Oki Techno Centre (singapore) Pte Ltd

Wipro Techno Centre (singapore) Pte. Ltd.

Oki Techno Center (singapore) Pte Ltd.

Masayuki Tomisawa

Zhongjun Wang

Yanxin Yan

Lee Guek Yeo

Wenzhen Li

Chang Qing Xu

Yujing Ting

Theng Tee Yeo

Ju Yan Pan

Zhi Ping Li

Yu Jing Ting

Saigui Hu

Chunhua Yang

Qi Jun Xu

An apparatus for sampling clock recovery (SCO) and methods for estimating and compensating SCO are provided. The apparatus comprises a symbol timing adjustment module for shifting forward or backward symbol timing of the transmitted OFDM symbols; a discrete Fourier transform (DFT) processor for performing DFT to an output from the symbol timing adjustment module; a channel estimator for undertaking a channel frequency response estimation based on a channel estimation sequence; a SCO phase rotator for receiving and performing phase shift on the transmitted OFDM symbols of a frame header and a frame payload; an SCO estimation stage for undertaking an SCO estimation based on a pilot-subcarrier-related output of the SCO phase rotator and the CFR estimation; and an SCO compensation distributor for dividing the SCO estimation into integer and fractional portions and then distributing them into the symbol timing adjustment module and the SCO phase rotator, respectively.

Apparatus and methods for estimating and compensating sampling clock offset

A multi-stage CFR estimation method for multi-band OFDM-based UWB systems is provided. The method includes obtaining a CFR estimation &#x125;by performing LS estimation using a channel estimation sequence from a received OFDM-UWB frame; obtaining a CFR estimation &#x125;by applying a frequency-domain smoothing to the CFR estimation &#x125;with a first smoothing factor; obtaining a frame header which contains OFDM symbols transmitted with frequency-domain spreading on each OFDM symbol, and detecting signal signs based on a combination of two spread signals of the same OFDM symbol in the frame header with a decision directed mode and the CFR estimation &#x125;assisted; obtaining a CFR estimation &#x125;by using the signs and a finite-alphabet feature of the detected transmitted signals; obtaining a CFR estimation &#x125;by applying a frequency-domain smoothing to the CFR estimation &#x125;with a second smoothing factor; and obtaining a CFR estimation &#x125;by averaging the CFR estimations &#x125;and &#x125;.

CFR estimation method for multi-band OFDM-based UWB systems

Method and apparatus for receiving coded signals with the aid of CSI are provided. The method comprises: performing channel estimation to obtain a CFR estimation vector; computing a squared magnitude of the CFR estimation vector, and obtaining a normalization factor &#x3b1; by averaging the squared magnitudes of CFR estimations on all N subcarriers; finding a norm-shift operand m satisfying the condition that &#x3b1;=2is a power of 2 number closest to the normalization factor &#x3b1;; performing a CSI-aided one-tap channel equalization on an output signal vector from a DFT processor by using the norm-shift operand m; performing constellation demapping; and performing channel decoding. The method further comprises obtaining a weighting factor vector by right shifting m bits of the squared magnitude of the CFR estimation vector so that the constellation demapping can use the weighted decision boundary values in case that its input signal is sensitive to both amplitude and phase.

Method and apparatus for receiving coded signals with the aid of channel state information

A system for performing LS equalization on a signal in an OFDM system comprises a receiver stage for receiving a modulated signal, a demodulation stage for demodulating the received modulated signal to produce a demodulated signal, a channel estimation stage for processing the demodulated signal to provide an output signal corresponding to a channel frequency response and an equalization stage arranged to process the output signal from the channel estimation stage to produce a channel state information signal. The equalization stage is arranged to use the channel state information signal to operate on the demodulated signal from the demodulation stage to produce an equalized demodulated output signal. There is also disclosed a method for performing LS equalization on a signal in an OFDM system.

System and method for performing LS equalization on a signal in an OFDM system

A method for demapping dual carrier modulated COFDM signals comprises normalizing an estimated channel state information signal to obtain a normalized channel state information signal, determining a Y-domain weighting factor from the normalized channel state information signal, determining an X-domain weighting factor from the normalized channel state information signal, performing equalization on a received data OFDM signal to obtain an equalized data signal, weighting an equalized data signal using the Y-domain weighting factor and the X-domain weighting factor to generate a weighted input signal of a demapper and performing linear demapping of the weighted input signal in the demapper. There is also disclosed an apparatus for demapping dual carrier modulated COFDM signals and a receiver comprising such an apparatus.

Method, apparatus and receiver for demapping dual carrier modulated COFDM signals

A processor for performing a Fast Fourier Transform and/or an Inverse Fast Fourier Transform of a complex input signal comprises a first stage for passing the input signal to a second stage when a Fast Fourier Transform procedure is to be performed and for swapping the real and imaginary components of the complex input signal before passing the signal to the second stage if an Inverse Fast Fourier Transform procedure is to be performed. The second stage has first and second radix-4 butterfly elements. A third stage is arranged to switch between first and second operating modes, the second operating mode being for processing a complex conjugate symmetrical input signal. A fourth stage has a plurality of processing units, one or more of the processing units comprising a radix-2 pipelined Fast Fourier Transform processor. The first and second radix-4 butterfly elements are arranged to perform a butterfly operation on the complex input signal to generate and deliver one or more components of a processed signal to the fourth stage. The fourth stage is arranged to process the processed signal received from the first stage according to a Fast Fourier Transform processing procedure to produce an output signal. There is also disclosed a method for performing a Fast Fourier Transform and/or Inverse Fast Fourier Transform of a complex input signal.

Processor and method for performing a fast fourier transform and/or an inverse fast fourier transform of a complex input signal

An encoder system for encoding a signal according to any number of FEC and/or channel codes comprises a shift register, an array of MOD/XOR stages, and a generator matrix stage for controlling the connections between the shift register and the MOD/XOR stages and altering these connections according to a coding format selected by an encoder selection stage. There is also disclosed a decoder system for decoding a signal encoded according to a number of FEC and/or channel codes comprising a decoding stage, and a generator matrix stage for configuring the decoding stage to a decoding code format to be applied an incoming encoded signal. A decoder selection stage is coupled to the generator matrix stage and selects the decoding code format to be used in the decoding process. The decoder selection stage instructs the generator matrix stage to configure the decoding stage according to the selected decoding code format. There is also disclosed a method for encoding and decoding.

Encoder system, a decoder system, a coding/decoding apparatus, an encoding method and a decoding method

A method of estimating the reliability of decoded message bits in a digital communications system is proposed. Message and tail bits are coded and transmitted across a communications channel. The coded message and tail bits are then decoded and it is determined that the decoded message bits have no error when the decoded tail bits have at least one error.

Method of estimating reliability of decoded message bits

An automatic gain control system comprises a number of variable gain stages connected in series and a number of sensors, the input of each sensor being connected to a respective output of the variable gain stages. The input of an analogue-to-digital converter is connected to the output of one of the variable gain stages. The input of a control unit is connected to the outputs of the sensors and to the output of the analogue-to-digital converter. The input of a digital-to-analogue converter is connected to the output of the control unit, and the control inputs of each of the variable gain stages is connected to an output of the digital-to-analogue converter. The outputs of the digital-to-analogue converter are used to control the gains of the variable gain stages. Also disclosed is a method for automatically controlling gain in a receiver system.

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Singapore, Singapore

Masayuki Tomisawa