Q7/24 , H04L12/56
CPC分类号： H04L49/254 , H04L49/105 , H04L49/20 , H04L49/30 , H04L49/3063 , H04L49/552 , H04L2012/5607 , H04L2012/5619 , H04W36/00

10. 发明公开

EP1043875A3 Receiver for discrete multitone modulated signals having window function 有权
标题翻译：接收器用于与窗函数的多载波调制信号
公开(公告)号：EP1043875A3
公开(公告)日：2002-04-03
申请号：EP99122054.2
申请日：1999-11-17
申请人： NEC USA, Inc.
发明人： Kapoor, Samir , Nedic, Slobodan
IPC分类号： H04L27/26 , H04L1/00
CPC分类号： H04L27/2647
摘要： A receiver structure for improving the performance of conventional Discrete Multitone Modulation (DMT) based Asymmetric Digital Subscriber Line (ADSL) modems, particularly in the presence of noise and/or interference. A conventional demodulator having an FFT followed by a single-tap-per-bin frequency-domain equalizer is augmented by an additional data-path utilizing windowing or pulse shaping. Windowing is done independently for each symbol over the orthogonality interval and can be carried out efficiently in the time domain or frequency domain. A decision feedback equalizer is used at the output of the windowed data-path to cancel inter-bin-interference created by windowing. Windowing is most effective against narrowband interference (NBI) and other conditions which lead to diminished orthogonality between bins such as inadequate channel shortening in ADSL, symbol timing offset and jitter. Limited performance gains may also be achieved in the presence of crosscalk with strong spectral coloration. The overall technique is potentially also applicable to other DMT based modems such as VDSL and wireless OFDM. The receiver does not require changes to be made to the transmitter.

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