Abstract: A hybrid base station transceiver has an ATM matching unit for connecting a wireless terminal to an ATM-based communication network; an IP matching unit for connecting a wireless terminal to an IP-based communication network; a channel and RF processor for performing physical connection protocol processing and RF transceiving processing with the wireless terminal; and a routing processor for determining which network to which the wireless terminal is to connect to by analyzing a signal of OSI Layer 2 or Layer 3 received from the wireless terminal and for connecting the wireless terminal to the ATM-based or IP-based communication network through the channel and RF processor according to the analysis.

Abstract: A VPN includes a shared label switching network, a plurality of VLANs and edge routers interfacing the VLANs with the shared label switching network. The VLANs are each coupled to an edge router and communicate traffic using channelized EoS.

Abstract: The present invention relates to communications systems and, more particularly, to methods and apparatus for efficient address delegation and/or assignment and/or signaling in a virtual communications network, e.g., a network supporting virtual private networks (VPNs) and one or more addressing domains. The methods are well suited for systems such as mobile communications systems, where the number of mobile nodes in each of a plurality of visited domains can change on a relatively rapid time scale, so rendering static address delegation from the home to each visited domain highly inefficient. Address delegation may be undertaken in advance of address assignment requests from a visiting mobile node, or address delegation may be triggered by the address assignment request. Information update messages keep the home domain aware of the assignment status of its delegated addresses and can specifically trigger further delegations so that a number of unassigned delegated addresses is maintained.

Abstract: The present invention allows a terminating telephony switch to detect whether or not a caller associated with an incoming call is associated with multimedia capability. The terminating telephony switch will monitor a call setup message, such as an Integrated Services User Protocol Initial Address Message, to determine whether or not there is multimedia capability information indicative of the caller's telephony terminal being associated with another media device, or including media capability sufficient to support packet sessions over a data network. The multimedia capability information may simply be the presence or absence of a flag, wherein the presence of a flag indicates there is multimedia capability. Alternatively, the call setup message may include the multimedia address associated with the media device of the caller. The originating telephony switch is configured to create call setup messages to provide multimedia capability information to enable the functionality of the terminating telephony switch.

Abstract: In a multi-service network, layer 2 traffic such as IP traffic according to the invention is carried over ATM SVCs or SPVCs. Methods of setting up such connections using the PNNI protocol are also discussed. Using enhancements to the standard ATM SPVC/SVC signaling messages, layer 3 IP routing processes on multi-services switches on opposite ends of the network allow traffic to flow transparently through an underlying layer 2 virtual connection. This provides a simple and efficient way to transport IP packets across an ATM network.

Abstract: A system in accordance with the present invention operates a wireless ad hoc network. The system includes a plurality of nodes and a plurality of protocols for governing transmission of data between the plurality of nodes. A first node of the plurality of nodes executes an evolutionary service migration algorithm for transferring a service from the first node to one of the remaining of the plurality of nodes.

Abstract: An apparatus comprises a forwarding component configured to forward data by looking up a routing table, another forwarding component configured to receive the data, and an intermediate forwarding component bridging the two components to forward the data without looking up the routing table.

Abstract: The present invention is directed to a system for linking a first autonomous network system to at least one second autonomous network system. The first autonomous network system having a first private IP address space and the at least one second autonomous network system having at least one second private IP address space. The first private IP address space and the at least one second private IP address space are at least partially overlapping. The system includes a first routing domain including the first autonomous network system and at least one second routing domain including the at least one second autonomous network system. A geographically diverse linking autonomous system couples the first autonomous network system and the at least one second autonomous network system.

Abstract: A gateway supports communications between network devices connected to different private networks. When a tunnel setup request message is received from a host connected to a first private network to setup a tunnel to a second private network connected to a public network, a a control unit of the gateway communicates with the gateway of the second private network, negotiates necessary information, and sets up a VPN tunnel utilizing the information. If the private networks have identical network address, or if network address of one private network is included in the network address of the other, a new network address table is created such that the two private networks can use different network addresses in the VPN tunnel. With respect to data packets being transmitted from the host of the first private network, or from the second private network, an address is translated based on the new network address table, and therefore, the translated address is forwarded.

