407 results about "Adjacent-channel interference" patented technology

Wireless networks and devices are ubiquitous today. For service providers to offer customers QoS and Service Level Agreements (SLAs) means in part providing resilient connectivity of wireless devices with good signal strength, good Signal to Noise and Interference Ratio (SNIR), and adequate useable bandwidth. Doing so requires that devices transmitting and receiving packets use over-the-air bandwidth efficiently and manage over-the-air congestion. According to embodiments of the invention QoS measurements and controls are incorporated only in the network (i.e. APs or controllers) and therefore QoS and SLAs can be achieved with all deployed client stations versus standards based approaches that require additional capabilities in network nodes, client stations and in most cases modifications to the applications. SLAs can be provided exploiting embodiments of the invention for traffic prioritization, capacity improvements through load distribution, and adjacent channel interference mitigation discretely or in combination with standards based mechanisms.

In a transmitting method, it is possible to avoid influences of adjacent-channel interference to perform communication satisfactorily. In the case of performing transmission with a previously set sending power, the transmission is performed with the set sending power with respect to a channel having the largest sending power. With respect to a channel having the next largest sending power, if its adjacent channel is the determined channel, the transmission is performed such that the sending power is corrected on the basis of the sending power of the determined channel. Thereby, it is possible to prevent the signal-to-interference wave power ratio C/I of the channel from deteriorating due to the leakage signal (interference wave) from the adjacent channel. Thus, it is possible to avoid the influences of adjacent-channel interference to thereby perform communication satisfactorily.

A system and method for Access Point (AP) channel selection based upon a Channel Quality Index (CQI) is described. The Channel Quality Index (CQI) is a value which quantifies a transmission quality of a channel. The transmission quality is evaluated based on a combination of different types of measured interference in the channel. In one embodiment the different types of measured interference include co-channel congestion, adjacent channel interference and in-band interference. The CQI is a value derived from the measurements, and for example may be a sum of all of the measurements. Each AP of the present invention determines the CQI of potential transmission channels, and selects a channel for use which has the ‘best’ CQI; for example if the CQI is a sum of all measured interferences, the ‘best’ AP is the one with the lowest CQI

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.

The guard band between two carriers of the same or different operators is reduced or dynamically adjusted by initiating a dynamic change request of the guard band between the two carriers to allow for flexible spectrum use by adjusting the tolerable guard band overlap. The data is distributed or positioned in the carrier spectrum band as a function of the Quality of Service so that the lowest Quality of Service constrained data are positioned at the edges of the carrier spectrum band and the highest Quality of Service constrained data are positioned in the middle of the carrier spectrum band to minimize any impact from the increased adjacent channel interference due to the guard band overlap and narrower guard band.

Systems, methods, and apparatuses for providing waveform adaptation are provided. In an example, a method is provided for identifying a plurality of candidate waveforms, and selecting one of the candidate waveforms for data transmission. The candidate waveforms may be identified in accordance with one or more criteria, such as a transmission capability of the transmitting device, a reception capability of the receiving device, a desired Peak-to-Average-Power-Ratio (PAPR) characteristic, adjacent channel interference (ACI) rejection requirements, spectrum localization requirements, and other criteria. The waveform selected for data transmission may be selected in accordance with one or more waveform selection criteria, such as traffic characteristic, application types, etc.

A circuit for reducing adjacent-channel interference by pre-linearizing and pre-distorting an input signal to be transmitted via a power amplifier having a non-linear transmission characteristic is disclosed. A portion of the input signal exceeding a dynamic range of the power amplifier is determined and expanded along the time axis to produce an expanded version thereof. The expanded version and the input signal are combined, such that the expanded version is subtracted from the input signal, to produce a pre-linearized signal. The circuit further has a pre-distorting unit for pre-distorting the pre-linearized signal using complex pre-distortion coefficients, such that the distortion introduced by the non-linear transmission characteristic of the power amplifier is substantially compensated for according to magnitude and phase.

Wireless networks and devices are ubiquitous today. For service providers to offer customers QoS and Service Level Agreements (SLAs) means in part providing resilient connectivity of wireless devices with good signal strength, good Signal to Noise and Interference Ratio (SNIR), and adequate useable bandwidth. Doing so requires that devices transmitting and receiving packets use over-the-air bandwidth efficiently and manage over-the-air congestion. According to embodiments of the invention QoS measurements and controls are incorporated only in the network (i.e. APs or controllers) and therefore QoS and SLAs can be achieved with all deployed client stations versus standards based approaches that require additional capabilities in network nodes, client stations and in most cases modifications to the applications. SLAs can be provided exploiting embodiments of the invention for traffic prioritization, capacity improvements through load distribution, and adjacent channel interference mitigation discretely or in combination with standards based mechanisms.

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.

