Patents Assigned to Metricom, Inc.
  • Publication number: 20030003934
    Abstract: In a wireless communication system having sometimes mobile subscriber units and a plurality of fixed network devices located at cell sites, a multimode acquisition protocol is provided at each subscriber unit which first senses whether the subscriber unit is static or mobile from the nature and quality of the communication links with nearby network devices and then enables an acquisition protocol suited to either static mode or mobile mode. In a specific embodiment, the protocol initiates procedures to change acquisition mode from static to mobile upon failure of the subscriber unit to sense three consecutive scheduled polling packets sent by a linked network device or upon loss of communication with any locally-known network device or upon failure to transmit 25 consecutive data packets. In such case, the procedure is initiated to determine whether it is appropriate to switch to a mobile mode for purposes of acquisition.
    Type: Application
    Filed: June 27, 2001
    Publication date: January 2, 2003
    Applicant: Metricom, Inc.
    Inventors: Rodrigo Garces, Cuong-Thinh Nguyen, William San Filippo
  • Publication number: 20030002442
    Abstract: In a mesh communication network, a poll request protocol (PRP) is provided in which a special packet is broadcast by the congested node when it is ready to provide services. The controlling node (usually the more congested node) broadcasts a packet to request poll signals from nodes desiring resources of the controlling node. The contending nodes then have equal chances to request the services of the controlling node by sending poll signals. The controlling node can then arbitrate the requests, determine the most fair and efficient use of its resources, and broadcast a scheduling packet to inform the contending nodes when to inform the contending nodes of controlling node scheduling. The contending nodes then send their packets to the controlling node without lost packets caused by congestion collisions. The controlling node can then send data to the contending nodes also without lost packets.
    Type: Application
    Filed: June 27, 2001
    Publication date: January 2, 2003
    Applicant: Metricom, Inc.
    Inventors: George H. Flammer, David L. Paulsen, Michael W. Ritter
  • Patent number: 6298053
    Abstract: In a radio based wireless mesh packet network wherein packet traffic is scheduled between a high capacity communications link and a plurality of nodes interconnected by wireless links, an access unit is provided at a first node having a plurality of radios coupled to the high capacity link and wherein each of the plurality of radios is capable of detecting a polling of the access unit by other nodes. A poll is sent from a second node to the access unit at the first node on a first channel. Reports of receipt of the poll are shared among the plurality of radios. An acknowledgment is sent on behalf of the access unit from only one of the plurality of radios to the polling node, and further communication is conducted between the one of the plurality of radios and the node on a second channel.
    Type: Grant
    Filed: January 14, 2000
    Date of Patent: October 2, 2001
    Assignee: Metricom, Inc.
    Inventors: George H. Flammer, III, David Lynn Paulsen
  • Patent number: 5903566
    Abstract: A large data file is distributed to a number of nodes in a data communication network by a process of distributed downloading. Destination nodes are informed of the location in the network of the large data file and are directed to receive the large data file by requesting that blocks of data containing the file be transmitted to them from the designated source node. The destination nodes control the file transfer. The large data file may contain program code for updating network software.
    Type: Grant
    Filed: June 24, 1994
    Date of Patent: May 11, 1999
    Assignee: Metricom, Inc.
    Inventor: George H. Flammer, III
  • Patent number: 5818828
    Abstract: In a wireless frequency hopping communication system, a protocol, which does not employ carrier sense or collision detect, is provided for allocating bandwidth fairly and efficiently under varying load conditions, wherein a node is permitted random access to the medium bandwidth under light loading conditions and wherein under higher loading conditions a time/bandwidth allocation is made with a portion of the allocation dedicated to inband backhaul tasks by introducing a form of polling, the size of the reserved time/bandwidth allocation being selected based on traffic pattern. Under such heavy load conditions, non-slave traffic is allocated bandwidth in slots as pseudo-slave packets to guarantee a share of the bandwidth. Depending on the activity of the population of packets, including responsiveness and trend of responsiveness, the relative size of the slots is determined.
    Type: Grant
    Filed: October 4, 1996
    Date of Patent: October 6, 1998
    Assignee: Metricom, Inc.
