Patent application number | Description | Published |
20080225761 | Estimating Timing And Frequency Information For Multiple Channel Wireless Communication Systems - One method of estimating timing and frequency information of a payload transmitted through two or more frequency separated channels combines training fields from preambles from the two or more frequency separated channels to construct combined values that may be used to estimate the frequency and timing information. In one embodiment, the combined values may be determined by combining self-correlated training fields from the frequency separated channels. Another method of estimating the timing and frequency information selects the training fields from the preamble of one of the frequency separated channels based upon a signal quality metric. In another embodiment, the selection of the training fields based upon a signal quality metric may be biased to favor a particular channel. | 09-18-2008 |
20100111212 | Decision Feedback Channel Estimation And Pilot Tracking for OFDM Systems - Current OFDM systems use a limited number of symbols and/or sub-channels to provide approximations for channel estimations and pilot tracking, i.e. phase estimations. For example, two training symbols in the preamble of a data packet are used to provide channel estimation. Four of the fifty-four sub-channels are reserved for providing phase estimation. However, noise and other imperfections can cause errors in both of these estimations, thereby degrading system performance. Advantageously, decision feedback mechanisms can be provided to significantly improve channel estimation and pilot tracking in OFDM systems. The decision feedback mechanisms can use data symbols in the data packet to improve channel estimation as well as data sub-channels to improve pilot tracking. | 05-06-2010 |
20120014415 | TRANSMITTER BEAMFORMING STEERING MATRIX PROCESSING AND STORAGE - A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices. | 01-19-2012 |
20120062421 | PHASE ROTATION TECHNIQUES IN A MULTI-USER WIRELESS COMMUNICATION ENVIRONMENT - A mechanism for mitigating inter-user interference in a multi-user wireless communication environment is disclosed. A first network device determines a plurality of steering matrices, associated with a corresponding plurality of subcarriers, for each of multiple destination devices associated with the first network device. A phase difference between corresponding steering vectors of each pair of consecutive steering matrices of the plurality of steering matrices associated with each of the destination devices is determined and phase rotation is performed to maintain phase continuity between the consecutive steering matrices. One or more pre-coding matrices are calculated based on at least a subset of the plurality of steering matrices associated with the multiple destination devices. The one or more pre-coding matrices are applied to data to be transmitted to the multiple destination devices to mitigate interference between each of the multiple destination devices. | 03-15-2012 |
20120063335 | PACKET IDENTIFICATION FOR POWER SAVING IN WIRELESS COMMUNICATION NETWORKS - A network coordinator can assign an association identifier (AID) and/or a group identifier (GID) to identify a client station to which a packet is to be transmitted and to enable the client station to determine whether to receive an incoming packet. The network coordinator can randomly generate a base AID that is representative of the network coordinator and can assign at least one AID to client stations to minimize the probability of client stations associated with proximate network coordinators being assigned the same AIDs. The network coordinator can also randomly assign at least one GID to a group of client stations to minimize the probability of groups of client stations associated with the proximate network coordinators being assigned the same GID. The client station can analyze indications of a received AID and/or received GID to determine whether to receive the packet or whether to switch to an inactive power state. | 03-15-2012 |
20120069804 | Selecting Frequency Bands For Transmitting Data Packets - A first combination of frequency bands is selected for transmitting a first data packet, and a second, different combination of frequency bands is selected for transmitting a second data packet. A data stream is divided into a first set of data and a second set of data. The first set of data is allocated to the first combination of frequency bands, and the second set of data is allocated to the second combination of frequency bands. | 03-22-2012 |
20120069830 | System And Method For Transmitting A Low Density Parity Check Signal - A system and method for transmitting LDPC parameters is provided. In the method, an initial number of OFDM symbols (Nsym_init) is determined for a packet that is based on the number of information bits to be delivered in the packet. An STBC value is also determined. A number of extra symbols (Nsym_ext) value is generated based on the Nsym_init value, wherein a Nsym value is based on said Nsym_init value and said Nsym_ext value. An Nldpc_ext value is determined based on the STBC value and the Nsym_ext value for purposes of determining LDPC parameters associated with the packet. | 03-22-2012 |
