Abstract: A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

Abstract: Methods, apparatus, and computer program products are disclosed for clock signal synchronization among computers in a network, including designating, as a primary clock signal for all the computers in a network, a clock signal from one of the computers in the network; providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through multiplexers and phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer.

Abstract: A disclosed network device includes a plurality of interface cards that receive clock signals and clock signal quality information from other devices via communication lines, respectively being predetermined communication line types corresponding to the plurality of interface cards, a controller that acquires the clock signal quality information and determines one of the clock signals having a highest quality based on this, and a clock processor that generates a synchronization clock signal used for network synchronization the clock processor, based on the determined one of the clock signals, whereby the clock processor includes a frequency measuring instrument that measures a frequency component of the one of the clock signals, and determines the communication line type corresponding to one of the interface cards, and a clock controller that provides a coefficient to a digital filter based on the determined communication line type.

Abstract: An input bit stream including a clock signal and data bits is oversampled to obtain one or more sets of data samples. One or more sets of non-transitioning phases corresponding to data samples that do not switch between zero and one are then identified. Center phases corresponding to the one or more sets of non-transitioning phases are identified and then a final center phase that accurately represents the bits belonging to the input bit stream is selected. The data samples corresponding to the final center phase are extracted, thereby recovering the clock signal and data bits from the input bit stream.

Abstract: Apparatus, systems, and methods are provided for transmitting messages over a serial interface. A method comprises receiving a first signal at a first time and receiving a second signal at a second time, the second time being after the first time. If a difference between the second time and the first time is less than a threshold time period, the method comprises generating a first message that is representative of the first signal and the second signal and transmitting the first message over the serial interface. In accordance with one embodiment, the threshold time period is equal to one half of an interface acquisition delay time period associated with the serial interface.

Abstract: The present invention relates to an apparatus and method for estimating and compensating for a time offset and a carrier frequency offset in a Multiple Input Multiple Output (MIMO) communication system that supports Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiplexing Access (OFDMA). According to the present invention, a phase difference of pilot signals of the same transmitting antenna, which are received through receiving antennas, is calculated. An arc tangent operation is then carried out on the phase difference of the pilot signals to calculate a time offset linear phase and/or a carrier frequency offset linear phase. Further, a time offset compensation value and/or a carrier frequency offset compensation value are found by employing the time offset linear phase and/or the carrier frequency offset linear phase.

Abstract: A system including a magnitude measuring module, an energy normalization module, and a metric generation module. The magnitude measuring module is configured to measure magnitudes of real portions of differentially demodulated signals, wherein the differentially demodulated signals are generated by differential demodulation of signals received from a base station. The energy normalization module is configured to generate a sum of energies of a plurality of subcarriers included in the signals received from the base station. The metric generation module is configured to generate a plurality of metrics for a plurality of symbols included in the signals received from the base station. The metric generation module is further configured to detect, based on the plurality of metrics, a preamble symbol included in the signals received from the base station.

Abstract: A method is provided for maximizing utility of a media delivery network having a media source, a first media adaptor, a second media adaptor and a media renderer. The media source can provide data in a first format and a second format. The first media adaptor can receive the data in the first format from the media source. The second media adaptor can receive the data in the second format from the media source. The first media adaptor can further provide data in a third format based on the received data in the first format. The second media adaptor can further provide data in a fourth format based on the received data in the second format. The media renderer can render the data in the third format and can render the data in the fourth format.

Abstract: The invention concerns a method for receiving a multi-carrier signal of reduced complexity when the number of carriers is not high. The method includes: demodulating the multi-carrier signal; converting a received signal received in binary representation into a modal representation in a base of at least two mutually prime numbers on a finite space of size equal to the product of the mutually prime numbers; demodulating including conversion.

Abstract: The invention provides a method of generating a downlink signal and searching a cell on the basis of the downlink signal in an OFDM-based cellular system. The downlink signal includes a plurality of synchronization blocks each having a plurality of sub-frames, and a synchronization pattern composed of a combination of a cell group identification code for identifying a cell group and a frame synchronization identification code for indicating a frame start point is generated in each of the synchronization blocks. Different frame synchronization identification codes are allocated to the synchronization blocks.

Abstract: A mobile communication network includes an antenna site shared by two or more telecommunications service providers. The antenna site includes a shared resource, such as an antenna, telecommunications equipment, or bandwidth, used by multiple service providers and connects to multiple signal processing centers, each of which belongs to one of the service providers. The signal processing centers may provide modulating signals to the antenna site to use in modulating a carrier. The antenna site may also direct received signals from mobile terminals to the signal processing center for the appropriate service provider. A billing module at the antenna site maintains an accounting of resources used by each service provider.

