481 results about "Co-channel interference" patented technology

A method of determining operating parameters for a secondary system transmitter is described. The transmitter characteristics, including location and operating frequency band, are provided to a geo-location database. The database determines the maximum allowable transmission power that meets various specifications for different channels and conveys the power and channel(s) to the transmitter. The database estimates channel incumbent signal strengths based on the transmitter location and primary and higher-priority secondary incumbent systems, estimates the splatter levels, determines whether adjacent and co-channel interference protection ratios are met, and adjusts the allowable power level accordingly. The database also estimates aggregate co- and adjacent channel primary and secondary incumbent system interference levels at the transmitter location and predicts channel quality for each allowable channel. The estimated levels are updated using measurements of actual levels at the transmitter location. The database dynamically allocates channels using the secondary system priorities.

A system, method, and software are provided for measuring co-channel interference in a wireless network with particular application for management of resource allocation for Non Line of Sight (NLOS) wireless backhaul in MicroCell and PicoCell networks. Given the difficulty of predicting the mutual interference between multiple links, DownLink and UpLink co-channel interference are characterized between each Hub and each Remote Backhaul Module Unit periodically during active service. Beneficially, the co-channel interference metrics are used as the basis for intelligently and adaptively managing network resources to substantially reduce interference and increase the aggregate data capacity of the network e.g. by grouping of interfering and/or non-interfering links, and managing resource block allocations accordingly, i.e. assigning common resource blocks preferentially to weakly interfering links or groups of links and allocating different resource blocks or orthogonal channels to strongly interfering links or groups of links.

A downlink frame (401) is divided in to similar sized resource blocks (403, 405, 407) with each co-channel sector scheduled to transmit from the beginning of its respective assigned resource block. Transmissions to remote units within the particular sector will occur only within the particular resource block, up to a point where all N resource units have been utilized. Beyond that point, additional transmissions are scheduled to be transmitted at the end of the resource blocks assigned to the other sectors.

A novel and useful apparatus for and method of Gaussian Minimum Shift Keying (GMSK) single antenna interference cancellation (SAIC) for use in a digital receiver. The invention comprises an interference mitigation module that treats the problem of GMSK SAIC in a blind manner. The interference mitigation mechanism is operative to compensate for the co-channel interference added in the communications channel which is subject to multipath propagation and fading, receiver filter and any pre-channel estimation filtering. The interference mitigation module takes advantage of the spatial diversity making up multiple branches of the received signal. The branches comprise the in-phase and quadrature elements of the received signal, the sampling phases if over sampling is applied (i.e. T/m sampling) and/or multiple antennas. The invention utilizes the spatial diversity of these multiple representations of the received signal and combines (i.e. collapses) the information in the plurality of branches into a single branch that is input to the equalizer.

A DTV signal has a plural-data-segment frame header including complementary first and second ghost-cancellation reference signals differentially delayed by the duration of two NTSC horizontal scan lines. A receiver for such DTV signal has an adaptive equalizer for baseband symbol code with kernel weights calculated by a computer operative on the equalizer response after comb filtering. The comb filter combines the equalizer response as differentially delayed by the duration of two NTSC horizontal scan lines to cancel artifacts of co-channel NTSC interference in the comb filtered equalizer response supplied to the computer. This reduces the undesirable influence of such artifacts on equalization to reduce intersymbol interference.

A femtocell increases efficiency and coverage of a macrocellular network operating in a co-channel manner within the macrocell spectrum by selecting subcarriers for its mobile station using both the subcarrier allocation map received from the macrocell and a spectrum sensing operation. Interference is avoided by selecting only subcarriers not allocated by the macrocell and subcarriers allocated to users not nearby to the femtocell. Interference is eliminated from the received signals using co-channel interference avoidance techniques. Selection of subcarriers for femtocell use may take into consideration inter-carrier interference detected.

A method and apparatus for transmitting beacon signals in a wireless communications network. For a given cell site, a single frequency may be used for the beacon signal by assigning different beacon signal time slots to different sectors of the cell site. During one time slot, the beacon signal is transmitted to one of the sectors, and during another one of the time slots, the beacon signal is transmitted to a different one of the sectors. Because a single frequency can be used for all of the sectors of a cell site, more frequencies are available for other purposes, such as for user traffic, for example. The invention improves spectral efficiency, reduces adjacent channel interference and co-channel interference and allows power consumption to be controlled.

Methods and systems consistent with the present invention provide a method for dynamically controlling power consumption in a digital demodulator circuit by varying clock rates and bit widths of demodulator components including an analog to digital converter, decimation filter, OFDM operating engine, FEC decoder, and MPE-FEC processor, according to parameters and conditions of the received signal including modulation mode, signal to noise ratio, effective bit transmission rate, bit error rate, packet error rate, adjacent channel interference, and co-channel interference.

A digital receiver automatically detects and non-coherently demodulates a multiplicity of interfering digitally modulated signals transmitted simultaneously at approximately the same carrier frequency. The receiver includes one or more antenna inputs (e.g., polarization and/or space diverse), a parameter estimator module, and a multiuser detector for estimating the data transmitted by each interfering signals and adapted to operate with at least one of a MUD algorithm with partially quantized prior information and a MUD algorithm based on prewhitened data.

In a wideband Personal Communication Services system, a method and system are proposed for suppressing co-channel interference and reducing inter-symbol interference generated during the transfer of a data packet through a selected radio frequency channel. The system includes a weight controller utilizing recursive least squares algorithm to generate a plurality of appropriate weights to be integrated into received signals in order to maximize signal-to-noise ratio. A detected signal or a training sequence is intelligently switched in as a reference sequence in order to generate a plurality of appropriate weights. To further enhance the adaptive array system and take advantage of the multi-path radio frequency communication environment, two multi-path diversity schemes are included. One embodiment includes an adaptive array system with parallel array processors and another embodiment includes a system with tapped delay line processors.

