Massachusetts Institute of Technology

Lucent Technologies Inc.

Rmi Corporation

Kai-Yeung S Siu

Haruhiko Harry Asada

Hong-Yi Tzeng

Paolo Narvaez-Guarnieri

Mizanur Mohammed Rahman

Ching Law

Brian Hang Wai Yang

Ken Yeung

Kuo Wei Chang

Kayi Lee

Boo-Ho Yang

Erin Cem

Thit Minn

Hsi-Tung Huang

Paolo Narvaez

Cem Erin

Chun-Hung Liu

Paolo L Narvaez

A communication circuit for verified communication comprising a transmitter having input terminals to receive a data word, an encoder configured to encode the data word to create an encoded word different from the data word, and output terminals configured to transmit the data word and the encoded word. A receiver is coupled to the transmitter and includes input terminals to receive the data word as a received word and the encoded word, a decoder configured to decode the encoded word to create a decoded word, and a comparator configured to compare the received word and the decoded word to create a select signal, and a selector responsive to the select signal and configured to select the received data word or the decoded word based at least in part on the select signal. Advantages of the invention include the ability to verify redundant received data without decreasing bandwidth or increasing latency.

Advanced communication apparatus and method for verified communication

A method of encoding a transmission signal to reduce multiple access interference at a receiver. A data source signal including a plurality of source symbols is received into a transmitter. The source symbols are encoded using low energy encoding forming encoded codewords. An identifying pattern is applied to the encoded codewords forming a transmission signal. In one embodiment, the identifying pattern is a unique pseudo-random pattern identifying the data source. Once the pattern has been added, multiple transmission signals can be summed together and then modulated onto a carrier wave. The transmission signals are then transmitted on the carrier wave which is at a pre-selected frequency. The low energy encoding format is such that a sequence of signals forming codewords is created. Each sequence of signals is characterized by an energy and normally a high bit consumes energy whereas a low bit requires substantially less energy.

Source coding for interference reduction

The invention features a method and system for identifying a plurality of tags using an efficient memoryless protocol. The system includes a reader and a plurality of tags. The reader is adapted to maintain an ordered set of query strings; select a string from the set of query strings; broadcast a query message containing the selected string or a portion of the selected string to the tags; and receive a response from one of the tags. The tags operate without batteries and are adapted to respond to the selected string broadcast by the reader. Accordingly, the tag identification methods are efficient in terms of both time and communication complexities.

Efficient memoryless protocol for tag identification

This invention is an algorithm that restores routing in a link-state network after a link failure without flooding the entire routing area with new routing information. The algorithm operates only in the local neighborhood of the failed link and informs the minimum number of routers about the failure.

Fault-tolerant non-flooding routing

A dynamic shortest path tree (SPT) algorithm for a router determines a new SPT for a root node in response to a link-state or other network topology change. The dynamic SPT algorithm determines the new SPT as an optimization problem in a linear programming framework based in an existing SPT in the router. The dynamic SPT algorithm emulates maximum decrement of a ball and string model by iteratively selecting nodes of the existing SPT for consideration and update of parent node, child nodes, and distance attributes based on the maximum decrement. For the maximum decrement, a node in the existing SPT is selected by each iteration based on the greatest potential decrease (or least increase) in its distance attribute. The ball and string model that may be employed for the dynamic SPT algorithm represents a network of nodes and links with a ball representing a node and a string representing a link or edge. The length of a string is defined by its link's weight. The set of strings connecting the balls defines a path between the root node and a particular node. The shortest path is the path defined by the strings from a root node to a particular node that are tight. For the dynamic SPT algorithm, an increase (or decrease) in an edge weight in an existing SPT corresponds to a lengthening (or shortening) of a string. By sequentially pulling balls away in a single direction from the ball of the root node, the new SPT becomes defined by the balls and tight strings.

Dynamic algorithm for determining a shortest path tree between network nodes

A method and apparatus for telemetering data on a channel having a maximum data rate by utilizing a power efficient communication protocol is provided. The data to be telemetered comprises a number of source symbols where each source symbol is characterized by a probability of occurrence. A sequence of signals forming codewords having an energy and a length is produced. The length for the codewords is based at least on the number of symbols to be coded. Each codeword signifies a specified source symbol on the basis of a mapping between source symbols and codewords. The mapping is such that each source symbol of lower probability of occurrence is associated with a codeword of at least equal energy.

