Abstract: An optical add-drop multiplexer successively comprises a first ferrule, a first graded index (GRIN) lens with a bandpass filter attached thereon, an optical crystal, a second GRIN lens, and a second ferrule. An input and an output optical fiber are stationed in the first ferrule, and a dropping and an adding optical fiber are stationed in the second ferrule. An optical multiplexed signal from the input optical fiber is transmitted through the first GRIN lens to the bandpass filter. From the bandpass filter, an optical signal having a wavelength identical to a central wavelength of the bandpass filter is output to the dropping optical fiber, and other optical signals having other wavelengths are coupled with an optical signal from the adding optical fiber having a wavelength identical to the central wavelength of the bandpass filter and are transmitted to the output optical fiber.

Abstract: An orthogonal code generating circuit 10 is arranged by a counter circuit unit 12, a combination circuit unit 14 of orthogonal codes, and a control circuit unit 16. Furthermore, the combination circuit unit 14 is constructed of an AND gate 14a and an exclusive-OR gate 14b. The control circuit unit 16 outputs a decode output in response to a set code designation signal CNo. When a code generation starting signal ST is inputted, a counter circuit 12 starts to output a counter output. Both the decode output and the counter output are entered to the combination circuit unit 14 which AND-gates the corresponding output bits with each other, and thereafter, exclusively OR-gates the AND-gated outputs, and then outputs the exclusively OR-gated signal as serial data of an orthogonal code. As a consequence, since the conventional ROM unit for storing thereinto the orthogonal codes can be omitted, the circuit scale of the orthogonal code generating circuit 10 can be reduced.

Abstract: A User Equipment (UE) has a circuit that performs the acquisition for the low chip rate option of the Universal Mobile Telecommunication System (UMTS) Time Division Duplex (TDD) standard as formulated by the Third Generation Partnership Project (3GPP). The present invention implements the detection of the basic SYNC code; the determination of the midamble used and the detection of the superframe timing based on SYNC code modulation sequence. This enables reading of a full Broadcast Channel (BCH) message.

Abstract: Techniques to process data for transmission in a time division duplexed (TDD) communication system. In one aspect, the frequency response of a forward link is estimated at a base station based on reverse link transmissions (e.g., pilots) from a terminal. Prior to a data transmission on the forward link, the base station determines a reverse transfer function based on the pilots transmitted by the terminal, “calibrates” the reverse transfer function with a calibration function to derive an estimate of a forward transfer function, and preconditions modulation symbols based on weights derived from the forward transfer function. In another aspect, the terminal estimates the “quality” of the forward link and provides this information to the base station. The base station then uses the information to properly code and modulate data prior to transmission such that the transmitted data can be received by the terminal at the desired level of performance.

Abstract: Method and apparatus for Min star calculations in a Map decoder. Min star calculations are performed by a circuit that includes a first circuit that performs an Min(A,B) operation simultaneously with a circuit that calculates a ?log(1+e?|A?B|) value. The sign bit of the A?B calculation is used to select whether A or B is a minimum. The A?B calculation is also used to select either ?log(1+e?|A?B|) or ?log(1+e?|B?A|) as the correct calculation. In order to hasten the selection of either ?log(1+e?|A?B|) or ?log(1+e?|B?A|) as the correct calculation the apparatus does not wait for the A?B calculation to complete. Any bit of the A?B calculation between the third bit and final (sign bit) can be used for the selection. If an incorrect value is selected a log saturation circuit may correct the value.

Abstract: A searcher is centered on frequency bins to search for an incoming signal. The frequency locked loop generates an initial phase signal and a phase increment signal that are input to an accumulator. The accumulator accumulates the phase increments over a predetermined interval. After the interval, the accumulator generates a control signal that instructs a rotator to perform a phase rotation function.

Abstract: An apparatus includes two antennas and a receiving device working with space diversity. The receiving device receives signals modulated with complex time spreading coefficients produced by a base station. The receiving device includes demodulation branches which have code inputs. To avoid signals coming from the antennas being digitally coded in an independent manner, a mixer circuit shifts the phase of the signals of one of the channels, whereas the code inputs of one of the branches receive the spreading code and the inputs of at least one other branch receive the conjugate spreading code.

