Cisco Technology, Inc.

Yanxin Na

Hang Jin

Robert Charles Meier

Tak Ming Pang

Emburey Samrex Edward

Li Guo

Genyuan Wang

Daniel Wee

Matthew Aaron Silverman

David Stuart Kloper

John Grabner

Hanqing Lou

Narayan Vishwanathan

Bror Peterson

Jeffrey R Adams

A method is performed at a mesh access point (MAP) in a wireless mesh network including access points (APs) of a spanning tree being divided among multiple Internet Protocol (IP) subnets. The method includes receiving from a first parent AP to which the MAP is a child a first IP subnet identifier indicating the first IP subnet to which the first parent AP belongs. The method also includes obtaining a first IP address associated with the first IP subnet, roaming from the first to a second parent AP, receiving from the second parent AP a second IP subnet identifier indicating a second IP subnet to which the second parent AP belongs, determining if the first and second parent APs are both part of the same IP subnet, and determining whether to maintain connectivity with a current controller or establish connectivity to a new controller based on results of the determining.

Wireless mesh network including resilient backhaul links and WLAN traffic local switching

A wireless mesh network includes mesh access points (mesh APs) and a root access point (RAP) forming a root of a tree of the mesh APs in which the mesh APs are linked back to the RAP through parent-child relationships over wireless backhaul links. A mesh AP provides access to the mesh network via connections to wireless clients in one or more wireless local area networks (WLANs) served by the mesh AP. The mesh AP stores mappings between the one or more WLANs served by the mesh AP and one or more virtual local area networks (VLANs) configured on a wired network and to which the WLANs are assigned. The mesh AP receives mappings between the VLANs configured on the wired network and WLANs served by the mesh AP as known by the RAP. If the stored mappings and the received mappings differ, the mesh AP updates the stored mappings with the received mappings that differ from the stored mappings.

A wireless mesh network includes mesh APs and a root AP forming a root of a tree of the mesh APs in which the mesh APs are linked back to the root AP over wireless backhaul links. The root AP has a wired connection to a wired network. An AP detects a loss of connectivity to a controller through which traffic associated with the AP is normally routed to and from the wired network. In response, if the AP is the root AP, the root AP operates as a proxy controller through which the traffic may be routed. The AP maintains connectivity with parent and child APs over the wireless backhaul links.

A channel sounding scheme is presented herein that relies on a combination of a first channel sounding procedure and a second channel sounding procedure. The first channel sounding technique is one that involves an exchange of dedicated channel sounding related signals to determine channel conditions between the first wireless communication device and the particular second wireless communication device. The second channel sounding technique is one in which channel conditions are implicitly discovered from any signals transmitted by the particular second wireless communication device to the first wireless communication device. A first wireless communication device computes updates to steering matrix information used for beamforming one or more signal streams to a particular second wireless communication device based on a combination of the first channel sounding technique and the second channel sounding technique.

Explicit and implicit hybrid beamforming channel sounding

Techniques are provided herein for improving multiple-input multiple-output (MIMO) wireless communications, and in particular to dynamically determining when to switch MIMO transmission modes on a communication link between two devices that are capable of supporting multiple MIMO transmission modes. A base station receives from a client device one or more signals containing information representing a first signal-to-noise ratio (SNR) measurement and a second SNR measurement made by the client device. The first SNR measurement is associated with a first MIMO transmission mode and the second SNR measurement is associated with a second MIMO transmission mode. The base station computes a MIMO channel quality indicator from the first SNR measurement and the second SNR measurement, and evaluates the MIMO channel quality indicator to determine whether to switch MIMO transmission modes for transmissions to the client device.

MIMO mode switch management for beamformed MIMO systems

Techniques are provided herein to enable collaborative spatial multiplexing in a wireless communication system. At M plurality of antennas of a first wireless communication device, N plurality of spatially multiplexed transmissions are received from corresponding ones of N plurality of second wireless communication devices. The first wireless communication device produces M receive signals from the transmissions received at the M plurality of antennas. The first wireless communication device applies beamforming weight vectors to the M receive signals and in so doing produces N signals or signal streams, where N is less than or equal to M. The first wireless communication device then recovers the modulated data for each of the transmissions from the N signals.

Beamforming spatial de-multiplexing for collaborative spatially multiplexed wireless communication

Techniques are provided herein to generate beamforming weight vectors for transmissions to be made from a first wireless communication device, e.g., a base station, to a second wireless communication device, e.g., a client device. The first device has a plurality of antennas and receives uplink transmissions from the second device, each uplink transmission comprising a group of frequency subcarriers. The first device computes channel information from the received uplink transmission and computes one or more trigonometric waveforms determined to approximate the channel information. One or more downlink beamforming weight vectors are computed at any given frequency subcarrier (thus in any frequency subband) by interpolation using the one or more trigonometric waveforms.

