Facebook, Inc.

Ali Yazdan Panah

Karthik Yogeeswaran

Sam Padinjaremannil Alex

Qi Qu

Ahmed Alkhateeb

Sungwoo Park

Yael Gregory Maguire

Abhishek Tiwari

Pratheep Bondalapati

Hongyu Zhou

Viswanath Poosala

Yan Yan

Talha Ahmed Khan

Jeonghun Park

Massive MIMO systems provide impressive spectral efficiencies through beam forming techniques such as Zero-Forcing Precoding (ZFP). Unfortunately, ZFP imposes a considerable computational burden for each additional user. Relationships between the antennas, the users, and the environment must be rapidly, and accurately, reassessed during ZFP on an ongoing basis. Brute force approaches to these reassessments may be unfeasible for certain hardware and design conditions. Accordingly, various of the proposed embodiments implement representational optimizations which reduce the computational burden for each reassessment. Some embodiments employ 'dynamic sectorization', whereby the serviced environment is divided into regions and the corresponding representation is modified to reduce the computations of each reassessment. A backplane, antenna separation/directivity and thresholds for environment noise may each be adjusted to reduce the computational burden.

Optimizations for zero-forcing precoding

Embodiments are disclosed for improving precoder-matrix computations in a MIMO base station. Particularly, various embodiments implement methods for interpolating pilot signal results from multiple calibration transmissions. A subchannel of a resource block is selected as an anchor subchannel and the channel matrices for each subchannel are then determined using weights associated with each subchannel that are determined from the subchannel's distance away from the anchor subchannel. Selecting variable subchannels allows the accuracy of the channels matrices for the subchannels to be tailored where more accuracy is desired.

Estimating signals in sub-sampled systems

Apparatuses, methods, and systems for jointly selecting a plurality of antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from a base station to a device are disclosed. One apparatus includes a base station, wherein the base station includes a plurality of N antennas configured to transmit and receive electromagnetic signals, and a controller connected to the plurality of N antennas through a plurality of RF (radio frequency) chains. The controller is configured to jointly select a plurality of M of the plurality of N antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from the base station to a device based on an activation threshold of the device and a saturation level of the device.

Joint selection of antennas and transmission power level for wireless energy transfer

Apparatuses, methods, and systems for selecting an ADC for each RF chain of an RRU are disclosed. One embodiment of the RRU includes a plurality of antennas and a plurality of RF chains configured to receive a plurality of wireless signals, A plurality of outputs of the RRU connected to a front-haul, wherein the front-haul electrically connects the plurality of outputs of the RRU to a baseband unit (BBU), wherein each of the outputs is connected to an output of one of a plurality of ADCs. Further, the RRU selects a one of the plurality of ADCs having the plurality of ADC resolutions for each of the RF chains based on the capacity of the front-haul, a channel gain of each of the RF chains, and a performance parameter of the RRU. A switch connects each of the RF chains to a corresponding one of the plurality of ADCs.

Selection of an ADC for each RF chain of a remote radio head unit

Apparatuses, methods, and systems zone precoding are disclosed. One method includes training a transmission channel between a base station and each of a plurality of users and determining a precoding of transmission signals to each of the plurality of users from the base station. The training includes determining a transmission zone for each of the plurality of users, wherein the transmission zone includes an angle of direction of a directional beam to each user, and a deviation of the angle of direction. Determining a precoding of transmission signals to each of the plurality of users from the base station, includes determining an initial precoding for each of the users based on the transmission zone associated with the user, and constructing the precoding for each user by adjusting the initial precoding for each user based on the transmission zone determined for each of the other users.

Zone precoding

Apparatuses, methods, and systems for MIMO inter-stream interference cancellation are disclosed. One method includes determining a channel matrix between a plurality of transmitting antennas of a transmitter and a plurality of receiving antennas of a receiver, determining a plurality of channel propagation delays based on a propagation delay between each of the plurality of transmitting antennas and each of the plurality of receiving antennas, preprocessing, by the transmitter, streams of symbols for each transmitting antenna for transmission based on the plurality of channel propagation delays and based on the channel matrix, and transmitting, by the transmitter, the preprocessed symbol streams through the plurality of transmitting antennas.