Abstract: A phase detector generates a phase dependent control signal according to the phase relationship between a first and second clock signal. The phase detector includes first and second phase detector circuits receiving the first and second clock signals and generating select signals having duty cycles corresponding to the phase relationship between the clock edges of the first and second clock signals. The phase detector also includes a charge pump that receives select signals from the phase detector circuits and produces an increasing or decreasing control signal when the first and second clock signals do not have the predetermined phase relationship, and a non-varying control signal when the first and second clock signals do have the predetermined phase relationship. The control signal may be used to adjust the delay value of a voltage-controlled delay circuit in order to adjust the phase relationship between the first and second clock signals to have a predetermined phase relationship.

Abstract: A self-adjusting optical add-drop multiplexer monitors the power in a drop signal and attenuates the power in an add signal to match the power in express WDM channels (signals). When used in a fiber network, and more particularly, in a metro network, the deleterious effects of optical amplification are reduced. Power attenuation is also used in an optical switching assembly particularly useful in two-fiber ring network. The optical switching assembly monitors drop channels from the two rings of the network and attenuates the add channel(s) accordingly. An optical switch operates to direct the drop signal from one of the two rings to a receiver in accordance with a control signal based on the monitored drop channels. The self-adjusting optical add-drop multiplexer also monitors the power in the drop signals and issues an alarm if the drop signal is of a power level above or below predetermined levels.

Abstract: A signal extraction method is provided. In the method, signals are extracted by using K beam forming parts, wherein K is a natural number equal to or more than 2, and received signals from a plurality of antennas are applied to each beam forming part. The method includes the steps of: the received signals being processed by each beam forming part successively; a first beam forming part extracting a first signal from the received signals; and a kth beam forming part canceling, from the received signals, signal components which are extracted by beam forming parts from the first beam forming part to a (k?1)th beam forming part so as to extract a kth signal, wherein 2?k?K.

Abstract: A symbol combining method in a Rake receiver, which relates to a method for combining the demodulated multi-path signals in a demodulation process of a code division multiple access communication system. The symbol combining method, a Rake receiver using the symbol combining method and a method for driving the Rake receiver, remarkably reduce a hardware complexity of a FIFO register used to regulate a timing synchronization of each finger in Rake receiver by using a new algorithm in a combining process when a CDMA communication system combines a plurality of multi-path signals therebetween. Whereas a conventional combining algorithm uses an individual FIFO register every finger so as to adjust a timing synchronization of each symbol before combining a demodulated symbol, the inventive combining algorithm performs a symbol combining operation as well as a timing synchronization of a symbol at the same time, and performs a combining action by using only one FIFO register irrespective of the number of fingers.

Abstract: A constrained-envelope digital communications transmitter (10) places constraints on the envelope of a spectrally constrained, digitally modulated communication signal (42) to lower peak-to-average power ratio without allowing significant spectral regrowth. A communication signal (14,42) is applied to a plurality of cascade-coupled constrained-envelope generators (50). Each constrained-envelope generator (50) detects overpeak events (52) and configures corrective impulses (54) for the overpeak events (52). The corrective impulses (54) are filtered into shaped pulses (88) that exhibit a constrained spectrum and combine with the communication signal (14, 42) to reduce an unwanted signal peak. Trailing portions (92) of the shaped pulses (88) are fed-back and combined with the communication signal (14,42) so that future overpeak events (52) are identified after compensation is made for the influence of the trailing portions (92) of any recently past shaped pulses (88) on the communication signal (14,42).

Abstract: A device forms packets for a stream of information being transmitted over a packet switched network (such as the Internet) in the normal manner. The device responds to a predetermined event by deliberately forming packets to provide a different quality of service, as compared to the service quality provided by packets that were formed prior to the event. The predetermined event can be related to deterioration or improvement in network performance, and the device can respond by correspondingly decreasing or increasing the service quality of the packets being formed. Specifically, the predetermined event can indicate an increase in processing requirements beyond a threshold, and the device reduces service quality by including a larger amount of information (also called “payload”) in each packet formed after the event, as compared to the amount of information included prior to the event.