20120076234 | Method And Apparatus For Coding And Interleaving For Very High Throughput Wireless Communications - A wireless transmitter can include a plurality of bandwidth modules, each bandwidth module processing data based on a predetermined frequency band. In one embodiment, such a wireless transmitter can include encoding components for receiving transmit data and generating encoded data. A multiple-input multiple-output (MIMO) stream parser can receive the encoded data and generate a plurality of MIMO streams. A first module parser coupled to a first MIMO stream can generate a first plurality of partial MIMO streams. A first bandwidth module can include a first interleaver that interleaves bits of the first partial MIMO stream and generates first interleaved data. A second bandwidth module can include a second interleaver that interleaves bits of the second partial MIMO stream and generates second interleaved data. A first inverse fast Fourier transform (IFFT) unit can combine and process the first and second interleaved data and generate a first transmission MIMO stream. | 03-29-2012 |
20120149320 | SPUR MITIGATION FOR WIRELESS COMMUNICATION SYSTEMS - A receiver for a wireless communication device comprising a mechanism for performing spur mitigation. A spur mitigation unit of the receiver is operable to determine a current estimate of a spur signal from an ADC output signal using a growing box filter. The spur mitigation unit can determine a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal using a power measurement unit. The spur mitigation unit can determine whether the power of the previous estimate of the spur signal is greater than the power of the current estimate of the spur signal. If the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the spur mitigation unit can remove the spur signal from the ADC output signal based on the previous spur signal estimate. | 06-14-2012 |
20120163415 | Adjacent Channel Rejection Of A CCK Blocker - An adjacent channel interference rejection mechanism is provided to detect and reject CCK-modulated signals from an adjacent channel in a wireless communication receiver. Replicas of the baseband signals are frequency-shifted and then analyzed through a series of correlations to compare the power of the correlation outputs. An adjacent channel interference of a CCK-modulated signal is determined and rejected based on the comparisons meeting a predetermined tolerance level. | 06-28-2012 |
20120224612 | Method And Apparatus Supporting Improved Wide Bandwidth Transmissions - A method for transmitting information in a wireless system is provided. In this method, the traffic on a plurality of channels can be determined. A bandwidth for a packet can be selected based on the traffic and available channel bandwidths. A modulation and a coding rate can be selected from a plurality of modulations and associated coding rates. The modulation and coding rate can be applied to a segment of the packet, wherein each segment includes one or more bandwidth units. The packet including the selected modulation and coding rate therein can be transmitted on at least one channel | 09-06-2012 |
20120269170 | Synchronization-Free Station Locator In Wireless Network - A method of providing synchronization-free station locating in a wireless network is provided. In this method, an AP having a known location sends a unicast packet to the station and notes its time of departure TOD(D). The station receives the unicast packet, notes its time of arrival TOA(D), sends an acknowledgement packet to the AP, and notes its time of departure TOD(D_ACK). The AP receives the acknowledgment packet and notes its time of arrival TOA(D_ACK). Notably, a distance between the AP and the station can be accurately determined using a first difference between the TOA(D_ACK) and the TOD(D) and a second difference between the TOD(D_ACK) and the TOA(D). A plurality of such computed distances between a plurality of APs and the station can be used to determine an accurate location of the station. | 10-25-2012 |
20120293370 | TRANSMITTER BEAMFORMING STEERING MATRIX PROCESSING AND STORAGE - A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices. | 11-22-2012 |
20130007554 | Dynamically Scaled LLR For An LDPC Decoder - A method for decoding an LDPC (low-density parity check) code word. The method includes receiving a plurality of LLR (log likelihood ratio) terms from a demodulation unit of a receiver and generating a scaling factor in accordance with at least one parameter descriptive of communication channel conditions for the receiver. The scaling factor is applied to each of the plurality of LLR terms to compute a corresponding plurality of scaled LLR terms. An iterative layered belief propagation algorithm is then executed by using the plurality of scaled LLR terms to generate decoded information. | 01-03-2013 |
20130010617 | RELATIVE POSITION DETERMINATION OF WIRELESS NETWORK DEVICES - The position of a target wireless device in a wireless communication network can be calculated relative to a predetermined number of reference wireless devices in the wireless communication network to preclude the need for fixed/absolute reference points. The reference wireless devices can be selected based, at least in part, on comparing one or more performance measurements associated with each wireless device against one or more corresponding threshold performance measurements. The position of each of the reference wireless network devices relative to each other is determined based, at least in part, on a distance between each pair of the reference wireless network devices. The relative position of the target wireless network device is determined based, at least in part, on the position of each of the reference wireless network devices relative to each other and a distance between the target wireless network device and each of the reference wireless network devices. | 01-10-2013 |