Abstract: A system includes an input, a differential demodulation module, a magnitude measuring module, a summing module, and a metric generator module. The input receives input signals that include s sets of modulated sub-carriers carrying symbols, where s is an integer greater than or equal to 1. The differential demodulation module generates differentially demodulated signals based on the input signals. The magnitude measuring module measures magnitudes of real portions of the differentially demodulated signals. The summing module generates s sums, wherein each of the s sums is a sum of the magnitudes generated based on a respective one of the s sets. The metric generator module generates metrics for the symbols based on the s sums.

Abstract: A wireless local area network (WLAN) transceiving integrated circuit services voice communications in a WLAN with at least one other WLAN device. The WLAN transceiving integrated circuit includes a WLAN interface, an input buffer, a transcoder, and a processor. The WLAN interface wirelessly communicates with the at least one WLAN device to receive packetized audio data from the at least one WLAN device. The input buffer operably couples to the WLAN interface and receives the packetized audio data from the WLAN interface. The transcoder converts the packetized audio data to Pulse Code Modulated (PCM) audio data and outputs the PCM audio data to a coupled audio COder/DECoder (CODEC) such that the PCM audio data is substantially temporally aligned with Radio Frequency (RF) slots of the WLAN interface.

Abstract: Embodiments of system and method for generating channel estimates in a wireless network are generally described herein. Other embodiments may be described and claimed. In some embodiments, a linear interpolator uses refined cross-correlation and autocorrelation estimates and pilot subcarrier estimates to generate channel estimates for the current OFDM data symbol.

Abstract: A method of processing data comprises the receiving a frame of data having a predetermined number of time slots (502,504,506). Each time slot comprises a respective plurality of data symbols (520). The method further comprises a primary (508), a secondary (510) and a tertiary (512) synchronization code in each said predetermined number of time slots.

Abstract: In a mobile communication system, multiple transceivers perform radio communications in the same frequency band.

Abstract: Receivers (1) for receiving frequency signals are, to improve their time synchronization accuracy, provided with synchronization stages (20) for performing a coarse time synchronization through autocorrelating samples of a group of preamble symbols (t1,t2,t3) and a fine time synchronization through crosscorrelating samples of a further group of preamble symbols (t10,G1) with predefined samples. The synchronization stages (20) also perform a coarse and a fine frequency synchronization through detecting and accumulating phases of samples of a yet further group of preamble symbols (t8,t9) and of another group of preamble symbols (T1,T2). The synchronization stages (20) have buffering units (21) and controlling units (22) for controlling mixing units (11) and transformating units (12) in processing stages (10). The preamble symbols have ten short preamble symbols (t1-t10), a guard interval preamble symbol (G 1) and two training symbols (T 1,T2).

Abstract: Systems and methods are provided for the transmission of waveforms. The method includes inserting at least one TDM pilot symbol located at a transition between wide area and local area waveforms to facilitate decoding of the transmission block.

Abstract: A time reference point can be determined in a radio system by sending a synchronization sequence s(i), i=0, . . . N?1, from transmitter X, 40 to receiver Y, 48, and by detecting the peak value at the output of a matched-filter, 44, h(i)=s(N?1-i) on Y. In practical systems the accuracy of this peak detection is limited by interference and noise on the radio channel. To increase the peak detection accuracy, we propose to repeat the transmission of the same synchronization sequence K times. The interval L between repetitions is constant and the amplitude of the synchronization sequence in each repetition varies according to a given variation pattern a(jL), j=0, . . . , K?1. The receiver Y, 48 knows L and a(jL), j=0, . . . , K?1. After comparison to a threshold, the matched-filter 44 at the receiver 48 may deliver peaks resulted from repeatedly received synchronization sequences or peaks caused by interference and/or noise.

Abstract: A packet preamble search method is disclosed for locating a packet preamble with multiple predetermined patterns of a regular form within a received transmission signal with sequential multiple patterns. The pattern of the received transmission signal and the predetermined pattern of the packet preamble have the same length with even bits. The pattern of the transmission signal is sequentially compared with the predetermined pattern. A hit count is increased and a miss count is reset when the pattern of the transmission signal matches the predetermined pattern. The miss count is increased and the hit count is decreased when the pattern of the transmission signal does not match the predetermined pattern. The hit count and the miss count are reset when the hit count is less than or equal to the miss count. An address matching procedure is activated when the hit count exceeds or is equal to a threshold value.

