Abstract: Performing cell search in a wireless communications system includes receiving a preamble signal, match filtering the preamble signal with a pseudo noise sequence to form a filtered preamble signal of a plurality of filtered preamble signals, choosing a largest filtered preamble signal from the plurality of filtered preamble signals, and determining an estimated pseudo noise sequence index and an estimated integer part frequency offset according to the largest filtered preamble signal.

Abstract: A communication system comprises a predistorter for distorting an input signal according to at least one parameter to generate a distorted signal, an amplifier for amplifying the distorted signal according to an input-output characteristic to generate an output signal, and a frequency-domain adaptive calibration module for adaptively adjusting the parameter of the predistorter according to a frequency characteristic of the output signal. Because the calibration is performed in the frequency domain, there is no need to precisely estimate the group delay formed by the feedback path. The system complexity is therefore reduced without loss of performance.

Abstract: Performing cell search in a wireless communications system includes receiving a preamble signal, match filtering the preamble signal with a pseudo noise sequence to form a filtered preamble signal of a plurality of filtered preamble signals, choosing a largest filtered preamble signal from the plurality of filtered preamble signals, and determining an estimated pseudo noise sequence index and an estimated integer part frequency offset according to the largest filtered preamble signal.

Abstract: An encoder for use in information processing applications includes an input configured to provide information bits to be encoded and a feedforward convolutional outer code encoder configured to encode the information bits to generate encoded information bits including the information bits and parity bits. The encoder may also include at least one interleaver configured to interleave the encoded information bits to generate an outer codeword. Further, the encoder may include a rate-1 1/(1+D) accumulate code based inner code encoder configured to encode the outer codeword to generate one or more codewords corresponding to the information bits.

Abstract: A communication system comprises a predistorter for distorting an input signal according to at least one parameter to generate a distorted signal, an amplifier for amplifying the distorted signal according to an input-output characteristic to generate an output signal, and a frequency-domain adaptive calibration module for adaptively adjusting the parameter of the predistorter according to a frequency characteristic of the output signal. Because the calibration is performed in the frequency domain, there is no need to precisely estimate the group delay formed by the feedback path. The system complexity is therefore reduced without loss of performance.

Abstract: A system and method for transmitting data in multiple-branch transmitter-diversity OFDM systems is presented. In one embodiment, an approach is taken where an inverse Fourier transform (IFT) is performed on data prior to encoding the data for transmission in the multiple-branch transmitter-diversity system. In another embodiment an IFT is performed on data prior to encoding the data using a space-time block code (STBC) algorithm.

Abstract: A system and method for transmitting data in multiple-branch transmitter-diversity OFDM systems is presented. In one embodiment, an approach is taken where an inverse Fourier transform (IFT) is performed on data prior to encoding the data for transmission in the multiple-branch transmitter-diversity system. In another embodiment an IFT is performed on data prior to encoding the data using a space-time block code (STBC) algorithm.

Abstract: A method and system are disclosed for decoding block codes using a single decoder and trellis diagram. The signal can include at least one block code, and the block code can be modulated using at least one of a plurality of modulation modes. The block code contained in the signal can be selectively decoded based on the modulation mode for the block code using a trellis diagram corresponding to the modulation mode for the block code, for example, a low and high-rate CCK modulation mode or a differential quadrature phase shift keying (DQPSK) Baker sequence modulation mode and a differential binary phase shift keying (DBPSK) Barker sequence modulation mode. The trellis diagram can have multiple embedded subtrellis diagrams in the trellis diagram. In this manner, multiple types of block codes and be decoded using a single decoder and trellis diagram.

Abstract: A method for I/Q mismatch calibration of a transmitter. First, a discrete-time signal is generated. Next, a corrected signal based on the discrete-time signal and a set of correction parameters Ap and Bp is obtained. Next, the corrected signal is converted to an analog corrected signal. Next, I/Q modulation is applied to the analog corrected signal and outputs a modulated signal. Next, a first, second, and third desired component measures and a first, second, and third image component measures with the first, second and third sets of the correction parameters Ap and Bp are respectively obtained from the modulated signal. Next, a fourth and fifth set of correction parameters Ap and Bp are obtained based on the first, the second, and the third desired component measures as well as the first, the second, and the third image component measures.

Abstract: An encoder for use in information processing applications includes an input configured to provide information bits to be encoded and a feedforward convolutional outer code encoder configured to encode the information bits to generate encoded information bits including the information bits and parity bits. The encoder may also include at least one interleaver configured to interleave the encoded information bits to generate an outer codeword. Further, the encoder may include a rate-1 1/(1+D) accumulate code based inner code encoder configured to encode the outer codeword to generate one or more codewords corresponding to the information bits.

Abstract: A system and method for estimating channel characteristics in orthogonal frequency-division multiplexing (OFDM) systems with transmitter diversity is presented. The disclosed approach is compatible with the Institute of Electrical and Electronics Engineers (IEEE) “Wireless Local Area Network (LAN) Medium Access Control (MAC) and Physical Layer (PHY) Specification.” In the disclosed system and method, an additional training symbol is transmitted during the data period. This provides additional information that may be used to more accurately estimate channel characteristics.

