Abstract: A communication system transmits orthogonally encoded data at a symbol rate which is selected from a plurality of symbol rates. The data is encoded in a plurality of packets, each packet having a plurality of symbols having signal points in a field. The signal points of consecutively transmitted symbols are correlated unless the rate is changed, and the data is encoded such that only particular orthogonal descendants of a selected maximum rate code are used. The encoded data is transmitted to a receiver, and orthogonally decoded. A change in the rate of data transmission is recognized when the signal points of consecutively transmitted symbols are not correlated.

Abstract: A method for receiving radio signals in a mobile station, and a mobile station for sending and receiving radio signals are proposed. The method and the mobile station have the aim of correcting predistorted code-spread and phase-modulated radio signals with respect to a phase error. In this context, in the receiver of the mobile station, the phase is determined for the radio signals, in order to carry out a phase demodulation, and the phases are mapped in a preselected phase zone and averaged, in order to formulate therefrom a phase correction factor, by which the code-despread radio signals are multiplied in order to correct the phase error. The method according to the present invention therefore improves the data detection of the received radio signals.

Abstract: Space time transmit diversity (9, 14, 17, 19) is applied at the block level to an original block of bits (12) in order to reduce the effects of fading in wireless communication systems that use nonlinear modulation schemes (13, 33). At the receiving end, fading parameters (?1, ?2) are estimated (?E1, ?E2) and the properties of complex conjugates are utilized (28, 29, 201, 202) to produce a result (r1, r2) that is representative of the original block of bits.

Abstract: A method for conveying over telephone lines digitized voice signals simultaneously with digital data signals by means of a communication system, having a transmitter having a discrete multi-tone unit yielding a plurality of carriers of different frequency, several of which are assigned to the voice signals and others to the data signals. The carriers for transmitting voice are selected on the basis of their signal-to-noise ratio characteristics, which carriers can be reallocated dynamically to data transmission. A first tone ordering circuit assigns data streams to data carriers, and a second tone ordering circuit assigns voice streams to voice carriers. Each carrier is modulated by QAM modulation, the data carriers by a sequence of QAM symbols representing data and the voice carriers by a sequence of QAM symbols representing voice. QAM modulation is carried out by a first constellation encoder that modulates the data carriers and a second constellation encoder that modulates the voice carriers.

Abstract: In a method of discriminating a received spread spectrum signal among a number of received spread spectrum signals that are transmitted over a transmission channel, the received spread spectrum signal is despread, thereby using a locally generated pseudo noise sequence with a given phase offset. The despread received spread spectrum signal is quantized so as to obtain a probability mass function estimate of the despread received spread spectrum signal. A difference is determined between the probability mass function estimate and a true probability mass function that corresponds to a transmitted spread spectrum signal before transmission over the transmission channel. The difference is accumulated over a given number of symbols so as to obtain a statistic of the received spread spectrum signal. If the statistic fails a test against a given threshold, the received spread spectrum signal is rejected. Otherwise, the statistic is accepted.

Abstract: Techniques for selecting either a DFE or an LE for use to equalize a received signal, and for quickly and efficiently determining the coefficients for the selected equalizer. In an embodiment, a method is provided whereby the DFE is initially adapted based on the received signal and a particular adaptive algorithm (e.g., the LMS algorithm) for an initial time period. A quality metric is then determined for an output of the DFE. The DFE is selected for use if the quality metric is better than a threshold value, and the LE is selected otherwise. If the LE is selected, then the initial values for the coefficients of the LE may be derived based on the coefficients of a feed-forward filter and a feedback filter for the DFE, and the LE coefficients may further be adapted for an additional time period prior to its use to equalize the received signal.

