Abstract: A guard time reducing system and a method thereof for realizing a guard time that each packet is near each other in time without overlapping each other. A GPS timing unit finds the propagation passed time from a static orbit communication satellite to an earth station and a packetizing unit transmits a packet as fast as the propagation passed time than the UTC time when the packetizing unit transmits the packet to the static orbit communication satellite. According to the method, it is possible to maximize the use efficiency of the communication channel from the earth station to the static orbit communication satellite because respective earth station transmits data in each time period allocated thereto without overlapping each time period.

Abstract: Jitter of a Program Clock Reference (PCR) in a transport stream of an Moving Picture Experts Group (MPEG) signal transmitted over Asynchronous Transfer Mode (ATM) system is reduced by correcting PCR to PCR−(T−&dgr;) if |PCR−STC|>T−&dgr;−&Dgr; is true and (PCR−STC)>0, correcting PCR to PCR+(T−&dgr;) if |PCR−STC|>T−&dgr;−&Dgr; is true and (PCR−STC)<0, and making no correction if −PCR−STC−>T−&dgr;−&Dgr; is false. The program clock reference received is represented by PCR, a system time clock at the time when the program clock reference is received is represented by STC, a period of a transport stream packet at an output terminal of an MPEG encoder is represented by T, a packet transmission time of the transport stream packet at an input terminal of the apparatus is represented by &dgr;, and a tolerable range is represented by &Dgr;.

Abstract: A multi-carrier transmission system, such as a DMT system. A receiver must be able to recover a sampling clock that is very accurately synchronized to a transmitter sampling clock. Typically, synchronization is achieved by using a reserved carrier, the pilot carrier, which is transmitted with a fixed phase. The receiver sampling clock is then phase locked to the pilot carrier. Frame timing can be recovered by using a correlation technique. Thus an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier is provided.

Abstract: To synchronize clock signals in spatially distributed nodes in a large, synchronous electronic, optical, optoelectronic or wireless system, a master node generates two identical pulse trains and propagates them to a plurality of slave nodes via first and second propagation channels, respectively, so that a pair of pulses, one from each pulse train, arrive at each slave node simultaneously, travelling in opposite directions. Each slave node generates a clock signal event when the pair of pulses arrive substantially simultaneous. When the pulses in the two channels do not arrive simultaneously, the slave node adjusts delays in each propagation channel so as to adjust arrival times of subsequent pairs of pulses. The delays may comprise pre-delays upstream of the detection point and post-delays downstream of the detection point, any increment in a pre-delay being compensated by an equal decrement in the post-delay in the same propagation channel.

Abstract: A method of controlling data sampling clocking of asynchronous network nodes, each asynchronous network node having a local clock and transmitting and receiving packets to and from an asynchronous network according to an asynchronous network media access protocol. An asynchronous network node capable of transmitting and receiving packets on the asynchronous network is designated as a master node. Each non-master asynchronous network node which desires to synchronously transport packets across the asynchronous network is designated as a slave node. A master node clock of the master node is synchronized with a slave node clock of each slave node. Each slave node clock is continuously corrected compared with the master node clock to smooth slave clock error to an average of zero compared with the master clock as a reference using timestamp information from the master node.

Abstract: Transmitting data packets received from a non-constant delay medium includes storing the data packets in a buffer, determining a play-out schedule for the data packets based on timing information in the data packets, and transmitting the data packets from the buffer in accordance with the play-out schedule. Two of the data packets may contain time-stamps and the play-out schedule may be determined based on a difference between the time-stamps.

Abstract: A system for time-stamping a data packet associated with a data network allows software applications, running on non-deterministic systems, to determine the precise time that packets were transmitted to or received from a physical network interface. The system includes a network media interface device for transferring a data packet to or from a network medium, and a time source for generating and maintaining a time code. The system further includes a time-stamping circuit for sampling a time code from the time source when the interface device transfers the data packet to or from the network medium, and for associating the time code with the receive data packet so as to form a time-stamped packet.