Power-efficient communication protocol

A novel data structure in a router helps to compute viable next hops for forwarding a data packet from a router to its destination along multiple alternate loop-free paths, which are not necessarily of shortest distance. Each viable next hop may also be specified with a degree of optimality, which enables a route to perform QoS routing and fault-tolerant routing efficiently. The data structure can be implemented as an add-on software to existing routing protocols and may be implemented in existing networks which use shortest path protocols, even where less than all of the routers use the data structure and multiple path scheme described herein.

Multiple path routing

A method for regulating flow through a network node where forwarding of successive data packets from sources is dependent on receipt of acknowledgments from the destinations, the packets are buffered in a packet buffer as they arrive from their sources. Acknowledgments are withheld in an acknowledgment bucket, and are released such that successive data packets are buffered in the sources to avoid overflow of the packet buffer due to bandwidth limitations toward the destinations. The destination is typically in a bandwidth constrained network (BCN) while the source is in a local area network (LAN) using transmission control protocol (TCP). In a preferred embodiment the BCN operates in asynchronous transfer mode (ATM), and a transmission rate of the BCN is returned upon request. TCP source states are maintained by observing TCP traffic through the node. The behavior of TCP sources is predicted from traffic observations. Then, the known transmission rate of the BCN is translated to a timed sequence of acknowledgments releases based on the predicted behavior. Alternatively, an estimate is maintained of effective queue size, which includes data buffered in the packet buffer, and residual data packets, i.e., those data packets that have been requested but have not yet been received at the node. An acknowledgment is released if the effective queue size is less than a threshold, which may be dynamic.

Method for regulating TCP flow over heterogeneous networks

In a cell switching network, a method of buffering cells in a switch assigns guaranteed buffer space per time interval T to individual virtual connections (VCs). In each of successive periods of time, the individual VCs are allocated available buffer space up to their guaranteed buffer space. After the VCs are served their guaranteed data rates, and within the remaining time of each period, excess buffer space is allocated to individual VCs. In a preferred embodiment, cells are stored in a shared first-in-first-out (FIFO) buffer which serves plural VCs. A cell count is maintained for each VC, and is incremented for each corresponding incoming cell. Cell counts are decremented according to a round robin scheme, no lower than some negative limit, independent of the actual VC with which the outgoing cell is associated, allowing the VC to make up some bandwidth later for an earlier period of non-use. When a cell count for some virtual connection is above a connection threshold, incoming cells associated with the virtual connection are blocked from storage in the buffer. In an alternate embodiment, cells are buffered in queues where there is one queue per VC.

Network switching system supporting guaranteed data rates

A method of communicating multiple signals over a common communications link by modulating first input signals with respective first codes of low cross-correlation to obtain a first set of modulated signals at a first chip rate. The input signals can be, for example, digitized audio or video signals, or data signals. The second input signals are of a data rate higher than the first input signals, and the second codes are of a dimension greater than the first codes. The second input signal or signals are modulated with respective second codes of low cross correlation relative to each other and relative to the first codes, resulting in a second set of modulated signals at a second chip rate such that there is spectral overlap between the first and second sets of modulated signals. The first and second sets of modulated signals are preferably modulated with different noise signals to spread the spectrum of each. In a preferred embodiment, the first and second codes are Walsh codes of different dimensions.

Variable chip rate code-division multiple access

A monitoring system for monitoring the health status of a patient and transmitting to a remote receiver a signal, based on measured physiological parameters. A sensor is incorporated in a finger ring or other article of apparel so as to monitor skin temperature, blood flow, blood constituent concentration, or pulse rate of the patient. The data are encoded for wireless transmission by mapping a numerical value associated with each datum to a pulse emitted after a delay of a specified duration following a fiducial time. Multiple ring bands and sensor elements may be employed for deriving three-dimensional dynamic characteristics of arteries and tissue of the finger.

Growing community of inventors

Charlestown, MA, United States of America

Kai-Yeung S Siu