Abstract: Synchronization techniques for reducing the effects of time dispersive wireless communications channels are presented. A synchronization technique for communications over a time dispersive wireless channel includes receiving a signal having at least identical first and second symbols, and calculating a metric for each sampling time by correlating respective samples of the first symbol included in a first sampling window with respective samples of the second symbol included in a second sampling window. The technique further includes identifying one of the sampling times at which the metric attains a maximum value, and estimating an optimal time offset for synchronizing to the received signal based on the identified sampling time. Optionally, the technique further includes estimating a carrier frequency offset based on the difference of phase of the complex conjugate samples at the maximum absolute value of the metric.

Abstract: The manipulation of audio data can be simplified, such as, for example, with regard to the combination of individual audio data streams to multi-channel audio data streams or the general manipulation of an audio data stream, by modifying a data block in an audio data stream divided into data blocks with determination block and data block audio data, such as by completing or adding or replacing part of the same, so that the same includes a length indicator indicating an amount or length of data, respectively, of the data block audio data or an amount or length of data, respectively, of the data block to obtain a second audio data stream with modified data blocks. Alternatively, an audio data stream with pointers in determination blocks, which point to determination block audio data associated to this determination blocks, but distributed among different data blocks, is converted into an audio data stream, wherein the determination block audio data are combined to contiguous determination block audio data.

Abstract: Systems and methods are disclosed for time synchronization of operations in a control system. Synchronization networks and devices are provided for transferring synchronization information between controllers in a distributed or localized control system, which is employed in order to allow operation of such controllers to be synchronized with respect to time. Also disclosed are synchronization protocols and hardware apparatus employed in synchronizing control operations in a control system.

Abstract: A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

Abstract: Methods and systems provide approaches to start code emulation prevention at a granularity higher than the bit level. By operating at a level other than the bit level, processing capability requirements on both the encoder and decoder side can be reduced. In accordance with one or more embodiments, a start code emulation prevention method looks for data patterns relative to fixed-size data portions larger than single bits. When a particular pattern is found, start code emulation prevention data is inserted to prevent start code emulation. The inserted data is larger than a single bit and, in some embodiments, comprises a byte. When a decoder decodes data that has had start code emulation prevention data inserted, it can easily identify legitimate start codes and then can remove the start code emulation prevention data to provide the original data that was protected.

Abstract: A method of shaping an orthogonal frequency division multiplexing (OFDM) signal spectrum is disclosed. The method comprises receiving an input signal that has a frequency spectrum that includes a frequency peak, and limiting the amplitude of the frequency peak to a predetermined clip level. An orthogonal frequency division multiplexing (OFDM) transmitter is disclosed. The OFDM transmitter comprises an input interface configured to receive an input signal that includes a frequency spectrum that includes a frequency peak, and a processor coupled to the input interface, configured to limit the amplitude of the frequency peak to a predetermined clip level.

Abstract: A method for receiving at a receiver having a variable filter a transmitted signal that includes a periodic training signal. The method includes (a) receiving and sampling the transmitted signal at the receiver to produce a digital complex baseband signal; (b) filtering the digital complex baseband signal with the variable filter; (c) detecting the periodic training signal in the filtered digital complex baseband signal; (d) determining a desired channel impulse response based on the detected periodic training signal; (e) calculating filter coefficients required by the variable filter to achieve the desired channel impulse response; and (f) adjusting the variable filter according to the calculated filter coefficients. A receiver for implementing the method is also provided.

Abstract: A wireless device generates a peak profile for a primary synchronization channel (PSCH), and has a synchronization stage for performing code group identification and scrambling code identification. A first peak from the peak profile is chosen. The first peak has a first path position. The synchronization stage is handed the first path position to obtain a first code group number and a first code number associated with the first peak. A multi-path search window is then opened in the peak profile around the first path position. A second peak within the multi-path search window is selected, and a verification procedure is performed on this second peak to determine if the second peak has a code number that is identical to the first code number. The first code group number is assigned to the second peak if the code number of the second peak is identical to the first code number.

Abstract: A method of synchronizing the information held in a switching database associated with a switching function of a data switching node, with a data network node identifier record associated with a management processor enabling a managed mode thereof is provided. An entry of the switching database is modified. A status specifier corresponding to the modified entry is set to signify the modification thereof. An inspection of the switching database is initiated on the expiration of an adjustable timer, and the information held in modified switching database entries is synchronized with the data network node identifier record. This method of synchronization of the information held in the switching database spreads out of burst changes thereof over time. The advantages are derived from the use of a more economical management processor while providing the same or enhanced levels of service of the data switching node.