Abstract: A system for time-stamping a data packet associated with a data network includes a network media interface device for transferring a data packet to a network medium, and a time source for generating and maintaining a time code. The system further includes a time-stamping circuit for sampling the time code from the time source when the data packet is available to be transferred to the network medium so as to acquire an outgoing time code. The time-stamping circuit also embeds the outgoing time code into a predetermined field in the data packet. The time-stamping circuit also provides the data packet with the embedded outgoing time code to the interface device, and the interface device subsequently transfers the data packet to the network medium.

Abstract: The invention relates to a protective device for a clean robot that includes a base 7 in which actuators 4 and 5 for driving a robot arm 3 are accommodated; a translational guide 8 for causing the base 7 to travel in a rectilinear direction; and a robot controller 10 that drives and controls the drive motor 4A and 5A of the robot arm 3 and an actuator 9 of the translational guide 8; wherein the protective device further includes acceleration sensors 11, which are disposed in the base 7 and are provided in respective axes so that they can detect an impact, when the clean robot 1 interferes with a surrounding substance, as vibration acceleration in the three-dimensional directions; an interference detecting device 13 that outputs a pulse when the detection signals of the acceleration sensors 11 of the respective axes exceed the threshold values that will become standards; and the first AND circuit that converts signals outputted from the interference detection means of the respective axes to interference signal

Abstract: A method and an apparatus provide for controlled access to a shared communication medium. Time slots on a forward channel include information regarding status useful for remote units to determine whether a reverse channel is available for seizure. Additionally, information along the forward channel provides guidance to the remote units to control attempts to seize the reverse channel. In one embodiment a remote unit divides a data package into a plurality of portions and attempts to seize the reverse channel using a single portion of the data package which corresponds to one time slot on the reverse channel. It then waits until it receives notification along the forward channel that the first data portion was successfully received before it attempts to send any of the remainder of its data in consecutive time slots on the reverse channel.

Abstract: A method for extending a cell radius or access range of a base station without incurring ASIC correlator re-design. This is accomplished using a modified timing protocol that will cause signals transmitted by mobile-telephones positioned beyond the limitations of the ASIC correlator bit limitation to be received within a search window so the signals may be detected and demodulated. In one embodiment, the modified timing protocol incorporates a timing advance technique in which the base station transmits its signals at an advanced time before frame boundaries such that signals transmitted by out-of-range mobile-telephones can be received within a search window beginning at a frame boundary and spanning a time interval corresponding to the ASIC correlator bit limitation. In another embodiment, the modified timing protocol incorporates a shifted search window that begins at an advanced time after a frame boundary and spans a time interval corresponding to the ASIC correlator bit limitation.

Abstract: In a method for reducing latency in packet telephony caused by anti-jitter buffering, audio data elements are received and placed in a telephony input buffer used for anti-jitter buffering. Rather than wait until the buffer is full, the audio data elements are clocked, or played, out of the buffer at a rate slower than the normal play rate. In this way, latency due to the initial buffer fill period is reduced or eliminated. Audio data elements continue to be played out at a slower than normal rate until the buffer fill level reaches a threshold. At that time, the play rate for sending data elements out of the telephony input buffer is adjusted to the normal play rate. In an alternative embodiment of the present invention, the fill level of the telephony input buffer is controlled within a desired range by speeding up or slowing down the rate at which audio data elements are played out of the telephony input buffer.

Abstract: A method for timing correction in a communications receiver includes the steps of (a) setting a timer to a known value; (b) defining a first window by defining a first rollover value; (c) defining a second window by defining a second rollover value; (d) defining a first receive gate transition relative to the first rollover value; (e) defining a second receive gate transition relative to the second rollover value; (f) starting the timer; (g) receiving a first receive burst in the first window; (h) receiving a second receive burst in the second window; (i) if a first receive burst is received after the first receive gate transition, increasing the second rollover value, and decreasing the first rollover value by an equal amount; (j) if the first receive burst is received before the first receive gate transition, decreasing the second rollover value, and increasing the first rollover value by an equal amount; (k) if the second receive burst is received after the second receive gate transition, increasing the fi

Abstract: A timing system for distributing a timing signal includes a master timing system that receives a network timing reference. The master timing system generates a master timing signal from the network timing reference. A distributed services node timing system receives the master timing signal and embeds a timing signal into a data transmission frame. A network interface island receives the data transmission frame and retrieves the embedded timing signal therefrom.