Abstract: A method and apparatus associates a domain name of a home gateway with one or more PVCs. After the PVC is established, a tunneling protocol is used to request the domain name of the home gateway, and the domain name is associated with the PVC. When a user logs on via an access communication device, the user will provide a domain name of a home gateway with which the user desires to communicate. A PVC associated with the home gateway is then used to allow the user to communicate with the home gateway. The domain name of the home gateway may be periodically verified to detect any changes.

Abstract: A switch, switched architecture and process for transferring data through an FCAL switch is disclosed. The switch uses multiple switch control circuits each coupled to one FCAL network and all connected to a crossbar switch. The switch control circuits are coupled together by a protocol bus for coordination purposes. Local conversations can occur on each FCAL loop and crossing conversations through the switch can occur concurrently. The OPN primitive is used to establish the connection before any data is transferred thereby eliminating the need for buffer memory in the switch control circuits. The destination address of each OPN is used to address a lookup table in each switch control circuit to determine if the destination node is local. If not, the destination is looked up and a connection request made on the protocol bus. If the remote port is not busy, it sends a reply which. causes both ports to establish a data path through the backplane crossbar switch.

Abstract: A plurality of mesh-connecting ports interconnect a plurality of bridges including an own bridge and other bridges as a mesh network. A packet transmitter/receiver reciprocally transmits and receives packets between the plurality of bridges through the mesh-connecting ports. A shortest path constructing unit constructs the shortest path between the bridges through the packet transmitter/receiver. An STP processing unit executes STP processing for activating a spanning tree protocol (STP) to provide redundancy to the mesh network. A backup processing unit continuously leaves in the mesh domain a first mesh network bridge detected a line fault, and executes the backup processing to active a back up protocol for forming a backup route in such a manner that the packet reaches a second mesh network bridge that has become unreachable by the line fault, through a third mesh bridge connected with the second mesh network bridge.

Abstract: A method of processing a call with reduced call set-up times using one or more telecommunication networks includes providing one or more preferences for a call associated with a first terminal and a second terminal. The one or more preferences are associated with an initial setup of one or more media channels for the call. The method also includes processing the one or more preferences as a preference message, processing the preference message by an FEA procedure to provide an FEA preference message, and transferring a first framing synchronization flag sequence, the FEA preference message, and a second framing synchronization flag sequence from the first terminal to the second terminal. The method further includes receiving one or more acknowledgement preference messages from the second terminal, completing the initial setup of the one or more media channels, and thereafter, exchanging information between the first and second terminals.

Abstract: A system improves reconstruction of real-time data in a packetized network. The system includes the following elements. A play-out buffer receives packets from the network. A playback element, coupled with the play-out buffer, retrieves packets from the play-out buffer and outputs data for the reconstruction of real-time data. A time adjuster alters the rate at which the data is output in accordance with the availability of the packets.

Abstract: The present invention provides a system and a method for filtering a plurality of frames sent between devices coupled to a fabric by Fiber Channel connections. Frames are reviewed against a set of individual frame filters. Each frame filter is associated with an action, and actions selected by filter matches are prioritized. Groups of devices are “zoned” together and frame filtering ensures that restrictions placed upon communications between devices within the same zone are enforced. Zone group filtering is also used to prevent devices not within the same zone from communicating. Zoning may also be used to create LUN-level zones, protocol zones, and access control zones. In addition, individual frame filters may be created that reference selected portions of frame header or frame payload fields.

