Abstract: Techniques are disclosed to reduce latency of processing for access points using a central controller. For example, an example method of wireless communication includes receiving, at an access point, a signal wirelessly. The method further includes filtering the signal using a first passband filter having a first bandwidth to generate a first filtered signal. The method further includes filtering the signal using a second passband filter having a second bandwidth to generate a second filtered signal, wherein the first bandwidth is less than the second bandwidth. The method further includes determining whether the signal includes a packet based on the first filtered signal and generating a control signal indicative of the determination. The method further includes transmitting the control signal and the second filtered signal to a central controller.

Abstract: The present disclosure discloses a distributed system. The distributed system includes a plurality of radio heads and a plurality of controllers disposed in one or more chassis external to the plurality of radio heads. Each of the plurality of controllers includes a baseband unit (BBU), an uplink time-division multiplexing (TDM) switch and a downlink TDM switch. The uplink TDM switch and the downlink TDM switch forward data bits between a radio head and a BBU by using TDM cells which may reduce latency relative to using Ethernet frames.

Abstract: Embodiments herein describe a network device (e.g., an access point) that dynamically arranges multi-user (MU) multiple input multiple output (MIMO) compatible client devices into MU-MIMO groups. That is, the network device uses network metrics and historical data to change the assignment of client devices in the MU-MIMO groups which may improve MU-MIMO efficiency by reducing the amount of power that leaks between the clients devices in the group. In one embodiment, the AP identifies a MU-MIMO group based on a performance evaluation such as evaluating network metric or determining if the group is underutilized. The AP can replace the identified MU-MIMO group with a substitute MU-MIMO group where the substitute MU-MIMO group is selected based on historical data corresponding to the client devices assigned to the substitute MU-MIMO group.

Abstract: The present disclosure discloses a distributed system. The distributed system includes a plurality of radio heads and a plurality of controllers disposed in one or more chassis external to the plurality of radio heads. Each of the plurality of controllers includes a baseband unit (BBU), an uplink time-division multiplexing (TDM) switch and a downlink TDM switch. The uplink TDM switch and the downlink TDM switch forward data bits between a radio head and a BBU by using TDM cells which may reduce latency relative to using Ethernet frames.

Abstract: Techniques are disclosed to synchronize wireless signal transmission by endpoints controlled by a central controller. For example, an example method of wireless communication includes receiving, at a first device, over a wired medium between the first device and a second device, a plurality of packets from the second device. Each of the plurality of packets comprises data representative of a portion of a signal corresponding to a wireless medium. The method further includes receiving, at the first device, from the second device over the wired medium a synchronization signal based on a common master clock at the second device. The method further includes synchronizing, at the first device, a local clock of the first device to the common master clock based on the synchronization signal. The method further includes reconstructing the signal corresponding to the wireless medium based on the plurality of packets and the synchronized local clock.

Abstract: The present disclosure discloses a central controller controlling multiple radio heads (RHs) in a network. The central controller generates network information for the radio heads based on a probe request transmitted from a network device and received by one or more of the radio heads. The central controller calculates a respective metric value for each of the radio heads based on the network information. The metric value indicates a capability of a radio head to serve the network device. The central controller selects a subset of radio heads from the multiple radio heads to send a probe response to the network device based on the metric values.

Abstract: Embodiments herein describe using an intermediate distribution frame (IDF) which is connected between a central controller and a plurality radio heads which each include at least one antenna for wireless communication with a user device. Instead of running separate cables to each of the radio heads, a single cable can be used to connect the IDF to the central controller and then separate cables can be used to connect the IDF to the radio heads. If the IDF is disposed near the radio heads, the amount of cables can be reduced. Moreover, the IDF may recover a clock signal used by the central controller and forward that clock to the plurality of radio head in order to synchronize the radio heads to the central controller.

