Microsoft Technology Licensing, LLC

Other

Dinan Srilal Gunawardena

Peter Bernard Key

Bozidar Radunovic

Eno Thereska

Richard Harper

Alexandre Proutiere

James William Scott

Laurent Massoulie

Ranveer Chandra

Austin N Donnelly

Christos Gkantsidis

Alf Zugenmaier

Jacob Scott

Milan Vojnovic

Fan Yang

Stuart Taylor

Richard John Black

Thomas Karagiannis

Shao Liu

Michael Alex Schroeder

Shobana Balakrishnan

Gregory O'Shea

Philip Charles Gosset

Mudit Goel

Pablo Rodriguez Rodriguez

Peter Marbach

Wenjun Hu

Timothy Regan

Dave Maltz

Nikhil Singh

Milan Vojnović

Richard James Cruise

A distributed file system for devices is described. In an embodiment, each data element stored on one of the devices has an associated location and availability attribute. The location attribute is stored co-located with the data element. The availability attribute and a copy of the location attribute are stored by a metadata service. When a client on a device needs to access a data element, it sends a request to the metadata service to find the location of the data element. If the data element is available, this information is provided to the client and this may involve waking a dormant device which holds the data element. Where the data element is not available, read only access may be granted to a cached copy of the data element. Where replication is used and one of the devices holding a replica is unavailable, the system may use write off-loading.

Distributed file system

Wireless protocols in the unlicensed spectrum are developed for different requirements in terms of transmit range and power, which makes it difficult for multiple nodes having disparate transmit ranges to coexist in the same unlicensed spectrum. A short-range wireless node uses adaptive preambles to signal presence to long-range wireless nodes outside of its transmit range. In addition, a long-range wireless node detects an adapter preamble and backs-off transmissions for reservation period dedicated to short-range nodes.

Long-range nodes with adaptive preambles for coexistence

Short-range nodes with adaptive preambles for coexistence

A decentralized relaying algorithm for mobile devices is described. In an embodiment, a mobile device acts as a relay within a network of mobile devices and on contact with a source device downloads messages from the source according to a locally stored relaying probability for each channel of information within the network. These messages are subsequently downloaded to another device which is the end user of the message. Where the relay does not download the message from the source as a result of the decision made based on the relaying probability, a virtual message is downloaded which comprises metadata only and not the payload of the message. The relay updates the stored relaying probabilities for each channel based on locally observable information which includes feedback received from mobile devices to which the relay has downloaded messages. The feedback identifies unique paths for the payload of messages through the network.

Decentralized relaying algorithm for mobile devices

Mobile device localization using audio signals is described. In an example, a mobile device is localized by receiving a first audio signal captured by a microphone located at the mobile device and a second audio signal captured from a further microphone. A correlation value between the first audio signal and second audio signal is computed, and this is used to determine whether the mobile device is in proximity to the further microphone. In one example, the mobile device can receive the audio signals from the further microphone and calculate the correlation value. In another example, a server can receive the audio signals from the mobile device and the further microphone and calculate the correlation value. In examples, the further microphone can be a fixed microphone at a predetermined location, or the further microphone can be a microphone located in another mobile device.

Mobile device localization using audio signals

Dynamic channel and transmission rate selection is described. In an example, a communication resource for transmitting data to a receiver is selected from several channels, each having several associated rates. The selection comprises storing a weighting factor for each channel/rate combination, monitoring transmission performance on a selected channel and rate, and inferring performance for other rates on the selected channel from the monitored performance. Each weighting factor is then updated using the monitored and inferred performances, and used to select a channel/rate combination for subsequent transmission. In another example, a communication device comprises a transmitter, a processor, and a memory arranged to store a weighting factor associated with each receiver, channel and rate combination. The transmitter sends data to a receiver using one channel and rate, and the processor monitors the performance, updates the weighting factors accordingly, and selects a receiver, channel and rate combination for subsequent transmission.

Dynamic channel and transmission rate selection

A data store including a file location attribute is described. In an embodiment, the location attribute for a data element, such as a file or database record, is stored with the bytes of data and records the geographic location of the data element. Writing to this attribute is limited to a single trusted entity, such as an operating system, to ensure that the location data can be trusted and when a data element is moved or replicated, the attribute is updated to reflect the new location of the data element. This location data is made available to users and applications by a metadata service which tracks the locations of data elements and responds to requests from users. Access control policies can been defined in terms of location and stored at the metadata service and the metadata service can then enforce these policies when responding to requests.

Data store including a file location attribute

An improved network protocol for mitigating network amplification attacks is provided. The absolute network load that any transient distributed attack can cause is bounded based on a resource crediting scheme. The protocol accumulates 'credit' upon reception and detection of candidate attack request packets, and draws against that credit when transmitting responsive packets. In some implementations, the time frame of such an attack is also bounded using time limits applied to a resource crediting scheme. Other resources may also be bounded by the resource crediting scheme, including without limitation CPU utilization, storage capacity, power, etc.

Network amplification attack mitigation

Control of background data transfers is described. In an embodiment, a background data transfer is controlled at a receiver node by measuring a time period taken to receive from a sender node a data sequence of the same size as a receive window. The time period is used to evaluate available network capacity, and the network capacity used to calculate a new window size. The new window size is applied and communicated to the sender node. In another embodiment, a background data transfer is controlled at a receiver node by measuring a quantity of data received from a sender node during a first control interval. The measured quantity is used to evaluate available network capacity, and the network capacity used to calculate a new receive window size and a second control interval duration. The new window size is applied for the second control interval, and communicated to the sender node.

Control of background data transfers

Systems, devices, and methods for associating network devices with users are described, which can facilitate establishing a secure user to network device association. In various embodiments, the disclosed subject matter facilitates devices providing indication of location and device identity to a user and recognizing the user is in the proximity of the device. The disclosed subject matter provides efficient and secure device to user association and can facilitate performing customized actions based on the nature of the association.

Associating network devices with users

In example methods and algorithms, a node in a wireless mesh network calculates an estimated cost for a packet flow through the node. The estimation may be based on the back-log at the node and the cost of downstream neighbor nodes for the flow. Further, selection of a downstream flow and a downstream neighbor node may be based on the estimation. A packet re-ordering algorithm is also described which intercepts packets received at a node and delays delivery of the packet to the IP layer if an earlier packet in the sequence of packets has not been received.

Path estimation in a wireless mesh network

Full-duplex wireless communication is described. In an embodiment, a transceiver device having a transmitter circuit and a receiver circuit receives a data packet sent over a shared communication medium. In the embodiment, the transceiver reads the header of the data packet and starts transmitting an output signal on the same shared communication medium. Embodiments are described in which, whilst the transmission of the output signal is ongoing, the transceiver receives an impaired data signal which is made up of the payload of the data packet and interference from the output signal. In the embodiment, a cancellation signal is derived from the output signal, and this is combined with the impaired data signal to remove the interference and recover the payload of the data packet.

Full-duplex wireless communications

Growing community of inventors

Cambridge, United Kingdom

Dinan Srilal Gunawardena