Abstract: A system receives input data frames that are configured according to a SONET or an SDH standard. The input data is converted to parallel data. The system provides groups of bits along parallel signal lines. In each group of bits, N contiguous bits in the group form a complete word of input data. The system identifies the boundary between complete words in the input data by comparing subsets of the bits to predefined framing patterns. The system then aligns the input data based on the location of each word using the boundary information. The output data of the system includes data that is word aligned. The system can also detect boundaries between the frames.

Abstract: A correlation between a received signal and a sync word signal is calculated. A window signal having a time span which is equal to an equalization range for an adaptive equalizer is defined. A power sum of the correlation output signal in each of window signals #1, #2, #3, . . . are calculated by sequentially shifting the window signal in the time domain, and a rising edge of the particular window signal whose power sum maximum defines a symbol sync timing.

Abstract: The transportation system, such a airplane, which comprises the cabin, the internal antenna system, and the external antenna system. The voice data and the non-voice data of a plurality of passengers located in the cabin are received via the internal antenna system and transferred via the external antenna system. The TV data received via the external antenna system is distributed in the cabin.

Abstract: Systems and methods are disclosed for time synchronization of operations in a control system. Synchronization networks and devices are provided for transferring synchronization information between controllers in a distributed or localized control system, which is employed in order to allow operation of such controllers to be synchronized with respect to time. Also disclosed are synchronization protocols and hardware apparatus employed in synchronizing control operations in a control system.

Abstract: The frame synchronizing circuit establishes frame synchronization by detecting a sync pattern laid in an incoming frame. The frame synchronization circuit comprises a first frame synchronizing unit and a second frame synchronizing unit. The first and second synchronizing units synchronize with a first pattern, a second pattern at a first position and a second position, respectively. Thereafter, when the first position used for the synchronization by the first frame synchronizing unit is found to be in error, the first frame synchronizing unit synchronizes with the second pattern at the second position used by the second frame synchronization unit.

Abstract: An “identical beacons” field (401) is inserted near the beginning of a transmitted beacon (403) that contains either an integer equal to the number of consecutive identical beacons sent (i.e., identical to the one presently being transmitted) or a repetition bit indicating whether or not the beacon contains changed information when compared to a prior-sent beacon. After sleeping awhile, a node (302-304) wakes up, receives a first portion of the beacon containing the identical beacons field, and analyzes the identical beacons field. Based on the analysis, the node makes a decision on whether to remain “awake” for reception of the remaining beacon or to return to sleep.

Abstract: An apparatus for providing wireless transmission of information in electronic display systems and methods of using the same. In particular, the present invention is directed to an air interface and protocol to facilitate wireless transmission of information from a communication base station or other controlling device to individual electronic display modules.

Abstract: A method is provided for transmission of packets (102) as a sequence of data packets (104). A redundancy or check word (106) is composed for each packet of the sequence of data packets. A transmission packet is composed of a packet, a check word of a prior packet in the sequence of packets, and a check word of a subsequent packet in the sequence of packets. The transmission packets are transmitted in a sequence and received in a sequence. After reception, the transmission packets are separated so that the packets are compared with the corresponding check words transmitted with adjacent packets in the sequence.

Abstract: A method is provided for channel coding a parameter whose values are correlated with one another to different extents and according to which code words with better distance properties are at least partially associated with the more strongly correlated values of the parameters, and code words with weaker distance properties are at least partially associated with the more weakly correlated values of the parameter.

Abstract: A method and apparatus for estimating the timing position of data bursts received in a data stream, where each data burst includes a number of bits comprising a training sequence in a fixed location. The receiver includes circuitry for estimating the timing position of the data bursts received in the data stream. For each of the first N received data bursts, the receiver estimates a plurality of timing locations of the training sequence, correlates the training sequence for each estimated timing location, and determines the timing location associated with the highest correlation value. The receiver then determines the average timing location of the highest correlation values for each of the first N data bursts. For the next M data bursts the receiver estimates the timing location of each data burst based on the average timing location for the first N data bursts.

Abstract: The invention provides a method and system for accessing ports of a very high-speed, fixed-size cell switch fabric. It is aimed at permitting a tradeoff between the overall number of I/Os required to access all the switch ports, that must stay within the board and modules packaging constraints and the maximum speed at which each individual wire, making up ports, may be toggled while not violating any of the speed limitation imposed by the transmission medium (board wiring) or the module interface devices; i.e., receivers and drivers. This is achieved by eliminating the need of having extra control signals, thus, greatly easing the requirement for module and board I/Os. Then, synchronization is obtained from in-band information transported by fixed-size idle logical units from a robust protocol based on two CRCs. The acquisition of synchronization does not require any particular training sequence and is conducted by the receiving device component only which retrieves computed delimiters on which it locks.

