Abstract: A system for bidirectional communication of digital data between a central unit and a remote unit wherein the need for tracking loops in the central unit has been eliminated. The central unit transmitter generates a master carrier and a master clock signal which are used to transmit downstream data to the remote units. The remote units recover the master carrier and master clock and synchronize local oscillators in each remote unit to these master carrier and master clock signals to generate reference carrier and clock signals for use by the remote unit receiver. These reference carrier and clock signals are also used by the remote unit transmitters to transmit upstream data to the central unit. The central unit receiver detects the phase difference between the reference carrier and clock signals from the remote units periodically and adjusts the phase of the master carrier and master clock signals for use by the central unit receiver to receive the upstream data.

Abstract: A system and method is disclosed for providing dynamic multimedia jitter buffer adjustment for packet-switched networks. The system temporarily stores an amount of incoming data, which is dynamically adjustable, for an amount of time before sending the data out in a more even stream. The system includes a decoder clock, a jitter buffer, a network jitter statistics collector, and a jitter buffer controller. The decoder clock indicates the arrival-time of the data at the system, while the network jitter statistics collector collects the playback-time of that data. By comparing the arrival-time and the playback-time, the jitter buffer controller determines whether the data arrived on schedule. Accordingly, the depth of the jitter buffer can be adjusted to accommodate the late or early arriving data.

Abstract: A method for synchronizing a timing device of a client station via a communications network is disclosed. A plurality of packets is sent from a time server to the client station via the communications network. Upon receipt of the plurality of packets at the client station a time indicative of a local time of receipt of the plurality of packets is determined and the plurality of packets are returned to the time server via the communications network. Upon receipt of the plurality of packets at the time server data in dependence upon round trip delay of the packets and variance in packet spacing are determined and compared to threshold values. If the determined data are within the threshold values data indicative of a time correction are determined and sent from the time server to the client station.

Abstract: An interleaved delay line for use in phase locked and delay locked loops is comprised of a first portion providing a variable amount of delay substantially independently of process, temperature and voltage (PVT) variations while a second portion, in series with the first portion, provides a variable amount of delay that substantially tracks changes in process, temperature, and voltage variations. By combining, or interleaving, the two types of delay, single and dual locked loops constructed using the present invention achieve a desired jitter performance under PVT variations, dynamically track the delay variations of one coarse tap without a large number of delay taps, and provide for quick and tight locking. Methods of operating delay lines and locked loops are also disclosed.

Abstract: A method for synchronizing a data exchange between a data source and a control device is provided. A synchronization request signal is first transmitted via the bus system to the data source, which then measures a signal propagation time from the control device to the data source. In the data source, a transmission delay time is set which is dependent on the measured signal propagation time. Data which are to be transmitted are delayed by the transmission delay time. A bus system for synchronizing a data exchange is also provided. After receiving a synchronization request signal, the data source measures signal propagation times and sets a transmission delay time in a transmission delay device on the basis of the measured signal propagation times.

Abstract: Since a multiplexed signal quality display system according to the present invention is provided with a memory means which stores measurement results obtained by measuring electric powers of signals present in all of channels within a band used and a display means which specifies a channel where the presence of a signal is predicted and which reads and displays the measured value of the specified channel, it is possible to display the waveform quality of a channel which is determined by desired Walsh code and Walsh code length.

Abstract: Methods, apparatuses and systems directed to measuring delay attributable to a network. The network delay is computed, in one implementation by determining a round-trip time for a network connection based on the arrival times of selected packets transmitted by first and second endpoints to establish the network connection, measuring the time gaps between consecutively increasing data packets in an ordered packet stream associated with a transaction, comparing the measured time gaps to the round-trip time, and computing a network delay for the transaction by adding the round-trip time to the measured time gaps that exceed the round trip time.

Abstract: A method and system for allocating an initial maintenance request (IMR) for an upstream channel in a communications system, wherein the communication system includes a headend and at least one remote device associated with the channel. A first propagation delay from the headend to the remote device having the greatest delay is determined. Likewise, a second propagation delay from the headend to the remote device experiencing the least delay is determined. The IMR is then defined to be shorter than the first propagation delay and at least as long as the difference between the two propagation delays. The starting point of the IMR is established by modifying the clock output of the headend. A modification value is added to the headend clock output. The modification value corresponds to a time interval that can be as long as the propagation delay from the headend to the remote having the shortest delay.