Abstract: The test unit delays its transmission of a reverse-link signal over the hard-wire connection to a base station by a specified transmission delay in order to ensure that the reverse-link signal is received at the base station within the base station search window. The present invention is especially useful in configurations in which the base station advances the timing of its forward-link signals to account for delay between the base station and its antennas and where there is a relatively large distance between the base station and its antennas. In such a configuration, without the transmission delay of the present invention, a reverse-link signal transmitted by a test unit over the hard-wire connection to the base station may arrive at the base station before the start of the base station search window, in which case, the test unit would not be able to initiate or maintain communications with the base station.

Abstract: A method using a Reflective Timing Signal to automatically adjust the timing parameters of an asynchronous bus to compensate for its physical extension.

Abstract: A method and apparatus for synchronizing to a time structure associated with base station transmissions in a radiocommunication system are described. A broadcast control channel can contain synchronization symbols within one or more of a plurality of timeslots. The symbols can be provided as periodic, e.g., exponential, signals which introduce a frequency deviation into the broadcast control channel. This frequency deviation can be recognized by the receiver to synchronize to the time structure of the base station transmissions. Moreover, the variation in the frequency deviation caused by phase rotation associated with local oscillator inaccuracy can also be compensated to achieve frequency synchronization.

Abstract: A method and system are provided for remultiplexing program bearing data. The remultiplexing method and system are applicable to MPEG-2 compliant transport streams carrying video programs. A descriptor based system is used for scheduling the timely output of transport packets wherein each descriptor records a dispatch time as well as a receipt time for each transport packet. The receipt time is used for estimating program clock reference adjustments, but final program clock reference adjustment is performed in hardware in relation to the precise output timing of each transport packets. A descriptor and transport packet caching technique is used for decoupling the synchronous receipt and transmission of transport packets from any asynchronous processing performed thereon. The descriptors can also be used for managing scrambling and descrambling control words (encryption and decryption keys). Remultiplexing functions may be distributed across a network.

Abstract: A method and system that enables an automatic delay setting within a wireless local loop system. The present invention determines the transmission distance time delay existing between a base station and a personal station by employing the communication interface that is utilized between them. The main reason for determining the transmission time delay caused by large transmission distances (e.g., over 300 meters) existing between base stations and personal stations is to compensate for it. Once the transmission distance time delay is known, the personal station utilizes that value to compensate for it. Specifically, the present invention directs a base station to transmit a control signal to a personal station. The personal station receives the control signal and transmits a signal to the base station. The base station determines if it started to receive the signal from the personal station later than it expected the signal to arrive, assuming close proximity of the two stations.

Abstract: A line interface controlling unit terminates a synchronous digital interface. A bandwidth controlling unit generates a timing signal for specifying respective timings of a plurality of time slot groups (TS groups) in order to divide a plurality of time slots structuring the interface into the plurality of time slot groups. Division specification of the TS groups is made from a controlling device. A plurality of cell mapping controlling units identify each of the TS groups in the interface based on the timing signal, and map data streams of asynchronous fixed-length cells, which respectively belong to a plurality of communication device interfaces, onto each of the identified TS groups, for example, via a communication device interface controlling unit.

Abstract: A method for maintaining synchronization between a base transceiver station (BTS) and an interworking function (IWF) within a cellular communications network is disclosed. The method utilizes a synchronization procedure between the IWF and the BTS that makes the IWF aware of propagation delays between the IWF and BTS. The IWF utilizes this information to adapt to the delays such that the correct sequence is unpacked uplink when obtained from the base transceiver station. The IWF also uses synchronization data to control transmissions from the IWF to the BTS such that frame numbers and timeslots are received at the BTS in the correct sequence.

Abstract: A process for the transmission of data packets from mobile stations to base stations in mobile radio systems operated by the time-division multiplex method where an effective utilization of resources and a reduced amount of signalling is achieved in the transmission of such data packets by the fact that the determination of the timing advance for the time of sending of the mobile station is linked to the satisfying of decision criteria with respect to the period of time between timing advance determinations. This period of time can be made relatively generous by transmitting the data packets with a short guard time.