Abstract: Apparatuses and methods for efficiently transmitting and receiving multicast data having a scalable data structure preferably provide for the transmission of a first data stream at a basic data rate using a first modulation scheme that can be received by all receivers in a communications system, while simultaneously providing for the transmission of at least a second data stream at a higher data rate using a second modulation scheme that can be received by groups of receivers having higher data rate capabilities, thereby maximizing data communications to all receivers in the communications system. The transmitting apparatus preferably includes a stream generator that divides multicast data into a plurality of multicast streams, an encoding processor, a header processor that generates a header for each of the encoded multicast streams, a stream modulator that modulates each of the encoded multicast streams, and a frame generator for generating a transmission frame.

Abstract: An out-of-band ranging technique is automatically initiated at a customer premises equipment unit when the equipment is installed, when power is restored after a power failure or interruption, upon verification of the equipment, upon reconnection after a disconnection of the equipment or the like. To this end, an out-of-band tone is employed that is automatically transmitted when the customer premises equipment that transmits the TDMA signal is powered ON, or transmitted in response to a specific command generated locally or remotely. Specifically, when ranging is being effected the customer premises equipment generates and transmits the out-of-band ranging tone until a message is received from a remote terminal indicating that the transmission of the ranging tone be terminated. The loop delay being determined is the delay interval between transmission of the termination message and detection that transmission of the ranging tone has terminated.

Abstract: The present invention is to provide method and apparatus for adapting a GBIC module to an Ethernet switch capable of outputting one of different voltages in which in a case of the GBIC module coupled to the Ethernet switch, a DC converter of the GBIC module is adapted to lower an input voltage thereof supplied by the Ethernet switch prior to boosting the lowered voltage to an operating voltage required by a GBIC logic circuit of the GBIC module without confirming whether the input voltage has the same value as the operating voltage. Thus, the present invention can prevent the GBIC module from not working due to low input voltage or being damaged due to high current when the GBIC module is coupled to the Ethernet switch.

Abstract: Methods and systems for interfacing packet and circuit telephony operations in a distributed telecommunications network. Initially, one or more digital circuit switches can be associated with the distributed telecommunications network. Thereafter, one or more network transmission elements within the distributed telecommunications network can be connected to one or more of the digital circuit switches. One or more broadband switches can then be associated with one or more of the network transmission elements, such that the broadband switches thereof interface with network transmission elements and the digital circuit switches to coordinate combined circuit and packet signaling, routing and calling processing services among varying terminals of the distributed telecommunications network.

Abstract: For a network that connects several computers, a method of determining the network bandwidth between two computers. The method measures a first time interval between when one of the computers (1) sends a first data set to the other computer and (2) receives a first response. It also measures a second time interval between when one of the computers (1) sends a second data set to the other computer and (2) receives a second response. The method then identifies the network bandwidth from the two measured time intervals.

Abstract: A few high power tones used for synchronization and/or other purposes are transmitted in a FDM system during a period of time into a region, e.g., sector of a cell, e.g., a symbol transmission time period. During normal data transmission symbol periods signals are transmitted using at least 10 tones, e.g., per symbol time. Less than 5 high power signals are transmitted in a symbol time with at least 80% the maximum total transmitter power used for transmitting into said region being allocated to the high power signals where the maximum total transmitter power is determined from a period of time which may includes one or more data and/or high power tone transmission periods. When the high power tones are transmitted at most 20% of transmitter power used for transmitting into the region is available for transmitting other tones with the power normally being distributed among multiple tones. Often some tones which would be transmitted in a symbol time go unused during transmission of the high power signals.

Abstract: A vector-based sequence generator (100) provides for a general architecture that can be easily adapted to any random length sequence and any random number of bits per access. The sequence generator (100) can also produce a new access on every hardware clock cycle, thereby maximizing the efficiency of the bit sequence requesting process.

Abstract: Disclosed are systems and methods which provide interference mitigation by making alternative resources available within areas served by wireless communication links. Embodiments provide multiple channel availability in establishing wireless communication links to facilitate interference mitigation. Time domain techniques, spatial processing techniques, and/or frequency domain techniques may be implemented for spectrum management. Embodiments provide wireless base station configurations in which all or a plurality of base station sectors use a same frequency channel and/or in which each sector or a plurality of sectors use all frequency channels. Multi-channel strategies may be implemented such as to provide dynamic selection of a “best” frequency channel, to provide transmission of identical data on multiple channels for combining/selection at the receiver, and/or to provide for dividing the data for transmission on multiple channels.