Abstract: An improved analog front end and methods for increasing the power efficiency of duplex signals on a transmission line are disclosed. The improved analog front end bifurcates a hybrid into a fixed portion and an adaptive portion. The adaptive portion combines a biquad and a summer to produce a filter transfer function suited to compensate for transmission line irregularities. A method for configuring a local transceiver to minimize power requirements at a remote transmitter is disclosed. Broadly the method entails, applying a transmit signal to a front end in the absence of a remote signal; optimizing the transmit signal power; recording the reflected transmit signal; applying an adaptive filter in response to transmission line irregularities; and controllably adjusting the adaptive filter to minimize the amplitude of the reflected version of the transmit signal in the receive path. A method for recovering a remotely generated signal is also disclosed.

Abstract: A method and apparatus are disclosed for reducing crosstalk in a telecommunication system. Broadly, the present invention utilizes a common mode signal to obtain additional information that can be used to better approximate the transmitted signal (by approximating and canceling crosstalk or otherwise). In accordance with one embodiment of the invention, a modem is provided having improved crosstalk cancellation circuitry for canceling crosstalk received on a local loop (or otherwise estimating the remotely transmitted signal) carrying modem communications. The modem includes a first input for receiving a signal carried on the local loop and a second input for receiving a signal obtained from the common mode. The modem further includes processing circuitry configured to either reduce crosstalk present in the signal carried on the local loop, or to otherwise closely approximate the remotely transmitted signal.

Abstract: A method and an arrangement are provided for generating an estimate of the impulse response of a radio channel. There is generated (202, 406) an initial estimate of the impulse response of a radio channel, and a signal is equalized (203, 407) by using the initial estimate. The equalized signal is decoded (205, 409). There is obtained (411) feedback information from the signal (306) after equalization, an updated channel estimate is generated (304 412) by using said feedback information, and the signal is equalized (407) again by using said updated channel estimate and said feedback information.

Abstract: A method and system are provided for recognizing a path having low level signals, which is conventionally treated as useless, as a valid receiving path. Recognition is made from a plurality of receiving paths in a CDMA wireless telecommunication system by receiving at least one set of signals through a transmission path, generating at least two spread codes each with its own delay time, and calculating at least two correlation values of the set of signals with the spread codes. A CDMA wireless telecommunication mobile station is also provided for receiving a set of telecommunication signals through a telecommunication path from a base station. At least two spread codes are generated, each with its own delay time and a predetermined number of spread code bits. At least two correlation values of the set of signals are calculated with the spread codes.

Abstract: Radiocommunication systems, methods and terminals are described wherein metrics associated with MLSE detecting techniques, e.g., using the Viterbi algorithm, are accumulated in a manner which is less computationally intensive than conventional techniques. The delta metrics associated with each state are partitioned into, for example, six different terms. These terms are then selectively accumulated in phases, before decisions, during decisions and after decisions, to reduce the total number of computations associated therewith. Additionally, certain symmetries associated with exemplary modulations are taken into account in order to further simplify processing and memory requirements of these detecting techniques.

Abstract: A system and method for efficiently correcting block errors in packet-based digital communications are provided whereby the ratio of redundant symbols/message symbols over the length of a data packet decreases in order to more efficiently use available bandwidth. The reduction of this ratio, and subsequently the change in a corresponding framing schedule, may be determined through negotiations between the transmitting device and the receiving devices. Each receiving device calculates a redundancy requirement based on signal-to-noise ratio samples. This requirement is returned to the transmitting device in the form of a schedule request. The transmitting device determines if a new framing schedule is needed based on the schedule request, and communicates this new framing schedule to the receiving device. Once the receiving device acknowledges receipt of the new schedule, the transmitting device switches to the new framing schedule for future data packet transmissions.

Abstract: The present invention includes a wireless communication system. The wireless communication system includes a plurality of transceiver antennae. Each transceiver is spatially separate from at least one other transceiver antenna. Each transceiver antenna includes a transceiver antenna polarization. At least one transceiver antenna has a polarization that is different than at least one other transceiver antenna. Each transceiver antenna transmits a corresponding data stream. The wireless communication system further includes a plurality of receiver antennae. The receiver antennae receive at least one data stream. The transceiver antenna polarization of each transceiver antenna is pre-set to optimize separability of the received data streams. A transmission channel between the transceiver antennae and the receiver antennae can be estimated with a channel matrix. The pre-set transceiver antenna polarization of each transceiver antenna can be determined by minimizing a singular value spread of the channel matrix.

