3560 results about "Spread spectrum" patented technology

A method called the evolvable interference management (EIM) method is disclosed in this patent for avoiding interference and collision and increasing network throughput and energy efficiency in wireless networks. EIM employs sensitive CSMA/CA, patching approaches, interference engineering, differentiated multichannel, detached dialogues, and/or spread spectrum techniques to solve the interference and QoS problems. EIM-based protocols can considerably increase network throughput and QoS differentiation capability as compared to IEEE 802.11e in multihop networking environments. Due to the improvements achievable by EIM, the techniques and mechanisms presented in this application may be applied to obtain an extension to IEEE 802.11 to better support differentiated service and power control in ad hoc networks and multihop wireless LANs. New protocols may also be designed based on EIM.

A wireless packet data communications system that includes a number of modem pool transceivers (MPTs), one or more modem pool controllers (MPCs), and one or more servers. Each MPT receives and processes data packets to generate a modulated signal (e.g., a CDMA spread spectrum signal) suitable for transmission over a terrestrial communications link. Each MPC provides call related processing for one or more MPTs. The servers couple to the MPTs and MPCs via an Internet Protocol (IP) back-bone and provide management of the communications system. The IP back-bone further interconnects the MPTs with one or more data networks and includes a number of routers that route data packets between the data networks and the MPTs. Each MPT can couple to two or more routers for redundancy. Each MPT is operated as an element in an IP network and is associated with an IP address that identifies the MPT. One to three MPTs can be deployed at each cell site to provide wireless data service coverage for up to three sectors at the cell site. The MPCs can either be centralized and coupled to the MPTs via the IP back-bone or distributed about the communications system.

The method and apparatus for information conveyance and distribution to bidirectionally focus or guide a wide spectrum of electromagnetic waves propagated over a possible variety of propagation media, including free space or wireless, surface wave, and cable or wired transmission lines. The apparatus communicates with information devices immediately adjacent to these media wherein the devices, which are not themselves part of the apparatus, may have electromagnetic access to one another. The apparatus maintains adequate signal to noise ratio and low distortion for a possible variety of different signal modulation and encoding types which it can support while permitting transparent, simultaneous communications among a variety of devices. Spread spectrum techniques may be used within the apparatus to mitigate propagation medium distortions and impairments as well as to control access and provide a means for securing information within the corridor and for obtaining revenue. Adapters may be employed to provide either full or half duplex access to the information devices which utilize it.

The present invention is generally directed to systems and device for monitoring remote device with a wireless, dual-mode communication protocol. As such, a representative embodiment is a system for monitoring and controlling remote devices. The system includes a first- and a second remote device; and a first and a second wireless transceiver integrated with the respective remote devices. The wireless transceivers are configured to communicate with at least one of a spread-spectrum communication protocol and a fixed-frequency communication protocol.

The invention discloses a presswork encryption security printing technology based on multi-system quadrature amplitude modulation. By adopting the security printing technology, a paseudorandom modulating signal can be generated from anti-counterfeiting information through spread spectrum, encryption and channel coding, the anti-counterfeiting information can be embedded into a whole page through a multi-system quadrature amplitude modulation (QAM) mode, and the anti-counterfeiting information can be identified from any fragment in presswork identification. The invention has very strong smash-resistance, can effectively resist piracy behaviour based on cameras, scanners, electronic documents and the like, and can be widely applied to the field of presswork anti-counterfeit.

Apparatuses and methods determine positional information from a reflected optical signal for an object on a per pixel basis. A spread spectrum imaging system includes a transmitting module transmitting a transmitted optical signal that illuminates a target space and contains a transmitted pulse that is modulated with a first pseudo-noise (PN) code. The imaging system includes a receiving module that receives a reflected optical signal from an object. The reflected signal is processed by an optical array that detects a detected signal from the reflected optical signal, where the detected signal contains a plurality of pixels spanning a target space. When the determined PN code corresponds to the selected PN code, image information and the positional information is presented for the object. When different positional information is obtained for different pixels in the image, the imaging system may determine that different objects appear in the received image.