Abstract: The disclosure relates generally to a system including a passive optical network element and a first ultra wideband adapter coupled to the passive optical network element. The first ultra wideband adapter is coupled via a data communication line to a second ultra wideband adapter. The second ultra wideband adapter has a connection to an end user computing device.

Abstract: An apparatus and method to generate and restore an RTP (Real-Time Transmission Protocol) packet. A setting unit assigns a CTS (Composition TimeStamp), a DTS (Decoding TimeStamp), and a PSN (Packet Sequence Number) that sequentially increase according to a packet generation order for each of a plurality of SL (Synchronization Layer) packets, extracting a time stamp length and a packet sequence number length from an SLCD (SL Configuration Descriptor) within each SL packet. A packet generating unit generates a header of the SL packet accommodated in an RTP packet header and the RTP packet based on the CTS, the DTS, the PSN, the time stamp length and the packet sequence number length. Since only difference values in the CTS, the DTS, and the PSN information between a previous SL packet and the present SL packet, are recorded, a number of bits can be reduced if the CTS value rolls over and a multiple SL packet can be made for the SL packet having a time stamp length greater than 32 bits.

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: A method and an apparatus using a system level clocking scheme to remove jitter from multi-media packets distributed over an asynchronous network. The present invention overcomes the problems associated with jitter introduced in an asynchronous network by using various time stamps to synchronize a client device clock to a headend clock and to control the data flow in the client device to match the rate that the data is received by a broadband receiver coupled to the headend. The present invention allows the client device to synchronize to a selected one of a plurality of headend clock by including a clock adjustment factor along with the time stamps. The time stamps are added at the physical layer so that the time stamps correspond to the time the data packets are placed onto and received from the asynchronous network.

Abstract: A receiver for high-speed indirect synchronous digital data transmission includes an elastic buffer receiving an incoming data stream containing embedded timing information preceding a data sequence, generating a recovered clock from the timing information, initially synchronizing the frequency of a local clock to the recovered clock, and accommodating subsequent drift between the recovered and local clocks across the duration of the data sequence while tolerating clock jitter. Received data is clocked into a FIFO buffer within the elastic buffer based on the recovered clock and read out based upon the local clock, with the buffer expanding or contracting by adjustment of an index to accommodate skew of greater than one clock period. Expansion or contraction of the FIFO buffer is disabled during periods when clock jitter is likely, such as periods immediately following an index change.

Abstract: A network switch for switching packets from a source to a destination includes a source port for receiving an incoming packet from a source, a destination port which contains a path to a destination for the packet, and a filter unit for constructing and applying a filter to selected fields of the incoming packet. The filter unit further includes filtering logic for selecting desired fields of the incoming packet and copying selected field information therefrom. The filtering logic also constructs a field value based upon the selected fields, and applies a plurality stored field masks on the field value. The switch additionally includes a rules table which contains a plurality of rules therein. The filtering logic is configured to perform lookups of the rules table in order to determine actions which must be taken based upon the result of a comparison between the field value and the stored filter masks and the rules table lookup.

Abstract: An orthogonal polarization multiplexing transmission apparatus capable of performing dispersion compensation considering a short wavelength side and a long wavelength side of a zero dispersion wavelength. A plurality of light signals of different wavelengths are divided into two orthogonal polarization multiplexing portions, and the light signals of an oddnumber array polarization multiplexing portion and an even-number array polarization multiplexing portion are orthogonal-polarization-multiplexed in each orthogonal polarization multiplexing portions. Adjacent light signals of the two orthogonal polarization multiplexing portions have their mutual planes of polarization rendered non-orthogonal when multiplexed by an optical multiplexer so that, for the purpose of deterring inter-symbol interference, a guard hand having the wavelength spacing rendered wider than that on orthogonal polarization multiplexing is provided in advance.