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: In a CDMA reception apparatus, averaging part for averaging at least one of vector, amplitude and power of received signal of a plurality of transmit power control sections is provided. Further, propagation path variation estimator for estimating a propagation path variation of the present transmit power control section from respective transmit power control sections in the past to obtain a propagation path variation estimation value and propagation path variation correction part (multiplier) for correcting by the propagation path variation estimation value are further provided, wherein the averaging part averages at least one of vector, amplitude and power of received signal of the plurality of transmit power control sections corrected by the propagation path variation correction part (multiplier). With this configuration, the measurement accuracy is improved by measuring received signal power using a plurality of slots including past slots, resulting in more accurate transmit power control.

Abstract: A TDMA radio terminal comprises a transmitter portion and a receiver portion. A reference signal is launched in the transmitter portion while tuning the receiver portion. At the same time, an internal delay counter is started. The counter counts clock pulses till the reference signal returns through the receiver portion. Letting this pulse count be Nd, a transmission wait time is Nt?Nd. Nt is a transmit timing at the antenna. The Nd counting operation may be triggered by a power on or a signal from a controller. Method for determining the transmission wait time in the production site is also disclosed.

Abstract: A communication apparatus that shares precise return channel uplink timing information includes a common symbol timing reference and one or more control stations that each transmit independent asynchronous DVB data streams which evenly share the common symbol timing. The control stations each include respective delay trackers to determine broadcast transmission delays associated with the particular control station and transmission path. Each broadcast data stream includes the same non real-time frame marker and a transmission delay message particular to the respective control station. A remote receiver receives one of the broadcast streams and timestamps the non real-time frame marker with a local time of receipt. A timing recovery circuit determines an upcoming return channel frame start time by adjusting the local time of receipt by the particular broadcast transmission delay and a unique receiver offset time.

Abstract: Communication between a burst manager and plural remote terminals over a first passive optical network (PON) and a second PON, with each PON having a downstream portion and an upstream portion, includes transmitting a common synchronization signal from the burst manager to the plural remote terminals over both downstream PON portions and transmitting burst data from the plural remote terminals over both upstream PON portions to the burst manager. The burst data for each remote terminal is delayed on the first and second PONs by corresponding first and second delays.

Abstract: A communications system and method for self-regulating quality of service in a communications network are provided which includes measuring the amount of jitter of a first media stream received in a router, comparing the amount of jitter of the first media stream received in the router to the amount of jitter of at least one other media stream received in the router and prioritizing the timing of the transmission of a packet in the first media stream from the router based at least in part on the results of the comparing step.

Abstract: Disclosed is a mobile communication system including a network constituted of at least one switching center and a plurality of base stations, and a mobile station which communicates with the base stations simultaneously. The system permits varying transmission delay between the switching center and the base stations according to the type of services available to the mobile station. The object of the present invention is to propose a communication which permits varying transmission delay according to the type of service currently employed, and to promptly recover a synchronization state even if an out-of-sync state happens. To attain the object, a memory means (mobile switching center processor 32) stores transmission delay characteristics corresponding to services which are available to the mobile station.

Abstract: A method and apparatus for recording digital data streams. When a digital broadcast data stream received by a set top box is transmitted through a communication interface such as an IEEE-1394 bus to a streamer, program clock references contained in the data stream become different from the actual arrival time of the digital data stream because of different clock frequencies of the digital data stream and communication interface. The difference is compensated before the digital data stream is recorded on the streamer. The method in accordance with the present invention comprises detecting program clock references contained in received digital transport stream packets, creating the transport time reference of each transport stream packet based upon the detected program clock references and arrival times of the transport stream packets, and creating transport stream units by adding each of the created transport time reference to the associated transport stream packet.