20130072217 | TIME OF ARRIVAL BASED POSITIONING SYSTEM - A TOA positioning system can be implemented that employs a calculated initial location of a wireless network device. For each of a plurality of reference wireless network devices, a distance between the wireless network device and the reference wireless network device is determined based, at least in part, on a round trip transit time between the wireless network device and the reference wireless network device. An initial location of the wireless network device can be calculated based, at least in part, on a location of each of the plurality of reference wireless network devices. A location of the wireless network device can be estimated based, at least in part, on the calculated initial location, the distance to each of the reference wireless network devices, and an initial distance calibration constant. | 03-21-2013 |
20130072218 | TIME DIFFERENCE OF ARRIVAL BASED POSITIONING SYSTEM - A TDOA positioning system that employs a calculated initial location of a wireless network device can be implemented to minimize sensitivity to the initial location of the wireless network device. For each pair of a plurality of reference network devices, the wireless network device can determine a distance difference between itself and the pair of the plurality of reference network devices based, at least in part, on round trip transit times between the wireless network device and the plurality of reference network devices. The initial location of the wireless network device can be calculated based on a location of each of the plurality of reference network devices. A location of the wireless network device can be estimated based on the calculated initial location of the wireless network device, the distance differences, and the location of each of the plurality of reference network devices. | 03-21-2013 |
20130072219 | HYBRID TIME OF ARRIVAL BASED POSITIONING SYSTEM - A hybrid TOA positioning system can be implemented to improve location estimation of a wireless network device. An initial location of the wireless network device can be calculated based on locations of a plurality of reference network devices. A first intermediate location of the wireless network device and an intermediate distance calibration constant can be determined based, at least in part, on the initial location of the wireless network device and distance between the wireless network device and each of the reference network devices. A second intermediate location of the wireless network device and a target distance calibration constant can be calculated based on the locations of the reference network devices, the first intermediate location, and/or the intermediate distance calibration constant. The location of the wireless network device can be iteratively estimated based, at least in part, on the second intermediate location and the target distance calibration constant. | 03-21-2013 |
20130072220 | HYBRID TDOA AND TOA BASED POSITIONING SYSTEM - A hybrid TDOA-TOA positioning system can be implemented to improve location estimation of a wireless network device. An initial location of the wireless network device can be calculated based on locations of a plurality of reference network devices. An intermediate location of the wireless network device can be determined based, at least in part, on the initial location of the wireless network device and distance differences between the wireless network device and each pair of the reference network devices. A second intermediate location of the wireless network device and a distance calibration constant can be calculated based on the locations of the reference network devices, the intermediate location, and/or round trip transit times between the wireless network device and each reference network device. The location of the wireless network device can be iteratively estimated based, at least in part, on the second intermediate location and the distance calibration constant. | 03-21-2013 |
20130100850 | TIME OF ARRIVAL BASED POSITIONING FOR WIRELESS COMMUNICATION SYSTEMS - A TOA positioning system can be implemented to improve location estimation of a wireless network device. A first subset of a plurality of reference wireless network devices for determining potential locations of the wireless network device and a second subset of the plurality of reference wireless network devices for determining an estimated location of the wireless network device can be selected. The first and the second subsets can be selected based on a plurality of distance measurements and an average distance and associated with each of the plurality of reference wireless network devices. The potential locations of the wireless network device can be determined based on the first subset of the plurality of reference wireless network devices. The estimated location of the wireless network device can be determined from the potential locations of the wireless network device based on the second subset of the plurality of reference wireless network devices. | 04-25-2013 |