Beamforming weight generation using adaptive trigonometric waveform interpolation techniques

Signal sequence detection techniques are provided to enable a wireless communication device to detect presence of a sequence, such as a preamble sequence, in the presence of other transmission that would otherwise interference with the ability of the device to detect the sequence. At the wireless communication device, energy in a frequency band is received and a receive signal is generated from the received energy. The receive signal is divided into windows of a predetermined time duration. A running auto-correlation of the receive signal is computed to produce an auto-correlation sequence for a sequence to be detected in the receive signal. Data representing a mask is generated for a window based on the receive signal. The mask is applied to the auto-correlation sequence to filter out portions of the auto-correlation sequence that are outside of the mask. A position of sequence, e.g., a preamble sequence, in the receive signal is detected based on a position of a peak in the auto-correlation sequence after application of the mask.

Signal sequence detection in presence of carrier or narrow band transmissions

Techniques are provided to compute the physical carrier to interference-plus-noise ratio (PCINR) in a wireless communication system. In one embodiment, the PCINR is computed from received signals in active subcarriers in a preamble of a wireless transmission frame. In another embodiment, the PCINR is computed from a block of contiguous subcarriers in a symbol of received wireless transmission. The PCINR may be used to adjust a system parameter associated with wireless communication between wireless communication devices.

Physical carrier to interference-plus-noise ratio techniques for wideband wireless communication networks

Techniques are provided herein to compute beamforming weight vectors for pre-coding broadcast signals. First, system parameters for a device configured to wirelessly transmit one or more broadcast signals via a plurality of antennas are determined. Based on the system parameters a plurality of beamforming weight vectors are computed. The beamforming weight vectors are computed such that they have omni-directional like characteristics and such that correlation between beamforming weight vectors is relatively low. The plurality of beamforming weight vectors are applied to each of the one or more broadcast signals for transmission by the device to produce beamformed transmit signals for transmission via the plurality of antennas.

Omni-directional and low-correlated pre-coding broadcast beamforming

Techniques are provided to improve receive beamforming at a wireless communication device that receives energy in a frequency band at M plurality of antennas, where the received energy includes desired signals and interference signals. The wireless communication device has no knowledge of the spatial signatures of the desired signals and interference signals. A weighted sum signal vector is computed from the received signals and a covariance matrix is computed from the receive signals. Eigenvalue decomposition of the covariance matrix is computed to obtain M eigenvalues of corresponding M eigenvectors of the covariance matrix. A correlation rate is computed between the M eigenvectors and the weighted sum signal vector. A combined receive beamforming and nulling weight vector is computed from the M eigenvectors and the weighted sum signal vector and based further on the correlation rate. The combined receive beamforming and nulling weight vector is applied to the received signals so as to receive beamform the desired signals and null out the interference signals.

Combined beamforming and nulling to combat co-channel interference

Techniques are provided for wireless communication between a first wireless communication device and a second wireless communication device. At a plurality of antennas of the first wireless communication device, one or more signals transmitted by a second wireless communication device in a first frequency band are received. Beamforming weights are computed from information derived from the signals received at the plurality of antennas using one or more of a plurality of methods without feedback information from the second wireless communication device about a wireless link from the first wireless communication device to the second wireless communication device. The beamforming weights are applied to at least one transmit signal to beamform the at least one transmit signal for transmission to the second wireless communication device in a second frequency band.

Open-loop beamforming MIMO communications in frequency division duplex systems

Techniques are provided to facilitate the computation of beamforming weights used by a first communication device when sending a transmission via a plurality of antennas to a second communication device where knowledge of the behavior of the channel between the first communication device and the second communication device is limited to a portion of a wide frequency band. A frequency extrapolation beamforming weight computation process is provided to derive knowledge in other frequency subbands based on information contained in the received transmission from the second communication device.

Frequency band extrapolation beamforming weight computation for wireless communications

Techniques are provided for generating downlink beamforming weighting vectors by using channel information about one or more uplink sub-channels in a wireless communications network in the case of frequency mismatch between downlink channels and uplink channels for a specific user. The method comprises calculating an average channel covariance matrix of one or more uplink sub-channels assigned to a specific user, dividing a sector of a cell into a plurality of sub-sectors, transforming the average channel covariance matrix into a plurality of average sub-sector channel covariance matrices and obtaining an average uplink beamforming weighting vector group corresponding to the plurality of sub-sectors, selecting direction of arrival (DOA) sub-sectors from the plurality of sub-sectors by using the plurality of average sub-sector channel covariance matrices, and computing a time delay sequence for the DOA sub-sectors, and generating downlink beamforming weighting vectors by using the average uplink beamforming weighting vectors corresponding to the DOA sub-sectors and the information derived from the time delay sequence.

Method for generating downlink beamforming weighting vectors

Ranging code detection techniques are provided. Energy is received at a plurality of antennas of a first wireless communication device and received signals are generated from the received energy. The received energy comprises a ranging transmission from one or more second wireless communication devices, wherein each ranging transmission comprises a ranging code selected from a set of possible ranging codes. A ranging code specific receive beamforming weight vector is generated for a ranging code in the set of possible ranging codes from the received signals. The ranging code specific receive beamforming weight vector is applied to corresponding ranging code specific signals derived from the received signals to produce ranging code specific beamformed signals. The ranging code specific beamformed signals are correlated to produce correlation results. A determination is made as to whether the ranging code is present in the received energy based on the correlation results.

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Plano, TX, United States of America

Yanxin Na