Abstract: Real-time communication of multimedia data over heterogeneous networks that may include constant delay networks, variable delay networks that have a common reckoning of time, and variable delay networks that do not have a common reckoning of time. If there are any variable delay networks in which there is no common reckoning of time in the heterogeneous networks, a common reckoning of time is established in each of those networks. Then, a constant delay network is emulated for each variable delay network using the specific common time reckoning present in each variable delay network.

Abstract: A terminal device is provided for communicating data signals with a central communication device via a first signal carrying line and a second signal carrying line. The first signal carrying line is arranged for transporting a first signal and the second signal carrying line is arranged for transporting a second signal, wherein the first and second signals have equal content. The first signal carrying line has a first propagation time and the second signal carrying line has a second propagation time, such that the first propagation time is shorter than the second propagation time. The terminal device includes a signal quality comparison element for determining a first signal quality of the first signal and a second signal quality of the second signal, for comparing the first and second signal qualities, and for accepting the one of the first and second signals that has a better quality.

Abstract: Transmission delay in a serial bus connected network is determined by transmitting a Ping packet which is replied to in a physical layer of the bus from a request node to a response node, and measuring the time required from transmission of Ping packet by the request node until a Self—ID packet corresponding to the Ping packet is returned to the request node. The delay deviation between cycle timers of the request node and the response node is compensated by this transmission delay. The delay deviation may be also compensated using a time stamp.

Abstract: A method, apparatus and system detects a loss of synchronization between a transmitter and a receiver in a multiple-carrier communication system such as an OFDM system. A phase-frequency synchronization detector determines when the receiver has lost synchronization with the transmitter based on a phase-frequency relationship of plurality of pilot signals transmitted at different frequencies from the transmitter and received at the receiver. A loss of synchronization is detected when a slope of a line defined by the phase-frequency relationship exceeds a timing threshold more at a rate in excess of an occurrence threshold within a time period.

Abstract: A method and system for determining a relative location of a device on a network is provided. In this system and method, a list of landmark nodes provided on the network is received. Then, a value which is a time, a latency and/or a distance from the device to each of the landmark nodes is determined. Each of the determined values corresponding to the respective node of the landmark nodes is transmitted to a central arrangement to provide the relative location of the device with respect to the landmark nodes.

Abstract: A signal delay circuit that compensates for other delays introduced within the signal delay circuit itself. A delay-locked loop may produce multiple delayed clock signals, each having a defined phase difference with respect to, and representing a different delay from, a reference clock. A synchronization circuit may determine a first selection value that selects a first delayed clock whose delay compensates for the propagation delays created in a selection circuit. A selection circuit may add a specified offset value to the first selection value to produce a second selection value, and use the second selection value to select a second delayed clock whose delay approximates the sum of the internal delay of the selection circuit and the delay specified by the offset value.

Abstract: A data transfer system makes more effective use of a band available for the data transfer. In data transfer systems having devices with a different delay time in sending back the data depending on the transfer rate of data, it is possible to make more effective use of the band available for the transfer by transferring predetermined data at a slowest transfer rate within the data transfer system.

Abstract: A method and device for determining a parameter (RTO) associated with a retransmission time-out feature in a data unit transmitter implementing a protocol (TCP) that provides an acknowledgment feature and a retransmission time-out feature, where according to one aspect decreasing values of the round trip time (RTT) are treated differently with respect to their influence on a mean deviation parameter (RTTVAR) than increasing values of the round trip time, where according to another aspect weight values (g, h, w) used in the determination of the parameter (RTO) are chosen such that at least one of them is time variable, and where according to a further aspect the parameter (RTO) is also calculated on the basis of a value (SR) indicative of the number of spurious time-outs in the communication.

Abstract: A base station for compensating a fixed route delay between a base station and a mobile station of a CDMA mobile communication system and an operation method thereof are disclosed.

Abstract: An interleaved delay line for use in phase locked and delay locked loops is comprised of a first portion providing a variable amount of delay substantially independently of process, temperature and voltage (PVT) variations while a second portion, in series with the first portion, provides a variable amount of delay that substantially tracks changes in process, temperature, and voltage variations. By combining, or interleaving, the two types of delay, single and dual locked loops constructed using the present invention achieve a desired jitter performance under PVT variations, dynamically track the delay variations of one coarse tap without a large number of delay taps, and provide for quick and tight locking. Methods of operating delay lines and locked loops are also disclosed.