20130121173 | METHOD AND APPARATUS FOR DETERMINING DISTANCE IN A WI-FI NETWORK - A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects. | 05-16-2013 |
20130148514 | POSITIONING TECHNIQUE FOR WIRELESS COMMUNICATION SYSTEM - A hybrid positioning system can be implemented to improve location estimation of a wireless network device when reference network devices can have different distance calibration constants. For each of a plurality of positions at which the wireless network device is placed and for each reference network device, a distance between the wireless network device and the reference network device is determined. A first positioning algorithm is executed to determine an intermediate location (corresponding to each position) of the wireless network device and a distance calibration constant for each reference network device based, in part, on a corresponding initial location of the wireless network device. A second positioning algorithm is executed to estimate a subset of the positions of the wireless network device based on the intermediate location (corresponding to the position) of the wireless network device and the distance calibration constant of each of reference network devices. | 06-13-2013 |
20130265907 | Wireless Channelization - A wireless device may be configured to operate in one of two modes where each mode uses a different channel list to perform operations in accordance with the IEEE 802.11 standard. In a first mode, the wireless device operates as an access point that sets up channels using one channel list in order to facilitate communications within a basic service set (BSS). In a second mode, the wireless device uses a second channel list to operate as a station and scan for a BSS. The first channel list contains a subset of the channels contained in the second channel list. The channels in each respective channel list may be reconfigured to adapt to changes in the configuration of a BSS and the devices communicating therein. | 10-10-2013 |
20130287069 | Transmit Beamforming With Singular Value Decomposition And Pre-Minimum Mean Square Error - Transmitting beamforming can steer a transmitting signal to reduce the interference between spaces of a MIMO system and achieves constructive combination at the receiver. One method of steering matrix calculation includes using singular value decomposition (SVD). Notably, the singular values of SVD, which represent the stream strengths in a MIMO system, are in descending order. In equal modulation, signal strength degradation makes the receive EVM of the latest stream poor and increases the probability of packet error. MMSE can be used to weight the steering vectors of the steering matrix calculated in SVD. This weighting of the singular values can balance the SNR of the streams, thereby improving packet error rate. | 10-31-2013 |
20130301764 | AUTOMATIC GAIN CONTROL TECHNIQUES FOR DETECTING RF SATURATION - Functionality can be implemented for automatic gain control (AGC) in a wireless network device to determine whether to change the gain of the wireless network device based on determining the strength of an RF signal. At various time instants, the strength of the RF signal can be compared against different thresholds to determine the presence of and severity of the saturation of the RF front end. The gain settings can be adjusted based on comparing the strength of the RF signal with a set of thresholds. This can help the wireless network device receive RF signals with little or no distortion, and can minimize RF saturation, gain compression, false detection and other performance degradation at the wireless network device. | 11-14-2013 |
20130315326 | Single Stream PhaseTracking During Channel Estimation In A Very High Throughput Wireless MIMO Communication System - In a multiple-input, multiple-output (MIMO) system, a wireless node's receive chain demodulation function is enhanced to include phase tracking. VHT Long Training Fields (LTFs) embedded in a frame preamble are used for phase tracking. Single stream pilot tones are added during transmission of VHT-LTFs. A receiver estimates the channel using the pilot tones in a first set of LTFs. A second set of LTFs are used to estimate the phase of the pilot tones using the estimated channel. The phase estimation is continuously applied to other received data tones throughout the VHT-LTFs of data symbols. Phase errors due to PLL mismatches and phase noise are reduced at reception, leading to better signal to noise ratio for different levels of drift and frequency offset. Further, MIMO channel estimation is more accurate, improving the overall wireless network when the accurate MIMO channel estimation data participates in calibration and handshake between wireless nodes. | 11-28-2013 |
20130316665 | Method And Apparatus For Coding And Interleaving For Very High Throughput Wireless Communications - A wireless transmitter can include a plurality of bandwidth modules, each bandwidth module processing data based on a predetermined frequency band. In one embodiment, such a wireless transmitter can include encoding components for receiving transmit data and generating encoded data. A multiple-input multiple-output (MIMO) stream parser can receive the encoded data and generate a plurality of MIMO streams. A first module parser coupled to a first MIMO stream can generate a first plurality of partial MIMO streams. A first bandwidth module can include a first interleaver that interleaves bits of the first partial MIMO stream and generates first interleaved data. A second bandwidth module can include a second interleaver that interleaves bits of the second partial MIMO stream and generates second interleaved data. A first inverse fast Fourier transform (IFFT) unit can combine and process the first and second interleaved data and generate a first transmission MIMO stream. | 11-28-2013 |
