Abstract: Rate adaptation in a digital wireless communication network is performed by measuring by a wireless node data throughput values attained while communicating at different data rates on a channel in the network. The node calculates from the measured throughput alone a current transmission rate without any a priori knowledge of a state of the channel. The transmission rate calculation involves calculating a ratio of the measured throughput with respect to an exponential weighted moving average of the measured throughput. By repeating the measurements and calculations periodically, the rate used for transmission by the node is adapted automatically.

Abstract: A wireless base station having K antennas communicates with M mobile devices using multiuser diversity scheme with opportunistic interference management. The base station transmits K distinct pilot signals from K corresponding antennas and receives feedback from mobile devices. The feedback from each device indicates a strong pilot signal and a weak pilot signal received from the K distinct pilot signals. Using these indications, the base station assigns each of the K antennas to a mobile device. The base station then transmits distinct data streams to the mobile devices using the corresponding antennas assigned to the corresponding mobile devices. The transmission may include multiplying the transmitted distinct data streams by a vector V orthogonal to a vector U, thereby allowing mobile devices not assigned to an antenna to cancel the transmitted distinct data streams.

Abstract: A method is described for routing network traffic based on distance information to provide multiple paths that need not have equal costs. The routing algorithm MPATH of the present method provide loop-free routing at every instant, without the need of internodal synchronization which spans more than a single hop. Paths are computed using shortest distances and predecessor information in the routing computation. The use of multiple-successors allows for load-balancing within the network. The algorithm is both distributed and scalable to large networks due to its use of only one-hop synchronization. A number of procedures are described by way of example, including path computation, main table updating, neighbor table updating, and a multipath (MPATH) algorithm.

Abstract: A protocol for differentiating congestion-related packet loss versus random packet loss in a wireless data connection. The protocol monitors changes in the length of a transmission queue in a wireless data connection over an interval substantially equal to the amount of time it takes to transmit a window of data packets and receive acknowledgements corresponding to all data packets transmitted in the window. If packet loss is preceded by an increase in the queue length over two consecutive intervals, the packet loss is designated as being due to congestion and a congestion avoidance algorithm is initiated. Otherwise, the packet loss is designated as random loss and the transmission window is maintained at its current size. The protocol reduces the transmission rate only when congestion is identified as the cause of lost packets; otherwise wireless losses can simply be quickly retransmitted without a reduction in the data transmission rate.

Abstract: A protocol for differentiating congestion-related packet loss versus random packet loss in a wireless data connection. The protocol monitors changes in the length of a transmission queue in a wireless data connection over an interval substantially equal to the amount of time it takes to transmit a window of data packets and receive acknowledgements corresponding to all data packets transmitted in the window. If packet loss is preceded by an increase in the queue length over two consecutive intervals, the packet loss is designated as being due to congestion and a congestion avoidance algorithm is initiated. Otherwise, the packet loss is designated as random loss and the transmission window is maintained at its current size. The protocol reduces the transmission rate only when congestion is identified as the cause of lost packets; otherwise wireless losses can simply be quickly retransmitted without a reduction in the data transmission rate.

Abstract: A bandwidth efficient routing protocol for wireless ad-hoc networks. This protocol can be used in ad-hoc networks because it considerably reduces control overhead, thus increasing available bandwidth and conserving power at mobile stations. It also gives very good results in terms of the throughput seen by the user. The protocol is a table-driven distance-vector routing protocol that uses the same constraints used in on-demand routing protocols, i.e., paths are used as long as they are valid and updates are only sent when a path becomes invalid. The paths used by neighbors are maintained and this allows the design of a distance-vector protocol with non-optimum routing and event-driven updates, resulting in reduced control overhead.

Abstract: A family of medium-access (MAC) collision-avoidance receiver-initiated channel-hopping (RICH) protocols which do not rely on carrier-sensing, or unique codes to each node within the network. The RICH protocol requires that each network nodes adhere to a common channel-hopping sequence, and that nodes that are not in a state of sending or receiving data will listen on the common channel hop. To send data nodes enter into a receiver-initiated dialogue over the channel-hop at the time at which a data transmission is needed. Nodes which succeed in performing the collision-avoidance handshake remain in the same channel-hop for the remainder of the data transfer, while the remaining nodes continue with the common channel hopping sequence. The described RICH protocols are capable of providing collision-free operation even in the presence of hidden terminals.