Abstract: The invention relates to a conventional broad-area laser having a single-mode output through the phenomenon of multimode interference (MMI) in step-index waveguides. Another aspect of the present invention relates to a very robust multi-mode compound cavity laser design that is fully defined by the geometry and the refractive index profile of the MMI region, which is quite insensitive to slight macro-scale refractive index variations due to manufacturing variation or temperature. As the self-imaging position shifts linearly in the refractive index, the confocal beam parameter can be made relatively long.

Abstract: A laser device which may be used as an oscillator or amplifier comprising a chamber having a volume formed therein and a gain medium within the volume. The gain medium comprises a solid-state element containing active laser ion within the volume. A cooling fluid flows about the solid-state element and a semiconductor laser diode provides optical pump radiation into the volume of the laser chamber such that laser emission from the device passes through the gain medium and the fluid. The laser device provides the advantages of a solid-state gain medium laser (e.g., diode-pumping, high power density, etc), but enables operation at higher average power and beam quality than would be achievable from a pure solid-state medium.

Abstract: An alterable frequency coherent light generator for the generation of highly energy efficient coherent light, by means of a power supply connected to a four-lead capacitor, which is connected to a variable resistive device in series with a vacuumed bulb. The direct current being conducted through the circuit is formed into a transverse wave of electrons or electric pulses within the vacuumed bulb by means of four-lead capacitor, variable resistive device, vacuumed bulb, and electric current interaction. The anode of the vacuumed bulb is thoroughly connected to the corners of a thin, square metal plate which has a relief conductive wire connecting from an edge of the thin, square metal plate to the four-lead capacitor. The electric pulses emanating from the vacuumed bulb, resonate the electrons within the thin, square metal plate at a frequency determined by four-lead capacitor, variable resistive device, vacuumed bulb, and electric current interaction. The resonating electrons generate coherent light.

Abstract: The relative timing delay between channels of a discharge circuit can be adjusted through application of appropriate control voltages. A control voltage of relatively long duration and relatively small voltage, with respect to a common system pulse, can be applied to any channel in order to adjust the relative timing delay. This control voltage can be, for example, a magnetization pre-pulse voltage applied to an indictor for a channel in order to adjust a hold-off time. A synchronization control unit and feedback loop can be used to monitor the timing, such that the syncronization control unit can apply a control voltage when a delay change exceeds a timing adjustment threshold value, and can apply a pre-ionization voltage when the delay change is less than the adjustment threshold value. Using both a control voltage and a pre-ionization voltage provides for both coarse and fine adjustment of the delay.

Abstract: A diode-pumped solid-state laser (DPSSL) has self-maintained multi-dimensional optimization. The output property of the DPSSL, including optical power, noise level, and the operation conditions of its individual components, including the drive current and temperature of the laser diode, the temperature of the laser crystals and laser cavity, the drive current of the thermoelectric coolers, is monitored and systematically optimized in real time through automatic electronic control using a microprocessor. Such monitoring and optimization enable the DPSSL to maintain its optimum performance in output power, beam quality, noise level, and stability, throughout its lifetime regardless of component aging and change of environmental conditions. A highly accurate temperature monitoring and control method is also developed.

Abstract: An optical module includes a stem; a first lead pin and a second lead pin for receiving differential signals, the first and second lead pins penetrating the stem; a mount block fixed to the stem; a laser diode having a pair of electrodes; a submount mounted on the mount block and having a matching resistance, an interdigital capacitor, and a plurality of electrode patterns on a surface on the submount; and a first wire and a second wire electrically connecting the submount to the first and second lead pins, respectively. The laser diode is mounted on one of the electrode patterns on the submount and connected to another one of the electrode patterns on the submount by a third wire such that the laser diode, together with the matching resistance and the interdigital capacitor, forms an electrical circuit. The value of the matching resistance is smaller than an impedance value of a differential signal source supplying the differential signals minus the resistance of the laser diode.