An improved multicarrier modulation system and method, which has the advantages of both isotropic orthogonal transfer algorithm orthogonal frequency division multiplexing (IOTA OFDM) and scalable advanced modulation (SAM), is introduced. The invention is root raised cosine (RRC) OFDM using the most spectrally efficient RRC filter without sacrificing the compact subchannel spacing of OFDM. The invention further provides an adjacent channel interference (ACI) suppression scheme and a modified RRC for better suppressing ACI of RRC OFDM. The ACI suppression scheme can also be applied to SAM with the modified RRC and to IOTA OFDM with a modified IOTA. The invention greatly improves a major problem of conventional OFDM namely ACI due to the use of a wide subchannel filter. Thus, the invention allows OFDM to meet even the strictest ACI requirements, which was not possible by using a conventional raised cosine windowing method.

A method and system for transmitting and receiving data to prevent Adjacent Channel Interference (ACI) in a Cognitive Radio (CR) communication system are provided, in which a second system using a second frequency band measures a first channel interference that a first frequency band used by a first system causes to the second frequency band, determines a frequency spreading parameter according to the first channel interference, measures a second channel interference that the second frequency band causes to the first frequency band, receives link information from the first system according to the second channel interference, determines a power allocation map according to the link information and transmits and receives data according to the frequency spreading parameter and the power allocation map.

The invention discloses an implementation method and device for avoiding adjacent channel interference in electronic toll of collection (ETC). The method comprises the following steps that: an on-board unit (OBU) receives a beacon service table (BST) signal transmitted by a road-side unit (RSU), records a channel number field identifier of the RSU in the BST and establishes a communication link with the RSU, wherein RSUs of adjacent lanes are provided with different channel number field identifiers; and when the OBU receives the BST signal once again in an area covered by an RSU antenna, the OBU verifies a channel number field identifier in the BST, determines that the BST signal which is received once again is transmitted by the RSU if the channel number field identifier is consistent with the recorded channel number field identifier, and completes charging operation with the RSU in response to the BST signal which is received once again. After the method and the device are adopted, two communicating parties are arranged at the same fixed frequency point during a transaction between the RSU and the OBU, so that the probability of adjacent channel interference is effectively lowered.

The invention discloses an antenna downward inclination angle determination method and device based on a geographic information system (GIS). The method comprises the following steps: determining an equivalent coverage radius of a cell of each base station according to base station location information in the GIS and the Thiessen polygon principle and determining a maximum coverage radius of the cell of each base station according to an application scene which the cell of each base station is located in; when the equivalent coverage radius is ascertained to be smaller than or equal to the maximum coverage radius, determining the antenna downward inclination angle of the base station which the cell belongs to based on the equivalent coverage radius; and when the equivalent coverage radius is ascertained to be larger than the maximum coverage radius, determining the antenna downward inclination angle of the base station which the cell belongs to based on the maximum coverage radius. According to the technical scheme of the antenna downward inclination angle determination method and device based on the GIS, the problems, that handling capacity in a border cell is reduced and a resource usage ratio is low, caused by unreasonable arrangement of the antenna downward inclination angle of the base station in same-frequency networking in a time division-long term evolution (TD-LTE) system can be avoided, same and adjacent channel interference among cells can be reduced effectively and network service quality and user experience effects are improved.

A method for designing Wavelets for communications and radar which combines requirements for Wavelets and finite impulse response FIR filters including no excess bandwidth, linear performance metrics for passband, stopband, quadrature mirror filter QMF properties, intersymbol interference, and adjacent channel interference, polystatic filter design requirements, and non-linear metrics for bandwidth efficient modulation BEM and synthetic aperture radar SAR. Demonstrated linear design methodology finds the best design coordinates to minimize the weighted sum of the contributing least-squares LS error metrics for the respective performance requirements. Design coordinates are mapped into the optimum FIR symbol time response. Harmonic design coordinates provide multi-resolution properties and enable a single design to generate Wavelets for arbitrary parameters which include dilation, down-sampling, up-sampling, time translation, frequency translation, sample rate, symbol rate, symbol length, and set of design harmonics. Non-linear applications introduce additional constraints. Performance examples are linear communications, BEM, and SAR.

The present invention offers significant improvements in the performance of a radio receiver operating in an environment with high desired band interference. The present invention comprises a high selectivity RF circuit that is located between the antenna and the radio receiver, and utilizes superheterodyne technology to filter adjacent channel interference in the desired band frequency spectrum. This type of interference is problematic for IEEE 802.11 radio receivers that are implemented with the popular direct conversion radio receiver architectures. The present invention may be utilized in many types of radio receivers.

The high selectivity RF circuit comprises channel select filters, a down-converter, an up-converter and a programmable local oscillator. The radio receiver provides control signals to the high selectivity RF circuit that permits the selection of an appropriate channel select filter and permits the generation of a local oscillator that subsequently generates the proper intermediate frequency in a mixer.