Abstract: An approach is provided for bit labeling of a signal constellation. A transmitter generates encoded signals using, according to one embodiment, a structured parity check matrix of a Low Density Parity Check (LDPC) code. The transmitter includes an encoder for transforming an input message into a codeword represented by a plurality of set of bits. The transmitter includes logic for mapping non-sequentially (e.g., interleaving) one set of bits into a higher order constellation (Quadrature Phase Shift Keying (QPSK), 8-PSK, 16-APSK (Amplitude Phase Shift Keying), 32-APSK, etc.), wherein a symbol of the higher order constellation corresponding to the one set of bits is output based on the mapping.

Abstract: Coding techniques for a (e.g., OFDM) communication system capable of transmitting data on a number of “transmission channels” at different information bit rates based on the channels' achieved SNR. A base code is used in combination with common or variable puncturing to achieve different coding rates required by the transmission channels. The data (i.e., information bits) for a data transmission is encoded with the base code, and the coded bits for each channel (or group of channels with the similar transmission capabilities) are punctured to achieve the required coding rate. The coded bits may be interleaved (e.g., to combat fading and remove correlation between coded bits in each modulation symbol) prior to puncturing. The unpunctured coded bits are grouped into non-binary symbols and mapped to modulation symbols (e.g., using Gray mapping). The modulation symbol may be “pre-conditioned” and prior to transmission.

Abstract: A system, method and apparatus for demodulating a received signal using a configurable receiver. The receiver performs the demodulation of a signal according to a selected interference cancellation demodulation scheme. The same receiver can be configured, by setting certain parameters, to behave as a successive interference cancellation (SIC) scheme receiver, a parallel interference cancellation (PIC) scheme receiver, or a hybrid interference cancellation (HIC) scheme receiver. In another aspect of the present invention, the receiver performs its demodulation operation using a single interference cancellation unit (ICU). In addition, the ICU's despreading and respreading functions may be performed by the same processing element.

Abstract: A method for blind source separation of sources detects the sources using sensors to obtain representative data. The data is then represented by two mixtures having estimates of amplitude and delay mixing parameters. The estimates are updated, including: calculating error measures, each indicating a closeness of the estimates for a given source to a given time-frequency point in the mixtures; and revising the estimates, based on the error measures. The mixtures are filtered to obtain estimates of the sources, including: selecting one error measure having a smallest value in relation to any other error measures, for each time-frequency point in the mixtures; and leaving unaltered any time-frequency points for which a given error measure has the smallest value, while setting to zero any other time-frequency points for which the given error measure does not have the smallest value, for each error measure. The estimates of the sources are output.

Abstract: A phase detector circuit for a phase control loop includes two EXOR circuits and an integrating loop filter which are connected to form one circuit. The two EXOR circuits have common load resistors or current sources. The output signals from the EXOR circuits are integrated through the use of two integrators, which are respectively connected in parallel with the common load resistors or current sources. The voltage across the two integrators provides the output voltage of the loop filter. This eliminates the need for an additional differential amplifier and integrator. The phase detector has a low current consumption and can be produced with a simplified circuit technique.

Abstract: Apparatus, and an associated method, for creating a profile associated with burst data signals communicated to a base station of a fixed wireless access communication system. The profile is created to facilitate receive operations performed upon subsequent bursts of the burst data signal. The profile is stored at a storage device and retrieved when subsequent bursts of the bursts data signal are received at the base station.

Abstract: A method and a system for decoding information signals encoded by a multi-state encoding architecture and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are detected in a symbol decoder, implemented using look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The symbol decoder is implemented as a pair of slicers, each detecting an input signal with respect to one of two disjoint symbol-subsets. A third slicer detects the input with respect to the union of the two disjoint symbol-subsets. Decisions from the first, second and third slicers are processed to define 1D square error terms expressed in Hamming metrics. Reduced bit count error terms allow follow-on error processing to be performed with a minimum of computational complexity.