Abstract: In a multi-channel communication system (300) data (306) and pilot data (308) are combined to provide a composite signal comprising discrete data signals (405), each having a data portion (407) and a pilot data portion (409). The composite signal is transmitted and a corresponding composite signal received on a communication channel having varying characteristics. An added pilot semi-blind (APSB) channel estimator (320) and equalizer (330) apply a converging iterative process to estimate the characteristics of the communication channel and the transmitted data.

Abstract: A Direct Sequence Spread Spectrum (DSSS) receiver system (100) combines and orders the soft symbols from associated information channels. The system permits a QPSK channel to be demodulated as a pair of BPSK channels, and the soft symbols of the demodulated BPSK channels to be multiplexed into a single information channel. The receiver system (100) includes a plurality of demodulating fingers (102–106). Each demodulating finger accepts modulation parameters and a sample stream, while supplying soft symbols with indexing information so that information channels can be subsequently multiplexed into a single information channel. A method for ordering the soft symbols of associated information channels in a DSSS system is also provided.

Abstract: A superhet receiver with quadrature IF and improved demodulator is configured to recover a modulated signal from a low IF in a radio receiver. A superhet receiver receives a FM radio-frequency signal, converts the input RF signal to an in-phase IF signal and an IF signal in phase quadrature to the in-phase signal, and outputs the IF signals. A plurality of monostables receive the IF signals and each monostable generates a corresponding output pulse. By combining the monostable output pulses, a complex waveform is generated. The complex waveform includes the demodulated signal and a carrier signal at a significantly higher IF. The complex waveform is filtered to recover the desired modulated signal.

Abstract: Optical signals inputted to input ports are split in half by 1×2 optical splitters respectively and the resulting signals are inputted to the input terminals of an optical matrix switch. The optical matrix switch switches between the routes of the individual optical signals and outputs the signal at any of the output ports. This enables the optical signal from the same input port to be outputted at two different output ports, which makes it possible to effect “bridge” at the time of protection switching.

Abstract: A router apparatus 5 is provided with an ATM switch, an IP controller for performing routing control as a controller for layer 3, plural kinds of interfaces which are individually provided to plural transmission paths in which various communications are performed, and a cell multiplexing/demultiplexing unit, and manages the cell communications between respective parts on the basis of identification information. The input packet is subjected to IP processing in an interface to be converted to a cell in a common format, and the cell is serially multiplexed with a cell from another interface on a cell basis, and transmitted to the ATM switch at the cell multiplexing/demultiplexing unit. Each interface and each cell multiplexing/demultiplexing unit sets and switches the identification information for the header portion of the packet and the cell to be communicated by using a table in which the corresponding relationship of the identification information is registered.

Abstract: Systems and methods are disclosed for improving DSL performance, including ADSL and VDSL performance, over a local loop between a telephone company central office and a customer premises. In particular, a loop extender is coupled to the local loop and differentially amplifies downstream and upstream DSL signals to at least partially compensate for DSL signal attenuation that occurs as DSL signals pass over the local loop. Pursuant to one embodiment, the loop extender includes an upstream filter/amplifying equalizer, a downstream filter/amplifying equalizer, a differential amplifier pair, an inverting amplifier, and a pair of electromagnetic hybrids, which couple the loop extender to the loop and provide upstream and downstream signal amplification. In another embodiment, the loop extender includes POTS loading coils to improve the POTS or voice band transmission over the local loop. According to this embodiment, the loop extender provides both improved POTS band signal transmission and DSL service.

Abstract: The present invention provides a method and network for communicating over free space links. The network includes a plurality of buildings, each housing at least one of a residence and a business. Pluralities of free-space optical links are established, where each optical link is defined between two of the buildings, and data is communicated across the plurality of links. Each of the buildings includes a distribution system configured to receive the data communicated across at least one of the links and to distribute the data to an intended recipient. The plurality of optical links are configured to form a network topology providing alternate communication paths for at least two of the plurality of buildings and an external network is coupled with the optical communication network, wherein at least some of the data is communicated between the external network and the optical communication network.