    Inventors: Robert Lawrence Packer, Milton Y. Xu, John Bettendorff
  • Patent number: 5774344
    Abstract: A metallized plastic RFI/EMI shield is provided against electromagnetic energy for a circuit card wherein the shield is formed of a box enclosure with two casing halves to enclose the card, the first casing half having a solid flange side walls surrounding the card and the second casing half having a flange formed by flat, plate-like closely-spaced fingers, the fingers confronting, being in electrical contact with and mating in full length with substantially the entire periphery of the side walls of the first casing half. The fingers are preferably spaced with a separation of less than 1/4 wavelength of any measurable harmonic of the intended operating frequency, typically up to the tenth harmonic. A slot may be provided to receive the fingers on the outside of the side walls, and closely-spaced grounding pins arranged around the periphery of the card may extend between the first and second casing halves through ground plated perforations along the edge of the side walls.
    Type: Grant
    Filed: December 6, 1995
    Date of Patent: June 30, 1998
    Assignee: Metricom, Inc.
    Inventor: Matthew P. Casebolt
  • Patent number: 5706221
    Abstract: A data filter consists of an electronic circuit with a delay and offset in a feedback loop to a reference input of a comparator to provide low frequency tracking of a binary-level data signal so digital information can be extracted at the output of the comparator by causing the reference input to track a relatively slowly-varying baseband neutral signal level. The delay is preferably implemented by a low-pass filter, providing additional noise immunity.
    Type: Grant
    Filed: May 13, 1996
    Date of Patent: January 6, 1998
    Assignee: Metricom, Inc.
    Inventor: David L. Paulsen
  • Patent number: 5703602
    Abstract: A small, collapsible, high-gain, dipole antenna and a method to make the antenna. The present invention provides a collapsible half-wavelength dipole antenna for use in a portable device, the antenna having a fully collapsed position and a fully extended position. The antenna includes a static dipole arm, and a movable dipole arm. The movable dipole arm is capable of being moved to the fully collapsed position and the fully extended position. The antenna also includes a balun feed assembly electrically coupled to the static dipole arm and to the movable dipole arm. The antenna is capable of transmitting and receiving electrical signals in either the fully collapsed position or the fully extended position. The balun feed assembly is fixed to the static dipole arm, and the movable dipole arm is movably coupled to the balun feed assembly.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: December 30, 1997
    Assignee: Metricom, Inc.
    Inventor: Matthew Phillip Casebolt
  • Patent number: 5664194
    Abstract: In a computer-driven device, a start-up mode after reset is provided whereby boot-up instructions are by default always accepted directly from an external source. The device may comprise a gate array (GA) which is connected directly via a serial port to a receiving or input device, to receive program code for transfer directly as instructions to a microprocessor-type central processing unit. The central processing unit is part of a computer controlled device containing a microprocessor, memory (a RAM), and typically a bulk erase flash memory device, the flash memory device being unprogrammed when the computer controlled device is fabricated originally. When the computer controlled device first powers up, a special mode of operation ensues in which the gate array directly monitor bits received via the serial port from the input device and shifts them into a local register from which bytes or words are loaded directly into the CPU as instructions.
    Type: Grant
    Filed: December 4, 1995
    Date of Patent: September 2, 1997
    Assignee: Metricom, Inc.
    Inventor: David L. Paulsen
  • Patent number: 5636216
    Abstract: In a local network connected to other networks which employ an Internet Protocol, and wherein the local network includes nodes which cannot monitor all other nodes in the local network, an Internet Protocol address of a target node in the local network is translated at a gateway node in the local network to a network-specific local address of the target node without the use of broadcasting. The network specific local address of the target node is the address which is usable within the local network for forwarding a packet to the target node.
    Type: Grant
    Filed: April 8, 1994
    Date of Patent: June 3, 1997
    Assignee: Metricom, Inc.
