Abstract: Channel estimation and spatial processing for a TDD MIMO system. Calibration may be performed to account for differences in the responses of transmit/receive chains at the access point and user terminal. During normal operation, a MIMO pilot is transmitted on a first link and used to derive an estimate of the first link channel response, which is decomposed to obtain a diagonal matrix of singular values and a first unitary matrix containing both left eigenvectors of the first link and right eigenvectors of a second link. A steered reference is transmitted on the second link using the eigenvectors in the first unitary matrix, and is processed to obtain the diagonal matrix and a second unitary matrix containing both left eigenvectors of the second link and right eigenvectors of the first link. Each unitary matrix may be used to perform spatial processing for data transmission/reception via both links.

Abstract: A soft symbol decoder for use in a multiple input multiple output (MIMO) and OFDM (orthogonal frequency division multiplexing) system. The decoder generates soft symbol values for a digital signal that represents a number of source bits. The source bits are transmitted as symbols in corresponding to points in a signaling constellation. Soft metrics are determined by searching for all possible multi-dimensional symbols that could have been transmitted. The method includes transmitting a sample of the multi-dimensional symbol using K transmit antennas. The multi-dimensional symbol is represent-able as a complex, K-dimensional vector x. Each vector component of vector x represents a signal transmitted with one of the K transmit antennas. After transmission through a communication channel, a sample corresponding to the transmitted sample is received. The received sample is represented by a complex, N-dimensional vector y, where N is the number of receive antennas in the MIMO system.

Abstract: A method and apparatus for allocating subcarriers in a broadband wireless communication system using multiple carriers are provided. In the wireless communication system where the total available frequency band is divided into a plurality of subcarriers and subchannels each are formed with a predetermined number of subcarriers, the subcarriers are grouped into subcarrier groups, subcarriers are selected from the subcarrier groups according to predetermined sequences, and the selected subcarriers are allocated as a subchannel to a cell in a predetermined time period.

Abstract: A data acquisition system includes a programmable gain amplifier, an analog-to-digital converter, a filter, and control circuitry. The programmable gain amplifier is operatively connected to receive an analog input signal on its input and generates an amplified signal on its output in accordance with gain control signals. The analog-to-digital converter is operatively connected to receive the amplified signal from the amplifier and generates a digitized signal on its output. The filter is operatively connected to receive the digitized signal from the converter and generates a filtered digital signal on its output. The control circuitry is operatively connected to the amplifier and to the converter and is also responsive to the gain control signals for dynamically adjusting power between the amplifier and converter when the gain control signals are changed.

Abstract: The present invention relates to a system and method for generating a first clock frequency for a plurality of digital data bursts compressed in time, where each of the plurality of digital data bursts has been multiplexed into one of a plurality of data blocks of higher speed digital data. The system and method includes acquiring the width in data elements of a digital data burst and the width in data elements of a data block of higher speed digital data. The width of one period of a clock pulse is computed at the first clock frequency. A clock pulse is generated at the first clock frequency.

Abstract: A communication circuit (28) is designed with a signal processing circuit (370) arranged to produce a first plurality of data signals and receive a second plurality of data signals. A transmit circuit (364) is coupled to receive the first plurality of data signals and transmit each data signal of the first plurality of data signals on a respective transmit frequency in a predetermined sequence of transmit frequencies. A receive circuit (362) is coupled to receive each data signal of the second plurality of data signals from a remote transmitter on the respective transmit frequency in the predetermined sequence. The receive circuit applies the second plurality of data signals to the signal processing circuit.

Abstract: A method and apparatus for a UWB radio utilizing MEMS filtering is described. The method described includes receiving a pulse signal from a transmission station. Once received, a delay line including one or more taps is driven with the pulse signal. Once the pulse signal exits the delay line, the delay line is sampled at each of the taps to determine a time delay and amplitude of each echo in the pulse signal. These steps are repeated for each pulse signal received until a delay/amplitude map of the transmission channel between the stations is complete. Using the echo map, a time delay and amplitude of each echo indicated by the map is determined synthetic and recursive anti-echoes. Accordingly, when transmitting or receiving a signal over the channel, anti-echoes are combined with the signal in order to eliminate channel echoes in a received signal.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: Disclosed is a method and a system for performing N-ary modulation in which bit errors may be reduced against symbol error. A binary signal, a bit length thereof being n, is associated with N-ary signals arranged in first and second phase planes respectively for transmission, wherein N is not a number belonging to powers of 2 but is a number belonging to a series beginning from 12 and sequentially doubled, that is, any one of 12, 24, 48, 96, . . . , and wherein n is such that, if the bit length n is 7, 9, 11, 13, . . . , the number N is 12, 24, 48, 96, . . . , respectively, two out of the n bits are allocated for identifying four quadrants of the first phase plane, two out of the remaining (n?2) bits are allocated for identifying four quadrants of the second phase plane. The binary signal of three out of the n bits is converted into two digits of ternary signals (T1, T2). The ternary signals are mapped to the first and second phase planes with rotational symmetry of 90° or with axial symmetry.