Abstract: A method is disclosed for traffic policing in packet-based, broadband networks, such as ATM networks. The method comprises the steps of monitoring the arrival of incoming cells, and advancing a reference clock on a step of I if an arrival is late but not later than I, where I is an increment, and if an arrival is later than I assuming a new busy period and setting the reference clock at the arrival time.

Abstract: The invention substantially reduces the occurrence of unnecessary synchronization rearrangements in nodes within synchronous transmission systems such as SONET networks. In one embodiment of the invention, the method disclosed for reducing synchronization rearrangements within interconnected nodes of a synchronous transmission system includes the steps of: detecting, at a node within the synchronous transmission system, a change in a synchronization status message received at the node; propagating the changed synchronization status message from the node to another node within the synchronous transmission system if the changed synchronization status message corresponds to an active timing reference; waiting a specified amount of time upon detection of the change in the synchronization status message; then determining whether a synchronization rearrangement is necessary at the node; and then performing a synchronization rearrangement at the node if necessary.

Abstract: Packet production by a digital signal processor (DSP) is synchronized with modem transmission opportunities in a cable network. The cable modem computes the average waiting time a packet spends waiting to be transmitted by the modem. The DSP re-syncs transfer of packets to the modem by using this average waiting time minus a small amount sufficient to account for the maximum anticipated propagation delay, as the amount to delay the transmission of its next packet to the cable modem. This invention is a mechanism for re-synchronization that is largely independent of any propagation delays inherent in the hardware architecture.

Abstract: A method of clock recovery from a fast packet switched asynchronous network wherein a time stamp is transmitted over a network that has variable delay, involves maintaining an input counter at a sending device. The counter has a value dependent on an input clock. The value of the input counter is periodically transmitted over the network to a receiving device. A local counter at a receiving device has a value dependent on a local clock. The received value sample x.sub.i is compared with the local sample y.sub.i to derive the difference e.sub.i. The local clock frequency f.sub.j is adjusted such that the average of Emin.sub.j, where Emin.sub.j is the minimum of a block of error samples e.sub.i, remains close to a predetermined value, preferably zero. The clock recovery method is particularly suitable for MPEG2 video transmitted over ATM.

Abstract: A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satellite link, local or wide area network, wireless including cellur network or some combination of these media using suitable interface circuitry. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise.

Abstract: A method for synchronizing a cycle master node to a cycle slave node, including the steps of utilizing logic circuitry in the cycle slave node to determine a timer offset value, in response to the cycle slave node receiving synchronization information, transmitting the timer offset value to the cycle master node, and, utilizing logic circuitry in the cycle master node to adjust a value of a cycle master node cycle timer on the basis of the timer offset value. The synchronization information is preferably a cycle reset signal that is asserted at a prescribed rate which is a multiple of one cycle of the cycle slave node cycle timer. The cycle master node and the cycle slave node can advantageously be included in a first network or sub-network and the cycle reset signal can be supplied by a second network or sub-network which is external to the first network or sub-network.

Abstract: In each low-rate interface 1, a clock/frame pulse signal 16 is separated from a signal 11 outputted from a high-rate interface and coupled through a phase controller 6 for clock substitution in a clock substituting circuit 5. The phase controller 6 sets a phase delay as a result of design when making evaluation such that the phase of a signal 13 inputted to an exchanger 7 is coincident with the phase of its output signal 12. Thus simplifying the clock supply to low-rate interfaces in a multiplex transmission system, in which housings of a high-rate interface and the low-rate interfaces are physically separate from one another.