Abstract: In this demodulation method, a receive signal is demodulated estimating the fading distortion of data by detecting the fading distortion of unique word as pilot signal inserted into multiple sections of the receive signal. The method has the steps of: comparing a unique word in the multiple sections of receive signal and a known unique word and thereby detecting the fading distortion of unique word in the multiple sections; calculating a spline interpolation curve based on the fading distortion of unique word in the multiple sections; estimating the fading distortion of data in the receive signal from the spline interpolation curve; and demodulating the data in the receive signal based on the fading distortion of the data.

Abstract: A data synchronizing method for a radio multi-terminal communications system including a cellular telephone and a PDA (Personal Data Assistant). Messages transmitted between the cellular telephone and the PDA are prioritized. The cellular telephone and the PDA interchange the message data according to the set priority order, thereby sharing the data with reduced data processing time. A radio multi-terminal communications system is also included which uses prioritized messages for sharing data.

Abstract: An ATM cell synchronization circuit can be realized by a circuit construction operable at low speed. Cell strings developed into eight parallel strings by a serial to parallel development circuit are further developed into 8n parallel strings. A frequency of a clock signal synchronous with bytes of the input cell string is divided into n by a frequency divider circuit for lowering speed to be 1/n. The parallel developed signals are rearranged by a shifted register into a signal string for detection by HEC (Header Error Control) detecting circuit. Then, an HEC byte is detected by the HEC detecting circuit. In order to detect the HEC bytes located at n positions, n in number of HEC detecting circuits are provided, At this time, the HEC byte after n cells becomes the same position. The interval of n cell is fifty-three. Therefore, a counter counting fifty-three is provided. Respectively predetermined values are detected by the decoders to generate detection signals.

Abstract: A method for handling underflow and overflow of data in a FIFO buffer includes steps of inserting an insert data word in the FIFO buffer if there is an underflow of data at the FIFO buffer and discarding a discard data word of the FIFO buffer if there is an overflow of data at the FIFO buffer. In one embodiment, the insert data word is null and does not change the status of the FIFO buffer.

Abstract: The amount of jitter that results in a serial receiver having a parallel architecture Can is reduced by insuring that the edges specifically introduced by the code are actually received by the phase detector. In particular, the code is designed to increase the probability that the edges it introduces are actually received by the phase detector. In a preferred embodiment of the invention, all the edges introduced by the code are actually received by the phase detector. This is achieved by guaranteeing that the edges introduced by the code are evenly spaced in the data stream at a rate corresponding to the phase detector sampling rate. For example, if the receiver consists of N data samplers, e.g., N=5, and one phase detector, the edges introduced by the code are arranged to be N symbols apart. This may be done by inserting as the Nth symbol an overall symbol that has a dummy component so that an edge results between the N-1 symbol and the overall Nth symbol.

Abstract: A synchronization method and apparatus for synchronizing a receiver, such as a radiotelephone operable in a cellular communication system with a transmitter. Synchronization sequences are transmitted as parts of a control signal to the receiver. The synchronization sequences are formed of either a dotting sequence or a set of m-sequences. Such synchronization sequences are of high margins and also permit synchronization of the user terminal responsive to a reduced number of calculations.

Abstract: A wireless telecommunications system (1) includes a central terminal (10) for transmitting and receiving radio frequency signals to and from a subscriber terminal (20). A downlink communication path is established from a transmitter (200) of the central terminal (10) to a receiver (202) of the subscriber terminal (20). A downlink signal (212) is transmitted from the transmitter (200) to the receiver (202) during setup and operation of the wireless telecommunications system (1) carrying information partitioned into a plurality of frames. The downlink signal (212) includes an overhead channel (224) having a frame alignment signal (232) for each frame of information. The receiver (202) monitors the downlink signal (212) to identify the frame alignment signal (232). The downlink communication path is established when the receiver (202) identifies two successive frame alignment signals (232).

Abstract: A method for frame synchronization including the detection of an n-bit pattern with predetermined characteristics in a bitstream is described. The subject method includes the steps of extracting a first set of m bits, with m being smaller than or equal to n, from a first position in said bitstream, deriving from said first set an address of a location in a first memory, deriving from the contents of said location in said first memory at least one second position in said bitstream and at least one second set of bits to be extracted therefrom until said n-bit pattern is detected in said bitstream. An apparatus for performing the subject method is additionally described.