Abstract: Cryptographically secure data communications between layered groups of devices in a wireless cooperative broadcast network encrypts datagrams twice prior to transmission by a source device, first using an inner layer key that is shared by a first group of devices, and second using an outer layer key that is shared by a second group of devices; the devices of the first group being members of the second group. Received datagrams are recovered by first decrypting with the outer layer key and second decrypting with the inner layer key.

Abstract: A system and method for cryptographically securing data communications between a group of networked devices establishes and maintains an overlay network at the Application Layer, on top of a unicast routing service provided at the Internetworking Layer. The overlay network provides first, the routes that are used to deliver multicast datagrams and second, the cryptographic keys used to secure multicast datagrams. A common cryptographic key is established between all members of each group, and end-to-end encryption ensures that multicast datagrams can be accessed only by authorized group members. In other embodiments, keys are established between pairs of adjacent devices in the overlay network, and hop-by-hop encryption ensures that multicast datagrams can be accessed only by overlay network members.

Abstract: Cryptographically secure data communications between layered groups of devices in a wireless cooperative broadcast network encrypts datagrams twice prior to transmission by a source device, first using an inner layer key that is shared by a first group of devices, and second using an outer layer key that is shared by a second group of devices; the devices of the first group being members of the second group. Received datagrams are recovered by first decrypting with the outer layer key and second decrypting with the inner layer key.

Abstract: A system and method for cryptographically securing data communications between a group of networked devices establishes and maintains an overlay network at the Application Layer, on top of a unicast routing service provided at the Internetworking Layer. The overlay network provides first, the routes that are used to deliver multicast datagrams and second, the cryptographic keys used to secure multicast datagrams. A common cryptographic key is established between all members of each group, and end-to-end encryption ensures that multicast datagrams can be accessed only by authorized group members. In other embodiments, keys are established between pairs of adjacent devices in the overlay network, and hop-by-hop encryption ensures that multicast datagrams can be accessed only by overlay network members.

Abstract: Cryptographically secure data communications between layered groups of devices in a wireless cooperative broadcast network encrypts datagrams twice prior to transmission by a source device, first using an inner layer key that is shared by a first group of devices, and second using an outer layer key that is shared by a second group of devices; the devices of the first group being members of the second group. Received datagrams are recovered by first decrypting with the outer layer key and second decrypting with the inner layer key.

Abstract: Cryptographically secure data communications between layered groups of devices in a wireless cooperative broadcast network encrypts datagrams twice prior to transmission by a source device, first using an inner layer key that is shared by a first group of devices, and second using an outer layer key that is shared by a second group of devices; the devices of the first group being members of the second group. Received datagrams are recovered by first decrypting with the outer layer key and second decrypting with the inner layer key.

Abstract: A system and method for cryptographically securing data communications between a group of networked devices establishes and maintains an overlay network at the Application Layer, on top of a unicast routing service provided at the Internetworking Layer. The overlay network provides first, the routes that are used to deliver multicast datagrams and second, the cryptographic keys used to secure multicast datagrams. A common cryptographic key is established between all members of each group, and end-to-end encryption ensures that multicast datagrams can be accessed only by authorized group members. In other embodiments, keys are established between pairs of adjacent devices in the overlay network, and hop-by-hop encryption ensures that multicast datagrams can be accessed only by overlay network members.

Abstract: Systems and methods are presented for topology discovery in a multi-hop ad hoc network. The method operates on two time and distance scales. Nodes periodically transmit messages to their immediate neighbors that enable the discovery of their two-hop network topologies (i.e., within two hops). Less frequently, nodes broadcast messages network-wide that enable the discovery of the global network topology at all nodes. In multi-hop ad hoc network architectures that are characterized by efficient broadcast protocols—e.g., Barrage Relay Networks—the proposed method provides a particularly efficacious means for global topology discovery.

Abstract: An apparatus for joint analog and digital interference cancellation includes a receiver configured to receive an analog reference interfering signal on a reference path, and a sum of an analog interference signal and an analog signal of interest on an antenna path. An analog interference canceller may be configured to produce an analog partially interference-cancelled signal using the analog reference interfering signal and the sum of the analog interference signal and the analog signal of interest. A first analog-to-digital converter may be configured to digitize the analog reference interfering signal to produce a digital reference interfering signal. A second analog-to-digital converter may be configured to digitize the analog partially interference-cancelled signal to produce a digital partially interference-cancelled signal.

Abstract: Systems and methods are presented for controlling the peak-to-average-power of a baseband orthogonal-frequency-domain multiplexing (OFDM) signal by designating a subset of the available subcarriers as information-bearing data-subcarriers, and loading remaining subcarriers by symbols that are a function of the symbols loading the data-subcarriers. At the receiver, the data-dependent subcarriers are optionally combined with data-subcarriers to increase error protection.