20130322508 | Antenna Selection Technique For Fast Diversity - A fast diversity technique using either an EESM or a capacity computation can determine antenna selection in a wireless communication device. A fast Fourier transform (FFT) for the EESM/capacity computation can be performed with consecutive samples of a single symbol period of a short training field (STF) of a packet received by each antenna. The effective signal-to-noise ratio (SNR) for each antenna can be calculated using the results of the EESM or capacity computation. The antenna with the highest effective SNR is selected. | 12-05-2013 |
20130336131 | RTT BASED RANGING SYSTEM AND METHOD - A system and method are disclosed for performing ranging operations ( | 12-19-2013 |
20140010102 | PACKET IDENTIFICATION FOR POWER SAVING IN WIRELESS COMMUNICATION NETWORKS - A network coordinator can assign an association identifier (AID) and/or a group identifier (GID) to identify a client station to which a packet is to be transmitted and to enable the client station to determine whether to receive an incoming packet. The network coordinator can determine a base AID that is representative of the network coordinator and can assign at least one AID to client stations to minimize the probability of client stations associated with proximate network coordinators being assigned the same AIDs. The network coordinator can also assign at least one GID to a group of client stations to minimize the probability of groups of client stations associated with the proximate network coordinators being assigned the same GID. The client station can analyze indications of a received AID and/or received GID to determine whether to receive the packet or whether to switch to an inactive power state. | 01-09-2014 |
20140071955 | Dynamic Sounding Control In Wifi - A method of performing dynamic sounding in a wireless communication device includes determining whether to perform sounding based on an age of current channel state information (CSI). An achievable throughput can be recorded as a reference throughput after performing the sounding. A current achievable throughput can be compared with the reference throughput. A CSI timestamp can be reset when the current throughput is above the reference throughput by a first predetermined amount, thereby prolonging a lifespan of the current CSI. The CSI timestamp can be reduced when the current throughput is below the reference throughput by a second predetermined amount, thereby reducing the lifespan of the current CSI. | 03-13-2014 |
20140073352 | METHOD FOR PRECISE LOCATION DETERMINATION - According to embodiments, methods are presented to for determining precise location of a device by exchanging a plurality of messages with one or more devices (e.g., access points or mobile devices) in vicinity. Embodiments may calculate distance between the devices using round trip time that takes to transmit and receive signals to/from each of the devices. Using definitions that account for multiple input multiple output (MIMO) transmission, the embodiments determine precise location of a device. | 03-13-2014 |
20140086369 | CYCLIC SHIFT DELAY DETECTION USING AUTOCORRELATIONS - Systems, apparatus and methods for determining a cyclic shift diversity (CSD) mode are presented. Examples use two different autocorrelations to determine a current CSD mode. Specifically, a delay-based autocorrelation and a cyclic shift-based autocorrelation are each computed then compared to each other, for example, by taking a difference of the two autocorrelations. A multipath signal leads to similar autocorrelations, where as a signal with a CSD mode enabled leads to dissimilar autocorrelations. By examining the number of peaks in the delay-based autocorrelation or the autocorrelation difference, a current CSD mode may be determined. | 03-27-2014 |
20140092819 | Scheduling Transmission For Multi-User, Multiple-Input, Multiple-Output Data - An access point determines the buffered data for each station of a plurality of stations in a BSS and groups the stations with similar station characteristics. The transmission time to the stations in a group can be apportioned. The groups can be ordered based on station characteristics and a transmission history. A sounding for a group can be performed based on the order. The MU-MIMO transmission for the group can be performed until a first condition is met. If the first condition is met, then the sounding and the MU-MIMO transmission for a next group can be performed, according to the order, until a second condition is met. The first condition can include an apportioned transmission time having expired and/or the buffers for the group being flushed. The second condition can include new data having been buffered by the AP and/or all buffered data having been transmitted. | 04-03-2014 |