Abstract: In an improved system for receiving digital voice signals from a data network, a jitter buffer manager monitors packet arrival times, determines a time varying transit delay variation parameter and adaptively controls jitter buffer size in response to the variation parameter. A speed control module responds to a control signal from the jitter buffer manager by modifying the rate of data consumption from the jitter buffer, to compensate for changes in buffer size, preferably in a manner which maintains audio output with acceptable, natural human speech characteristics. Preferably, the manager also calculates average packet delay and controls the speed control module to adaptively align the jitter buffer's center with the average packet delay time.

Abstract: A system and method is disclosed for providing dynamic multimedia jitter buffer adjustment for packet-switched networks. The system temporarily stores an amount of incoming data, which is dynamically adjustable, for an amount of time before sending the data out in a more even stream. The system includes a decoder clock, a jitter buffer, a network jitter statistics collector, and a jitter buffer controller. The decoder clock indicates the arrival-time of the data at the system, while the network jitter statistics collector collects the playback-time of that data. By comparing the arrival-time and the playback-time, the jitter buffer controller determines whether the data arrived on schedule. Accordingly, the depth of the jitter buffer can be adjusted to accommodate the late or early arriving data.

Abstract: A method for calibrating a propagation delay in a network trunk includes the step of calculating a time period Ti in a first network switch between sending a marker and receiving a trunk package acknowledgement marker from the second network switch, and a time period Tt in the second switch between receiving the trunk package and the marker and transmitting an acknowledgement marker containing the trunk package back to the first switch, the second switch appending the time period Tt to the acknowledgement marker before sending it back to the first switch. The time gap is read and a time delay caused by sending the trunk package on each channel is calculated. The second switch decodes the received trunk package and calibrates the propagation delay based on the time delay to determine a time gap between the packages in the same channel.

Abstract: A system for supporting security and mobility management of wireless communications to multiple wireless transmit/receive units (WTRUs) includes a first database having a listing of each of the WTRUs along with their capabilities, and a second database having a listing of the location of each of the WTRUs. The second database has at least one subgroup which corresponds to at least two WTRUs which are co-located. The WTRUs in the subgroup are treated as a single WTRU for security and mobility management.

Abstract: Disclosed is a reception apparatus employing a post-descrambling scheme in a mobile communication system for code division multiple access and provides methods which are used for channel-compensating received multi-path signals, sorting the channel-compensation signals according to positions in time in consideration of multi-path latency, combining the sorted signals, and descrambling each of the combined signals by means of one of preset scrambling codes in a reception apparatus of Code Division Multiple Access (CDMA) mobile communication system.

Abstract: The invention relates to a method for synchronizing nodes of a communication system comprising the following steps: receipt of a first synchronization message by a first node, whereby the first synchronization message contains a desired receipt time by a first node; correction of a time base of the first node, based on a deviation between an actual receipt time, determined as a result of the base time, and the desired receipt time.

Abstract: The invention relates to a method for determining the propagation delay in a packet-based network for a packet-based network section of a connection between terminals, at least sections of the connection being routed via the packet-based network. According to the inventive method, the broadcast relay in the packet-based network is determined for the packet-based network section of the connection and substantially half of the time period that has been determined for the broadcast relay is taken as a value for the propagation delay of the packet-based network section. The method permits the determination of the propagation delay in the packet-based network. This parameter can help, for example, to determine whether an echo compensation is required during a voice connection.

Abstract: The invention relates to a communication system comprising a plurality of interactive terminals which communicate with a master station via a transmission medium. The invention is particularly applied to interactive satellite broadcast systems. The invention relates to a request mechanism permitting the interactive terminals to have reservations assigned to them on the transmission medium for transmitting information to the master station. When a terminal receives assignments that have not yet expired, it temporarily stores them in an assignment memory. The invention comprises taking the number of assignments contained in this memory into account when a new request is transmitted. It thus permits to avoid that requests for the assignments that have already been granted are formulated again.

