Abstract: A method for locating nodes in a multi-hop sensor network forms a rigid body (RB1, RB2, RB3) and, from the nodes, utilizes the rigid body to decide if a node is locatable. The method obtains a reduced order model (ROM) of the network by categorizing all of the nodes by location status, grouping them based upon the categorizations, and defining and identifying a rigid body from a group. To locate the nodes, the nodes are separated from one another into subsets dependent upon characteristics (1100). Then, super groups are formed from one subset (1200) and the sub-groups are formed from each super group (1300). The rigid body core is formed (1400) and the resultant rigid body is determined (1500). The ROM is formed from the rigid body (1600) and a location capability of the rigid body is evaluated based upon the ROM (1700).

Abstract: A location technique is utilized within a wireless communication system where power measurements from various nodes are weighted to determine a node's location. An iterative location process is executed where as more and more nodes are heard from, a node will re-locate itself in order to improve location accuracy.

Abstract: A method for estimating the location of a blindfolded node (235) in a wireless network having reference nodes (225, 230) is provided. The reference nodes (225, 230) are combined into pairs (301) and each pair is checked to determine if the reference nodes are within each other's communication rage (304). A plurality of probable regions (315) for the blindfolded node are obtained (313, 315). These probable regions are overlapped (320), and the blindfolded node's estimated location is estimated to be the geometric center of the overlapped regions (325).

Abstract: A method and apparatus for determining the path loss model of an object within a wireless communication system is provided herein. During operation, a path loss model for a node is generated based on path loss values and corresponding numbers of neighbors of the said node. The path loss model is used to determine a relationship between path loss and distance. With this relationship established, distances to known-located nodes may be obtained by obtaining a path loss to the known-located node. From these distances, a node can then be located.

Abstract: A location technique is utilized where channel-model parameters are originally estimated prior to location taking place. Location then takes place using a first set of known-located nodes, and the channel-model parameters are updated based on the distances resulting from the location estimate. Once the channel-model parameters have been updated, location again takes place using a second set of known-located nodes, node distances are calculated based on the produced locations and the channel-model parameters are again updated. This process continues until no significant change is observed between the previous and the newly estimated location, or until a maximum number of iterations is reached.

Abstract: A method and apparatus for determining a best technique (algorithm and/or parameters) to use when locating a node (104) is provided herein. In particular, reference nodes (105) are provided that not only know their own locations, but also test various algorithms and parameters by estimating their locations as if they were blind nodes. The reference nodes then evaluates these various techniques against the user defined criteria for the best technique. Recommendations as to the best technique to utilize are then made to other nodes within the system.

Abstract: To enable wireless applications which require the use of location information, a method and apparatus for transmitting location data within an ad-hoc communication system is provided herein. During operation, a portion of a packet payload is used to transmit location coordinate information along with an identifier of location estimation technique utilized for a node, as well as other parameters that may be needed for location estimation. Nodes in the communication system calculate their location coordinates using the said portion of packets received from other nodes in the communication system.

Abstract: A method and apparatus for determining the location of a node within a communication system is provided herein. During operation, reference nodes (105) having known locations are utilized to locate “blind” nodes (104) whose location is to be determined. More particularly, a blind node (104) wishing to determine its location will measure a plurality of path losses between itself and a plurality of reference nodes (105). These reference nodes' locations will then be mathematically weighted by the path loss between these reference nodes (105) and the blind node (104). The location of the blind node (104) is a sum of the mathematically weighted reference nodes' locations.

Abstract: A method and system is provided for determining a location for each of a plurality of units, which is selected from one of multiple sets of locations, which are each estimated based upon different initial location estimates. The selected set of locations includes the set which has the minimum error value, where the error value is based on the aggregate of the differences between the range determined from the estimated locations and the measured range. By using different sets of initial location estimates, there is a greater chance that at least one of the sets of initial location estimates will avoid any local minimums and produce a more accurate estimate of unit locations.

Abstract: A Voice Over Internet Protocol (VOIP) receiver (630), operating in conjunction with a transmitter (606) receives a sequence of voice packets representing a speech utterance transmitted over a VOIP wireless interface (112). A receive packet buffer (120) buffers the received sequence of voice packets after receipt and before playback of reconstructed speech. A processor (650), operating under program control, determines a transmission buffer (108) delay of a first packet in the sequence of packets representing the speech utterance. The control processor (650) further sets a prescribed amount of delay in the receive packet buffer (120) based upon the transmission buffer (108) delay so that the transmission buffer delay+receive buffer delay=a predetermined total delay.

Abstract: To reduce interference and increase battery life, a method and apparatus for transmitting location data within an ad-hoc communication system is provided herein. During operation, a portion of a beacon payload is reserved to broadcast location information (coordinates) for a node as well as other parameters that may be needed for location estimation. In addition to a node's location, an accuracy of the nodes location is also included within the beacon field. Because nodes will no longer have to awake outside their beacon transmit times to broadcast location information, battery life is extended. In addition, because nodes will no longer be transmitting location information outside their guaranteed time slot, system interference is also reduced.