20140133303 | Multicast Rate Control - A method of providing multicast rate control in a wireless communication device can include transmitting data frames to a plurality of stations in a multicast group with a first data rate. Acknowledgements (ACKs) can then be requested from a first subset of the plurality of stations. Frame losses can be determined using the ACKs from the first subset. A second data rate can be determined based on the frame losses with the first subset. A second subset of the plurality of stations can be selected based on the frame losses with the first subset. Data frames can be transmitted to the plurality of stations with the second data rate. Notably, ACKs only from the second subset of the plurality of stations are requested. Frame losses for the second subset can be determined using those ACKs. A current data rate can be adjusted based on the frame losses for the subset and at least one predetermined threshold. Data frames can be transmitted to the plurality of stations using the adjusted data rate. | 05-15-2014 |
20140160947 | Method And System for Unified Rate Adaptation For SU-BF And MU-MIMO Operation - A method of providing rate adaptation in a multi-user wireless communication system including single-user beamforming (SU-BF) and multi-user multiple-input multiple-output (MU-MIMO) is described. In this method, a master rate, which is a modulation and coding scheme (MCS) for the SU-BF, is determined. An MCS for each transmit mode is derived from the master rate using a rate mapping. Using the results from the mapping, the master rate, instead of the MCS for each transmit mode, is tracked. In one embodiment, a mapping calibration is periodically performed. | 06-12-2014 |
20140206389 | VISUAL IDENTIFIER OF THIRD PARTY LOCATION - Aspects of determining a geographical state of a target through a user device are provided. One method includes identifying at least one target associated with a target device configured to provide position data in a standard reference frame along with corresponding time values, and sending a request for access to geographical state information for at least one target. The method may further include receiving geographical state information associated with the at least one target, and generating a visual identifier of the at least one target based on the geographical state information. The visual identifier may be associated with data captured by an imaging sensor which is functionally coupled to the user device. Systems and apparatuses for determining a geographical state of a target through a user device are further presented. | 07-24-2014 |
20140211642 | Method And System For Boosting Transmission Settings Based On Signal To Interference And Noise Ratio - A method of performing transmission from an access point (AP) in a wireless communication system provides transmission setting adjustment after sounding. In this method, stations associated with the AP and having transmission data can be identified. Transmission to those stations can be performed using a predetermined transmission setting. For a first transmission after a sounding, the predetermined transmission setting can be boosted. For any transmission other than the first transmission after the sounding, a current or adjusted transmission setting can be used based on a detected PER during transmission. An adjusted transmission setting can be an MCS rate, a user-level (SU-BF, 2U-MIMO, or 3U-MIMO), or an aggregated MAC protocol data unit (AMPDU) aggregation level. A single transmission setting or a combination of settings can be used. The method can be used with any transmission setting(s), including those mapped from the Signal to Interference and Noise Ratio (SINR). | 07-31-2014 |
20140219110 | Method And System For Dynamic AMPDU Duration Control In A Wireless Communication System - A method of providing aggregated MAC protocol data unit (AMPDU) duration control in a wireless communication device includes setting an AMPDU duration. Pass/fail statistics are collected for each MPDU of an AMPDU in a time window, W. A packet error rate (PER) difference is calculated between first and last sets of MPDUs for each AMPDU in the window. An average PER difference is calculated across all AMPDUs in the window. When the average PER difference is greater than a first threshold, then the AMPDU duration is decreased. When the difference is less than a second threshold, then the AMPDU duration is increased. When the difference is within the first and the second thresholds, then the method returns to the step of collecting for a next time window. The AMPDU duration can also be adjusted based on detected Doppler and line-of-sight transmissions. | 08-07-2014 |
20140219111 | Method And System For Dual-Mode Rate Control In A Wireless Communication System - A method of performing dual-mode rate control for an access point in a wireless communication system includes a single-user mode of operation and a multi-user mode of operation. In the single-user mode, a basic rate for a station is determined based on channel conditions. In the multi-user mode, a rate for a plurality of stations is determined using tracking. The tracking includes performing a sounding for the plurality of stations. An initial multi-user current rate is then set equal to a function of a number of users and the basic rate. A transmission is sent to the plurality of stations using the current rate. A packet error rate (PER) is detected during transmission to the plurality of stations. The current rate is adjusted based on the PER. After rate adjustment, either sounding is triggered or the method returns to sending a transmission using the current rate. | 08-07-2014 |
