Abstract: Potential interference is reduced in an impulse radio. A signal including an impulse signal and potential interference is received by the impulse radio. The impulse signal includes a sequence of impulses. The sequence of impulses of the received signal is sampled at a sequence of data sample times to produce a sequence of data samples. The received signal is also sampled at a plurality of time offsets from each of the data sample times to produce a plurality of nulling samples corresponding to each of the data samples. A separate sequence of nulling samples for each of the time offsets is thereby produced. Each of the data samples is then separately combined with a corresponding nulling sample from each of the separate sequences of nulling samples to produce a separate sequence of adjusted samples corresponding to each of the time offsets. A separate quality metric, representative of a signal-to-interference level, is then determined for each of the separate sequences of adjusted samples.

Abstract: A method and an apparatus transmits information in various carrier frequencies with frequency hopping. A table 25 with a plurality of n possible carrier frequency values fx in addresses 1 through N of the table 25 is thereby offered. Further, a sequence of random values is generated, for example in a random number generator 22, on the basis whereof a part M of the N carrier frequency values fx is read from the corresponding addresses of the table 25, whereby M?N applies. Information is subsequently transmitted in the corresponding carrier frequencies. The inventive apparatus or, respectively, the inventive method can be implemented, for example, in a mobile station and/or a base station of a mobile radiotelephone system.

Abstract: A Viterbi decoder system is provided in accordance with the present invention. The decoder system includes a State Metric Update unit including a state metric memory and a cascaded Add/Compare/Select (ACS) unit. The cascaded ACS unit comprises a plurality of serially coupled ACS stages for performing a plurality of ACS operations in conjunction with the state metric memory. An ACS stage is operable to identify a plurality of path decisions and path differences and communicate the identified path decisions and the identified path differences to a next ACS stage coupled thereto. The decoder also includes a Traceback unit for storing a set of accumulated path decisions in a traceback memory associated therewith, and performing a traceback on the set of accumulated path decisions. The path decisions associated with the ACS stage and the next ACS stage are accumulated as a set during the ACS operations before being written to the traceback memory, thereby minimizing accesses to the traceback memory.

Abstract: Methods and apparatuses for iterative parameter estimation are described. The iterative parameter estimation includes performing a first estimation of a first portion of a signal to obtain first parameters of the portion of the signal, wherein the signal contains no known data symbols. The first portion of the signal is demodulated using the first parameters to recover data symbols. The demodulated first portion of the signal is checked to confirm correct demodulation of the first portion of the signal. A second estimation of the first portion of the signal is performed using the recovered data symbols to obtain second parameters of the first portion of the signal. Then, a second portion of the signal is demodulated using the second parameters when the first portion of the signal is correctly demodulated.

Abstract: The evolution of high rate data services within future wireless networks will call for new RF access technologies to enable substantial increases in overall system spectral efficiency at an acceptably low cost to the user. Space-Time Coding (STC) is an antenna array processing technology currently simulating considerable Interest across the wireless industry. The invention provides a space-time coding apparatus having an input, a trellis encoder, a modulator, a demultiplexer, and a set of signal outputs wherein the input is operable to receive a stream of data. This allows de-multiplexing to take place after coding and modulation has been performed. The trellis encoder comprises a convolutional encoder operable to sequentially group data to provide coded bits to provide QPSK symbols. By the selection of convolutional encoder rates and/or modulation alphabets STCs of any desired dimensionality may be produced including multi-dimensional codes.

Abstract: A portable radio system, a portable radio equipment to be used in the same and a frequency error prediction method can be adapted to large frequency error by making tap number smaller and frequency error smaller. The portable radio system employs an automatic frequency control for detecting a frequency shift of an internal oscillator of a portable radio equipment with reference to a received wave transmitted from a base station having higher precision of frequency and adjusting the frequency of the internal oscillator by feeding back the frequency shift to the internal oscillator. Coordinate rotation digital computation (CORDIC) is employed for calculation of arctangent in the automatic frequency control.

Abstract: Serially transmitted digital data are received in a predetermined format such as an SPDIF format. In the format, identification data are incorporated in the serial data in predetermined cycles. Generation of a train of bit-extracting pulses having a predetermined pulse generation pattern is triggered by detection of a pulse edge of the received serial data. By counting the bit-extracting pulses, bit location information is generated which identifies each bit location in the received serial data. Each identification data is detected from among the received digital data and the number of detections of the identification data within a predetermined time period is calculated, so as to identify a transmission rate of the digital data on the basis of the number of detections.

Abstract: A method for reducing interblock interference (IBI) in an impulse response signal transmitted by a communications channel such as a digital subscriber loop (DSL) channel. The method includes computing a time of reference (TOR) based on a windowing function that assumes that the main lobe segment of the impulse response signal does not contribute IBI power and that the tail segments of the impulse signal, which fall outside of the main lobe segment of the impulse signal, contribute a non-uniform amount of IBI power. The method reduces IBI in the impulse response signal beyond that of conventional IBI reducing methods.

Abstract: A digital signal receiver capable of obtaining a favorable receiving performance even if the input signal level changes rapidly is presented. A control voltage for controlling a variable gain amplifier is read by a microprocessor, and an operation-starting point of the variable gain amplifier is shifted by using this control voltage. As a result, a favorable level fluctuation response characteristic is obtained regardless of the input level.

Abstract: In a direct sequence spread spectrum data communication system an information bit is mixed with a pseudorandom noise or spreading code to produce modulated codeword for transmission. A method of bandwidth efficient M-ary phase shift key modulation encoding at least 16 bits of data to a single codeword is disclosed for extending the data rate of a spread spectrum system. Interoperability with legacy devices is maximized by maintaining structural similarity between the modulated waveforms of the extended data rate and legacy systems.