MIMO (multiple-input, multiple-output) inter-stream interference cancellation

Apparatuses, methods, and systems for precoding multi-carrier signals are disclosed. One method includes obtaining a transmission channel matrix between a terminal and a plurality of separate users, wherein the transmission channel matrix includes channel estimates for a plurality of subcarriers of the multi-carrier signal. A channel dimension reduction matrix is determined based upon a composite of the channel estimates for the plurality of subcarriers, wherein dimensions of the channel dimension reduction matrix are less than dimensions of the transmission channel matrix. The method further includes determining a precoding matrix for the terminal based on the channel dimension reduction matrix, wherein the precoding matrix is multi-carrier signal independent, determining an effective channel based on a channel estimate of the transmission channel and based on the precoding matrix of the terminal, and determining a precoding matrix for the central processing unit based on the effective channel.

Multi-layered precoding

Techniques for securing the delivery of an audio message on a device are described. A method may include presenting a visual representation associated with an audio file in a user interface view of an application executing on a first mobile device and receiving a control directive to select the visual representation. The method may include retrieving, from a data store, an indicator of the audio file associated with the selected visual representation; constructing, by the application, a first message comprising a first field to hold an electronic message address for a recipient and a second field to hold the indicator of the audio file associated with the selected visual representation; and sending the first message to the electronic message address of the recipient for delivery to a destination second mobile device. Other embodiments are described and claimed.

Techniques for communication using audio stickers

Some embodiments includes a method of forming a local area mesh network at a computing device. The method can include: receiving a connection request from a first neighbor device utilizing a Wi-Fi Direct (WFD) discovery protocol; forming a first peer-to-peer (P2P) connection with the first neighbor device utilizing WFD, wherein the computing device is set as a group owner of the first P2P connection; generating a notice of absence schedule to send to the first neighbor device indicating suspension intervals of the first P2P connection during which the computing device is suspended from being the group owner of the first P2P connection; forming a second P2P connection with a second neighbor device utilizing WFD, wherein the second neighbor device is set as a group owner of the second P2P connection, wherein the first P2P connection and the second P2P connection constitute part of a mesh communication network.

Local area network meshing

Apparatuses, methods, and systems for beamforming in antenna systems are disclosed. A method includes determining an unconstrained analog precoding matrix (F), wherein the unconstrained analog precoding matrix (F) is determined based on M dominant eigenvectors of the sum of spatial channel covariance matrices of K users, and wherein K indicates a number of users communicating with a base station. The method further includes determining a constrained analog precoding matrix (F) based on the unconstrained analog precoding matrix (F), determining a compensation matrix (F), digitally multiplying K inputs with a multiple-input multiple-output (MIMO) precoding matrix (F) generating M outputs, digitally multiplying the M outputs with the compensation matrix (F) generating M compensation outputs, generating M analog frequency-up-converted signals based on the M compensation outputs, and analog multiplying the M analog frequency-up-converted signals with the analog precoding matrix (F) generating N output signals for transmission, wherein N is greater than M.

Beamforming in antenna systems

Various of the disclosed embodiments relate to line-of-sight (LOS), e.g., optical, based networks. Systems and methods are provided for connecting nodes based on their topological position in a line-of-sight communication network. Some embodiments may represent each node by a 'backbone' and a 'subnetwork' rank. The determination of a node's rank can prevent the formation of isolated &#x201c;islands&#x201d; of nodes, cut off from the backbone. The ranking can also provide a total ordering of nodes relative to the &#x201c;fiberpop&#x201d; node which can be used for healing and routing behaviors.

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San Francisco, CA, United States of America

Ali Yazdan Panah