Abstract: Methods for determining delay offsets of communication systems arc provided. One such method comprises: determining components of a propagation path of a base station of a communication network; determining a propagation delay associated with each of the components; and determining a delay of the propagation path using the delays of the components. Systems also are provided.

Abstract: In a method of controlling a frequency via an asynchronous transmission network, signals received at the output of the asynchronous transmission network have been clocked at a reference frequency and transmitted by the network with respective varying transit delays and the frequency of a local clock is slaved to the reference frequency by means of an error signal formed from selected received signals with minimal transit delays. Applications include local mobile telephone networks.

Abstract: An improved tracking system, illustrated as a delayed lock loop. The time intervals of a communication signal are tracked by first sampling the communication signal. A standard and a sample, advanced relative to each other by i sample positions from a sample position representing an assumed arrival position ta of a time interval, are correlated over a correlating length of k samples. Also, the standard and a sample retarded relative to each other by the i sample positions from the assumed arrival time ta are also correlated over k samples. A timing error is determined from the correlations. A predication of the arrival time tp of the next interval is determined from the error. One or more of the correlation length k or the i sample position is modified based on the predicated arrival time tp. The process is repeated using any of the modified correlation length k and/or sample position i. The timing error may also be used for descrambling and despreading.

Abstract: In an audio transmission apparatus used in an asynchronous communication network, a receiving buffer stores temporarily an audio packet received in a network interface section. This audio data is decoded in an audio decoder, and is passed through a D/A converting speed changer, and the digital audio data is converted into analog in a D/A converter. Concurrently, in a delay time fluctuation measuring section, the delay time fluctuation of audio packet received is measured in the network interface section, and a buffer controller determines the data storage amount of the receiving buffer on the basis of this delay time fluctuation. Accordingly, the buffer controller changes the D/A converting speed on the basis of the delay time fluctuation, thereby adjusting the audio data flow from the receiving buffer. Accordingly, a real-time audio transmission apparatus capable of avoiding lack of audio data in the buffer and reproducing audio continuously is presented.

Abstract: In a discrete tone system, a base station receives a transmission burst from a remote unit being installed that includes delay compensation pilot tones that are uniformly spread throughout the transmission bandwidth. The arrival time transmission burst is not synchronized with the other remote units transmitting to the base station. The base station measures the phase delay of each tone and calculates the delay of the remote unit from the slope of the line of phase angle versus tone frequency. The base station transmits a signal to the remote unit that includes the magnitude and direction of the delay, which allows the remote unit to adapt the timing of its transmission to be synchronized with the other remote units.

Abstract: Calibrating return time includes determining clock calibration information based on clock signals local to a master device and return clock signals corresponding to each of at least two slave devices, storing clock calibration information with respect to each of the slave devices with which the master device will communicate using a bus, and, after the clock calibration information has been stored, resynchronizing data signals that are received from each of the slave devices based on the corresponding stored clock calibration information.

Abstract: This invention enables the digital broadcast receiving section to restore the reception timing even in a system incapable of guaranteeing the real-time feature of digital broadcast data as far as the 1394 Link. The digital broadcast signal received by the RF section and tuner section is restored to ATM cells at the packeting section. The ATM cells are then sent to the time stamp adding section, which adds the arrival time to the ATM cells. The CPU extracts, as a time stamp, the arrival time of the first ATM cell in each transport packet and creates a 4-byte source packet header on the basis of the value of the arrival time and the value of the CTR in the 1394 Link.

Abstract: A system for optimally mapping circuits into packets based on round trip delay (RTD), and a system for measuring RTD for use in packet communications systems such as circuit emulation (CEM) systems is disclosed. The measured RTD value can be used in a system that adjusts packet size to reduce capture delay to partially offset an increase in RTD. As the use of smaller packets increases the overhead burden on the packet communication system, the packet size can be increased to reduce the overhead burden when the size of the current RTD becomes appropriately short. The disclosure also teaches the placement of data from two or more circuits destined for the same emulation endpoint into the same transmission packet in order to improve system performance. The abstract is a tool for finding relevant disclosures and not a limitation on the scope of the claims.

