295results about "Multiplex multicode" patented technology

In this patent, we present MultiCode Direct Sequence Spread Spectrum (MC-DSSS) which is a modulation scheme that assigns up to N DSSS codes to an individual user where N is the number of chips per DSSS code. When viewed as DSSS, MC-DSSS requires up to N correlators (or equivalently up to N Matched Filters) at the receiver with a complexity of the order of N2 operations. In addition, a non ideal communication channel can cause InterCode Interference (ICI), i.e., interference between the N DSSS codes. In this patent, we introduce new DSSS codes, which we refer to as the "MC" codes. Such codes allow the information in a MC-DSSS signal to be decoded in a sequence of low complexity parallel operations which reduce the ICI. In addition to low complexity decoding and reduced ICI. MC-DSSS using the MC codes has the following advantages: (1) it does not require the stringent synchronization DSSS requires, (2) it does not require the stringent carrier recovery DSSS requires and (3) it is spectrally efficient.

A multiple access, spread-spectrum communication system processes a plurality of information signals received by a Radio Carrier Station (RCS) over telecommunication lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed (CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request signal that corresponds to a telecommunication line information signal, and a user identification signal that identifies a user to receive the call. The RCS includes a plurality of Code Division Multiple Access (CDMA) modems, one of which provides a global pilot code signal. The modems provide message code signals synchronized to the global pilot signal. Each modem combines an information signal with a message code signal to provide a CDM processed signal. The RCS includes a system channel controller is coupled to receive a remote call. An RF transmitter is connected to all of the modems to combine the CDM processed signals with the global pilot code signal to generate a CDM signal. The RF transmitter also modulates a carrier signal with the CDM signal and transmits the modulated carrier signal through an RF communication channel to the SUs. Each SU includes a CDMA modem which is also synchronized to the global pilot signal. The CDMA modem despreads the CDM signal and provides a despread information signal to the user. The system includes a closed loop power control system for maintaining a minimum system transmit power level for the RCS and the SUs, and system capacity management for maintaining a maximum number of active SUs for improved system performance.

A constant amplitude coded bi-orthogonal demodulator demodulates the received constant amplitude bi-orthogonal modulated data, cancels the parity bits to generate the serial data, detects the occurrence of an error by dividing the demodulated data into a plurality of groups of data, outputs the serial data as demodulated data if an error does not occur, sequentially converts bit polarities of data of groups in which an error occurs if the error detector detects the error, compares distances between the received bi-orthogonal modulated data and the constant amplitude coded bi-orthogonal modulated data, and selects, as demodulated data, data of which corresponding bit polarities are changed according to the comparison results. According to the present invention, power consumption is reduced, a power amplifier can be manufactured at an inexpensive cost, interference robustness can be ensured, and data can be transmitted at a high transmission rate and a variable transmission rate.

An information stream of binary symbols is divided into serial packets of N binary symbols. The method further includes serial-parallel conversion of binary symbols in each serial packet and repeating N times the parallel packet thus obtained in order to form a serial-parallel packet of binary symbols. The binary symbols are permuted in the duration interval of each serial-parallel packet, and orthogonal codes generated according to the above binary symbol permutation are then applied. A space-diversity channel is then assigned to each serial group of the serial-parallel packet of coded binary symbols thus obtained. All the serial groups of coded binary symbols, each coded binary symbol having been previously spread by a user spreading code, as well as pilot signals of the corresponding space diversity channels are simultaneously transmitted. The method also involves generating on the reception side a serial packet of soft decisions that corresponds to the serial packet of binary symbols on the transmission side.

Connections from a client to respective ones of a plurality of application instances that receive data from a shared communication protocol stack are assigned by defining an affinity between the client and a corresponding one of the plurality of application instances. Connection requests received from the client at the shared communication protocol stack are assigned to the corresponding one of the plurality of application instances if an affinity is defined between the client and the corresponding one of the plurality of application instances. Connection requests received from the client at the shared communication protocol stack are distributed to selected ones of the plurality of application instances if an affinity is not defined between the client and the corresponding one of the plurality of application instances.

A communications system improves performance of detecting a signal having an indication of a request to change communications states by making at least two positive identifications of the request in a given time frame. The system may further improve performance by applying a difference in power levels for a non-request state (i.e., steady state or ‘control hold’ state) versus a request state (i.e., ‘request to change’ state). In one particular application, a base station determines a request to change communications states with a reasonably high probability of detection and a reasonably low probability of false detection. The system has a reduced number of erroneous communications states, such as erroneous traffic channel allocations. The detection technique is compatible with 1xEV-DV systems and I-CDMA systems, but general enough to support systems employing various other communications protocols used in wired and wireless communications systems.

A CDMA communication method capable of providing a multi-rate user with high quality transmission using a spreading sequence selected from sequences which consist of multilayer sequences arranged in a hierarchical tree structure. A higher level sequence C16(1) and its inverted sequence +E,ovs C+EE 16(1) are included in its lower level sequences {C32(1), C32(2)} and {C64(1), C64(2), C64(3), C64(4)}, for example, and a sequence from a higher level is selected to transmit a higher rate data: The C16(1) is used to transmit data whose peak rate is twice the peak rate of the data transmitted using its lower level sequences {C32(1), C32(2)}, and four times (=22) that of the data transmitted using the sequences {C64(1), C64(2), C64(3), C64(4)}. The C16(l), however, cannot be selected if any one of its lower level sequences {C32(1), C32(2)} and {C64(1), C64(2), C64(3), C64(4)} are already being used. This makes it possible for all the spreading sequences of simultaneous multi-rate users to be orthogonal at any transmission rate.