Abstract: Receiver-initiated collision avoidance methods for use in ad-hoc wireless networks in which carrier sensing is available. A number of protocol variants are described including RIMA-SP (simple polling), RIMA-DP (dual-purpose polling), and RIMA-BP (broadcast polling). These handshake methods according to the invention are capable of correctly avoiding collisions within a network that contains hidden nodes, and the RIMA-DP protocol provides higher performance levels than attainable with existing handshaking protocols within the ad-hoc wireless networks. The use of dual-purpose polling allows a control packet to be sent which has alternative functions, such as requesting data from the polled node, if available, and if not available then providing a transmission request from the polling node to send data to the polled node.

Abstract: A protocol to coordinate multipoint groupwork in the IP-multicast framework. Called Aggregated Coordination Protocol (ACP), the protocol operates on a shared multicast tree, benefiting from the underlying tree structure to store and forward coordination primitives between hosts in different multicast groups on the tree. ACP coordinates distributed activities via message passing, and manifests control by ephemeral permissions rather than actual locks, allowing control over continuous media flows as well as discrete data. The protocol supports Internet-wide coordination for large and highly interactive groupwork, relying on transmission of coordination directives between group members across a shared end-to-end multicast tree.

Abstract: A routing methodology for constructing multiple loop-free routes within a network of nodes executing the methodology. The method is capable of generating shortest-distance routing within the network and is not subject to the counting-to-infinity problem to which conventional distance-vector routing protocols are subject. By way of example the method comprises computing link distances Dij to generate routing graph SGj. The nodes exchange distance and status information and upon receiving increasing distance information diffusing computations are performed. The information collected is used to maintain routing tables, from which shortest-path routes may be selected according to loop-free invariant (LFI) conditions.

Abstract: A practical framework and “near-optimal” routing method which approximates minimum delay routing within a network. A framework for approximating Gallager's minimum-delay routing problem (MDRP) is described with methods for implementing the approximation on real networks subject to frequent topology changes and bursty traffic. The computation of minimum-delay paths is divided into two parts, (1) the establishment of multiple loop-free paths of unequal cost to a destination, (2) allocation of flows to minimize delays using short-term link-cost information. The method provides multi-path routing which overcomes the implementation limitations of optimal routing algorithms, such as oscillatory behavior, and the delays associated with shortest-path routing methods, while avoiding undetected loops.

Abstract: A family of medium-access (MAC) collision-avoidance receiver-initiated channel-hopping (RICH) protocols which do not rely on carrier-sensing, or unique codes to each node within the network. The RICH protocol requires that each network nodes adhere to a common channel-hopping sequence, and that nodes that are not in a state of sending or receiving data will listen on the common channel hop. To send data nodes enter into a receiver-initiated dialogue over the channel-hop at the time at which a data transmission is needed. Nodes which succeed in performing the collision-avoidance handshake remain in the same channel-hop for the remainder of the data transfer, while the remaining nodes continue with the common channel hopping sequence. The described RICH protocols are capable of providing collision-free operation even in the presence of hidden terminals.

Abstract: A protocol for differentiating congestion-related packet loss versus random packet loss in a wireless data connection. The protocol monitors changes in the length of a transmission queue in a wireless data connection over an interval substantially equal to the amount of time it takes to transmit a window of data packets and receive acknowledgements corresponding to all data packets transmitted in the window. If packet loss is preceded by an increase in the queue length over two consecutive intervals, the packet loss is designated as being due to congestion and a congestion avoidance algorithm is initiated. Otherwise, the packet loss is designated as random loss and the transmission window is maintained at its current size. The protocol reduces the transmission rate only when congestion is identified as the cause of lost packets; otherwise wireless losses can simply be quickly retransmitted without a reduction in the data transmission rate.

Abstract: A bandwidth efficient routing protocol for wireless ad-hoc networks. This protocol can be used in ad-hoc networks because it considerably reduces control overhead, thus increasing available bandwidth and conserving power at mobile stations. It also gives very good results in terms of the throughput seen by the user. The protocol is a table-driven distance-vector routing protocol that uses the same constraints used in on-demand routing protocols, i.e., paths are used as long as they are valid and updates are only sent when a path becomes invalid. The paths used by neighbors are maintained and this allows the design of a distance-vector protocol with non-optimum routing and event-driven updates, resulting in reduced control overhead.

Abstract: A protocol to coordinate multipoint groupwork in the IP-multicast framework. Called Aggregated Coordination Protocol (ACP), the protocol operates on a shared multicast tree, benefiting from the underlying tree structure to store and forward coordination primitives between hosts in different multicast groups on the tree. ACP coordinates distributed activities via message passing, and manifests control by ephemeral permissions rather than actual locks, allowing control over continuous media flows as well as discrete data. The protocol supports Internet-wide coordination for large and highly interactive groupwork, relying on transmission of coordination directives between group members across a shared end-to-end multicast tree.