Abstract: In a digital communications system for transmitting and receiving digital data over a CSMA-type network having a source for transmitting a source signal comprising a synchronization interval and a data interval and at least one receiver for receiving a second signal having a second synchronization interval and a second data interval corresponding to the data interval of the source signal, comprising: receiver means responsive to the source signal for synchronizing the source within the synchronization interval and providing a retransmit request signal indicative of the source signal; transmitter means responsive to the retransmit request signal for synchronizing at least one receiver within one CSMA time interval delay of the synchronization interval and for transmitting the second data interval to the at least one receiver within one CSMA time interval delay of the source data interval; and interface means for synchronizing the receiver means with the transmitter means to enable data transmission therebetwee

Abstract: For use in a communications network capable of establishing a bonded call between first and second endpoints using at least two bonded communication channels, a subsystem for preserving a relative latency of the at least two bonded communication channels to allow the bonded call to be transferred to a third endpoint. The subsystem includes: (1) a buffer depth index detection circuit that detects learned values of buffer depth indices associated with the bonded call and stored at a first location and (2) a buffer depth index transmission circuit, coupled to the buffer depth index detection circuit, that transmits the learned values to a second location accessible by the third endpoint to allow the bonded call to be transferred to the third endpoint without requiring the third endpoint to relearn the values.

Abstract: The data communications systems disclosed herein accommodates terminals having different throughput capabilities by flexibly allocating cyclicly rotated phases of a common pseudo-noise (P/N) code. Throughput capabilities of the terminals are expressible in multiples of a preselected minimum throughput rate so that a single respective code phase is assigned to any terminal operating at the minimum throughput rate while a plurality of sequential consecutive phases are assigned to each terminal having a capability greater than the minimum throughput rate. One or more unassigned phases are provided between phases assigned to different terminals. Any terminal operating at the minimum throughput rate utilizes all time slot intervals in a predetermined frame interval while terminals of greater capability are assigned time slots in accordance with the amount of data traffic to be carried by that terminal and the number of code phases assigned thereto.

Abstract: In a cellular telephone system of the type having TDMA channels, the beginnings of the time slots of an uplink transmission as seen in the base station are offset from the beginnings of the time slots of a downlink transmission as seen in the base station by a predetermined amount. By offsetting the beginnings of the time slots, a mobile station is able to operate at an extended distance from the base station without any modifications to the mobile station. Because the mobile stations can operate at a greater distance from the base station without a decrease in the number of available channels, the cellular telephone system is particularly suitable for use in rural areas or coastal areas.

Abstract: Remote units (113) having large amounts of data to transmit will be dynamically assigned Orthogonal Variable Spreading Factor (OVSF) codes corresponding to higher data rates and remote units (113) with lower amounts of data to be transmitted will be assigned OVSF codes corresponding to lower data rates. The reduction of the data rate between the base station (100) and remote units (113) occurs by changing the current OVSF codes utilized by both the remote units (113) and the base station (100). In order to eliminate collisions among remote units transmitting data, a remote units transmission is advanced and retarded in time based on an amount of offset from a frame boundary.

Abstract: A system for synchronizing base transceiver stations includes a reference base transceiver station and a subordinate base transceiver station. Each base transceiver station has a clocks with the same frequency but any relative phase, and a timing reference. The reference base transceiver station imposes its own timing reference on each subordinate base transceiver station to compensate the phase difference between the two stations. The timing reference is imposed by having a mobile station listen to the reference base transceiver station and the subordinate base transceiver station, deducing a time shift D1 between the two base transceiver stations from the perspective of the mobile, determining a propagation time difference D2 between the mobile and the reference base transceiver station and the subordinate base transceiver station upon the occurrence of a handover that involves the reference base transceiver station.

Abstract: The transmission points are determined in time for an asynchronous transfer of information (speech/data) in relation to a synchronous information transfer so that the asynchronous transmission does not coincide with the synchronous reception. The asynchronous and the synchronous reception take place at short distances, e.g., less than 200 m, and the terminals are arranged close to each other and can therefore disturb each other. The frequency band of one terminal is also close to the frequency band of the second terminal. In the asynchronous terminal, the relative times are stored for transmission and reception regarding the synchronous terminal. A procedure is stored in the asynchronous terminal, which, during a predetermined time interval before each synchronous transmission, detects if and when transmission occurs from the synchronous terminal and if the detected signal power exceeds a predetermined threshold value.