A DS-CDMA transmission method capable of improving the accuracy of channel estimation using pilot symbols by eliminating cross-correlation between pilot symbols inserted into code channels in CDMA multiplexing carrying out fast signal transmission. In each frame assembler, the pilot symbols, which are used for channel estimation for coherent detection, are inserted into coded information data on code channels at fixed intervals, and then the data is modulated by the modulator. The modulated data symbols in each code channel from the modulator are spread by the spreading modulator, the pilot symbols are spread using a spreading code, whereas the information symbols are spread using different spreading codes assigned to respective code channels. The spread signals of the code channels are summed up by the adder to be transmitted.

The number of users and data capacity of wireless systems are increased by employing apparatus and method for increasing the number of spreading codes available in the system by providing a mechanism to reuse the already allocated spreading code or use the codes that may correlate to those already being used within the same sector/cell. This, in return, provides capacity improvement proportional to the number of added base station (BS) antennas for each cell. An antenna null steering technique for code allocation maintains the cross correlation properties of the codes only for the desired user and to obtain a gain in capacity improvement.

Between communication equipment to be loaded in a vehicle and a base station, CDMA data communication is performed. A speed sensor detects a traveling speed. When the speed sensor crosses a speed determining value, a communication speed is changed. When the vehicle is at a halt or travels at a low speed, the communication speed is set to be high. When the traveling speed exceeds the speed determining value resulting from acceleration, the communication speed is decreased. Satisfactory communication is performed in the whole speed range, and data communication can be performed at the maximum speed. In order to change the communication speed, for example, a chip rate of PN code is changed. Also, the number of PN codes to which parallel processing is simultaneously applied is changed. Thus, it is possible to set the communication speed to be high even in a high-speed mobile object.

Frames comprise odd fields and even fields. The frame sync segments of the odd fields contains a current map specifying the location of data in frames, a next map specifying the location of data in a future frame, and a frame count designating the future frame. The frame sync segments of the even field may contain the same information. Alternatively, the frame sync segments of the odd fields contain the current map and part of the frame count, and the frame sync segments of the corresponding even fields contain the next map and the rest of the frame count. A receiver uses the map and frame count information to find data in the fields of received frames.

An optical processor for controlling a phased antenna array uses a frequency-shifted feedback cavity (FSFC), which includes a traveling-wave cavity. The FSFC incrementally delays and incrementally frequency shifts optical signals circulating in the traveling-wave cavity. Optical signals coupled out of the FSFC are separated by frequency, hence by delay, and processed to control either or both transmit and receive beam-forming operations. The FSFC provides a receiver with multiple receive signals which have incremental values of frequency. Each frequency corresponds to an incremental time sampling of optical signals input into the FSFC. Transmit signals coupled out of the FSFC have frequency and phase relationships that result in short time-domain pulses when combined. Controlling modulation and frequency of the transmit signals achieves carrier interference multiple access, a new type of spread-spectrum communications.

A Wideband Code-Division Multiple Access (WCDMA) transceiver and a method of operating the same. In one embodiment, the transceiver includes: (1) a transmit chain having a lookup table that provides coefficients to a digital predistorter based on power indicators and (2) a predistorter training circuit, coupled to the transmit chain, that employs a receive chain of the WCDMA transceiver to provide a digital compensation signal that is a function of an output of the transmit chain and employs both the power indicators and the digital compensation signal to cause the lookup table to provide alternative coefficients to the digital predistorter thereby to reduce distortion in the output.

In a radio communication system, transmission of CAZAC sequences as the pilot signal sequences by using code division multiplexing as at least one of user multiplexing schemes, is done by dividing a system band as a frequency band usable in the system into frequency blocks B1 and B2 having bandwidths W1 and W2, generating the pilot signals of the frequency blocks B1 and B2 with a single carrier, using the pilot signal sequences having sequence lengths L1 and L2 corresponding to frequency blocks B1 and B2 respectively; and, transmitting the generated pilot signals as the pilot signals corresponding individual users, with multicarriers using an arbitrary number of frequency blocks among the plural frequency blocks

A weighted secret sharing and reconstructing method includes encoding the secret using a predetermined code, producing voices so that different weights are assigned to errors in an error vector according to locations of the errors, encrypting the encoded secret using the error vector and distributing the encrypted encoded secret to a plurality of participants.

The present invention relates to a method and an apparatus for spread spectrum modulation and demodulation using a special spread spectrum sequence, characterized in that Golay complementary codes are modulated onto orthogonal channels such that a corresponding complex complementary code is obtained. The signal spread by such complex complementary code has a low peak-to-average power ratio, a sound self-correlation property and cross-correlation property, which can well solve the problem of multi-access interference such that the communication performance of the entire system is improved.

A transmitting device of the present invention is used in a CDMA communications system, and comprises: a plurality of spreading units for spreading user data; a managing unit for managing spread codes; a determining unit for determining a number of codes to be multiplexed based on use statuses of the spread codes managed by said managing unit; and a multiplexing unit for multiplexing the user data spread by spreading units a number of which corresponds to the number of codes to be multiplexed.

A system and method for transmitting a plurality of spread-spectrum signals over a communications channel having fading. The plurality of spread-spectrum signals are radiated by a plurality of antennas, with each antenna preferably spaced by one-quarter wavelength. A plurality of receiver antennas receive the plurality of spread-spectrum signals and a plurality of fading spread-spectrum signals. Each receiver antenna is coupled to a plurality of matched filters having a respective plurality of impulse responses matched to the chip-sequence signals of the plurality of spread-spectrum signals. A RAKE and space-diversity combiner combines, for each respective chip-sequence signal, a respective plurality of detected spread-spectrum signals and a respective multiplicity of detected-multipath-spread-spectrum signals, to generate a plurality of combined signals. The symbol amplitudes can be measured and erasure decoding employed to improve performance.