Abstract: Network delay is determined in order to synchronize a clock in a mobile station with a reference clock. Tones are generated that represent a sequence of bits in a synchronization flag. The tones are sampled beginning at a selected sample start time. The sampled tones are demodulated to identify the bit values in the synchronization flag. The demodulator is synchronized with the sampled tones in the synchronization flag by shifting the sample start time until the samples generate an optimum synchronization value. A reference time is then identified according to the optimum sample start time.

Abstract: In order to predictively time stamp isochronous data packets transmitted over an IEEE 1394-1995 serial bus network, an application, which is to send a stream of isochronous data packets to a receiving node, first transmits a number of dummy frames each consisting of a number of packets. Preferably, these isochronous data packets make up frames of video data. From these dummy packets, the application obtains the time stamp values within the common isochronous packet (CIP) header of each packet. Using these obtained time stamp values, the application calculates a presentation time value for each data frame to be transmitted. The obtained time stamp value from a transmitted video frame is used to calculate the presentation time for a video frame which is a number of frames ahead within the transmit queue.

Abstract: Propagation delay compensation in a wireless network comprising a central access point and multiple subscriber terminals is achieved by defining a registration time slot in which new subscriber terminals must first transmit network registration signals to the access point. The subscriber terminals by default transmit at the start of the time slot, and the access point times the delay from the start of the slot to the receipt of the subscriber terminal registration request, and then transmits this information back to the subscriber terminal. In all subsequent transmissions the subscriber terminal uses this information to delay its transmissions to compensate for differences in signal propagation delay between each subscriber terminal.

Abstract: A system and method in a digital TDMA telecommunication system for evaluating time slot offsets of asynchronously operating transmitters. The transmitters are equipped to receive a common reference clock signal, whereupon the value of the reference clock signal is recorded at transmission of specific time slots. The transmitters then perform a modulo operation on the recorded time and reports the result to a controlling node. Results of the modulo operation may then be compared with similar results reported by other transmission sources to the controlling node to determine relative time slot offsets between the transmission sources.

Abstract: In a computer network, the bandwidth of the communication channel connecting nodes of the network is limited. A cost function is used to allocate the bandwidth of the channel among the data for a plurality of elements in a multimedia session. The cost function relates the distortion produced by a change in encoding rate for one or more media with a delay in transferring data related to another medium at a particular rate. A fairness criterion, expressing the relative weighting of the distorted and delayed elements for specific applications, can be included in the cost function. The cost function can be used to allocate the bandwidth between media from both push and pull sources.

Abstract: Computers that exchange data over communication networks frequently wait for responses to messages and therefor use timers to control the amount of time that the computer will wait for a response to a command issued over a network. Communication network responsiveness varies as traffic loading on the network changes. Fixed-value timers that don't take network loading into account can inadvertently terminate communications if a response is not timely received. Varying or adjusting data communication timers according to data network responsiveness can prevent erroneous data communication session termination.

Abstract: A new algorithm for clock offset estimation for resources distributed across a network (such as the Internet). By exchanging a sequence of time-stamped messages between pairs of network nodes and separately estimating variable delays for each message direction, present inventive embodiments provide more accurate estimates for clock offset between node pairs. Present inventive algorithms operate in a variety of peer and server network configurations while providing significant improvement in convergence speed and accuracy.

Abstract: A telephony system 10 having automatic timing adjustment for diverse routing of HFC systems has a signal stream routing through a signal line loop between a head-end 120 and at least one communication unit 16, i.e., a cable modem cable access unit (CAU). If a fault occurs within the signal line loop, recognized by the head-end 120 when a short uplink burst from the communication unit 16 does not align within a predetermined timing window based on a value in the database, the head-end will adjust the cycle through predetermined delay parameters, corresponding to various alternate signal line loops made up of redundant signal lines. An information processor is provided at the head-end 120 of the HFC system 10 for automatically adjusting the timing of the signal stream in order to maintain the database determined at the information processor at the head-end 120. The timing adjustment of the signal stream is communicated between the head-end 120 and the communication units, CAUs 16.