    Inventors: Richard H. Fox, Brett D. Galloway
  • Patent number: 5570084
    Abstract: In a packet communication system, loose source routing is employed to permit communication over networks of disparate types, including geographic and path-unaware types. No information resides on a wired access point (WAP). All of the intelligence of the system resides in Name Servers, which provide opaque addresses that end nodes (radios) in a wireless cloud can use to send packets to other end nodes (radios) in other wireless clouds. (A cloud is the set of radios serviced by a particular WAP.) According to the invention, the method employs an ordered list called a path and the network address of a packet consists of such an ordered list of addresses with a "marker" that flags the current destination of the packet and a "direction bit" that tells which direction on the list the next destination is. Each address in the path is type-length-value (TLV) encoded.
    Type: Grant
    Filed: June 28, 1994
    Date of Patent: October 29, 1996
    Assignee: Metricom, Inc.
    Inventors: Michael W. Ritter, John Bettendorff, George H. Flammer, III, Brett D. Galloway
  • Patent number: 5515369
    Abstract: In a wireless packet communication system having a plurality of nodes, each having a transmitter and a receiver, the receiver at each node is assigned a seed value and is provided with a channel punchout mask. A node uses its seed value and punchout mask to generate a specific randomly ordered channel hopping band plan on which to receive signals. A node transmits its seed value and punchout mask to target nodes with which it wants to establish communication links, and those target nodes each use the seed value and punchout mask to generate the randomly ordered channel hopping band plan for that node. Subsequently, when one of the target nodes wish to transmit to the node, the target node changes frequency to the frequency of the node according to that node's band plan.
    Type: Grant
    Filed: June 24, 1994
    Date of Patent: May 7, 1996
    Assignee: Metricom, Inc.
    Inventors: George H. Flammer, III, Brett D. Galloway, David L. Paulsen
  • Patent number: 5488608
    Abstract: In a packet communication system, wherein nodes are assigned an absolute coordinate-based address and routing decisions are made at each node without the use of directory-based routing, routing decisions made for a particular packet with an ultimate destination are stored at each node so that the next packet sent by that node to that same ultimate destination can be forwarded in accordance with the previous routing decision made for that destination. Routing decisions are stored locally at each node in a routing table. In one embodiment, nodes also store routing information about the source node for a packet so that when a return packet is received for the original source, the relay node will not have to make a routing decision.
    Type: Grant
    Filed: April 14, 1994
    Date of Patent: January 30, 1996
    Assignee: Metricom, Inc.
    Inventor: George H. Flammer, III
  • Patent number: 5485393
    Abstract: A digital current meter, usable either alone or in combination with a voltage meter, is disclosed. The current meter includes a current sensor which outputs the time derivative of the current flowing through the load being measured. The differentiated current signal is digitally sampled, usually by a sigma-delta sampler, filtered, and digitally integrated. A feedback path is provided to remove the direct-current (DC) component of the current signal, to keep the integrator from going out of range. A bleeder feedback channel around the digital integrator is provided to keep the digital integrator from permanently latching an impulse. In combination with a voltage meter, a half-sample delay is introduced in the current signal path, to compensate for the lead provided by the combination of the analog differentiator and the digital integrator, and the voltage signal path uses filters with the same characteristics as the current channel, to match the delay in the two channels.
    Type: Grant
    Filed: July 27, 1993
    Date of Patent: January 16, 1996
    Assignee: Metricom, Inc.
    Inventor: Curtis V. Bradford
  • Patent number: 5479176
    Abstract: An antenna array for direction-agile applications, such as r.f. packet mesh networks, employs a plurality of quarter-wave radiators disposed normally to a ground plane on a dielectric backing and switching elements for selecting a desired receiving direction and transmission direction and minimizing interference from signals in opposing directions. A control system selects and switches direction rapidly enough to receive and transmit digipeating signals in selected different directions using the phasing and switching elements. A specific embodiment employs eight radiators of 0.2625 electrical wavelengths (quarter wave plus 5%) disposed equidistant along a circle within a circular ground plane in a pattern which is 1/4 wavelength from the outer boundary of the ground plane, each radiator being disposed at least 0.15 wavelengths to about 0.25 wavelengths from adjacent radiators in a circular pattern. The antenna is characterized by eight electronically switchable radiating directions (at 45.degree.
    Type: Grant
    Filed: October 21, 1994
    Date of Patent: December 26, 1995
    Assignee: Metricom, Inc.