A system and method for increasing the performance of a satellite communication system by using a multivariate analysis approach to optimize the pointing of the boresight of a satellite-mounted antenna. Optimizing the pointing of the boresight of the antenna minimizes sidelobe generation, and thus Co-Channel Interference (CCI) in geographic areas served by the system. By minimizing CCI, the overall system performance of the communication system is optimized. To optimize the pointing of the boresight of the antenna, the overall performance of the satellite communication system is determined, and the boresight of the antenna is iteratively repointed in the direction of increasing system performance until the optimized boresight pointing is determined. Alternatively, the frequency re-use plan of the satellite communication system may be analyzed to determine a high density cell region and the boresight may be pointed to the high density cell region.

The invention discloses an SC-OFDMA-based satellite mobile communication system for a forward link, which belongs to the field of satellite mobile communication. The SC-OFDMA-based system for the forward link is characterized in that single carrier signals of a user are mapped to different sub-carriers through DFT (discrete Fourier transform) or FFT (fast Fourier transform) and then subjected to IFFT (inverse fast Fourier transform) to realize orthogonal transmission of each user signal so as to improve the utilization rate of high frequency spectrum resources and reduce the peak-to-average power ratio of the satellite forward link; and in the multi-beam-based satellite mobile communication system, different sub-carrier groups are distributed to the users in a beam overlapped area according to the beams belonging to the users so as to reduce the co-channel interference between the low beams and fulfill the aim of improving the capacity of the system.

Co-channel interference in a wireless network is identified and quantified. Rather that using color code identification, a more reliable identification property of each co-channel component of the received composite signal is used, namely, the time of arrival of a known part of a signal. Detection and timing measurement is performed even in presence of stronger signals by focusing selectively on bursts having fixed contents (e.g., the FCCH burst used in GSM for frequency correction). The repetitive measurements of the time-of-arrival of each of the interfering components of the signal during a drive test enables determination of the geographical location of the interfering co-channel base stations.

Substantial improvements in frequency reuse in microwave communications systems is achieved by canceling co-channel interference and transmitter leakage. Interferometric beam-narrowing reduces beamwidth without reducing preak magnitude of the beam pattern. Frequency-dependent beam-shaping compensates for frequency-dependent distortions of the beam pattern thereby improving bandwidth. A spatial demultiplexing technique utilizes spatial gain distributions of received signals to separate signals, even from co-located transmit sources, and uses microwave lensing to enhance received spatial gain distributions. Predetermined cross-polarization interference is used to separate differently polarized receive signals. A reference branch provides a cancellation signal to a receiver to cancel transmitter leakage signals. An error signal controls an impedance-compensation circuit that is responsive to changes in antenna impedance but not to receive signals. A dc bias magnetic field applied to a magnetic permeable material adjusts non-linear distortion in a cancellation circuit for canceling distortion in a transmitter leakage signal. Discreet impedance elements approximate a circuit having distributed impedance.

Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises scrambling a first frame using a first scrambling code, attaching a first header to the first frame to create the first signal, scrambling a second frame using a second scrambling code, attaching a second header to the second frame to create the second signal, and transmitting the first signal and the second signal over different channels of the communication system.

Disclosed is a RF receiver that includes baseband circuitry for performing Minimum Mean-Square Error (MMSE) optimization for substantially simultaneously suppressing inter-symbol interference (ISI) and co-channel interference (CCI) on a signal stream that comprises real and imaginary signal components. In a preferred embodiment the receiver includes a single receive antenna, and operates as a single/multi antenna interference cancellation (SAIC) receiver. The baseband circuitry operates to determine a set of In-Phase and Quadrature Phase (I-Q) MMSE vector weights that are used to perform the ISI suppression and the CCI suppression. A method for operating the receiver is also disclosed.

Base stations having potentially interfering terminal stations that are geographically located on the same or similar diagonal or Line of Sight (relative to the base station) operate on a first set of time frames (e.g., “even” time frames). Similarly, base stations having potentially interfering terminal stations that are not geographically located on the same or similar diagonals operate on a second set of time frames (e.g., “odd” time frames). By alternating in their use of the even and odd frames, the potential for co-channel interference between terminal stations is minimized. Systems and methods are disclosed which reduce co-channel and adjacent channel interference between terminal stations of different cells as well as adjacent channel interference between terminal stations of adjacent cells. The methods and systems so described can be used during the deployment or expansion of a communication system in a region.

Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises scrambling a first header of the first signal using a first scrambling code, scrambling a second header of the second signal using a second scrambling code, and transmitting the first signal and the second signal with the scrambled first header and the scrambled second header over different channels of the communication system.

A received signal selector for a received signal, the received signal including a set of carriers, the received signal selector being configured for use with an antenna system including a plurality of antenna elements. The received signal selector includes a plurality of received signal inputs for receiving signals from the plurality of antenna elements, an interference detector for each of the received signals inputs, coupled to the received signal inputs to receive, from each input, a version of the received signal, and configured to provide an interference output for the set of carriers from each input, a selection controller configured to receive the interference output for each input and having a control output, and a selector coupled to the received signal inputs and responsive to the control output to select one or more of the versions of the received signal for output. The invention provides a simplified technique for mitigating the effects of co-channel interference and severe multipath distortion.

An OFDM receiver includes a CCI detector and a frequency-domain notch filter. The CCI detector detects whether or not the co-channel interference exists in a sub-carrier and lowers the weight of a distorted sub-carrier to eliminate the influence of the co-channel interference. The frequency-domain notch filter receives a frequency-domain signal and generates a notched frequency-domain signal.