Abstract: A data transmitting method, a data transmitting apparatus, and a data transmitting system by which a transmission delay time to be received by the transmission data is measured, the data is transmitted while compensating for the transmission delay in the communication line on the transmission side, and the data received at the reception side is processed. The transmitting apparatus on the reception side transmits the measurement bit to the transmission side, and the transmission side sends back this measurement bit to the reception side. The delay processing circuit on the reception side detects the time difference between the generated measurement bit and the returned measurement bit. The delay processing circuit on the reception side generates the reference signal at a timing preceding in time the reference signal in the internal portion on the reception side by exactly the detected time difference and transmits the same to the transmission side.

Abstract: A system for time division multiplexed communication over a single frequency band in which guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. In one embodiment, during a first portion of a time frame, a base station issues a single burst segmented into time slots comprising data directed to each user station. After a single collective guard time, the user stations respond, one by one, in allocated time slots on the same frequency as the base station, with only minimal guard times between each reception. In order to prevent interference among the user transmissions, the base station measures the round trip propagation time for each user station and commands the user stations to advance or retard their transmission timing as necessary.

Abstract: A method for scheduling a plurality of cells of a call via a connection linking a multiplicity of nodes which include a source node and a destination node is provided. A frame counter which counts down the time slots of each frame to be reset to a frame size is assigned to each node of each connection. All the frame counters at all the nodes are pre-synchronized on a connection basis based on propagation delays and delay bounds so that each upstream count of the frame counter in the upstream node is previously correlated to a downstream count of the frame counter in the downstream node. So the eligible time of a cell at each node can be determined without delivering scheduling information from an upstream node to a downstream node.

Abstract: An asynchronous digital system, an asynchronous data path circuit, an asynchronous digital signal processing circuit and an synchronous digital signal processing method, which enables improved processing speed while maintaining high reliability are provided by dividing the overall chip into blocks with a specified area, forming the connection between the blocks by applying thereto a delay insensitive (DI) model or a quasi delay insensitive (QDI) model, while forming each block by applying thereto a scalable delay insensitive (SDI) model. In the SDI model, the system is configured using circuit components having a delay assumed during design in which if the specification states that a signal transition (b) in a subcircuit 7 precedes a signal transition (c) in a subcircuit 8, k.multidot.

Abstract: The present invention comprises a dynamic skew compensation circuit. The present invention includes a receiver, a plurality of channel inputs built into the receiver, and a delay stack structure coupled to the plurality of channel inputs. The receiver is adapted to accept data from a parallel data transfer cable. The channel inputs couple to each of the individual communications channels which comprise the parallel data transfer cable. The delay stack structure includes a plurality of delay stacks, each coupled to a respective channel input. Each delay stack dynamically selects an additional delay amount for its respective communications channel such that each communications channel of the parallel data transfer cable is deskewed with respect to the others. In so doing, the distances across which data can be received and the speeds at which data is transferred via the parallel data transfer cable is increased.

Abstract: An improved method for Time Division Multiple Access (TDMA) communications particularly applicable to a network comprising transmitters having significantly different transmission paths to a common receiver. The common receiver measures the response time from each transmitter, relative to a common time reference, then instructs each transmitter to delay all subsequent responses by an amount specific to each transmitter, as determined from these measured response times. This imposed delay results in a more time efficient TDMA protocol, improved error detection capability, and improved security capabilities. This invention is particularly applicable to bi-directional communications to and from a provider of Cable TV, Telephony, and Data Services.

Abstract: The present invention pertains to a self-synchronization apparatus and method for use in a multiple access channel communication network. In an embodiment of the present invention, the communication system is a wireless mobile telephone network having a service area including one or more base stations and multiple mobile stations. The base and mobile stations are in communication with a Global Positioning System (GPS). A mobile station communicates with a particular base station through a TDMA radio communication link. Each mobile station is assigned one time slot for transmitting data to the base station and a second time slot for receiving data from the base station. The mobile station and the base station exchange their respective GPS positions. A transmitting station determines a time delay based on the receiving station's GPS position.