Abstract: A method and system is provided for determining a location for each of a plurality of units, which are sub-divided into more than one sub-net groupings, that each include two or more units. Within each sub-net grouping, measured range information between units within the sub-nets and one or more reference units is gathered in at least a selected one of the units. The selected one of the units then estimates a location for each of the units, which minimizes any error in the measured ranges between the units in each of the corresponding sub-nets.

Abstract: A method and system is provided for determining a location for each of a plurality of units, which is selected from one of multiple sets of locations, which are each estimated based upon different initial location estimates. The selected set of locations includes the set which has the minimum error value, where the error value is based on the aggregate of the differences between the range determined from the estimated locations and the measured range. By using different sets of initial location estimates, there is a greater chance that at least one of the sets of initial location estimates will avoid any local minimums and produce a more accurate estimate of unit locations.

Abstract: A method and location determination module is provided for determining a location of one of a plurality of units using neighbor lists. Each unit is communicatively coupled to at least some of the other plurality of units, where at least some of the plurality of units are reference units, whose locations are known. The units communicate with other nearby units within communication range, to establish neighbor lists. A unit to be located then identifies an aggregate value corresponding to the number of occurrences of the reference units in the neighbor list of the unit to be located and the neighbor lists of each of a group of associated units. The location of the unit to be located is then determined, based upon the known locations of the reference units and the number of identified occurrences of the reference units in the corresponding neighbor lists.

Abstract: To address the need for channel assignment in an ad-hoc network, a method and apparatus for channel assignment is provided herein. In particular, a communication system (100) utilizes a method for deterministic node (101-107) channel assignment that enables channel reuse and thus scalability of an ad-hoc network. The channel assignment is dependent upon a current level for the particular nodes, as well as the maximum available channels, the maximum allowable levels in the network, and the maximum number of children nodes that a parent can have.

Abstract: A method for peer-to-peer ranging and discovery of a rigid body existing in a scatternet having piconets and nodes includes the steps of defining a node (12) in a piconet (10) to be a piconet controller (PNC) having controller functions, locating a rigid body seed including the node (12), and discovering a rigid body by sequentially downloading controller functions of the piconet controller (12) to at least one border node. Also provided is a communications node including a receiver for receiving communications from other communications nodes in a communications range (R), a transmitter for sending communications to other communications nodes in the communications range (R), a memory storing at least ranging information and a unique identification for describing the node, and a processor connected to the receiver, to the transmitter, and to the memory, the processor being programmed to carry out the method according to the present invention.

Abstract: A method for reducing communications in a peer-to-peer wireless network having nodes includes sending an RTS-TOA ranging communication from a first node (N0) in a node group to another node (Nr, I) in the group, receiving the RTS-TOA communication with the second node (Nr, I) and sending a multi-cast CTS-TOA/RTS-TOA ranging communication from the second node (Nr, I) as a reply to the received RTS-TOA communication, and successively and sequentially repeating the multi-cast sending step for each of the nodes. A CTS-TOA message is a reply to the received RTS-TOA message and, simultaneously, is an RTS-TOA ranging communication to a new destination node (J). The method applies for a randomized communications approach when node identifications are not sequenced and to a sequential approach where nodes are sequenced, and also applies to completely connected and multi-hop networks. Also provided is a node for carrying out the method of the present invention.

Abstract: A method for locating nodes in a multi-hop sensor network forms a rigid body (RB 1, RB2, RB3) and, from the nodes, utilizes the rigid body to decide if a node is locatable. The method obtains a reduced order model (ROM) of the network by categorizing all of the nodes by location status, grouping them based upon the categorizations, and defining and identifying a rigid body from a group. The method further simplifies determinability of node location by forming the rigid body from the nodes based upon the categorized location status. To locate the nodes, the nodes are separated from one another into subsets dependent upon characteristics (100). Then, groups are formed from one subset (200) and the rigid body is formed from a group (300). The ROM is formed from the rigid body (400) and a location capability of the rigid body is evaluated based upon the ROM (500).

Abstract: A communications network (100) has coordinator devices (10) each transmitting a beacon message in a cluster area (30). Neighboring coordinator devices (1, 2) define overlap areas (60) in which each beacon message of the neighboring coordinator devices is present. Neighboring coordinator devices (1, 2) may also define non-overlap areas (204) in which each beacon message is present. A method for distributing communication signals includes providing nodes (50), (51,52) within a transmission region (30) of the coordinator devices (1, 2). The node (50) or nodes (51, 52) detect at least one beacon message of the neighboring coordinator devices (1, 2), determine the existence of a condition (302), and warn neighboring coordinator devices of the condition. The condition (302) is corrected by making an adjustment to the communication signal (such as beacon timing) by a correction amount (304).

Abstract: A Voice Over Internet Protocol (VOIP) receiver (630), operating in conjunction with a transmitter (606) receives a sequence of voice packets representing a speech utterance transmitted over a VOIP wireless interface (112). A receive packet buffer (120) buffers the received sequence of voice packets after receipt and before playback of reconstructed speech. A processor (650), operating under program control, determines a transmission buffer (108) delay of a first packet in the sequence of packets representing the speech utterance. The control processor (650) further sets a prescribed amount of delay in the receive packet buffer (120) based upon the transmission buffer (108) delay so that the transmission buffer delay+receive buffer delay=a predetermined total delay.