Cisco Technology, Inc.

Espan Systems

Sandeep Shetty

Shmuel Shaffer

Jean-Philippe Vasseur

Charles Okwudiafor

Lu Qian

Neil Robert Diener

Rajneesh Kumar

Douglas Chan

Jonathan W Hui

David Stuart Kloper

David Sheldon Stephenson

Bretton Lee Douglas

Tak Ming Pang

Tak Ming Francis Pang

Wenfeng Huang

Hari Narayanan Rangarajan

Igal Gutkin

Richard Gustav Geiger

Predrag Tosic

Saurabh Bhasin

Suyog Deshpande

A method determines wireless radio locations in a network. The method includes identifying a group of location fixed radios in a network. Radios in the network with known location coordinates and/or known timing bias error values are grouped. RTT values are determined between each radio in the group and radios outside the group. Timing bias error values are determined for each radio outside the group. The timing bias error value for each radio outside the group of radios with known location coordinates and known timing bias error values is based on the determined RTT values. Location coordinates are estimated for each radio outside the group. A request is received for access to the network from a mobile radio device. The known location coordinates and estimated location coordinates of radios are used to determine a distance of the mobile radio device from one of the location fixed radios.

High precision distance computations for FTM estimates

In an example embodiment, an apparatus comprising an interface configured to communicate with at least one wireless transceiver, and a controller coupled to the interface. The controller is configured to determine a predefined characteristic such as current load and/or interference for a wireless channel associated with the at least one wireless transceiver. The controller is operable to suppress sending a probe response in response to the at least one wireless transceiver receiving a probe request, wherein how often probe responses are suppressed is based on the predefined characteristic for the wireless channel.

Load based probe response scheduling

In one embodiment, a particular node in a shared media computer network may determine a set of network parameters for the network, and a timing of super-frames in the network, each super-frame having one or more frames, each frame divided into a plurality of timeslots. In addition, the particular node computes a discovery scheduling function using its own identification to determine in which particular timeslot of the frames to transmit a network discovery packet. Accordingly, the particular node may transmit the network discovery packet in the particular timeslot of the frames. In an additional or alternative embodiment, the particular node may receive a network discovery request from a requesting node. In response, the particular node determines whether it is free to reply to the network discovery request based on parameters in the network discovery request, and if free to reply, may transmit a network discovery packet to the requesting node.

Systematic neighbor detection in shared media computer networks

In one embodiment, a management device determines a topology of nodes in a network. Based on the topology, frequency hopping sequences are assigned (and notified) to the nodes such that each particular node of a certain set of the nodes is assigned a frequency hopping sequence on which to transmit that is different than frequency hopping sequences of neighbors and hidden neighbors of that particular node. In another embodiment, a transmitting node first transmits a transmission indication signal on its particular frequency band based on its frequency hopping sequence, and then transmits a message on the particular frequency band. In a further embodiment, a receiving node listening to a plurality of frequency bands may detect the transmission indication signal on the particular frequency band. In response, the receiving node filters out all frequency bands other than the particular frequency band, and receives the following transmission on that particular frequency band.

Dynamic assignment of frequency hopping sequences in a communication network

In one embodiment, a particular node in a wireless network may receive a wireless signal, and may determine whether the wireless signal is intended for itself. In response to determining that the wireless signal is intended for the particular node, the particular node may transmit a non-colliding wireless carrier sense detected alert (CSDA) signal during the received wireless signal to request that other nodes within communication distance of the particular node refrain from transmitting for a duration of the received wireless signal. In another embodiment, a node listens on a first frequency for a wireless CSDA signal regarding a second (colliding) frequency, and in response to receiving a CSDA signal, may refrain from transmitting a wireless signal on the second frequency for the particular duration, or else (if not receiving a CSDA signal), may allow transmission of a wireless signal on the second frequency, accordingly.

Collision avoidance for wireless networks

In one embodiment, a node may determine a topology of a plurality of reporting nodes within a directed acyclic graph (DAG) in a computer network. The reporting nodes may then be assigned to one of a plurality of reporting groups, where reporting nodes are allowed to report only during designated time windows corresponding to their assigned reporting group. The reporting nodes may then be informed of at least their own assignment to a particular reporting group. In another embodiment, a particular reporting node may join the DAG, and may also receive an assignment to one of a plurality of reporting groups. Accordingly, the particular reporting node may also determine designated time windows corresponding to the assigned reporting group, where the particular reporting node is allowed to report only during the designated time windows.