20140235270 | TIME OF ARRIVAL BASED POSITIONING SYSTEM - A TOA positioning system can be implemented that employs a calculated initial location of a wireless network device. For each of a plurality of reference wireless network devices, a distance between the wireless network device and the reference wireless network device is determined based, at least in part, on a round trip transit time between the wireless network device and the reference wireless network device. An initial location of the wireless network device can be calculated based, at least in part, on a location of each of the plurality of reference wireless network devices. A location of the wireless network device can be estimated based, at least in part, on the calculated initial location, the distance to each of the reference wireless network devices, and an initial distance calibration constant. | 08-21-2014 |
20140254511 | REDUCING IMPACT OF CLOCK DRIFT IN WIRELESS DEVICES - Systems and methods for calculating round trip time (RTT) between two wireless devices with respective clock drifts, while lowering the impact of the clock drifts on the RTT. A first RTT in a first direction is determined between a first wireless device and a second wireless device based on a first set of one or more messages exchanged between the first wireless device and the second wireless device. A second RTT in a second direction is determined between the second wireless device and the first wireless device based on a second set of one or more messages exchanged between the second wireless device and the first wireless device, and an average RTT of the first RTT and the second RTT is computed, wherein the average RTT has a low impact of the clock drifts. | 09-11-2014 |
20140254716 | Power Amplifier System Including A Composite Digital Predistorter - A power amplifier system including a composite digital predistorter (DPD) ensuring optimized linearity for the power amplifier is described. In this system, a digital-to-analog converter (DAC), an analog filter, a first mixer, and the power amplifier are serially coupled to the composite DPD. A second mixer, a receive gain block, and an analog-to-digital converter (ADC) are serially coupled to the output of the power amplifier. A DPD training component is coupled between the inputs of the composite DPD and the ADC. The composite DPD includes a memory-based DPD, e.g., a memory polynomial (MP) DPD, a memoryless-linearizing DPD, e.g., a look-up table (LUT) DPD, and two multiplexers. | 09-11-2014 |
20140269377 | Methods Permitting A Wireless System Receiver To Determine And Report Channel Conditions To A System Transmitter - A method of providing feedback on channel observations to a transmitter includes observing a channel at a receiver based on received signals from the transmitter and determining whether a packet error rate (PER) is rising based on the observing. The receiver determines whether a rising PER is caused by channel noise or interference, and transmits a message to the transmitter indicating the cause of the rising PER. The cause may be encoded in reserved bits of a block acknowledgement (BA) frame or an Acknowledge (ACK) frame, or in a modulation coding scheme (MCS) used to transmit the message. The cause may be detected in response to SNR/RSSI level of received signals, or a number of receiver restarts. The transmitter may change the transmit rate adaptation algorithm to use a lower MCS if channel noise causes the rising PER, and a higher MCS if interference causes the rising PER. | 09-18-2014 |
20140269462 | Signature-Coded Wake-Up Transmission - A wake-up radio is configured to scan for transmissions while the radio receiver is in sleep mode. The wake-up radio detects incoming RF transmissions intended for the radio receiver by analyzing data frame characteristics in an incoming RF transmission. The data frame characteristics may contain a signature code that is unique to the radio receiver. The signature code may be based on the time duration of a sequence of orthogonal frequency division multiplex (OFDM) symbols received in a clear to send to self (CTS2S) transmission or a time duration of short interframe spaces (SIFS) used to transmit the data frames. | 09-18-2014 |
20140269994 | Systems And Methods For Antenna Management Using Per-Packet Channel Information - A wireless device that operates in accordance with the IEEE 802.11 standard receives the preamble of a packet with the highest number of receive chains enabled, thereby obtaining the highest gain, detection sensitivity and range. The wireless device determines a signal-to-noise ratio (SNR) in response to two different short training fields (STFs) in the preamble. The wireless device also determines a modulation and coding scheme (MCS) and a number of spatial streams (Nss) used to transmit the received packet in response to a signal field of the preamble. The wireless device uses these determined parameters to identify a minimum number of the receive chains required to reliably receive the packet. The wireless device uses only the identified minimum number of receive chains to perform channel estimation and receive the data portion of the packet. | 09-18-2014 |