Abstract: A semiconductor laser element having a structure in which at least one AlGaInP or GaInP layer is formed above a GaAs substrate. The crystal orientation of the principal plane of the GaAs substrate is tilted from (100) toward (111). When the total thickness of the at least one AlGaInP or GaInP layer is 1 micrometer or smaller, the tilt angle of the crystal orientation of the principal face is 8 to 54.7 degrees. When the total thickness of the at least one AlGaInP or GaInP layer is 1 micrometer or greater, the tilt angle of the crystal orientation of the principal face is 13 to 54.7 degrees.

Abstract: An optical structure that reduces the effects of spontaneous emissions from the active region of a laser. An optical structure includes optimizations to reduce the effects of spontaneous emissions. The optical structure includes a VCSEL with top and bottom DBR mirrors and an active region connected to the mirrors. The optical structure further includes a photodiode connected to the VCSEL. One or more optimizations may be included in the optical structure including optically absorbing materials, varying the geometry of the structure to change reflective angles, using optical apertures, changing the reflectivity of one or more mirrors, changing the photodiode to be more impervious to spontaneous emissions, and using ion implants to reduce photoluminescence efficiency.

Abstract: A vertical cavity surface emitting laser diode includes a lower semiconductor reflector, an active region, an upper semiconductor reflector constituting a resonator with the lower semiconductor reflector, a metallic part being formed on the upper semiconductor reflector, which has a first aperture defining an output region of laser light generated in the active region, and a light confining region being provided between the metallic part and the lower semiconductor reflector, and having a second aperture defining an emission region of the laser light. The upper semiconductor reflector includes a lenticular medium having a convex surface toward the lower semiconductor reflector.

Abstract: A line narrowing method and module for a narrow band DUV high power high repetition rate gas discharge laser producing output laser light pulse beam pulses in bursts of pulses, the module having a nominal optical path are disclosed which may comprise: a dispersive center wavelength selection optic moveably mounted within an optical path of the line narrowing module, selecting at least one center wavelength for each pulse determined at least in part by the angle of incidence of the laser light pulse beam containing the respective pulse on the dispersive wavelength selection optic; a first tuning mechanism operative in part to select the angle of incidence of the laser light pulse beam containing the respective pulse upon the dispersive center wavelength selection optic, by selecting an angle of transmission of the laser light pulse beam containing the pulse toward the dispersive center wavelength selection optic; a second tuning mechanism operative in part to select the angle of incidence of the laser light pu

Abstract: A tunable laser includes an optical waveguide alternately including a gain waveguide portion and a wavelength controlling waveguide portion, and a diffraction grating. The diffraction grating includes a gain diffraction grating and a wavelength controlling diffraction grating. A wavelength controlling region is configured such that the wavelength controlling waveguide portion and the wavelength controlling diffraction grating are included therein. A gain region is configured such that the gain waveguide portion and the gain diffraction grating are included therein. The Bragg wavelength of the wavelength controlling region is longer than that of the gain region in a state in which current injection or voltage application is not performed for the wavelength controlling waveguide portion.

Abstract: A laser apparatus is disclosed. The laser apparatus has a diffraction grating that receives laser light from a semiconductor laser, emits first order diffracted light having a predetermined wavelength to the semiconductor laser, and reflects zero-th order light, a reflection section that reflects the zero-th order light reflected by the diffraction grating, a hold section that holds the diffraction grating and the reflection section while an open angle of the diffraction grating and the reflection section is kept constant, the hold section being rotatable with a fulcrum of an intersection of an extended line of a front surface of the diffraction grating and an extended line of a front surface of the reflection section, and a linear drive section that rotates the hold section with a linear motion of a piezoelectric device that expands and shrinks by the piezoelectric effect.