Abstract: Apparatus, and an associated method, for estimating frequency offset introduced upon symbols of a sequence communicated by a sending station to a data destination during operation of a communication system. A received sequence is rotated by multiplying the symbols thereof by offset values selected from a set of offset values. Then, for each rotated sequence, an estimation of a data sequence is made. Noise indicia associated with each estimated data sequence is calculated. And, comparisons are made of the noise indicia associated with each of the estimated data sequences. Responsive to the comparisons, selection is made of the frequency offset that has been introduced upon the data sequence.

Abstract: In a method of digital data transmission in a wireless communication network in which a controlling communication takes place within a fixed bandwidth of a channel from a master station to all subscribers (downlink) with the help of a fixed signal frame, and the beginning of the fixed signal frame is marked by a special frame synchronization signal detectable by the subscribers, an occupancy of at least one subband by transmission signals and a non-occupancy of at least one complementary subband by transmission signals is used as a frame synchronization signal.

Abstract: An impulse detector which can detect both low and high levels of impulse noise in a CDMA system is comprised of circuitry to calculate the background noise level in unused codes. Another circuit calculates the average noise power in the unused codes of each spreading interval to output the noise power per spreading interval. This average is continuously averaged over spreading intervals by another circuit which outputs the average background noise power. A comparator compares the noise power in the current spreading interval with the background noise power plus a programmable threshold and generates an erasure indication if the background noise power plus a discrimination threshold is exceeded.

Abstract: There is disclosed a finger for effectively processing signals received via multi-path in a receiver of a mobile communication system and a RAKE receiver having the finger. In processing signals received by a plurality of antennas in the present invention, a single finger batch-processes the signals received by the plurality of antennas using the property that the time delays of the received signals are almost same and a time division method. At this time, a single apparatus batch-processes a portion necessary for a common calculation and a plurality apparatus separately process portions necessary for separate calculations. Thus, the present invention can provide a high-performance finger and a RAKE receiver having the finger wherein a single finger can process each of signals received by a plurality of antennas.

Abstract: A time synchronization system comprises a GPS (Global Positioning System) receiver for receiving a time signal from a Global Positioning System (GPS), and outputting a UTC (Universal Time Coordinated) synchronization reference signal synchronizing with UTC and a UTC synchronization absolute time signal, and a time signal distributor for generating a reference time signal synchronizing with UTC from the synchronization reference signal and the absolute time signal, and transmits this reference time signal in distribution to a plurality of distributed control oriented terminal devices. The time synchronization between the plurality of distributed control oriented terminal devices can be thereby taken.

Abstract: An apparatus for acquisition of an asynchronous wideband direct-sequence/code division multiple access signal, which acquires a long code from a direct-sequence/code division multiple access control channel signal, in which a common short code, and the long code are transmitted within one frame, and a group identification code indicating a code group, to which a base station belongs, are combined and transmitted with the common short code, includes: a long code masking correlation portion; a differentially coherent combining portion; a code group and frame timing acquisition portion; and a long code acquisition portion for acquiring the long code by correlating the long codes belonging to the acquired code group and the received long code, respectively.

Abstract: A method for differential phase evaluation of M-ary communication data is employed in which the data consists of N sequential symbols r1 . . . rN, each having one of M transmitted phases. Selected sequences of N?1 elements that represent possible sequences of phase differentials are evaluated using multiple-symbol differential detection. Using r1 as the reference for each phase differential estimate, sN?1 phase differential sequences are selected in the form (P2i, P3i, . . . , PNi) for i=1 to s for evaluating said symbol set, where s is predetermined and 1<s<M. Each set of s phase differential estimate values are chosen based on being the closest in value to the actual transmitted phase differential value. These s phase differential estimates can be determined mathematically as those which produce the maximum results using conventional differential detection.

Abstract: A technique for decoding an encoded data stream representing an original sequence of data bits, each data bit comprising a plurality of codes, each code being dependent on a current data bit and a first predetermined number of preceding data bits in the original sequence. Scores are provided indicating the likelihood that a corresponding state represents the first predetermined number of preceding data bits. The scores are arranged in an initial ordering. A first plurality of score bit slices are stored to collectively represent the initially ordered scores, each score bit slice containing a predetermined bit from each of the scores. The scores are then reordered and a second plurality of score bit slices are stored to collectively represent the reordered scores. By this approach, all the scores are updated simultaneously.

Abstract: A procedure for the semi-blind separation and detection of digital co-channel signals, whereby after a simultaneous spatial-temporal equalization, iterative projections of the symbol vectors to be detected, in a vector subspace or a symbol alphabet &OHgr; of finite size are initialized making use of a network user identifier IDi. These projections are then used to adapt the symbol vectors Si to the vector subspace and to the symbol alphabet &OHgr; of finite size, making use of the method of least squares algorithm but performing only matrix multiplications without eigenvalue or singular decompositions.

Abstract: A method to transfer data from a digital data modulator device to a digital data demodulator device over a subscriber line. The digital data modulator device has a detection circuit for detecting incoming idle ATM cells, and a cascade coupled null data cell generator, a trellis code modulator, a data encoder/mapper, a constellation points rotation circuit and a constellation points shifting circuit for shifting constellation points to lower power points. The digital data demodulator device has a detection circuit for detecting received null data, and a cascade coupled de-shifting circuit for shifting constellation points with the lowest power back to points corresponding to null data cells, a de-rotation circuit for de-rotating the constellation points, a data decoder/de-mapper and a trellis code de-modulator. Transmission power of idle data is minimized, and the random rotation of low power constellation points simplifies the training and tracking of the frequency equalizer in the demodulator.