20140269995 | Method And Apparatus For Switching Between Low-Power, Single-Chain Listen And Multiple-Chain Demodulation - A single receive chain of a MIMO receiver is activated during a low power listen mode. Upon detecting a legacy short training field (L-STF) in a received packet, the single receive chain performs a first frequency estimation, and activates one or more additional receive chains of the MIMO receiver. The MIMO receiver uses maximal ratio combining (MRC) to receive the signal using the first receive chain and the one or more additional activated receive chains, wherein the MRC is based, at least in part, on the first frequency estimation. The MIMO receiver may determine whether the received packet is a high throughput/very high throughput (HT/VHT) packet, and if not, deactivate the one or more additional receive chains. In one alternative, the additional receive chains are not activated until determining that a HT/VHT packet has been received. | 09-18-2014 |
20140273963 | WIRELESS NETWORKING-ENABLED PERSONAL IDENTIFICATION SYSTEM - A beacon message is wirelessly transmitted from a first device. The first device receives a first response to the beacon message, wherein the first response includes identification values associated with a personal identification device. A second device associated with the personal identification device is communicated with. The personal identification device is authenticated based, at least in part, on the identification values and the communication with the second device. | 09-18-2014 |
20140313922 | METHOD AND APPARATUS FOR DETERMINING DISTANCE IN A WI-FI NETWORK - A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects. | 10-23-2014 |
20150023245 | MULTI-BAND MANAGEMENT OF WIRELESS RELAYING NETWORKS - Methods, systems, devices, and apparatuses are described for wireless communications in which first type of traffic may be transmitted from a gateway access point (AP) directly to a station. Beacon signals transmitted to the station are transmitted as part of the first type of traffic. A second type of traffic may be transmitted from the gateway AP to the station via at least one relay AP. The first type of traffic may include low-throughput traffic and may be transmitted over a long-range radio link (e.g., 2 GHz band link or sub-1 GHz band link). The second type of traffic may include high-throughput traffic and may be transmitted over at least one short-range radio link (e.g., 5 GHz band link). The gateway AP may receive low-throughput traffic directly from the station and high-throughput traffic from the station via the at least one relay AP. | 01-22-2015 |
20150063283 | Single Stream Phase Tracking During Channel Estimation In A Very High Throughput Wireless MIMO Communication System - In a multiple-input, multiple-output (MIMO) system, a wireless node's receive chain demodulation function is enhanced to include phase tracking. VHT Long Training Fields (LTFs) embedded in a frame preamble are used for phase tracking. Single stream pilot tones are added during transmission of VHT-LTFs. A receiver estimates the channel using the pilot tones in a first set of LTFs. A second set of LTFs are used to estimate the phase of the pilot tones using the estimated channel. The phase estimation is continuously applied to other received data tones throughout the VHT-LTFs of data symbols. Phase errors due to PLL mismatches and phase noise are reduced at reception, leading to better signal to noise ratio for different levels of drift and frequency offset. Further, MIMO channel estimation is more accurate, improving the overall wireless network when the accurate MIMO channel estimation data participates in calibration and handshake between wireless nodes. | 03-05-2015 |
20150063500 | METHOD AND APPARATUS FOR SWITCHING BETWEEN LOW-POWER, SINGLE-CHAIN LISTEN AND MULTIPLE-CHAIN DEMODULATION - A single receive chain of a MIMO receiver is activated during a low power listen mode. Upon detecting a legacy short training field (L-STF) in a received packet, the single receive chain performs a first frequency estimation, and activates one or more additional receive chains of the MIMO receiver. The MIMO receiver uses maximal ratio combining (MRC) to receive the signal using the first receive chain and the one or more additional activated receive chains, wherein the MRC is based, at least in part, on the first frequency estimation. The MIMO receiver may determine whether the received packet is a high throughput/very high throughput (HT/VHT) packet, and if not, deactivate the one or more additional receive chains. In one alternative, the additional receive chains are not activated until determining that a HT/VHT packet has been received. | 03-05-2015 |
20150200749 | System And Method For Transmitting A Low Density Parity Check Signal - A system and method for transmitting LDPC parameters is provided. In the method, an initial number of OFDM symbols (Nsym_init) is determined for a packet that is based on the number of information bits to be delivered in the packet. An STBC value is also determined. A number of extra symbols (Nsym_ext) value is generated based on the Nsym_init value, wherein a Nsym value is based on said Nsym_init value and said Nsym_ext value. An Nldpc_ext value is determined based on the STBC value and the Nsym_ext value for purposes of determining LDPC parameters associated with the packet. | 07-16-2015 |