Abstract: An apparatus for joint analog and digital interference cancellation includes a receiver configured to receive an analog reference interfering signal on a reference path, and a sum of an analog interference signal and an analog signal of interest on an antenna path. An analog interference canceller may be configured to produce an analog partially interference-cancelled signal using the analog reference interfering signal and the sum of the analog interference signal and the analog signal of interest. A first analog-to-digital converter may be configured to digitize the analog reference interfering signal to produce a digital reference interfering signal. A second analog-to-digital converter may be configured to digitize the analog partially interference-cancelled signal to produce a digital partially interference-cancelled signal.

Abstract: A method for secure key agreement among a subset of a plurality of transceivers includes generating a first ordered subset of a plurality of keys k?j, where j=0 to S. Each of the subset of the plurality of transceivers may possess at least one of the plurality of keys k?j from the first ordered subset. Each of the subset of the plurality of transceivers possessing one or more keys k?i, i=1 to S, also possesses at least one key from a second ordered subset of the plurality of keys k?j, j=0 to i?1. A key with index ?0 is designated as a group key. A binary sum of the group key k?0 and a key k?j, where j?0, is transmitted from one or more of the subset of the plurality of transceivers that possesses the group key k?0.

Abstract: Systems and methods are presented for establishing network-wide time synchronization in a time-slotted barrage relay network. In the first phase, nodes obtain coarse, slot-level time synchronization by estimating the time-of-arrival (TOA) of a message that rapidly floods the network via the barrage relay mechanism. In the second phase, fine time synchronization is achieved via a messaging protocol that exchanges TOA information between neighboring nodes.

Abstract: A method for secure key agreement among a subset of a plurality of transceivers includes generating a first ordered subset of a plurality of keys k?j, where j=0 to S. Each of the subset of the plurality of transceivers may possess at least one of the plurality of keys k?j from the first ordered subset. Each of the subset of the plurality of transceivers possessing one or more keys k?i, i=1 to S, also possesses at least one key from a second ordered subset of the plurality of keys k?j, j=0 to i?1. A key with index ?0 is designated as a group key. A binary sum of the group key k?0 and a key k?j, where j?0, is transmitted from one or more of the subset of the plurality of transceivers that possesses the group key k?0.

Abstract: A system and method is presented for establishing relayed communications involving (1) sending a request message from a source node to a destination node through a plurality of intermediate nodes, (2) receiving the request message at the destination node, and (3) sending an acceptance message from the destination node to the source node through at least a subset of the intermediate nodes, wherein an intermediate node relays the request or acceptance message by receiving the message and re-transmitting the message, and wherein the intermediate node is capable of receiving the message from more than one other intermediate node.

Abstract: Systems and methods are presented for controlling the peak-to-average-power of a baseband orthogonal-frequency-domain multiplexing (OFDM) signal by designating a subset of the available subcarriers as information-bearing data-subcarriers, and loading remaining subcarriers by symbols that are a function of the symbols loading the data-subcarriers. At the receiver, the data-dependent subcarriers are optionally combined with data-subcarriers to increase error protection.

Abstract: Methods and systems for on-demand adaptation of packet time-to-live in time-slotted barrage relay networks are disclosed. For example, one disclosed method includes: transmitting a first packet from a first node in a wireless ad hoc network to a second node in the wireless ad hoc network; determining a first path distance, in terms of number of hops, from the first node to the second node, based on the first packet transmission; transmitting a second packet from the second node to the first node, wherein the second packet includes content representing the first path distance; and determining a time-to-live value for subsequent transfers from the first node to the second node, by taking into account the first path distance, wherein the time-to-live value limits the number of hops each packet is allowed to take in subsequent transfers from the first node to the second node.

Abstract: Methods for coordinating access to a barrage relay networks are disclosed. For example, one disclosed method includes: receiving, by a first node, a first message from a second node on a network; suppressing transmission of messages by the first node; receiving, by the first node, a second message corresponding to the first message or waiting a sufficient amount of time without receipt of the second message; reactivating transmission of the messages by the first node.

Abstract: A system and method is presented for establishing relayed communications involving (1) sending a request message from a source node to a destination node through a plurality of intermediate nodes, (2) receiving the request message at the destination node, and (3) sending an acceptance message from the destination node to the source node through at least a subset of the intermediate nodes, wherein an intermediate node relays the request or acceptance message by receiving the message and re-transmitting the message, and wherein the intermediate node is capable of receiving the message from more than one other intermediate node.

Abstract: Methods for coordinating access to a barrage relay networks are disclosed. For example, one disclosed method includes: receiving, by a first node, a first message from a second node on a network; suppressing transmission of messages by the first node; receiving, by the first node, a second message corresponding to the first message or waiting a sufficient amount of time without receipt of the second message; reactivating transmission of the messages by the first node.