The present invention is directed to the selective provision of interference canceled signal streams to demodulating fingers in a communication receiver. According to the present invention, potential interferer signal paths are identified. Signal streams having one or more potential interferer signals removed or canceled are created, and a correlation is performed to determine whether the strength of a desired signal path increased as a result. If the correlation indicates that the strength of a desired signal path was increased by the signal cancellation, the interference canceled signal stream is provided to the demodulation finger assigned to track the desired signal path. If the correlation determines that the strength of the desired signal path did not increase as a result of performing interference cancellation, the raw or a different interference canceled signal stream is provided to the demodulation finger.

Embodiments of the present invention include one or more wireless transmitting devices and an array of receiver units for receiving wireless communications from the transmitting devices. The transmitter devices and receiver units can be arranged in one, two or three dimensional configurations. Signals are transmitted from the devices for identification and accurate location determination. Spread spectrum techniques can be used, such as DSSS, FHSS, THSS, and pseudo-noise (PN) coding schemes, or combinations thereof. The transmitting devices can generate one or a plurality of data signals that are orthogonal-code modulated, to be decoded by the receiver units and a processor associated therewith. A plurality of transmitter signals can be received, identified, located, and data demodulated substantially simultaneously using embodiments of the invention. The combined use of array processing methods and diversity schemes can be used to reduce the effects of signal multi-path and occlusion.

A method and apparatus are disclosed for a wireless communication device to simultaneously receive at least two signals. Two receiver portions are provided in the wireless communication device. A first receiver portion is configured to receive a first communication signal. A second receiver portion is configured to receive a second communication signal. The two receiver portions are configured to convert the first and second communication signals to a common frequency band. The common frequency band may be an intermediate frequency band or baseband frequency band. The converted first and second communication signals are combined in the common frequency band using an adder or other signal combiner. The combined signal is processed in a single signal processor. The communication device is able to resolve each of the received signals when the first communication signal is a narrowband signal and the second communication signal is a wideband signal, such as a spread spectrum signal.

Spread spectrum packet-switching radio devices (22) are operated in two or more ad-hoc networks or pico-networks (19, 20, 21) that share frequency-hopping channel and time slots that may collide. The frequency hopping sequences (54) of two or more masters (25) are exchanged using identity codes, permitting the devices to anticipate collision time slots (52). Priorities are assigned to the simultaneously operating piconets (19, 20, 21) during collision slots (52), e.g., as a function of their message queue size or latency, or other factors. Lower priority devices may abstain from transmitting during predicted collision slots (52), and/or a higher priority device may employ enhanced transmission resources during those slots, such as higher error correction levels, or various combinations of abstinence and error correction may be applied. Collisions are avoided or the higher priority piconet (19, 20, 21) is made likely to prevail in a collision.

A spread spectrum receiver and method having narrow-band interference rejection of narrow-band jamming signals using digital signal processing frequency domain techniques. The method performed in the receiver includes transforming the received signal to a frequency domain signal and identifying narrow-band interference components in the frequency domain signal; suppressing the identified narrow-band interference components by excising the identified narrow-band interference components from the frequency domain signal to produce an interference excised signal in the frequency domain, and storing in a memory frequencies corresponding to the identified narrow-band interference components; synchronizing a receiver code to a transmitter code in the frequency domain using the interference excised signal; generating coefficients for a time domain filter that includes notches at the frequencies corresponding to the excised narrow-band interference components and that jointly despreads and rejects narrow-band interference from the excised frequencies; applying the coefficients generated in the preceding step to the time domain filter, and despreading and filtering in real time in the time domain the received signal using the applied coefficients.

The present invention relates to remote radio control technology, and a remote radio control system includes a radio movable working machine (1), a remote control apparatus (6A), and a movable repeater station (7). First bidirectional communication means (31, 71) having a high radio wave directionality and first automatic tracking means (32, 71A) are provided between the working machine (1) and the repeater station (7), and second bidirectional communication means (63, 76) having a high radio wave directionality, second automatic tracking means (63A, 76A), and emergency spread spectrum bidirectional communication means (64, 87) for enabling bidirectional communication between the remote control apparatus (6A) and the repeater station (7) when communication by the second bidirectional communication means (63, 76) is impossible are provided between the remote control apparatus (6A) and the repeater station (7). Consequently, even if communication between the working machine (1) and the movable repeater station (7) is disabled, each of the working machine (1) and the repeater station (7) is permitted to perform a minimum necessary operation, and any other person than those skilled in actual controlling operation of the working machine (1) can perform remote control easily.