A filter device and method for suppressing effects of Adjacent-Channel Interference of a received signal in a Frequency-Division-Multiple-Access system by filtering a baseband signal of the received signal. The filter device comprises an interference filter, which is a complex digital Single-Input-Multiple-Output, SIMO, filter that is adapted to simultaneously generate a first signal filtered at an upper-frequency-band and a second signal filtered at a lower-frequency-band, wherein the first signal is separate from the second signal. The filter device also comprises a selector adapted to select one of the signals as the output from the filter device.

A method of receiving an FM digital audio broadcasting signal including a first plurality of subcarriers in an upper sideband of a radio channel and a second plurality of subcarriers in a lower sideband of the radio channel comprises the steps of mixing the digital audio broadcasting signal with a local oscillator signal to produce an intermediate frequency signal, passing the intermediate frequency signal through a bandpass filter to produce a filtered signal, determining if one of the upper and lower sidebands of the digital audio broadcasting signal is corrupted, and adjusting the local frequency oscillator signal to change the frequency of the intermediate frequency signal such that the bandpass filter removes the subcarriers in the upper or lower sideband that has been corrupted. A receiver that processes a digital audio broadcasting signal in accordance with the method is also provided.

A system and method for Access Point (AP) channel selection based upon a Channel Quality Index (CQI) is described. The Channel Quality Index (CQI) is a value which quantifies a transmission quality of a channel. The transmission quality is evaluated based on a combination of different types of measured interference in the channel. In one embodiment the different types of measured interference include co-channel congestion, adjacent channel interference and in-band interference. The CQI is a value derived from the measurements, and for example may be a sum of all of the measurements. Each AP of the present invention determines the CQI of potential transmission channels, and selects a channel for use which has the ‘best’ CQI; for example if the CQI is a sum of all measured interferences, the ‘best’ AP is the one with the lowest CQI

The present invention relates to an adaptive, cost-performance efficient, power-saving apparatus for wireless communication systems, such as but not limited to Bluetooth (BT) receivers, and in particular to a packet-based receiver's decoding algorithm which can detect the presence or absence of the adjacent channel interference (ACI) before the scheduled starting time for receiving a Bluetooth packet, and accordingly set the receiver configurations including the filter's pass-band bandwidth (BW), filter's order, the sampling rate, the number of analog-to-digital-converter (ADC) output bits, and the automatic-gain-control (AGC) algorithm unit to determine the low noise amplifier (LNA) and variable gain amplifier (VGA) settings.

In accordance with the principles of the present invention, in addition to conventional use of frequency division multiplexed upper and lower side bands, the spectral area occupied by the analog host will be utilized by applying a one-dimensional modulation, e.g., pulse amplitude modulation (PAM) as opposed to the conventional use of a two-dimensional modulation, e.g., quadrature amplitude modulation (QAM). Furthermore, the analog and digital information within the analog host bandwidth may be combined in quadrature to keep the signals orthogonal. Thus, should one side band under the analog carrier be deteriorated or obliterated by adjacent channel interference, the other side band under the analog carrier can still provide useful data and hence better digital audio codec performance. By transmitting one or two digital data streams asymmetrically with respect to the center frequency, particular digital side bands can be rendered useless as environmental conditions warrant (e.g., as they become detrimentally affected by adjacent channel interference), reducing bandwidth capacity but not affecting the quality of the received digital data transmitted in any of the remaining digital side band regions.

A blind scan system in a DVB-S system includes a spectrum parameter extractor to fetch and calculate a coarse carrier frequency offset and coarse symbol rate of a signal; a digital mixer to depend on the coarse frequency offset to shift the center of a spectrum of the signal to a position where a DC part of a working spectrum of a digital matched filter locates, so as to produce an offset signal; and an interpolator to perform a down-sampling on the offset signal according to the coarse symbol rate in order to improve the in-band signal-to-noise ratio of the digital matched filter and mitigate impacts due to adjacent channel interferences. Thus, the fine carrier frequency offset and fine symbol rate estimation can be performed accurately.

The invention relate to the technical field of mobile communication, disclosing a terminal of a digital mobile wireless transferring system, a method for adjusting the transmission power thereof and a system thereof. The method comprises the following steps of: receiving an idle frame transmitted by a transferring table, wherein the idle frame carries the information of transferring table transmitting power; obtaining the transferring table transmitting power according to the information in the idle frame; transmitting data at appointed transmitting time slot after entering into a transmitting status; receiving a single of the transferring table and computing a received signal strength value in a reversal signal path; ensuring the transmitting power of the next frame according to the transmitting power of the transferring table and the received signal strength value when needing to continuously transmit the data; and transmitting the next frame data at the appointed transmitting time slot according to the ensured transmitting power of the next frame. The invention can lead the terminal to adaptively adjust the transmitting function thereof, reduces the power consumption, and reduces the adjacent channel interference and radiation.