Abstract: A low cost, high speed multimedia data network is disclosed. The network preferably includes a fiber optic data bus arranged in a star topology configuration. Various types of devices or nodes may be placed in communication with the bus via a specially designed interface. The interface allows a device to communicate with the high speed network without requiring that the device have the processing power to receive and transmit data according to the protocols and demands of the network. The interface may be configured to match the complexity of its associated device. For intelligent devices, the interface may allow some of the network-related functions to be performed by the device itself. For non-intelligent (or "dumb") devices, the interface performs substantially all of the network-related functions.

Abstract: In time domain multiplex/time domain multiple access communications between a base station and subscriber unit, the base station sends a timing reference signal. A subscriber unit responds with a data packet (a) sufficiently short to ensure correct reception by the base irrespective of transmission time. The base determines the transmission time taken and instructs the subscriber unit to advance its timings so that longer data packets (b) can be sent so as to be received when expected. The timing adjustment includes both a fixed present component dependent on approximate separation of base station and subscriber unit, and a second component from measurement of the transmission time taken.

Abstract: A self synchronizing network protocol which allows networks to become self synchronizing. Two pairs of nodes communicate in an ad hoc packet radio network. Packets are communicated over a plurality of frames of time. A known bit field is appended to each packet. A clock at the first pair of nodes (10 and 12) is unavoidably slower than the clock at the second pair of nodes (14 and 16). As a result, packets transmitted from the second pair of nodes (14 and 16) will eventually overlap packets transmitted from the first pair of nodes (10 and 12). Errors in the appended field (17) can be used to detect such an overlap in advance to prevent damage to the payload. The protocol provides for additional channel efficiency, more responsiveness and the ability to grow without a central controller. Further, the ability to accommodate new traffic is increased.

Abstract: According to the present invention, an adaptive and efficient MAC protocol for wireless access to an ATM network is capable of supporting any type of ATM service class with associated Quality of Services parameters. An ATM cell-switched architecture is utilized in which several ATM Mobile Terminals within a given geographic cell (small cells covering a range of several tens of meters) communicate with an ATM Access Point using radio frequency channels, which is connected to an infrastructure ATM network by the means of conventional ATM links. Mobile Terminals can operate both indoor and outdoor with limited range and have wireless access to the Access Points on the ATM network.

Abstract: A Time Division Duplex (TDD) wireless system utilizes an identical TDD IC engine in both base station and remote stations. In the base station the clock input to the TDD IC is halted once in the middle of each time slice to provide a central guard band between transmit and receive portions that determines the maximum range of the system. At the remote stations clock halts are programmed and utilized to provide guard bands to position transmit and receive portions in each time slice to accommodate propagation delay based on separation of a remote station from the base station. In a preferred embodiment the remote stations determine range to the base and a controller programs clock halts based on the range finding. In one aspect a TDD IC engine is used with a minimum fixed central guard band and a time slice of a first duration at a first clock frequency. Clock frequency is increased and the clock halted to provide increased range at the same time slice duration.

Abstract: A method for compensating for propagation time delays in a communication network includes connecting each of a plurality of subscribers to a ring feeder for a common transmission of digital source data and control data in a data stream synchronous with a clock signal. The source and control data are transmitted in a format prescribing a pulsed sequence of individual bit groups of identical length containing component bit groups each forming a data channel for source data or control data. At least two subscribers, which are connected at different locations to the ring feeder, receive source data that are transmitted by one of the subscribers on different data channels and are correlated with one another. Specific bit positions are reserved in each bit group for a numerical value relayed from subscriber to subscriber. The numerical value is always set by one of the subscribers to a fixed initial value and incremented by each following subscriber along the ring feeder.

Abstract: With an object being the overall reduction of error in systems wherein reception timing is controlled by detecting the timing error of the received signal even when the signal arrival path varies in multipath communication and similar conditions, the present invention comprises a timing error detection means 3 which detects errors between the time slot reception time and reception timing of the received signal, a reception timing control means 1 which controls the reception timing of the slot on the basis of errors at reception of preceding time slots, and a control adjustment means 2 which adjusts the amount of control of the reception timing in relation to the errors detected, the control adjustment means 2 making it possible, by taking the time average of each error detected during reception of a plurality of time slots, to fix the error in the vicinity of the maximum frequency of timing delay distribution, even where there are variations in error resulting from variations in the arrival path of the receiv