Abstract: The present disclosure discloses that a device uses precoding to transmit independent data streams to existing users and additional independent data streams to one or more new users simultaneously. During a first transmission of a first one or more data streams that are precoded using a first precoding matrix, the device determines to transmit a second one or more data streams in a second transmission. Before the first transmission is complete, the device calculates a combined precoding matrix for precoding the first one or more data streams and the second one or more data streams. The device transmits the first one or more data streams in the first transmission and the second one or more data streams in the second transmission simultaneously using the combined precoding matrix.

Abstract: Techniques are disclosed to reduce latency of processing for access points using a central controller. For example, an example method of wireless communication includes receiving, at an access point, a signal wirelessly. The method further includes filtering the signal using a first passband filter having a first bandwidth to generate a first filtered signal. The method further includes filtering the signal using a second passband filter having a second bandwidth to generate a second filtered signal, wherein the first bandwidth is less than the second bandwidth. The method further includes determining whether the signal includes a packet based on the first filtered signal and generating a control signal indicative of the determination. The method further includes transmitting the control signal and the second filtered signal to a central controller.

Abstract: Embodiments herein describe a network device (e.g., an access point) that dynamically arranges multi-user (MU) multiple input multiple output (MIMO) compatible client devices into MU-MIMO groups. That is, the network device uses network metrics and historical data to change the assignment of client devices in the MU-MIMO groups which may improve MU-MIMO efficiency by reducing the amount of power that leaks between the clients devices in the group. In one embodiment, the AP identifies a MU-MIMO group based on a performance evaluation such as evaluating network metric or determining if the group is underutilized. The AP can replace the identified MU-MIMO group with a substitute MU-MIMO group where the substitute MU-MIMO group is selected based on historical data corresponding to the client devices assigned to the substitute MU-MIMO group.

Abstract: In an example embodiment, a channel that includes a plurality of sub-channels is sampled to detect pulses indicative of a presence of a radar signal. A frequency for the radar signal is determined. If the frequency of the radar signal maps to a selected subset of the plurality of sub-channels, the selected subset of the plurality of sub-channels are determined to be unavailable due to radar, while the remaining sub-channels remain available for use. The selected subset of the plurality of sub-channels determined to be unavailable due to radar may be selectively returned for use after the radar signal is no longer detected for a predetermined selected time period.

Abstract: In an example embodiment, a channel that includes a plurality of sub-channels is sampled to detect pulses indicative of a presence of a radar signal. A frequency for the radar signal is determined. If the frequency of the radar signal maps to a selected subset of the plurality of sub-channels, the selected subset of the plurality of sub-channels are determined to be unavailable due to radar, while the remaining sub-channels remain available for use. The selected subset of the plurality of sub-channels determined to be unavailable due to radar may be selectively returned for use after the radar signal is no longer detected for a predetermined selected time period.

Abstract: A spectrum analysis engine (SAGE) that comprises a spectrum analyzer component, a signal detector component, a universal signal synchronizer component and a snapshot buffer component. The spectrum analyzer component generates data representing a real-time spectrogram of a bandwidth of radio frequency (RF) spectrum. The signal detector detects signal pulses in the frequency band and outputs pulse event information entries output, which include the start time, duration, power, center frequency and bandwidth of each detected pulse. The signal detector also provides pulse trigger outputs which may be used to enable/disable the collection of information by the spectrum analyzer and the snapshot buffer components. An alternative pulse detection module is provided that tracks signal pulses by comparing peak data from successive FFT cycles with existing signal pulse data that is derived from comparing peak data for prior FFT cycles.

Abstract: A spectrum analysis engine (SAGE) that comprises a spectrum analyzer component, a signal detector component, a universal signal synchronizer component and a snapshot buffer component. The spectrum analyzer component generates data representing a real-time spectrogram of a bandwidth of radio frequency (RF) spectrum. The signal detector detects signal pulses in the frequency band and outputs pulse event information entries output, which include the start time, duration, power, center frequency and bandwidth of each detected pulse. The signal detector also provides pulse trigger outputs which may be used to enable/disable the collection of information by the spectrum analyzer and the snapshot buffer components. An alternative pulse detection module is provided that tracks signal pulses by comparing peak data from successive FFT cycles with existing signal pulse data that is derived from comparing peak data for prior FFT cycles.

