266 results about "Cdma signal" patented technology

A method and device which dynamically detects, tracks and filters interfering signals with sufficient speed (i.e. within one IS-95 CDMA data frame period, or 20ms and fidelity to eliminate or greatly reduce the deleterious effects of narrow band interferor signals on a CDMA link. When inserted in an RF signal path an Adaptive Notch Filter (ANF) detects narrow band interferors above a threshold level within the CDMA signal. Detection is accomplished by continuous scanning of a preset excision band, e.g. a specified narrow band associated with an AMPS system. Detected interferors are then automatically acquired and suppressed. This is achieved by electronically placing a rejection notch at the frequency of the interferors. Multiple notch filters may be used to simultaneously suppress multiple interferors. In the absence of interferors a bypass mode is selected allowing the RF signal to bypass the notch. Upon detection of an interferor, a switch is made to a suppression mode where the interferor is steered through a first notch section and suppressed. Alternatively, an external control line may be used to select the bypass mode so that the signal is allowed to pass the notch section, regardless of interferer content.

The present invention relates to a system and method for providing location determination in a configured environment in which Global Navigation Satellite System Signals are not available. In this regard, local beacon systems generate spread spectrum CDMA signals that are received by spectral compression units that derive physically meaningful observations without a requirement for correlation of the intercepted energy by means of the known spreading codes. The invention can coexist with communication assets already in place, and the design allows for self calibration, which simplifies installation and usage. The invention has utility in applications in which GNSS signals are unavailable or limited, for example, in warehouse inventory management, in search and rescue operations and in asset tracking in indoor environments.

The invention relates to a mobile terminal parallel radio frequency testing device, which comprises a CDMA signal resource, a frequency spectrum analyzer and a switch matrix connected to the CDMA signal resource and the frequency spectrum analyzer; a testing control unit via the GPIB connecting the CDMA signal resource, the frequency spectrum analyzer, and the switch matrix; and a communication direct current power resource connected to the CDMA signal resource, the frequency spectrum analyzer and the tested mobile terminal to supply power for them. The invention uses the dynamic power testing technique based on the single point trigger and the mobile terminal sender, to realize the parallel correction test. The invention can correct and test the radio frequency property of the sender and the receiver of CDMA mobile terminal to improve the testing speed and improve the utilization of device.

Bandwidth reduction of amplitude and/or phase components of relatively wide bandwidth composite signal. In an exemplary embodiment, an EER amplifier system for CDMA signal amplification includes an amplitude bandwidth reduction module included in an amplitude signal component path and a phase bandwidth reduction module is included in a phase signal component path, for controlling an RF amplifier. The phase bandwidth reduction module may reduce the phase component bandwidth of the input signal by, for example, generating a non-linear relationship between phase signal amplitude and input signal amplitude. The amplitude bandwidth reduction module may reduce the amplitude component bandwidth of the input signal by, for example, generating a non-linear relationship between the supply voltage to the RF amplifier and an input signal amplitude.

An improved approach to noise estimation permits, for example, tighter closed-loop power control in a wireless communication network with attendant improvements in transmit power efficiency and network capacity. In an exemplary embodiment, the received signal-to-noise ratio (SNR) of a data signal is estimated based on noise samples obtained from one or more other signals received in association with the data signal. In general, these associated signals are characterized by the receiver's ability to extract like valued samples from them, such that pairs of these like valued signal samples may be subtracted, thereby canceling their deterministic signal components and leaving only difference values representative of the non-deterministic noise components of the signal samples. Obtaining difference values from more than one associated signal increases the sample size of difference values used in noise estimation, thereby improving the statistical basis for noise estimation and, therefore, the accuracy of SNR estimation.

Disclosed is a pilot multiplexing method in an Orthogonal Frequency Division Multiplexing (OFDM) system. Transmit data is transmitted by an OFDM signal through an OFDM scheme, pilot data is directly spread, and a spread-spectrum signal, which has been obtained by spreading, is transmitted in the same frequency band as that of the OFDM signal at the same time in superposition therewith or time-division multiplexed therewith. The spread-spectrum signal is a CDMA signal that has been obtained by spreading the pilot data by a prescribed spreading code.

An apparatus for searching for a cell and a method of acquiring a code unique to each cell in an asynchronous wideband Direct-Sequence Code Division Multiple Access (DS/CDMA) receiver, wherein the cell searching apparatus searches for a cell based on a received asynchronous wideband DS/CDMA signal in a receiver, the apparatus including a code group identifying unit for estimating and compensating for a frequency error between the synchronous channel and an internally generated primary synchronization code, estimating and compensating for channel degradation which the synchronous channel has experienced, and performing correlation on the compensated synchronous channel and available secondary synchronization codes, thereby identifying the code group; and a scrambling code identifying unit for performing correlation on a plurality of scrambling codes belonging to the code group, thereby obtaining a scrambling code unique to each cell.

A plurality of communications is received. The communications are transmitted in a wireless code division multiple access format. A channel response for each received communication is estimated. A system response matrix is constructed using codes and the channel responses of the received communications. An objective matrix is produced using the system response matrix. The received communications are matched filtered to produce a first input. The first input is processed with an interference cancellation matrix to produce a first set of symbols of the received communications. The first set of produced symbols are processed with a feedback interference construction matrix to produce feedback interference. The feedback matrix added to an inverse of the interference cancellation matrix equals the objective matrix. The feedback interference is subtracted from a result of the match filtering to produce a next input. The next input is processed with the interference cancellation matrix to produce a next set symbols of the received communications.