Data reporting using reporting groups in a computer network

In one embodiment, a data aggregator discovery (DAD) message may be distributed by an associated data aggregator, the DAD message identifying the initiating data aggregator, and comprising a recorded route taken from the data aggregator to a receiving particular node as well as a total path cost for the particular node to reach a root node of the DAG through the recorded route and via the data aggregator. The receiving particular node determines a path cost increase (PCI) associated with use of the data aggregator based on the total path cost as compared to a DAG-based path cost for the particular node to reach the root node via the DAG. If the PCI is below a configured threshold, the particular node may redirect traffic to the data aggregator as source-routed traffic according to the recorded route. The traffic may then be aggregated by the data aggregator, accordingly.

Redirecting traffic via tunnels to discovered data aggregators

In one embodiment, a particular node in a computer network, that is, one receiving electrical power from a grid source, may determine routing metrics to a plurality of neighbor nodes of the particular node in the computer network. In addition, the node also determines power grid connectivity of the plurality of neighbor nodes. Traffic may be routed from the particular node to one or more select neighbor nodes having preferred routing metrics, until a power outage condition at the particular node is detected, at which time the traffic (e.g., last gasp messages) may be routed from the particular node to one or more select neighbor nodes having diverse power grid connectivity from the particular node. In this manner, traffic may be routed via a device that is not also experiencing the power outage condition.

Data routing for power outage management

In one embodiment, a particular node in a computer network receives an indication of a number of child nodes of one or more potential parent nodes to the particular node in a primary directed acyclic graph (DAG). From this, the particular node selects a particular potential parent node with the highest number of child nodes as a secondary DAG parent for the particular node, and joins the secondary DAG at the selected secondary DAG parent (e.g., for multicast and/or broadcast message distribution). This may recursively continue, such that nodes gravitate toward parents with more children, potentially allowing parents with fewer children to relinquish their parental responsibilities.

Gravitational parent selection in directed acyclic graphs

In one embodiment, a repeater node in a shared media network may intercept a shared media transmission from a first node to a second node. Once a shared media transmission is intercepted, the repeater node may determine whether the second node returns an acknowledgement (ACK) to the first node. If the second node does not return an ACK to the first node, the repeater node repeats the shared media transmission to the second node. Also, according to one or more additional embodiments of the disclosure, when receiving an ACK at the repeater node from the second node in response to the repeated shared media transmission, the repeater node may also forward the ACK from the second node to the first node.

Repeater nodes in shared media networks

According to one or more implementations of the disclosure, packets may be transmitted in a low power and lossy network (LLN) by receiving, on a first node, a message from a sending node, and by activating a critical message configuration to be applied in routing the message. A message identifier (e.g., signature) for the message may also be received or gleaned. The message identifier can be compared at the first node to a list of stored message identifiers, created based on routing history, to determine if the message has already been received. As such, if the message has not been received at the first node previously, a first parent and a second parent for the message are identified and the message, along with the critical message indication, can be transmitted to the first parent and the second parent, thereby achieving redundancy in the routing of the message.

System and method for routing critical communications

In one embodiment, a node may determine a trigger for establishing transmission priority on a path through a shared-media communication network for priority traffic to a particular node. As such, the node may generate a path clear message (PCM) that would instruct one or more receiving nodes along the path to suspend transmission for traffic other than the priority traffic for a specified duration, and also to transmit a local non-repeated distributed message to one or more neighbor nodes of each respective receiving node, the local non-repeated distributed message to instruct the neighbor nodes to suspend transmission for the specified duration. After transmitting the PCM along the path to the particular node to establish the transmission priority for the priority traffic along the path through the shared-media network, the priority traffic may be transmitted to the particular node along the path during the transmission priority.

Transmission priority paths in mesh networks

In one embodiment, a device in a computer network monitors an alternating-current (AC) waveform of an electrical power source at the device, where the power source is part of a polyphase power source system. Once the device determines a particular phase of the polyphase power source system at the device, then the device joins a directed acyclic graph (DAG) specific to the particular phase. In another embodiment, a device detects a time of a zero crossing of the AC waveform, and may then determine a particular phase of the polyphase power source system at the device based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network.

Phase-based operation of devices on a polyphase electric distribution system

In one embodiment, hidden neighbor relationships are identified based on received neighbor information from a plurality of nodes in a communication network. Based on determining a number of hidden neighbors for a particular node at various node parameters, a cost function associated with the particular node may be determined and utilized. In another embodiment, a number of hidden nodes of the particular node is determined across a range of transmission powers, and a delay associated with the particular node reaching a root node in the network across the range of transmission powers is also determined based on the neighbor nodes reachable at respective transmission powers. A tradeoff is determined across the range of transmission powers between the number of hidden nodes and the delay, and then the transmission power of the particular node can be set based on an acceptable determined tradeoff.

Growing community of inventors

San Jose, CA, United States of America

Sandeep Shetty