At+t Corp.

At&t Intellectual Property I, L.p.

Bell Telephone Laboratories

At&t Bell Laboratories

Rca Inc.

Lucent Technologies Inc.

American Telephone & Telegraph Co., At&t Bell Laboratories

Other

Columbia University

Nicholas Frank Maxemchuk

David Hilton Shur

Aleksandr Zelezniak

David McManamon

Steven H Low

Sanjoy Paul

Lawrence P O'Gorman

John Thomas Brassil

Ellen L Hahne

Arun N Netravali

Abhijit K Choudhury

Dhiraj K Sharma

John A Stuller

John Charles Hartmann

Milorad R Buric

Jo-Mei Chang

Congzhou Zhou

Henning G Schulzrinne

A system and method are disclosed for the repair of IP multicast sessions. A repair server polls multiple transmit servers to accumulate as many of the packets missing from the multicast session as possible. A network includes a source of multicast packets in a multicast session and a plurality of multicast recipients in that session. A repair server in the network provides the packets it receives to the recipients. The repair server includes a missing packet detector. There is a plurality of retransmit servers in the network buffering portions of the packets they respectively receive during the session. The repair server maintains an ordered list of the retransmit servers that are most likely to have buffered copies of packets missing from the session. When the repair server detects that there are packets missing from the session it has received, it uses the ordered list to sequentially request the missing packets from respective ones of the plurality of retransmit servers.

Network-based service for the repair of IP multicast sessions

Systems and methods for modeling a mobile ad hoc wireless network are disclosed herein. In some embodiments of the disclosed subject matter, methods for modeling a mobile ad hoc wireless network for a predetermined geographical area. An exemplary method includes dividing the geographic area into a network grid including a plurality of network grid elements, locating obstacles, if any, to communication between transmission nodes located in at least two different grid elements from the plurality of network grid elements, locating bottlenecks within the plurality of network grid elements, locating network grid elements from the plurality of network grid elements where wireless transmission is unconstricted, determining a transmission flow rate across the bottlenecks, and comparing the transmission flow rate across the bottlenecks to determine if any of the bottlenecks are not real bottlenecks.

Systems and methods for modeling a mobile ad hoc wireless network

An improved system is achieved in a cellular arrangement where mobile units employ a moveable slot TDM approach to send packets to base stations, and where the base stations use a non-contention approach. When a base station transmits information packets to different mobile units, it merely queues the packets and transmits over a given channel. In a corresponding inbound channel, the mobile units transmit packets to the base station using the MSTDM protocol. The base station also transmits information regarding whether the inbound frequency is occupied by a signal that is being transmitted to the base station, or whether a collision exists. A collision on an inbound frequency occurs when more than one signal is simultaneously transmitted on the inbound frequency. On an additional control channel that is shared by all base stations, the base station sends information in a TDM fashion.

Packet transmissions over cellular radio

An improved cellular arrangement is created with mobile units that are responsive to control signals that direct the mobile units to modify the rate of packet transmissions in case of channel overload. A mobile unit in such an arrangement encodes either the speech signal, or only a portion thereof that is sufficient to reproduce a lower fidelity speech which is still intelligible&mdash;and at a lower rate. In another embodiment, the mobile unit creates a second stream of packets, also at a lower rate. The second stream complements the first stream of packets in its lower rate form, to allow reproducing the speech signal with high fidelity. Operationally, such a mobile unit is responsive to a base station which, under overload conditions, directs the mobile unit to transmit packets at the lower rate (and the lower fidelity). Optionally, the base station can also directs the mobile unit to send the second stream of packets over a different channel.

Overload control in a packet-switching cellular environment

Improved performance is achieved for cellular systems with an arrangement where mobile units transmit information in packet format. A base station routes received packets to switching agents identified by the packets, and the switching agents forward the information contained in the packets to a wired network. The switching agent thus forms the interface between the packet switched portion of the cellular system and the wired network, which may be a circuit switched network. The routing of packets to switching agents allows the system to dedicate one agent to each mobile unit known to the system. It also allows a mobile unit's switching agent to remain wherever it is hosted even when the mobile unit moves from cell to cell, causing different base stations to receive the mobile unit's packets. The routing of packets is achieved with a routing network, which preferably is immune to single failures. In one illustrative embodiment, the routing network comprises a mesh network that interfaces a multiply connected routing network.

Packet switching architecture in cellular radio

The present invention is directed to a method of deterring the illicit copying of electronically published documents. It includes utilizing a computer system to electronically publish a plurality of copies of a document having electronically created material thereon for distribution to a plurality of subscribers and operating programming within the computer system so as to perform the identification code functions. The steps are to encode the plurality of copies each with a separate, unique identification code, the identification code being based on a unique arrangement of the electronically created material on each such copy; and, creating a codebook to correlate each such identification code to a particular subscriber. In some embodiments, decoding methods are included with the encoding capabilities. The unique arrangement of the electronically created material may be based on line-shift coding, word-shift coding, or feature enhancement coding (or combinations of these) and may be effected through bitmap alteration of document format file alteration.

Document copying deterrent method

An improved cellular arrangement is created with mobile units that are responsive to control signals that direct the mobile units to modify the rate of packet transmissions in case of channel overload. A mobile unit in such an arrangement encodes either the speech signal, or only a portion thereof that is sufficient to reproduce a lower fidelity speech which is still intelligible--and at a lower rate. In another embodiment, the mobile unit creates a second stream of packets, also at a lower rate. The second stream complements the first stream of packets in its lower rate form, to allow reproducing the speech signal with high fidelity. Operationally, such a mobile unit is responsive to a base station which, under overload conditions, directs the mobile unit to transmit packets at the lower rate (and the lower fidelity). Optionally, the base station can also directs the mobile unit to send the second stream of packets over a different channel.

A methodology for allocation of transmission capacity in communications networks is provided wherein a collection of constant rate channels is implemented between end points in the network. In that methodology, periodic sources are assigned channels of bandwidth corresponding to the transmission rate for each such source, and bursty sources are assigned to channels providing bandwidth corresponding to a minimum service guarantee for each such bursty source. Channel capacity assigned to periodic services which is not needed by such sources is then made available to bursty sources for accommodating capacity requirements of such bursty sources over and above the minimum service guarantee.

System and method for capacity management in multi-service networks

A method is provided that deters the illicit copying of electronically published documents. It includes publishing a plurality of copies of electronically created material to be distributed to a plurality of subscribers. Each copy of subscriber's document has a unique identification code embedded in the document. The arrangement of the code on the document is based on the line-shifting and word-shifting techniques. This is to minimize the effects from noise and distortions on future illicit copies to simplify detection and decoding of the unique code. A codebook is created to correlate each unique code with each subscriber.

Document copying deterrent method using line and word shift techniques

A method for protecting electronically published documents involves operating a computer system and network for electronic publication of documents, and includes the steps of receiving requests for documents from users having computers with display devices or printers, including with the requests unique user identification for each of the user; authenticating the requests with a copyright server; using the copyright server to direct a document server to act upon proper authentication of each request; using the document server to create uniquely encoded, compressed and encrypted documents for each authenticated request, where the documents have unique encoding corresponding to each of the users, and forwarding the documents to each authenticated request user through the network to corresponding agents of each authenticated request user, with each of the agents being selected from display agents and printer agents; and decrypting and uncompressing the documents at each of the agents and making the documents available for use only in response to receiving correct secret keys provided by the authenticated request user to the agents.

Growing community of inventors

Mountainside, NJ, United States of America

Nicholas Frank Maxemchuk