A PON and a method of transmitting data employing different upstream and downstream transmission protocols are disclosed. The PON includes: a plurality of ONTs; WDM filters; an OLT receiving and transmitting optical signals to and from the ONTs and a higher network; and an optical coupler. The ONT includes a first switching unit, a level transformer converting two level Ethernet signals into a three level data signals, a first code generator generating a specific CDMA codes that distinguish the ONT from another ONT, and a first multiplier performing a spread spectrum function with the CDMA codes. The OLT includes an optical receiver, a branching filter branching the upstream CDMA signals, a plurality of second code generators generating codes for despread, a plurality of second multipliers multiplying the received signals by the despread codes, and a plurality of data decider extracting data through correlation calculation.

Systems and methods for generating a CDMA signal s(t) comprising N components involves assigning to each of the N components one unique spreading sequence a_n selected from a set of M spreading sequences with M≧N, modulating the symbols d_n of each component on the assigned unique spreading sequence a_n, and combining the N symbols d_n each being spread with its own unique spreading sequence a_n to a CDMA signal s(t). The assigned spreading sequences a_n are selected such that all selected pairs within the set of N spreading sequences are orthogonal or very close to be orthogonal so that cross-correlation components between all spreading sequences a_n are close to zero or zero.

A wireless communication device includes a Generalized RAKE (G-RAKE) receiver circuit that is configured to determine a traffic-to-pilot gain scaling parameter as part of the impairment correlation determination process that underlies (G-RAKE) combining weight generation. In this manner, the receiver circuit conveniently and accurately accounts for gain differences between the pilot channel of a received CDMA signal, as used for channel estimation, and the traffic channel(s) of the CDMA signal, which carry received data to be recovered. The gain difference accounting enables proper demodulation of amplitude-modulated traffic signals. By way of non-limiting example, such gain scaling may be used for demodulating/decoding High Speed Downlink Packet Access (HSDPA) signals used in Wideband Code Division Multiple Access (W-CDMA) systems.

The present invention provides a method for a multi-path detection analysis and selectivity of CDMA signals using spread spectrum receivers using a correlation technique. The invention is based on determining by the spread spectrum receiver whether a distortion of a received radio frequency signal, caused by a multi-path component of said received signal, meets a predetermined condition using a pre-selected correlation analysis of said received signal. This invention is generally applicable to global navigation satellite system (GNSS) receivers and it is particularly useful in GNSS receivers, such as GPS (global positioning system) and Galileo receivers. The important goal of this invention is to provide a simple method for identifying signals that are corrupted by multi-path effects, and can be excluded from position calculation in the GNSS receivers.

A signal reception method including method and apparatus for receiving a signal, down converting the received signal through multi-tone down conversion to form an intermediate signal, and decoding the intermediate signal to extract data. In an embodiment, the received signal may include multiple transmission bands of a multi-code (MC)-CDMA signal, each of which occupies a different spectrum. Each of the transmission bands also includes an information channel signal. When the received MC-CDMA signal is down converted through multi-tone down conversion, the intermediate signal is formed. The intermediate signal includes a common spectrum that includes an information channel from a plurality of transmission bands. When the intermediate signal is decoded, data from a plurality of information channel bands is extracted. The method and apparatus may be implemented in a multi-mode MC-CDMA/CDMA receiver.

There is disclosed, for use in a CDMA receiver, a noise reduction circuit for improving the signal-to-noise ratio of a received CDMA signal comprising a series of chip sequences. The noise reduction circuit comprises: 1) a sampling circuit for generating an original plurality of samples of the received signal; and 2) a controller for determining a first plurality of time slots containing chip samples equal to Logic 1, and a second plurality of time slots containing chip samples equal to Logic 0. The controller generates a reconstructed plurality of samples by at least one of: a) modifying an order of a first Logic 1 chip sample and a second Logic 1 chip sample; and b) modifying an order of a first Logic 0 chip sample and a second Logic 0 chip sample.

The present invention discloses a method for detecting orthogonal code CDMA signal implemented mainly through the following steps: estimating the total power of interference to the multi-path signals; performing matched filtering on the multi-path signals and performing maximum ratio combining on the multi-path signals by utilizing the total power of interference to the multi-path signals, to obtain the optimized matched filtering result; and performing joint detection on the optimized matched filtering result. There are two schemes for implementing: if the optimized matched filtering detection scheme is used, only the first two main steps are executed; if the joint detection scheme is used, all of the three steps are executed. In either of above two schemes, the interference code channels involved in the estimation of total power of interference to the multi-path signals are need to be selected, i.e., all of the code channels in the serving cell or the code channels in the serving cell which are not performed joint detection on are selected. As the present invention takes full advantage of the characteristic of orthogonal code as well as the channel estimation result, system performance can be improved at a lower price. The present invention is especially suitable for terminal devices in an orthogonal code Code Division Multiple Access system.

In an arrangement for receiving CDMA signals, insertion of guard intervals is rendered unnecessary and transmission efficiency loss is suppressed, along with greatly reducing the computational burden of weight calculations. Impulse responses of a transmission channel are obtained by time-domain signal processing, the impulse responses are Fourier transformed and converted into frequency domain signals, equalizing filter weights are calculated using the frequency domain impulse responses, the calculated frequency domain weights are converted to time domain weights using an inverse Fourier transform, the received signals are filtered using time-domain signal processing, and data signals are demodulated by despreading the equalized signals.