Abstract: An apparatus and method for calculating bit metrics in data receivers. The apparatus of the invention includes a storage unit and a calculator. The storage unit is configured to store a number of modulation-dependent coefficients; it selects as output one of the coefficients in accordance with a modulation mode being used. The calculator receives the selected coefficient from the storage unit and takes a received signal and a channel response in the frequency domain. According to the selected coefficient, the received signal and the channel response, the calculator generates at least N number of bit metrics for an N-bit codeword in the received signal.

Abstract: A method is directed to recovering a digital data content in a communication system, wherein the digital data content has been converted into an analog signal based on a primary clock, at a transmitter for transmitting to a receiver. The method comprises receiving the analog signal by the receiver. The analog signal is converted into a digital signal, based on a clock of the receiver. The digital signal is interpolated at the desired interpolation point, if digital signal in time has been shifted by an amount equal to or larger than a predetermined time length. The interpolated digital signal is recovered back to the digital data content, with the assist of an estimated channel impulse response. The channel impulse response is retrained every time when the interpolation point is significantly changed.

Abstract: A link quality estimating method and apparatus adopts a fading value to modify an estimated link quality of a channel thereby obtaining a measure being very close to the real link quality. The method is implemented by utilizing two sequentially received long training symbols to derive two sets of subcarrier gain values Hk,1 and Hk,2. Based on the subcarrier gain values Hk,1 and Hk,2, parameters representing the estimated channel gain value (A), the fading value (F) and the noise quantity (B) of the channel are all calculable. With these parameters, the link quality (LQ) of said communication channel is derived.

Abstract: A method and a device for detecting a preamble type of a wireless data frame are provided. The preamble has a synchronization (SYNC) field and a start frame delimiter (SFD) field, and the method comprises following steps. The wireless data frame is first received, and then determined whether the wireless data frame has a short preamble. When the wireless data frame has the short preamble, the wireless data frame is transmitted to a MAC device. In addition, if the wireless data frame does not have the short preamble, it determines whether the wireless data frame has a long preamble. When the wireless data frame has the long preamble, the wireless data frame is then transmitted to the MAC device.

Abstract: An avoidance method for co-channel interference in a wireless network. The first step of the method is to evaluate an interference measure on each subcarrier. Based on the interference measure of each subcarrier, a peak-to-average measure ratio of interference within the received symbol is then obtained. If the peak-to-average measure ratio of interference is greater than a predetermined threshold, a most interfered subcarrier at which the maximal interference measure occurs is detected. Accordingly, a downgrading factor is set for the most interfered subcarrier.

Abstract: A method for I/Q mismatch calibration of a receiver having an I/Q correction module with correction parameters, comprising the steps of generating a test signal containing a single tone waveform with frequency of a carrier frequency plus a predetermined frequency, applying I/Q demodulation to reduce the central frequency of the test signal and outputting a demodulated signal, converting the demodulated signal to a digital signal, obtaining measures of the digital signal respectively indicative of the frequency response of the digital signal at the plus and minus predetermined frequencies, and calculating the set of the correction parameters for the I/Q correction module based on the measures.

Abstract: A method for I/Q imbalance calibration of an OFDM system comprising the steps of initializing parameters Ap, Bp and ?p, estimating a loop delay factor L, generating a discrete-time test signal x[n], deriving a signal xcom[n] by compensating the test signal x[n] according to a function with parameters Ap, Bp and ?p, converting the signal xcom[n] to an analog signal x(t), applying I/Q modulation to the signal x(t) and outputting a modulated signal xmod(t), obtaining a characteristic signal xc(t) of the modulated signal, obtaining a signal xs[n] by sampling the characteristic signal xc(t) and obtaining statistics U1 and U2 of the signal xs[n], and updating the parameters Ap, Bp and ?p respectively by functions of L, U1, U2, and the current values of Ap, Bp and ?p.

Abstract: A method for I/Q mismatch calibration in a receiver. The receiver has an I/Q correction module using parameters Ap and Bp. The method comprises the steps of generating an analog test signal x(t), applying I/Q demodulation to reduce the central frequency of the signal x(t) by fc Hz and outputting a demodulated signal xdem(t), converting the analog signal xdem(t) to a digital signal xdem[n], sending the signal xdem[n] into the I/Q correction module using parameters Ap and Bp and outputting a corrected signal w[n], obtaining two measures U1 and U2 of the corrected signal w[n], and updating the parameters Ap and Bp of the I/Q correction module respectively by a first and second function of the two measures U1 and U2, and the current values of the parameters Ap and Bp.

Abstract: A system and method of processing frequency-diversity coded signals with a low sampling rate less than the Nyquist rate for ultra-wideband devices are described. The frequency-diversity coding system comprises a frequency-diversity encoder, one or more first transformation device, a summation device, a signal filter, a sampling device, a second transformation device and a frequency-diversity decoder. The frequency-diversity encoder encodes a plurality of information blocks to output matrix elements. The first transformation devices convert the matrix elements into a plurality of OFDM symbols. The summation device superposes a plurality of frequency bands to generate a transmitted signal. The signal filter eliminates noise in the received signal. The signal filter comprises a low-pass filter for removing the noise in the received signal. The sampling device coupled to the signal filter samples the received signal by a sampling rate less than a Nyquist rate.