Abstract: A receiver includes an input, a correlator, a phase-assisted demodulator, and an output. The input receives a modulated signal and the correlator generates a plurality of correlation values from the received modulated signal The phase-assisted demodulator, coupled to the correlator, selects one of the plurality of correlation values based on relative magnitude and relative phase information of at least a two of the plurality of correlation values. The output provides a demodulated signal, corresponding to the modulated signal, based on the selected one of the plurality of correlation values. The correlation value having the largest magnitude and the correlation value having the second largest magnitude is used in combination with the relative phase information of both correlation values in determining which correlation value corresponds to the correct demodulated symbol.

Abstract: A method and system for retrieving a desired user data symbol sequence from a received signal are disclosed. In one embodiment, the method includes i) receiving a channel modified version of a transmitted signal comprising a plurality of user data symbol sequences, each being encoded with a user specific known code, ii) determining an equalization filter directly and in a deterministic way from the received signal and iii) applying the equalization filter on the received signal to thereby retrieve the transmitted signal.

Abstract: A transcoding method and apparatus and a motion vector interpolation method. The transcoding method and apparatus convert moving picture data from one encoding format to another encoding format. The transcoding method includes (a) decoding an image coded in a first encoding method and then obtaining encoding mode information and motion vector information of each block of the image; (b) selecting at least one of available encoding modes of a second encoding method based on the encoding mode information of each block of the decoded image; and (c) performing a motion estimation process on each block of the decoded image in the at least one selected encoding mode and then determining an optimal encoding mode for each block of the decoded image based on the motion estimation result(s).

Abstract: A multicarrier transmitter assigns for each of a plurality of spatial channels, sets of the constellation symbols to subcarriers of each subchannel. Constellation symbol assignments to the subchannels are circularly rotated among some of the spatial channels so that subchannels use different sets of subcarriers for each spatial channel for enhanced frequency diversity.

Abstract: The present invention includes a time-division-multiple-access (TDMA) communication system having a base station and at least one mobile station, each transmitting and receiving an analog radio-frequency signal carrying digitally coded speech. The speech is encoded using a vocoder which samples a voice signal at variable encoding rates. During periods when the radio-frequency channel is experiencing high levels of channel interference, the encoded voice channel having a lower encoding rate is chosen. This low-rate encoded voice is combined with the high degree of channel coding necessary to ensure reliable transmission. When the radio-frequency channel is experiencing low levels of channel interference, less channel coding is necessary and the vocoder having a higher encoding rate is used. The high-rate encoded voice is combined with the lower degree of channel coding necessary to ensure reliable transmission.

Abstract: The present invention relates to a filter apparatus and method having a fixed aspect for providing a predetermined selectivity and having an adaptive aspect for determining the frequency response of said filter apparatus. The adaptive aspect is controlled to change the frequency response. Predetermined zero values of the filter characteristic are set to provide a predetermined filter selectivity; and at least one filter parameter is controlled to change pole values of the filter characteristic so as to provide frequency response adaptation. Thereby, the frequency response of the filter operation can change while the filter selectivity can be maintained. The filter apparatus is thus able to cope with advanced system requirements while keeping the complexity and power consumption low.

Abstract: A phase detector generates a phase dependent control signal according to the phase relationship between a first and second clock signal. The phase detector includes first and second phase detector circuits receiving the first and second clock signals and generating select signals having duty cycles corresponding to the phase relationship between the clock edges of the first and second clock signals. The phase detector also includes a charge pump that receives select signals from the phase detector circuits and produces an increasing or decreasing control signal when the first and second clock signals do not have the predetermined phase relationship, and a non-varying control signal when the first and second clock signals do have the predetermined phase relationship. The control signal may be used to adjust the delay value of a voltage-controlled delay circuit in order to adjust the phase relationship between the first and second clock signals to have a predetermined phase relationship.

Abstract: A communication system includes a transmitter, a communication channel, and a receiver. The transmitter includes a pre-emphasis module, a summing module, a line driver, and a decision feedback pre-emphasis (DFP) module to produce a pre-emphasized serial stream of data based on a communications channel response and an inter-symbol interference level. The receiver includes a linear equalizer, a summing module, a decision module, and a decision feedback equalization (DFE) module. The linear equalizer produces an equalized serial stream of data. The summing module sums at least one data element of the equalized serial stream of data with DFE data elements to produce equalized data elements. The decision module interprets the equalized data elements to produce interpreted data elements to DFE module, which produces the DFE data elements from the interpreted data elements.

Abstract: A signal routing apparatus comprises a register bank to store a set of data signals. A delay locked loop generates a set of phase displaced clock signals. A phase controlled read circuit sequentially routes the set of data signals from the register bank in response to the phase displaced clock signals. A Low Voltage Differential Signaling buffer connected to the phase controlled read circuit transmits the data signals in a Low Voltage Differential Signaling mode. The phase displaced clock signals operate in lieu of a higher clock rate in order to reduce power consumption.

Abstract: Carrier interferometry (CI) methods may be used to provide transmission protocols having various desirable properties. Such properties may include interference rejection, reduced multipath fading, and/or operation across discontinuous frequency bands. Codes used for such CI techniques, known as CI codes, may be orthogonal polyphase codes.

Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels. A transmitter system and a receiver system are described for the communication system.