Abstract: Disclosed is a method for increasing a data transfer rate without an increase in the whole bandwidth using intrinsic spreading codes and orthogonal codes. The method uses interleaving, OFDM modulation/demodulation, and maximum likelihood detection (MLD) to overcome the effects of multipath fading or signal interference, determines grouped optimal values by a grouping method of dividing the intrinsic spreading codes in series, and calculates an integrated optimal value for all the intrinsic spreading codes using the grouped optimal values, thereby reducing the complexity of MLD according to the length of the intrinsic spreading code and acquiring an improved performance.

Abstract: The present invention can be used to modify hopping sequences and families of hopping sequences. In one embodiment the present invention includes modifying a family of hopping sequences by eliminating a resource from a plurality of resources used by the family of hopping sequences, eliminating a hopping sequence from the family of hopping sequences, and creating a new family of hopping sequences by replacing the eliminated resource in each remaining hopping sequence using the eliminated hopping sequence. Embodiments of the present invention may further include repeating eliminating a resource, eliminating a hopping sequence, and creating a new family of hopping sequences, until the new family of hopping sequences uses a desired number of resources.

Abstract: A method and device are disclosed for the detection and synchronization of a signal in a frequency-hopping system. The method has a step, for each frequency F(1) . . . F(M), of selecting the K samples corresponding to the greatest values of the signal, and their positions. For a given position, the M greatest values are combined which are selected from among K samples on each frequency having the given position. The greatest combined value is kept and the corresponding position. The greatest combined value is compared with a threshold value, and if the greatest combined value is greater than this threshold value, then the detection of the signal is declared.

Abstract: A mobile communication system receives a reception signal of a reception signal, and performs a control operation such that a weight for generating a reception beam is calculated using a first technique if a difference between an error sum value at a current time and an error sum value at a previous time is greater than an absolute value of a first threshold or the error sum value at the current time is greater than or equal to a second threshold, and performs a control operation such that the weight is calculated using a second technique if the different between the error sum value at the current time and the error sum value at the previous time is less than or equal to the absolute value of the first threshold and the error sum value at the current time is less than the second threshold.

Abstract: The present invention discloses a method for pilot channel tracking based on multipath channel barycenter tracking loop, comprises steps of evaluating multipath fading channel parameters, calculating the barycenter of a multipath energy window, and loop filtering and adjusting the phase of spread spectrum sequence codes. The method of the invention does not need to individually track each delay path, thereby improving the tracking performance and timing recovery stability of a spread spectrum receiver. Only a multipath channel evaluator and a multipath energy window barycenter calculating means are used to track PN signals from a plurality of signal sources, thereby reducing hardware. Thus, a novelty coherent spread spectrum receiver can be constituted by cooperating with other parts.

Abstract: In a spread spectrum system, methods and despreader architectures for despreading the received spreaded codes with the use of a single correlator and a single correlation code is provided. Before despreading the incoming received spreaded codes, a single correlation code is generated using a symbol from a set of symbols that has been mapped into a set of differential encoded PN codes. Despreading output samples for each received spreaded code are obtained by correlating the received spreaded code with this single correlation code. Correlation is accomplished by multiplying each received sample of the received spreaded codes with the correlation code samples and accumulating the products of this multiplication. After correlation, the index for the maximum or minimum peak of the despreading output samples for each code is identified. This index can then be mapped into a symbol corresponding to the transmitted information.

Abstract: In a channel estimating circuit, a Sync Word is demodulated by using a channel estimation value not with a symbol or a slot including the Sync Word to be demodulated, but with its preceding and succeeding symbols or slots. Furthermore, in a channel estimation process, if a Synch Word to be demodulated is included in any of groups into which a plurality of symbols are divided, the Sync Word is demodulated by using a channel estimation value obtained with the channel estimation process using not this group but another group.

Abstract: Provided is a method for generating a preamble sequence group. The method includes creating a preamble sequence, calculating a cross-correlation value between sequences using the created preamble sequence, determining a limit cross-correlation value using the cross-correlation value to construct a preamble set used in the communication system, calculating a preamble set that satisfies the determined limit cross-correlation value, and terminating construction of the preamble set.