    Inventor: Robert J. Zavrel, Jr.
  • Patent number: 5479400
    Abstract: A microcellular digital packet communication system is provided for digital communication having a plurality of repeating packet-mode fixed-site transceivers each being at a plurality of different sites and each being capable of communicating on mutually-common frequencies, including for example by means of frequency-hopping spread spectrum, wherein a terminal transceiver directly communicates substantially simultaneously with at least a few of the fixed-site transceivers on the mutually-common frequencies and distributes information packets of a single originating message among the fixed-site transceivers, the fixed-site transceivers forwarding the information packets via multiple communication links to a single destination terminal on the mutually-common frequencies at which the message is reassembled. The system enables reliable handoffs and robust connectivity by maintaining multiple simultaneous communication links between terminal transceivers and repeating transceivers.
    Type: Grant
    Filed: June 6, 1994
    Date of Patent: December 26, 1995
    Assignee: Metricom, Inc.
    Inventors: Robert P. Dilworth, George H. Flammer, III, Brett D. Galloway
  • Patent number: 5465398
    Abstract: In a wireless LAN packet communication system, for each successfully received packet the strength of the received signal is measured at a target node by monitoring an A/D converted rssi (received signal strength indication) signal. A record of minimum strength among successfully received packets is maintained at the target node. For each succesfully received packet the difference between the signal strength of the packet and the recorded minimum is calculated at the target node and sent over the link to the source node as a quantitative difference indicator. The source node maintains a moving average of difference indicators received over time and adjusts the transmitter power level so as to maintain the moving average at a preselected link margin threshold level. Alternatively, the calculation of a desired source node power level change is performed at the target node and transmitted to the source node.
    Type: Grant
    Filed: October 7, 1993
    Date of Patent: November 7, 1995
    Assignee: Metricom, Inc.
    Inventor: George H. Flammer
  • Patent number: 5453977
    Abstract: In a mesh communication network, new network nodes acquire information about nearby nodes to which they may communicate through a third-party query whereby an established node with which a new node can communicate is queried to provide a list of nodes in the vicinity of the new nodes with which the new node is likely to be able to communicate. The new node uses this list in attempting to establish communication links and then repeats the third-party query for each node in the list to which it can communicate.
    Type: Grant
    Filed: February 8, 1994
    Date of Patent: September 26, 1995
    Assignee: Metricom, Inc.
    Inventors: George H. Flammer, III, William E. San Filippo, III
  • Patent number: 5406249
    Abstract: An apparatus and a method for communicating data among transceivers in an electrical utility distribution system where a signal path between the transceivers includes multiple power distribution transformers is described. A first transceiver, common-mode coupled to a secondary of a first power distribution transformer transmits a carrier signal modulated by a data stream to the secondary. The modulated signal is transferred to the primary of the first power distribution transformer which is coupled to the primary of a second power distribution transformer. A second transceiver, common-mode coupled to a secondary of the second power distribution transformer, receives the modulated signal from the secondary. Both transceivers are protected from the high power delivered at the line frequency by filtering capacitors which attenuate signals at the line frequency and pass signals at the carrier signal frequency.
    Type: Grant
    Filed: March 9, 1993
    Date of Patent: April 11, 1995
    Assignee: Metricom, Inc.
    Inventor: Michael G. Pettus
  • Patent number: 5400338
    Abstract: In a packet communication system wherein stationary nodes are assigned an absolute coordinate-based address, the addressing of roaming nodes is accomplished by parasitically adopting a coordinate routing scheme used for addressing stationary nodes. Each roaming node selects a parent stationary node with which the roaming node can communicate directly. During the course of network operation, the roaming node may select a new parent node. At the time of reassignment, the coordinates of the new parent node, along with the identity of the roaming node, is recorded at the former parent node. Forwarding of packets to stationary nodes is accomplished according to a known coordinate-based routing scheme. A packet addressed to a destination roaming node is forwarded and directed through the then current stationary parent node. The packet is then forwarded to the destination roaming node.
    Type: Grant
    Filed: February 8, 1994
    Date of Patent: March 21, 1995
    Assignee: Metricom, Inc.
    Inventor: George H. Flammer, III