Abstract: An intelligent spectrum management (ISM) system and method are provided that includes sophisticated features to detect, classify, and locate sources of RF activity. The system comprises one or more sensors positioned at various locations in a region where activity in a shared radio frequency band is occurring and a server coupled to the sensors. Each sensor monitors communication traffic, such as IEEE WLAN traffic, as well as classifies non-WLAN signals occurring in the frequency band. The server receives data from each of the plurality of sensors and that executes functions to process the data supplied by the plurality of sensors. In particular, the server aggregates the data generated by the sensors and generates event reports and other configurable information derived from the sensors that is interfaced to a client application, e.g., a network management station.

Abstract: Monitoring for unauthorized RF energy emitted or transmitted in a particular zone or portion of a building, etc. Radio frequency energy is received in a region that encompasses a zone in which it is desired to monitor for unauthorized radio frequency energy. At least one characteristic of the received radio frequency energy is analyzed to determine whether unauthorized radio frequency energy is occurring in the zone. Unauthorized RF energy may be detected by analyzing at least one spectral characteristic of the received radio frequency energy and comparing the at least one spectral characteristic with data associated with authorized and/or unauthorized radio frequency energy. Alternatively, signal classification techniques can be applied to data derived from the received radio frequency energy to classify by type signals contained in the received radio frequency energy.

Abstract: Several techniques are provided for use by wireless devices to avoid interference with signals that are of a periodic or quasi-periodic nature that may operate in the same frequency band and proximity. In some cases, the periodic signals are detected and their timing is determined so as to predict when a next interfering event will occur. Devices that are affected by the periodic signal (such as an affected device with information to be transmitted or devices that have information to be transmitted to the affected device) are controlled to prevent transmissions during the interfering intervals. In addition, a process is provided to dynamically fragment a transmit frame of information to transmit part of the information before the interfering interval and the remainder of the information after the interfering interval, rather than waiting to transmit the entire frame until after the interfering interval.

Abstract: A system and method for determining the location of a source (target device) of a wireless radio signal of an unknown or arbitrary type for which a signal correlator is not known or available. The target device's signal is received at a plurality of known locations to generate receive sample data representative thereof at each known location. Receive signal data samples associated with the target device's signal at one of the plurality of known locations is selected to be used as a reference waveform. For example, information concerning the target device's signal received at each known location is compared to determine the known location that best receives it. The receive signal sample data obtained by the known location that best receives the target device's signal is used as the reference waveform. A measurement experiment is run in which the target device's signal is followed or preceded relatively close in time by a transmission of a reference signal.

Abstract: Techniques to avoid interference with a frequency hopping signal that are of a periodic or quasi-periodic nature that may operate in the same frequency band and proximity with other devices. For example, the frequency hopping signals may be transmitted by Bluetooth devices operating in the same frequency band as IEEE 802.11 WLAN devices. When a frequency hopping interfering signal is detected, sufficient knowledge of the frequency hopping sequence is derived without obtaining state of a frequency hop sequence from information carried in the frequency hopping signal. This knowledge is used to predict or determine when future transmissions of the frequency hopping signal will be present in a particular frequency channel of concern.

Abstract: Several techniques are provided for use by wireless devices to avoid interference with signals that are of a periodic or quasi-periodic nature that may operate in the same frequency band and proximity. In some cases, the periodic signals are detected and their timing is determined so as to predict when a next interfering event will occur. Devices that are affected by the periodic signal (such as an affected device with information to be transmitted or devices that have information to be transmitted to the affected device) are controlled to prevent transmissions during the interfering intervals. In addition, a process is provided to dynamically fragment a transmit frame of information to transmit part of the information before the interfering interval and the remainder of the information after the interfering interval, rather than waiting to transmit the entire frame until after the interfering interval.