A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment. Such systems are compatible with bandwidth-on-demand and higher-order modulation formats and use advanced adaptation algorithms. In a specific embodiment the spectral and spatial components of the adaptive weights are calculated in a unified operation based on the mathematical analogy between the spectral and spatial descriptions of the airlink.

A cellular wireless internet access system which operates in the 2.5 to 2.68 GHz band and which must comply with complex government regulations on power levels, subscriber equipment and interference levels yet which provides high data rates to users and cell sizes of 1½ miles radius or more from base stations with subscriber equipment and antennas mounted indoors. Such base stations are mounted low and use spread-spectrum transmission to comply with interference rules with respect to adjacent license areas. An unidirectional tear-drop coverage pattern is used at multiple cells to further reduce interference when required. Time division duplex is used to allow the system to operate on any single channel of varying bandwidth within the 2.5 to 2.68 GHz band. Backhaul transmission from base stations to the Internet is provided using base station radio equipment, operating either on a different frequency in the band or on the same frequency using a time-division peer-to-peer technique. Different effective data-rates are provided by a prioritization tiering technique.

A radio frequency (RF) motion capture system includes stationary sensor receivers, one or more transmitter marker tags on one or more objects to be tracked within a capture zone, at least one stationary reference tag transmitter, and a processing system for processing the received signals. The individual tags transmit burst of spread-spectrum RF signals. The transmitted signals include a common sync code, and a tag identification code that is unique to each tag. By computing double differences of pseudoranges, clock terms are cancelled out allowing the processing system to precisely determine the location of each tag as it moves through the capture zone without the need to synchronize clocks between sensors and tags. The system can be used for RF match moving.

A method and spread spectrum transceiver for demodulating a spread spectrum signal is disclosed. A spread spectrum phase shift keyed (PSK) modulated information signal is received within a demodulator of a spread spectrum receiver on a signal channel. The information signal includes a sequence of data symbols formed from a plurality of high rate mode chips. A precursor portion of the signal channel is Viterbi detected. A multi-state trellis is formed having a predetermined number of states. A post-cursor portion of the signal channel is feedback equalized with a finite impulse response filter having feedback taps operatively connected to a chip detection circuit that tracks high rate mode chips and a carrier loop circuit for phase and frequency tracking. The information signal is despread within a spread spectrum code function correlator.

According to embodiments of the invention, a communications system includes an error correction encoder that error correction encodes a bitstream according to an error correction code. The system also includes a variable symbol generator that generates a symbol according to a selected one of a plurality of selectable signal constellations from a group of bits of the error correction encoded bitstream. The system further includes a spreader that spreads the symbol according to a spreading code, and a transmitter that transmits the spread symbol in a communications medium. Preferably, the plurality of selectable signal constellations includes at least two signal constellations of different order. In other embodiments, the error correction encoder includes a variable error-correction encoder that encodes the bitstream according to a selected error correction code of a plurality of selectable error correction codes. In still other embodiments, the spreader includes a variable spreader that spreads the symbol according to a selected spreading code of a plurality of selectable orthogonal spreading codes including at least two spreading codes of different lengths. A controller may select the error correction code used by the variable error correction encoder, the signal constellation used by the variable symbol generator, and the spreading code used by the variable spreader to provide a desired information transmission rate for the bitstream. Related methods are also described.

A system for monitoring a physical parameter of a subject includes a sensor, a transmitter, a repeater, and a base station. The sensor is located within the body of the subject and is operable to sense a physical parameter of the subject. The transmitter is electrically connected to the sensor, and is operable to transmit a spread spectrum encoded signal using a digital spreading code, the encoded signal carrying information indicative of the sensed physical parameter and being transmitted to a local region outside the body. The repeater is located in the local region, is movable with the subject, and is operable to receive the transmitted encoded signal and retransmit it to a remote region outside the body. The base station is located in the remote region and is operable to receive and decode the retransmitted encoded signal.